Field of the Invention

5 The present invention relates to method for reducing volume of deformable and/or com- pactable waste material by compacting the waste material to a block as a function of temperature and hardness.

The present invention relates to a compactor for compacting deformable and/or com- 10 pactable waste material to a block.

Background of the Invention

Waste material and the recycling of waste material is a field which receives increasing focus. Therefore, there is an ever-increasing demand for a higher quality of the waste 15 material to be recycled.

Waste material made from expanded polymeric material, such as expanded polystyrene, is in many cases feed to a compactor in order to compact the waste material into a block, which block has a reduced volume making it easier to transport. However, at present 20 each compactor designed to compact expanded polymeric material will compact with different efficiencies, and as a consequence, the different blocks will have varying den sity making it harder to optimize the recycling of the blocks.

A further problem is that in some cases the expanded polystyrene can melt too much 25 during compaction, which will cause the block to act like soft rubber and deform after leaving the compactor, thereby it becomes more difficult to handle and it further lower the quality of the block to be recycled. Even worse the expanded polystyrene may burn solid to parts of the compactor thereby causing a jam.

30 Similar problems related to varying density and melting damage of blocks can arise, when compacting PET material. Object of the Invention

It is an object of the invention to provide a method and a compactor capable of com pacting blocks of a higher quality, which higher quality is blocks with a lower variance of block density and with no melting or burn damage.

Description of the Invention

An object of the invention is achieved by a method for reducing volume of deformable and/or compactable waste material by compacting the waste material to a block as a function of temperature and hardness of the block.

The method comprises acts of

- feeding waste material to a compactor;

- compacting the waste material at the compactor to a block;

- determining a hardness of the block and a temperature of the waste material in the compactor; and

- adjusting the act of compacting as a function of the hardness and the temperature.

The deformable and/or compactable waste material may be expanded polymeric mate rial such as expanded polystyrene or expanded polystyrene foam or Polypropylene (PP) foam or Polystyrene (PS) foam or extruded polystyrene foam (XPS) or Polyurethane (PU) foam or Polyvinyl chloride (PVC) foam or Low-density polyethylene (LDPE) foam or other kinds of foam. All these foams are both deformable and compactable.

The deformable and/or compactable waste material may be Polypropylene (PP) or Pol- ystyrene (PS) or extruded polystyrene (XPS) or Polyurethane (PU) or Polyvinyl chlo ride (PVC) or Low-density polyethylene (LDPE) or Polyethylene terephthalate (PET).

The act of feeding may be performed by a user feeding the compactor or by an auto mated system or semiautomated system which system will perform the act of feeding. In some cases, there will be performed an act of shredding or dividing the waste material before the act of feeding. However, this act of shredding or dividing is not essential.

The compactor performing the act of compacting may compact using an auger powered by a motor. The act of determining and the act of adjusting may be performed simultaneously, or the act of adjusting may be performed with a minor delay. The act of determining may include performing a series of measurements of hardness and temperature followed by calculating an average, which average may be based on 2, 4, 8 or 12 measurements.

The act of determining the hardness may be performed as close to the act of compacting as possible to determine a hardness of the block exiting the active part of the compactor, while the temperature may be measured at the active part of the compactor, such that a temperature of the waste material being compacted is determined. Tests have shown that this setup results in the best quality of a block as melting is prevented, and the hardness of the block exiting the active part of the compactor is determined, enabling fast adjustment of the act of compacting, thereby the resulting block has a lower density variance.

As an example, expanded polystyrene (EPS) foam can have many different configura tions depending on the purpose of the EPS foam. Thus, different EPS foam materials contain different amounts of air and thus have different densities i.e. the EPS foam may be so called 10-gram EPS or 30-gram EPS. It is necessary to compact the 10-gram EPS more due to lower density i.e. lower amount of EPS. A conventional compactor cannot automatically adjust to the different kinds of material and as a result the produced blocks will vary as a function of feed EPS material furthermore the EPS material is compacted to avoid melting/bum damage for alle the different kinds of EPS foam. A conventional produced block (250 mm x 250 mm x 800 mm) will typically have a weight of 4-6 kg.

However, tests have shown that expanded polystyrene (EPS) foam compacted using the method according to the invention will result in block (250 mm x 250 mm x 800 mm) having a weight of 22-23 kg no matter whether the compactor is feed 10-gram EPS and/or 30-gram EPS or another kind of EPS foam. Thus, the method enables three times as much EPS material to be in stored in the same volume without causing melt/burn damage. The skilled person would understand that other dimensions of the block will result in other weights.

The resulting block also has a higher density compared to blocks compacted present day. As the compacting of the waste material is increased, so is the risk of melting damage. Thus, the act of determining and adjusting enable the act of compacting to be performed closer to the melting threshold. The waste material such as EPS is preferably compacted at or slightly below the melting temperature as the EPS material will be more deformable at or slightly below the melting temperature thereby enabling a higher com- pacting.

If the temperature is above the melting temperature then the resulting block will further deform after compaction and even worse there is a risk of the waste material such as EPS to bum solid onto the compactor thereby causing a jam

The waste material feed to the compactor is preferably material of the same type such as EPS or PET or other materials that is customary within the field of compacting, thereby the resulting block is made of the same material. In an aspect the method may comprise one or more acts of

- heating the waste material in the compactor as a function of the hardness and the tem perature; and/or

- cooling the waste material in the compactor as a function of the hardness and the temperature.

Tests have shown that the quality of the resulting block compacted from waste material such as expanded polystyrene foam is increased when compacted at a temperature at least above room temperature (20 degrees Celsius), but below a threshold temperature causing melt damage of the resulting block. The increased compacting temperature in- crease the density of the resulting block. The threshold temperature for expanded poly styrene foam may be 65 degrees Celsius. The waste material feed to the compactor will typically have a temperature being com parable with room temperature. Thus, the act of heating the waste material in the com pactor will enable a higher density. The act of heating the waste material may be performed by an auger mechanically work ing the waste material until the wanted temperature is reached. In this method a press plate may be used to control the auger displacing the block through the compactor at a speed, such that the auger works on the waste material until the wanted temperature is reached.

When the wanted temperature is reached then the revolution rate of auger may be low ered such that the temperature is kept constant. In some cases the revolution rate is lowered from 30 rpm to 12 rpm. If the temperature nears or reaches the threshold temperature, an act of cooling may be performed to prevent melt damage. The act of cooling may be a hibernating as a func tion of the temperature thus no work is performed on the waste material, such foamed waste material, until the temperatures moves below a set temperature. The method can be performed closer to the threshold temperature as the act of hibernating prevents melt damage, and in most cases the act of hibernating is performed until the temperature is dropped a few degrees Celsius.

The act of cooling may be performed by feeding new waste material to the compacter thereby reducing the temperature. This will result in a sharper drop in temperature com- pered to hibernating.

The controller may be configured to control the act of feeding the compactor.

The act of heating and/or cooling may be performed by a heat pump which can heat or cool the compactor depending on the measured temperature. This will allow a higher throughput as the compactor will not need to perform the same work on the feed waste material to reach the temperature resulting in a high density.

In an aspect the act of determining hardness may be performed by; - an act of forcing a pawl into the block, while performing an act of measuring penetra tion force.

Thereby, a direct measurement of the hardness is made, and thus the control of the com pactor can be based on data from the inner parts of the block. The pawl may be designed to be forced into the centre of the block or slightly past the centre of the block, as the centre of the block will have received the highest compacting force. There is a correla tion between the penetration force and the hardness of the block and thus of the density of the block, thus the variance of the resulting block can be decreased by measuring the hardness.

The pawl may be longitudinal element, or a cylindrical element or a spear.

The pawl may be made of metal such as steel.

The pawl can be positioned near parts of the compactor compacting the waste material, such as an auger, thereby the hardness measurement can be performed on parts of the block which has just been compacted. This will again further decrease the variance of the density along the block and between blocks.

If the hardness and thus density is too high and the temperature is too high, then the act of compacting is adjusted to achieve a lower hardness and density and temperature. If the hardness and thus density is too low and the temperature is too low, then the act of compacting is adjusted to achieve a higher hardness and density and higher temperature.

The act of determining hardness may be performed by performing an ultrasound meas urement on the block. Thereby, a non-invasive measurement is performed on the block.

In an aspect the act of compacting may be performed on expanded polystyrene with the temperature being around 70 degrees Celsius, or between 50-70 degrees Celsius or 55-63 degrees Celsius.

Expanded polystyrene (EPS) such expanded polystyrene foam has a melting tempera ture around 65-70 degree Celsius, thus the compaction expanded polystyrene can be performed at 65-70 degree Celsius or around 70 degree Celsius. However, the risk of bum damage where the EPS bums solid to the compactor causing a jam increases with temperature. Tests have shown that expanded polystyrene (EPS) such as expanded polystyrene foam can be compacted at a temperature around 65-70 degrees Celsius without caus ing melt/bum damage, where the compacted block becomes to deformable and rubber like or where the expanded polystyrene (EPS) burns solid to the compacter causing jam.

Other types of expanded polymeric material may have other threshold values, the skilled person will through tests be able to determine the different threshold tempera tures for different expanded polymeric material or other materials such as PET. Test shows that a temperature between 55-63 degrees Celsius results in a high density while having a low risk of melt/burn damage.

An object of the invention is achieved by a compactor comprising a temperature sensor and a hardness sensor and means adapted to execute the acts of the previously described method.

The compactor will produce blocks having a higher density, a smaller density variance along the block and with no or at least fewer melting damages, i.e. the compactor will produce blocks of a higher quality compared with the prior art due to adjusting the act of compacting as function of temperature and hardness.

An object of the invention is achieved by a compactor for compacting deformable and/or compactable waste material to a block. The compactor comprising:

- an inlet for receiving deformable and/or compactable waste material, an outlet and a channel extending between the inlet and the outlet;

- an auger positioned in the channel;

- a hardness sensor positioned between the auger and the outlet;

- a temperature sensor adapted for measuring a temperature in the channel, and - a controller adapted for communicating with the temperature sensor and the hardness sensor and for adjusting the auger as a function of the temperature and the hardness.

The inlet may be adapted such that a user can feed the compactor, or the inlet may be connected to a buffer tank, which may be connected to a shredder such that the waste material is shredded prior to being compacted.

The auger may be positioned at or near the inlet as it is easier to design the compactor, where the auger extends through one end of the channel as shown in fig. 1.

The hardness sensor is positioned between the auger and the outlet such that the hard ness of the block is measured. The hardness sensor may be positioned as close to the auger as possible as this enables a faster adjustment of the auger power. The temperature sensor may be positioned anywhere in the channel; however, the tem perature measurement is best if performed along the part of the channel where the auger works on the waste material. The measurement is best if performed on part of the chan nel where auger is closest to the outlet as this will be the part of the channel which will typically have the highest temperature.

The channel will typically be formed out of metal and thus a temperature measurement on the channel can be used as a temperature measurement due to the great heat conduc tion ability of metal. In an embodiment, the temperature sensor is installed as part of the auger. Thereby, the measurement is a direct temperature measurement.

The controller will receive communication from the temperature sensor and the hard ness sensor and correct the auger as a function of the temperature and the hardness.

The compactor will thus be capable of producing blocks exiting the outlet, which have a higher density, and a lower density variance along block and with less or no melting damage. The higher density will enable more material to be transported in the same volume such as the same truck storage volume. The fewer or no melt/burn damage will allow for easier recycling of the block.

In an aspect the hardness sensor may comprise: - a pawl being displaceable between a rest position outside the channel and an inserted position inside the channel, and

- means for displacing the pawl between the rest position and the inserted position, wherein the means are in communication with the controller. Thereby a direct hardness measurement is performed into the block.

The pawl may have a length enabling the pawl to insert into the centre of the channel and thus the centre of the block during intended use. The central part of the block will be the hardest part and thus the best measurement.

The pawl may be longitudinal element, or a cylindrical element or a spear.

The pawl may be made of metal such as steel. The pawl may comprise a protrusion and the hardness sensor may comprise a trigger adapted to trigger when registering the protrusion being displaced between the rest po sition and the inserted position, such that the hardness measurement is performed at the same part of the channel and thus at the same depth into the block when in intended use. The means for displacing may be a pneumatic system or a hydraulic system or a motor, however hydraulic system will give the fastest and most precise measurement of a needed penetration pressure to insert the pawl into the block. The controller will contain instructions capable of converting the penetration pressure to a hardness. The skilled person would be able to make such a conversion through tests as different pawls types and sizes will result in different penetration pressures for the same hardness.

In an aspect the compactor may further comprise - a press plate positioned between the hardness sensor and the outlet, the press plate being adapted to constrict the channel and thereby prevent or slow displacement of a block through the channel.

The press plate may be hingely connected and form part of the channel.

The press plate may comprise press plate control means, which may be a pneumatic system or a hydraulic system or a motor. The controller may be adapted to adjust press plate control means as a function of the hardness and the temperature.

The press plate may be used to control the density of the resulting press plate as a higher constriction will result in a higher density, however the temperature at the auger will also increase. Thus, the controller being able to adjust the press plate will further in crease the quality of the resulting blocks.

An object of the invention is achieved by a container comprising a compactor as previ ously described. Thereby, the compactor may be installed at a public recycling station.

The container may be a waste container comprising a shreeder and optionally a buffer tank prior to the compactor.

An object of the invention is achieved by a block obtainable by performing the method as previously described on deformable and/or compactable waste material.

Thereby, a block having less variance of the density along a longitudinal axis is obtained with no or less damage.

An object of the invention is achieved by a computer program comprising instructions to cause the compactor to execute the acts of the method.

An object of the invention is achieved by a computer-readable medium having stored thereon the computer program. Description of the Drawing

Fig. 1 illustrates a compactor in a perspective view;

Fig. 2 illustrates a compactor in a cross-section view;

Fig. 3 illustrates a compactor; Fig. 4 illustrates a hardness sensor; and

Fig. 5 illustrates a method for reducing volume of deformable and/or compactable waste material by compacting the waste material to a block as a function of tempera ture and hardness.

Detailed Description of the Invention

Fig. 1 illustrates a compactor 10 in a perspective view. The compactor 10 being de signed for compacting deformable and/or compactable waste material to a block 80.

The compactor 10 comprises an inlet 22 for receiving deformable and/or compactable waste material, an outlet 24 and a channel 20 extending between the inlet 22 and the outlet 24. A tray 12 extends after the outlet 24 for receiving the blocks 80 (not shown) exiting the compactor.

The shown compactor 10 comprises a separator 70 for dividing the block 80 exiting the outlet 24. The separator 70 comprises a displaceable blade for dividing the block 80, wherein separator control means 72 control the displaceable blade. The separator control means 72 may be a pneumatic system, or a hydraulic system or a motor for displacing the blade into the block 80. The separator 70 may be controlled by a con troller 50. The compactor 10 comprises an auger 26 positioned in the channel 20 and powered by a motor 28. The auger is not visible in figure 1.

The compactor 10 comprises a hardness sensor 30 positioned between the auger 26 and the outlet 24. The hardness sensor 30 comprises a pawl 32 being displaceable between a rest position 34 outside the channel 20 and an inserted position 36 inside the channel 20. The hardness sensor 30 comprises means 38 for displacing the pawl 32 between the rest position 34 and the inserted position 36, wherein the means are in communication with the controller 50.

The pawl 32 control means 38 may be a pneumatic system or a hydraulic system or a motor. However, the hydraulic system will give the more precise measurement of the hardness than the pneumatic system.

The compactor 10 comprises a temperature sensor 40 adapted for measuring a temper ature in the channel 20. The temperature sensor 40 is position outside the channel 20, however that measurement is sufficient to measure a temperature of the waste material in the compactor 10.

The temperature sensor 40 is positioned on part of the channel 40 having the auger 20 to measure a temperature of the waste material being compacted.

The compactor 10 further comprises a press plate 60 positioned between the hardness sensor 30 and the outlet 24. The press plate 60 is adapted to constrict the channel 20 and thereby prevent or slow displacement of a block 80 through the channel 20.

The press plate 60 comprises a press plate control means 62 which may be pneumatic system or hydraulic system or a motor.

The press plate 60 is hingely connected to and forms part of the channel 20.

The compactor 10 the controller 50 adapted for communicating with the temperature sensor 40 and the hardness sensor 30 and for adjusting the auger 26 as a function of the temperature and the hardness.

The controller 50 can further be adapted for adjusting the press plate 60 as a function of the temperature and the hardness.

Figure 2 and 3 illustrates a compactor 10 in a cross-section view, wherein the figure 3 discloses the part around the auger 26, hardness sensor 30 and the temperature sensor 40. The shown compactor 10 is the same as the compactor 10 disclosed and described in figure 1.

Fig. 4 illustrates a hardness sensor 30. The hardness sensor 30 comprises pawl control means 38, which is a hydraulic system controlling the displacement of a pawl 32, which pawl 32 is displaceable between a rest position 34 as shown in figure 4 and a inserted position 36 as shown in figure 3.

The pawl 32 comprises a protrusion 33 and the hardness sensor 30 comprises a trigger 39 adapted to trigger when the protrusion 33 moves past the trigger 39 and thereby causing a controller 50 to determining a hardness of the block 80. The pawl 32 and protrusion 33 is positioned such that the act of determining is performed before the pawl 32 is at maximum penetration depth.

The pawl 32 will in most cases have a length enabling a penetration into or slightly past the centre of a channel 20 and thereby into the centre of a block 80 to determine a hardness of the centre.

Fig. 5 illustrates a method 1000 for reducing volume of deformable and/or compacta- ble waste material by compacting the waste material to a block 80 as a function of temperature and hardness.

The method 1000 comprises an act of feeding 1100 waste material to a compactor 10. The act of feeding 1100 may be performed manually by a user or by an automated system.

The method 1000 comprises an act of compacting 1200 the waste material at the com pactor 10 to a block 80.

The method 1000 comprises an act of determining 1300 a hardness of the block 80 and a temperature of the waste material in the compactor 80. The act of determining 1300 hardness may be performed by an act of forcing 1350 a pawl 32 into the block 80, while performing an act of measuring 1360 penetration force.

The act of measuring 1360 penetration force may be by measuring the hydraulic pres- sure needed for the pawl being inserted into the block 80.

The method 1000 comprises an act of adjusting 1400 the act of compacting 1200 as a function of the hardness and the temperature. The method 1000 may comprise one or more acts of

- heating 1500 the waste material in the compactor 10 as a function of the hardness and the temperature; and/or

- cooling 1550 the waste material in the compactor 10 as a function of the hardness and the temperature.

Tests have shown that the act of compacting should at least be performed at a tempera ture above room temperature but below a threshold temperature causing degradation of the waste material such as melting. The skilled person will be able to perform experi ence determine the threshold temperature for different material types.

If the act of compacting 1200 is performed on expanded polystyrene, then the temper ature during the act of compacting should be below 65 degrees Celsius, or between 50-65 degrees Celsius or 55-63 degrees Celsius. Experiments show signs of melting at temperatures at or above 65 degrees Celsius of the expanded polystyrene. The density was maximised at the range 55-63 degrees Cel sius without causing melting damage.

The act of cooling 1550 may be performed by hibernating until the temperature is at an acceptable level.

The act of heating 1500 may be performed by an auger 26 performing work on the waste material until a desired temperature is reached. The act of heating 1500 and act of cooling 1550 may be performed by a heat pump.