Device for monitoring the particle load of a compressed gas or gas mixture, compressor system comprising such a monitoring device, and method for operating such a monitoring device

Abstract

The invention relates to a device (100) for monitoring the particle load of a gas or gas mixture compressed to a predetermined first pressure, the device comprising a discharge line (102) which is designed and intended to forward the gas or gas mixture provided at the predetermined first pressure by a compressor (104), which is not part of the monitoring device (100), to a consumption point (106) which is also not part of the monitoring device (100). According to the invention, the monitoring device (100) also comprises: a branch line (108) which is connected to the discharge line (102) and is designed and intended to branch off part of the compressed gas or gas mixture; a pressure reducer (110) which is designed and intended to reduce the pressure of the gas or gas mixture to a second pressure; and a particle measuring device (112) which is connected to a section (108a) of the branch line (108) arranged downstream of the pressure reducer (110).

Description

[0001] Device for monitoring the particle load of a compressed gas or gas mixture, compressor system with such a monitoring device and method for operating such a monitoring device

[0002] Description

[0003] The invention relates to a device for monitoring the particle load of a gas or gas mixture compressed to a predetermined pressure.

[0004] Although the device according to the invention can in principle be used with any gases and gas mixtures, it will be explained below using breathing air as an example, since compressed breathing air must, for understandable reasons, meet very high requirements. These requirements are laid down, for example, in the European breathing air standard EN 12021 and the US standard NFPA 1989 (Standard on breathing air quality for emergency services respiratory protection). A key difference between the two standards is that the NFPA also specifies a limit for particles (Condensed oil and particulate content test). This limit is currently 2 mg / m 3 and must currently be determined using a graphimetric method.

[0005] In this context and in connection with the present invention, particles are considered to be particles in liquid form, e.g. oil droplets, or particles in solid form, e.g. dust particles.

[0006] To meet the requirements, samples of the gas or gas mixture must be taken at least every three months, and additionally during maintenance work, and sent to a laboratory for analysis. This process is inefficient because the compressor may not be put back into operation until an analysis confirms compliance with the aforementioned limit value. Furthermore, this process is expensive and does not provide complete monitoring, as the particle load of the compressed gas or gas mixture can fluctuate greatly due to short-term changes in the compressor's operating conditions and depending on the air quality of the intake air supplied to the compressor.

[0007] It is therefore an object of the present invention to make the monitoring of the particle load of the gas or gas mixture more efficient.

[0008] This object is achieved according to the invention by a device for monitoring the particle load of a gas or gas mixture compressed to a predetermined first pressure, which device comprises a discharge line designed and intended to convey the gas or gas mixture provided by a compressor not belonging to the monitoring device at the predetermined first pressure to a consumption point also not belonging to the monitoring device, wherein the monitoring device further comprises a branch line connected to the discharge line and designed and intended to branch off a portion of the compressed gas or gas mixture, as well as a pressure reducer associated with the branch line, which is designed and intended to reduce the pressure of the gas or gas mixture to a second pressure whose value is lower than the value of the first pressure, and a particle measuring device,which is connected to a section of the branch line downstream of the pressure reducer.

[0009] In this way, the particle load of the gas or gas mixture can be determined during operation, i.e. continuously, or at least at significantly shorter intervals. Furthermore, the administratively complex process of sending samples to an external laboratory is eliminated, as the particle load can be monitored on-site. Finally, the evaluation results are obtained in real time, thus eliminating lengthy interruptions to compressor operation. In a further development of the invention, it is proposed that the particle measuring device be a laser particle measuring device, preferably a mobile laser particle measuring device. Such laser particle measuring devices can be purchased, for example, from CS INSTRUMENTS GmbH & Co. KG, ccstec GesmbH, SUTO iTEC GmbH, or Walter Stauffenberg GmbH & Co. KG.

[0010] In order to be able to reduce the pressure of the gas or gas mixture as gently as possible, i.e. as free as possible from pressure surges and / or pressure fluctuations, it is proposed that the pressure reducer comprises a valve seat formed on a pressure reducer housing and a movable piston which can be pressed against the valve seat and which has an inflow surface limited by the valve seat on the upstream side, wherein the piston is designed as a stepped piston which has a smaller piston surface on its side facing the upstream side and a larger piston surface on the downstream side, the surface area of ​​which is greater than the surface area of ​​the smaller piston surface, wherein when the piston is lifted from the valve seat, both the smaller piston surface and, via an overflow line, the larger piston surface are acted upon by the gas or gas mixture, and that a flow limiting unit is assigned to the pressure reducer.

[0011] The pressure acting on the inflow surface attempts to push the piston towards its open position, in which it is lifted off the valve seat. Conversely, the pressure acting on the difference between the larger and smaller piston areas pushes the piston towards its closed position, in which it rests against the valve seat. The cross-sectional area of ​​the overflow line must be selected such that essentially the same pressure acts on both the larger piston area and the smaller piston area. In this context, the flow limitation unit reduces the influence of the cross-sectional area of ​​the overflow line and also prevents the upstream pressure from collapsing due to excessive gas or gas mixture throughput after the piston has lifted off the valve seat.In this way, a quasi-stationary floating state is quickly established, in which the piston is lifted just enough from the valve seat to balance the pressure forces acting on it in the opening and closing directions. Only the pressure fluctuations in the gas or gas mixture caused by the compressor still need to be compensated for by slight movements of the piston.

[0012] Due to this quasi-stationary suspension, the piston and the entire pressure reducer neither promote the adhesion nor the detachment of particles from the edges and surfaces of the monitoring device. In other words, the pressure reducer practically does not distort the measured particle count.

[0013] This effect can be further enhanced by designing a section of the pressure reducer housing forming the valve seat and / or at least a section of the piston interacting with the valve seat to reduce the flow resistance it offers to the incoming gas or gas mixture when the piston is lifted from the valve seat. The lower the flow resistance, the weaker the interaction of the passing gas or gas mixture with the aforementioned components, i.e., the lower the probability that a particle entrained by the gas or gas mixture will attach to or be detached from the respective component.

[0014] A simple pressure reducer design can be achieved by having the overflow line pass through the piston, preferably centrally. In this case, a separate overflow line is unnecessary.

[0015] In order to ensure that the piston can react sensitively to pressure changes in the gas or gas mixture present, it is proposed that a spring unit be accommodated in a step chamber of the pressure reducer housing arranged between the smaller piston surface and the larger piston surface, which is preferably connected to the external environment. This spring unit urges the piston into a position lifted from the valve seat. This spring unit thus supports the piston in overcoming the so-called breakaway torque. It should be noted that the force of the spring unit was not taken into account in the above description of the function of the pressure reducer. However, this circumstance leads to the fact that the monitoring device according to the invention can be used with particular advantage in conjunction with high-pressure compressors, i.e.Compressors whose discharged gas or gas mixture can have a first pressure between approximately 90 bar and approximately 550 bar, and the amplitude of the pressure fluctuations occurring in these high-pressure compressors typically exceeds atmospheric pressure, result in only negligible deviations. The second pressure delivered by the pressure reducer, whose value can be between approximately 1.5 bar and approximately 15 bar, can therefore be very well described solely by the area ratio A1 / (A3-A2).

[0016] To enable maintenance or temporary shutdown of the monitoring device, a shut-off unit can be assigned to the pressure reducer. In this context, it should be noted that the flow-limiting unit can be designed as a flow-limiting nozzle, which can preferably be integrated into the shut-off unit.

[0017] At this point, it should be noted that the pressure reducer described above is similar in design and function to the B-DRAIN condensate drain valve marketed by the applicant, which is also described and illustrated in WO 201 1 / 060909 A1. Although, according to the present application, a gas or gas mixture is passed through the pressure reducer, while in WO 201 1 / 060909 A1 a condensate, i.e., a liquid, is passed through the B-DRAIN condensate drain valve, it has surprisingly been found that, despite the different viscosities of liquids and gases, a similarly designed pressure reducer can also be advantageously used in the monitoring device according to the invention.

[0018] In order to be able to check the proper functioning of the particle measuring device at regular intervals, a further development of the invention can provide that the monitoring device comprises a bypass line that runs parallel to a section of the branch line located downstream of the pressure reducer but upstream of the particle measuring device, and in which a zero filter is arranged. By means of the zero filter, any particles contained in the gas or gas mixture can be reliably retained, so that the measurement result to be delivered by the particle measuring device is known in advance. By comparing the results with the actual measurement result, conclusions can be drawn about the functionality of the particle measuring device.

[0019] If directional control valves are provided at the beginning and end of the bypass line, which alternatively direct the flow of gas or gas mixture via the section of the branch line downstream of the pressure reducer or the bypass line, it is possible to switch back and forth between a "normal" measuring operation and a function test operation.

[0020] To enable remote maintenance, it is advantageous if the shut-off unit and / or the directional control valves can be remotely operated and / or the measurement results of the particulate filter can be remotely retrieved. This allows the operator of the monitoring device or the compressor to which the monitoring device is assigned, and / or a maintenance company, for example, the manufacturer of the monitoring device and, if applicable, the compressor, to remotely switch the monitoring device from "normal" measurement mode to functional test mode to check whether the particulate measuring device is still functioning properly.

[0021] If, in addition to the measurement results from the particulate filter, additional parameters are recorded and stored, for example, in a data cloud, such as parameters describing the operation of the compressor and / or the ambient conditions, the operation of the monitoring device and, if applicable, the compressor can be monitored remotely. This monitoring can complement the already known remote monitoring of certain gas components, particularly CO, CO2, O2, H2O, and VOCs (Volatile Organic Compounds) in the gas or gas mixture.

[0022] As already mentioned above, the monitoring device according to the invention can be used with particular advantage when the gas mixture is breathing air.

[0023] The invention further relates to a compressor system with a compressor, a consumption point and a monitoring device according to the invention, in which the compressor is connected to the inlet side of the discharge line and the consumption point is located on the discharge side of the discharge line.

[0024] It should be noted at this point that, even with the most smoothly operating pressure reducer, it can never be ruled out in practice that one or another particle may become deposited on an edge and / or surface of the pressure reducer and / or another of the aforementioned components and / or one of the lines connecting them during operation and then detach again at a later point in time. In this context, not only pressure fluctuations in the gas or gas mixture play a role, but also vibrations originating from the compressor and / or other sources of vibration that propagate through the monitoring device.Since this effect makes it difficult, if not impossible, to assign the measurements of the particle measuring device to an actual measurement time, the invention further relates to a method for operating a monitoring device according to the invention or a compressor system according to the invention, in which method the particle measuring device continuously monitors the particle load of the gas or gas mixture compressed to the first pressure at least during a predetermined first period of time. Through the continuous monitoring, at least effects resulting from the opening and closing of the shut-off unit can be excluded or at least minimized. In a further development of this aspect of the invention, it can further be provided that the monitoring result is averaged over a predetermined second period of time, which is shorter than the first period of time.

[0025] The invention will be explained in more detail below using an exemplary embodiment with reference to the accompanying drawing. It shows:

[0026] Figure 1 is a schematic diagram to explain the basic structure and function of the monitoring device according to the invention; and

[0027] Figure 2 is a sectional view of the design of a specific embodiment of a pressure reducer.

[0028] In Figure 1, a device according to the invention for monitoring the particle load of a gas or gas mixture compressed to a predetermined first pressure is generally designated 100.

[0029] The monitoring device 100 comprises a discharge line 102, which conveys the gas or gas mixture provided by a compressor 104 at the predetermined first pressure p1 to a consumption point 106. A branch line 108 branches off from the discharge line 102 and conveys a portion of the compressed gas or gas mixture via a pressure reducer 110 to a particle measuring device 112, which is preferably designed as a laser particle measuring device. The pressure reducer 110 has the task of reducing the pressure of the gas or gas mixture from the first pressure p1 to a lower second pressure p2. Furthermore, the pressure reducer 110 is assigned a flow-limiting unit 114, which simultaneously serves as a shut-off unit 116.

[0030] In order to regularly check the functionality of the particle measuring device 112, a bypass line 118 is also provided. This bypass line is arranged parallel to a section 108a running between the shut-off unit 116 and the particle measuring device 112. A zero filter 120 is provided in the bypass line, which filters out any particles present in the gas or gas mixture. The bypass line 118 can be selectively activated via two directional valves 122, 124.

[0031] Lightning symbols in Figure 1 generally indicate that the shut-off unit 116 and / or the directional control valves 122, 124 can be remotely operated or that the measurement data of the particle measuring device 112 can be remotely retrieved.

[0032] Since Figure 1 also shows the compressor 104 and the consumption point 106, this figure also shows the entire compressor system 130.

[0033] With reference to Figure 2, the structure and function of the pressure reducer 110 will now be explained in more detail.

[0034] The pressure reducer 110 comprises a movable piston 142 accommodated in a pressure reducer housing 140, which can be pressed against a valve seat 144 formed on the pressure reducer housing 140. The valve seat 144 defines the inflow area A1, via which the piston 142 is subjected to the upstream pressure p1 of the gas or gas mixture.

[0035] Piston 142 is designed as a stepped piston, with an upstream, smaller-diameter section 146 and a downstream, larger-diameter section 148. A smaller piston area A2 is formed on the upstream side of the smaller-diameter section 146, and a larger piston area A3 is formed on the downstream side of the larger-diameter section 148. The two piston areas A2 and A3 are connected to one another via an overflow channel 150, whose cross-sectional area A4 is dimensioned such that the same pressure p2 is present at both piston areas A2 and A3.

[0036] For the sake of completeness, it should be mentioned that a spring unit 156 is arranged in a step chamber 150, which is provided in the transition region between the two piston sections 146, 148 and which is connected to the external environment, i.e., to atmospheric pressure, via a branch line 154. However, for the reasons explained above, this spring unit 156 is not relevant for understanding the function of the pressure reducer 110.

[0037] The pressure p1 acting on the inflow area A1 attempts to push the piston 142 towards its open position, i.e. downwards in Figure 2, in which it is lifted off the valve seat 144. In contrast, the pressure p2 acting on the difference (A3-A2) between the larger piston area A3 and the smaller piston area A2 pushes the piston 142 towards its closed position, in which it rests on the valve seat 144. The cross-sectional area A4 of the overflow line 150 must be selected such that essentially the same pressure p2 acts on both the larger piston area A3 and the smaller piston area A2. In this context, the flow limiting unit 114 (see Figure 1) prevents the inflow-side pressure p1 from collapsing due to an excessive throughput of gas or gas mixture after the piston 142 has been lifted off the valve seat 144.In this way, a quasi-stationary floating state is quickly established, in which the piston 142 is lifted just enough from the valve seat 144 to balance the pressure forces acting on it in the opening and closing directions. Only the pressure fluctuations in the applied gas or gas mixture resulting from the compressor 104 still need to be compensated for by slight movements of the piston 142.

[0038] For the sake of completeness, the sealing elements shown in Figure 2

[0039] 160 and 162, which seal the piston 142 relative to the housing 140.

Claims

Claims 1 . A device (100) for monitoring the particle load of a gas or gas mixture compressed to a predetermined first pressure (p1), comprising: a discharge line (102) designed and intended to convey the gas or gas mixture provided by a compressor (104) not belonging to the monitoring device (100) at the predetermined first pressure (p1) to a consumption point (106) likewise not belonging to the monitoring device (100), characterized in that it further comprises: a branch line (108) connected to the discharge line (102) and designed and intended to branch off a portion of the compressed gas or gas mixture, a pressure reducer (110) associated with the branch line (108) designed and intended to reduce the pressure of the gas or gas mixture to a second pressure (p2) whose value is lower than the value of the first pressure (p1), and a particle measuring device (112),which is connected to a section (108a) of the branch line (108) downstream of the pressure reducer (110).

2. Monitoring device according to claim 1, characterized in that the particle measuring device (1 12) is a laser particle measuring device.

3. Monitoring device according to claim 1 or 2, characterized in that the pressure reducer (1 10) comprises a valve seat (144) formed on a pressure reducer housing (140) and a movable piston (142) which can be pressed against the valve seat (144) and which has an inflow area (A1) delimited by the valve seat (144) on the upstream side, wherein the piston (142) is designed as a stepped piston which has a smaller piston surface (A2) on its side facing the inflow side and a larger piston surface (A3) on the outflow side, the surface area of ​​which is greater than the surface area of ​​the smaller piston surface (A2), wherein when the piston (142) is lifted from the valve seat (144), both the smaller piston surface (A2) and, via an overflow line (150), the larger piston surface (A3) are acted upon by the gas or gas mixture, and that a flow limiting unit (114) is assigned to the pressure reducer (110).

4. Monitoring device according to claim 3, characterized in that a section of the pressure reducer housing (140) forming the valve seat (144) and / or at least one section of the piston (142) cooperating with the valve seat (144) is / are designed to reduce the flow resistance which it / they oppose to the incoming gas or gas mixture when the piston (142) is lifted off the valve seat (144).

5. Monitoring device according to claim 3 or 4, characterized in that the overflow line (150) passes through the piston (142), preferably centrally.

6. Monitoring device according to one of claims 3 to 5, characterized in that in a step chamber (152) of the pressure reducer housing (140) arranged between the smaller piston surface (A2) and the larger piston surface (A3), which is preferably connected to the external environment, a spring unit (156) is accommodated, which urges the piston (142) into a position lifted from the valve seat (144).

7. Monitoring device according to one of claims 3 to 6, characterized in that a shut-off unit (116) is assigned to the pressure reducer (110).

8. Monitoring device according to one of claims 1 to 7, characterized in that it comprises a bypass line (118) which runs parallel to the section (108a) of the branch line (108) arranged downstream of the pressure reducer (110) and in which a zero filter (120) is arranged.

9. Monitoring device according to claim 8, characterized in that directional control valves (122, 124) are provided at the beginning and at the end of the bypass line (118), which direct the flow of gas or gas mixture alternatively via the section (108a) of the branch line (108) arranged downstream of the pressure reducer (110) or the bypass line (118).

10. Monitoring device according to one of claims 1 to 9, characterized in that the shut-off unit (116) and / or the directional control valves (122, 124) can be remotely actuated and / or the measurement results of the particle filter (112) can be remotely retrieved. 11 . Monitoring device according to one of claims 1 to 10, characterized in that the gas mixture is breathing air.

12. Monitoring device according to one of claims 1 to 11, characterized in that the first pressure (p1) has a value of between about 90 bar and about 550 bar.

13. Monitoring device according to one of claims 1 to 12, characterized in that the second pressure (p2) has a value of between about 1.5 bar and about 15 bar.

14. Compressor system (130) with a compressor (104), a consumption point (106) and a monitoring device (100) according to one of the preceding claims, in which the compressor (104) is connected to the inlet side of the discharge line (102) and the consumption point (106) is located on the discharge side of the discharge line (102).

15. A method for operating a monitoring device (100) according to one of the preceding claims or a compressor system (130) according to claim 14, wherein the particle measuring device (112) continuously monitors the particle load of the gas or gas mixture compressed to the first pressure (p1) at least during a predetermined first time period, wherein the monitoring result is preferably averaged over a predetermined second time period which is shorter than the first time period.

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