Process and apparatus for purifying waste waters

• US 4,236,974 A
• Filed: 02/22/1979
• Issued: 12/02/1980
• Est. Priority Date: 06/18/1976
• Status: Expired due to Term

• Current Assignee: HCH Bertrams AG
• Original Assignee: HCH Bertrams AG
• Inventors: Kuhnlein, Hans
• Primary Examiner(s): Hart, Charles N.
• Assistant Examiner(s): Hruskoci, Peter A.
• Application Number:
  US06/014,167
• Time in Patent Office: 649 Days
• Field of Search: 159/47 WL, 159/DIG. 8, 202/153, 202/174, 202/182, 203/10, 203/11, 203/25, 203/31, 203/39, 210/63 R, 210/67, 210/71, 210/73 R, 210/73 SG, 210/150, 210/152, 210/180-182, 210/188, 423/224, 431/11, 431/163, 431/210
• US Class Current: 203/11
• CPC Class Codes: C02F 1/048 Purification of waste water by evaporation
• CPC Class Codes: C02F 11/06 by oxidation incinerators for burning waste liquors, e.g. sulfite liquor from paper-making plant F23G7/04
• CPC Class Codes: F23G 7/008 for liquid waste waste oil F23G7/05, waste liquors F23G7/04, sludges F23G7/001
• CPC Class Codes: Y02W 10/40 Valorisation of by-products of wastewater, sewage or sludge processing

Abstract

A process and apparatus for purifying waste water which comprises introducing said waste water into a separation zone, removing a portion of the impurities recovered from said separation zone, and concentrating said impurities by their introduction into an evaporation system to form a still fluid residue and remaining impurities composed of impurities in gaseous and vapor form together with waste vapors, transferring said remaining impurities to an oxidation chamber, and supplying said oxidation chamber with heat and air, thereby oxidizing said remaining impurities through spontaneous combustion, wherein the proportion of the low boiling-point impurities in the waste water introduced into the separation zone is adjusted to a predetermined value.

Claims

1. An apparatus for purifying waste water contaminated with high- and low-boiling point organic impurities which comprises a stripping system for separating said waste water into waste vapor and waste water such that the waste water contains about 2 percent of low-boiling point impurities in the form of combustible hydrocarbons and high-boiling point impurities, a combustion chamber into which said waste vapor is introduced and combusted into clean fumes, a forced-circulation evaporation system comprising first, second and third stages for further concentrating said waste water into a fluid concentrate of high boiling point impurities and a waste vapor containing low boiling point impurities in gaseous form together with steam, a waste-vapor outlet from the first stage being connected with said combustion chamber, first and second oxidation chambers into which waste vapors from said second and third stages are introduced and oxidized into purified waste vapor respectively, means for introducing pressurized air into the oxidation chambers, means for introducing waste vapor from said second and third stages into first and second heat exchangers respectively, means for introducing the purified waste said first and second oxidation chambers into said first and second heat exchangers respectively, to raise the temperature of the waste vapor to the starting oxidation temperature in the respective oxidation chambers, means for introducing the waste water to be purified into the stripping system, means for conveying the waste-water impurities from the stripping system to the three-stage evaporation system, and means means for introducing said purified waste vapor from said first and second heat exchangers into said first and second stages respectively, to condense said purified waste vapors into purified waste water, and means for removing said purified waste water from said first and second stages.

2. The apparatus of claim 1, wherein each oxidation chamber is provided with a cylindrical vessel comprising a pressure-resistant outer jacket and an inside insulation, said vessel comprising at one end a mixing chamber equipped with inlets for oxidizing air and crude waste vapors, a reaction chamber containing packing and separated from the mixing chamber by a perforated plate being located above said mixing chamber, said reaction chamber, in turn, being connected through a deflecting chamber with an outlet for clean waste vapors.

4. The apparatus of claim 1, wherein the stripping system is a stripping column and means are provided for conveying waste vapor from the stripping column to a combustion system which is supplied with an auxiliary fuel system.

3. A process for heat purifying waste water contaminated with high- and low-boiling point organic impurities which comprises introducing said waste water into a stripping column so as to separate said waste water into waste vapor containing low-boiling point impurities and waste water containing about 2 percent of low-boiling point impurities in the form of combustible hydrocarbons and high-boiling point impurities, said waste vapor containing said low-boiling point impurities being supplied to a combustion chamber operating at a temperature in the range of from 900°

to 1200°

C. producing substantially clean combustion gases, said waste water being introduced into a forced-circulation evaporation system comprising first, second and third evaporation stages so as to further concentrate said waste water such that it leaves said evaporation stages as a concentrate of high-boiling point impurities in a fluid condition and waste vapors containing said low boiling point impurities in gaseous form together with steam, wherein the waste vapors from the first stage are fed directly to a combustion chamber where combustion takes place at 900°

to 1200°

C., thereby completely oxidizing all of the organic impurities therein, the waste vapors from the second and third stages being heated to about 600°

C. while simultaneously introducing pressurized air at 600°

C. and the waste vapor from said second and third stages into first and second oxidation chambers, respectively, where temperatures of about 800°

C. are obtained by means of spontaneous combustion to thereby bring about complete combustion or oxidation of the organic, low-boiling point impurities present, said heat for heating the waste vapors from the second and third stages being derived from heat exchange with the purified hot waste vapors of the respective oxidation chambers, introducing the resulting steam-gas flow free of organic materials comprising purified waste vapors together with resulting combustion gases from said first and second oxidation chambers into said first and second stages respectively, to produce a condensate of pure water while a portion of the steam remains uncondensed, the overall process being such that the concentrate leaving the third evaporation stage contains concentrated high-boiling point impurities, the entire evaporation and oxidation process taking place under pressure of about 3-20 atmospheres, gauge, said stripping column being operated with the uncondensed remainder of the steam and the oxidizing gas from the evaporation system.