Study On HENS Considering Detailed Equipment's Pressure Drop Effects

Energy security is becoming the focus of attention, we should insist on conservation and development simultaneously, giving priority to conservation. Increasing the energy efficiency of the system as quickly as possible, the energy efficiency of key energy-consuming industries can meet international advanced level, with the smallest possible consumption of energy resources, supporting the economic and social development as large as possible. Industrial, transportation and construction are the priority areas, while the heat exchanger network is an important part of the process industry. Reducing energy consumption in heat exchanger network is significant to raise process industry's energy efficiency.This paper, aimed at the low industrial energy efficiency, integrated the study of the heat exchanger networks theory and method, proposed an improved genetic algorithm for simultaneous optimization of heat exchanger networks for solving MINLP model and raised a new method about heat exchanger network synthesis considering detailed heat exchanger's pressure drop effects.After full study of genetic algorithm and particle swarm optimization, author found the prematurity and slow convergence of the genetic algorithm, and the low diversity of the population of the particle swarm algorithm, combined the genetic algorithm and particle swarm algorithm. Take advantage of genetic algorithm's select, crossover steps to maintain the diversity of population, and complete the process of population's mutation by using the particle swarm algorithm's speed formula, to achieve the feasible space of the search process. Examples show that the improved genetic algorithm's feasibility in heat exchanger networks synthesis.Taking into account the traditional heat exchanger networks, the single device on the heat exchanger caused by the neglect of the results and the actual discrepancies, this paper proposed of the new method about heat exchanger network synthesis considering the detailed equipment's pressure drop effects. First, assume a constant film heat transfer coefficient, design a preliminary heat exchanger network, and then design every heat exchanger including calculating the pumping cost, the film heat transfer coefficients of internal and external tubes, in accordance with its proportion of heat load to get the new film heat transfer coefficient of the streams; after that, re-design the heat exchanger network structure with the new film heat transfer coefficient, compare with the total cost and the structure of the network,finally receive optimal network structure, and the basic parameters of each heat exchanger. This method can fully utilizes the engineers'experience, designs the better network to meet the engineering requirements for heat exchanger network synthesis, and it's significant to the transformation of the old network.