Fundamental Research Of Application On Dry Coal Coking Technology

China is a large coke producer in the world,but currently the coking industry is still high energy consumption,high pollution and high resource consumption.Since that,under the background of“carbon peak and carbon neutralisation”（“double carbon”）goal,it has become an urgent task for the development and application of green coking process.Relying on the National Key Research and Development Program of China"Key Technologies for Green Steel Process"project（No.2017YFB0304303）,this research focusing on the problems such as long coking cycle,high energy consumption,difficult coking wastewater treatment and shortage of high-quality coking coal resources,the fundamental problems of application on dry coal coking technology are studied by experimental test and parametric analysis by numerical simulation systematically.The main research contents and conclusions are as follows:（1）After analysis and coking experiments,the influences of moisture,dry bulk density and heating conditions on coke quality（cold strength and thermal properties）are studied.The results show that reducing the moisture content,increasing the dry bulk density of coal bed,and shortening the coking cycle when increasing the loading temperature are helpful to improve the fragmentation index(M₂₅)and coke strength after reaction（CSR）of coking.The increment of CSR by reduce moisture content is less than increasing coal bed dry bulk density.（2）Mathematical models of combustion chamber and coking chamber are established,which are used to predict the fluid flow,heat transfer and combustion behavior in combustion process and coking process of the coal bed respectively.Combined with the temperature measured by coking experiment,the differences of the equivalent specific heat model,porous media model and Euler-Euler model for predicting the coal bed coking process are compared and analyzed.The results show that,the Euler-Euler model is inadequate to consider the influence of intermediate products thermal properties on the coking process,make the predicted temperature at the center of coal bed rises too fast.Compared with the equivalent specific heat model,the porous medium model can describe the influence of gas flow on the heat transfer of coal bed in the coking process better.（3）The porous medium model is used to predict and analyse the characteristics of heat and mass transfer in the coking process in laboratory-scale coke oven,and many factors are studied in the coking process of dry coal in experimental coke oven,such as the effects of moisture content,dry bulk density,heating conditions and volatile content,and the influences on the temperature rise of coal bed,evaporation and condensation of water and the reaction of coking process are studied.Considering with the effect on the coal bed heating process,the influence of moisture content is mainly on the duration of temperature platform in the early stage of coking,and the influence of dry bulk density is mainly on the middle and late stage of coking cycle.The increase of moisture content（0 to 10%）leads to the increase of volatile component release rate in the range of coking reaction temperature（from 710K to 810K）,which increases the pore structure and decreases the CSR.（4）The coking process of coal bed in the coking chamber is simulated by the porous medium model and the heat and mass transfer characteristics of dry coal coking process and wet coal coking process are studied and compared.The simulation results predict that the dry coal coking technology can produce 13%more coke in the same coking time with 96%of the coking heat consumption of wet coal coking,and less surplus ammonia water generation,which are obvious characteristics of the green coking process.（5）By using the porous medium model,the industrial application of dry coal coking technology is predicted.The effects of the coal dryness,the temperature difference across the dividing wall and the loading amount of briquette are investigated.The results show that moisture content in the range from 1%to 3%has little effect on both the temperature rise of the coal bed and the amount of surplus ammonia water generation,but the suitability of fluidized bed drying process and coke oven production cycle should be considered.There exists a suitable temperature difference between the coke side and the pusher side of the dividing wall（in the range of 60℃to 100℃）can promote the uniform coking of the dry coal bed,and improve the uniformity of coke quality.When compared with the dry pulverized coal charging,while the"net coking time"is delayed,adding 30%briquette can reduce the coking heat consumption about9.8%.Moreover,in comparison with the conventional wet coal coking process,coking heat consumption of coke can be decreased about 13.3%,with the same"net coking time".