JP6686335B2 - Relation information setting method, flow velocity measurement method, relation information setting system and flow velocity measurement system - Google Patents

Description

  The present invention relates to a relation information setting method, a flow velocity measuring method, a relation information setting system, and a flow velocity measuring system.

  Patent Document 1 discloses a method for measuring the flow velocity of a fluid flowing in a pipe. In this flow velocity measuring method, heat is exchanged at a predetermined portion of the surface of the pipe, the temperature distribution in the pipe axis direction of the pipe is measured, and the flow velocity of the fluid flowing inside the pipe is obtained based on the measured temperature distribution.

JP, 2015-148508, A

  As a method of obtaining the flow velocity of the fluid flowing inside the pipe from the temperature distribution of the pipe, a method of previously obtaining the relationship between the temperature distribution and the flow velocity and using the obtained relation to convert the temperature distribution into the flow velocity can be considered. In this method, it is preferable to obtain the relationship between the temperature distribution and the flow velocity with high precision in order to obtain the flow velocity with high precision.

  The present invention provides a relation information setting method, a flow velocity measuring method, a relation information setting system, and a flow velocity measuring system capable of accurately obtaining the relation between the temperature distribution of the pipe and the flow velocity of the fluid flowing inside the pipe.

According to the first aspect of the present invention, the relation information setting method is a relation information setting method for obtaining relation information indicating a relation between a flow velocity of a fluid flowing inside a pipe and a temperature distribution on the surface of the pipe, A heat exchange step of performing heat exchange on a predetermined portion of the surface of the pipe, and an analysis step of obtaining an analysis value of a temperature distribution on the surface of the pipe in a state where heat exchange is performed on a predetermined portion of the surface of the pipe; A heat transfer coefficient correction coefficient that takes a value according to a distance from the predetermined portion in the pipe axis direction of the pipe , and the larger the value of the heat transfer coefficient correction coefficient, the more the fluid flowing inside the pipe. The heat transfer coefficient correction coefficient value acquisition step of acquiring the value of the heat transfer coefficient correction coefficient in which the heat transfer coefficient with the pipe wall of the pipe is set large, and the analysis value acquired in the analysis step, the heat transfer coefficient correction Heat transfer coefficient correction section acquired in the coefficient value acquisition process And modified based on the value, including the related information setting step of obtaining the relation information.

  In the heat transfer coefficient correction coefficient value acquisition step, the value of the heat transfer coefficient correction coefficient may be acquired for each position along the pipe.

  The heat transfer includes: a temperature measuring step of measuring a temperature distribution on a surface of the pipe in a pipe axis direction of the pipe where heat is exchanged in the predetermined portion; and a flow velocity measuring step of measuring a flow velocity of the fluid. In the coefficient correction coefficient value acquisition step, the temperature distribution measured in the temperature measurement step, the analysis value of the temperature distribution acquired in the analysis step, and the heat transfer coefficient correction coefficient based on the flow velocity measured in the flow velocity measurement step You may make it set a value.

  According to the second aspect of the present invention, the flow velocity measurement method is a flow velocity measurement in which heat exchange is performed at a predetermined portion of the surface of the pipe in a state where the flow velocity of the fluid flowing inside the pipe is the flow velocity to be measured. A time heat exchange step, a flow velocity measurement temperature distribution measurement step of measuring a temperature distribution of the surface in the pipe axis direction of the pipe heat exchanged in the predetermined portion in the flow velocity measurement heat exchange step, and Flow through the inside of the pipe based on the temperature distribution measured in the temperature distribution measuring step during flow velocity measurement and the relation information obtained by the relation information setting method according to any one of claims 1 to 3. A flow velocity acquisition step of obtaining the flow velocity of the fluid.

According to a third aspect of the present invention, the relation information setting system is a relation information setting system for obtaining relation information indicating a relation between a flow velocity of a fluid flowing inside a pipe and a temperature distribution on the surface of the pipe, A heat exchanger that performs heat exchange on a predetermined portion of the surface of the pipe, and an analysis unit that obtains an analysis value of a temperature distribution on the surface of the pipe in a state where heat exchange is performed on a predetermined portion of the surface of the pipe. A heat transfer coefficient correction coefficient that takes a value according to a distance from the predetermined portion in the pipe axis direction of the pipe, and the greater the value of the heat transfer coefficient correction coefficient, the more the fluid flowing inside the pipe. The heat transfer coefficient correction coefficient value acquisition unit for acquiring the value of the heat transfer coefficient correction coefficient in which the heat transfer coefficient with the pipe wall of the pipe is set large, and the analysis value acquired by the analysis unit Heat transfer coefficient correction coefficient acquired by the coefficient value acquisition unit And modified based on the value, and a relation information setting unit for determining the relation information.

  The heat transfer coefficient modification coefficient value acquisition unit may acquire the value of the heat transfer coefficient modification coefficient for each position along the pipe.

  The heat transfer includes: a temperature measuring unit that measures a temperature distribution on a surface of the pipe in a pipe axis direction of the pipe where heat is exchanged in the predetermined portion; and a flow velocity measuring unit that measures a flow velocity of the fluid. The coefficient correction coefficient value acquisition unit is a temperature distribution measured by the temperature measurement unit, an analysis value of the temperature distribution acquired by the analysis unit, and the heat transfer coefficient correction coefficient based on the flow velocity measured by the flow velocity measurement unit. You may make it set a value.

  According to the fourth aspect of the present invention, the flow velocity measurement system is configured such that the relation information setting system described above, the storage unit that stores the relation information set by the relation information setting unit, and the flow velocity of the fluid flowing inside the pipe are A heat exchanger that performs heat exchange at a predetermined portion of the surface of the pipe in a state where the flow velocity is a measurement target, and a surface of the pipe in the pipe axial direction of the pipe where heat is exchanged at the predetermined portion. A temperature measurement unit that measures a temperature distribution, a temperature distribution measured by the temperature measurement unit, and a flow velocity calculation unit that calculates the flow velocity of the fluid based on the relationship information stored in the storage unit. .

  According to the relation information setting method, the flow velocity measuring method, the relation information setting system, and the flow velocity measuring system described above, the relation between the temperature distribution of the pipe and the flow velocity of the fluid flowing inside the pipe can be accurately obtained.

The figure which shows schematic structure of the flow velocity measuring system which concerns on this embodiment. The figure which shows the principal part structure of a flow velocity measuring system. The schematic diagram which shows the control unit 4. Explanatory drawing which shows the example of division | segmentation into the cell of the area | region of the piping 10. The graph which shows the example of setting of a heat transfer coefficient correction coefficient. Explanatory drawing which shows the example of a setting of a temperature boundary coefficient. The graph which shows the example of setting of a temperature boundary coefficient. The figure which shows schematic structure of the related information setting system which concerns on this embodiment. The graph which shows the example of the measured value and analysis value of the temperature distribution in piping before setting the value of a heat transfer coefficient correction coefficient and the value of a temperature boundary coefficient. The graph which shows the example of the measured value and analysis value of the temperature distribution in piping after setting the value of a heat transfer coefficient correction value and the value of a temperature boundary coefficient.

Hereinafter, embodiments of the present invention will be described, but the following embodiments do not limit the invention according to the claims. In addition, not all of the combinations of features described in the embodiments are essential to the solving means of the invention.
The flow velocity measuring system according to the present embodiment is a system capable of measuring the flow velocity of a fluid (for example, steam) flowing in a pipe arranged between a steam manufacturing apparatus such as a boiler and load equipment.

FIG. 1 is a diagram showing a schematic configuration of a flow velocity measuring system according to this embodiment. FIG. 2 is a diagram showing a main configuration of the flow velocity measuring system.
As shown in FIG. 1, the flow velocity measuring system 100 according to the present embodiment includes a heating unit (heat exchanger) 2, a pre-heater 2b, a temperature measuring unit 3, and a control unit (flow velocity calculating unit) 4. Including. In FIG. 1, a pipe 10 is arranged between a steam producing apparatus 20 (boiler or the like) and a load facility 30. Steam from the steam manufacturing apparatus 20 flows through the pipe 10 and is sent to the load facility 30. In the load facility 30, steam or heat of steam is used. The steam discharged from the load facility 30 is collected as a drain, collected in a return water tank (not shown), and then supplied to the steam manufacturing apparatus 20 again. A heat insulating material is wound around the pipe 10.

The heating unit 2 is for heating a predetermined portion by exchanging heat with the surface 10a of the pipe 10. In the present embodiment, the heating unit 2 is composed of, for example, a ring-shaped heater, and is arranged at a predetermined position on the surface 10a of the pipe 10 in the circumferential direction, as shown in FIG. Thereby, the heating unit 2 uniformly heats the surface 10a of the pipe 10 in a predetermined portion of the pipe 10 (the installation portion 11 of the heating unit 2). The heating unit 2 is electrically connected to the control unit 4 and its operation is controlled.
The heat exchanger mentioned here transfers heat from an object having a high temperature to an object having a low temperature. The heater corresponds to an example of a heat exchanger.
Note that, in FIG. 2, an arrow B11 indicates an example of a direction in which the fluid flows in the pipe 10.

  The pre-heater 2b heats the fluid flowing in the pipe 10. The preheater 2b is provided to prevent liquefaction of the fluid of the gas flowing in the pipe 10. For example, when the fluid flowing in the pipe 10 is steam, the preheater 2b heats the steam to prevent the steam from being liquefied and attached to the pipe 10 or the load equipment 30. .

  The temperature sensor groups 3A are arranged on both sides (upstream side and downstream side) of the installation portion 11 of the heating portion 2 on the surface 10a of the pipe 10. The installation position of each temperature sensor group 3A is determined according to the distance from the installation portion 11. For example, taking the upstream side of the installation portion 11 as an example, in each temperature sensor group 3A, the distance from the end surface of the installation portion 11 is 0 mm (millimeter), 6 mm, 14 mm, 24 mm, 36 mm, 50 mm, 66 mm, 84 mm, 104 mm. , 126 mm, 150 mm, 176 mm. Here, a distance of 0 mm from the end face of the installation portion 11 means that the temperature sensor group 3A is arranged along the end face of the heating unit 2. In FIG. 2, as the cross-sectional structure of the pipe 10, the vicinity of the downstream end face of the installation portion 11 (cross section taken along the line AA) and the distance 24 mm from the downstream end face of the installation portion 11 near the arrow BB (arrow B-B). And a cross section by visual observation).

  As shown in FIG. 2, the temperature sensor groups 3A are arranged such that the distance between the adjacent temperature sensor groups 3A increases by 2 mm as the temperature sensor groups 3A move away from the installation portion 11. Therefore, the closer the temperature sensor group 3A is to the installation portion 11 (heating unit 2), the closer the sensors are arranged. As a result, it is possible to accurately detect the temperature of the surface 10a of the pipe 10 near the installation portion 11.

  The temperature measurement unit 3 is composed of a plurality of (for example, 12 in this embodiment) temperature sensor groups 3A. Each temperature sensor group 3A is arranged on the surface 10a of the pipe 10 along the pipe axis direction of the pipe 10. Each temperature sensor group 3A includes a plurality of temperature sensors 3a for measuring the temperature of the surface 10a of the pipe 10. In the present embodiment, each temperature sensor group 3A is composed of four temperature sensors 3a. The four temperature sensors 3a are evenly arranged in the circumferential direction on the surface 10a of the pipe 10. That is, the four temperature sensors 3a are arranged so as to be displaced by 90 degrees in the circumferential direction of the pipe 10. Each temperature sensor group 3A outputs the average value of the values measured by the four temperature sensors 3a as a measurement value. As described above, the temperature sensor group 3A can output a highly reliable measurement result (temperature) by taking the average of the values measured at a plurality of points on the surface 10a of the pipe 10 as the measured value.

  The number of the temperature sensors 3a forming each temperature sensor group 3A is not limited to four shown in FIG. 2 and may be one or more. For example, each temperature sensor group 3A includes two temperature sensors 3a, and the two temperature sensors 3a are evenly arranged in the circumferential direction of the pipe 10 (so that the positions are different by 180 degrees in the circumferential direction of the pipe 10). It may have been done. As described above, each temperature sensor group 3A includes a plurality of temperature sensors 3a, and the average of the values measured at a plurality of points on the surface 10a of the pipe 10 is used as the measured value to obtain a highly reliable measurement result (temperature). Output is possible.

  Based on the configuration described above, the temperature measuring unit 3 can measure the temperature distribution of the surface 10a in the pipe axis direction of the pipe 10 from the measurement result of each temperature sensor group 3A. The temperature distribution measured by the temperature measuring unit 3 is transmitted to the control unit 4.

  At least a part of the surface 10 a of the pipe 10 is covered with the heat insulating material 12. In the present embodiment, the heat insulating material 12 is installed in the pipe axial direction so as to cover the heating unit 2 and the temperature measuring unit 3 (each temperature sensor 3a) provided on the surface of the pipe 10.

  FIG. 3 is a schematic diagram showing the control unit 4. In FIG. 3, the computing device 50 is, for example, a computer system. The control unit 4 has an input device 60 and a display device (output device) 64 in addition to the calculation device 50. The computing device 50 includes a converter 61 such as an A / D converter, a CPU (arithmetic processing unit) 62, a memory 63, and the like. The measurement data (temperature distribution) sent from the temperature measuring unit 3 of the flow velocity measuring system 100 is converted by the converter 61 or the like as required and is taken into the CPU 62. Further, initial setting values, temporary data, and the like are loaded into the computing device 50 via the input device 60 and the like. The display device 64 can display information regarding input data, information regarding calculation, and the like.

The CPU 62 can calculate the flow velocity of the steam flowing inside the pipe 10 based on the measurement data and the information stored in the memory 63. The CPU 62 calculates the flow velocity of the steam flowing inside the pipe 10 from the information stored in the memory 63, using the measurement result of the temperature measurement unit 3 (temperature distribution on the surface 10a of the pipe 10), for example. The control unit 4 corresponds to an example of the flow velocity calculation unit.
Specifically, the memory 63 stores in advance (prior to the measurement of the flow velocity) relation information indicating the relation between the temperature distribution on the surface 10a of the pipe 10 and the flow velocity of the fluid flowing inside the pipe 10. . The memory 63 corresponds to an example of a storage unit. In the relation information stored in the memory 63, the flow velocity and the temperature distribution are associated with each other for each flow velocity of the fluid.
Then, when the temperature measuring unit 3 measures the temperature distribution on the surface 10a of the pipe 10, the CPU 62 refers to the relationship information and is closest to the temperature distribution measured by the temperature measuring unit 3 (for example, the sum of absolute values of differences). The flow velocity associated with the temperature distribution is read out and used as the measured flow velocity value.

  In this way, the memory 63 stores in advance relational information in which the temperature distribution and the flow velocity are associated with each other. Then, the heating unit 2 heats a predetermined portion with a ring heater (ring-shaped heater), and the temperature measuring unit 3 measures the temperature distribution in the pipe 10 in a state where the temperature distribution of the pipe 10 is in a steady state. Then, the control unit 4 refers to the relationship information and sets the flow velocity associated with the temperature distribution closest to the temperature distribution obtained by the measurement as the flow velocity measurement value.

Next, a method of acquiring the related information stored in the memory 63 in advance will be described.
The relational information can be obtained by analyzing the heat transfer in the temperature steady state of the pipe 10 by the finite element method. The case where the control unit 4 performs the finite element method calculation will be described below as an example, but the finite element method analysis may be performed using another computer.
In order to apply the finite element method to the pipe 10, the region of the pipe 10 is divided into cells (partial regions).

FIG. 4 is an explanatory diagram showing an example of division of the region of the pipe 10 into cells.
An area A11 shown in the figure shows an area (area in which fluid flows) inside the pipe. A region A12 indicates a region of the pipe 10 (a region of a pipe wall). A region A13 indicates a region of the heat insulating material wound around the pipe 10. Area A14 indicates an area of air outside the heat insulating material. The arrow B11 indicates an example of the direction in which the fluid flows in the pipe 10.

In cell division for applying the finite element method, as shown in FIG. 4, the region A12 of the pipe wall of the pipe 10 is divided into three layers with an equal thickness. The three layers, the fluid region A11, the heat insulating material region A13, and the outside air region A14 are divided into six layers in the radial direction of the pipe 10.
Further, in the axial direction (longitudinal direction) of the pipe 10, the pipe 10 is equally divided into relatively small widths such as 3 mm width.
Further, a ring-shaped heater is used as the heating unit 2, and the thickness of the heating unit 2 in the longitudinal direction of the pipe 10 is ignored as shown in FIG. In particular, it is approximated that the heating unit 2 heats only one of the cells in the region A12 of the pipe wall of the pipe 10. Also, the influence of the capacity of the heating unit 2 itself is ignored (the capacity is assumed to be sufficiently small).

The heat transfer between the adjacent contact points includes the convective heat transfer between the inner surface of the tube and the fluid in the tube, the heat transfer in the tube wall (in the area A12 in FIG. 4), the heat transfer from the tube wall to the heat insulating material and the heat insulating material. And heat transfer by convective heat transfer between the outer surface of the heat insulating material and the ambient air. In addition, the outer edge of the cell at the end of the tube that is sufficiently distant from the heating unit 2 is adiabatic condition.
The following equation based on heat balance (the following equation (1)) is set for each cell, and the control unit 4 analyzes it using the finite element method to calculate the temperature difference between the cells. As the solution method of the finite element method (solution method of simultaneous equations), for example, the Newton-Raphson method can be used. However, the solution method used by the control unit 4 is not limited to the Newton-Raphson method, and various solution methods applicable to simultaneous equations can be used.

Here, in the steady state, the sum of the heat input amounts from the adjacent cells becomes zero. The amount of heat released is expressed as the amount of heat input minus.
The heat balance in the cell located at the coordinates (i, j) is expressed by the equation (1).

Q _{i, j-1} + Q _{i, j + 1} + Q _{i-1, j} + Q _{i + 1, j} = 0 (1)

Here, the coordinates of the cells adjacent to the cell located at the coordinates (i, j) are (i, j-1), (i, j + 1), (i-1, j), and (i + 1, j). . In addition, Q _{i, j−1} , Q _{i, j + 1} , Q _{i−1, j} , and Q _{i + 1, j} represent the heat input amounts from the cells located at the coordinates indicated by the subscripts. If there is no adjacent cell, the heat input from the cell is set to 0.
As described above, the equation (equation (1)) based on the heat balance is set for each cell. The equation is set by, for example, the user of the flow velocity measuring system 100 and stored in the memory 63 of the control unit 4. Then, the control unit 4 performs analysis by the finite element method for each set value of the flow velocity, and acquires the relation information indicating the relation between the temperature distribution and the flow velocity. The control unit 4 corresponds to an example of the analysis unit in that the analysis value of the temperature distribution in the pipe 10 is obtained.

For Q _{i, j−1} , Q _{i, j + 1} , Q _{i−1, j} , and Q _{i + 1, j} in Expression (1), for example, the right side of any of the following Expressions (2) to (4) is applied. To do.

  Convection heat transfer: The amount of heat input from the fluid (fluid in the pipe 10) to the cell on the inner side of the cells of the pipe 10 is represented by the equation (2).

      Heat input due to convective heat transfer = α ・ A ・ Δt (2)

Here, α [W (Watt) / (m ² (square meter) · K (Kelvin))] indicates a convective heat transfer coefficient.
A [m ² ] indicates a heat transfer area. Here, it is the area where the cells of the pipe 10 contact the fluid in the pipe.
Δt [K] indicates a temperature difference between adjacent cells. Here, the temperature difference in the contact portion between the pipe 10 and the fluid in the pipe is shown.

  Radial heat conduction: The amount of heat input due to the heat conduction in the pipe 10 in the radial direction in the pipe 10 is represented by the equation (3). That is, the amount of heat input from the cells of the tubes (cells obtained by cutting the tube into a mesh) that are adjacent to each other in the radial direction of the tube is expressed by equation (3).

      Heat input due to heat conduction in the radial direction = 2π · λ · L · Δt / ln (ro / ri) (3)

Here, π indicates the circular constant.
λ [W / (m (meter) · K)] indicates the thermal conductivity of the material (for example, steel) of the pipe 10.
L [m] indicates the length of the cell in the pipe axis direction (the axial direction of the pipe 10).
Δt [K] indicates the temperature difference between adjacent cells, as described above. Here, the temperature difference in the contact portion between the cells of the pipe 10 that is adjacent to the pipe 10 in the radial direction is shown.
In indicates a natural logarithm.
ro / ri [m] indicates the distance between cells in the radial direction (for example, the distance between the centers of cells).

  Heat transfer in the axial direction of the pipe: The heat input amount due to the heat transfer in the axial direction (longitudinal direction) of the pipe 10 in the pipe 10 is represented by Expression (4). That is, the amount of heat input from the cells of the pipe 10 that are adjacent to each other in the pipe axis direction is represented by Expression (4).

      Heat input due to heat transfer in the tube axial direction = λAΔt / L (4)

Here, λ and L are as described above.
A [m ² ] indicates the heat transfer area as described above. Here, it is an area where cells of the pipe 10 (cells of the pipe 10 that are adjacent to each other in the radial direction of the pipe 10) are in contact with each other.
Δt [K] indicates the temperature difference between adjacent cells, as described above. Here, the temperature difference in the contact portion between the cells of the pipe 10 adjacent to each other in the pipe axis direction is shown.

  Further, regarding convection heat transfer, the following equation (5) is used.

^{_{N ud = 0.022 · X WT ·}} R ed 0.8 · P r 0.4 ··· (5)

Here, N _ud indicates the Nusselt number.
R _ed indicates the Reynolds Number.
P _r indicates the Prandtl Number.
X _WT is a coefficient for correcting the temperature, and takes a value according to the distance from the heating unit 2 (heater). In particular, the _XWT increases the temperature in the vicinity of the heating unit 2 (that is, increases the heat transfer). Hereinafter, X _WT is referred to as a heat transfer coefficient correction coefficient.

The Nusselt number N _ud is expressed as in Expression (6).

N _ud = αi · di / λ (6)

Here, λ is as described above.
di [m] indicates the inner diameter of the pipe 10.
αi [W / (m ² · K)] indicates the thermal conductivity inside the pipe 10.

Further, the Reynolds number R _ed is expressed as in Expression (7).

R _ed = u × di / ν (7)

Here, u [m / s (second)] indicates the flow velocity of the fluid flowing in the pipe 10.
ν [m ² / s] represents the kinematic viscosity coefficient of the fluid flowing in the pipe 10.
di [m] indicates the inner diameter of the pipe 10.

Further, the Prandtl number P _r is _expressed as in Expression (8).

P _r = ν × ρ × Cp / λ (8)

ν and λ are as described above.
ρ [kg (kilogram) / m ³ (cubic meter)] indicates the density of the fluid.
Cp [kJ (kilojoule) / (kg · K)] indicates the specific heat of the fluid.

FIG. 5 is a graph showing a setting example of the heat transfer coefficient modification coefficient. The horizontal axis of the figure shows the distance from the predetermined reference position in the flow direction of the fluid flowing in the pipe 10 (pipe axis direction of the pipe 10). The side with a smaller coordinate value indicates the upstream side of the fluid flow, and the side with a larger coordinate value indicates the downstream side of the fluid flow. The vertical axis represents the value of the heat transfer coefficient modification coefficient. The coordinate value X1 indicates the coordinate value on the horizontal axis of the position where the heater of the heating unit 2 is provided.
As shown in the figure, the value of the heat transfer coefficient modification coefficient X _WT is made larger than 1 in the vicinity of the heater installation position (coordinate X1) of the heating unit 2.

_Increasing the value of the heat transfer coefficient modification coefficient X _WT corresponds to increasing the heat transfer coefficient between the fluid flowing in the pipe 10 and the pipe wall of the pipe 10. Here, steam is flown into the pipe 10 to measure the temperature distribution and the flow velocity, and the analysis value of the temperature distribution (the value obtained by the analysis using the finite element method by applying the general heat transfer equation) and As a result of comparison with the measured value, the measured temperature value was higher than the analyzed value in the vicinity of the heater installation position of the heating unit 2. In particular, the measured temperature value was higher than the analyzed value on the upstream side from the heater installation position of the heating unit 2. Therefore, when the heat transfer coefficient correction coefficient X _WT was introduced and recalculation was performed, the analyzed value and the actually measured value were in better agreement.

In the example of FIG. 5, the value of the heat transfer coefficient modification coefficient X _WT is set to 1.75 within a range of 100 mm upstream from the installation position of the heater of the heating unit 2. Further, the value of the heat transfer coefficient correction coefficient X _WT is set to be larger than 1 even in the range within 100 mm downstream from the installation position of the heater of the heating unit 2. Specifically, the value of the heat transfer coefficient correction coefficient X _WT is set to 1.25 at the installation position of the heater of the heating unit 2. Then, gradually decreases the value of heat transfer coefficient correction factors X _WT at a constant decreasing rate as going to the downstream side, at a position upstream 100mm from the installation position of the heating unit 2 heater, the heat transfer rate correction factor X _WT Is set to 1.
For example, the user of the flow velocity measuring system 100 may flow a fluid having a known flow velocity into the pipe 10 to measure the temperature distribution, and set the value of the heat transfer coefficient correction coefficient X _WT based on the obtained measurement result. Good.

The Nusselt number N _ud of the equation (5) is proportional to the convection heat transfer coefficient α of the equation (2), and the heat transfer coefficient α can be obtained from the Nusselt number N _ud . The value of the convection heat transfer coefficient α can be obtained with high accuracy by introducing the heat transfer coefficient correction coefficient X _WT as shown in Expression (5) and _obtaining the value of the Nusselt number N _ud with high accuracy. By obtaining the value of the convection heat transfer coefficient α with high accuracy, the temperature difference between the cells can be obtained with high accuracy by the analysis using the finite element method, and thus the analysis value of the temperature distribution in the pipe 10 can be obtained. The accuracy of can be improved.

  Further, regarding convection heat transfer, the following equation (9) is also used.

W = Y _HT / G / C _p / ΔT (9)

Here, Cp is as described above.
W [J (joule) / s] indicates the heating amount by the heating unit 2.
G [kg / s] indicates the total flow rate of the fluid flowing through the pipe 10.
ΔT [° C. (degrees)] indicates the temperature rise of the fluid due to the heating of the heater of the heating unit 2.
_YHT is the ratio of the amount of fluid that contributes to the transfer of heat from the heater of the heating unit 2 (the amount of fluid that receives heat from the heater of the heating unit 2) in the total amount of fluid that flows in the cross section of the tube. Show. Specifically, Y _HT = S1 / S, where S is the area of the entire fluid in the cross section of the tube and S1 is the area of the portion of the fluid in the cross section of the tube that receives heat from the heating of the heater. In the _following, referred to as the temperature boundary coefficient _{Y HT.}

As described above, the temperature distribution and the flow velocity are measured by flowing steam in the pipe 10, and the analysis value of the temperature distribution (the value obtained by the analysis using the finite element method by applying the general heat transfer equation) ) And the measured value, the measured temperature value was higher than the analyzed value in the vicinity of the heater installation position of the heating unit 2. In addition to the deviation of the temperature from the heater installation position of the heating unit 2 to the upstream side, the measured temperature value was higher than the analysis value also from the heater installation position of the heating unit 2 to the downstream side. As one of the causes of this temperature shift, it is conceivable that among the fluids flowing in the pipe 10, only a part near the inner surface of the pipe 10 transfers the heat from the heater. Therefore, when the temperature boundary coefficient _YHT was introduced and recalculation was performed, the analytical value and the actual measurement value were in better agreement. In particular, by introducing both the heat transfer coefficient correction coefficient X _WT and the temperature boundary coefficient Y _HT , the analyzed value and the actually measured value were in better agreement.

_Making the value of the temperature boundary coefficient Y _HT smaller than 1 corresponds to reducing the amount of fluid that contributes to the heat transfer from the heater. When the amount of the fluid that contributes to the heat transfer from the heater is small, the value of the temperature difference Δt in Expression (2) (the temperature difference at the contact portion between the pipe 10 and the fluid in the pipe) is calculated to be large. By introducing a temperature boundary coefficient Y _HT by calculating the value of the temperature difference Δt of the formula (2) with high accuracy, it is possible to improve the accuracy of analysis of the temperature distribution in the pipe 10.

FIG. 6 is an explanatory diagram showing an example of setting the temperature boundary coefficient _YHT . In the figure, the temperature boundary coefficient Y for each of the cases where the flow rate is 10 m / s, 20 m / s, 30 m / s, and 40 m / s for the case where the fluid flowing in the pipe 10 is air and the case described above The example of the set value of _HT is shown.
By measurement of the temperature distribution described above, by reducing the value of the higher flow rate is high temperature boundary coefficient Y _HT 6, it was possible to bring the analysis of the temperature distribution in the measured value. Further, as shown in FIG. 6, the analysis value of the temperature distribution can be brought close to the actual measurement value by using the same value as the value of the temperature boundary coefficient Y _HT when the fluid is air and when the fluid is steam. It was

FIG. 7 is a graph showing a setting example of the temperature boundary coefficient. The horizontal axis of the figure shows the flow velocity of the fluid flowing in the pipe 10. The vertical axis represents the value of the temperature boundary coefficient.
The value of the temperature boundary coefficient _YHT shown in FIG. 7 is similar to the value of the temperature boundary coefficient _YHT shown in FIG. Specifically, in the range of the flow velocity of 10 m / s to about 31 m / s, the value of the temperature boundary coefficient Y _HT shown in FIG. 6 is a value obtained by linear interpolation. Further, in about 31m / s or more flow rates, the value of the temperature boundary coefficient _{Y HT} is constant (0.185).

Next, a method of setting the value of the heat transfer coefficient modification coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT will be described with reference to FIGS.
FIG. 8 is a diagram showing a schematic configuration of the relationship information setting system according to the present embodiment. Of the parts shown in FIG. 8, those parts corresponding to the parts in FIG. 1 and having the same functions are designated by the same reference numerals (2, 2b, 3, 4, 10, 20, 30) and description thereof will be omitted. .

The relationship information setting system 101 shown in FIG. 8 is provided with a flow velocity meter 5 in addition to each part of the flow velocity measurement system 100 shown in FIG. The relationship information setting system 101 has each part of the flow velocity measuring system 100 shown in FIG. 1, and also functions as a flow velocity measuring system.
The velocity meter 5 corresponds to an example of the velocity measuring unit, and measures the velocity of the fluid flowing in the pipe 10. By including the velocity meter 5, the relation information setting system 101 measures the temperature distribution in the pipe 10 and the flow velocity of the fluid flowing in the pipe 10. As a result, the relationship information setting system 101 acquires the correspondence relationship between the temperature distribution on the surface 10a of the pipe 10 and the flow velocity of the fluid flowing inside the pipe 10 in the measured value.
In addition, in the relation information setting system 101, the control unit 4 has a function of analyzing the heat transfer in the temperature steady state of the pipe 10 described above by the finite element method, in addition to the function of the control unit 4 in the flow velocity measurement system 100. have. The control unit 4 of the relationship information setting system 101 corresponds to an example of the flow velocity calculating unit in that it has the function of the control unit 4 in the flow velocity measuring system 100.

Here, if the temperature distribution and the flow velocity are measured for various flow velocities of the fluid flowing through the pipe 10, the related information to be stored in the memory 63 can be obtained. However, if all the related information is acquired by actual measurement, the number of times of measurement increases, and the user of the related information setting system 101 has a heavy burden of setting the related information setting system 101 (for example, a burden of adjusting the flow velocity of the fluid). Become.
Therefore, the control unit 4 analyzes the heat transfer in the temperature steady state of the pipe 10 by the finite element method for each flow velocity of the fluid, and acquires the related information. As a result, the burden on the user of setting the related information setting system 101 can be reduced. The control unit 4 corresponds to an example of the relationship information setting unit.

The control unit 4 analyzes the heat transfer in the temperature steady state of the pipe 10 based on the above-described equations (1) to (9). At that time, the control unit 4 sets the value of the heat transfer coefficient correction coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT in advance (before performing the analysis for acquiring the relationship information). The control unit 4 corresponds to an example of the heat transfer coefficient correction coefficient value acquisition unit.
The control unit 4 prepares, for example, a plurality of combinations of the value of the heat transfer coefficient modification coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT . The control unit 4 then, for the flow velocity measured by the relation information setting system 101 (flow velocity measured by the anemometer 5), for each combination of the value of the heat transfer coefficient correction coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT . An analysis by the finite element method is performed to calculate the temperature distribution in the pipe 10. Then, the control unit 4 adopts the combination of the value of the heat transfer coefficient correction coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT , which has obtained the analysis value closest to the actual measurement value of the temperature distribution in the pipe 10.

FIG. 9 is a graph showing an example of the actual measurement value and the analysis value of the temperature distribution in the pipe 10 before setting the value of the heat transfer coefficient correction coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT .
The horizontal axis of the figure shows the distance from the predetermined reference position in the flow direction of the fluid flowing in the pipe 10 (pipe axis direction of the pipe 10). The side with a smaller coordinate value indicates the upstream side of the fluid flow, and the side with a larger coordinate value indicates the downstream side of the fluid flow. The vertical axis represents temperature. The installation position of the heater of the heating unit 2 is a position with a coordinate value of 0.5 on the horizontal axis.

Further, each of the points P11 plotted in FIG. 9 indicates an example of the actual measurement value of the temperature distribution in the pipe 10 (the actual measurement value by the temperature measuring unit 3). The line L11 shows an example of the analysis value of the temperature distribution calculated by the control unit 4. The line L12 shows an example of the analysis value of the fluid temperature calculated by the control unit 4.
In the example of FIG. 9, there is a portion near the heater installation position (horizontal axis coordinate value 0.5) where the analyzed value of the temperature of the pipe 10 is higher than the measured value. Particularly, in the area A21, the analysis value of the temperature of the pipe 10 is higher than the actual measurement value. Further, even on the downstream side from the installation position of the heater, there are places where the analyzed value of the temperature of the pipe 10 is higher than the measured value.
Therefore, the control unit 4 sets the value of the heat transfer coefficient correction coefficient X _{WT as in} the example shown in FIG. 5, for example. By setting the value of the heat transfer coefficient correction coefficient X _WT larger than 1, the analysis value of the temperature of the pipe 10 becomes low. This corresponds to the pipe 10 being cooled by the fluid.
Further, in the example of FIG. 9, the analysis value of the temperature of the pipe 10 is lower than the actual measurement value in the region A22. Therefore, the control unit 4 sets the value of the temperature boundary coefficient _YHT as in the example shown in FIGS. 6 and 7, for example. As a result, the temperature of the fluid flowing through the pipe 10 is calculated to be high, and the temperature of the region A22 of the temperature distribution of the pipe 10 that receives heat from the fluid is also calculated to be high.

FIG. 10 is a graph showing an example of the actual measurement value and the analysis value of the temperature distribution in the pipe 10 after setting the value of the heat transfer coefficient correction coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT .
The horizontal axis and the vertical axis in FIG. 10 are similar to those in FIG. Further, the installation position of the heater of the heating unit 2 is also the position of the coordinate value 0.5 on the horizontal axis, as in the case of FIG.

Moreover, each of the points P11 plotted in FIG. 10 shows the same actual measurement value as in the case of FIG. On the other hand, the line L21 shows an example of the analysis value of the temperature distribution calculated by the control unit 4 in a state where the value of the heat transfer coefficient modification coefficient X _{WT and} the value of the temperature boundary coefficient Y _HT are set. The analysis value indicated by the line L21 is different from the analysis value indicated by the line L11 in FIG. The line L12 shows an example of the analysis value of the fluid temperature calculated by the control unit 4, as in the case of FIG.
Areas A21 and A22 correspond to areas A11 and A12 in FIG. 9, respectively.

In the example of FIG. 10, the analyzed value of the temperature of the pipe 10 and the measured value are substantially the same as in the example of FIG. In particular, in both the areas A21 and A22, the analyzed value of the temperature of the pipe 10 and the measured value are substantially the same.
Thus, by introducing the heat transfer coefficient correction coefficient X _WT and the temperature boundary coefficient Y _HT , the analysis accuracy of the temperature distribution of the pipe 10 by the control unit 4 is improved. This improves the accuracy of the relation information stored in the memory 63. Since the accuracy of the related information is improved, the accuracy of the flow velocity measurement value acquired by the control unit 4 by referring to the information is improved.

The flow velocity used by the control unit 4 (as the relation information setting unit) to set the relation information is not limited to the actual measurement value of the flow velocity by the flow velocity meter 5 (the flow velocity measured by the flow velocity meter 5). For example, the control unit 4 may use the flow velocity set when the heat transfer in the temperature steady state of the pipe 10 is analyzed by the finite element method as the flow velocity in the relation information. Alternatively, the control unit 4 may use the flow velocity estimated from the temperature distribution measured by the temperature measuring unit 3 as the flow velocity in the relation information.
In this case, the control unit 4 can bring the analysis value of the temperature distribution close to the actual measurement value by using the heat transfer coefficient correction coefficient when performing the analysis by the finite element method. As a result, when the control unit 4 (as the flow velocity calculation unit) obtains the flow velocity from the measured value of the temperature distribution, the difference between the measured value of the temperature distribution and the temperature distribution indicated in the relationship information becomes small. By reducing the deviation, the control unit 4 can accurately select the temperature distribution corresponding to the actual measurement value among the temperature distributions shown in the relationship information, and can acquire the flow velocity corresponding to the selected temperature distribution. . In this respect, the control unit 4 can accurately obtain the flow velocity.

As described above, the control unit 4 (heat transfer coefficient correction coefficient value acquisition unit) is a heat transfer coefficient correction coefficient for correcting the analysis value of the temperature distribution on the surface of the pipe 10 and is a predetermined portion (of the heater of the heating unit 2). Obtain the value of the heat transfer coefficient correction coefficient that takes a value according to the distance from the installation position). For example, the control unit 4 sets the value of the heat transfer coefficient correction coefficient based on the measured value of the temperature distribution measured by the temperature measuring unit 3 and the analyzed value of the temperature distribution acquired by the control unit 4 (analyzing unit). To do. Then, the control unit 4 (relationship information setting unit) acquires the relationship information based on the value of the set heat transfer coefficient modification coefficient.
As a result, in the relationship information setting system 101, the relationship information indicating the relationship between the temperature distribution of the pipe 10 and the flow velocity of the fluid flowing through the pipe 10 can be obtained more accurately than when the heat transfer coefficient correction coefficient is not used. Since the accuracy of the relationship information is high, when the control unit 4 (flow rate calculation unit) calculates the flow rate of the fluid using the relationship information, the flow rate can be accurately calculated.

Further, the control unit 4 (heat transfer coefficient correction coefficient value acquisition unit) acquires the value of the heat transfer coefficient correction coefficient for each position along the pipe 10. The position along the pipe 10 referred to here is a position in the direction of fluid flow indicated by an arrow B11 in FIGS. 2 and 4.
In this way, the control unit 4 (heat transfer coefficient correction coefficient value acquisition unit) acquires the value of the heat transfer coefficient correction coefficient for each position along the pipe 10, whereby the control unit 4 (relationship information setting unit) The value of the heat transfer coefficient correction coefficient corresponding to the position along the pipe 10 can be used, and the related information can be obtained with higher accuracy.

It should be noted that a program for realizing all or a part of the functions of the control unit 4 is recorded in a computer-readable recording medium, and the program recorded in this recording medium is read by a computer system and executed to execute each unit. You may perform the process of. The “computer system” mentioned here includes an OS and hardware such as peripheral devices.
The "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, the above program may be one for realizing some of the functions described above, and may be one that can realize the above functions in combination with a program already recorded in the computer system.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and can be modified as appropriate without departing from the spirit of the invention. For example, in the above-described embodiment, the configuration in which the heating unit 2 and the temperature measuring unit 3 (each temperature sensor 3a) are covered with the heat insulating material 12 in the pipe 10 is taken as an example, but the present invention is not limited to this. For example, if the control unit 4 corrects the measurement data (temperature distribution) sent from the temperature measuring unit 3 in consideration of heat radiation from the surface 10 a of the pipe 10, the surface 10 a of the pipe 10 is covered with the heat insulating material 12. You don't have to. Alternatively, the heat insulating material 12 may cover only a part of the surface 10a (where the temperature measuring unit 3 is installed).

  The fluid flowing in the pipe is not limited to steam or air. For example, the present invention can be applied to the case of measuring the flow velocity of hot water flowing in the pipe. The fluid flowing in the pipe may be chlorofluorocarbon, ammonia, LNG (Liquefied Natural Gas), etc., and the present invention is also applicable to the case of measuring the flow velocity of these fluids.

  Further, in the above-described embodiment, the heating unit 2 is exemplified as the heat exchanger that exchanges heat with the pipe 10, but the present invention is not limited to this. For example, as the heat exchanger, a cooler that cools the surface 10a of the pipe 10 may be used, and the flow velocity of the steam flowing in the pipe 10 based on the temperature distribution generated in the pipe axis direction of the pipe 10 by cooling. May be measured. In this case, when the steam is saturated steam or superheated steam close to it, there is a possibility that condensation will occur, so it is necessary to take this into consideration when calculating the heat transfer coefficient.

  Further, in both the flow velocity measuring system 100 (FIG. 1) and the relation information setting system 101 (FIG. 8), the preheater 2b is not an essential component. Either or both of the flow velocity measurement system 100 and the relation information setting system 101 may be configured without the preheater 2b.

2 ... Heating part, 2b ... Pre-heater, 3 ... Temperature measuring part, 4 ... Control unit, 5 ... Velocity meter, 10 ... Piping, 100 ... Velocity measuring system, 101 ... Relation information setting system.

Claims (8)

A relation information setting method for obtaining relation information indicating a relation between a flow velocity of a fluid flowing inside a pipe and a temperature distribution on the surface of the pipe,
A heat exchange step of performing heat exchange at a predetermined portion of the surface of the pipe,
An analysis step of obtaining an analysis value of a temperature distribution on the surface of the pipe in a state where heat exchange is performed in a predetermined portion of the surface of the pipe,
A heat transfer coefficient correction coefficient that takes a value according to a distance from the predetermined portion in the pipe axis direction of the pipe, and the larger the value of the heat transfer coefficient correction coefficient, the more the fluid flowing inside the pipe and the fluid. A heat transfer coefficient correction coefficient value acquisition step of acquiring the value of the heat transfer coefficient correction coefficient in which the heat transfer coefficient with the pipe wall of the pipe is set large,
A relationship information setting step of correcting the analysis value acquired in the analysis step based on the value of the heat transfer coefficient correction coefficient acquired in the heat transfer coefficient correction coefficient value acquisition step to obtain the relationship information,
Related information setting method including. In the heat transfer coefficient correction coefficient value acquisition step, the value of the heat transfer coefficient correction coefficient is acquired for each position along the pipe,
The related information setting method according to claim 1. A temperature measuring step of measuring a temperature distribution on the surface of the pipe in the pipe axis direction of the pipe in which heat exchange is performed in the predetermined portion,
A flow velocity measuring step of measuring the flow velocity of the fluid,
Including,
In the heat transfer coefficient correction coefficient value acquisition step, the heat transfer coefficient is based on the temperature distribution measured in the temperature measurement step, the analysis value of the temperature distribution acquired in the analysis step, and the flow velocity measured in the flow velocity measurement step. Set the value of the correction factor,
The relationship information setting method according to claim 1 or 2. In a state where the flow velocity of the fluid flowing inside the pipe is the flow velocity of the measurement target, a heat exchange step during flow velocity measurement for performing heat exchange at a predetermined portion of the surface of the pipe,
A flow velocity measuring temperature distribution measuring process for measuring a temperature distribution of the surface in the pipe axis direction of the pipe in which heat exchange has been performed in the predetermined portion in the flow velocity measuring heat exchange process,
Based on the temperature distribution measured in the temperature distribution measurement step during the flow velocity measurement and the relation information obtained by the relation information setting method according to any one of claims 1 to 3, the inside of the pipe is A flow velocity acquisition step of obtaining a flow velocity of the flowing fluid,
Flow velocity measuring method including. A relation information setting system for obtaining relation information indicating a relation between a flow velocity of a fluid flowing inside a pipe and a temperature distribution on the surface of the pipe,
A heat exchanger that performs heat exchange at a predetermined portion of the surface of the pipe,
An analysis unit that obtains an analysis value of a temperature distribution on the surface of the pipe in a state where heat exchange is performed at a predetermined portion of the surface of the pipe,
A heat transfer coefficient correction coefficient that takes a value according to a distance from the predetermined portion in the pipe axis direction of the pipe, and the larger the value of the heat transfer coefficient correction coefficient, the more the fluid flowing inside the pipe and the fluid. A heat transfer coefficient correction coefficient value acquisition unit for acquiring the value of the heat transfer coefficient correction coefficient in which the heat transfer coefficient with the pipe wall of the pipe is set large,
The analysis value acquired by the analysis unit is corrected based on the value of the heat transfer coefficient correction coefficient acquired by the heat transfer coefficient correction coefficient value acquisition unit, and a relationship information setting unit that obtains the relationship information,
Related information setting system. The heat transfer coefficient correction coefficient value acquisition unit acquires a value of the heat transfer coefficient correction coefficient for each position along the pipe,
The related information setting system according to claim 5. A temperature measuring unit that measures the temperature distribution of the surface of the pipe in the pipe axis direction of the pipe in which heat exchange is performed in the predetermined portion,
A flow velocity measuring unit for measuring the flow velocity of the fluid,
Equipped with
The heat transfer coefficient correction coefficient value acquisition unit is based on the temperature distribution measured by the temperature measurement unit, the analysis value of the temperature distribution acquired by the analysis unit, and the flow velocity measured by the flow velocity measurement unit. Set the value of the correction factor,
The related information setting system according to claim 5 or 6. A related information setting system according to claim 5 or claim 6,
A storage unit that stores the relationship information set by the relationship information setting unit;
A heat exchanger that performs heat exchange at a predetermined portion of the surface of the pipe in a state where the flow velocity of the fluid flowing inside the pipe is the flow velocity to be measured.
A temperature measuring unit that measures the temperature distribution of the surface of the pipe in the pipe axis direction of the pipe in which heat exchange is performed in the predetermined portion,
A temperature distribution measured by the temperature measurement unit, and a flow velocity calculation unit that calculates the flow velocity of the fluid based on the relation information stored in the storage unit,
Flow velocity measuring system.

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