Research Of Optimization Of Heat Exchanger Network And Evaluation Of Heat Exchangers Efficiency In Propylene Oxide Process System Of Chlor-alkali Plant

With the continuous expansion of the industrial production scale of our country,the amount of energy use increased year by year,the way to alleviate the tense situation of energy supply is directly related to the problem of the sustainable development of social economy in our country,and scientific and effective energy saving is an important aspect to solve the problem of energy supply.So the paper takes the high energy consumption of propylene oxide as the object to explore the optimization and transformation of the heat exchanger network system,and the energy efficiency evaluation of the heat exchanger.The operating parameters of heat exchanger equipments in one chlor alkali plant epoxy propane unit system for thermal equipment were tested to extract the basic data of cold and hot streams temperature,pressure and flow which were needed in pinch analysis technology.Using Aspen Plus software to simulating the operation of thermal equipment of each heat exchanger,analyzing and calculating the parameters of the numerical situation,and compared with the extraction flow data.The results show that the relative average error between simulated and measured values is 2.42%,which verifies the accuracy and reliability of the data,and the method can be improved by using simulated data and measured data.Using pinch analysis technology to optimized the chlorohydrin production of propylene oxide process system for thermal network which can point out the bottleneck of the thermal network system utilization and determined the pinch point temperature and energy saving potential of overall system and each subsystem for thermal network.Set a minimum experience value of pinch temperature difference and calculated the target value of energy consumption of the utility and energy saving achieved,gave the optimization measures,and cleared the optimization of heat exchanger network system neutron method to compare the overall system method has better energy saving effect and pointed out that the optimization method is the best basis for selection.By introducing the influence coefficient of the heat exchange network,a new model and method for evaluating the energy efficiency of the heat exchanger which can consider the influence of heat exchange network was established.The application of the method in the epoxy propane unit for heat exchanger efficiency evaluation showed that the new established method can significantly improve the change small heat exchanger score value and efficiency levels,reduce the large change scores of the heat exchanger,which can overcome the limitations of heat exchanger efficiency evaluation by single change and reflect the running situation of the heat exchangers more fully and whether need to optimize the conditions.The evaluation result was more practical significance,and would have strong operability.In order to make up for the disadvantages of the evaluation method based on the first law of thermodynamics,the mathematical model of the energy efficiency evaluation of heat exchangers was established according to the second law of thermodynamics.We improved the mathematical model of entropy production using ?-NTU method to derive the mathematical models of heat transfer and flow resistance entropy production under different conditions and analyzed the influence of the basic parameters on the energy efficiency evaluation of the heat exchangers and finally made the energy efficiency evaluation entropy model more widely applied.