DE102013002068A1 - Compressed air preparation device i.e. membrane dryer, for providing compressed air, has blocking unit associated to flushing air inlet, and including pressure scale that is loaded in load pressure controlled manner - Google Patents

Abstract

The device i.e. membrane dryer (5), has a membrane filter including a compressed air input and a compressed air outlet for dried compressed air, and an inlet for flushing air (Ps). A blocking unit i.e. pneumatic switching element (4), is associated to the flushing air inlet. The blocking unit includes a pressure scale, which is loaded in a load pressure controlled manner. The scale includes an annular restrained membrane e.g. seam membrane, with spring constants. Membrane lower and upper sides have same active surfaces. The scale is actively connected with a spring-loaded control unit (1).

Description

The invention relates to a compressed air treatment device, in particular a membrane dryer, which has a membrane filter through the compressed air by means of a compressed air input compressed air and compressed air output dry compressed air is discharged while having a scavenging air inlet, wherein the scavenging air inlet is assigned a shut-off.

Of the DE 197 22 731 A1 is a device for removing compressed air, which is housed in a filter housing and having an inlet for moist compressed air and an outlet for dried compressed air and a scavenging air inlet and a scavenging air outlet, and in which a membrane filter, preferably arranged from bundles of hollow fiber membranes, that on whose one filter side sweeps along the compressed air, on the other side of which the scavenging air flows, in particular in the opposite direction to the compressed air, and that is selectively permeable to water vapor and with a feed line, fed by the originating from the outlet and thus dried compressed air in the scavenging air inlet, said in the supply line a shut-off is present, which is influenced by the compressed air consumption.

A compressed air treatment device of the aforementioned type can also from the DE 20 2004 017 303 U1 be removed.

The usable compressed air, which is clean and free of liquid particles, can be taken from the outlet of the membrane dryer. However, in order to get out of this clean compressed air, the remaining water particles, it is necessary that dry purging air is fed into a flushing chamber, thus causing a constant migration of the water mill from the compressed air into the purging air. A major disadvantage of such compressed air treatment devices is the fact that a very high consumption of purging air is present, and thus at the same time there is a lower Nutzluftausbeute. Even if no compressed air is removed from the membrane dryer, there is a constant consumption of purified, high-quality compressed air via the flowing purging air.

The object of the invention is to avoid the permanent consumption of the scavenging air, or to reduce, so that only scavenging air flows, if at the same time at the outlet of the device and dry compressed air is removed.

The object of the invention is achieved by the claims 1 and 2. The dependent claims provide a further embodiment of the inventive concept again.

To reduce the consumption of purge air, d. H. purge air is only provided if there is a pressure drop in the system, i. H. a consumption of compressed air is present to realize is resorting to the means of a pneumatic switching element. Such a pneumatic switching element can be load pressure controlled, which means that at the moment where in the main stream of compressed air is demanded, even at the same moment due to a differential pressure education between input and output pressure of the system, the pneumatic switching element opens the way for the scavenging air. Although such an approach is possible today by means of pressure sensors and electronically executed components, but the present invention provides a purely pneumatic way to do this without electrical components. No electrical regulations or explosion regulations need to be observed.

This basically means that upon detection of pressure changes, i. H. Pressure drops, at the same time in the compressed air treatment device, the path for the purge air is switched through. In addition, the system can also be used so that, for example, in the main stream by reducing the pressure also another medium, eg. As oxygen, can be unlocked. This is also possible with the present embodiment of the shut-off.

The switching element is thus differential pressure dependent. This means that the switching element is only automatically activated when a sufficiently large amount of air flows through the assembly, and the differential pressure exceeds an adjustable switching threshold. However, if the flow is stopped, the outlet pressure rises again and reaches the level of the inlet pressure. For this reason, a pressure compensator is selected to control the switching element, which is acted upon by load pressure control.

Thus, for example, a procedure would be to see that a compressed air treatment device fills with an inlet pressure without a pressure difference to the inlet pressure being detectable at the outlet. This situation means that no compressed air is taken off.

Thus, the invention proposes that the switching element includes a load pressure-controlled or control pressure-dependent pressure compensator. This pressure compensator is designed for a load pressure independent operation. In this case, such a switching element is automatically activated as soon as, for example, a sufficient amount of air flows through the module or the module and a differential pressure reaches the switching threshold, which brings the pressure balance out of balance and thereby changed the switching element in its switching position. If such a flow is stopped, the output pressure rises again and the inlet pressure is equal to the outlet pressure, which means that the switching element due to the pressure compensator returns to its initial position and its closed position, for example, resumes.

By using a pressure compensator, it is possible with a small pressure difference such a switching element in two switching states namely closed or open to spend. In this case, the pressure balance consists essentially of an annular clamped membrane with a spring constant. In a preferred embodiment, the membrane is formed with beads or the like in the edge region. In addition to the preferred bead shape, it is also possible to use flat membranes, because they are cheaper priced. However, with flat membranes a precise switching point can only be realized with high costs. In a further preferred embodiment, it may also be rolling membranes, which are produced in a mold. Such rolling membranes are produced in a compression or spraying process and then vulcanized. The advantage of such a membrane is that it is very smooth and has little friction. It can perform a very high accuracy with only a few forces by low strokes.

Alternatively, with very thin flat membranes, which are biased to a small extent, such an embodiment of the invention is also possible. Once a stroke is performed, the membrane would relax. By biasing the flat membrane alone can relax back into the horizontal position but it is prevented by a counter-pressure spring.

An embodiment with pistons is very expensive and technically not necessarily a very good design, since they have relatively high friction forces and membranes, in contrast, work smoothly.

It has therefore proven to be expedient that the bead membranes are inexpensive to manufacture and can be tuned in their switching behavior exactly on the balance of power.

The membrane used in the switching element is designed so that the membrane underside and the membrane top side have the same active surfaces.

The pressure compensator is in operative connection with a spring-loaded actuating device. The adjusting device consists essentially of a plunger with directly or indirectly associated valve seat of a valve.

Since the membrane top, for example, with an inlet pressure P ₁ and the membrane bottom are subjected to a pressure P _2, which are equal in amount, the pressure balance remains in the balance, because from both sides, the pressures are the same. Only by a pressure difference, the pressure balance and thus the switching element would be activated. At the moment when a switching threshold is exceeded and the differential pressure has a certain amount, the switching operation is performed. Such a differential pressure between P ₁ and P ₂ thus leads to a switching operation. Such a switching operation can open or close the switching element, depending on the training.

With the pressure compensator is in operative connection with the switching element, which acts directly or indirectly on the valve. In the case of pressure drop at the outlet thus the membrane of the pressure compensator is brought out of balance and simultaneously actuates the valve, so that the purging air can only flow when a pressure difference between the inlet pressure and outlet pressure is present.

When the outlet of the compressed air treatment device is closed again, the outlet pressure will increase again up to the amount of the inlet pressure. This means that the pressure compensator comes back into equilibrium and thereby the actuator causes a closure of the valve, which means a shutdown of the purge air.

This procedure makes it clear that only at a pressure drop, i. H. it is compressed air consumed, it comes to a switching of the purge air in the membrane dryer.

The invention will be explained in more detail with reference to the drawings.

It shows:

1 : A schematic diagram of a membrane dryer;

2 a first preferred embodiment of a switching element;

3 A second preferred embodiment of a switching element.

By the 1 is a block diagram of an exemplary use of a switching element 4 in conjunction with a membrane dryer 5 played. It is to an actuating means 1 an input pressure P _{1 is} applied, for example, a pressure regulator 2 and Z. B. Filter level 3 passes through before entering the membrane dryer 5 entry. At the same time, the inlet pressure P _{1 is} also on the with the membrane dryer 5 connected switching element 4 fluidly further connected. At the exit of the membrane dryer 5 is an output pressure P ₂ , which also also to the switching element 4 is forwarded. Inside the membrane dryer 5 are usually hollow fiber elements, which provide for an absolutely clean air at the exit. In order to be able to remove even vaporous particles from the clean compressed air, a so-called purge air is present, which is branched off from the clean output air and through the switching means 4 according to demand only at a consumption of the outlet pressure 2 through the membrane dryer 5 as P _{S is} passed. With such a scavenging air, it is possible to get the last water components out of the compressed air. In addition to an adaptive application of the switching element 4 Of course it is also possible that this in the membrane dryer 5 is integrated. The switching element is executed 4 as a pneumatic switch that does not require any external power to properly perform its switching functions.

For better clarity is according to the 2 the upper part of a compressed air treatment device, in particular the structure of the switching element 4 , reproduced in a sectional view. Here is the switching element 4 on the membrane dryer 5 about connections 16 replaceable mounted.

Within the switching element 4 There is a pressure compensator, which is essentially formed by a smooth-running membrane 19 is realized. The membrane 19 has been performed in the embodiment as a bead membrane. At the bottom of the membrane 19 is a printing plate 22 and at the top of the membrane 19 a printing plate 20 with the membrane 19 connected. Thus, the middle region of the membrane 19 stiffened so that such a pressure compensator can also respond to small minor pressure changes. The membrane 19 is clamped laterally annular, so that they can be replaced even in the event of a defect.

With the pressure compensator is in operative connection with the active part of the switching element 4 , The pressure compensator acts via a valve tappet 11 on a valve seat 12 one, in this case by a spring 10 is loaded and thus in the closed state against the pressure plate 22 comes to the plant. The feather 10 relies on a closure 9 that is in the upper part of the switching element 4 is off. The valve lifter 11 is still over a ring seal 23 opposite a pressure chamber 7 which is at the bottom of the membrane 19 is located, sealed.

As the switching element 4 works without any additional external energy, is subsequent to the operation of this switching element 4 in particular received. An activation of the switching element 4 occurs only when an occurrence of a pressure difference between the inlet pressure P ₁ and the outlet pressure P ₂ otherwise the pressure balance is in equilibrium, which triggers no switching state. The differential pressure, from the inlet pressure P ₁ and the outlet pressure P ₂ , which can be referred to as differential pressure, is at a pressure loss at the outlet of the membrane dryer 5 generates and thus brings the pressure compensator out of balance. Here, a corresponding switching threshold is provided in order not to encourage minor pressure fluctuations to swing the pressure compensator. As soon as the inlet pressure P ₁ and the outlet pressure P ₂ are equal in magnitude again, the valve is automatically closed via the pressure compensator.

The inlet pressure P ₁ , which is in the membrane dryer 5 is routed in a channel branches 17 and passes through a connection hole 21 in a pressure room 18 , which is located on the top of the pressure compensator. This pressure P ₁ is thus able to open the valve in the absence of a pressure P ₂ or a pressure difference. So that this does not happen, the output pressure P ₂ via a channel 6 and in continuation over a canal 8th in the pressure room 7 led to the bottom of the pressure compensator. As long as P ₁ and P ₂ are equal in magnitude, the valve remains 12 in its rest position, ie it is closed.

At the moment when the outlet pressure P ₂ drops, this can be, for example, the removal of appropriate compressed air from the membrane dryer 5 mean, the pressure compensator is brought out of balance. This has the consequence that the pressure P _{1 is} greater than P ₂ , and the pressure compensator via the valve stem 11 the valve seat 12 opens. The channel 8th has also been continued in this embodiment and thus ends next to the pressure chamber 7 also in the area of the valve seat 12 , As long as the valve seat 12 remains in its closed position, the pressure P ₂ via the valve can not enter the channel 15 reach. Next to the valve 12 however, it is an aperture 13 present, which allows a very low flow of compressed air (bypass).

Opens the valve 12 , so the pressure P ₂ over the channel 15 and an aperture at the exit 14 as purge air P _S in the membrane dryer 5 promoted. Since it is a very dry compressed air in the scavenging air, this is particularly suitable to the residual water content from the Compressed air inside the membrane dryer 5 to eliminate. On the special function of the membrane dryer need not be discussed at this point, since this is not relevant to the invention.

In a further preferred embodiment, the use of the apertures 13 and 14 be dispensed so that purge air P _S directly through the switched switching element 4 in the membrane dryer 5 can be directed.

Due to the not conclusively shown possibilities in the figures, a switching element of pneumatic type has been used, the load pressure-controlled or control pressure-dependent is acted upon by a pressure compensator.

LIST OF REFERENCE NUMBERS

1

actuating means

2

pressure regulator

3

filter stage

4

switching element

5

membrane dryer

6

channel

7

pressure chamber

8th

channel

9

shutter

10

feather

11

tappet

12

valve seat

13

cover

14

cover

15

channel

16

connection

17

channel

18

pressure chamber

19

membrane

20

printing plate

21

connecting bore

22

printing plate

23

poetry

P ₁

inlet pressure

P ₂

output pressure

P _S

purge air

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19722731 A1 [0002]
• DE 202004017303 U1 [0003]

Claims (13)

Compressed air treatment device, in particular membrane dryer, which has a membrane filter, and having a compressed air inlet P ₁ and a compressed air outlet P ₂ for dried compressed air and a scavenging air inlet, wherein the scavenging air inlet is assigned a blocking means, characterized in that the blocking means as a pneumatic switching element ( 4 ) is formed and has a pressure compensator, which is applied under load pressure control. Compressed air treatment device, in particular membrane dryer, which has a membrane filter, and having a compressed air inlet P ₁ and a compressed air outlet P ₂ for dried compressed air and a scavenging air inlet, wherein the scavenging air inlet is assigned a blocking means, characterized in that the blocking means as a pneumatic switching element ( 4 ) is formed and is acted upon by a pressure balance, the load pressure controlled or control pressure dependent works. Compressed air treatment device according to claim 1 or 2, characterized in that the switching element ( 4 ) is used as shut-off or Zuschaltmittel for purging air. Compressed air treatment device according to one of the preceding claims, characterized in that the pressure compensator essentially consists of an annularly clamped membrane ( 19 ) with a spring constant, wherein the membrane underside and membrane top have the same active surfaces. Compressed air treatment device according to claim 1 or 2, characterized in that the pressure compensator is in operative connection with a spring-loaded adjusting device. Compressed air treatment device according to one of the preceding claims, characterized in that the adjusting device consists essentially of a plunger ( 11 ) with directly or indirectly associated valve seat ( 22 ) consists of a valve. Compressed air treatment device according to one of the preceding claims, characterized in that the membrane top side with a pressure P ₁ and the diaphragm underside with a pressure P _{2 are} applied, wherein for activating the switching element ( 4 ) a switching threshold must be reached, which is formed from a differential pressure between P ₁ and P ₂ . Compressed air treatment device according to one of the preceding claims, characterized in that for actuating the switching element ( 4 ) the necessary force is changeable. Compressed air treatment device according to one of the preceding claims, characterized in that the switching element ( 4 ) and / or the membrane ( 19 ) is / are interchangeable. Compressed air treatment device according to one of the preceding claims, characterized in that the membrane ( 19 ) is formed as a bead membrane or the like. Compressed air treatment device according to one of the preceding claims, characterized in that the switching element ( 4 ) is designed as a module with a housing. Compressed air treatment device according to one of the preceding claims, characterized in that the switching element ( 4 ) adaptive or integrative with the membrane dryer ( 5 ) connected is. Pneumatic switching element actuated by a pressure compensator for use in a scavenge air line or the like.

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