CS209084B1 - A way of regenerating contaminated organic solvents - Google Patents

Abstract

From the cleaning processes in the mechanical engineering, textile, chemical and municipal industries, organic solvents contaminated with oils and other organic and inorganic impurities are discarded. When these solvents are cleaned by distillation or rectification, concentrated impurities containing organic solvents result as a residual product. Their disposal causes serious hygiene problems. This deficiency is eliminated according to the invention by subjecting contaminated organic solvents with limited miscibility with water to heteroazeotropic distillation or rectification with steam. The vapors of the heteroazeotropic pure solvent and water are condensed and the pure solvent is subsequently separated from the water. The regeneration residue free from organic solvent is divided into an oil phase and residual water. The residual water is purified from emulsified impurities and oil on a suitable adsorbent. The oil phase is disposed of by incineration using the combustion heat to produce steam, which is reused in the heteroazeotropic distillation of the contaminated solvent.

Description

The invention relates to a process for the regeneration of contaminated organic solvents of limited miscibility with water and the disposal of regeneration wastes so as to comply with the principles of environmental protection.

Organic solvents for cleaning purposes are used in industrial plants of the mechanical engineering, textile and chemical industries as well as in municipalities. Organic solvents contaminated with oils and other organic and inorganic contaminants are removed from the cleaning processes. Distillation or rectification is carried out to restore the purity of the solvents. With this purification procedure, only part of the solvent can be recovered - complete purification encounters problems associated with foaming of the solution at high concentration of impurities and increasing the boiling point of the solution. Because of these problems, the regeneration process is usually carried out to the point where a portion of the original organic solvent remains in the distillation residue. The imperfect separation of the organic solvent from the residue causes problems with the disposal of the residue in addition to the losses of the solvent itself. This is particularly pronounced for chlorinated organic solvents, where the presence of a chlorinated solvent in the residue makes it impossible to dispose of it by incineration to form highly toxic phosgene. Contaminated organic solvents, resp. their concentrated residues are either stored, very often contaminated into the waste water, causing serious hygiene problems.

These drawbacks are overcome by the method of regeneration according to the invention, which consists in that the regeneration of waste solvents - limitedly miscible with water, respectively. their concentrated residues are carried out by heteroazeotropic distillation or rectification with water vapor. The contaminated organic solvent is thus separated into a pure solvent and a solvent-free oil layer useful for scaffolding or collecting worn oils. The regeneration process results in residual water contaminated with soluble or emulsified oils and other impurities from which the impurities are removed by trapping on a suitable adsorbent. The spent adsorbent from the residual water purification is disposed of by incineration.

In addition to the advantage of providing such a procedure for the recovery of contaminated organic solvents and the disposal of waste from the recovery process,

Claims (1)

OBJECT OF THE INVENTION A method of regenerating contaminated organic solvents with limited water miscibility, characterized in that the action of water vapor on a contaminated solvent is carried out by heteroazeotropic distillation or rectification of solvent, steam of a heteroazeotrope of pure solvent and water that complies with environmental regulations. recovering the entire amount of organic solvent in a quality that allows it to be reused in cleaning processes. An example is 1459 g of a dark brown trichlorethylene dirty solution containing 3.3 wt. oily impurities were subjected to heteroazeotropic distillation with saturated water vapor at 100 ° C. 75 ° C heteroazeotrope vapors were condensed and the trichlorethylene condensate separated from water. 1414 g of a clear, colorless condensate of pure trichlorethylene and 131 g of water were obtained. Of the distillation residue, after separation of 45 g of the oil layer without trichlorethylene traces, 323 g of residual water remained, the purity of which was expressed as a chemical oxygen demand of 1200 mg O2 / liter. To the 100 g of this residual water was added 15 g of expanded perlite and, after thorough mixing and filtration, a chemical oxygen demand of 350 mg O2 / liter was determined in the filtrate. To a further 100 g of residual water, 5 g of activated carbon was added and after mixing and filtering, a chemical oxygen demand of 80 mg O2 / liter was determined in the filtrate. Example 2 970 g of impure perchlorethylene black oily consistency solution containing 77.5 wt. the oily impurities were subjected to heteroazeotropic rectification with saturated water vapor at 100 ° C. 93 ° C heteroazeotrope vapors were condensed and the perchlorethylene condensate separated from water. The separated water returned to the regeneration system in the form of reflux. 218 g of a clear, colorless condensate of pure perchlorethylene were obtained. From the distillation residue, after separation of 732 g of the oil layer without the presence of traces of perchlorethylene, 912 g of residual water remained, the purity of which was expressed as a chemical oxygen demand of 3300 mg O2 / liter. To the 100 g of this residual water was added 15 g of expanded perlite, and after mixing and filtering, the chemical oxygen demand was 2200 mg O2 / liter in the filtrate. To another 100 g of residual water, 5 g of activated carbon was added and after mixing and filtering, a chemical oxygen demand of 170 mg O2 / liter was determined in the filtrate. BACKGROUND OF THE INVENTION The scenting and condensate of the pure solvent is water-abated, the organic solvent-free regeneration residue is separated into the oil phase and the residual water and the residual water is purified by adsorption, preferably on the recovered activated carbon.