A boiler is a pressurized part that contains water and steam, including a drum, a heating surface, a collecting box (also called a coupling box) and pipes. The process of water heating, vaporization and water separation is carried out.

Generally speaking, boiler is the main working process on fuel combustion, heat transfer, water heating and vaporization and steam overheating and so on. The whole boiler is composed of boiler body and auxiliary equipment. Boiler body: Boiler body is the main part of boiler equipment, is composed of "pot" and "furnace" two parts.

"Pot" is a water system, its main task is to attract the heat released by the fuel, so that the water heating, evaporation and finally into a certain parameter of superheated steam. It is composed of economizer, drum, down pipe, coupling box, water wall, superheater and reheater and other equipment and connecting pipes and valves.

(1) economizer. Located in the vertical flue at the tail of the boiler, the waste heat of the flue gas is used to heat the boiler feed water, reduce the exhaust temperature, improve the efficiency of the boiler and save fuel.

(2) drum. Located at the top of the boiler, it is a cylindrical pressure vessel with water below and steam above. It receives water from the economizer, and at the same time, it forms a water circulation loop together with the descending pipe, header and water wall. Water absorbs heat in the water wall and the mixture of soda water is collected in the drum. After the separation of soda water, saturated steam is delivered to the superheater.

(3) drop pipe. Is the water supply pipe of the water wall, its function is to introduce the water in the drum into the lower header and then distribute it to each water wall pipe. There are two kinds of small diameter scattered down pipe and large diameter concentrated down pipe. Small diameter down pipe small diameter, adverse to water circulation.

(4) water wall lower header. The main function of the coupling box is to gather the mass together, or to redistribute the working mass through the coupling box to other pipelines. The lower water wall header is a thick pipe closed at both ends. Its function is to connect the lower pipe and the water wall together so as to play the role of collecting, mixing and redistributing the working medium.

(5) Water wall. Located around the furnace, its main task is to absorb the radiant heat in the furnace, so that water evaporation, it is the main heating surface of modern boilers, but also can protect the furnace wall.

(6) Superheater. Its function is to heat the saturated steam from the drum into superheated steam with a certain temperature.

(7) Reheater. Its function is to do some work in the steam turbine steam heating up again, and then sent to the steam turbine to continue to do work.

"Furnace" is the combustion system, its task is to make the fuel in the furnace good combustion, release heat. It consists of furnace, burner, ignition device, air preheater, smoke duct and furnace wall, frame and so on.

(1) Furnace. It is converted from the furnace wall and the water wall to fuel combustion. The fuel burns in suspension in the space, releasing a lot of heat.

(2) Burner. Located on the four corners or walls of the furnace, its function is to inject fuel and air into the furnace at a certain speed, so that it can be well mixed in the furnace to ensure that the fuel fire in time and quickly and completely combustion. There are two basic types: DC burner and cyclone burner.

(3) Air preheater. Located in the tail flue of the boiler, its role is to use the waste heat of the flue gas to heat the air needed for fuel combustion, which can not only further reduce the exhaust temperature, but also for strengthening the combustion in the furnace, improving the economy of combustion, drying and conveying pulverized coal are favorable. Boiler efficiency can be increased by about 2%. Split tube type and rotary type.

(4) smoke duct. It is composed of the furnace wall, part of the heating surface pipe and wall pipe, to guide the flow of smoke, and through each heating surface for heat exchange, divided into horizontal flue and tail flue. Auxiliary equipment Auxiliary equipment includes ventilation equipment (feed, induced draft fan), fuel transportation equipment, powder system, ash removal and dust removal equipment, desulfurization equipment, etc.