JP4984252B2 - Non-condensable gas sensor using thermoelectric element - Google Patents

Description

  The present invention relates to a non-condensable gas sensor using a thermoelectric element.

  A means for sampling a gas in a tube or a container and analyzing the sampled sample by gas chromatography has been conventionally used in various fields (see Patent Document 1).

  FIG. 1 is a diagram illustrating an example of a conventional gas measuring apparatus. 1b is a condenser, 1a, 2a, 3a are gas chromatography. Reference numerals 1c, 2c and 3c are pipes for sampling a gas sample.

  In this non-condensable gas measuring device, the condenser 1b functions as a gas storage container in which a gas sample is placed, in which a sample and water vapor are contained. If the concentration of the non-condensable gas (air) in the water vapor is small, it will be difficult to detect the non-condensable gas by the non-condensable gas sensor, and a high-precision and large-scale device will be required. Sufficient time and a large number of samplings are required.

In the condenser, the vapor state changes near the condensation surface and is not completely mixed, so it is difficult to obtain the same value at each sampling point. Even if the amount of non-condensable gas is obtained from the sampling value at one point, It is difficult to estimate the influence on the condensation of the material, and there is a problem that a lot of sampling is required.
JP 2002-39925 A

  The object of the present invention is to solve the problems of the conventional apparatus as described above, and it is miniaturized so that it can directly measure the influence on condensation and know the accurate phase change state in real time. An object is to realize a non-condensable gas sensor.

In order to solve the above problems, the present invention is a non-condensable gas sensor that measures the concentration of a small amount of non-condensable gas present in the vapor in a predetermined container, and is provided with a thermoelectric element that contacts the vapor.
The thermoelectric element is repeatedly heated and cooled by applying a current that continuously changes at a constant period to cause the vapor to evaporate and condense, and the surface of the thermoelectric element in contact with the vapor A temperature change is measured, and a concentration of non-condensable gas in the vapor is measured by a difference between a phase of the periodic change of the applied current and a phase of the periodic change of the surface temperature of the thermoelectric element. A non-condensable gas sensor using a thermoelectric element is provided.

  Conventionally, measurement of a small amount of non-condensable gas has required a lot of time and a large-scale apparatus. However, according to the present invention, the phase change state can be directly and immediately determined by using the cooling and heating characteristics of the thermoelectric element. At the same time, it is possible to reduce the size and the price.

  Embodiments of a non-condensable gas sensor using a thermoelectric element according to the present invention will be described below with reference to the drawings based on examples.

  FIG. 2 is a diagram for explaining an example of a non-condensable gas sensor using a thermoelectric element according to the present invention. The non-condensable gas sensor 1 is formed in a cylindrical shape as a whole, and has a thermoelectric element 3 at the tip head 2 thereof. The thermoelectric element 3 is configured to be supplied with a current continuously changing from a power source 4 at a constant cycle, and to be heated and cooled periodically.

  Here, the current continuously changing at a constant period is “intermittent continuous current” or “alternating current”.

  In the condensed gas sensor 1, a heater 5 and a cooling water channel 10 are provided. The heater 5 and the cooling water channel 10 constitute a temperature control unit, and this temperature control unit is provided as a constant temperature means for the thermoelectric element 3 to keep a constant temperature while suppressing a temperature rise due to Joule heat.

  The non-condensable gas sensor 1 having such a configuration is mounted so as to penetrate the wall 7 of the sample gas container (condenser) 6 and to expose the thermoelectric element 3 of the tip head 2 in the non-condensable gas sensor 1. The In the sample gas container 6, there are sample gas and water vapor. The water vapor touches the surface of the thermoelectric element 3 (the surface of the thermoelectric element 3 on the sample gas container 6 side). Water vapor consists of air and water, which are non-condensable gases.

  Evaporation occurs when the surface temperature of the thermoelectric element 3 is higher than the saturation temperature of water vapor, and vapor condensation occurs when the temperature is lower. Therefore, by repeating heating and cooling with the thermoelectric element 3 and changing the surface temperature, the condensed water is evaporated and the water component of the water vapor is condensed.

  A temperature measuring element 8 (thermocouple, thermistor, resistance thermometer, etc.) for the first temperature measurement for measuring the surface temperature is attached to the surface of such a thermoelectric element 3. A second temperature measuring element 9 (thermocouple, thermistor, resistance thermometer, etc.) for temperature measurement is also provided on the back surface of the thermoelectric element 3 (the surface of the thermoelectric element 3 on the heater 5 side). .

  The back surface side of the thermoelectric element 3 is controlled by cooling water flowing through the heater 5 and the cooling water passage 10 so as to have a constant temperature. The heater 5 makes the thermoelectric element 3 have a constant temperature on the back surface side, and the second temperature measuring element 9 measures and monitors the back surface side of the thermoelectric element 3.

  When the non-condensable gas sensor 1 having the above configuration is used, a current is repeatedly applied to the thermoelectric element 3 by a power source 4 at a constant period. Then, the thermoelectric element 3 is heated and cooled, and water adhering to the surface of the thermoelectric element 3 evaporates and condenses, and the surface temperature of the thermoelectric element 3 changes with such a phase change.

  In this way, the current periodically applied to the thermoelectric element 3 is measured by an ammeter (not shown), and the temperature (surface temperature) at the surface of the thermoelectric element 3 that changes in response to the change of the current is measured. The surface temperature of the thermoelectric element 3 responds to a change in current and changes in the same cycle (synchronization) as the change in current. However, a time delay occurs from the periodic change in current, that is, the phase shifts, and the thermoelectric element 3 changes. The surface temperature of the element 3 changes.

  That is, when a phase change occurs between water vapor and water, a change in the amount of heat occurs on the surface of the thermoelectric element 3, so that the temperature of the surface of the thermoelectric element 3 changes. The current is increased until a temperature slightly deviated from the saturation temperature, and the current is decreased after a certain time.

  Thus, by applying a periodically changing current (intermittent continuously changing current or alternating current), the temperature of the surface of the thermoelectric element 3 is periodically changed by the phase change between water vapor and water. Appears as a change. That is, a periodic change in the surface temperature of the thermoelectric element 3 with respect to a periodic change in current causes a time delay, that is, a phase shift.

  By the way, when the water component of the water vapor in the sample gas container 6 is large (when the concentration of the non-condensable gas is low), the amount of water adhering to the surface of the thermoelectric element 3 is large. It takes a lot of time to evaporate.

  That is, when the non-condensable gas concentration is low (when the water component is large), the time delay of the periodic change of the surface temperature of the thermoelectric element 3 with respect to the periodic change of the current, that is, the phase shift width becomes large. .

  The present invention measures the current applied to the thermoelectric element 3 at a constant period, measures the surface temperature of the thermoelectric element 3 in the sample gas container 6, and calculates the phase difference between the periodic changes in the current and the surface temperature. By detecting, the magnitude of the ratio of air (noncondensable gas concentration) to the amount of water vapor in the sample gas container 6 can be grasped.

  If a relationship curve is created in advance for the correspondence between the non-condensable gas concentration in the sample gas container 6 and the phase difference of the temperature change of the temperature measuring element 8, the non-condensable gas concentration is measured by detecting the phase difference. can do.

  That is, several non-condensable gas concentrations in the sample gas container 6 are changed in advance, and the phase difference between the change in current applied to the thermoelectric element 3 and the temperature change in the temperature measuring element 8 is detected for each of them. If a curve is prepared, the concentration of non-condensable gas existing in the vapor can be easily and accurately measured by using the relationship curve.

  Since the non-condensable gas sensor 1 using the thermoelectric element 3 according to the present invention is configured as described above, a direct phase can be obtained by measuring the current applied to the thermoelectric element 3 and the surface temperature of the thermoelectric element 3. Changes or non-condensable gas concentration can be measured, the non-condensable gas concentration can be measured in real time as compared with the conventional device, and the device can be downsized.

  In other words, according to the present invention, in the phase change at the surface of the thermoelectric element 3, the thermal resistance (from another viewpoint, heat transfer) due to the influence of the non-condensable gas can be measured as a current change and a temperature change. It is possible to detect and measure the effect on the phase change caused by the non-condensable gas contained in.

  As described above, the best mode of the condensed gas sensor using the thermoelectric element according to the present invention has been described based on the embodiments. However, the present invention is not limited to such embodiments, and the technology described in the claims. It goes without saying that there are various embodiments within the scope of the subject matter.

  Since the non-condensable gas sensor using the thermoelectric element according to the present invention is configured as described above, the present invention relates to a cooling and heating device and a temperature measuring device for the surface thereof, and not only non-condensable gas measurement but also saturated vapor temperature measurement. It can be used as a phase change phenomenon observation device.

It is a figure explaining the conventional gas measuring device. It is a figure explaining the Example of the condensed gas sensor using the thermoelectric element which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Non-condensable gas sensor 2 Tip head 3 Thermoelectric element 4 Power supply 5 Heater 6 Sample gas container (condenser)
7 Wall of sample gas container 8 Temperature measuring element for first temperature measurement (thermocouple, thermistor, resistance temperature detector, etc.)
9 Temperature measuring element for second temperature measurement (thermocouple, thermistor, resistance temperature detector, etc.)
10 Cooling channel

Claims (1)

A non-condensable gas sensor that measures the concentration of a small amount of non-condensable gas present in the vapor in a predetermined container,
A thermoelectric element in contact with the steam, a temperature measuring element for measuring the temperature of the surface of the thermoelectric element in contact with the steam, and a thermostatic means for maintaining the back surface at a constant temperature on the back surface side of the thermoelectric element;
To the thermoelectric element, repeating the heating and cooling of the steam by applying a continuously varying current at a constant period, along with causing the evaporation and condensation of the steam, the contact surface between the vapor in the thermoelectric element Measure the temperature change,
Detecting the phase difference between the phase of the periodic change of the applied current and the phase of the periodic change of the surface temperature of the thermoelectric element;
From the phase difference, the concentration of the non-condensable gas in the steam is measured by using a relationship curve between the non-condensable gas concentration and the phase difference created in advance by changing several non-condensable gas concentrations in the container. A non-condensable gas sensor using a thermoelectric element.

Images