Apparatus for separating materials Field of the Invention The present invention relates to an apparatus for separating materials comprising liq- uid and solid substances, which apparatus comprises a frame structure, a drive station, a first piston rod, a second piston rod, a first piston member, a second piston member, a cylinder housing with at least one inlet for the material, the drive station is connected to the frame structure, the cylinder housing is movably connected to the frame struc- ture, the first piston member is connected to the first piston rod, and the second piston member is arranged inside the cylinder housing and connected to the second piston rod.

Background of the Invention The separation of materials into liquid and solid substances is applied in several dif- ferent branches, e. g. the branches regarding waste water, fruit and manure.

Decanters, filters or sieves are usually applied for removing solid materials. Decanters are disadvantageous as they are very expensive and mechanically advanced. Further- more, they can only be used in waste water containing large amounts of liquid and small amounts of solid particles. Thus it is impossible to apply a decanter in connec- tion with materials containing liquid and large particles such as metal items, paper, diapers, straw, rooks, rubber bands, organic matter and the like without damaging the decanter.

The disadvantage of filters or sieves is that these only separate a certain amount of solid materials from the liquid, thus the liquid contains a lot of unwanted solid materi- als, which can be burned off. Furthermore, the filters or sieves may clog as a result of continuous use; hence it is necessary to clean them periodically which is a waste of time and which reduces filter or sieve capacity.

DE-C1-19604662 describes a dewatering apparatus for sludge, especially liquid sludge from a waste water purification plant. The apparatus comprises a frame structure with

one cylinder housing, a number of piston members and a hydraulic activated piston rod arrangement. The sludge is filled into the cylinder, and the piston members are pushed together by the hydraulic activated piston rod, whereby the liquid is squeezed out of the sludge.

The dewatering apparatus is disadvantageous as it is very complex and comprises a vibration module (17) for vibrating the squeezed sludge, and thus it releases the sludge into an underlying discharge unit (9) and several hydraulic activated piston rods (3,5, 7).

Furthermore, DE-C1-19604662 describes the use of a cloth (13) inside the cylinder.

The cloth is probably used for retaining the solid material during the squeezing of the sludge. There is no mentioning of why such cloth is used inside the cylinder housing; however, the use of the cloth is illustrated in figures 2-4C. This means that a kind of filter or cloth bag is provided, which prevents the sludge from disappearing though the outlet of the cylinder housing.

The use of a cloth is not recommendable as the squeezed sludge has to be emptied from the cloth into the underlying discharge unit by e. g. the aforementioned vibration module. Furthermore, there is a risk of the solid materials clogging the cloth when dewatering sludge with large amount of solid materials. To prevent the solid materials from clogging the cloth, the cloth may be replaced after each pressing process, how- ever, this is time consuming, and thus it is not advantageous to apply this method in connection with continuous use of the dewatering apparatus.

Object of the Invention The object of the present invention is to provide a mechanically simple apparatus which continuously and/or in batches separates materials into liquid and solid sub- stances regardless of the type of material and the amount and size of the solid sub- stances of the material.

A further object of the present invention is to provide an apparatus, which can be ap- plied in connection with different kinds of materials, e. g. waste water, fruits and ma- nure, without changing the configurations of the cylinder housing and the piston member significantly.

These objectives can be obtained with an apparatus as described in the preamble of claim 1, where the apparatus further comprises locking means for releasable interlock- ing of the cylinder housing and the first piston member during the separation process.

Description of the Invention The apparatus for separating a material comprising liquid and solid substances, com- prises a frame structure, a drive station, a first piston rod, a second piston rod, a first piston member, a second piston member, a cylinder housing with at least one inlet for the material, the drive station is connected to the frame structure, where the cylinder housing is movably connected to the frame structure, the first piston member is con- nected to the first piston rod, and the second piston member is arranged inside the cyl- inder housing and connected to the second piston rod.

Hence, it is possible to move the cylinder housing along the frame structure while maintaining the position of the second piston member in relation to the frame struc- ture, thereby causing a reduction of the volume of the cylinder housing so the material is squeezed and the liquid substances are removed from the material.

To provide the compression chamber consisting of the cylinder housing and the two piston members, the apparatus further comprises locking means for releasable inter- locking of the cylinder housing and the first piston member during the separation process. Hence, the locking means ensure that the first piston member is interlocked with the cylinder housing while the second piston member is arranged inside the cyl- inder housing causing the compression chamber to occur.

According to one embodiment of the present invention the locking means are pneu- matically driven. However, as an alternative they can be driven either electrically or hydraulically.

Due to the fact that the cylinder housing is moving, the second piston member acts as a return flow seal when the inlet of the cylinder housing passes the second piston member. This simplifies the inlet construction as no return flow valve has to be in- stalled.

The following describes one cycle of the separation process, which cycle comprises the following steps: 1. The locking means interlock the first piston member and the cylinder housing, which means that a compression chamber occurs between the two piston members and the inside of the cylinder housing.

2. Material is filled into the compression chamber. Firstly, the liquid substances flow through the cylinder housing without obstruction. Secondly, the inlet closes when the compression chamber is full.

3. The drive station activates the first piston rod, so the cylinder housing and the first piston member move along the frame structure, which reduces the compression chamber volume. Furthermore, the liquid substances are squeezed out of the mate- rial.

4. When the material is squeezed enough, or when the first piston member/cylinder housing can not be moved any further, the compression chamber contains only solid substances with a small amount of liquid substances.

5. To empty the compression chamber, the locking means disengage the interlocking of the first piston member and the cylinder housing. Thereby the first piston mem- ber moves a further distance, which means that a gap between the cylinder housing and the first piston member occurs. The cylinder housing moves again so the sec-

ond piston member pushes the compressed material out of the cylinder housing and into an underlying discharge.

6. Then the first piston member moves back into contact with the cylinder housing, and the locking means ensure that the first piston member and the cylinder housing interlock once more and the compression chamber occurs again.

7. Finally, the cylinder housing/first piston member moves backward until the inlet of the cylinder housing is positioned in front of the second piston member. The appa- ratus is now ready for the next cycles.

According to one preferred embodiment of the invention the drive station is a hydrau- lic pump unit. Because of the hydraulic pump unit it is possible to provide the neces- sary pressure for moving the cylinder housing/first piston member and thus pressing the material trapped inside the cylinder housing and the two piston members.

If the solid substances e. g. are used as fuel, it is important to remove as much of the liquid substances as possible, hence it is necessary to apply high pressure on the mate- rial trapped inside the cylinder housing and the two piston members. According to one embodiment of the present invention, the hydraulic pump unit allows a pressure of 180 bars on the material, which equals 15 ton of pressure. Tests carried out with a proto- type have shown that it is necessary to apply a hydraulic pressure above at least 100 bars to produce solid substances with sufficiently low liquid content.

Alternatively to a hydraulic drive station, the drive station can be driven by a motor, which is connected to a mechanical arrangement comprising a toothed rack and gear wheel or a pneumatic drive station. It is important that the drive station has enough power to apply the necessary pressure on the material trapped inside the cylinder hous- ing and the two piston members. Likewise it is important that the drive station dis- places the piston members along the piston rods.

To ensure that only liquid substances are pressed out of the material during movement of the piston member/cylinder housing, the cylinder housing is perforated, having ap-

ertures covering 25-75 % of the cylinder housing surface area. These apertures contain solid substances of a dimension larger than the dimension of the apertures. It is possi- ble to change the cylinder housing according to which materials need to be dewatered.

According to one embodiment of the present invention, the apertures are circular holes having a diameter of 2 millimetres. Hence, all solids exceeding 2 millimetres are con- tained inside the cylinder housing. If the liquid substances are to be further purified, a decanter is positioned right next to the apparatus, hence removing small solid sub- stances.

To press as much liquid as possible out of the material, the apertures cover 25-75 % of the cylinder housing surface area. Tests with a prototype have shown that apertures covering 50 % of the cylinder housing surface area ensure a very high drainage effect.

The dimension of the inlet of the cylinder housing and the apertures in the cylinder housing determine the size of the solid substances, which the apparatus is able to con- tain. According to a preferred embodiment of the present invention the inlet is circular with a dimension of 130 millimetres, and the apertures consist of circular holes with a diameter of 2 millimetres, hence the apparatus can contain solid substances in the range of 2-130 millimetres.

Filling the cylinder housing with material comprising liquid and solid substances, causes the cylinder housing during the filling time to act as a sieve, where liquid sub- stances run through the apertures without obstruction, and during the pressing period liquid is squeezed out of the material and discharged through the apertures. Hence, the cylinder housing has two functions, firstly it acts as a sieve and secondly it acts as a barrier containing solid substances.

To prevent any solids from clogging the apertures in the cylinder housing during use, the apertures are conically formed with outwardly increasing dimension. Hence, any solid entering the apertures easily leaves the apertures. If the apparatus contains any solids while not in use, these solids are pushed out of the apertures next time the appa- ratus is used.

Hence, it is the cylinder housing, which is moving when the material is pressed, thus the cylinder housing has to be movably connected to the frame structure in a securely and supporting manner. Therefore the apparatus, furthermore, comprises a number of support units, which are connected to the frame structure. The support units consist of one or more of the following: a number of aligned sliding rails, a number of evenly distributed ball bearings or row of rollers.

To prevent the fluid substances from being squeezed from the material and to the envi- ronment, the apparatus, furthermore, comprises a jacket, which encircles the cylinder housing and which is connected to the cylinder housing. Hence, it is possible to collect the liquids e. g. into a discharge.

According to a preferred embodiment of the present invention the apparatus, further- more, comprises at least one discharge unit for both liquid and solid substances. The discharge for liquid substances can be a tray or pipes providing a connection to a large holding tank, which must be emptied a few times during a time period. Alternatively, the discharge unit can be directly connected to e. g. the drain or to a following process apparatus.

The discharge unit for solid substances can be a bin, a chute leading to a bin, a belt conveyor leading to a container, which must be emptied few times during a time pe- riod. Alternatively, the discharge unit can be directly connected to e. g. a following process apparatus or a burning facility.

The discharge unit for fluid substances is connected to the cylinder housing, and the discharge unit for solid substances can either be connected to the cylinder housing and/or be movably arranged to the frame structure.

To control the dewatering process the apparatus, furthermore, comprises at least one sensor arranged inside the cylinder. One kind of sensor is a floating device, which me- ters the amount of material filled into the cylinder housing, hence when the cylinder housing is filled, the feeding of material stops, and the movement of the piston mem- ber/cylinder housing starts, which causes squeezing of the material.

Another kind of sensor is a movement sensor, which determines the exact position of the piston members/cylinder housing, hence the steering knows if the first piston member has to be interlocked with the cylinder or if is has to be moved to allow the dewatered solid substances to fall into an underlying discharge. Furthermore, the sen- sor registers when the second piston member moves past the material inlet of the cyl- inder housing, thereby sending a signal to a valve shutting off the inlet, hence material is prevented from entering the cylinder housing behind the second piston member.

A steering is arranged in connection to the apparatus for controlling the drive station, hence the movement of the cylinder housing, the locking means and the inlet valve.

According to one embodiment of the present invention the steering is a PLC steering.

In the aforementioned the apparatus according to the present invention is used for separating materials, such as liquid manure comprising liquid (e. g. water, urine) and solids (e. g. organic fibres like straw, faeces) substances, with a large amount of solid substances. However, the apparatus can be used for separating other materials com- prising liquids and solid substances, e. g. waste water, sludge, fruits.

Description of the Drawing In the following the invention is explained in more detail with reference to the accom- panying drawing, where Fig. 1-3 shows an apparatus according to the invention.

Detailed Description of the Invention Fig. 1-3 shows an apparatus 1 for separating materials comprising liquid and solid substances, which apparatus 1 comprises a frame structure 8, a drive station 7, a first piston rod 6, a second piston rod 5, a first piston member 4, a second piston member 3, a cylinder housing 2 with at least one inlet 11 for the material.

The drive station 7 is connected to the frame structure 8, and the cylinder housing 2 is movably connected along the sliding rail 9 to the frame structure 8, the first piston

member 4 is connected to the first piston rod 6, and the second piston member 3 is arranged inside the cylinder housing 2 and connected to the second piston rod 5 Locking means 12 are provided for releasable interlocking of the cylinder housing 2 and the first piston member 4 during the separation process.

Fig. 1 shows that the locking means 12 are activated, thus causing the first piston member 4 and the cylinder housing 2 to interlock, so a compression chamber 13 oc- curs between the two piston members 3,4 and the inside of the cylinder housing 2.

Fig. 2 shows that the drive station 7 activates the first piston rod 6, so the cylinder housing 2 and the first piston member 4 moves along the sliding rail 9/frame structure 8, thereby reducing the volume of the compression chamber 13, and further liquid sub- stances are squeezed out of the material (not shown). Furthermore, it is possible to see that the second piston member 3 acts as a return flow seal, as the inlet 11 is positioned at right of the second piston member 3.

Fig. 3 shows how to empty the apparatus 1 by disengaging the locking means 12, hence the first piston member 4 and the cylinder housing 2 is no longer interlocked.

Thus the first piston member 4 moves a further distance, so a gap X between the cyl- inder housing 2 and the first piston member 4 occurs. Again the cylinder housing 2 moves, so the second piston member 3 pushes the compressed material (not shown) out of the cylinder housing 2 and into an underlying discharge 10, here shown as a belt conveyor.