WO2025264162A1

WO2025264162A1 - Apparatus for discharging fibrous material and steam

Info

Publication number: WO2025264162A1
Application number: PCT/SE2025/050492
Authority: WO
Inventors: Patrik Pettersson; Mikael Löfgren; Johan Carlsson
Original assignee: Valmet Oy; Valmet AB
Current assignee: Valmet Technologies Oy; Valmet AB
Priority date: 2024-06-19
Filing date: 2025-05-22
Publication date: 2025-12-26
Anticipated expiration: 2026-12-19
Also published as: SE2430337A1

Abstract

The disclosure relates to an apparatus (1) for discharging a flow of fibrous material and steam from a reactor, wherein the apparatus comprises a screw conveyor (20), a blow line (17), and a blow valve (10) arranged between the conveyor screw (22) and the blow line (17), said screw conveyor (20) comprising a barrel (21) and a conveyor screw (22), and said blow valve (10) comprising front wall (11), a rear wall (12) and side walls (13), and wherein the blow valve comprises an inlet opening (14) arranged in the front wall (11) and being connected to an outlet (23) of the screw conveyor (20); a flow regulating device (30) arranged at the inlet opening (14) of the blow valve (10); an outlet opening (15) arranged in a side wall (13) of the blow valve in a position that is at a distance (d) from the rear wall (12) in a direction toward the front wall; and a fiber build-up space (40) at a rearward end of the blow valve, between the outlet opening and the rear wall, and opposite to the inlet opening (14) of the blow valve.

Description

Apparatus for discharging fibrous material and steam

Technical field

The present disclosure relates to an apparatus for discharging a flow of fibrous material and steam from a reactor having a higher pressure than the zone to which the fibrous material is discharged.

Background art

The present disclosure thus relates to discharging of a flow of fibrous material and steam from pressurized treatment equipment, and is especially directed to equipment for treatment of non-wood plant material, i.e. plant material or bio-material, such as for example annual plants, herbaceous plants, straw, bagasse, etc.

In the processes for treatment and defibration of biomass materials, such as in pulp manufacturing and in the manufacturing of biofuels, blow valves are typically used to control the pressure and/or process flow in process elements such as boilers, reactors and refiners which have inner pressurized process chambers.

Commonly used types of blow valves in the pulp manufacturing industry are shutter valves, gate valves and ball sector valves. Process flows in processes involving treatment of lignocellulosic materials are generally corrosive, high temperature and contain abrasive particulate material such as cellulose fibers and fragments and impurities following with the processed material. A blow valve being continuously exposed to such harsh material will wear overtime and will eventually have to be replaced by a new valve, which is costly and may involve lengthy stop-times in the process. In order to mitigate this, a replaceable inner lining can be arranged in the flow channel, as shown for example in document WO16171604A1. However, it has been found that problems with wear of the inner surfaces of the blow valve may still arise, in particular in processes for treatment of non-wood biomaterials, where the pressure difference over the blow valve may be considerably higher than in treatment of wood material, which may cause extreme wear on the blow valve. To deal with this, attempts have been made to rebuild existing blow valves into static nozzles. However, even though a static nozzle could withstand wear better, a drawback is that the flow through the nozzle cannot be controlled. There is thus a need desire to find solutions for discharge of fibrous material and steam from pressurized equipment in plants for treatment of non-wood material, which can withstand the high wear caused by the flow and can be adapted to control the discharge flow.

Summary

It is an object of the present disclosure to solve at least the above-mentioned problem. According to the invention, there is provided an apparatus for discharging a flow of fibrous material and steam from a reactor, wherein the apparatus comprises a screw conveyor, a blow line, and a blow valve arranged between the conveyor screw and the blow line. The pressure in the reactor is higher than the pressure in the blow valve and blow line. The screw conveyor comprises a barrel and a conveyor screw. The blow valve comprising front wall, a rear wall and side walls. An inlet opening arranged in the front wall of the blow valve is connected to an outlet of the screw conveyor. A flow regulating device comprising an inlet body arranged at the inlet opening of the blow valve. A blow valve outlet opening is arranged in a side wall of the blow valve in a position that is at a distance from the rear wall of the blow valve in a direction toward the front wall. A fiber build-up space is located at a rearward end of the blow valve, between the blow valve outlet opening and the rear wall, and opposite to the inlet opening of the blow valve. As the fibrous material initially flows through the blow valve, fibers are caught and collected in the fiber build-up space in the rearward end of the blow valve where they form a pad of accumulated fibers. Once the fibrous pad has been formed, it will act as a wear lining at the end of the blow valve, protecting the rear end of the valve from high wear.

The flow regulating device comprising an inlet body is designed to be located in a fixed position in relation to the inlet opening of the blow valve such that the inlet opening always is open, e.g. forming a gap between the inlet opening in the front wall of the blow valve and the inlet body, allowing a flow of fibrous material to pass through the inlet opening. The flow regulating device is either arranged permanently in a fixed position or arranged to be adjusted, e.g. controlled by a motor or manually, to shift between different fixed positions depending on process parameters or wear pattern. The position of the flow regulating device may be the same overtime or it may be desired to regularly adjust the position somewhat, e.g. adjust the position once a week, every day or every hour to change the flow pattern such that different surface areas in the blow valve will be subjected to wear from the biomass flow. By the expression fixed position is thus meant one specific fixed position or a set position which may be adjusted manually or by a motor to vary the position between different fixed positions. Hence, when in use, the position of the flow regulating device is intended to be kept in a fixed position but occasionally moved from one fixed position to another fixed position. said flow regulating device (30) arranged permanently in a fixed position or being controlled to be located at a fixed position in relation to the inlet opening (14) of the blow valve (10) forming a gap between the inlet opening (14) and the flow regulating device (30)

The flow regulating device is of particular interest when the pressure difference between the reactor and the blow line is large. A large pressure difference will induce a larger driving force of the biomass flow. The pressure in the reactor may be in a range from 3 to 24 bar, more preferably between 6 and 24 bar and most preferably between 10 and 24 bar. The pressure in the blow line is close to atmospheric pressure but may be somewhat higher, e.g. up to 3 bars, due to an increased pressure from overpressure leaking into the valve from the reactor. The flow regulating device is particularly useful when the pressure difference is above 5 bar, in particular if the pressure difference is above 8 bars. The flow regulating device is in particular useful when the biomass material is contaminated, e.g. with silica particles (e.g. sand) or dirt, which is abrasive. Such contaminants are more frequently occurring in non-wood lignocellulosic biomass, e.g. agricultural waste, than in woody biomass. The flow regulating device is thus in particular useful for non-wood lignocellulosic biomass

The moveably arranged inlet body at the inlet opening of the blow valve is advantageously tapered and has a tip and a lateral surface, and is suitably arranged in the blow valve with the tip directed toward the conveyor screw and forming a gap between the front wall of the blow valve and the lateral surface of the body at the inlet opening of the blow valve. The tapered inlet body may suitably have a substantially flat base surface directed away from the tip.

The flow regulating device can further comprise a shaft connected to the inlet body, and an actuator configured to move the shaft linearly and thereby regulate the position of the inlet body. The actuator may preferably be a step motor actuator. A shaft support bracing may be arranged across the blow valve between opposite side walls and connected to the shaft, and a shaft protecting tube may be arranged coaxially around the shaft and extending between the shaft support bracing and the rear wall of the blow valve.

Wear sleeves may be arranged on an inner surface of the blow valve, preferably at one or more of the front wall at the inlet opening, at a portion of the side walls adjacent the front wall and at the outlet opening. The blow valve may suitably comprise an inlet tube arranged at the inlet opening of the valve and extending toward the screw conveyor, and a wear sleeve may suitably be arranged on an inner surface of the inlet tube. The blow valve may further suitably comprise an outlet tube arranged at the outlet opening of the valve and extending toward the to a blow line, and a wear sleeve may be suitably arranged on an inner surface of the inlet tube.

The present disclosure will become apparent from the detailed description given below. 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 herein disclosed disclosure 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 purpose of describing particular embodiments only, and is not intended to be limiting. For example, the terms "front" and "rear" and the like, are used in the description of the blow valve. In the context of this application "front" refers to the direction toward the screw conveyor, and "rear" refers to the opposite direction, i.e. away from the screw conveyor.

The invention also relates to a method for discharging a flow of fibrous material and steam from a high-pressure reactor to a low-pressure zone wherein an apparatus as disclosed herein is used for treatment of fibrous material. The method may advantageously be used for fibrous material comprising non-wood lignocellulosic biomass. The fibrous material may in this case consist of non-wood lignocellulosic biomass or being a mixture of woody biomass and nonwood lignocellulosic biomass comprising at least 50 % non-wood lignocellulosic biomass The method will of course also work for woody biomass but there will in general be a greater need for non-wood cellulosic biomass which usually comprises more dirt and particles which render the biomass more abrasive.

Brief of the

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and nonlimiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawing.

Figure 1 shows a schematic cross-sectional view of a blow valve included in an apparatus according to the present disclosure.

Detailed description

The present invention relates to an improved apparatus for discharging flow of fibrous material and steam from a reactor for treatment of biomass material, such as non-wood plant material or biomaterial, for example annual plants, herbaceous plants, straw, bagasse, etc. The process flow may typically be a mix of biomass fibers, steam, chemicals and abrasive particles, or the like. The very high pressure in the reactor needed to treat the non-wood biomass material and the solids of the flow exiting the reactor expose the blow valve to harsh and extremely abrasive conditions. The blow valve, therefore, needs to be designed to withstand these conditions to have an acceptable lifetime, but it must at the same time be possible to adjust the valve to properly control the process of treating the biomass material.

The apparatus comprises a screw conveyor, a blow line, and a blow valve arranged between the conveyor screw and the blow line. The screw conveyor transports treated biomass from the reactor to the blow valve, by means of a conveyor screw, ensuring a controlled flow towards the blow valve, where the pressure is rapidly reduced. The blow valve controls the depressurization of the system, the precise control over the depressurization step being vital for the efficiency of the overall treatment process. When the treated biomass reaches the blow valve, the pressure is rapidly reduced, often referred to as a steam explosion, which leads to expansion of steam within the biomass fibers, which contributes to the disruption of the lignocellulosic structure. The flow of steam and fibers leaves the blow valve through the blow line, ready for subsequent processing steps.

The blow valve of the present disclosure comprises a front wall, a rear wall and side walls. The side walls are suitably substantially perpendicular to the front wall, and may preferably form a rounded inner space, such as an essentially cylindrical shape. The absence of corners reduces the wear of the surfaces inside the blow valve. The blow valve has an inlet opening arranged in the front wall, which is directed towards the screw conveyor, and the blow valve inlet is connected to an outlet of the screw conveyor. The blow valve has an outlet opening arranged in a side wall thereof, such that the flow of fibers and steam is forced to bend in order to exit the blow valve. At a rearward end of the blow valve, i.e. opposite to the inlet opening, a fiber build-up space is located, behind the outlet opening. When the flow of fibrous material first passes through the blow valve, it is trapped and gathered in space at the back of the blow valve, which thus functions as a fiber accumulation zone. Here, the fibers are collected to create a dense layer. This layer of fibers then serves as an extra protective barrier at the valve's end, safeguarding it against excessive wear and tear, and thereby increasing its lifetime. The blow valve may be configured to be opened, to allow replacement of worn parts.

A flow regulating device is arranged at the inlet opening of the blow valve. The flow regulating device preferably comprises a moveably arranged inlet body positioned at the inlet opening of the blow valve. The inlet body is advantageously tapered and comprises a tip and a lateral surface and can for example have the shape of a cone. The inlet body is suitably arranged in the blow valve with the tip directed toward the conveyor screw and forming a gap between the front wall of the blow valve and the lateral surface of the body at the inlet opening of the blow valve. The gap between the edges of the inlet opening in the front wall of the blow wall and the lateral surface of the inlet body constitutes the flow channel through which the flow of fibers and steam can enter the blow valve.

The tapered inlet body may preferably have a substantially flat base surface directed away from the tip. When the flow of steam and particles passes through the gap between the front wall of the blow valve and the lateral surface of the inlet body, a wake is created on the leeward side of the inlet body, and the flow will then be drawn into the wake because the pressure is lower there. Thus, the flow does not hit the inner wall of the valve to the same extent and wear on the valve wall is thus reduced.

The flow regulating device may further comprise a shaft connected to the inlet body, and an actuator configured to move the shaft linearly and thereby regulate the position of the inlet body. Thereby, the flow through the blow valve can be adjusted and the steam explosion can be controlled. The shaft is preferably arranged so that it is parallel with and forms an extension of the axis of the inlet body, to give sufficient strength and stability to the inlet body. A shaft support bracing can be arranged across the blow valve between opposite side walls and connected to the shaft, to stabilise the shaft. Further, a shaft protecting tube may be arranged coaxially around the shaft and extending between the shaft support bracing and the rear wall of the blow valve, to protect the shaft from wear.

The actuator may preferably be a step motor actuator. A step motor is an electrical motor that rotates in a series of small angular steps, instead of continuously, and is capable of precisely controlling the position of its shaft in discrete steps, thus allowing precise flow control. Despite the above precautions to protect the blow valve from wear, some positions may still be exposed to high wear, such as at the inlet opening and the inner surface adjacent to the inlet opening and at the outlet opening of the blow valve, where the flow hits the surfaces of the blow valve. In order to further protect the blow valve, wear sleeves functioning as a wear lining may therefore be arranged on an inner surface of the blow valve, preferably at one or more of the front wall at the inlet opening, at a portion of the side walls adjacent the front wall and at the outlet opening. The blow valve may suitably comprise an inlet tube arranged at the inlet opening of the valve and extending toward the screw conveyor to facilitate connection to the outlet of the screw conveyor, and a wear sleeve may suitably be arranged on an inner surface of the inlet tube. The blow valve may further suitably comprise an outlet tube arranged at the outlet opening of the valve and extending toward the to a blow line to facilitate connection to the blow line, and a wear sleeve may suitably be arranged on an inner surface of the inlet tube. The wear sleeves may preferably be detachable and replaceable, to allow extended lifetime for the blow valve. embodiment

The present invention will now be described with reference to the accompanying drawing, in which preferred example embodiments of the disclosure is shown. The invention may, however, be embodied in otherforms 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 shows schematically an apparatus 1 for discharging a flow of fibrous material and steam from a reactor. The apparatus comprises a screw conveyor 20 (shown only partially), a blow line 17, and a blow valve 10 arranged between the conveyor screw 22 and the blow line 17. The screw conveyor 20 comprises a barrel 21 and a conveyor screw 22. The blow valve 10 comprises a front wall 11, a rear wall 12 and side walls 13. The blow valve comprises an inlet opening 14 arranged in the front wall 11, which is connected to an outlet 23 of the screw conveyor 20. A flow regulating device 30 is arranged at the inlet opening 14 of the blow valve 10 and an outlet opening 15 is arranged in a side wall 13 of the blow valve in a position that is at a distance d from the rear wall 12 in a direction toward the front wall. A fiber build-up space 40 is located at a rearward end of the blow valve, between the outlet opening and the rear wall, and opposite to the inlet opening 14 of the blow valve. The flow regulating device 30 preferably comprises a moveably arranged inlet body 31 positioned at the inlet opening 14 of the blow valve.

The inlet body 31 may be tapered and comprise a tip 32 and a lateral surface 33. The body 31 may be arranged in the blow valve with the tip 32 directed toward the conveyor screw 22 to form a gap 34 between the front wall 11 of the blow valve 10 and the lateral surface 33 of the body 31 at the inlet opening 14 of the blow valve 10. The tapered inlet body 31 may have a substantially flat base surface 35 directed away from the tip 32. As illustrated in Fig. 1, the flow of steam and particles is drawn into the wake 41 on the leeward side of the bode 31, because the pressure is lower there. Thus, the flow does not hit the inner wall of the valve to the same extent and wear on the valve wall is thus reduced.

The flow regulating device 30 may further comprise a shaft 36 connected to the inlet body 32, and an actuator 37 configured to move the shaft 36 linearly and thereby regulate the position of the inlet body 31. A shaft support bracing 38 may be arranged across the blow valve 10 between opposite side walls 13 and connected to the shaft, and a shaft protecting tube 39 may be arranged coaxially around the shaft 36 and extending between the shaft support bracing 38 and the rear wall 12 of the blow valve.

Further, wear sleeves 44,45,46 may advantageously be arranged on an inner surface of the blow valve, preferably at one or more of the front wall at the inlet opening, at a portion of the side walls adjacent the front wall and at the outlet opening.

An inlet tube 42 may preferably be arranged at the inlet opening of the valve and extending toward the screw conveyor, and a wear sleeve 44 is then preferably arranged on an inner surface of the inlet tube 42. Similarly, an outlet tube 43 may be arranged at the outlet opening 15 of the valve and extending toward the to a blow line 17, and a wear sleeve 46 may preferably be arranged on an inner surface of the inlet tube 42.

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

Claims

1. An apparatus (1) for discharging a flow of fibrous material and steam from a high pressure reactor, wherein the apparatus comprises a screw conveyor (20), a blow line (17), and a blow valve (10) arranged between the conveyor screw (22) and the blow line (17), and said blow valve (10) comprising a front wall (11), a rear wall (12) and side walls (13), characterized in that the blow valve comprises: an inlet opening (14) arranged in the front wall (11) and being connected to an outlet (23) of the screw conveyor (20); a flow regulating device (30) comprising an inlet body (31) arranged at the inlet opening (14) of the blow valve (10), said flow regulating device (30) and inlet body (31) arranged permanently in a fixed position or arranged to be adjusted, e.g. controlled by a motor or manually, to shift between different fixed positions in relation to the inlet opening (14) of the blow valve (10) forming a gap between the inlet opening (14) and the inlet body (31); an outlet opening (15) arranged in a side wall (13) of the blow valve in a position that is at a distance (d) from the rear wall (12) in a direction toward the front wall; and a fiber build-up space (40) at a rearward end of the blow valve, between the outlet opening and the rear wall, and opposite to the inlet opening (14) of the blow valve.

2. The apparatus of claim 1, wherein the flow regulating device (30) is arranged to be adjusted, e.g. controlled by a motor or manually, to shift between different fixed positions.

3. The apparatus of claim 2, wherein the inlet body (31) is tapered and comprises a tip (32) and a lateral surface (33), said body (31) being arranged in the blow valve with the tip (32) directed toward the conveyor screw (22) and forming a gap (34) between the front wall (11) of the blow valve (10) and the lateral surface (33) of the body (31) at the inlet opening (14) of the blow valve (10).

4. The apparatus of claim 2 or 3, wherein the tapered inlet body (31) has a substantially flat base surface (35) directed away from the tip (32).

5. The apparatus of any one of claims 2-4, wherein the flow regulating device (30) further comprises a shaft (36) connected to the inlet body (32), and an actuator (37) configured to move the shaft (36) linearly and thereby regulate the position of the inlet body (31).

6. The apparatus of claim 5, further comprising a shaft support bracing (38) arranged across the blow valve (10) between opposite side walls (13) and connected to the shaft.

7. The apparatus of claim 6, further comprising a shaft protecting tube (39) arranged coaxially around the shaft (36) and extending between the shaft support bracing (38) and the rear wall (12) of the blow valve.

8. The apparatus of any one of the preceding claims, further comprising wear sleeves (44,45,46) arranged on an inner surface of the blow valve, preferably at one or more of the front wall at the inlet opening, at a portion of the side walls adjacent the front wall and at the outlet opening.

9. The apparatus of any one of the preceding claims, further comprising an inlet tube (42) arranged at the inlet opening of the valve and extending toward the screw conveyor, and preferably further comprising a wear sleeve (44) arranged on an inner surface of the inlet tube

(42).

10. The apparatus of any one of the preceding claims, further comprising an outlet tube

(43) arranged at the outlet opening (15) of the valve and extending toward the to a blow line (17), and preferably further comprising a wear sleeve (46) arranged on an inner surface of the inlet tube (42).

11. A method for discharging a flow of fibrous material and steam from a high-pressure reactor to a low-pressure zone wherein an apparatus according to any of claims 1-10 is used

12. A method for discharging a flow of fibrous material and steam wherein the fibrous material comprises non-wood lignocellulosic biomass.