Volatility Of Heavy Metal During Coal And Petroleum Coke Gasification

In coal utilization, the emissions of heavy metal element such as mercury, cadmium, lead, chromium,nickel and arsenic emissions has brought serious pollution to the environment. Clean coaltechnology---coal gasification technology, can significantly improve the utilization rate of coal. As a result,the research on the laws of the heavy metals during coal and petroleum coke gasification has afar-reaching significance on heavy metal pollution control.In this paper, two large pieces of content about heavy metal elements in the process of the coal,petroleum coke gasification reveal mercury, cadmium, lead, chromium, nickel and arsenic migrationtransformation rule. A thermodynamic simulation has been done first, and lay a solid theoreticalfoundation, and then carry out a series of experimental research, provide powerful experimental support.The two complement each other to explore the factors influencing the release of heavy metals in theprocess of coal gasification.HSC thermodynamic calculation shows that the heavy metals mainly exists chloride, oxides, sulfidesin the gasification process. mercury, chromium, arsenic and cadmium in low temperature, mainly exists inthe form of chloride, with the increase of temperature, chromium, arsenic in the form of oxide, mercuryand cadmium exists in elemental form.Mercury migration experiment show that temperature and atmosphere heating way, gasification, coalsample components and vaporization rate are the factors to influence the rate of volatile of mercury incoal gasification. With the increasing of temperature, the volatilization rate of mercury increases,Programmed mode of vaporization rate is higher than the rapid warming of the vaporization rate; thevaporization rate and the rate of the volatile mercury under water atmosphere is higher than CO2atmosphere,The increasing of water content promote the raw materials of gasification; With theincreasing of gasification rate, the volatilization rate of mercury increased, With the increasing of Scontent, mercury volatilization rate increased.Icp-ms experimental results show that the temperature is the key factors influencing volatilizationrate of heavy metals. With the increasing of temperature, volatilization rate of heavy metal elements Pb,As, Cd, Cr and Ni increased. Pb, As and Cd is easy to volatile, Cr and Ni is hard to volatile. Programmedmode of heavy metal evaporation rate is higher than the rapid heating volatilization rate of heavy metals.Field sampling experiment results show that the gasifier type has small impaction of trace elementsof mercury, cadmium, lead, arsenic, chromium distribution, but type furnace for nickelhas greater influence on the distribution of trace elements.Mercury and cadmium are mainly distributed inthe gas phase, Lead is released into the gas content about25.5%---59.8%, low content in the waste water.Trace element arsenic are mainly distributed in the slag samples, in the coarse slag percentage is higherthan the percentage in the fine slag. Chromium are mainly distributed in the slag samples, released into the gas phase product about40%. Trace elements of nickel in the multi-nozzle furnace coal gasificationare mainly distributed in the slag samples, mainly in the Texaco coal gasification furn.