METHOD OF PURIFYING SULPHUR ALKALI WASTE WATER Russian patent published in 2019 - IPC B01D1/00 B01D19/00 B01D3/00 C02F1/20 C02F9/00 C02F103/18 C02F101/10 

FIELD: oil and gas industry.

SUBSTANCE: invention can be used in oil refining and petrochemical industries. Sulphurous alkali waste waters (SAWW) are fed into stripping column 3 operating in rectification mode for evaporation of ammonia, part of hydrogen sulphide and water, which are discharged successively into refrigerator 7 and separator 8. Stripped SAWW from the cube of stripping column 3 after cooling is directed to saturator 12, operating at pressure up to 6.0 atm. overp., where also gaseous CO₂ is supplied with ratio of CO₂ : SAWW equal to 0÷15 nm³ : 1 m³. Carbonated SAWW is fed into desorption column 13 operating in rectification column mode at pressure 0.2÷1.0 atm. overp. To bottom part of desorption column 13 Co₂ is supplied with ratio of CO₂ : SAWW equal to 5÷20 nm³ : 1 m³. In desorption column 13 there is recycling of vat with mixing unit circulating SAWW with CO₂ in mixing device 30. Gaseous products from desorption column 13 are directed successively into cooler 16, separator 17, and then directed to production of elemental sulfur. Part of bottom product of desorption column 13 is directed through recuperative heat exchanger to blowing/stripping column 19. Gaseous products of stripping/stripping column 19 are discharged in series into refrigerator 25 and separator 26. Formed condensate is returned to the upper plate of stripping/stripping 19 as circulating reflux.

EFFECT: disclosed invention enables deep cleaning of SAWW by stripping and complex carbonisation with gaseous CO₂ to residual content of ammonium nitrogen of not more than 10 mg/dm³, sulphides to a value of not more than 10 mg/dm³ and pH 6,9–9, with initial content of ammonium nitrogen to 10,000 mg/dm³, sulphides to 20,000 mg/dm³ and pH not more than 13,5.

1 cl, 1 dwg, 1 tbl