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EP-4735781-A1 - A DISCHARGE VALVE

EP4735781A1EP 4735781 A1EP4735781 A1EP 4735781A1EP-4735781-A1

Abstract

A discharge valve (1) comprising a valve housing (2) connectable to a process element (10) having a pressurized interior process volume, said discharge valve (1) comprising a flow channel (3) having a longitudinal centre axis (A) and extending from an inlet (5) of the flow channel to an outlet (6) thereof, and being arranged to be in fluid communication with a pressurized interior process volume of said process element (10); and a first valve member (4) being arranged to protrude into the flow channel (3), and a second valve member (7) being arranged to protrude into the flow channel from a different direction than the first valve member.

Inventors

  • WALLIN, PER

Assignees

  • Valmet AB

Dates

Publication Date
20260506
Application Date
20240624

Claims (14)

  1. 1. A discharge valve (1) comprising a valve housing (2) connectable to a process element (10) having a pressurized interior process volume, said discharge valve (1) comprising a flow channel (3) having a longitudinal centre axis (A) and extending from an inlet (5) of the flow channel to an outlet (6) thereof, and being arranged to be in fluid communication with a pressurized interior process volume of said process element (10); and a first valve member (4) being arranged to protrude into the flow channel (3), characterized in that a second valve member (7) is arranged to protrude into the flow channel from different direction that the first valve member.
  2. 2. The discharge valve of claim 1, wherein said first and second valve members have the shape of a cylindrical body.
  3. 3. The discharge valve of claim 2, wherein the housing (2) comprises a first containment portion (20) connected to the flow channel (3) and from which the first valve member is arranged to protrude into the flow channel (3) and a second containment portion (21) connected to the flow channel (3) and from which the second valve member is arranged to protrude into the flow channel (3).
  4. 4. The discharge valve of claim 3, further comprising a first sealing element (11) arranged between the first valve member (4) and the first containment portion (20) of the housing (2) and a second sealing element (12) arranged between the second valve member (7) and the second containment portion (20) of the housing (2).
  5. 5. The discharge valve of claim 3 or 4, further comprising a first steam or compressed air inlet (13) located in the first containment portion (20), such that a gap between the first valve member (4) and the first containment portion (20) can be filled with pressurized steam or compressed air.
  6. 6. The discharge valve of any one of the preceding claims, wherein said first valve member (4) is arranged to protrude from a first location (Pl), and said second valve member (7) is arranged to protrude from a second location (P2), said first and second locations being situated at different positions in a circumferential direction of the flow channel (3).
  7. 7. The discharge valve of claim 6, wherein said second location is situated 160°-200°, from said first location in a circumferential direction of the flow channel (3), preferably 175°- 185°, more preferably 180°.
  8. 8. The discharge valve of any one of the preceding claims, wherein the first valve member (4) is arranged at a first length position (101) along said longitudinal centre axis (A) of the flow channel (3) the second valve member is arranged at a second length position (102) in said length direction, which at least partially overlaps with said first position (101).
  9. 9. The discharge valve of any one of the preceding claims, wherein said first and second length positions along said longitudinal centre axis (A) fully overlap.
  10. 10. The discharge valve of any one of the preceding claims, wherein said first valve member (4) protrudes into said flow channel (3) at a first angle (al) to said longitudinal centre axis (A) of the flow channel, and said second valve member protrudes into said flow channel (3) at a second angle (a2) to said longitudinal centre axis (A) of the flow channel, said first and second angles (al,a2) being the same or different, and being 30- 150°, preferably from 45-135°, more preferably from 80-100°, most preferably substantially 90°.
  11. 11. The discharge valve of any one of the preceding claims, wherein said first and second valve members protrude into the flow channel (3) to such an extent that a forward end (4a) of said first valve member (4) and a forward end (7a) of said second valve member (7) are on the same distance from said longitudinal centre axis (A) of the flow channel.
  12. 12. The discharge valve of any one of the preceding claims, wherein said first valve member (4) and second valve member (4) are retractable so as to be able to move between a protruding state and a retracted state.
  13. 13. The discharge valve of any one of the preceding claims, wherein a detachable inner lining (8) is arranged in said flow channel (3) and at least partly forms the flow channel.
  14. 14. A process element (10) in a manufacturing process involving processing of lignocellulosic material, wherein a discharge valve (1) according to any one of the preceding claims is connected to a pressurized interior process volume of the process element.

Description

A discharge valve Technical field The present disclosure relates to a discharge valve, in particular a discharge valve for use in a manufacturing process involving processing of lignocellulosic material, such as a pulp manufacturing processes or a process for manufacturing bio-fuel. Background art In the process industry and, in particular, in the biomass process industry such as in pulp manufacturing and in the manufacturing of bio-fuels, discharge valves are used to control the pressure and/or process flow in process elements such as boilers, reactors and refiners which have inner pressurized process chambers. Shutter valves, gate valves and ball sector valves are the most commonly used types of discharge valves in the pulp manufacturing industry. Process flows in processes involving processing of lignocellulosic materials are generally corrosive, high temperature and containing abrasive particulate material such as cellulose fibers and fragments and impurities following with the processed material. A discharge valve being continuously exposed to such harsh material will wear over time and will eventually have to be replaced by a new valve, which is costly and may involve lengthy stop-times in the process. In to mitigate this, a replaceable inner lining can be arranged in the flow channel. An example of this is shown in document WO16171604A1. However, it has been found that problems with wear of the inner surfaces of the discharge valve may still arise, in particular in applications where the pressure difference over the discharge valve is very high and the process flow has a high content of abrasive particles, and there is a desire to find solutions to this. Summary The present invention aims at providing a way of reducing the wear of the inner surface of a discharge valve, to allow discharging a highly abrasive process flow with less risk of damaging the discharge valve, thus leading to a discharge valve having a more robust construction and longer service life. The discharge valve as disclosed herein may be a discharge valve adapted for connection to an outlet of a pressurized process element in any biomass processing system involving evacuation of material from pressurized processing voids, such as found in refiners, boilers and reactors or may be a discharge valve connected to an outlet of a pressurized process element in any biomass processing system involving evacuation of material from pressurized processing voids, such as found in refiners, boilers and reactors. Biomass processing systems may be found, e.g. in cellulose pulp manufacturing processes and in bioplants for the production of biofuels such as ethanol and biodiesel. Such processes involve processing of lignocellulosic raw materials derived from perennial plants such as trees as well as annual plants such as sugar cane, straw, hemp, etc. thus, the process flow may typically be a wood or plant fibre mix, i.e. a mix of wood or plant fibers, steam, chemicals and abrasive particles, or the like. In a mechanical pulping process for example, wood chips are generally washed, and subjected to heat and/or a chemical pre-treatment and refined to pulp by being fed between two disks in a refiner wherein the wood chips are ground to pulp, which is discharged through a discharge valve connected to an outlet of the refiner. During processing in the refiner, pressure and heat are built up, putting the discharge valve under a lot of strain and wear as the discharge valve is opened and pressurized pulp is discharged through the discharge valve. In prior art solutions, such as the one disclosed in W02016171604A1, a valve member may be arranged to be inserted into the flow channel. In such a discharge valve, the valve geometry with a valve member inserted into the flow channel from one direction, in combination with increased pressure difference over the valve and more abrasive particles in the raw material, may cause the flow direction of the process flow to change when it collides with the inserted part of the valve member. The solid materials of the process flow will hit the inserted part and then change direction so that they bounce down on the surface of flow channel, or the wear lining inserted therein, before they move forward out from the discharge valve and into a discharge tubing and further onward to a tank, dryer or the like. When a small valve opening is used, the abrasive solid materials of the process flow may also bounce back toward the opposite side of the valve and cause abrasion on the flow channel surface also on the upper side of the valve, and possibly also in the discharge tubing following the discharge valve. According to the present invention, there is provided a discharge valve, or blow valve, comprising a valve housing connectable to a process element having a pressurized interior process volume. The discharge valve comprises a flow channel having a longitudinal centre axis, A, and extending from an inlet of the flow channel to