Kinematic viscosity measuring system

Abstract

To measure kinematic viscosity in-line and in real time.SOLUTION: A flow velocity calculation circuit 106 determines a specific flow velocity from a flow rate measured by a thermal flowmeter 104 when a determination circuit 105 determines a laminar flow state, and a kinematic viscosity calculation circuit 107 divides a value obtained by multiplying the specific flow velocity by hydraulic diameter of a piping 101 by the Reynolds number at the fluid's specific flow velocity to determine the kinematic viscosity of the fluid. The kinematic viscosity calculation circuit 107, for example, determines the Reynolds number by dividing the distance between the thermal flowmeter 104 which has measured the specific flow velocity and a turbulent flow generating part 102 by the hydraulic diameter of the piping 101, then dividing the result by 0.065.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a kinematic viscosity measurement system. [Background technology]

[0002] Thermal flow meters include a method of measuring the flow rate from the temperature difference between the upstream and downstream of a heater, and a method of measuring the flow rate from the power consumption of the heater. For example, when measuring the flow rate of a liquid, the heater is operated by heating drive to a constant temperature, such as 10°C above the liquid temperature, and the flow rate is calculated from the temperature difference between the upstream and downstream or the power of the heater (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-010322 [Non-patent literature]

[0004] [Non-Patent Document 1] Akira Ito, "Velocity distribution in pipe flow, entrance region," Chemical Engineering Materials Page, Process Fluid Engineering, [Retrieved February 27, 2024], (https: / / chemeng.web.fc2.com / fl / fl7.html). Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the kinematic viscosity of the fluid being measured changes, the flow velocity distribution inside the pipe changes, making it impossible to accurately measure the flow rate with a thermal flow meter. Known methods for measuring kinematic viscosity include B-type viscometers and vibration viscometers. However, these kinematic viscometers cannot be used for in-line measurements, and therefore cannot be used when in-line, real-time kinematic viscosity measurement is required.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to measure kinematic viscosity in-line in real time. [Means for solving the problem]

[0007] The kinematic viscosity measurement system according to the present invention comprises a pipe that transports a fluid to be measured, a turbulence generating unit that is provided in the pipe and generates turbulence in the fluid, and a thermal flow meter that is located downstream of the turbulence generating unit, and is equipped with a flow velocity calculation unit that calculates a specific flow velocity of the fluid at a point where the fluid that has been made turbulent by the turbulence generating unit becomes a laminar flow, and a kinematic viscosity calculation circuit that is configured to calculate the kinematic viscosity of the fluid by multiplying the specific flow velocity by the hydraulic diameter of the pipe and dividing the result by the Reynolds number at the specific flow velocity of the fluid.

[0008] In one configuration example of the above kinematic viscosity measurement system, a laminarizing unit is provided in a pipe between the turbulence generating unit and the thermal flow meter to make the fluid flow laminar.

[0009] In one example configuration of the above-described kinematic viscosity measurement system, the flow velocity calculation unit includes a flow velocity control unit that changes the flow velocity of the fluid, a determination circuit that determines a laminar flow state in which the fluctuation of the measured value of the thermal flow meter is equal to or less than a set value while the flow velocity control unit is changing the flow velocity, and a flow velocity calculation circuit that calculates a specific flow velocity from the flow rate measured by the thermal flow meter when the determination circuit determines that the laminar flow state exists.

[0010] In one configuration example of the above kinematic viscosity measurement system, there is provided a thermal flow meter disposed at each of a plurality of locations downstream of the turbulence generating section, and the flow rate calculation section has a determination circuit that selects the thermal flow meter whose fluctuation in the measurement value is equal to or less than a set value and that is closest to the turbulence generating section, and a flow rate calculation circuit that determines a specific flow rate from the flow rate measured by the thermal flow meter selected by the determination circuit.

[0011] In one example of the configuration of the above kinematic viscosity measurement system, the kinematic viscosity calculation circuit determines the kinematic viscosity of the fluid using a Reynolds number of 2300.

[0012] In one example configuration of the above kinematic viscosity measurement system, the kinematic viscosity calculation circuit determines the Reynolds number as the value obtained by dividing the distance between the thermal flow meter that determined the specific flow velocity and the turbulence generating part by the hydraulic diameter of the piping and then dividing that value by 0.065. [Effects of the Invention]

[0013] As described above, according to the present invention, the specific flow velocity of the fluid at the point where the turbulent fluid becomes a laminar flow is determined by a thermal flowmeter placed downstream of the turbulence generating section, and the kinetic viscosity of the fluid is determined from the determined specific flow velocity, so that kinetic viscosity can be measured inline in real time. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a configuration diagram showing the configuration of a kinematic viscosity measurement system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram for explaining an example of determination by the determination circuit 105. In FIG. [Figure 3] FIG. 3 is a configuration diagram showing the configuration of a kinematic viscosity measurement system according to a second embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram for explaining an example of selection by the decision circuit 105a. [Figure 5] FIG. 5 is a characteristic diagram showing the relationship between the flow rate and the Reynolds number. [Figure 6] FIG. 6 is a diagram showing an example of the configuration of the turbulence generating unit 102a. [Figure 7] FIG. 7 is a diagram showing an example of the configuration of the laminarization unit 111. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] A kinematic viscosity measurement system according to an embodiment of the present invention will be described below.

[0016] [Embodiment 1] First, a kinematic viscosity measurement system according to a first embodiment of the present invention will be described with reference to Fig. 1. This system includes a pipe 101 that transports a fluid to be measured, and a turbulence generating unit 102 that is provided in the pipe 101 and generates turbulence in the fluid. The turbulence generating unit 102 is provided upstream of the pipe 101. The turbulence generating unit 102 can be formed, for example, from a bent pipe.

[0017] This system also includes a flow velocity calculation unit that is composed of a thermal flow meter 104 arranged downstream of the turbulent flow generating unit 102 and that calculates the specific flow velocity of the fluid at the point where the fluid that has been turbulent by the turbulent flow generating unit 102 becomes a laminar flow. The position where the thermal flow meter 104 is arranged is known, and the distance between the thermal flow meter 104 and the turbulent flow generating unit 102 is also known.

[0018] In the first embodiment, the flow rate calculation unit includes a flow rate control unit 103, a determination circuit 105, and a flow rate calculation circuit 106. The flow rate control unit 103 changes the flow rate of the fluid. The flow rate control unit 103 can be arranged, for example, upstream of the turbulence generation unit 102. The flow rate control unit 103 can also be arranged downstream of the thermal flow meter 104. The flow rate control unit 103 can be configured, for example, by a mass flow controller using a valve.

[0019] The determination circuit 105 determines whether a laminar flow state exists when the fluctuation in the measurement value of the thermal flow meter 104 is below a set value while the flow velocity control unit 103 is changing the flow velocity. For example, the set value can be a state where the fluctuation in the measurement value (flow rate value) fluctuates by 1% of the full scale output. The output used to determine the fluctuation can be the temperature difference between the upstream and downstream of the heater or the power consumption of the heater. The flow velocity calculation circuit 106 calculates the specific flow velocity from the flow rate measured by the thermal flow meter 104 when the determination circuit 105 determines the laminar flow state. For example, as shown in FIG. 2, when the determination circuit 105 determines that the fluctuation in the measurement value of the thermal flow meter 104 is below a set reference value A, the flow velocity value a at the time of this measurement is calculated as the specific flow velocity.

[0020] This system also includes a kinematic viscosity calculation circuit 107 that calculates the kinematic viscosity of the fluid by multiplying the specific flow velocity by the hydraulic diameter of the pipe 101 and dividing the result by the Reynolds number at the specific flow velocity of the fluid. For example, the kinematic viscosity calculation circuit 107 determines the Reynolds number by dividing the distance between the thermal flow meter 104, at which the specific flow velocity has been calculated, and the turbulent flow generating unit 102 by the hydraulic diameter of the pipe 101, and then dividing that value by 0.065.

[0021] When the determination circuit 105 determines that the thermal flow meter 104 is in a laminar flow state, where the fluctuation in the measurement value is below a set value, the installation position of the thermal flow meter 104 at the flow velocity at this time (specific flow velocity) can be determined as the point where the turbulent fluid flow changes to laminar flow. Furthermore, this point can be determined as the inlet distance from the turbulent flow generating section 102 when the fluid flow velocity reaches the specific flow velocity. As is well known, in the case of laminar flow, the relationship between the inlet distance x, the hydraulic diameter Dh of the pipe 101, and the Reynolds number Re is "x = 0.065 × Dh × Re." Therefore, it can be determined that "Re = x ÷ Dh ÷ 0.065" (Non-Patent Document 1).

[0022] According to the first embodiment, the kinetic viscosity of the fluid to be measured is determined from the measurement results obtained by the thermal flowmeter 104 provided in the pipe 101, so that the kinetic viscosity can be measured inline in real time.

[0023] [Embodiment 2] Next, a kinematic viscosity measurement system according to a second embodiment of the present invention will be described with reference to Fig. 3. This system first includes a pipe 101 that transports a fluid to be measured, and a turbulence generating unit 102 that is provided in the pipe 101 and generates turbulence in the fluid. The turbulence generating unit 102 is provided on the upstream side of the pipe 101. The turbulence generating unit 102 can be formed, for example, from a bent pipe.

[0024] The system also includes a flow velocity calculation unit that is composed of thermal flow meters 104a, 104b, 104c, 104d, and 104e that are respectively arranged at a plurality of locations downstream of the turbulent flow generating unit 102 and that calculates the specific flow velocity of the fluid at the location where the fluid that has been turbulent by the turbulent flow generating unit 102 becomes a laminar flow. The locations where the thermal flow meters 104a, 104b, 104c, 104d, and 104e are arranged are known, and the distance between each of the thermal flow meters 104a, 104b, 104c, 104d, and 104e and the turbulent flow generating unit 102 is also known.

[0025] In embodiment 2, the flow rate calculation unit includes a judgment circuit 105a that selects the thermal flow meter 104a, 104b, 104c, 104d, or 104e whose measurement value fluctuation is below a set value and that is closest to the turbulence generating unit 102, and a flow rate calculation circuit 106 that calculates a specific flow rate from the flow rate measured by one of the thermal flow meters 104a, 104b, 104c, 104d, or 104e selected by the judgment circuit 105a.

[0026] 4, the thermal flowmeter 104d, which is closest to the turbulence generating section 102, is selected by the judgment circuit 105a from among the thermal flowmeters 104d and 104e whose fluctuations in the measurement values ​​are equal to or less than the set value indicated by the dashed line. The flow rate calculation circuit 106 calculates the specific flow rate from the flow rate measured by the thermal flowmeter 104d selected by the judgment circuit 105a.

[0027] This system also includes a kinematic viscosity calculation circuit 107 that calculates the kinematic viscosity of the fluid by multiplying the specific flow velocity by the hydraulic diameter of the pipe 101 and dividing the result by the Reynolds number at the specific flow velocity of the fluid. For example, the kinematic viscosity calculation circuit 107 determines the Reynolds number by dividing the distance between the thermal flow meter 104, at which the specific flow velocity has been calculated, and the turbulent flow generating unit 102 by the hydraulic diameter of the pipe 101, and then dividing that value by 0.065.

[0028] According to the second embodiment, the kinetic viscosity of the fluid to be measured is determined from the measurement results of the thermal flow meters 104a, 104b, 104c, 104d, and 104e provided in the pipe 101, thereby enabling in-line real-time measurement of the kinetic viscosity.

[0029] Here, the kinematic viscosity calculation circuit 107 can calculate the kinematic viscosity of the fluid using a Reynolds number of 2300. As is well known, the Reynolds number (critical Reynolds number) at which a laminar flow changes to a turbulent flow has been experimentally determined by Reynolds to be 2300 (FIG. 5).

[0030] As shown in FIG. 6, a turbulent flow generating section 102a can be formed by a location where the pipe diameter (hydraulic diameter) suddenly changes (becomes smaller). Also, as shown in FIG. 7, a laminarizing section 111 that laminarizes the fluid flow can be provided in the pipe 101a between the turbulent flow generating section 102 and the thermal flow meter 104. The laminarizing section 111 can be formed by a section where the pipe diameter gradually decreases. Also, the laminarizing section 111 can have a mesh-like structure. By providing the laminarizing section 111, the inlet distance of the turbulent flow generated in the turbulent flow generating section until it becomes laminar can be shortened, thereby enabling the system to be made more compact.

[0031] As described above, according to the present invention, the specific flow velocity of the fluid at the point where the turbulent fluid becomes a laminar flow is determined by a thermal flowmeter placed downstream of the turbulence generating section, and the kinematic viscosity of the fluid is determined from the determined specific flow velocity, thereby enabling in-line measurement of kinematic viscosity in real time.

[0032] Some or all of the above-described embodiments may also be described as, but are not limited to, the following supplementary notes.

[0033] [Appendix 1] a flow velocity calculation unit that calculates a specific flow velocity of the fluid at a point where the fluid, which has been made turbulent by the turbulence generating unit, becomes a laminar flow; and a kinematic viscosity calculation circuit that is configured to calculate the kinematic viscosity of the fluid by multiplying the specific flow velocity by the hydraulic diameter of the pipe and dividing the result by the Reynolds number of the fluid at the specific flow velocity.

[0034] [Appendix 2] 2. The kinematic viscosity measurement system according to claim 1, further comprising a laminarizing unit provided in the piping between the turbulence generating unit and the thermal flow meter to make the flow of the fluid laminar.

[0035] [Appendix 3] In the kinematic viscosity measurement system described in Supplementary Note 1 or 2, the flow rate calculation unit includes: a flow rate control unit that changes the flow rate of the fluid; a determination circuit that determines a laminar flow state in which fluctuations in the measurement value of the thermal flow meter are equal to or less than a set value while the flow rate control unit is changing the flow rate; and a flow rate calculation circuit that calculates the specific flow rate from the flow rate measured by the thermal flow meter when the determination circuit determines that the laminar flow state exists.

[0036] [Appendix 4] The kinematic viscosity measurement system according to Supplementary Note 1 or 2, further comprising the thermal flow meters disposed at a plurality of locations downstream of the turbulent flow generating section, wherein the flow rate calculation section comprises a determination circuit that selects the thermal flow meter whose fluctuation in measurement value is equal to or less than a set value and that is closest to the turbulent flow generating section, and a flow rate calculation circuit that calculates the specific flow rate from the flow rate measured by the thermal flow meter selected by the determination circuit.

[0037] [Appendix 5] 5. The kinematic viscosity measurement system according to any one of claims 1 to 4, wherein the kinematic viscosity calculation circuit determines the kinematic viscosity of the fluid using a Reynolds number of 2300.

[0038] [Appendix 6] In the kinematic viscosity measurement system described in any one of Supplementary Notes 1 to 4, the kinematic viscosity calculation circuit sets the Reynolds number to a value obtained by dividing the distance between the thermal flowmeter, which has determined the specific flow velocity, and the turbulence generating part by the hydraulic diameter of the piping, and then dividing the result by 0.065.

[0039] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0040] 101...piping, 102...turbulence generating section, 103...flow rate control section, 104...thermal flow meter, 105...determination circuit, 106...flow rate calculation circuit, 107...kinematic viscosity calculation circuit.

Claims

1. A pipe for transporting a fluid to be measured; a turbulence generating section provided in the pipe for generating turbulence in the fluid; a flow velocity calculation unit that is composed of a thermal flow meter arranged downstream of the turbulence generating unit and that calculates a specific flow velocity of the fluid at a location where the fluid that has been made turbulent by the turbulence generating unit becomes a laminar flow; a kinematic viscosity calculation circuit configured to calculate the kinematic viscosity of the fluid by multiplying the specific flow velocity by the hydraulic diameter of the pipe and dividing the result by the Reynolds number of the fluid at the specific flow velocity; A kinematic viscosity measurement system comprising:

2. 2. The kinematic viscosity measurement system according to claim 1, The kinematic viscosity measurement system further comprises a laminarizing unit provided in the piping between the turbulence generating unit and the thermal flow meter to make the flow of the fluid laminar.

3. 2. The kinematic viscosity measurement system according to claim 1, The flow velocity calculation unit a flow rate control unit that changes the flow rate of the fluid; a determination circuit that determines a laminar flow state in which fluctuations in the measured value of the thermal flow meter are equal to or less than a set value during the process in which the flow rate control unit changes the flow rate; a flow velocity calculation circuit that calculates the specific flow velocity from the flow rate measured by the thermal flow meter when the determination circuit determines that the flow is in a laminar flow state; A kinematic viscosity measurement system having

4. 2. The kinematic viscosity measurement system according to claim 1, the thermal flowmeter is disposed at each of a plurality of locations downstream of the turbulent flow generating section, The flow velocity calculation unit a determination circuit for selecting the thermal flow meter whose fluctuation in the measurement value is equal to or less than a set value and which is closest to the turbulence generating portion; a flow rate calculation circuit that calculates the specific flow rate from the flow rate measured by the thermal flow meter selected by the determination circuit; A kinematic viscosity measurement system having

5. The kinematic viscosity measurement system according to any one of claims 1 to 4, The kinematic viscosity calculation circuit is a kinematic viscosity measurement system that calculates the kinematic viscosity of the fluid using the Reynolds number of 2300.

6. The kinematic viscosity measurement system according to any one of claims 1 to 4, The kinematic viscosity calculation circuit determines the Reynolds number by dividing the distance between the thermal flowmeter, which has calculated the specific flow velocity, and the turbulence generating portion by the hydraulic diameter of the pipe, and then dividing the result by 0.

065. Kinematic viscosity measurement system.

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