Basics of Mechanical Engineering


What are the Boiler Accessories?

Boiler Accessories: These are the devices which are used as integral parts of a boiler and which are helps proper operation & increases the efficiency of the boiler.

Boiler Accessories are given below:
  • Feed pump
  • Super heater
  • Economiser
  • Air Preheater
  • Injector
Functions/Applications of different boiler accessories:

>> Feed Pump:
It is used to deliver water to the boiler. A feed pump may be of centrifugal type or reciprocating type. But a double acting reciprocating pump is commonly used as a feed pump.
>> Super heater:
It is an important devices of a steam generating unit. Its purpose is to increase the temperature of saturated steam without raising its pressure. It is generally an integral part of a boiler and is places in the path of hot flue gases from the furnace. The heat, given up by these flue gases, is used in superheating the steam.
  • Steam consumption of the engine is reduced.
  • Losses due to the condensation in the cylinders and steam pipes are reduced.
  • Efficiency of the steam plant is increased.
>> Economiser:
An Economiser  is a device used to heat feed water by utilizing the heat in the exhaust flue gases before leaving through the chimney.

  • There is about 15-20% of coal saving
  • It increases the steam raising capacity of a boiler
  • Its prevents formation of scale in boiler water tubes, because the scale now formed in the economiser tubes, which can be cleaned easily.
>> Air Preheater:
The function of the air pre-heater is to increase the temperature of air before it enters the furnace. It is generally placed after the economiser, so the flue gases passing through the economiser and then to the air pre-heater.
 >> Injector:
The function of an injector is to feed water into the boiler. It is commonly employed for vertical and locomotive boilers and does not find its application in large capacity high pressure boilers. It is also used where the space is not available for the installation of a feed water.
In an injector the water is delivered to the boiler by steam pressure, the kinetic energy of steam is used to increase the pressure and velocity of the feed water.
  • Low initial cost
  • Simplicity
  • Compactness
  • Absence of dynamic parts
  • The efficiency very high
  • Ease of operation

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