Patent RU-2245849-C1 (RU)
Title: Method of treatment of sulfurous-alkaline sewage and the installation for its realization
Inventor: SHUKAJLO BORIS NIKOLAEVICH
IPC: C02F1/58
Filed: 2003-08-20
Granted: 2005-02-10
Abstract: FIELD: petrochemical and petroleum refining industry; methods and installations of industrial sewage treatment. 
     SUBSTANCE: the invention presents a method of treatment of sulfurous-alkaline sewage and the installation for its realization and is dealt with the field of industrial sewage treatment, in particular, with reprocessing of the sulfurous-alkaline sewage of oil-refining enterprise using alkali purification of petroleum into target products. The method of processing of sulfurous-alkaline sewage includes neutralization of the sewage with the help of an acid with evolution and predistillation by a noble gas of the volatile sulfur-containing and other compounds. At that the neutralization is conducted by sulfuric acid or its water solution in two stages at the temperature of no more than 70°С. The post-neutralization sewage is exposed to extraction by an organic solvent with separation of a water layer containing salt cake and an organic layer bed containing petroleum acids. The water layer containing salt cake is neutralized by alkali and then dry with production of crystalline salt cake, and the organic layer containing petroleum acids is subjected to reextraction by alkali with separation of a water layer containing naphthenates of sodium and organic solvent, which is returned to the stage of extraction. The water layer containing naphthenates of sodium is recirculated to the stage of reextraction with withdrawal of naphthenates of sodium from the cycle of recirculation. At implementation of the method it is preferable to exercise at рН equal to 4.5-5.5, the second stage - at рН of no more than 2.5, in the capacity of the noble gas to use nitrogen and in the capacity of the organic solvent to use kerosene. Naphthenates of sodium are removed from a cycle of recirculation at reaching concentration of free alkali in them, equal to no more than 0.5 mass %. Extracted in the process of neutralization the light volatile sulfur-containing and other compounds are directed to catalytic purification from sulfides. The installation for processing sulfurous -alkaline sewage includes two in series linked to each other reactors and one extractor, two collectors and three pumps. Additionally it includes one neutralizer, one dryer and one reextractor. At that the inlet of the neutralizer is fused to the outlet of a still of the extractor, the outlet of the latter through a pump is connected to the dryer, the inlet of the reextractor is fused to the outlet of the upper part the extractor, the outlet from the upper part of the reextractor through the collector and the pump is fused to the second inlet of the extractor, the outlet from the lower part of reextractor through the second collector and the pump is fused to the upper part of the reextractor with a capability of withdrawal of the final solution. The method and the installation ensures a closed-circuit processing of sulfurous -alkaline sewage with production of target usable products - crystalline salt cake and liquid sodium naphthenates, exclusion of disposal of sewage contaminated by toxiferous sulfides that simplifies operation of biological sewage treatment plants. 
     EFFECT: the invention ensures a closed-circuit processing of sulfurous -alkaline sewage with production of target usable products - crystalline salt cake and liquid sodium naphthenates, exclusion of disposal of sewage contaminated by toxiferous sulfides that simplifies operation of biological sewage treatment plants. 
     5 cl, 1 dwg, 1 ex