FIELD: gas industry.
SUBSTANCE: invention can be used at gas industry enterprises in the preparation of natural gas for cryogenic extraction of methane, ethane and a wide fraction of light hydrocarbons. The method for purifying natural gas from impurities includes the stage of absorption extraction of carbon dioxide and methanol from the natural gas feed with an aqueous solution of an amine in an absorber, followed by regeneration of a saturated absorbent in an amine regeneration column and obtaining a regenerated absorbent, acidic water and acid gas, then the stage of adsorption drying of purified natural gas with subsequent regeneration of the adsorbent with a portion of the purified and dried natural gas. The regeneration of waste gas is combined with the purified natural gas and, after cooling, is separated from the condensed water, which is returned to the tank for the preparation of the aqueous amine solution. Acidic water from the reflux tank of the amine regeneration column is separated in a stripping distillation column into methanol and stripped water. In this case, the flow of acidic water from the reflux tank of the amine regeneration column is divided into two parts: the first part is sent to the stripping distillation column for separation, and the second part is sent to the amine regeneration column as reflux. The optimal ratio between the first part and the entire flow of acidic water from the reflux tank of the amine regeneration column in the range from 100 to 0% is determined from the condition of the minimum total heat supply to the bottom of the amine regeneration column and the stripping distillation column and / or the total heat removal from the flows of the upper part of the column regeneration of amine and stripping distillation column per 1 ton of extracted methanol.
EFFECT: this invention is an energy-saving method for preparing raw natural gas for further cryogenic processing by using the energy potential and the composition of intermediate technological streams.
5 cl, 2 dwg, 5 tbl
