JPH05501764A - Apparatus and method for determining the dew point of components of a gas mixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Apparatus and method for determining the dew points of components of a gas mixture The present invention provides a method for determining the dew points of components of a gas mixture. The present invention relates to an apparatus and method for determining dew point.

Accurately determining the vapor content of a gas stream is essential to avoid corrosion and Preventing air contamination or testing the humidity of gas streams to ensure optimal process performance It is of vital importance in many areas of process technology.

It is widely used as an instrument, especially for determining the water vapor content of the atmosphere. Point hygrometers are known. A dew point hygrometer measures air as it cools until water vapor condenses. It will be done.

The dew point temperature detected in this way corresponds to the saturation temperature of the air; Not only can the perceived temperature of the airflow be detected from the temperature, but the relative humidity can also be detected. can be detected.

For this reason, for example, see "Basics on Humidity Measurement and Adjustment" by Winfried Luc. Research 1964 Munich, Vienna, Published by R. Oldenburg, p. 74 There are three main methods or devices known, as described in pages 8 and 4. It is.

a) Dew point mirror that fogs up below the dew point when cooled b) Electrical resistance or is a cooled electronic device with varying capacity. C) Antechamber. When the temperature of the gas to be measured in this chamber drops below the dew point, the subchamber Fog is observed inside.

In this subchamber hygrometer, the gas to be measured is compressed without falling below its dew point, and then allowed to relax. It will be done. This relaxation causes the humid air to be cooled to a considerable degree almost uniformly. Ru.

When the temperature of the measured gas drops below the dew point due to relaxation, the illuminated “secondary” The formation of fog is observed in the chamber. When the gas relaxes to atmospheric pressure, for example, it undergoes compression and relaxation. Repeated slowdowns create overpressure due to fog formation.

The dew point temperature can be calculated from the temperature of the humid gas and the compression ratio.

Mira complete dew point measuring instruments equipped with a dew point mirror allow the measurement gas to reach the limit of fog formation. The formation of fog can be confirmed by repeatedly changing the cooling temperature. Adjust the cooling accordingly. Photocell device cools dew point mirror via regulation amplifier and/or controlling the heating so that the fog deposition limit is maintained automatically, i.e. regularly. A device that does this is known. However, in terms of adjustment technology, automatic dew point adjustment comes with some problems. This is because the fog generation rate strongly depends on the dew point temperature at each time. This is because it exists. Various modifications of the MIRA set dew point measuring device can be found in most of the above specialized books. Crab German Patent Publication No. 1957322, German Patent Publication No. 1299437 German Patent Publication No. 2640663, German Patent Publication No. 29454 45 and from US Pat. No. 3,385,098.

To eliminate problems associated with photoreflection scanning in Mira complete dew point meters, the Electronic devices may also be used. Conductor tracks arranged in a pattern on an insulating substrate By doing this, you can obtain a very small section resistance and easily control a large amount of resistance. can be transmitted. Instead of measuring the resistance of the electronic device being cooled, the capacitance Volume changes may also be used. This capacitance change is caused by fogging of the sensor. Occurs when the air constant changes. This type of capacitive dew point detector is known, for example, from a German patent. It is known from Publication No. 3231534.

A significant disadvantage of devices with a dew point mirror and antechamber is the cost of the device and the cost of adjustment technology. The strike is high. This increases the cost of this type of device. against this A disadvantage of electronic devices that are cooled by cooling is relatively poor measurement accuracy. This drawback is , due to the hygroscopicity of all the usual materials used for conductor track carriers. The surface resistance increases long before the liquid becomes saturated and therefore long before the liquid precipitates. decrease. Conductor track carriers with relatively low moisture absorption, e.g. paraffin or Using wax or conventional conductor track carriers with such materials Due to its low melting temperature and low mechanical strength, I can't get a satisfactory result.

Another disadvantage of cooled electronic devices is that due to the poor thermal conductivity properties of the above-mentioned materials, this material It is very difficult to determine the exact surface temperature of the material, i.e. of the condensing surface. That's true. As a result, the dew point temperature cannot be determined accurately either.

The above-mentioned drawbacks of the above-mentioned known measuring instruments or methods are discussed in the specialized magazine "Compressed Air Technology" Written by E. Blum, published in No. 11-12, 1989, pages 33 and 34. The article “Are compressed air dryers working?” was also pointed out.

Finally, from German Patent Publication No. 3713864, the premise of claim 1 of the present application is Devices and methods for determining the dew points of components of gas mixtures are known which correspond to the concept. ing. This known device has a temperature sensor. This humidity senna has dew point mira - and electronic equipment to be cooled.

Furthermore, a condensate collector is provided which is cooled or heated by the Peltier element. ing. A temperature sensor is also provided in thermal contact with the condensate collector. child A temperature sensor measures the temperature of the condensate collector or condensing surface. humidity sensor The sensor, condensate collector and temperature sensor are integrated into one component. Therefore In this known device, a liquid precipitate is deposited on both the dew point mirror and the electronic device to be cooled. This device also has the drawbacks of the measurement principle mentioned above. ing.

The object of the invention is to provide an apparatus and a method for determining the dew point of a component of a gas mixture. Therefore, the purpose of the present invention is to make it possible to obtain the measurement accuracy of the MIRA complete dew point measuring device at a low cost.

This problem is solved by the configuration according to claim 1 or claim 12.

The main feature of the arrangement according to the invention is that the temperature-controlled condensate collector is combined with a humidity sensor. These points are located spatially apart. Once the dew point temperature is reached, the condensate collection is cooled. Liquid is deposited in the aggregate. This liquid is vaporized again during heating of the condensate collector. and higher vapor content around the condensate collector where the humidity sensor is located. Become. This content is displayed by a humidity sensor.

The main advantage of the invention is that it is no longer necessary to measure condensate temperature and evolution at the same time. That's a good thing. Rather, according to the invention, during the heating of the condensate collector a significant Due to humidity changes, reaching the desired dew point temperature during the preceding cooling stage is indirectly It is estimated that Therefore, by varying the achieved temperature difference, the cooling end can therefore be By changing the end temperature, a desired dew point temperature can be detected repeatedly.

For this purpose, the starting temperature at the beginning of the cooling phase can also be varied.

At least a humidity sensor and condensate are installed so that the vapor content can be changed significantly. It is advantageous to arrange the condensate collector in one measuring chamber. Further writing this change In order to increase the temperature, the flow of the measuring gas is interrupted at least during the heating phase. This is it At the same time, the amount of measurement gas required to determine the dew point is also reduced.

Another configuration to increase the importance of annunciation is to place the humidity sensor spatially in the condensate collector. placed immediately above so that the condensate evaporated during the heating stage energizes the humidity sensor. This was done so that

A mirror or an electronic device can be used as a humidity sensor. steam content Other components whose electrical resistance changes significantly due to an increase in Ru.

Peripheral equipment required to detect significant changes in humidity Can be made to correspond to the sensor.

A mirror is used as a humidity sensor, and the mirror is activated when a significant change in humidity occurs. Unlike the known Mira set dew point measuring instrument, it requires less troublesome adjustment. This greatly simplifies the implementation of the process or method. In known dew point measuring instruments, condensate The problem with adjustment technology is to determine the temperature as accurately as possible at the time when it first precipitates. There was a problem.

In other words, the exact point at which fog appears and the temperature at this point are measured and linked to each other. I had to let it go and detect it. On the other hand, in the present invention, the humidity The measurement or measurement of condensate formation and the measurement of temperature are, as it were, separated. single determine whether significant humidity changes have occurred over relatively large temperature and time intervals. All you have to do is set it. The measurement of dew point temperature is carried out by an iterative method.

Even when electronic devices are used as temperature sensors, the hygroscopicity of the conductor track carrier is a problem. do not become. This is because only changes in moisture content need to be qualitatively detected. Ru.

The hygroscopicity of the material used for the condensate collector also plays only a secondary role. . This is because the amount of liquid that exists before reaching the saturation temperature due to hygroscopicity is small, and The resulting indicator pulse from this is the condensate collection indicator pulse after the dew point temperature has fallen below. or the condensate collection indication pulse when the dew point temperature is reached. Because there is.

Another advantage of the invention is that there is no need to heat or cool the temperature sensor itself, and the humidity sensor The point is that only a small amount of condensate settles in the sensor. This causes contamination and corrosion. The main causes of this will be reduced.

When using an electronic device as a temperature sensor, the humidity sensor is connected with alternating current during measurement. Corrosion can also be avoided by ensuring that no electrical changes occur. .

A further advantage of the invention is that temperature measurement on the surface of the condensate collector is relatively simple. That's true. This is because the surface of the condensate collector is made of gold, which has excellent thermal conductivity and does not corrode. This is because the genus can be used.

A further advantage of the invention is that the liquid is frequently condensed and then evaporated again. Contamination that occurs in the condensate collection body due to the It should not affect anything.

The use of Berthier elements to cool and heat the condensate collector makes the configuration particularly Can be made simple and compact.

It is also possible to configure one side of a heat exchanger, especially an evaporative heat exchanger, as a condensate collector in a compact manner. You can get a simple configuration. When cooling the condensate collector using an evaporative heat exchanger The heating of the condensate collector is carried out, for example, by resistive heating or by microwave radiation. I can.

When it is necessary to continuously determine the dew points of multiple components in one mixed gas It is advantageous to use a sintered metal heat exchanger as the condensate collector. this place In this case, it is first necessary to separate the component with the highest dew point from the measurement gas. Do this After that, the dew point of the component with the next highest dew point can be determined. That is, condensate collection The aggregate also acts as a cooling dryer.

In this case, the humidity sensor and/or the condensate collector attached to it are each duplicated. It is advantageous to have several. For example, multiple humidity sensors and multiple humidity sensors attached to them. operating the condensate collector and the condensate collector simultaneously during cooling at different starting temperatures and/or temperature differences. This minimizes the time required to determine the desired dew point temperature.

Next, embodiments of the present invention will be described using the accompanying drawings.

FIG. 1 shows a schematic diagram of an advantageous embodiment of the device according to the invention.

The dew point measuring device illustrated in FIG. It has a collector 1. Of course, other configurations of stiffeners with materials with excellent thermal conductivity may also be used. It is also possible to use shrinkage collectors. One side of the condensate collector 1 is a Peltier element. connected to a device for regulating the temperature of the condensate collector 1, configured as 2; Excellent thermal conductivity. Precipitating condensate on the other side, i.e. on the active surface 3 Can be done. A temperature sensor 4 is provided on the active surface 3 of the condensate collector 1 . temperature Monitoring the temperature of the condensate collector 1 and more precisely the temperature of the active surface 3 using a sensor 4 The dew point temperature can be measured.

The Peltier element 2 has electrical connections 6 and 7. Above the condensate collector 1 , a humidity sensor 8 configured as an electronic device is provided. Humidity sensor 8 is It has a rim 10. On the insulator 10 are conductors interlocking with each other in the form of teeth. Two poles 11 and 12 of an electronic device configured as tracks are provided.

Humidity sensor 8 and condensate collector 1 are arranged in measurement chamber 14 . Measurement chamber 14 has a supply pipe 16 and a discharge pipe 17. Discharge pipe 17 can be shut off by valve 18 It is Noh. The supply pipe 16 includes a transport device for transporting the measurement gas into the measurement chamber 14. 20 are provided. Between the transfer device 20 and the measurement chamber 14, or between the measurement chamber 14 and the valve Between 18 and 18 are optional devices such as filters, heat exchangers, volumetric flow monitors (not shown). can be provided.

The adjustment and operating mode in the embodiment described above is extremely simple. At the start of the measuring instrument, That is, at the beginning of the measurement cycle, the active surface 3 of the condensate collector 1 is at the starting temperature level T. It is at 0. This arbitrary starting temperature level T0 is normally at ambient temperature or into the measuring chamber 14. is the intrusion temperature of the measured gas. Cooling the condensate collector 1 using the Peltier element 2 By doing so, the condensate collector or its active surface 3 is brought to a temperature T1 by a temperature difference ΔT. Descend. The dew point measuring device according to the invention can be used, for example, in compressed air supply systems. temperature T1 is the temperature defined as an alarm threshold or monitored Desired dew point temperature of the dryer.

When the temperature T is reached, the electrodes of the electrical connections 6 and 7 of the Berthier element 2 are replaced. The heating phase begins.

Time of cooling stage or time of heating stage and stop time at each temperature level are selected depending on the particular application. The cooling stage is sufficient to precipitate the condensate. The heating step should ensure that the condensate formed must ensure complete evaporation. Humidity sensor 8 until the final heating temperature is reached, which can be selected arbitrarily and corresponds to the area of use. If the signal appears, for example, as a strong resistance drop, it indicates the cooling reached during the preceding cooling phase. The final cooling temperature is a desired dew point temperature or a temperature below the dew point temperature.

If the humidity sensor 8 does not show an indication pulse, i.e. the resistance remains constant, for example. If so, the dew point temperature has not been reached.

In this way it is ensured that the series of measurements is always taken towards the actual dew point temperature. It is proved.

The exact parameters of the adjustment method, e.g. temperature step, cooling rate, heating rate, are selected depending on the particular application.

If a continuous display is required, e.g. the last indicated temperature will be Determine the current dew point temperature as corresponding to the actual temperature.

The permissible length of the measuring interval, i.e. the appropriate time length, is also determined in each case by the application. It can be controlled by the output of the built-in cooling device. moreover It is also possible to have multiple cooling surfaces on one sensor, or multiple cooling surfaces in one measuring chamber. It is also possible to arrange several devices, and in this way continuous measurement becomes possible.

In order to automate the adjustment of the dew point measuring instrument according to the invention, i.e. the determination of the dew point temperature, the humidity sensor The display of the sensor 8, the signal from the temperature sensor 4, and the control of the Berthier element 2 are shown in the diagram. You will be guided to a control device that does not exist.

After optimizing the time of the cooling stage, the Mira set dew point can be measured using the dew point measuring device shown in Figure 1. The measurement accuracy of the device (Spiegel-Taupunk+-Me8gerite) was obtained. In other words, a measurement accuracy of ±0.2°C is obtained.

In the specific configuration of the dew point measuring device shown in FIG. A plate made of resin (15 x 15 mm) is used as the insulator 10, and the width is 300 μm, with a thickness of 35 μm, and 150 μm as poles 11 and 12. Copper conductor tracks are used which are arranged with mutual spacing of μm. As a condensate collector An aluminum plate with a size of 3 x 15 x 15 mm is used. humidity sensor The distance between the sensor 8 and the condensate collector 1 is 2 mm. Berthier element 2 has a maximum of 3V A current of 1.8A flows at a voltage of . The volume of the measurement chamber 14 is 20CI+! It is. dew 8 when the point temperature is 1.5 to 2.5°C and the average perceived temperature of the compressed air is 22°C. The measurement was carried out with bar compressed air, and 12 measurement cycles were performed per hour.

The volumetric flow through the measuring chamber 14 is 150NLtr,/b (standard liters per hour). ). At this time, while heating the condensate collector 1, the following resistance Changes were made.

Initial conditions >50X10’Ohm O02K Dew point temperature or higher >50X10’OhmO, 2K Dew point temperature or lower <0 ．． If the 5X10’Ohm measurement accuracy is 0.2 above, then 1:100. An important resistance ratio can be obtained. It is also important if the resistance ratio is significantly smaller than this. Therefore, measurement accuracy can be improved.

In addition to the conductor track sensors shown, optical sensors, ultrasonic sensors, capacitive or resistive Other components suitable for measurement may also be used.

The measuring chamber can basically be designed for any pressure level.

The advantageous embodiment described above is very robust and is compatible with conventional optical and capacitive devices. It is more resistant to contamination than other machines, requires no calibration, and can be made from standard, inexpensive industrial parts. As a result, 1/1 of the Mira complete dew point meter can be installed. It can be realized at a cost on the order of 10.

The present invention is not limited to the above-mentioned embodiments, but allows for numerous modifications. For example, multiple belts can be used to obtain lower cooling temperatures or higher recooling. It is possible to cascade elements or use other cooling systems. be.

Still other variations are possible, for example when there are several types of condensable vapors. It is also possible to subject senna to temperature treatment in order to measure its vapors, or by placing multiple sensors around the cooling surface of the It is also conceivable to install multiple cooling surfaces around the server.

/71/I abstract 1. Name of the invention Apparatus and method for determining the dew points of components of gas mixtures 2, summary 2.1 Outdoor hygrometers are very accurate, such as the Bamira set of outdoor hygrometers. is very expensive or requires only one electronic device, e.g. to measure electrical resistance. Although they are cheap, their accuracy is either relatively poor. According to the present invention This device is inexpensive and has measurement accuracy comparable to that of an open-air hygrometer. ing.

2.2 Place the humidity sensor (8) spatially separated from the condensate collector (1), but next to it. Place them next to each other. The condensate collector (]) is heated to a predetermined temperature by means of a cooling/heating device (2). Cool by the difference. During this cooling process, when the dew point temperature is reached, the condensate collector ( 1) This condensate is evaporated again in the 9th heating stage where a liquid is precipitated on top; The increase in steam content during soil removal is controlled by a humidity sensor placed above the condensate collector (1). It is detected by the sensor (8). by changing the temperature difference during the cooling stage. The desired dew point temperature is detected by an iterative method.

2.3 Process technology in general, measurement technology in general, monitoring of compressed air equipment 3. Drawings Figure 1 International v4 inspection report international search report

Claims (16)

[Claims] 1. Apparatus for determining the dew point of a component of a gas mixture, the apparatus comprising: - a humidity sensor (8); - a condensate collector (1); - regulating the temperature of the condensate collector (1), which is thermally connected to the condensate collector (1); a device (2) for - a temperature sensor (4) in thermal contact with the condensate collector (1); In an apparatus for determining the dew point of a component of a gas mixture, having A humidity sensor (8) measures the humidity of the gas and spatially removes it from the condensate collector (1). characterized in that it is located apart but adjacent to the condensate collector (1) Device. 2. A humidity sensor (8) is spatially arranged directly above the condensate collector (1). 2. Device according to claim 1, characterized in that: 3. At least a humidity sensor (8) and a condensate collector (1) are located in the measuring chamber (14). Device according to claim 1 or 2, characterized in that it is arranged. 4. The measuring chamber (14) has a supply pipe (16) and a discharge pipe (17); characterized in that at least the discharge pipe (17) can be shut off by a valve (18) , the apparatus according to claim 3. 5. Mirror with humidity sensor (8) indicating high vapor content due to cloudy weather The device according to any one of claims 1 to 3, characterized in that it has a Place. 6. The humidity sensor (8) has a base body (10) made of an electrical insulator, the base body (10 ), at least two conductor tracks (11,1 2) according to any one of claims 1 to 4, characterized in that The device described. 7. A device (2) for adjusting the temperature of the condensate collector (1) is provided in the condensate collector (1). 1) has at least one Berthier element (2) for cooling and heating the 7. Device according to any one of claims 1 to 6, characterized in that: 8. A device (2) for regulating the temperature of the condensate collector (1) is provided with a heat exchanger, in particular a evaporator. characterized in that it has an exothermic heat exchanger, one side of which forms a condensate collector (1); 7. A device according to any one of claims 1 to 6. 9. Device according to claim 1, characterized in that the heat exchanger is a sintered metal heat exchanger. Place. 10. Claims 1 to 9, characterized in that a plurality of humidity sensors are provided. The device according to any one of the above. 11. From claim 1, characterized in that a plurality of condensate collectors are provided. 10. The device according to any one of items 1 to 10. 12. A method for determining the dew point of a component of a gas mixture, in particular any one of the above claims A method using the apparatus described in , comprising the following steps, a) A condensate collector placed in the gas mixture at a temperature difference ΔT from the starting temperature To. b) heating the condensate collector; c) Humidity changes in the gas using a humidity sensor located remote from the condensate collector. d) the humidity changes during heating of the condensate collector are at least The value of the starting temperature To and/or the temperature difference ΔT is changed until the temperature difference ΔT is detected once. a step of repeating the above steps; e) termination such that no changes in humidity occur during the heating phase following the cooling phase; determining the temperature during the cooling phase; A method characterized by comprising: 13. A closed measuring volume is present at least during the heating phase or during the humidity measurement. 13. The method according to claim 12, characterized in that: 14. heating the condensate collector during the heating stage to a temperature above the starting temperature To; 14. A method according to claim 12 or 13, characterized in that: 15. The individual steps are identical with different starting values for the starting temperature To and the temperature difference ΔT. 15. According to any one of claims 12 to 14, characterized in that the method is carried out at times. Method. 16. The change in humidity during the heating stage is controlled by the change in resistance of the electronic device (11, 12). the electronic device (11, 12) is energized with an alternating current. , a method according to any one of claims 12 to 15.