Evaporation ratio of
boiler reduces with time, due to poor combustion, poor operation and
maintenance and heat transfer fouling.
Deterioration of fuel quality and water quality also leads
to poor performance of boiler. Hence for performance
test it is necessary to find out current evaporation ratio of boiler. Any observed
abnormal deviations could therefore be investigated to pin point the problem
area for necessary correction action.
Evaporation Ratio
= Quantity of steam generation/ Quantity of fuel consumption
Boiler evaporation
ratio also known as steam to fuel
ratio.
Boiler evaporation ratio monitoring is best for any boiler
when its own performance is compared on day to day basis as a performance
indicator. A drop in boiler evaporation ratio indicates a drop in boiler
efficiency.
Values of evaporation ratio for different type of fuels are
as below:
Coal Fired Boiler - 4.0 to
6.0
Oil fired Boiler - 13.0
to 14.5
Gas fired Boiler -
11.0 to 13.0
Biomass fired boiler – 2.0 to
3.0