14. ASSIGNMENT TOPICS WITH MATERIALSkgr.ac.in/beta/wp-content/uploads/2018/09/Power-Plant... · 2018-10-10 · Draught system in thermal power plant Ans.: The draught is one of the

Saba Sultana Assistant Professor, MECH

14. ASSIGNMENT TOPICS WITH MATERIALS


UNIT-I

1. Steam power plant

Ans: General layout of Steam Power Plant:

Boiler: The mixture of pulverized coal and air (usually preheated air) is taken into boiler and then burnt in the combustion zone. The heat energy is utilized to convert the water into steam at high temperature and pressure. The flue gases from the boiler make their way through superheated, economizer; Air preheated and finally get exhausted to the atmosphere from the chimney.

Superheated: The superheated tubes are hanged at the hottest part of the boiler. The saturated steam produced in the boiler tubes is superheated to about 540 °C in the superheated. The superheated high pressure steam is then fed to the steam turbine.

Economizer: An economizer is essentially a feed water heater which heats the water before supplying to the boiler.

Air pre-heater: The primary air fan takes air from the atmosphere and it is then warmed in the air pre-heater. Pre-heated air is injected with coal in the boiler. The advantage of pre-heating the air is that it improves the coal combustion.

Steam turbine: High pressure super-heated steam is fed to the steam turbine which causes turbine blades to rotate. Energy in the steam is converted into mechanical energy in the steam turbine which acts as the prime mover. Condenser: The exhausted steam is condensed in the condenser by means of cold water circulation. Here, the steam loses its pressure as well as temperature and it is converted back into water. Alternator: The steam turbine is coupled to an alternator. When the turbine rotates the alternator, electrical energy is generated. This generated electrical voltage is then stepped up with the help of a transformer and then transmitted where it is to be utilized. Feed water pump: The condensed water is again fed to the boiler by a feed water pump. Some water may be lost during the cycle, which is suitably supplied from an external water source.

2. Principle of underfeed stoker & overfeed stoker

Ans.: Underfeed stoker firing:


Under stoker firing is the process of combustion in which the new coal is heated by radiation in the presence of air and located under ignited fuel bed. The heating of coal is running less rapidly and release volatile matter combine with air, so generate low Smoke.

Schematic diagram of Overfeed stoker firing. Underfeed stoker firing: Overfeed stoker firing is the process of combustion in which the un-ignited fuel or incoming coal is located above ignited fuel bed. The ignited fuel transfer heat to the incoming coal by radiation. Moreover coal is heated convection from hot gases that has been through the combustion. Secondary air is added to perform complete combustion unless steam boiler will produce more smoke because the hot gases contain little oxygen.

Schematic diagram of Underfeed stoker firing. 3. Pulverized coal firing & its types Ans.:Pulverized Fuel Burning System: There are two common methods of pulverized fuel burning systems- 1. Unit system 2. Central or Bin system 1. Unit System: In this system, each burner and a pulverized constitute a unit. It consists of a raw coal bunker, a feeder, pulverizing mill, separator, and the burner. In operation, the raw coal is supplied to the bunker, where it is crushed to the required sizes; the crushed coal is then fed to the pulverizing mill through the feeder at the required rate, depending upon the


combustion requirements. Hot gases are passed through the feeder to dry the coal. The dried coal is pulverized in the mill and it is carried to the burner. An induced draft fan is used at the pulverized to carry the powdered coal to the burner. A separator is provided to separate the grains of bigger size from the powder and returned to the pulverized for further crushing.

Schematic diagram of Unit system. Advantages: 1. It is simple in operation and economical than the central system. 2. Combustion is controlled directly after pulverize. 3. Maintenance cost is low. 4. Fuel supply to the burner can be controlled easily. Disadvantages 1) The performance of the pulverizing mill is poor as the system operates at variable loads. 2) The total capacity of mills must be higher than the central system. 3) The unit system of fuel burning is less flexible. 4) Whenever any of the auxiliaries fails the burner has to be put-off. 5) Wear and tear of the fan blades is more since it handles hot air and coal particles. 6) Strict maintenance of pulverizing mill is a must for perfect operation of the system. 2) Central or Bin System: The Fig. shows schematic arrangement and the principle of operation of a central, or bin system for burning pulverized coal. The crushed raw coal is dried using hot air or flue gases and fed to the pulverizer. The pulverized coal from the pulverizing mill is passed to the cyclone separator where over-sized particles are separated and fed back to the mill.


Schematic diagram of Central or Bin system. The pulverized coal is then transferred from the separator to the central bunker (bin) through a conveyer system. The pressurized air from the forced draft fan, supplies the stored coal to the burner. This air not only carries the fuel, but also acts as the primary air for the combustion of the fuel. Secondary air is supplied to the burner separately to assist in the complete combustion. Advantages of Central system: 1) Central system is highly flexible and hence can meet any quick changes in the demand. 2) Burner operation is independent of coal pulverization. 3) The pulverizing mill can be stopped when there is a good stock of pulverized fuel in the bin. 4) The fan wear is less as it handles only natural air. 5) Coal size can be controlled efficiently. Disadvantages: 1) Central system is expensive, and occupies more space. 2) It requires complicated coal handling systems. 3) Power consumption in auxiliaries is high. 4) Chances of fire hazards are more since the pulverized fuel is stored. 5) Operation and maintenance costs are high.

4. Draught system in thermal power plant Ans.: The draught is one of the most essential systems of thermal power plant which supplies required quantity of air for combustion and removes the burnt products from the system. To move the air through the fuel bed and to produce a flow of hot gases through the boiler, economizer, pre-heater and chimney require a difference of pressure. www.joshikandarp.webs.com require a difference of pressure. This difference of pressure for to maintaining the constant flow of air and discharging the gases through the chimney to atmosphere is known as draught. Draught can be obtained by use of chimney, fan, steam or air jet or combination of these. When the draught is produced with the help of chimney only, it is known as Natural Draught and when the draught is produced by any other means except chimney it is known as artificial draught. Advantages of mechanical draught over natural draught:

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1. The artificial mechanical draught is better in control and more economical than natural draught. 2. The rate of combustion is high as the available draught is more. The better distribution and mixing of air with fuel is possible therefore the quantity of air required per kg of fuel is less. 3. The air flow can be regulated according to the requirement by changing the draught pressure. 4. The chimney draught is produced at the cost of thermal efficiency of the plant because it is necessary to exhaust the gases at high temperature to produce the draught. In mechanical draught, the exhaust gases can be cooled to lowest possible temperature before exhaust and improves the overall thermal efficiency of the plant. 5. The height of the chimney used in mechanical draught can be reduced sufficiently as the function of the chimney is only to exhaust the gases high in the atmosphere to prevent the contamination. 6. The efficiency of the artificial draught is nearly 7% whereas th e efficiency of the chimney draught is hardly 1%. 7. The fuel consumption per kW due to artificial draught is 15% less than the natural draught. 8. The fuel burning capacity of the grate is 200 to 300 kg/m 2 in area of the grate per hour with mechanical draught whereas it is hardly 50 kg/m 2-hr with natural draught. 9. It prevents the formation of smoke as complete combustion is possible even with less excess air. 5. Feed water treatment Ans:Feed water treatment: The natural water contains solid, liquid & gaseous particles present which may create problems for the steam power plant. Different methods for water treatment to remove the impurities:

a. Internal treatment b. External treatment

a) Internal treatment: If the impurities are removed from the water in the boiler by chemical treatment.

i) Soda ash treatment: It is not applicable for high temperatures&pressures .

ii) Phosphate treatment:

The common phosphates are tri-sodium phosphate, di-sodium phosphate, and mono-sodium phosphate.

iii) Colloidal treatment: Proper colloidal materials are added to the boiler water which are excellent absorbing capacity to form the sledge rapidly onto the surface.

iv) Use of volatile amines: They are mainly used for to reduce (or) control the corrosion of the boiler.

v) Blow-down systems:


Some of the hot water is coming out from the boiler while removing the sludges from the boiler.

b) External treatment: Before supplying to the boiler if the impurities are removed it is called as external treatment.

i) Removal of un-dissolved salts: The un-dissolved salt particles are removed by sedimentation (or) filtration.

ii) Removal of dissolved solid: Hot-lime:

Zeolite process:

c) Removal of dissolved gases:

Generally the water contains oxygen, CO2, other gases in dissolved condition which creates corrosion in the boiler.


UNIT-II 1. Fuel injection system Ans:

Fuel injection system: The mechanical heart of the diesel engine is the fuel injection system. Types of fuel injection system:

i) Common rail system: A single pump supplies high-pressure fuel to header, a relief valve holds pressure constant.

ii) Individual pump injection system: In this system, an individual pump or pump

cylinder connects directly to each fuel nozzle.

iii) Distributor system: In this system, the fuel is metered at a central point , a pump,

pressures, meters the fuel & times the injection.


2. Cooling system in diesel power plant Ans:

Cooling system: If the engines are not properly cooled, the temperature existing inside engines would disintegrate the film of lubricating oil on the livers & wrapping of valves & pistons takes place.

i. Single circuit cooling system: It may be subjected to corrosion in the cylinder jackets because of dissolved gases in the cooling water.

ii. Double circuit cooling system: In double circuit system largely eliminates internal

jacket corrosion but the corrosion may exist in the raw water circuit.

3. Open cycle & closed cycle gas turbine Ans: Open cycle gas turbine: The compressor takes in ambient air& rises its pressure. Heat is added to the air in its temperature. The heated gases coming out of C.C are then passed to the turbine.

Closed cycle gas turbine: In closed cycle gas turbine power plant, the working fluid coming out from compressor is heated in a heater by an external source at constant pressure.


4. MHD generation Ans:

MHD is concerned with the flow of a conducting fluid in the pressure of magnetic field. MHD generator converts heat energy of a fuel directly into electrical energy without a conventional electric generator. Principle of MHD power generation:

move in respect with each other, an electric voltage is induced in the conductor. The MHD generator uses the principle by forcing a high temperature combustion gas through a strong magnetic field. When the gas flows across a magnetic field, a current is induced & a force tending to slow down the gas is experienced. E= V.B E = e.m.f , V = voltage , B = strength of magnetic field at right angles The power out- 2B2.K(1-K)

K Load factor

The load factor (k) =


5. Working principle of Fuel cell Ans::

FUEL CELL:

A fuel cell is an electrochemical device in which the chemical energy of a conventional fuel is converted directly & efficiently into low voltage, direct-current electrical energy.

The fuel cell consists of an anode, a cathode, and an electrolyte. Hydrogen fuel is fed into the anode side of the cell. Positive H2 ions move from the anode side &benter the electrolyte through porous walls. The anode is negative charge. Air is fed into cathode side. O2 ions enter electrolyte leaving the cathode with a positive charge. Advantages:

i) Conversions efficiencies are very high. ii) Require little attention and less maintenance. iii) Fuel cell does not make any noise.

Dis-advantages: i) High initial cost. ii) Low service life.


UNIT-III

1. Hydro-electric power plant Ans:

Hydro-electric power plant: Catchment area: To start any hydroelectric power plant the catchment area is most important to store water & to maintain the head rays in the reservoir (or) otherwise, it is simply the run-off water to the dam (or) reservoir. Damn: It is the main component of hydro-electric power plant & it built the structure for the storage of water. Penstock: It is a long pipe connected between head rays to turbine blade the materials used is steel, plastic. Surge tank: It is the amount of temporary water stored in the surge tank which supplies the water for the peak loads of the power house. Turbine: It is a hydraulic device which is used to convert hydraulic energy into mechanical energy the water having high K.E & P.E energy is directed to flow on the turbine blades. Generator: It is a device which is used to convert mechanical energy & which is coupled to the turbine.

2. Types of measurements Ans: Measurement of rainfall:

There are two types of measurements: i) Non-recording type gauge:

The water from the rainfall is collected before the losses takes place. The depth of the water over the area can be determined to find out the rainfall. The non-recording type consists of funnel which is poured into the receiver. The funnel & the receiver are placed in a metal


casing with suitable packing. The water collected from the rainfall into the receiver through funnel.

ii) Recording type gauge:

A standard funnel is provided on a top of a rectangular box on a floating rod with a pin point draw the graph on rotating drum which is just above the rectangular box. In this method some rain gauges are added & the value of individual gauges is added & the sum of all these values divided by no: of rain gauges. Rainfall=

3. Solar collectors Ans: Solar collectors: A solar collector is a device for collecting solar radiation to transfer the energy to a fluid passing in contact with it. Utilization of solar energy requires solar collectors. These are generally two types:

iii) Non-concentrating type solar collectors: In the non-concentrating type the collected area is the same as the absorber.

iv) Concentrating type solar collectors: In concentrating collectors, the area intercepting the solar radiation is greater, sometimes hundreds of times greater than the absorber area.


Flat plate collector: The flat plate collectors are classified as low temperature collectors because it gives a temperature range of 60-1000C with a collection efficiency of 30-50%.

A flat plate coated with black coke powder is the solar energy absorber and is covered by one (or) more transparent plates of glass. Parabolic concentrator: A simple parabolic concentrator consists of parabolic cylinder, reflector to concentrate sunlight on to a collecting pipe within Pyrex envelope. 4. Hydroelectric power plant Ans:

i) Availability of water flow: a) Run-off River with poundage: These types of run-off river

hydroelectric power plants usually produce the power during peak loads. During the day-time and off-power and the water is stored in large pond. At night-times and during peak load the stored water is used to generate electricity.

b) Run-off River without poundage: In the run-off river type of hydroelectric power plants the running water of the river is used for the generation of electricity. Whenever the water is available the hydroelectric power plant generates electricity and when there is no water no power is generated

c) Reservoir power plants: The reservoir in the hydroelectric power plants has the capacity to store extremely large quantities of water that can be used throughout the whole season.

ii) Availability of water head:


a) Low head: The low head hydroelectric power plants are the ones in which the available water head is less than 30 meters.

b) Medium head: The hydroelectric power plants in which the working head of water is more than 30 meters but less than 300 meters are called medium head hydroelectric power plants.

c) High head: In the high head hydroelectric power plants the head of water available for producing electricity is more than 300 meters and it can extend even up to 1000 meters.

ii) According to the loading types: a) Base load:The base load type of hydroelectric power plants produce

power constantly irrespective of the total load in the national grid. They keep on producing power throughout the day and during all the times of the year. They will stop producing power only during breakdown maintenance.

b) Peak load: Most of the normal power requirements are fulfilled by the base load hydroelectric power plants. However, during night times the requirement of power becomes very high; it is called peak load period.


UNIT-IV

1. Nuclear fuel cycle

Ans: Nuclear fuel: The materials used in nuclear reactors must satisfy the mechanical & metallurgical requirements as adequate strength & corrosion resistance during operation & good ductility & machinability during fabrication. The main fuel materials which are used are natural uranium, enriched uranium, plutonium & U233.Nuclear fuel has the highest energy density of all practical fuel sources.

The nuclear fuel cycle consists of front end steps that prepare uranium for use in nuclear reactors and back end steps to safely manage, prepare, and dispose of highly radioactive spent nuclear fuel.

2. Components of nuclear reactor with its neat sketch Ans:Nuclear reactor: A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an exploitation. The general arrangement of nuclear power plant with essential components using steam as working fluid:

i) Fuel: The nuclear fuels which are generally used in reactors are 92U235, 94Pu 239 and 92U233. Among the three, the 92U235is naturally available up to 0.7% in the uranium ore and the remaining is 92U238.

ii) Moderator: The moderator is a material which reduces the kinetic energy of fast neutron to slow neutron and this is done in a fraction of second.

iii) Reflector: It is always necessary to conserve the neutrons as much as possible in order to reduce the consumption of fissile material and o keep the size of the reactor small.

iv) Coolant: The main purpose of the coolant in the reactor is to transfer the heat produced inside the reactor.

v) Control rods: Some type of control is absolutely necessary to fulfill the function. The control is necessary to prevent the melting of fuel rods, disintegration of coolant and destruction of reactor as the amount of energy released is enormous.

vi) Shielding: The reactor is a source of intense radioactivity and these radiations are very harmful to the human life.


vii) Reactor vessel: The reactor vessel encloses the reactor core, reflector and shield. It also provides the entrance and exit passages for directing the flow of coolant.

3. PWR &BWR

Ans: Pressurized water cooled reactor: Pressurized water reactors (PWRs) constitute the large majority of the world's nuclear power plants. In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator.In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator.

Design: Nuclear fuel in the reactor pressure vessel is engaged in a fission chain reaction, which produces heat, heating the water in the primary coolant loop by thermal conduction through the fuel cladding. The hot primary coolant is pumped into a heat exchanger called the steam generator, where it flows through hundreds or thousands of small tubes. Heat is transferred through the walls of these tubes to the lower pressure secondary coolant located on the sheet side of the exchanger where the coolant evaporates to pressurized steam. The transfer of heat


is accomplished without mixing the two fluids to prevent the secondary coolant from becoming radioactive. Some common steam generator arrangements are u-tubes or single pass heat exchangers. Sodium graphite reactor:

It is one of the typical liquid metal reactors. In this reactor sodium works as a coolant & graphite works as a moderator. Sodium is first melted by electric heating system & be pressured to about 7 bar. The liquid sodium is then circulated by the circulation.

iii) Primary circuit: It has liquid sodium which circulates through the fuel core & gets heated by the fissioning of the fuel. This liquid sodium gets cooled in the intermediate heat exchanger & goes back to the reactor vessel.

iv) The secondary circuit: It has an alloy of sodium & potassium in liquid form. This coolant takes heat from liquid sodium-potassium of primary circuit.

4. Shielding

Ans: Shielding: Shielding is necessary in order to:

i) To protect the walls of the reactor vessel from radiation damage & ii) Protect operating personnel from exposure to radiation.

The radiation from nuclear reactors is extremely varied in character and its ability to -

ra -radiations which penetrate much due to their high energy level & frequency require higher thickness of shielding material.

The main function of lead in nuclear plants is to protect the radioactive materials which are produced in the reactor and to protect the harmful radiations. Lead bricks, core lead pipes, lead wool, lead sheets are some of the radioactive materials which are used in the nuclear plants. Lead shields and the lead foils are the most commonly used radioactive shielding accessories.


Some of the most common lead shielding equipments which are used in the industry are glass plates, glass equipments and lead shielded syringes. Radiation proof shielded doors are used in the X-ray rooms. Lead shielded gloves, curtains aprons, collar are widely used by the medical practitioners who are handling with the radioactive materials. Lead containers are widely used for storing the samples required for the tests and for treating the diseases which make use of radioactive materials. Lead sheets Lead sheets are widely used to weaken certain kinds of radiations due to its high density and atomic number. They are quite effective in stopping the alpha rays, x-rays and the gamma rays. It is more effective than neutron radiation. Lead bricks are used to build shielding walls for temporary or permanent storage locations. The properties of good shielding:

1) -radiations with minimum thickness of shielding material.

2) It must be fire-resistant. 3) It should not be decomposed (or) weaken under the influence of radiation.

5. Nuclear waste disposal system

Ans:Different methods for nuclear waste disposal. i) Disposal of low level solid waste:

The nuclear waste of this category is cast in cement in steel drum. These drums are buried either below the soil(or) kept at the bed of the ocean. The safety of the method lies in the vast dilution of the activity as it disperses at the bottom of the ocean.

ii) Disposal of medium level solid waste:

These wastes are mainly contaminated with neutron activation product isotopes. They are incorporated into cement cylinders as cement is non-combustible and provides shielding against external exposure.

iii) Disposal of high level liquid waste: The remaining liquid is stored on the site in special steel tanks in concrete vaults. They are water cooled and then taken to the storage area.


UNIT-V

1. Capital cost Ans: Capital cost:

It includes the following:

i) Initial cost. ii) Interest iii) Depreciation cost iv) Taxes v) Insurance.

i) Initial cost: Some of the several factors on which cost of a generating station or a power plant depends are:- a) Location of the plant. b) Time of construction. c) Size of units. d) No: of main generating units. e) The type of generating units.

The initial cost of a power station includes the following:-

a) Land cost b) Building cost c) Equipment cost d) Installation cost e) Overhead charges which will include the transportation cost, stores & storekeeping

charges, interest during construction etc. ii) Interest: It is the difference between money borrowed & money returned. iii) Depreciation: It accounts for the deterioration of the equipment & decrease in its

value to corrosion, weathering & wear & tear with use. i. Straight line method: It is the simplest method & commonly used.

The life of the equipment or the enterprise is first assessed as also the residual (or) salvage value of the same after the estimated life span.

ii. Percentage method: In this method the deterioration in value of equipment from year to year is taken into account & the amount of depreciation calculated upon residual value for each year.

iii. Sinking fund method: This method is based on the conception that the annual uniform deduction from income for depreciation will accumulate to capital value of the plant.

iv. Unit method: In this method some factor is taken as a standard one & depreciation is measured by that standard.


2. Operating cost Ans:

Operating charges: The elements that make up the operating expenditure of a power plant include the following costs: (a) Cost of fuels. (b) Labour cost. (c) Cost of maintenance and repairs. (d) Cost of stores (other than fuel). (e) Supervision. (f) Taxes. Cost of Fuels: In a thermal station fuel is the heaviest item of operating cost. The selection of the fuel and the maximum economy in it use are, therefore, very important considerations in thermal plant design. It is desirable to achieve the highest thermal efficiency for the plant so that fuel charges are reduced. The cost of fuel includes not only its price at the site of purchase but its transportation and handling costs also. In the hydro plants the absence of fuel factor in cost is responsible for lowering the operating cost. Plant heat rate can be improved by the use of better quality of fuel or by employing better thermodynamic conditions in the plant design. The cost of fuel varies with the following : (a) Unit price of the fuel. (b) Amount of energy produced. (c) Efficiency of the plant. Labour Cost: For plant operation labour cost is another item of operating cost. Maximum labour is needed in a thermal power plant using coal as a fuel. A hydraulic power plant or a diesel power plant of equal capacity require a lesser number of persons. In case of automatic power station the cost of labour is reduced to a great extent. However, labour cost cannot be completely eliminated even with fully automatic station as they will still require some manpower for periodic inspection, etc. Cost of Maintenance and Repairs: In order to avoid plant breakdowns maintenance is necessary. Maintenance includes periodic cleaning, greasing, adjustments and overhauling of equipment. The material used for maintenance is also charged under this head. Sometimes an arbitrary percentage is assumed as maintenance cost. A good plan of maintenance would keep the sets in dependable condition and avoid the necessity of too many stand-by plants. Repairs are necessitated when the plant breaks down or stops due to faults developing in the mechanism. The repairs may be minor, major or periodic overhauls and are charged to the depreciation fund of the equipment. This item of cost is higher for thermal plants than for hydro-plants due to complex nature of principal equipment and auxiliaries in the former. Cost of Stores (Other Than Fuel): The items of consumable stores other than fuel include such articles as lubricating oil and greases, cotton waste, small tools, chemicals, paints and such other things. The incidence of this cost is also higher in thermal stations than in hydro-electric power stations. Supervisions: In this head the salary of supervising staff is included. A good supervision is reflected in lesser breakdowns and extended plant life. The supervising staff includes the station superintendent, chief engineer, chemist, engineers, supervisors, stores incharges, purchase officer and other establishment. Again, thermal stations, particularly coal fed, have a greater incidence of this cost than the hydro-electric power stations.


Taxes The taxes under operating head includes the following: (a) Income tax (b) Sales tax

3. Load curve and its significance Ans: Load Curve: A load curve (or load graph) is a graphic record showing the power demands for every instant during a certain time interval. Such a record may cover 1 hour, in which case it would be an hourly load graph; 24 hours, in which case it would be a daily load graph; a month in which case it would be a monthly load graph; or a year (7860 hours), in which case it would be a yearly load graph. Significance of Load Curves

c) Load curves give full information about the incoming and help to decide the installed capacity of the power station and to decide the economical sizes of various generating units.

d) These curves also help to estimate the generating cost and to decide the operating

schedule of the power station, i.e. the sequence in which different units should be run.

4. Power plant Ans:

Effluents from power plant Fossil fuel-fired and biomass-fired plants burn fuels to make either hot air or steam needed to spin power turbines generating electricity. Nuclear power plants use the nuclear fission reaction to create steam to do the same. The burning of fuel creates exhaust gases and other by-products, including air pollutants. The use of water to make steam requires large quantities of water from nearby rivers or lakes, or from local underground water aquifers, and it must be purified. In some cases, water must be discharged from the plant after it has been

concentration of pollutants in the water are all factors to be considered. A variety of solid wastes can be produced, and these must be handled. The combustion of coal creates ash as a


solid waste. Nuclear power plants create spent nuclear fuel rods and low-level radioactive wastes. Power plants that use water to create steam or for cooling must often filter and purify the water before discharging to surface waters. The filtered solids are a by-product that must be disposed appropriately. The water used for cooling is often run through cooling towers to

the atmosphere carrying great quantities of water as vapor, in some cases millions of gallons per day. That lost water vapor, obtained locally, represents significant water consumption by the power plant. Some aspects of the construction and operation of a power plant can have unsettling effects on the community in which the power plant is built. Construction of the power plant, while very organized, can be viewed by surrounding landowners and other citizens as ugly and chaotic and might have an effect on community aesthetics or business. Costs for community services such as police, fire protection, emergency medical service, and traffic control can increase. Additional requirements might be placed on the municipal water supply or wastewater treatment capacity, or on solid-waste management systems. Coal-fired power plants require an efficient, reliable and longterm means of coal delivery, usually by rail or barge. Nearby road or rail traffic might be complicated or burdened by construction traffic and the delivery of materials, particularly large items. Noise levels in neighborhoods might increase during construction, and power plant operation also creates noise and vibration. The cooling towers of an operating power plant can also create fog and rime ice. Air space issues and compatibility with local land use must be considered in light of the space the power plant occupies and the way it operates.

5. Pollutant and its standards Ans:

Pollutant: A pollutant is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with human amenities, comfort, health, or property values. Pollutant standard: The Pollutant Standards Index, or PSI, is a type of air quality index, which is a number used to indicate the level of pollutants in air.

Pollutants: Coal combustion releases nitrogen oxides, sulfur dioxide, particulate matter (PM), mercury, and dozens of other substances known to be hazardous to human health.[1]

Aging coal plants "grandfathered" in after passage of the Clean Air Act have been particularly linked to large quantities of harmful emissions.[4][5]

Such emissions include: Nitrogen oxides (NOx): The release of oxides of nitrogen (nitrogen oxides and nitrogen dioxides [NO2]) reacts with volatile organic compounds in the presence of sunlight to produce ground-level ozone, the primary ingredient in smog. Nitrogen oxide also contributes to fine particulate matter, or soot. Both smog and soot are linked to a host of serious health effects. Nitrogen oxide also harms the environment, contributing to acidification of lakes and streams (acid rain).[6] Sulfur dioxide (SO2). Sulfur dioxide contributes to the formation of microscopic particles (particulate pollution or soot) that can be inhaled deep into the lungs and aggravate


respiratory conditions such as asthma and chronic bronchitis, increasing cough and mucous secretion.[6]

Mercury (HG). Coal contains trace amounts of mercury that, when burned, enter the environment and human bodies, effecting intellectual development.[6]

Particulate matter (PM), also known as particle pollution, includes the tiny particles of fly ash and dust that are expelled from coal-burning power plants. Fine particles are a mixture of a variety of different compounds and pollutants that originate primarily from combustion sources such as power plants, but also diesel trucks and buses, cars, etc. Fine particles are either emitted directly from these combustion sources or are formed in the atmosphere through complex oxidation reactions involving gases, such as sulfur dioxide (SO2) or nitrogen oxides (NOX). Among particles, fine particles are of particular concern because they are so tiny that they can be inhaled deeply, thus evading the human lungs' natural defenses.[7]

Smog is the chemical reaction of sunlight, nitrogen oxides (NOx), and volatile organic compounds (VOCs) in the atmosphere, which leaves airborne particles (particulate matter) and ground-level ozone (smog). Ground level ozone is an invisible gas made of three oxygen atoms (O3).

Black carbon, also called soot, arises from sources such as diesel engine exhaust, burning biomass, cooking fires, and coal plants. It is made up of tiny carbon particulate matter that contributes to global warming by absorbing heat in the atmosphere and reducing albedo, the reflection of sunlight, when deposited on snow and ice. It is also a big component of air pollution around the world.


15. TUTORIAL TOPICS AND QUESTIONS: NIL


16. UNIT-WISE QUESTION BANK


UNIT-I

Two Marks Questions with Answers

1. What are the constituents of coal?

Ans.: The constituents of coal are: Carbon 42.9% Hydrogen 2.96% Nitrogen 0.91% Sulphur 0.33%

2. What are the sources through which energy is extracted?

Ans.: The sources of energy which energy is extracted are: Fuels ( Solids, Liquid & Gases) Energy stored in water (Hydro power) Nuclear energy(Atoms) Wind energy( Air) Solar energy(Sun) Tidal energy(Waves) Geothermal energy(Rocks) Thermo-electric power( 2 dis-similar conductors)

3. What are the properties of a coal?

Ans.: The properties of a coal are: Sulphur content. Burning characteristics. Grindability. Ash softening temperature. Weatherability.

4. What is draught system? Name type of draught systems?

Ans.:Most boilers now depend on mechanical draught equipment rather than natural draught. This is because natural draught is subject to outside air conditions and temperature of flue gases leaving the furnace, as well as the chimney height. All these factors make proper draught hard to attain and therefore make mechanical draught equipment much more economical.


Types :-

i. Induced draught

ii. Balanced draught

iii. Forced draught

.

5. List out the names of the power plants which produce electricity?

Ans.: The power plants which produces electricity are: Steam power plant. Diesel power plant. Hydro-electric power plant. Nuclear power plant. Gas turbine plant. Conventional (or) Direct energy conversions


Three Marks Questions with Answers

1. Write short notes on cooling towers?

Ans.:.Cooling towers are heat removal devices used to transfer process waste heat to the

atmosphere. Cooling towers may either use the evaporation of water to remove process heat

and cool the working fluid to near the wet-bulb air temperature or in the case of "Close

Circuit Dry Cooling Towers" rely solely on air to cool the working fluid to near the dry-bulb

air temperature. Common applications include cooling the circulating water used in oil

refineries, chemical plants, power stations and building cooling.

2. What are the types of coal?

Ans:There are six main types of coal that are regularly used:

i. Peat ii. Lignite

iii. Bituminous/Sub Bituminous Coal iv. Anthracite v. Steam Coal

vi. Graphite

3. What is the necessity of feed water treatment?

Ans:Raw water contains a variety of impurities.

For the removal of above impurities feed water treatment is necessary.

4. Write a short notes on Dust collection and it's deposit?

Ans:DUST COLLECTION AND DISPOSAL - In coal fed furnaces the products of combustion contain particles of solid matter floating in suspension. This may be smoke or dust. The production of smoke indicates that combustion conditions are faulty and amount of


smoke produced can be reduced by improving the furnace design. Smoke is produced due to the incomplete combustion of fuels, smoke particles are less than 10µ in size.

The disposal of smoke to the atmosphere is not desirable due to the following reasons:

i) A smoky atmosphere is less healthful than smoke free air.

ii) Smoke is produced due to incomplete combustion of coal. This will create a big economic

loss due to loss of heating value of coal.

iii) In a smoky atmosphere lower standards of cleanliness are prevalent. Buildings, clothings,

furniture, etc., becomes dirty due to smoke. Smoke corrodes the metals ' darkens the paints

5. What are stokers?

Ans.:A mechanical stoker is a device which feeds coal into the firebox of a boiler. It is standard equipment on large stationary boilers and was also fitted to large steam locomotives to ease the burden of the fireman. The locomotive type has a screw conveyor (driven by an auxiliary steam engine) which feeds the coal into the firebox. The coal is then distributed across the grate by steam jets, controlled by the fireman. Power stations usually use pulverized coal-fired boilers.


Five Marks Questions with Answers

1. Write short notes on ash handling equipments?

Ans.:There are three types of ash handling systems. They are a) Hydraulic system b) Pneumatic system c) Mechanical system

a)Hydraulic system: i)Low pressure system:

ii) High pressure system:

b) Pneumatic system


c) Mechanical system

2. Explain the construction & operation of the cyclone furnace?

Ans: Construction: A cyclone furnace consists of a horizontal cylindrical barrel attached through the side of a boiler furnace. The cyclone barrel is constructed with water cooled, tangential oriented, tube construction. Inside the cyclone barrel are short, densely spaced, pin studs welded to the outside of the tubes. The studs are coated with a refractory material, usually silica or aluminum based, that allows the cyclone to operate at a high enough temperature to keep the slag in a molten state and allow removal through the tap. Operation:

Crushed coal and a small amount of primary air enter from the front of the cyclone into the burner. In the main cyclone burner, secondary air is introduced tangentially, causing a circulating gas flow pattern. The products, flue gas and un-combusted fuel, then leave the burner and pass over the boiler tubes. Tertiary air is then released further downstream to complete combustion of the remaining fuel, greatly reducing NO x formation. A layer of molten slag coats the burner and flows through traps at the bottom of the burners, reducing the amount of slag that would otherwise form on the boiler tubes.Cyclone Furnaces can handle a wide range of fuels. Low volatile bituminous coals, lignite coal, mineral rich anthracitic coal, wood chips, petroleum coke, and old tires can and have all been used in cyclones.

3. Explain the types of feed water treatment? A) Ans.:Feed water treatment:

The natural water contains solid, liquid & gaseous particles present which may create problems for the steam power plant. Different methods for water treatment to remove the impurities:

c. Internal treatment d. External treatment

d) Internal treatment: If the impurities are removed from the water in the boiler by chemical treatment.

vi) Soda ash treatment: It is not applicable for high temperatures&pressures .


vii) Phosphate treatment:

The common phosphates are tri-sodium phosphate, di-sodium phosphate, and mono-sodium phosphate.

viii) Colloidal treatment: Proper colloidal materials are added to the boiler water which are excellent absorbing capacity to form the sledge rapidly onto the surface.

ix) Use of volatile amines: They are mainly used for to reduce (or) control the corrosion of the boiler.

x) Blow-down systems: Some of the hot water is coming out from the boiler while removing the sledges from the boiler.

e) External treatment: Before supplying to the boiler if the impurities are removed it is called as external treatment.

iii) Removal of un-dissolved salts: The un-dissolved salt particles are removed by sedimentation (or) filtration.

iv) Removal of dissolved solid: Hot-lime:

Zeolite process:


f) Removal of dissolved gases:

Generally the water contains oxygen, CO2, other gases in dissolved condition which creates corrosion in the boiler.

4. Explain the significance of cooling tower? Ans.:Cooling Tower: A cooling tower is a heat rejection device that rejects waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature. A cooling tower water treatment is the process which ejects the waste heats to the environment through the cooling of a water stream to redeemed temperature. The method which is used to eliminate the waste heat is the evaporation of water through the heat and cooling process. The cooling water tower is depended on air to cool for the working of the process. The cooling tower used for water treatment may vary in size from small rooftop to larger units like hyperboloid structures.

Applications of cooling towers: Common applications include cooling the circulating water used in oil refineries, petrochemical and other chemical plants, thermal power stations and HVAC systems for cooling buildings.

5. What do you mean by pulverized coal firing? Explain its types? Ans.:Pulverized Fuel Burning System: There are two common methods of pulverized fuel burning systems- 1. Unit system 2. Central or Bin system 1. Unit System: In this system, each burner and apulverize constitute a unit. It consists of a raw coal bunker, a feeder, pulverizing mill, separator, and the burner. In operation, the raw coal is supplied to the bunker, where it is crushed to the required sizes; the crushed coal is then fed to the pulverizing mill through the feeder at the required rate, depending upon the combustion requirements. Hot gases are passed through the feeder to dry the coal. The dried coal is pulverized in the mill and it is carried to the burner. An induced draft fan is used at the pulverize to carry the powdered coal to the burner. A separator is provided to separate the grains of bigger size from the powder and returned to the pulverize for further crushing.


Advantages 1. It is simple in operation and economical than the central system. 2. Combustion is controlled directly after pulveriser. 3. Maintenance cost is low. 4. Fuel supply to the burner can be controlled easily. Disadvantages 1) The performance of the pulverizing mill is poor as the system operates at variable loads. 2) The total capacity of mills must be higher than the central system. 3) The unit system of fuel burning is less flexible. 4) Whenever any of the auxiliaries fails the burner has to be put-off. 5) Wear and tear of the fan blades is more since it handles hot air and coal particles. 6) Strict maintenance of pulverizing mill is a must for perfect operation of the system. 2) Central or Bin System: The Fig. shows schematic arrangement and the principle of operation of a central, or bin system for burning pulverised coal. The crushed raw coal is dried using hot air or flue gases and fed to the pulveriser. The pulverised coal from the pulverizing mill is passed to the cyclone separator where over-sized particles are separated and fed back to the mill.

The pulverised coal is then transferred from the separator to the central bunker (bin) through a conveyer system. The pressurized air from the forced draft fan, supplies the stored coal to the burner. This air not only carries the fuel, but also acts as the primary air for the combustion of the fuel. Secondary air is supplied to the burner separately to assist in the complete combustion. Advantages of Central system: 1) Central system is highly flexible and hence can meet any quick changes in the demand. 2) Burner operation is independent of coal pulverization. 3) The pulverizing mill can be stopped when there is a good stock of pulverised fuel in the bin. 4) The fan wear is less as it handles only natural air. 5) Coal size can be controlled efficiently. Disadvantages: 1) Central system is expensive, and occupies more space. 2) It requires complicated coal handling systems.


3) Power consumption in auxiliaries is high. 4) Chances of fire hazards are more since the pulverized fuel is stored. 5) Operation and maintenance costs are high.

6. What is the importance of draught system in thermal power plant?

Ans:The draught is one of the most essential systems of thermal power plant which supplies required quantity of air for combustion and removes the burnt products from the system. To move the air through the fuel bed and to produce a flow of hot gases through the boiler, economizer, pre-heater and chimney require a difference of pressure. www.joshikandarp.webs.com require a difference of pressure. This difference of pressure for to maintaining the constant flow of air and discharging the gases through the chimney to atmosphere is known as draught. Draught can be obtained by use of chimney, fan, steam or air jet or combination of these. When the draught is produced with the help of chimney only, it is known as Natural Draught and when the draught is produced by any other means except chimney it is known as artificial draught. Advantages of mechanical draught over natural draught: 1. The artificial mechanical draught is better in control and more economical than natural draught. 2. The rate of combustion is high as the available draught is more. The better distribution and mixing of air with fuel is possible therefore the quantity of air required per kg of fuel is less. 3. The air flow can be regulated according to the requirement by changing the draught pressure. 4. The chimney draught is produced at the cost of thermal efficiency of the plant because it is necessary to exhaust the gases at high temperature to produce the draught. In mechanical draught, the exhaust gases can be cooled to lowest possible temperature before exhaust and improves the overall thermal efficiency of the plant. 5. The height of the chimney used in mechanical draught can be reduced sufficiently as the function of the chimney is only to exhaust the gases high in the atmosphere to prevent the contamination. 6. The efficiency of the artificial draught is nearly 7% whereas th e efficiency of the chimney draught is hardly 1%. 7. The fuel consumption per kW due to artificial draught is 15% less than the natural draught. 8. The fuel burning capacity of the grate is 200 to 300 kg/m 2 in area of the grate per hour with mechanical draught whereas it is hardly 50 kg/m 2-hr with natural draught. 9. It prevents the formation of smoke as complete combustion is possible even with less excess air.

http://www.joshikandarp.webs.com


Multiple Choice Questions with Answers

1. The flue gases contain various [ ] a) gases b) ash c) gases and ashes d) none

2. In order to balance the boiler in a large power station ___are used [ ]

a) both fans b) both coolents c) one fan d) air

3. Which one is a property of coal relevant to thermal power plant [ ]

a) low ash content b) high calorific value c) high grinding index d) all the above

4. Which of the following process involve coal oil mixture [ ] a) grinding of coal b) mixing of coal with oil c) none d) both a and b

5. Photo voltaic come under [ ]

a) wind b) solar heat c) hydro d) thermal gradient

6. In last 10 years the development of power in the country is seen due to the setup of

_____super thermal pit head stations of nearly ____mw capacity [ ] a) 5 , 2000 b) 6 , 3000 c) 2 , 9000 d) 4 , 3000

7. Which of them are principles of site selection of a steam power station [ ] a) cost of land b) public problem c) future extensition d) all the above e)

8. Which of the statement is true


i. boiler ,super heater , reheater are used in steam power plant.

ii. boiler ,super heater , reheater are not used in steam power plant.

iii. steam turbine , economiser are used in steam power plant.

[ ]

a) i and ii b) i and iii c) ii and iii d) none

9. Which is not a solid fuel [ ]

a) coal b) coke c) mercury d) peat

10. Which of them is not a coal handeling equipments [ ]

a) belt conveyor b) trolly conveyor c) bucket elevstor d) grsb bucket conveyor

Answer:1.c 2. a 3.d 4. D 5. B 6.A7. D8. B9. C10. b


Fill in the Blanks with Answers

1. Fossil fuels, hydropower and nuclear energy are generally termed

2. 3. 4. The coal which 5. 6. 7.

capacity is large. 8.

fired directly in to the furnace. 9. The pressure at the furnace is minimum in draught system. 10. t will be

removed by the collector

Answer:1. Commercial 2.Chandrapur 3.Carbon, hydrogen & Sulphur 4.Caking coals 5.Iron particles 6. Cyclone 7.Overfeed 8. Unit 9.Balanced 10.Absolute efficiency


UNIT-II


1. Write the dis-advantages of over cooling of the engine? Ans: i)Engine starting is difficult, ii) Over-cooling reduces the overall efficiency of the system. iii)At low temperatures, corrosion assumes considerable magnitude that it may reduce the life of various components. 2. List the various Liquid Cooling Systems? Ans:In liquid cooling following methods are used for circulating the water around the cylinder and cylinder head:

(i) Thermo-system cooling

(ii) Forced or pump cooling

(iii) Cooling with thermostatic regulator

(iv) Pressurized cooling

(v) Evaporative cooling. 3. What is the purpose of super charging? Ans:The purpose of supercharging is to raise the volumetric efficiency above that value which can be obtained by normal aspiration. 4. Define Flywheel? Ans.:It is a heavy wheel mounted on the crankshaft. It stores the excess energy delivered by the engine during power stroke and supplies the energy needed during other strokes. Thus it keeps the fluctuations in the crankshaft speed within desired limits . 5. Define open cycle gas turbine? Ans.:In the open cycle gas turbine, air is drawn into the compressor from atmosphere and is compressed. The compressed air is heated by directly burning the fuel in the air at constant pressure in the combustion chamber. Then the high pressure hot gases expand in the turbine and mechanical power is developed. 6. List out the direct energy conversion systems? Ans.: There some of the direct energy conversion types are: 1) fuel cells 2) Solar energy 3) Thermo-electric 4) Thermo-ionic 5) MHD generator



1. Classify the gas turbines? Write the major field of application of gas turbines?

Ans: The gas turbines are mainly divided into two groups: Constant pressure combustion gas turbine:

a) Open cycle gas turbine. b) Closed cycle gas turbine.

The major fields of application of gas turbines are: i)Aviation. ii)Power generation. iii)Oil and gas industry. iv)Marine propulsion. 2. Write the few fuels for Gas turbine and why these fuels are used for gas turbine.

Ans: Natural gas, blast furnace gas, produce gas, coal gas and solid fuels distillate oils and used in gas turbine and methane, ethane, propane, octane. Important

properties to be considered while selecting the fuel for gas turbine are as follows:

i) Volatility. ii) Combustion products iii)Energy contents iv)Lubricating properties v) Availability. 3. Define open cycle gas turbine? What are the methods to improving the thermal

efficiency in open cycle gas turbine plant? Ans:In the open cycle gas turbine, air is drawn into the compressor from atmosphere and is compressed. The compressed air is heated by directly burning the fuel in the air at constant pressure in the combustion chamber. Then the high pressure hot gases expand in the turbine and mechanical power is developed. Methods to improving the thermal efficiency in open cycle gas turbine plant:

i) Inter-cooling ii) Reheating. iii) Regenerating.

4. What is the function of Lubrication system?

Ans:a) To reduce the wear & tear between the mating parts and thereby increase the life of engine. b)The lubricating oil acts as a seal, i.e., it prevents the high pressure gases in the combustion chamber from entering the crankcase. c) To cool the surfaces. 5. Explain the working principle of fuel cell?

Ans:FUEL CELL: A fuel cell is an electrochemical device in which the chemical energy of a conventional fuel is converted directly & efficiently into low voltage, direct-current electrical energy.


The fuel cell consists of an anode, a cathode, and an electrolyte. Hydrogen fuel is fed into the anode side of the cell. Positive H2 ions move from the anode side &benter the electrolyte through porous walls. The anode is negative charge. Air is fed into cathode side. O2 ions enter electrolyte leaving the cathode with a positive charge.



1. Explain the general layout of Diesel engine? Write its advantages & dis-

advantages?

A) Ans: Diesel engine:

The essential components of diesel electric plants: Engine: This is the main component of the plant which develops required power. The

engine is generally directly coupled to the generator. Air-filter & supercharger: The function of the air-filter is to remove the dust from the

air which is taken by the engine. The function of supercharger is to increase the pressure of the air system supplied to the engine to increase the power of the engine.

Exhaust system: This includes the silencers & connected ducts. The temperature of the exhaust gases is sufficiently high, therefore the heat of the exhaust gases many times is used for heating the oil supplied to the engine.

Fuel system: It includes the storage tank, fuel pump, strainers & heaters. Cooling system: This system includes water circulating pumps, cooling towers (or)

spray ponds & water filtration plant. Lubricating system: It includes oil pumps, oil tanks, filters, coolers & connecting

pipes. Starting system: The function of this system is to start the engine from cold by

supplying the compressed air. Governing system: The function of the governing system is to maintain the speed of

the engine constant. Advantages: - Both of design and layout of the plant are quite simple. - Occupies less space as the number and size of the auxiliaries is small. - Can be located at any place. - Can be started quickly and can pick up load in a short time. - No standby losses. - Requires less quantity of water for cooling. - Overall cost is much less than that of steam power station of same capacity. - Thermal efficiency of the plant is higher than that of a steam power station. -Requires less operating staff. Disadvantages: - High running charges as the fuel (diesel) used is costly.


- Does not work satisfactorily under overload conditions for a long period. - Generates small amount of power. - Cost of lubrication is high. - Maintenance charges are high

2. Explain different types of Fuel supply system?

A) Ans: Fuel injection system: The mechanical heart of the diesel engine is the fuel injection system. Types of fuel injection system:

iv) Common rail system: A single pump supplies high-pressure fuel to header, a relief valve holds pressure constant.

v) Individual pump injection system: In this system, an individual pump or pump

cylinder connects directly to each fuel nozzle.

vi) Distributor system: In this system, the fuel is metered at a central point , a pump,

pressures, meters the fuel & times the injection.


3. Explain open cycle & closed cycle gas turbine?

Ans: Open cycle gas turbine: The compressor takes in ambient air& rises its pressure. Heat is added to the air in its temperature. The heated gases coming out of C.C are then passed to the turbine.

Closed cycle gas turbine: In closed cycle gas turbine power plant, the working fluid coming out from compressor is heated in a heater by an external source at constant pressure.


4. Explain the combine cycle power plant?

Ans: Arrangements of Combined cycle: 1) The heat in the exhaust can be used by using one of the arrangements of combined

cycle. The heat in the exhaust gases of a simple gas turbine plant can be used to generate steam in waste heat boiler & the generated steam is used in the steam turbine for power generation.

2) In this cogeneration is most economically used in process industries such as chemical,

steel, paper & petroleum refining.


5. Explain about MHD generation?

Ans: MHD is concerned with the flow of a conducting fluid in the pressure of magnetic field. MHD generator converts heat energy of a fuel directly into electrical energy without a conventional electric generator. Principle of MHD power generation:

ion states that when a conductor & a magnetic field move in respect with each other, an electric voltage is induced in the conductor. The MHD generator uses the principle by forcing a high temperature combustion gas through a strong magnetic field. When the gas flows across a magnetic field, a current is induced & a force tending to slow down the gas is experienced. E= V.B E = e.m.f V = Voltage B = strength of magnetic field at right angles The power out-put per unit volume.

2 B2.K (1-K)

K Load factor

The load factor (k) =



1. Compression ratio of petrol is _____ [ ]

A) 7:1

B) 16:1

C) 1:16

D) 9:1

2. Most of the high speed diesel engine works on ___ [ ]

A) Diesel cycle

B) Otto cycle

C) Carnot cycle

D) Duel combustion cycle

3. Which of the following is the type of fuel supply system [ ]

A) Common rail injection

B) Individual pump injection

C) Distributor system

D) All the above

4. The cetane number of diesel fuels are in the range of [ ]

A) 10-200

B) 30-60

C) 20-400

D) 60-80

5. Most commonly used to lubrication system is ____ [ ]

A) Gravity system

B) Mechanical system

C) Pressure system

D) None

6. The mechanical efficiency _____ due to super charging [ ]

A) Increases

B) Decreases

C) remains un-effected

D) None


7. A gas turbines work on the____ thermodynamic cycle [ ]

A) joules cycle or Brayton

B) Atkinson cycle

C) Rankine cycle

D) Ericson cycle

8. The pressure ratio of open cycle gas turbine is of the order____ [ ]

A) 12:1

B) 18:1

C) 6:1

D) 9:1

9. Solar cells are made up of____ materials [ ]

A) Semi conductor

B) Conductor

C) Insulator

D) None

10. Thermo-electric energy conversion is due to [ ]

A) Emission effect

B) Radiation

C) Thermal energy

D) None

Answer: 1.A 2. D 3. D 4. B 5. C 6. A 7. A 8. C 9. A 10. C



1.

3. In SI

-fuel

mixture.

.

circulation of water.

speed of the cylinder as constant.

9. High thermal efficiency in

cycle gas turbine.

is used for converting chemical energy into electricity

17. In thermo-

18.

MHD generator

Answer:

1. 30-40 kg f/cm2 2. Greater 3. Carburetor 4. Otto cycle 5. Detonation 6. 0.21Mpa-0.42Mpa

7. Thermosyphon8. Supercharging 9. Closed cycle 10. Brayton cycle or joule cycle

11. High nickel alloy12. Higher13. Fuel cell14. Silicon15. DC16. See-beck

17. Electrons18. Increases.


UNIT-III


1. Define Surge tank? What is the use of surge tank?

Ans: Surge tank is a small reservoir or tank in which the water level rises or falls to reduce the pressure swings so that they are not transmitted in full to a closed circuit. The surge tank is used to provide better regulation of water pressure in the system. The surge tank controls the water when the load on the turbine decreases and supplies water when the load on the turbine increases. Thus, surge tank controls the pressure variations resulting from the rapid changes in water flow in penstock and hence prevents water hammer.

2. Write the purpose of Draft tube?

Ans.:A draft tube serves the following two purposes: i) It allows the turbine to be set above tail-water level, without loss of head, to

facilitate inspection and maintenance. ii) It regains, by diffuser action, the major portion of the kinetic energy delivered to it

from the runner.

3. What is the main purpose of reservoir? Ans: The main purpose of reservoir is to store water received from catchments areas duringthe rainy seasons and supply the same during the dry season. 4. Why trash rack is used?

Ans: The trash rack is used to prevent the entry of debris, which might damage the turbine runners and chock up the nozzle of impulse turbine. 5. Define water turbine? Ans: Water turbine is a prime mover used for the alternator at the hydro electric power plant which changes the direction of the flowing water and converts the same to useful mechanical energy and also gives mechanical energy to the alternator. 6. Define hydrology? Ans: The science which deals with rainfall and run-off is call as hydrology.



1. Explain hydrological cycle?

Ans. Hydrological cycle:

Rainfall gives the information about the quantity of waterfall on the earth during raining it is also called as Precipitation.

Runoff = Rainfall Losses. The evaporation of the water from the surfaces of river & oceans & its precipitation on the earth is known as hydrological cycle. Water is evaporated from rivers, oceans and carried with air in the forms of vapor which is known as clouds. When the vapor in the atmosphere clouds cools below the dew point temperature, it falls in the form of water or snow depending upon the temperature, this evaporation& precipitation is a continuous process.

2. What do you mean by hydrograph? Ans A hydrograph is a graph showing the rate of flow (discharge) versus time past a specific point in a river, or other channel or conduit carrying flow. It can also refer to a graph showing the volume of water reaching a particular outfall, or location in a sewerage network. Graphs are commonly used in the design of sewerage, more specifically, the design of surface water sewerage systems and combined sewers.

3. Classify Dams & Spillways?

Ans: The different types of dams are: i) Masonry dams:

a. Gravity dams: This type of dam is built of masonry, motor (or) concrete.


b. Buttress dams: An arch dam is a solid concrete structure, curved

upstream in plan, which is addition to resisting part of pressure of the reservoir.

c. Arch dams: The dams of buttress type have become more & more popular because of overall economy in their construction.

ii) Earth-fill dams: a. Earth-fill dams: For small projects, in particular dam constructed of

earth-fill are commonly used.

b. Rock fill dams: The rock-fill dams have characteristics midway between gravity dams & earth dams.

Spillways: i) Overflow spillway: The spillway built on the top of the dam. It is used for

concrete dams.

ii) Chute spillway: The chute spillway refers to an overflow spillway isolated from the dam.

iii) Shaft spillway: The water drops the vertical stop & passes through a horizontal passes the water to the down direction of the dam.

iv) Siphon spillway: If the space is limited & the discharge capacity is less this type of spillways are used.

4. What are the merits & demerits of the hydro-electric power station? Ans: : a) Merits:

i)The layout, construction, and operation of the plant are simple.

ii)Maintenance cost is low.

iii)It can be started and put into service instantly.

iv)It can take varying load easily.

v)It has no standby losses.

vi)No fuel charges are required.

vii)Less number of operational staff is required.

b)Demerits :

i)Large area is required.

ii)It takes a long time for erection.


iii)The construction cost is very high.

5. Write about Hydro Electric Plant?

Ans: Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. Worldwide, an installed capacity of 777 GWe supplied 2998 TWh of hydroelectricity in 2006. This was approximately 20% of the world's electricity, and accounted for about 88% of electricity from renewable sources.



1. Explain the general layout of Hydro-electric power plant?

Ans: Hydro-electric power plant: Catchment area: To start any hydroelectric power plant the catchment area is most important to store water & to maintain the head rays in the reservoir (or) otherwise, it is simply the run-off water to the dam (or) reservoir. Damn: It is the main component of hydro-electric power plant & it built the structure for the storage of water. Penstock: It is a long pipe connected between head rays to turbine blade the materials used is steel, plastic. Surge tank: It is the amount of temporary water stored in the surge tank which supplies the water for the peak loads of the power house. Turbine: It is a hydraulic device which is used to convert hydraulic energy into mechanical energy the water having high K.E & P.E energy is directed to flow on the turbine blades. Generator: It is a device which is used to convert mechanical energy & which is coupled to the turbine.

2. What do you mean by hydrograph iin detail?

Ans.:A hydrograph is a graph showing the rate of flow (discharge) versus time past a specific point in a river, or other channel or conduit carrying flow. It can also refer to a graph showing the volume of water reaching a particular outfall, or location in a sewerage network. Graphs are commonly used in the design of sewerage, more specifically, the design of surface water sewerage systems and combined sewers.


This type of hydrograph is known as astorm or flood hydrograph and it is generally drawn with two vertical axes. One is used to plot line graph showing the discharge of a river in cum/sec (cubic meters per second) at agiven point over a period of time. The second is used to plot a bar graph of the rainfall event which precedes the changes in discharge.The scale on the horizontal axis is usually in hours/days and this allows both the rain event to be recorded and the subsequent changes in river discharge to be plotted.

The shape of the hydrograph varies according to a number of controlling factors in the drainage basin but it will generally include the following features.

The baseflow of the river represents the normal day to day discharge of the river and is the consequence of groundwater seeping into the river channel. The rising limb of the hydrograph represents the rapid increase in resulting from rainfall causing surface runoff and then later throughflow. Peak discharge occurs when the river reaches its highest level. The time difference between the peak of the rain event and the peak discharge is known as the lag time or basin lag. The falling limb (or recession limb as it is sometimes known) is when

most overland flow has now been discharged and it is mainly throughflow which is making up the river water.

3.i)Availability of water flow: a) Run-off River with poundage: These types of run-off river

hydroelectric power plants usually produce the power during peak loads. During the day-time and off-power and the water is stored in large pond. At night-times and during peak load the stored water is used to generate electricity.

b) Run-off River without poundage: In the run-off river type of hydroelectric power plants the running water of the river is used for the generation of electricity. Whenever the water is available the hydroelectric power plant generates electricity and when there is no water no power is generated

c) Reservoir power plants: The reservoir in the hydroelectric power plants has the capacity to store extremely large quantities of water that can be used throughout the whole season.

ii)Availability of water head: a) Low head: The low head hydroelectric power plants are the ones in

which the available water head is less than 30 meters.


b) Medium head: The hydroelectric power plants in which the working head of water is more than 30 meters but less than 300 meters are called medium head hydroelectric power plants.

c) High head: In the high head hydroelectric power plants the head of water available for producing electricity is more than 300 meters and it can extend even up to 1000 meters.

iii)According to the loading types: c) Base load:The base load type of hydroelectric power plants produce

power constantly irrespective of the total load in the national grid. They keep on producing power throughout the day and during all the times of the year. They will stop producing power only during breakdown maintenance.

d) Peak load: Most of the normal power requirements are fulfilled by the base load hydroelectric power plants. However, during night times the requirement of power becomes very high; it is called peak load period.

4. How wind energy is used for producing electricity? Ans: Wind energy: The electrical energy can be generated by wind energy. The wind energy, which is an indirect source of energy, can be used to run a wind mill which in turn drives a generator to produce electricity. Types of Wind energy: The wind energy mills are generally classified as:

iv) Horizontal axis wind mill (HAWM): Its extremely long blades are mounted on rigid hub; large blade-root bending moments can occur due to tower shadow, gravity and sudden shifts in wind directions. Horizontal axis is again classified as:

d) Single-bladed. e) Double-bladed. f) Multi-bladed & bi-cycle multi-bladed type.

v) Vertical axis wind mill (VAWM): To reduce the cost of large wind turbine

generator is to design them with motors that spin on vertical axis. 5. List out the types of tidal energy? Explain tidal energy?

Ans: Tidal energy:


The periodic rise & fall of water level of the sea. Tides occur due to the attraction of sea water by the moon. These tides can be used to produce electrical power which is known as tidal power. When the water is above the mean sea level, it is called flood tide and when the level is below the mean level, it is called ebb tide.

Classification of tidal power plant: Classified on the basis of the no: of basins. a) Single basin system:

i. One-way system. ii. Two-way system.

iii. Two-way with pump storage. b) Double basin system:

i. Simple double basin. ii. Double basin with pumping.

6. Explain different types of solar collectors?

Ans: Solar collectors: A solar collector is a device for collecting solar radiation to transfer the energy to a fluid passing in contact with it. Utilization of solar energy requires solar collectors. These are generally two types:

i) Non-concentrating type solar collectors: In the non-concentrating type the collected area is the same as the absorber.

ii) Concentrating type solar collectors: In concentrating collectors, the area intercepting the solar radiation is greater, sometimes hundreds of times greater than the absorber area.


Flat plate collector: The flat plate collectors are classified as low temperature collectors because it gives a temperature range of 60-1000C with a collection efficiency of 30-50%.

A flat plate coated with black coke powder is the solar energy absorber and is covered by one (or) more transparent plates of glass. Parabolic concentrator: A simple parabolic concentrator consists of parabolic cylinder, reflector to concentrate sunlight on to a collecting pipe within Pyrex envelope.


Multiple Choice Questions with Answers 1. Flat plate collector absorbs ____ [ ]

A) Direct radiation

B) Diffuse radiation

C) Both a and b

D) None

2. That transparent cover in the solar collector helps to___ [ ]

A) Prevent the collector from dust

B) Decrease the heat loss from collector

C) Transmit solar radiation

D) All the above

3. Which of the following is an auxiliary of hydropower plants? [ ]

A) Exciter

B) Governor oil system

C) Lubrication oil pump

D) All the above

4. Major portion of the solar radiation received on the surface of the

Earth lies between_____ [ ]

A) 0.2 to 0.4

B) 0.38 to 0.78

C) 0.8 to 6.0

D) 0 to 0.38

5. _____ turbines are used in the medium head power plants [ ]

A) Francis

B) Kaplan

C) Pelton

D) None

6. The wall built across the river to store water is____ [ ]

A) Spill way

B) Draft tube

C) Dam

D) Surge tank


7. _____ is the curve drawn between flow available during a period and the

Fraction of time [ ]

A) Hydrograph

B) Flow duration curve

C) Mass flow curve

D) None

8. The main phase of hydrological cycle is___ [ ]

A) Infiltration

B) Evaporation

C) Precipitation

D) None

9. The science that deals with the study of rainfall and run-off is____ [ ]

A) Hydrology

B) Geology

C) Metrology

D) None

10. The cheapest plant in operation and maintenance is.......

A) Steam power plant

B) Nuclear power plant

C) Hydro-electric power plant

D) None of the above

Answer:1. B2. C3. A4. D5. A6. C7. B8. C9. A10. C



1. The energy obtained from the falling water is a small process in the heat power cycle

4. The dams of hydro-plants are

storage above the permissible level.

7. Pumped storage plants are used for supplying.

s the temperature attained by a flat plate collector.

Answer:1. Hydrological cycle.2. Hydrograph.3. Run-off.4. Spillways.5. Mass flow curve.6.

High.7. Peak load 8. 90 0C9. Cylindrical parabolic &paraboloid10. Reversible type.


UNIT-IV


1. What is an atom?

Ans: The smallest particle of an element which can take part in chemical reaction is known

as atom.

2. What are isotopes?

Ans: Atoms having different number of neutrons than the number of protons are known as isotopes. 3. What is radioactive decay?

Ans: The disintegration of heavier nuclei isotope by the emission of alpha, beta or gamma

particle through fission reaction.

4. What are elastic scattering?

Ans: The total internal energy of the bombarded nucleus and the re-striking particles identical

neutron the process is known as elastic scattering

5. What is the purpose of reprocessing of nuclear reactor?

Ans: The used fuel contains 96% uranium,1% plutonium and 3% radioactive wastes. Reprocessing is used to separate the waste from the uranium and plutonium which can be recycled into new fuel. The reprocessing effectively reduces the volume of waste and limits the need to mine new supplies of uranium, so that extending the time of resources 6. Define nuclear fusion?

Ans: The process of combining two lighter nuclei into a stable and heavier nuclei by releasing large amount of energy.



1. List the four types of radiation associated with nuclear fission?

Ans:i)Alpha radiation ii)Beta radiation iii) Gamma radiation iv)Neutron radiation i)Alpha radiation: Alpha radiation consist of alpha particles at high energy/speed. The production of alpha particles is termed alpha decay. Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha particles are relatively large and carry a double positive charge. They are not very penetrating and a piece of paper can stop them. They travel only a few centimeters but deposit all their energies along their short paths. ii)Beta radiation: Beta radiation consists of electrons or their positively charged counterparts. This can penetrate the skin, but not very far. iii)Gamma radiation: Gamma radiation is penetrative in a manner similar to X-rays and has similar physical properties. It can be stopped only by thick shields of lead or concrete. iv) Neutron radiation: Neutron radiation consists of the neutrons emitted during the fission process. Neutrons are

also very penetrative, but less so then gamma-radiation

2. Explain the nuclear fuel cycle?

Ans: Nuclear fuel: The materials used in nuclear reactors must satisfy the mechanical & metallurgical requirements as adequate strength & corrosion resistance during operation & good ductility & machinability during fabrication. The main fuel materials which are used are natural uranium, enriched uranium, plutonium & U233.Nuclear fuel has the highest energy density of all practical fuel sources.

The nuclear fuel cycle consists of front end steps that prepare uranium for use in nuclear

reactors and back end steps to safely manage, prepare, and dispose of highly radioactive spent

nuclear fuel

3. Write a short note on a)Breeding materials b)Fertile materials ?

Ans: a)Breeding:


Breeding in nuclear reactors refers to the process in which significantly amount of fertile materials are converted to fissile materials by nuclear transmutation. This requires the fertile isotope to have large cross section for neutron capture. Since the main purpose of a nuclear reactor is to produce electricity, breeding is considered as an off-shoot of excess neutrons produced during fission above the ones required for sustenance of chain reaction. The possibility of breeding in a nuclear reactor, taking into account of the type of fissile material used, depends on the number of neutrons produced for every neutron absorbed in the fuel.

s sections as follows: b) Fertile ,materials:

Fertile materials: It has been found that some materials are not fissionable by themselves but they can be converted to the fissionable materials, these are known as fertile materials.

Pu239 and U233 are not found in nature but U238 and Th232 can produce them by nuclear reactions. When U238 is bombarded with slow neutrons it produces 92U239 with half-life of 23.5 days which is unstable and undergoes two beta disintegrations. The resultant Pu239has half-life of 2.44*104yrs and is a good alpha emitter.

4. State the beneficial uses of nuclear radiation?

Ans: Nuclear radiation has number of ways of beneficial uses, including:

Medicinal, such as radio therapy for cancers and X-rays

Level indicators and thickness gauges.

In smoke detectors and

In tracing locations of gas or liquid leaks or

Tracing locations of malfunctioning in the body such as a blocked kidney.

Sterilization of medical instruments or bacteria or moulds in foods.

5. What are the criteria used for evaluation of nuclear plant safety?

Ans: The criteria used for the evaluation of nuclear plant safety are No unreasonable risk

Adequate protection of public health safety.

Risk as low as reasonable practicable.

Safety as high as reasonably achievable.

Limit risk by use of best technologies at acceptable economic costs.



1. Explain the components of nuclear reactor with its neat sketch?

Ans: Nuclear reactor: A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an exploitation. The general arrangement of nuclear power plant with essential components using steam as working fluid:

i) Fuel: The nuclear fuels which are generally used in reactors are 92U235, 94Pu 239 and 92U233. Among the three, the 92U235is naturally available up to 0.7% in the uranium ore and the remaining is 92U238.

ii) Moderator: The moderator is a material which reduces the kinetic energy of fast neutron to slow neutron and this is done in a fraction of second.

iii) Reflector: It is always necessary to conserve the neutrons as much as possible in order to reduce the consumption of fissile material and o keep the size of the reactor small.

iv) Coolant: The main purpose of the coolant in the reactor is to transfer the heat produced inside the reactor.

v) Control rods: Some type of control is absolutely necessary to fulfill the function. The control is necessary to prevent the melting of fuel rods, disintegration of coolant and destruction of reactor as the amount of energy released is enormous.

vi) Shielding: The reactor is a source of intense radioactivity and these radiations are very harmful to the human life.

vii) Reactor vessel: The reactor vessel encloses the reactor core, reflector and shield. It also provides the entrance and exit passages for directing the flow of coolant.

2. Explain in detail of PWR & BWR?

Ans:Pressurized water cooled reactor: Pressurized water reactors (PWRs) constitute the large majority of the world's nuclear power plants.In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated water then


flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator.In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator.

Design: Nuclear fuel in the reactor pressure vessel is engaged in a fission chain reaction, which produces heat, heating the water in the primary coolant loop by thermal conduction through the fuel cladding. The hot primary coolant is pumped into a heat exchanger called the steam generator, where it flows through hundreds or thousands of small tubes. Heat is transferred through the walls of these tubes to the lower pressure secondary coolant located on the sheet side of the exchanger where the coolant evaporates to pressurized steam. The transfer of heat is accomplished without mixing the two fluids to prevent the secondary coolant from becoming radioactive. Some common steam generator arrangements are u-tubes or single pass heat exchangers. Sodium graphite reactor:

It is one of the typical liquid metal reactors. In this reactor sodium works as a coolant & graphite works as a moderator. Sodium is first melted by electric heating system & be pressured to about 7 bar. The liquid sodium is then circulated by the circulation.

i) Primary circuit: It has liquid sodium which circulates through the fuel core & gets heated by the fissioning of the fuel. This liquid sodium gets cooled in the intermediate heat exchanger & goes back to the reactor vessel.

ii) The secondary circuit: It has an alloy of sodium & potassium in liquid form. This coolant takes heat from liquid sodium-potassium of primary circuit.

3. Write a short note on fast breeder reactor, Homogenous & Gas cooled reactor?

Ans: ) Fast breeder reactor:


In fast breeder reactor, an enriched uranium (or) plutonium is kept in the casing without moderator. The casing is surrounded by fairly thick blanket of depleted fertile uranium. The ejected excess-neutrons are absorbed by the fertile blanket & it converts into fissile material.

.

Homogenous reactor:

In homogenous reactor the fuel & moderator are mixed in the form of homogenous material, i.e. uranium fuel salt forms a homogenous solution in water which is a moderator or particles of uranium & carbon gives a mechanical mixture. Gas cooled reactor:

The reactor is cooled by the gas and the heat carried by the gas from the reactor is either used for generating stem in the secondary circuit like PWR (or) it can be directly used as working fluid in gas turbine plant.

4. What is the necessity of shielding?

Ans: Shielding: Shielding is necessary in order to:

iii) To protect the walls of the reactor vessel from radiation damage & iv) Protect operating personnel from exposure to radiation.

The radiation from nuclear reactors is extremely varied in character and its ability to -

radiations, -radiations which penetrate


much due to their high energy level & frequency require higher thickness of shielding material.

The main function of lead in nuclear plants is to protect the radioactive materials which are produced in the reactor and to protect the harmful radiations. Lead bricks, core lead pipes, lead wool, lead sheets are some of the radioactive materials which are used in the nuclear plants. Lead shields and the lead foils are the most commonly used radioactive shielding accessories. Some of the most common lead shielding equipments which are used in the industry are glass plates, glass equipments and lead shielded syringes. Radiation proof shielded doors are used in the X-ray rooms. Lead shielded gloves, curtains aprons, collar are widely used by the medical practitioners who are handling with the radioactive materials. Lead containers are widely used for storing the samples required for the tests and for treating the diseases which make use of radioactive materials. Lead sheets Lead sheets are widely used to weaken certain kinds of radiations due to its high density and atomic number. They are quite effective in stopping the alpha rays, x-rays and the gamma rays. It is more effective than neutron radiation. Lead bricks are used to build shielding walls for temporary or permanent storage locations. The properties of good shielding:

4) -radiations with minimum thickness of shielding material.

5) It must be fire-resistant. 6) It should not be decomposed (or) weaken under the influence of radiation.

5. Explain nuclear waste disposal system?

Ans: Different methods for nuclear waste disposal. i) Disposal of low level solid waste:

The nuclear waste of this category is cast in cement in steel drum. These drums are buried either below the soil(or) kept at the bed of the ocean. The safety of the method lies in the vast dilution of the activity as it disperses at the bottom of the ocean.

ii) Disposal of medium level solid waste:


These wastes are mainly contaminated with neutron activation product isotopes. They are incorporated into cement cylinders as cement is non-combustible and provides shielding against external exposure.

iii) Disposal of high level liquid waste: The remaining liquid is stored on the site in special steel tanks in concrete vaults. They are water cooled and then taken to the storage area.



1. The methods used for radioactive waste disposable are _____ [ ] a) dilutions of liquids and gases b) storage in sealed containers c) underground burial d) all the above

2. The purpose of thermal shield is to______ [ ]

I. absorb the fast moving neutrons II. protect the reactor walls from radiation damage

III. protect the operator from exposure to radiation a) only i b) only ii c) both i and ii d) both ii and iii

3. In sodium graphite reactor (sgr),_______ is used as coolant [ ]

a) water b) liquid sodium c) co2 d) none

4. ______ fuel is used in boiling water reactor (bwr) [ ]

a) thorium b) enriched uranium c) plutonium d) all the above

5. In pressurized water reactor [ ]

a) coolant water is pressurised to work as the moderator b) coolant water is boiled in the core of a reactor c) coolant water is pressurised to prevent boiling of water in cooler d) no monitor is used

6. The function of reflector in reactor is to _______ [ ]

a) decrease the laws of neutrons b) slow down the fast moving neutrons c) absorb the neutrons d) reduce the temperature

7. The moderator helps in ______ in a nuclear reactor [ ]


a) reducing the temperature b) reducing the speed of the neutrons c) absorbing the neutrons d) stopping the chain reaction

8. The percentage of u235 by weight in naturally available uranium is ___ [ ]

a) 0.3 b) 0.5 c) 1.04 d) 0.7

9. The first nuclear power plant in india was started at ______ [ ]

a) kota b) kalapakkam c) tarapur d) naroria

10. ______ isotope of uralian is used in the nuclear fission reaction [ ]

a) u233 b) u234 c) u235 d) u238

Answer:1.d 2.d 3. b4. B 5. C 6.a 7. b 8. D 9.c 10.a



2. Each neutron that causes fission reaction in a nuclear chain fission reaction produces

New neutron.

3. The materials which are not fissionable can be converted into fissionable materials by

particular

generation to the number of neutrons in the preceding generation.

reactor.

controlled self-sustaining chain reaction.

d reflector.

Moderator is used in fast breeder reactor(FBR).

Answer: 1. 200 2. More than one 3. Fertile materials 4. Multiplication factor.

5. Breeding.6. Nuclear reactor 7. Graphite.8. Ordinary water (H 2 O) 9. No.

10. Fluid fuel reactors.


UNIT-V


1. Define demand factor?

Ans: Demand factor is defined as the ratio of maximum demand to connected load.

2. Define load factor?

Ans: Load factor is defined as the ratio of average load to the peak load (or) maximum

demand.

3. Define load curve?

Ans: Load curve is a graphical representation between load in kW and time in hours. It

shows variation of load at the power station. The area under the load curve -represents the

energy generated in a particular period.

4. What is the need of depreciation cost?

Ans: Depreciation cost is the amount to be set aside per year from the income of the plant to

meet the depreciation caused by the age of service, wear and tear of the machinery and

equipments. Depreciation amount collected every year helps in replacing and repairing the

equipment.

5. What includes fixed cost?

Ans.: Fixed cost includes the following cost:

1. Cost of land

2. Cost of building

3. Cost of equipment

4. Cost of installation

5. Interest

6. Depreciation cost

7. Insurance

8. Management cost



1.What do you understand from the load duration curve?

Ans.: Load Duration Curve A load duration curve represents re-arrangements of all the load elements of chronological load curve in order of descending magnitude. This curve is derived from the chronological load curve. Figure shows a typical daily load curve for a power station. It may be observed that the maximum load on power station is 35 kW from 8 AM to 2 PM. This is plotted in Figure. Similarly, other loads of the load curve are plotted in descending order in the same figure. This is called load duration curve.

Fig: daily load curve

Fig: Daily duration curve

2.What are the different types of pollutants? Ans: Types of pollutants: Primary pollutants are emitted directly into the environment, while secondary pollutants are formed from primary pollutants and external factors.


Many pollutants are introduced into the environment in different ways, they have different and sometimes unique health effects and are found in different amounts. It is hard to briefly describe these for each chemical, however they can be read about on each pollutant's own page. Different types of pollutants include:

Nitrogen oxides (NOx) Sulfur oxides (SOx) Particulate matter (PM) Ground level ozone (O3) Volatile organic compounds (VOCs) Mercury (Hg) Peroxyacyl nitrates (PANs)

3. Define the following terms?

Connected load. Maximum Demand. Demand factor.

Ans: Connected load:

The connected load is the sum of ratings in kW of the equipments installed in the

= 60+500+60+100+500+100+60 = 1440 watts.

Maximum demand : The maximum demand is the maximum load which a consumer uses at any time. It is always less than connected load (or) equal to connected load. When all the equipments

ly then the maximum demand becomes equal to connected load.

Demand factor : It is defined as the ratio of maximum demand to connected load. It is defined as the ratio of maximum demand to connected load.

4. Define load curve? Explain the significance of load curves?

Ans: Load Curve: A load curve (or load graph) is a graphic record showing the power demands for every instant during a certain time interval. Such a record may cover 1 hour, in which case it would be an hourly load graph; 24 hours, in which case it would be a daily load graph; a month in which


case it would be a monthly load graph; or a year (7860 hours), in which case it would be a yearly load graph. Significance of Load Curves

a) Load curves give full information about the incoming and help to decide the installed capacity of the power station and to decide the economical sizes of various generating units.

b) These curves also help to estimate the generating cost and to decide the operating

schedule of the power station, i.e. the sequence in which different units should be run.

5. Define the following terms?

Average load.

Load factor.

Diversity factor.

Plant capacity factor.

Plant use factor.

Ans: Average load : The average load is calculated dividing the area under the load curve by the period considered to draw the load curve. Average load =

Load factor : It is defined as the ratio of average load to the peak or maximum load determined by the consumer.

Diversity factor : The diversity factor is the ratio of the sum of the maximum demands of the individual consumers and the simultaneous maximum demand of the whole group during a particular time.

Plant capacity factor : It is defined as the ratio of actual energy produced to the maximum possible energy that could have been produced at the same time.

Plant use factor : It is defined as the ratio of energy produced in given time to maximum possible energy that could have been produced during the actual number of hours of operation.



1. Define Initial cost? Mention its types??

Ans: The initial cost of a power station includes the following:-

Land cost Building cost Equipment cost Installation cost Overhead charges which will include the transportation cost, stores & storekeeping

charges, interest during construction etc. Interest: It is the difference between money borrowed & money returned. Depreciation: It accounts for the deterioration of the equipment & decrease in its

value to corrosion, weathering & wear & tear with use. Straight line method: It is the simplest method & commonly used. The life of the

equipment or the enterprise is first assessed as also the residual (or) salvage value of the same after the estimated life span.

Percentage method: In this method the deterioration in value of equipment from year to year is taken into account & the amount of depreciation calculated upon residual value for each year.

Sinking fund method: This method is based on the conception that the annual uniform deduction from income for depreciation will accumulate to capital value of the plant.

Unit method: In this method some factor is taken as a standard one & depreciation is measured by that standard.

2. Define pollutant? What are its standards?

Ans: Pollutant: A pollutant is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with human amenities, comfort, health, or property values. Pollutant standard: The Pollutant Standards Index, or PSI, is a type of air quality index, which is a number used to indicate the level of pollutants in air.

Pollutants: Coal combustion releases nitrogen oxides, sulfur dioxide, particulate matter (PM), mercury, and dozens of other substances known to be hazardous to human health.[1]

Aging coal plants "grandfathered" in after passage of the Clean Air Act have been particularly linked to large quantities of harmful emissions.[4][5]

Such emissions include: Nitrogen oxides (NOx): The release of oxides of nitrogen (nitrogen oxides and nitrogen dioxides [NO2]) reacts with volatile organic compounds in the presence of sunlight to


produce ground-level ozone, the primary ingredient in smog. Nitrogen oxide also contributes to fine particulate matter, or soot. Both smog and soot are linked to a host of serious health effects. Nitrogen oxide also harms the environment, contributing to acidification of lakes and streams (acid rain).

Sulfur dioxide (SO2). Sulfur dioxide contributes to the formation of microscopic particles (particulate pollution or soot) that can be inhaled deep into the lungs and aggravate respiratory conditions such as asthma and chronic bronchitis, increasing cough and mucous secretion.

Mercury (HG). Coal contains trace amounts of mercury that, when burned, enter the environment and human bodies, effecting intellectual development.[6]

Particulate matter (PM), also known as particle pollution, includes the tiny particles of fly ash and dust that are expelled from coal-burning power plants. Fine particles are a mixture of a variety of different compounds and pollutants that originate primarily from combustion sources such as power plants, but also diesel trucks and buses, cars, etc. Fine particles are either emitted directly from these combustion sources or are formed in the atmosphere through complex oxidation reactions involving gases, such as sulfur dioxide (SO2) or nitrogen oxides (NOX). Among particles, fine particles are of particular concern because they are so tiny that they can be inhaled deeply, thus evading the human lungs' natural defenses.[7]

Smog is the chemical reaction of sunlight, nitrogen oxides (NOx), and volatile organic compounds (VOCs) in the atmosphere, which leaves airborne particles (particulate matter) and ground-level ozone (smog). Ground level ozone is an invisible gas made of three oxygen atoms (O3).

Black carbon, also called soot, arises from sources such as diesel engine exhaust, burning biomass, cooking fires, and coal plants. It is made up of tiny carbon particulate matter that contributes to global warming by absorbing heat in the atmosphere and reducing albedo, the reflection of sunlight, when deposited on snow and ice. It is also a big component of air pollution around the world.

3. Define capital cost? Mention its types?

Ans: Capital cost:

It includes the following:

Initial cost.


Interest Depreciation cost Taxes Insurance.

iv) Initial cost: Some of the several factors on which cost of a generating station or a power plant depends are:- a) Location of the plant. b) Time of construction. c) Size of units. d) No: of main generating units. e) The type of generating units.

4. What are the elements which includes operating cost?

Ans: Operating charges: The elements that make up the operating expenditure of a power plant include the following costs: (a) Cost of fuels. (b) Labour cost. (c) Cost of maintenance and repairs. (d) Cost of stores (other than fuel). (e) Supervision. (f) Taxes. Cost of Fuels: In a thermal station fuel is the heaviest item of operating cost. The selection of the fuel and the maximum economy in it use are, therefore, very important considerations in thermal plant design. It is desirable to achieve the highest thermal efficiency for the plant so that fuel charges are reduced. The cost of fuel includes not only its price at the site of purchase but its transportation and handling costs also. In the hydro plants the absence of fuel factor in cost is responsible for lowering the operating cost. Plant heat rate can be improved by the use of better quality of fuel or by employing better thermodynamic conditions in the plant design. The cost of fuel varies with the following : (a) Unit price of the fuel. (b) Amount of energy produced. (c) Efficiency of the plant. Labour Cost: For plant operation labour cost is another item of operating cost. Maximum labour is needed in a thermal power plant using coal as a fuel. A hydraulic power plant or a diesel power plant of equal capacity require a lesser number of persons. In case of automatic power station the cost of labour is reduced to a great extent. However, labour cost cannot be completely eliminated even with fully automatic station as they will still require some manpower for periodic inspection, etc. Cost of Maintenance and Repairs: In order to avoid plant breakdowns maintenance is necessary. Maintenance includes periodic cleaning, greasing, adjustments and overhauling of equipment. The material used for maintenance is also charged under this head. Sometimes an arbitrary percentage is assumed as maintenance cost. A good plan of maintenance would keep the sets in dependable condition and avoid the necessity of too many stand-by plants. Repairs are necessitated when the plant breaks down or stops due to faults developing in the mechanism. The repairs may be minor, major or periodic overhauls and are charged to the


depreciation fund of the equipment. This item of cost is higher for thermal plants than for hydro-plants due to complex nature of principal equipment and auxiliaries in the former. Cost of Stores (Other Than Fuel): The items of consumable stores other than fuel include such articles as lubricating oil and greases, cotton waste, small tools, chemicals, paints and such other things. The incidence of this cost is also higher in thermal stations than in hydro-electric power stations. Supervisions: In this head the salary of supervising staff is included. A good supervision is reflected in lesser breakdowns and extended plant life. The supervising staff includes the station superintendent, chief engineer, chemist, engineers, supervisors, stores incharges, purchase officer and other establishment. Again, thermal stations, particularly coal fed, have a greater incidence of this cost than the hydro-electric power stations. Taxes : The taxes under operating head includes the following: (a) Income tax (b) Sales tax

5. Describe briefly about general arrangement of power distribution?

Ans: General arrangement of power distribution:

The cost of generation & transmission is not only dependent on the improved operating conditions, such as turbine & generators operating at their best efficiency or uniform rate of driving the boilers, but depends upon the first cost of equipment which can be reduced by using simplified control and eliminating the various auxiliaries & regulating devices. Electric power distribution is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers. A modern power station has more than one generator and these generators are connected in parallel. Also there exist a large number of power stations spread over a region or a country. A regional power grid is created by interconnecting these stations through transmission lines. In other words, all the generators of different power stations, in a grid are in effect connected in parallel. One of the advantages of interconnection is obvious; suppose due to technical problem the generation of a plant becomes nil or less then, a portion of the demand of power in that area still can be made from the other power stations connected to the grid. One can thus avoid complete shut-down of power in an area in case of technical problem in a particular station. It can be shown that in an interconnected system, with more number of generators connected in parallel, the system voltage and frequency tend to fixed values irrespective of degree of loading present in the system. This is another welcome advantage of inter connected system. Inter connected system however, is to be controlled and monitored carefully as they may give rise to instability leading to collapse of the system.


Thermal plant: We have seen in the previous section that to generate voltage at 50 Hz we have to run the generator at some fixed rpm by some external agency. A turbine is used to rotate the generator. Turbine may be of two types, namely steam turbine and water turbine. In a thermal power station coal is burnt to produce steam which in turn, drives the steam turbine hence the generator (turbo set). In figure 2.2 the elementary features of a thermal power plant is shown. In a thermal power plant coil is burnt to produce high temperature and high pressure steam in a boiler. The steam is passed through a steam turbine to produce rotational motion. The generator, mechanically coupled to the turbine, thus rotates producing electricity. Chemical energy stored in coal after a couple of transformations produces electrical energy at the generator terminals as depicted in the figure. Thus proximity of a generating station nearer to a coal reserve and water sources will be most economical as the cost of transporting coal gets reduced. In our country coal is available in abundance and naturally thermal power plants are most popular. However, these plants pollute the atmosphere because of burning of coals. Transmission of power : The huge amount of power generated in a power station (hundreds of MW) is to be transported over a long distance (hundreds of kilometers) to load centers to cater power to consumers with the help of transmission line and transmission towers. Distribution system: Till now we have learnt how power at somewhat high voltage (say 33 kV) is received in a substation situated near load center (a big city). The loads of a big city are primarily residential complexes, offices, schools, hotels, street lighting etc. These types of consumers are called LT (low tension) consumers. Apart from this there may be medium and small scale industries located in the outskirts of the city. LT consumers are to be supplied with single phase, 220 V, 40 Hz. We shall discuss here how this is achieved in the substation receiving power at 33 kV.


Multiple Choice Questions Answers

UNIT-V

1. _____ is the pollutant which is responsible for suffocation, irritation of throat and eyes in humans [ ]

a) so2 b) no2 c) h2s d) co

2.___ power plants consume more fuel and effort the environment [ ]

a) nuclear b) hydro c) thermal d) gas

3.Depreciation charges are more in case of ____ [ ]

a) thermal plant b) hydroelectric plant c) diesel plant d) gas turbine plant

4._____ is the ratio of maximum power demands of subdivisions of the system of the maximum demand of the system measured at point of supply [ ]

a) load factor b) diversity factor c) capacity factor d) utilization factor

5. Demand factor is defined as [ ]

a)

b)


c)

d)

6. The highest of all the demands that are often during a given period is [ ]

a) average demand b) maximum demand c) connected load d) none

7.The annual depreciation cost can be calculated by ____ method [ ]

a) straight line method b) sinking fund method c) both a and b d) none

8. Which of the following comes under capital cost [ ]

a) initial cost b) interest c) taxes d) all the above

9.The load which is constant throughout the whole day on the power plant is known as _____ [ ]

a) base load b) peak load c) load factor d) load curve

10.A graph obtained between the load consumption and time is called as _____ [ ]

a) base load b) load curve c) peak load d) load factor

Answer: 1. a 2. c 3. a 4. b 5. a 6. b 7. c 8. d 9. a 10. b



3. The rearrangement of all the load elements of load curve in the descending order is

represented

the contamination of soil,

air

and water with unwanted material or heat.

-charged to the environment for

evergy

unit of electrical energy produced.

Answer: 1. Operational cost.2. Load curve. 3. Load duration curve.

4. Connected load. 5. Load factor. 6. Pollutants. 7. NOX 8. 9. Thermal discharge index(TDI)

9. Straight line method (or) Sinking fund method.9. Thermal


17. BEYOND SYLLABUS TOPICS WITH MATERIAL -NIL


18. RESULT ANALYSIS

Academic Year Students Appeared Students Passed Pass Percentage (%)

2013 56 43 76.78

2014 41 40 97.60

2015 35 33 94.28

2016 103 92 89.32

2017 59 49 83.05



19. Record of Tutorial Classes



20. Record of Remedial Classes



21. Record of Guest Lecturers Conducted



EXTRA QUESTION SET 1. Explain coal handling equipments used at different stages in power plant with

neat line diagram ?

2. Describe hydraulic ash handling system?

3. Briefly describe various ash handling equipments?

4. Explain different components used in steam power plant ?

6. Discuss the principles of site selection of a steam power station?

7. Explain basic energy resources in India?

8. Briefly discuss fuel resources and power development in India?

9. Explain briefly air and gas flow system in a thermal power plant? Classify

draught system. Mention the types of fans used for producing draughts?

10. Define energy and explain different forms of energy?

11. Explain the working of different circuits in thermal power plant?

12. Explain overfeed firing of coal?

13. Classify and explain methods of pulverized coal firing?

14. How are pulverize classified? On what factors does the performance of a

pulverize depends?

17. Explain water treatment process in power plant?

18. With the help of neat sketch explain the working of electrostatic precipitator?

19. Illustrate the constructional details of an I C engine. Explain briefly about

important components?

20. Name the essential components and their functions in a diesel power plant?

21. Draw the schematic diagram of a simple cycle with intercooler and explain

Briefly the working principle. Draw also the p-v and t-s diagram of the

cycle?

22. Explain different types of combustion chambers used in gas turbines?

23. Explain the necessity of cooling system in a diesel engine? What are the

methods of cooling the engine?

24. Why the maximum temperature in a gas turbine cycle is limited to 850? What

are the principle components in a closed cycle gas turbine and explain them

Briefly, show the cycle on t-s diagram ?

25. Describe the construction and working of a solar cell ?


26. Explain the principle of MHD power generation? Differentiate between

thermo-electric and thermo-ionic conversion systems?

27. Explain the working of open and closed cycle MHD systems and discuss their

Relative merits?

28. Explain See-back, Peltier and Thomson effect?

29.Draw a neat sketch of a hydropower plant and show the various elements

and purpose of providing it ?

30.Discuss various types of spillways with neat sketch ?

31.Explain layout diagram of high , medium and low head plant with neat Sketches ?

32.Discuss in detail classification of hydroelectric plants and their special Features?

33.Discuss with the help of a neat sketch the working of pressurized water

reactor plant ?

34. Explain the construction and working of a gas cooled reactor. What are its

advantages and dis-advantages ?

35. Explain the working of a moderated type nuclear power station with a

block diagram ?

36. Give the classification of nuclear wastes in detail? Describe how nuclear

wastes are disposed ?

37. What is function of shield? What are the different types of shields? What is

radioactive pollution and explain the measures to control it?

38.What is a homogeneous reactor ? Explain its working?

39.Explain the working of fast breeder reactor with a neat sketch?

40. Explain about 3- stages nuclear programmed of India?

41.Explain briefly about capital or fixed cost and operational cost?

42. Explain the methods to reduce noise pollution?

43. Define connected load, maximum demand , demand factor ?

44. Explain how the load factor, capacity factor and utilization factor are interrelated . also

explain the significance of diversity factor ?

45. Explain different methods to adopt nuclear pollution ?

46. What are the basic radioactive pollutants? What are their bad effects on human and

vegetarian life ?

47.Define pollutants? What do you mean by depreciation? Enumerate and explain briefly

various methods used to calculate the depreciation cost?


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14. ASSIGNMENT TOPICS WITH MATERIALSkgr.ac.in/beta/wp-content/uploads/2018/09/Power-Plant... · 2018-10-10 · Draught system in thermal power plant Ans.: The draught is one of the