MODERNIZATION OF THE NATURAL GAS LIQUEFACTION CYCLE AT GAS DISTRIBUTION STATIONS

The possibility of developing the liquefied natural gas (LNG) market in the Russian Federation can be realized by increasing the projects of low-tonnage LNG production. The development of LNG production projects at gas distribution stations should be a priority, since in this case it is possible to implement various production schemes: expander, throttle or cycle with a vortex pipe. To assess the efficiency of the use of low-tonnage LNG production at gas distribution stations (GDS), the dynamics of changes in maximum and minimum pressure values  in the main gas pipeline, as well as the distribution of GDS by seasonal change in pressure drop and throughput are presented. To assess the operability and applicability of the work, a design model of the natural gas liquefaction throttle cycle was built and numerical modeling of its operation was carried out at seasonal fluctuations in pressures and GDS costs, which showed a strong dependence on these fluctuations and a low degree of natural gas liquefaction. In order to further modernize the liquefaction cycles of natural gas, modeling was carried out according to the turbo expander cycle, which also showed a dependence on seasonality, but a higher degree of liquefaction of natural gas, which during modeling reached more than 8%. The final stage was the construction of a design model of the combined technology — throttling and turbo expander cycles, as well as numerical modeling, which showed the possibility of increasing the liquefaction of natural gas at GDS to 19%, but the impact of seasonal fluctuations also remains significant. Summing up, it can be said that the work has worked out options for the transition from the throttle cycle to the throttle-expander and turbo-expander, as a result of which it was concluded that the operation of each cycle is effective, due to which it is possible to expand the LNG production network at the GDS at various input pressures, flow rates and the required degree of liquefaction of natural gas.