Attention

Boiler steam drum water level is one of the most important power plant parameters to both measure and control. Control of the proper water level in the boiler is critical for safe operation of the boiler. If the level is too low, boiler tubes will be damaged by overheating. If the level is too high, steam separators will not function properly, temperature control will be difficult, and the superheater tubes and turbine could be damaged by moisture or water treatment chemical carryover.

Water circulation

Natural Circulation

In this circulation, the water flowing from upper drums through downcomers which is located in the boiler is relatively cold, flow down to mud drum. From mud drum, water flow back into the steam drum after passing through the evaporator tubes.

Forced circulation

In this forced circulation, fluid is pumped through the evaporator. This causes the boiler can work with very high pressures.

working

The separated steam is drawn out from the top section of the drum and distributed for process. Further heating of the saturated steam will make superheated steam normally used to drive a steam turbine. Saturated steam is drawn off the top of the drum and re-enters the furnace in through a superheater.

The steam and water mixture enters the steam drum through riser tubes, drum internals consisting of demister separate the water droplets from the steam producing dry steam. The saturated water at the bottom of the steam drum flows down through the down comer pipe, normally unheated, to headers and water drum. Its accessories include a safety valve, water-level indicator and level controller. Feed-water of boiler is also fed to the steam drum through a feed pipe extending inside the drum, along the length of the steam drum.

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