The Integration And Optimization Of Heat Exchanger Networks And Key Technology Research Of Equipment's Characteristic Parameter

The energy resources can ensure the persistent and healthy development for the country's economy. The average energy resources of our country are few, however, the wastage is rather larger, and the using efficiency is lower than the developed country. It's time for our government to take some measures to deal with this severe state, which has blocked the development of our country's economy. In allusion to the process industry, such as oil refining, chemical industry, fertilize industry, metallurgy, electric power, light industry, etc, which always consume much energy. It is necessary to use reasonable method to reduce the energy consumption and improve the efficiency of utilizing energy, so as to reduce the product cost and make it been selling well. As one of high consuming energy industry, the heat exchanger networks can bring an active influence if there are some effective methods can be adopted.Aim at the above mentioned issue, the technology of process synthesis and integration has developed well and become the main method to decrease the consumption of energy in past thirty years. The method has been applied in some fields, such as reactor networks, separating process, heat exchanger networks, utility system, and the whole process.The field the article researched is heat exchanger networks. In order to get the best structure of the networks, which need to use the process synthesis and integration to analysis and optimize the whole networks on the basis of meeting the process demand and the fewest equipments and operation cost.Since the heat exchanger network has been put forward, many scholars have researched fully and summarized several methods to solve this problem. These methods have been applied to engineering and had notability economy profit. The research fields of heat exchanger network conclude the synthesize of heat exchanger network, the flexibility and maneuverability design of heat exchanger network, the structure optimization of heat exchanger network, etc. While the method that has been adopted can be summed up as follows: the pinch technology, the mathematics programming method, the thermodynamics analyzing method,the genetic algorithms and the artificial intelligence technology. In this article, there is an overview of development about these methods. Among these methods, the pinch technology is developed relatively mature; which is based on the thermodynamics. Using this method, the relationship of energy and temperature can be found and the 'bottleneck' can be removed. This method is brought forward by Linnhoff in 1978, and he pointed out the temperature pinch point and the most heat recovery. Among 1982 and 1983, Linnhoff discussed the pinch technology of heat exchanger network and extended this method to the whole process system. In 1993, he gave the full comment about the pinch technology. In this article, a particular discuss about pinch technology has been given in the way of diagram and problem table. The diagram method is intuitionist and it can exhibit the matching relationship of the cool and heat streams. When used the utility, it should consider the quality of energy and make the difference of temperature matching reasonably. The method of diagram may be not exacter than the problem table. So the detailed calculation process has been given in the way of solving an example.In the process of heat exchanger network design, the author consults many data and finds most researches ignored the influence of pressure drop in design heat exchanger network. And the aim of design is the matching of streams; it does not consider the heat exchanger design. In the article, the author makes a deeper research about pressure drop and provides some opinions and optimizes the whole heat networks finally. In the whole design process of heat exchanger network, some designers now consider the pressure drop in the aim of the least expense. But the factors are very various and the limited condition is complex. Many methods are applied by the mathematics programming and the equation is always the mixture integer nonlinear equation. The genetic algorithms are adopted to solve this kind of equation. But the equation is very complex and in order to deal with it some hypothesis have adopted and this is may lead to part constringency. There is no united format has been formed about how to solve this equation and the process is going on. The author is going to use the suppleness and practicality method of pinch technology to deal with the design of heat exchanger networks. On the base of getting the primaryoptimization, then consider the pressure drop and design all the heat exchangers and get the whole optimization.Surrounding this subject, such work has been done:First, it is using the pinch technology to analysis the curve of heat stream, cold stream and the whole combination stream to distinguish the state of energy.Second, it is to analyze the relationship of the heat recovery approach temperature and the process-process duty, the total utility duty, and their areas to realize the energy change trend.Finally, the process of co-conversion and methanation of synthesis ammonia industry has been simulated with considering the pressure drop, and designed every exchanger of the networks.