Shut-off valve for a high-pressure roller press

Abstract

The invention relates to a shut-off valve for a high-pressure roller press, which is movable via a straight slot to control the flow of ground material, wherein the shut-off valve has a dovetail-shaped recess. According to the invention, it is provided that when the shut-off valve is moved from a closed position to an open position, the slot gradually opens from the center of the slot to both ends of the slot in order to apply material to the roller gap in a controlled manner.

Description

[0001] The invention relates to a shut-off valve for a high-pressure roller press, which is movable via a straight slot to control the flow of ground material, wherein the shut-off valve has a dovetail-shaped recess.

[0002] In high-pressure roller presses, brittle material is drawn through a narrow roller gap for comminution and, under the high pressure of the roller press, is broken down by brittle fracture. When feeding the material into the roller gap, it is important to monitor the fill level during operation. The roller gap must not be overloaded to allow the material sufficient space for brittle fracture. If the roller gap is underfilled, the high-pressure roller press acts like a crusher. The material breaks and is forced into the remaining, unoccupied space in the roller gap, thus avoiding brittle fracture.

[0003] Each high-pressure roller press is equipped with a metering slide that controls the material flow and a shut-off slide that can completely stop the flow. The material flow is shut off in the event of a milling malfunction to ensure that no material can pass through the high-pressure roller press. The shut-off slide, when closed, separates a feed hopper for the material to be ground from the high-pressure roller press, thus cutting off the material feed. During a controlled start-up process, the shut-off slide opens only when the rollers of the high-pressure roller press are running at their rated speed, the metering slide is almost closed, the moving roller is in its starting position, and the hydraulic pressure is at start-up level. The shut-off slide is pneumatically, hydraulically, or electrically operated to ensure rapid closing in the event of a malfunction during operation.One problem, however, is that the shut-off valve also opens very quickly. This leads to unintended high stress on the machine components of the high-pressure roller press, even to the point of breaking the shear pins of the roller drive coupling. This situation occurs more frequently than one would expect, especially when grinding raw material.

[0004] The object of the invention is therefore to carry out the opening or closing process of the shut-off valve of a high-pressure roller press at different speeds.

[0005] The problem according to the invention is solved by a gate valve with the features according to claim 1. Further advantageous embodiments are specified in the dependent claims to claim 1.

[0006] According to the invention, the shut-off valve itself is not straight and does not open and close a straight slot. Instead, the shut-off valve has an edge that is not parallel to the slot axis, with the slot covering the roller gap. If the edge of the shut-off valve is straight and not parallel to the slot axis, the shut-off valve closes like a guillotine. This would cause the material being ground to gradually fill the roller gap from one end, across the middle, to the other end, as the shut-off valve opens slowly, thus causing the rollers to become misaligned. Therefore, the shut-off valve is designed to have at least one dovetail-shaped recess.When the gate valve opens, a small opening initially appears in the center of the at least one dovetail-shaped recess. As the gate valve opens further, this opening gradually widens towards both ends of the slot. This prevents the rollers from becoming misaligned when the gate valve opens and avoids a sudden material feed into the roller gap. It is also possible to design the gate valve with a serrated edge. This serration is created by adjacent dovetail-shaped recesses in the edge of the gate valve that traverses the slot.

[0007] To actuate the gate valve, it can be connected to a pneumatic lifting system. When the slot is opened, this system cocks a compressed air cannon, which can be triggered in an emergency or breakdown to quickly close the slot. Due to the gate valve's special edge design, rapid closure is essential. A pneumatic, hydraulic, or electric lifting system of this type typically performs the stroke equally quickly in both directions, i.e., for opening and closing. To enable rapid closure, the pneumatic cannon is cocked, forcing compressed air into the gate valve's lifting system, thus ensuring a particularly fast closure of the gate valve.

[0008] Unlike a rapid closing mechanism, it is desirable for the gate valve to open more slowly. This can be achieved by incorporating a pressure reduction system into the pneumatic lifting system, which is activated during the opening process and results in a slow opening of the slot.

[0009] To actuate the gate valve, it can also be provided that it is connected to a hydraulic lifting system which, when the slot is opened, tensions a bladder accumulator, whereby the bladder accumulator can be triggered in an emergency / breakdown situation and quickly closes the slot.

[0010] To close the gate valve slowly with the hydraulic lifting system, the hydraulic lifting system may be provided with a pressure reduction system which is activated during the opening process and leads to a slow opening of the slot.

[0011] Up to this point, a gate valve has been presented that is a flat slide that is pushed over a straight slot. In a particular embodiment of the gate valve, it can be cylindrical and have at least one dovetail-shaped recess in its cylindrical body. As the gate valve rotates, this recess is pushed over the slot. A rotating gate valve has the advantage that two edges exist in the open cylindrical body. One edge can have the dovetail-shaped recess, while a second edge can be straight and run parallel to the cylinder axis. When this cylindrical gate valve rotates, the edge of the gate valve is pushed over the slot.The slot opens as the at least one dovetail-shaped recess passes through it, and closes as the straight edge closes it. The opening of the slot is therefore slow, while the closing is fast, with the rotational speed of the gate valve remaining constant during both opening and closing.

[0012] The invention is explained in more detail with reference to the following figures. They show: Fig. 1 a sketch of the gate valve according to the invention in a first embodiment in the open state, Fig. 2. Turn off the shut-off valve Fig. 1 near the closed state Fig. 3 a pneumatic lifting device for actuating the shut-off valve in the Fig. 1 and Fig. 2, Fig. 4 a hydraulic lifting device for actuating the shut-off valve in the Fig. 1 and Fig. 2, Fig. 5 a cylindrical variant of the gate valve, Fig. 6 different edge shapes for the gate valve.

[0013] Fig. Figure 1 shows a schematic diagram of the gate valve 100 according to the invention in a first embodiment in the open state. The gate valve rests on the base 10 of a feed device 11, the base 10 having a slot 110 through which the material being ground, which is held in the feed device 11, falls. In this state, the gate valve 110 is completely pushed to the side. This means that the slot 110 is fully open.

[0014] In Fig. 2 is the shut-off valve 100 from Fig. Figure 1 shows the position of the gate near the closed position. In the closed position, the gate valve 100 lies over the slot 110 of the feed device 11 and closes the slot 110, leaving the center 115 of the slot 110 open. When opening, the gate valve 100 moves back to the left, slowly opening the slot 110 first in the center 115 and only then at both ends 116 and 117.

[0015] Fig. Figure 3 shows a pneumatic lifting device 300 for actuating the shut-off valve in the Fig. 1 and Fig. 2. The pneumatic lifting device 300 is connected to the shut-off valve 100 via a coupling 305. A pneumatic double cylinder 306 is opened by a compressor 307, causing the piston 308 in the double cylinder 306 to move to the left. For this to occur, the control valve 309b is open, control valve 309d is open, and control valves 309a and 309c are closed. The piston 308 pushes air into the compressed air gun 310, thus pre-pressurizing it. It is possible for the compressor 307 to further pressurize the compressed air gun 310 by closing control valve 309b and opening control valves 309a and 309d. For quick closure in case of failure, the control valve 309d and also the control valve 309c can be opened, causing the piston 308 to move to the right and thereby pushing the shut-off valve 100 to the right over the slot 110.The control valve 309b can only be partially opened as a pressure reducing system in order to ensure that the pressure in the left cylinder of the double cylinder 306 builds up slowly and that the gate valve 100 is moved slowly to the right.

[0016] In Fig. 4 is a hydraulic lifting device 400 for actuating the shut-off valve in the Fig. 1 and Fig. Figure 2 is shown in the diagram. The hydraulic lifting device 400 is connected to the gate valve 100 via a coupling 405. A hydraulic double cylinder 406 is opened by a hydraulic pump 407, causing the piston 408 in the double cylinder 406 to move to the left. The piston 408 pushes hydraulic fluid into the accumulator 410, thus pre-pressurizing it. For rapid closure in case of a failure, the control valve 409 can be opened, causing the piston 408 to move to the right and thereby pushing the gate valve 100 to the right over the slot 110. A pressure-reducing valve can also be open while the accumulator 410 is being pressurized, so that the pressure in the double cylinder 406 builds up only slowly and thus pushes the gate valve 100 slowly to the right over the slot 110.

[0017] In Fig. Figure 5 shows a cylindrical variant of the gate valve 200. The gate valve 200 has a cylindrical design. The cylindrical body contains at least one dovetail-shaped recess 220, which slowly opens the slot 110 when the gate valve rotates over it. As the gate valve 200 continues to rotate, the straight edge 230 moves over the slot 110 and closes it significantly faster than it opens via the dovetail-shaped recess 120 when the gate valve 200 rotates over the slot 110.

[0018] Fig. Figure 6 shows various edge shapes for the gate valves 100 and 200. As shown here, it is possible to provide one dovetail-shaped recess 120 (left), two dovetail-shaped recesses 120 (center), and four dovetail-shaped recesses 120 (right). Three and five dovetail-shaped recesses 120 can also be provided. REFERENCE MARK LIST 10 Floor 11 Feed device 100 gate valves 110 slots 115 Middle (slot) 116 End (slot) 117 End (slot) 120 dovetail-shaped recesses 200 gate valves 210 cylinder jacket 220 dovetail-shaped recesses 230 straight edge 300 pneumatic lifting system 305 Clutch 306 pneumatic double cylinder 307 compressors 308 pistons 309a Control valve 309b Control valve 309c Control valve 309d Control valve 310 compressed air cannon 320 Pressure Reduction System 400 hydraulic lifting system 405 Clutch 406 twin cylinders 407 Hydraulic pump 408 pistons 409 Control valve 410 bladder reservoirs 420 Pressure Reduction System

Images