Feedwater is the water to be supplied into steam boiler. Requirement of feedwater is regulated by ABMA (American Boiler Manufacturing Association). Water treatment is one of step in this requirement. Temperature of feedwater influence efficiency of steam boiler, higher temperature will increase the efficiency, so feedwater heater is required in the feedwater system.
Amount of feedwater is maintained to keep steam boiler on the range of NOWL (Normal Operation Water Level). Maintain water level is totally important to keep steam boiler safe from both short term overheating or long term overheating and also damage turbine generator.
There are three types of feedwater regulators commonly used in the power plant system. The type of feedwater regulator is generally used based on function, size, and the principal working. The following below are the feedwater regulator type:
1. Thermostatic Expansion Regulator.
This type is feedwater regulator which uses inclined tube and connects it between feedwater control valve and boiler. If the water level in the boiler indicates low level, the tube will get expansion, so the feedwater control valve will supply the feedwater.
2. Hydraulic Regulator
This type is feedwater regulator which consist tube, fin, and jacket. This regulator use tube which be connected between water column in the steam drum and feedwater control valve. When water level show low level which means that amount of steam steam is higher than water, the steam will enter the tube, at the certain temperature and pressure, the valve will open to supply feedwater into steam boiler.
3. Float Regulator
This type is feedwater regulator which uses floating equipment like a ball and connects it to the boiler. The floating ball will move up and down parallel with water level in the boiler. A connecting system must be set up between this equipment and the feedwater control to maintain the steam boiler water level in the range NOWL.