FIELD: chemistry.
SUBSTANCE: method for purifying natural gas from carbon dioxide and hydrogen sulfide involves two consecutive absorption steps for processing natural gas having a ratio of hydrogen sulfide to carbon dioxide of 1.0 but not more than 1.5 and a concentration of hydrogen sulphide of 3.5 to 8.0 vol. %: at the first step, selective purification of the starting natural gas is performed with respect to carbon dioxide to a carbon dioxide content of, at least, 60% of the original in the feed natural gas and a hydrogen sulphide content of not more than 5-7 mg/m3, in the second step, the partially purified natural gas after the first absorption step is purified to a carbon dioxide content of not more than 50-200 mg/m3 in the complete absence of hydrogen sulphide. The saturation of the alkylamine absorbent in each absorption step by the acidic components is higher than 0.4 mol/mol, the partially purified natural gas after the first absorption step is divided into two streams: the first is purified in the second absorption step, and the second is combined with the first stream purified in the second absorption step and withdrawn as a marketable gas at a cost ratio determined by the equation G2/G1 = K*(C"ДОП" - C1)/(C2 - C"ДОП"). The installation includes two consecutive absorption gas purification units consisting of an absorber, a regenerator, pumps, a refrigerator, a recuperative heat exchanger, a reboiler, a tank and piping of the apparatus of the absorption gas purification units.
EFFECT: invention makes it possible to effectively purify natural gas from carbon dioxide and hydrogen sulphide.
21 cl, 1 dwg
