The Research For Distillation Energy Conservation And Optimization

Distillation is a complex and important chemical unit operation; it consumes about 40% of all energy in chemical industry and it is widely used in oil refining, petrochemical, natural gas, fine chemical industries, etc. The distillation processes consume huge resources such as coal, water, electricity and gas etc. Therefore, the research about energy conservation and optimization for distillation is rather important.Since energy saving and the protection of the environment have been the theme of the era for the world, any research about optimization and energy saving bears great significance. Nowadays what confronts every researcher is that how to take full consideration for all elements concerning the energy cost of distillation and how to find the perfect matching for optimal operation conditions and parameters of the process to minimize the energy cost. However, there are only a few references on energy conservation and optimization for distillation to be found and most of them are only introductions of concepts with no tangible research processes and valuable results. This paper in a systematic way pointed out four main technologies to save energy for distillation and their related case studies. The four main technologies are about the feed state, the feed tray location, inter-heat exchanger and heat pump. This paper based the research on the simulation and calculation carried out by chemical software PRO /â…¡, and comes to the following results:The optimization of feed state is one of the critical measures for the energy conservation for distillation and it is much to be regreted that the attention has not been paid to this measure in the academic and industry fields. The people are used to adopting the bubble point as the favourite feed state. This"habit"would cause rapid increase in energy consumption under some circumstances. This paper analyzed and discussed how to adopt suitable feed state under different situations, and pointed out the right and necessary approach.The concept of the feed location optimization is known by most people, but there are not many people who understand the methods and criteria of how to optimize the feed location. The paper introduced the different feed tray optimization methods, which are hand calculation method, the separation factor method, the optimizer method and the sensitivity method. And the sensitivity method was pointed out to be the most reliable and accurate one. Inter-heat exchanger is another way of energy conservation for distillation. It is not very clear to many people that what the energy saving principle is, the application criteria, how to locate the exchanger and determine the flow rate to be drawn out of the column plate and how the impact on the parameters of the column will be. This paper answered these questions with case studies.Heat pump is a very important and widely used way of energy saving for distillation. However, the related references and material about heat pump are less, and those on the key process parameters of the heat pumps and their determination principles are extremely scarce. This paper discussed thoroughly three kinds of mostly used heat pumps in industry-closed, vapor recompression and bottoms flashing heat pumps. The paper presented the methods to determine the key process parameters of these heat pumps and made comparisons for their differences and energy consumptions case by case. And it is pointed out that vapor recompression heat pump consumes the fewest energy among the three kinds heat pumps.