The Composition Of Power Plant Boilers

The entire boiler is composed of two parts, the boiler body and auxiliary equipment.
Boiler:
The boiler body is the main part of the boiler equipment, which is composed of two parts: the "boiler" and the "furnace". "Boiler" is a soda system. Its main task is to attract and collect the heat released by the fuel, so that the water is heated, evaporated and finally turned into superheated steam with certain parameters. It consists of economizer, steam drum, downcomer, header, water wall, superheater, reheater and other equipment and its connecting pipes and valves.
(1) Economizer. Located in the vertical flue at the end of the boiler, the waste heat of the flue gas is used to heat the boiler feed water, reduce the exhaust gas temperature, improve the boiler efficiency, and save fuel.
(2) Steam drum. Located at the top of the boiler, it is a cylindrical pressure vessel with water under it and steam at the top. It receives water from the economizer and at the same time forms a water circulation loop with the downcomer, header and water wall. The steam-water mixture generated by the water absorbing heat in the water wall is collected in the steam drum, and the saturated steam is sent to the superheater after the steam-water separation.
(3) Drop tube. It is the water supply pipe of the water wall, and its function is to introduce the water in the steam drum into the lower header and then distribute it to each water wall pipe. There are two types of small-diameter dispersed downcomers and large-diameter concentrated downcomers. The small diameter downcomer has a small diameter, which is not good for water circulation.
(4) The lower header of the water wall. The main function of the header is to gather the materials together, or to redistribute the working fluid to other pipelines through the header through the header. The lower header of the water wall is a thicker tube with closed ends. Its function is to connect the downcomer and the water wall to collect, mix and redistribute the working fluid.
(5) Water wall. Located around the furnace, its main task is to absorb the radiant heat in the furnace and evaporate the water. It is the main heating surface of modern boilers and at the same time protects the furnace wall.
(6) Superheater. Its function is to heat the saturated steam from the steam drum into superheated steam with a certain temperature.
(7) Reheater. Its function is to heat up the steam that has done part of the work in the steam turbine again, and then send it to the steam turbine to continue doing work.
The "furnace" is a combustion system, and its task is to make the fuel burn well in the furnace and release heat. It consists of a furnace, a burner, an ignition device, an air preheater, a flue duct, a furnace wall, and a frame.
(1) Furnace. It is converted from the furnace wall and the water wall for 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 mixed well in the furnace to ensure that the fuel catches fire in time and burns quickly and completely. There are two basic types of direct current burners and swirl burners.
(3) Air preheater. Located in the flue at the end of the boiler, its function is to use the waste heat of the flue gas to heat the air required for fuel combustion, which not only can further reduce the exhaust gas temperature, but also is beneficial for strengthening the combustion in the furnace, improving the economics of combustion, drying and transporting pulverized coal. of. The boiler efficiency can be increased by about 2%. There are two types: pipe type and rotary type.
(4) Smoke duct. It is a pipe composed of furnace wall, partial heating surface pipes and wall-clad pipes, which is used to guide the flow of flue gas and exchange heat through each heating surface. It is divided into horizontal flue and tail flue.
Auxiliary equipment
Auxiliary equipment includes ventilation equipment (supply and induced draft fans), fuel transportation equipment, pulverizing system, ash and dust removal equipment, desulfurization equipment, etc.