Fluid temperature measurement system and fluid temperature measurement method

Abstract

The object of the present invention is to provide a fluid temperature measurement system and a fluid temperature measurement method that can measure the fluid temperature inside a pipe without requiring pipe construction work or prior preparation of correlation graphs, and that can guarantee the accuracy of the measured temperature. [Solution] The fluid temperature measurement system of the present invention is a fluid temperature measurement system for measuring the fluid temperature inside a pipe through which liquid or steam flows, and is characterized by comprising: a heat flux control unit positioned on the opposite side of the pipe from a temperature sensor and a heat flux sensor installed on the outer surface of the pipe, which controls the heat flux on the outer surface of the pipe to within a target value range; an internal fluid temperature calculation unit which calculates the internal fluid temperature from the output values ​​of the temperature sensor and the heat flux sensor; and a measurement accuracy calculation unit which calculates the measurement accuracy of the internal fluid temperature from the measurement accuracy of the temperature sensor and the measurement accuracy or setting accuracy of the heat flux sensor.

Description

[Technical Field]

[0001] This invention relates to a fluid temperature measurement system and a fluid temperature measurement method. [Background technology]

[0002] In power plants that utilize the steam cycle, such as nuclear and thermal power plants, steam generated in the reactor and boiler is sent to a steam turbine to efficiently convert thermal energy into electrical energy. The main components of the steam cycle are the reactor and boiler, steam turbine, condenser, and feedwater pump, but it also includes various other systems such as auxiliary equipment and seawater cooling systems that cool the auxiliary equipment with seawater. Traditionally, plant function has been maintained by regularly maintaining major components such as pumps and heat exchangers, but in recent years, maintenance has been shifting to focus on the system functions of each system, such as the cooling water supply function. Therefore, it is necessary to quantitatively evaluate the system status during plant operation, and the importance of sensing with instruments is increasing.

[0003] While major systems such as reactor systems are equipped with numerous standard design instruments, allowing for system condition monitoring using these instruments, auxiliary systems often have fewer standard design instruments, making system condition evaluation difficult. Therefore, additional instruments are necessary. For example, adding a thermometer to measure internal fluid temperature requires shutting down the system, draining the water, and welding a thermometer protection tube to the piping, which is a laborious process. Seawater cooling systems, in particular, operate even when the plant is shut down, and the addition of instruments has a significant impact on the overall plant operation and maintenance plan.

[0004] Given the above background, there is a growing need for a preliminary design device that can perform sensing easily without shutting down the system. In particular, internal fluid temperature is the most important parameter for verifying system function. Furthermore, when quantitatively evaluating system function, it is also an important requirement to be able to guarantee the measurement accuracy of the measured temperature.

[0005] In Patent Document 1, a method for measuring the fluid heat quantity that can accurately grasp the temperature of the fluid flowing in a pipe without accompanying pipe work while the fluid is flowing in the pipe is disclosed. For each pipe with a different diameter, a correlation graph is prepared in advance with the horizontal axis being the difference between the indoor temperature and the pipe surface temperature and the vertical axis being the difference between the fluid temperature in the pipe and the pipe surface temperature. After that, the pipe surface temperature and the indoor temperature are measured to obtain the difference between the pipe surface temperature and the indoor temperature, and the fluid temperature in the pipe is estimated through the correlation graph.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In Patent Document 1, in order to estimate the fluid temperature in the pipe from the measured values of the pipe surface temperature and the indoor temperature, a previously prepared correlation graph is required. However, in the existing plant auxiliary equipment system targeted by the present invention, a thermometer for measuring the fluid temperature in the pipe is not installed, and a correlation graph cannot be created. In the performance confirmation test before the start of plant operation, the fluid temperature in the pipe may be measured by a provisional device, but the number of data is small, and a sufficient number of data required for creating a correlation graph cannot be obtained. [[ID=XXX]] [[ID=XXX]]

[0008] [[ID=XXX]] Also, in seawater pipes or pipes containing non-clean fluids, dirt and scale adhere to the inner surface of the pipe over time, increasing the thermal resistance and changing the correlation between the pipe surface temperature and the fluid temperature in the pipe. Therefore, the measurement accuracy of the internal fluid temperature cannot be guaranteed by the previously prepared correlation graph.

[0009] An object of the present invention is to provide a fluid temperature measurement system and a fluid temperature measurement method that can measure the fluid temperature inside a pipe without requiring pipe work or prior preparation of a correlation graph and can guarantee the accuracy of the measured temperature. [Means for solving the problem]

[0010] The fluid temperature measurement system of the present invention is a fluid temperature measurement system for measuring the fluid temperature inside a pipe through which liquid or steam flows, and is characterized by comprising: a heat flux control unit positioned on the opposite side of the pipe from a temperature sensor and a heat flux sensor installed on the outer surface of the pipe, which controls the heat flux on the outer surface of the pipe to within a target value range; an internal fluid temperature calculation unit which calculates the internal fluid temperature from the output values ​​of the temperature sensor and the heat flux sensor; and a measurement accuracy calculation unit which calculates the measurement accuracy of the internal fluid temperature from the measurement accuracy of the temperature sensor and the measurement accuracy or setting accuracy of the heat flux sensor.

[0011] The present invention relates to a fluid temperature measurement method for measuring the fluid temperature inside a pipe through which liquid or steam flows, and is characterized by including: a surface temperature measurement step for measuring the temperature of the outer surface of the pipe; a heat flux control step for controlling the heat flux of the outer surface of the pipe to within a range of a target value; an internal fluid temperature calculation step for calculating the internal fluid temperature from the measurement result of the surface temperature measurement step and the value of the heat flux; and a measurement accuracy calculation step for calculating the measurement accuracy of the internal fluid temperature from the measurement accuracy in the surface temperature measurement step and the measurement accuracy or setting accuracy of the heat flux in the heat flux control step. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a fluid temperature measurement system and a fluid temperature measurement method that can measure the fluid temperature inside a pipe without requiring pipe construction work or prior preparation of correlation graphs, and that can guarantee the accuracy of the measured temperature. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing the configuration of the fluid temperature measurement system according to Example 1. [Figure 2] This is a view of the heat flux sensor and heat flux control unit of the fluid temperature measurement system according to Example 1, as seen from the direction of the pipe cross-section. [Figure 3]This is a test result demonstrating the effectiveness of the heat flux control unit in the fluid temperature measurement system according to Example 1. [Figure 4] This figure shows an example of the display unit of the fluid temperature measurement system according to Example 1, illustrating a state in which the internal fluid temperature has been measured correctly. [Figure 5] This figure shows an example of the display unit of the fluid temperature measurement system according to Example 1, illustrating a situation where the internal fluid temperature is not measured correctly and a review of the heat flux control unit is necessary. [Figure 6] This is a diagram showing the configuration of the fluid temperature measurement system according to Example 2. [Figure 7] This is a view of the heat flux sensor and heat flux control unit of the fluid temperature measurement system according to Example 2, as seen from the pipe cross-sectional direction. [Figure 8] This is a diagram showing the configuration of the fluid temperature measurement system according to Example 3. [Figure 9] This is a view of the heat flux sensor and heat flux control unit of the fluid temperature measurement system according to Example 3, as seen from the pipe cross-sectional direction. [Modes for carrying out the invention]

[0014] The following describes a fluid temperature measurement system and a fluid temperature measurement method for measuring the fluid temperature inside a pipe through which liquid or steam flows, using examples, text, and drawings. However, elements not directly related to the present invention are omitted from the illustrations. [Examples]

[0015] Figure 1 is a diagram of the fluid temperature measurement system targeted in Example 1. Figure 2 is a view of the heat flux sensor and heat flux control unit of the fluid temperature measurement system according to Example 1, viewed from the pipe cross-sectional direction. The fluid temperature measurement system 1 inside the pipe shown in this example is installed on the outer surface of the pipe 2 through which water, air, steam, gas, etc., flows.

[0016] The fluid temperature measurement system 1 is installed on the outer surface of the pipe and consists of a temperature sensor 3 that measures the temperature of the outer surface of the pipe, a heat flux sensor 4 that measures the heat flux, a heat flux control unit 5, and a calculation control unit 6. It is assumed that the fluid flowing through pipe 2 has a temperature relatively close to the ambient temperature and that no pipe insulation material is installed. However, even when pipe insulation material is present, the same effect as in this embodiment can be obtained by placing the temperature sensor 3, heat flux sensor 4, and heat flux control unit 5 on the outer surface of the pipe beneath the insulation material.

[0017] The temperature sensor 3 can use either a thermocouple or a resistance thermometer. Any type of thermocouple specified in the JIS standard, such as K-type, J-type, T-type, E-type, N-type, R-type, S-type, or B-type, may be used. However, from the viewpoint of durability and measurement accuracy, K-type or T-type is preferable. Furthermore, for ease of placement on the pipe surface, a sheath diameter of 1 mm or less is preferable. In addition, it is necessary to quantify the temperature measurement accuracy as it is required for calculations in the measurement accuracy calculation unit 8. It is desirable to perform a calibration test using a temperature calibrator and obtain a calibration record, but if calibration is difficult, the planned accuracy provided by the sensor supplier or the standard accuracy for each type as defined in the JIS standard can be used.

[0018] If an air layer exists between the thermocouple and the outer surface of the pipe, the outer surface temperature of the pipe cannot be measured correctly. Therefore, the thermocouple should be attached to the outer surface of the pipe from above using highly thermally conductive aluminum tape or glass tape. Alternatively, thermally conductive gel or thermally conductive clay can be applied to the tip of the thermocouple and then attached from above with aluminum tape or glass tape.

[0019] The heat flux sensor 4 can be either an epoxy glass type, which detects the heat flux by connecting multiple small thermocouples in series with an epoxy glass plate in between and using the thermoelectric voltage generated from the temperature difference between the two sides of the epoxy glass plate, or a semiconductor type, which uses a semiconductor as the thermoelectric conversion material.

[0020] As will be explained later, the accuracy of heat flux measurement affects the accuracy of internal fluid temperature measurement, so a highly sensitive sensor is required, with a measurement of 0.01 mV / (W / m). 2A heat flux sensor having the above sensitivity coefficient is desirable. If there is an air layer between the heat flux sensor 4 and the outer surface of the pipe, the heat flux cannot be measured correctly. Therefore, the heat flux sensor 4 is adhered to the outer surface of the pipe with a double-sided tape having a thickness of 0.1 mm or less whose thermal resistance can be ignored.

[0021] The heat flux control unit 5 aims to suppress the surface heat flux generated due to heat dissipation from the pipe and its variation. It is arranged on the side opposite to the pipe of the temperature sensor 3 and the heat flux sensor 4, and controls the heat flux on the outer surface of the pipe within the range of the target value. Although it is also possible to actively control the surface heat flux as described in Example 2, in Example 1, a configuration for passively controlling the surface heat flux is adopted. The heat flux control unit 5 of the present embodiment is a block-shaped member made of a material with low thermal conductivity, and has a layered structure such that the thickness H and widths W1, W2 can be changed. The material is rock wool, glass wool, calcium silicate, foamed plastic thermal insulation material, etc., which are used as thermal insulation materials. Also, as long as it is a solid substance with a thermal conductivity of 0.5 W / mK or less, other materials may be used. The thickness H is determined so as to satisfy the following formula (1).

[0022] H≧k2×[(T i -T o ) / σ q -1 / h i -t0 / k0-t1 / k1-1 / h o … (1) Here, T i is the designed pipe temperature, T o is the outside air temperature, h i is the convective heat transfer coefficient inside the pipe, and is given by an empirical formula such as the Dittus - Boelter formula or 5000 W / m 2 2 K. t0 is the lining thickness, k0 is the thermal conductivity of the lining material, t1 is the pipe wall thickness, k1 is the thermal conductivity of the pipe material, h0 is the convective heat transfer coefficient outside the pipe, and is given by an empirical formula related to the natural convective heat transfer coefficient of air or 10 W / m 2 K. k2 is the thermal conductivity of the heat flux control unit 5. σ 2 is the measurement error of the heat flux, and is obtained by the following formula (2). q

[0023] σq =σ V / C … (2) Here, σ V σ is the voltage logger accuracy of the output voltage input section of the heat flux sensor 4, and C is the sensitivity coefficient of the heat flux sensor. When a high-precision voltage logger is used, q When this becomes extremely small, H calculated from equation (1) may become larger than the pipe diameter. In that case, installation problems arise, so in equation (1), σ q Instead, the heat flux setting error S q You may use S. q This is an arbitrary value, and should be set so that H does not become excessively large. The widths W1 and W2 of the heat flux control unit 5 are determined to cover the installation areas of the heat flux sensor 4 and temperature sensor 3.

[0024] The thickness of the heat flux control unit 5 should preferably be greater than the value obtained by dividing the temperature difference between the fluid inside the pipe and the outside air by the measurement accuracy or setting accuracy of the heat flux sensor 4 and multiplying by the thermal conductivity of the block-shaped member.

[0025] To confirm the effectiveness of the heat flux control unit 5 in this embodiment, an example is shown. A verification test was conducted under conditions where the internal fluid temperature was 26°C and the ambient temperature was 22°C.

[0026] Figure 3 shows the test results demonstrating the effect of the heat flux control unit in the fluid temperature measurement system according to Example 1. It compares the surface heat flux with and without the heat flux control unit 5. In result 11 without the heat flux control unit, heat dissipation from the pipe surface, which is a factor in temperature errors, occurs, resulting in large heat flux fluctuations. However, in result 12 with heat flux control, the measurement error σ of the heat flux is reduced. q The surface heat flux is suppressed and variability is reduced as follows.

[0027] The calculation control unit 6 reads the input values ​​10 of the output voltage and measurement error from the temperature sensor 3 and the heat flux sensor 4. The calculation control unit 6 then performs various calculations and displays the internal fluid temperature, measurement accuracy, surface temperature, and surface heat flux, and has the function of indicating whether or not the heat flux control needs to be reviewed.

[0028] The internal fluid temperature calculation unit 7 receives the output value from the temperature sensor 3 and performs noise reduction by removing outliers and averaging. The internal fluid temperature calculation unit 7 calculates the internal fluid temperature from the output values ​​of the temperature sensor 3 and the heat flux sensor 4. The measurement accuracy calculation unit 8 calculates the measurement error σ of the internal fluid temperature using the following formula.

[0029] σ = √[σ T ^2+(σ q ·R)^2] … (3) σ is, σ T The square of (σ q It is the square root of the sum of the squares of (R). Here, σ T σ represents the measurement error of the temperature sensor. q S instead q When using this method, the measurement error σ of the internal fluid temperature is calculated using the following formula.

[0030] σ = √[σ T ^2+(S q ·R)^2] … (4) σ is, σ T The square of (S q It is the square root of the sum of the squares of (R). Here, R in equations (3) and (4) is the total thermal resistance from the inside of the pipe to the outside surface of the pipe, and is calculated using the following formula.

[0031] R = 1 / h i +t0 / k0+t1 / k1… (5) In this manner, the measurement accuracy calculation unit 8 calculates the measurement accuracy of the internal fluid temperature from the measurement accuracy of the temperature sensor 3 and the measurement accuracy or set accuracy of the heat flux sensor 4.

[0032] The display unit 9 receives the calculation results and displays the internal fluid temperature, measurement accuracy, surface temperature, and surface heat flux, as well as indicating whether a review of the heat flux control is necessary. The surface heat flux measured by the heat flux sensor 4 is the measurement error σ of the heat flux. q Alternatively, setting error S q If the value exceeds a certain limit, it can be determined that the heat flux is not being controlled correctly, and the user may be asked to review the heat flux control settings.

[0033] Figure 4 shows an example of the display unit of the fluid temperature measurement system according to Example 1, illustrating the state in which the internal fluid temperature is measured correctly. As shown in Figure 4, the internal fluid temperature is 60.1°C, the measurement accuracy is ±0.3°C, the surface temperature is 60.1°C, and the surface heat flux is 9 W / m 2 It displays the following and indicates that a review of the heat flux control is not necessary.

[0034] Figure 5 shows an example of the display unit of the fluid temperature measurement system according to Example 1, illustrating a state where the internal fluid temperature is not measured correctly and a review of the heat flux control unit is necessary. As shown in Figure 5, the internal fluid temperature and measurement accuracy are not displayed, and the surface temperature is 55.0°C and the surface heat flux is 400 W / m 2 It displays the information and indicates whether a review of the heat flux control is necessary.

[0035] If a request for a review of the heat flux control arises, the user shall attach a material of the same type to the heat flux control unit 5, increasing its thickness H and widths W1 and W2, and measure again. This procedure shall be repeated until the measurement results are normal. If a large-sized heat flux control unit 5 is installed in advance, it becomes difficult to handle and the risk of corrosion under the insulation material increases. Following this procedure makes it possible to measure the internal fluid temperature with the smallest possible device configuration.

[0036] The system includes a heat flux control unit 5 positioned on the opposite side of the pipe from the temperature sensor 3 and heat flux sensor 4 installed on the outer surface of the pipe, which controls the heat flux on the outer surface of the pipe to within a target range; an internal fluid temperature calculation unit 7 that calculates the internal fluid temperature from the output values ​​of the temperature sensor 3 and the heat flux sensor; and a measurement accuracy calculation unit 8 that calculates the measurement accuracy of the internal fluid temperature from the measurement accuracy of the temperature sensor 3 and the measurement accuracy or set accuracy of the heat flux sensor 4. This allows for easy measurement of the fluid temperature inside the pipe and verification of the measurement accuracy.

[0037] Furthermore, by performing a surface temperature measurement step to measure the temperature of the outer surface of the pipe, a heat flux control step to control the heat flux on the outer surface of the pipe to within a target range, an internal fluid temperature calculation step to calculate the internal fluid temperature from the measurement results of the surface temperature measurement step and the heat flux value, and a measurement accuracy calculation step to calculate the measurement accuracy of the internal fluid temperature from the measurement accuracy in the surface temperature measurement step and the measurement accuracy or setting accuracy of the heat flux in the heat flux control step, the internal fluid temperature can be easily measured and the measurement accuracy can be verified.

[0038] As described above, by using the fluid temperature measurement system 1 of this embodiment, the fluid temperature inside the pipe can be measured without requiring piping work or prior preparation of correlation graphs. Furthermore, the measurement accuracy of the measured temperature can be improved and the measurement accuracy can be guaranteed. [Examples]

[0039] In the fluid temperature measurement system 1 of Example 1, the heat flux control unit 5 requires a certain thickness, which can make installation difficult in piping in narrow spaces. This embodiment was made in consideration of such circumstances, and by adopting a thinner structure, it becomes possible to install it in piping in narrow spaces.

[0040] Figure 6 is a diagram showing the configuration of the fluid temperature measurement system according to Example 2. Figure 7 is a view of the heat flux sensor and heat flux control unit of the fluid temperature measurement system according to Example 2, taken from the direction of the pipe cross-section.

[0041] The fluid temperature measurement system 21 shown in this embodiment is installed on the outer surface of a pipe 22 through which water, air, steam, gas, etc., flows. The fluid temperature measurement system 21 consists of a temperature sensor 23, a heat flux sensor 24, a heat flux control unit 25, and a calculation control unit 26, all attached to the outer surface of the pipe. It is assumed that the temperature of the fluid flowing through the pipe 22 is relatively close to the ambient temperature, and that no pipe insulation material is installed. However, even if pipe insulation material is present, the same effect as in this embodiment can be obtained by placing the temperature sensor 23, heat flux sensor 24, and heat flux control unit 25 on the outer surface of the pipe beneath the insulation material.

[0042] The temperature sensor 23 can use either a thermocouple or a resistance thermometer. Any type of thermocouple specified in the JIS standard, such as K-type, J-type, T-type, E-type, N-type, R-type, S-type, or B-type, may be used. From the standpoint of durability and measurement accuracy, the K-type or T-type is preferable. For placement on the pipe surface, a sheath diameter of 1 mm or less is preferable.

[0043] Furthermore, quantification of temperature measurement accuracy is necessary for calculations performed by the measurement accuracy calculation unit 28. It is desirable to perform calibration tests using a temperature calibrator and obtain calibration records, but if calibration is difficult, the planned accuracy provided by the sensor supplier or the standard accuracy for each type defined in the JIS standard can be used. If an air layer exists between the thermocouple and the outer surface of the pipe, the outer surface temperature of the pipe cannot be measured correctly, so the thermocouple should be attached to the outer surface of the pipe from above using aluminum tape or glass tape, which has high thermal conductivity. Alternatively, thermal conductive gel or thermal conductive clay may be applied to the tip of the thermocouple and attached from above with aluminum tape or glass tape.

[0044] The heat flux sensor 24 can be either an epoxy glass type, which detects the heat flux by connecting multiple small thermocouples in series with an epoxy glass plate in between and using the thermoelectric voltage generated from the temperature difference between the two sides of the epoxy glass plate, or a semiconductor type, which uses a semiconductor as the thermoelectric conversion material. As described later, the measurement accuracy of the heat flux affects the measurement accuracy of the internal fluid temperature, so a sensor with the highest possible sensitivity is required, and an accuracy of 0.01 mV / (W / m) is necessary. 2 A heat flux sensor having a sensitivity coefficient of ) or higher is desirable. If an air layer exists between the heat flux sensor 24 and the outer surface of the pipe, the heat flux cannot be measured correctly, so the heat flux sensor 24 is attached to the outer surface of the pipe with double-sided tape with a thickness of 0.1 mm or less, where the thermal resistance is negligible.

[0045] The heat flux control unit 25 aims to suppress the surface heat flux and its variations that occur due to heat dissipation from the piping. While the heat flux control unit 5 described in Example 1 passively controlled the surface heat flux, this embodiment actively controls the surface heat flux to achieve a thinner device configuration. The heat flux control unit 25 in this embodiment consists of a thin rubber heater and a voltage input terminal. For piping where the internal temperature is lower than the ambient temperature, a small cooler such as a thin fan is used. The heat flux control unit 5 is a layered heater or layered cooler, and its thickness and output can be adjusted. In addition, the heating and cooling output of the heat flux control unit 5 is set to 100W or less. In this embodiment, in all cases, small heating / cooling units with a heating / cooling capacity of about 10 to 30W are used. The voltage input terminal of the rubber heater / small cooler is connected to the voltage output terminal of the calculation control unit 26 described later via a lead wire, and the output of the heater / cooler changes dynamically. The axial width W1 of the heat flux control unit 25 is at least 1.1 times the length occupied by the temperature sensor 23 and the heat flux sensor 24, and the circumferential width W2 of the pipe is at least 1.5 times the length occupied by the temperature sensor 23 and the heat flux sensor 24. To improve adhesion, the heat flux control unit 25 is attached by covering the entire unit with high-temperature tape from above.

[0046] The calculation control unit 26 reads the output voltage and measurement error input values ​​31 from the temperature sensor 23 and the heat flux sensor 24. The calculation control unit 26 then displays the internal fluid temperature, measurement accuracy, surface temperature, and surface heat flux through various calculations, and also has the function of indicating whether a review of the heat flux control is necessary. Furthermore, it has the function of controlling the output voltage to the heat flux control unit 25 based on the deviation between the output voltage of the heat flux sensor 24 and the set value. The internal fluid temperature calculation unit 27 receives the output value from the temperature sensor 23 and performs noise reduction by removing outliers and averaging. The measurement accuracy calculation unit 28 calculates the measurement error σ of the internal fluid temperature using equation (3). σ q S instead q If this is used, σ is calculated using equation (4). The total thermal resistance R in equations (3) and (4) can be calculated using equation (5).

[0047] The voltage control unit 29 compares the output value (measured value) of the heat flux sensor 24 with a target value. The heating and cooling output of the heat flux control unit 5 is controlled according to the measured value of the heat flux sensor 4. For example, if the measured value is greater than the target value, the output voltage to the heat flux control unit 25 is increased. If the measured value is within the range of the target value, the output voltage to the heat flux control unit 25 is set to a predetermined value, for example, constant. If the measured value becomes negative, the output voltage to the heat flux control unit 25 is decreased.

[0048] In other words, the heat flux control step includes a heating and cooling step in which the outer surface of the piping is heated and cooled according to the measured heat flux. In the heating and cooling step, the output voltage is increased if the measured heat flux is greater than the target value, the output voltage is set to a predetermined value if the measured heat flux is within the target range, and the output voltage is decreased if the measured heat flux is a negative value.

[0049] In this way, the device configuration can be made thinner by actively controlling the surface heat flux. A PID control algorithm may be introduced to suppress overshoot and output voltage fluctuations. The target value is within the measurement error range of the heat flux sensor 24 ±σ. q , or within the range of setting error ±S q This allows for a proper determination of whether or not a review of the heat flux control is necessary.

[0050] The display unit 30 receives the calculation results and displays the internal fluid temperature, measurement accuracy, surface temperature, and surface heat flux, as well as indicating whether a review of the heat flux control is necessary. The surface heat flux measured by the heat flux sensor 24 is the measurement error σ of the heat flux. q Alternatively, setting error S q If the value exceeds this limit, it will be determined that the heat flux is not being controlled correctly, and the user will be requested to review the heat flux control settings.

[0051] If a request to revise the heat flux control is issued, it means that the output of the heat flux control unit 25 is insufficient and the heat flux cannot be controlled to the target value. Therefore, the target value of the heat flux control is set to a larger value and the measurement is taken again. This process is repeated until the measurement result is normal. As the target value increases, the measurement error σ of the internal fluid temperature increases, as shown in equation (4).

[0052] As described above, by using the fluid temperature measurement system 1 of this embodiment, the fluid temperature inside pipes can be measured even in pipes installed in confined spaces, without the need for pipe construction work or prior preparation of correlation graphs. Furthermore, the accuracy of the measured temperature can be guaranteed. [Examples]

[0053] In the fluid temperature measurement systems of Examples 1 and 2, when the temperature difference between the fluid inside the pipe and the outside air becomes large, the control range of the heat flux control units 5 and 25 is exceeded, resulting in an excessive measurement error σ of the internal fluid temperature, which may prevent the required measurement accuracy from being met. This embodiment was made in consideration of such a situation, and enables measurement of the fluid temperature inside the pipe even when the temperature difference between the fluid inside the pipe and the outside air is large.

[0054] Figure 8 is a diagram showing the configuration of the fluid temperature measurement system according to Example 3. Figure 9 is a view of the heat flux sensor and heat flux control unit of the fluid temperature measurement system according to Example 3, viewed from the pipe cross-sectional direction.

[0055] The fluid temperature measurement system 41 shown in this embodiment is installed on the outer surface of a pipe 42 through which water, air, steam, gas, etc., flows. The fluid temperature measurement system 41 consists of a temperature sensor 43, a heat flux sensor 44, a heat flux control unit 45, and a calculation control unit 46, all attached to the outer surface of the pipe. The fluid flowing through the pipe 42 has a temperature difference with the outside air, but the system assumes a situation where no pipe insulation material is installed. Even when pipe insulation material is present, the same effect as in this embodiment can be obtained by placing the temperature sensor 43, heat flux sensor 44, and heat flux control unit 45 on the outer surface of the pipe beneath the insulation material.

[0056] The temperature sensor 43 can use either a thermocouple or a resistance thermometer. Any type of thermocouple specified in the JIS standard, such as K-type, J-type, T-type, E-type, N-type, R-type, S-type, or B-type, may be used. From the standpoint of durability and measurement accuracy, the K-type or T-type is preferable. Due to the ease of placement on the pipe surface, a sheath diameter of 1 mm or less is preferable. In addition, it is necessary to quantify the temperature measurement accuracy as it is required for calculations in the measurement accuracy calculation unit 48. It is desirable to perform a calibration test using a temperature calibrator and obtain a calibration record, but if calibration is difficult, the planned accuracy provided by the sensor supplier or the standard accuracy for each type as defined in the JIS standard can be used. If an air layer exists between the thermocouple and the outer surface of the pipe, the outer surface temperature of the pipe cannot be measured correctly, so the thermocouple should be attached to the outer surface of the pipe from above using highly thermally conductive aluminum tape or glass tape. Alternatively, thermally conductive gel or thermally conductive clay may be applied to the tip of the thermocouple and attached from above with aluminum tape or glass tape.

[0057] The heat flux sensor 44 can be either an epoxy glass type, which detects the heat flux by connecting multiple small thermocouples in series with an epoxy glass plate in between and using the thermoelectric voltage generated from the temperature difference between the two sides of the epoxy glass plate, or a semiconductor type, which uses a semiconductor as the thermoelectric conversion material. As described later, the measurement accuracy of the heat flux affects the measurement accuracy of the internal fluid temperature, so a sensor with the highest possible sensitivity is required, and an accuracy of 0.01 mV / (W / m) is necessary. 2 A heat flux sensor having a sensitivity coefficient of ) or higher is desirable. If an air layer exists between the heat flux sensor 44 and the outer surface of the pipe, the heat flux cannot be measured correctly, so the heat flux sensor 44 is attached to the outer surface of the pipe with double-sided tape with a thickness of 0.1 mm or less, where the thermal resistance is negligible.

[0058] The heat flux control unit 45 aims to suppress the surface heat flux and its variations that occur due to heat dissipation from the piping. In this embodiment, the configuration is designed to control excessive surface heat flux, which is difficult to control with the configurations of Embodiments 1 and 2.

[0059] The heat flux control unit 45 has a configuration in which a block-shaped member 53 made of a low thermal conductivity material is placed on the upper surface of a thin rubber heater and a voltage input terminal 52. For pipes where the internal temperature is lower than the ambient temperature, a small cooler such as a thin fan is used instead of the rubber heater. In either case, the heating / cooling capacity is small, around 10 to 30 watts.

[0060] The voltage input terminal of the rubber heater / small cooler is connected via lead wires to the voltage output terminal of the voltage control unit 49 described later, and the output of the heater / cooler changes dynamically. The block-shaped member 53 has a layered structure so that the thickness H and widths W1 and W2 can be changed. The material is a thermal insulation material such as rock wool, glass wool, calcium silicate, or foamed plastic insulation material. In addition, other materials may be used as long as they are solid substances with a thermal conductivity of 0.5 W / mK or less. The thickness H is determined to satisfy the following formula.

[0061] H≧0.2×k²×[(T i -T o ) / σ q -1 / h i -t0 / k0-t1 / k1-1 / h o ] ... (6) Here, T i The design piping temperature is T o The outside temperature is h i This is the convection heat transfer coefficient within the pipe, expressed by empirical formulas such as the Dittus-Boelter equation or 5000 W / m². 2 Let K be given as follows: t0 is the lining thickness, k0 is the thermal conductivity of the lining material, t1 is the pipe wall thickness, k1 is the thermal conductivity of the pipe material, and h0 is the convection heat transfer coefficient outside the pipe. The empirical formula for the natural convection heat transfer coefficient of air is 10 W / m². 2 Let K be given as k2. k2 is the thermal conductivity of the heat flux control unit 5. q σ is the measurement error of the heat flux and is calculated using equation (2). The H calculated from equation (6) is 1 / 5 of that in equation (1), and it is possible to prevent H from becoming excessive even under conditions where the temperature difference between the internal fluid and the outside air is large. Also, in equation (6), σ q Instead, the heat flux setting error S qYou may use S. q This is an arbitrary value, and should be set so that H does not become excessively large. The widths W1 and W2 of the heat flux control unit 45 are determined to cover the installation areas of the heat flux sensor 44, temperature sensor 43, and rubber heater.

[0062] The calculation control unit 46 reads the output voltage and measurement error input values ​​51 from the temperature sensor 43 and the heat flux sensor 44, and has the function of displaying the internal fluid temperature, measurement accuracy, surface temperature, and surface heat flux through various calculations, as well as indicating whether or not the heat flux control needs to be reviewed. Furthermore, it has the function of controlling the output voltage to the heat flux control unit 45 based on the deviation between the output voltage of the heat flux sensor 44 and the set value. The internal fluid temperature calculation unit 47 receives the output value of the temperature sensor 43 and performs noise reduction by removing outliers and averaging. The measurement accuracy calculation unit 48 calculates the measurement error σ of the internal fluid temperature using equation (3). σ q S instead q If this is used, σ is calculated using equation (4). The total thermal resistance R in equations (3) and (4) is calculated using equation (5).

[0063] The voltage control unit 49 compares the output value (measured value) of the heat flux sensor 44 with the target value. If the measured value is greater than the target value, the output voltage to the heat flux control unit 45 is increased. If the measured value is within the range of the target value, the output voltage to the heat flux control unit 45 is kept constant. If the measured value is negative, the output voltage to the heat flux control unit 45 is decreased. A PID control algorithm may be introduced to suppress overshoot and oscillations in the output voltage. The target value is within the measurement error range of the heat flux sensor 44 ±σ. q , or within the range of setting error ±S q Let's assume that.

[0064] The display unit 50 receives the calculation results and displays the internal fluid temperature, measurement accuracy, surface temperature, and surface heat flux, as well as indicating whether a review of the heat flux control is necessary. The surface heat flux measured by the heat flux sensor 44 is the measurement error of the heat flux σ q Alternatively, setting error S qIf the value exceeds this limit, it is determined that the heat flux is not being controlled correctly, and the user is requested to review the heat flux control settings. Figure 4 shows the display result when the heat flux is controlled correctly, and Figure 5 shows the display result when it is not measured correctly.

[0065] If a request for a review of the heat flux control arises, the user attaches a material of the same quality to the heat flux control unit 45, increasing its thickness H and widths W1 and W2, and then measures again. This process is repeated until the measurement results are normal. If a large-sized heat flux control unit 45 is installed in advance, it becomes difficult to handle and the risk of corrosion under the insulation material increases. Following this procedure allows for measurement of the internal fluid temperature with the smallest possible device configuration. Furthermore, compared to Example 1, this embodiment adds the effect of controlling the surface heat flux by rubber heater control, allowing the thickness H, widths W1 and W2 to be smaller than those of the block-shaped member in Example 1, thus reducing the size of the fluid temperature measurement system and improving workability.

[0066] If a request for a review of the heat flux control arises, and further increases in thickness H, width W1, and W2 are difficult, the target value for heat flux control is set to a larger value and the measurement is performed again. This process is repeated until the measurement result is normal. As the target value increases, the measurement error σ of the internal fluid temperature increases, as shown in equation (4). Compared to Example 2, in this example, the surface heat flux control effect of the block-shaped member 53 is added, making it possible to control a larger surface heat flux.

[0067] By using a fluid temperature measurement system based on the above configuration, it is possible to measure the fluid temperature inside pipes even in pipes with a large temperature difference between the fluid inside and the outside air, and a large surface heat flux, without requiring pipe construction work or prior preparation of correlation graphs. Furthermore, the accuracy of the measured temperature can be guaranteed. [Explanation of symbols]

[0068] 1…Fluid temperature measurement system, 2…Piping, 3…Temperature sensor, 4…Heat flux sensor, 5…Heat flux control unit, 6…Calculation control unit, 7…Internal fluid temperature calculation unit, 8…Measurement accuracy calculation unit, 9…Display unit, 10…Input value, 11…Result without heat flux control unit, 12…Result with heat flux control, 21…Fluid temperature measurement system, 22…Piping, 23…Temperature sensor, 24…Heat flux sensor, 25…Heat flux control unit, 26…Calculation control unit, 27…Internal fluid temperature calculation unit, 28…Measurement accuracy calculation unit, 29…Voltage control unit, 30…Display unit, 31…Input value, 41…Fluid temperature measurement system, 42…Piping, 43…Temperature sensor, 44…Heat flux sensor, 45…Heat flux control unit, 46…Calculation control unit, 47…Internal fluid temperature calculation unit, 48…Measurement accuracy calculation unit, 49…Voltage control unit, 50…Display unit, 51 ...input value, 52...voltage input terminal, 53...block-shaped component.

Claims

1. In a fluid temperature measuring system that measures the fluid temperature inside a pipe through which liquid or vapor flows, A heat flux control unit is positioned on the opposite side of the pipe from the temperature sensor and heat flux sensor installed on the outer surface of the pipe, and controls the heat flux on the outer surface of the pipe to be within a target range. An internal fluid temperature calculation unit that calculates the internal fluid temperature from the output values ​​of the temperature sensor and the heat flux sensor, A fluid temperature measurement system characterized by comprising a measurement accuracy calculation unit that calculates the measurement accuracy of the internal fluid temperature from the measurement accuracy of the temperature sensor and the measurement accuracy or setting accuracy of the heat flux sensor.

2. In the fluid temperature measurement system according to claim 1, A fluid temperature measurement system characterized by comprising a display unit that displays the internal fluid temperature and the measurement error of the internal fluid temperature, and indicates whether or not the heat flux control needs to be reviewed.

3. In the fluid temperature measurement system according to claim 1, A fluid temperature measurement system characterized in that the target value of the heat flux control unit is the measurement accuracy of the heat flux sensor or the setting accuracy of the heat flux sensor.

4. In the fluid temperature measurement system according to claim 1, The heat flux control unit is a block-shaped member made of a material with a thermal conductivity of 0.5 W / mK or less. The heat flux control unit is configured in a layered structure so that its thickness and width can be changed. A fluid temperature measurement system characterized in that the thickness of the heat flux control unit is greater than the value obtained by dividing the temperature difference between the fluid inside the pipe and the outside air by the measurement accuracy or setting accuracy of the heat flux sensor and multiplying by the thermal conductivity of the block-shaped member.

5. In the fluid temperature measurement system according to claim 1, The heat flux control unit is a layered heater or a layered cooler, and the heating / cooling output of the heat flux control unit is 100W or less. The heat flux control unit is equipped with a voltage control unit that controls the heating and cooling output of the heat flux control unit according to the measurement value of the heat flux sensor, The fluid temperature measurement system is characterized in that the voltage control unit controls the output voltage to increase when the measured value of the heat flux sensor is greater than a target value, to set the output voltage to a predetermined value when the measured value of the heat flux sensor is within the range of the target value, and to decrease the output voltage when the measured value of the heat flux sensor is negative.

6. In the fluid temperature measurement system according to claim 1, The heat flux control unit comprises a layered heater or a layered cooler, The layered heater or the layered cooler has a block-shaped member made of a material with a thermal conductivity of 0.5 W / mK or less on the side opposite to the piping, The fluid temperature measuring system is characterized in that the block-shaped member has a layered structure such that its height and width can be changed.

7. In a fluid temperature measurement method for measuring the fluid temperature inside a pipe through which a liquid or vapor flows, A surface temperature measurement step to measure the temperature of the outer surface of the pipe, A heat flux control step for controlling the heat flux on the outer surface of the piping to within a target value range, An internal fluid temperature calculation step which calculates the internal fluid temperature from the measurement results of the surface temperature measurement step and the heat flux value, A fluid temperature measurement method characterized by including a measurement accuracy calculation step that calculates the measurement accuracy of the internal fluid temperature from the measurement accuracy in the surface temperature measurement step and the measurement accuracy or setting accuracy of the heat flux in the heat flux control step.

8. In the fluid temperature measurement method described in claim 7, A fluid temperature measurement method characterized by displaying the internal fluid temperature and the measurement error of the internal fluid temperature, and indicating whether or not the heat flux control needs to be reviewed.

9. In the fluid temperature measurement method described in claim 7, The heat flux control step includes a heating and cooling step of heating and cooling the outer surface of the pipe according to the measured value of the heat flux, The heating and cooling step is characterized by increasing the output voltage when the measured value of the heat flux is greater than a target value, setting the output voltage to a predetermined value when the measured value of the heat flux is within the range of the target value, and decreasing the output voltage when the measured value of the heat flux is negative.

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