Method of cleaning passageways using a mixed phase flow of gas and a liquid

• US 6,454,871 B1
• Filed: 12/17/1999
• Issued: 09/24/2002
• Est. Priority Date: 06/23/1997
• Status: Expired due to Term

• Current Assignee: Olympus Corporation
• Original Assignee: Princeton Trade & Technology, Inc.
• Inventors: Mahon, Geoffrey Lawrence, Materna, Peter A., Lai, Ching-Yue, Labib, Mohamed Emam
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): CHAUDHRY, SAEED T
• Application Number:
  US09/466,714
• Time in Patent Office: 1,012 Days
• Field of Search: 134/22.1, 134/22.12, 134/22.14, 134/34, 134/37, 134/8, 422/28
• US Class Current: 134/8
• CPC Class Codes: A61C 1/0076 Sterilising operating fluids or fluid supply elements such as supply lines, filters sterilisation of liquid substances in general A61L2/18
• CPC Class Codes: A61L 2/186 Peroxide solutions
• CPC Class Codes: A61L 2/22 Phase substances, e.g. smokes, aerosols or sprayed or atomised substances
• CPC Class Codes: A61L 2202/24 Medical instruments, e.g. endoscopes, catheters, sharps
• CPC Class Codes: A61M 1/1682 both machine and membrane module, i.e. also the module blood side
• CPC Class Codes: A61M 1/169 using chemical substances
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/2066 Pulsated flow
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 65/022 Membrane sterilisation
• CPC Class Codes: B08B 2209/022 making use of the reversal flow of the cleaning liquid
• CPC Class Codes: B08B 9/032 by the mechanical action of a moving fluid, e.g. by flushing B08B9/04 takes precedence ; by fluid jets mounted on cleaning devices B08B9/0433
• CPC Class Codes: B08B 9/0326 Using pulsations
• CPC Class Codes: B08B 9/0327 the fluid being in the form of a mist
• CPC Class Codes: C11D 2111/20 Industrial or commercial equipment, e.g. reactors, tubes or engines
• CPC Class Codes: C11D 3/042 Acids
• CPC Class Codes: C11D 3/044 Hydroxides or bases
• CPC Class Codes: C11D 3/14 Fillers; Abrasives ; Abrasive compositions; Suspending or absorbing agents not provided for in one single group of C11D3/12; Specific features concerning abrasives, e.g. granulometry or mixtures dyes, pigments C11D3/40
• CPC Class Codes: C11D 3/3947 Liquid compositions
• CPC Class Codes: C11D 3/3956 Liquid compositions
• CPC Class Codes: C11D 3/48 : Medical, disinfecting agents, disinfecting, antibacterial, germicidal or antimicrobial compositions
• CPC Class Codes: C23G 5/00 : Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents

Abstract

A method of cleaning surfaces using a mixed phase cleaning mixture of an aqueous solution and a flow of gas sufficient to produce droplets of the liquid which are entrained by the gas for a time sufficient to clean tubing of various lengths and geometries and porous membranes to remove biofilm, debris and contaminants.

Claims

1. A method of removing biofilm, debris and contaminants from surfaces of a passageway comprising forming a mixed phase flow of liquid droplets dispersed in a gas along a surface of the passageway from a mixture of gas and a liquid that creates shear or impact stresses and wherein the droplets are pulled from the surface of the liquid by hydrodynamic instability, for a time sufficient to remove biofilm, debris and contaminants from the surfaces.

2. A method according to claim 1 wherein the liquid has a surface tension of at least 18 dynes/cm.

3. A method according to claim 1 wherein the velocity of the gas is greater than 1 meter/second.

4. A method according to claim 3 wherein the velocity of the gas is from about 10 meters to 100 meters/second.

5. A method according to claim 1 wherein the passageway includes one or more changes of direction.

6. A method according to claim 1 wherein the passageway divides into multiple passageways.

7. A method according to claim 1 wherein the passageway is either the shell side or tube side of a shell and tube geometry.

8. A method according to claim 1 wherein the passageway is a biopsy device.

9. A method according to claim 1 wherein at least a portion of the surface of the passageway is a permeable membrane.

10. A method according to claim 9 wherein the portion of liquid introduced into the passageway through a permeable membrane reacts with the liquid flowing within the passageway to form additional bubbles that clean the pores and surface.

11. A method according to claim 9 wherein the exterior of the passageway is subjected to a pressurized gas.

12. A method according to claim 9 wherein the liquid includes a dissolved gas.

13. A method according to claim 9 wherein the exterior of the passageway is subject to a pressurized liquid.

14. A method according to claim 1 wherein the passageway comprises a hemodialyzer.

15. A method of claim 14 wherein the mixed-phase flow is formed by adding the liquid into the permeable surface of the passageway wherein the gas is flowing.

16. A method according to claim 1 wherein the direction of flow of the mixed-phase flow is reversed one or more times.

17. A method according to claim 1 wherein the mixed phase flow is pulsed.

18. A method according to claim 1 wherein the ratio of the volumetric flow rate of the gas at standard conditions to the volumetric flow rate of the liquid is between about 50:

1 to about 6000;

1.

19. A method according to claim 18 wherein the rinse is pulsed to remove residual surfactants, biofilm, debris and contaminants.

20. A method according to claim 1 wherein after removal of the biofilm, debris and contaminants, the passageway is rinsed.

21. A method according to claim 1 wherein the mixed-phase flow comprises a plurality of interconnected liquid films or light foam.

22. A method according to claim 1 wherein the mixed phase flow is partially formed by the release of a gas dissolved in the liquid.

23. A method according to claim 1 wherein the liquid includes solid particles.

24. A method according to claim 1 wherein the liquid includes one or more biocides.

25. A method according to claim 1 wherein the liquid includes one or more oxidizing agents.

26. A method according to claim 1 wherein the passageway divides into a plurality of conduits, each conduit having surfaces, wherein the opposite side of each of said surfaces defines part of the boundary of another conduit.

27. A method according to claim 26 wherein the passageways comprise a spiral wound membrane filter.

28. A method according to claim 1 wherein the passageway comprises an input header, a plurality of conduits, and wherein the mixed-phase flow contacts the inside of the conduits and the inside of the input header and the output header.

29. A method according to claim 1 wherein prior to forming the mixed-phase flow, the passageway is soaked in the liquid to soften the biofilm, debris and contaminants.

30. A method according to claim 1 wherein the mixed-phase flow is heated above ambient temperature.

31. A method according to claim 1 wherein the inlet pressure of the gas is at least 15 psig.

32. A method according to claim 1 wherein the passageway is exposed to ultrasonic vibrations during the removal period.

33. A method according to claim 1 wherein the liquid includes one or more surfactants.

34. A method according to claim 1 wherein the droplets are continually pulled from the surface of the liquid.

35. A method of removing biofilm, debris and contaminants from the exposed surfaces of a passageway having a portion of the surfaces comprised of a permeable membrane comprising

forming a mixed phase mixture of a liquid and a gas having a volumetric ratio of gas to liquid greater than 50:

1 by introducing at least a portion of the liquid through pores in the passageway at a sufficient velocity for a sufficient time to form droplets and bubbles that remove the biofilm, debris and contaminants.

36. A method according to claim 35 wherein the liquid is exposed to a pressure drop sufficient to initiate boiling.

37. A method according to claim 35 wherein the liquid contains a dissolved gas which forms bubbles due to the pressure drop through the membrane.

38. A method according to claim 35 wherein the passageways comprise a hemodialyzer.

39. A method according to claim 35 wherein the passageways comprise a hollow fiber membrane filter.

40. A method according to claim 35 wherein the passageways comprise a tubular membrane filter.