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Experimental Study On High Efficiency Combustion Of Anthracite In A 440t/h CFB Boiler

Posted on:2007-08-26Degree:MasterType:Thesis
Country:ChinaCandidate:F ZhangFull Text:PDF
GTID:2132360185987718Subject:Engineering Thermal Physics
Abstract/Summary:PDF Full Text Request
For its advantages of low pollutant emission and adaptability to fuels et al, CFB boiler is considered to be the most suitable boiler for burning anthracite.So more and more CFB boilers are used to bum anthracite in China.But due to long burnout time of anthracite and low combustion temperature in CFB boiler, there is a problem that the carbon content of fly ash is so high that the combustion efficiency is lower than the designed efficiency when burning anthracite in CFB boiler.Aiming the problem, an experimental study on optimal combustion experiment for a 440t/h CFB boiler of Lianzhou Power Plant was proceeded in this thesis.The thesis first introduced the research background and summarized ignition characteristic of anthracite,the factors affecting on its burnout in CFB boiler and the shortage of the existing research.In order to understand the combustion characteristic of anthracite better and proceed the optimal combustion experiment more effectively,an experiment was carried out on coal pyrolysis and combustion with TGA to compare the kinetic parameters of pyrolysis and combustion reactions of the anthracite bumt in Lianzhou Power Plant with these of a typical bituminous coal.The result shows that the reactivity of anthracite is much worse than bituminous coal.In the optimal combustion experiment,the effects of oxygen content of flue gas,secondary air coefficient, Ca/S, boiler load on boiler efficiency and main heat loss were studied. The burnout characteristic of anthracite was analysed by measuring particle size and carbon content distribution of fly ash and slag.The effects of operation paraments on burnout of anthracite were also studied.In addition,emission characteristic of combustion pollutant was tested. Basing on these studies, measures were put forward to improve boiler efficiency and burnout of anthracite,and reduce total emission of combustion pollutant.After the optimal combustion,the boiler efficiency increased 1.59%, achieving the designed efficiency nearly.Furthermore,the distribution of temperature in the boiler and the heat transfer characteristic of the superheaters.economizer and air heater in the backpass of boiler and their primary effect factors were analyzed.The heat transfer coefficients were also calculated and compared with the design values.It was found that actual heat transfer coefficients were 40% larger than designed ones ,so that the areaes of heat exchangers were 1/3 larger than needed.It was one reason for that the flow of desuperheater spray water was far larger than design value.By theoretics study and optimal combustion experiments for the practical CFB boiler,some suitable operation measures for the CFB boiler burning anthracite were put forward,which offered a good reference for the optimal operation of large CFB boilers burning anthracite.
Keywords/Search Tags:Anthracite, CFB boiler, Optimal combustion, Burnout
PDF Full Text Request
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