Screw press apparatus including an improved CIP arrangement and method of cleaning the apparatus

Abstract

The invention relates to a screw press apparatus (1) comprising an outer casing (2) surrounding a screening tube (6a) with a plurality of liquid discharge holes, a slurry inlet port (3) at one end of the screening tube and a solids discharge port (4) at an opposite end of the screening tube, the screening tube housing an axially located auger (5), the outer casing (2) having a first opening in fluid communication with the slurry inlet port (3), a second opening in fluid communication with the solids discharge port (4), and a third opening (8) in fluid communication with the liquid discharge holes of the screening tube (6), a cleaning device (20) located between the outer casing and the screening tube, a device (10) for axially moving the cleaning device. The cleaning device (20) has a rigid co-axial liquid supply pipe (30) having at least one washing pipe (21, 22, 23, 24) at least partially surrounding the screening tube (6), each at least one washing pipe (21, 22, 23, 24) containing a plurality of nozzles (211, 221, 231, 241) facing the screening tube (6a). The screw press apparatus is especially suited for processing protein containing slurries, and in another aspect the invention relates to a method of producing a gluten product using the screw press apparatus.

Claims

1. A screw press apparatus comprising: an outer casing surrounding, a screening tube defining a longitudinally extending axial direction, the screening tube comprising a plurality of liquid discharge holes, a slurry inlet port at one end of the screening tube and a solids discharge port at an opposite end of the screening tube, the screening tube housing an axially located auger, the outer casing having a first opening in fluid communication with the slurry inlet port, a second opening in fluid communication with the solids discharge port, and a third opening in fluid communication with the liquid discharge holes of the screening tube, a cleaning device located between the outer casing and the screening tube, wherein the cleaning device has a rigid co-axial liquid supply pipe configured to be moved axially between the slurry inlet port and the solids discharge port, the supply pipe having a substantially smooth surface, which is generally parallel to the axial direction as defined by the screening tube, and wherein the rigid co-axial liquid supply pipe comprises two or more washing pipes, each washing pipe at least partially surrounding the screening tube, each washing pipe comprising a plurality of nozzles facing the screening tube, the two or more washing pipes being distributed in the longitudinally extending axial direction along a longitudinal axis of the rigid co-axial liquid supply pipe, with a distance between the respective washing pipes not exceeding a stroke of the rigid co-axial liquid supply pipe, and wherein the rigid co-axial liquid supply pipe engages a water-tight gland disposed at an opening in the outer casing, and wherein the liquid supply pipe extends through the outer casing.

2. A screw press apparatus according to claim 1, wherein the rigid co-axial liquid supply pipe is connected to a hose connection at an end of the rigid co-axial liquid supply pipe, and wherein the end of the rigid co-axial liquid supply pipe is located outside the outer casing.

3. A screw press apparatus according to claim 2, wherein the hose connection is connected to at least one internal supply conduit, each in fluid communication with the two or more washing pipes and accommodated in the rigid co-axial liquid supply pipe.

4. A screw press apparatus according to claim 2, wherein the hose connection is connected to an internal low-pressure supply conduit and an internal high-pressure supply conduit, each supply conduit being in fluid communication with the two or more washing pipes and accommodated in the rigid co-axial liquid supply pipe.

5. A screw press apparatus according to claim 1, wherein at least some of said plurality of nozzles are capable of operating with an applied pressure of washing liquid of 60 bar or more.

6. A screw press apparatus according to claim 1, wherein at least one of the two or more washing pipes has an open configuration in the form of a V, a U, or a Y.

7. A screw press apparatus according to claim 1, wherein at least one of the two or more washing pipes has a closed configuration in the form of a circle, a rectangle, or any other polygonal shape.

8. A screw press apparatus according to claim 1, wherein at least one of the two or more washing pipes comprises at least one additional nozzle directed in another direction than towards the screening tube.

9. A screw press apparatus according to claim 1, wherein the cleaning device does not comprise any moving parts within the outer casing.

10. A screw press apparatus according to claim 1, wherein the cleaning device does not comprise any hosing within the outer casing.

11. A screw press apparatus according to claim 1, wherein the screening tube is accommodated in a concentrically arranged support tube.

12. A screw press apparatus according to claim 1 further comprising a motor for axially moving the rigid co-axial liquid supply pipe.

13. A screw press apparatus according to claim 1 further comprising a linear actuator for axially moving the rigid co-axial liquid supply pipe.

14. A method of cleaning a screw press apparatus, the method comprising: providing a screw press apparatus according to claim 1, and applying a cleaning liquid through the rigid co-axial liquid supply pipe at a pressure in the range of 3 bar to 60 bar to wash the plurality of liquid discharge holes of the screening tube.

15. A method of producing a sticky product, the method comprising: providing a screw press apparatus according to claim 1, applying a slurry comprising a sticky product and having a predefined water content, applying a cleaning liquid through the rigid co-axial liquid supply pipe at a pressure in the range of 3 bar to 60 bar to wash the plurality of liquid discharge holes of the screening tube, and obtaining the sticky product from the solids discharge port.

16. A method of producing a gluten product, the method comprising: providing a screw press apparatus according to claim 1, applying a gluten slurry having a water content, a protein content and a content of other solids, applying a cleaning liquid through the rigid co-axial liquid supply pipe at a pressure in the range of 3 bar to 60 bar to wash the plurality of liquid discharge holes of the screening tube, and obtaining the gluten product from the solids discharge port.

17. The method according to claim 16, wherein the gluten product has a moisture content below 68%.

18. The method according to claim 16, wherein applying the gluten slurry is performed continuously over a period of at least 1 week.

19. The method according to claim 16, wherein the gluten product is obtained at a rate in the range of 1 ton/hour to 15 tonnes/hour.

20. The method according to claim 16, wherein the cleaning liquid is applied during normal operation of the screw press apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in more detail below by means of non-limiting examples of presently preferred embodiments and with reference to the schematic drawings, in which

(2) FIG. 1 shows a part-sectional plan view of a screw press apparatus in an embodiment of the present invention;

(3) FIG. 2 shows a plan view of a detail of the screw press apparatus of FIG. 1, on a larger scale;

(4) FIG. 3 is a cross-sectional view along the line A-A of FIG. 1; and

(5) FIGS. 4 and 5 show schematic views corresponding to FIG. 2 of the screw press apparatus in two different positions.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(6) FIGS. 1 to 5 show an embodiment of the screw press apparatus 1 of the invention. The screw press apparatus 1 generally comprises an outer casing 2 surrounding a screening tube 6a (cf. FIG. 3) with a plurality of liquid discharge holes (not shown in detail). The screening tube 6a is in the embodiment shown accommodated in a concentrically arranged support tube 6. The support tube 6 is also provided with openings (not shown in detail) but of a larger dimension than the discharge holes of the perforated screening tube 6a. A slurry inlet port 3 is provided at one end of the support tube 6 and a solids discharge port 4 is provided at an opposite end of the screening tube. Furthermore, the support tube 6 and the screening tube 6a house an axially located auger 5.

(7) The outer casing 2 has a first opening (not shown in detail) in fluid communication with the slurry inlet port 3, a second opening (not shown in detail) in fluid communication with the solids discharge port 4, and a third opening 8 in fluid communication with the liquid discharge holes of the screening tube 6a, here via a funnel-shaped section 7.

(8) In the embodiment shown, the screw press apparatus 1 has an outer casing 2 made of stainless steel AlSl316, which fully surrounds the screening tube 6a, so that access to the screening tube 6a by the operator is prevented. The outer casing 2 has a hopper 3a providing fluid communication with the slurry inlet port 3 for applying an aqueous protein slurry or another starting material to the screw press apparatus 1. The hopper 3a is likewise made of stainless steel although a thermoplastic material is equally relevant for the hopper. Only a section is shown of the support tube 6 and the screening tube 6a, at the zone of the apparatus labelled as zone 3, although it is to be understood that the support tube 6 and the screening tube 6a cover the full length of the axially located auger 5, i.e. zone 1, zone 2 and zone 3. The plurality of liquid discharge holes of the screening tube 6a are round and of the same diameter and equally distributed over the surface of the screening tube 6a. The auger 5 has a predefined taper and a helical conveyor 5a so that rotation of the auger 5 will move the slurry towards the solids discharge port 4. Liquid discharge is guided via funnel-shaped section 7 and further out of the third opening 8 to suitable drainage means (not shown). The support tube 6 and the screening tube 6a define a longitudinally extending axial direction a, indicated in FIGS. 1 and 4.

(9) As will be described in further detail below, the screw press apparatus 1 comprises a cleaning device 20 located between the outer casing 2 and the screening tube 6a and a device 10 for axially moving the cleaning device 20. The device 10 for axially moving the cleaning device 20 is located outside the outer casing 2 and is capable of axially moving the cleaning device 20 over a stroke L.

(10) A plan view of a detail of the screw press apparatus 1 of FIG. 1 is shown in FIG. 2. The cleaning device 20 has a rigid liquid supply pipe 30 defining a longitudinal axis x as shown in FIG. 2. In FIG. 3, the longitudinal axis x of the rigid liquid supply pipe 30 hence extends in a direction perpendicular to the paper plane, but is not indicated for the sake of clearness and ease of reading. The axial direction a as defined by the screening tube 6a is not shown in FIG. 3 either, and, as is readily understood, the extension of the axial direction at the center of the screening tube 6a is also perpendicular to the paper plane in FIG. 3. In FIG. 4, the indication of the longitudinal axis x would be substantially superimposed on the shown longitudinally extending axial direction a of the screening tube 6a, and thus of the concentric support tube 6. Thus, in the context of the invention co-axial is used synonymously for such configurations in which the axis of the liquid supply pipe is generally parallel to the longitudinal axis of the screening tube itself and hence extends in the axial direction defined by the screening tube. The cleaning device 20 has the rigid co-axial liquid supply pipe 30 with washing pipes 21, 22, 23, 24, which washing pipes have nozzles 211, 221, 231, 241 facing and capable of washing the full perimeter of the screening tube 6a. The rigid co-axial liquid supply pipe 30 enters the outer casing 2 via a water-tight gland 31. The device 10 for axially moving the cleaning device, as depicted in FIG. 2, comprises a motor 11 with a gear (not shown) for belt 12 thereby causing axial movement of the rigid co-axial liquid supply pipe 30. The device 10 may in principle be any suitable linear actuator capable of providing the required stroke L. The piping including the flexible hoses represented by the hose connection 32 and supported by flexible hose support 13 are capable of withstanding a pressure of at least 100 bar, and the other end of the hose connection 32 is connected to a high pressure liquid supply system (not shown). It is to be understood that the hose connection 32, the motor 11 and other parts of the device 10 for axially moving the cleaning device 20 are located outside the outer casing 2, even though this is not shown in FIG. 2.

(11) The screw press apparatus 1 of FIG. 1 is depicted cross-sectionally in FIG. 3 along the line A-A indicated in FIG. 1. Thus, FIG. 3 shows the outer casing 2 surrounding the support tube 6 and in turn the screening tube 6a. The outer casing 2 is depicted as having a square cross-section and is provided with an end wall 9, but the outer casing 2 is not limited to having a square cross-section; the cross-section could likewise be round or have another rectangular shape. The auger 5 and the screening tube 6 are shown having round cross-sections. The slurry inlet port 3 is shown on top of the outer casing 2, and thereby also on top of the support tube 6 and the screening tube 6a so that a slurry present in the hopper will enter the screening tube 6a due to gravity. Likewise, the third opening 8 is below the screening tube 6a.

(12) The screw press apparatus 1 is shown as being positioned substantially horizontally. However, it is also conceivable to position the screw press apparatus 1 is an inclined position.

(13) Generally, the rigid co-axial liquid supply pipe 30 has two or more washing pipes in preferred embodiments. Here, four washing pipes including a first washing pipe 21, a second washing pipe 22, a third washing pipe 23, and a fourth washing pipe 24 are provided, each at least partially surrounding the screening tube 6. Each washing pipe 21, 22, 23, 24 is provided with a plurality of nozzles 211, 221, 231, 241 facing the screening tube 6a. It is also advantageous if at least one of the washing pipes 21, 22, 23, 24 comprises one or more nozzles directed in another direction than towards the screening tube 6. In the embodiment shown, the fourth washing pipe 24 is shown with one such nozzle 242,

(14) In principle, the washing pipes may take any suitable form and configuration, either open or closed in a cross-sectional view. In the embodiment shown as is discernible from FIG. 3, the first washing pipe 21 and the third washing pipe 23 each has an open configuration. The open configuration may for instance be in the form of a V, a U or a Y, the first washing pipe 21 thus having a substantially Y-shaped configuration, whereas the third washing pipe 23 has the shape substantially as a stylized C.

(15) The second washing pipe 22 and the fourth washing pipe 24 each has a closed configuration in the form of polygonal shape.

(16) The spray pattern of representative nozzles 211, 221 and 231 are indicated in the cross-sectional view of FIG. 3, the fourth washing pipe 24 being not visible in this cross-section.

(17) For instance, the second washing pipe 22 may be provided with a high pressure nozzle 221 which can spray the surface of the screening tube 6a with washing liquid in an angle of about 60.

(18) The cleaning device 20 may as indicated in FIG. 3 be provided with separate internal supply conduits 301 and 302, either for supplying different cleaning liquids, or one and the same cleaning liquid at different pressures.

(19) Throughout the above description it is understood that the terms cleaning liquid and washing liquids are used interchangeably. Furthermore, it is understood that terms such as directed towards the screening tube 6a are to be interpreted as covering also the presence of the support tube 6, as the cleaning liquid here reaches the screening tube 6a via the openings of the support tube 6.

(20) Referring now in particular to FIGS. 4 and 5, the cleaning device 20 is shown in two different positions, relative to zone 1, zone 2 and zone 3 of the outer casing 2 and in turn of the screening tube 6a.

(21) It is preferred that the washing pipes 21, 22, 23, 24 are distributed axially, that is in the generally longitudinal direction as defined by the longitudinally extending axial direction a of the screening tube 6a, and thus in turn along the longitudinal axis x of the rigid co-axial liquid supply pipe 30, with a distance d1, d2, d3 between the respective washing pipes 21, 22, 23, 24. In order to provide optimum coverage of the spraying of the screening tube 6, it is advantageous that the distance d1, d2, d3 do not exceed the stroke L or at most corresponds to the stroke L of the rigid co-axial liquid supply pipe 30.

(22) The rigid co-axial liquid supply pipe 30 of the cleaning device 10 is shown schematically in the two different positions in FIGS. 4 and 5, which illustrate how the full length of the screening tube 6a can be washed with one stroke L of the rigid co-axial liquid supply pipe 30, which stroke L is much shorter than the full length of the screening tube 6a when the cleaning device 20 has multiple washing pipes appropriately distributed over the length of the rigid co-axial liquid supply pipe 30.

(23) During operation, the slurry is fed to the screw press apparatus 1 via hopper 3a and further to slurry inlet port 3. The slurry is dewatered as the auger 5 rotates and the excess water is squeezed through the perforations of the screening tube 6a and openings in the support tube 6 and drained off from the third opening 8. The sticky product is obtained from the solids discharge port 4.

(24) When washing of the screw press apparatus 1 is desired, for instance according to a pre-defined cleaning regime, a cleaning liquid is supplied through the rigid co-axial liquid supply pipe 30 and further to the cleaning device 20. The cleaning liquid is sprayed through the nozzles 211, 221, 231, 241 associated to the respective washing pipes 21, 22, 23, 24. As described in the above, the cleaning liquid may be applied to some of the nozzles 221 at high pressure, for instance at 30 to 60 bar or even higher, whereas the cleaning liquid is supplied to other nozzles at a lower pressure, either at an intermediate pressure level of 10 to 30 bar, or at a relatively low pressure, for instance 3 to 10 bar. By the movement of the cleaning device 20 by the device 10, the screw press apparatus 1 is washed in the various zones, zone 1, zone 2 and zone 3. The washing is able to take place also during normal operation of the screw press apparatus 1, i.e. during the production of the sticky product such as a gluten product.

(25) The invention should not be regarded as being limited to the embodiments shown and described in the above, but various combinations and modifications are conceivable.

LIST OF REFERENCE NUMERALS

(26) 1 screw press apparatus 2 outer casing 3 slurry inlet port 3a hopper 4 solids discharge port 5 auger 5a helical conveyor 6 concentric support tube for the screening tube 6a screening tube 7 funnel-shaped section 8 third opening (drainage opening) 9 end wall of outer casing 10 device for axially moving cleaning device 11 motor 12 belt 13 flexible hose support 20 cleaning device 21 first washing pipe 211 nozzle 22 second washing pipe 221 nozzle 23 third washing pipe 231 nozzle 24 fourth washing pipe 241 nozzle 30 rigid co-axial liquid supply pipe 31 water-tight gland 32 hose connection 301 internal supply conduit 302 internal supply conduit