Optimization Of Hot Water System In Refinery

Low temperature heat recovery in refinery is an important part of energy saving and consumption reduction,and the construction of hot water system is the most important way to recover low temperature heat.Due to the lack of systematic thinking to guide the design of hot water system,it is not possible to understand energy from the two aspects of "quality" and "quantity",resulting in insufficient recovery of low temperature heat,unreasonable energy utilization,serious energy derogatory,the benefits of low temperature heat recovery is not significant,can not achieve the expected energy-saving effect.Therefore,it is very important to study how to recover low temperature heat more scientifically and how to use it more rationally in response to national policies to reduce carbon emissions.Based on the theory of chemical process system,this paper puts forward the design method of hot water system.The main research content is as follows:(1)Using process system theory,we are instructed to collect data on low temperature heat in refineries.First of all,through the energy analysis of each plant,the grand composite curve of each plant is drawn,and the heat source or trap is divided according to the pinch temperature.Then,according to the grand composite curve,the energy distribution of the plant is analyzed and the low temperature heat data are collected.Finally,according to the collected data,a T-H diagram is drawn,the hot composite curve represents the heat source,the cold composite curve represents the heat trap,and the match between the two curves is achieved by adjusting the load of the heat source and the heat trap.(2)The optimization design method of the hot water system.The traditional heat source or heat trap device in the hot water system is heated side by side,which causes the problems of large flow of hot water circulation,low temperature rise and difficult to adjust the system.In this paper,the method of optimizing the side-by-side hot water system is put forward,according to the temperature of the streams,the internal heat exchange mode of the device is changed to the streams and hot water for the rung heat exchange,which reduces the flow of hot water circulation in the system and increases the temperature rise of hot water.The structureoptimized hot water system enhances the low temperature heat recovery effect.(3)By constructing the super-structure of the hot water system,the mathematical model is established,and the optimized hot water system structure is solved by genetic algorithm.When the temperature distribution of low temperature heat varies greatly between plants,the connection structure of the plant may have the potential of optimization,because the proposed optimization method is not considered,so the super-structure model is used to improve the design method of the hot water system.(4)Calculation of the actual example.Through the example,the optimization effect of the hot water system design method proposed in this paper is shown,and the two optimization design methods are compared.