Mechanism And Experimental Study About Fouling And Slagging Of High Alkaline Coal In Xinjiang Province

The high alkali coal reserves located in Zhundong(Xinjiang Province,China),are huge.However,fouling,slagging,and corrosion caused by using this type of coal in a pulverized coal furnace is still the biggest challenge.Due to this,more and more power plants are quitting the use of high alkali coal in a pulverized coal furnace.In this study,the mechanism and characteristics of fouling,slagging,and corrosion of the high alkali coal samples from Zhundong area are analyzed and compared.As well,the reaction conditions and the influence of some important parameters are also discussed.Chemical reaction control method is applied to prevent the fouling,slagging,and corrosion problems in the boiler for the Xinjiang coal samples.The worldwide used index of fouling and slagging is analyzed,as well,the application conditions and reaction mechanisms are confirmed by literature review.Three different types of coal: Jinggong coal,Xiheishan coal,and Nenghua coal are burned,and the results predicteded by index are compared with the experimental results.It is found that these indexes are not good enough to predict the difference of fouling and slagging among coals.Therefore,it is still necessary to conduct experimental research to find regularity of fouling and slagging.High-tech machine and analytic instruments are applied for element analysis,industrial analysis,ash melting point analysis,synchronous thermal analysis,and ash element analysis,which definitely helps researchers understand the combustion characteristics of different coals.On the basis of modularization,visualization,and easily-modified,the 60 KW coal-fired boiler test is designed and built,including the reliable data collecting system,well-performed fluidized feeder,temperature control system and measurement system of flue gas composition.The influence of specific parameters(such as flue gas temperature,wall temperature,coals,the coating on tubes,the arrangement of tube bundle)on actual fouling and slagging are fully discussed;The experimental results show the distribution law of wall temperature of tube,finding fouling and slagging mostly happen in face of tube,fouling also happen in side while ash deposition largely happens in back of tube.Element Ca is mainly deposited in back position,while Fe obviously stains in face and side of the tube.Element K is also easily found in ash and stain,which means Na & K should be payed attention equally when coals are choosed to burn in boiler.Element Na and S are mainly found in face of tube,comparing to back of tube,which shows the important link between Na&S and fouling Ash percentage in coal largely decides the level of fouling and slagging of coal-more ash,more fouling and slagging.Last but not least,the effectiveness of nano-ceramic coating,which designed to prevent slagging and corrosion,is also verified.