GB2383761A

GB2383761A - Process for the removal of blowing agents / ozone depleting substances from rigid foam in refrigeration equipment

Info

Publication number: GB2383761A
Application number: GB0200111A
Authority: GB
Inventors: Anthony James Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-01-04
Filing date: 2002-01-04
Publication date: 2003-07-09
Also published as: GB0200111D0

Abstract

A process for the removal of ozone depleting substances (ODS) from foam insulating material of refrigerator equipment carcasses 4 involves (after degassing and removing the compressor unit) removing the top and bottom of the carcass, placing the remaining shell 4 within an hermetically sealed enclosure 14 (seals 15) and grinding down the foam insulant with a series of rotating augers 7 and brushes (positioned at the end of flexible driving shafts 8 and driven by gear train 10, 11) so as to produce a concentrated mixture of ODS vapours which may be subsequently collected. The concentration of the vapours is increased by filling any void spaces within the carcass with bulk material or an inflatable air bag 18. This also serves to facilitate the removal of any vapours which are released from the foam (and which are additionally recycled to the enclosure so as to minimise loss to the atmosphere). Foam residue falls in to hopper mill 9, underneath which outlet 13 (which may carry mill driveshaft 12) is positioned. A relationship between clamps 16, flexible bellows 6 and a switch within lid 1 allows the sideways oscillation of the carcass so as to ensure the removal of all foam. Augers may be arranged in an offset double row and may also have a quick-release nature so as to be removed and replaced with augers of different sizes. An interlocking system 3 prevents enclosure lid 1 being open until the ODS vapour concentrations reach a pre-determined level.

Description

Process for efficient removal of blowine agents from rigid foam in refri2eranon equipment Background (0001) Current state of the art involves passing the refrigerators through a shreddmg machine such as is used for recycling motor cars and collecting the remains for recycling or destruction The Ozone Depleting Substances (ODS) vapours released in the process are trapped m a regenerative activated charcoal system for reuse or destruction This process is inherently inefficient and is difficult to apply control standards to The main disadvantages are (1) that the process requires high energy (typically 1000kW), (2) there is an estimated 10-1lg fugitive emission of ODS per refrigeration unit destroyed (not including any such losses from the degassing process of the compressor), (3) recyclates are of poor quality due to cross contamination (e g thermoplastic inner shell contaminated with foam resides, different types of foam processed giving a mixed powdered foam product) and (4) it is difficult to verify that ODS emissions are within any specification limits. A fifth problem concerns the destruction of equipment which was blown with flammable vapours such as pentane because there is a nsk of explosion within the plant. For this reason it is normal to purge with nitrogen during processing.

(0002) According to this invention, refrigerators are first degassed in order to remove ODS from the compressor unit (as is also done with the shredding process described above) and the compressor and its ancillaries removed from the carcass of the refrigerator for recycling before cutting off the top and bottom with a fine bladed bandsaw, so that disturbance to the foam at this stage is minimal The top and bottom sections can be separately treated in an embodiment of the same process

f (0003) The refrigerator carcass (4) is placed in a hermetically sealed enclosure (14) (seals shown 15) so designed as to have as small an internal dead space as possible Packing (18) by a solid material or an inflatable airbag fills such unwanted space Clamps (16) secure the carcass, and an array of rotating augers (7) (along all four sides) is driven via a gear train (10,11) into the foam sandwich layer (4) so as to remove and comminute it, leaving the inner plastic and outer wall substantially mtact Wire brushes mounted behind the augers ensure complete removal When the augers have passed through the foam, they engage in slots in the lid of the enclosure (2) A switch within the lid then activates a drive motor which acts on the clamps, causing them to oscillate sideways, ensuring that any foam is completely removed. For this to be possible, the long dnveshafts to the augers (8) must be sufficiently flexible to take up the movement. A flexible bellows (6) enables the movement to be accomodated by the enclosure itself Such flexibility within the system also allows for curvature in the doors which is sometimes used as a styling feature. The foam resides fall into a hopper which has a mill (9) placed in the outlet so as to ensure complete reduction of the foam and release of ODS from it. Beneath the mill is an outlet (13) (which can conveniently carry the driveshaft (12) for the mill) to a storage hopper from which foam can be either bagged or transferred m bulk. Drive motors are not shown in figure 1 for reasons ofclanty.

(0004) While the foam is being removed, the air in the enclosure is drawn out via a

paitculate filter Because the ODS concentration mside the plant is high, the off- gases may conveniently be compressed, causing much of the ODS vapours to condense out for direct collection before passing to a regenerative activated charcoal unit (not shown) or any equivalent system to collect it Cleaned air is returned to the enclosure. Monitoring equipment located in the off-gas outlet capable of detecting the presence of ODS is operated continuously and an interlock (3) to the hd of the enclosure held closed until the concentration of ODS has dropped to a predetermined level (0005) Figure 2 is a flow chart illustrating the process.

Embodiments (0006) A first embodiment of the present invention m which an end-of-hfe refrigerator is stripped of foam, ODS recovered and the remams recovered for recycling is described in Figure 2.

(0007) A second embodiment of the present invention in which an end-of-life freezer is stripped of foam m a similar manner to the first embodiment but because the foam layer is thicker an offset double row of augers is used in a variation of the process plant (0008) A third embodiment of the present invention in which an end-of-life freezer is stnpped of foam in a similar manner to the first embodiment but because the foam layer is thicker a proportionally larger sized auger is used in a variation of the process plant This may also be the original plant equipped with quick-release augers so that they can be changed to an appropriate size between stripping operations of either refrigerators or freezer units.

(0009) A fourth embodiment of the present invention m which the top and bottom parts of the carcass of either a refrigerator or freezer are stripped of foam in a similar manner to the first embodiment. Before placing these into the process plant and clamping them individually into place, the edges on two opposite sides must first be trimmed away using a fine-bladed bandsaw as close to the outer edge as possible so as to minimally disturb the foam In this embodiment, the clamps press the panels agamst the inner dead-space filler.

(0010) A fifth embodiment of the present invention in which panels are cut to standard sizes, typically with applicability to larger freezers, including industrial freezers (which would otherwise not be able to be fitted into the process plant as descnbed in the first embodiment) but which could be done with refrigeration equipment of any kind The panels can then be stnpped as in the fourth embodiment (0011) A sixth embodiment of the present invention in which carcasses which have been identified as containing different lands of foam are batched separately through the process plant of the other embodiments and the reduced residues collected separately so as to improve their recyclability. Once the top and bottom of the carcass has been cut away, the foam can be inspected for type (usually identifiable by colour

and texture) and the blowing agent by an appropriate gas monitor with a probe which can be inserted into the foam so as to facilitate such batchmg up.

(1012) A seventh embodiment of the present invention in which foams which have been blown with flammable (typically hydrocarbon based) blowing agents are batched separately through the process plant of the other embodiments. The nsk of explosion or ignition of flammable vapours is low provided that normal precautions are taken for the operation of process plant in flammable atmospheres because the concentrations produced within the plant are likely to be above the upper flammable limit and the dead space is small so that energy available to any such explosion or ignition is limited. Nonetheless, the plant should be operated remotely if such flammable vapours are likely to be present.

Figure 2 First embodiment for reclamation process for ODS and other recyclates from end-of-life refrigeration equipment 1 Degass refrigerator compressor 2 Remove compressor assembly and radiator 3 Open and remove any intemals (shelves etc) 4 Cut top and bottom off carcass so as to leave an oopen ended box. The cut should be close to the inner surfaces 5 Check nature of foam. Segregate types-PU, PS 6 Check blowing agent. Segregate hydrocarbon blown foams 7 Place carcass in foam remover 8 Clamp carcass.

9 Close lid 10 Start mill.

11 Start gas extraction system 12 Start augers. When augers engage in lid, sideways movement automatically operates 13 Stop augers when cycle is complete 14 Open lid when interlock releases. Stop mill. Stop gas extraction system Open lid when interlock releases.

15 Unclamp and release inner and outer shells.

16 Remove for recycle

Claims

Claims I An efficent, low energy process for the removal of ozone depleting substances from refrigeration equipment by grinding down the foam msulant using a system of augers and brushes, producing an off-gas mixture which is nch in ODS vapours which are thus easily collected
2 An interlocking system which prevents opening the enclosure of the processing plant according to claim 1 until ODS vapour concentrations within have been reduced to a predetermined concentration.
3 Recycling of cleaned off-gases to the enclosure of the processing plant according to claim 1 to further reduce any losses to atmosphere and protect against breakthrough of ODS should the ODS collection system begin to

fall. 4 A design according to Claim 1 to minimise by careful consideration of internal dimensions and clearances, and the filling of any voids with either bulk material or inflatable airbags, any internal dead spaces within the enclosure so that the concentration of any ODS released from the foam as off-gases is high and thus lends itself to more efficient removed therefrom 5 A mill to release any residual ODS from incomplete reduction of the foam which operates at the outlet of the process plant as claimed in Claim 1 6. A means of separating foam according to type and blowing agent so as to facilitate separation of carcasses for efficient batch processing and improving the quality of any recyclates from the process