JPH08201130A - Method of measuring flow rate of two-phase fluid with turbine type flowmeter - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method for efficiently determining a total volumetric flow rate, a gas-liquid volumetric flow rate ratio, and a total mass flow rate at the same time while a two-phase fluid of liquid and gas remains in a mixed phase flow. [Structure] The turbine type flow meter measures the rotational speed of the rotating body, the current value of the induced electromotive force due to the rotation, and the pressure difference between the inlet side and the outlet side. When the pressure difference increases, the gas-liquid volume increases.
A relational expression flow ratio increases, based on a relational expression total volume flow with increasing gas-liquid volumetric flow rate ratio is increased, on the basis of the relational expression obtained by erasing the gas-liquid volumetric flow ratio, the total volume flow rate Then, based on the relational expression that the gas-liquid volumetric flow rate ratio increases as the total volumetric flow rate increases, the gas-liquid volumetric flow rate ratio is calculated,
Then, the total mass flow rate, gas-liquid volumetric flow rate ratio, and It consists of simultaneously determining the mass flow rate for practical purposes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the flow rate of a two-phase fluid composed of a liquid and a gas by a Turbin type flow meter when the liquid and the gas are flowing in a mixed phase flow state. In particular, the present invention relates to a method for measuring the above flow rate in the state of multiphase flow. The present invention is applied to all technical fields that require measurement of the total volumetric flow rate, the gas-liquid volumetric flow rate ratio, and the total mass flow rate of the two-phase fluid in such a mixed-phase flow state. It can be done.

[0002]

2. Description of the Related Art As a conventional technique for measuring the flow rate of a two-phase fluid of liquid and gas, after separating the gas and the liquid,
Each was measured in a single-phase flow state. However, recently, a so-called two-phase flow measurement technique for simultaneously measuring the flow rates of the liquid and the gas without separating the liquid and the gas in the mixed phase flow has been developed, which is as follows. Is.

Whereas the volumetric flow measurement of a single-phase fluid is obtained by using an orifice or nozzle to measure only the differential pressure before and after the fluid enters the flowmeter, 2
The measurement of the volume flow and mass flow rate of the phase fluid, in a two-phase fluid, the void ratio alpha, or the average density and the phases of the phase velocity v _w, it is necessary to measure the v _g, these measurement target factor It is necessary to construct a complicated system that combines the measuring instruments for each. In order to measure the mass flow rate of the two-phase fluid, the void ratio α or the density ρ of each phase is used.
_It is necessary to measure _w , ρ _g and phase velocities v _w , v _g .

Conventionally, in order to obtain the volumetric flow rate or mass flow rate of a two-phase fluid, first, the void fraction α of the two-phase fluid or the densities ρ _w and ρ _g of each phase are _calculated by a capacitance meter and a neutron density. Meter, γ-ray densitometer, microwave, etc., and then the flow velocity and flow rate are measured by the orifice type flow meter and the turbine type flow meter of the contact type flow meter, or the ultrasonic flow rate meter of the non-contact type flow meter. Attempts have been made to measure such as.

The method of measuring the flow velocity and flow rate of a fluid is roughly classified into a contact type measuring method and a non-contact type measuring method, and there are the following measuring methods. The contact-type measurement method includes a tracer method and a thermal probe method.
Valve, pit-tube, throttle flow meter (orifice, venturi,
Nozzle, etc.), a resistance plate (strain gauge), a turbine type flow meter, and a multi-function measuring method (which simultaneously measures two or more variables with a single measuring instrument). Non-contact measurement methods include electromagnetic flowmeters, ultrasonic or acoustic measurement methods, mass flowmeters, cross-correlation methods, and computer tomography (CT).

As another two-phase fluid measuring technique, there is a homogeneous measuring method which can treat the two-phase fluid sufficiently like a single-phase flow by homogenizing it sufficiently. In this method, the average density and average flow velocity of the two-phase fluid are
It is necessary to obtain the mass flow rate by using a measuring instrument similar to the above-mentioned instrument.

[0007]

Recently, in the marine petroleum related field, the measurement accuracy of the mass flow rate of each phase of a two-phase fluid is ± 5.
It is required to be within%. Furthermore, the response is fast (100 μs or less) and the pressure loss is small (1
00 kPa or less), low cost measurement, durable equipment, and good maintainability are required.

However, in the above-mentioned conventional technique,
When measuring the volume flow rate and the mass flow rate of each phase of a two-phase fluid, a method of adopting a flow meter suitable for each phase after separating a liquid and a gas has been adopted. The development of a method for measuring theoretically required measurement items with a complicated device configured by combining multiple instruments has been started. However, with such technology,
It is difficult to solve the above problems.

Therefore, it is an object of the present invention to allow the flow rates of liquid and gas in a two-phase fluid to remain simultaneously and to remain a multiphase flow in order to be able to meet the conditions desired in the marine petroleum context described above. An object of the present invention is to provide a method capable of performing measurement in a state and inexpensively using a device having a simple structure.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies and experiments in order to solve the above problems, and as a result, completed the present invention by the following means.

According to the method for measuring the flow rate of a multiphase fluid by the turbine type flowmeter (first invention) of the present invention, the flow rate of a two-phase fluid of a liquid and a gas is determined as a mixed phase flow of the liquid and the gas. A method of measuring with a turbine type flow meter as it is,
The number of revolutions of the rotating body of the turbine type flow meter, the current value of the induced electromotive force generated with the rotation of the rotating body, and the inlet side of the two-phase fluid with respect to the turbine type flow meter. Each of the pressure differences between the outlet and the outlet is measured, and then the relational expression (16) in which the pressure difference increases and the gas-liquid volume flow ratio increases. Based on the relational expression (14) that the total volumetric flow rate of the phase fluid increases,
Based on the relational expression (20) obtained by eliminating the gas-liquid volumetric flow ratio, the total volumetric flow rate is obtained, and then, when the total volumetric flow rate thus obtained increases, the gas-liquid volumetric flow rate ratio is increased. Is calculated based on the relational expression (17) that increases the total mass flow rate, and then the total mass flow rate increases regardless of which of the current value and the rotation speed increases. It is characterized in that the total mass flow rate, the gas-liquid volumetric flow rate ratio, and the total mass flow rate are simultaneously obtained in practical use by obtaining the total mass flow rate based on the equation (19).

Further, a second invention is the same as the first invention, except that the relational expressions (14), (16), (17), (19) and (20) are used.
Is the following step: Ratio Δp / of the pressure difference Δp between the fluid before and after the _Turbin type flow meter in the case of two-phase flow and the pressure difference Δp _l0 between the fluid before and after the flow meter in the case of liquid single-phase flow.
The following relational expression (16) between Δp ₁₀ and the void fraction α of the two-phase fluid: Δp / Δp _lo = (1-α) ^-h --------------- ------ (16) However, so that h: constant holds, Δp and Δp obtained by multiple experiments in advance.
_The constant h is determined by the combination of the value with _l0 and the function of equation (16) is specified, and α is Δp / Δp according to equation (16).
It is expressed by a function of _lo , and then the following equation (14): Q _tp = Ar _m ω / ε _tp = f ₁ (ω, α) ------------------- (14) where ε _tp is a two-phase flow rotation ratio, and ε _tp = Ar _m ω / Q _tp = e ₁ −e ₂ λ _tp where e ₁ = tan β _rm / (1 + κ) e ₂ = A / By substituting the above α represented by the function of Δp / Δp _lo into r _m ² (1 + κ) λ _tp = r _m M _tp / GQ _tp , α is eliminated and the following nonlinear equation (20): Q _tp = f ₄ (ω, Δp, Q _tp ) ------------------------- _Find (20) and solve the nonlinear equation (20). obtains a total volume flow Q _tp, then, in this way the total volume flow Q _tp obtained, and the data in the case of the two-phase flow - the pressure difference Δp bottle flow meter before and after the fluid, formula _{(17): Δp = c 3} (1-α) -h {(1-α) Q tp} 2 ---------------- (17) However, c ₃ And h is a constant, by substituting c _3, the previously determined in the same manner as obtaining the h described above, to calculate the void fraction alpha, i.e., determine the gas-liquid volumetric flow ratio, and, then , The total volumetric flow rate Q _tp obtained by the relational expression (16), the angular velocity ω of the rotating body obtained from the number of rotations of the rotating body of the turbine type flow meter, and the rotation of the rotating body. the value i of the induced electromotive force current generated Te, formula _{(19): i = c 4} (ωGQ tp / r m) · {c 1 -c 2 (1-α) d} ------ ---------- (19) where c ₁ , c ₂ , c ₄ and d are constants, and c ₂ ,
By substituting c ₄ and d in the same manner as the above-described method of obtaining c ₃ , the total mass flow rate G is obtained by the following relational expressions (14), (16), (17),
(19) and a (20), symbols and indices in the equation is the symbol: A: cross-sectional area of impeller ^{_{= π (r s 2 -r b}} 2) κ: Slip Coefficient of the impeller M: shaft torque of the impeller G: mass flow p: pressure Delta] p: data - the pressure difference of the fluid before and after the bottle flow meter) Q: volume flow rate r: radius r _m: average radius ^{_{= √ {(r s 2 +}} r b 2) / 2} α: Void ratio ε: Rotation ratio = Ar _m ω / Q ω: Rotational angular velocity of the rotating body c ₁ , c ₂ , c ₃ , c ₄ : Constant d: Constant h: Constant F: Function Subscript: w: liquid phase tp: two-phase flow 0: single-phase flow 1: impeller inlet side 2: exit of the impeller-side r _m: characterized in that the average radius = a ^{_{√ {(r s 2 + r}} b 2) / 2} Is to have.

[0013]

According to the present invention, the flow rate of the two-phase fluid of liquid and gas is generated in accordance with the rotation speed of the rotating body and the rotation of the rotating body while maintaining the mixed phase flow of the liquid and gas. Each of the current value of the induced electromotive force and the pressure difference between the inlet side and the outlet side of the flow meter to be used are simultaneously measured using the turbine type flow meter, and the turbine is converted into a single-phase flow. The flow rate measurement method in the case of applying the type flow meter was examined, and a new flow rate measurement method in which the turbine type flow meter was applied to the two-phase flow was found by applying this method. Here, the Turbin type flow meter is required to have a configuration capable of measuring all of the rotation speed, the current value and the pressure difference. As a result, the total volumetric flow rate, the gas-liquid volumetric flow rate ratio, and the total mass flow rate of the two-phase fluid are simultaneously determined practically by using the Turbin type flow meter while maintaining the state of the mixed phase flow of liquid and gas. I was able to do it.

In a mixed-phase fluid of liquid and gas, there are a plurality of kinds of liquid substances, for example, in the case of marine petroleum, oil and water are mixed, and further gas is mixed. In the present invention, the two-phase fluid of liquid and gas is included, including the case of such a mixed-phase fluid.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example of an apparatus used for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a meridional section showing an example of a Turbin type flow meter used for carrying out the measuring method of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

This turbine type flow meter is shown in FIGS.
As shown in FIG. 1, the impeller 1 is installed inside the casing 15 of this flow meter. The impeller 1 includes a rotating shaft 3 supported by bearings 2a and 2b formed integrally with the front guide vane 5a and the rear guide vane 5b, and a plurality of blades 4 attached to the rotating shaft 3. It consists of A front guide vane 5a and a rear guide vane 5b are provided on both sides of the impeller 1, that is, on an inlet side 6 and an outlet side 7 inside the flow meter, and a fluid homogenizer 8 is provided in front of the front guide vane 5a. Has been.

On the other hand, on the outside of the casing 15, a pickup coil 11 composed of a magnet 10 around which a coil 9 is wound is fixed in proximity to the impeller 1, and the pickup coil 11 has an ammeter 12 and a frequency meter. 13 and resistor 14
A circuit including is connected. Further, pressure gauges 16a and 16b having detection ends inside the casing 15 are provided on the inlet side to the fluid homogenizing device 8 and the outlet side from the impeller 1, respectively.

The vane 4 has flat blades whose shape is twisted and is fixed radially around the rotary shaft 3, and the gas-liquid 2
It is designed to have a wide range of flow rate measurement for the phase fluid flow measurement, and high performance such as high accuracy. The material is a magnetic body. Fluid homogenizer 8
When the two-phase fluid consisting of liquid and gas homogenized by is guided to the impeller 1 by the front guide vane 5a and collides with the impeller 4, the impeller 1 rotates about the rotating shaft 3. Along with this rotational movement, an induced electromotive force is generated when the magnetic blade 4 crosses the vicinity of the pickup coil 11, and the current value generated by this induced electromotive force is measured by the ammeter 12. Further, the frequency meter 13 measures the fluctuation frequency of the induced current. The shaft torque of the impeller 1 is measured from the absolute value (effective value) of the current value, and the rotational speed and the rotational angular velocity of the impeller 1 are measured at the frequency. On the other hand, the pressure difference between before and after the impeller 1 is obtained by the pressure gauges 16a and 16b.

With the Turbin type flow meter having the above-mentioned structure, the volume flow rate and mass flow rate of the two-phase fluid consisting of liquid and gas can be efficiently measured with the multi-phase fluid as it is.

In the following, in the embodiments of the present invention, the flow rate of the two-phase fluid of liquid and gas is measured by the Turbin type flow meter while maintaining the state of multiphase flow, that is, the Turbin type. The rotation speed measured by the flow meter, the current value of the induced electromotive force, and the pressure difference between the inlet side and the outlet side of the Turbin type flow meter are used to determine the entire two-phase fluid. An example of a method for simultaneously obtaining the product flow rate, the gas-liquid volume flow rate ratio, and the total mass flow rate will be described.

First, how to obtain the volumetric flow rate, void fraction, mass flow rate, etc. when the turbine type flow meter shown in FIG. 1 is used for a single-phase flow will be described, and then the results regarding this single-phase flow will be described. Is applied to a two-phase flow, and using the turbine type flow meter shown in FIG.
A method of obtaining the void rate, the total mass flow rate, etc. will be described. The contents and definitions of the symbols and subscripts showing the respective physical quantities used in the following description are shown at the end of the examples described later.

1. When a turbine type flow meter is applied to a single-phase flow The impeller of the turbine flow meter is an axial flow meter, and consider a blade row in which an impeller portion (blade element) with a small radius Δr at a radius r is developed. The blades are twisted flat blades, and are designed so that the blade angle β _r formed by the circumferential direction opposite to the rotating direction is proportional to the radius r. That is, tan β _r / r = c _l (constant) --------------------------- (1)

Assuming that the flow velocity υ _{a in the} direction of the rotation axis is uniform in the circumferential direction and the impeller is rotating at a constant angular velocity ω, the torque ΔM acting on this blade element due to the flow is the circumferential velocity before and after the blade. Proportional to the component difference (υ _u1 -υ _u2 ). That is, ΔM = ρr (2πrΔrυ _a ) (υ _u1 -υ _u2 ) ----------- (2)

Immediately after the homogenizer, the flow at the inlet of the impeller has no pre-whirl and νμ ₁ = 0. Further, the peripheral velocity at the outlet of the impeller flows at an angle different from the blade angle due to the finite number of blades and the viscosity of the flow, and the slip velocity κrω occurs. Therefore, the following equation is obtained from the velocity triangle. υ _u2 = (1 + κ) rω−υ _a tanβ _r -------------- (3) Assuming that υ _a and κ are constant in the radial direction, the equation (2) is changed to Integrating from the boss surface r _b to the shroud surface r _s (from the blade root to the tip) and using the continuous condition ν _a A = Q, the following equation is obtained. M = (πρ / 2) υ a {c l υ a -ω (1 + κ)} (r s 4 -r b 4) ------------------ (4)

The blade angle β _r is the value r at the average radius rm
_When represented by _m , equation (4) can be transformed into the following equation. The torque M is equal to the sum of the torque due to the circumferential component of the force acting on the blade due to the fluid and the torque due to the bearing friction. By transforming the equation (5) and expressing the torque dimensionlessly,

The left side of the above equation is a characteristic number defined as the ratio of the rotational angular velocity ω of the flowmeter to the volumetric flow rate Q, so this is defined as the rotational ratio ε. The first term on the right side of the above equation is a constant determined by the shape of the blade, and e ₁ {= tan β _rm / (1+
κ)}, a value determined by the shape and structure of the impeller of the second term, and if e ₂ {= A / r _m ² (1 + κ)}, then equation (5) can be expressed as the following equation. ε = e ₁ -e ₂ λ ------------------------------- (7) However, e ₂ is usually 0. is about 5~5, λ (= r _m
The order of (M / GQ) is 10 ^-2 at the maximum, and in comparison with this, in general, it is so small and negligible that ε = e ₁ , that is,
ω / Q = constant. Therefore, the volume flow rate Q can be measured by measuring the rotational angular velocity ω.

2. Applying a turbine flow meter to two-phase flow Assuming that the flow angle of each phase in the gas-liquid two-phase flow with respect to the rotation axis direction is the same as that in single-phase flow, applying the separated flow model The torque ΔM _tp during phase flow has the following relationship. ΔM _tp = [2πρ _g αυ _ag {c ₁ υ _ag -ω (1 + κ)} r ³ + 2πρ (1-α) υ _aw {c ₁ υ _aw −ω (1 + κ) r ³ }] Δr ------ ------------ (8)

Here, the value of the slip coefficient κ is the same as that in the single-phase flow, and α, υ _al and υ _ag are considered to be constant in the r direction, and equation (8) is integrated in the same manner as in the single-phase flow. By rearranging, the following formula is obtained.

However, Q _tp = Q _w + Q _g = A {αυ _ag +
(1-α) υ _aw }, G = A {ρ _g αυ _ag + ρ _w (1-
α) υ _aw }. Slip ratio s, two-phase flow coefficient a
When transformed using (= {α / (1-α)} (ρ _g / ρ _w )) _, Of the torque M _tp acting on the impeller during the two-phase flow, the torque due to the bearing friction is considered to remain unchanged even during the two-phase flow, but the torque due to the fluid force changes depending on the void ratio and the like.

When Ar _m ω / Q _tp = ε _tp , the equation (10) can be transformed into the following equation similar to the equation (7) at the time of single-phase flow. Since the axial pressure gradient in the impeller immediately after the homogenizing device is small, the gas-liquid relative velocity here is small and the slip ratio s is 1. In this case, the gas-liquid volume flow rate ratio β is equal to the void ratio α, that is, β = α. Further, in the range of α ≦ 0.9 where the void rate α is not large, the two-phase flow coefficient a is negligibly small as compared with 1. Therefore,
The first term on the right side of the equation (11) is substantially equal to the value e ₁ in the single-phase flow, and therefore can be expressed by the following equation similar to that in the single-phase flow. _{ε tp = e 1 -e 2 λ} tp ----------------------- (12) _{where, λ tp (= r m M} tp / GQ tp) Is the blade load coefficient of two-phase flow that represents the torque generation rate due to the flow, and is a function of the blade shape and void rate.

In the two-phase flow, it was found from the experimental results that each item has the following characteristics. ε _tp = c ₁ -c ₂ (1-β) ^d = c ₁ -c ₂ (1-α) ^d ------------------------ -(13) However, c ₁ , c ₂ and d are constants. Therefore, the formula (1
The following equation is obtained from 1). Q _tp = Ar _m ω / ε _tp = f ₁ (ω, α) --------------------- (14)

On the other hand, the differential pressure before and after the flow meter in the single-phase flow can be generally expressed by the following equation. Δp _w = ζ (1/2 g) (Q _w / A) ² = c ₃ Q _w ² ----------- (15) Install the turbine flow meter installed horizontally and the homogenizer. The included pressure difference Δp (= p ₁ −p ₂ ) before and after the measuring device is a loss pressure based on the viscosity of the fluid. ζ is a constant. This value is the same as the loss pressure when flowing not only through a straight pipe but also through an elbow or a valve, and is based on the experimental results between the ratio of loss pressure between two-phase flow and single-phase flow, that is, the loss pressure ratio. It was found to have the following properties: That is, Δp / Δp _lo = (1-α) ^-h --------------------- (16) where Δp _lo is the liquid phase in the two-phase flow It is the virtual loss pressure when only one flows to fill the cross section of the pipe. Also, h
Is a constant. From equations (15) and (16), the pressure loss of the two-phase flow is expressed by the following equation from Q _w = (1−α) Q _tp . Δp = c ₃ (1-α) ^-h {(1-α) Q _tp } ² --------------- (17) = f ₂ (Q _tp , α)

From the expressions (11), (12) and (13), the two-phase flow torque M _tp is given by the following expression. _{M tp = (GQ tp / r} m) · {c 1 -c 2 (1-α) d} / e 2 ---------------------- ( 18) On the other hand, the effective value i of the current is proportional to ωM _tp . Therefore, if the constant of proportionality is c ₄ , then i = c ₄ (ωGQ _tp / r _m ) · {c ₁ −c ₂ (1-α) ^d } ----- (19) = f ₃ (G, Q _tp , ω, α)

Using the results obtained from all the above equations, when the rotational angular velocity ω, the pressure difference Δp and the current value i of the Turbin type flow meter are known,
It is possible to calculate the volume flow rate and the mass flow rate of the two-phase flow.

When Equation (16) is solved for α and is substituted into Equation (14) to eliminate α, Q _tp = f ₄ (ω, Δp, Q _tp ) ---------- ------------- (20) (20) is a non-linear equation for Q _tp, can be solved by repeated several times calculation of, it is possible to determine the Q _tp. Therefore, Q _tp can be obtained from ω and Δp.

Substituting Q _tp obtained in step (17) into equation (17) gives the void fraction α. Therefore, α can be obtained from Q _tp and Δp.

From Q _tp and α obtained in and, the volumetric flow rate Q _{g of the} two-phase fluid and the volumetric flow rate Q _{w of the} liquid phase are expressed as Q _g = Q _tp × α and Q _w = Q _tp ×
It can be calculated by (1-α).

Q _tp obtained in, the impeller angular velocity ω obtained from the impeller rotation speed, the void fraction α, and
By substituting the current value i into the equation (19), the total mass flow rate G can be obtained.

Considering that the value of ρ _g / ρ _w is sufficiently smaller than 1 using G, Q _tp and α obtained as described above, the mass flow rate G _l of the liquid phase and the liquid phase The density ρ _l can be obtained.

As described above, by using the turbine type flowmeter as shown in the embodiment of the present invention and the knowledge about the method for measuring the two-phase fluid described in detail above, the gas-liquid mixed phase flow can be obtained. It will be understood that the total volumetric flow rate, gas-liquid flow rate ratio, and total mass flow rate of the two-phase flow can be simultaneously measured. The contents and definitions of the symbols and subscripts of each physical quantity used in the description of the present invention are summarized below.

[0041] Symbol: A: cross-sectional area of impeller ^{_{= π (r s 2 -r b}} 2) κ: Slip Coefficient of the impeller M: shaft torque of the impeller G: mass flow p: Pressure Delta] p: data - Bin type pressure difference of the fluid in the flow meter before and after) Q: volume flow rate r: radius r _m: average radius ^{_{= √ {(r s 2 +}} r b 2) / 2} α: void ratio epsilon: rotation ratio = Ar _m ω / Q ω: Rotational angular velocity of the rotating body c ₁ , c ₂ , c ₃ , c ₄ : constant d: constant h: constant a: two-phase flow coefficient = {α / (1-α)} (ρ _g / ρ _w ) D : diameter of the turbine flow meter (= 50 mm) j: flux ^{= Q / (πD 2/4} ) ζ: loss pressure coefficient s: gas-liquid flow rate slip ratio = υ _g / υ _w υ: flow rate beta: liquid volume Flow rate = Q _g / (Q _w + Q _g ) β _r : Blade angle λ: Blade load coefficient (= r _m M / GQ) ρ: Density g: Gravity acceleration f _1, f _2, f _3, f ₄ : function

The subscript: w: liquid phase tp: Two-Phase Flow 0: single-phase flow 1: entry side of the impeller 2: impeller exit side rm: average radius ^{_{= √ {(r s 2 +}} r b 2) / 2 } A: Axial component b: Boss surface E: Calculated value w: Liquid phase g: Gas phase n: Normal direction component s: Shroud surface u: Circumferential component

[0043]

As described above, according to the present invention,
It is possible to measure the total volumetric flow rate, the gas-liquid volumetric flow rate ratio, and the total mass flow rate with high accuracy in a two-phase fluid flow of a liquid and a gas in a mixed phase flow state, and at the same time with high accuracy. It has a simple structure and can be inexpensively measured by a highly durable device. Therefore, for example, it is possible to obtain a particularly excellent effect in the flow rate measurement of the gas-liquid mixed phase flow in the marine oil related field, etc.
It is possible to provide a method for measuring the flow rate of a phase fluid, and to bring about an extremely useful effect industrially.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a meridional section showing an example of a Turbin type flow meter used for carrying out the measuring method of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Impeller 2a Bearing 2b Bearing 3 Rotating shaft Chi 4 Blade 5a Front guide vane 5b Rear guide vane 6 Inlet side 7 Outlet side 8 Fluid homogenizer 9 Coil 10 Magnet 11 Pickup coil 12 Ammeter 13 Frequency meter 14 Resistance 15 units -Thing 16a Pressure gauge 16b Pressure gauge 17 Magnetic material

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[Procedure amendment]

[Submission date] March 23, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

Recently, in the marine petroleum related field, the measurement accuracy of the mass flow rate of each phase of a two-phase fluid is ± 5.
It is required to be within%. Furthermore, the response is fast (100 ms or less), and the pressure loss is small (1
00 kPa or less), that it can be inexpensively measured, that it is a durable device, and that it has good maintainability.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

A method for measuring a flow rate of a multiphase fluid by a turbine type flow meter (first invention) according to the present invention is a method for measuring a flow rate of a liquid and a gas.
A method of measuring a flow rate of a phase fluid by a turbine type flow meter in a mixed phase flow state of the liquid and the gas, the number of revolutions of a rotating body of the turbine type flow meter, and
Each of the current value of the induced electromotive force generated by the rotation of the rotating body and the pressure difference between the inlet side and the outlet side of the two-phase fluid with respect to the turbine type flow meter is measured. relational expression relational expression gas-liquid volumetric flow rate ratio increases with the pressure difference is increased (16), the total volumetric flow rate of the two-phase fluid with increasing gas-liquid volumetric flow rate ratio is increased (1
4), the total volumetric flow rate is obtained based on the relational expression (20) obtained by eliminating the gas-liquid volumetric flow rate ratio,
Then, the gas-liquid volumetric flow rate ratio is calculated based on the relational expression (17) that the gas-liquid volumetric flow rate ratio increases as the total volumetric flow rate thus obtained increases. The total volumetric flow rate and the gas-liquid volumetric flow rate ratio are obtained by calculating the total mass flow rate based on the relational expression (19) that the total mass flow rate increases regardless of which of the value and the rotation speed increases. , And that the total mass flow rate is practically simultaneously determined.

Claims (2)

[Claims] 1. A method of measuring a flow rate of a two-phase fluid of liquid and gas by a turbine type flow meter in a mixed phase flow state of the liquid and gas, wherein the turbine type is used. The number of rotations of the rotating body of the flowmeter, the current value of the induced electromotive force generated with the rotation of the rotating body, and the inlet side and the outlet side of the two-phase fluid with respect to the turbine type flowmeter. Each of the pressure differences between the two is measured, and then the relational expression (16) in which the pressure difference increases and the gas-liquid volume flow ratio increases, and the total volume of the two-phase fluid increases as the gas-liquid volume flow ratio increases. Based on the relational expression (14) that the flow rate increases and the relational expression (20) obtained by eliminating the gas-liquid volume flow rate ratio, the total volumetric flow rate is obtained, and then, in this way A relational expression (17) that the gas-liquid volumetric flow rate ratio increases when the obtained total volumetric flow rate increases Then, the gas-liquid volumetric flow rate ratio is determined, and then, based on the relational expression (19) that the total mass flow rate increases regardless of which of the current value and the rotation speed increases, By determining the mass flow rate, the total volumetric flow rate, the gas-liquid volume flow rate ratio, and the total mass flow rate are practically simultaneously determined,
A two-phase fluid flow rate measurement method using a turbine type flow meter. 2. The relational expressions (14), (16), (17),
(19) and (20) are the following steps: Pressure difference Δp between the fluid before and after the turbine type flow meter in the case of two-phase flow and pressure difference between the fluid before and after the flow meter in the case of liquid single-phase flow. the ratio Delta] p / Delta] p _l0 with Delta] p _l0, the following relationship between the void fraction alpha of the two-phase fluid _{(16): Δp / Δp lo} = (1-α) -h -------- ------------- (16) However, so that h: constant holds, Δp and Δp by multiple experiments beforehand
_The constant h is determined by the combination of the value with _l0 and the function of equation (16) is specified, and α is Δp / Δp according to equation (16).
It is expressed by a function of _lo , and then the following equation (14): Q _tp = Ar _m ω / ε _tp = f ₁ (ω, α) ------------------- (14) where ε _tp is a two-phase flow rotation ratio, and ε _tp = Ar _m ω / Q _tp = e ₁ −e ₂ λ _tp where e ₁ = tan β _rm / (1 + κ) e ₂ = A / By substituting the above α represented by the function of Δp / Δp _lo into r _m ² (1 + κ) λ _tp = r _m M _tp / GQ _tp , α is eliminated and the following nonlinear equation (20): Q _tp = f ₄ (ω, Δp, Q _tp ) ------------------------- _Find (20) and solve the nonlinear equation (20). obtains a total volume flow Q _tp, then, in this way the total volume flow Q _tp obtained, and the data in the case of the two-phase flow - the pressure difference Δp bottle flow meter before and after the fluid, Formula (17) below: Δp = c ₃ (1-α) ^-h {(1-α) Q _tp } ² ---------------- (17) where c ₃ And h are constants, and the void rate α is calculated by substituting c ₃ in the same manner as the above-described method for obtaining h, and then, is calculated by the relational expression (16). The total volume flow rate Q _tp , the angular velocity ω of the rotating body obtained from the number of rotations of the rotating body of the turbine type flow meter, and the value of the current of the induced electromotive force generated with the rotation of the rotating body. i
Is expressed by the following formula (19): i = c ₄ (ωGQ _tp / r _m ) · {c ₁ −c ₂ (1-α) ^d } ---------------- ( 19) However, c ₁ , c ₂ , c ₄ and d are constants, and c ₂ ,
By substituting c ₄ and d in the same manner as the above-described method of obtaining c ₃ , the total mass flow rate G is obtained by the following relational expressions (14), (16), (17),
(19) and a (20), symbols and indices in the equation is the symbol: A: cross-sectional area of impeller ^{_{= π (r s 2 -r b}} 2) κ: Slip Coefficient of the impeller M: shaft torque of the impeller G: mass flow p: pressure Delta] p: data - the pressure difference of the fluid before and after the bottle-type flowmeter Q: volume flow rate r: radius rm: average radius ^{_{= √ {(r s 2 +}} r b 2) / 2 } Α: Void ratio ε: Rotation ratio = Ar _m ω / Q ω: Rotational angular velocity of the rotating body c ₁ , c ₂ , c ₃ , c ₄ : constant d: constant h: constants f ₁ and f ₄ : function subscript: w: liquid phase tp: two-phase flow 0: single-phase flow 1: impeller inlet side 2: impeller outlet side rm: average radius = √ {(r _s ² + r _b ² ) / 2}, claim Item 2. A method for measuring the flow rate of a two-phase fluid by the turbine type flow meter according to Item 1.