Waste Heat recovery boiler system introduction:
Heat recovery boiler system named waste heat recovery boiler which are used to capture heat energy directly from a waste heat source like exhaust gas. The hot waste fluid passes around consecutive tube bundles such as economizer, evaporator and super-heater, while inside the tubes water is flowing and steam is being produced. Alternatively, thermal oil may be heated up on the secondary side of the heat ex-changer without boiling.
Waste heat recovery boiler have two types of boiler- water tube waste heat boiler and fire tube waste heat boilers which both are arrangements may also be involved in utilizing low-temperature heat with the help of advanced systems.
Application of exhaust gas boilers for heat recovery
Exhaust Gas Boilers (EGB) meant for medium speed engine heat recovery boiler systems are designed to capture heat energy from engine exhaust gas at medium temperature levels and limited pressure loss. Therefore EGBs are designed with finned or pinned boiler tubes at the gas side in order to effectively capture and transfer heat from relatively high quantities of flue gas.
The effectiveness of an EGB largely depends on the condition of the heat transferring surface. Therefore periodic soot blowing of the boiler is essential to keep the heat transferring surface free from soot deposits which may decrease steam production considerably and could lead to a soot fire if unattended for a considerable period.
The application of a typical heat recovery system used on board employing a medium speed engine. The waste heat from the engine exhaust gas is converted to steam energy and a steam turbine is driven from it in turn driving an alternator to produce electricity. The generated steam is also used for on board process heating and whenever the steam production exceeds the demand the excess steam is dumped to a dumping condenser.