Steam-auxiliaries-reviewer.docx

STEAM GENERATING PLANT AUXILIARIES AND COMPONENTS CONDENSERS Devices used to condense a substance from its gaseous state to its liquid state, typically by cooling it. TYPES OF CONDENSER CONTACT CONDENSERS In these condensers, exhaust steam and condensing water are actually mixed together. Further subdivided into: Low Level Jet, High Level Jet and Ejector Condenser SURFACE CONDENSERS These condensers interpose a wall between steam and water, through which heat must be convectively transferred. FEED WATER SYSTEMS The feed water is put into the steam drum from a feed pump. The feed water consists of recovered condensed water and fresh water. SUPERHEATER A superheater is a device used to convert saturated steam or wet steam into superheated steam or dry steam.

TYPES OF SUPERHEATERS RADIANT SUPERHEATER A radiant superheater is placed directly in radiant zone of the combustion chamber near the water wall so as to absorb heat by radiation.

CONVECTIVE SUPERHEATER A convection superheater is located in the convective zone of the furnace. These are also called primary superheaters.

SEPARATELY FIRED SUPERHEATERS A separately fired superheater is a superheater that is placed outside the main boiler, which has its own separate combustion system.

ECONOMIZERS Economizers are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. TYPES OF ECONOMIZERS DIFFERENCE Condensing economizers are designed to accommodate the corrosive fluids generated when condensing the moisture out of the flue gas. Non-condensing economisers are generally of fin type which are located in the flue gas ducting at the exit so that they can gain more heat which is being wasted anyways. APPLICATION Common applications of economizers in steam power plants are to capture the waste heat from boiler stack gases (flue gas) and transfer it to the boiler feedwater.

FORCED DRAFT FAN Forced Draft (FD) fan is a type of fan that provides a positive pressure to a system. Fans for boilers force ambient air into the boiler, typically through a preheater to increase overall boiler efficiency. INDUCED DRAFT FANS Induced draft fan or ID fan is used to create a vacuum or negative pressure in the system. It is located at the outlet between dust collector and chimney, the ID fans will take the hot flue gases from furnace via dust collector and will deliver to chimney. ID fans handle hot gas, hence more maintenance is required. SOOT BLOWERS A device for removing the soot that is deposited on the furnace tubes of a boiler during combustion and prevent clogging of gas passes and maintain boiler efficiency. TYPES 1. Long retractable soot blower This is normally used to clean the ash deposit from between the coils of super-heaters and economizers.

2. Wall/Short retractable soot blower Wall blowers are used to clean the furnace walls.

3. Rotary Soot blower Rotary soot blowers are mainly used for blowing economizer and air pre-heater in the tail flue of the boiler.

4. Rake/Branched Soot blower Rake soot blower is used for cleaning the economizer fin type heating surface and the air pre-heater tube heating surface.

OPERATION A soot blower may be operated manually or by a remotely controlled motor. The soot, which is removed from the heating surfaces, will be blown out with the flue gases. If the boiler is equipped with a dust collector, it will trap the soot. Otherwise, the soot will be ejected into the outside air through the chimney stack. OIL PURIFIER A machine designed especially for purifying various industrial lubricating oils such as hydraulic oil, gear oil, coolant oil, compressor oil, etc. Due to long period usage of the systems, lube oils would be mixed and polluted with particles, impurities, water content and other waste residues which destroy the lube oil’s functions.

AIR COMPRESSOR An air compressor is a device which is used to compress the air and to raise its pressure. THERE ARE THREE TYPES OF COMPRESSOR IN A STEAM POWER PLANT 1. Rotary air compressor It uses two Asymmetrical rotors that are also called helical screws to compress the air. It is used for large discharge at low pressure. 2. Reciprocating air compressor It is such type of air compressor in which the pressure of the air is increased in its cylinder with the help of a moving piston. It is suitable for low discharge of air at very high speed. 3. Centrifugal air compressor

USES OF AIR COMPRESSORS IN A STEAM POWER PLANT 1. Instrument air All control valves operate by the use of instrument air. 2. Service air It is a compressed air directly coming out of the compressor. It is used for other purposes like transmitter, purging or cleaning.