Method and apparatus for treating aqueous medium

• US 6,572,759 B1
• Filed: 08/09/2001
• Issued: 06/03/2003
• Est. Priority Date: 02/10/1999
• Status: Expired due to Fees

• Current Assignee: Ebara Corporation
• Original Assignee: Ebara Corporation
• Inventors: Usui, Takashi, Su, Oingquan, Nishimura, Tatsuya, Isaka, Masahiro, Serikawa, Roberto Masahiro
• Primary Examiner(s): Phasge, Arun S.
• Application Number:
  US09/913,028
• Time in Patent Office: 663 Days
• Field of Search: 205/687, 205/688, 205/701, 205/742, 204/242, 204/275.1
• US Class Current: 205/687
• CPC Class Codes: B01D 53/32 by electrical effects other than those provided for in group B01D61/00
• CPC Class Codes: B01D 53/77 Liquid phase processes
• CPC Class Codes: B01J 10/00 Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor B01J19/08 takes precedence; separation, e.g. distillation, also combined with chemical reactions B01D, e.g. B01D3/009
• CPC Class Codes: B01J 19/18 Stationary reactors having moving elements inside B01J19/08, B01J19/26 take precedence
• CPC Class Codes: B01J 19/26 Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles
• CPC Class Codes: B01J 2219/00054 Controlling or regulating the heat exchange system
• CPC Class Codes: B01J 2219/00058 Temperature measurement
• CPC Class Codes: B01J 2219/00063 of the reactants
• CPC Class Codes: B01J 2219/00069 Flow rate measurement
• CPC Class Codes: B01J 2219/00087 with heat exchange elements outside the reactor
• CPC Class Codes: B01J 2219/00099 the reactor being immersed in the heat exchange medium
• CPC Class Codes: B01J 2219/00103 in a heat exchanger separate from the reactor
• CPC Class Codes: B01J 2219/00132 using electric heating or cooling elements
• CPC Class Codes: B01J 2219/00135 Electric resistance heaters
• CPC Class Codes: B01J 2219/00155 using insulating materials or refractories
• CPC Class Codes: B01J 2219/00157 by means of a burner
• CPC Class Codes: B01J 2219/00159 controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
• CPC Class Codes: B01J 2219/00162 controlling the pressure
• CPC Class Codes: B01J 2219/00164 controlling the flow
• CPC Class Codes: B01J 2219/00182 controlling the level of reactants in the reactor vessel
• CPC Class Codes: B01J 2219/083 : cylindrical
• CPC Class Codes: B01J 2219/0884 : Gas-liquid
• CPC Class Codes: B01J 2219/185 : vertical
• CPC Class Codes: B01J 2219/30207 : Sphere
• CPC Class Codes: B01J 2219/30223 : Cylinder
• CPC Class Codes: B01J 3/04 : Pressure vessels, e.g. autoclaves
• CPC Class Codes: C02F 1/02 : by heating methods of steam generation F22B; preheating boiler feed-water or accumulating preheated boiler feed-water F22D
• CPC Class Codes: C02F 1/025 : Thermal hydrolysis
• CPC Class Codes: C02F 1/461 : by electrolysis
• CPC Class Codes: C02F 1/46104 : Devices therefor; Their operating or servicing
• CPC Class Codes: C02F 1/46114 : Electrodes in particulate form or with conductive and/or non conductive particles between them
• CPC Class Codes: C02F 1/467 : by electrochemical disinfection; by electrooxydation or by electroreduction
• CPC Class Codes: C02F 1/4672 : by electrooxydation
• CPC Class Codes: C02F 1/74 : with air aeration of stretches of water C02F7/00
• CPC Class Codes: C02F 2001/46133 : characterised by the material
• CPC Class Codes: C02F 2101/36 : containing halogen
• CPC Class Codes: C02F 2103/18 : from the purification of gaseous effluents
• CPC Class Codes: C02F 2103/28 : from the paper or cellulose industry
• CPC Class Codes: C02F 2201/4612 : Controlling or monitoring
• CPC Class Codes: C02F 2201/46155 : Heating or cooling
• CPC Class Codes: C02F 2301/066 : Overpressure, high pressure
• CPC Class Codes: C02F 2301/08 : Multistage treatments, e.g. repetition of the same process step under different conditions

Abstract

An object of the present invention is to provide a process and an apparatus for treating an aqueous medium at low running costs with a decreased electricity required for hydrothermal electrolytic reaction. The present invention proposes a two-step process comprising a first step of performing a conventional hydrothermal reaction or a conventional electrolytic reaction prior to hydrothermal electrolytic reaction to degrade readily degradable substances or ammonia or various electrolytically degradable organics and then a second step of performing hydrothermal electrolytic reaction to degrade the remaining organics, whereby the electricity consumed by hydrothermal electrolytic reaction in the second step can be greatly reduced.

Claims

1. A process for treating an aqueous medium comprising:

a first step of subjecting an aqueous medium containing water, reducing substances and a halide ion to electrolytic reaction under the conditions of a temperature of 100°

C. or less and atmospheric pressure, and then

a second step of performing hydrothermal electrolysis by supplying a direct current to said aqueous medium at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase.

2. The process of claim 1 comprising adding an oxidizer to the aqueous medium after the first step of electrolytic reaction and before the second step of hydrothermal electrolysis.

3. The process of claim 2 wherein air is added as said oxidizer.

4. The process of claim 1 comprising subjecting the aqueous medium to a hydrothermal oxidation reaction by maintaining the aqueous medium in the presence of an oxidizer at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase, after the first step of electrolytic reaction and before the second step of hydrothermal electrolysis, and then subjecting said aqueous medium to hydrothermal electrolysis.

5. The process of claim 4 comprising adding an oxidizer to the aqueous medium after the first step of electrolytic reaction but before the hydrothermal oxidation reaction and after the hydrothermal oxidation reaction but before the hydrothermal electrolysis step.

6. The process of claim 1 wherein said aqueous medium contains a strong acid ion in addition to a halide ion.

7. The process of claim 1 comprising adding conductive particles to the aqueous medium.

8. The process of claim 1 for treating lignin or a derivative thereof.

9. An apparatus for treating an aqueous medium comprising:

an electrolytic reactor having a vessel for receiving an aqueous medium and at least a pair of electrodes for performing electrolysis in said vessel, and

a hydrothermal electrolytic reactor having a reactor having an inlet for introducing the aqueous medium treated by said electrolytic reactor and an outlet for discharging effluent and capable of resisting the pressure of hydrothermal reaction, and at least a pair of electrodes for performing electrolysis in said reactor.

10. The apparatus of claim 9 further comprising a heater for heating the reactor of the hydrothermal electrolytic reactor.

11. The apparatus of claim 9 wherein the reactor of the hydrothermal electrolytic reactor further comprises a means for introducing an oxidizer into the reactor.

12. The apparatus of claim 11 wherein said means for introducing an oxidizer is a nozzle for mixing an aqueous medium and an oxidizer.

13. The apparatus of claim 9 further comprising a means for heating the aqueous medium before introducing the aqueous medium into the reactor of the hydrothermal electrolytic reactor.

14. The apparatus of claim 9 wherein the hydrothermal electrolytic reactor comprises a hydrothermal oxidation reaction part for maintaining the aqueous medium at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase, and a hydrothermal electrolysis part for supplying a direct current to the aqueous medium treated in said hydrothermal oxidation reaction part at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase.

15. The apparatus of claim 14 wherein said hydrothermal oxidation reaction part and said hydrothermal electrolysis part are provided in one reactor.

16. The apparatus of claim 14 wherein said hydrothermal oxidation reaction part and said hydrothermal electrolysis part are provided in separate reactors.

17. The apparatus of claim 9 wherein the reactor of the hydrothermal electrolytic reactor has a multitube structure consisting of a plurality of containers and an electrode is provided in each container.

18. The apparatus of claim 9 wherein the reactor of the hydrothermal electrolytic reactor has a pair of electrodes comprising:

a first electrode having two or more concentrically cylindrical first side walls and a first connecting member for connecting said first side walls together, and

a second electrode having two or more concentrically cylindrical second side walls and a second connecting member for connecting said second side walls together,

wherein said first side walls of said first electrode and said second side walls of said second electrode are alternately arranged to form a channel for influent between said first side walls and said second side walls.

19. The apparatus of claim 9 further comprising a conductive particle feed line for adding conductive particles to the aqueous medium.

20. The process of claim 19 comprising the step of adding conductive particles into the aqueous medium.

21. The apparatus of claim 20 further comprising a conductive particle feed line for adding conductive particles to the aqueous medium.

22. The apparatus of claim 9 comprising a feed line for introducing lignin or a derivative thereof into the aqueous medium.

23. A process for treating an aqueous medium comprising:

a hydrothermal reaction step of maintaining an aqueous medium containing water and reducing substances at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase, and then

a hydrothermal electrolytic step of supplying a direct current to said aqueous medium at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase.

24. The process of claim 23 wherein the aqueous medium further contains an oxidizer in the hydrothermal reaction step.

25. The process of claim 23 wherein said aqueous medium further contains a strong acid ion in said hydrothermal electrolysis step.

26. The process of claim 23 for treating lignin or a derivative thereof.

27. An apparatus for treating an aqueous medium comprising:

a hydrothermal reaction part for maintaining an aqueous medium containing water and reducing substances at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase, and

a hydrothermal electrolytic reaction part for supplying a direct current to the aqueous medium treated in said hydrothermal reaction part at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase.

28. The apparatus of claim 27 wherein said hydrothermal reaction part and said hydrothermal electrolysis part are provided in one reactor.

29. The apparatus of claim 27 wherein said hydrothermal reaction part and said hydrothermal electrolysis part are provided in separate reactors.

30. The apparatus of claim 29 wherein the reactor of the hydrothermal electrolysis part has a pair of electrodes comprising:

a first electrode having two or more concentrically cylindrical first side walls and a first connecting member for connecting said first side walls together, and

a second electrode having two or more concentrically cylindrical second side walls and a second connecting member for connecting said second side walls together,

wherein said first side walls of said first electrode and said second side walls of said second electrode are alternately arranged to form a channel for influent between said first side walls and said second side walls.

31. The apparatus of claim 27 wherein the reactor has a multitube structure consisting of a plurality of containers.

32. The apparatus of claim 27 comprising a feed line for introducing lignin or a derivative thereof into the aqueous medium.

33. A process for treating an aqueous medium comprising:

a first step of subjecting an aqueous medium containing water, reducing substances and a strong acid ion to electrolytic reaction under the conditions of a temperature of 100°

C. or less and atmospheric pressure, and then

a second step of performing hydrothermal electrolysis by supplying a direct current to said aqueous medium at a temperature of 100°

C. or more but not more than the critical temperature of said aqueous medium and at a pressure that allows said aqueous medium to be kept in the liquid phase.