Apparatus and method for cleaning pipelines, tubing and membranes using two-phase flow

Abstract

An apparatus and method for cleaning passageways and the like with a two-phase mixture of gas under pressure and an aqueous cleaning solution. The two-phase cleaning mixture is generated in a module and is passed out of the module at a predetermined rate that determines droplet size, velocity and droplet density at the pipeline surface to be cleaned. The droplets impact the walls of the passageway to be cleaned, thereby fragmenting, eroding and removing contaminants in said passageway. These are then flushed out of the passageway by the two-phase flow. The flow of cleaning solution can be steady or pulsed. The apparatus and process include a clean-in-place system that is useful in food, beverage, pharmaceutical and similar process industries.

We claim:  
     
         1 . An apparatus for cleaning pipes, tubing and membranes comprising: 
 a module have a gas inlet and a liquid inlet wherein a two phase flow of gas and liquid is stored, and an outlet for passing the resultant two phase flow into one or more pipes, tubing or membranes to be cleaned;    an air or gas source for supplying said gas to said module;    one or more holding tanks for liquid connected to said module;    a first pumping means for supplying said liquid at a predetermined rate to said module;    a second pumping means for supplying gas under pressure to said module;    a mist separator connected to said module that collects said two phase flow, separates the gas and the liquid and passes them through separate outlets.    
     
     
         2 . An apparatus according to  claim 1  wherein said two phase flow has a gas to liquid ratio between about 50:1 to 15,000:1.  
     
     
         3 . An apparatus according to  claim 1  further including a backflushing line connected to one or more valves to supply pressurized liquid at a predetermined rate.  
     
     
         4 . An apparatus according to  claim 1  further comprising one or more holding tanks for supplying sanitizing solutions to aid module through one or more valves that deliver said sanitizing solution at a predetermined rate.  
     
     
         5 . An apparatus according to  claim 1  further comprising one or more holding tanks for supplying rinse solution to said module through one or more valves that deliver said rinse solution at a predetermined rate.  
     
     
         6 . An apparatus according to  claim 5  further comprising one or more valves and lines from said module to the lines being cleaned at a predetermined rate.  
     
     
         7 . An apparatus according to  claim 1  further comprising a controller connected to said apparatus for delivering cleaning solution, gas, rinse solution and sanitizer solution to said module at a predetermined rate and for a predetermined time, in any sequence.  
     
     
         8 . An apparatus according to  claim 1  further comprising a nozzle that generates droplets of a predetermined size to said module.  
     
     
         9 . A method of cleaning pipes, tubing and membranes comprising 
 mixing air under pressure and an aqueous cleaning solution having a pH of 1.0 to 14.0 in an enclosed module at a predetermined rate so as to obtain a gas to liquid ratio of between 50:1 and 15,000:1, thereby creating a two-phase flow of gas and liquid;    passing said mixture to one or more lines to be cleaned;    backflushing said lines with the cleaning liquid under pressure;    flushing said lines with a sanitizing solution;    rinsing said lines with an aqueous solution; and    drying said lines.    
     
     
         10 . A method according to  claim 9  wherein said two-phase mixture is formed using a nozzle that generates droplets in the liquid between 25 and 400 microns in size.  
     
     
         11 . A method according to  claim 9  wherein said gas and liquid pass along said pipes at a velocity of from 10 meters per second to 200 meters per second.  
     
     
         12 . A method according to  claim 9  wherein said gas and liquid is pulsed.