Research On Waste Heat Recovery Technology Of Low Temperature Flue Gas In Drying Kiln Of Ceramic Factory

Energy consumption is becoming increasingly serious with the development of industry.From the perspective of energy structure,energy consumption is still dominated by fossil fuels represented by coal.China’s current energy utilization structure is not yet complete,on the one hand,the energy efficiency of the production process itself is not high enough,on the other hand,a large amount of surplus resources are directly discharged without utilization.The low temperature waste heat in China’s industrial waste heat accounts for more than half of the total,and the potential for recycling is huge.For a long time,in the low-temperature waste heat recovery process,there have been problems of difficult recovery and low recovery efficiency due to the nature of the low-temperature waste heat itself.Taking the waste heat utilization principle as the starting point.Firstly,it analyzes and summarizes the three levels of utilization of flue gas waste heat,then the Organic Rankine cycle(ORC)system was finally selected for low temperature flue gas waste heat recovery by comparing different waste heat recovery methods.Then,the exhaust gas heat recovery heat exchanger was selected by comprehensively considering the performance of different heat exchangers in terms of volume and side pressure drop of the flue gas.Then established thermodynamic model and evaluation model of ORC system.The cold and heat source parameters and simulation conditions of the simulation experiment are designed by analyzing the residual heat parameters of the drying kiln flue gas and R245 fa are selected as the circulating working medium to conduct research by combining the characteristics of the working medium and the principle of working medium selection.Finally,multi-parameter optimization of the ORC system under different external cold and heat source parameters is performed with the minimum power generation cost as the objective function,and finding the best internal operating parameters and their changes.Based on the analysis of the change law,the main influencing factors of the system’s optimal operating parameters and minimum power generation costs are summarized,and the aspects that the ORC system should focus on in engineering practice are pointed out.The result reveals: 1)among the enamel plate heat exchangers,fluoroplastic tube heat exchangers and TD steel tube heat exchangers designed in the article,the volume and flue gas side pressure drop of the enamel plate heat exchanger under design conditions 47% and 43% of fluoroplastic tube type,41% and 59% of TD steel tube type,and enamel plate heat exchanger is more suitable as flue gas waste heat recovery heat exchanger than the other two;2)The optimal evaporation temperature of the ORC system is mainly affected by the temperature of the heat source inlet.When the temperature of the heat source inlet increases from 120 °C to 180 °C,the optimal evaporation temperature increases by 46%.The optimal condensation temperature is most affected by the inlet temperature of the cold source.When the inlet temperature of the cold source is increased from 15 °C to 35 °C,the optimal condensation temperature is increased by 44%;3)The influence of the heat source inlet temperature on the minimum power generation cost is the largest in the given four cold and heat source parameters.The minimum power generation cost rangeability is 0.072 $/kWh within the given heat source import parameter range.Therefore,the temperature of the heat source should be considered first in the engineering practice application of the organic Rankine cycle,and the heat source inlet temperature should be set according to the annual average temperature of the flue gas waste heat in the actual project to ensure that the cycle can run under the design conditions.