The Research On Fault Diagnosis Of Air Separation Multi-Stream Heat Exchanger

In the field of low temperature technology,multi-stream heat exchanger is the key heat transfer equipment to recover cold quantity.As the main energy device of the air separation system,the accurate calculation of its heat transfer performance and the reasonable diagnosis of the fault condition seriously affect the energy consumption and economy of the low temperature distillation air separation device.The traditional extensive evaluation standard gradually fades out of the historical stage,seeking a more efficient and accurate evaluation standard of heat transfer performance of multi-stream heat exchanger and introducing it into the fault diagnosis strategy has become the current development trend of green economy.In this paper,the fault diagnosis strategy of multi-stream heat exchanger is based on the parameter value of fault condition,after accurate reasoning,decoupling the corresponding fault type,in the concrete realization scheme,it fuses the evaluation standard of heat transfer performance,and realizes the accurate and timely control of the fault condition.On the basis of summing up and analyzing the existing research,this paper has carried out the following research:(1)A more targeted evaluation standard for heat transfer performance of multi-stream heat exchanger is proposed by analyzing and summarizing the performance evaluation method of traditional extensive heat exchanger.Firstly,the thermal efficiency of the two streams of cold and heat is obtained by analyzing the heat transfer process of two-flow plate-fin heat exchanger.And then,combined with the definition of heat transfer and the conservation of thermodynamic energy,the relationship between the heat transfer efficiency of multi-stream heat exchanger and two-flow heat exchanger is obtained.According to the relation formula,the most practical multi-stream heat exchanger efficiency can be obtained in the engineering production process,and could be used as an important analysis index of fault diagnosis.(2)the influence of the key indexes of multi-stream heat exchanger on heat transfer performance under normal working conditions is analyzed by establishing the process simulation platform.And the optimum parameter range of thermal end temperature difference and path pressure drop is summarized.Then the phenomenon of blockage and leakage fault of multi-stream heat exchanger is simulated,the deviation of the key indexes under abnormal working condition and normal working condition is analyzed,and the fault characteristics of heat exchanger are summarized.(3)A complete knowledge base is obtained through the collection and accumulation of fault knowledge of multi-stream heat exchanger.And a fault diagnosis system of multi-stream heat exchanger based on expert system is established by combining accurate and efficient inference engine.At the same time,with the help of web-related technology,the expert system is integrated to network system,to achieve the function of query,display,analysis,alarm,and serve the actual industrial production.