SI9500294A - Combination of a differential pressure and flow controller - Google Patents

Abstract

The valve unit has a pair of separate regulating valves (2,13) connected in series within a common valve housing (1), with the difference pressure regulating valve (2) infront of the volumetric flow regulating valve (13). The difference pressure regulating valve simultaneously acts as throttle for controlling the volumetric flow regulating valve, the volumetric flow set by limiting the displacement of the difference pressure regulating valve.

Description

DIFFERENTIAL PRESSURE AND FLOW REGULATOR COMBINATION

The subject of the invention is a combination of differential pressure regulator and fluid and gas flow, which should have low pressure loss at low cost and long life span.

This combination is particularly suitable for district heating networks and in district heating plants.

There are three technical problems to be solved by this invention.

Problem 1.

Requires the lowest total pressure consumption with the highest accuracy and the lowest possible cost. But the flow regulator works more accurately if the throttle pressure consumption, which gives the control pulse the greater. Larger diaphragms are usually required for greater accuracy, which means higher cost.

Problem 2.

Minimal dynamic seals are required, which seal the moving parts and are subject to constant wear and cause additional friction. The friction of moving parts shortens the service life and reduces the accuracy of regulation.

Problem 3.

The throttle should also serve as a shut-off valve.

The known solutions to these problems are as follows.

Problem 1.

Two embodiments of the combination of differential pressure and flow controllers are known.

a) Two separate series-connected regulators shall be used. The flow regulator is integrated in the inlet and the differential pressure regulator in the return. Each regulator works for itself. The first disadvantage is that when closing the differential pressure regulator, the flow drops as well, so the flow regulator opens and thus interferes - it inhibits the operation of the differential pressure regulator. Another drawback is the high pressure consumption, two valves and a throttle to control the flow. The third weakness is in the high price.

b) Combined regulator with one valve body and two diaphragms. One membrane regulates flow and the other differential pressure. The advantage is lower pressure consumption, since only one valve and throttle are required to control the flow. The price is also slightly lower than with two separate regulators. The downside, however, is the reduced accuracy of differential pressure control. In certain circumstances, the differential pressure diaphragm must also overcome the force, or at least part of the force acting on the diaphragm for flow. Therefore, two separate springs on the diaphragm are usually used for flow. One acts only on the flow diaphragm and the other serves at the same time to open the valve and acts on the flow diaphragm via a vent plate. In any case, this opening spring must also be overcome by the differential pressure diaphragm. This is a relatively large additional control error that is added to the differential pressure control error.

Problem 2.

A known embodiment of the Honeywell pressure reducing valve according to patent DE-PS2407223 is where the vent plate is stationary and the seat, which has the shape of a tube through which the medium flows, moves. However, in addition to sealing the movable seat, it is also necessary to seal a movable axis connecting the diaphragm to the seat. Therefore, sealing of two moving parts is required. Which means double friction and therefore more error and shorter life span.

Problem 3.

With the known solutions, the functions of ordinary valve closing and throttle adjustment are always separate. This is because, otherwise, the throttle flow setting is lost every time it is closed. However, the flow setting should be memorized, written down, or somehow marked on the throttle so that it can be reset to the previous value after reopening. Two separate features mean a higher price.

Solution to the problem 1.

The problem is solved with three structural elements.

1.1 Two axial actuators are installed in series in one common housing. The first in the direction of flow of the medium is the differential pressure regulator and the second is the flow regulator. The differential pressure regulator and its pressure drop serve as a throttle to control the flow regulator. The stroke of the differential pressure regulator, and thus the flow restriction, is limited by a suitable closure. This greatly reduces permanent pressure loss. And both regulators work in the same way.

1.2. Plus pressure for flow control shall be taken in front of the differential pressure regulator, where the flow opening in the housing has the same cross section as the pipeline and minus the pressure in the constricted part behind the differential pressure regulator, where the absolute pressure is much lower than the full cross section due to the higher velocity. This dynamic pressure difference does not represent a permanent loss, as the pressure later in the full cross section after the valve increases again. This further reduces the permanent consumption of pressure.

1.3 Due to the axial design of the valves, the resistance is very small, so that at the same capacity as the normal valve, the axial valves can have a significantly smaller seat diameter. A smaller seat means less friction at the same time. Therefore, the membrane and thus the whole structure may be smaller.

The consequence is a lower price.

Solution to the problem 2.

The regulators are axial designs. In the middle, the membrane has a flow opening through which the medium flows. The valve seat is in the form of a flexible tube that is attached to the diaphragm plate. The valve plate is fixed. The diaphragm is on the outer and inner edges, tightly clamped into the housing. The diaphragm plate is freely leaned and pressed against the diaphragm under the force of the spring and centered in the radial direction by the outer and inner waves of the diaphragm. The tubular flexible valve seat is guided in the housing and sealed with a gasket. The inner edge and the wave of the diaphragm replace the second seal of the movable valve seat. In the membrane, the internal friction on motion is much smaller than that of a friction seal (O-ring, cuff, etc.). Because there is no friction on the membrane with moving parts, there is no wear and tear. The sliding valve seat is slidably guided in only one support and is guided by the diaphragm without friction on the other side, thus further reducing friction and regulation error.

Solution to the problem 3.

Both functions, closing and limiting the stroke of the differential pressure regulator (that is, setting the flow rate), are performed by a single simple mechanism, which has the following elements: a nut with a pointer, a ring with a scale and a fixing screw, and a fixing hole on the valve body. The nut is used to adjust and limit the position of the differential seat of the differential pressure regulator. On the nut is a pointer positioned so that, with the differential pressure regulator closed, it shows a fixing hole on the valve body. At the perimeter of the nut is a wreath of teeth. The teeth of the ring with the rock are clamped into these teeth, which together with the teeth on the nut form a toothed clutch. On the adjustable ring there is a scale for adjusting the flow, with a fixing screw fitted to or as NOTHING. There is a fixing hole on the valve body into which the tip of the fixing screw goes if screwed on. When the fixing screw is not screwed in, the nut with the ring can be rotated arbitrarily to open or close the valve. The fixed nut position (and thus the specified flow) is fixed by placing the scale ring on the nut with the desired scale position relative to the pointer on the nut. Then turn the nut so that the fixing screw can be screwed into the fixing hole on the housing. The intersection of the nut and the ring with the rock is fixed with the clutch teeth. Even if the fixing screw is unscrewed due to the need for complete closure or opening, the position of the broom with the scale relative to the nut remains unchanged and the flow setting is not lost. Of course, provided that the ring is not removed from the grip of the teeth.

DESCRIPTION OF THE CONSTRUCTION SOLUTION

Figure 1 combination according to the invention with external impulse control Figure 2 combination according to the invention with internal impulse control

Figure 1

There are two controllers in the common housing (1). In the direction of flow of the flow medium, a differential pressure regulator (2) consisting of a diaphragm (3) with a middle opening (4), a diaphragm plate (5), a tubular seat (6) with a flow opening (7), which is guided, is first mounted in the partition (8) and sealed with the seal (9). The seat has a sealing edge (11). Valve plates are indicated by (12) and spring by (10).

The diaphragm (3) has an outer sealing edge (31) and an outer wave (32) for centering the diaphragm on the outside, and an inner edge (36) for sealing and an inner wave (35) for centered diaphragm plates on the inside.

In the direction of flow, behind the differential pressure regulator is a flow regulator (13) consisting of a diaphragm (14) with a middle opening (15), a diaphragm plate (16), a tubular seat (17), with a flow orifice (18), which is guided in partition (19) and sealed with gasket (20). The seat has a sealing edge (22). Valve plates are indicated by (23) and spring by (21).

The adjusting nut (39) is screwed onto the housing (1) with a pointer (40) and a retaining ring (42), which is connected to the adjustable ring (44) by means of a toothed clutch (44) on which the flow scale (43). On the ring, a fixing screw (34) is mounted next to the NIC mark on the scale, which can be screwed into the fixing hole (33) on the housing (1). The adjusting nut presses on the diaphragm plate (5) via the closure (45) and spacer (46), thereby limiting the stroke - opening of the differential pressure regulator. The axial direction of movement of the adjustable ring (44) away from the housing (1) is indicated by (F) and the opposite direction by (L).

The inlet (38) and the outlet (24) of the housing (1) have approximately the same intersection as the pipeline in front of the controller. The flow openings (7) and (18) in the valve seats (6) and (17), however, have a significantly smaller flow cross section than the pipeline in front of the regulator. The plus impulse for differential pressure control is (dp +). The minus differential pressure pulse (dp-) is at the same time plus the flow pulse (V +). The openings in the housing (1) through which (dp-) and (V +) act are indicated by (37) and (30) a the openings in the partitions through which the impulses on the membrane by (29) and (27) operate. The median chamber is (29). A minus impulse for flow (V-) through the opening (25) acts on the diaphragm (14) in the flow controller. The minus flow chamber is (26).

The flow medium enters through the inlet (38) into the housing (1), flows through the flow port (7) through the valve seat (6) past the vent plate (12) of the differential pressure regulator (2). Then, through the flow port (18) of the valve seat (18), the flow regulator (13) flows past the valve plate (23) and exits the housing through the outlet port (24).

The impulse (dp +) acts on the membrane (3) against the force of the spring (10) and the impulse (dp-). if the forces on the diaphragm are in equilibrium, the diaphragm plate (5) is stationary, otherwise it moves in the proper direction and by adjusting the free section between the sealing edge (11) on the valve seat (6) and the valve plate (12), regulates the differential pressure between points where the impulses (dp +) and (dp-) are taken.

The pulse (dp-) acts simultaneously as a pulse (V +) through the middle chamber (29) on the diaphragm (14) against the force of the spring (21) and the pulse (V—). This acts to reduce the pressure in the differential pressure regulator as a throttle to control the flow regulator. As long as the pressure drop in the differential pressure regulator (2) is less than the pressure of the spring (21) on the diaphragm (14), the flow regulator is open, otherwise it will clamp until the equilibrium pressure on the diaphragm (14) resumes. With the adjusting nut (39), the stroke (H) of the valve seat (6) in the differential pressure regulator (2) is limited by the required flow.

This gives the maximum flow rate, since only one flow through which the pressure drop will be equal to the pressure of the spring (21) on the diaphragm (14) corresponds to one seat position. It is essential that the pulse (V-) is taken in the flow orifice (18) in the valve seat (17) having a substantially smaller cross-section than the inlet (38) where the pulse (V +) is taken. Due to the higher velocity, the absolute pressure in the constricted section is lower. Therefore, the pressure drop in the differential pressure regulator (2) may be correspondingly smaller. Later in the outlet (24) the speed drops again and the absolute pressure rises. Thus, a temporary dynamic pressure difference is used to reduce the pressure drop required to control the flow regulator.

Using the gear clutch (41) on the adjusting nut (39) and the adjustable ring (44), an angle can be set between the pointer (40) on the nut and the NIC mark on the ring. This angle determines the opening of the differential pressure regulator (2) when the adjusting nut is tightened so that the fixing screw (34) can be twisted into the fixing hole (33) on the housing.

Figure 2

The impulse for (dp-) and (V +) enters through the lateral opening (51) into the impulse tube (52) and then through the bore (50) in the vent plate (12) through the middle chamber (29) acts on the membrane (3) and ( 14). The flow minus pulse (V-) flows through the lateral opening (48) in the pulse tube (49) and then through the bore (47) in the valve plate (23) through the minus chamber (26) onto the diaphragm (14). Both impulse tubes are located approximately approximately in the axis of the valve (53).

Claims (10)

1. A combination of flow and differential pressure controllers, consisting of two sequentially coupled regulators in which the differential pressure acts on the diaphragm and the spring force, and the diaphragm moves the valve seat which, together with the valve plate, regulates the differential pressure or flow, characterized in that a differential pressure regulator (2) relative to the direction of flow of the medium positioned in front of the flow regulator (13) and serves as a differential pressure regulator (2) at the same time as a throttle for controlling the flow regulator (13), the flow adjustment being made by limiting the maximum stroke (H) in differential pressure regulator (2). Combination according to claim 1, characterized in that the plus pulse (V +) for controlling the flow regulator (2) is taken in the inlet opening (38) of the housing (1) in front of the differential pressure regulator (2), wherein the flow cross-section is the inlet opening (38) is approximately equal to the cross-section of the pipeline in front of the differential pressure regulator (2) and minus the flow impulse (V-) behind the differential pressure regulator (2) in the flow orifice (18) with the cross section of the flow orifice (18) being substantially smaller than section of the inlet opening (38). Combination according to claim 1, characterized in that the plus impulse (V +) for the flow, which is simultaneously a minus impulse (dp-) for the differential pressure, is passed through the impulse tube (52) and the bore (50) in the valve plate (12) into the middle chamber (29) and that the minus pulse (V-) for flow is passed through the pulse tube (49) and the bore (47) in the valve plate (23) into the minus chamber (26). Combination according to claim 3, characterized in that both impulse tubes (52) and (49) are closed in the forward direction and the inlet bores (51) and (48) are located on the side of the tube and the impulse tube is positioned approximately in. axles (53) of housing (1). Combination according to claim 1, characterized in that only the impulses (V +) and (dp-) are passed through the impulse tube (52) or only the minus impulse (V-) is passed through the impulse tube (49). Combination according to claim 1, characterized in that the differential pressure regulator (2) is of an axial design and that the membrane (3) on the outer (31) and inner (36) edges is tightly clamped into the housing (1) and is in the middle of the membrane inside the inner edge (36) the middle opening (4) through which the medium flows and the diaphragm plate (5) is freely supported and only by force of the spring (10) is pressed against the diaphragm (3) centered in the radial direction by the inner (35) and an outer (33) wave on the diaphragm (3) and a valve seat (6) of tubular shape, which is guided externally in the partition wall (8) and sealed with a seal (9) and sealed at the end of the seat (9). 11) which, when moving the membrane (3), regulates or closes the flow as it approaches or presses on the plate (12). Combination according to claim 1, characterized in that the flow regulator (13) is also implemented in the manner shown in the claim 6. A standalone differential pressure or flow regulator, characterized in that it is implemented in the manner shown in claim 6. Combination according to claim 1, characterized in that the closing and opening and the restriction of the stroke (H) of the valve seat (6) in the differential pressure regulator (2) are carried out with the adjusting nut (39) having a fixed pointer (40). which indicates the position is closed and the nut (39) is connected to the adjustable ring (44) by means of a toothed clutch (41) on which the flow scale (43) is mounted, and a fixing screw (34) is mounted next to the mark or as zero on the scale. on the housing (1) the fixing hole (33) into which the tip of the fixing screw (34) sits when we want to adjust and fix a certain position of the adjusting nut (39), whereby the angle between the pointer (40) can be adjusted by means of the toothed clutch (41) on the adjusting nut (39) and the fixing screw (34) on the ring (44), thereby adjusting and fixing a certain flow. Combination according to claim 9, characterized in that the toothed clutch (41) is designed so that the ring (44) can only be pulled in the direction (L) against the housing (1) and that the fixing screw (34) when tightened. the backs in the fixing hole (33) on the housing (1) press the ring (44) in the direction (F) away from the housing (1) so that the toothed clutch (41) is closed, with the axial movement of the ring (44) along the nut (39) ), away from the housing (1), is limited by a stop (42) on the nut (39) so that the ring (44) cannot be removed from the nut (39) by the force of the fixing bolt (34) and is thus secured by the retaining screw the toothed clutch (41) is also closed and fixed to the screw (34).