DE10252360A1 - Plastic foam decontamination process involves removal of fluorinated hydrocarbons by passing steam through an evaporation drum sealed by compacted plastic in extruders at each end - Google Patents

Abstract

The initial material is pelletized and fed continuously to first screw extruder(1) whose conical output end forms a solid material steam barrier. Pelletized material is pumped out into rotating evaporation drum(2). Steam(7) fed to the drum drives out the fluorinated contaminants and flows to filtering and condensation zone. Decontaminated plastic then flows via a shaft(4) into a second screw extruder(9). The initial material is pelletized and fed continuously to a first screw extruder(1) whose conical output end forms a solid material steam barrier. Pelletized material is pumped out into a rotating evaporation drum(2). Steam(7) fed to the drum drives out the fluorinated contaminants and flows to a filtering and condensation zone. Decontaminated plastic then flows via a shaft(4) into a second screw extruder(9) whose conical output end forms another steam barrier for the drum. Pelletizing produces particles 5-10mm across. Material passes through the evaporation drum under gravity. Condensate is subjected to phase separation. An Independent claim is included for the process plant which comprises a first screw extruder(1) with a conical output end forming a pressure tight connection to an evaporation drum(2), a steam feed pipe(5) into the drum, second screw extruder(9) with a conical output end forming a pressure tight connection to the output side of the drum and a gas outlet in the drum incorporating a filter.

Description

The invention relates to a method and a device for the treatment of contaminants Materials, especially contaminated with fluorocarbons Plastic foams through Degassing according to the generic term of the subordinate claims.

Are fluorocarbons (CFCs) organic compounds containing carbon and hydrogen atoms in the molecule contain. The hydrogen can be replaced by fluorine, chlorine, bromine, i.e. halogen be replaced, different depending on the number of halogens in the molecule A distinction is made between substance classes.

Because of their high durability and inertia CFCs and halons reach the higher areas of the atmosphere. In 10 up to 15 km altitude is the majority of ozone within the atmosphere. This ozone layer protects earthly life from harmful ones ultraviolet rays. The very reactive ozone molecules are located yourself naturally in a constant Assembly and disassembly. This existing equilibrium is Fluorine and bromine atoms destroyed, which are released from CFCs by UV light. When ozone depletion the chlorine, fluorine and bromine atoms are not consumed and can therefore a variety of ozone molecules columns.

According to the agreement concluded Production and consumption of CFCs will be reduced by 50% worldwide. Specifically, there is a gradual ban on use or manufacture certain CFC substances have been adopted. Specifically, partially halogenated Fluorocarbons will no longer be produced by the end of 2025 with gradual limitation their use. The establishment of recovery systems is also mandatory.

Worldwide consumption was in 1995 on ozone depleting Substances with almost 400,000 t ozone depletion potential. It must considered be that in existing plants, equipment and products considerable reservoir of ozone-depleting substances is stored. For example, about 30,000 tons were produced in Germany in 1997 ozone-depleting Substances used.

Combine fluorocarbons various properties of a broadly applicable connection group, they are largely non-toxic to people Animals and plants, do not react with other substances, are not explosive, non-flammable and odorless and tasteless. Advantageous is the low thermal conductivity, i.e. the corresponding fabrics are heat-insulating. Special thermodynamic Properties to a preferred use as a refrigerant. Technically significant Representatives are R11, R12, R113, R114 and R115. As explained above, is however the chemical stability, the difficult degradability and thus the longevity of CFCs in problematic to the environment.

With the use as a blowing agent with plastic foams fluorocarbons have been widely used. polyurethane or PUR flexible foams as upholstery material, for thermal insulation and for packaging purposes as well as PUR rigid foam as thermal insulation, integrated in cooling devices Foam or assembly foam are the main areas of application. In insulation materials has been using CFCs throughout Germany since 1994 and has also been used since 2000 from R22, i.e. a representative of the partially halogenated HCFCs.

Therefore comes from the above the recycling of plastic foams in particular with a separate collection option CFCs are becoming increasingly important. What makes matters worse is that the emission limit values for the Release of CFCs at R11 reduced to the value of 0.20% per kg of PUR foam so that new technical ways of degassing e.g. PUR foam, which comes from old cooling devices, for example, is to be found.

The previous recycling technology from Used refrigeration devices to several mechanical shredding levels using shredder and hammer mills back. Here, the body is separated into individual fractions to separate. The fractions concern iron, non-ferrous and plastic materials, Hardboard, small electrical material and insulating foam made of polyurethane.

The shredding itself takes place in closed enclosures instead, in which the enriched process air is suctioned off permanently.

To blowing agent R11 from PUR foam from e.g. Evacuate old cooling devices, it is previously known to undergo mechanical treatment by means of several grinding steps down to fine grinding. This reduces the proportion of blowing agent R11 to about 0.6% by weight R11 / kg PUR foam. A known thermal post-degassing with heating screws only a slight further improvement of about 0.2% by weight R11 / kg foam to a residual value that is no longer justifiable.

It is from the foregoing, therefore Object of the invention, a further developed method and a associated Device for the treatment of materials contaminated with pollutants, plastic foams contaminated in particular with fluorocarbons Specify degassing, which enables continuous process control and that compared to the prior art a much lower Residual value of pollutants in compliance with the emission limit values guaranteed.

The solution to the problem of the invention takes place with a method in its definition according to claim 1 and with a device with the combination of features according to claim 6th

The subclaims provide at least practical configurations and further training.

The basic idea of the invention goes accordingly, after-treatment of the fractionated plastic foam material with overheated Saturated steam. Here is a surprisingly satisfactory one Post-degassing takes place right into the plastic matrix.

According to the method, there is first a pre-shredding of the material to be treated to obtain a grain fraction. The pre-comminuted fraction then becomes essentially continuous placed in a first screw press. The screw press owns discharge a cone or a conical geometry, so that a solid seal due to the compressed grain fraction formed.

Output side of the screw press becomes a surrender the pre-shredded fraction into a coupled, rotating steaming drum performed.

In the steaming drum an application of the existing fraction there with registered superheated steam to drive out pollutants. The loaded steam is placed on a filter and condensation path led. which is followed by a phase separator and a cooled storage container for the condensate can be.

The cleaned fraction is on a second screw press with a conical discharge, whereby the second screw press also has a solid closure, which represents a vapor barrier with the first solid closure.

For the formation of this vapor barrier is understood to be the first and the second screw press gas-tight or pressure-tight with the Steaming drum are connected.

At the discharge of the second screw press can then the cleaned fraction removed and further processing be recycled.

The pre-shredding of the abandoned preferred plastic foams takes place on a grain fraction with grain sizes in the range of essentially 5-10 mm.

The transportation of the faction within the steaming drum is over gravitational forces realized, so that the procedural but also the constructive Effort of an appropriately trained device can be reduced can.

The method is suitable according to the invention its application in cleaning and degassing in a PUR matrix contained pollutants, especially CFC-containing blowing agents.

The treatment device according to the invention materials contaminated with pollutants, especially those contaminated with fluorocarbons Plastic foams starts from a first screw press with a conical discharge from which with a rotating steaming drum in essentially there is a pressure-tight connection.

There is one in the steaming drum Steam lance arranged to a device for hot steam generation is connected.

A second screw press with also conical Discharge is also provided, with the feed side of the second Screw press essentially pressure-tight on the discharge side the steam drum is fixed.

The steaming drum has one Gas outlet which includes a filter or with such a filter in Connection is established.

In a preferred embodiment the steaming drum is conical or frustoconical and spatially so arranged that the axis of the drum is substantially horizontal. By the cone shape is the desired gravity Transport of the loaded fraction from the loading side, i.e. the first screw press to the discharge side, i.e. to the second screw press.

In the above sense is the first screw press with its discharge to the top surface of the Steaming drum directed and the second screw press below or laterally offset, based on the foot area of the Drum arranged.

In the area of the foot surface of the steaming drum is in one embodiment the invention is a chute, the lower end of which is essentially pressure-tight leads to the second screw press.

The aforementioned steam lance runs preferentially essentially along the axis of the drum to be effective To cause degassing of the abandoned fraction.

The chute, the more constructive Can be part of the steaming drum, has at the top End of a gas outlet or merges into such an opening, whereby in the area of the opening a filter, in particular a roller belt filter, is provided.

The loaded steam passes through the Filters on a condenser with a phase separator is connected to separate the degassed pollutant and take.

The invention is based on the following of an embodiment and explained with the help of a figure.

The figure shows a schematic representation one to carry out device suitable for the method.

Pre-shredded PUR foam with grain sizes in the range <10 and> 5 mm is preferably used continuously in a first conical screw press 1 fed.

A solid forms due to the conical geometry of the first screw press on the discharge side closure that serves as a vapor barrier and that the grain fraction in the steaming drum 2 promotes.

The preferably conical steaming drum 2 rotates around one in the center of the drum 2 arranged steam lance 5 , The conical geometry of the drum 2 during rotation, taking gravity into account, leads to an automatic material feed in the direction of the shaft 4 or the second screw press 9 ,

With the grain in the steaming drum 2 is about the steam lance 5 Superheated steam added, ie steam is applied to the PUR grain with the result that degassing of the blowing agent contained in the PUR grain, eg R11, occurs almost instantaneously.

The degassed material fraction arrives at the exit of the steaming drum 2 in the aforementioned shaft 4 and finally under gravity into the second screw press 9 that works as a discharge screw. This discharge screw is also conical on the discharge side and thus provides a further pressure barrier in relation to the steam, which is preferably permanently introduced, inside the drum 2 represents.

The loaded steam is through an opening in the shaft 4 and a roll band filter 3 cleaned and fed to a condensation stage (not shown). This condensation stage can be followed by a phase separation device and a cooled storage container.

Furthermore, the device comprises a steam supply 7 and an overheating level 8th , A central control unit 6 serves to drive motors M1 to M4 and usual monitoring and control tasks.

1

first screw Press

2

Bedampfungstrommel

3

Roll filters

4

shaft

5

Bedampfungslanze

6

control

7

steam supply

8th

overheating stage

9

second Screw press (discharge screw)

Claims (13)

Process for treatment with pollutants contaminated materials, especially with fluorocarbons contaminated plastic foams by degassing, characterized by the following steps - pre-shredding the material to be treated; - essentially continuous Feeding the pre-shredded fraction into a first screw press, which has a first due to a discharge-side conical geometry Solid closure forms; - Handover of the pre-shredded Fraction in a discharge side of the screw press, rotating steaming drum; - loading of the parliamentary group in the steaming drum with superheated steam to expel pollutants and directing the loaded steam onto a filter and condensation section; - Lead the cleaned fraction in a second screw press with conical Discharge with receipt of another solid closure, which with the first solid closure, a vapor barrier for the drum represents and output of the fraction at the discharge of the second screw press. A method according to claim 1, characterized in that the condensate is subjected to a phase separation. A method according to claim 1 or 2, characterized in that that the pre-crushing to a grain fraction with grain sizes in the range of essentially 5-10 mm is done. Method according to one of the preceding claims, characterized characterized that the transport of the fraction within the evaporation drum done by gravity. Method according to one of the preceding claims, characterized by its use in cleaning and degassing contained in a polyurethane matrix Pollutants, especially CFC-containing blowing agents. Device for the treatment of contaminants Materials, especially contaminated with fluorocarbons Plastic foams by degassing, characterized in that a first screw press with conical design Discharge with a rotating steaming drum essentially is connected in a pressure-tight manner, a steam lance is arranged in the steaming drum is connected to a device for generating steam is a second screw press with a conical discharge is provided is, the feed side of the second screw press essentially is pressure-tightly fixed on the discharge side of the steaming drum, the Steaming drum has a gas outlet opening which Filters or is associated with one. Apparatus according to claim 6, characterized in that the steaming drum has a conical or truncated cone shape and spatially so is arranged that the axis of the drum is substantially horizontal runs. Apparatus according to claim 7, characterized in that the first screw press with its discharge to the top surface of the Steaming drum directed and the second screw press below or laterally offset, based on the foot surface or Floor space the drum is arranged. Apparatus according to claim 8, characterized in that in the area of foot or footprint the vaporization drum is a chute, the lower End essentially pressure-tight for feeding the second screw press leads. Apparatus according to claim 7, characterized in that the steam lance is substantially along the axis of the drum runs. Device according to claim 9, characterized in that the chute goes into a gas outlet at the top, being in the area of the opening a filter, in particular a roller belt filter, is provided. Device according to one of claims 6-11, characterized in that that the loaded steam is led to a condensation device. Device according to claim 12, characterized in that the condensing device is connected to a phase separator stands.