CIRCULATION SYSTEMS
CIRCULATION SYSTEMS In power plant boiler is used as a steam generator. From boiler high pressure & high temperature steam is generated and used in steam turbine. In power plant boiler may be drum type or without drum. Drum type boilers are called as sub-critical boiler because its working pressure is bellow critical pressure while without drum type boiler is called once through boiler because its pressure is higher than critical pressure. In sub-critical units boiler drum acts as reservoir for water & saturated steam and also provides means and arrangements for separation and purification of steam. The term circulation generally refers that "the movement of fluid from boiler drum to the combustion zone (furnace water walls) and back to the drum". In boiler drum steam separator equipment are installed. Feed water is supplied to the drum via the economizer in heated condition. when feed water enters in to the boiler drum then it mixed with the dr