Influence Of Magnesium Compounds On Petroleum Coke Gasification Reaction

With the development of global petroleum towards low-quality and high-sulfurization,the digestibility of high-sulfur petroleum coke is close to saturation,and the newly increased capacity is nowhere to be released.Most of the ways to use high-sulfur petroleum coke are burned in China,which not only wastes energy but also pollutes the air.Under the general situation of energy saving and emission reduction in China,petroleum coke gasification is a good industrial development idea.It can solve the problem of the utilization of petroleum coke,and can also supplement natural gas and hydrogen energy resources.The conventional catalyst-free petroleum coke gasification process obtains a low volume fraction of natural gas or hydrogen and requires a high temperature and high pressure environment.The addition of a catalyst can reduce the temperature required for the gasification reaction,reduce the input amount of the gasification agent,and obtain a higher purity natural gas or hydrogen gas during the petroleum coke gasification process.Therefore,it is of great practical significance to use suitable catalysts to increase petroleum coke gasification activity and to understand the thermodynamic effects of catalysts on petroleum coke gasification.The magnesium compounds(MgCl2,MgO,Mg(NO3)2,and MgSO4)are used as catalysts to study the effects of catalyst type,catalyst addition amount and gasification temperature on petroleum coke-H2O gasification by thermogravimetric analyzer.The results show that the catalytic activity of MgCl2 is higher than that of other magnesium catalysts.The catalytic activity of the catalyst increases with the increase of temperature.At the same temperature,as the amount of catalyst increases,the time required for the complete conversion of petroleum coke decreases gradually.There is a limit value for the addition amount.Under the experimental conditions,the optimum addition amount of MgCl2 catalyst is 5%.The Guass model,the homogeneous reaction model,the mixed reaction model,the shrinkage core reaction model and the random pore model are used to fit the kinetic data of gasification reaction of petroleum coke with or without catalyst,while comparing with the activation energy calculated by the equivalent conversion method.It was found that the shrinkage core reaction model can better describe the kinetic characteristics of petroleum coke-H2O gasification reaction.The homogeneous model can better describe the kinetic characteristics of-H2O gasification reaction of petroleum coke catalyzed by MgCl2.Based on the Aspen Plus simulation software,a petroleum coke-steam gasification model was established.Based on the verification model,the simulation calculation of the gasification process was carried out.The thermodynamic effects of different conditions(temperature,pressure,catalyst addition,H2O/PC)on the gasification of petroleum coke to produce hydrogen-rich gas and methane-rich gas were analyzed.The results show that increasing the temperature or increasing the pressure can decrease the volume fraction of hydrogen.The volume fraction of hydrogen can increase by increasing the mass ratio of H2O to PC.As the amount of magnesium chloride increases,the volume fraction of hydrogen will increase.When the magnesium chloride is added to 5%,the hydrogen volume fraction is increased by 4%.When the mass ratio of H2O to PC is equal to 1.1,the methane volume fraction reaches the maximum.The temperature of petroleum coke gasification to obtain methane-rich gas should not be too high.Increasing the pressure is conducive to the preparation of methane gas.As the amount of magnesium chloride added increases,the volume fraction of methane increases.When the magnesium chloride is added to 5%,the methane volume fraction increases by 7%.