DE4446964C2 - Method and device for the pyrolytic decomposition of plastic waste - Google Patents

Description

The present invention relates to a method and a Device for the pyrolytic decomposition of plastic waste and in particular a way of doing it effectively pyrolytic decomposition of waste plastic, including polyvinyl chloride resins and the like, can undertake training of a high quality Heating oil through pyrolysis of the waste plastic.

Plastic materials are usually used to a large extent Manufacture of electrical household items and numerous other items due to their beneficial Properties, low weight and good Strength used, but the cycle of manufacture and of Consumption of the plastic material also has large amounts Waste plastic objects result, and such Waste plastic items are currently incinerated will be or be sent to landfill. More recently because legislation in some countries around the world Recycle provides, e.g. B. since 1991 in Japan public interest in recycling and recycling Reuse of waste plastic products.

Plastics come in numerous types and at Production of an object from plastic are in the general different types of plastic used. however each type of plastic requires a different one Treatment method to facilitate reprocessing.  

As a result, it is necessary that the Waste plastic objects in the different components depending on the type of plastic used, where however, this work is tedious and it is also in practice it is difficult to do this work completely. As a result, it is inevitable that the quality and the Value of the products thus recovered because of this incomplete separation deteriorate. Especially difficult cases it is even impossible that Practical recovery.

Under these circumstances, a technique of Large scale dry distillation of waste plastics Attracted attention because this technique allows from waste plastic items products with proportionate recover high value. Such However, dry distillation technology currently requires high Cost and it is still required that Improve recovery efficiency of this technique. It's also when you're dealing with thermoplastic Bypasses materials such as polystyrene, and polypropylene the like, which have low thermal conductivity, difficult, even and rapid heating of large volumes of plastic objects cause, and from such a thermoplastic source oil obtained consists of a variety of components with boiling points far apart. That is why it is at the practical implementation of the dry distillation technique also required the quality of the oil obtained improve.

A method of improving oil quality is described in the Japanese Patent Application Laid-Open (Kokai) Nos. S63-178195 and H2-29492 proposed, namely the use of a Vapor phase reaction catalyst such as zeolite and the like to improve oil quality.  

In a device for performing this method however, when containing a waste plastic mixture Polyvinyl chloride resin (hereinafter referred to as PVC resin) is thermally decomposed, corrosive hydrogen chloride gas are generated, which deactivates the catalyst. About that In addition, the wall of the thermal decomposition furnace damaged. This is very disadvantageous for the pyrolytic Decomposing device, in particular if the Decomposition device under increased pressure for manufacture of a light oil is used. In addition, the im PVC resin contains plasticizers harmful organic Chlorine compounds which contaminate the oil obtained, and often some products cause the decomposition of the Plasticizer a silting up of the gas flow and Pipe system in the decomposition device.

DE-OS 24 15 412, JP-A-62-15240, JP-A-62-184034 and DE-OS 43 44 311 describe a method and an apparatus for the treatment of high molecular weight hydrocarbons, wherein the hydrocarbons thermally into a light and a Heavy component cracked and from the light component further cleavage oils can be obtained. DE-OS 42 43 063 and DE-OS 42 07 976 describe similar processes, in which the thermal decomposition of halogenated plastics in Presence of alkali or alkaline earth bases is carried out.

As previously mentioned, the usual methods are: thermal decomposition of waste plastic problems on which affect the durability of the decomposition apparatus, as well as the poor oil quality and the low Recovery yield for the fuel oil obtained, and it there is a need due to the generation of Hydrogen chloride gas and plasticizer products protection against pollution and damage to reach.  

In addition, the remains after the pyrolytic decomposition Plastic materials charred residual products in the Splitter. Will the pyrolytic decomposition repeated, then this residue product from the Disintegrator can be removed to another Feed some of the waste plastic material to be decomposed. However, the residue product, especially the Residue, the plastic waste containing PVC resin consists of the decomposition device and is often only with greatest difficulty to remove from the device. As a result, it is necessary during the Cleaning work to the operation of the decomposition device interrupt. However, this will make the operating efficiency of the Decomposition device significantly reduced.

The object of the invention is therefore to provide a method for pyrolytic decomposition of plastic materials for To be able to provide one high quality fuel oil from waste plastic items for To provide and being the disintegrator remains mechanically durable.

Another object of the present invention is to provide a Device for the pyrolytic decomposition of PVC-containing Waste plastic materials available at Obtaining a high quality fuel oil from Waste plastic items that are operated effectively can and where the organic chlorine compound contained in the collected fuel oil is present is reduced.

Another object of the present invention is to provide a To provide a device that allows the Decomposition residue easily from the decomposition reactor remove the decomposition that has occurred.

The present object of the present invention is achieved by a method for pyrolytic decomposition of a  Plastic material comprising: a first thermal Decomposition stage for the thermal decomposition of the plastic in an atmosphere of normal or reduced pressure below Formation of a primary decomposition product in gas form and a decomposition residue; a separation stage to separate the primary decomposition product into a first fraction, the one can contain desired low-boiling constituent and a second fraction that is heavier-boiling than the first Fraction, by condensation of the second fraction; a second thermal decomposition stage for the thermal decomposition of the separated second fraction in an atmosphere using a different from the first decomposition stage and higher pressure is applied, forming a second Decomposition product containing the desired light boiling ingredient in gaseous form; and a collection level for Collect the desired low-boiling ingredient from the first fraction and the second decomposition product.

A preferred embodiment of the invention pyrolytic decomposition process includes: a first thermal decomposition stage for the thermal decomposition of the Plastic in the presence of an alkaline material in one Atmosphere of normal pressure to form a primary Decomposition product in gas form and one Decomposition residue; a first cooling stage for cooling the primary decomposition product at a first cooling temperature separating the primary decomposition product into one first fraction that desired a low-boiling May contain component and a second fraction that is heavier-boiling than the first fraction Condensation of the second fraction; a second thermal Decomposition stage for the thermal decomposition of the second Fraction of the primary decomposition product in one on one predetermined pressurized atmosphere under training of a secondary decomposition product containing the desired low-boiling component in gaseous form; and a second cooling stage for cooling the first fraction and the  secondary decomposition product in a second Cooling temperature that is lower than the first cooling temperature to condense a fraction that easily contains boiling ingredient.

Another pyrolytic decomposition process according to the present invention is useful for decomposing plastic containing polyvinylchloride and comprising: a first thermal decomposition stage for the thermal decomposition of the Plastic in an atmosphere of normal or reduced Pressure to form a primary decomposition product in Gaseous form and a decomposition residue, the primary Decomposition product of hydrogen chloride, which results from Has formed polyvinyl chloride contains; a separation stage to Separate the primary decomposition product into a first one Fraction that has a desired low-boiling ingredient may contain and a second fraction, the heavier-boiling than the first fraction, by condensation of the second Fraction, with hydrogen chloride in the first fraction is introduced; a second thermal decomposition stage for thermal decomposition of the second fraction in one Atmosphere that is pressurized to a predetermined pressure to form a secondary decomposition product containing the desired low-boiling component in Gaseous form; and a collecting stage for collecting the desired one low-boiling component from the first fraction and the secondary decomposition product by condensation thereof.

Another pyrolytic decomposition process according to the present invention for decomposing suitable plastic and contains: a first thermal decomposition stage for thermal Decompose the plastic containing polyvinylchloride in an atmosphere of normal pressure to form a Decomposition residue and a primary decomposition product, which contains hydrogen chloride; an alkali treatment step to Treating the primary decomposition product with a  Alkali material to essentially from the primary Decomposition product to remove the hydrogen chloride; and a second thermal decomposition stage for thermal decomposition of the primary decomposition product after the Alkali treatment step in one with a predetermined pressure pressurized atmosphere forming a secondary Decomposition product that is lighter-boiling than the primary Decomposition product and the desired low-boiling Contains ingredient.

The pyrolytic decomposition method according to the present Invention is also for decomposing Suitable plastic and contains: a Heating step for heating the polyvinylchloride-containing Plastic in the presence of an alkali material, whereby Hydrogen chloride from the polyvinyl chloride is heated and is neutralized by the alkali material; a first thermal decomposition stage for the thermal decomposition of the Plastic in an atmosphere of normal or reduced pressure to form a primary Decomposition product in gas form and one Decomposition residue; a separation stage to separate the primary decomposition product into a first fraction, which the can contain desired low-boiling constituent and a second fraction that is heavier-boiling than the first Fraction, by condensation of the second fraction; a second thermal decomposition stage for the thermal decomposition of the second fraction of the primary decomposition product in one with a predetermined pressurized atmosphere Formation of a second decomposition product, which the contains the desired boiling component in gaseous form; and a Collection stage for collecting the desired low-boiling Part of the first fraction and the second Decomposition product by condensation of the same.

The pyrolytic decomposer according to the present The invention comprises: a first thermal decomposer  for thermal decomposition of the plastic in an atmosphere of normal or reduced pressure to form a primary decomposition product in gaseous form and one Decomposition residue; a separator for separating the primary decomposition product into a first fraction, the one can contain desired low-boiling constituent and a second fraction that is heavier-boiling than the first Fraction, by condensation of the second fraction; a second thermal decomposition device for thermal decomposition the second fraction in one with a predetermined pressure pressurized atmosphere forming a second Decomposition product that has the desired low-boiling Contains component in gaseous form; and a collecting vessel for Collect the desired low-boiling ingredient from the first fraction and the second decomposition product Condensation of the same.

Another device for pyrolytic decomposition of polyvinylchloride containing plastic according to the present The invention comprises: a first thermal decomposer for thermal decomposition of the plastic in an atmosphere of normal or reduced pressure to form a primary decomposition product in gaseous form and one Decomposition residue; a separator for separating the primary decomposition product into a first fraction, the one can contain desired low-boiling constituent and a second fraction that is heavier-boiling than the first Fraction, by condensation of the second fraction; a second thermal decomposition device for thermal decomposition of the second fraction in one with a predetermined pressure pressurized atmosphere forming a secondary Decomposition product containing the desired light boiling ingredient in gaseous form; and a collection container for Collect the desired low-boiling ingredient from the first fraction and the secondary decomposition product Condensation of the same, the first and the second thermal decomposition device an inner vessel, a  outer vessel that removably removes the inner vessel can accommodate, and a heater to heat the outside Vessel comprises, the outer vessel one Has heat transfer part that matches with the inner vessel is connected when the outer vessel and the inner vessel be heated to improve the heat transfer between the outer vessel and the inner vessel.

Furthermore, the pyrolytic comprises Decomposing device a thermal decomposer for thermal decomposition of the plastic with training a decomposition product and a decomposition residue, and the thermal decomposer includes: an inner one Vessel for holding the plastic; an outer vessel that in removably can hold the inner vessel, and one Heater for heating the outer vessel, the outer one Vessel has a heat transfer part that fits is in contact with the inner vessel when the outer vessel and the inner vessel to be heated to improve the Heat transfer between the outer vessel and the inner one Vessel.

In the present invention, when the waste plastic includes halogen-containing plastic, the pyrolytic decomposition be carried out effectively, contamination of the obtained fuel oil is avoided. Furthermore, the Mode of action of the pyrolytic decomposition of the Plastic waste can be improved and the oil obtained can be made in high quality. It is also possible the pyrolytic decomposition device to operate in a row. Aftercare of the pyrolytic decomposer is very simple.

Brief description of the drawings

The features and advantages of the method and the Device for pyrolytic decomposition of plastic according to  the present invention will be more readily apparent from the following description of the preferred embodiments of the present invention understandable in Connection with the attached drawings, in which same reference numerals same or similar elements or Sections in all figures mean.

Fig. 1 is a schematic representation of a first exemplary embodiment of the device for pyrolytic decomposition of plastic material according to the invention;

Fig. 2 is a schematic description of a second exemplary embodiment of the apparatus for carrying out the pyrolytic decomposition of a plastic material according to the present invention;

Fig. 3 is a vertical cross sectional view showing an exemplary configuration of a decomposition vessel, which the present invention is used for pyrolytic decomposition of plastic material according to;

Fig. 4 is a schematic description of an exemplary configuration for an apparatus in which the decomposition vessel of Figure 3 is used for carrying out the pyrolytic decomposition of a plastic material according to the present invention.

Fig. 5 is a horizontal cross section of the decomposition vessel of Fig. 3;

Fig. 6 is a vertical cross sectional view showing another exemplary embodiment of a decomposition vessel, which is used for the pyrolytic decomposition of a plastic material according to the present invention;

Fig. 7 is a vertical cross sectional view showing a third exemplary embodiment for a decomposition vessel, the invention is used for pyrolytic decomposition of plastic material according to;

Fig. 8 is a vertical cross section showing a plurality of inner vessels of Fig. 7 stacked; and

Figure 9 is a schematic description for an embodiment of the device that includes two decomposition vessels.

First, the basic principles of the process for pyrolytic decomposition of plastic material according to the present invention explained.

Are plastic materials at a temperature in the range from 300 to 600 ° C under normal pressure without the intended Supply of oxygen decomposes pyrolytically, then different components with different molecular weights, contained in the pyrolysis gas at the same time manufactured. Therefore, when the pyrolysis gas becomes an oil is condensed, then the oil obtained has no high Quality and is not for use as a fuel suitable considering air pollution. Especially in the thermal decomposition of polyethylene the pyrolysis gas mixture often solidifies into a wax at room temperature, the large amounts of heavy-boiling Contains components.

On the other hand, the plastic material in one closed reaction system thermally decomposes, then rises the pressure in the system spontaneously when implementing under Generation of the pyrolysis gas from the plastic material. At the same time the molecular movements are activated and the Thermal conductivity in the reaction system is increased. That I due to the pressure increase the boiling point of each Ingredients increased, the heavy-boiling or remain high molecular weight components easily in the liquid Phase, and therefore you can see the decomposition behavior among the  improve the above reaction conditions. The Decomposition efficiency is increased by reducing the pressure at the pyrolytic decomposition level increased. However, one causes too high pressure a high rate of formation of volatile Components that are too low-boiling to be at room temperature to condense, and this in turn causes one Reduce the yield of condensed oil. Based on these The fact is preferably a pressure gauge in the range of 98 to 980 kPa applied in the reaction system.

From the above it is understood that the effect of the pressure only the range of molecular weight distribution Components of the decomposition product towards the lower molecular weight shifts. Therefore it is not possible to avoid that the oil obtained by heavy boiling substances in the aforementioned thermal Decomposition process contaminated under increased pressure alone becomes. In other words, this means that the area of Molecular weight distribution in the oil obtained does not follow the aforementioned thermal decomposition method under increased Pressure alone can narrow. As a result, it is impossible to get a high quality oil.

On the other hand, it is possible to change the area of Molecular weight distribution of the components in the obtained Constrict oil by using a thermal decomposition process which includes the following stages: cooling the Pyrolysis gas to make a heavy-boiling fraction condense in such a way that the heavy-boiling Fraction of a low-boiling fraction of the pyrolysis gas can sever; and feeding the condensed heavy boiling fraction back to the decomposition stage. at Applying this procedure you can see the distribution area the components that make up the extracted oil, in Comparison to that in the pyrolysis gas product. However, that contains Pyrolysis gas product, which is caused by thermal decomposition normal pressure was obtained, large amounts of different  heavy-boiling ingredients, so these are not can be removed satisfactorily by the aforementioned cooling stage can. Furthermore, the yield of oil obtained is also this thermal decomposition method is reduced.

The present inventors have already in DE 42 43 063 A1 suggested that when you have the stage to carry out the pyrolysis of the plastic material under increased pressure a stage at which the pyrolysis gas is fractionated combined and only a fraction of the desired light boiling components wins, it is possible the quality and to drastically improve the oil yield, and it has also been shown that the oil obtained from the Plastic materials with hardly any high-boiling components Contains boiling points above 250 ° C. With this procedure become the heavy-boiling components of the pyrolytic decomposed product of the plastic material back into the pyrolytic decomposition stage and the thermal Decomposition is under the same pressure and at the same Repeat temperature until it reaches the desired light- boiling components are decomposed. In other words this means that the method described above is called equivalent to a method that can handle a variety of identical thermal decomposition levels at which the Decomposition reaction under the same reaction conditions is carried out includes.

The present invention is concerned with an improvement the aforementioned pyrolytic decomposition method such that you put them into practice on decomposition and recovery of plastic waste items can apply, and affects them a variety of thermal decomposition stages in which the Reaction conditions taking into account the improvement the quality of the oil product obtained. More accurate said the pyrolytic decomposition process according to the present invention, a first stage of decomposition which the plastic materials thermally at normal pressure  or reduced pressure to form a primary Decomposition product are decomposed, a separation stage, at which turns the primary decomposition product into a low-boiling Fraction and a heavy-boiling fraction is separated, and a second stage of decomposition, in which the separated heavy-boiling fraction is thermally decomposed in one Pressurized atmosphere forming a second Decomposition product. The desired low-boiling Component can be obtained by collecting the light boiling fraction and the second decomposition product. The second decomposition product can continue in a second Separation stage can be fractionated.

The method is characterized in that it is a variety of thermal decomposition levels at different Pressures are performed includes. The first thermal Decomposition stage is at normal pressure or reduced pressure performed, and this method is particularly effective for the treatment of plastic waste containing PVC resin. The Further procedural features are explained below.

In the thermal decomposition of polyolefin resins, such as Polyethylene and the like, the main chain is broken down statistically (at about 350 to 600 ° C) so that the fuel contains various components from gasoline to heavy oil. In contrast, a halogen-containing polymer such as PVC Resin, polyvinylidene chloride and the like in the thermal Decomposition in an atmosphere that does not contain oxygen, Bindings of the side chains as they are contained in PVC (at about 100 to 300 ° C, especially 250 to 350 ° C) before the Main chain breaks up, so that hydrogen halide or Hydrogen chloride gas is generated, causing the Decomposing device is destroyed. Attacked in particular Hydrogen chloride in a pressurized atmosphere quite significantly the device. Therefore it is necessary the pressurization of the atmosphere, the hydrogen chloride contains to avoid. PVC resin also contains  generally large amounts (i.e., about 30% by weight) of plasticizers, such as di (2-ethylhexyl) phthalate (DOP) and the like that with the hydrogen chloride gas under Formation of harmful organic chlorine compounds react which contaminate the oil product obtained. The Plasticizer can also be used in a decomposition product, e.g. B. Phthalic anhydride etc., during the pyrolytic Decomposition reaction can be changed, as in the the following reaction formula (1) is shown. The Phthalic anhydride itself sublimes and clogs it Piping system of the pyrolytic decomposition device and disrupt or interrupt the flow of the gas product.

Will the pyrolytic decomposition of the PVC resin in one Then pressurized atmosphere performed organic chlorine compounds easily from the plasticizer and the hydrogen chloride formed. This is because the Reaction system is generally a closed and neither the plasticizer nor the hydrogen chloride from the Reaction system can escape. It is impossible that Concentration of hydrogen chloride gas and plasticizer in the Reduce reaction system. As a result, the Plasticizer essential with the hydrogen chloride under Formation of harmful organic chlorine compounds during thermal decomposition.

In contrast, when the pyrolytic decomposition of the Plastic material containing PVC resin at reduced pressure or is carried out in an open reaction system which plasticizer contained in the PVC resin evaporates easily and can leave the reaction system before hydrogen chloride is formed or before the plasticizer with the  Hydrogen chloride reacts. So you can see the formation of organic chlorine compounds by reducing the pressure, in which the pyrolytic decomposition is carried out avoid. Because the concentrations of the plasticizer continue and the hydrogen chloride in the reaction system can be reduced can, the formation of organic chlorine compounds decreases from.

In the above case, the decomposition products contain Polyolefin resins hardly at normal or reduced pressure heavy-boiling hydrocarbon components. These difficult boiling components are rather evaporated and left the decomposition system because the pressure is low. Becomes as a result, the decomposition gas product in a cooler cooled, then a heavy-boiling fraction of the heavy-boiling components and is boiling fraction separated. At this time, the heavy boiling fraction collected no hydrogen chloride. After this separation stage, when the heavy-boiling components again thermally decomposed at elevated pressure, runs the decomposition and the crushing of the heavy-boiling Ingredients continue to decrease because of an atmosphere below Pressure causes an increase in the boiling temperature and a Shift in vapor-liquid equilibrium. At this No organic chlorine compound is formed and the Distribution of the constituents of the decomposition gas used in the aforementioned two-stage decomposition will be obtained noticeably narrower than with a single stage decomposition. Therefore can the product obtained by the aforementioned method use well as a fuel. Since the secondary continues Gas product obtained from the second decomposition stage does not contain hydrogen chloride, you can use the secondary Introduce gas product into a column with a catalyst to to reform the secondary gas product. With the double step It is also a decomposition process of the type described above easier to adjust the fuel oil so that it is the desired one contains low-boiling components compared to that  One-step decomposition process because of the reaction conditions changed once in the double stage decomposition process are intended to contain the heavy-boiling components of the primary decomposition product in the plastic raw material decompose.

In the subsequent cooling and separation stage as mentioned before is the plasticizer (DOP etc.) in general in the heavy-boiling fraction and is then boiling fuel components in the second decomposition stage, which is carried out under pressure decomposes.

The low-boiling fraction used in the separation stage is separated, and the secondary product can be put together be treated without organic chlorine compounds be generated. If the low-boiling fraction is low Amounts of the intended low-boiling components contains, then you can a suitable post-treatment subject and only treat the secondary product and collect.

As a result, it is with the aforementioned decomposition processes possible to form organic chlorine compounds reduce and silting up the tube system Avoid phthalic anhydride.

Becomes the first decomposition stage under normal pressure performed, it is possible to remove the hydrogen chloride and that evaporated plasticizers from the disintegrator to remove and quickly detach or treat before it can react. However, there are some other measures.

First, the plastic material becomes one Melting / kneading pretreatment at a temperature of 200 to Subjected to 400 ° C before pyrolytic decomposition, then the hydrogen chloride released from the plastic material. Therefore it is possible to form organic  Chlorine compounds during the pyrolytic Reduce decomposition. Beyond that it is possible the amount of alkali material that you add to the Plastic waste before the first decomposition there to decrease (the addition of the alkali material at the first Decomposition stage will be described later). Besides, because the plastic material in the first decomposition stage in molten state is introduced, the pyrolysis efficiency noticeably increased. If the plastic material with the kneaded alkaline material, then the chlorine is by the alkaline material included. Can as alkali material Alkali metal hydroxide compounds such as lithium hydroxide, Sodium hydroxide and potassium hydroxide and as Alkaline earth metal hydroxide compounds magnesium dihydroxide and Calcium dihydroxide and the like can be used.

Second, the first stage of decomposition is equivalent to one performed alkaline substance and preferably also from Water, then the generation of organic Chlorine compound and the anhydride compound in accordance with the saponification of the plasticizer, as in the the following reaction formula (2) is prevented become. Is the amount added to the plastic waste sufficient alkaline substance, then the Hydrogen chloride also neutralized and in the alkaline substance included.

It should be noted that it is quite complicated and in practice it is difficult to find the exact amount of the in the PVC resin containing plastic waste materials determine. As a result, there is always a small one Possibility back that hydrogen chloride and the plasticizer  one does not react due to the lack of alkali material sufficient mixing of the plastic with the Alkali material etc. However, the decomposition system will not pressurized, then they can from the Decomposition system escape and therefore the generation of organic chlorine compounds are reduced, and therefore it is useful the first stage of decomposition at normal pressure perform. It is preferred to use the plastic waste Water (either liquid or vapor water) for a slight saponification of the plasticizer with the mix alkaline material.

In the two-stage decomposition process described above becomes when the primary decomposition product from the first Decomposition under reduced pressure which the Contains plasticizer and hydrogen chloride gas, then cleaned with an alkali material, e.g. B. when the primary gaseous product is released using a shower aqueous alkaline liquid to the primary gaseous Product is washed, the plasticizer decomposes and by the alkaline material while cleaning the primary Gas product saponified and the hydrogen chloride is in one harmless salt transferred. As a result, they are out of the primary decomposition product in the form of a salt and a Soap removed.

The primary gaseous product will shower with a shower washed aqueous alkaline liquid, then that Hydrogen chloride gas and the plasticizer in the alkaline Liquid collected in the form of a salt and a soap. At the same time, the primary product is cooled and the heavily boiling components of the washed gaseous product are condensed into an oil so that the primary product itself into a low-boiling fraction and a heavy-boiling Fraction separates. However, the temperature of the primary tends Product to drop very sharply, so that the condense the intended constituents and  boiling fraction are included. Nevertheless, it is possible if you have the condensed fraction before the second Decomposition stage collects and heats to the intended one low-boiling component from the heavy-boiling fraction to evaporate the intended component from the heavy boiling fraction, the heavy-boiling components, the still further decomposes contains, separate. The remaining heavy-boiling ingredients will then be the Subsequent second decomposition stage subjected to elevated temperatures is carried out.

In the second thermal decomposition stage, the heavily boiling fraction continues pyrolytically under increased pressure decomposed. As previously described, the second one Decomposition stage of the present invention applied pressure set to a predetermined value suitable for to get an oil of the desired quality because that Molecular weight distribution of the pyrolysis product becomes one lower range with the increase in pressure in the Decomposition reaction system shifts. One intends for example a fairly light-boiling one to get fuel-like kerosene, then it is preferred, a pressure gauge in the range of 98 to 588 kPa in the pyrolytic decomposition system. The pyrolytic one is even more preferred Decomposition system pressure gauge to be applied in one area from 294 to 490 kPa. In the aforementioned preferred The heavy-boiling fraction is subjected to pressure conditions Temperature in the range of about 300 to 600 ° C heated. Will the Pressure within the aforementioned preferred range applied, then you can get an oil product in the desired Quality, e.g. As kerosene, gasoline, etc., with a yield of obtained about 50 to 80 wt .-%.

That obtained in the second thermal decomposition stage secondary pyrolysis gas product is in a collection stage introduced. At this stage, the pyrolysis gas is reduced to one  predetermined temperature, e.g. B. room temperature, using a cooler to condense the intended easy boiling ingredients cooled. The cooler also does one Fractionation. As a result, the secondary product is in separate a fuel and a gaseous fraction. The Cooling temperature is in depending on the type of oil product last appropriately changed.

It is also possible to provide a feedback stage like this is described in DE 42 43 063 A1, the proportionately heavy-boiling components of the secondary Decomposition gas product before the collection stage in another Fractionation and separation stage are condensed and then in the second thermal decomposition stage be returned to where they are further cracked. The relatively low-boiling ingredients that the pass through the second separation stage, are brought to a temperature in the Near room temperature at the collection stage to win cooled where they liquefy and as oil that spills out composes relatively low-boiling components, be won. Through this measure, the received Fuel oil is of higher quality because it is easier-boiling Contains ingredients. Because the constituents of the faction, the can pass through the second separation stage, according to the Cooling level and the fractionation temperature in the second Change separation level, the cooling and fractionation temperature in appropriately set. In this context, you can the details for the thermal conditions and the Printing conditions can be found in DE 42 43 063 A1.

A device for performing the aforementioned double-stage decomposition process can be operated effectively by building the device so that it Transport devices for the forced transport of the gaseous Decomposition products from the low pressure decomposition boiler in the subsequent unit by means of kinetic energy of the Decomposition gas in a high pressure decomposition boiler  is formed. It is with the transport facilities possible, a combination of a turbo blower, which is on Outlet of the high-pressure decomposition vessel is located with a Blower fan that cooperatively connects to the turbo blower is to use. With this combination the Turbo fan through the kinetic energy of the in the High pressure decomposition vessel generated gas after Turbo principle. Then the torque on the blower fan transmitted, which is connected to the turbo blower. As The result is the decomposition gas product from the Low pressure decomposition vessel forced into the subsequent one Blown unit and the internal pressure in the Low pressure decomposition is continuously reduced.

With reference to the drawings, special Examples of the above-mentioned device and the double stage decomposition process shown below.

Fig. 1 is a schematic representation of an embodiment of the pyrolytic decomposition device for the double-stage decomposition process according to the invention.

In Fig. 1, the pyrolytic decomposition device ( 1 ) comprises a vacuum decomposition vessel ( 2 ), an alkali cleaning vessel ( 3 ), a pressurized decomposition vessel ( 4 ) and a cooler ( 5 ). The vacuum decomposition vessel ( 2 ) is connected to the alkali cleaning vessel ( 3 ) by a line ( 6 ), and the alkali cleaning vessel ( 3 ) is connected to a line ( 7 ) by the pressurized decomposition vessel ( 4 ). In addition, the pressurized decomposition vessel ( 4 ) and the cooler ( 5 ) are connected by means of a line ( 8 ). A blower ( 9 ) is provided at the inlet ( 6 ) for introducing the decomposition gas containing the high-boiling constituents from the vacuum decomposition vessel ( 2 ) into the alkali cleaning vessel ( 3 ). On the other hand, a turbo blower ( 10 ) is provided at the inlet ( 8 ) in order to lead the decomposition gas out of the pressurized decomposition vessel ( 4 ). The blower ( 9 ) is connected to the turbo blower ( 10 ) so that the axis S of the blower ( 9 ) is coaxial with that of the turbo blower ( 10 ). Alternatively, the blower ( 9 ) can be cooperatively connected to the turbo blower ( 10 ). There is also an aqueous alkaline solution in the alkaline cleaning vessel. ( 3 ) and is circulated by means of a pump ( 11 ) through a pipe which connects the bottom part of the cleaning vessel ( 3 ) and a valve ( 12 ) which connects inside the alkali cleaning vessel ( 3 ). The aqueous alkaline solution which is supplied at the valve ( 12 ) is sprayed onto the decomposition gas which is supplied from the vacuum decomposition vessel ( 2 ) of the alkali cleaning vessel ( 3 ). The neutral salt precipitated at the bottom of the alkali cleaning vessel ( 3 ) is suitably discharged through an outlet ( 13 ) which is connected to the bottom part of the alkali cleaning vessel ( 3 ). The upper part of the alkali cleaning vessel ( 3 ) is connected to an exhaust gas treatment device ( 14 ).

In operating the pyrolytic decomposition with the above decomposer, a mixture of broken pieces of different waste plastics including PVC resin and polyolefin resin is introduced into the vacuum decomposition vessel ( 2 ) and heated. When the temperature is raised, vapors are generated from the plasticizer contained in the PVC resin, hydrogen chloride and decomposition gas containing the high-boiling components from the polyolefin resin. These are introduced into the alkali cleaning vessel ( 3 ) by means of the blower ( 9 ), separately or in the form of a gas mixture. The hydrogen chloride is removed from the mixed gas in the form of a harmless salt by spraying with the aqueous alkaline solution. The softening agent is also saponified by the aqueous alkaline solution. The remaining mixed gas is largely liquefied into an oil.

The liquefied oil is introduced into the pressurized decomposition vessel ( 4 ) by the pump ( 15 ) and decomposed into a light product gas. This light product gas flows into the cooler ( 5 ) while the flow of the product gas rotates the turbo blower ( 10 ). The product gas in the cooler ( 5 ) is condensed and obtained as a low-boiling fuel oil.

If the operating conditions in the device ( 1 ) are set as follows, the oil product obtained contains mainly aliphatic and aromatic hydrocarbons having 4 to 18 carbon atoms and has no detectable organic chlorine compounds according to a gas chromatographic analysis of the oil product obtained.

Example of the operating conditions

Internal atmosphere in the vacuum decomposition vessel (

2

): -98 to 0 kPa pressure gauge
Internal atmosphere of the pressurized decomposition vessel (

4

): 294 to 490 kPa pressure gauge
Temperature in the vacuum decomposition vessel (

2

) and im with pressure applied decomposition vessel (

4

): 350 to 600 ° C
Temperature in the cooler (

5

): 250 to 300 ° C.

In contrast, if the device ( 1 ) is operated with the turbo blower ( 19 ), then the blower ( 9 ) can be omitted and the oil product obtained contains mainly hydrocarbons with 4 to 32 carbon atoms, although organic chlorine compounds can be detected to a small extent.

Taking into account the above, it is understood that the Pressure in the primary decomposition stage is higher than Normal pressure and that the content of organic chlorine compound in the product obtained increases. In addition, if the Pressure becomes lower at the second stage of decomposition, i. H. if the pressure is outside a suitable pressure range, the  is higher than the normal pressure, then the Decomposition reaction is insufficient and it remains Heavy oil components back.

Another embodiment of the pyrolytic decomposer for double-stage decomposition will be described with reference to Fig. 2, which is a schematic illustration of the decomposer.

The decomposer ( 16 ) comprises an extruder ( 17 ), a first reaction furnace ( 18 ), an additive container ( 19 ), a first cooler ( 20 ), a vapor-liquid separator ( 21 ), a second reaction furnace ( 22 ) and one second cooler ( 23 ). In order to apply a predetermined pressure to the second reaction furnace ( 22 ), a pressure pump ( 24 ) and a shut-off valve ( 25 ) are connected between the first cooler ( 20 ) and the second reaction furnace ( 22 ), and a pressure control valve ( 26 ) is between the second Reaction furnace ( 22 ) and the second cooler ( 23 ) are provided.

In the above decomposition device ( 16 ), the alkali cleaning kettle for purifying the primary decomposition gas for removing hydrogen chloride, which was provided in the first embodiment of the double-stage decomposition device, is omitted and the plastic waste material containing PVC resin is thermally heated in the presence of alkali decomposed.

In operation of the decomposition device ( 16 ), the plastic waste material is first melted and kneaded while heating to a temperature below 300 ° C. The melted plastic after the melting / kneading stage is transferred to the first reaction furnace ( 18 ). Then alkali material and water present in the additive container ( 19 ) are put on the molten plastic on the upper part of the first decomposition furnace ( 18 ), and the plastic material is at a temperature of about 350 to 600 ° C in the presence of water and heated and decomposed alkali material. The pyrolytic decomposition gas flows from the first reaction furnace ( 18 ) into the first cooler ( 20 ). In the first cooler ( 20 ), the pyrolytic decomposition gas is cooled at a temperature of 250 to 300 ° C. and part of the decomposition gas, which is composed of relatively low-boiling constituents, is liquefied and separated from the decomposition gas. The other part of the decomposition gas is not liquefied in the first cooler ( 20 ) and is transferred to the second cooler ( 23 ).

The liquefied part is fed into the second reaction furnace ( 22 ) through the shut-off valve ( 25 ) by means of the pressure pump ( 24 ). In the second reaction furnace ( 22 ), the liquefied part is subjected to pyrolytic decomposition again, that is to say that it is thermally decomposed at a temperature of about 350 to 600 ° C. in an atmosphere of 98 to 980 kPa. The second decomposition gas is transferred to the second cooler ( 23 ) through the pressure control valve ( 26 ) and is cooled to room temperature together with the gas part which has not been liquefied in the first cooler ( 20 ), and thereby a condensed fuel containing the desired light boiling ingredient collected. The fuel obtained is received in a receptacle ( 27 ) and the remaining gas fraction that was not condensed in the second cooler ( 23 ) is cleaned with an alkaline material in an exhaust gas treatment unit ( 28 ) and burned with a burner for the aftertreatment. The afterburned gas is released from the device ( 16 ).

When operating the decomposition device ( 16 ), the melt / kneading pretreatment is carried out in addition to the basic operation of the two-stage decomposition method. A conventional extruder can be used as the extruder ( 17 ) used for the melt / kneading pretreatment. The melt / kneading pretreatment effectively improves the pyrolytic decomposition efficiency. However, if this causes an increase in the production of hydrogen chloride gas from PVC resin, the primary decomposition gas in the first reaction furnace ( 18 ) may be contaminated by hydrogen chloride gas generated in the extruder ( 17 ). In this case, it is desirable to provide an alkali cleaning device, such as a liquid alkali spray for cleaning the primary decomposition gas inside the first reaction furnace ( 18 ), or adding and kneading an alkaline material to the plastic waste to be melted to capture the hydrogen chloride gas. Alternatively, forced ventilation can be provided in the extruder in order to remove the hydrogen chloride gas formed from the kneaded plastic material. For this purpose, the first decomposition stage, carried out at reduced pressure, is used, in which hydrogen chloride is effectively removed. In the second embodiment, the generation of organic chlorine compounds by hydrogen chloride is prevented in three ways, namely by the extruder, the addition of alkaline material and the first cooler, which is connected directly to the first reaction furnace.

After the pyrolytic decomposition of the Plastic waste material remains a black one Residual product in the pyrolytic decomposition vessel and adheres to the inner surface of the vessel. Of these Residue products made from various plastic materials form those made of polyolefinic material such as polyethylene, Polypropylene and the like are soft lumps that are easy can scrape out of the decomposition vessel and the one fine powder such as soot powder. On the other hand the residual product from PVC resin forms a hard mass like Coal coke, so it is very difficult to find satisfactory Carry out the residue product in a short time Remove scraping and the like. So if a Plastic material to be pyrolytically decomposed PVC resin contains, increases operational efficiency at a repeated Application of the disintegrator noticeably. About that  In addition, workers' health is at risk if the Workers scrape out the residue product for a long time have to.

The aforementioned problems can be solved by doing that Decomposition vessel of the pyrolytic decomposition device so changed that there is a double pot structure.

An embodiment of a modified decomposition vessel with the double pot structure is shown in FIG. 3.

The modified decomposition vessel ( 29 ) in Fig. 3 comprises an outer vessel ( 30 ) and an inner vessel ( 31 ). The outer vessel ( 30 ) is heated directly by means of a heating device and the inner vessel ( 31 ) can be separated from the outer vessel ( 30 ). The inner vessel ( 31 ), which receives the plastic waste material to be pyrolytically decomposed, is inserted into the outer vessel ( 30 ). After pyrolytic decomposition of the plastic waste material, the inner vessel ( 31 ) with the residue product from the decomposed plastic material is taken out of the outer vessel ( 30 ), and another part of the plastic waste material is in another inner vessel ( 31 ) and is into the outer one Vessel ( 30 ) used to carry out the next decomposition treatment. During the next decomposition treatment, the removed inner vessel ( 31 ) is subjected to a scraping treatment to remove the residue product.

In the construction described above, the outer vessel ( 30 ) is said to have a heat transfer part, ie, a recessed part ( 32 ) to improve the heat transfer efficiency between the outer vessel ( 30 ) and the inner vessel ( 31 ). If the inner vessel ( 31 ) is inserted into the recess part ( 32 ) and the outer and inner vessels ( 30 and 31 ) are heated to a temperature for pyrolytic decomposition, then the surfaces of the recessed part ( 32 ) and the inner vessel ( 31 ) and contact each other, and the heat is transferred directly from the recessed part ( 32 ) to the inner vessel ( 31 ). As a result, the heat is easily transferred. The recessed part ( 32 ) is constructed so that the heat is suitably transferred from the lower part to the upper part of the inner vessel ( 31 ).

According to the present invention, the details of one Embodiment for the pyrolytic decomposer with a decomposition vessel with a double pot structure underneath Described with reference to the drawings.

As shown in FIGS. 3 and 4, the pyrolytic decomposer ( 33 ) comprises an outer vessel ( 30 ) and an inner vessel ( 31 ). The inner vessel ( 31 ) in this embodiment has a tubular side wall ( 34 ) and a circular bottom part ( 35 ). The inner vessel ( 31 ) also has a hook or handle (not shown) for carrying the inner vessel ( 31 ). The inner vessel ( 31 ) is carried using a jib crane ( 36 ). The outer vessel ( 30 ) has a hatch ( 37 ) which is opened and closed at the upper end of the outer vessel ( 30 ) for introducing the inner vessel ( 31 ) into the outer vessel ( 30 ). As shown in Fig. 4, the cylindrical recessed part ( 32 ) is formed at the center of a flat plate ( 38 ) of the outer vessel ( 30 ) and the inner vessel ( 31 ) is inserted into the recessed part ( 32 ). A combustion chamber ( 39 ) is integrally formed on the bottom of the outer vessel ( 30 ) and is separated from the outer vessel ( 30 ) by the plate ( 38 ). The outer vessel ( 30 ) including the plate ( 38 ) is heated by means of a burner ( 40 ) installed in the combustion chamber ( 39 ). During heating, the heat is transferred from the plate ( 38 ) to the inner vessel ( 31 ) through the portion of the inner vessel ( 31 ) that is in contact with the recessed portion ( 32 ). The plate ( 38 ) in Fig. 4 has a plurality of drill holes on the part surrounding the recessed part ( 32 ). If a burner is used as a heater as described above, the boreholes must be connected to the lines so that the hot gas coming from the burner flows into the lines so that heat is released to the atmosphere that the inner vessel ( 31 ) in Surrounds inside the outer vessel ( 30 ). In contrast, when using an electric heater or the like that works fire-free, the boreholes can be left as provided in the drawing.

Furthermore, a heat sensor of the inner vessel (31) (41 a) for measuring the internal temperature through the hatch (37) into the interior of the inner vessel (31), which is located in the outer vessel (30), and a heat sensor (41 b) for measuring the internal temperature of the outer vessel ( 30 ) penetrates through the side wall of the outer vessel ( 30 ) into the interior of the outer vessel ( 30 ). The heat meters ( 41 a, 41 b) are electrically connected to a control operator ( 42 ) for the controlled application of the heat by the burner ( 40 ) using the temperatures measured by the heat sensors ( 41 a, 41 b) as the variables to be controlled.

The outer vessel ( 30 ) is connected to the exterior of the outer vessel ( 30 ) by a line ( 43 ) for supplying the thermal decomposition gas generated in the pyrolytic decomposition of the waste plastic material, and a flow meter ( 44 ) is in the line ( 43 ) is provided to measure the flow of the liquid or gas product, as shown in FIG . The line ( 43 ) also has a control valve ( 45 ) for regulating the flow from the line ( 43 ), and the control valve ( 45 ) is operated by means of a flow control operator ( 46 ) using the current supplied with the flow meter ( 44 ) variable to be controlled is measured, controlled. In addition, mounted a pressure gauge (47) on the outer vessel (30) for measuring the pressure in the gas in the outer vessel (30).

The line ( 43 ) is also connected to an exhaust gas treatment system ( 50 ) via a first cooler ( 48 ) and the second cooler ( 49 ). The first cooler ( 48 ) and the second cooler ( 49 ) are connected to the storage part for a high-boiling fraction ( 51 ) and a storage tank ( 52 ) for a low-boiling fraction. On the other hand, the combustion chamber ( 39 ) is connected to an exhaust gas treatment device ( 53 ) for treating the combustion gas discharged from the burner ( 40 ).

According to the construction given above, this will be Waste plastic material treated in the following manner.

First, for successful handling of the halogen-containing plastic, an alkaline material such as sodium hydroxide and the like is preferably added to the broken and flowable pieces or grains of the plastic waste material P as an accelerator to accelerate the elimination of halogen from the halogen-containing plastic to obtain a mixture of the waste plastic material and the alkaline material. The mixture is poured into the inner vessel ( 31 ) and the inner vessel ( 31 ) is then placed on the outer vessel ( 30 ) by means of the lifting crane ( 36 ). When the hatch ( 37 ) is opened, the inner vessel ( 31 ) with the plastic waste mixture is placed in the recessed part ( 32 ). The burner ( 40 ) is then lit to heat the plate ( 38 ). During the heating, the heat is transferred from the plate ( 38 ) to the inner vessel ( 31 ) from the part of the inner vessel ( 31 ) which is in contact with the recessed part ( 32 ) in the plate ( 38 ), so that the plastic material P is heated. In the case of continuous heating, a gas product containing fuel components is generated by thermal decomposition of the plastic waste material and filled into the outer vessel ( 30 ), where the property modification of the gas product due to the dry distillation is accelerated.

The temperature of the plastic waste material to be decomposed is measured with the heat sensor ( 41 a), and the combustion on the burner ( 40 ) is set in accordance with the detected temperature so that the internal temperature in the inner vessel ( 31 ) is preferably in a range from 400 to 500 ° C is set. The gas containing the gaseous fuel components flows in the tube system ( 43 ), while the flow of the gas is suitably adjusted by means of the control valve ( 45 ). For example, the opening and / or closing of the control valve ( 45 ) is carried out in such cases when the pressure on the inside of the outer vessel ( 30 ) suddenly changes, or the like. The gas product then reaches the first cooler ( 48 ), in which the gas product is cooled and condensed, so that a fraction consisting mainly of the heavy oil constituents is liquefied and separated from the remaining gas product. The liquefied fraction is stored in the heavy-boiling fraction storage tank ( 51 ). The remaining gas product is further cooled in the second cooler ( 49 ) and a further fraction, which mainly contains low-boiling components such as kerosene and the like, is condensed and separated off. The condensed second fraction is stored in a low-boiling fraction storage tank ( 52 ). The other fraction of the gas product which has not been liquefied is fed to an exhaust gas treatment system ( 50 ) and treated in such a way that it can be discharged without danger.

When the pyrolytic decomposition of the plastic waste material is complete, the burner ( 40 ) is turned off to stop heating and the outer vessel ( 30 ) is cooled to or near normal temperature. The completion of the decomposition reaction can be seen from the phenomenon that the temperature inside the inner vessel ( 31 ) increases, etc. Alternatively, the decomposition measure can be stopped when the amount of the fuel product obtained reaches a stoichiometric amount obtained from the initial amount of the waste plastic material is calculated. After the outer vessel ( 30 ) has cooled down, the hatch ( 37 ) is opened and the inner vessel ( 31 ) with the crane ( 36 ) is removed from the outer vessel ( 30 ). The decomposition residue left in the inner vessel ( 31 ) is removed with a scraper device ( 58 ) with a rotatable drive shaft ( 57 ) and the inner vessel ( 31 ) is cleaned. During the scraping and cleaning of the inner vessel ( 31 ), another part of the plastic waste mixture is subjected to the pyrolytic decomposition using another inner vessel. Since the location and the respective conditions for cleaning the inner vessel ( 31 ) can be changed as required, it is possible to select them in such a way that there is no damage to the health of the workers. If an oil fraction remains in the decomposition residue, the decomposition residue can be used as a solid fuel.

As shown in Fig. 4, the decomposition device described above is constructed so that the product obtained in the pyrolytic decomposition can be used for combustion in the burner ( 40 ) by using a line ( 59 ) for supplying the fuel product to the burner ( 40 ) provides. The work of inserting the plastic waste material into the inner vessel ( 31 ) and scraping off the decomposition residue can be done at a place away from the outer vessel ( 30 ), and the inner vessel ( 31 ) can be used for after-treatment with a truck and the like be transported.

In the decomposition device described above, the diameter d of the inner vessel ( 31 ) and the diameter D of the recessed part ( 32 ) of the plate ( 38 ) are determined as shown in Fig. 5, so that a small space between the outer Circumferential surface of the inner vessel ( 31 ) and the inner circumferential surface of the recessed part ( 32 ) and the plate ( 38 ) is at normal temperature. The materials for the inner vessel ( 31 ) and the recessed part ( 32 ) are chosen so that the degree of thermal expansion of the material of the inner vessel ( 31 ) is slightly larger than the plate ( 38 ). By this measure, the inner vessel ( 31 ) can be easily inserted into the recessed part ( 32 ) at normal temperature, and the circumference of the inner vessel ( 31 ) in the heat is in close contact with the circumference of the recessed part ( 32 ) through the Thermal expansion of the material. As a result, the heat conduction to the inner vessel ( 31 ) can be improved. For example, if the inner vessel ( 31 ) is made of austenitic stainless steel and the plate ( 38 ) is made of carbon steel, then in combination the thermal expansion of the inner vessel ( 31 ) is greater than that of the recessed part ( 32 ), and thereby suitably fits each other. If the materials are selected in a suitable manner as previously indicated, then the inner vessel ( 31 ) and the recessed part ( 32 ) are designed such that the diameter ratio d / D corresponds to the equation: 0.7 <d / D ≦ 0.98 (If d or D in a single embodiment does not have a constant value, then an average value is taken for the area in which the inner vessel ( 31 ) comes into contact with the recessed part ( 32 )). If the diameter ratio d / D is equal to or less than 0.98, then the insertion of the inner vessel ( 31 ) into the recess ( 51 b) can easily be accomplished at normal temperature. However, if the diameter ratio is not larger than 0.7, it is difficult to achieve proper heat conduction.

During the pyrolytic decomposition, the plastic material expands due to the heat and its height in the inner vessel ( 31 ) is increased noticeably, in particular because bubbles are also generated in the course of the decomposition reaction. As a result, the level of the molten plastic material increases 1.2 to 1.5 times compared to the initial state, and in some cases it expands two or more times. Therefore, it is preferable to limit the amount of the plastic waste material introduced into the inner vessel ( 31 ) so that the upper level of the introduced plastic material is 0.5 to 0.85 times the height or depth of the inner vessel ( 31 ) , In addition, when the heat acts directly on the upper part of the inner vessel ( 31 ), the plastic material tends to expand upward and then overflows from the inner vessel ( 31 ). For this reason, it is preferred to provide the heat transfer part only at the lower end of the inner vessel ( 31 ). In consideration of the foregoing, the height of the inner vessel ( 31 ) in the axial direction is appropriately selected so that it is in the range of about 1.2 times to twice the depth of the recess part ( 32 ).

By building the heat transfer part in the aforementioned manner, the heat from the outer vessel ( 30 ) can be transferred directly to the inner vessel ( 31 ) without being dependent on heat transfer through the air. Therefore, the energy can be supplied to the inner vessel ( 31 ) accordingly, so that the plastic waste material is heated quickly, and thereby the operation is improved.

In the pyrolytic decomposition process for obtaining fuel oil from plastic waste material of the aforementioned type, the efficiency of heat transfer is a very important factor in obtaining the fuel product of high quality and consistency. However, the heat transfer efficiency changes with the ratio of the area of the contact surface of the heat transfer member with respect to the volume of the plastic waste material to be pyrolytically decomposed. As a result, if the above area / volume ratio is appropriately set, sufficient heat transfer efficiency is achieved and the decomposition measure can be carried out effectively. If the volume has a cylindrical shape with a radius of 30 cm, the preferred area / volume ratio is in a range of about 0.04 to 0.9 cm ² / cm ³ . On the other hand, the height of the cylindrical volume is preferably used in a range from r / 10 to 10 r (r: radius), taking into account the processability and the reduction in the decomposition residue.

In the aforementioned construction, the use of the Decomposition vessel with the double pot structure and the provision of a heat transfer part the time lost for the Cleaning the decomposition vessel is necessary too reduce and improve the efficiency of thermal energy. Therefore, the total operating time in the event that the Decomposition measure in a batch operated Decomposition vessel repeated, shortened and the Throughput capacity is increased.

The double pot structure has another advantage, namely that the amount of decomposition residue is reduced. If one uses a single-type decomposition vessel, one becomes significant amount of black residue formed in the jar especially near the edges of the vessel. This is because that the vessel is heated directly and that the Waste plastic is not heated evenly. Compared this is when you have a decomposition vessel from Double pot type with a heat transfer part, as before has been used, and the plastic inside Vessel is heated indirectly, heat transfer improved more evenly and the amount of black Residue is reduced.

Fig. 6 shows a further embodiment of the decomposition vessel of the double pot structure. In this decomposition vessel ( 29 a) an all-purpose metal drum ( 31 a) with a side wall ( 34 a) and a bottom ( 35 ) is used as the inner vessel. In this embodiment, a gap between the side wall ( 34 a) of the metal drum ( 31 a) and the bore surface of the recessed part ( 32 ) and the plate ( 38 a) can occur even when heat is applied, and thereby the heat transfer efficiency between the outer vessel ( 30 a) and the inner vessel ( 31 a) disturbed. In order to solve this problem, a filler F with a low value for the specific heat, in particular a metal medium such as steel wool and the like or a liquid medium such as heavy oil or the like, is filled into the intermediate space and forms a heat transfer part. The introduction of a highly conductive filler forms a heat transfer part that is in close contact with the inner vessel. From the description of this embodiment, it is clear that even if the diameter ratio d / D in the double pot decomposition vessel ( 50 ) in the above-mentioned embodiment is less than 0.7 and the conformability is low, it can be improved by using a filler can.

Fig. 7 shows a third embodiment of the decomposition vessel with a double pot structure. In the decomposition vessel (29 b) of this third embodiment, the inner vessel (31 b) of the double cup-type a truncated conical shape. As a result, the corresponding recess part ( 32 a) of the plate ( 38 b) of the outer vessel ( 30 b) has a similar truncated conical shape. According to the structure of the inner vessel ( 31 b) and the recessed part ( 32 a) with a tapered shape, the tapered surfaces act as a guide for the inner vessel ( 31 b) so that it has the correct position during the adjustment, the side wall ( 34 b) slides into the recessed part ( 32 a). Therefore, one can simply insert the inner vessel ( 31 b) into the recessed part ( 32 a), even if the position of the inner vessel ( 31 b) is slightly different from that of the recessed part ( 32 a). As a result, precise operational control for the transport and insertion of the inner vessel ( 31 b) into the recessed part ( 32 a) is not necessary. Therefore, the insertion of the inner vessel ( 31 b) in the recessed part ( 32 a) is very easy. Even if the dimensions of the inner vessel ( 31 b) and the recessed part ( 32 a) are different due to the production process, heat transfer during heating can be completely achieved and damage to the decomposition vessel ( 29 b) due to the internal vessel being too large ( 31 b) can be prevented. In addition, the inner vessel ( 31 b) sits smoothly in the recess part ( 32 a). Because further opens the conical inner vessel well (31 b), can be the residue product easily from the inner vessel (31 b) to remove. The conical inner vessel ( 31 b) has the further advantage that the inner vessel can be stored and transported well. A plurality of the conical inner vessels ( 31 b) can be stacked in order to save space and during transport, as is shown in FIG. 8.

FIG. 9 shows a decomposition system in which the double-pot structure of the decomposition vessel ( 29 b) from FIG. 7 is incorporated into the basic structure of the device of FIG. 2. More specifically, the first decomposition vessel ( 29 b), in which the decomposition is carried out in an atmosphere of normal pressure or reduced pressure, has an outer vessel ( 30 a) and an inner vessel ( 31 b), and the second decomposition vessel ( 22 ), at which the reaction atmosphere is pressurized is also of the double pot structure.

In the decomposition system of Fig. 9, the pressure inside the first decomposition vessel ( 29 b) is monitored by means of a pressure sensor ( 60 ), a vacuum pump ( 61 ) and a control unit ( 62 ) in order to adjust the pressure to normal pressure or reduced pressure in a predetermined manner adjust. The liquid part ( 54 a) first condenses in the cooler ( 20 ) and is pumped ( 24 ) to the inner vessel ( 31 b) of the pressurized decomposition vessel ( 29 b), which has a control valve ( 25 ) and one Pressure control valve ( 26 ) is equipped so that the liquid part is further decomposed and forms a second decomposition gas product. The low-boiling fuel component ( 55 a) is condensed in the second cooler ( 23 ) and received in the receiving container ( 27 ).

The part of the second decomposition gas product that is not liquefied in the second cooler ( 23 ) is treated in the exhaust gas treatment unit ( 28 ).

An example of system monitoring, setting the System conditions for the production of kerosene as the end product is given below.

First decomposition vessel 29 b

P: normal pressure, T: 300 to 650 ° C, preferably 300 to 500 ° C

Second decomposition vessel 22

P: 98 to 980 kPa pressure gauge, preferably about 392 kPa, T: 400 to 500 ° C

First cooler 20

T: 200 to 300 ° C, preferably 200 to 250 ° C

Second cooler 23

T: 100 to 150 ° C, preferably about 150 ° C

In the case described above, the other gas part, which is not condensed in the second cooler ( 23 ), can contain more low-boiling fuel components, such as gasoline. Therefore, a third cooler, which cools the gas part to normal temperature in order to obtain the gasoline content, can be incorporated into the exhaust gas treatment unit ( 28 ). After the gasoline component is condensed, the remainder is subjected to a neutralization treatment to neutralize hydrogen chloride gas and an afterburning to burn the hydrocarbon in the gas portion.

Examples

With reference to the drawings and the results of Studies are the preferred below Embodiments of the method and the device for pyrolytic decomposition of plastic materials according to the described the present invention.

example 1

Using the pyrolytic decomposer ( 16 ) of Fig. 2, 100 parts by weight of the plastic waste mixture was charged into the extruder ( 17 ). In the extruder ( 17 ) the plastic waste mixture was heated from normal temperature to 300 ° C and melted and kneaded. There is an elimination reaction of hydrogen chloride from the PVC resin in the plastic waste mixture. The molten plastic mixture was then poured continuously into the first reaction furnace ( 18 ). To the molten plastic mixture, 5 parts by weight of sodium hydroxide and 1 part by weight of water were added from the additive container ( 19 ), and the whole was heated to 420 to 450 ° C. A pyrolytic decomposition reaction of the molten polyolefin plastic and the decomposition of plasticizers that are present in the plastic mixture take place with the formation of decomposition gas.

The decomposition gas was introduced into the first cooler ( 20 ) and cooled to a temperature of 250 to 300 ° C, whereby part of the decomposition gas liquefied. The liquefied fraction was separated from the remaining gas in the vapor / liquid separator ( 21 ) and passed by means of a pressure pump ( 24 ) into a second reaction furnace ( 22 ), which was equipped with a control valve ( 25 ) and a pressure control valve ( 26 ) , The remaining gas part was introduced into the second cooler ( 23 ).

The liquefied part was heated again to a temperature of 420 to 450 ° C and further pyrolytically decomposed. During this operation, the pressure inside the second reaction furnace ( 22 ) was increased by evaporating the liquefied part and kept at 392 kPa pressure gauge by means of the pressure control valve ( 26 ). The pyrolytically decomposed part was passed from the second reaction furnace ( 22 ) into the second cooler ( 23 ) so that the secondary decomposed part with the remaining gas portion from the first decomposed product was cooled to a temperature near normal temperature and finished to one liquid product condensed. The finished liquid product was taken up in a warm-up container. On the other hand, the remaining gas portion, which was not liquefied in the second cooler ( 23 ), was introduced into the exhaust gas treatment unit ( 28 ), where the gas portion was washed with alkali material, then burned in a burner and finally released into the environment.

As a result of this procedure, 20 parts by weight of hydrogen chloride were discharged from the extruder ( 16 ). In the first reaction furnace, 70 parts by weight of decomposition gas was generated and 15 parts by weight of a soft residue composed of carbonaceous material, which remained at the bottom of the first reaction furnace ( 18 ) and was removed from an opening therein. Of the 70 parts by weight of the above-mentioned decomposition gas, a part of about 20 parts by weight was liquefied in the first cooler ( 20 ), which was then further decomposed in the second reaction furnace. In the receptacle ( 27 ), 60 parts by weight of oil and 1 part by weight of water were obtained, and 10 parts by weight of gas were discharged through the exhaust gas treatment unit ( 28 ).

According to the GC-MS analysis of the oil obtained found that the oil obtained from Hydrocarbon compounds with 4 to 18 carbon atoms composed, and no organic chlorine-containing Connection 09278 00070 552 001000280000000200012000285910916700040 0002004446964 00004 09159ng proven.  

Example 2

The extruder ( 17 ) was removed from the decomposer ( 16 ) of Fig. 2, and 100 parts by weight of the plastic waste mixture, 30 parts by weight of sodium hydroxide and 5 parts by weight of water were charged into the first reaction furnace ( 18 ). Then, the decomposition procedure of Example 1 was repeated under the same reaction conditions, except that the melting and kneading were not carried out.

After completing the above measure, 50 parts by weight of the decomposition residue remained in the first reaction furnace ( 39 ) and the residue contained salt because the hydrogen chloride gas formed from the PVC resin was neutralized with the alkali material in the above process. 60 parts by weight of oil and 15 parts by weight of water were obtained from the container ( 27 ). In addition, 10 parts by weight of gas was discharged through the exhaust gas treatment unit ( 28 ).

GC-MS analysis of the oil obtained showed that the oil obtained from hydrocarbon compounds with 4 to 18 carbon atoms and there was none organic chlorine-containing compound detected.

Example 3

The pyrolytic decomposer ( 16 ) of Fig. 2 was used and the decomposition measures of Example 1 were repeated under the same reaction conditions, but with no sodium hydroxide and no water added.

As a result of these measures, 20 parts by weight of hydrogen chloride were discharged from the extruder ( 17 ). 70 parts by weight of decomposition gas was generated in the first reaction furnace, and the rest (10 parts by weight) was taken out from the outlet at the bottom of the first reaction furnace ( 18 ) in the form of a hard residue composed of carbonaceous material. Of the 70 parts by weight of the above decomposition gas, a part of about 30 parts by weight was liquefied in the first cooler ( 20 ), and this was then further decomposed in the second reaction furnace ( 22 ). 60 parts by weight of oil were obtained in the container ( 27 ) and 10 parts by weight of gas were released to the outside.

GC-MS analysis of the oil obtained showed that the oil obtained from hydrocarbon compounds with 4 to 18 carbon atoms and there was none Detected compound with organic chlorine.

Example 4

The first cooler ( 20 ) was removed from the decomposer ( 37 ) of Fig. 2, and then the decomposition procedure of Example 3 was repeated under the same conditions as there, except that the condensation in the first cooler ( 20 ) was omitted ,

As a result of these measures, 20 parts by weight of hydrogen chloride were discharged into the extruder ( 17 ). In the first reaction furnace, 70 parts by weight of decomposition gas was generated, and the rest (10 parts by weight) was taken out at the bottom outlet of the first reaction furnace ( 18 ) as a hard residue of a carbonaceous material. Then 70 parts by weight of the above decomposition gas, which was not condensed, was directly introduced into the second cooler ( 23 ). Most of the decomposition gas condensed, but 15 parts by weight of the decomposition gas remained in the uncondensed gas form. A part of 10 parts by weight of the condensed part was not liquefied but solidified. Although there was no complete silting in the second cooler ( 23 ), some of the decomposition product adhered to the inner wall of the cooler. It can be assumed that this sticking results in a deterioration in the condensation efficiency and an increase in the uncondensed gas part. 45 parts by weight of an oil were obtained in the container ( 27 ).

GC-MS analysis of the oil obtained showed that none organic chlorine-containing compounds can be detected could. However, the oil expired Hydrocarbon compounds with 4 to 32 carbon atoms together and contained non-decomposed plasticizers.

The above result shows that the omission of the second thermal decomposition stage in a pressurized Atmosphere gives a heavier-boiling oil product.

Example 5

The extruder ( 17 ) and the first cooler ( 20 ) were omitted from the decomposer ( 16 ) of Fig. 2 and the decomposition procedure of Example 4 was repeated under the same conditions except that the melt / kneading process in the extruder ( 17 ) and condensation in the first cooler ( 20 ) ceased.

As a result of this procedure, 80 parts by weight of decomposition gas was generated in the first reaction furnace and the rest (20 parts by weight) was taken out at the bottom of the first reaction furnace ( 18 ) at an outlet in the form of a foamy carbon residue. Then 80 parts by weight of the above decomposition gas was not condensed but introduced directly into the second cooler ( 23 ). Half of the decomposition gas liquefied but 30 parts by weight of the decomposition gas remained in the uncondensed gas form. A part of 10 parts by weight of the condensed portion was not liquefied but solidified. 40 parts by weight of oil were obtained in the container ( 27 ).

GC-MS analysis of the oil obtained showed that 2% organic chlorine-containing compounds can be detected could. The oil has been identified as olefinic Hydrocarbon compounds with 4 to 32 carbon atoms and contained undecomposed plasticizer.

Example 6 (comparative example)

The extruder ( 17 ) and the first cooler ( 20 ) were omitted from the decomposer ( 16 ) of Fig. 2 and a pressure control valve was connected to the first reaction furnace. Then, a decomposition as in Example 4 was repeated under the same reaction conditions, except that the melting / kneading process in the extruder ( 17 ) and the condensing in the first cooler ( 20 ) continued and the first thermal decomposition at an increased pressure of 392 kPa pressure gauge was carried out.

As a result of this procedure, 80 parts by weight of decomposition gas was generated in the first reaction furnace and the rest (20 parts by weight) at the bottom of the first reaction furnace ( 18 ) were taken out at an outlet in the form of a foamy carbon residue. Then 80 parts by weight of the above decomposition gas was not condensed, but was introduced directly into the second cooler ( 23 ). 55 parts by weight of the decomposition gas liquefied from this part, but 25 parts by weight of the decomposition gas remained in a non-condensed gaseous state. The condensed oil was collected in the container ( 27 ).

By GC-MS analysis of the oil obtained, 1.5% were organic chlorine-containing compounds, based on the total weight, demonstrated. The oil has been identified as olefinic Hydrocarbon compounds with 4 to 18 carbon atoms.  

From the results of Example 6 it can be seen that organic chlorine compounds essential for decomposition PVC resin can be produced under pressure. Furthermore, the Results of Examples 1 to 4 show that the formation of organic chlorine compounds can be avoided by hydrogen chloride is removed or neutralized. It is important in preventing the formation of organic Chlorine compounds to build up the decomposition system so that no reaction between the plasticizer and Hydrogen chloride runs out. As shown in this description there are some measures you can take to prevent this.

The previous description shows that with the Method and device for pyrolytic decomposition high quality fuel oil according to the present invention easy and efficient production from plastic waste material can. The present invention therefore has a great one practical meaning.

In the present invention, even if that Plastic waste material contains PVC resin, the oil obtained of high quality that contains little or no chlorine. As a result, PVC resin has to be made Plastic waste materials that are pyrolytically decomposed can no longer remove. And that's why it's possible to practical and economic advantages in recycling of plastic materials according to the present invention achieve.

The invention is not shown in accordance with the Embodiments limited and numerous modifications can be done without departing from the scope of the invention, such as it is reproduced in the claims, deviates.

Claims (34)

1. A method for pyrolytically decomposing plastic waste, comprising:
a first thermal decomposition stage for thermally decomposing the plastic to form a primary decomposition product in the form of a gas and a decomposition residue;
a separation step for separating the primary decomposition product into a first fraction, which may contain a desired low-boiling component, and a second fraction, which is heavier-boiling than the first fraction, by condensation of the second fraction;
a second thermal decomposition stage for thermally decomposing the separated second fraction to form a second decomposition product containing the desired low-boiling component in gaseous form; and
a collecting stage for collecting the desired low-boiling constituent from the first fraction and the second decomposition product, characterized in that one carries out the first thermal decomposition stage at normal pressure or reduced pressure, and the second thermal decomposition stage at a pressure different from and higher than the first decomposition stage performed as normal pressure. 2. Pyrolytic decomposition process according to claim 1, the plastic is a halogen-containing plastic contains. 3. A pyrolytic decomposition method according to claim 1, which the plastic contains polyvinyl chloride.   4. A pyrolytic decomposition process according to claim 2, characterized in that it further comprises:
an alkaline treatment step for treating the primary decomposition product with an alkali material for removing an acidic halogen-containing substance contained in the primary decomposition product from the primary decomposition product. 5. A pyrolytic decomposition process according to claim 4, characterized in that the alkali material in the Alkali treatment step in the form of a spray is supplied aqueous liquid containing a alkaline substance that is selected from Alkali metal hydroxide compounds and Alkaline earth metal hydroxide compounds, the Alkali metal hydroxide compounds lithium hydroxide, Sodium hydroxide and potassium hydroxide and the Alkaline earth metal hydroxide compounds Magnesium dihydroxide and are calcium dihydroxide. 6. A pyrolytic decomposition process according to claim 4, characterized in that the alkali treatment step comprises the following steps:
Supplying an alkaline substance to the plastic before the first thermal decomposition stage so that the primary decomposition product formed in the first thermal decomposition stage comes into contact with the alkaline substance, the alkaline substance being selected from alkali metal hydroxide compounds and alkaline earth metal hydroxide compounds, the alkali metal hydroxide compounds Are lithium hydroxide, sodium hydroxide and potassium hydroxide and the alkaline earth metal hydroxide compounds are magnesium dihydroxide and calcium dihydroxide. 7. The pyrolytic decomposition process according to claim 4, characterized in that it continues the supply of Water to the plastic before the first thermal Decomposition stage includes. 8. The pyrolytic decomposition process according to claim 1, characterized in that the pressure gauge at first thermal decomposition level equal to or greater than -98 kPa. 9. pyrolytic decomposition process according to claim 1, characterized in that in the first thermal Decomposition stage of the plastic to a temperature in the Range of 300 to 650 ° C is heated. 10. The pyrolytic decomposition process according to claim 1, characterized in that in the first thermal Decomposition stage of the plastic to a temperature in the Range of 300 to 500 ° C is heated. 11. A pyrolytic decomposition process according to claim 1, characterized in that the pressure gauge at second thermal decomposition stage in the range of Is 98 to 980 kPa. 12. The pyrolytic decomposition process according to claim 1, characterized in that the pressure gauge at second thermal decomposition stage approximately 392 kPa is. 13. A pyrolytic decomposition process according to claim 1, characterized in that the primary Decomposition product is separated off at the separation stage, by reducing the primary decomposition product to a Cools temperature from 200 to 300 ° C.   14. A pyrolytic decomposition process according to claim 1. characterized in that the primary Decomposition product is separated off at the separation stage, by reducing the primary decomposition product to a Cools temperature from 200 to 250 ° C. 15. A pyrolytic decomposition process according to claim 1, in which the desired low-boiling component in the Collection level is collected by the first fraction and the secondary decomposition product at one Temperature from 100 to 150 ° C cools and condenses. 16. The pyrolytic decomposition process according to claim 1, characterized in that the desired light boiling component is collected at the collection stage, by separating the first fraction and the secondary Decomposition product at a temperature of approximately 150 ° C cools and condenses. 17. A pyrolytic decomposition process according to claim 15, characterized in that it further comprises:
a recovery stage for recovering a portion of the secondary decomposition product that was not condensed at the collection stage by continuing to cool the portion to approximately room temperature. 18. A pyrolytic decomposition process according to claim 1. characterized in that it is before the first thermal decomposition stage a stage in the form of a Kneading stage for heating and kneading the plastic Material includes. 19. A pyrolytic decomposition process according to claim 18. characterized in that the plastic at the Kneading stage to a temperature in the range of 100 to 300 ° C is heated.   20. The pyrolytic decomposition process according to claim 18, where the plastic at the kneading stage on a Temperature in the range of 250 to 300 ° C is heated. 21. A pyrolytic decomposition process according to claim 1, characterized in that it comprises:
a first thermal decomposition step for thermally decomposing the plastic in the presence of an alkali material in an atmosphere of normal pressure to form a primary decomposition product in the form of a gas and a decomposition residue;
a first cooling stage for cooling the primary decomposition product to a cooling temperature at which the primary decomposition product separates into a first fraction, which may contain a desired low-boiling component, and a second fraction, which is heavier-boiling than the first fraction, by condensation of the second fraction;
a second thermal decomposition step for thermally decomposing the second fraction of the primary decomposition product in an atmosphere pressurized to a predetermined pressure to form a second decomposition product containing the desired low-boiling component in gaseous form; and
a second cooling stage for cooling the first fraction and the second decomposition product to a second cooling temperature, which is lower than the first cooling temperature, for condensing a fraction containing the desired low-boiling component. 22. A device for the pyrolytic decomposition of plastic, comprising:
a first thermal decomposition device for thermally decomposing the plastic to form a primary decomposition product in gaseous form and a decomposition residue;
a separator for separating the primary decomposition product into a first fraction, which may contain a desired low-boiling ingredient, and a second fraction, which is higher-boiling than the first fraction, by condensing the second fraction;
a second thermal decomposition device for thermally decomposing the second fraction to form a second decomposition product containing the desired low-boiling component in gaseous form; and
a collecting container for collecting the desired low-boiling constituent from the first fraction and the second by condensing the same, characterized in that the first thermal decomposer is one for thermally decomposing plastic under normal pressure or reduced pressure, and the second thermal decomposer is one for thermal decomposition of the second fraction under a pressure different from the first thermal decomposition device and higher than normal pressure. 23. A pyrolytic decomposition device according to claim 22, characterized in that it further comprises:
an alkali treatment device for treating the primary decomposition product with an alkali material for removing an acidic halogen-containing substance formed from the halogen-containing polymer contained in the plastic from the primary decomposition product. 24. A pyrolytic decomposition device according to claim 23, characterized in that the alkali treatment device includes:
a spray device for supplying the alkali material in the form of a spray from an aqueous liquid containing an alkaline substance selected from alkali metal hydroxide compounds and alkaline earth metal hydroxide compounds, the alkali metal hydroxide compounds being lithium hydroxide, sodium hydroxide and potassium hydroxide and the alkaline earth metal hydroxide compounds being magnesium dihydroxide and calcium. 25. A pyrolytic decomposition device according to claim 23, characterized in that the alkali treatment device comprises:
an alkali feeder for feeding an alkaline substance to the plastic so that the primary decomposition product formed in the first thermal decomposer can come into contact with the alkaline substance, the alkaline substance being selected from alkali metal hydroxide compounds and alkaline earth metal hydroxide compounds, wherein the alkali metal hydroxide compounds are lithium hydroxide, sodium hydroxide and potassium hydroxide and the alkaline earth metal hydroxide compounds are magnesium dihydroxide and calcium dihydroxide. 26. A pyrolytic decomposition device according to claim 23. characterized in that it continues to be a Water supply device for supplying water the plastic includes. 27. A pyrolytic decomposition device according to claim 22, characterized in that it further comprises:
a condenser for cooling and condensing a part which is part of the secondary decomposition product but which is not condensed in the storage tank. 28. A pyrolytic decomposition device according to claim 22, characterized in that it further comprises:
a kneader for heating and kneading the plastic material for feeding the kneaded plastic into the first thermal decomposer. 29. Apparatus for the pyrolytic decomposition of plastic containing polyvinyl chloride, comprising:
a first thermal decomposition device for thermally decomposing the plastic to form a primary decomposition product in gaseous form and a decomposition residue;
a separator for separating the primary decomposition product into a first fraction, which may contain a desired low-boiling ingredient, and a second fraction, which is higher-boiling than the first fraction, by condensing the second fraction;
a second thermal decomposition device for thermally decomposing the second fraction to form a secondary decomposition product containing the desired low-boiling component in gas form; and
a collector for collecting the desired low-boiling ingredient from the first fraction and the secondary decomposition product by condensing the same;
wherein each of the first and second thermal decomposition means comprises an inner vessel, an outer vessel that can removably receive the inner vessel, and a heater for heating the outer vessel, in which the outer vessel has a heat transfer member that fits the inner one Contacted vessel, when the outer vessel and the inner vessel are heated, to improve the heat transfer between the outer vessel and the inner vessel, characterized in that the first thermal decomposition device is one for the thermal decomposition of plastic under normal pressure or reduced pressure, and the second thermal decomposition device is one for thermally decomposing the second fraction under a pressure different from the first thermal decomposition device and higher than normal pressure. 30. A pyrolytic decomposer according to claim 29, characterized in that it further comprises:
an alkali treatment device for treating the primary decomposition product with an alkaline material for removing an acidic substance from the primary decomposition product. 31. A pyrolytic decomposition device according to claim 30. characterized in that the Alkali treatment device one Alkaline feeder includes for feeding the alkaline material to the plastic. 32. Pyrolytic decomposition device according to one of the Claims 22 to 31, characterized in that the inner vessel is a cylindrical container and the Heat transfer part with a boundary wall includes cylindrical inner bore, the Inner diameter of the inner hole of the formula 0.7 <d / D ≦ 0.98, where d is the outer Diameter of the inner vessel and D is the Diameter of the inner bore of the boundary wall. 33. Pyrolytic decomposition device according to one of the Claims 22 to 31, characterized in that the Heat transfer part has a truncated conical shape and the inner vessel has a corresponding bottom part with a truncated conical shape.   34. Pyrolytic decomposition device according to one of the Claims 22 to 31, characterized in that the outer vessel has a surrounding part that extends from the Boundary wall extends and that the surrounding part has a penetration hole.