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Performance Terms and Definitions
Heat ot!t
Heat In!tBoiler Efficiency, =
Heat in steam ot!t "#Ca$s%Heat in Fe$ In!t "#Ca$s%
&antit' of Steam Generation
Quantity of fuel ConsumptionEvaporation Ratio =
The efficiency of a boiler is expressed as the % of useful heat
available from the total energy available by burning the fuel.
T(is is e)!ressed on t(e *asis of +ross ca$orific ,a$e "GC-% .
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StandardsBritis( standards/ BS0123 4506
This describes the methods and conditions under which a boilershould be tested.Boiler should be operated under steady load
conditions generally full load! for a period of one hour before ta"ing
reading
ASME Standard3 PTC7174 Po8er Test Code for Steam Generatin+
9nits
Part One: Direct method (also called as Input -output method) Part Two: Indirect method (also called as Heat loss method)
IS 062:3 Indian Standard for Boi$er Efficienc' Testin+
#ll standards do not include blow down as a loss in the efficiency
determination process.
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Direct Met(od Testin+
$
valuecalorific&rossxratefiring'uel
enthalpy!waterfeedenthalpysteamxrateflow(teamxEfficiencyBoiler
=
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Indirect Met(od Testin+
Boi$er 'lue gas sample
(team )utput
Efficiency = $ * $++-++/+0+1+2! by 3ndirect 4ethod!
#ir
'uel 3nput, $%
$. 5ry 'lue gas loss
. 6 loss
-. 4oisture in fuel
. 4oisture in air
/. 7) loss
1. 'ly ash loss
0. (urface loss
2. Bottom ash loss
Blow down
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Instruments used for Boiler PerformanceAssessment.
Instrument Type Measurements
Flue gasanalyzer
Portale or !i"ed # $O% & O% and $O
Temperatureindicator
Thermocouple&li'uid in glass
Fuel temperature& !lue gastemperature& comustionair temperature& oilersur!ace temperature&steam temperature
Dra!t gauge anometer&di!!erentialpressure
mount o! dra!t used ora*ailale
TD+ meter $onducti*ity ,oiler water TD+& !eedwater TD+& mae-up waterTD+.
Flow meter s applicale +team !low& water !low&!uel !low& air !low
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4.Tec(nica$ s!ecification of *oi$er
/ ,oiler ID code and ae
% 0ear o! ae
1 ,oiler capacity rating
2 Type o! ,oiler
3 Type o! !uel used
4 a"imum !uel !low rate
5 6!!iciency y 7$8
9 +team generation pressure superheat temperature
; Heat trans!er area in m%
/< Is there any waste heat reco*ery de*ice installed
// Type o! dra!t
/% $himney height in metre
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; 7 Fe$ ana$'sis detai$s
Fe$ Fired
GC- of fe$
S!ecific +ra,it' of fe$ "Li
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9$timate Ana$'sis Date of Test3$aron #
Hydrogen #
+ulphur #
=itrogen #sh #
oisture #
O"ygen #
Water Analysis Date of Test:Feed water TD+ ppm
,low down TD+ ppm
PH o! !eed water
PH o! low down
Flue gas Analysis Date of Test:
$O%
#
O%
#
$O #
Flue gas temperature O
$
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S
.No
T
ime
Amient air Fuel Feed !ater Steam Flue gas
analysis
Surface
Temp ofoiler" o# Dry
ulTemp"
o#
WetBul
Temp"o#
Flo!$ate"%g&'r
Tempo
#
Flo!rate"
m(&'r
Tempo
#
Flo!
rate"
m(&'r
Pr
ess
r
e%g&c
m)
g
Tempo
#
*
)
+
#*
)
+
C
O
+
Temp,
#
/.
%.
1.
2.
3.
4.
5.
9.
-. Format s'eet for oiler efficiency testing
5ate8 9999999 Boiler 7ode :o. 9999999
Boiler (upervisor Energy 4anager Energy #uditor
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'uel firing rate = //;;.$1 "g of fly ash = /./ "7al of 7oal = -/$ "7al
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Boi$er efficienc' *' indirect met(od
Ste! > 4 Find t(eoretica$ air
re
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Ste! > ; Find t(eoretica$ CO;=
7)at theoretical condition 7)!t
=
4oles of 7
4oles of :+ 4oles of 7
here,
oles of : =
.2 x 11
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Ste! > : To find E)cess air
s!!$ied
#ctual 7) measured in flue gas = $.%
% Excess air supplied E#! = 1; x @ 7)!t* 7)!aC
7)!ax @$ * 7)!tC
= 1; x @.01 * $ C
$ax @$ * .01C
= 16.11 =
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Ste! > 1 to find acta$ mass of air s!!$ied
#ctual mass of air supplied = A$ + E#
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Ste! > @ to find a$$ $osses
$. % 6eat loss in dry flue gas $! = m x cpx Tf* Ta!
x $
&7> of fuel
=1./0 x .- x $; * -$!
x $-/$
$ = 6.05 =
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. % 6eat loss due to formation
of water from 6in fuel !
= ; x 6 x A/2 + 7pTf* Ta!
x $
&7> of fuel
=; x .$ x A/2 + ./$;D-$!
x $
-/$ = :.11 =
-. % 6eat loss due to moisture in
fuel E-!
=
4 x A/2 + 7p Tf* Ta!
F $
&7> of fuel
=
.-$0 x A/2 + ./ $; * -$!
x $
-/$
E- = 2.54 =
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. % 6eat loss due to moisture in
air !
=
##( x humidity x 7px Tf* Ta! x $
&7> of fuel
=1.$- x . x ./ x $; * -$! x $
-/$
= .;5 =
/. % 6eat loss due to partial
conversion of 7 to 7) /!
=%7) x %7 /1
x x $
% 7) + % 7)!a &7> of fuel
=
.// x .$0/ /1
x x $.// + $ -/$
/ = ;.20 =
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0. 6eat loss due to radiation and
convection E0!
= ./2 x @ --
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1. % 6eat loss due to unburnt in fly ash
#sh in coal = 2.0-
atio of bottom ash to fly ash = ;8$&7> of fly ash = /./ "7al
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oiler efficiency by indirect
ethod
= $ * E$+ E+ E-+ E+ E/+ E0+ E1+ E2!
= $D1.2; + -.+ /.;$+ .;+ ./2+ ./+
.$$+$.11!
= $D.
66.6@ =
Summary of Heat Balance for Coal Fired Boiler
In!t?Ot!t Parameter #Ca$ ? #+ of
coa$
= $oss
6eat 3nput = -/$ $Eosses in boiler
$. 5ry flue gas, E$ = 10.- 1.2;
. Eoss due to hydrogen in fuel, E = $.- -.
-. Eoss due to moisture in fuel, E- = 0.;$ /.;$
. Eoss due to moisture in air, E = $.$/ .;
/. Gartial combustion of 7 to 7), E/ = ;.- ./20. (urface heat losses, E0 = 2.1/ ./
1. Eoss due to Hnburnt in fly ash, E1 = -.2/ .$$
2. Eoss due to Hnburnt in bottom ash,
E2
= 0$.;1 $.11
Boi$er Efficienc'= $ * E$+ E+ E-+ E+ E/+ E0+ E1+ E2% 66.6@ =
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Factors Affecting BoilerPerformance
I Geriodical cleaning of boilers
I Geriodical soot blowing
I Groper water treatment programme and blow down
control
I 5raft control
I Excess air control
I Gercentage loading of boiler
I (team generation pressure and temperature
I Boiler insulation
I Juality of fuel
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