Method and system for preventing boiler heating surface from being contaminated through circulation of wearable materials

Abstract

The invention discloses a method and a system for preventing a boiler heating surface from being contaminated through circulation of wearable materials and belongs to the field of boilers. The method comprises the following steps of sending mixtures of the wearable materials and granular fly ash into burning wind region of a boiler, mixing the mixtures with exhaust gas of the boiler, and circularly recycling the wearable materials and the granular fly ash. The system comprises a circulated material caching tank, wherein a material outlet of the circulated material caching tank is communicated with the burning wind region of the boiler, a material inlet of the circulated material caching tank is communicated with a coal economizer ash bucket, a denitration inlet-outlet ash bucket, an air pre-heater ash bucket in the boiler as well as one or multiple parts in a first electric field of a dust remover, the circulated material caching tank is provided with a material feeding hole, and a pipeline for communicating the material outlet of the circulated material caching tank with the burning wind region of the boiler is further communicated with a primary hot wind branch pipe. by utilizing the method and the system, the convection heating surface of a high-sodium coal burning boiler can be prevented from being contaminated, the heating surface can be prevented from being seriously contaminated with low initial investment and operation costs on the basis that the structure of the boiler is basically unchanged, and the Zhundong (a region in a Uygur Autonomous Region) high-sodium coal can be completely burnt by the boiler.

Description

technical field [0001] The invention belongs to the field of boilers. Background technique [0002] The Xinjiang region is rich in coal resources. Only the Zhundong Coalfield has a cumulative proven coal resource reserve of 213.6 billion tons and a predicted reserve of 390 billion tons. It is currently the largest integrated coal field in my country. However, Zhundong coal has a high content of alkali metals and has serious slagging and pollution characteristics. [0003] During the combustion of coal particles, all the sodium salts in the ash will be released and exist in the flue gas in the gas phase. When the gas phase sodium salt contacts the heating surface with a lower temperature, it condenses and gathers on the surface of the tube, and absorbs the ultrafine ash in the flue gas to form a contaminated inner layer. On the boiler burning high sodium coal, as the gas phase sodium salt continues to Condensation and capture of fly ash particles in the flue gas make the fo...

AI Technical Summary

Problems solved by technology

When the gas phase sodium salt contacts the heating surface with a lower temperature, it condenses and gathers on the surface of the tube, and absorbs the ultrafine ash in the flue gas to form a contaminated inner layer. On the boiler burning high sodium coal, as the gas phase sodium salt continues to Condensation and capture of fly ash particles in the flue gas make the fouling layer grow continuously, resulting in the thickening of the fouling layer on the pipe wall, and finally covering the entire pipe wall. The fouling layer becomes very hard. Conventional boiler steam sootblowing has If it cannot be removed, the heat transfer effect of the convection heating surface will be greatly reduced, which will directly affect the long-term safe and stable operation of the boiler.

[0004] The boilers that were put into operation in the early stage were forced to shut down because of the convective heating surface being covered and blocked after burning Xinjiang high-sodium coal.

The boilers put into operation in Xinjiang recently cannot all burn Zhundong high-sodium coal. They all need to be blended with Wudong low-sodium coal in different proportions (about 30% to 50%), which greatly increases operating costs and reduces unit capacity. operating economy

Judging from the situation of materials such as diatomite and low-sodium coal boiler fly ash blended in the inventor's laboratory, the amount of blended firing required is extremely large, and it is difficult to popularize and apply them in actual operating boilers.

After a large number of boilers burning high-sodium coal are put into operation, it will be more difficult and costly to find low-sodium coal or other material resources for blending

For high-sodium coal in Xinjiang, the current measures taken in boiler design are mainly to enlarge the furnace size, increase the distance between burners, increase the number of sootblowers, increase the pitch of convective heating surfaces, etc., which will greatly increase The cost of equipment and the contamination of the convection heating surface still cannot be eradicated

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