A boiler is called a high-pressure boiler
when it operates with a steam pressure
above 80 bars.
The modern high pressure boiler is of:
Steam capacities – 30 to 650 tons/hour
Pressure – up to 160 bar
Maximum steam emperature – 549° C
TYPES OF HIGH PRESSURE BOILER:
1) La-Mont boiler
2) Loeffler boiler
3) Benson boiler
4) Schmidt-Hartman boiler
5) Velox boiler
UNIQUE FEATURE CF HIGHPRESSURE BOILER:
Method of water circulation:
1) Forced circulation, using pump.
Types of Turbine:
2) Water Tube Boilers, with flow through several sets of parallel system of turbine – to reduce pressure loss occurring in single tube system and to have better control over quality of stedm.
Improve method of heating:
1) Saving of heat by evaporation of water abovecritical pressure of steam.
2) Heating of water by mixing with superheated steam to give high heat transfer coefficients.
3) Increase in overall heat transfer coefficients
by increasing water velocity inside the tube and
increasing gas velocity above sonic velocity.
1) Large number of small size tub and number of pass are used which increases the heat transfer area, hence size and weight of boiler is reduced.