Method for cleaning hollow tubing and fibers

Abstract

Hollow porous fibers containing adhered contaminants are cleaned to remove the contaminants by backflushing a liquid to fill the pores, and adding a flow of gas so as to form a two-phase mixture of gas and bubbles of liquid that can scrub the fibers, loosening the contaminants and allowing them to be flushed from the hollow fibers. The method is particularly useful for cleaning hemodialyzers used for dialysis and hollow fiber modules used in water treatment and separations. The two phase flow method is specifically effective in cleaning piping systems having high length to diameter (l/d) ratios.

1 - 14 . (canceled) 
   
   
       15 . A method of removing contaminants from a hemodialyzer comprising
 backflushing the dialyzer membrane with a cleaning solution by pressurizing the solution from the dialysate side of the dialyzer,   forming a two-phase flow mixture by passing a gas into the lumen side of a plurality of porous hollow fibers and combining to form a mixed phase solution-gas mixture,   rinsing the dialyzer with water to remove said cleaning solution and contaminants, and   filling said dialyzer with a liquid sterilant.   
   
   
       16 . A method according to  claim 15  wherein the liquid to gas ratio of the two-phase mixture is from 1:50 to about 1:6000. 
   
   
       17 . A method according to  claim 15  wherein the liquid used for backflushing and the liquid injected into the fiber lumens are different. 
   
   
       18 . A method according to  claim 15  wherein the cleaning solution has a pH of over 7.0. 
   
   
       19 . A method according to  claim 15  wherein the cleaning solution has a pH within the range of 11.3 to 12.8. 
   
   
       20 . A method according to  claim 15  wherein cleaning is effective to remove middle solutes in dialysis patients. 
   
   
       21 . An apparatus for cleaning hemodialyzers comprising
 a two-phase dialyzer re-processing tank having an inlet for aqueous cleaning solution and an inlet for compressed air;   an outlet for delivering a two-phase flow of cleaning solution and air to a dialyzer to one or both of the lumen side and the dialysate side.   
   
   
       22 . An apparatus according to  claim 21  wherein the two-phase flow is directed to the lumen side. 
   
   
       23 . An apparatus according to  claim 21  wherein the two-phase flow is directed out of the dialyzer to a mist separator wherein the cleaning solution is separated from air. 
   
   
       24 . An apparatus according to  claim 21  wherein, after cleaning the dialyzer, it is rinsed with a mixture of water and air. 
   
   
       25 . An apparatus for cleaning a hemodialyzer having a plurality of membrane hollow fibers provided in a housing, wherein the hemodialyzer comprises a blood side within the membrane hollow fibers and a dialysate side within the housing and outside of the membrane hollow fibers, and the housing includes a blood side inlet, a blood side outlet, a dialysate side inlet, and a dialysate side outlet, wherein the apparatus comprises
 a water inlet,   a cleaning solution inlet,   a liquid outlet constructed for attachment to the dialysate side inlet or the dialysate side outlet of the hemodialyzer for providing a pressurized liquid cleaning solution to the dialysate side,   a compressed air outlet constructed for attachment to the blood side inlet or the blood side outlet of the hemodialyzer for providing pressurized air to the blood side, and   wherein, during operation of the apparatus, the liquid outlet and the compressed air outlet of the apparatus can provide a two-phase flow within the blood side of the hemodialyzer.   
   
   
       26 . An apparatus according to  claim 25 , wherein mist separator provides for separation of liquid and gas exiting the blood side inlet or the blood side outlet of the hemodialyzer. 
   
   
       27 . An apparatus according to  claim 25 , further comprising a compressor for providing compressed air to the compressed air outlet. 
   
   
       28 . An apparatus according to  claim 25 , further comprising a sterilant inlet. 
   
   
       29 . An apparatus according to  claim 25 , where at least one of a cleaning solution, water, or sterilant can be provided to the liquid inlet. 
   
   
       30 . An apparatus according to  claim 25 , wherein the apparatus provides compressed air to the plurality of hollow fibers of the hemodialyzer at a velocity of 10 ft/sec to 500 ft/sec. 
   
   
       31 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide a two-phase flow mixture of liquid and gas in the plurality of hollow fibers having an internal diameter of about 20 microns or higher. 
   
   
       32 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide a two-phase flow mixture of gas and bubbles of cleaning liquid in the plurality of hollow fibers of the hemodialyzer. 
   
   
       33 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide a two-phase flow mixture comprising droplets in the plurality of hollow fibers having diameter of about 50 microns to 250 microns. 
   
   
       34 . An apparatus according to  claim 25 , wherein the apparatus can provide cleaning solution to gas in the plurality of hollow fibers at a ratio of 1:50 to 1:6000. 
   
   
       35 . An apparatus according to  claim 25 , wherein cleaning solution from the cleaning solution inlet can be provided to the liquid outlet. 
   
   
       36 . An apparatus according to  claim 25 , wherein the water from the water inlet can be provided to the liquid outlet. 
   
   
       37 . An apparatus according to  claim 28 , wherein sterilant from the sterilant inlet can be provided to the liquid outlet. 
   
   
       38 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide reversed direction of two-phase flow through the plurality of hollow fibers of the hemodialyzer. 
   
   
       39 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide cleaning liquid from the dialysate side inlet or the dialysate side outlet into the plurality of hollow fibers of the hemodialyzer. 
   
   
       40 . An apparatus according to  claim 39 , wherein the apparatus is constructed to provide compressed air to form two-phase flow mixture in the plurality of hollow fibers of the hemodialyzer. 
   
   
       41 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide a pre-mixed two-phase flow of cleaning solution and compressed air to the blood side inlet or the blood side outlet of the hemodialyzer. 
   
   
       42 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide a heated cleaning solution to the liquid outlet. 
   
   
       43 . An apparatus according  claim 25 , wherein the apparatus is constructed to mix water and cleaning solution to form a mixture and direct the mixture to the liquid outlet. 
   
   
       44 . An apparatus according to  claim 25 , wherein the apparatus is constructed to provide compressed air to the dialysate side inlet or the dialysate side outlet of the hemodialyzer.