Valve arrangement

Abstract

Valve arrangement for a system which is loaded with fluid, for connecting a first pressure region to a second pressure region by means of a first valve and a second valve connected in series. A third valve connects a region between the first valve and the second valves to a third pressure region. The first valve closes when a pressure which prevails on the side of the second pressure region is at least as high as a pressure which prevails on the side of the first pressure region. The first valve is coupled to the second valve so that the second valve closes when the first valve closes. The second valve is coupled to the third valve so that the third valve opens when the second valve closes.

Claims

1. Valve arrangement for a system which is loaded with fluid, for connecting a first pressure region to a second pressure region by means of a first valve and a second valve which is connected in series thereto, a third valve connecting a region between the first valve and the second valve to a third pressure region; the first valve being set up such that the first valve closes when a pressure which prevails on a side of the second pressure region is at least as high as a pressure which prevails on a side of the first pressure region; the first valve being coupled to the second valve in such a way that the second valve closes when the first valve closes; the second valve being coupled to the third valve in such a way that the third valve opens when the second valve closes wherein the first valve is coupled via a switching apparatus to the second valve.

2. Valve arrangement according to claim 1, the switching apparatus having a valve.

3. Valve arrangement according to claim 2, wherein the valve of the switching apparatus is a solenoid valve.

4. Valve arrangement according to claim 1, the first valve being coupled to the switching apparatus mechanically, pneumatically or hydraulically.

5. Valve arrangement according to claim 1, the second valve being coupled to the switching apparatus electrically, hydraulically or pneumatically.

6. Valve arrangement according to claim 1, the second valve being coupled to the third valve mechanically, electrically, hydraulically or pneumatically.

7. Valve arrangement according to claim 1, the third valve being coupled to the switching apparatus electrically, hydraulically or pneumatically.

8. Valve arrangement according to claim 1, the first valve being arranged closer to the first pressure region than the second valve.

9. Valve arrangement according to claim 1, the first pressure region is at a lower pressure than the second pressure region.

10. Valve arrangement according to claim 1, a pressure in the third pressure region being lower than in the first pressure region.

11. Valve arrangement according to claim 1, the third pressure region having a connection to a disposal system, a flare system or atmosphere.

12. Method of preventing back-flow from a high-pressure region to a low-pressure region comprising: providing a valve arrangement that connects the low-pressure region to the high-pressure region by means of a first valve and a second valve connected in series, and having a third valve connecting a region between the first valve and the second valve to a third pressure region; closing the first valve when a pressure prevails on a side of the second pressure region that is at least as high as a pressure which prevails on a side of the first pressure region; coupling the first valve to the second valve so that the second valve closes when the first valve closes; and coupling the second valve to the third valve so that the third valve opens when the second valve closes wherein the first valve is coupled via a switching apparatus to the second valve.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a shut-off valve arrangement with a non-return valve and safety valve in the case of liquid metering according to the prior art.

(2) FIG. 2 shows one preferred refinement of a valve arrangement according to the invention.

(3) FIG. 3 shows a further preferred refinement of a valve arrangement according to the invention.

EMBODIMENTS OF THE INVENTION

(4) FIG. 1 diagrammatically shows a system 100 for liquid metering. A refillable tank 110 serves as supply for a fluid which is present as a liquid. The liquid is guided via a valve 115 to a pump 120, by means of which a corresponding pressure can be built up, in order to forward the liquid to a distributor 160.

(5) A non-return valve 130 and a further metering and/or shut-off valve 150 are arranged between the pump 120 and the distributor 160. The non-return valve divides the system 100 into a low-pressure region with the tank 110 and a high-pressure region with the distributor 160, via which the fluid is introduced gaseously into a process circuit. It is to be noted here that a part of the system 100 which is designed for high pressures is usually called the high-pressure side or high-pressure region. However, during regular operation, a somewhat higher pressure prevails on the low-pressure side or in the low-pressure region than on the high-pressure side, or at least part of the high-pressure side, since otherwise no transport of the fluid in the direction of the high-pressure side would be possible.

(6) In addition, a branch is provided between the pump 120 and the non-return valve 130 in the low-pressure region, which branch leads via a shut-off valve 170 to a safety valve 140.

(7) In the case of an excess pressure in the high-pressure region, for example on account of an operational disruption, the non-return valve 130 then closes automatically. This is intended to prevent a permissible pressure in the low-pressure region being exceeded.

(8) In reality, however, a non-return valve is not completely sealed, that is to say 100%. This therefore nevertheless leads as a rule to excess pressure on the low-pressure side as a result of back-flowing gas. Said excess pressure can be dissipated by way of the safety valve 140, in the case of an open shut-off valve 170. A safety valve 140 opens automatically at a corresponding excess pressure, it being possible as a rule for the magnitude of the excess pressure, at which the safety valve 140 opens, to be set and/or adjusted.

(9) However, the valve arrangement in the system 100 cannot prevent undesired substances which are situated in the fluid in the high-pressure region passing into the low-pressure region through the leaky non-return valve 130 in the case of an excess pressure.

(10) FIG. 2 diagrammatically shows a valve arrangement 200 according to the invention in one preferred refinement. The valve arrangement 200 serves to connect a first pressure region p1 which is configured as a low-pressure region to a second pressure region p2 which is configured as a high-pressure region in a system which is loaded with fluid. Since the valve arrangement 200 connects two sides with different pressure regions, the low-pressure region p1 is also called the low-pressure side and the high-pressure region p2 is also called the high-pressure side. It is to be noted here that a part of the system which is designed for high pressures is usually called the high-pressure side. However, during regular operation, a somewhat higher pressure prevails on the low-pressure side than on the high-pressure side, or at least part of the high-pressure side, since otherwise no transport of the fluid in the direction of the high-pressure side would be possible.

(11) The connection takes place via a first valve 10 and a second valve 20 which is connected in series thereto. Here, a region p1/2 is formed between the first valve 10 and the second valve 20. The first valve 10 is configured as a process medium-controlled valve. It closes automatically as soon as the pressure which prevails in the high-pressure region p2, in this case also and in particular in the region p1/2, is at least precisely as high as the pressure which prevails in the low-pressure region p1.

(12) The first valve 10 is coupled to a switching apparatus 40 which is configured as a solenoid valve. This coupling can be, for example, electric. In the case of a differently configured switching apparatus 40, a different type of coupling can be more suitable, however. The solenoid valve 40 in turn is coupled to the second valve 20. Here, this coupling is configured in such a sway that the solenoid valve 40 can open and close a connection of the second valve 20 to a compressed air store 80. A valve drive of the second valve 20 is therefore driven here by means of compressed air, that is to say pneumatically.

(13) Depending on the configuration, the second valve 20 can be closed by the solenoid valve 40 opening and closing the connection to the compressed air store.

(14) The region p1/2 has a branch to a third valve 30 which connects the region p1/2 to a third pressure region p3. The third pressure region p3 has, for example, a connection to a flare system and therefore approximately atmospheric pressure.

(15) The third valve 30 is then coupled to the second valve 20 in such a way that it is opened automatically as soon as the second valve 20 is closed. This coupling can take place, for example, mechanically. In this way, the third valve 30 does not require a dedicated valve drive, but rather is controlled by the valve drive of the second valve 20, which valve drive is in turn operated by means of compressed air.

(16) FIG. 3 diagrammatically shows a valve arrangement 300 according to the invention in a further preferred refinement. The valve arrangement 300 differs from the valve arrangement 200 which is shown in FIG. 2 merely in that the second valve 20 is not coupled directly to the third valve 30, but rather indirectly via a switching apparatus 40. The third valve 30 is coupled to the switching apparatus 40, for example by means of a compressed air connection just like the second valve 20. In this way, the second valve 20 and the third valve 30 are controlled in each case, in particular at the same time, by the switching apparatus 40, that is to say the second valve 20 is closed and the third valve 30 is opened.

(17) The effects which are achieved by way of the valve arrangements 200 and 300 are identical, however, independently of the precise actuation of the second valve 20 and of the third valve 30. A distinction will therefore not be made between the two valve arrangements in the following text during the description of the method of operation.

(18) A has already been mentioned, during normal operation of the system, the fluid flows from the low-pressure region p1 to the high-pressure region p2, where it is fed, for example, to a process. Here, the first valve 10 and the second valve 20 are open, and the third valve 30 is closed.

(19) If, for example, an operational disruption then occurs in the high-pressure region p2, as a result of which the pressure rises, the pressure also rises in the region p1/2. A soon as the pressure in the region p1/2 is then at least as high as that in the low-pressure region p1, the first valve 10 closes automatically. Depending on how rapidly a pressure rise of this type takes place and how rapidly the first valve 10 can react and to which precise pressure conditions it is set, the first valve 10 already closes in the case of equal pressure between the region p1/2 and the low-pressure region p1 or else not until a certain excess pressure in the region p1/2; equal pressure is to be preferred, in particular, with regard to possible contamination of the tow-pressure region p1.

(20) The closure of the first valve 10 is also accompanied by the closure of the second valve 20, as described above. This is therefore a double shut-off between the low-pressure region p1 and the high-pressure region p2.

(21) Since opening of the third valve 30 takes place at the same time as the closure of the second valve 20, it is ensured that this pressure in the low-pressure region p1 is always greater than the pressure in the region p1/2. Pressure which would build up as a result of a possible leaky second valve 20 in the region p1/2 as a result of fluid which flows over fro the high-pressure region p2 is dissipated immediately via the third valve 30, since the fluid is discharged, for example, to the flare means and/or the atmosphere. The third valve 30 therefore has the action of a ventilating valve.

(22) Since fluid which flows from the high-pressure region p2 in the direction of the low-pressure region p1 without exception flows out via the third valve 30, no fluid passes from the high-pressure region p2 into the low-pressure region p1. No undesired substance or contamination can therefore pass from the high-pressure region p2 into the low-pressure region p1 either.

(23) Even in the case of liquid metering, no gas can therefore pass from the high-pressure region p2 into the low-pressure region p1, as a result of which disruptions might occur, for example, by way of pump failure.