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Boiler Accessories - An Overview

These are auxiliary plants required for steam boilers for their proper operation and for the increase of their efficiency. 

Commonly used boiler accessories are :

Feed pumps

A boiler feed pump is critical equipment used in a boiler house which supplies deaerated and LP dosed feedwater to the boiler. This pump has to pump feedwater into the boiler drum against the boiler drum pressure. So, discharge pressure of this pump is higher than the boiler drum pressure. Normally, the feed pump is a multistage pump driven by an electrical motor or turbine.

Injector

An injector is a device used for forcing water into a boiler against the existing pressure. It operates through the principle of utilizing a steam jet to create suction, which in turn lifts or pumps one fluid using another, higher-pressure fluid. This dual fluid mechanism is essential in ensuring that boilers operate efficiently and effectively.



 

Economiser

Economiser is used to utilise the fuel economically or make the boiler economical. Hot exhaust Flue gas from the boiler, which would have gone to the atmosphere, is used to increase the efficiency of the boiler. This is a heat exchanger in which flue gas flows in a shell arranged with water tubes. Heat of flue gas is utilised to increase the temperature of water to increase sensible heat of water.


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 pass through the economiser and then to the air preheater. 

 


Superheater

The function of a superheater is to increase the temperature of the steam above its saturation point. The superheater is a very important accessory of a boiler and can be used both on fire-tube and water-tube boilers. The small boilers are not commonly provided with a superheater.



Steam separator

'Wet' steam is a major concern in a steam system as it can cause process and maintenance problems, including lower productivity, erosion and corrosion. Separators are designed to efficiently remove the moisture from steam flow. It is located in steam drum. 

Steam trap

A steam trap is an automatic valve that holds the steam at the load until it gives up its heat energy and condenses to water (condensate). After the steam condenses to water, the steam trap allows only the condensate to pass, thereby contributing to plant efficiency.


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