A METHOD FOR REMOVING, CONDENSING AND COLLECTING PROPELLANTS FROM FOAM MATERIALS AND OTHER MATERIALS FOR WHICH THE METHOD IS SUITABLE IN AN ENVIRONMENTALLY FRIENDLY MANNER

Abstract: A method for removing, condensing and collecting propellants, e.g. chlorofluoro-carbons (CFCs) in an environmentally friendly manner from foam materials, e.g. insulant materials from old (discarded) refrigerators, district heating tubes and other materials for which the method is suitable. The method is based on the fact that the decomposition of the foam materials and accordingly the liberation of the propellant in the foam takes place in a liquid medium, e.g. water. In case the temperature of the liquid medium is equal to or above the temperature corresponding to the boiling point of the propellant at the actual pressure, the propellant is liberated from the foam as a gas. The propellant gases are conducted through one or several liquid media, e.g. water and/or one or several ''cold traps'' in which the temperature is below the temperature corresponding to the boiling point of the propellant gases at the actual pressure which causes that the propellant condenses. In case the temperature of the liquid medium is below the temperature corresponding to the boiling point of the propellant at the actual pressure, immediately upon liberation the propellant will condense when entering into contact with the liquid medium and be located in the process container according to the density of the materials. The condensed propellant and the non-condensed gases are optionally conducted to a succeeding treatment.

Description: A METHOD FOR REMOVING, CONDENSING AND COLLECTING PROPELLANTS FROM FOAM MATERIALS AND OTHER MATERIALS FOR WHICH THE METHOD IS SUITABLE IN AN ENVIRONMENTALLY FRIENDLY MANNER Background of the invention The invention relates to a method for driving off and collecting pro¬ pellents, e.g. chlorofluoro-carbons (CFCs) from foam materials, e.g. insulating foam in refrigerators, freezers, district heating tubes, etc. DK patent application Nos. 4084/89 and 1306/90 disclose the only methods known at present which are environmentally friendly for driv¬ ing off and collecting propellants, e.g. CFCs from foam materials. By other prior art techniques it is only possible to destroy these foam products in such a manner that the propellants are liberated and either escape into the atmosphere thus charging the environment and/or are being decomposed to highly poisonous products. If foam products are decomposed mechanically (crushed) without being surrounded by a liquid medium it is difficult to condense the propel¬ lants sufficietly as the propellant gases are mixed with large amounts of air which impede a subequently efficiently condensing. Accordingly, these materials are being deposited for being removed/ destroyed at a later time when a suitable method has been developed. In the following, the term "process container" is used describing the part of the equipment which e.g. contains/consists of: A process vessel in which the mechanical decomposition and an optional condensing takes place and the part of the equipment which is neces¬ sary for the collecting of the propellant gases and non-condensable gases. The method is based on the fact that the mechanical decomposition of the foam material which may be attached to one or more solid sides, e.g. a side plate of a refrigerator takes place in such a manner that the propellant does not escape into the atmosphere, as the foam mate¬ rial together with the propellants during the decomposition process and the liberation process, is surrounded/confined and thus in contact with a liquid medium, e.g. water. By decomposing the foam material in a liquid medium having a tempera¬ ture equal to or above the temperature corresponding to the boiling point of the propellant at the actual pressure, the propellant present in the structure (cells) of the foam material is liberated from the foam product. This liberation of the propellant causes that the propellant contacts the liquid medium thereby ensuring that due to the temperature of the liquid medium, the propellant is liberated from the foam product as a gas, ascends as a gas, breaks the surface of the liquid medium and is collected under the top of the process container. From the top of the process container all of the liberated gases are conducted through one or several containers containing a cold liquid medium, e.g. water in which a condensing takes place and/or the gases are conducted through one or several "cold traps" in which the propel¬ lant gases are being condensed. By using a cold liquid medium for effecting said condensing, the con¬ densed propellant and the cold liquid medium is provided according to the miscibility and density of the two media. Thereafter, the propellant condensate is conducted to a succeeding treatment. In the "cold traps" the propellant gases will condense and be collect¬ ed at the bottom of the "cold trap" from where it is conducted to a succeeding treatment. Succeedingly, the remaining gas/air mixture (mixture of equilibrium) is conducted to and through a medium, e.g. butanol which removes the remaining propellant gas. From this medium the propellant can be re- moved by distillation. A smaller amount of the propellant will remain inside the process con¬ tainer in the liquid medium in a proportion corresponding to the solu¬ bility. The above method is characterized in that the liberation process of the propellant takes place inside a totally or partly closed process container containing a liquid medium having a temperature equal to or above the temperature corresponding to the boiling point of the pro- pellant at the actual pressure, said liberation process is performed by means of mechanical equipment located below the surface of the liquid medium performing a mechanical decomposition, e.g. rolling, compression and/or other ways of decomposing the foam material in such a manner that the propellant is pressed out of or/liberated from the foam product and is brought into contact with the surrounding liquid medium and is collected in a collecting part/container and conducted to the codensation for a succeeding treatment. The process container is constructed in a manner avoiding any uncon- trolled blow offs of propellant gases into the atmosphere and ensuring that a minimum of non-condensable gases, e.g. air are added (introduc¬ ed). The process container is constructed in a manner ensuring that a mini- mum of non-condensable gases, e.g. air are carried along (introduced) by introduction of the material to be decomposed. The upper part of the process container may act as a propellant gas collecting container from which the gases are conducted to condensing equipment, equipment for removing the remainder of the propellant from the air/gas mixture and equipment for optional removal of other ex¬ traneous gases. The mechanical method of decomposing the foam depends on the nature of the foam material to be decomposed. When mechanically decomposing the foam products, firm components, e.g. remainders of foam and metal wastes are removed from the process con¬ tainer by means of well-known technology. By decomposing the foam material in a liquid medium, e.g. water having a temperature equal to or below the temperature corresponding to the boiling point of the propellant at the actual pressure, the propellant which is located in the structure (cells) of the foam material is lib- erated. This liberation of the propellant causes that the propellant contacts the liquid medium whereby it is condensed (liquidized). Due to any differencies of densities between the condensed propellant and the cooling medium and the non-miscibility between the propellant and the cooling medium, the/those condensed propellants and the cooling medium are located in the process container in separate layers. The above method is characterized in that a mechanical decomposition is performed, e.g. compression, rolling and/or other ways of decompos¬ ing the foam material in a process container containing a liquid medium having a temperature below the temperature corresponding to the boiling point of the propellant at the actual pressure, which decomposition is performed by means of mechanical equipment which is located below the surface of the liquid medium and in such a manner that the propellant is pressed out of or/liberated from the foam product and contacts the liquid medium whereby it is condensed. Following the condensing process, according to its density, the con¬ densed propellant will be located in the the process container from which it can be recharged for a further treatment. Succeedingly, the remaining gas/air mixture (mixture of equilibrium) is optionally conducted through one or several "cold traps" and/or through a medium, e.g. butanol which removes the remaining propellant gas. From this medium the propellant can be removed by distillation. A smaller amount of the propellant will remain inside the process con¬ tainer in the liquid medium in a proportion corresponding to the solu¬ bility. In a specific embodiment, the cold liquid medium can be identical (same product) with the condensed propellant. The upper part of the process container may optionally act as a gas collecting container for non-condensed gases which may originate from the state of equilibrium of the materials. From this part of the process container, the gases are conducted to equipment for a succeeding treatment for removal of remaining propel¬ lants from the air/gas mixture and further on to equipment for optio¬ nal removal of other extraneous gases. In order to avoid that undesired vapours is blown off into the atmos¬ phere, the process container can be closed thus having the effect that non-condensable gases are removed through blow-off valves and/or through a controlled mechanical ventilation and are conducted to fil- ter units outside the plant. The process container is constructed in manner avoiding any uncontrol¬ led blow-offs of propellant gases into the atmosphere and ensuring that a minimum of non-condensable gases, e.g. air, are added (intro- duced). The process container is constructed in a manner ensuring that a mi¬ nimum of non-condensable gases, e.g. air are carried along (introduced) by introduction of the material to be decomposed. The method of decomposing the foam depends on the nature of foam ma¬ terial to be decomposed. When mechanically decomposing the foam products, solid components e.g. remainders of foam and metal wastes are removed from the process con¬ tainer by means of well-known technology.

Claims: CLAIMS 1. A method for removing, condensing and collecting propellants, e.g. chlorofluoro-carbons (CFCs) in an environmentally friendly manner from foam materials, e.g. insulants from old (discarded) refrigerators, district heating tubes and other materials for which the method is suitable, c h a r a c t er i z e d in that the mechanical decomposi¬ tion of the product and the liberation of the propellant is effected inside af partly closed process container under/in a liquid medium, e.g. water. 2. A method according to claim 1, c h a r a c t e r i z e d in that the liquid medium in which the liberation of the propellant is taking place, has a temperature equal to or above the temperature correspond- ing to the boiling point of the propellant at the actual pressure after which the gaseous propellant is collected in a gas collecting part and is conducted to a container containing a liquid medium, e.g. water, in which the propellant is condensed, said liquid medium has a temperature which is below the temperature corresponding to the boiling point of the propellant at the actual pressure, and then the propellant is re¬ moved from said liquid medium for a succeeding treatment. 3. A method according to claim 1, c h a r a c t e r i z e d in that the liquid medium, e.g. water in which the liberation of the propel- lant takes place has a temperature which is below the temperature cor¬ responding to the boiling point of the propellant at the desired work¬ ing pressure, whereby the the condesing of the propellant takes place in said liquid medium from which the propellant is removed for a suc¬ ceeding treatment. 4. A method according to claims l and 2, c h a r a c t e r i z e d in that the condensing is performed by means of one or several "cold traps" in which the temperature is below the temperature corresponding to the dew point of the propellant. 5. A method according to claims 1,2 and 4, c h a r a c t e r i z e d in that the condensing is performed by means of a combination of a cold liquid medium and one or several "cold traps". 6. A method according to claims 1 and 2 or 1 and 4 and/or 5, c h a ¬ r a c t e r i z e d in that a combination of several condensing steps by means of a liquid medium which may have different temperatures, and several "cold traps" which may have different temperatures. 7. A method according to claims 1 and 2 or 1 and 3, c h a r a c t e r - i z e d in that the method takes place in a process container closed with one or several traps. 8. A method according to claims 1 or 2 or 1 and 3, c h a r a c t e r ¬ i z e d in that the method takes place in a closed process container. 9. A method according to claims 1 and 2 or 1 and 3 and/or 4 and/or 5 and/or 6 and/or 7 and/or 8, c h a r a c t e r i z e d in that the pro- cess plant is connected to peripheral equipment for a succeeding treat¬ ment of the remaining non-consensed/bound gases.

Inventors: VOERS LAU OVE, VOERS, LAU, OVE
Applicants: VOERS LAU OVE, VOERS, LAU, OVE
Application year: 1990
Main classification: B29B17
IPC codes: B09B3, C08J11, C09K3