Natural gas liquefaction (LNG)

For covering peak gas consumption loads, gas transportation, provision of gas supply to remote, rural and resort areas and for using gas as engine fuel, LENNIIHIMMASH Group designs both large-capacity plants for production of liquefied natural gas with capacity of 10-40 t/hour with a high (more than 90%) gas liquefaction ratio, and low-capacity plants with capacity up to 1 t/h.

The liquefaction process comprises a single-flow cooling cycle using mixture of hydrocarbons and nitrogen. Such plant includes the following units:

• gas preparation (deep dehydration, and purification and filtration in case of a high content of harmful impurities)
• coolant compression
• pre-cooling
• condensation and re-cooling
• storage of liquefied natural gas
• rectification (for production of coolant components)

For low-capacity gas liquefying plants, the following liquefaction methods are possible:

• use of one-flow cooling cycle in processing of low source gas flow rates (liquefaction ratio is 0,95)
• use of expander cycle:
       а) closed-circuit cycle with a liquefaction ratio of 0,7 – 0,8;
       б) open-circuit cycle with a liquefaction ratio of 0,08 – 0,12.

The latter is recommended to be used at gas distribution stations, where a reducing unit is replaced by a natural gas liquefaction plant providing gas expansion in an expansion unit and partial liquefaction. This method practically does not require any energy consumption. The plant output depends on the flow rate of gas arriving at gas distribution stations and on pressure difference range at station inlet/outlet.

The plant includes the following units:

• gas preparation
• cooling and separation
• expansion (with one or two expansion stages)
• storage of liquefied natural gas

For production of engine fuel, a wide range of plant capacities is available in terms of both processed gas and produced liquefied gas, depending on the gas source and requirements (i.e., sales opportunities).