Author: haroonkhan

The injector is a feed pump which is used to deliver feed water into the boiler under pressure. It is mostly used in vertical and locomotive boilers. It is not suitable for large power plants. It consists of group of nozzles so arranged that the steam expanding in these nozzles imparts kinetic energy to a…

The function of feed pump is to feed the feed water to the boiler. Different types of feed pumps used in boilers are reciprocating, centrifugal, and injector. Centrifugal or rotary pumps are used where large amount of water is required. For small boilers, reciprocating pump and injectors are used.

Steam generated in the boiler is wet due to contact with water. To get superheated steam, a device known as superheater is used in the boilers. The function of superheater is to super heat the steam up to desired level. It is a surface heat exchanger, located in the path of the flue gas. The…

Air preheater is a device for recovery of waste heat from flue gas and is placed in the path of the waste flue gas going to chimney. Waste heat if the flue gas is transferred to the air before entering into the furnace to support the combustion of fuel. It is placed in chimney and…

Economiser is a type of heat exchanger which exchanges some parts of the waste heat of flue gas to the feed water. It is installed between exit of the furnace and entry into the chimney. Generally, economiser is placed after feed pump to avoid the problem of priming in feed pump. If economiser is installed…

The devices used in boiler to increase its efficiency and quality of steam are known as accessories. The names of some important accessories are as follows:

This is opening in the boiler. It is used for cleaning and inspection purpose. Through this hole operator enters inside the boiler in idle condition.

The function of fusible plug is to extinguish the fire in the fire box, when water level in the boiler comes down the limit. It prevents from blasting the boiler, melting the tube, and overheating the fire box crown plate. The constructional details of fusible plug are shown in Figure 4.23. It is located in water space…

The function of blow-off cock is to blow down the sediments collected at the bottom of the drum or to empty the boiler or to lower down the water level in the drum. The blow-off cock is fitted at lowest portion of the boiler. The casing is provided with two flanges—one is connected to the…

The function of steam stop valve is to stop or allow the flow of steam from boiler to steam pipe or from steam pipe to supply. The opening of the valve is controlled by a hand wheel. The constructional details of steam stop valve are very simple which is shown in Figure 4.21. Figure 4.21 Steam Stop…