BOILER WATER LEVEL CONTROL
WATER LEVEL INDICATOR
THERMODYNAMIC STEAM TRAP
With diesel machinery the
amount of heat carried away by the exhaust gases varies between 20 to 25
per cent of the total heat energy supplied to the engine. Recovery of some
of this heat loss to the extent of 30 to 50 percent is possible by means
of an exhaust gas boiler or water heater.
The amount of heat recovered from the exhaust gases depends upon various
factors, some of which are, Steam pressure, temperature, evaporative rate
required, exhaust gas inlet temperature, mass flow of exhaust gas,
condition of gas exchange surfaces, etc.
Composite boilers are often used in conjunction with Diesel machinery,
since if the exhaust gas from the engine is low in temperature due to slow
running of the engine and reduced power output; the pressure of the steam
can be maintained by means of an oil fired furnace. Steam supply can also
be maintained by these types of boilers when the engine is not in
The Cochran boiler whose
working pressure is normally of the order of 7 bar is available in various
types and arrangements, some of which are:
Simple pass composite, i.e., one pass of the exhaust gases and two
uptakes, one for the oil fired system and one for exhaust system. Double
pass composite, i.e., two passes for the exhaust gases and two uptakes,
one for the oil fired system and one for the exhaust system. Double pass
exhaust gas, no oil fired furnace and a single uptake. Double pass
alternatively fired, two passes from the furnace for either exhaust gases
or oil fired system with one common uptake.
The material used is good quality low carbon boiler steel plate. The
furnace is pressed out of a single plate and is seamless.
"REED'S GENERAL ENGINEERING
KNOWLEDGE FOR MARINE ENGINEERS", by Leslie Jackson and Thomas D. Morton