BOILER FEED WATER PUMP:

-

A boiler feed water pump is a specific type of pump used to pump feed water into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler. These pumps are normally high pressure units that take suction from a condensate return system and can be of the centrifugal pump type or positive displacement type.


CONSTRUCTION:
Feed water pumps range in size up to many horsepower and the electric motor is usually separated from the pump body by some form of mechanical coupling. Large industrial condensate pumps may also serve as the feed water pump. In either case, to force the water into the boiler, the pump must generate sufficient pressure to overcome the steam pressure developed by the boiler. This is usually accomplished through the use of a centrifugal pump.

            Each unit has been equipped  with three numbers of horizontal , barrel type boiler feed pumps installed at zero meter level in turbine hall, out of which two pumps will be required to run for full load of unit and one pump will remain  50% stand by. The feed pumps are driven by electric motor through the hydraulic coupling.

Each feed pump has been provided with a motor driven booster pump in its suction line for maintaining a definite positive suction pressure for the feed pump.

HYDURALIC COUPLING:
          The feed pump is coupled with its driving motor through hydraulic coupling. The hydraulic coupling serves the purpose of controlling the speed of feed pump for maintaining a definite delivery head and delivered quantity of the pump as per requirement of the boiler.
            The speed control is done with the help of scoop tube setting alteration which consequently alters the oil quantity maintained between the devices transmitting power from motor shaft to the pump shafts. The oil quantity to the hydraulic coupling is supplied under pressure by auxiliary lubricating oil pump before starting of the feed pump and when the feed pumps has started the oil pressure is supplied by the shaft driven lubricating oil pump and auxiliary lubricating pump gets tripped.

FUNCTION OF FEED PUMP:
.            During normal running of the unit , the feed pump has to handle hot water receive from feed water storage tank of Deaerator through its booster pump enhancing the positive suction pressure and has to deliver the hot water under high pressure to boiler drum , through high pressure heaters and economiser for steam generation. The feed pump may be treated as the heart of the unit and therefore, full attention is to be paid during its starting up shutting down and normal running.Feed water is delivered by the feed pump is also utilized in the plant for the following purpose:
1.      For temperature control of auxiliary PRDS steam.
2.      For temperature control of superheated steam.
3.      For temperature control of reheat steam.

ARRANGEMENT OF BOOSTER PUMP & BFP:















OPERATION:
Feed water pumps sometimes run intermittently and are controlled by a float switch (or other similar level-sensing device energizing the pump when it detects a lowered liquid level in the boiler.)The pump then runs until the level of liquid in the boiler is substantially increased. Some pumps contain a two-stage switch. As liquid lowers to the trigger point of the first stage, the pump is activated. If the liquid continues to drop (perhaps because the pump has failed, its supply has been cut off or exhausted, or its discharge is blocked), the second stage will be triggered. This stage may switch off the boiler equipment (preventing the boiler from running dry and overheating), trigger an alarm, or both.
B.F.P is situated at zero meters (distance from earth level.). It takes water from Deaerator (27 meter) and serves to the boiler drum.
 Also a booster pump is provided which increase the head for boiler feed pump. There must be positive head for a boiler feed pump.






Comments

Post a Comment

Popular Posts

HPBP & LPBP

-
Image
HP Bypass Station 1:- HP/LP bypass system can handel 60% of boiler load. 2:- HPBP valve is a combined pressure reducing and desuperheating station valve 3:- Spray water is tapped from BFP discharge  and spray controled by spray control valve. 4:- HPBP dumps the depressurised and desuperheated steam with suitable parameter into CRH line. 5:-Can operate without coordinate with turbine. 6:- Allows quick raising of steam parameters at a level acceptable to turbine for rolling operqtion during start up. 7:-Oil supply unit is installed for operation of HPBP & LPBP valves  8:-Supply oil pressure is maintained at 160 kg/cm2 by the pump and accumulator unit. Modes of HP Bypass Operation 1:- Boiler start-up with TG set at stand still. 2:- Rising of steam parameters to a level acceptable to turbine for rolling. 3:- Turbine start-up and loading while steam flow gets transferred to the turbine 4:- Parallel operation with turbine on load rejection. 5:- Allowing boiler operatio
Read more

APRDS in THERMAL POWER PLANT

-
Image
OBJECTIVE Auxiliary steam is the steam that is required for various auxiliary requirements in a power plant. A part of main steam is tapped off for auxiliary steam station from MS/CRH line, after pressure reducing and de-superheating up to 16 Kg/cm 2   & 320 °C. At the HT header (16 16 Kg/cm 2    & 320⁰C) and then at the LT header (16 Kg/cm2 & 210⁰C) through desuperheater b/w the HT & LT headers. Spray water quantity required for the temperature reduction of the steam is controlled by separate spray water valve (taken from CEP discharge). TYPES OF STATIONS System consists of  two auxiliary  steam pressure reducing and desuperheating stations (APRDS). High capacity PRDS (LTPRDS)  with tapping off steam from main steam line or CRH line . Low Capacity PRDS(LTPRDS)  from HT header. APRDS SERVICES Auxiliary steam system is designed to provide steam for following systems. 1:-  Turbine  &  Turbine auxiliaries . 2:-  Boiler auxiliaries . 3:-
Read more

CONDENSATE EXTRACTION PUMP (CEP) IN A THERMAL POWER PLANT

-
Image
CONDENSATE EXTRACTION PUMP (CEP) Its Importance in Thermal Power Plant It handles water from hot well. The characteristic of that pump is that it handles water from vacuum.  Berceuse the condenser and the hot well are in vacuum bellow atmospheric pressure. No other pump has this characteristic to handle in such condition. It takes water from vacuum pressure and delivered above atmospheric pressure.   It is a vertical turbine type pump which is multi stage. It deliver water from hot well to deaerator. They may be used to pump the condensate produced from latent water vapors in any of the following mixtures: Steam condensed (exhaust from LP turbine) in condenser Make up water (dumped in condenser hot well from condensate storage tank) Flash box water LPDFT water HPDFT water Drip from ejector Drip from LPFWH   CEP for a 200 MW unit:- Each unit has been equipped with three nos. of condensate pumps installed vertically at minus four meter level in to the turbine hall.
Read more