NATURAL GAS LIQUEFACTION METHOD Russian patent published in 2016 - IPC F25J1/02 

FIELD: heating.

SUBSTANCE: present invention relates to cryogenic equipment, namely to equipment and process of natural gas liquefaction, and first of all to low and medium capacity units. HP natural gas is supplied to the input of a dehydration system 1, where it is cleaned and dehydrated. Downstream the dehydration unit it is supplied to a heat exchanger 2, where it is cooled and liquefied by heat exchanging with the LP cold nitrogen flow, and then is throttled via a valve 3 to the pressure, when its accumulation and storage in a cryogenic tank 4 are ensured. In the main cooling circuit nitrogen is used as the coolant, it circulates in the closed loop organized based on a circulating compressor 5. To the expander stage of a turbine expander-compressor plant 7 not the full flow of the HP cooled nitrogen is supplied. Some part of the said flow is sequentially subjected to additional cooling in the heat exchanger 2 and throttling in a valve 10 to obtain the liquid phase of nitrogen that is delivered to a heat exchanger-evaporator 11, where overcooling of the LNG flow is performed due to heat exchanging with boiling liquid nitrogen. The nitrogen vapours generated during boiling from the heat exchanger-evaporator 11 are mixed with the LP nitrogen flow from the output of the expander stage of the turbine expander-compressor plant 7, and further the combined flow enters the heat exchanger 2, and further back to the suction line of the circulating compressor 5.

EFFECT: increased efficiency of the method.

3 cl, 3 dwg, 2 tbl