ENERGY EFFICIENT NATURAL GAS LIQUEFACTION TECHNOLOGIES IN LOW-TONNAGE PLANTS: UKRAINE’S PROSPECTS

Abstract

Along with the growth of natural gas consumption in the world, small-scale production of liquefied natural gas (LNG) is developing at a faster pace. It opens up the possibility of LNG obtaining and transporting as a commodity product at remote from gas networks fields or wells, and also at low-production wells and alternative sources of methane-containing gas. The development of modern technologies for natural gas liquefaction has been studied and the liquefaction cycles used in the low-tonnage scale have been classified. In Ukraine, rather large reserves of natural gas are found in small as well as depleted fields, so the problem of energy efficient technologies for liquefaction and transportation of their hydrocarbon resources creating is of particular relevance. For the development of such low-resource fields, liquefaction units operating on the compression-throttle cycle are most suitable. Energy efficient technological schemes of natural gas liquefaction plants have been developed: in the high-pressure throttle-ejector cycle with pre-cooling using a propane refrigerating machine and in the middle-pressure throttle cycle with ethane refrigeration cycle and the recovery of part of the liquefied gas. Optimum parameters of the refrigeration cycle and the whole plant are obtained from the point of view of minimizing the specific energy costs. The advantages of the proposed throttle schemes are simplicity, reliability, that are results from the use of standard compressor and refrigeration equipment, and energy efficiency of 0.5 kWh/kg LNG, which is sufficiently high for low-tonnage LNG production. Ref. 20, Fig. 6, Tab.1.