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1.8 Example For Coal Fired Boiler Energy Performance Assesment of Boilers

This document provides information to calculate the boiler efficiency of a coal fired boiler using the indirect method. It includes details of the fuel and steam properties, flue gas composition, heat losses, and calculations. The boiler efficiency is calculated to be 77.7388% based on determining the theoretical air requirement and CO2%, measuring excess air supplied, calculating actual air and flue gas, and quantifying various heat loss percentages from components like dry flue gas, moisture, carbon conversion, and unburned fuel in ash.

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109 views3 pages

1.8 Example For Coal Fired Boiler Energy Performance Assesment of Boilers

This document provides information to calculate the boiler efficiency of a coal fired boiler using the indirect method. It includes details of the fuel and steam properties, flue gas composition, heat losses, and calculations. The boiler efficiency is calculated to be 77.7388% based on determining the theoretical air requirement and CO2%, measuring excess air supplied, calculating actual air and flue gas, and quantifying various heat loss percentages from components like dry flue gas, moisture, carbon conversion, and unburned fuel in ash.

Uploaded by

AyiRahmawati
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as XLSX, PDF, TXT or read online on Scribd
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1.

8 example
for coal fired boiler
energy performance assesment of boilers

fuel firing rate 5599.17 kg/hr Percent Mass of Nitrogen 77


steam generation rat 21937.5 kg/hr Percent Mass of Oxygen 23
steam pressure 43 kg/cm2
steam temperature 377 C
feed water temperatu 96 C
%CO2 in flue gas 14
%CO in flue gas 0.55
avarage flue gas temp 190 C
ambient temperatur 31 C
humidity 0.0204 kg/kg dry air
surafce temperature o 70 C
wind velocity around 3.5 m/s
total surface area of 90 m2
GCV of bottom 800 Kcal/kg
GCV of fly ash 452.5 Kcal/kg
ratio of bo 90 10
fuel analysis (in %)
ash content in 8.63
moisture in coal 31.6
carbon content 41.65
hydrogen content 2.0413
nitrogen content 1.6
oksigen content 14.48
GCV of coal 3501 Kcal/kg
BM N2 28
BM C 12
Boiler Efficiency By Indirect Method
Step -1 Find Theoritical air recruirement
Theoritical air recuired for complete combustion = 4.911892 kg/kg of coal

Step -2 Find Theoritical CO2 %


Moles of N2 = 0.135648
Where moles of C = 0.034708
(CO2)t = 20.37391 %

Step -3 To find excess air supplied


Actual CO2 measured in flue gas = 14 %
% Excess air supplied (EA) = 45.16991 %
Step -4 to find actual mass of air supplied
Actual mass of air supplied = 7.13059 kg/kg of coal

Step -5 to find actual mass of dry flue gass


Mass of dry flue gass = 7.544021 kg/kg of coal

step -6 to find all losses


1. % Heat loss in dry flue gas (L1) = 7.880173 %

2. % Heat loss due to formation = 3.440037 %


of water from H2 in fuel (L2)

3. % Heat loss due to moisturein fuel (L3) = 5.916989 %

4. Heat loss due to moisture in air (L4) = 0.297261 %

5. Heat loss due to partial convertion of C to CO (L5) = 2.583075 %

6. Heat loss due to radiation and convection (L6) = 651.6972 watt/m2


= 560.4596 kcal
total radiation and convection loss per hour = 50441.36 kcal

%radiatio and convection loss L6 = 0.257319 %

7. % Heat loss due to unburnt in fly ash


% Ash in coal = 8.63 %
Ratio of bottom ash to fly ash = 90 : 10
GCV of fly ash = 452.5 kcal/kg
Amount of fly ash in ! Kg of coal = 0.00863 kg
Heat loss in fly ash = 3.905075 kcal/kg of coal
% Heat loss in fly ash L7 = 0.111542 %

8. % Heat loss due to un burnnt in bottom ash


GCV of bottom ash = 800 kCal/kg
amount of bottom ash in 1 kg of coal = 7.767 kg
Heat loss in bottom ash = 62.136 kCal/kg of coal

%Heat loss in bottom ash L8 = 1.774807 %

Boiler Efficiency by indirect methode = 77.7388


%
%

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