Apparatus and method for degassing a device and corresponding test system for gas analysis

Abstract

In order to degas a device (7), a device (10) is provided, which comprises a control unit (19), a pump (3), a first volume (1), a second volume (2), a first valve (12) and a second valve (13). At the discharge end, the pump (3) is connected to the first volume (1), at the suction end, the pump (3) is connected to the second volume (2) through the second valve (13) and can be connected to the device (7) to be degassed. The first volume (1) and the second volume (2) are connected through the first valve (12).

Description

TECHNICAL FIELD

[0001] The invention relates to a device and a method for degassing a device, wherein the extracted gas is compressed, for example in order to be able to analyze the dissolved gas better. BACKGROUND

[0002] For example for condition determination and error recognition of oil-paper insulated power transformers, the analysis of the gases dissolved in the insulating oil (Dissolved Gas Analysis, DGA) is an important method. Before the analysis, the gases to be analyzed must be separated from the insulating oil (for example), which is known as degassing. This degassing can be carried out in various ways. The highest extraction rate can be achieved by vacuum complete degassing.

[0003] For example, the lower the pressure in the container or volume containing the gas, the more effective the extraction of the gas from the insulating oil. The lower the pressure difference between the pressure at the gas inlet and the pressure at the gas outlet, the more effective the degassing pump for carrying out this gas extraction. Therefore, according to the prior art, the volume at the pump outlet is selected such that the pressure in this volume does not rise too much during the degassing or extraction process.

[0004] However, many analysis methods require the gas concentration to be as high as possible in order to be able to detect certain gas components or certain gases contained in the extracted gas as well as possible. SUMMARY

[0005] The task set by the invention is therefore to extract the gas at low pressure during the degassing process and to extract the gas at high pressure when analyzing the extracted gas. In doing so, the means for solving this contradiction should be as inexpensive as possible and require as little space as possible.

[0006] Within the framework of the invention, a device for degassing a device, in particular a degassing container, is provided. The device comprises a control unit, a pump, a first volume or container, a second volume or container, a first valve and a second valve. The pump is connected to the first volume, also referred to as high-pressure volume, at the outlet end in order to be able to pump gas into the first volume. The first volume and the second volume, also referred to as low-pressure volume, are connected to each other by means of the first valve, such that depending on the state of the valve (open or closed), the first volume is connected to the second volume or the two volumes are separated. At the inlet end, the pump is connected to the second volume by means of the second valve, such that when the second valve is open, the pump can pump gas out of the second volume. At the inlet end, the pump can be connected to the device to be degassed, such that when the pump is connected to the device, the pump can pump gas away from the device or out of the device.

[0007] The device according to the invention advantageously makes it possible to pump or to convey the extraction gas during the degassing into two volumes, so that the pressure at the discharge end of the pump is only slightly increased. After the degassing, the same pump can pump the extraction gas from the second volume into the first volume, as a result of which the pressure of the extraction gas in the first volume increases. The invention thus fulfils the above-mentioned task.

[0008] The second volume or low-pressure volume is preferably at least five times larger, more preferably ten times larger, even 20 times larger than the first volume or high-pressure volume. However, it is also possible (depending on the amount of gas present and the amount of gas on the pump) that the second volume or low-pressure volume is 100 times or even 1000 times larger than the first volume or high-pressure volume.

[0009] According to this embodiment, the high-pressure volume is significantly smaller than the low-pressure volume. The volume of the low-pressure volume is advantageously chosen so that the pressure at the discharge end of the pump does not rise during the degassing so as to impair the efficiency of the pump.

[0010] In an exemplary application, only a small amount of gas (approximately 1 ml) is available. In this case, the size of the first volume (high-pressure volume) can be 0.5 ml and the size of the second volume (low-pressure volume) can be 10 ml.

[0011] The absolute size of the volumes generally depends on the amount of gas to be measured or that can be measured (i.e. available). The absolute size of the volumes also depends on the sensor used (for analysing the gas). Of course, the volumes can also be in the μl range (i.e. significantly smaller than 1 ml). On the other hand, it is also possible to produce several litres of gas (for example during the measurement of emissions), whereupon a corresponding larger volume (in the range of 1 1 to 20 1) is chosen.

[0012] The ratio between the gas volume (volume of the gas to be analysed or degassing volume) and the first volume and the second volume is essentially similar. The second volume (low-pressure volume) is mostly chosen to be equal to or larger than the gas volume, while the first volume (high-pressure volume) is significantly smaller. This ratio can depend on the pump used. For example, when a high-pressure pump is used, the second volume (low-pressure volume) can be only, for example, one tenth of the gas volume. In this case, the second volume will thus be smaller than the gas volume.

[0013] According to an embodiment of the invention, the device opens the first valve and closes the second valve with the aid of the control unit of the device. After the first valve has been opened and the second valve has been closed, the control unit activates the pump in order to pump the gas from the device to be degassed into the first volume and into the second volume, which is connected to the first volume by means of the first valve.

[0014] Since the first valve is open, the pump pumps gas in the degassing step into a very large volume corresponding to the sum of the first volume and the second volume. Due to this large volume, the pressure in this volume advantageously hardly rises during the degassing step. As a result, during the degassing step, one can work for a long time at as low a pressure as possible in the first volume, ideally an absolute vacuum, and with a very low pressure difference between the first volume and the second volume. As a result, one can advantageously extract from the device to be degassed a gas with a wide solubility coefficient, so that all the gas can be released and the ratio of the extracted gas also corresponds to the ratio of the gas in the device, for example in the insulating oil.

[0015] According to an embodiment of the invention, the device closes the first valve and opens the second valve with the aid of the control unit of the device. After the first valve is closed and the second valve is opened, the control unit activates the pump in order to pump gas from the second volume or low-pressure volume into the first volume or high-pressure volume.

[0016] Since the second valve is open, the pump can pump gas from the low-pressure volume into the high-pressure volume in the compression step after the degassing step in order to increase the pressure there. With the higher pressure, the concentration of the gas increases, which facilitates the subsequent analysis.

[0017] According to an embodiment of the invention, the device comprises a third valve. The device to be degassed is connected to the gas inlet of the pump via the third valve.

[0018] The third valve can permanently connect the device to the device to be degassed via the third valve. With the aid of the third valve, one can very simply control the degassing step and the compression step. During the degassing step, the third valve is opened so that the pump can pump gas away from the device to be degassed. In contrast, the third valve is closed in the compression step so that the pump pumps only gas from the second volume (and no other gas from the device) into the first volume. This will be described more precisely in the following embodiments.

[0019] According to an embodiment of the invention, the device opens the first valve and the third valve and closes the second valve with the aid of the control unit of the device. After the first valve and the third valve are opened and the second valve is closed, the control unit activates the pump in order to pump gas from the device to be degassed into the first volume and the second volume connected to the first volume via the first valve.

[0020] Since the first valve and the third valve are open, the pump pumps gas in the degassing step into the first volume and the second volume connected to the first volume via the first valve. As a result, one can work for a long time at a very low pressure in the first volume and the second volume during the degassing step, so that all the gas can be advantageously released in the device.

[0021] According to an embodiment of the present invention, with the assistance of the device's control unit, the device closes the first and third valves and opens the second valve. After the first and third valves are closed and the second valve is opened, the control unit activates the pump to pump gas from the second volume or low-pressure volume into the first volume or high-pressure volume.

[0022] Since only the second valve is open, and the first and third valves are closed, the pump only pumps gas from the low-pressure volume into the high-pressure volume during the compression step. Because the third valve is closed, the pump does not extract gas from the equipment, and because the first valve is also closed, the pump does not extract gas (through the low-pressure volume) from the high-pressure volume.

[0023] According to an embodiment of the invention, the device includes a sensor. The sensor is at least partially arranged within a first volume and is designed to analyze the gas in the first volume.

[0024] With the aid of a sensor, the gas in the first volume or high-pressure volume can be analyzed in a nearly automated manner after the compression step. This sensor measures the gas. The sensor can be a semiconductor sensor, an optical sensor (or optical measuring device), a thermal conductivity sensor, or a chemical analysis device (e.g., a gas chromatograph). In other words, the sensor can be any device capable of measuring gases, where these gases are required to have the highest possible (absolute) concentration.

[0025] The apparatus according to the invention advantageously allows the degassing and compression steps to be performed using only one, or more precisely, the same pump. In the compression step, the pressure in the high-pressure volume can be increased until the desired pressure value is reached, all gas is pumped out of the low-pressure volume, or the pump's capacity is exhausted. By using only one pump for both degassing and compression, space requirements and the cost of additional pumps are advantageously saved.

[0026] Even if not all the gas is pumped from the low-pressure volume to the high-pressure volume during the compression step, the gas ratio is advantageously kept the same as the gas ratio in the equipment (e.g., in the insulating oil). This would not be the case, for example, if the pump directly pumps the gas from the equipment into the high-pressure volume during the compression step. Furthermore, due to the higher inlet pressure, the pressure generated in the high-pressure volume during the compression step can be higher than the pressure during direct degassing (without the low-pressure volume).

[0027] Within the framework of this invention, a testing system is also provided for testing one or more gases dissolved in or at equipment (such as high-voltage equipment). According to the invention, the testing system includes an evaluation unit and a degassing device as described above. The testing system is designed to analyze gases inside or from the equipment (e.g., analyze gases dissolved in the insulating oil of high-voltage equipment). The evaluation unit is designed to analyze the gas pumped into a first volume (e.g., with the assistance of sensors in the device), and based on this analysis, plot and advantageously output the test results of the equipment.

[0028] The testing system according to the invention can be used in a similar manner to the apparatus according to the invention on oil-insulated high-voltage equipment, such as power transformers, current transformers, voltage transformers, and gas-insulated switchgear. The gas to be analyzed can be a gas used to insulate the high-voltage equipment itself, or a gas released from insulating components or liquid insulating oil.

[0029] Finally, within the framework of this invention, a method for degassing a device is provided. This method includes the following steps:

[0030] • Connect the first volume to the second volume. This step can be performed, for example, by opening a valve between the first and second volumes. This step is essentially preparation for the next step.

[0031] The gas is pumped from the device into a first volume, and thus into a second volume that was connected to the first volume in the previous step. In this step, the gas is pumped from the device into a large volume consisting of the first and second volumes. The large volume facilitates degassing.

[0032] • Disconnect the connection between the first volume and the second volume. For example, this step can also be performed by closing the valve specified in the first step.

[0033] • The gas is pumped from the second volume into the first volume. In this step, the gas is compressed by pumping a portion of the gas extracted by the device and located in the second volume into the first volume.

[0034] The advantages of the method according to the invention substantially correspond to the advantages of the apparatus according to the invention, which have been described above and will therefore be avoided here.

[0035] Specifically, the device to be degassed is a degassed container into which the liquid to be degassed (e.g., oil) is filled (e.g., manually). However, it is also possible that a manual process is not required, for example, by automatically filling (pumping) the liquid to be degassed into the degassed container, or by introducing gas into the device or test system according to the invention and obtaining the gas to be analyzed directly from the equipment (e.g., high-pressure equipment). In the latter case, the device to be degassed corresponds almost entirely to the equipment described above.

[0036] Besides inspecting high-pressure equipment, this invention can also be used with gas measuring equipment. Therefore, this invention can be used for quality control in laboratories, for process analysis and monitoring in the following scenarios:

[0037] Petrochemical and chemical plants;

[0038] Natural gas processing plant;

[0039] • Biogas plant;

[0040] • Online natural gas analysis and determination of higher calorific value in energy production;

[0041] • Emissions measurement. Attached Figure Description

[0042] The present invention will now be described in more detail using preferred embodiments and with reference to the accompanying drawings.

[0043] Figure 1 An apparatus according to the invention is schematically depicted, which is connected to a degassing container to be degassed.

[0044] Figure 2 A test system connected to the high-voltage equipment under test is illustrated schematically. Detailed Implementation

[0045] Figure 1 The device 10 according to the invention is schematically depicted, which is connected to the degassing volume or degassing container 7.

[0046] The device includes a first valve 12, a second valve 12, a third valve 11, a pump 3, a first container or volume 1, a second container or volume 2, and a sensor 4 disposed in the first volume 1. The first valve 12 is disposed between the first volume 1 and the second volume 2. In other words, when the first valve 12 is open, the first volume 1 and the second volume 2 effectively form a large volume. The pump 3 is arranged such that the pump is connected at the suction end to the degassing container 7 via the second valve 13 and / or to the second volume 2 via the third valve 11.

[0047] For example, the volume content of the degassing volume (the volume of the degassing container 7) can be about 300 ml (about 700 ml) (depending on the degassing container 7 used), the volume content of the second volume 2 (low-pressure volume or expansion volume) can be about 10 ml, and the volume content of the first volume 1 (high-pressure volume or analytical volume) can be about 500 μl.

[0048] The degassing container 7 contains insulating oil 5. The analysis of gases dissolved in the insulating oil 5 is carried out with the assistance of sensor 4, because these gases released from the insulating oil are pumped into the first volume 1 and analyzed there with the assistance of sensor 4.

[0049] Therefore, in the degassing step, the first valve 12 and the third valve 11 are opened and the second valve 13 is closed. Pump 3 then pumps gas from the degassing container 7 into the first volume 1, and there through the first valve 12 into the second volume 2. Then, the first valve 12 and the third valve 11 are closed and the second valve 13 is opened. Pump 3 then pumps gas from the second volume 2 into the first volume 1, resulting in an increase in the pressure in the first volume 1 and thus the gas concentration in the first volume 1. When the first volume 1 reaches its maximum possible pressure, the gas in the first volume 1 is analyzed with the assistance of sensor 4.

[0050] The degassing process, as well as the activation of valves 11-13 and pump 3, are preferably performed automatically or via a suitable control unit (see [link]). Figure 2 The control unit 19 shown is operated in a computer-aided manner.

[0051] Figure 2 A test system 30 and a high-voltage device 40 according to the invention are schematically depicted. The test system 30 is designed to inspect the insulation 41 of the high-voltage device 40. The test system 30 includes a degassing device 10 according to the invention, which is as described above and Figure 1 The diagram is schematically depicted. Furthermore, the test system 30 includes an evaluation unit 20 to plot inspection results based on degassing and compression, and the device 10 analyzes the gas using its control unit 19. The device 10 analyzes the gas from the insulating element 41 using the mass of the insulating element 41, thereby measuring the operational readiness of the high-voltage equipment 40 itself, which can be determined by analyzing the gas.

Claims

1. A device for degassing equipment (7), It has a pump (3), which is connected to a first volume (1) at the discharge end. in, The first volume (1) is connected to the second volume (2) via a first valve (12). The pump (3) is connected to the second volume (2) at its suction end via a second valve (13), and can be connected to the device (7) to be degassed. It has a control unit (19) for activating the pump (3) and the first valve (12) and the second valve (13). The device (10) is designed to open the first valve (12) and close the second valve (13) by means of the control unit (19), and then pump gas from the device to be degassed (7) into the first volume (1) and into the second volume (2) connected to the first volume (1) by means of the pump (3).

2. The apparatus according to claim 1, Its features The second volume (2) is at least five times larger than the first volume (1).

3. The apparatus according to claim 1, Its features The device (10) is designed to close the first valve (12) and open the second valve (13) via the control unit (19), and then pump gas from the second volume (2) into the first volume (1) via the pump (3).

4. The apparatus according to claim 1, Its features The device (10) includes a third valve (11), and the pump (3) is connected at the suction end to the device (7) to be degassed via the third valve (11).

5. The apparatus according to claim 4, Its features The device (10) is designed to open the first valve (12) and the third valve (11) and close the second valve (13) by means of the control unit (19), and then pump gas from the device to be degassed (7) into the first volume (1) and into the second volume (2) connected to the first volume (1) by means of the pump (3).

6. The apparatus according to claim 4, Its features The device (10) is designed to close the first valve (12) and the third valve (11) and open the second valve (13) by means of the control unit (19), and then pump gas from the second volume (2) into the first volume (1) by means of the pump (3).

7. The apparatus according to claim 1, Its features The device (10) includes a sensor (4) arranged in the first volume (1), and The sensor (4) is designed to analyze the gas in the first volume (1).

8. The apparatus according to claim 1, Its features The device (10) is designed to degas high-pressure equipment (40).

9. A test system for testing equipment (7), in, The testing system (30) includes an evaluation unit (20) and a device (10) according to any one of claims 1 to 8, for analyzing gases in or from the device (7). The evaluation unit (20) is designed to analyze the gas pumped into the first volume (1) and plot the test results of the device (7) based on the analysis.

10. A method for degassing equipment (7), comprising the following steps: Connect the first volume (1) to the second volume (2) provided separately from the first volume (1). Gas is pumped from device (7) into the first volume (1) and from the first volume into the second volume (2) connected to the first volume (1). Disconnect the second volume (2) from the first volume (1), and Gas is pumped from the second volume (2) into the first volume (1). in, The method is performed using the apparatus (10) according to any one of claims 1 to 8.

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