Study On Multilevel Synthesis Strategy Of Heat Exchanger Network

Synthesis and optimization of process energy system is an important method of decreasing energy consumption nowadays. It is important for saving energy source, protecting environment and establishing national economic system with low devotion and high output, less energy consumption and less let off, circular and continuable. Improving the efficiency of energy using and the conflict between demand and supply will ensure social economic and national economic safe.Based on the nowaday condition of the energy using efficiency and the theory and technology about process energy system synthesis and optimization, optimum energy system combined with factual problem was proposed. It is aimed at offering advice for grassroots and retrofit design of process industry.Combined the first and the second law of thermodynamics and exergy consumption expense substituted utilities cost as operating cost, the objective function based on exergoeconomics was proposed, which determined the optimum minimum approach temperature of HENs. Cold and hot utilities were integrated with process streams into T-H plot, forming balanced composite curves, basing on pinch technology. Exergy consumption of heat transfer in HENs was calculated using subsection integral on balanced composite curves.The effect of fouling on temperature disturbance propagation to a controlled variable in heat exchanger network was researched. It was studied that the qualitative and quantitative effect of fouling on temperature propagating in the whole heat exchanger network and the measures of eliminating negative effect were proposed. Based on the method of temperature propagating, the temperature propagating tables were put forward, which contain the information for improving the network and can be become the effective tool to evaluate and analyze the temperature propagating in the heat exchanger network.It is to integrate optimal design of single heat exchanger in network with heat transfer enhancement and pressure drop constrain distribution of the stream in design heat exchanger network. The compared results between the synthesis energy system and the virtual system indicate the validity of the method.The model of optimum cleaning circle of heat exchanger was proposed based on considering several ingredient such as operating fee, cleaning time, cleaning fee and lost fee of off line. The optimum cleaning circle of heat exchangers in the network was calculated and the result will be meaningful for considering the opportunity of heat exchanger cleaning.Based on the temperature propagating analysis, the quantitative effect of decision parameter on position parameter and the objective function was obtained. In order to test the validity of this method, the testing facilities were designed, which can be used to test the heat transfer of single heat exchanger and heat exchanger network. The obtained results indicate that the method of temperature propagating is validity.