IIR document

Conceptual design of an efficient small LNG production facility.

Number: pap. n. 031

Author(s) : QUACK H.

Summary

For environmental reasons more and more cars, trucks and buses are using compressed natural gas (CNG) as fuel. This trend could be enlarged, if there were more CNG gas stations. Presently such stations can only be built near the distribution grid of natural gas. To build a station away from the grid, it would be necessary to transport the natural gas there in form of liquefied natural gas (LNG). Sometimes it is economical to transport the LNG from far away locations, but it would be beneficial, if gas companies could produce LNG within their own grid. An optimum location for such a small LNG production facility would be a place in the grid, where high pressure gas from the pipeline with a pressure higher than 40 bar is throttled to a medium pressure distribution grid with a pressure below 6 bar. Here one can efficiently liquefy a small part stream. The main stream is used to supply precooling due to the Joule-Thomson effect. It can act as heat sink for the heat given off by the liquefaction process and it also can absorb those components of the natural gas, which are separated upstream or during the liquefaction process like H2O, CO2, higher hydrocarbons and N2. The liquefaction process is a Joule-Thomson process supported by precooling of a cascade with e.g. CO2 and ethylene as refrigerants. To improve the quality of the CNG for the use in internal combustion engines it is advisable to reduce the content in ethane below about 3%. For this purpose one can include a small rectification column in the process, which can work at a pressure level between 10 and 40 bar. The concept is usable for plant sizes between 5 and 50 T/d. The power consumption is in the order of 0.2 to 0.22 kWh/kg, which is lower than the specific power needed in large bulk LNG facilities.

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Pages: 215-220

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Details

  • Original title: Conceptual design of an efficient small LNG production facility.
  • Record ID : 30006630
  • Languages: English
  • Source: Cryogenics 2012. Proceedings of the 12th IIR International Conference: Dresden, Germany, September 11-14, 2012.
  • Publication date: 2012/09/11

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