Optimization Design Of Batch Heat Exchanger Networks Based On Petri Net

The continuing global competition for raw materials and energy together with the pressure on environmental sustainability now provides a strong impetus for chemical industries to consi-der heat integration as a means to minimize energy consumption. As demands for most produc-ts are highly seasonal and low in volume, nowadays, about half of industrial chemical products are manufactured using batch processes. The increasing popularity of batch plants and the cont-inuing global emphasis on emissions reduction is starting to warrant either the adaptation of the well-established heat integration techniques to or the development of novel techniques for batc-h processes.Heat integration techniques adapted to batch processes is advantageous to save investment and reduce environmental pollution, what's more, productivity pinch that constrained by the ra-te of heat flow can be distinguished through the techniques. Successful application of heat inte-gration to these batch processes that incur substantial energy consumptions would therefore co-ntribute significantly to their sustainability standing. The present methods for batch heat integr-ation exists certainly shortages and inadequacy, more or less. Because of the virtue in system modeling and analysis, the paper presents a Petri net based approach, combined with pinch tec-hnology and scheduling optimization, to design batch heat exchanger networks.(1) Batch pinch technology is derived from continuous process, and continuous process can be classified as a special batch process. So, firstly, base on the characteristics of dynamic and concurrent and the ability to express logic, Petri net for the minimum temperature optima-zation, pinch analysis and synthesis and loop search and path identity are builded, respectively. One illustrative example is presented to demonstrate the validity and advantages of the propos-ed.(2) According to the time-dependent heat cascade analysis technique, time places that rep-resent time for batch process were imported to optimized batch heat exchange network (HEN) in the Self-organizing Petri Net Modules for The optimal design of batch heat exchanger netw-orks. The introduction of time places developed the representation of time in Petri net, and it profitably studied reachability of system. Besides, streams split in HEN based on pinch techno-logy were studied and the formulas considered comprehensively all the principles of pinch tec- hnology were established to split steams accurately and quickly in pinch point. One illustrative example is presented to demonstrate the validity and advantages of the proposed approach.(3) The increase in popularity is due to the flexibility and adaptability of batch plants, whi-ch is crucial and preferred in the current volatile market trends. So, scheduling and heat integr-ation of batch processes should be considered together. Because there are many shortages, such as asyntactic expression time factors and violable concurrent and conflict and unreachable anal-ysis, in the present Petri net based modeling approach for the scheduling of batch plants, the pa-per treat time factors as a set of elements and modify Original model by using inhibitor arcs an-d self-adaptive weight. In this way, system reachability and time performance can be acquired easily. Then, base on the function of multiple view integrated modeling, Petri nets for schedul-ing and heat integration are composited together. The composited model can synchronously op-timize a problem for incorporating scheduling in batch process heat integration. Two simple illustrative examples are presented to demonstrate the validity and advantages of the proposed approach.