Boiler Theoretical Question

8/3/2019 Boiler Theoretical Question

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BOILER THEORETICAL QUESTION

1 . Define a boiler and steam generated unit .

y A boiler is a container into which is fed, and by application of heat, water evaporators continuously into steam .

y A boiler also can define as a closed vessel where water or someother liquid is heated.

2 . State the use of steam produced by the boiler .

y Economizer used to heat water being fed to the vessely Super heaters used for heating steamy Any pipes and fittings connected

3 . List the primary requirements of steam boiler .

y For generating power in steam turbines.y In the textile industries for sizing and bleaching .y For power plant .

4. How are boiler classified ?

y Horizontal, vertical or inclinedy Fire tube and water tubey Externally fire and internally firey Forced calculation and natural calculationy High preasure and low preasure boiler .y Stationary and portable .

5 . Give the comparison between fire tube and water tube boiler .

PARTICULARS FIRE TUBE BOILER WATER TUBEBOILER

1. Position of water andhot gases.

Hot gases inside thetubes and water

Water inside thetubes and hot gases


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outside the tubes. outside the tubes.

2. Made of firing Generally internallyfired.

Externally fired.

3. Operating pressure Operating pressurelimited to 16 bar.

Can work under ashigh pressure as100 bar.

4. Rate of steamproduction

Lower Higher

5. Suitability Not suitable forlarge power plants.

Suitable for largepower plants.

6. Risk on bursting Involves lesser riskon explosion due to

lower pressure.

Involves more riskon bursting due to

high pressure.7. Floor area For a given power itoccupies more floorarea.

For given power itoccupies less floorarea.

8. Construction Difficult Simple

9. Transportation Difficult Simple10.

Shell diameter Large for samepower.

Small for samepower.

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Chances of explasion Less More

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Treatment of water Not so necessary More necessary

13.

Accessibility ofvarious parts

Various parts not soeasily accessible forcleaning,repair andinspection.

Various parts aremore accessible

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Requirement of skill Require less skill forefficient andeconomic working

Require more skilland carefullattention


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6 . State the differences between the following boilers .

External Fire Internal Fire

The boiler is known as externallyfired if the fire outside the shell

Internally fired boilers , the furnaceis located insides the boiler shell.

Forced circulation Natural circulationIn forced circulations type ofboilers , the circulation of water isdone by a pump .

In natural circulation type ofboilers ,circulations of water in theboiler takes place due to natural

convection currents produced bythe applications of heat.

External Fire Internal Fire

The boiler is known as externallyfired if the fire outside the shell

Internally fired boilers , the furnaceis located insides the boiler shell.

High Pressure Low pressureThe boiler which produce steam atpressure of 80 bar and above arecalled high preasure boiler .

The boiler which produced steamat preasure below of 80 bar arecalled low preasure boilers .

7 .Enumerate the factor which should considered while selecting a boiler

.

The boiler should :

y Realatively inexpensivey Easy to cleany Compact in size


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y Easy to replace tubey Well suited for industrial application

8 . Explain with the help of neat diagrams any two of the following

boilers .

y Scotch boiler

y Simple vertical boiler


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9 . What is the function of the boiler mounting ? can a boiler work

without mounting ?

y Are defined as devices that are attached directly to the boiler sothat the boiler can be operated safely .

y Without mounting boiler cannot work because cannot operatedsafely.

10 . How do accessories differ from mounting ?

y Accessories~boiler accessories are use to recover energy and mark boiler

function more efficientlyy Mounting

~mounting defined as devices that are attached directly to the

boiler can be operates safely .

11 . Enumerate the various accessories normally used in steam

generating plant .

y Economizery Air-preheatery Super heater

12 .What is the function of safety valve ? state the minimum number of

safety valve to be used on a boiler ?

y Safety valves or pressure safety valves are pressure-releasemechanisms used in pressure vessels, boilers and other systems.

y Two safety valve are fitted to each boiler.


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13 . What is a fusible plug and state where it is located in a boiler ?

y To extinguish fire in the event of water level in the boiler shellfalling below a certain specific limit . its protect fire tube from

burning when the level of the water fall abnormally low .

y It is installes below water level.

14 . Describes with the help of sketch the construction and working of a

simple vertical boiler ?

The vertical boiler is a simple type which consists of a firebox at the

bottom and a copper barrel with a smoke tube. It typically is used to

drive stationary engines and boats. Firing is accomplished by alcohol orsolid fuel pellets. More sophisticated versions of the vertical boiler

contain many small tubes and are sometimes fired by coal or charcoal.

15 . Why are water tube kept inclined in Babcock and Wilcox boiler ?

y Babcock and Wilcox boiler with longitudinal drum . It consists of adrum connected to a series of front end and rear and header by

short riser tubes . To these headers are connected a series of

inclined water tube of solid drawn mild steel . The angle ofinclination of the water tubes to the horizontal .


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16 . Distinguish between the mounting and accessory fitted in a boiler

.Explain with sketch any two type of the boiler accessories .

y Accessories~boiler accessories are use to recover energy and mark boiler

function more efficiently

y Mounting~mounting defined as devices that are attached directly to the

boiler can be operates safely .

~AIR-PREHEATER

y The function of the pre-heatr is to increase the temperature of airbefore it enter the furnace . It is generally placed after the

economizer ; so the flue gases pases through the economizer and

then to the air preheated .


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~ECONOMIZERS

y An economizer is a device in which the waste heat of the flue gasesis utilized for heating the feed water .

17 . Distinguish between the mounting and accessory fitted in a boiler

.Explain with sketch any two type of the boiler accessories .

18 . Name all mounting and accessories of a steam boiler and describes

an economizer .

Mounting :y Gauge glassy Safety and relief valvey Pressure gaugey Blow down valvey Fusible plugs


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y Main steam stop valvey Feed check valvey Boiler feed water regulatory Chemical dosing valve

Accessories :

y Economizesy Air preheatery Super heater

Economizers :

~ An economizer is a device in which the waste heat of the flue gases is

utilized for heating the feed water .

19 .What is the function of boiler mounting ? can a boiler work without

mounting ? Explain the sketches any two boiler mounting .

y Are defined as devices that are attached directly to the boiler sothat the boiler can be operated safely .

y Without mounting boiler cannot work because cannot operatedsafely.


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SAFETY AND RELIEF VALVE

~ Is mounted to prevent the pressure in the boiler from exceeding

its maximum allowable working pressure.

~Mechanical device use protecting the boiler against overpressure

FUSIBLE PLUG

~To extinguish fire in the event of water level in the boiler shell falling

below a certain specific limit .

~its protect fire tube from burning when the level of the water falls

abnormally low.


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20 . What do you mean by evaporative of a boiler ? How is it expressed ?

Define and explain equivalent evaporation .

y The process by which any substance is converted from a liquidstate into and carried off in vapour as the evaporation of water of

eather of camphor . the transformation of a portion of a fluid into

vapour in order to obtain the fixed matter contained in it in a state

of greater consistence .


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4 KAEDAH

UTAMA INJAP

DIGERAKAN

INSANI

PNEUMETIKELEKTRIKAL

MEKANIKAL


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Boiler Theoretical Question