What are the classifications of coal-fired boilers?

coal-fired boiler refers to the boiler equipment with bituminous coal, lean coal, anthracite and other kinds of coal as fuel. There are many kinds of coal-fired boilers in the market, and users often can't distinguish them correctly. What are the classifications of coal-fired boilers, and how many kinds of boilers are included?

Principle of coal-fired boiler

Before introducing the classification of coal-fired boilers, let's first understand what coal-fired boilers are. Coal-fired boiler is composed of two parts: a boiler drum and a furnace. The boiler drum is a metal container for holding water, and its function is to absorb the heat energy released by burning fuel, so that the water in the boiler can be heated to a certain parameter range to form steam.

It is composed of flue gas preheater, steam drum, downcomer, header pipe, water wall pipe, drum, steam-water separator and other equipment, as well as connecting steam pipe and valve surface, induced draft fan and blower, etc. The "furnace" is the part where fuel is burned for heat conversion, and the softened water in the pot absorbs the heat generated by the fuel in the furnace to form steam.

What are the classifications of coal-fired boilers?

a. Medium: coal-fired hot water boiler, coal-fired steam boiler, coal-fired steam-water boiler and coal-fired heat conduction oil boiler.

b. Circulation mode: natural circulation boiler and controlled circulation boiler. Forced circulation boiler includes controlled circulation boiler, once-through boiler and compound circulation boiler.

c. Drum placement: vertical coal-fired boiler and horizontal coal-fired boiler

d. Combustion mode: stratified combustion boiler, suspension combustion boiler, cyclone combustion boiler and circulating fluidized bed boiler.

e. Pressure

(1) Supercritical boiler, P≥22.1MPa

(2) Subcritical boiler, 16.7MPa≤P＜22.1MPa

(3) Ultra-high pressure boiler, 13.7MPa≤P＜16.7MPa

(4) High pressure boiler, 9.8MPa≤P＜13.7MPa

(5) Secondary high pressure boiler, 5.3MPa≤P<9.8MPa

(6) Medium pressure boiler, 3.8MPa≤P＜5.3MPa

(7) Low pressure boiler P≤2.5MPa

(8) Atmospheric pressure boiler

f. Package method

Quick-installed boiler: The so-called quick-installed boiler is also called a packaged boiler. The boiler is fully installed in the manufacturing plant, and the whole machine is shipped to the operation department to ensure the quality of the boiler's manufacturing and installation.

Assembled boilers: Assembled boilers are generally divided into two or three bodies. They are assembled on site. The heating surface of the boiler is basically welded in the boiler plant. Only a few connecting pipes are welded on site, and the furnace wall is built on site.

Bulk boilers: The combustion equipment and heating surfaces of bulk boilers are all shipped from the factory, assembled on site. The heating surfaces, boiler steel structures, and combustion equipment must be welded on site, and the furnace walls must be built on site.

After more than 30 years of manufacturing boilers, at present, ZOZEN has formed a variety of specifications such as gas boilers, biomass boilers, coal-fired boilers, circulating fluidized bed boilers, organic heat carriers, etc., which are widely used in chemical, food, brewing, heating, paper making, printing and dyeing, rubber and other industries.