JP5914152B2 - Dew point temperature measurement system - Google Patents

Description

  This invention provides a mirror-cooled dew point meter that measures the dew point temperature from dew condensation or frost generated on a mirror surface cooled using a thermoelectric cooling element in which one surface is on the low temperature side and the other surface is on the high temperature side. It relates to the dew point temperature measurement system used.

  Conventionally, as a humidity measurement method, a dew point detection method is known in which a dew point is detected by measuring the temperature when the temperature of a gas to be measured is reduced and a part of water vapor contained in the gas to be measured is condensed. ing. For example, a mirror is cooled by using a cryogen, a refrigerator, an electronic cooler, etc., the change in the intensity of reflected light on the mirror surface of the cooled mirror is detected, and the mirror surface when the intensity of the reflected light is in an equilibrium state A mirror-cooled dew point meter that detects the dew point of moisture in the gas to be measured by measuring the temperature is used.

  There are two types of mirror-cooled dew point meters depending on the type of reflected light used. One is a specularly reflected light detection method that uses specularly reflected light (see, for example, Patent Document 1), and the other is a scattered light detection method that uses scattered light (see, for example, Patent Document 2).

[Specular reflection detection method]
FIG. 22 shows a configuration of a sensor unit in a conventional mirror-cooled dew point meter that employs a regular reflection light detection method. The sensor unit 101 includes a chamber 1 into which a gas to be measured flows and a thermoelectric cooling element (Peltier element) 2 provided at the bottom of the chamber 1. A mirror 3 is attached to the cooling surface 2-1 of the thermoelectric cooling element 2, and a heat radiating member 5 is attached to the heating surface 2-2 of the thermoelectric cooling element 2 via a heat pipe 4. That is, one end 4-1 of the heat pipe 4 is attached to the heating surface 2-2 of the thermoelectric cooling element 2, and the heat radiating member 5 is attached to the other end 4-2 of the heat pipe 4 separated from the thermoelectric cooling element 2. It has been.

  Further, a heat insulating member 6 is provided at one end 4-1 of the thermoelectric cooling element 2 and the heat pipe 4 so as to cover the periphery thereof, and a temperature detecting element 7 is attached to the upper surface (mirror surface) 3-1 of the mirror 3. It has been. In addition, a light emitting element 8 that irradiates light obliquely onto the mirror surface 3-1 of the mirror 3 and a regular reflection light of the light emitted from the light emitting element 8 to the mirror surface 3-1 are provided on the upper portion of the chamber 1. A light receiving element 9 for receiving light is provided. Further, a lead wire 10 to the thermoelectric cooling element 2 is provided through the heat insulating member 6.

  In the sensor unit 101, a gas to be measured flows into the chamber 1 through a branch pipe branched from a main pipe (not shown). Thereby, the mirror surface 3-1 in the chamber 1 is exposed to the gas to be measured. If condensation does not occur on the mirror surface 3-1, almost all of the light emitted from the light emitting element 8 is regularly reflected and received by the light receiving element 9. Therefore, when there is no condensation on the mirror surface 3-1, the intensity of the reflected light received by the light receiving element 9 is high.

  When the current to the thermoelectric cooling element 2 is increased and the temperature of the cooling surface 2-1 of the thermoelectric cooling element 2 is lowered, water vapor contained in the measured gas is condensed on the mirror surface 3-1, and the water molecules Part of the light emitted from the light emitting element 8 is absorbed or irregularly reflected. Thereby, the intensity of the reflected light (regularly reflected light) received by the light receiving element 9 is reduced. By detecting the change in the specularly reflected light on the mirror surface 3-1, it is possible to know the change in the state on the mirror surface 3-1, that is, that moisture (water droplets) has adhered to the mirror surface 3-1. Further, by measuring the temperature of the mirror surface 3-1 at this time with the temperature detecting element 7, the dew point of the moisture in the gas to be measured can be known.

(Scattered light detection method)
FIG. 23 shows a configuration of a sensor unit in a conventional mirror-cooled dew point meter employing a scattered light detection method. The sensor unit 102 has substantially the same configuration as the sensor unit 101 adopting the regular reflection light detection method, but the mounting position of the light receiving element 9 is different. In the sensor unit 102, the light receiving element 9 is provided at a position for receiving scattered light, not at a position for receiving regular reflection light of light emitted from the light emitting element 8 to the mirror surface 3-1.

  In the sensor unit 102, a gas to be measured flows into the chamber 1 via a branch pipe branched from a main pipe (not shown). Thereby, the mirror surface 3-1 in the chamber 1 is exposed to the gas to be measured. If there is no condensation on the mirror surface 3-1, almost all of the light emitted from the light emitting element 8 is regularly reflected, and the amount of light received by the light receiving element 9 is extremely small. Therefore, when no condensation occurs on the mirror surface 3-1, the intensity of the reflected light received by the light receiving element 9 is small.

  When the current to the thermoelectric cooling element 2 is increased and the temperature of the cooling surface 2-1 of the thermoelectric cooling element 2 is lowered, water vapor contained in the measured gas is condensed on the mirror surface 3-1, and the water molecules Part of the light emitted from the light emitting element 8 is absorbed or irregularly reflected. Thereby, the intensity | strength of the irregularly reflected light (scattered light) received by the light receiving element 9 increases. By detecting the change in the scattered light on the mirror surface 3-1, it is possible to know the change in the state on the mirror surface 3-1, that is, that moisture (water droplets) has adhered to the mirror surface 3-1. Further, by measuring the temperature of the mirror surface 3-1 at this time with the temperature detecting element 7, the dew point of the moisture in the gas to be measured can be known.

  In addition, in the dew point meter mentioned above, although demonstrated in the example which detects the dew condensation (dew point) which arises on the mirror surface 3-1, it is also possible to detect the dew condensation (frost point) which arises on the mirror surface 3-1 by the same structure. It is. In this specification, the temperature including the frost point is defined as the dew point temperature.

  In such a mirror-cooled dew point meter, a substance (for example, an organic solvent) that condenses at a low temperature may be mixed in the gas to be measured. That is, there is a case where a substance that is usually a gas and is contained in the gas to be measured and becomes a solid at a low temperature higher than the dew point temperature may be included. If such a substance condenses and adheres to the mirror surface as it cools down to measure the dew point temperature, the condensed material adhering to the mirror surface adversely affects the reflected or scattered light, and the dew point temperature is accurately measured. Cannot be performed. For example, if condensate adheres during continuous dew point measurement and the mirror surface becomes dirty, the measurement becomes unstable, or the detection of dew condensation becomes abnormal due to contamination, and it is determined that dew condensation is excessive and the dew point temperature rises. Sometimes.

  Therefore, conventionally, in order to prevent contamination of the mirror surface, the dew point temperature measurement is periodically interrupted and the mirror surface is manually cleaned with a cotton swab or the like, as shown in Patent Document 3, The condensate contained in is removed by a removing device before being guided to the mirror surface, or as disclosed in Patent Document 4, CO2 gas is blown to blow away the condensate from the mirror surface.

JP-A-61-75235 Japanese Patent Publication No. 07-104304 JP 2002-189007 A JP 05-99846 A

  However, in the method of manually cleaning the mirror surface, the dew point temperature measurement must be periodically interrupted, and a mirror surface contamination alarm may occur frequently when checking the surface of the mirror surface. Further, the cleaning work is troublesome, and the dew point temperature measurement must be interrupted for a relatively long time for the cleaning work, and the dew point temperature cannot be continuously measured.

  Further, in the method of removing the condensed substance before the measurement gas is guided to the mirror surface, the condensed substance is specified in advance, and a removing device for removing it by a chemical reaction or the like is required. Also, it is not adapted for all condensed matter.

  In the method in which the condensed material is blown off from the mirror surface by blowing CO2 gas, a device for blowing CO2 gas is required, and measurement of the dew point temperature must be interrupted while CO2 gas is being blown.

  The present invention has been made to solve such a problem. The object of the present invention is to enable continuous measurement of the dew point temperature during the automatic cleaning control of the mirror surface, and to manually perform the mirror surface. It is an object of the present invention to provide a dew point temperature measurement system that does not require cleaning and does not require a separate apparatus for removing condensed substances.

In order to achieve such an object, the present invention irradiates light to a mirror surface exposed to a gas to be measured, a thermoelectric cooling element that cools the mirror surface, a temperature sensor that detects the temperature of the mirror surface, and the mirror surface. A light projecting means, a light receiving means for receiving reflected light of the light emitted from the light projecting means to the mirror surface, and a control for controlling the current supplied to the thermoelectric cooling element based on the amount of reflected light received by the light receiving means. And the control means controls the current supplied to the thermoelectric cooling element based on the amount of reflected light received by the light receiving means so that there is no increase or decrease in condensation or frost on the mirror surface, A means for performing dew point temperature measurement control for measuring the mirror surface temperature detected by the temperature sensor in the equilibrium state as a dew point temperature, and determining whether the mirror surface state is normal or abnormal based on the amount of reflected light received by the light receiving means. That means, would be attached to the mirror surface, usually are contained in the measurement gas in a gas, solid and becomes a higher temperature lower than the dew point temperature, automatic cleaning to remove by evaporation or sublimation of the condensed matter contaminating the mirror A dew point temperature measurement system having first and second mirror-cooled dew point meters provided with means for performing control, wherein the first mirror-cooled dew point meter is set as a dew point meter for initial measurement. The second mirror-cooled dew point meter is set as an auxiliary dew point meter at the beginning of operation, and the first mirror-cooled dew point meter always performs dew point temperature measurement control and periodically performs this dew point temperature measurement control. The process is interrupted to determine whether the mirror surface state is normal or abnormal based on the mirror surface state determination. If the mirror surface state is determined to be abnormal, the dew point temperature measurement control is stopped and the process proceeds to the automatic cleaning control. The mirror-cooled dew point meter Run the dynamic cleaning control at all times, if the first cooled mirror dew point meter is shifted to the automatic cleaning control, to stop the automatic cleaning control, characterized in that it shifts to the dew point temperature measurement and control.

  In the present invention, the first mirror-cooled dew point meter is set as a dew point meter for initial measurement, the second mirror-cooled dew point meter is set as an auxiliary dew point meter for initial operation, and the first mirror surface The cooling dew point meter always performs dew point temperature measurement control, and the second mirror-cooled dew point meter always performs automatic cleaning control. During the dew point temperature measurement control, the first mirror surface cooling type dew point meter periodically interrupts this dew point temperature measurement control to determine whether the mirror surface state is normal or abnormal, and the mirror surface state is determined to be abnormal. In this case, the dew point temperature measurement control is stopped and the process shifts to automatic cleaning control. When the first mirror-cooled dew point meter shifts to automatic cleaning control, the second mirror-cooled dew point meter stops automatic cleaning control and shifts to dew point temperature measurement control.

  For example, in the present invention, as the operation method 1, the second mirror-cooled dew point meter shifts to the dew point temperature measurement control, and then periodically interrupts the dew point temperature measurement control to normal / abnormal of the mirror surface state. When the mirror surface state is determined to be abnormal, the dew point temperature measurement control is stopped and the automatic cleaning control is resumed. After the first mirror surface cooling dew point meter shifts to the automatic cleaning control, When the second mirror-cooled dew point meter returns to the automatic cleaning control, the automatic cleaning control is stopped and the method returns to the dew point temperature measurement control.

  When this operation method 1 is adopted, if an abnormality occurs in the first mirror-cooled dew point meter, the second mirror-cooled dew point meter performs dew point temperature measurement control, and is switched to this dew point temperature measurement control. Until the abnormality occurs in the second mirror-cooled dew point meter, the first mirror-cooled dew point meter continues the automatic cleaning control.

  For example, in the present invention, as the operation method 2, the first specular cooling dew point meter periodically determines whether the specular state is normal or abnormal after shifting to automatic cleaning control, and the specular state is normal. If it is judged, the automatic cleaning control is stopped and the dew point temperature measurement control is resumed. After the second mirror cooled dew point meter shifts to the dew point temperature measurement control, the first mirror cooled dew point meter dew points. When returning to the temperature measurement control, a method of stopping the dew point temperature measurement control and returning to the automatic cleaning control is adopted.

  When this operation method 2 is adopted, if an abnormality occurs in the first mirror-cooled dew point meter, the first mirror-cooled dew point meter performs automatic cleaning control. The second mirror-cooled dew point meter performs dew point temperature measurement control until the meter returns to a normal state.

Further, in the present invention, automatic cleaning control is performed to remove the condensed substance that would have adhered to the mirror surface by evaporation or sublimation . As this automatic cleaning control, the condensed material that would have adhered to the mirror surface. In order to remove by evaporating or sublimating, a method of controlling the current supplied to the thermoelectric cooling element so as to raise the temperature of the mirror surface, and condensing substances that may have adhered to the mirror surface are removed by evaporation or sublimation In order to achieve this, it is conceivable to adopt a system in which the pressure in the chamber containing the mirror surface, thermoelectric cooling element, temperature sensor, light projecting means and light receiving means is controlled to be reduced.

  According to the present invention, the first mirror-cooled dew point meter is set as a dew point meter for initial measurement, the second mirror-cooled dew point meter is set as an auxiliary dew point meter for initial operation, The mirror-cooled dew point meter always performs dew point temperature measurement control and periodically interrupts this dew point temperature measurement control to determine whether the mirror surface state is normal or abnormal, and determines that the mirror surface state is abnormal. If this happens, stop the dew point temperature measurement control and shift to automatic cleaning control. In the second mirror-cooled dew point meter, the automatic cleaning control is always executed and the first mirror-cooled dew point meter is automatically When shifting to the cleaning control, the automatic cleaning control is stopped and the dew point temperature measurement control is shifted. Therefore, the dew point temperature is measured with one dew point meter by adopting the operation method 1 or the operation method 2. During control, the other The dew point temperature is continuously measured in the dew point meter, that is, during the automatic cleaning control in one dew point meter, the dew point temperature measurement control is performed in the other dew point meter. It is possible to make it happen.

Further, according to the present invention, in the first mirror-cooled dew point meter set as a measurement dew point meter at the beginning of operation and the second mirror-cooled dew point meter set as an auxiliary dew point meter at the beginning of operation By performing automatic cleaning control to remove condensed substances that may have adhered to the mirror surface by evaporating or sublimating, it becomes unnecessary to manually clean the mirror surface, and there is no need to provide a separate apparatus for removing the condensed material. .

It is a schematic block diagram of the mirror surface cooling type dew point meter used for the dew point temperature measurement system which concerns on this invention. It is a figure which shows the installation condition of the gate valve and suction pump for guide | inducing a to-be-measured gas in the sampling chamber of this specular cooling type dew point meter. It is a flowchart which shows the operation | movement by the side of the sub controller in this mirror surface cooling-type dew point meter. It is a figure which shows the pulsed light irradiated with respect to the mirror surface in this mirror surface cooling-type dew point meter, and the reflected pulsed light received from a mirror surface. It is a figure which shows the cooling curve (characteristics I and II) of a subcooler and a 1st thermoelectric cooling element in this mirror surface cooling-type dew point meter. It is a flowchart which shows normal / abnormal determination of the mirror surface state performed in this mirror surface cooling type dew point meter, and the shift operation to automatic cleaning. It is a flowchart which shows operation | movement at the time of confirming that the change of mirror surface temperature no longer arises in this mirror surface cooling-type dew point meter confirming normality / abnormality of a mirror surface state. It is a flowchart which shows operation | movement at the time of confirming that the change of reflected light amount no longer arises in this mirror surface cooling-type dew point meter, and judging whether the mirror surface state is normal / abnormal. It is a flowchart which shows another example of the determination operation | movement of the normal / abnormality of a mirror surface state performed regularly in this mirror surface cooling-type dew point meter, and the transfer operation | movement to automatic cleaning. FIG. 11 is a flowchart showing another example of the operation in the case of determining whether the specular state is normal or abnormal in the specular cooling type dew point meter after confirming that the change in specular temperature no longer occurs. It is a flowchart which shows the operation | movement of another example at the time of confirming that the change of reflected light quantity no longer arises in this specular cooling type dew point meter, and confirming whether the specular state is normal / abnormal. It is a functional block diagram of the principal part of this mirror surface cooling type dew point meter. It is a time chart which shows the change of the control mode in this mirror surface cooling type dew point meter. It is a functional block diagram of the principal part of one Embodiment of the dew point temperature measurement system which concerns on this invention. It is a time chart which shows the change of the control mode in the 1st specular cooling type dew point meter and the 2nd specular cooling type dew point meter at the time of operating this dew point temperature measurement system by operation method 1. It is a control flowchart of the 1st mirror surface cooling-type dew point meter and the 2nd mirror surface cooling-type dew point meter at the time of operating by the operation method 1. 5 is a control flowchart of the overall controller when operated in operation method 1; 7 is a time chart showing control mode changes in the first mirror-cooled dew point meter and the second mirror-cooled dew point meter when the dew point temperature measurement system is operated in the operation method 2. It is a control flowchart of the 1st specular cooling type dew point meter and the 2nd specular cooling type dew point meter at the time of operating by operation method 2. 10 is a control flowchart of the overall controller when operated in operation method 2; It is a figure which shows the structural example at the time of installing the 1st mirror surface cooling-type dew point meter and the 2nd mirror surface cooling-type dew point meter in series. It is a figure which shows the structure of the sensor part in the conventional mirror surface cooling-type dew point meter which employ | adopted the regular reflection light detection system. It is a figure which shows the structure of the sensor part in the conventional mirror surface cooling-type dew point meter which employ | adopted the scattered light detection system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, before describing the embodiment of the dew point temperature measurement system according to the present invention, a mirror-cooled dew point meter used in this dew point temperature measurement system will be described.

[Mirror surface dew point meter]
FIG. 1 is a schematic configuration diagram of a single unit of this mirror-cooled dew point meter. The mirror-cooled dew point meter 201 has a sensor unit 201A and a control unit 201B.

(Sensor part)
In the sensor unit 201A, reference numeral 11 denotes a mirror, and the surface 11-1 is a mirror surface. The mirror 11 is, for example, a silicon chip, and the cooling surface 2-1 of the first thermoelectric cooling element (Peltier element) 2 is attached to the back surface 11-2 side of the mirror 11. In addition, a first temperature sensor 12 made of platinum, for example, is provided between the mirror 11 and the cooling surface 2-1 of the first thermoelectric cooling element 2. The first temperature sensor 12 detects the temperature of the back surface 11-2 of the mirror 11 as the mirror surface temperature tPpv.

  The first thermoelectric cooling element 2 is attached to the inclined surface 13b of the tip end portion 13a of the sensor body 13 with the heating surface 2-2 as the bottom surface. The inclined surface 13 b has an inclination angle of 30 ° to 45 ° with respect to the central axis of the sensor body 13. Therefore, the mirror surface 11-1 of the mirror 11 attached to the cooling surface 2-1 of the first thermoelectric cooling element 2 with the first temperature sensor 12 interposed therebetween is also 30 ° to 45 ° with respect to the central axis of the sensor body 13. Is tilted at an angle of

  A rear end portion 13c connected to the front end portion 13a of the sensor body 13 has a cylindrical shape. The rear end portion 13c holds a light projecting / receiving integrated optical fiber 14 with its front end face facing the mirror surface 11-1. The light projecting axis and the light receiving axis of the light projecting / receiving integrated optical fiber 14 are parallel to the central axis of the sensor body 13. In this example, among the optical fibers 14-1 and 14-2 of the light projecting / receiving integrated optical fiber 14 protruding from the rear end portion 13c toward the mirror surface 11-1, 14-1 is disposed on the light projecting side. The optical fiber 14-2 is an optical fiber on the light receiving side.

  A cooling block 15 is joined to the rear portion of the rear end portion 13 c of the sensor body 13. A cooling plate 16 is joined to the rear part of the cooling block 15. The sensor body 13, the cooling block 15, and the cooling plate 16 are all heat conductive members, and the sensor body 13, the cooling block 15, and the cooling plate 16 constitute a heat conductor 17.

  A second thermoelectric cooling element (Peltier element) 18 is provided at the rear of the cooling plate 15. The second thermoelectric cooling element 18 is attached to the heat conductor 17 with the cooling surface 18-1 as the cooling plate 16 side. That is, the heating surface 2-2 of the first thermoelectric cooling element 2 is attached to one end of the heat conductor 17, and the cooling surface 18-1 of the second thermoelectric cooling element 18 is attached to the other end of the heat conductor 17. ing. In this specular cooling type dew point meter 201, the cooling capacity of the second thermoelectric cooling element 18 is much larger than the cooling capacity of the first thermoelectric cooling element 2, as can be seen by comparing the sizes thereof. Has been.

  A heat sink 19 is joined to the heating surface 18-2 of the second thermoelectric cooling element 18 as a radiator. The heat sink 19 has a large number of radiating fins 19a. The heat sink 19 is also a heat conductive member like the heat conductor 17. A cooling fan 20 is provided behind the heat sink 19, and a second temperature sensor 21 is provided on the cooling plate 16. The second temperature sensor 21 detects the temperature of the cooling surface 18-1 of the second thermoelectric cooling element 18 as the subcooler temperature tSpv.

  In this mirror-cooled dew point meter 201, a configuration in which the cooling plate 16, the second thermoelectric cooling element 18, the heat sink 19 and the cooling fan 20 are combined is called an auxiliary cooler (subcooler). The main configuration is the second thermoelectric cooling element 18, and the second thermoelectric cooling element 18 alone may be called an auxiliary cooler (subcooler). Here, a configuration in which the cooling plate 16, the second thermoelectric cooling element 18, the heat sink 19, and the cooling fan 20 are combined is referred to as a subcooler SC.

  Further, the mirror-cooled dew point meter 201 includes the first thermoelectric cooling element 2, the mirror 11, the first temperature sensor 12, the light-emitting side optical fiber 14-1, the light-receiving side optical fiber 14-2, and the like. The detector DT is provided through the heat insulating material 32 in the sampling chamber 31 into which the gas to be measured is drawn. Further, as shown in FIG. 2, the sampling chamber 31 is provided with a gate valve 33 and a suction pump 34 for guiding the gas to be measured to the sampling chamber 31.

  Further, the photoelectric converter 22 is provided in the sensor unit 201A. The photoelectric converter 22 converts the electrical signal from the control unit 201B into an optical signal and supplies it to the light-projecting optical fiber 14-1, or converts the optical signal from the light-receiving optical fiber 14-2 into an electrical signal. To the control unit 201B. The connection relationship between the photoelectric converter 22 and the control unit 201B will be described later. The sensor unit 201A is provided with an outside air temperature sensor 23 that detects the temperature of outside air sucked by the cooling fan 20 as tout. The outside air temperature tout detected by the outside air temperature sensor 23 is sent to the control unit 201B.

[Control part]
The control unit 201B includes a main controller 24, a sub controller 25, a power source 26, a power switch 27, a dew point measurement ON / OFF switch 28, a sub cooler control ON / OFF switch 29, and a sub cooler low temperature / high temperature / interlocking switch. A selector switch 30 is provided.

  The main controller 24 includes a CPU 24-1, a first A / D converter 24-2, a second A / D converter 24-3, a dew point temperature output unit 24-4, a RAM 24-5, ROM 24-6. The CPU 24-1 operates according to a program stored in the ROM 24-6 while obtaining various input information from the outside and accessing the RAM 24-5. The ROM 24-6 stores a dew point measurement program.

  In the main controller 24, the first A / D converter 24-2 digitally converts the optical signal (signal S4) from the light receiving side optical fiber 14-2 converted into the electrical signal from the photoelectric converter 22. It converts into a signal and gives to CPU24-1. Further, the second A / D converter 24-3 converts the mirror surface temperature tPpv (signal S2) from the first temperature sensor 12 into a digital signal and supplies the digital signal to the dew point temperature output unit 24-4 and the CPU 24-1. . The dew point temperature output unit 24-4 sends the mirror surface temperature tPpv converted into the digital signal from the first temperature sensor 12 to the host device as the dew point temperature.

  The sub-controller 25 includes a CPU 25-1, a first A / D converter 25-2, a second A / D converter 25-3, a RAM 25-4, and a ROM 25-5. The CPU 25-1 obtains various input information from the outside, and operates according to the program stored in the ROM 25-5 while accessing the RAM 25-4. The ROM 25-5 stores a subcooler control program.

  In the sub-controller 25, the first A / D converter 25-2 converts the sub-cooler temperature tSpv (signal S6) from the second temperature sensor 21 into a digital signal and supplies it to the CPU 25-1. Further, the second A / D converter 25-3 converts the outside air temperature tout (signal S8) from the outside air temperature sensor 23 into a digital signal and gives it to the CPU 25-1. Further, the mirror temperature tPpv from the first temperature sensor 12 is given to the CPU 25-1 via the second A / D converter 24-3 in the main controller 24. Further, as shown in FIG. 2, the CPU 25-1 of the sub-controller 25 receives instructions from the CPU 24-1 of the main controller 24 and controls the opening / closing of the gate valve 33 and the operation / stop of the suction pump 34.

[Sub-cooler low temperature / high temperature / linked switching setting]
In this mirror-cooled dew point meter 201, whether the subcooler SC is operated at “low temperature (for example, fixed at −5 ° C.)” or “high temperature (for example, fixed at 25 ° C.)” It is possible to selectively set the operation mode using the subcooler low temperature / high temperature / interlocking selector switch 30 as to whether to operate at “temperature + α)”.

[Dew point measurement with the operation mode set to "low temperature"]
Now, the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “low temperature”, and dew point measurement is started. In this case, it is assumed that the power switch 27 has already been turned on and the main controller 24 and the sub-controller 25 are in a state of being supplied with power.

  When dew point measurement is started, both the dew point measurement ON / OFF switch 28 and the subcooler control ON / OFF switch 29 are turned ON. The subcooler control ON / OFF switch 29 may be turned on first, and the dew point measurement ON / OFF switch 28 may be turned on after a certain period of time. It is assumed that the subcooler control ON / OFF switch 29 is turned ON simultaneously.

  When the sub-cooler control ON / OFF switch 29 is turned on, the CPU 24-1 of the main controller 24 sets the sub-cooler control ON / OFF switch 29 in accordance with the current setting state of the sub-cooler low temperature / high temperature / interlocking selector switch 30. The CPU 25-1 of the sub-controller 25 is informed that it has been turned ON.

[Operation on the sub-controller side]
When the CPU 25-1 of the sub-controller 25 receives notification from the main controller 24 that the sub-cooler control ON / OFF switch 29 has been turned ON (FIG. 3: YES in step S101), it opens the gate valve 33 (step S102). Then, the operation of the suction pump 34 is started (step S103), the inflow of the gas to be measured into the sampling chamber 31 is started, and the operation of the cooling fan 20 is started (step S104, signal S5). It should be noted that when the power switch 27 is turned on, the introduction of the gas to be measured into the sampling chamber 31 (opening of the gate valve 33 and the operation of the suction pump 34) and the operation of the cooling fan 20 may be started. Good.

  Further, the CPU 25-1 of the sub controller 25 checks the current setting state of the sub cooler low temperature / high temperature / interlocking switch selector switch 30 notified from the main controller 24 (step S105). In this case, since the setting state of the subcooler low temperature / high temperature / interlocking selector switch 30 is “low temperature”, the process proceeds to step S109 through step S108, and the set target temperature Tsp of the subcooler is set to a low temperature (for example, −5 ° C.). And

  Then, the subcooler temperature tSpv from the second temperature sensor 21 is taken in (step S114, signal S6), and the current supplied to the second thermoelectric cooling element 18 is set so that the subcooler temperature tSpv and the set target temperature Tsp match. ON / OFF control is performed (step S115, signal S7).

[Operation on the main controller side]
On the other hand, when the dew point measurement ON / OFF switch 28 is turned on, the CPU 24-1 of the main controller 24 sends a signal S3 to the photoelectric converter 22, and the mirror surface from the front end surface of the optical fiber 14-1 on the light projecting side. 11-1 is irradiated with light at a predetermined cycle (see FIG. 4A). Note that the photoelectric converter 22 may be configured to irradiate light from the distal end surface of the light-projecting optical fiber 14-1 when the power switch 27 is turned on.

  If the mirror surface 11-1 is exposed to the gas to be measured and no condensation occurs on the mirror surface 11-1, almost all of the light emitted from the tip of the optical fiber 14-1 on the light projecting side is specularly reflected. However, the amount of reflected light (scattered light) from the mirror surface 11-1 received through the optical fiber 14-2 on the light receiving side is extremely small. Therefore, when no condensation occurs on the mirror surface 11-1, the intensity of the reflected light received through the light receiving side optical fiber 14-2 is small. The reflected light received through the optical fiber 14-2 on the light receiving side is converted into an electric signal by the photoelectric converter 22 and sent to the first A / D converter 24-2 of the main controller 24, where it is a digital signal. Is converted into and taken into the CPU 24-1.

  The CPU 24-1 obtains the difference between the upper limit value and the lower limit value of the reflected light received through the light receiving side optical fiber 14-2 as the intensity of the reflected light. In this case, since the intensity of the reflected light is almost zero and has not reached a predetermined threshold value (setting value for dew condensation determination), the CPU 24-1 generates a current to the first thermoelectric cooling element 2. Increase (signal S1). Thereby, the temperature of the cooling surface 2-1 of the first thermoelectric cooling element 2 is lowered.

  When the temperature of the cooling surface 2-1 of the first thermoelectric cooling element 2 is lowered, that is, the temperature of the mirror surface 11-1, the water vapor contained in the gas to be measured is condensed on the mirror surface 11-1, and the water molecules Part of the light emitted from the tip of the optical fiber 14-1 on the light projecting side is absorbed or irregularly reflected. Thereby, the intensity | strength of the reflected light (scattered light) from the mirror surface 11-1 light-received via the optical fiber 14-2 by the light-receiving side increases.

  Here, when the intensity of the reflected light received through the optical fiber 14-2 on the light receiving side exceeds the threshold value, the CPU 24-1 reduces the current to the first thermoelectric cooling element 2. Thereby, the fall of the temperature of the cooling surface 2-1 of the 1st thermoelectric cooling element 2 is suppressed, and generation | occurrence | production of dew condensation is suppressed. By suppressing this dew condensation, the intensity of the reflected light received through the optical fiber 14-2 on the light receiving side becomes small, and when it falls below the threshold, the CPU 24-1 increases the current to the first thermoelectric cooling element 2. Let

  By repeating this operation, the temperature of the cooling surface 2-1 of the first thermoelectric cooling element 2 is adjusted so that the intensity of the reflected light received through the optical fiber 14-2 on the light receiving side is approximately equal to the threshold value. Adjusted. The adjusted temperature, that is, the temperature at which the dew condensation occurring on the mirror surface 11-1 reaches the equilibrium state (dew point temperature) is sent to the dew point temperature output unit 24-4.

  In this dew point detection operation, the heating surface 2-2 of the first thermoelectric cooling element 2 is cooled by the subcooler SC including the second thermoelectric cooling element 18 via the heat conductor 17. FIG. 5 shows a cooling curve of the subcooler SC as a characteristic I, and shows a cooling curve of the first thermoelectric cooling element 2 as a characteristic II. For reference, a cooling curve is shown as characteristic III when the subcooler SC is not used and the thermoelectric cooling element for mirror surface cooling is a large multistage Peltier.

  As can be seen by comparing the characteristic II and the characteristic III, when the thermoelectric cooling element for mirror surface cooling is a large multi-stage Peltier, the heat capacity around the mirror surface increases, and the responsiveness deteriorates. On the other hand, when the subcooler SC is used, the heat capacity around the mirror surface can be kept small, so that the responsiveness does not deteriorate.

  In this way, in this mirror-cooled dew point meter 201, by using the subcooler SC, it is possible to use a small element (Peltier with a high cooling speed) having a relatively small cooling capacity as the first thermoelectric cooling element 2. ing. For this reason, responsiveness is not sacrificed, and enlargement of the size around the mirror surface can be avoided. In addition, since a Peltier-type cooler is used for the subcooler SC, a refrigerant-type cooler and piping are not required, the apparatus is not complicated, and the size is reduced. Moreover, there is no fear of refrigerant leakage.

[Dew point measurement with the operation mode set to "Linked"]
Next, a case where the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “interlocking” and dew point measurement is started will be described. Also in this case, the dew point measurement ON / OFF switch 28 and the subcooler control ON / OFF switch 29 are simultaneously turned ON.

  When the sub-cooler control ON / OFF switch 29 is turned on, the CPU 24-1 of the main controller 24 sets the sub-cooler control ON / OFF switch 29 in accordance with the current setting state of the sub-cooler low temperature / high temperature / interlocking selector switch 30. The CPU 25-1 of the sub-controller 25 is informed that it has been turned ON.

[Operation on the sub-controller side]
When the CPU 25-1 of the sub-controller 25 receives notification from the main controller 24 that the sub-cooler control ON / OFF switch 29 has been turned ON (FIG. 3: YES in step S101), it opens the gate valve 33 (step S102). Then, the operation of the suction pump 34 is started (step S103), the inflow of the gas to be measured into the sampling chamber 31 is started, and the operation of the cooling fan 20 is started (step S104, signal S5).

  Further, the CPU 25-1 of the sub controller 25 checks the current setting state of the sub cooler low temperature / high temperature / interlocking switch selector switch 30 notified from the main controller 24 (step S105). In this case, since the setting state of the subcooler low temperature / high temperature / interlocking selector switch 30 is “interlocking”, the mirror surface temperature tPpv from the first temperature sensor 12 is acquired (step S106), and the set target temperature of the subcooler is acquired. Tsp is set to a mirror surface temperature tPpv + α (step S107).

  Then, the outside air temperature tout from the outside air temperature sensor 23 is taken in (step S111), and the set target temperature Tsp determined in step S107 is compared with the outside air temperature tout (step S112). If the set target temperature Tsp is equal to or lower than the outside air temperature tout (YES in step S112), the sub-cooler temperature tSpv from the second temperature sensor 21 is taken in (step S114), and the sub-cooler temperature tSpv and the set target temperature Tsp are The current supplied to the second thermoelectric cooling element 18 is ON / OFF controlled so as to match (step S115).

  On the other hand, when the set target temperature Tsp is higher than the outside air temperature tout (NO in step S112), the set target temperature Tsp is set to the outside air temperature tout (step S113), that is, the upper limit value of the set target temperature Tsp is set to the outside air temperature. The current supplied to the second thermoelectric cooling element 18 is controlled to be ON / OFF so that the subcooler temperature tSpv and the set target temperature Tsp coincide with each other (steps S114 and S115).

[Operation on the main controller side]
The operation on the main controller 24 side is the same as the case where the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “low temperature”, and the description thereof is omitted here.

  When the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “low temperature”, that is, when the set target temperature Tsp of the subcooler is fixed at a low temperature (for example, −5 ° C.), the fixed set target temperature A dew point higher than Tsp cannot be measured. Even when the dew point near the upper limit of the measurement range is measured, a large amount of energy is consumed because the set target temperature Tsp is fixed.

  On the other hand, when the subcooler low temperature / high temperature / linkage selector switch 30 is set to “linkage”, that is, when the set target temperature Tsp of the subcooler is set to the mirror surface temperature tPpv + α, the set target temperature Tsp increases as the mirror surface temperature tPpv increases. Therefore, the dew point can be measured up to the same temperature as the ambient temperature. Further, since the set target temperature Tsp always fluctuates at the mirror surface temperature tPpv + α, the consumed energy becomes the minimum necessary.

[Mirror surface maintenance (1)]
For example, it is assumed that maintenance of the mirror surface 11-1 is desired during dew point measurement with the operation mode set to "low temperature". In this case, the dew point measurement ON / OFF switch 28 is turned OFF, and the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “high temperature”.

  Then, the CPU 24-1 of the main controller 24 interrupts the cooling operation of the mirror surface 11-1 by the first thermoelectric cooling element 2, and the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “high temperature”. Is notified to the CPU 25-1 of the sub-controller 25.

  When the CPU 25-1 of the sub-controller 25 receives notification from the main controller 24 that the sub-cooler low temperature / high temperature / interlocking selector switch 30 has been set to “high temperature”, the sub-cooler set target temperature Tsp is set to a high temperature (for example, 25 ° C) (FIG. 3: Steps S108 and S110).

  Then, the subcooler temperature tSpv from the second temperature sensor 21 is taken in (step S114), and the current supplied to the second thermoelectric cooling element 18 is turned ON / OFF so that the subcooler temperature tSpv and the set target temperature Tsp match. Control is performed (step S115). In this case, since the set target temperature Tsp is higher than the subcooler temperature tSpv, a reverse current is applied to the second thermoelectric cooling element 18. Thereby, subcooler SC is utilized as a heater and the mirror surface is returned to room temperature in a short time.

[Mirror surface maintenance (2)]
For example, it is assumed that maintenance of the mirror surface 11-1 is to be performed during the dew point measurement with the operation mode “interlocking”. In this case, the dew point measurement ON / OFF switch 28 is turned OFF and the subcooler low temperature / high temperature / interlocking selector switch 30 is set to “high temperature” in the same manner as during dew point measurement with the operation mode set to “low temperature”. However, the dew point measurement ON / OFF switch 28 may be simply turned OFF.

  When the dew point measurement ON / OFF switch 28 is turned OFF, the CPU 24-1 of the main controller 24 interrupts the cooling operation of the mirror surface 11-1 by the first thermoelectric cooling element 2. In this case, the CPU 25-1 of the sub-controller 25 continues control to set the sub-cooler target temperature Tsp to the mirror surface temperature tPpv + α. Thereby, the set target temperature Tsp of the subcooler also increases as the temperature increases due to the interruption of the cooling operation of the mirror surface 11-1.

  In this way, if dew point measurement is being performed with the operation mode set to “interlocking”, the decool point measurement ON / OFF switch 28 is simply turned OFF, and the set target temperature Tsp of the subcooler is automatically switched without switching to a high temperature. The mirror surface can be returned to room temperature.

[Performance of main controller and sub controller]
In this mirror-cooled dew point meter 201, the generation speed of condensation on the mirror surface 11-1 is very fast, and the mirror surface temperature tPpv and the amount of reflected light from the mirror surface must be measured with high accuracy. On the other hand, the control of the subcooler SC is slow because the heat capacity is large, and the detection of the subcooler temperature tSpv does not require much accuracy.

  Therefore, in the mirror-cooled dew point meter 201, the main controller 24 requires high-speed control and high-accuracy measurement. Therefore, a high-performance and high-price controller is used, and the sub-controller 25 requires less control performance and measurement accuracy. Therefore, by using a low-performance / low-cost controller, the cost and performance of the main controller 24 and the sub-controller 25 are balanced to reduce the product cost.

  This point will be described more specifically. The main controller 24 A / D converts the amount of reflected light received by the optical fiber 14-2 on the light receiving side, and supplies a predetermined current to the first thermoelectric cooling element 2 based on the A / D conversion value. Control with the control cycle. Further, the mirror surface temperature tPpv detected by the first temperature sensor 12 is A / D converted, and the mirror surface temperature tPpv at every moment is displayed. And the temperature when the dew condensation produced on the mirror surface 11-1 reaches the equilibrium state is displayed as the dew point temperature. On the other hand, the sub-controller 25 performs A / D conversion on the sub-cooler temperature tSpv detected by the second temperature sensor 21, and performs a predetermined control on the current supplied to the second thermoelectric cooling element 18 based on the A / D conversion value. Control by cycle.

  In the main controller 24, A / D conversion of the amount of reflected light received by the light receiving side optical fiber 14-2 is performed by the first A / D converter 24-2, and the first A / D conversion value is used. The CPU 24-1 controls the supply current to one thermoelectric cooling element 2 in a predetermined control cycle. The A / D conversion of the mirror surface temperature tPpv detected by the first temperature sensor 12 is performed by the second A / D converter 24-3. On the other hand, in the sub-controller 25, the A / D conversion of the sub-cooler temperature tSpv detected by the second temperature sensor 21 is performed by the first A / D converter 25-2, and the second based on the A / D conversion value. The CPU 25-1 controls the current supplied to the thermoelectric cooling element 18 at a predetermined control cycle.

  Here, in order to balance the cost and performance of the main controller 24 and the sub-controller 25, the A / D of the first A / D converter 24-2 and the second A / D converter 24-3 in the main controller 24 is used. The accuracy of D conversion is higher than the accuracy of A / D conversion of the first A / D converter 25-2 in the sub-controller 25. Further, the control cycle of the supply current to the first thermoelectric cooling element 2 in the main controller 24 is shorter than the control cycle of the supply current to the second thermoelectric cooling element 18 in the sub-controller 25.

  In the sub-controller 25, the accuracy of the A / D conversion of the second A / D converter 24-3 is approximately the same as that of the first A / D converter 25-2. In this example, for the sake of explanation, the first A / D converter 25-2 and the second A / D converter 25-3 are provided separately, but the first A / D converter 25- 2 and the second A / D converter 25-3, and one A / D converter may be used in a time-sharing manner.

  In this mirror-cooled dew point meter 201, the control period of the supply current from the main controller 24 to the first thermoelectric cooling element 2 is the control period of the supply current from the sub-controller 25 to the second thermoelectric cooling element 18. Although the cycle is shorter, the control of the supply current from the main controller 24 to the first thermoelectric cooling element 2 is proportionally controlled, and the control of the supply current from the sub-controller 25 to the second thermoelectric cooling element 18 is controlled. May be set to ON / OFF control.

  That is, the main controller 24 that controls condensation in an equilibrium state requires high-speed and precise control, and therefore employs proportional control, and the sub-controller 25 that controls the temperature of the sub-cooler may be relatively about control. The control method may be different, such as adopting ON / OFF control that is not high in control performance and can be realized at a low price. Of course, both the main controller 24 / sub-controller 25 may control the supply current by proportional control.

[Normal / abnormal judgment of mirror surface status using the received light intensity reference range]
The CPU 24-1 of the main controller 24 controls the supply current to the first thermoelectric cooling element 2 (dew point temperature) so as to achieve an equilibrium state in which the increase or decrease of the condensation occurring on the mirror surface 11-1 is eliminated as a periodic interrupt processing operation. Measurement control) is interrupted (FIG. 6: step S201).

  Then, after the elapse of a predetermined time (YES in step S202), the light amount (light reception amount) Rpv of the reflected light from the mirror surface 11-1 received through the light receiving side optical fiber 14-2 is obtained (step S203). ). Then, it is checked whether or not the calculated received light amount Rpv is within a predetermined received light amount reference range (step S204).

  That is, after interrupting the dew point temperature measurement control (step S201), the CPU 24-1 waits for the elapse of a predetermined time (step S202) to create a state in which no condensation occurs on the mirror surface 11-1, and the mirror surface at this time The received light amount Rpv of the reflected light from 11-1 is obtained (step S203), and it is checked whether or not the obtained received light amount Rpv is within a predetermined received light amount reference range (step S204).

  If the received light amount Rpv is within the received light amount reference range (YES in step S204), the CPU 24-1 determines that the state of the mirror surface 11-1 is normal, and resumes dew point temperature measurement control ( Step S205).

[Transition to automatic cleaning control]
On the other hand, if the received light amount Rpv is out of the received light amount reference range (NO in step S204), the CPU 24-1 determines that the state of the mirror surface 11-1 is abnormal and adheres to the mirror surface 11-1. In order to remove the condensate that would be present, the current supplied to the first thermoelectric cooling element 2 is controlled so as to raise the temperature of the mirror surface 11-1 (step S206). That is, the dew point temperature measurement control is stopped, and the control proceeds to control of the current supplied to the first thermoelectric cooling element 2 (automatic cleaning control) so as to increase the temperature of the mirror surface 11-1. In this example, the current supplied to the first thermoelectric cooling element 2 is increased to a predetermined current value, and the temperature of the mirror surface 11-1 is increased.

  Then, after elapse of a predetermined time (YES in step S207), N (initial value 0) is set to N = N + 1 (step S208), and it is confirmed that N> Nmax is not satisfied (NO in step S209). The process returns to S203. That is, by waiting for the elapse of a predetermined time, the temperature of the mirror surface 11-1 is increased to a value corresponding to the current value increased in step S206, and the reflection from the mirror surface 11-1 is performed again at the increased temperature. The amount of received light Rpv is obtained.

  In this case, if the dirt adhering to the mirror surface 11-1 is a condensed material, and the condensed material is removed by evaporation or sublimation due to the temperature rise of the mirror surface 11-1, the reflected light from the mirror surface 11-1. The received light amount Rpv falls within the received light amount reference range (YES in step S204), and the CPU 24-1 determines that the state of the mirror surface 11-1 has returned to normal, and resumes dew point temperature measurement control (step S205). .

  On the other hand, if the received light amount Rpv of the reflected light from the mirror surface 11-1 is out of the received light amount reference range (NO in step S204), the CPU 24-1 does not return the state of the mirror surface 11-1 to normal. The current supplied to the first thermoelectric cooling element 2 is increased by a predetermined amount (step S206), and the temperature of the mirror surface 11-1 is further increased.

  Then, after a predetermined time has elapsed (YES in step S207), N = N + 1 is set (step S208). After confirming that N> Nmax is not satisfied (NO in step S209), the process returns to step S203. The received light amount Rpv of the reflected light from the mirror surface 11-1 is obtained again at the raised temperature.

  In the same manner, it is checked whether or not the received light amount Rpv of the reflected light from the mirror surface 11-1 is within the received light amount reference range (step S204). Determining that the state has returned to normal (YES in step S204), restarting dew point temperature measurement control (step S205), and determining that the state of the mirror surface 11-1 has not returned to normal if it is outside the received light amount reference range. Then (NO in step S204), the current supplied to the first thermoelectric cooling element 2 is increased by a predetermined amount (step S206), and the processing operation of further increasing the temperature of the mirror surface 11-1 is repeated.

  In this way, in this mirror-cooled dew point meter 201, when the condensed material is attached to the mirror surface 11-1, the condensed material is evaporated or sublimated at a high speed due to the temperature rise of the mirror surface 11-1, There is no need to manually clean the mirror surface, and there is no need to provide a separate device for removing the condensed material. Moreover, in this mirror surface cooling-type dew point meter 201, when the stain | pollution | contamination adhering to the mirror surface 11-1 is a condensed substance, even if it does not understand the kind of the condensed substance, the process of the temperature rise of the mirror surface 11-1 is carried out. The condensed substance evaporates or sublimes along the way. Therefore, it is possible to return the state of the mirror surface 11-1 to a normal state without specifying the condensed substance in advance.

  When N> Nmax is satisfied during the repeated processing of steps S206 to S209 (YES in step S209), the CPU 24-1 determines that the stain on the mirror surface 11-1 cannot be recovered by the temperature rise, and is abnormal. An alarm is issued (step S210). For example, when dust adheres to the mirror surface 11-1 or the detection system is deteriorated, the temperature cannot be recovered by the temperature rise of the mirror surface 11-1, so that an alarm is issued. This alarm is sent to the host device via the dew point temperature output unit 24-4.

  In the flowchart shown in FIG. 6, after the dew point temperature measurement control is interrupted, the received light amount Rpv of the reflected light from the mirror surface 11-1 after the elapse of a predetermined time is obtained, but the first thermoelectric cooling element 2 After interrupting the control of the supply current to the light source, the change in the mirror surface temperature tPpv from the first temperature sensor 12 is checked, and the amount of reflected light received from the mirror surface 11-1 when the mirror surface temperature tPpv no longer changes Rpv may be obtained.

  FIG. 7 illustrates a flowchart in this case. This flowchart corresponds to FIG. 6. In step S202-1, the change in the mirror surface temperature tPpv is checked, and in step S202-2, the time point at which the change in the mirror surface temperature tPpv no longer occurs is determined. It should be noted that the point in time at which the change in the mirror surface temperature tPpv no longer occurs is determined as the timing when the rate of change in the mirror surface temperature tPpv falls below a predetermined value.

  Further, as shown in FIG. 8, instead of checking the change in the mirror surface temperature tPpv in step S202-1, the received light amount Rpv of the reflected light from the mirror surface 11-1 is checked, and in step S202-2, the received light amount Rpv. It is also possible to determine the point in time when no change occurs. Note that when the change in the amount of received light pv no longer occurs, it is determined as the timing when the rate of change in the amount of received light Rpv falls below a predetermined value.

  In addition, in this mirror surface cooling-type dew point meter 201, the dew condensation (dew point) which arises on the mirror surface 11-1 is detected, However, The frost (frost point) which arises on the mirror surface 11-1 by the same structure is detected. You can also. That is, the frost (frost point) generated on the mirror surface 11-1 is controlled by controlling the supply current to the first thermoelectric cooling element 2 so as to achieve an equilibrium state in which the increase or decrease of the frost generated on the mirror surface 11-1 is eliminated. It is also possible to detect.

  In this mirror-cooled dew point meter 201, the dew point measurement ON / OFF switch 28 and the subcooler control ON / OFF switch 29 are provided separately. However, the dew point measurement ON / OFF switch 28 and the subcooler control ON / OFF are provided. The switch 29 may be constituted by a single switch. In this case, dew point measurement is turned on and subcooler control is turned on simultaneously, and dew point measurement is turned off and subcooler control is turned off simultaneously.

  Further, in this mirror-cooled dew point meter 201, the first thermoelectric cooling element 2 is a one-stage Peltier, but it may be a two-stage Peltier. That is, as long as the size around the mirror surface and responsiveness are sufficient, a configuration in which a multistage Peltier and a subcooler are combined may be used. Further, in the mirror surface cooling type dew point meter 201, the second thermoelectric cooling element 18 is provided, but the second thermoelectric cooling element 18 is not necessarily provided, and only the first thermoelectric cooling element 2 is provided. You may be the structure provided.

  Further, in this mirror-cooled dew point meter 201, for example, as shown in the processing of steps S206 to S209 in FIG. 6, the temperature of the mirror surface 11-1 is gradually increased, but an appropriate temperature (for example, (100 ° C.) may be determined and the temperature may be increased at once. In this case, for example, if the mirror surface 11-1 does not return to a normal state even after a predetermined time has elapsed, an alarm is issued.

  Further, in this mirror-cooled dew point meter 201, as an automatic cleaning control, the thermoelectric cooling element 2 is used so as to raise the temperature of the mirror surface 11-1 in order to remove condensed substances that may have adhered to the mirror surface 11-1. Although the current supplied to is controlled, the pressure in the sampling chamber 31 may be controlled to be reduced in order to remove the condensed material that may have adhered to the mirror surface 11-1.

  When the condensed material that would have adhered to the mirror surface 11-1 is removed even if the mirror surface 11-1 is heated, it is damaged by heat shock. On the other hand, if the condensed substance that would have adhered to the mirror surface 11-1 is removed by reducing the pressure in the sampling chamber 31, there will be no heat shock as in the case of heating and damage will not occur. It becomes possible.

  FIG. 9 shows a flowchart corresponding to FIG. 6 in the case where the pressure in the sampling chamber 31 is controlled to be reduced in order to remove the condensate that may have adhered to the mirror surface 11-1. In this flowchart, the processing from steps S301 to S304 is the same as the processing from steps S201 to S204 in FIG.

  If the received light amount Rpv is out of the received light amount reference range (NO in step S304), the CPU 24-1 determines that the state of the mirror surface 11-1 is abnormal and adheres to the mirror surface 11-1. In order to remove the wax condensate, the gate valve 33 is closed and the operation of the suction pump 34 is continued to reduce the pressure in the sampling chamber 31 (step S306). That is, while the operation of the suction pump 34 is continued, the gate valve 33 is closed to shift to a pressure reduction control (automatic cleaning control) that lowers the pressure in the sampling chamber 31. The gate valve 33 is closed via the CPU 25-1 of the sub-controller 25.

  Then, after elapse of a predetermined time (YES in step S307), N (initial value 0) is set to N = N + 1 (step S309), and after confirming that N> Nmax is not satisfied (NO in step S309), step The process returns to S303. That is, by waiting for the elapse of a predetermined time, the pressure in the sampling chamber 31 is reduced to a predetermined value, and the received light amount Rpv of the reflected light from the mirror surface 11-1 is again set in a state where this pressure is reduced. Ask.

  In this case, if the dirt adhering to the mirror surface 11-1 is a condensed substance and the condensed substance is removed by evaporation or sublimation due to a decrease in the pressure in the sampling chamber 31, the reflection from the mirror surface 11-1. The light reception amount Rpv falls within the light reception amount reference range (YES in step S304), and the CPU 24-1 determines that the state of the mirror surface 11-1 has returned to normal, and continues the operation of the suction pump 34. Thus, the gate valve 33 is opened, and the dew point temperature measurement control is resumed (step S305).

  On the other hand, if the received light amount Rpv of the reflected light from the mirror surface 11-1 is out of the received light amount reference range (NO in step S304), the CPU 24-1 does not return to the normal state of the mirror surface 11-1. When the gate valve 33 is kept closed, the passage of a predetermined time is waited (YES in step S307), and the pressure in the sampling chamber 31 is further reduced. In this case, the elapsed time in step S307 is shorter than the first elapsed time, and the amount of decrease in the pressure in the sampling chamber 31 is small. Thereby, the pressure in the sampling chamber 31 decreases to the predetermined value PL at the first time and decreases to PL-α at the second time.

  Then, the CPU 24-1 sets N = N + 1 (step S308), confirms that N> Nmax is not satisfied (NO in step S309), returns to the process in step S303, and again at the increased temperature, the mirror surface 11 The received light amount Rpv of the reflected light from −1 is obtained.

  Similarly, it is checked whether or not the received light amount Rpv of the reflected light from the mirror surface 11-1 is within the received light amount reference range (step S304). Determining that the state has returned to normal (YES in step S304), restarting dew point temperature measurement control (step S305), and determining that the state of the mirror surface 11-1 has not returned to normal if it is outside the received light amount reference range. Then (NO in step S304), the processing operation of reducing the pressure in the sampling chamber 31 by a predetermined amount α (steps S306 and 307) is repeated.

  If N> Nmax is satisfied during the repeated processing of steps S306 to S309 (YES in step S409), the CPU 24-1 determines that the stain on the mirror surface 11-1 cannot be recovered due to a temperature rise, and issues an alarm. (Step S310).

  In the flowchart shown in FIG. 9, after interrupting the control of the current supplied to the first thermoelectric cooling element 2, the received light amount Rpv of the reflected light from the mirror surface 11-1 after a lapse of a predetermined time is obtained. As shown in the flowchart of FIG. 10 corresponding to the flowchart of FIG. 7, after the control of the supply current to the first thermoelectric cooling element 2 is interrupted, the change in the mirror surface temperature tPpv from the first temperature sensor 12 is checked. The received light amount Rpv of the reflected light from the mirror surface 11-1 when the mirror surface temperature tPpv no longer changes may be obtained.

  As shown in FIG. 11, instead of checking the change in the mirror surface temperature tPpv in step S302-1, the received light amount Rpv of the reflected light from the mirror surface 11-1 is checked, and in step S302-2, the received light amount Rpv. It is also possible to determine the point in time when no change occurs. Note that when the change in the amount of received light pv no longer occurs, it is determined as the timing when the rate of change in the amount of received light Rpv falls below a predetermined value.

[Functional block diagram of the main part of the mirror-cooled dew point meter]
FIG. 12 shows a functional block diagram of the main part of the above-described mirror-cooled dew point meter 201. In this figure, the same reference numerals as those in FIGS. 1 and 2 denote the same or equivalent components as those described with reference to FIGS. 1 and 2, and the description thereof will be omitted. In this specular cooling type dew point meter 201, the control unit 201B includes a dew point temperature measurement control unit 34, a specular surface abnormal state determination unit 35, an automatic cleaning control unit 36, and a control mode selection unit 37. In addition, when starting dew point measurement, the suction pump 34 is operated and the gate valve 33 is opened, but a control unit for the gate valve 33 and the suction pump 34 is not shown.

  In the control unit 201B, the dew point temperature measurement control unit 34 mirrors the current supplied to the thermoelectric cooling element 2 based on the amount of reflected light from the mirror surface 11-1 received through the light receiving side optical fiber 14-2. 11-1 is controlled so that there is no increase or decrease in dew condensation or frost formation, and the temperature tx1 of the mirror surface 11-1 detected by the temperature sensor 12 in the equilibrium state is taken in and controlled as a dew point temperature measurement value tx1. The data is sent to the mode selection unit 37.

  In the control unit 201B, the mirror surface abnormality state determination unit 35 determines whether the state of the mirror surface 11-1 is normal or abnormal based on the amount of reflected light from the mirror surface 11-1 received through the light receiving side optical fiber 14-2. The determination result is sent to the control mode selection unit 37.

  In the control unit 201B, the automatic cleaning control unit 36 supplies current to the thermoelectric cooling element 2 so as to raise the temperature of the mirror surface 11-1 so as to remove the condensed material that may have adhered to the mirror surface 11-1. To control. In this example, the temperature tx1 of the mirror surface 11-1 detected by the temperature sensor 12 is given to the automatic cleaning control unit 36. In this example, a method of increasing the current value supplied to the thermoelectric cooling element 2 is taken. Therefore, the temperature tx1 of the mirror surface 11-1 detected by the temperature sensor 12 is not necessarily required.

  In the control unit 201B, the control mode selection unit 37 instructs the dew point temperature measurement control unit 34 to always execute the dew point temperature measurement control, and periodically interrupts the dew point temperature measurement control to cause a mirror surface abnormality. Whether the state of the mirror surface 11-1 is normal or abnormal is determined by the state determination unit 35, and when the state of the mirror surface 11-1 is abnormal, the automatic cleaning control unit 36 performs automatic cleaning of the mirror surface 11-1. . When the state of the mirror surface 11-1 returns to normal by this automatic cleaning, the control mode selection unit 37 restarts the dew point temperature measurement control by the dew point temperature measurement control unit 34. In addition, during the dew point temperature measurement control by the dew point temperature measurement control unit 34, the control mode selection unit 37 outputs the dew point temperature measurement value tx1 from the dew point temperature measurement control unit 34 to the host device.

  FIG. 13 is a time chart showing changes in the control mode in this mirror-cooled dew point meter 201. The control mode selection unit 37 always executes the dew point temperature measurement control by the dew point temperature measurement control unit 34. During the dew point temperature measurement control (period T1), the control mode selection unit 37 periodically interrupts this dew point temperature measurement control, and the mirror surface abnormal state determination unit 35 determines whether the mirror surface 11-1 is normal or abnormal. Execute (t1, t2, t3 points). Here, for example, when it is determined that the state of the mirror surface 11-1 is abnormal at the point t3, the control mode selection unit 37 stops the dew point temperature measurement control by the dew point temperature measurement control unit 34, and performs automatic cleaning. The control unit 36 shifts to automatic cleaning control. Then, after the transition to the automatic cleaning control, when the mirror surface abnormal state determination unit 35 confirms that the state of the mirror surface 11-1 has returned to normal (point t4), the control mode selection unit 37 performs dew point temperature measurement. The dew point temperature measurement control by the control unit 34 is resumed.

  In this mirror cooled dew point meter 201 alone, the dew point temperature measurement control is once stopped (stopped) and the mirror surface 11-1 is heated in order to remove condensed substances that may have adhered to the mirror surface 11-1. . For this reason, as shown as a period T2 in FIG.

[Dew point temperature measurement system]
Therefore, in the dew point temperature measurement system of the present embodiment, two mirror-cooled dew point meters 201 are used, one is a dew point meter for initial measurement, and the other is an auxiliary dew point meter for initial operation. By doing so, the dew point temperature can be continuously measured even when one of the dew point meters is under automatic cleaning control. That is, the period T2 during which the dew point temperature cannot be measured is prevented from occurring.

  FIG. 14 shows a functional block diagram of the main part of the dew point temperature measurement system of the present embodiment. In this dew point temperature measurement system, two mirror-cooled dew point meters 201 are used, one mirror-cooled dew point meter 201 is a first mirror-cooled dew point meter (dew point meter 1) 201L, and the other mirror-cooled dew point meter 201 is used. 201 is a second mirror-cooled dew point meter (dew point meter 2) 201R.

  In the first specular cooling dew point meter 201L, the control unit 201BL includes a dew point temperature measurement control unit 34L, a specular abnormal state determination unit 35L, an automatic cleaning control unit 36L, and a control mode selection unit 37L.

 In the second specular cooling dew point meter 201R, the control unit 201BR includes a dew point temperature measurement control unit 34R, a specular abnormal state determination unit 35R, an automatic cleaning control unit 36R, and a control mode selection unit 37R.

  A gate valve 33L and a suction pump 34L are provided for the first mirror-cooled dew point meter 201L, and a gate valve 33R and a suction pump 34R are provided for the second mirror-cooled dew point meter 201R. It has been. Although the control unit for the gate valves 33L and 33R and the suction pumps 34L and 34R is not shown, when the dew point measurement is started, the suction pumps 34L and 34R are operated and the gate valves 33L and 33R are opened. A gas to be measured is branched and supplied to the sampling chambers 31L and 31R. That is, in the present embodiment, the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R are installed in parallel, and the gas to be measured having the same supply source is placed in the sampling chambers 31L and 31R. It is made to flow at the same time.

  Further, in this dew point temperature measurement system, for the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R, an overall controller 300 that controls the operation of the specular cooling type dew point meters 201L and 201R. Is provided. The overall controller 300 includes a dew point meter control mode specifying unit 301, a dew point temperature measurement value selecting unit 302, a dew point meter current control mode recognizing unit 303, and a specular state determination result recognizing unit 304.

  In the first specular cooling type dew point meter 201L, the control mode selection unit 37L receives the designation of the control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and receives the current current value in the first specular cooling type dew point meter 201L. Select whether the control mode is the dew point temperature measurement control mode or the automatic cleaning control mode. In addition, the control mode selection unit 37L sends the currently selected control mode to the dew point meter current control mode recognition unit 303 of the overall controller 300. Further, the control mode selection unit 37L sends the dew point temperature measurement value tx1 from the dew point temperature measurement control unit 34L to the dew point temperature measurement value selection unit 302 of the overall controller 300. In the first specular cooling dew point meter 201L, the specular state determination unit 35L determines whether the specular state of the specular surface 11-1L is normal / abnormal, not the control mode selection unit 37L of itself, and the specular state of the overall controller 300. The result is sent to the determination result recognition unit 304.

  In the second specular cooling type dew point meter 201R, the control mode selection unit 37R receives the control mode designation from the dew point meter control mode designation unit 301 of the overall controller 300, and determines the current control mode in the specular cooling type dew point meter 201R. Select the dew point temperature measurement control mode or automatic cleaning control mode. Further, the control mode selection unit 37R sends the currently selected control mode to the dew point meter current control mode recognition unit 303 of the overall controller 300. Also, the control mode selection unit 37R sends the dew point temperature measurement value tx2 from the dew point temperature measurement control unit 34R to the dew point temperature measurement value selection unit 302 of the overall controller 300. Further, in the second mirror-cooled dew point meter 201R, the mirror surface state determination unit 35R determines the normal / abnormal state determination result of the state of the mirror surface 11-1R, not the own control mode selection unit 37R, but the mirror surface state of the overall controller 300. The result is sent to the determination result recognition unit 304.

  The dew point meter current control mode recognition unit 303 of the overall controller 300 recognizes the currently selected control mode sent from the first specular cooling dew point meter 201L and the second specular cooling dew point meter 201R, and The recognition result is sent to the dew point meter control mode designating unit 301 and the dew point temperature measurement value selecting unit 302 and notified to the host device.

  The specular state determination result recognition unit 304 of the overall controller 300 recognizes the determination result of the specular state sent from the first specular cooling dew point meter 201L and the second specular cooling type dew point meter 201R, and uses the recognition result as a result. The dew point meter control mode designation unit 301 and the dew point temperature measurement value selection unit 302 are sent to the host device and notified to the host device.

  The dew point temperature measurement value selection unit 302 of the overall controller 300 includes a dew point temperature measurement value tx1 from the first mirror-cooled dew point meter 201L, and a dew point temperature measurement value tx2 from the second mirror-cooling dew point meter 201R. , The recognition result of the control mode currently selected in the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R from the dew point meter current control mode recognition unit 303, and the specular state determination result recognition unit 304 From the result of recognition of normal / abnormality of the mirror surface state in the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R from the measured value, the measured dew point is either the measured value tx1 or tx2 of the dew point temperature. Decide whether to notify the host device as the temperature.

  The dew point meter control mode specifying unit 301 of the overall controller 300 is a control mode currently selected in the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R from the dew point meter current control mode recognition unit 303. And the recognition result of normal / abnormality of the specular state in the first specular cooling dew point meter 201L and the second specular cooling dew point meter 201R from the specular state determination result recognition unit 304, the first specular surface A control mode to be designated for the cooling dew point meter 201L and the second specular cooling type dew point meter 201R is determined.

  The dew point meter control mode designating unit 301 of the overall controller 300 designates the dew point temperature measurement control mode as the control mode for the first mirror-cooled dew point meter 201L as an initial setting when the operation of the dew point temperature measurement system is started. The automatic cleaning control mode is designated as the control mode for the second mirror-cooled dew point meter 201R. That is, the dew point meter control mode designating unit 301 of the overall controller 300 first sets the first specular cooling type dew point meter 201L (dew point meter 1) as a dew point meter for initial measurement, and performs the second specular cooling. A type dew point meter 201R (dew point meter 2) is set as an auxiliary dew point meter at the beginning of operation.

[Operation method 1: Alternate switching in case of abnormality]
FIGS. 15A and 15B show changes in the control mode in the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R when this dew point temperature measurement system is operated in the operation method 1. It is a time chart.

  First, the dew point meter control mode designating unit 301 of the overall controller 300 designates the dew point temperature measurement control mode as the control mode for the first specular cooling dew point meter 201L, and the control mode for the second specular cooling type dew point meter 201R. Specify the automatic cleaning control mode. As a result, the first mirror-cooled dew point meter 201L is set as a dew point meter for initial measurement, and the second mirror-cooled dew point meter 201R is set as an auxiliary dew point meter for initial operation.

  The control mode selection unit 37L of the first mirror-cooled dew point meter 201L set as a dew point meter for measurement at the beginning of operation always executes the dew point temperature measurement control by the dew point temperature measurement control unit 34L, and is used for auxiliary at the beginning of operation. The control mode selection unit 37R of the second mirror-cooled dew point meter 201R set as the dew point meter always performs automatic cleaning control by the automatic cleaning control unit 36R.

  FIG. 16 shows a control flowchart of the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R when operated in the operation method 1. FIG. 17 shows a control flowchart of the overall controller 300 when the operation method 1 is also used.

  The control mode selection unit 37L of the first specular cooling type dew point meter 201L periodically interrupts the dew point temperature measurement control during the dew point temperature measurement control, and changes the state of the mirror surface 11-1L by the mirror surface abnormal state determination unit 35L. Normal / abnormal judgment is executed (points t1, t2, and t3). That is, the control mode selection unit 37L confirms the current self control mode (FIG. 16: step S401), and since the current self control mode is dew point temperature measurement control (YES in step S402), the mirror surface state It is checked whether or not it is the confirmation timing (step S403), and if it is the mirror surface state confirmation timing (YES in step S403), the dew point temperature measurement control is interrupted and the state (normal / abnormal) of the mirror surface 11-1L is confirmed. (Step S404).

  Here, for example, when it is determined that the state of the mirror surface 11-1L is abnormal at point t3 (NO in step S405), the mirror surface abnormality state determination unit 35L notifies the overall controller 300 of the determination result (step S405). S406). Note that at the points t1 and t2, it is determined that the state of the mirror surface 11-1L is normal (YES in step S405). The result of the determination of normality is also notified to the overall controller 300 from the mirror surface abnormal state determination unit 35L (step S407). Further, when the mirror surface state confirmation timing is not reached during the dew point temperature measurement control (NO in step S403), the control mode selection unit 37L notifies the overall controller 300 of the dew point temperature measurement value tx1 from the dew point temperature measurement control unit 34L. (Step S408).

  On the other hand, the control mode selection unit 37R of the second specular cooling type dew point meter 201R causes the automatic cleaning control unit 36R to perform automatic cleaning control. In this case, as the automatic cleaning control, the automatic cleaning of the mirror surface 11-R is periodically executed, and the normal / abnormal determination of the state of the mirror surface 11-1R after the cleaning is performed by the mirror surface abnormal state determination unit 35R. The mirror surface abnormal state determination unit 35R notifies the overall controller 300 of the determination result of normality / abnormality (step S409).

  Based on the recognition result from the dew point meter current control mode recognition unit 303, the dew point meter control mode setting unit 301 of the overall controller 300 determines the current control of the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R. The mode is confirmed (FIG. 17: Step S501). In this case, since the current control mode of the first specular cooling dew point meter 201L is the dew point temperature measurement control mode (YES in step S502), the first specular surface is determined based on the recognition result from the specular state determination result recognition unit 304. The state of the mirror surface 11-1L of the cooling type dew point meter 201L is confirmed (step S503).

  Here, at the point t3 shown in FIG. 15 (a), if the determination result that the state of the mirror surface 11-1L is abnormal is sent from the first mirror surface cooling type dew point meter 201L (step). (NO in S504), the dew point meter control mode designation unit 301 sends a switching command to the first mirror-cooled dew point meter 201L so as to shift the control mode to the automatic cleaning control mode (step S505), and the second A switching command is sent to the mirror-cooled dew point meter 201R so as to shift the control mode to the dew point temperature measurement control mode (step S506).

  If a determination result indicating that the state of the mirror surface 11-1L is normal is sent from the first mirror-cooled dew point meter 201L (YES in step S504), the dew point temperature measurement value selection unit 302 is The dew point temperature measurement value tx1 from the mirror surface cooling type dew point meter 201L is taken in and output as a measurement result of the dew point temperature measurement system (step S507).

  The control mode selection unit 37L of the first specular cooling type dew point meter 201L receives the switching command to the automatic cleaning control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode to the dew point temperature until then. Switching from the measurement control mode to the automatic cleaning control mode (point t3 shown in FIG. 15A). In other words, the dew point temperature measurement control up to that point is stopped, and the process shifts to automatic cleaning control.

  On the other hand, the control mode selection unit 37R of the second specular cooling type dew point meter 201R receives the switching command to the dew point temperature control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode up to that time. The automatic cleaning control mode is switched to the dew point temperature measurement control mode (point t3 shown in FIG. 15B). That is, the automatic cleaning control up to that point is stopped and the process proceeds to dew point temperature measurement control.

  The control mode selection unit 37R of the second specular cooling type dew point meter 201R periodically interrupts the dew point temperature measurement control during the dew point temperature measurement control, and determines the state of the mirror surface 11-1R by the mirror surface abnormal state determination unit 35R. Normal / abnormal judgment is executed (t4, t5... Tn point). That is, the control mode selection unit 37R confirms the current self control mode (step S401), and the current self control mode is dew point temperature measurement control (YES in step S402). (Step S403), if it is the mirror surface state confirmation timing (YES in step S403), the dew point temperature measurement control is interrupted and the state (normal / abnormal) of the mirror surface 11-1R is confirmed (step). S404).

  Here, for example, when it is determined that the state of the mirror surface 11-1R is abnormal at the point tn (NO in step S405), the mirror surface abnormal state determination unit 35R notifies the overall controller 300 of the determination result (step S405). S406). In this example, it is determined that the state of the mirror surface 11-1L is normal at the points t4 to tn-1 (YES in step S405), and the determination result indicating that the mirror surface is normal is also determined as the mirror surface abnormal state determination. The overall controller 300 is notified from the unit 35R (step S407). Further, when the mirror surface state confirmation timing is not reached during the dew point temperature measurement control (NO in step S403), the control mode selection unit 37R notifies the overall controller 300 of the dew point temperature measurement value tx2 from the dew point temperature measurement control unit 34R. (Step S408).

  On the other hand, the control mode selection unit 37L of the first mirror-cooled dew point meter 201L performs automatic cleaning control by the automatic cleaning control unit 36L. In this case, as the automatic cleaning control, automatic cleaning of the mirror surface 11-L is periodically performed, and the mirror surface abnormal state determination unit 35L determines whether the mirror surface 11-1L after the cleaning is normal or abnormal. The mirror surface abnormal state determination unit 35L notifies the overall controller 300 of the normal / abnormal determination result (step S409).

  Based on the recognition result from the dew point meter current control mode recognition unit 303, the dew point meter control mode designating unit 301 of the overall controller 300 determines the current control of the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R. The mode is confirmed (step S501). In this case, since the current control mode of the first specular cooling dew point meter 201R is not dew point temperature measurement control (NO in step S502), that is, the current control mode of the second specular cooling type dew point meter 201R is dew point temperature measurement. Since it is control, the state of the mirror surface 11-1L of the second mirror surface cooling type dew point meter 201R is confirmed from the recognition result from the mirror surface state determination result recognition unit 304 (step S508).

  Here, at the point tn shown in FIG. 15, if the determination result that the state of the mirror surface 11-1R is abnormal is sent from the second mirror-cooled dew point meter 201R (NO in step S509). ), The dew point meter control mode designating unit 301 sends a switching command to the second specular cooling type dew point meter 201R so as to shift the control mode to the automatic cleaning control mode (step S510), and the first specular cooling type A switching command is sent to the dew point meter 201L so as to shift the control mode to the dew point temperature measurement control mode (step S511).

  If a determination result indicating that the state of the mirror surface 11-1R is normal is sent from the second mirror-cooled dew point meter 201R (YES in step S509), the dew point temperature measurement value selection unit 302 is The dew point temperature measurement value tx22 from the mirror surface cooling type dew point meter 201R is taken in and output as a measurement result of the dew point temperature measurement system (step S512).

  The control mode selection unit 37L of the first specular cooling type dew point meter 201L receives the switching command to the dew point temperature measurement control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and automatically changes the control mode to the previous control mode. Switching from the cleaning control mode to the dew point temperature measurement control mode (tn point shown in FIG. 15A). That is, the automatic cleaning control so far is stopped and the dew point temperature measurement control is restored.

  On the other hand, the control mode selection unit 37R of the second mirror-cooled dew point meter 201R receives the switching command to the automatic cleaning control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode up to that time. The dew point temperature measurement control mode is switched to the automatic cleaning control mode (point tn shown in FIG. 15B). That is, the previous dew point temperature measurement control is stopped and the automatic cleaning control is resumed.

  Thus, in this operation method 1, first, the first mirror-cooled dew point meter 201L is set as a dew point meter for measurement at the beginning of operation (a dew point meter that performs dew point temperature measurement control), and the second The mirror-cooled dew point meter 201R is set as an auxiliary dew point meter (dew point meter that executes automatic cleaning control) at the beginning of operation, and every time an error occurs in the dew point meter that is performing dew point temperature measurement control, automatic cleaning is performed until then. The dew point meter that was executing the control is switched to the dew point temperature measurement control, and the dew point meter that was previously executing the dew point temperature measurement control is switched to the automatic cleaning control, and one dew point meter is in the automatic cleaning control. However, since the other dew point meter performs dew point temperature measurement control, there is no period during which dew point temperature measurement control is stopped, and the dew point temperature must be measured continuously. It becomes possible way.

[Operation method 2: Switch only when an error occurs]
FIGS. 18A and 18B show changes in the control modes in the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R when this dew point temperature measurement system is operated in the operation method 2. It is a time chart.

  First, the dew point meter control mode designating unit 301 of the overall controller 300 designates the dew point temperature measurement control mode as the control mode for the first specular cooling dew point meter 201L, and the control mode for the second specular cooling type dew point meter 201R. Specify the automatic cleaning control mode. As a result, the first mirror-cooled dew point meter 201L is set as the initial measurement dew point meter (main dew point meter), and the second mirror-cooled dew point meter 201R is the initial auxiliary dew point meter ( Sub dew point meter).

  The control mode selection unit 37L of the first mirror-cooled dew point meter 201L set as the main dew point meter always executes the dew point temperature measurement control by the dew point temperature measurement control unit 34L, and the first dew point meter set as the sub dew point meter. The control mode selection unit 37R of the second mirror-cooled dew point meter 201R always performs automatic cleaning control by the automatic cleaning control unit 36R.

  FIG. 19 shows a control flowchart of the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R when operated in the operation method 2. FIG. 20 shows a control flowchart of the overall controller 300 when the operation method 2 is also used.

  The control mode selection unit 37L of the first specular cooling type dew point meter 201L periodically interrupts the dew point temperature measurement control during the dew point temperature measurement control, and changes the state of the mirror surface 11-1L by the mirror surface abnormal state determination unit 35L. Normal / abnormal judgment is executed (points t1, t2, and t3). That is, the current self control mode is confirmed (FIG. 19: Step S601), and since the current self control mode is dew point temperature measurement control (YES in Step S602), it is checked whether or not the mirror surface state confirmation timing is reached. If it is the mirror surface state confirmation timing (YES in step S603), the dew point temperature measurement control is interrupted and the state (normal / abnormal) of the mirror surface 11-1L is confirmed (step S604).

  Here, for example, when it is determined that the state of the mirror surface 11-1L is abnormal at the point t3 (NO in step S605), the mirror surface abnormal state determination unit 35L notifies the overall controller 300 of the determination result (step S605). S606). Note that at the points t1 and t2, it is determined that the state of the mirror surface 11-1L is normal (YES in step S605). The result of the determination of normality is also notified from the mirror surface abnormal state determination unit 35L to the general controller 300 (step S607). In addition, during the dew point temperature measurement control, when the mirror surface state confirmation timing is not reached (NO in step S603), the control mode selection unit 37L notifies the overall controller 300 of the dew point temperature measurement value tx1 from the dew point temperature measurement control unit 34L. (Step S608).

  On the other hand, the control mode selection unit 37R of the second specular cooling type dew point meter 201R causes the automatic cleaning control unit 36R to perform automatic cleaning control. In this case, as the automatic cleaning control, the automatic cleaning of the mirror surface 11-R is periodically executed, and the normal / abnormal determination of the state of the mirror surface 11-1R after the cleaning is performed by the mirror surface abnormal state determination unit 35R. The mirror surface abnormal state determination unit 35R notifies the general controller 300 of the normal / abnormal determination result (step S609).

  Based on the recognition result from the dew point meter current control mode recognition unit 303, the dew point meter control mode designating unit 301 of the overall controller 300 determines the current control of the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R. The mode is confirmed (FIG. 20: Step S701). In this case, since the current control mode of the first specular cooling dew point meter 201L is the dew point temperature measurement control mode (YES in step S702), the first specular surface is determined based on the recognition result from the specular state determination result recognition unit 304. The state of the mirror surface 11-1L of the cooling type dew point meter 201L is confirmed (step S703).

  Here, at the point t3 shown in FIG. 18 (a), if the judgment result that the state of the mirror surface 11-1L is abnormal is sent from the first mirror surface cooling type dew point meter 201L (step). (NO in S704), the dew point meter control mode designating unit 301 sends a switching command to the first mirror-cooled dew point meter 201L so as to shift the control mode to the automatic cleaning control mode (step S705). A switching command is sent to the mirror-cooled dew point meter 201R so as to shift the control mode to the dew point temperature measurement control mode (step S706).

  If a determination result indicating that the state of the mirror surface 11-1L is normal is sent from the first mirror-cooled dew point meter 201L (YES in step S704), the dew point temperature measurement value selection unit 302 is The dew point temperature measurement value tx1 from the mirror surface cooling type dew point meter 201L is taken in and output as a measurement result of the dew point temperature measurement system (step S707).

  The control mode selection unit 37L of the first specular cooling type dew point meter 201L receives the switching command to the automatic cleaning control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode to the dew point temperature until then. Switching from the measurement control mode to the automatic cleaning control mode (point t3 shown in FIG. 18A). In other words, the dew point temperature measurement control up to that point is stopped, and the process shifts to automatic cleaning control.

  On the other hand, the control mode selection unit 37R of the second mirror-cooled dew point meter 201R receives the switching command to the dew point temperature measurement control mode from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode until then. The automatic cleaning control mode is switched to the dew point temperature measurement control mode (point t3 shown in FIG. 18B). That is, the automatic cleaning control up to that point is stopped and the process proceeds to dew point temperature measurement control.

  The control mode selection unit 37L of the first mirror-cooled dew point meter 201L performs automatic cleaning control by the automatic cleaning control unit 36L. In this case, as the automatic cleaning control, automatic cleaning of the mirror surface 11-L is periodically performed, and the mirror surface abnormal state determination unit 35L determines whether the mirror surface 11-1L after the cleaning is normal or abnormal. The mirror surface abnormal state determination unit 35L notifies the overall controller 300 of the normal / abnormal determination result (step S609).

  Based on the recognition result from the dew point meter current control mode recognition unit 303, the dew point meter control mode designating unit 301 of the overall controller 300 determines the current control of the first specular cooling type dew point meter 201L and the second specular cooling type dew point meter 201R. The mode is confirmed (step S701). In this case, since the current control mode of the first specular cooling type dew point meter 201R is not dew point temperature measurement control (NO in step S702), the first specular cooling type is determined based on the recognition result from the specular state determination result recognition unit 304. The state of the mirror surface 11-1L of the dew point meter 201L is confirmed (step S708).

  Here, at the time point t5 shown in FIG. 18, if a determination result indicating that the state of the mirror surface 11-1R has returned to normal is sent from the first mirror surface cooling type dew point meter 201L (YES in step S709). The dew point meter control mode designating unit 301 sends a switching command to the second mirror-cooled dew point meter 201R so as to shift the control mode to the automatic cleaning control mode (step S710), and the first mirror-cooled dew point is designated. A switching command is sent to the total 201L so as to shift the control mode to the dew point temperature measurement control mode (step S711).

  If a determination result indicating that the state of the mirror surface 11-1L is abnormal is sent from the first mirror-cooled dew point meter 201L (YES in step S709), the dew point temperature measurement value selection unit 302 receives the second result. The dew point temperature measurement value tx2 from the mirror surface cooling type dew point meter 201R is taken in and output as a measurement result of the dew point temperature measurement system (step S712).

  The control mode selection unit 37L of the first mirror-cooled dew point meter 201L receives a control mode switching command from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode from the automatic cleaning control mode so far. Switch to the dew point temperature measurement control mode (point t5 shown in FIG. 18A). That is, the automatic cleaning control so far is stopped and the dew point temperature measurement control is restored.

  On the other hand, the control mode selection unit 37R of the second mirror-cooled dew point meter 201R receives the control mode switching command from the dew point meter control mode designating unit 301 of the overall controller 300, and changes the control mode to the previous dew point temperature measurement. The control mode is switched to the automatic cleaning control mode (point t5 shown in FIG. 18B). That is, the conventional dew point temperature measurement control is stopped and the automatic cleaning control is resumed.

  In this way, in this operation method 2, first, the first mirror-cooled dew point meter 201L is used as an initial measurement dew point meter (main dew point meter (dew point meter that performs dew point temperature measurement control)). The second mirror-cooled dew point meter 201R is set as an auxiliary dew point meter (sub dew point meter (dew point meter that executes automatic cleaning control)) at the beginning of operation, and every time an abnormality occurs in the main dew point meter. In addition, only when the main dew point meter is abnormal, that is, until the main dew point meter returns to the normal state by the automatic cleaning control, the sub dew point meter is switched to the dew point temperature measuring control. There is no period of stoppage, and the dew point temperature can be measured continuously.

  In the above-described embodiment, the automatic cleaning control in both the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R is a heating control system that heats the mirror surface. It is good also as a pressure reduction control system which depressurizes pressure, and it is good also considering either one as a heating control system and the other as a pressure reduction control system.

  In the above-described embodiment, the gate valve 33 (33L, 33R) is provided on the upstream side of the sampling chamber 31 (31L, 31R), the suction pump 34 (34L, 34R) is provided on the downstream side, and the gate valve 33 ( 33L, 33R) is opened, and the suction pump 34 (34L, 34R) is operated to allow the gas to be measured to flow into the sampling chamber 31 (31L, 31R). However, the suction pump is not provided. In addition, the configuration may be such that the gas to be measured flows into the sampling chamber 31 (31L, 31R) by increasing the pressure on the upstream side. In such a configuration, for example, a valve is provided above and downstream of the sampling chamber 31 (31L, 31R), a pump for pressure reduction is provided near the sampling chamber 31 (31L, 31R), and a valve upstream and downstream is provided. It is possible to reduce the pressure in the sampling chamber 31 (31L, 31R) by closing and operating the pressure reducing pump.

  In the embodiment described above, the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R are installed in parallel, but may be installed in series. FIG. 21 shows a configuration example when the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R are installed in series. When they are installed in series, the automatic cleaning control in the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R is a heating control method.

  Further, in the above-described embodiment, the overall controller 300 is provided for the first mirror-cooled dew point meter 201L and the second mirror-cooled dew point meter 201R. The mirror-cooled dew point meter 201L or the second mirror-cooled dew point meter 201R may be provided.

  The dew point temperature measurement system of the present invention is a dew point temperature measurement system that uses a mirror-cooled dew point meter using a thermoelectric cooling element (Peltier element), and continuously determines the dew point temperature from dew condensation or frost generated on the mirror surface of the mirror. It can be used as a dew point meter to detect.

  201 (201L, 201R): mirror-cooled dew point meter, 201A: sensor unit, 201B ... control unit, 2 ... second thermoelectric cooling element (Peltier element), 2-1 ... cooling surface, 2-2 ... heating surface, DESCRIPTION OF SYMBOLS 11 ... Mirror, 11-1 ... Front surface (mirror surface), 11-2 ... Back surface, 12 ... 2nd temperature sensor, 13 ... Sensor body, 13a ... Tip part, 13b ... Inclined surface, 13c ... Rear end part, 14 ... Optical fiber integrated with light emitting and receiving, 14-1... Optical fiber on the light projecting side, 14-2... Optical fiber on the light receiving side, 15... Cooling block, 16. Thermoelectric cooling element (Peltier element), 18-1 ... cooling surface, 18-2 ... heating surface, 19 ... heat sink, 19a ... radiating fin, 20 ... cooling fan, 21 ... second temperature sensor, 22 ... photoelectric converter, 23 ... Outside air temperature sensor, DT ... Detector, S , Subcooler, 24, main controller, 24-1, CPU, 24-2, second A / D converter, 24-3, second A / D converter, 24-4, dew point temperature output unit, 24 -5 ... RAM, 24-6 ... ROM, 25 ... sub-controller, 25-1 ... CPU, 25-2 ... second A / D converter, 25-3 ... second A / D converter, 25- 4 ... RAM, 25-5 ... ROM, 26 ... power supply, 27 ... power switch, 28 ... dew point measurement ON / OFF switch, 29 ... subcooler control ON / OFF switch, 30 ... subcooler low temperature / high temperature / interlocking selector switch, 31 (31L, 31R) ... Sampling chamber, 33 (33L, 33R) ... Gate valve, 34 (34L, 34R) ... Suction pump, 300 ... General controller, 34 (34L, 34R) ... Dew point temperature measurement control , 35 (35L, 35R) ... automatic cleaning control unit, 36 (36L, 36R) ... mirror state determination unit, 37 (37L, 37R) ... control mode selection unit, 301 ... dew point meter control mode designation unit, 302 ... dew point temperature Measurement value selection unit, 303 ... dew point meter current control mode recognition unit, 304 ... specular state determination result recognition unit.

Claims (8)

A mirror surface exposed to the gas to be measured;
A thermoelectric cooling element for cooling the mirror surface;
A temperature sensor for detecting the temperature of the mirror surface;
A light projecting means for irradiating the mirror surface with light;
A light receiving means for receiving a reflected light of the light emitted from the light projecting means to the mirror surface;
Control means for controlling the current supplied to the thermoelectric cooling element based on the amount of reflected light received by the light receiving means,
The control means includes
Based on the amount of reflected light received by the light receiving means, the current supplied to the thermoelectric cooling element is controlled to be in an equilibrium state where there is no increase or decrease in condensation or frost generated on the mirror surface, and in the equilibrium state, the temperature sensor Means for performing dew point temperature measurement control for measuring the temperature of the mirror surface detected by as a dew point temperature;
Means for executing normal / abnormal judgment of the state of the mirror surface based on the amount of reflected light received by the light receiving means;
Automatic cleaning that would be attached to the mirror surface , usually a gas, contained in the gas to be measured, becomes a solid at a temperature lower than the dew point temperature, and removes condensed substances that contaminate the mirror surface by evaporation or sublimation A dew point temperature measuring system having first and second mirror-cooled dew point meters with means for performing control,
The first mirror-cooled dew point meter is set as a dew point meter for initial measurement,
The second mirror-cooled dew point meter is set as an auxiliary dew point meter at the beginning of operation,
The first mirror-cooled dew point meter is
When the dew point temperature measurement control is always executed, the dew point temperature measurement control is periodically interrupted to determine normality / abnormality of the mirror surface state, and when the mirror surface state is determined to be abnormal, Stop temperature measurement control, shift to automatic cleaning control,
The second mirror-cooled dew point meter is
The automatic cleaning control is always executed, and when the first mirror-cooled dew point meter shifts to the automatic cleaning control, the automatic cleaning control is stopped and the dew point temperature measurement control is shifted to. Dew point temperature measurement system. In the dew point temperature measurement system according to claim 1,
The second mirror-cooled dew point meter is
After the transition to the dew point temperature measurement control, the dew point temperature measurement control is periodically interrupted to determine normality / abnormality of the mirror surface state, and when the mirror surface state is determined to be abnormal, Stop temperature measurement control, return to the automatic cleaning control,
The first mirror-cooled dew point meter is
After the transition to the automatic cleaning control, when the second mirror-cooled dew point meter returns to the automatic cleaning control, the automatic cleaning control is stopped and the dew point temperature measurement control is resumed. Dew point temperature measurement system. In the dew point temperature measurement system according to claim 1,
The first mirror-cooled dew point meter is
After transitioning to the automatic cleaning control, normal / abnormal determination of the mirror surface state is periodically performed. When the mirror surface state is determined to be normal, the automatic cleaning control is stopped and the dew point temperature measurement is performed. Return to control,
The second mirror-cooled dew point meter is
After the transition to the dew point temperature measurement control, when the first mirror-cooled dew point meter returns to the dew point temperature measurement control, the dew point temperature measurement control is stopped and the automatic cleaning control is resumed. Dew point temperature measurement system. In the dew point temperature measurement system according to any one of claims 1 to 3,
The first and second mirror-cooled dew point meters are
When the dew point temperature measurement control is periodically interrupted to determine whether the mirror surface is normal or abnormal,
After the interruption of the control of the current supplied to the thermoelectric cooling element by the dew point temperature measurement control, the amount of the reflected light is determined in advance based on the amount of the reflected light received by the light receiving means after a predetermined time has elapsed since the interruption. A dew point temperature measurement system, wherein the mirror surface state is determined to be abnormal when the received light amount is out of a reference range. In the dew point temperature measurement system according to any one of claims 1 to 3,
The first and second mirror-cooled dew point meters are
When the dew point temperature measurement control is periodically interrupted to determine whether the mirror surface is normal or abnormal,
After interruption of control of the current supplied to the thermoelectric cooling element by the dew point temperature measurement control, the reflected light is based on the amount of reflected light received by the light receiving means when it is determined that the temperature of the mirror surface no longer changes. The dew point temperature measurement system is characterized in that when the amount of light deviates from a predetermined received light amount reference range, the mirror surface state is determined to be abnormal. In the dew point temperature measurement system according to any one of claims 1 to 3,
The first and second mirror-cooled dew point meters are
When the dew point temperature measurement control is periodically interrupted to determine whether the mirror surface is normal or abnormal,
The amount of reflected light received by the light receiving means when it is determined that there is no change in the amount of reflected light received by the light receiving means after interruption of control of the current supplied to the thermoelectric cooling element by the dew point temperature measurement control The dew point temperature measurement system is characterized in that, when the amount of reflected light deviates from a predetermined received light amount reference range, the mirror surface state is determined to be abnormal. In the dew point temperature measurement system according to any one of claims 1 to 3,
At least one of the first and second mirror-cooled dew point meters is
As the automatic cleaning control,
A dew point temperature measurement characterized by controlling a current supplied to the thermoelectric cooling element so as to raise a temperature of the mirror surface in order to evaporate or sublimate and remove condensate that may adhere to the mirror surface. system. In the dew point temperature measurement system according to any one of claims 1 to 3,
At least one of the first and second mirror-cooled dew point meters is
The mirror surface, the thermoelectric cooling element, the temperature sensor, the light projecting means, and a chamber that houses the light receiving means, at least,
As the automatic cleaning control,
A dew point temperature measurement system, wherein the pressure in the chamber is controlled to be reduced in order to evaporate or sublimate and remove condensate that may adhere to the mirror surface.