Study On Improvement Of Process For Dehydration And Regeneration Gas System Of Molecular Sieve In Small And Medium - Sized LNG Plant

Liqufied natural gas (LNG) is considered as a kind of high quality clean energy sources in the21century for its characteristic of calorific value and pollution-free to the environment. The improvement of overall technology of the LNG industry chain and the ascending demand make LNG as the first-advocated choice for many chountries. Faced with imports of LNG, the coastal areas first to build the LNG terminal to the introduction of LNG, therefore we should make full use of domestic natural gas resources and some inland natural gas producing areas of quality and environmental conditions are suitable for the nearest to build LNG plant.There is a late start to the development and application of LNG technology, with the strong support of the national policy, domestic small and medium sized LNG plant to flourish, meanwhile, the one or two decades of techonology experience in the domestic LNG industry is difficult to keep up with the LNG technology in foreign countries, we should learn and absorb foreign mature technology, and innovations. Energy saving, reducing production costs are called for in the "Twelve-Five" energy development plans, molecular sieve dehydration is commonly used in the pretreatment department of LNG plants, the heat consumption in molecular sieve regeneration is large, but there is scarcity of relevant research in this field both at home and abroad, therefore, the researchment to the existing LNG plant process, achieving the waste heat recovery have important scientific significance and application value.In this paper, the theoretical investigation of the dehydration process in the LNG plant at home and abroad is researched and through the small and medium sized LNG plant regeneration gas system process improvement to solve the problem of large heat consumption when the molecular sieve regeneration process, the SRK state equation is used as the caculation basis in HYSYS steady state simulation of the regeneration gas system. The waste heat recovery is achieved with regeneration gas heat exchanger in the regeneration process for the first time, and the regeneration gas heat exchanger technological design is complicated in this paper, etc.In this paper, use this molecular sieve dehydration regeneration gas system process improvement to a30×104Nm3/d LNG plant in the Xin jiang region as a calculation example. The molecular sieve dehydration regeneration gas system process is simulated with HYSYS software, the alternation of heat consumption and other factors before and after the regeneration gas system process change is compared and analysed. Kern method and HTRI software are intergrated to design and calculate the regeneration gas heat exchanger and other equipments, and the actual operation after process improvement of this LNG plant is analysed. The results turn out that the improved equipments run well, effectively reduced the heat consumption of the molecule sieve regeneration process, and achieve the waste heat recovery of the regeneration gas system. Research results of this paper have adoped in the molecule sieve dehydration process program design of a30×104Nm3/d LNG plant in the Xin jiang region, indicating that the contents of this paper has a strong engineering practice significance.