It is a fire tube, internally fired, stationary, horizontal,
natural circulating type boiler. Evaporative capacity may be up to 8500 kg/hr.
and can operate with working pressures up to 1.5Mpa. Normally it is used in
sugar mills and chemical plants i.e. in moderate conditions.
CONSTRUCTION
Consists of a boiler shell which contains water and
steam, Diameter may vary from 1.75 to 2.75 m and length may be 7.25 – 9 m. It
has two side channels connected to rear end of the boiler shell and then
finally to the chimney. To provide larger heating surface area it has two large
diameter flue gas tubes. The tubes are tapered with larger diameter in front
and smaller diameter at back. The taper is provided to accommodate the grate.
Two grates are provided at the front end of the flue gas tubes. For controlling
the flow of the flue gases two dampers are also provided at the rear end. Further
for cleaning and inspection of the drum, manhole is also provided. Other boiler
mountings like feed check valve, pressure gauge, water level gauge, steam stop
valve, blow off cock are also provided.
WORKING
Water is filled through the feed check valve. On
burning the fuel over the grate, the hot gasses are produced which move in the
flue gas tubes. The flue gasses reach the rear end of the boiler and then made
to deflect and pass through the bottom central chamber. On reaching the front
end the flue gasses again get deflected and then pass through the side
chambers. Finally the flue gasses are discharged to atmosphere through chimney.
The flows of flue gasses are controlled by dampers which are operated by boiler
operator using chain pulley arrangement.
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