TECHNICAL FIELD

The invention relates to a processing apparatus and a processing method for processing waste material comprising thermoplastic material, particularly for processing crushed waste material.

BACKGROUND ART

Currently, communal solid waste is typically subjected to preliminary manual or machine sorting. The residual waste material unsuited for further recycling is disposed of at landfills or is burned; both processes having harmful effects on the environment. To overcome this problem, a number of approaches have been developed for processing waste.

In US 2010/0091794 A1 an apparatus and method for processing waste having plastic content is disclosed. In the course of the method the plastic content of the waste forms a coating on the other part of the loaded waste, with various objects being manufactured by extrusion from the material thus produced. According to the document the material to be processed is first sterilized in an autoclave, followed by producing from it the end product ready for extrusion by heating to a high temperature in a melting apparatus. According to the document, heat generated in the melting apparatus can be recovered. The idea of recovering waste heat appears in the document in a generic way, the manner of recovery, disadvantageously, is not detailed in the document. In the document, at the sterilization and heating steps, economic efficiency does not come up as an aspect: sterilization is performed in a large autoclave, and in the heating step very high temperatures are applied. A similar apparatus is disclosed in US 2011/0272858 A1 . According to this approach, waste is dried before or after particulation, the duration of the drying process being 24 hours or even longer. The apparatus according to US 2011/0272858 A1 is also applied for processing waste material that has very low or nonexistent plastic content. ln US 4,968,463 a waste processing method is disclosed. After drying the waste material, preliminary heating is performed, during which the material is softened, which is followed by mixing at high temperature, during which step a material suitable for extrusion is prepared. In US 5,624,620 a method for producing sheet goods and other products is disclosed wherein a mixture comprising non-purified thermoplastic material and other, non-thermoplastic materials is applied as starting material. The starting material is first cut to appropriate size, which is followed by removing its metal content. The material is then introduced into a mixing apparatus, where it is heated to a temperature of approximately 230 °C.

In US 2007/0272775 A1 a waste-processing method is disclosed wherein the end product is produced by heating waste having plastic content in a mixer, and thereby melting the plastic.

In Hungarian patent application P 1 1 00068 a method for processing waste is disclosed wherein waste plastic is recycled as a mixture with ground basalt and limestone for producing various products.

In CN 102423909 A a method for processing waste is disclosed wherein - though larger pieces are removed from it - the waste material is essentially processed without sorting and purification. Further waste processing methods are disclosed in GB 2 291 419 A, in Hungarian patent application P 10 00230, and in US 6,253,527.

In US 5,495,948 an ash melting furnace and the operating method thereof are disclosed. According to the document the heat carried by the gases generated in the ash melting furnace is used for drying the ash so as to separate larger objects from dry ash. After the drying has been completed, drying air is led away (discharged) through an outlet opening.

In light of the known approaches, and due to the fact that waste processing, with special regard to its efficient realization and environmental considerations, is becoming a more and more important issue, the need has arisen for a waste processing method and apparatus that is capable of processing waste material having an appropriate thermoplastic material content as recyclable material in a more efficient way than known approaches, and preferably in a manner that is more beneficial from the aspect of energy consumption compared to known approaches. A common disadvantage of various known approaches is that using these waste material that has already gone through a preliminary sorting process may be processed, and thus comprises already only certain specific components. In light of this fact a need related to processing has also arisen, applying which communal waste can be processed substantially without sorting. DESCRIPTION OF THE INVENTION

The primary object of the invention is to provide a method and an apparatus for processing waste which are free from disadvantages of prior art approaches to the greatest possible extent.

A further object of the invention is to provide a method and an apparatus for processing waste using which waste material having an appropriate thermoplastic material content (applied as base material) can be processed as recycled material in a more efficient manner based on the appropriate utilization of resources (preferably in a more beneficial way than known approaches), and with a lower environmental impact compared to known approaches. The objects of the invention can be achieved by the processing apparatus according to claim 1 and by the processing method according to claim 14. Preferred embodiments of the invention are defined in the dependent claims.

The processing apparatus and processing method according to the invention can be applied for making recycled products from communal solid waste comprising thermoplastic material. The apparatus and method according to the invention are applied for making a liquid melt (fluidic mass) from the waste material (the waste material fed into the apparatus gets molten as passing through the subassemblies, and its plastic content forms an encompassing coating on other particles, resulting in a fluidic melt (liquiform mass)), which can be further shaped into an end product utilizing a press-machine having a capacity between 20 and 500 tonnes, or applying an extrusion machine. The end product may be by way of example a shaped article (e.g. a noise barrier panel, a paving block, a pot, etc.)

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below by way of example with reference to the following drawings, where

Fig. 1 is a schematic drawing in side view illustrating the apparatus for processing waste material according to the invention,

Fig. 2 is a schematic sectional drawing illustrating the input side (first end) of the drying apparatus applied in an embodiment of the apparatus according to the invention,

Fig. 3 is a schematic sectional drawing of the output side (second end) of the drying apparatus of Fig. 2,

Fig. 4 is a sectional drawing of a fan connected to the output side illustrated in Fig. 3,

Fig. 5 is a schematic drawing illustrating the output side of a further embodiment of the drying apparatus,

Fig. 6 is a sectional drawing of the fan connected to the output side illustrated in Fig. 5,

Fig. 7 is a schematic sectional drawing illustrating the interconnection of the drying apparatus and the screw conveyor in the embodiment of Fig. 2,

Fig. 8 is a schematic sectional drawing illustrating, in the embodiment of Fig. 2, the top portion of the screw conveyor, the melting apparatus, and the sterilizing apparatus,

Fig. 9 is a schematic top sectional drawing of the melting apparatus illustrated in Fig. 8, and

Fig. 10 is a schematic sectional drawing illustrating the heat exchanger connected to the flue of the melting apparatus, and draining of the air.

MODES FOR CARRYING OUT THE INVENTION

An embodiment of the processing apparatus according to the invention adapted for processing waste material comprising thermoplastic material, particularly for processing crushed waste material is illustrated in Fig. 1 . In this embodiment, the processing apparatus comprises a drying apparatus 12 adapted for drying the waste material by means of an air flow. Forwarding blades are arranged in the elongated internal space of the drying apparatus 12 on a shaft connecting a first end 11 and a second end 13, the forwarding blades being adapted for mixing the waste material and moving it towards the second end 13. The forwarding blades are suitable for mixing the waste material and for moving it towards the second end 13 when rotated in both of their rotating directions.

The processing apparatus further comprises a melting apparatus 16 adapted for melting the waste material that has been subjected to drying by the drying apparatus 12. The melting apparatus 16 is capable of melting the waste material 15 at a temperature of at least 100 °C.

The processing apparatus according to the invention further comprises a sterilizing apparatus adapted for applying sterilizing heat treatment of the waste material having been subjected to melting by the melting apparatus 16 at a temperature of at least 240 °C. In addition to the above mentioned drying 12 and melting apparatuses 16 the processing apparatus also comprises a heat recovery channel 24 extending between the drying apparatus 12 and the melting apparatus 16, connected with one channel end thereof to an air channel of a heat exchanger being in heat transfer relationship with a flue 28, the air channel having an air intake opening (air inlet opening), the flue 28 being arranged on the melting apparatus 16 and being adapted for draining heat-carrying fluid generated during melting, and the heat recovery channel 24 being connected with the other channel end thereof to the internal space of the drying apparatus 12 through an air feed device arranged at the second end; and a draining channel 26 (releasing, discharging channel) adapted for draining of fluid generated in the drying apparatus 12 during drying, connected to the drying apparatus 12 at the first end 1 , and also being connected to the flue 28.

In the embodiment illustrated in Fig. 1 the air channel of the heat exchanger is connected to a first flue 21 , and the draining channel 26 is connected to a second flue 29, i.e. the draining channel 26 is connected to the flue 28 above the heat exchanger. This arrangement is advantageous because the draining channel 26 can be easily connected, and also because the fluid transported in the draining channel 26 typically does not carry a significant amount of heat. However, the draining channel can also be connected to other parts of the flue, such as to the first flue, under the air channel of the heat exchanger. In this latter case the residual heat carried by the fluid in the draining channel can be recovered and utilized for contributing to heating. Since, however, there is no significant amount of heat present in the draining channel; the draining channel is connected to the flue above the heat exchanger such that it does not by any means have a cooling effect. The manner of transporting the waste material between the subassemblies in the order specified according to the invention, the temperatures applied in the subassemblies, and the application of channels adapted for utilizing waste heat for drying, and for appropriate draining of the fluids generated in the drying apparatus during drying (which typically comprise harmful substances) allows for processing the waste material more efficiently compared to known approaches, and also allows for collecting (accumulating) harmful substances generated during the process. Thanks to the configuration of the processing apparatus, harmful substances generated during operation are treated in a closed system.

In the figures illustrating the internal space of the drying apparatus 12 (e.g. Fig. 2) the waste material 15 being processed is also shown. The flue is adapted for draining (discharging, leading away) vapour, gases and steam, and at the same time it prevents the build-up of overpressure in the melting apparatus 16 (preferably made of steel).

In the embodiment according to Fig. 1 the first end 1 1 of the drying apparatus 12 is in the left of the drawing, while the second end 13 thereof is on the right. In Fig. 1 it is shown that a forwarding channel 14 is connected to the drying apparatus 12 through a passage element 30 at the second end 13 of the drying apparatus 12. The forwarding channel 14 comprises a screw conveyor 92 (forwarding screw) that is shown in Fig. 7 and will be explained in relation to that figure. As shown in Fig. 1 , the drying apparatus 12 is connected to the melting apparatus 16 by means of the forwarding channel 14. In this embodiment, therefore, the apparatus according to the invention comprises a forwarding channel 14 comprising a screw conveyor 92, the forwarding channel 14 being adapted for transporting the waste material from the drying apparatus 12 to the melting apparatus 16, and being connected with one channel end thereof to the drying apparatus 12 through a first passage element 30 at the second end 13 of the drying apparatus 12, and being connected with the other channel end thereof to the melting apparatus 16.

In other embodiments of the processing apparatus the waste material subjected to drying may be transferred from the drying apparatus to the melting apparatus in another way. If, e.g., the apparatuses are arranged below each other, the material may simply be made to fall into the melting apparatus from the drying apparatus, or in case of other arrangements other ways of transfer are conceivable.

Screw-forwarding expels air from the waste material in the forwarding channel 14 to a certain extent, which also contributes to preventing spontaneous ignition in the melting apparatus 16. The internal space of the melting apparatus 16 is not in direct contact with open air as its top portion is closed off; hot steam, gases are discharged through the flue, the outside air cannot enter the apparatus through it, which also secures that spontaneous ignition is prevented.

In the present embodiment the melting apparatus 16 is arranged vertically and has a cylindric shape with a conically narrowing bottom portion. The conically narrowing portion of the melting apparatus 16 leads to a sterilizing apparatus 18. As shown in Fig. 1 the inlet of the processing apparatus is an inlet opening 10 arranged on the drying apparatus 12, and its outlet is an outlet opening 20 arranged at the downstream end of the sterilizing apparatus 18. The waste material - which at this stage has a mass-like consistency - is discharged through the outlet opening 20 by the help of an automatically controlled shutter or flap. As shown in Fig. 1 , a flue 28 comprising a heat exchanger is connected to the top portion of the melting apparatus 16. The internal configuration of the flue 28 (comprising a flue housing 22) is illustrated in Fig. 8, and thus the internal configuration will be explained later, in relation to Fig. 8.

As shown in Fig. 1 , the heat recovery channel 24 is connected to the top portion of the air channel of the heat exchanger through a control valve 48. As shown in Fig. 1 , the heat recovery channel 24 leads into a fan housing 50 arranged at the second end of the drying apparatus 12. The manner of connection of the fan housing 50 to the drying apparatus 12 and the internal space of the drying apparatus 12 are illustrated in Figs. 3 and 4 in an embodiment, and in Figs. 5 and 6 in another embodiment.

As shown in Fig. 1 , the draining channel 26 is arranged at the first end 1 1 of the drying apparatus 12. The other end of the draining channel 26 is connected to the portion of the flue 28 that is situated above the heat exchanger. Such a manner of connection of the draining channel 26 is advantageous because that way it can be connected upstream of a filter arrangement 63. That way, the filter arrangement 63 is capable of filtering out those substances which are proceeding from the heat exchanger 22 arrangement directly upwards with the hot air, and in addition it can also filter out substances arriving through the draining channel 26. Thereby the accumulated harmful substances can be filtered out and the environmental impact of the processing apparatus can be controlled. The end of the draining channel 26 that is situated near the first end 1 of the drying apparatus 12 can be opened by means of a flap automation unit 56 adapted for releasing a closing element 58. The draining channel 26 is adapted for draining of the fluids - such as humid, hot air - generated therein from the drying apparatus 12. The fluids can be carried off applying air flow coming from an air feed device arranged at the other end of the drying apparatus 12, or by other auxiliary means.

As shown in Fig. 1 , a humidity sensor 60 is connected to the internal space of the drying apparatus 12. By way of example, the humidity sensor 60 can be a vapour measuring sensor. The moisture content - i.e., by way of example, humidity - is measured in the internal space of the drying apparatus 12 by means of this humidity sensor 60. The (sufficiently dried) waste material can leave the drying apparatus 12 through the passage element 30. The processing apparatus can be therefore operated in such a way that the actual moisture content of the waste material comprised in the drying apparatus 12 is checked by means of the humidity sensor 60, and in case this moisture content is sufficiently low, the waste material is enabled to proceed forward in the processing apparatus. Proceeding forward of the waste material is performed as follows. If the moisture content is sufficiently low, a closing element 34 is opened applying a closing element motor 32, i.e. the closing element 34 is removed from the opening of the passage element 30. As illustrated in Fig. 2, the waste material is moved from the first end 1 1 towards the second end 13 in the internal space of the drying apparatus 12 by means of forwarding blades 80. Accordingly, utilizing the forwarding blades 80 the waste material can be made to enter the passage element 30, from which it is conveyed to the melting apparatus 16 by a screw conveyor arranged in the forwarding channel 14. In Fig. 1 a motor 36 of the screw conveyor is also shown.

In the melting apparatus 16 the waste material is subjected to warming, heating, while being preferably stirred by blades rotated by a motor 38. The current condition of the waste material comprised in the melting apparatus 16 can be inspected through an inspection window 40, while the pressure inside the melting apparatus 16 can be monitored by means of a pressure sensor 42. The waste material comprised in the melting apparatus 16 has to reach a sufficiently high temperature in order that it can proceed to the sterilizing apparatus 18. By opening an unfoldable (openable) closure element 66 arranged at the bottom portion of the melting apparatus 16 the waste material comprised in the melting apparatus 16 can be drained to the sterilizing apparatus 18. In order that the heating process is carried out in the melting apparatus 16 in an efficient manner, the melting apparatus 16 is provided with heat insulation 70.

According to the invention, in the melting apparatus 16 the waste material is heated to a temperature of at least 100°C. Our experiments indicated that by heating the waste material comprising thermoplastic material to such a temperature the waste material melts sufficiently to produce a molten mass which can be forwarded to the sterilizing apparatus 18. It is this heating process that is essentially responsible for providing a suitable end product. There exist such known approaches wherein very high temperatures (as high as 200-300°C) are applied in a mixing apparatus performing a function similar to the functionality of the present melting apparatus. In these approaches the large amount of material comprised in the mixing apparatus is heated to such high temperatures. In contrast to that, in the melting apparatus of the processing apparatus according to the invention the lowest possible temperature is applied, with really high temperatures (allowing for sterilization) preferably applied only in the sterilizing apparatus that has reduced cross sectional area compared to the melting apparatus.

The sterilizing apparatus 18 arranged downstream of the melting apparatus 16 is therefore responsible for the sterilization of the waste material rather than for providing an appropriate-consistency material. According to the relevant standards, such as the relevant Hungarian standard, the material leaving the apparatus has to be heated to a temperature of at least 240°C in order that it can be considered as sterilized, i.e. standards-compliant from a microbiological aspect. The desired temperature of 240°C in the sterilizing apparatus 18 is preferably adjusted applying a temperature controller, and is monitored continuously using automatic heat sensors; these are controlled by central control means. Thereby, non-sterilized material (material not sterilized due to uncertain or variable temperatures) can be prevented from leaving the apparatus. Preferably, a maximum temperature of 300°C is applied in the sterilizing apparatus 18.

Compared to the melting apparatus 16 the sterilizing apparatus 18 preferably has a much lower cross sectional area, and thus the sufficiently molten material introduced therein can be heated with much lower energy input at such a low cross section. It is sufficient to heat the mass flow passing through the sterilizing apparatus 18 at only one point to such a temperature in order that it can be considered sterilized.

In the processing apparatus according to the invention the ratio of the cross sectional area of the internal space of the melting apparatus receiving waste material and the cross sectional area of the internal space of the sterilizing apparatus receiving waste material is between 10:1 and 25: 1. Because both the melting apparatus and the sterilizing apparatus preferably have cylindrical internal space, their volume is essentially governed by these ratios. According to the invention, therefore, the waste material is heated in the melting apparatus 16 preferably in a greater volume in order to obtain a softened melt (mass), which softened melt is then subjected to sterilization by introducing it in the sterilizing apparatus 18, therein passing it through a pipe of appropriate length, preferably 1-1 .5 m, and providing a temperature of at least 240°C along the pipe, preferably in at least one cross section of the pipe it is subjected to a sterilizing treatment, before the material is discharged through the outlet opening 20.

The material discharged through the outlet opening 20 is subjected to further processing (e.g. pressing, extrusion, rolling). In the sterilizing apparatus 18 heating of the waste material to a sufficiently high temperature is preferably performed by heater units 68 arranged about the outer periphery of a pipe that forms a part of the sterilizing apparatus 18. Such heater units 68 are capable of heating the material to be sterilized to an appropriate temperature through the pipe wall.

As shown in Fig. 1 , in this embodiment the processing apparatus stands on legs 72, 74, and 76. The drying apparatus 12 is supported by legs 72. The forwarding channel 14 is supported on the ground by a leg 74. The melting apparatus 16 is supported and elevated to appropriate height by legs 76 (such that the sterilizing apparatus 18 may be arranged under it). As shown in the figure, with such an arrangement the height of the individual apparatuses can be adjusted arbitrarily. Thanks to that, an arrangement illustrated in Fig. 1 can be devised wherein the material processed by the drying apparatus 12 is discharged from the drying apparatus downwards - in a gravitational manner - and then the waste material is lifted by a screw arranged in the forwarding channel 14 to a height sufficient for it to enter the melting apparatus 16.

In a manner similar to the drying apparatus 12, the waste material processed by the melting apparatus 16 is discharged therefrom also in a gravitational manner. Thereby the waste material is introduced in the sterilizing apparatus 18 in a gravitational manner, and then, after proceeding through the pipe of the sterilizing apparatus 18 it can be discharged through the outlet opening 20 also in a gravitational manner. It is accordingly seen that in this embodiment it is expedient to arrange the forwarding channel 14 comprising the screw conveyor so that the waste material - which is discharged from the drying apparatus 12 in a gravitational manner - can be lifted to a height sufficient for feeding into the melting apparatus 16. When the melting apparatus 16 is combined with the sterilizing apparatus 18 as illustrated in the figure, on even ground the assembly cannot be installed at a lower height than indicated. As shown in the figure, the heat recovery channel 24 and the draining channel 26 are both arranged above the subassemblies. However, these channels can be routed substantially arbitrarily because they are adapted for conveying air and other gases. The flue 28 is of course arranged above the melting apparatus 16, with the gases and vapours being discharged through it in an upward direction.

In Fig. 2 a detail of Fig. 1 is illustrated, showing the internal structure of the drying apparatus 12. Fig. 2 also illustrates how the waste material 15 is fed, showing that the waste material 15 is introduced into the internal space of the drying apparatus 12 through an inlet opening 10. As shown in Fig. 2 a motor 54, adapted for rotating a shaft 78, is connected to the drying apparatus 12. There are forwarding blades 80 arranged on the shaft 78. The forwarding blades 80 are adapted for conveying the waste material in the direction of end 13 - i.e., in the figure, to the right. The forwarding blades 80 perform mixing and loosening of the waste material during the operation of the drying apparatus 12.

The air applied for the drying operation is fed to the internal space of the drying apparatus 12 through perforated channels 82. These perforated channels 82 will be described in relation to Fig. 3. As shown in Fig. 2, closing elements 59 are arranged at the bottom of the inlet opening 10. The closing elements 59 open, preferably in a computer-controlled manner when the waste material is fed into the apparatus (but they may be operated by other means, by way of example they can be opened under the weight of the waste material). It is also shown in the figure that a closing element 58 controlled by the flap automation unit 56 is configured such that the unit 56 is capable of opening the closing element 58 by rotating it about a shaft. The inlet of the draining channel 26 is then freed up. In a similar manner, the draining channel 26 can also be closed.

A buffer tank can also be installed upstream of the drying apparatus 12 for storing waste material or crushed waste material. This is especially advantageous because our experience indicates that drying is the second longest-duration process applied herein, and thus it is preferable to have the material to be processed ready at hand. Because the melting apparatus has the longest cycle time, all subassemblies are adjusted to match its capacity.

In Fig. 3 the side of the drying apparatus 12 proximate the second end 13 is illustrated. As shown in the figure, the fan housing 50 is connected to the second end 13. In this embodiment, therefore, the air feed device is a fan arranged in the fan housing 50. Fig. 3 also shows fan blades 86 as well as a motor 52 adapted for driving the fan. For better comprehension of the operation of the perforated channels 82, Figs. 3 and 4 are explained together. As shown also in Fig. 3, in the fan housing 50 channel introductory portions 88 branching off from the fan. These channel introductory portions 88 convey air delivered by the fan into the perforated channels 82, which air arrives through the heat recovery channel 24 and is. In Fig. 3 it is indicated by an arrow shown in the heat recovery channel 24 that the incoming air is coming from that direction (i.e. from the direction of the melting apparatus 16). This arrow is also shown in Fig. 4. The fan typically delivers air at a temperature of 60-70 °C, while the forwarding blades 80 - which in the closed state of the drying apparatus 12 also perform mixing - slowly move the waste material. The forwarding blades 80 are configured such that they can slowly mix the waste material while it is dried, and that they can convey the material towards the passage element 30 when the drying apparatus 12 is being emptied. The perforations of the perforated channels 82 are oriented differently in order to prevent turbulences inside the drying apparatus 12. The number of the applied perforated channels 82, as well as the number of perforations each channel has, depend on the capacity of the drying apparatus.

In this embodiment, therefore, the processing apparatus comprises at least one perforated channel 82 adapted for distributing in the internal space of the drying apparatus 12 the air forwarded into the drying apparatus 12 by the air feed device, the perforated channel 82 being arranged inside the internal space of the drying apparatus 12 parallel with the shaft 78 of the drying apparatus 12. Also, in this embodiment the perforated channels 82 are arranged along the circumference (periphery) of the internal space of the drying apparatus 12.

The fan blades 86 are therefore rotated by the motor 52, the blades directing air incoming through the heat recovery channel 24 into the perforated channels 82 through the channel introductory portions 88. Air is then fed into the internal space of the drying apparatus 12 through the perforations of the perforated channels 82. The heat recovery channel 24 - in a way to be detailed below - carries hot air heated up by the waste heat of the melting apparatus 16. Accordingly, hot air can be fed into the internal space of the drying apparatus 12 through the perforated channels 82. This hot air can be utilized for drying the waste material comprised in the drying apparatus 12 (the fluids, i.e. essentially vapour and gases, are carried off by the draining channel 26). The longer the duration of the drying process in the drying apparatus 12, the lower the achievable residual humidity (monitored applying the humidity sensor 60). When a predetermined, sufficiently low moisture content (humidity) value is reached, the waste material comprised in the drying apparatus 12 is considered to be dried to a sufficient extent. At this point mass transport is halted and - in case the melting apparatus 16 is able to receive the waste material - the closing element 34, which is situated at the bottom of the drying apparatus 12 and shuts off the inlet opening of the passage element 30 in its closed state, is opened. From this point, the route of the waste material is illustrated in relation to Fig. 7.

In Figs. 5 and 6 a further embodiment of the apparatus according to the invention is illustrated. This embodiment differs from the one illustrated in Figs. 3 and 4 in that air is introduced from the fan housing 50 into the internal space of the drying apparatus 12 in a different way. In this embodiment perforated channels and channel introductory portions are not included, but the heat recovery channel 24 being connected to the drying apparatus 12 directly through the fan housing 50. In Fig. 5 the direction in which air is directed from the fan housing 50 when the fan is operating is indicated by arrows. The waste material comprised in the drying apparatus 12 can therefore also be dried in a manner illustrated in Figs. 5 and 6, utilizing hot air introduced through the heat recovery channel 24. Figs 5 and 6 also show fan blades 90.

As with the above figures, Fig. 7 also illustrates the second end of the drying apparatus 12 but it also shows the passage element 30 and the forwarding channel 14. In Fig. 7 the screw conveyor 92 arranged in the forwarding channel 14 is shown; it can be rotated by a motor 36. In Fig. 7 such a state is illustrated in the embodiment of the drying apparatus 12 also illustrated in Fig. 3 and 4 (that is, in the embodiment wherein perforated channels 82 are arranged in the internal space of the drying apparatus 12) wherein the waste material is discharged from the internal space of the drying apparatus 12. Preferably, this happens when appropriate humidity (moisture) is measured in the drying apparatus 12. Then the closing element 34 is opened applying the motor 32, i.e. the inlet opening of the passage element 30 is freed up such that the waste material can enter the passage element 30. The temperature of the material leaving the drying apparatus 12 is preferably maximum 80 °C, typically around 20 °C. As illustrated in the figure, the material entering the passage element 30 is fed to the first part of the screw conveyor 92 such that the material is carried forward in the forwarding channel 14 by the appropriate-pitch screw conveyor 92. As shown in the overview drawing of Fig. 1 , the forwarding channel 14 leads to the melting apparatus 16. The waste material discharged from the drying apparatus 12 (i.e. material that has already been subjected to drying) is preferably introduced into the melting apparatus 16 through the forwarding channel 14.

When the internal space of the drying apparatus 12 is emptied - which is facilitated by the forwarding blades 80 - the closing element 34 is closed again, and then the internal space of the drying apparatus 12 can again be filled up with waste material. The forwarding blades 80 are preferably kept rotating during the drying process such that they keep turning the waste material. During drying, the air flow delivered by the fan also contributes to dispersing the waste material in the internal space of the drying apparatus 12. Because the process carried out by the melting apparatus (out of processes performed by other subassemblies) typically takes longer than the drying process, the waste material can preferably be pre- dried in the drying apparatus, preparing it for introduction into the melting apparatus 16 when it has become empty.

Fig. 8 shows the melting apparatus 16. The figure also shows the outlet portion of the forwarding channel 14 which leads into the internal space of the melting apparatus 16. From this direction the internal space of the melting apparatus is isolated by a closing element 98. The closing element 98 is opened in case the internal space of the melting apparatus 16 has been emptied and further waste material already subjected to drying is arriving through the channel 14. In Fig. 8 a flue cleaning opening 99 is shown at the bottom portion of the flue housing 22.

As shown in Fig. 8, loosening-mixing blades 100 are arranged in the internal space of the melting apparatus 16. In addition to that, a mixing-forcing blade 104 is also arranged such that it extends into the conical portion of the melting apparatus 16. The first mixing-forcing blade 104 has a trapezoidal shape as shown from the side view, the blade fits into the conical portion of the melting apparatus 16. The blade 104 is also shown in top view in Fig. 9. As shown in Fig. 8, there are openings arranged on the blade 104, which openings are adapted for facilitating the moving of waste material mixed and forwarded by the blade. The main functionality of the blades 100 and 104 are mixing, forcing the melt produced from the waste material towards the bottom of the melting apparatus 16, and, in case of a re-start, applying opposite-direction motion, loosening the material.

As shown in Fig. 8, the melting apparatus 16 is connected to the sterilizing apparatus 18 by a passage element 107. In the passage element 107 second mixing-forcing blades 108 are arranged. The loosening-mixing blades 100, the first mixing-forcing blade 104 (essentially, a pair of blades), and the second mixing- forcing blades 108 are arranged on a common shaft 106. Motor 38 is adapted for driving the shaft 106. In this embodiment, therefore, the melting apparatus 16 comprises a cylindrical portion and a portion conically narrowing at the bottom, and the melting apparatus 16 and the sterilizing apparatus 18 are connected with each other by means of a second passage element 107 arranged coaxially with the melting apparatus 16 and separated therefrom by an unfoldable closure element 66. In some embodiments at least one loosening-mixing blade 100 is arranged in the cylindrical portion of the melting apparatus 16 on a shaft 106 extending through the melting apparatus 16 and the second passage element 107, at least one first mixing-forcing blade 104 shaped to fit in the conically narrowing portion of the melting apparatus 16 is arranged therein, and at least one second mixing-forcing blade 108 is arranged in the second passage element 107. As shown in the figure, there are heater units 102 arranged in a circularly around the melting apparatus 16 inside the heat insulation 70. These heater units 102 are responsible for heating to an appropriate temperature the waste material comprised in the internal space of the melting apparatus 16. In order that the waste material has an appropriate temperature also in the conical portion of the melting apparatus 16, i.e. that the temperature of the waste material to be forwarded into the sterilizing apparatus 18 is also appropriate, one or more heater units can be arranged also at the conical portion of the melting apparatus 16. Thereby the conical portion can be heated as well, which allows for preventing the waste material from cooling while it is being discharged (in order to minimize the energy consumption of sterilization it is preferred that the waste material arrives in the sterilizing apparatus 18 at as high a temperature as possible). In addition to that, the heating units 102 arranged at the conical portion can be applied for melting the material in the event of a malfunction, or if the material has cooled off (has hardened) because the processing apparatus was restarted. The blades can thereby be prevented from breaking and also the malfunctioning of the upper drive unit (motor 38) can be prevented. In the embodiment of the apparatus illustrated in the figures the sterilizing apparatus 18 comprises a tube-shaped sterilizing channel 109 connected with one channel end thereof to the bottom portion of the melting apparatus 16 and provided at the other channel end thereof with an outlet opening 20, multiple (at least one) heater units 68 arranged at the periphery of the sterilizing channel 109, and a screw conveyor 1 14 arranged in the sterilizing channel and adapted for forwarding the waste material entering the sterilizing apparatus 18. The sterilizing apparatus may comprise more than one such structures, i.e. sterilizing channels provided with heater units and screw conveyors, and thus more than one outlet openings can be included. The heater units 68 and 102, connected to the sterilizing apparatus 18, and to the melting apparatus 6, respectively, are oil or electric heater cartridges, and/or ring heaters arranged around the sterilizing channel 109 and the melting apparatus 16. Expediently, no energy produced by combustion is applied for heating.

As shown in Fig. 8, the melting apparatus 16 and the passage element 107 are separated by an unfoldable closure element 66. The partition that can be observed in the middle of the closure element 66 is configured because the closure element 66 opens by unfolding in both directions. In the closed state of the closure element 66 the shaft 106 can pass through it (an opening is formed in the middle of the closure element 66 for receiving the shaft 106), but the waste material cannot, therefore, the closure element 66 can be applied for providing that the waste material remains in the melting apparatus 16 for the required duration. When the temperature of the waste material comprised in the melting apparatus 16 reaches the predetermined temperature of at least 100 degrees (the temperature value can be adjusted corresponding to the composition of the waste material), the closure element 66 is opened. Thereby the waste material (which is already in a molten state) enters the passage element 107, and moving therethrough, it passes into the sterilizing apparatus 18.

The homogeneous melt (mass) produced in the cylindrical melting apparatus 16 is pushed by the blade 104 into the conical portion, and then the computer-controlled sliding closing structure (closing element 66) applied for feeding the melt opens and provides that the material is passed from the melting apparatus 16 to the sterilizing apparatus 18.

A motor 44 of the sterilizing apparatus 18 is then started, and the motor 44 starts to rotate a screw conveyor 1 14. The heater unit 68 is also activated at this time in order that the waste material passing through the sterilizing apparatus 18 can be heated to an appropriate temperature for successful sterilization. As shown in the figure, heat insulation 1 12 is arranged around the sterilizing apparatus 18.

The surface of the screw conveyor 1 14 and the blades 100, 104, 108 is preferably treated with a material that prevents the melt from sticking to the surfaces, and thereby facilitates its transport.

As it is shown in Fig. 8, a first flue 21 is also arranged at the top portion of the melting apparatus 16 surrounded by the air channel 94 of the heat exchanger, with perforations 96 being arranged on the first flue 21. Hot air generated during the melting process is introduced from the melting apparatus 16 into the internal space of the flue housing 22 through the perforations 96, while it heats also the air sucked in through the air intake opening 46 into the air channel 94 of the heat exchanger. A fan arranged in the fan housing 50 described above is responsible for sucking in air through the air intake opening 46 (in other embodiments, this functionality is performed by other air feed devices that are capable of sucking in air through the air intake opening 46). By such a configuration of the internal space of the flue housing 22 it can be provided that outside air sucked in through the air intake opening 46 can be heated utilizing the waste heat of the melting apparatus 16, and can be transported into the drying apparatus 12 applying the fan.

In the present embodiment, therefore, the flue 28 comprises a first flue 21 having cylindrical shape, provided with perforations 96 and connected to the melting apparatus 16, a flue housing 22 surrounding the first flue 21 , arranged coaxially therewith, and a second flue 28 connected to the top portion of the flue housing 22, and the air channel 94 of the heat exchanger is connected to the first flue 21 , and the air intake opening 46 is arranged outside the flue housing 22.

The internal space of the flue housing 22 can also be configured in an alternative manner in order that air entering through the air intake opening 46 can be heated up, but the helical coil arrangement is exceptionally preferable due to its simple configuration. Other heat exchanger types may also be applied.

Fig. 9 shows the top view of the loosening-mixing blades 100 and the first mixing- forcing blades 104. In Fig. 9 there is also shown that the melting apparatus 16 is supported on legs 76 (the figure essentially illustrates the internal configuration of the melting apparatus). In Fig. 9 there is shown that the blades 104 (having a trapezoidal shape in side view) assume a slight S-shape when seen from above, i.e. the upper edge of the blade 104 is bent and further portions of the blade are configured accordingly, in such a way that the blade 104 fits appropriately into the conical portion of the melting apparatus.

Fig. 10 essentially shows the air channel 94 of the heat exchanger, the heat recovery channel 24 and the connection of the draining channel 26 to the flue 28. As is shown in Fig. 10, the heat exchanger air channel 94 arranged around the first flue 21 terminates in the heat recovery channel 24 after a few revolutions around the perforated portion. In case it is not required to introduce air into the heat recovery channel 24, the inlet of the heat recovery channel 24 can be shut off by a control valve 48. In the closed state of the control valve 48, the fan arranged in the fan housing 50 is not capable of sucking in air through the air intake opening 46. Accordingly, closing the control valve 48 results in that there is no air flow through the air channel 94, implying that waste heat recovery is interrupted. This is desirable when the processing apparatus is shut down.

It is shown in Fig. 10 that the flue housing 22 leads into a second flue 29, with the second flue 29 being attached to the flue housing 22 by means of a joining flange 62. Therefore, hot air leaving the melting apparatus 16, as well as the heated gases and vapour are introduced into the internal space of the flue housing 22 through the first flue 21. Subsequently - since hot air moves upwards - the mixture of air and gases/vapours moves from the flue housing 22 to the second flue 29 at the top. The joining flange 62 does not close off the outlet opening of the flue housing 22, as it is only adapted for fitting the outlet opening to the inlet opening of the second flue 29, creating an opened (permeable) connection between them. It is shown that in this embodiment the draining channel 26 is connected to the second flue 29 (i.e. it is connected to the flue 28 of the melting apparatus 16 above the heat exchanger). The filter arrangement 63 shown in Fig. 1 is not shown in the drawing, as it is arranged at an even higher-situated section of the second flue 29.

Therefore, through the heat recovery channel 24 hot air is delivered from the air channel 94 of the heat exchanger into the drying apparatus 12. Hot air is introduced into the drying apparatus 12 by means of the air feed device, i.e. for example a fan arranged in the fan housing 50. This hot air is utilized for drying the waste material contained in the drying apparatus 12, with the gases and vapours generated during the drying process, as well as other fluids, being subsequently drained through the draining channel 26. The draining channel 26 leads into the second flue 29, implying that the material arriving from the draining channel 26 - together with the material arriving directly from the melting apparatus 16 through the flue housing 22 - is filtered in the filter arrangement 63. The filter arrangement 63 can be implemented as a mechanical filter and/or as a catalytic burner. The arrangement of the draining channel 26 according to the invention preferably provides that all of the material to be filtered can be filtered applying single common filter, i.e. the filter arrangement 63. Thereby the processing apparatus according to the invention constitutes a closed system as far as harmful substances are considered. Thereby harmful substances are filtered out without regard to their place of origin within the processing apparatus. The configuration of the processing apparatus according to the invention therefore simultaneously provides that the waste heat transmitted by the hot vapours/gases and other fluids emerging from the melting apparatus can be recovered for utilization during drying in the drying apparatus 12, and also that the emerging harmful substances are treated commonly and are filtered out.

Some embodiments of the invention relate to a method for processing waste material comprising thermoplastic material, particularly for processing crushed waste material. In the course of the method according to the invention the waste material is dried in a drying apparatus by means of an air flow, and the waste material subjected to drying by the drying apparatus is molten in a melting apparatus. In the course of the method, furthermore, the waste material melted by the melting apparatus is subjected to a sterilizing heat treatment at a temperature of at least 240 °C applying a sterilizing apparatus, and, and during the melting step, the waste material is subjected to melting in the melting apparatus at a temperature of at least 100 °C. During the drying step, in the drying apparatus, forwarding blades arranged in the elongated internal space of the drying apparatus on a shaft connecting a first end and a second end, the waste material is mixed and moved towards the second end, the waste material is dried by introducing an air flow into the drying apparatus by means of an air feed device , the air flow being heated up by heat carried off by the fluid generated during the melting process, and being fed to the drying apparatus through a heat recovery channel extending between the drying apparatus and the melting apparatus, connected with one channel end thereof to an air channel of a heat exchanger being in heat transfer relationship with a flue, the air channel having an air intake opening, the flue being arranged on the melting apparatus and being adapted for draining heat- carrying fluid generated during melting in the melting apparatus, and the heat recovery channel being connected with the other channel end thereof to the internal space of the drying apparatus through an air feed device arranged at the second end, and the fluid generated during the drying process is drained through a draining channel connected to the drying apparatus at the first end and also connected to the flue above the heat exchanger. In an embodiment of the processing apparatus and method according to the invention, the thermoplastic material content of the waste material, relative to the unit mass of the waste material, is at least 10 weight%. In a further embodiment the thermoplastic material content of the waste material, relative to the unit mass of the waste material, is between 20 and 50 weight%. In a still further embodiment the maximum particle size of the waste material is 30 mm.

In order that the percentage of the thermoplastic material preferably applied in an embodiment of the apparatus and method can be adjusted, plastic waste and communal waste are preferably fed to a crusher from two separate locations applying a transporting conveyor (the plastic waste is fed in such a quantity that the mixed waste material has a thermoplastic material content of at least 10 weight%, preferably 20-50 weight% relative to the unit mass of the mixed waste material; it is not necessary to adjust the ratio of different plastic types within that; and it does not pose a problem if the communal waste has additional thermoplastic material content as that only increases plastic content). Thereby the materials unsuited for sale and plastic waste applied as a binder are stored at separate deposits (other materials required for ensuring the desired quality of the end product, by way of example, strength-enhancing and/or strength increasing materials can also be prepared). The required quantities of waste plastic and communal waste are supplied in pre-portioned batches. Thereby the ratio and the appropriate quantities of waste plastic and communal waste can be adjusted.

The waste material is crushed to the appropriate size by the crusher. The maximum particle size is preferably 30 mm, i.e. the waste material is preferably a crushed material having a maximum particle size of 30 mm. Since the crushed material also comprises dust-like components, minimum particle size is very low. More preferably, the particle size is adjusted between 5 and 30 mm, particularly preferably between 5 and 10 mm.

Waste materials with a thermoplastic material content that is not adjusted to such extent can also be applied in the apparatus and method according to the invention, i.e. communal waste can in most cases be processed in a manner that results in a preferable end product. In case the processed communal waste does not have the required thermoplastic material content, plastic content can be increased upstream of the drying apparatus. A buffer tank may be arranged under the crusher such that it can feed the waste material continuously to the drying apparatus because the drying has the second longest cycle time. After the buffer has been filled, the crusher and the transporting conveyors applied for feeding material thereto are stopped.

In case pre-sorting is not complete, or there is no pre-sorting at all, larger objects not typically comprised in communal waste (e.g. concrete steels, large metal objects, large pieces of furniture board, tree stumps, construction waste, etc.) should expediently be manually picked out before the conveyor. If objects of that sort are regularly found in the waste material, it may be expedient to apply a more powerful crusher. In that case the waste material is first passed through a humus screen, then through a magnetic separator, and only then is it fed into the crusher.

The appropriate thermoplastic material content is obtained by analysing from time to time the waste material that is not suited for further sale (i.e. that is normally disposed of in landfills, or prepared for burning), and by taking samples, establishing an average plastic content which can be regarded the characteristic plastic content. The missing quantity has to be complemented by adding thermoplastic material. Since thermosetting plastics cannot be applied as a binder, they are not taken into account when the thermoplastic material content is calculated. Thermosetting plastics are processed in the same way as all the components of communal waste other than thermoplastic material.

The subsequent processing steps can be summarized as follows. When the drying apparatus has been filled up, the closing element situated at the bottom of the feed chute (i.e. at the bottom of the volume portion below the inlet opening 10) is closed and the drying of the mixed waste material begins. The forwarding blades - also adapted for loosening the material - are started together with the fan that delivers hot air into the apparatus through the perforated channels (which each have perforations directed at the respective appropriate angle), blowing the hot air in an evenly distributed manner utilizing waste heat, and opens the flap at adapted for controlling the air flow (the closing element 58) situated at the top of the drying apparatus, on the draining channel adapted for draining of effluent vapours/gases. In case the melting process has not yet started (i.e. during the first drying process), air can be heated applying alternative sources of energy (e.g. by heating elements - arranged along the heat recovery channel 24 - that are only applied during the first drying process), such that drying can be successfully performed.

According to our experiences the moisture content of the mixed crushed waste material fed into the drying apparatus is on average between 50%-90%, depending on regional and climatic conditions and on the time of the year. Drying is finished based on a preset value (preferably at a humidity of 10-30%) of the humidity sensor (psychrometer) such that the motor (by way of example, a fan) blowing hot air is stopped, the flap arranged on the draining channel adapted for draining of effluent vapours/gases (the closing element 58) is closed, and the control valve 48 is also closed, which that way blocks air from passing through the air channel 94 of the heat exchanger arranged in the flue housing 22. Thereby an air flow-free region is created in the whole processing apparatus.

Then the discharge flap (the closing element 34) arranged at the bottom of the drying apparatus is opened by the controller, with the screw conveyor (closed- trough screw conveyor) arranged in the forwarding channel 14 being started simultaneously and the flap arranged at the top of the screw conveyor 14 being opened such that the dried mixed waste material can be passed into the melting apparatus. The volume of the drying apparatus and the volume of the internal space of the melting apparatus have to be harmonized such that the waste material discharged from the drying apparatus can be received by the melting apparatus.

In case of a continuous operating regime the bottom discharge flap (the closing element 34) is closed by the controller as soon as the drying apparatus has become empty, while the closing flap (closing element 59) situated at the bottom of the feed chute being opened in order that the next portion of mixed, crushed waste material to be dried can be fed into the apparatus. As soon as the closed- trough screw conveyor feeding material into the melting apparatus (melting caldron, kettle, melter) has been emptied, the upper flap (closing element 98) is closed and the closed-trough screw conveyor is stopped. After the flap has been closed, heating of the waste material is started in the melting apparatus, and the mixing blades are also started. The homogenization, that is the melting (stirring and heating) of the mixed crushed waste material fed into the melting apparatus is performed applying heater rings and cartridges (heater units 102) arranged on the outside of the apparatus, controlled by the built-in temperature controllers, at a temperature of at least 100 °C, preferably 100 °C-150 °C, particularly preferably 100-120 °C. Expediently, temperatures exceeding 200 °C are not applied. As a result of continuous, uniform stirring a homogeneous melt (mass) is obtained from which the end product of any shape can be made by a press or extrusion machine (after being subjected to sterilizing heat treatment in the sterilizing apparatus). Depending on the quantity of the crushed mixed waste to be processed, the retention time of the waste material in the melting apparatus is 5-15 minutes. This duration can be measured applying a melting apparatus with a diameter of 710 mm and a height of 1 meter. The conical portion at the bottom of the melting apparatus has a height of 250 mm and a diameter narrowing from 710 mm to 200 mm. The melt is passed on to the sterilizing apparatus through the part that has a diameter of 200 mm. For example, for such an apparatus a sterilizing apparatus having a tube diameter of 140 mm can be applied. The required holding times can be calculated as a function of the quantity of the waste material and the volume of the melting apparatus. The processing apparatus can of course be operated applying a melting apparatus and sterilizing apparatus of much larger size, e.g. 5-7 times larger than the above specified dimensions. The drying apparatus should be dimensioned such that it can supply the appropriate quantities of waste material to the melting apparatus. For a single melting cycle, a batch of waste material dried during a single drying cycle is preferably fed into the melting apparatus. After the holding time has elapsed, the prepared soft homogeneous material (now having the desired fluidic consistency), made homogeneous by stirring, is discharged through the bottom discharge flap (the closing element 66) and is introduced into the sterilizing apparatus gravitationally and under the pressure exerted by the blades 104. A further functionality performed by the blades 104 is loosening the cooled off and re-hardened pieces of material (mass) by counter-rotational motion in case the apparatus becomes stuck or in the event of a later re-start, thereby increasing the service life of the apparatus and facilitating further processing. To perform this functionality, especially to perform loosening of the material, the blades 104 are arranged to have a pair of blades having an S-shaped profile. The S-shaped configuration also facilitates adequate mixing of the material and pushing it outwards into the sterilizing apparatus.

Immediately after the automated discharge flap apparatus (the closure element 66) has been opened - for example controlled by the temperature detected inside the melting apparatus - the sterilizing apparatus is started, in which the soft (fluidic), homogeneous material passes through, heated to a temperature of at least 240 °C, thereby ensuring that the material is fully sterilized. As soon as the melter has been emptied, the bottom flap is closed, followed by the opening of the upper flap of the closed-trough screw conveyor for introducing the next portion.

The melt flowing out of the sterilizing apparatus - being sufficiently agglomerated and homogeneous due to its plastic content - is fed to a press machine or extruder by an automated transport device, where it can be formed to the desired shape. The shaping devices may be low- or high-pressure (e.g. having an operating pressure of 80-540 bar), and tools adapted for preventing shrinking applying special cooling. These can be designed depending on the quality and the configuration of the planned end product, as well as on the foreseen stresses it has to withstand.

The melting apparatus and the sterilizing apparatus are preferably provided with appropriate outside insulation such that the lowest amount of energy is required for reducing environmental impact. The flue adapted for draining the vapours and gases accumulated inside the melting apparatus is arranged at the top of the melting apparatus, at the place opposite the closed-trough screw conveyor.

Hot air drained (discharged) from the melting apparatus (which is mixed with vapour and gases) is applied for drying the mixed crushed waste material fed into the drying apparatus such that a perforated cylinder (first flue 21 ) is arranged inside the flue housing, and is placed on the draining opening of the melting apparatus. The pipe coil of the heat exchanger is placed on the perforated cylinder in such a manner that it is connected to the outside air at the bottom portion of the flue housing to free breath air through a filter, with the pipe (pipe coil) being passed out from the cylinder at the top, where it carries the already heat- exchanged outside air.

Hot vapour/gases flowing out from the perforated inner cylinder heat up the outside air introduced into the pipe coil, the heated air then being introduced under the suction effect of the fan into the drying apparatus. When the drying apparatus is not operating, the control valve 48 situated at the top of the flue housing and the automatic flap (the closing element 58) arranged at the top of the drying are closed off in order to prevent a forced flow from entering the drying apparatus (which would make it more difficult to empty the drying apparatus).

According to our calculations, thereby the processing apparatus can be operated continuously, without human intervention. Quality and productivity can be ensured by taking the above mentioned control and safety measures. All the processes (and particularly the movement of closure member and flaps) are controlled and monitored by a computer. Should a problem occur, the location and description of the error is displayed on the computer screen, and thus swift intervention and problem solving is possible.

Applying the processing apparatus and method according to the invention, communal waste - optionally with the addition of an appropriate amount of thermoplastic material as a binder - can be transformed, even in a completely automated manner, to such an end product that is considered to be a recycled waste in its material according to the relevant norms and environmental regulations.

It is emphasized that the processing apparatus and method according to the invention does not relate to conventional plastic waste recycling, wherein only a given percentage of plastics and certain given types can be present in the material to be recycled, but rather envisages the processing of communal solid waste on as wide a scale as possible in order to transform waste material into usable end products that may by applied - by further shaping the material leaving the apparatus by pressing or extrusion - for replacing conventional timber and concrete products, as well as products for building and road construction. The invention is, of course, not limited to the preferred embodiments described in details above, but further variants, modifications and developments are possible within the scope of protection determined by the claims.