Technologies

Liquefied natural gas (LNG) production

Obtaining LNG is the key part in infrastructure of production,
storage, distribution and con-sumption of liquefied natural gas

It is reasonable to put the plants for obtaining LNG in the gas-distributing stations (GDS). This allows using gas pressure in pipe line to carry out technological cycle and excluding capital expenditure on compressions and energy for their drive. At carrying out such a scheme only part of the productional gas flew is liquefied (10-15%), the rest part goes to the consumer at decreased pressure.

At the whole flow liquation (100%) to compensate the deficiency of refrigerating capacity the additional cooling cycle is used. Choosing of cooling cycle depends on realized scheme, pro-ductivity, costs of LNG production and technological equipment. The table shows the conditional cycle classification which depends on showed parameters.

Productivity, t/h

Cycle characterization

Specific energy      consumption, kW/kg

Preferable placement

30 – 100 and more

Cooling cycle of mixtures

0,3 – 0,5

Terminals, GPP*

10 – 50

With a compressor, turbo-expander and propane cooling

0,6 – 0,9

Terminals, GPP*

3 – 10

With a compressor, and         turbo-expander

0,3 – 0,5

GPP*, GDS**

1 – 3

With turbo-expander

-

GDS**

GPP* - gas processing plants

GRS** - gas-distributing stations

Circuit design for LNG production

A key parameter of designing plants for LNG production is not only productivity but also gas composition, because the requirements of its purification are very strict and connected with the fact that under cryogenic temperature (boiling temperature of CH4 is 161.5°C bellow zero) admix-tures precipitate and block reinforcement.

In general the plant for LNG production include:

  • the block of purification from water vapor and carbon;
  • the block of liquation (with a throttle, with a turbo-expander or other equipment);
  • the automatic control system;
  • auxiliary equipment (for heating, blowing with gas during preventive and remedial maintenance);
  • cryogenic capacitive equipment for accumulation and storage of LNG;
  • compressor equipment in case of 100% natural gas liquation or additional cooling cy-cle support.

Realization of the project on creating the natural gas liquefier OPG-3 on the basis of Co Ltd «Gazprom transgaz Yekaterinburg»

According to the order of one of the subsidiary company of PSC “Gazprom”, NPO “Geliy-mash” created the natural gas liquefier assembled on the basis of ГРС «Gazprom transgaz Yekater-inburg». The liquefier is designed with using turbo-expander cycle and partial natural gas liquation with productivity of 3000 kg/h.

Liquefied natural gas (LNG) production.jpg


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