Abstract:

LNG production is a very energy intensive process and any effort to reduce energy costs is of great interest. LNG production with a circulating nitrogen cycle is seen as the most suitable option for small-scale LNG production. In circulating nitrogen cycle LNG systems, the maximum gas liquefaction ratio can be up to 100%. These systems require relatively low capital investments, as it is possible to use a small refrigeration machine and an appropriate system for gas pre-treatment. The technological scheme of the systems under consideration is characterized by relative simplicity, reliability, quick commissioning, compactness and minimal safety requirements. The main disadvantage of the technology is high energy consumption. In the article energy analysis of technologies with nitrogen cycle and ways to reduce their energy costs are carried out. Different modifications of such technologies are considered. The use of refrigeration machine with different working substances and their influence on the overall efficiency of the technology is also considered. The results of the analysis show that when the pre-cooling cycle is included in the scheme, the energy efficiency of the technology increases significantly. When including a refrigeration machine with the working substanceR410, the specific energy consumption of the process decreases by 22.7%, and when using propane as a refrigerant in the refrigeration machine - by 20%. The analysis also considers.

Keywords: liquefied natural gas, detander gas expansion, liquefaction process, pre-cooling, energy analysis, nitrogen circulation cycle, refrigeration machine, working substance.