Comprehensive Energy Analysis And Optimization Of Cement Production System

With the development of social economy,the consumption of energy resources is growing rapidly,which makes enormous energy and environmental pressures to human.As an important industry of the national economy,the cement industry always consumes huge energy resources,along with low energy efficiency and serious pollution.Therefore,it is urgent to carry out reasonable energy.efficiency assessment and propose appropriate energy conservation and emission reduction measurements.In this paper,a new dry process cement production system of 5000t/d is taken as an example.The energy efficiency,economy and comprehensive analysis of the cement production system are carried out by using exergy analysis and exergeconomic analysis method,so as to evaluate the energy performance of each subsystems of cement production.Based on the exergy and exergeconomic analysis,the optimization and improvement scheme of the waste heat boiler and the low temperature wind of the grate cooler are proposed.The main research contents and conclusions of this paper are as follows:(1)The material flow model and energy flow model of the cement production system are established.Based on this model,the exergy analysis is carried out,and the economic analysis is carried out in combination with economic analysis.The results indicate that the general exergy efficiency of the cement production system is 47.93%and the target exergy efficiency is 32.75%.The exergoeconomic analysis of the cement production system shows that all the exergoeconomic coefficients of the preheater&calciner,rotary kiln,grate cooler and waste heat power generation system are less than 0.3.The relative cost difference of the rotary kin and power generation system is larger.The exergy and exergoeconomic analysis of the cement production system shows that the waste heat power generation system could be optimized and the waste heat of low temperature gas from cooler should be recycled.(2)Based on the above analysis,this paper proposes three optimizations for the waste heat power station to improve the comprehensive efficiency of energy consumption and economy of the waste heat power generation system.a)The optimization and analysis of the waste heat power generation system with the total thermal conductivity as the objective function shows that,when the power generation is 10MW,the total thermal conductivity is at least 574kW/K;b)The optimization with the power generation as the objective function shows that,if the total thermal conductivity is 700kW/K,the power generation can reach 10.61 MW;c)The results of optimizing the waste heat power generation system with the profit rate and the exergoeconomic cost as the objective function show that,with the increase of power generation,the total thermal conduction and steam flow increase continuously,the investment and operating costs increase rapidly,and the profit rate increases first and then decreases.The optimization result of exergoeconomic cost shows that increasing the heating surfece of the boiler and increasing the non-energy input of the system can achieve the minimum exergoeconomic cost of 173.16 RMB/GJ.(3)To recover the waste heat of low temperature gas from sgrate cooler,this paper proposes three different waste heat recovery schemes:organic Rankine cycle,Kalina cycle recovery,cold and heat supply recovery.Then the exergy,economic and erxergoeconomic anahrsis are conducted on the three schemes.The results show that the combined cooling and heating has the highest profit rate and the lowest investment cost,but the total profit is relatively small.The heating system has the highest efficiency,and the absorption refrigeration system has the lowest efficiency,but the interhal thergy lost of the heating is the largest,and the external loss of the absorption refrigeration is the largest.For the organic Rankine cycle and the Kalina cycle,the exergoeconomic cost is much lower than that of the combined heat and cold,and the exergoeconomic factor is higher,which means these two schemes have better comprehensive effects of energy efficiency and econony.