Study On NO_x Pncmsors Formation During Coai Gasifcation

In this paper, different gasification conditions that affect the yield of NOX and its precursors, HCN and NHs, during coal and char gasification with CO2 and steam are considered. The factors concerned are coal type, reaction temperature, particle size of coal, gas flow rate, coal feeding methods, reaction time and gasification agents.Some useful results and conclusions are acquired as followings:(1) Gasification of volatile is the major source of HCN and NO formation.(2) With an increase of reaction temperature, the yields of HCN will increase, that of NO will decrease. And there is a maximum value for the yields of NH3 at 800℃.(3) NO may be reduced by CO and char during gasification.(4) Coal and char gasification efficiency with steam is much higher than with CO2.(5) The yield of gaseous nitrogenous compounds is the highest under coal gasification with steam, is the lowest under char gasification with CO2.(6) Coal gasification with steam needs much more time than coal gasification with CO2.(7) During coal and char gasification, the release speed of NHs is slower than that of HCN.(8) It is deduced that nitrogen bonds in Drayton coal are probably more stable than in Shenmu coal.(9) With the same gasification agent, temperature and reaction time are two key factors that affect the yield of HCN and NH3 during coal and charchar gasification.