mohd shahrulnizam bin abu seman u

7/27/2019 Mohd Shahrulnizam Bin Abu Seman u

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ABSTRACT

Steam power plant is using fuel to generate electrical power. The used of thefuel must be efficient so the boiler can generate for the maximum electrical power.By the time the steam cycle in the boiler, it also had heat losses through some partsand it effect on the efficiency of the boiler. This project will analyze about the partslosses and boiler efficiency to find the optimum cooling water flowrate. By u sing theCUSSO NS P76 90/SP steam power plant in mechanical laboratory in UMP the data iscollect by using 4 types of cooling water flowrate that is 30001/h, 40001/h, 50001/han d 60001/h. Result of the analysis show that the optimum cooling water flowrate forsuperheated steam is 60001/h that give lowest losses, 6.1 kW and maximumefficiency that is 78.99%. This study is fulfilling the objective of analysis to find theoptimum cooling water fowrate for steam power plant in liMP.

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ABSTRAJK

Stesen janakuasa stim menggunakan bahan bakar untuk menjana tenagaelektrik. Penggunaan bahan bakar tersebut mestilah efisien supaya dandang dapatmenjana tenaga elektrik yang maksimum. Dalam ketika kitaran stim berlaku didalam pendandang, haba telah terbebas pada sesuatu bahagian dan memberi kesankepada kecekapan penggunaan pendandang tersebut. Projek mi akan menganalisistentang kehilangan haba pada sesuatu bahagian dan kecekapan pendandang untukmencari aliran air sejuk yang paling optimum. Dengan menggunakan CUSSONSP7690/S P stesen janakuasa stim di makmal mekanikal dalam UIM P data telah diambilbagi 4 jenis aliran air sejuk iaitu 30001/h, 40001/h, 50001/h and 60001/h. Keputusandari analisis menunjukan aliran air sejuk yang optimum ialah pada 60001/h yangmemb eri kehilangan haba terendah, 6.1 kW dan maksimum kecekapan iaitu 78.99%.K ajian mi mem enuhi objektifanalisis iaitU untuk m encari aliran air sejuk yang p alingoptimum untuk stesen janakuasa :stim di UMP.

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TABLE OF CONTENTS

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CHAPTER TITLE

TITLE PAGESUPERVISOR DECLARATIONSTUDENT DECLARATIONDEDICATIONACKNOWLEDGEMENTABSTRACTABSTRAKTABLE OF CONTENTLIST OF TABLELIST OF FIGURELIST OF SYMBOLLIST OF APPENDICES

PAGE

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I I

1 1 1

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v iViiviiix lixli ix ivx vi

INTRODUCTION1.1ntroduction of the title1.2 Project Objectives1.3 Project Scopes1.4 Project BackgroundLITERATURE REVIEW2.1ntroduction2.2 The Use of Steam

2.2.1 Steam is Efficient and Economic to


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Generate2.2.2nergy is Easily Transferred to the P rocess 6

2.3 The Steam-Plant C ycle 82.4 Feedwater 1 02.5 Boiler Efficiency 1 2

2.5. Iross Calorific Value 1 22.5.2et Calorific Value 1 32.6 Heat Losses 1 42.6.1eat Losses in the Flue G ases 1 52.6.2adiation Losses 1 5

2.7 Fuel for Boilers 1 62.7.1oa l 1 62.7.2il 1 72.7.3as 1 82.7.4aste as the Primary Fuel 2 82.8 Boiler Design 202.8.1oiler Types 20

2.9 CUS SONS P7690 /SP Steam Power Plant 2 12.9.1iesel Fired Stea m Boiler Unit 222.10 Types Of Blowdown 242.10.1 Boiler Blowdown Purpose 242.11 Efficiency Measurement 2 52.11.1 Cost Measurement of Steam Efficiency 262.11.2 Method to Gauge Efficiency 262.11.3 Efficiency for Low-cost Fuel 272.11.4 Steam Efficiency 28

METHODOLOGY 29

3.1 Introduction 293.2 Boiler Starts up and Shutdown Procedure 29

3.2.1tarts up Procedure 293.2.2hutdown Procedure 32

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3.3nergy Balance Ana lysis233.1 Calculation and Data Analysis43.4ooling Water Flowrate A nalysis4RESULTS AND DISCUSSION54.1 Introduction 3 54.2 Energy Balance Ana lysis .54.2.1alculation for 3000 11 h Cooling Water 3 7Flowrate Losses

4.2.2 Calculation for 4000 1/h Cooling Water 3 8Flowrate Losses4.23 Calculation for 5000 1/h Cooling Water 39Flowrate Losses4.2.4 Calculation for 6000 1/h Cooling Water 40Flowrate Losses

4.3 Cooling Water Flowrate A nalysis 424.11 Calculation for 3000 1/h Cooling Water 4 3Flowrate E fficiency4.3.2 Calculation for 4000 1/h Cooling Water 4 3Flowrate E fficiency4.3.3 Calculation for 5000 1/h Cooling Water 4 3Flowrate E fficiency4.3.4 Calculation for 6000 i/h Cooling Water 4 3Flowrate Efficiency

4.4 Discussion on Losses 4 54.5 Discussion on Boiler Efficiency 46

CONCLUSION AND RECOMMENDATION 47

5.1 Introduction 475.2 Conclusion 475.3 Recommendation 48


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REFERENCES9Appendices075


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LIST OF TABLES

TABLE NO.ITLESAG E2.1omparison of heating media with steam2.2uel oil data32.3as data34.1fficiency for each flowrate4


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LIST OF FIGURE

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PAGEFIGURE TITLEN O.2.1 Heated water2 .2 A modern boiler house package

2.3 Boiler basic cycle2 .4 The flow in the boiler2.5 Cussons steam pow er plant3.1 Simple energy balance box4.1 Losses of each cooling w ater f low4.2 . Boiler efficiency according to different cooling wa ter

flowrate

5

71 0

1 1

2 1

3 1

4 4

4 5


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LIST OF SYMBOLS

mfboiler fuel pulsesUCVUpper calorific valueQsuperheaterinput electrical energy for superheat ermairestim ate air flowCpairapproxim ates to 1.005 kJ/(kgK)Tairam bient a ir t em p(mh)feedwaterinflux of enth alpy with feedwaterm sm ass flow rateh ienth alpy of waterWturbmepower output from turbineNrotational speed of turbine, R PMTnet output on output shaft(mh)ex si.enth alpy efflux th rough th e exhaus t s tack(ma mr )sum of fuel and air m ass flowCpexspecific heat a t constant pressure for exh aus t gasT e x exhaust gas tem perature measured a t s tack outle tPaabsolute am bient inlet pressureTaabsolute am bient inlet tem perature(mh)condensateenth alpy efflux th rough th e condenserhenthalpy of condensate leaving condenserh senth alpy of boiler saturated vapors xlv


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hfwnthalpy of feedwaterpfensity of fuelCVfross calorific value of fuel


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LIST OF APPENDICES

APPENDIX TITLE PAGE

A - 1 Project Flow Chart 5 0A-2 Project Gantt chart 5 1A-3 Log D ata for 30001/h Flowrate 5 2A-4 Log Data for 400011k Flowrate 5 4A - 5 Log D ata for 50001/h Fflowrate 5 6A-6 Log Data for 60001/h Flowrate 5 8A-7 Calculated Value For 30001/H 5 9A-8 Calculated Value For 40001/H 6 2A-9 Calculated Value For 50001/H 6 5A - 10 Calculated Value For 60001/H 6 8B - 1 Plant Component and Cycle 7 1B-2 Boiler Top View 7 2B-3 Boiler Front View 7 3B-4 Valves and Steam Turbine 7 4B-5 B oiler A nd Control Panel

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CHAPTER 2

LiTERATURE REVIEW

2.1ntroductionIn this chapter, all the important information related of this project is stated.

Besides that, the literature review can give a brief explanation abo ut the steam pow erplant and its operation also the effect of the cooling water flow rate. Some of thepoints in this chapter can give extra information which is useful while doing thisproject.

2.2The Use of Steam

Steam is a critical recourse in today's industrial world. It is essential forcooling and heating of large buildings, driving equipment such as pump andcompressors and for powering ships. However, its most importance priority remainsas source of pow er for the production of electricity.

Steam is extremely valuable because it can be produced anywhere in thisworld by using the heat that comes from the fuels that are available in this area.Steam also has unique properties that are very important in producing energy. Steamis basically recycled, from a steam to water and then back to steam again, all inmanner that is nontoxic in nature.

The steam plant of today are a combination of complex engineered systemthat work to produce steam in the most efficient manner that is economically


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feasible. Whether the end product of this steam is electricity, heat or a steam processrequired to develop a needed product such as paper, the goal is to have that productproduced at the lowest cost possible. The heat required to produce the steam is asignificant operating cost that affects the ultimate cost of the end product. (Everett,2005)

2.2.1 Steam is Efficient and Economic to Generate

Water is plentiful and inexpensive. It is non-hazardous to health andenvironme ntally, sound. In its gaseous form , it is a safe an d efficient energy carrier.Steam can hold five or six times as much potential 'energy as an equivalent mass ofwater.

When water is heated in a boiler, it begins to absorb energy. Depending onthe pressure in the boiler, the water will evaporate at a certain temperature to formsteam. The steam contains a large quantity of stored energy which will eventually betransferred to the process or the space to be hea ted.

It can be generated at high pressures to give high steam temperatures. Thehigher the pressure, the higher the temperature. More heat energy is containedwithin high tempe rature steam so its potential to do w ork is greater.

Figure 2.1: Heated water


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1odern shell boilers are compact and efficient in their design, using multiplepasses and efficient burner technology to transfer a very high proportion ofthe energy contained in the fuel to the water, with minimum emissions.

ii. The boiler fuel may be chosen from a variety of options, includingcombustible waste, which makes the steam boiler an environmentally soundoption amongst the choices available for providing heat. Centralized boilerplant can take advantage of low interruptible gas tariffs, because any suitablestandby fuel can be stored for use wh en the gas supply is interrupted.

iii. Highly effective heat recovery systems can virtually eliminate blowdowncosts, return valuable condensate to the boiler house and add to the overallefficiency of the steam and condensate loop.The increasing popularity of Combined Heat and Power (CHIP) systems

demonstrates the high regard for steam systems in today's environment and energy-conscious industries. (Everett, 2005)

2.2.2 Energy is Easily Transferred to the Process

Steam pro vides excellent heat transfer. W hen the steam reac hes the plant, thecondensation process efficiently transfers the heat to the product being heated.

Steam can surround or be injected into the product being heated. It can fillany space at a uniform temperature and will supply heat by condensing at a constanttemperature; this eliminates temperature gradients which may be found along anyheat transfer surface - a problem which is so often a feature of high temperature oilsor hot water heating, and may result in quality problems, such as distortion ofmaterialseingried.Because the heat transfer properties of steam are so high, the required heat transferarea is relatively small. This enables the use of more compact plant, which is easierto install and takes up less space in the plant. A modern packaged unit for steamheated hot water rated to 1200 kW and incorporating a steam plate heat exchanger


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and all the controls, requires only 0.7 rn2 floor spaces. In comparison, a packagedunit incorporating a shell and tube heat exchanger would typically cover an area oftwo to three times that size.

Figure 2.2: A mo dern boiler house package

Table 2.1: Com parison of heating media with steamSteamot Waterigh Tem p erature Oils I

High heat content Latent heat approximately2100 kJ/kg

Inexpensive Some water treatment costsGood hea t transfer

coefficientsHigh pressure requiredfor high temperatures

Moderate heat contentSpecific heat 4.19 kJ/kgC

Inexpensive Only occasional dosing

Moderate coefficients

High pressure neededfor high temperatures

Poor heat contentSpecific heat often1.69-2.93 kJ/kgC

Expensive

Relatively poorCoefficients

Low pressures onlyto get high temperatures

No circulating pum psirculating pum psirculating pumpsrequiredequiredequiredSmall pipesarge pipesven larger pipes


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Easy to control with two way valves

Temperature breakdown is easy through a reducing valve

Steam traps required

Condensate to be handled

Flash steam available

Boiler blowdownnecessaryW ater treatment required to prevent corrosion

Reasonable pipeworkrequired

No fire risk

System ve ry flexible

More complex to control -three way valves ordifferential pressure valvesmay be req uired

Temperature breakdownmore difficult

No steam traps required

No condensate handling

No flash steam

No blowdown necessary

Less corrosion

Searching m edium,welded or flanged jointsusual

No fire risk

System less flexible

More com plex to control - three way valves ordifferential pressure valves may be required.

Temperature breakdown more difficult

No steam traps required

No condensate handling

No flash steam

No blowdown necessary

Negligible corrosion

Very searching medium,welded o rilanged joints usual

Fire risk

System inflexible

2.3 The Steam-Plant Cycle

The simp lest steam cycle of practical value is called the Rankine cycle, wh ichoriginated around the p erformance of the steam engine. The steam cycle is importantbecause it connects processes that allow heat to be converted to work on aContinuous basis. This simple cycle was based on dry saturated steam being supplied


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by a boiler to a power unit such as a turbine that drives an electric generator. Drysaturated steam is at the temperature that corresponds to the boiler pressure, is notsuperheated, and does not contain m oisture. The steam from the turbine exhausts to acondenser, from w hich the condensed steam is pumped back into the boiler. It is alsocalled a condensing cycle, and a simple sche matic of the system is shown in Fig. 2.3.

This schematic also shows heat (Qin) being supplied to the boiler and agenerator connected to the turbine for the production of electricity. Heat (Qout) isremoved by the condenser, and the pump supplies energy (Wp) to the feedwater inthe form of a pressure increase to allow it to flow through the boiler.

A higher plant efficiency is obtained if the steam is initially superheated, andthis means that less steam and less fuel are required for a specific output.(Superheated steam has a temperature that is above that of dry saturated steam at thesame pressure and thus contains more heat content, called enthalpy, Btu/1b.) If thesteam is reheated and passed through a second turbine, cycle efficiency alsoimproves, and moisture in the steam is reduced as it passes through the turbine. Thismoisture reduction minimizes erosion on the turbine blades.

When saturated steam is used in a turbine, the work required rotating theturbine results in the steam losing energy, and a portion of the steam condenses asthe steam pressure drops. The amount of work that can be done by the turbine islimited by the amount of moisture that it can accept without excessive turbine bladeerosion. This steam moisture content generally is between 10 and 15 percent.Therefore, the m oisture content of the steam is a limiting factor in turbine design.

With the addition of superheat, the turbine transforms this additional energyinto work without forming moisture, and this energy is basically all recoverable inthe turbine. A rehea ter often is used in a large utility. (Kenneth, 2005)


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v y p'Ou1Figure 2.3: Boiler basic cycle

2.4 Feedwater

The feedwater system requires accessories to supply the correct amount ofwater in the proper condition to the boiler. A feedwater accessory is equipment thatis not directly attached to the boiler that controls the quantity, pressure, and/or tore ofwater supplied to the boiler. Maintaining the correct level of water in the boiler iscritical for safety and efficiency. If the water level in the boiler is too high, water canbe carried over into steam lines, which can lead to water hammer and line rupture. Ifthe water level in the boiler is too low, heat from the furnace cannot be properlytransferred to the water. This can cause overheating and damage to boiler tubes andheating surfaces. Significant damage from over heating can lead to a boilerexplosion.

Feedwater is treated and regulated automatically to meet the demand forsteam.Valves are installed in feedwater lines to permit access for maintenance and repair.The feedwater system must be capable of supplying water to the boiler in allcircumstances and includes feedwater accessories required for the specific boilerapplication, In a steam heating system.) Heat necessary for providing comfort in the

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H E A T I N GU N I TS T E A MT R A P C O N D E N S A T ER E T U R N L IN E

, -VENT

C H E C K\ V A L V ES T O PV A L V E

" - BOILER

" -- C H E C KV A L V ES T O PV A L V E

\ FE E D W A T E RL I N E

R I S E RI " ' 11-MA IN STEAM/ S T O P V A L V ES T E A ML I N E T O O T H E R

S T E A M H E A T I N GE Q U I P M E N TW A T E R C O N D E N S A T ELEVEL-M A I NETURN TANKSS T E A MHEADER F E E D W A T E RP U M P Ibuilding starts at the boiler. Water in the boiler is heated and turns to steam. Steamleaves the boiler through the main steam line (boiler outlet) where it enters the mainsteam header-. From the main steam header, main branch lines direct the steam up ariser to the heating unit (heat exchanger).Heat is released to the building space as steam travels through the heatingunit,Steam in the heating unit coals and turns into condense. The condensate is separatedfromt the steam by a steam trap that allows condensate, but not steam to pass. Thecondensate is directed through the condenser return line to the condensate returntank. The feedwater pump pumps the condensate and/or water back to the boilerthrough check valves and stop valves on the feedwater line. Feedwater enters theboiler and is turned to steam to repeat the process. (Kenneth, 2005)

Figure 2.4: The flow in the bo iler


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2.5Boiler E fficiency

Boiler Efficiency may be indicated byi. Combustion Efficiency indicates the burners ability to burn fuel measured

by unburned fuel and ex cess air in the exhau stii. Therm al Efficiency - indicates the heat excha ngers effectiveness to transfer

heat from the com bustion process to the water or steam in the boiler,exclusive radiation and convec tion losses

iii. Fuel to Fluid Efficiency - indicates the overall efficiency of the boilerinclusive thermal efficiency of the heat exchanger, radiation and conv ectionlosses - output divided by input.Boiler Efficiency is in general indicated by either Thermal Efficiency or Fuel

to Fluid Efficiency depe nding the context. (Chattopadhyay, 2005)

2.5.1 Gross Calorific Value

This is the theoretical total of the energy in the fuel. How ever, all commo nfuels contain hydrogen, which burns w ith oxygen to form wa ter, which passes up thestack as steam.

The gross c alorific value of the fue l includes the ene rgy used in evapo ratingthis water. Flue gases on steam boiler plant are not condense d; therefore the actualamount of heat available to the boiler plant is reduced.

Acc urate control of the am ount of air is essential to boiler efficiency:i. Too m uch air will cool the furnace, and carry aw ay useful heat.ii. Too little air and combustion will be incomplete, unburned; f4O will, be

carried over and smok e may be produced.


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Tab le 2.2:: Fuel oil dataOil Type -Grade Gross calorif ic value (MJ/l[light -E 4 0 . 1Medium -F 40.6Heavy -G 4 1 . 1Bunker -H 41 .8

Table 2.3: Gas dataG a s T y pe Gross ca lorif ic va lue (Mi /rn at NT PNatura l 38 .0Propane 93.0Butane 122.0

2.5.2 Net Calorific Value

This is the calorific value of the fuel, excluding the energy in the s teamdischarged to the s tack, and is the f igure gen era l ly used to ca lcula te boi le refficiencies. In broad term s:

Net calorif ic value z Gross calorific value - 1 0%

F u e lAirombustionThe combustion process:N !jWhere:C CarbonH = Hydrogen0 = O x y g enN = N it rogen

HeatI1O2 H20f-

Accurate control of the am ount o f air is essential to boiler effic iency:i . Too m uch air will cool the furnace, and carry aw ay useful heat .

ii . Too little air and combustion will be incomplete, unburned fuel will becarr ied over and sm oke may be produced.


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In practice, however, there are a num ber of difficulties in achieving perfect(stoichiometric) combustion:

i. The con ditions around the bu rner will not be perfect, and it is impossible toensure the completematching of carbon, hydrogen, and oxygen molecules.

ii. Som e of the oxygen m olecules will comb ine with nitrogen m olecules to formnitrogen oxides (NO .).To ensure complete combustion, an amount of 'excess air' needs to be

provided. This has an effec t on boiler efficiency. The c ontrol of the air/fuel mixtureratio on many existing smaller boiler plants is 'open loop'. That is, the burner willhave a series of cams and levers that have been calibrated to provide specificamounts of air for a particular rate of firing.

Clearly, being mechanical items, these will wear and sometimes requirecalibration. They must, therefore, be regularly serviced an d calibrated. On largerplants, 'closed loop' systems may b e fitted which use oxygen sen sors in the flue tocontrol combustion air dampers.

Air leaks in the boiler com bustion chamb er will have an adverse effect on theaccurate control of combustion. (Nag, 2005)

2.6eat LossesHaving discussed combustion in the boiler furnace, and particularly the

importance o f correct air ratios as they relate to complete and efficient comb ustion, itremains to review other po tential sources of heat loss and inefficiency. (Nag, 2005)


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2.6.1 Heat Losses in the Flue :Gases

This is probably the biggest single source of heat loss, and the EngineeringManager can reduce much of the loss. The losses are attributable to the temperatureof the gases leaving the furnace. Clearly, the hotter the gases in the stack, the lessefficient the boiler. The gases m ay be too hot for one of tw o reasons

1. The burner is producing more h eat than is required for a specific load on theboiler:

i. This means that the burner(s) and damper mechanisms requiremaintenance a nd re-calibration.

2. The hea t transfer surfaces within the boiler are no t functioning correctly, andthe heat is not being transferred to the water:i.his means that the heat transfer surfaces are c ontaminated, andrequire cleaning.Some care is needed here - Too much cooling of the flue gases may result intemperatures failing below the 'dew point' and the potential for corrosion is increasedby the formation of

i. Nitric acid (from the nitrogen in the air used for com bustion).ii. Sulphuric acid (if the fuel has a sulphur content.iii. Water.

2.6.2 Radiation Losses

Because the boiler is hotter than its environment, some heat will betransferred to the surroundings. Damaged or poorly installed insulation willgreatly increase the potential heat losses. A reasonably well-insulated shell or water-tube boiler of S M W or more w ill lose between 0.3 and 0.5% of its energy to thesurroundings.

This may not appear to be a large amount, but it must be remem bered that

mohd shahrulnizam bin abu seman u

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