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Pipe or container cleaning process to remove heavy hydrocarbons and other contamination using liquid CO2 and a co-solvent

IP.com Disclosure Number: IPCOM000028131D
Publication Date: 2004-Apr-27
Document File: 1 page(s) / 8K

Publishing Venue

The IP.com Prior Art Database

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Title

Pipe or container cleaning process to remove heavy hydrocarbons and other contamination using liquid CO2 and a co-solvent.

Date of Invention 

The process of using LCO2 has been used by since 1996 for cleaning refrigeration oil from refrigeration system to change from CFC’s.  The same process was used at an industrial customer for cleaning gas piping that had been contaminated with oils and other hydrocarbons. 

Problem

Air Liquide has a customer with a pipe that has been contaminated with with a heavy hydrocarbon oil.  This oil is a synthetic PAO (Poly Alpa Olefin) which has a very high melting temperature (>700 F) and is stable at very high temperatures. 

The problem is how to remove this oil without adding conventional solvents or chemicals to the piping that could leave residual material inside the piping or require expensive and complicated disposal methods.  The optimal system would also require minimal time to do the cleaning.

The proposed solution is to use liquid CO2 as a preliminary cleaning agent.  This is fast and has the advantage of using the viscosity reducing characteristics of LCO2 and the advantage of capturing the oils/contaminants in the dry ice snow for easy capture and disposal.

The PAO oil is difficult to dissolve and the LCO2 does not remove all the residue.  The PAO oil is not very soluble in liquid CO2 at pressure ranges from 200 psig up to 1000 psig.  It appears that the LCO2 reduces the viscosity of the oil and “scrubs” the walls of the piping using the turbulent 2 phase (liquid-gas flow).  This is sufficient to remove the majo...