METHOD OF LIQUEFYING NATURAL GAS Russian patent published in 2010 - IPC F25J1/00 

FIELD: chemistry.

SUBSTANCE: at the first step of the method, a first fraction of incoming gas is taken, compressed to temperature higher than or equal to 1500 pounds/kilo inch, cooled and expanded to lower pressure in order to cool said first fraction. The remaining fraction of the initial stream is cooled via indirect heat exchange with the expanded first fraction in a first heat exchange process. At the second step, the separated stream containing flash evaporation vapour is compressed, cooled and expanded to lower pressure, thus providing another cold stream. This cold stream is used to cool the remaining stream of incoming gas in a second indirect heat exchange process. The expanded stream coming out of the second heat exchange process is used for further cooling at the first step of indirect heat exchange. The rest of the incoming gas is then expanded to lower pressure, thereby partially liquefying that stream of incoming gas. The liquefied fraction of this stream is taken from the process in form of liquefied natural gas, whose temperature corresponds to boiling point pressure temperature.

EFFECT: high efficiency.

22 cl, 11 dwg, 1 tbl