| Steam power system (SPS) is an important part of the petrochemical enterprises, its security and stable operation are the basic of the process industrial long-period operation. Steam power system consumes a large amount of fuel and causes serious environment problem. Therefore, the optimization of the SPS operation and the reduction of operating costs, not only is an important way to improve efficiency for the process of industrial energy consumption, but also have important research significance to the sustainable development of human society.Steam power system in the petrochemical enterprises has its own complex operating characteristics. Understanding and analyzing deeply the characteristics is a premier to develop reasonable optimization programs for the operation of SPS. It is very important to establish a multi-level integration steam power system model of petrochemical enterprises for understanding deeply steam power system, guiding the activities of steam power system and achieving the overall optimization of energy systems of petrochemical enterprises. In this thesis, the multi-level modeling architecture is introduced, and the hierarchical model of steam power system, physical structure model and flow model are established. An integrated optimization mathematical model of steam power system including boiler, turbine, waste heat boilers and other major equipment, is established. Because of the shortcoming of traditional Particle swarm optimization with the slow convergence speed and weak convergence of global optimization, a new improved optimization algorithm-linear parameters of particle swarm optimization (ICPPSO algorithm) is developed. The algorithm predigests the constraint handling and transforms the constraint problem to unconstraint. Using the improved PSO algorithm to optimize the solution of the case in literature and practical case, the results show that the optimization speed of ICPPSO is higher than that of other optimization methods, and the optimized program can reduce operational costs largely. The results also show that the algorithm has good practicality and effectiveness.The variations of petrochemical enterprise's production capacity, market demand and seasonal alternation cause to different needs of steam and power in different periods and result in frequent start-up and shut-down issues of boiler and turbines. These operations not only increase the total operational cost, but also have very important impact on equipment life. Therefore, the model based on previous research on equipment start-up and shut-down cost is revised, In the thesis, when the start-up and shut-down time of boiler and gas turbine is considered, the models in the literatures are revised on the mathematic meaning. On the contrary, when the time is taken over, two revised programs are proposed. One program is to divide total time into three stages:equipment start-up time, equipment uptime and equipment shut-down time; the other revises the logic constraint of equipment start-up period early and delays shut-down period. Combined the steam power system of a petrochemical enterprise, a optimization mathematic model is developed and solved by adopting the ICPPSO algorithm with solving strategies by step, and two reasonable optimization programs are reached and the corresponding total operation cost decrease by 1.4% and 2.3% respectively. The results show that the revised model has not only mathematic meaning, and but also make the operation of SPS more near to ideal conditions and has good reference on the problem with the transit scheduling.China's energy situation is subject to dual constraints of economic growth and environmental protection. With the development of energy shortage and environmental pollution, the energy problem becomes more serious. An optimization model of petrochemical steam power system in different operation period including the environmental cost is proposed, In the model, the pollutant emission and the pollutant emission reduction factor are considered, and the constraint of pollutant emission is introduced and the penalty on air pollutants is enhanced. Combined the SPS of a petrochemical enterprise, the model is solved by adopting ICPPSO algorithm and a reasonable operation program is obtained. The optimization result demonstrates different unit configuration and fuel selection. Furthermore, the operation programs including power input, output, and steam purchased in different periods will be different even same fuel choices whether the environmental cost is considered. In the end, some reasonable advice is proposed to decrease total operational cost including environmental cost. |
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