NATURAL GAS PROCESSING METHOD Russian patent published in 2001 - IPC

FIELD: natural gas processing. SUBSTANCE: natural gas processing into pure ethane, methane fraction, and long fraction of light hydrocarbons involves multistage low-temperature condensation of cooled gas by way of separation thereof and dividing resulting gas stream, throttling, refrigeration in turbo-expander, and rectification to yield methane and ethane fractions. According to invention, crude gas is divided into two streams at volume ratio 13: 37, the first stream is cooled by methane fraction and the second one is conveyed into heat exchangers of lower column of demethanizer, after which combined cooled gas stream is transferred to separation unit and separated gas once again is divided into two streams at volume ratio 1:4 The first stream is cooled by methane fraction and the second one in turbo-expander, after which both are subjected to common multistage rectification in demethanizer consisting of upper and lower columns, temperature gradient between middle and lower sections of lower column being maintained constant and not exceeding 25 C. EFFECT: increased purity of ethane fraction. 1 dwg