JPH0629797B2 - Multi-point temperature measuring device with fluid resistance thermometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention utilizes a change in state due to the temperature of a fluid to measure, for example, the temperature in a furnace or the temperature of a molten metal by a fluid resistance thermometer for multipoint temperature measurement. It relates to the device.

(Prior art and its problems) Conventionally, a thermocouple, a resistance thermometer, or the like is generally used for measuring the temperature of a molten metal or a high temperature portion such as a furnace. However, these thermometers are, in principle, limited in the material of the temperature sensing part that is exposed to high temperatures, so it is difficult to take measures against oxidation and other causes that shorten the life, and are not suitable for long-term use. there were.

Therefore, a fluid resistance type temperature measuring device has been developed which has an advantage that the material of the sensor which is the temperature sensing unit is not restricted by the principle of measurement and can be freely selected from the viewpoint of life. This fluid resistance type temperature measuring device utilizes the temperature dependence of the viscosity coefficient of gas and tries to know the temperature from the change in pressure loss when the gas passes through a capillary tube, and its basic configuration is the tenth. As shown in the figure, the working fluid such as Ar gas is supplied from the working fluid supply source 11 via the pressure control device 31 at a constant pressure, and the pressure of the capillary tube 2 in the probe 1 generated corresponding to the temperature of the atmosphere to be measured. Loss Δ
P is a pressure difference ΔPc between the secondary side of the trim valve 32 and the secondary side of the capillary tube 2, amplified by the fluid element 33, and detected by the pressure sensor 34 as an electric signal.

Electrically speaking, the configuration of this system is a kind of Wheatstone bridge, and a slight fluctuation of the pressure loss in the sensitivity adjustment valve 35, the supply valve 36, or the trim valve 32 is large in the pressure signal from the fluid element 33. affect. Therefore, a change in the state of the working fluid due to the ambient temperature causes a change in the pressure loss in each of the valves 32, 35 and 36, and apparently as a change in the pressure loss ΔP of the capillary 2 of the probe 1, that is, a change in the temperature measured by the plow 1. As will be appreciated, this type of thermometer has the drawback of being susceptible to ambient temperature.

Further, when controlling the temperature in the furnace, etc., it is usual to simultaneously measure at a plurality of points in the furnace. Therefore,
When the fluid resistance type temperature measuring device 30 shown in FIG. 10 is used as a multi-point temperature measuring device, the configuration thereof is as shown in FIG.
It is conceivable that the working fluid supply source 11 and the pressure control device 31 shown in FIG. 0) are shared and connected in parallel. However, by configuring in this way, there are some new and different problems other than the above-mentioned drawbacks. The problem arises.

First, the first problem is that the environmental temperature depends on the installation positions of the supply valve 36, the sensitivity adjustment valve 35, and the trim valve 32 that causes the reference pressure loss on the upstream side of each probe. This means that the temperature measurement error differs depending on the measurement point, that is, the temperature measurement error differs depending on each measurement point, and correction is virtually impossible.

The second problem is the working fluid supply source 11 and the pressure control device 31.
Since the working fluid has a long pipe until it reaches each probe 1, the working fluid causes a pressure fluctuation due to the influence of the environmental temperature in the middle of the piping, and the working fluid having a constant pressure cannot be supplied to each probe. That is. That is, the temperature measurement error increases due to this phenomenon.

The third problem is that, as shown in FIG. 12, by providing the correction pressure control device 31a immediately before being supplied to each temperature sensor unit, the pressure fluctuation in the middle of the pipe is suppressed and the pressure is kept constant in each probe. It is possible to supply the working fluid, but since the pressure fluctuation on the primary side of the correction pressure control device 31a installed immediately before the unit is large, sufficient pressure control cannot be performed by the device 31a. Even in the device configuration shown in the figure, the temperature measurement error becomes large, and the pressure control device is required for the number of measurement points, which causes a cost increase.

The fourth problem is that in a multi-point temperature measuring device as shown in FIGS. 11 and 12, since a large number of temperature sensor units are connected in parallel after the working fluid supply source 11, the working fluid for each unit is It is necessary to supply at a constant pressure, and the consumption increases proportionally as the number of measurement points increases.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems,
It is an object of the present invention to provide a multi-point temperature measuring device using a fluid resistance type thermometer which enables continuous temperature measurement at a plurality of temperature parts efficiently using a working fluid with good accuracy.

(Structure of the Invention) In order to achieve the above object, the present invention provides a plurality of probes in which an inner cylinder having a narrowed portion at the tip is inserted into an outer cylinder whose one end is sealed, and these probes. Connected in series and connected to the first-stage probe, a working fluid supply pipe equipped with a pressure control device and a mass flow control device in sequence, and provided for each probe to detect pressure loss at the throttle section. And a temperature calculation means for calculating the temperature based on the signal from the differential pressure gauge.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a multi-point temperature measuring device using a fluid resistance thermometer according to a first embodiment of the present invention, and in this embodiment, five probes 1 which are temperature-sensitive sensors are provided. And the second
As shown in the figure, the probe 1 has passed through the capillary tube 2 which is a form of a throttle portion, an inner cylinder 4 which forms a working fluid supply channel 3 for guiding a working fluid to the capillary tube 2, and a capillary tube 2. An outer cylinder 6 that forms a working fluid discharge flow path 5 for discharging the working fluid to the outside of the probe 1, and as an example, penetrates the furnace wall 7 and projects into the furnace to measure the temperature inside the furnace. I am doing it. Further, each probe 1 has a working fluid discharge port 8 that is an outlet portion of the outer cylinder 6 of the probe 1 on the lower stage side.
Is connected in series so as to continue to the working fluid supply port 9 which is the inlet of the inner cylinder 4 of the probe 1 on the higher stage side adjacent thereto, and to the working fluid supply port 9 of the probe 1 of the first stage. Is connected to a working fluid supply pipe 10. That is, the working fluid supply pipe 11 is supplied from the working fluid supply source 11 via the pressure reducing valve 12, the pressure control valve 13, and the mass flow controller 14.
Thus, the working fluid having a constant mass flow rate can be supplied to the inner cylinder 4 of the first stage probe 1.

Furthermore, the pressure loss Δ in the capillary tube 2 in each probe 1
In order to directly detect P, a pressure detection pipe 15 is provided at the working fluid supply port 9 and the working fluid discharge port 8 of each probe 1 and is connected to the differential pressure gauge 16 as well as each differential pressure gauge 16 The pressure signal is connected to the temperature calculation means 17.

Next, temperature measurement by the device having the above configuration will be described.

First, a working fluid such as Ar gas is supplied from the working fluid supply source 11. The supplied working fluid is reduced to a predetermined pressure by the pressure reducing valve 12 and the pressure control valve 13, and at the same time,
The pressure is controlled to be kept constant, and in this state, the mass flow rate controller 14 supplies a constant mass flow rate Q to the working fluid supply port 9 of the first stage probe 1.

The working fluid supplied to the working fluid supply port 9 at a constant mass flow rate Q passes through the capillary 2 and the working fluid discharge port 8 of the probe 1.
Emitted from.

At this time, since the resulting pressure loss [Delta] P ₁ in the capillary tube 2, the pressure loss [Delta] P ₁ detected by the differential pressure gauge 16, the location where the probe 1 is provided at a temperature calculation means 17 based on the detection value The ambient temperature T ₁ is calculated.

Then, the working fluid discharged from the working fluid discharge port 8 of the probe 1-1 is supplied to the working fluid supply port 9 of the second stage probe 1-2, passes through the capillary tube 2 of the probe 1-2, and then the probe 1 -2 is discharged from the working fluid discharge port 8.

Also in this case, the pressure loss ΔP is caused by the capillary tube 2 of the probe 1-2.
₂ is generated, and from this pressure loss ΔP ₂ , the atmospheric temperature T _{2 of the} place provided in the probe 1-2 is obtained similarly to the probe 1-1.

After that, in the final stage probe 1, that is, in the embodiment,
This is repeated until the probe 1-5 in the fifth stage passes through the capillary tube 2.

The working fluid that has passed through each probe 1 is finally discharged to the atmosphere through the working fluid discharge port 8 of the probe 1-5 in the fifth stage.

By the way, since the flow of each probe 1-1 to 1-5 in the capillary tube 2 can be generally assumed to be Hagen-Poiseuille flow, the pressure loss generated in the capillary tube 2 is expressed by the following equation.

However, l and d indicate the length and inner diameter of the capillary, respectively, and μ (T) and (T) indicate the viscosity coefficient and density of the working fluid at the temperature T in the furnace. Further, Q indicates the mass flow rate of the working fluid, which is a constant because the mass flow rate controller 13 controls the mass flow rate to be constant.

Strictly speaking, the length l or the inner diameter d of the capillary tube 2 is also affected by the temperature. Considering this, the kinematic viscosity ν of the working fluid
Since (T) is ν (T) = μ (T) / ρ (T), the equation (1) can be rewritten as follows.

Therefore, it can be seen that ΔP is a function of the furnace temperature T.

In general, the temperature dependence of l and d is often smaller than that of ν (T), so Can be expressed as From this equation (3), it can be said that the pressure loss ΔP generated in the capillary tube 2 is proportional to the kinematic viscosity ν (T) of the working fluid when passing through the capillary tube 2. Working fluid kinematic viscosity ν
Since (T) is a function of temperature, the pressure loss ΔP is
Of the working fluid when passing through the furnace, that is, the temperature T in the furnace
Is a function of.

Therefore, no matter what is expressed by the equations (2) and (3), if the pressure loss ΔP generated in each capillary tube 2 is measured,
The temperature T in the furnace can be known.

As described above, the pressure loss ΔP in the capillary tube 2 according to the present device configuration depends only on the temperature of the working fluid passing therethrough. Therefore, the working fluid is not affected by the temperature, pressure history, material, material, shape, material environmental temperature, atmospheric pressure, etc. of the working fluid before entering the probe.

That is, even if the probe 1 has passed through a plurality of probes before, it is not affected at all when it passes through the next probe, and it is possible to accurately measure the temperature, and the probe 1 is installed at a position necessary for the measurement. If this is done, the temperature measurement for only the number of probes will be continuously performed.

FIG. 3 shows a multi-point thermometer side device according to a second embodiment of the present invention, in which a probe 1 having an arbitrary shape that suits the temperature measurement location of an object to be measured or the like, that is, a dissimilar substance, a dissimilar shape Probe 1 ((a), (b), (c) in the figure are also shown to distinguish different types) and capillary tube 2 ((x), (y) in the figure are shown for different types) Are connected in series to measure the temperature at each measurement point. In this case, the probe 1
By grasping the various characteristics of (a), 1 (b), 1 (c) in advance, the temperature based on each pressure loss generated in those capillaries 2 (x), 2 (y) as described above The temperature can be calculated and calculated by the calculation means 17.

FIG. 4 shows a multi-point temperature measuring device according to a third embodiment of the present invention, and a resistance means for producing a large flow resistance such as a silencer at the working fluid discharge port 8 of the probe 1-5 at the final stage. 18 are connected.

FIG. 5 shows a multipoint temperature measuring device according to a fourth embodiment of the present invention, in which an accumulator 19 for temporarily storing the working fluid to be discharged is provided as the resistance means 18.

In the third and fourth embodiments, hunting is less likely to occur in the output of the present apparatus even when the environmental pressure at the installation location of the present apparatus, that is, the atmospheric pressure changes significantly. Regarding this hunting prevention measure, as in the third and fourth embodiments, in addition to physically suppressing it, an electric signal is taken out from the differential pressure gauge 16 and passed through a filter circuit to be electrically removed. May be

Further, FIG. 6 shows a multipoint temperature measuring device according to a fifth embodiment of the present invention, in which the three-way switching valve 20, the on-off valves 21, 22 are provided in the working fluid supply pipe after the mass flow controller 14 of the first embodiment. ,
And the bypass piping 23 is provided.

For example, according to the apparatus configuration of FIG. 6, even if the second stage probe 1-2 is damaged or only the second stage probe 1-2 is intentionally discontinued during the multipoint temperature measurement, Therefore, the temperature measurement can be continued without affecting the probes 1-1, 1-3, 1-4, 1-5.

That is, the valves 21-1, 22-1, 21-3, 22-3, 2
Open 1-4, 22-4, 21-5, valves 21-2, 22-2
Is closed, and the three-way switching valve 20-1's A-B port, 20-2's B-C port, and 20-3's A-B port are opened, and the three-way switching valves 20-4, 20-5 are opened. By closing, the working fluid supplied at a constant mass flow rate
It will flow sequentially to the probes 1-1, 1-3, 1-4, 1-5. Therefore, with the device configuration as in the fifth embodiment, even if there is a damaged probe or a probe at a place where measurement is not necessary, other probes are not affected by the influence and the temperature is continuously measured. You can continue.

3 to 6 are substantially the same as FIG. 1 except for the above-mentioned portions, and the portions corresponding to each other are designated by the same reference numerals and the description thereof will be omitted.

Further, the present invention may be provided with a probe breakage detecting means 24a for detecting breakage of the probe 1 as shown in FIG. The damage detecting means 24a is composed of a differential circuit 25, a comparison operation processing circuit 26a, and an alarm means 27 connected in series. Of these, the differential circuit 25 is connected to the differential pressure gauge 16 and the pressure loss value measured by the differential pressure gauge 16 is measured. The damage of the probe 1 is detected from the changing speed of ΔP. That is, when the damaged portion 28 is generated in the probe 1, a gas flow occurs inside the probe 1 (indicated by a practice arrow in the figure) or outside the probe 1 (indicated by a practice arrow in the figure), and the differential pressure gauge 16 operates. The measured pressure loss value ΔP rapidly changes. The rate of change of the measured pressure loss value ΔP is extremely faster than the measured pressure loss value corresponding to the fluctuation of the temperature in the furnace.

Therefore, the signal of the pressure loss ΔP is time-differentiated by the differentiating circuit 25 to obtain the change speed (dΔP / dt) of the pressure loss ΔP, which is compared with the set reference fluctuation speed by the comparison calculation processing circuit 26a to obtain the pressure loss. When the changing speed of ΔP is higher, an abnormal signal is issued and the alarm means 27 issues an alarm. If this is expressed by a mathematical formula, However, ΔPmax: pressure loss value corresponding to the upper limit temperature Tmax of the temperature measuring range of the fluid resistance temperature measuring device ΔPmin: pressure loss value corresponding to the lower limit temperature Tmin of the temperature measuring range of the fluid resistance temperature measuring device t ₂ : furnace When the internal temperature fluctuates instantaneously from Tmax to Tmin, if the equation (1) of the time required for the temperature of the working fluid to reach Tmin is satisfied, an alarm is given that the probe 1 is damaged.

The probe breakage detecting means 24a detects breakage from the change in the pressure loss fluctuation speed of the differential pressure gauge 16, but in addition to this, the fluctuation speed of the calculated temperature obtained by the calculator 17 Of the fluid resistance type temperature measuring device, and calculates the rate of change between the upper limit temperature Tmax and the lower limit temperature Tmin of the temperature control range of the fluid resistance type temperature measuring device. The damage of the probe 1 may be detected by comparing with the above. That is, If the above two expressions are established, an alarm is issued as damage to the probe 1.

Further, FIG. 8 shows a structure in which the breakage of the probe 1 is detected from the change in the mass flow rate of the working fluid.
Mass flowmeter 29 for measuring the mass flow rate of the working fluid on the discharge side of the working fluid, the comparative calculation processing circuit 26b, and the alarm means 27.
It consists of Then, based on the signals from both mass flowmeters 14 and 29, the comparison calculation processing circuit 26b compares the mass flow rates of the working fluid supplied to the probe 1 and the working fluid discharged from the probe 1, and If the two do not match, an abnormal signal is issued and the alarm means 27 issues an alarm.

As described above, in any of the probe breakage detecting means 24a, 24b shown in FIG. 7 and FIG. 8, when the breakage of the probe 1 is detected, a signal from the comparison operation processing circuits 26a, 26b causes the above-mentioned FIG. The on-off valves 21 and 22 and the three-way switching valve 20 shown in FIG.

Furthermore, the present invention is not limited to the above, and may be a combination of a plurality of various probe damage detecting means, and as an example, FIG. 9 shows the probe damage detecting means shown in FIG. 7 and FIG. The probe breakage detecting means 24c is provided so that the three-way switching valve 20 and the valves 21 and 22 are operated so that the working fluid does not flow to the abnormal probe when the abnormalities are abnormal.

In each of the above embodiments, the working fluid is shown to flow from the inner cylinder 4 to the outer cylinder 6 (however,
7 to 9 show the flow direction is opposite. )
The present invention is not limited to this, and includes one in which the working fluid is caused to flow in the direction from the outer cylinder 6 to the inner cylinder 4, and in this case also, the temperature can be measured in the same manner as described above.

Needless to say, when the flow is reversed, the inner cylinder 4 is connected to the working fluid supply side pipe and the outer cylinder 6 is connected to the discharge side pipe.

(Effects of the Invention) As is apparent from the above description, according to the present invention, a plurality of probes in which an inner cylinder having a narrowed portion at the tip is inserted into an outer cylinder whose one end is sealed, and these probes A probe connected in series and connected to the first-stage probe, and a working fluid supply pipe provided with a pressure control device and a mass flow control device in sequence, and a pressure loss in the throttling portion provided for each probe. And a temperature exchange means for converting a signal from the differential pressure gauge into a temperature.

For this reason, the working fluid supplied to the probe always flows at a constant mass flow rate, and the ambient temperature,
With good accuracy without being affected by the working fluid temperature,
In addition, the working fluid can be efficiently used to perform continuous measurement at a plurality of high temperature portions.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-point temperature measuring device using a fluid resistance thermometer according to a first embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of a probe, and FIGS. FIG. 6 is a block diagram of a multipoint temperature measuring device using a fluid resistance thermometer according to the second, third, fourth and fifth embodiments of the present invention, and FIG. 7, FIG. 8, FIG. FIG. 10 is a partial block diagram of a probe breakage detecting means applied to the present invention, FIG. 10 is a block diagram of a conventional fluid resistance type temperature measuring device, and FIGS. 11 and 12 are multipoint temperatures by a conventional fluid resistance type thermometer. It is a block diagram of a measuring device. 1a, 1b, 1c ... probe, 2 ... capillary tube, 4 ... inner tube, 6
...... Outer cylinder, 10 ...... Working fluid supply pipe, 13 ...... Pressure control valve, 14 ...... Mass flow control device, 15 ...... Pressure detection pipe,
16 ... Differential pressure gauge, 17 ... Temperature calculation means.

Claims (1)

[Claims] 1. A plurality of probes in which an inner cylinder having a narrowed portion at the tip is inserted into an outer cylinder whose one end is sealed, and these probes are connected in series, and a first-stage probe is provided. Connected, working fluid supply pipe equipped with a pressure control device and a mass flow control device in sequence, and provided for each probe,
A multi-point temperature measuring device using a fluid resistance thermometer, comprising: a differential pressure gauge for detecting a pressure loss in the throttle portion; and a temperature calculating means for calculating a temperature based on a signal from the differential pressure gauge.