3195 292334 Boiler Performance

8/12/2019 3195 292334 Boiler Performance

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ENERGY PERFORMANCE

ASSESSMENT

OF BOILERS


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Introduction

Performance of the boiler, like

efficiency and evaporation ratioreduces with time, due to

1. Poor combustion,

2. Heat transfer fouling

3. Poor operation and maintenance.

4. Deterioration of fuel quality andwater quality also leads to poorperformance of boiler.


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IntroductionEfficiency testing helps us to find out

how far the boiler efficiency driftsaway from the best efficiency.

Any obsered abnormal deiations couldt!erefore be inestigated to pinpointt!e problem area for necessarycorrectie action. Hence it is necessary

to find out t!e current leel ofefficiency for performance ealuation,w!ic! is a pre requisite for energy

conseration action in industry.


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Purpose of the Performnce Test

1.To find out the efficiency of the boiler2.To find out the Evaporation ratio

The purpose of the performance test is todetermine actual performance and efficiencyof the boiler and compare it with design values

or norms. It is an indicator for tracking daytoday and seasontoseason variations inboiler efficiency and energy efficiencyimprovements.


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Performnce Terms nd

!efinitions


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Reference Stndrds

British stndrds" BS#$%& '(#)

ASME Stndrd& PTC*$*' Po+erTest Code for Stem Genertin,

-nits

IS #)%.& Indin Stndrd for

Boi/er Efficienc0 Testin,


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contd11

The efficiency of a boiler is (uoted as the ) of

useful heat a*ailable" e'#ressed as a #ercenta!eof the total ener!y #otentially a*ailable by

burnin! the fuel. This is e2pressed on the 3sis

of ,ross c/orific 4/ue 5GC671


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contd11

This deals with the com#lete heat balance and it

has two #arts:

. Prt Ideals with standard boilers" where the

indirect method is s#ecified

. Prt IIdeals with com#le' #lant where there are

many channels of heat flow. In this case" both the

direct and indirect methods are a##licable" in

whole or in #art.


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ASME Stndrd& PTC*$*'

Po+er Test Code for Stem

Genertin, -nits

This consists of

. Prt One: +irect method $also called as

In#ut ,out#ut method%

. Prt T+o: Indirect method $also called as-eat loss method%


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IS #)%.& Indin Stndrd for

Boi/er Efficienc0 Testin,

ost standards for com#utation of boiler efficiency"includin! IS #)%.and BS#$%are desi!ned for s#ot

measurement of boiler efficiency. In4ri3/0" // these

stndrds do not inc/ude 3/o+ do+n s /oss in the

efficienc0 determintion process1

Boiler efficiency can be tested by the followin! methods:

1% The !irect Method& /here the ener!y !ain of the

wor&in! fluid $water and steam% is com#ared with theener!y content of the boiler fuel.

0% The Indirect Method& /here the efficiency is the

difference between the losses and the ener!y in#ut.


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The !irect Method Testin,


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Merits of !irect Method

Merits

1 P/nt peop/e cn e4/ute 8uic9/0 the

efficienc0 of 3oi/ers

1 Re8uires fe+ prmeters for

computtion

1 Needs fe+ instruments for monitorin,


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!emerits of !irect Method

!emerits

1 !oes not ,i4e c/ues to the opertor s to +h0

efficienc0 of s0stem is /o+er

1 !oes not c/cu/te 4rious /osses

ccount3/e for 4rious efficienc0 /e4e/s

1 E4portion rtio nd efficienc0 m0mis/ed" if the stem is hi,h/0 +et due to

+ter crr0o4er


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The Indirect Method Testin,


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Losses in the Boi/er

The fo//o+in, /osses re pp/ic3/e to /i8uid",s nd so/id fired 3oi/er

L'1 Loss due to dr0 f/ue ,s 5sensi3/e het7

L:1 Loss due to h0dro,en in fue/ 5;:7

L.1 Loss due to moisture in fue/ 5;:O7

L$1 Loss due to moisture in ir 5;:O7

L%1 Loss due to cr3on mono2ide 5CO7


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Losses in the Boi/er Cont11

L


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Mesurements Re8uired for

Performnce Assessment

Testin,

7 F/ue ,s n/0sis

1. ercenta!e of 230or 30in flue !as

0. ercenta!e of 23 in flue !as

. Tem#erature of flue !as


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Testin,

37 F/o+ meter mesurements for

1. uel

0. Steam

. eed water

4. 2ondensate water

5. 2ombustion air


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Testin,

c7 Temperture mesurements for

1. lue !as 0. Steam . a&eu# water

4. 2ondensate return 5. 2ombustion air. uel 7. Boiler feed water


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Testin,

d7 Pressure mesurements for

1. Steam

0. uel

. 2ombustion air" both #rimary and secondary

4. +raft


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Testin,

e7 ter condition

1. Total dissol*ed solids $T+S%

0. #-

. Blow down rate and (uantity


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TYPICAL INSTRUMENTS

T C di i d


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Test Conditions nd

Precutions

A7 The efficienc0 test does not ccount for&.Standby losses. 6fficiency test is to be carried out" when the

boiler is o#eratin! under a steady load. Therefore" the combustion

efficiency test does not re*eal standby losses"which occur between

firin! inter*als.Blow down loss. The amount of ener!y wasted by blow down*aries o*er a wide ran!e.

.Soot blower steam. The amount of steam used by soot blowers is

*ariable that de#ends on the ty#e of fuel.

.Auxiliary equipment energy consumption. The combustionefficiency test does not account for the ener!y usa!e by au'iliary

e(ui#ments" such as burners" fans" and #um#s.

T t C diti d


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Test Conditions nd

Precutions

B7 Preprtions nd pre conditions for testin,

. Burn the specified fue/5s7 t the re8uired rte1

1 !o the tests +hi/e the 3oi/er is under sted0 /od1 A4oid testin,

durin, +rmin, up of 3oi/ers from co/d condition1 O3tin the chrts t3/es for the ddition/ dt1

1 !etermintion of ,ener/ method of opertion

1 Smp/in, nd n/0sis of fue/ nd sh1

1 Ensure the ccurc0 of fue/ nd sh n/0sis in the /3ortor01

1 Chec9 the t0pe of 3/o+ do+n nd method of mesurement

1 Ensure proper opertion of // instruments1

1 Chec9 for n0 ir infi/trtion in the com3ustion one.

T t C diti d


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Test Conditions nd

Precutions

C7 F/ue ,s smp/in, /oction

It is su,,ested tht the e2it duct of the 3oi/er 3e pro3ednd tr4ersed to find the /oction of the one of

m2imum temperture1 This is /i9e/0 to coincide +ith the

one of m2imum ,s f/o+ nd is therefore ,ood

smp/in, point for 3oth temperture nd ,s n/0sis1

T t C diti d


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Test Conditions nd

Precutions

!7 Options of f/ue ,s n/0sisCheck the Oxygen Test with the Carbon Dioxide Test

If continuous*redin, o20,en test e8uipment is inst//ed in

3oi/er p/nt" use o20,en redin,1

Occsion//0 use port3/e test e8uipment tht chec9s for 3otho20,en nd cr3on dio2ide1 If the cr3on dio2ide test does not

,i4e the sme resu/ts s the o20,en test" somethin, is +ron,1

One 5or 3oth7 of the tests cou/d 3e erroneous" perhps 3ecuse

of st/e chemic/s or driftin, instrument c/i3rtion1Another possi3i/it0 is tht outside ir is 3ein, pic9ed up /on,

+ith the f/ue ,s1 This occurs if the com3ustion ,s re

opertes under ne,ti4e pressure nd there re /e9s in the

3oi/er csin,1

T t C diti d


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Test Conditions nd

Precutions

Carbon onoxide Test

The carbon mono'ide content of flue !as is a !ood

indicator of incom#lete combustion with all ty#esof fuels" as lon! as they contain carbon. 2arbon

mono'ide in the flue !as is minimal with ordinary

amounts of e'cess air" but it rises abru#tly as soonas fuel combustion starts to be incom#lete.

T t C diti d


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Test Conditions nd

Precutions

E7 P/nnin, for the testin,

. The testin! is to be conducted for a duration of 4 to 8

hours in a normal #roduction day.

. d*anced #lannin! is essential for the resource

arran!ement of man#ower" fuel" water and instrument

chec& etc and the same to be communicated to the

3#eration and aintenance +e#artments.

. Sufficient (uantity of fuel stoc& and water stora!e

re(uired for the test duration should be arran!ed so that a

test is not disru#ted due to non,a*ailability of fuel and

water.

T t C diti d


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Test Conditions nd

Precutions

E7 P/nnin, for the testin, contdD

. ecessary sam#lin! #oint and instruments are to be

made a*ailable with wor&in! condition.

. ab nalysis should be carried out for fuel" flue !as

and water in coordination with lab #ersonnel.

. The steam table" #sychometric chart" calculator

com#uter etc are to be arran!ed for com#utation of

boiler efficiency.

C / / i P d d


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C/cu/tion Procedure nd

Formu/e

In order to calculate the boiler efficiency by indirect

method" all the losses that occur in the boiler must be

established. These losses are con*eniently related to theamount of fuel burnt.

In this way it is easy to com#are the #erformance of

*arious boilers with different ratin!s.

f T i f B il


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erformance Testin! of Boilers

Sam#le In#ut arameters , 1

'

:

.

$

%

3195 292334 Boiler Performance

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