Study On Characteristics Of Coke And Steamgasification

In china,coal clean conversion technology is significant development tendency in future,especially when we face the current coking industry overcapacity domestic,independent coking enterprises exploring new ideas,new technology development.To extend the coking industry and improve the competitiveness,we should use surplus coke production capacity to produce gasification coke and LNG.In many coal gasification studies,little attention has been paid to the gasification performance of coke gasification.In this paper,the progress of research on reaction of coal gasification in China and abroad is reviewed,and the mechanism of gasification reaction is discussed.In the experiment,we make use of several coking coal,such as leaching coal,fat coal,1/3 coking coal,gas coal,to produce stamping coke in 10 kg coke oven respectively.The characteristics of coke and water vapor about gasification reaction were studied on micro-fixed-bed gasification reactor.The effects of particle size of coke and steam fiow rate on the characteristics of gasification reaction were also investigated.The results show that with the decrease of the particle size of coke,the carbon conversion rate of lean coke or fat coke at the reaction temperature of 1000 ? and at the same time shows an increasing trend,and the conversion rate stabilizes after 190 min.At a certain reaction time,with the increase of steam flow rate,the carbon conversion rate tends to increase,and at 200 min,the carbon conversion rate also tends to be stable.In the experiment,in order to adjust the experimental conditions of the gasification reaction devicefurther,the influence of internal diffusion and external diffusion on coke gasification reaction characteristics can be eliminated when the coke particle size is less than 3mm and the steam flow rate is more than 1.5ml / min.In addition,in order to explore the gasification reaction characteristics of different coal species at different temperatures further,the influence of the metamorphic degree of raw coal on the gasification reaction under the same gasification conditions was experimentally studied.While the lower the degree of coal metamorphism is lower,the average diameter of the pores of the coke will gradually increase,the porosity will gradually increase,the corresponding coke reactivity is gradually increased.While the average thickness of the stomatal wall gradually decreases,the gasification reactivity with water vapor is better and better.With the increase of gasification temperature,the carbon conversion rate of coke produced by various kinds of coking coal is increasing,which shows that the gasification reaction of coke and steam is controlled by chemical reaction under the experimental conditions.In order to study the mechanism of gasification reaction further,the experiment was based on previous research on the kinetic model of coal gasification.In this paper,the kinetics of gasification reaction of coke and steam prepared by different coking coal was studied,and activation energy and pre-exponential factor were obtained.The experimental results show that the homogeneous model can describe the whole gasification process much better in this experimental setup and under certain gasification conditions.While the contractionfree core model and the random-pore reaction model are both limited by experimental conditions and models.So the simulation of the whole reaction process has some limitations.What's more,the results are as follows.The activation energy of lean coal coke is 115.2kJ.mol-1,the coke of fat coal is 104.6kJ.mol-1,the coke of 1/3 coke is 89.6kJ.mol-1,and the coke of gas coal is 70.0kJ.mol-1.Finally,in order to explore the effect of adding a certain percentage of long flame coal on the gasification reaction characteristics further,we added 8% long flame coal to gas coal.The results showed that long flame coal could reduce the activation energy of gas coal coke,which made the coke easier to gasify.