Combustion process method for granular coal circulating fluidized bed boiler

Abstract

The present invention discloses a combustion method for a pea coal circulating fluidized bed boiler and relates to the coal combustion technique. According to the method, pea coal particles with a diameter less than 2mm are taken as a fuel, limestone particles with a diameter less than 0.6mm are taken as a desulfurizing agent, and the fuel and the desulfurizing agent are added into a hearth. The combustion temperature in the boiler is controlled to be 850 to 950 DEG C; the fluidizing air speed is controlled to be 2 to 3.5m / s; the bed pressure drop is controlled to be 1 to 3kPa, and the primary air pressure head is controlled to be 5 to 7kPa; and when the NOx content of smoke is higher than an emission standard, ammonia water serving as a denitrifying agent is sprayed at an inlet of a cyclone separator. The pea coal with the small grain diameter serves as the fuel, so the invalid large particles content of the fuel is reduced, and the bed pressure drop and a primary air pressure head can be effectively reduced; because the height of a dense-phase area is reduced, the wear degree of a hearth heated surface can be reduced; and meanwhile, the fuel grain diameter is reduced, so that the stay time of the particles in the hearth is properly reduced, the 'inactivation' possibility of the fuel is efficiently decreased and the combustion efficiency is increased.

Description

technical field [0001] The invention relates to coal combustion technology and equipment, in particular to a combustion method for a circulating fluidized bed boiler. Background technique [0002] The circulating fluidized bed boiler is a device that uses the principle of fluidization to achieve high-intensity combustion. It has the advantages of wide fuel adaptability, low cost of combustion pollutant control, large load adjustment range, and easy comprehensive utilization of ash. Circulating fluidized bed combustion technology has been recognized as one of the clean coal technologies with the best commercialization degree in the world. [0003] In the existing circulating fluidized bed boiler combustion process, the particle size range of the fuel is wide and can vary between 0 and 6 mm. When the boiler is running, the gas-solid two-phase flow in the furnace forms a composite structure of bubbling fluidization with more large particles at the bottom and rapid fluidizatio...

AI Technical Summary

Problems solved by technology

The existence of invalid particles is equivalent to increasing the stock of materials in the combustion chamber, which brings a series of problems to the circulating fluidized bed boiler, such as the bed pressure drop and the pressure head of the primary fan are too large, the water wall is severely worn, and the combustion efficiency is low.

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