Steam Drum of Boiler

A steam drum is a pressure chamber of a steam boiler located at the upper extremity of steam boiler circulatory system. It is a reservoir of water/steam at the top end of the water tubes. The steam drum stores the steam generated in the water tubes and acts as a phase-separator for the steam/water mixture. Steam is separated from the water and then discharged at a position above the water level maintained there.

Fig.1: Steam Drum of Boiler
In natural circulation of steam boilers, the steam drum occupies a position of importance
because of: it is the heaviest PP and often the heaviest component, the layout and erection of the steam boiler revolve around it, It takes the maximum time for manufacturing and needs the costliest machinery, moving it demands a high level of logistics, it needs the heaviest crane or lifting tackle during both fabrication and erection.

Thermodynamically, however, a steam drum is merely a surge tank in the circulation
system to which the following parts are connected: Economizer outlet and Superheater inlet pipes on one side, downcomers and risers on the other side.

Under steady operating conditions when the flows are balanced, the steam drum produces
a steady water level. Drum water level is one of the most important parameters, of a steam boiler control system. The other important function of the steam drum is to house the drum internals, which perform the following functions: saturated water from evaporator circuits, which contain varying amounts of steam, is separated by the steam separators. Water-free steam to the SH and steam-free water to the downcomers are required of steam separators and purifiers, chemical dosing to maintain the chemistry of the circulating water, continuous blowdown of drum water to keep the carryover under specified limits.


zzor0 said...

Hi sir..I want to ask, how to determine the transfer function of steam drum on 3 element level control? please reply to my email
Thanks a lot

M. Taufik said...

Thaks very much for your question,
Three element level control is one of steam boiler level control strategies to maintain mass balance of water input and steam output in safety operation. The 3 elements will be controlled are drum level, main steam flow, and feedwater flow.

Drum level is used to control water level in steam drum and maintain it normal condition.

Main steam flow level is used to control mass balance of flow and check if there is leakage in tube of superheater

Feed water flow is used to control flow of feedwater which will be supplied into steam boiler safely.

For more explanation, I have technical paper maybe useful for you. I will sent to your email.

Anonymous said...

nice share bro

Anonymous said...

can you suggest to me about manufacturing steam & water drum..?
please contact :

gayatri said...

Can u send me the Transfer function model either 2 or 3 element control to my mail id I have readings from site and want to develop transfer function model from readings...i want generized Trasfer function model...plz help..


steam boiler said...

Dear gayatri,

please look my post on Boiler Drum Level Control Method

There some methods to control drum level in boiler.

sunil said...

iam interested in redycing the mfg cycle time of a steam drum,i want the mfg process and the time which individual processes take approximately