Coal fines high-temperature pre-warming method

Abstract

The invention relates to a coal powder high temperature preheating method which relates to the technology of coal powder combustion. The coal powder is added in the middle and lower part of the firebox of an insulating circulating fluid bed and little air is conducted in the bottom part; a part of the coal powder is burnt. The coal powder is heated to between 800 DEG C and 1300 DEG C and the high temperature coal powder enters a cyclone separating device with the flue gas; a part of the coal powder is collected by the cyclone separating device and returned to the firebox through a material returning device; the rest coal powder is sprayed into an inflamer of a coal powder boiler with the flue gas to burn. The invention has the advantages of broad application, good combustion stability and can also cooperate with a classified air distribution technology to control the uniformities of the temperature level and distribution of a furnace, thereby greatly reducing the exhausting of NOx.

Description

technical field [0001] The invention relates to the technical field of combustion, and relates to a pulverized coal combustion method, in particular to a pulverized coal high-temperature preheating method. technical background [0002] In the early 1990s, Japan’s Tanaka et al. proposed high-temperature air combustion technology. The air used for combustion can recover the waste heat of the flue gas to the maximum extent, so that the air temperature can be preheated to above 800°C; at the same time, the fuel is burned in a low-oxygen atmosphere. Realize ultra-low emission of NOx. This combustion method has the dual advantages of high efficiency, energy saving and low pollution emission. Practice shows that the energy saving of gas fuel can reach 60%, and the pollutant emission can be reduced by 25%. High-temperature air combustion technology has achieved good environmental and economic benefits in the industrial application of gas fuels. [0003] In 1999 and 2002, the Japan...

AI Technical Summary

Problems solved by technology

[0004] However, compared with the high-temperature air combustion of gas fuels, there is a problem in the high-temperature air combustion of pulverized coal: the specific heat of pulverized coal is much greater than that of general gas fuels. After mixing pulverized coal with high-temperature air at room temperature, the temperature of high-temperature air will be significantly reduced. To a certain extent, it affects the effect of high temperature air combustion

[0005] Chinese patent application 93107510.6 discloses a fluidized bed pulverized coal pre-combustion heating burner. A small fluidized bed pulverized coal pre-combustion heating chamber is arranged outside the pulverized coal primary air nozzle, in order to burn difficult-to-combustible coal and solve the problem of coal burning. Combustion support is usually required for pulverized boilers at low load

However, since the fuel added to the fluidized bed pulverized coal pre-combustion heating chamber is pulverized coal, its particle size is generally less than 200 μm, instead of the coal with a particle size usually between 0 and 5 mm added in a conventional fluidized bed combustion chamber. Particles, so the characteristics of the conventional fluidized bed combustion chamber are difficult to achieve in the pulverized coal pre-combustion heating chamber

Specifically, the fluidized bed described in the patent application is operated with hot bed material, which is difficult