Device for processing biomass, system comprising such a device, and method of processing biomass

Abstract

The invention relates to a device for releasing moisture from a plant-based biomass, the device comprising a processor having at least two bodies, an input and an output to / from the processor. The bodies can be counter rotating annular disks, provided with passages. Each passage may extend from the input to the output, wherein the at least two bodies are moveable with respect to each other such that their movement forces biomass from the input through the passage towards the output under a first pressure. The at least one passage comprises a first section of a first length and having first cross sectional area, wherein the first cross sectional area is chosen sufficiently small so that in operation the first pressure is sufficiently high to release moisture from the biomass as it leaves the first section, and the first length is chosen sufficiently small to accommodate the release of moisture.

Description

[0001] DEVICE FOR PROCESSING BIOMASS, SYSTEM COMPRISING SUCH A DEVICE, AND METHOD OF PROCESSING BIOMASS

[0002] The invention relates to a device for processing a preferably plant-based biomass.

[0003] Biomass can be used in several ways, for instance as a resource, as fuel - possibly after digestion into biogas, as (animal) food, or as part of a Biomass Carbon Removal and Storage (BiCRS) process. Depending on the application, different processing steps are needed. For instance, for BiCRS and for biogas production, it can be advantageous if the biomass is processed so that at least a part of its moisture content is released. This may facilitate transport and / or biogas production.

[0004] In the prior art, processes exist for removing moisture content, however these are energy intensive. As an example, paper is processed by exposing it to pressures above 200 bar at temperatures of over 200 °C in a steam vessel. When exiting the steam vessel, the biomass is cooled and the pressure lowered, thereby the internal structure of e.g. cells in the biomass and releasing moisture.

[0005] The invention has as its aim to provide less energy intense way for processing biomass. Said aim is achieved by a device according to the independent device claim.

[0006] By mutual movement of the at least two bodies, biomass is forced through the at least one passage, thereby passing through its first section. As a result, the biomass is temporarily exposed to a relatively high pressure, because the first section imposes a certain resistance to “flow” and thus a pressure drop exists across the first section. When the biomass leaves the first section, said pressure is released suddenly, thereby causing a pressure explosion, which destroys cell walls of cells present in the biomass. As a result, moisture in the cells is released.

[0007] Said principle relies on a sufficiently high pressure to arise when the biomass is forced through the at least one passage. The pressure can be increased by reducing the cross sectional area of the first section. Moreover, the first length must be sufficiently small so that the biomass travelling through the first section is exposed to a relatively sudden pressure drop as it leaves the first section. This relatively sudden pressure drop causes the pressure explosion mentioned above.

[0008] Depending on the moisture contents of the biomass to be processed, suitable quantities for the first cross sectional area and the first length the can be chosen, for instance in view of the force generated by the moving bodies. It is no problem for the skilled person to gradually decrease the first cross sectional area and / or the first length until a satisfactory result is achieved, although exemplary dimensions will be given below.

[0009] In most cases, for instance for biomass with a moisture content of above 18%, a pressure in the first section of approximately 10 bar is sufficient, assuming that the pressure beyond the first section is approximately atmospheric (1 bar). The pressure could be increased to 30 bar if desired. Of course it is alternatively possible to increase the force generated by the bodies moving together, in order to increase the pressure in the first section.

[0010] It is noted that although the term “flow” is used, the biomass is typically not fluid. In fact, the biomass can be freshly cut and / or crushed crops, such as grass, weeds, etc.

[0011] It is advantageous if the passage further comprises a second section further towards the outlet than the first section, the second section having a larger cross sectional area.

[0012] Accordingly, the passage can be longer without significantly influencing the operation thereof. A longer passage allows making a more rigid body, because more material can be used. The rigidity of the body may be important due to the high pressures involved.

[0013] The at least one passage comprises an intermediate section of tapering cross section between the first and second section. The taper can be used to prevent excessive wear to the passage. The tapering can be sufficiently “quick” so as to not influence the operation of the passage. In fact, a taper angle defined between the intermediate section and a longitudinal axis defined by the passage may be between 100° and 140°, preferably between 110° and 130°, more preferably between 115° and 125°, most preferably around 120°.

[0014] The at least one passage may further comprise an inlet section on a side of the first section facing the inlet, the inlet section being relatively wide as compared to the first section. Such an inlet section allows easy introduction of biomass into the passage an aids compression.

[0015] The first section may have a length of at most 5 millimetre, preferably at most 3 millimetres, most preferably around 2 millimetres. Such lengths are in typical circumstances sufficiently small to cause a pressure drop sufficient for pressure exploding the biomass.

[0016] A cross section of the at least one passage may substantially circular at any point along a length of said at least one passage. Such passages are easily made, e.g. by drilling, and are capable of withstanding strong forces.

[0017] The first section has a characteristic cross sectional dimension, such as a diameter, of between 15 and 5 millimetres, preferably between 12 and 8 millimetres, more preferably around 10 millimetres. Such a dimension is sufficiently small under typical circumstances to generate a pressure sufficient for exploding the biomass.

[0018] The second section may have a characteristic cross sectional dimension, such as a diameter, of between 10 and 20 millimetres, preferably between 12 and 15 millimetres, more preferably around 14 millimetres. This allows in typical circumstances expansion of the biomass downstream of the first section, thereby causing a pressure explosion.

[0019] Preferably, at least one, preferably all of the at least two bodies are an annular disks. Annular disks may be easily used, e.g. by rotation for offering multiple passages in succession so as to create a near-continuous biomass explosion process. The at least two bodies may all be annular disks, and the disks may be configured for counter rotation.

[0020] The disks can accordingly be rotated with respect to each other so as to force biomass between the disks, and then forcing it in a passage.

[0021] Forthat purpose, each passage in an annular disk may run from a circumferential outer side edge to a circumferential inner side edge of the annular disk.

[0022] To provide a compact device with higher capacity, two stacks of such annular disks are provided.

[0023] At least one of the at least two bodies may of a second type, and each body of the second type is solid. Accordingly, bodies of the second type can be used as a ram to push biomass into the passages in the other body.

[0024] Each body of the second type may comprises a ribbed surface for cooperation with another body. This allows pulling the biomass in between the disks and enhances forcing the biomass into the passages.

[0025] Bodies of the first type may have a radius that is smaller than that of bodies of the second type. Accordingly, a space exists radially outside of the first bodies, in which biomass can be temporarily received for forcing it in the passages. In particular, a chamber may be formed by at least the bodies radially outside of the first bodies in order to hold and compress the biomass into the passages.

[0026] As an example, bodies of the first type may have a diameter of between 1100 and 850 millimetres, preferably between 1000 and 900 millimetres, more preferably around 960 millimetres. Given these dimensions, a device can be obtained having sufficient material to resist the required forces. Bodies of the second type may have a diameter of between 1200 and 800 millimetres, preferably between 1100 and 900 millimetres, more preferably around 1000 millimetres.

[0027] Each stack may comprise altematingly bodies of the first and second type. Accordingly, each two second bodies of a stack can be used to create side walls radially outside a first body in between these two second bodies, for creating a pressure chamber for forcing the biomass through the passages.

[0028] A transporter may be further provided, configured for providing pressurized biomass at the input. The transporter may be e.g. a screw transporter. Precompression enhances feeding of the biomass to the bodies.

[0029] The device may additionally or alternatively comprise a funnel configured for receiving processed biomass from the at least one passage and coupled to the output. Accordingly, biomass from several passages can be easily caught and brought towards the output. For this purpose, the annular wheels may be placed with their axes of rotation substantially vertically.

[0030] The device may further comprise a heater for heating the at least two bodies and / or the biomass. Using said heating, pressure explosion may be enhanced, releasing more moisture.

[0031] The invention also relates to a method defined in the independent method claim.

[0032] The method essentially describes that performed by the device as described herein. In any case, the biomass is forced through a passage with a section of sufficiently small cross sectional area of sufficiently short length to cause the above -de scribed pressure explosion for releasing moisture. Said forcing may be performed by two mutually moving bodies, for instance using a device as described herein. The advantages described above apply also to the method.

[0033] Said forcing may thus be performed using a perforated annular disk and a counter rotating annular disk.

[0034] A precompression may be used before step a) to a pressure of between 1 - 3 atm, for enhancing the pressure explosion and / or the feeding of the biomass.

[0035] The relatively high pressure is preferably larger than 8 bar, preferably larger than 9 bar, preferably 10 bar or larger, and / or wherein the relatively low pressure is approximately equal to atmospheric pressure. Even larger pressures may also be used, e.g. at least 30 bar. In fact under demanding circumstances, the relatively high pressure may be raised to above 100 bar, 150 or 170 bar.

[0036] However, normally, the relatively high pressure is smaller than 100 bar, preferably smaller than 50 bar.

[0037] The method may be used to process biomass for BiRCS or for biogas production, both applications benefitting from the release of moisture from cells in the biomass.

[0038] Typically, the method is performed at an operating temperature, wherein said operating temperature is lower than 100 degrees Celsius, preferably lower than 50 degrees Celsius, more preferably lower than 40 degrees Celsius. However, it is also possible to increase the temperature to above 100 °C, to above 150 °C, or to above 200 °C.

[0039] The biomass to be processed may have a relatively high moisture content, e.g. of at least 18%, preferably at least 20%, more preferably at least 50%.

[0040] The invention will be further elucidated with reference to the attached drawings, in which: Figure 1 shows schematically the components of a device as described herein;

[0041] Figure 2 shows schematically a perspective view of two stacks of annular disks of the device;

[0042] Figures 3A - 3B show schematically details of annular disks; Figure 4 shows schematically the shape and dimensions of a passage in the annular disks.

[0043] Throughout the figures, like elements are referred to using like reference numerals.

[0044] Figure 1 shows a device 1 for releasing moisture from a preferably plant-based biomass. The device comprises a processor 2 having two bodies 5. An input 6 and an output 7 are generally shown. The device 1 also comprises a transporter 3 configured for providing pressurized biomass at the input 6. Two funnels 4 are further shown to collect biomass from the processor 2 to provide it at the output 7. Of course, a single funnel could be used instead.

[0045] In figure 2 and figures 3A and 3B, details of the processor 2 can be seen. Firstly, it is noted that the processor 2 comprises two stacks 5 of annular disks 8, 9, suffixed with 1 or 2 depending on whether they are part of first or second stack. The stacks 5, and thus the disks 8, 9 are configured for counter rotation, as is shown by rotational directions R_1 and R_2 for the two stacks 5 respectively. Each set of disks 8, 9 from different stacks 5 acts as a set of two bodies which are moveable with respect to each other such that their movement forces biomass from the input 6 towards the output 7 under a first pressure through passages 10 present in bodies 8 of a first type. The passages 10 run from on outer circumference 11 of the disks 8, 9 to the inside 17.

[0046] Now moving to figure 4, details of the passages 10 are first discussed. As mentioned above, the passages 10 are arranged in at least the disk of the first type 8. A single passage 10 is shown in cross section in figure 4. The passage 10 comprises a first section 13, which is relatively narrow, having a diameter of d_l. A second section 14 is also present, of a larger diameter d_2. Between the two, an intermediate and tapering section 15 is provided, with a tapering angle of 120°. d_l can be 10 mm, whilst d_2 is 14 mm. An inlet section 16 is also present, which acts as a funnel for accepting biomass. The first section 13 has a length L_1 that is relatively small, e.g. 3 mm. The passage 10 runs from the outside 11 of the disk 8-1 to the inside 17.

[0047] Moving now to figures 3A and 3B, it is noted that stacks 5 of disks are formed by alternating disks of the first 8 and second 9 type. Disks of the first type 8 comprise the passages, whilst disks of the second type 9 are solid. The disks of the first type 8 are smaller than those of the second type 9. The stacks 5 are laid out in an staggered pattern with respect to each other, so that a disk of a first type 8-1 of one stack, interfaces and cooperates with a disk of a second type 9-2 of the other stack, and vice versa. Each two consecutive disks of the second type 9-2, 9-2, enclose, together with an intermediate disk of the second type 9-1 of the other stack 5, a space 13 radially outside the disk of the first type 8-2 of the first mentioned stack. By counter rotating the disks 8, 9, biomass is forced into the space 13 and then through the passages 10, one after the other. The disks of the second type 9 are for this purpose provided with ribs along their outer circumference 11. The device is further in accordance with the claims, and can performed the method set out therein.

Claims

Claims1. Device for releasing moisture from a preferably plant-based biomass, the device comprising - a processor having at least two bodies;- an input to the processor for receiving unprocessed biomass; and- an output from the processor for providing processed biomass,wherein at least one of the at least two bodies is of a first type, each body of the first type comprising at least one passage through a part of said body, the at least one passage extending from the input to the output, wherein the at least two bodies are moveable with respect to each other such that their movement forces biomass from the input through the passage towards the output under a first pressure,wherein the at least one passage comprises a first section of a first length and having first cross sectional area,wherein the first cross sectional area is chosen sufficiently small so that in operation the first pressure is sufficiently high to release moisture from the biomass as it leaves the first section, and the first length is chosen sufficiently small so as to accommodate the release of moisture .

2. Device according to the previous claim, wherein the passage comprises a second section further towards the output than the first section, the second section having a larger cross sectional area.

3. Device according to the previous claim, wherein the at least one passage comprises an intermediate section of tapering cross section between the first and second section.

4. Device according to the previous claim, wherein a taper angle defined between the intermediate section and a longitudinal axis defined by the passage is between 100° and 140°, preferably between 110° and 130°, more preferably between 115° and 125°, most preferably around 120°.

5. Device according to any of the preceding claims, wherein the at least one passage further comprises an inlet section on a side of the first section facing the inlet, the inlet section being relatively wide as compared to the first section.

6. Device according to any of the preceding claims, wherein the first section has a length of at most 5 millimetre, preferably at most 3 millimetres, most preferably around 2 millimetres.

7. Device according to any of the preceding claims, wherein a cross section of the at least one passage is substantially circular at any point along a length of said at least one passage.

8. Device according to any of the preceding claims, wherein the first section has a characteristic cross sectional dimension, such as a diameter, of between 15 and 5 millimetres, preferably between 12 and 8 millimetres, more preferably around 10 millimetres.

9. Device according to any of the preceding claims, wherein the second section has a characteristic cross sectional dimension, such as a diameter, of between 10 and 20 millimetres, preferably between 12 and 15 millimetres, more preferably around 14 millimetres.

10. Device according to any of the preceding claims, wherein at least one, preferably all of the at least two bodies are an annular disks.

11. Device according to the previous claim, wherein the at least two bodies are all annular disks, and wherein the disks are configured for counter rotation.

12. Device according to any of claims 10 - 11, wherein each passage in an annular disk runs from a circumferential outer side edge to a circumferential inner side edge of the annular disk.

13. Device according to any of claims 10 - 12, wherein two stacks of such annular disks are provided.

14. Device according to any of the preceding claims, wherein at least one of the at least two bodies is of a second type, and each body of the second type is solid.

15. Device according to any of the preceding claims, wherein each body of the second type comprises a ribbed surface for cooperation with another body.

16. Device according to at least claim 14 and optionally any of the preceding claims, wherein bodies of the first type have an outer radius that is smaller than that of bodies of the second type.

17. Device according to at least claim 10 and optionally any of the preceding claims, wherein bodies of the first type have a diameter of between 1100 and 850 millimetres, preferably between 1000 and 900 millimetres, more preferably around 960 millimetres.

18. Device according to at least claim 10 and 14 and optionally any of the preceding claims, wherein bodies of the second type have a diameter of between 1200 and 800 millimetres, preferably between 1100 and 900 millimetres, more preferably around 1000 millimetres.

19. Device according to at least claim 14 and optionally any of the preceding claims, wherein each stack comprises altematingly bodies of the first and second type.

20. Device according to any of the preceding claims, further comprising a transporter configured for providing pressurized biomass at the input.

21. Device according to any of the preceding claims, further comprising a funnel configured for receiving processed biomass from the at least one passage and coupled to the output.

22. Device according to any of the preceding claims, further comprising a heater for heating the at least two bodies and / or the biomass.

23. Method of releasing moisture from a preferably plant-based biomass, the method comprising the steps of:a) exposing the biomass to a relatively high pressure, followed byb) exposing the biomass to a relatively low pressure, thereby causing a sudden drop in pressure so as to damage cell walls in the biomass;wherein steps a) and b) are performed by forcing the biomass through a passage with a section of sufficiently small cross sectional area of sufficiently short length.

24. Method according to the previous claim, wherein forcing is performed using a perforated annular disk and a counter rotating disk.

25. Method according to any of the preceding method claims, further comprising precompressing the biomass before step a) to a pressure of between 1 - 3 atm.

26. Method according to any of the preceding method claims, wherein the relatively high pressure is larger than 8 bar, preferably larger than 9 bar, preferably 10 bar or larger, and / or wherein the relatively low pressure is approximately equal to atmospheric pressure.

27. Method according to any of the preceding method claims, wherein the relatively high pressure is smaller than 100 bar, preferably smaller than 50 bar.

28. Method according to any of the preceding method claims, for processing biomass for BiRCS or for biogas production.

29. Method according to any of the preceding method claims, wherein the method is performed at an operating temperature, wherein said operating temperature is lower than 100 degrees Celsius, preferably lower than 50 degrees Celsius, more preferably lower than 40 degrees Celsius.

30. Method according to any of the preceding method claims, wherein the relatively high pressure is larger than 100 bar, preferably larger than 150 bar, preferably 170 bar or larger, and / or wherein the passage and / or the biomass is heated, preferably to above 100 °C, to above 150 °C, or to above 200 °C.

31. Method according to any of the preceding method claims, wherein the biomass to be processed has atotal moisture content of at least 18%, preferably at least 20%, more preferably at least 50%.

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