WO2025155231A1

WO2025155231A1 - Feeding arrangement for feeding of non-wood plant material

Info

Publication number: WO2025155231A1
Application number: PCT/SE2025/050020
Authority: WO
Inventors: Christer HÄGGLUND
Original assignee: Valmet Oy; Valmet AB
Current assignee: Valmet Technologies Oy; Valmet AB
Priority date: 2024-01-15
Filing date: 2025-01-13
Publication date: 2025-07-24
Anticipated expiration: 2026-07-15
Also published as: SE2430009A1; SE547764C2

Abstract

A feeding arrangement (100) for feeding non-wood plant material to a treatment vessel (10), said feeding arrangement comprising a plug screw feeder (20) configured to feed plant material to the treatment vessel (10), and a force feeder (30) configured to feed plant material to the plug screw feeder (20), wherein the plug screw feeder (20) comprises a plug feeder screw (21) arranged in a plug screw feeder barrel (22) and has a plant material receiving inlet (23) and a plant material plug discharge outlet (24); and the force feeder (30) comprises a force feeder screw (31) arranged in a force feeder barrel (32) and has a plant material receiving inlet (33) and a plant material discharge outlet (34), characterized in that the inlet (23) of the plug screw feeder (20) is located on an upper side of the plug screw feeder (20) and the force feeder (30) is arranged with its plant material discharge outlet above the plug screw feeder inlet (23), and wherein an inlet housing (40) is arranged between the force feeder (30) and the plug screw feeder (20), said inlet housing (40) having an inlet opening (42) connected to the force feeder outlet (34) and an outlet opening (41) connected to the plug screw feeder inlet (23).

Description

Feeding arrangement for feeding of non-wood plant material

TECHNICAL FIELD

The present disclosure relates to feeding of non-wood plant material to a treatment vessel, more specifically to a feeding arrangement for feeding of non-wood plant material.

BACKGROUND ART

Feeding arrangements including a plug screw feeder are commonly used in process equipment for treatment of plant material that is to be treated in a pressurized vessel or reactor, especially in treatment of wood chips. In the plug screw feeder, the plant material is compressed to remove excess water and is further compressed into a plug before it enters the treatment reactor. However, when the plant material is non-wood material, it’s more difficult to obtain effective feeding of the material to the plug screw feeder and a force feeder may be needed to obtain precompression of the material prior to entry in the plug screw feeder. One example of an arrangement comprising a force feeder is disclosed in document W013126007A1. However, there is a need for further enhancing feeding of non-wood plant material to obtain improved compression operation in the plug screw feeder.

SUMMARY OF THE INVENTION

It is an object of the present disclosure to obtain improved compression operation in a plug screw feeder when compressing non-wood plant material. The present disclosure thus relates to a feeding arrangement for feeding non-wood plant material to a treatment vessel. The feeding arrangement comprises a plug screw feeder configured to feed plant material to the treatment vessel and a force feeder configured to feed plant material to the plug screw feeder. The plug screw feeder comprises a plug feeder screw arranged in a plug screw feeder barrel and has a plant material receiving inlet and a plant material plug discharge outlet. The force feeder comprises a force feeder screw arranged in a force feeder barrel and has a plant material receiving inlet and a plant material discharge outlet. The plant material receiving inlet of the plug screw feeder is arranged such that it is located on an upper side of the plug screw feeder and the force feeder is arranged with its plant material discharge outlet above the plug screw feeder inlet, and thereby an improved plug having more even density can be obtained, and wear of the equipment can be reduced. The plug screw feeder is preferably arranged such that its central axis is located in a first substantially horizontal plane, and the force feeder is preferably arranged such that its central axis is located in a second substantially horizontal plane, which is located vertically above said first horizontal plane.

The feeding arrangement may advantageously comprise an inlet housing arranged on top of the plug screw feeder inlet and having an outlet opening connected to plug screw feeder inlet, said inlet housing further having an inlet opening connected to the force feeder outlet. The inlet housing preferably comprises a substantially vertical wall member, which is directed toward the force feeder outlet and in which the inlet opening of the inlet housing is provided, and preferably further comprises a curved wall member extending between an upper part of the vertical wall member and an opposite side of the inlet housing at the plug screw feeder plant material receiving inlet. The curved wall member is suitably flexible, and a lower end thereof can advantageously be moved in a direction toward or away from the vertical wall member of inlet housing. An actuator is preferably arranged at the lower end of the curved wall member.

The plant material receiving inlet of the plug screw feeder preferably has a width in a direction perpendicular to the central axis of the plug feeder screw that is the same or greater than the total diameter of the plug feeder screw at the inlet opening. The lower end of the flexible curved wall member is suitably positioned at a distance from the vertical wall member of the inlet housing, said distance being 60-100% of the width of the inlet of the plug screw feeder.

The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure. Hence, it is to be understood that the solution described herein is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The feeding arrangement of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings

Figure 1 is a schematic cross-sectional view of a feeding arrangement according to the present disclosure. Figure 2 is a top view of a feeding arrangement according to the present disclosure and also shows a plant material treatment vessel to which the feeding arrangement is connected.

Figure 3 is a perspective view of the feeding arrangement in Fig. 2.

DETAILED DESCRIPTION

The present disclosure thus relates to a feeding arrangement for feeding non-wood plant material to a treatment vessel, such as for example equipment for production of bio ethanol. The term non-wood plant material refers to plant material or bio-material which is not defined as wood, and can be for example annual plants, herbaceous plants, straw, bagasse, etc.

The feeding arrangement of the present disclosure comprises a plug screw feeder and a force feeder. The force feeder is arranged to feed plant material to the plug screw feeder and comprises a plant material receiving inlet and a plant material discharge outlet, and a force feeder screw arranged in a force feeder barrel, in which pre-compression of the plant material is obtained. Non-wood plant materials are typically bulky and can have considerable network strength such that they easily form skeins or balls of tangled stems which complicate feeding of the material to the plug screw feeder. Due to the high network strength of the non-wood plant material, gravity may not be sufficient to feed the plant material to the plug screw feeder. The force feeder enables plant material to be fed effectively to the plug screw feeder.

The plug screw feeder is configured compress plant material into a plug and feed it to a treatment vessel. The treatment vessel may typically be a pressurized vessel, and the compressed plant material plug serves as a seal toward the pressurized vessel, and it is thus important to avoid leakage in the plug, to reduce the risk of back flow of high-pressure steam or treatment media from the treatment vessel. The plug screw feeder comprises a plug feeder screw arranged in a plug screw feeder barrel, a plant material receiving inlet and a plant material plug discharge outlet. The plant material receiving inlet of the plug screw feeder is arranged such that it is located on an upper side of the plug screw feeder, and thus receives the plant material from above. The force feeder is arranged in the feeding arrangement such that its plant material discharge outlet is located above the plug screw feeder inlet. The pre-compressed plant material can thus be fed to the plant material receiving inlet of the plug screw feeder from above. By doing so, the pre-compressed material can be evenly distributed over an inlet end of the plug feeder screw. Feeding pre-compressed plant material from above thus results in more even plug density compared to feeding pre-compressed material through an inlet opening on the side of the plug feeder screw. Thereby, leakage due to uneven plug density can be avoided. Moreover, very high mechanical forces are applied in the plug screw feeder. When feeding bio material through an inlet opening on the side, there is a risk that the fed plant material does not travel sufficiently with the screw in the plug screw feeder, which can cause leakage and uneven force distribution over the screw and damage it since there may be a risk that the plug screw bend and gets caught by the screw barrel. By instead distributing the pre-compressed plant material to the plug feeder screw evenly from above according to the present invention, it can be ensured that forces applied on the parts of the plug screw feeder are balanced, thus reducing the risk of wear and damage of the plug feeder screw equipment. The plug feeder screw and the force feeder screw are preferably arranged substantially perpendicular to each other, so that their respective rotational axes are perpendicular to each other. The perpendicular setup can reduce the risk of material bridging which can occur if material forms an arch or bridge over the feeding mechanism and thereby improve material flow through the feeding arrangement.

One or both of the plug screw feeder and the force feeder can be arranged in an inclined position, but the plug screw feeder is preferably arranged such that its central axis is located in a first substantially horizontal plane, and the force feeder is preferably arranged such that its central axis is located in a second substantially horizontal plane, which is located vertically above said first horizontal plane. Thereby, the screws of the plug screw feeder and/or the force feeder can be oriented substantially horizontally. By “arranged in a substantially horizontal plane” is meant that the central axis of the plug screw feeder or force feeder is located in a plane which deviates from the horizontal plane by an angle 0-20°, preferably 0-10°, more preferably 0-5°. Horizontal screws facilitate feeding at the inlet of the force feeder and plug screw feeder respectively. Nonwood plant material typically has fiber lengths of approximately 5-7 cm, which is greater than for wood chips which typically has fibers of 2-3 cm. By using the force feeder, there is no need to cut the plant material to shorter lengths than approximately 5-7 cm, and an unnecessarily costly cutting operation can thus be avoided.

The plug screw feeder and/or the force feeder may include tapering or conical screws arranged in tapering barrels. A conical shape of the screws allows for a gradual compression of the plant material along the screw axis and can contribute to more efficient and uniform compression process compared to screws with constant diameter.

The feeding arrangement may advantageously comprise an inlet housing arranged on top of the plug screw feeder inlet and having an outlet opening connected to plug screw feeder inlet, said inlet housing further having an inlet opening connected to the force feeder outlet. During operation, the inlet housing will be substantially filled with rather compressed plant material coming from the force feeder and being pressed toward the plug feeder screw at the inlet of the plug screw feeder. Provision of the inlet housing facilitates feeding of plant material to the plug screw feeder since it allows the pre-compressed plant material from the force feeder to expand equally on both sides of the plug feeder screw, which improves even plug density, and the plant material inlet opening of the plug screw feeder can be made larger than the outlet of the force feeder, which means that the pre-compressed plant material can be pressed toward a larger surface of the plug feeder screw, than the area of the outlet of the force feeder. The larger inlet opening in the plug screw feeder also allows the space between adjacent screw threads to evenly and sufficiently filled with pre-compressed bio material. The plant material receiving inlet of the plug screw feeder preferably has a width in a direction perpendicular to the central axis of the plug feeder screw that is the same or greater than the total diameter of the plug feeder screw at the inlet opening, and the outlet opening of the inlet housing is preferably configured to have approximately the same width as the inlet of the plug screw feeder to ensure that precompressed plant material can be properly distributed.

The inlet housing may preferably comprise a substantially vertical first wall member directed toward the force feeder outlet, in which the inlet opening of the inlet housing is provided, and preferably further comprises a curved wall member extending between an upper part of the vertical wall member and an opposite side of the inlet housing at the plug screw feeder plant material receiving inlet. The substantially vertical first wall member is suitably arranged at one edge of the inlet opening of the plug screw feeder. A substantially vertical second wall member and a top wall member may suitably be arranged to cover and protect the curved wall member. Vertical walls members are preferably arranged at the front and rear ends of the inlet housing. The configuration of the inlet housing reduces the risk of wear on the last screw threads of the force feeder screw (i.e. the screw threads that are located closest to the discharge outlet of the force feeder) since the pre-compressed plant material is not fed directly into the plug screw feeder, but instead into the inlet housing, such that mechanical force on the last screw threads is reduced. The curved wall helps the pre-compressed plant material to move toward the plug feeder screw. The lower end of the flexible curved wall member is suitably positioned at a distance from the vertical wall member of the inlet housing, said distance being 60-100% of the width of the inlet of the plug screw feeder, so that the outlet of inlet housing is smaller or equal to the size of the inlet of the plug screw feeder. The distance between the lower end of the curved wall member and the vertical wall member should preferably not exceed the width of the inlet of the plug screw feeder to avoid exposure of an edge at the inlet of the plug screw feeder that may disturb the feeding of pre-compressed material.

The curved wall member may suitably be flexible, and a lower end thereof can advantageously be moved in a direction toward from the vertical wall member of inlet housing to adjust the size of the space inside the inlet housing and thus control feeding of pre-compressed plant material into the plug screw feeder. The curved wall member is suitably configured to allow adjustment of the distance between the lower end of the flexible curved wall member to the vertical wall member of the inlet housing to correspond to 65-90% of the width of the inlet of the plug screw feeder. When the lower end of the flexible curved wall member is adjusted to a position between the edge of the inlet of the plug screw feeder opposite to the vertical wall member and the axis of the plug screw feeder, e.g. to a position at 70-90% of the width of the inlet of the plug screw feeder, the distribution of pre-compressed material on both sides of the plug feeder screw can be further improved. The upper end of the curved wall member may be fixed to the upper end of the vertical wall member, e.g. by welding.

An actuator, such as an adjustment screw, may preferably be arranged at the lower end of the curved wall member to assist adjustment of the size of the space inside the inlet housing. One or more of the inlet housing wall members may preferably include an openable closing arranged to allow the inlet housing to be opened for inspection of the plug feeder screw when the feeding arrangement is not in operation.

A preferred example embodiment of the feeding arrangement described above is illustrated in Figures 1-3. The feeding arrangement may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

Figure 1 is a cross-sectional view of a feeding arrangement 100. Figures 2-3 show the arrangement from above and from the side respectively and also show the plant material treatment vessel 10 to which the feeding arrangement is connected. The feeding arrangement 100 for feeding non-wood plant material to a treatment vessel 10 comprises a plug screw feeder 20 configured to feed plant material to the treatment vessel 10, and a force feeder 30 configured to feed plant material to the plug screw feeder 20. The plug screw feeder 20 comprises a plug feeder screw 21 arranged in a plug screw feeder barrel 22 and further includes a plant material receiving inlet 23 and a plant material plug discharge outlet 24. The force feeder 30 comprises a force feeder screw 31 arranged in a force feeder barrel 32 and has a plant material receiving inlet 33 and a plant material discharge outlet 34. The inlet 23 of the plug screw feeder 20 is located on an upper side of the plug screw feeder 20 and the force feeder 30 is arranged with its plant material discharge outlet 34 above the plug screw feeder inlet 23.

As shown in the drawings, the plug screw feeder 20 is arranged with its central axis 25 in a first substantially horizontal plane 101 , and the force feeder 30 is arranged with its central axis 35 in a second substantially horizontal plane 102, which is located vertically above said first horizontal plane. The feeding arrangement comprises an inlet housing 40 arranged on top of the plug screw feeder inlet 23. The inlet housing has an outlet opening 41 connected to plug screw feeder inlet 23, said inlet housing 40 further having an inlet opening 42 connected to the force feeder outlet 34. The inlet housing 40 comprises a substantially vertical wall member 43, which is directed toward the force feeder outlet 34 and in which the inlet opening 42 of the inlet housing 40 is provided. The inlet housing 40 further comprises a curved wall member 44 extending between an upper part of the vertical wall member 43 and an opposite side of the inlet housing at the plug screw feeder plant material receiving inlet 23. A substantially vertical second wall member 47 and a top wall member 48 may suitably be arranged to cover and protect the curved wall member. Vertical walls members are preferably arranged at the front and rear ends 49, 50 of the inlet housing. The curved wall member 44 is preferably flexible and a lower end 45 thereof can be moved in a direction toward or away from the vertical wall member 43 of inlet housing 40, and this can be controlled by an actuator 46, such as a screw actuator, arranged at the lower end 45 of the curved wall member 44. As shown best in Fig. 1 , the plant material receiving inlet 23 of the plug screw feeder 20 can have a width in a direction perpendicular to the central axis of the plug feeder screw 21 that is the same or greater than the total diameter of the plug feeder screw 21 at the inlet opening 23, and the lower end (45) of the flexible curved wall member (44) is suitably positioned at a distance from the vertical wall member (43) of the inlet housing (40), said distance being 60-100% of the width of the inlet (23) of the plug screw feeder (20).

The person skilled in the art realizes that the present disclosure is not limited to the preferred embodiments described above but realizes that modifications and variations are possible within the scope of the appended claims.

Claims

1. A feeding arrangement (100) for feeding non-wood plant material to a treatment vessel (10), said feeding arrangement comprising a plug screw feeder (20) configured to feed plant material to the treatment vessel (10), and a force feeder (30) configured to feed plant material to the plug screw feeder (20), wherein the plug screw feeder (20) comprises a plug feeder screw (21) arranged in a plug screw feeder barrel (22) and has a plant material receiving inlet (23) and a plant material plug discharge outlet (24); and the force feeder (30) comprises a force feeder screw (31) arranged in a force feeder barrel (32) and has a plant material receiving inlet (33) and a plant material discharge outlet (34), characterized in that the inlet (23) of the plug screw feeder (20) is located on an upper side of the plug screw feeder (20) and the force feeder (30) is arranged with its plant material discharge outlet above the plug screw feeder inlet (23), wherein the inlet (23) of the plug screw feeder (20) has a width in a direction perpendicular to the central axis of the plug feeder screw (21) that is the same or greater than the total diameter of the plug feeder screw (21) at the inlet opening (23); and wherein an inlet housing (40) is arranged between the force feeder (30) and the plug screw feeder (20), said inlet housing (40) having an inlet opening (42) connected to the force feeder outlet (34) and an outlet opening (41) connected to the plug screw feeder inlet (23).

2. The feeding arrangement of claim 1 , wherein the inlet housing (40) comprises a substantially vertical wall member (43), which is directed toward the force feeder outlet (34) and in which the inlet opening (42) of the inlet housing (40) is provided.

3. The feeding arrangement of claim 2, wherein inlet housing (40) further comprises a curved wall member (44) extending between an upper part of the vertical wall member (43) and an opposite side of the inlet housing at the plug screw feeder plant material receiving inlet (23).

4. The feeding arrangement of claim 3, wherein the lower end (45) of the curved wall member

(44) is positioned at a distance from the vertical wall member (43) of the inlet housing (40), said distance being 60-100% of the width of the inlet (23) of the plug screw feeder (20).

5. The feeding arrangement of claim 4, wherein the curved wall member (44) is flexible, and a lower end (45) thereof can be moved in a direction toward from the vertical wall member (43) of the inlet housing (40).

6. The feeding arrangement of claim 5, further comprising an actuator (46) arranged at the lower end (45) of the curved wall member (44).

7. The feeding arrangement of any one of the preceding claims, wherein a central axis (25) of the plug screw feeder (20) is arranged in a first substantially horizontal plane (101 ), and a central axis (35) of the force feeder (30) is arranged in a second substantially horizontal plane (102), which is located vertically above said first horizontal plane.