Research On Multi-Resolution Modeling Technique Of CDU&VDU

The modern process industry is increasingly large, optimization integrated and management and control integrated, which require the simulation of process industry to consider mathematical models of different granularities and scales in a same frame. There is much difference of space and time in different level of process industry, which makes the research of multi-resolution more important. Based on the research of complex feature in petrochemical process, the paper studied the application of multi-resolution modeling technique in Crude Distillate Unit & Vacuum Distillate Unit (CDU&VDU). First, both no-component model and component model of CDU&VDU were modeled. And then aggregation and disaggregation of multi-resolution models were studied. At last, the paper studied the consistency of multi-resolution models on different levels and gave out the metric formula of consistency between multi-resolution models and calculated them.Main research works and achievements are summarized as following:On the background of 500×104t/aCDU&VDU of a petrochemical company, the dynamic models of every subsystem were established by mechanism analysis. Crude oil was cutting into several pseudo components according to the true boiling points data of products. Via chemic process calculate, we got saturation vapor tension and vapor-liquid equilibrium constant of pseudo components. And the vapor-liquid enthalpy formula was obtained by the least squares method. Then we got the no-component dynamic mathematics model based on functions of material balance and heat balance and the component model based on MESH by combining empirical formula.In this Paper,the characteristics of the large-scale complex systems and their hierarchical embodying relationships were discussed at first. Then,the advantages of Multi-Resolution Modeling(MRM) over the traditional modeling methods are reviewed in detail. Thereupon,some important concepts such as variable granularity analysis, aggregation and disaggregation,smooth and consistency transformation between multi-resolution models were studied.Thereupon, the characteristics of CDU&VDU were discussed and the method of choosing macro-variables was proposed. And the aggregation method for systems of differential equation is proposed. The paper applied the method to aggregate component models as a no-component model. Then aggregation model is analyzed and its steady state point was obtained.The aggregation method reduces the dimension and complexity of model, but the aggregation model is not the copy of the component model, so it makes new properties emerge at the macro-level. The paper studied the consistency of multi-resolution models on different levels and gave out the metric formula of consistency between multi-resolution models and calculated them.