An overview of the research on heating surface coking of boilers burning high-alkali coal and its prevention
Although the reserves of high-alkali coal represented by Zhundong coal is huge,the problem of coking on heating surface of the boiler is prominent during co-firing high-alkali coals in thermal power units,which not only reduces the boiler thermal efficiency,but also seriously threatens the safe,stable and economic operation of the unit.In order to solve this problem and promote the utilization of high-alkali coal,this paper reviews the researches on coking of the heating surface of high-alkali coal boilers and the prevention.Up to now,extensive researches have been carried out at home and abroad on the characteristics of coking on the heating surface of coal-fired boilers,coking mechanism,influencing factors,prevention and control measures,and so on,and fruitful research results have been achieved.On the basis of controlling the quality of coal,improving boiler structure,and optimizing boiler operation,the preparation of coating on the heating surface of boilers has also become an important technical path for preventing and controlling coking.In the future,the coating should possess excellent comprehensive properties such as high temperature resistance,corrosion resistance,wear resistance,thermal conductivity,thermal fatigue and so on,while having outstanding coking resistance.Meanwhile,the coating also should have desirable preparation economy and preparation efficiency,especially the on-site applicability.