DE19821470A1 - Recycling of used refrigeration equipment containing pentane foam expansion agent - Google Patents

Abstract

Processing areas are divided between two chambers. Sufficient air is extracted and/or supplied separately under individual control, to stay below the lower explosive limit (LEL). Preferred Features: The chambers are connected, air flow being controlled between them. Inert gas is supplied into individual chambers. This is recirculated. Air from the chambers is treated by incineration. Concentrations of pentane and/or oxygen in individual chambers and/or at the outlets is measured periodically and/or continuously.

Description

The invention relates to a method for continuous up preparation of old refrigeration appliances, the insulation layer of poly there is urethane foam for which pentane is used as a blowing or blowing agent or another combustible gas was used as well as for the Preparation of other parts and components that ver contain comparable insulation foams.

Refrigerators (refrigerators, freezers) usually consist essentially of an outer shell made of metal (usually Fe or stainless steel), an insulation made of polyurethane foam, an inner shell (usually made of plastic or stainless steel), a refrigeration unit with evaporator and the corresponding electrical and electronic components. Up to now, old cooling devices have been used in continuous processes in accordance with the state of the art (cf., for example, disclosure documents of DPA No. DE 39 06 516 A1, DE 39 41 742 C2 and EP 0 538 677 A1) by means of multi-stage mechanical comminution in combination with appropriate separation technology. These processes are essentially divided into the main areas

• 1. Mechanical pre-shredding of the entire device with the predominant goal to break down the entire device into particles.
• 2. mechanical re-crushing (partly multi-stage) from the 1. Receive particles with the aim of separating the area various fractions by fine grinding or Crushing the particles down to sizes for downstream Separation processes are necessary, possibly connected with a Metal discharge.
• 3. Sorting and rejection of the different fractions the separation processes.
• 4. Fine grinding of the in the different areas and Pro steps in different particle sizes Polyurethane foam down to the pore size of this look (usually less than 200 µm).

The methods which operate according to the prior art are usually provided with a closed housing, the process steps described above usually taking place within a single housing and being connected to one another by appropriate conveying techniques. This housing has the purpose, among other things, of avoiding an uncontrolled release of the escaping gases to the environment and of sucking off these gases (CFCs) in a targeted manner and of separate treatment, e.g. B. by adsorption on activated carbon. This extraction takes place with air volumes up to over 1000 m ³ / h. These air volumes are required on the one hand as carrier gas for the removal of the CFC released, and on the other hand for the removal of the thermal energy released in the process.

Conventional processes for the treatment of old refrigeration devices put - e.g. T. targeted - in different areas of processing process the gases originally used as blowing agents free, u. a. for the purpose of degassing the isolation cells or Recovery of propellants. What is significant here is that the crowd of the released gas (previously CFC) essentially from the Zer depends on the smaller extent of the polyurethane foam and thus in the ver different proportions in different shredding steps be set. It has been shown in practice that in the mechanical pre- and post-shredding steps only one small percentage (approx. 10-20% of the total gas) released is and the essential gas release in the fine grinding process takes place. Nevertheless, due to the inside of the enclosure strong internal air circulation should be regarded as even determining gas distribution.

With the previous continuous processes only cooling devices could be processed, the polyurethane foam insulation not with a flammable blowing agent. An interpretation of this Process for refrigeration equipment in which combustible foam insulation were not necessary insofar as refrigeration appliances earlier years of construction with non-flammable propellants, usually CFC R11, were foamed. Because of the release of CFCs  associated destruction of the ozone layer and the associated Ban on placing CFC propellants on the market Refrigeration appliances insulated with polyurethane foam are now CFC-free, e.g. T. flammable blowing agents, especially various pentanes (e.g. Cyclopentane, isopentane, n-pentane and various mixtures of these) used.

Are used in conventional processes for the preparation of Used refrigeration devices but used refrigeration devices or other polyurethane Foam-containing parts and components processed in which pentane or another combustible gas is used as a foaming agent it has been shown that this is in the processing processes at gas released in various process steps - in connection with Air and depending on the concentration - a flammable and / or can form an explosive mixture within these enclosures, especially through the distribution of this gas throughout Housing.

Try the fire and / or explosion described above danger in the existing enclosures through the supply of inert gases have to fix themselves during the reprocessing process the high inert gas requirement has proven to be not economical. About that additions of such quantities of inert gas are control engineering difficult to control because of fluctuating processes Amounts of material used and the high air requirement of the entire Housing does not run under constant conditions.  

The invention has for its object a continuous, in at least one enclosure process included preparation of old refrigeration devices and / or existing ones To improve processes in such a way that in these processes too Used refrigeration devices or other parts and components with Insulating foams containing flammable blowing agents, especially pentane contained, can be spread under without risk of explosion Avoidance of inert gas supply or its substantial reduction an economic measure.

This object is achieved in that the various areas of the processing process are specifically divided into chambers in order to

• - A distribution of the in large quantities in the fine grinding step to avoid released gas in the entire housing
• - to supply individual chambers with large amounts of air, especially with the purpose of individual process areas (especially the shredding areas and separation areas) due to this high air volumes always below the lower explosion limit of the To drive propellant gas while maintaining those in these areas to ensure particularly necessary heat dissipation (the the minimum required air volumes result from the fixed lower explosion limits for the propellant in Connection with the throughput quantities of polyurethane foam)  
• - Areas that may need to be treated with inert gas (Area of very fine size reduction) as small as possible hold.

Furthermore, the problem is solved in that the different Chambers are individually supplied with air and this air for each Chamber is suctioned off separately. A merger of the individual air flows after extraction from the chambers to ge joint exhaust air treatment (e.g. by means of exhaust gas combustion) however possible. The individual chambers are for material transport using transport technology (e.g. conveyor belts) over locks connected with each other. With suitable air routing (e.g. Additional blowers on the locks) can cause unwanted through mixtures of the air areas of the different chambers avoided become.

The advantages of this procedure are

• - the avoidance of hazardous areas in almost that entire process flow through targeted process control below the Explosion limit of the released gas by excess air especially in the areas of low gas release and thus significant improvement in process reliability
• - targeted heat dissipation through high air volumes, as in the areas low gas release usually most of the process waste heat is released  
• - Improving the after-treatment of the gases released Adaptation of this post-treatment to the individual process areas
• - if necessary, more targeted, significantly reduced Use of inert gas in restricted areas and thus considerable cost reduction
• - Existing systems can be economically justified Effort to be retrofitted.

It shows exemplary

Fig. 1 with the process flow

Reference list

1

Material supply

2nd

Pre-shredding area

3rd

Post-shredding area

4th

Sorting area

5

Fine grinding area

6

Material removal

7

Exhaust air routing from the chambers

8th

Air supply to the chambers

9

Overall housing

10th

Inert gas supply

11

Partitions between the chambers

Claims (7)

1. A process for the continuous processing of old refrigeration devices and parts and components, the insulation of which consists of polyurethane foam, was used for the flammable propellant, in particular pentane, characterized in that the different process areas are accommodated in at least two separate chambers and at least individually regulated from this chamber the quantities of air are sucked off and / or supplied that are required to fall below the lower explosion limit of the propellant / air mixture. 2. The method according to claim 1, characterized in that this Chambers are interconnected and the air flows between these chambers can be controlled specifically. 3. The method according to claim 1 and 2, characterized in that in inert gas is supplied to individual chambers. 4. The method according to claim 1 to 3, characterized in that this inert gas is circulated. 5. The method according to claim 1 to 4, characterized in that the Exhaust air from the individual chambers is treated. 6. The method according to claim 1 to 5, characterized in that this Exhaust air treatment by means of thermal afterburning.   7. The method according to claim 1 to 6, characterized in that the Concentrations of pentane and / or oxygen in each Chambers and / or in the outlet air of these chambers regularly and / or is measured continuously.