Method of large-proportion coal slime blending combustion of circulating fluidized bedboiler

Abstract

The invention discloses a method of large-proportion coal slime blending combustion of a circulating fluidized bedboiler. The method comprises the steps of (1) coal slime screening; (2) coarse slime unloading; (3) coarse slime airing and drying; (4) conveying of humidity-qualified coarse slime to a coal handling system; (5) coal conveying of the coal handling system; (6) coal feeding of the circulating fluidized bedboiler; and (7) combustion of fuel coal in the circulating fluidized bedboiler. The method of large-proportion coal slime blending combustion of the circulating fluidized bedboiler has the advantages that after low bed pressure operational optimization is implemented, the boiler efficiency reaches up to 91.9% and is increased by 1.9% when compared with a design value, the vibration of a material return device is effectively controlled, and the abrasion of a boiler heating surface is reduced; by means of implementation of low oxygen combustion optimization, the cost can be reduced by 4,800,000 RMB annually, and the standard coal can be saved by approximately 5,120 tons annually; and the generation of part of nitric oxide can be inhibited from the angle of combustion, and the urea usage amount of an SNCR system can be reduced.

Description

Technical field: [0001] The invention relates to a method for mixing coal slime in a boiler, in particular to a method for mixing coal slime in a large proportion in a circulating fluidized bed boiler. Background technique: [0002] my country's coal output ranks first in the world, and the depth and breadth of coal processing are developing rapidly. The quality of various coals is complex and changeable, especially coal slime. The output of coal slime is increasing year by year. The comprehensive utilization of coal slime has become an urgent problem to be solved. question. Since coal slime is a kind of discharge during the coal washing process, the particles contained in it are very fine (usually below 0.5mm), and the overall properties are high moisture (water content between 25% and 40%), high Viscous, high water holding capacity, high ash content, at the same time, because the coal slime is used as waste in the coal washing plant, there are many impurities in the coal s...

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Problems solved by technology

The amount of ash in the external circulation of the boiler increases, and the differential pressure of the furnace during full-load operation can reach 1.8KPa. The advantages of direct calcium injection desulfurization, but for the increasingly stringent environmental protection emission requirements, in the face of the control of flue gas sulfur dioxide emission value at 200mg / m 3 The following requirements require the boiler to strictly control the operating bed temperature and maintain a relatively high calcium-sulfur ratio to ensure the basic stability of the parameters; since the average water content in the coal slime is about 17%, a large proportion of coal slime is mixed with coal, with The boiler flue gas volume from the boiler increases, which makes the boiler run at a large air volume for a long time, the concentration of the circulating material is high, the flue gas flow rate is high, the erosion and wear of the heating surface are serious, and the power consumption of the boiler auxiliary equipment is high, resulting in a high power consumption rate of the production plant. No less, the more prominent problem in the high load process in summer is the high exhaust gas temperature, and various problems caused by the operation of large air volume directly restrict the long-term safe and economical operation of the boiler

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