What are the classifications of coal-fired boilers?

What are the classifications of coal-fired boilers? The following Zhongda Consulting Tendering Teacher will give you answers for your reference.

There are many types of coal-fired boilers, which can be classified according to combustion method, slag removal method and structural installation method.

It can be divided into 4 types according to the combustion method. ① Layer burning furnace: After the raw coal is broken into pieces with a particle size of 25 to 40 mm, it is spread flat on the chain grate using the coal gate of the coal hopper in front of the furnace or the coal spreader for layer burning. The advantage of the layer-burning furnace is that it has fewer ancillary equipment, is easy to manufacture and install, and is easy to operate. Suitable for small and medium capacity boilers. The disadvantages of this kind of boiler are incomplete coal combustion, high combustible content in slag and fly ash, and boiler efficiency is generally 75 to 85%. Usually better coal is burned. ② Chamber burning furnace: also called pulverized coal furnace. After the raw coal is screened, crushed and ground into pulverized coal with most particle sizes less than 0.1 mm, it is injected into the furnace through the burner for suspension combustion. Pulverized coal can quickly catch fire after being sprayed into the furnace, and the flue gas can reach a high temperature of about 1500°C. However, the relative motion between the pulverized coal and the surrounding gas is very weak. The pulverized coal needs to stay in the larger furnace for about 2 to 3 seconds to be basically burned. Therefore, the furnace volume of the pulverized coal furnace is often larger than that of the layer-fired furnace with the same evaporation amount. About twice as big. The advantage of this kind of boiler is that it can burn various coals and the combustion is relatively complete, so the boiler capacity can be made very large, and it is suitable for large, medium and extra large boilers. Boiler efficiency can generally reach 90 to 92%. Its disadvantages are that there are many ancillary machines, high automation level requirements, boiler feed water must be treated, and large infrastructure investment. ③Cyclone furnace: The crushed coal particles or coarse coal powder with a particle size of less than 10 mm are first burned in a cyclone shape in the front-mounted cyclone cylinder, and the high-temperature flue gas generated then enters the main furnace (cooling chamber) for radiation heat exchange. . The advantages of the cyclone furnace are the high thermal intensity of the furnace volume and the small size of the furnace; the small excess air coefficient (only 1.05 to 1.10) can reduce the loss of exhaust heat; the use of coarse coal powder can simplify the pulverizing equipment; the slag discharge rate High, low fly ash concentration, increased flue gas velocity to enhance heat transfer on the convection heating surface. Its disadvantages are that the applicable coal type is limited by the ash melting point and the viscosity of the slag; the boiler load changes within a small range; it cannot start and stop quickly; because the temperature in the furnace can reach about 2000°C, the harmful gas NOx emissions are large, which pollutes the atmosphere. More serious. ④ Boiling combustion furnace: that is, boiling combustion boiler.

It can be divided into two types according to the slag removal method. ①Solid-state slag removal furnace: The molten slag in the furnace is solidified in the cold ash hopper or slag condensing box at the bottom of the furnace and then discharged. Suitable for burning coal with higher ash melting point. ②Liquid slag removal furnace: There is an insulated molten pool at the bottom of the furnace. The molten slag flows out through the slag discharge port (or is discharged after being solidified by cold water), or is blown into slag wool by steam and discharged (can be used as insulation material).

It can be divided into two types according to the structural installation method. ①Suspended boiler: The boiler furnace and steering smoke chamber are suspended from large plate frame beams erected on reinforced concrete columns using suspenders. The advantage of a suspended boiler is that the furnace body can expand freely, is easy to be shaken, saves steel, and has a large space under the furnace bottom for easy arrangement of air blowers and ash removal equipment. However, the technical requirements for installation are high. ②Supported boiler: The boiler is supported entirely on a frame-shaped frame. It is characterized by easy installation and small footprint, but consumes a lot of steel.

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