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CASE STUDY OF A CONDEMNED BOILER & METHODS TO RE-ESTABLISH IT.

B.Tech. Major (or Minor) Project Report

BY

ADITYA BHATTACHARJEE

DEPARTMENT OF MECHANICAL ENGINEERINGBUDGE BUDGE INSTITUTE OF TECHNOLOGY

KOLKATAJune2016

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TITLE: - CASE STUDY OF A CONDEMNED BOILER & METHODS TO RE-ESTABLISH IT.

A Major (or Minor) Project Report

Submitted in partial fulfilment of theRequirements for the award of the degree

Of

Bachelor of Technology

In

MECHANICAL ENGINEERING

BY

ADITYA BHATTACHARJEE

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DEPARTMENT OF MECHANICAL ENGINEERINGBUDGE BUDGE INSTITUTE OF TECHNOLOGY

KOLKATAJUNE, 2016

CERTIFICATE

I hereby certify that the work which is being presented in the B.Tech. Major (or Minor) Project Report entitled “CASE STUDY OF A CONDEMNED BOILER & METHODS TO RE-ESTABLISH IT.”, in partial fulfillment of the requirements for the award of the Bachelor of Technology in Mechanical Engineering and submitted to the Department of Mechanical Engineering of Budge Budge Institute of Technology, Kolkata is an authentic record of my own work carried out during a period from January 2016 to July 2016 under the supervision of Prof. Debajit Banerjee ME , Jadavpur University Assistant ProfessorBudge Budge Institute of Technology

The matter presented in this thesis has not been submitted by me for the award of any other degree elsewhere.

Signature of Candidate

Roll No: 27600712006

This is to certify that the above statement made by the candidate is correct to the best of my knowledge.

Prof. Debajit Banerjee Signature of Supervisor(s)ME, Jadavpur University Date: Assistant ProfessorBudge Budge Institute of Technology

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Acknowledgements

I consider myself lucky to have the guidance of Mr. Debajit Banerjee, Assistant Professor, Department of Mechanical Engineering, and Budge Budge Institute of Technology, who took time from his busy schedule to guide me through my project constantly. I shall be ever grateful to him and owe my sincere debt to my guide.

I expressed my warm thanks to the Director Mr. Alok Saraf ; Project Co-ordinator Mr. Vedant Saraf ; Installation General Manager Mr. S.C.Chandra ; Mr. Natwar Gupta ; Mr. Debabrata Das ; Mr. Anway Chakraborty for their support and guidance at Hindustan Storage & Distribution Co. Ltd.

I would further like to thanks my co-member Mr. Argha Das who continuously supported me throughout the project and without his presence my project would have been incomplete.

I take the opportunity to express my gratitude to Prof. Debajit Banerjee , HOD In charge , Department of Mechanical Engineering, Budge Budge Institute of Technology for his continuous support he gave me by facilitating me with all requirements and taking care. I wouldn’t have been able to get through my internship without his encouragement and affection.

I take the opportunity to express my heartiest reverence to my parents who have worked very hard throughout their life to make me what I am today.

I am thankful to all who have assisted me directly or indirectly to accomplish this work.

At last but not the least, I am very grateful to the Almighty for keeping me healthy throughout the period.

Dated:

Budge Budge Institute of Technology

Kolkata

Aditya Bhattacharjee

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CONTENTS1. Introduction 62. Abstract on HSDCL 73. Definition of Boiler 84. Specification of Boiler 8-95. Scope of works for repairing & re-establishment of the condemned

boiler 10-175.1. Study of the boiler process & its accessories 105.2. Scope of work for boiler maintenance & repairing 135.3. Scope of work after renovation to start-up the boiler 17

6. Combustion Analysis 18-246.1. Combustion 196.2. Parameters that are measured in Combustion Analysis 216.3. Roles of the parameters 21

7. Measurement Tools 25-277.1. Manual Gas Measurements 25 I. Orsat Analyser 7.2. Portable Electronic Instruments 26 II. Combustion Analysis Calculator 7.3. Continuous Emission Monitors 27

8. Calculations 28-348.1. Excess Air 288.2. Carbon dioxide concentrations 288.3. Determining combustion efficiency 298.4. Temperature measurements 328.5. Draft measurements 328.6. Oxygen reference concentration calculations 338.7. Emission rate calculations 34

9. Boiler Tune-up 35-3910. Conclusion 4011. References 41

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1. INTRODUCTION

Boiler is one of the most important devices in a power plant or in industries where a source of stream is required as a source of heat.It is the device used to create stream by applying heat energy to water and the heat is supplied from the combustion of fuel. Hence brake down of boiler at any time may leads to severe damage to the industrial processes. Hence our project reflects the detail procedures to re-establish and start-up a condemned boiler such that it fulfil the industrial need by maximizing the economy while maintaining fuel economy.

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2. ABSTRACT ON HSDCL

Hindustan Storage & Distribution Company Ltd is a Public incorporated on 07 December

1982. It is classified as Non-govt. Company and is registered at Registrar of Companies,

Kolkata.

Directors of Hindustan Storage & Distribution Company Ltd are Alok Saraf, Sawarmal

Agarwal.

This company is basically an Oil Storage & Distribution Company which import and exports

a various kind of edible oils, lube oils and chemicals. The products are stored in several tank

with capacity range 500 kl to 8000 kl. The company have pipelines of 2.5 Km almost from

Jetty to their storage tank.

Product Type : CPO- Crude Palm Oil

RBDPO- Refined Bleached Deodorized Palm Oli

LAB- Linear Alkyl Benzene

LUBE- Lubricant Oil Ketrul D-80

SUPER SPIRIT

Requirement of Boiler :

The products like CPO & RBDPO which are stored in the company have slip melting

point at about 35 degree centre grade .That means during winter seasons as the atm.

temperature falls below 35 degrees they starts solidifying and about 15-16 degrees of

atmospheric temperature the oils get solidified. Hence hot steam under pressure is used to

melt the oils. To generate the hot stream a package boiler REVOMAX PLUS is installed

in the site.

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3. DEFINATION OF BOILER:A boiler is an enclosed container that provides a mean from heat of combustion to be

transferred to the working medium (water) until it become heated or convert in steam. The

heated steam can be utilized for transferring the heat in several processes that consume the

heat of the stream and turns in work or just to heat another substance.

4. SPECIFICATION OF REVOMAX PLUS (STEAM GENERATOR):

Model: R*D-850/164

Type: Package stream generator

Manufacturing Year: 2003

Fuel: Furnace Oil

Rating: 415V ; 3 Phase ; 50 HZ

Capacity: 850 kg/hr

Design pressure:10.54 -17.50 kg/cm^2

Fuel Firing System: Pressure Jet-Reverse Flue, Dual

Block

Make: Thermax Ltd.

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SPECIFICATION OF REVOMAX BOILER:

Product Features

Efficiency of 88% on NCV

Reverse fFlame technology

Unique patented membrane design

Built-in heat recovery device

Membrane design allows large tube diameter for coil enabling better steam dryness,

less frequent de-scaling, longer coil life and minimum downtime

Unique economiser - optimiser design ensures maximum heat recovery without

possibility of feed water pump failure due to boiling/ vapour causing cavitations and

pump failure

Unique circulation burner design prevents leakage and eliminates fire hazard

Ceramic wool refractory allows fast cooling of top plate and easy maintenance

Easy access to all parts requiring maintenance

Powder-coated, well-lit control panel for better life in industrial environment and easy

monitoring

Operating Range >Capacities: From 100 to 850 Kg/hr

Design pressure: From 10.54 to 15.00 Kg/cm² (g)

Firing fuels: Light oil, gas or dual fuel

The Revomax series incorporate a host of features that make them the first choice in their

capacity range.

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5. SCOPE OF WORKS FOR REPAIRING & RE-ESTIBLISHMENT OF

THE CONDEMED BOILER:

A. Detail study of the process and boiler accessories

B. Renovation & repairing works

C. Scope of works after renovation to start-up the boiler.

5.1 STUDY OF BOILER PROCESS AND ITS ACCESSORIES

5.1.1 PROCESS: The basis principal of boiler is to convert water to steam by

utilizing the heat of combustion of fuel.

Water-steam cycle: During the whole process water from the water tank flows

through the G.I pipe to the water softeners where the hard water gets converted to soft

water by ion exchange. From there the water enters the heat optimizer where its gets

heated and then it entersl;l; the economizer where it gets pre-heated by the heat of the flue

gas and hence heat is being recovered from the flue gas that enhance the efficiency. From

the economizer water again flows through the heat optimizer to the transparent water

filter what it gets filtered and then reciprocating feed water pump pumps the water to the

inner coils of the combustion chamber. As the water flows through the combustion

chamber it gets heated until it is converted into steam which is released to the steam line

at desired rate.

Fuel cycle: Furnace Oil is used as the fuel for the boiler. The oil is initially stored in

the fuel tank which is made up of mild steel. As the fuel pump runs suction is generated

in the fuel pipeline as a result of it the fuel flows through the pipe .A fuel filter is fitted

near the fuel pump and as the fuel pass the filter the impurities get filtered and the pure oil

is transferred to the fuel pre-heater where it is electrically heated to some specific

temperature before it flows to the burner assembly.

Firing Mechanism: The fuel is pumped to the burner gun. where it is atomized to

fine droplets in presence of stream of air as it pass through the nozzle. In the gun there is

a pair of electrodes for producing the spark. So as the air-fuel mixture passes through tip

of the nozzle the electrodes produce spark and combustion take place.

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5.1.2. BOILER ACCESSORIES:

Combustion Chamber: It internal space of the boiler where combustion take place.

Steam coil: The coil through which the water circulates and heats up to form stream .It is made up of mild steel.

Economizer: Heat exchanger (shell tube type) to preheat the feed water before it enters the combustion chamber by recovering the heat of flue gas.

Heat Optimizer: Preheat the water entering the economizer and optimize the temperature of water leaving the economizer and entering the feed water pump.

Feed water pump: 3 cylinder, positive displacement, reciprocating pump to feed the water to the steam coil at desired pressure and rate.

Centrifugal fuel pump: It is used to pump the oil from the oil tank to the combustion chamber.

Burner Gun: It is a heating device which burns the fuel oil. The fuel is atomized through the nozzle under pressure and it is ignited by electric sparks generated by 2 sets of electrodes.

Oil Filter: They minimize the dirt and water that can enter into the boiler fuel system. This not only maximizes the efficiency of your furnace but its longevity as well.

Water Softeners: Removes the minerals calcium, magnesium and metal cations from hard water. This is very essential to eliminate the formation of scales on the equipment’s.

Centrifugal Blower: It is a forced draught fan which runs on a motor to supply require amount of air for complete combustion of fuel.

Oil Pre-heater: It is a simple electric coil heater which is insulated from outside. It heat the incoming oil before it enters into the burner gun.

Pressure Gauges: To determine the pressure of fuel and stream at different section.

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Combustion Chamber

EconomizerCOILFeed Water Pump

OIL FILTER

BURNER GUN

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5.1.3. PROCESS FLOW CHART:

5.2 SCOPE OF WORK FOR BOILER MAINTENANCE &

REPAIRING

5.2.1. Dismantling of Boiler & its accessories: OBJECTIVE: To dismantle all the boiler internal parts and its accessories for

analysis so that if any defect found or any component is malfunctioning it can be

repaired.

EQUIPMENT OBSERVATION TEST STATUS

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PERFORMED

OUTER JACKETDamaged due to

rustingReplaced

INNER JACKET In good shape Found ok

INTERMEDDIATE

JACKET

Ceramic

insulations are

damaged

To be renewed

STREAM COILRusting and scales

formationHydrostatic test Found ok

ECONOMIZER

Outer and inner

tubes corroded

due to rusting

Complete set-up has to

be replaced

CONTROL PANELAll circuits are

intact

Checked by

electriciansFound ok

PUMPSUnused for long

days

Operated on no-

load condition

Shaft was moving at

required

speed(rpm).Workable

SENSORS damagedChecked by

electriciansReplaced with new one

INSULATIONS

Glass wool

insulations are

totally damaged

Replaced

BURNER ASSEMBLYIn good shape

electrodes are okFound ok

PRESSURE GAUGES working Found ok

WATER SOFTNERS

Anion and cation

exchanger are

damaged

Tested by

specialized

technicians

Replaced

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PROCEDURE:

Skilled technicians from Thermax Limited headed the operation.

They used overhead chain pulley to lift up the bulgy components like economizer

coil, inner and outer jackets.

Gas cutter and plasma cutter were used.

5.2.2. PRESSURE TEST OF DUCTS & STREAMLINE:

OBJECTIVE : It is the final check of mechanical integrity of the whole system and

should be followed religiously as after this activity the piping system has to be

commissioned.

PREPEARATION & TESTING : Pressure gauges should be fitted at both low and high point when testing large

volume systems.

The system shall be filled from the lowest available point; all vents and high

point connections shall be open during this operation to allow the air in the

system to vent off.

After the system has been completely vented all vents and drains should be

plugged or blinded. Verify that Valves are in place and open/closed as

required.

Maintain pressure for 10 minutes and then gradually increase pressure in steps

of one tenth of the test pressure until the test pressure is attained. The

recommended practice of a QC inspector is to walk through the whole piping

system and check for leaks. Every single length of piping, welds, bolted

connections shall be visually examined for any leakage. Duration of this

activity varies with the span of piping system. For larger piping system time

taken for this activity is enough to clear the hydrostatic test. In case of piping

system having smaller span, 1 hour time may be made as standard practice.

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Whenever a leak is found from flanged connection, it is advisable not to

perform any tightening before the system pressure is brought down to at least

70%. A leak from a weld joint, piping base metal or any other location which

may require hot work shall only be addressed after de-pressurizing the piping

under test.

After any leaks have been repaired the system shall again be pressurized to the

test pressure in stages.

The test should be witnessed and accepted by a third party, client

representative or a responsible person within the company and signed as

accepted.

Pressure and ambient temperatures should be recorded throughout the

complete test cycle. These charts should form part of the Hydrostatic Test

Documentation.

On completion of the test, the system shall be depressurized by controlled

means and all vents opened prior to draining of the system to avoid any

vacuum within the system.

PROCESS :

Compressed hot air at around 50 degree centigrade was allowed to pass

through the stream line while all the valves were closed.

Pressure gauges and temperature recorder were installed at the inlet and

outlet of the pipelines.

The operation was commenced at 1.5 times higher than the design pressure

of the system.

RESULT :

Pressure drop, temperature drop & several leakages were found. Therefore hence total

insulation has to be replaced & the pipeline has to be repaired by arc welding.

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5.3 Scope of works after renovation to start-up the boiler

1. COMBUSTION/FLUE GAS ANALYSIS

2. BOILER TUNE-UP

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6. COMBUSTION ANALYSIS

6. COMBUSTION ANALYSIS

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6.1 COMBUSTION: Combustion occurs when fossil fuels, such as natural gas, fuel oil,

coal or gasoline, react with oxygen in the air to produce heat. The heat from burning fossil

fuels is used for industrial processes, environmental heating or to expand gases in a cylinder

and push a piston. Boilers, furnaces and engines are important users of fossil fuels.

Fossil fuels are hydrocarbons, meaning they are composed primarily of carbon and hydrogen.

When fossil fuels are burned, carbon dioxide (CO2) and water (H2O) are the principle

chemical products, formed from the reactants carbon and hydrogen in the fuel and oxygen

(O2) in the air.

The simplest example of hydrocarbon fuel combustion is the reaction of methane (CH4), the

largest component of natural gas, with O2 in the air. When this reaction is balanced, or

stoichiometric, each molecule of methane reacts with two molecules of O2 producing one

molecule of CO2 and two molecules of H2O. When this occurs, energy is released as heat.

CH4 + 2O2 => CO2 + 2H2OReactants => Products + Heat

In actual combustion processes, other products are often formed. A typical example of an

actual combustion process is shown in Figure 1. Fuel has reacted with air to produce the

products shown on the right.

ANALYSIS: Combustion analysis is part of a process intended to improve fuel economy,

reduce undesirable exhaust emissions and improve the safety of fuel burning equipment.

Combustion analysis begins with the measurement of flue gas concentrations and gas

temperature, and may include the measurement of draft pressure and soot level. To measure

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gas concentration, a probe is inserted into the exhaust flue and a gas sample drawn out.

Exhaust gas temperature is measured using a thermocouple positioned to measure the highest

exhaust gas temperature. Soot is measured from a gas sample drawn off the exhaust flue.

Draft is the differential pressure between the inside and outside of the exhaust flue.

Once these measurements are made, the data is interpreted using calculated combustion

parameters such as combustion efficiency and excess air. A more in depth analysis will

examine the concentration of the undesirable products described earlier.

OBJECTIVE:

1. Improve Fuel Economy: The largest sources of boiler heat losses are shown Figure 2.

Heat energy leaving the system exhaust flue (or stack) is often the largest single source of lost

fuel energy and is made up of the Dry Gas loss and Latent Heat Loss. Although some flue

loss is unavoidable, an equipment tune-up using combustion analysis data can often

significantly reduce this source of heat loss and save fuel costs by improving fuel efficiency.

Table 1 gives examples of yearly cost savings that can be realized by improving equipment

efficiency by five percent.

2. Reduction Emission: Carbon monoxide, sulfur dioxide, nitrogen oxides and particles are

undesirable emissions associated with burning fossil fuels. These compounds are toxic,

contribute to acid rain and smog and can ultimately cause respiratory problems. Federal and

state laws govern the permissible emission rates for these pollutants under the guidance of the

Clean Air Act and oversight of the federal Environmental Protection Agency (EPA ).

Combustion analysis is performed to monitor toxic and acid rain forming emissions in order

to meet these federal, state and local regulations.

3. Improve Safety: Good equipment maintenance practice, which includes combustion

analysis, enables the boiler technician to fully verify and maintain the equipment operating

specifications for safe and efficient operation. Many boiler manufacturers suggest that flue

gas analysis be performed at least monthly. Boiler adjustments that affect combustion will

tend to drift with time. Wind conditions and seasonal changes in temperature and barometric

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pressure can cause the excess air in a system to fluctuate several percent. A reduction in

excess air can cause, in turn, a rapid increase of highly toxic carbon monoxide and explosive

gases, resulting in rapid deterioration in system safety and efficiency. Low draft pressures in

the flue can further result in these combustion gases building up in the combustion chamber

or being vented

indoors. Excessive draft pressures in the flue also can cause turbulence in the system. This

can prevent complete combustion and pull explosive gases into the flue or cause flame

impingement and damage in the combustion chamber and to the heat exchanger material.

6.2 PARAMETERS THAT ARE MEASURED IN COMBUSTION ANALYSIS: Combustion analysis involves the measurement of gas concentrations, temperatures and

pressure for boiler tune-ups, emissions checks and safety improvements. Parameters that are

commonly examined include:

Oxygen (O2)

Carbon Monoxide (CO)

Carbon Dioxide (CO2)

Exhaust gas temperature

Supplied combustion air temperature

Draft

Nitric Oxide (NO)

Nitrogen Dioxide (NO2)

Sulfur Dioxide (SO2)

6.3 ROLES OF THE PARAMETERS:1. Oxygen, Carbon monoxide, Carbon dioxide:

During combustion the oxygen in the air supplied reacts with the carbon & hydrogen

of the fuel to form CO2 & H2O. Under ideal conditions, the only gases in the exhaust

flue are CO2, water vapor and nitrogen from the combustion air. When O2 appears in

the flue exhaust, it usually means that more air (20.9 percent of which is O2) was

supplied than was needed for complete combustion to occur. Some O2 is left over. In

other words, the measurement of O2 gas in the flue indicates that extra combustion

air, or Excess Air, was supplied to the combustion reaction. This is demonstrated in

Figure 3 where the bar on the right represents the exhaust gas composition.

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When too little air is supplied to the burner, there is not enough oxygen to completely

form CO2 with all the carbon in the fuel. Instead, some oxygen combines with carbon

to form carbon monoxide (CO). CO is a highly toxic gas associated with incomplete

combustion and efforts must be made to minimize its formation. This effort goes

hand-in-hand with improving fuel efficiency and reducing soot generation. This

formation of CO gas is illustrated in Figure 4.

2. TEMPERATURE:

Exhaust Gas Temperature and Supplied Combustion Air TemperatureHeat leaving the exhaust flue with the hot gases is not transferred to do useful work, such as

producing steam. This heat loss becomes a major cause of lower fuel efficiency. Because the

heat content of the exhaust gas is proportional to its temperature, the fuel efficiency drops as

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the temperature increases. An example of efficiency loss due to the increase in stack gas

temperature is shown in Figure 6.

3. DRAFT: Draft refers to the flow of gases through the heat generating equipment,

beginning with the introduction of air at the back of the burner. Once combustion occurs, the

heated gas leaves the combustion chamber, passes heat exchangers and exits the exhaust

stack. Depending upon the design of the equipment, draft is natural, meaning combustion air

is pulled in by buoyant heated gases venting up the stack, or it is mechanical, meaning air is

pushed or pulled through the system by a fan. Often, draft relies on a combination of both

natural and mechanical means. Adequate draft is typically verified by measuring the pressure

in the exhaust stack. Measurement is important since environmental influences such as

changes in barometric pressure and ambient temperature can influence the flow. Typical draft

pressures are in the range of –0.5 to 0.5 inches of water column.

4. Nitrogen Oxides (NOx): Nitrogen oxides, principally nitric oxide (NO) and nitrogen

dioxide (NO2), are pollutant gases that contribute to the formation of acid rain, ozone and

smog. The NO concentration is often measured alone, and the NO2 concentration is generally

assumed to comprise an additional five percent of the total nitrogen oxides.

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5. Sulfur Dioxide (SO2): Sulfur dioxide combines with water vapor in the exhaust to

form a sulfuric acid mist. Airborne sulfuric acid is a pollutant in fog, smog, acid rain and

snow, ending up in the soil and ground water. Sulfur dioxide itself is corrosive and harmful to

the environment.

Sulfur dioxide occurs when the fuel contains sulfur and where the emission levels are directly

related to the amount of sulfur in the fuel. The most cost-effective way to reduce sulfur

emissions is to select a low-sulfur or de-sulfured fuel.

6. Hydrocarbons (HCs)/Volatile Organic Compounds (VOCs): Organic

compounds are sometimes present in the combustion exhaust products because of incomplete

combustion. Hydrocarbons (HCs), or volatile organic compounds (VOCs), are best reduced

through proper burner maintenance and by maintaining the proper air/fuel mixture

7. Soot :Soot is the black smoke commonly seen in the exhaust of diesel trucks, and is present

whenever fuel oils or solid fuels are burned. Excessive soot is undesirable because it indicates

poor combustion and is responsible for coating internal heat transfer surfaces, preventing

good thermal conductivity. Over time, serious damage to the heat exchanger can occur.

Soot is primarily unburned carbon, and is formed for the same reasons CO is formed

insufficient combustion air, poor mixing and low flame temperature. As with CO, it is usually

impossible or impractical to entirely eliminate soot formation for some fuel types.

7. MEASUREMENT TOOLS

7.1 Manual Gas Measurements

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1. ORSAT ANALYSER:

DEFINATION: The Orsat analyzer is a gas concentration analysis tool typically used to

manually sample CO2, O2 and CO from the flue of a combustion system

OBJECTIVE: The Orsat analyzer determines the gas concentrations from a sample of gas

extracted from the flue and bubbled through solutions of reagents that selectively absorb each

gas. By measuring the decrease in gas volume over the liquid reagents, the amount of gas

absorbed is indicated.

PROCEDURE:

1. The sample of flue gas is taken and allowed to pass through the orsat analyzer.

2. Expelling excess gas.

3. Absorption of the gas through contact with chemical by rising and lowering the leveling

bottle.

Gas then passed into KOH (potassium hydroxide) solution pipette to absorb CO2 to

form potassium carbonate by the reaction 2KOH + CO2 ↔ K2CO3+ H2O at ambient

conditions.

After confirming no change in the volume of reservoir than gas led to alkaline

pyrogallic acid containing pipette to absorb oxygen by the reaction:

2C6H3(OH)3(pyrogallol) + 2KOH(saturated alkaline)+ O2 ↔ 4H2O + 2C5H3OCOOK

and a physical color change is observed.

Finally carbon monoxide is absorbed by ammoniacal cuprous chloride pipette by the

reaction,

2CuCl + 2CO →(in NH3 solution)→ [CuCl(CO)]2

4. .Finally measuring the percentage of component by equating the water levels, repeating

(3 and 4) with other two absorber chambers.

RESULTS:

Potassium Hydroxide absorbs Carbon dioxide Alkaline pyrogalic acid absorbs Oxygen Cuprous Chloride absorbs Carbon monoxide

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NOMENCLATURE:

Md = Dry molecular weight, g/g-mole (lb/lb-mole).

%EA = Percent Excess Air.

%CO2 = Percent CO2 by volume, (dry basis).

%O2 = Percent O2 by volume, (dry basis).

%CO = Percent CO by volume, (dry basis).

%N2 = Percent N2 by volume, (dry basis).

7.2 Portable Electronic Instruments

COMBUSTION ANALYSIS CALCULATOR

OBJECTIVE:

To analyze combustion routinely for tune-up, maintenance & emission monitoring

PROCEDURE:

1.This instrument are extractive. The remove the sample from stack or flue by vacuum pressure

and the analyze the sample using electro chemical sensors.

2.Thermocouple used for the stack and flue temperature.

3.Pressure transducer is used for draft measurement.

4.On board computer performs the combustion calculations

7.3 Continuous Emission MonitorsContinuous emission monitors, or CEMS, are a class of electronic instruments designed to measure exhaust stack gases and temperature continuously. CEMs are sometimes used for combustion control, but typically are used for monitoring pollutant gas emissions as required by government regulations. CEMs can use both extractive and in-situ (sensors in the stack)

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sampling methods, and employ a variety of electronic sensor technologies for gas detection. CEMs are used most often on larger installations or when required by regulatory agencies.

A small sample of flue gas is extracted, by means of a pump, into the CEM system via a sample probe. Facilities that combust fossil fuels often use a dilution-extractive probe to dilute the sample with clean, dry air to a ratio typically between 50:1 to 200:1, but usually 100:1. Dilution is used because pure flue gas can be hot, wet and, with some pollutants, sticky. Once diluted to the appropriate ratio, the sample is transported through a sample line (typically referred to as an umbilical) to a manifold from which individual analyzers may extract a sample. Gas analyzers employ various techniques to accurately measure concentrations. Some commonly used techniques include  infrared  and  ultraviolet adsorption, chemiluminescence , fluorescence and beta ray absorption. After analysis, the gas exits the analyzer to a common manifold to all analyzers where it is vented out of doors. A Data Acquisition and Handling System (DAHS) receives the signal output from each analyzer in order to collect and record emissions data

8. CALCULATIONS:

8.1 EXCESS AIR:

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DEFINATION: The percentage of excess air needed above the theoretical amount for

complete combustion of fuel.

REQUIREMENT: Insufficient combustion air causes a reduction in fuel efficiency,

creates highly toxic carbon monoxide gas and produces soot. To ensure there is enough

oxygen to completely react with the fuel, extra combustion air is usually supplied. This

extra air, called “Excess Air,” is expressed as the percent air above the amount

theoretically needed for complete combustion. In real-world combustion, the excess air

required for gaseous fuels is typically about 15 percent. Significantly more may be

needed for liquid and solid fuels.

FORMULA:

8.2 CARBONDIOXIDE CONCENTRATION:

REQUIREMENT: Carbon dioxide (CO2) forms when carbon in the fuel combines with O2

in the combustion air. When there is just enough O2 supplied to react with the carbon in the

fuel, the CO2 concentration in the stack exhaust is at its highest level. This is generally at or

close to the ideal operating condition for the heat generating equipment. This was shown in

Figure 5.

The maximum possible CO2 exhaust concentration depends ultimately on the carbon content

of the fuel being burned.

FORMULA:

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8.3 DETERMINING COMBUSTION EFFICIENCY:

REQUIREMENT: Combustion efficiency is a measure of how effectively energy from the

fuel is converted into useful energy (e.g. to create steam). Combustion efficiency is

determined by subtracting the heat content of the exhaust gases, expressed as a percentage of

the fuel’s heating value, from the total fuel-heat potential, or 100%, as shown in the formula

below.

FORMULA 1:

STACK/FLUE HEAT LOSS = Lg+Lh+Lm+Lco

Lg = heat loss due to dry gas

Lh = heat loss due to moisture from burning hydrogen

Lm = heat loss due to moisture in fuel

Lco = heat loss from the formation of carbon monoxide

FUEL HEATING VALUE - Higher heating value(HHV) or Lower heating

value(LHV)

Heat loss due to dry gas (Lg):Lg = Wg x Cp x (Tflue – Tsupply) (The CA-CALC displays Loss as the dry

gas loss.)

Where: Wg = the weight of the flue gases per pound of as-fired fuel.

Cp = specific heat of the exhaust gas mix.

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Tflue = flue temperature

Tsupply = combustion supply air temperature

Heat loss due to H2O from combustion of hydrogen (Lh):Where the fuel has a high hydrogen content, latent heat loss from the water

formation can be very significant.

Lh = 8.936 x H x ( hl – hrw )Where: 8.936 = weight of water formed for each hydrogen atom

H = fractional hydrogen content of the fuel

hl = enthalpy of water at the exhaust temperature and pressure

hrw = enthalpy of water as a saturated liquid at fuel supply temperature

Heat loss due to moisture in fuel (Lm):

Moisture in the fuel is determined from lab analysis of the fuel and can be

obtained from the fuel supplier.

Lm = fraction fuel moisture x (hl – hrw)

Where: hl = enthalpy of water at exit gas temperature and pressure

hrw = enthalpy of water at fuel supply temperature

Heat loss due from the formation of carbon monoxide (Lco):

Carbon in the fuel reacts with oxygen to form CO first, then CO2, generating a

total of 14,540 Btus of heat per pound of carbon. If the reaction stops at CO

because of insufficient O2 or poor mixing of fuel and air, 10,160 Btus of

energy are lost.

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FORMULA 2: Combustion calculations using the Siegert formula

The Siegert formula is widely used in Europe to determine flue losses (qA) and efficiency.

Efficiency = 100 – qAWhere: qA = flue lossTs = flue temperatureTa = supply air temperatureO2 = measured volumetric oxygen concentration expressed as a percentA2, B = fuel dependent constants

The constants A2 and B are derived from the fuel composition. In Germany, the following

values are prescribed for some common fuels:

8.4 TEMPERATURE MEASUREMENTS:

OBJECTIVE: Measurements of the stack gas temperature and the combustion air

temperature are required to establish the heat loss from the exhaust gases and determine

combustion efficiency.

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MEASURING INSTRUMENT: A bimetallic thermocouple probe is typically used to

measure the stack temperature.

PROCEDURE: This thermocouple probe is placed at the point of highest exhaust gas

temperature at the base of the flue and toward the center for small ducts. If the stack gas

temperature is underestimated, the operating efficiency will be overstated. When an

economizer or air heater is used, stack temperature is measured after these devices. Figure 10

shows locations for measuring both stack and combustion air temperatures.

8.5 DRAFT MEASUREMENT:

OBJECTIVE:

Draft is a measurement to ensure the combustion gases are being properly exhausted.

MEASURING INSTRUMENT:

Draft is measured using a manometer or electronic pressure transducer.

PROCEDURE : Draft is usually measured in the same location as the stack temperature

relative to the ambient space. When a draft diverter or draft hood is in the stack, a second

measurement should be taken downstream of the device.

8.6 OXYGEN REFERENCE CONCENTRATION CALCULATION:

REQUIREMENT: Excess air is measured in the flue as a percentage of O2. This excess air

dilutes the concentration of other gases measured. The measured O2 concentration, together

with the O2 reference value is used in the equation below to obtain the corrected gas

concentration. O2 reference values of 3 and 6 percent are often used, giving a corrected gas

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concentration equivalent to that at oxygen concentrations of 3 or 6 percent. When an O2

reference of zero is

Used, the gas concentration is referred to as undiluted or air free.

FORMULA:

8.7 EMISSION RATE CALCULATION:

OBJECTIVE: The emission rate calculation presented below is described in EPA Method

19. This uses the dry gas factor Fd. Dry factors are incorporated into the values found in

Table 5 below. The table values (Ft), convert the measured concentrations of emission gases

CO, NOx, and SO2 from PPM to pounds per million Btu of fuel.

FORMULA:

Where: E = Emission rate (pounds/MBtu of fuel)*Cg = Gas concentration (PPM)Ft = Emission rate conversion factor from Table 5 (below)O2 measured = Oxygen concentration from flue measurement (%)*To convert emission rate to metric equivalent units, kg/kJ, multiply E in the equation above by 2.236.**Ft units are lb/MBtu PPM.

Ft Furnace oil

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SO2 0.00153

NOx 0.00110

CO 0.00670

Note: For those familiar with Method 19, Ft is related to Fd in the following way:Ft is in units lbs/(MBtu ppm)Fd is in units scf/MBtuFt = Fd x lb/(scf ppm)

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9. BOILER TUNE-UP

9. BOILER TUNE-UP

What Is Boiler Tune-up?

• Boiler tune up refers different aspects of improving and starting up the boiler

operations.

• The tune –up activity is the act of re-establishing the air-fuel mixture for the operating

range of boiler, oxygen and unburned fuel are balanced to provide safe and efficient

combustion

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PRIMARY OBJECTIVE:

• To improve the boiler efficiency with economically consumption of fuel while

providing the desired effect.

PROCEDURE:

1) Preparation:

a) Clearly identify the target equipment along with the intent and goals of the tune-up.

b) Assemble boiler drawings and data sheets.

c) Assemble burner drawings and data sheets.

d) Assemble combustion control information.

e) Identify environmental regulations and limitations.

i) Typically nitrogen oxides (NOx) and combustible material (often identified as CO) are

specifically addressed in the emission limits.

f) Identify steam production control strategy that will be used during the tune-up.

g) Identify in-situ instrumentation and verify calibration.

h) Identify measurement locations and verify access.

i) The most common flue gas measurement location is immediately downstream of

the steam generation section of a water-tube type boiler. For a fire-tube type boiler

the flue gas sample is most commonly taken as the exhaust gases exit the boiler

proper. Establish tune-up timeframe.

2) As-found observation:

NOTE: Identification of the as-found conditions centers on measurement of the operating

parameters of the combustion process that will be modified during the tune-up process. The

primary measurements required under the Boiler Area Source Rule are flue gas oxygen

content and flue gas carbon monoxide content at the high-fire or typical operation load.

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a) Examine the combustion control components (i.e., the system controlling the air-to-

fuel ratio) and ensure it is functioning properly.

b) Examine the burner internal components and identify any defects, if applicable.

c) Examine the general boiler conditions and identify any defects.

d) Measure and record the following for each operating position of the combustion

control system.

i) Observe flame pattern, flame dimensions, and burner condition.

ii) Flue gas oxygen content.

iii) Flue gas carbon monoxide (CO) content.

iv) Flue gas emissions content (NOx, if appropriate).

(1) Additional flue gas component analysis is required when the environmental

permit specifies limits on emission components. A common regulated

emission component is nitrogen oxides (NOx).

v) Emissions control settings.

(1) Flue Gas Recirculation flow settings (if applicable).

vi) Final flue gas temperature.

e) Document any modifications completed at this point.

3) Tune-up:

The tune-up activity is the act of ensuring the burners are properly mixing the air and fuel and

of reestablishing the most appropriate amount of excess air throughout the operating range of

the boiler.

a) Tune-up each operating position of the combustion control system (from high-fire

through low-fire).

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i) Establish steady operation for the target operating point.

ii) Adjust combustion control position relationship to achieve desired combustion

characteristics.

(1) Flue gas oxygen content - target will generally be the manufacturer’s

specifications.

(2) CO content - target will generally be the manufacturer’s specifications.

(3) NOx content, if applicable – target will generally be the limit specified in the

environmental permit.

(a) Adjustments for emissions control are generally completed after

combustion adjustments are established.

iii) Measure and record the following for each operating position of the combustion

control system.

(1) Observe flame pattern, flame dimensions, and burner condition.

(2) Flue gas oxygen content.

(3) Flue gas CO content.

(4) Flue gas emissions content (NOx and others).

(5) Final flue gas temperature.

iv) Document any modifications completed at each point.

4) Document tune-up.

a) Document the tune-up including the following.

i) As-found conditions.

ii) Post tune-up conditions.

iii) Modifications and repairs completed.

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iv) Recommended investigations and modifications.

v) Identified shortcomings of the equipment.

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10. CONCLUSION

Boiler or steam generator is an integral part of most of the core industries like power plant, steel plant etc. As machines are always susceptible to damages, any problem related to boiler will hampers the total process of production or service in an industry.

We are highly honoured to be part of the project which deals with immediate steps to repair, renovate and re-establishment of small industrial package boilers. From the project we have learned basic ideas about stream generator, its working processes, requirement in industries, individual parts and their functions and the means to improve the efficiency of the boiler while maintaining the environmental laws and pollution act.

The project has immensely helped us to use our theoretical knowledge and skills in practical field while dismantling the boiler parts and analysis for any defects and needful works for their repair.

Overall it has been a great learning experience and gain a lot of experience which we can utilize in practical field in future.

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11. REFERENCES

Brochure on REVOMAX PLUS by Thermax ltd.

“Stream Generator Unites”, American society of Mechanical Engineers,

New York,1991

“Flue and exhaust gas analysis”, American society of Mechanical

Engineers, New York,1981

“Energy efficiency”

R. k. Raj put, thermal engineering

S. Domkundwar , A. v domkundwar, s. c Arrora,

power plant engineering

P. c Sharma, power plant engineering

Thermal engineering- R.S Khurmi/J.s gupta/s.chand

Thermal engineering-M.L. Mathur &Mehtal/join bros

www.google.com

www.wikipidea.com

www.slideshare.com