Role of Feedwater Heaters in a Steam Boiler

Role of feedwater heaters in a steam boiler is important to make efficiency of steam boiler higher. A feedwater heater is a heat exchanger that has function to heat feedwater before to be supplied to a steam boiler. The feedwater heater is used to bring feedwater closer to temperature of the steam boiler water. It aims to increase steam boiler efficiency 1% with each 10oF rise in feedwater temperature. This increase efficiency can make saving in required fuel to heat steam boiler water.

 There are two general types of feedwater heaters are used in a steam boiler plant:
1.      Close feed water heater.
This type of heater is an indirect heater because the steam and water are separated by tubes and the water is heated by conduction. The closed feedwater heater contains two important parts: tubes and shell. Feedwater flow through the tubes and shell-side of the feedwater heater contains hot steam, generally use steam from exhaust turbine or waste heat generated in the steam boiler plant to improve overall plant efficiency. The feedwater is heated as a result of heat transfer from steam to feedwater.

The close type of heater can heat water with higher temperature than close type. The close feed water heater is located before the steam boiler feed pump with has low pressure and a high pressure feedwater heater is located at the downstream side of the steam boiler feed pump

2.      Open feed water heater.
This type of heater is a direct contact heater as the water is mixed directly with steam. The open feedwater heater is located at the suction side above steam boiler feedwater pump. This is necessary so that the feedwater pump can be supplied with a head pressure to permit higher feedwater temperature.

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