Optimization Of CDQ Process And Improvement Of Equipment Structure

The CDQ process is a way to extinguished red hot coke by inert gas,which has significant advantages in improving coke quality.It is widely used in the ironmaking industry due to its high quality coke production,low coke ratio and high productivity.In recent years,CDQ technology has also been gradually promoted and widely used in the coking industry and blast furnace ironmaking.This paper aims at many problems that affect the coke quality in the CDQ production process of X enterprise in Gansu Province,such as unsatisfactory control of coke maturity,large fluctuation of coke discharge temperature,large fluctuation of pre-storage section pressure,difficulty in adjusting circulating gas,the coke burning loss rate is high,the unsuitable gas-to-material ratio,uneven coke release when mixing dry and wet coke,and easy leakage of water from the top water seal tank and so on.The influence of CDQ process on coke quality and the structure optimization design of CDQ equipment were studied.The large-scale research aims to master the optimal CDQ process and the optimal design of key equipment,so as to lay a certain theoretical foundation and practical experience for the sustainable development of CDQ technology.（1）Research of the influence of CDQ process on coke qualityThe coke obtained by the CDQ production process not only has high uniformity,which is conducive to the stable production and operation of the blast furnace,but also has high crushing resistance and low reactivity,which can effectively improve the utilization rate of blast furnace ironmaking coke.The coke obtained by the CDQ production process not only has high uniformity,which is conducive to the stable production and operation of the blast furnace,but also has high crush resistance and low reactivity,which can effectively improve the utilization rate of blast furnace ironmaking coke.In this study,four material level gauges were proposed to detect material level,including two upper material levels,one lower material level,and one gamma ray in the middle of a pre-storage chamber are forced to correct the material level.During the CDQ operation.In order to ensure the stability of the coke,the material level is controlled between theγ-ray forced correctio and the upper limit material level,and the material level and pressure of the CDQ pre-storage section are well controlled.The combustible gas is diluted by the air-conduction method and the supplemental nitrogen method,which alleviates the problem that the concentration of combustible components threatens the safe production of coke.The research results show that the air-conduction method can effectively reduce the amont of nitrogen consumed by the CDQ system.In addition,the influence mechanism of the air-to-charge ratio on the coke quality was studied,and the internal relationship between the circulating air volume and the number of CDQ ovens was mastered.In order to prevent the boiler inlet temperature dropping too quickly,the air-to-charge ratio was set to 1250 m³/t.By increasing the range of CO content,introducing some nitrogen,checking the tightness of the system,and remodeling the heat pipe heat exchanger,the O₂content of the system was reduced from 1.0%to 0.2%,and the coke discharge temperature was reduced from 200℃to 150～180℃,which greatly controls the O₂content in the CDQ system,effectively reduces the coke burning loss rate,and achieves a significant improvement in coke quality.（2）Structure optimization design and transformation of CDQ equipmentFirst of all,focusing on the problems of high coke discharge temperature,large system resistance,and easy coke floating in industrial CDQ furnaces,relying on the existing steel structure of CDQ furnaces,optimize and transform parts such as corbels and inner ring walls in the chute area.After the transformation,the circulating air volume was increased from 145000m³/h to 160000m³/h,and the CDQ rate was increased from 90%to more than 95%.The steam recovery per ton of coke was increased by 19.1 kg/t,and the coke discharge temperature was decreased by 20°C.At the same time,the suction of the boiler inlet was increased.From-1.3 KPa to about-1.0 KPa,the problem of coke floating is solved.Secondly,the adjustment plate at the exit of the chute was remodeled and replaced,and the adjustment plate made of mullite silicon carbide with resistance to rapid cooling,rapid heating and erosion was selected instead of the original stainless steel wear plate,which completely solved the problem that the adjustment plate was easily deformed and fell off.In addition,we have optimized the structure of the chute area of??the CDQ:the partition wall is divided into two layers,the chute area is divided into three parallel airflow channels,and a boss structure is formed at the edges of the two adjacent layers of corbels to separate the Both ends of the wall are erected on the corresponding boss structures.The CDQ rate of the improved coke oven reaches 95%,the steam recovery per ton of coke is increased by 30kg/t,the coke quality is significantly improved.At the same time,the coke in the CDQ furnace chute no longer floats frequently.On the basis of the present,the circulating air volume is increased to more than 10,000 Nm³/h,the coke discharge temperature also meets the original design requirements,and the CDQ rate is increased by about 5%.Finally,the material of the water seal on the top of the CDQ furnace was improved,the original water seal groove made of ductile iron was replaced with a Q235 water seal groove,and the right-angle welding connection between the bottom and the side wall of the original water seal groove was changed to one time.The two half-ring groove bodies are formed by vertical seam welding,which prevents the cooling water from flowing into the CDQ and improves the coke quality.