Optimization and economic analysis of whole process design of a 5 000 t/d oxy-fuel combustion cement kiln

GAO Siyuan; DUAN Yuanqiang; DUAN Lunbo; MA Lei; YANG Hongcai; YANG Yu

doi:10.13226/j.issn.1006-6772.CBJ24123101

Abstract：As a major country of infrastructure,Chinese cement industry has high carbon emissions and it needs a suitable carbon emission reduction plan.As a carbon emission reduction scheme,oxy-fuel combustion has the advantages of low carbon capture cost and good capture effect,which is of great significance to the carbon emission reduction of the cement industry.However,the scheme design of the whole process and the system optimization corresponding to the actual production are still lacking.A process simulation model was established using Aspen Plus software with a dry cement production line with an approximately daily output of 5 000 tons as the reference object,and the accuracy of the model was verified.On this basis,the whole-process design of oxy-fuel combustion in cement kilns was carried out.Through process optimization and overall system heat matching,the air leakage coefficient was effectively reduced,and the CO2 concentration in the flue gas was increased.A carbon capture model for oxy-fuel combustion in cement kilns was built to study the carbon capture effect and energy consumption of cement kilns under oxy-fuel combustion conditions,determine the optimal operating conditions,and calculate the carbon capture cost.The results show that under basic operating conditions,the concentration of CO2 in wet basis of the flue gas is 79.7％,and the purity of CO2 after compression purification is 99.5％.The CO2 recovery rate of the system can reach 97.3％.Analyzing the impact of various influencing factors on system energy consumption,it was found that when the oxygen supply concentration is 97％,the air leakage coefficient is 0.03,the flue gas circulation ratio is 0.46,and the mixed oxygen concentration is 30％,the carbon capture energy consumption is the lowest.In addition,the high concentration of O2 in the combustion atmosphere can facilitate the co-firing of inferior coal and effectively reduce fuel costs.Under optimal operating conditions,calculated based on an annual operating time of 6 000 hours,the annual capture of CO2 is about 987 000 tons,and the additional cost of carbon capture is about 185 million yuan per year,equivalent to a unit carbon capture cost of 187.4 yuan/t,which is at a leading level.