METHOD FOR PURIFYING WATER-METHANOL SOLUTIONS TO REMOVE SALTS Russian patent published in 2023 - IPC B01D61/00 C07C29/76 C07C31/04 C02F1/44 

FIELD: natural gas treatment.

SUBSTANCE: method for purifying water-methanol solutions from salts, and can be used to ensure optimal management of a complex of technological processes for the regeneration of methanol from a water-methanol solution at oil and gas production enterprises. The proposed method includes the stages of introducing a reagent into the water-methanol solution, holding the resulting solution, removing the formed colloidal particles in the filtration membrane blocks, cleaning the membrane elements as they become contaminated. The water-methanol solution is mixed with trisodium phosphate in an amount of 86.3 grams per 1 litre of water-methanol solution, after which the resulting colloidal particles are removed at the first stage of filtration in a filtration membrane unit at a pressure of 2 to 6 atmospheres. The linear speed of movement of the filtered medium is not less than 1.5 m/sec, and temperature is not less than 35°C. Then bottoms water is added from the column of the direct-fired methanol regeneration unit, the secondary process of softening of the water-methanol solution is carried out at the second stage of filtration (diafiltration) in the filtration membrane block at a pressure of 2 to 6 atmospheres, the linear speed of movement of the filtered medium is at least 1.5 m/sec, and the temperature not less than 35°C. The reagent is reintroduced into the resulting permeate in an amount of 1.53 grams per liter of the water-methanol solution, the resulting colloidal particles are removed in the filtration membrane block of the third filtration stage at a pressure of 2 to 6 atmospheres, the linear speed of movement of the filtered medium not less than 1.5 m/sec, and the temperature not less than 35°C, and a softened water-methanol solution and salt slurry are obtained.

EFFECT: improved quality of methanol regeneration from a water-methanol solution, in particular preventing increased salt formation in water-methanol solutions having a high initial concentration of hardness salts and a high salt background of sodium compounds, reducing the volume of repair and restoration work and reducing the level of negative impact on the environment.

1 cl, 1 dwg