JP2002365105A - Method for measuring two-phase fluid and device for measuring it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measuring accuracy and measure density or volumetric flow of two-phase fluid and a volumetric content of solid particles even if the volumetric flow of the solid particles are unknown. SOLUTION: In a part 11 for measuring, the density γA+ S, the volumetric flow QA+ S of the two-phase fluid A+S, and the volumetric content ϕs of the solid particles S are obtained from differential pressure ΔPA measure by an orifice flowmeter 3 and the differential pressure ΔPA+ S measured by a flowmeter 7 for the two-phase flow by repeating approximate calculation. In this case, since measuring values of the volumetric flow Qs of the solid particles S, measured by a load cell 4, are not used, the measuring accuracy is improved and it is possible to measure even if the volumetric flow Qs of the solid particles S are unknown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-phase fluid measuring method and a measuring apparatus suitable for use in electrostatic powder coating and pulverized coal fuel.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a two-phase fluid control system using a conventional two-phase fluid measuring device. In the figure, 1 is a blower, 2 is an adjusting valve for adjusting the air flow rate from the blower 1, 3 is an orifice flow meter, 4 is a load cell in which solid particles (powder) S are stored, 5 is a load cell 4
A regulating valve for regulating the supply amount of solid particles S from the load cell, 6 a flow meter for detecting the volume flow rate Qs of the solid particles S from the load cell 4, 7 a venturi type two-phase flow meter, 8 a single tube density meter , 9 is a first controller and 10A is a second controller.

The air A from the blower 1 is mixed with the solid particles S from the load cell 4 to form a two-phase fluid A + S. The orifice flow meter 3 outputs a differential pressure ΔP _A corresponding to the flow rate of the air A before being mixed with the solid particles S. The two-phase flow meter 7 has a differential pressure ΔP corresponding to the flow rate of the two-phase fluid A + S flowing therethrough.
Outputs _{A + S.}

The two-phase flow meter 7 is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-133786 (Japanese Patent No. 2733717), and thus detailed description thereof will be omitted. Detect using a remote seal type differential pressure transmitter. Since the pressure receiving portion is wide, a differential pressure corresponding to the flow rate of the two-phase fluid can be detected without any trouble. The single-tube density meter 8 is provided in the middle of the pipe at the outlet of the two-phase fluid A + S, and is provided in the middle of the pipe. The differential pressure between the upper and lower h of the two-phase fluid A + S (h ≒ 1.5 m) is flowing through the pipe. ΔPh is output.

In this system, the controller 9
Receives the differential pressure ΔP _A from the orifice flow meter 3 as an input,
From this differential pressure ΔP _A, the volumetric flow rate Q _A of air A to the mixing section with the solid particles S is determined as Q _A = K ₁ · (ΔP _A / γ _A ) ^1/2 (K ₁ is the orifice flow meter 3 The coefficient, γ _A, is the density of air set as a known parameter), and controls the opening of the regulating valve 2 so that the volume flow rate Q _A of air A to the mixing section becomes a predetermined value.

The controller 10A receives the differential pressure ΔPh from the single tube density meter 8 as an input, and obtains the density of the two-phase fluid A + S by setting γ _{A + S} = ΔPh / h from the equation ΔPh = γ _{A + S} · h. (Mixing density of A and solid particles S) γ _{A + S} is determined.
Further, based on the obtained density γ _{A + S of} the two-phase fluid A + S and the differential pressure ΔP _{A + S} from the two-phase flow meter 7, the volume flow Q _{A + S} of the two-phase fluid A + S is calculated as Q _{A + S} = K ₂・ (ΔP _{A + S} / γ _{A + S} )
Obtaining ^1/2 (coefficient K ₂ is two-phase flow flowmeter 7). Then, while observing the volume flow rate Qs of the solid particles S from the flow meter 6, the determined density γ _{A + S} and the volume flow rate Q _{A + S} fall within predetermined ranges according to the use of the two-phase fluid A + S. , The opening of the regulating valve 5 is controlled.

When the mass flow rate W _{A + S} occupies about 30% of the volume flow rate Q _{A + S} of the two-phase fluid A + S in the dice-shaped solid particles and about 50% in the case of the spherical solid particles, the resistance decreases. Due to the increase, there is a high possibility that the pipeline is clogged. As a rough control, two-phase fluid A
The supply amount of the solid particles S may be controlled based on the density γ _{A + S} of _{+ S} , the mass flow rate W _{A + S} , and the volume flow rate Q _{A + S.} The mass flow rate W _{A + S} is the same as the volume flow rate Q _{A + S} ,
Can be determined from the differential pressure [Delta] P A _{+ S} from two-phase fluid A + S density gamma _{A + S} and two-phase flow flowmeter 7.

However, in this system, a single tube density meter 8 is used in addition to the two-phase flow meter 7 in order to obtain the density γ _{A + S} and the volume flow rate Q _{A + S} of the two-phase fluid A + S in the controller 10A. The cost is increased by using the single tube density meter 8. Further, in order to provide the single-tube density meter 8, it is necessary to set up a pipe L of about 5 m at the outlet of the two-phase fluid A + S, which also causes a cost increase. Further, the error of the differential pressure ΔP _{A + S} measured by the two-phase flow meter 7 is added to the error of the differential pressure ΔPh measured by the single tube density meter 8, so that the measurement accuracy is not very good. In particular,
The error of the differential pressure ΔPh measured by the single tube density meter 8 is large,
The measurement accuracy has deteriorated.

[Conventional example 2 (prior application)] The applicant of the present invention has previously disclosed, as Japanese Patent Application No. 2000-45920, a simple and simple system configuration without using a single tube density meter.
A two-phase fluid measurement method and a measurement device capable of accurately measuring the density and volume flow rate of a phase fluid have been proposed.

FIG. 7 is a system configuration diagram of a two-phase fluid control system using the two-phase fluid measurement device disclosed in Japanese Patent Application No. 2000-45920 (prior application). 6, the same reference numerals as those in FIG. 6 denote the same or equivalent components, and a description thereof will be omitted. In this system, conventional example 1
The single pipe density meter 8 required in (FIG. 6) is omitted, and the start-up L of the pipe at the outlet of the two-phase fluid A + S is eliminated, so that a simple and simple system configuration is provided. I have.

To explain the outline of this system, the controller 10B determines the two-phase fluid A + S from the measured differential pressure ΔP _{A + S} from the two-phase flow meter 7 and the volumetric flow rate Qs of the solid particles S from the flow meter 6. density gamma _{a + S} and volumetric flow rate Q _{a + S,} determined by the repetition of such an approximate calculation volume content φs of the solid particles S, density gamma _{a + S} and volumetric flow rate Q _{a + S} is two-phase fluid a +
The opening of the regulating valve 5 is controlled so as to be in a predetermined range according to the use of S.

[0012]

However, the system of the prior application has the above-mentioned advantages over the system of the prior art 1, but the solid particles S from the load cell 4 detected by the flow meter 6 are detected. Using the volumetric flow rate Qs of 2
Phase Fluid A + density of S gamma _{A + S} and volumetric flow rate Q _{A + S,} because you have to measure the volume content φs of the solid particles S, was expected significant improvement in measurement accuracy.

That is, the load cell 4 is intended to feed the solid particles S, and does not have a structure capable of accurately measuring the amount of the solid particles S fed to the mixing section. Therefore, a non-negligible error occurs in the volume flow rate Qs of the solid particles S from the flow meter 6 to the controller 10B, and the measurement accuracy is deteriorated. Further, as a measurement principle, it is necessary that the volume flow rate Qs of the solid particles S to the mixing section is known, and the volume flow rate Qs
It was impossible to measure the density γ _{A + S} of the two-phase fluid A + S, the volume flow rate Q _{A + S} , and the volume content φs of the solid particles S in a state where s is unknown.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to improve the measurement accuracy and to improve the accuracy even when the volume flow rate of solid particles is unknown. It is an object of the present invention to provide a two-phase fluid measuring method and a measuring device capable of measuring the density and volume flow rate of a two-phase fluid, the volume content of solid particles, and the like.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a two-phase fluid in which solid particles are mixed with a fluid, and the two-phase fluid is mixed in a fluid passage before being mixed with the solid particles. A first flow meter for detecting the flow rate of the two-phase fluid as a differential pressure, and a second flow meter for detecting the flow rate of the two-phase fluid as a differential pressure. At least one of the density, the volume flow rate, and the volume content of the solid particles of the two-phase fluid is obtained by repeating the approximate calculation from the measured differential pressure and the differential pressure measured from the second flow meter.

According to the present invention, the measured differential pressure (ΔP _A ) from the first flow meter (for example, the orifice flow meter) and the measured differential pressure (ΔP _A ) from the second flow meter (for example, a venturi type two-phase flow meter) are used. From the measured differential pressure (ΔP _{A + S} ), at least one of the density of the two-phase fluid (γ _{A + S} ), the volumetric flow rate (Q _{A + S} ), and the volume content of solid particles (φs) is obtained by repeating the approximate calculation. Desired.

The present invention also provides a first flow meter for mixing a solid particle with a fluid to form a two-phase fluid, and detecting a flow rate of the fluid as a differential pressure in a flow path of the fluid before being mixed with the solid particle. And a second flow meter for detecting the flow rate of the two-phase fluid as a differential pressure is provided in the flow path of the two-phase fluid, and the volume flow rate of the fluid determined from the differential pressure measured from the first flow meter is determined by the two-phase flow rate. The first approximate value of the volume content of solid particles in the two-phase fluid is determined from the measured differential pressure from the first flow meter and the differential pressure measured from the second flow meter as the first approximate value of the volume flow rate of the fluid. A first approximation of the volume content of the solid particles and a first approximation of the volume flow rate of the two-phase fluid
Calculating a second approximate value of the volume flow rate of the two-phase fluid from the approximate value;
A second approximate value of the density of the two-phase fluid is determined from the second approximate value of the volume flow rate of the two-phase fluid and the measured differential pressure from the second flow meter, and the second approximate value of the density of the two-phase fluid is determined. A second approximation of the volume content of solid particles in the two-phase fluid was determined and this 2
The second approximation of the volume content of solid particles in the phase fluid is replaced with a first approximation, and the above approximation calculation is repeated until a predetermined condition is satisfied.

According to the present invention, the volumetric flow rate (Q _A ) of the fluid obtained from the measured differential pressure (ΔP _A ) from the first flow meter (for example, the orifice flow meter) is the second volume flow rate of the two-phase fluid. 1 (Q), and the measured differential pressure (ΔP _A ) from the first flow meter and the measured differential pressure (ΔP _A ) from the second flow meter
_{A + S} ) to obtain a first approximate value (φ) of the volume content of solid particles in the two-phase fluid, and a first approximate value (φ) of the volume content of the solid particles and the volume flow rate of the two-phase fluid From the first approximate value (Q = Q _A ) of the two-phase fluid, a second approximate value (Q ′) of the two-phase fluid volume flow rate is obtained. 2 from the flowmeter (Δ
P _{A + S} ) to obtain a second approximate value (γ ′) of the density of the two-phase fluid, and from the second approximate value (γ ′) of the density of the two-phase fluid, the volume content of solid particles in the two-phase fluid A second approximate value (φ ′) of the volume fraction of the solid particles in the two-phase fluid is replaced with a first approximate value (φ) (φ ← φ ′). ), The above approximate calculation is repeated until a predetermined condition is satisfied. If the predetermined condition is satisfied, this approximation calculation is stopped.

As the predetermined condition, for example, when the difference between the second approximate value (φ ′) and the first approximate value (φ) of the volume content of solid particles in the two-phase fluid becomes almost equal, It is assumed that the number of repetitions of the calculation reaches a predetermined value.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention.
It is a figure showing an important section of a phase fluid measuring device. In the figure,
Reference numeral 3 denotes an orifice flow meter, 4 denotes a load cell in which solid particles (powder) S are stored, 7 denotes a venturi type two-phase flow meter, which is used in the system configuration shown in FIGS. Therefore, the description is omitted.

In this embodiment, the orifice flow meter 3
Differential pressure Δ but in accordance with the flow rate of the two-phase fluid A + S in which the differential pressure [Delta] P _A and two-phase flow flowmeter 7 corresponding to the flow rate of the air A to be detected is detected
Gives P A _{+ S} to the measuring part 11, the measuring unit 11, from this measurement differential pressure [Delta] P _A and [Delta] P A _{+ S} of a two-phase fluid A + S density gamma _{A + S,} the volumetric flow rate Q _{A + S} and solid particles S Content rate φs
Is obtained by repeating the approximate calculation described below.
The measuring unit 11 is an arithmetic device (for example, a computer) including a central processing unit (CPU) and a storage device, and executes an arithmetic process according to an arithmetic processing flow described later by cooperating with a program.

[0022] and [first approximation] first approximation of the volumetric flow Q _{A + S} volumetric flow rate Q _A two-phase fluid A + S of the air _{A (Q A + S) 1} . Q _A = (Q _{A + S} ) ₁ (1) This formula (1) and the following formula (2), which is the basic formula of the differential pressure flow meter,
If Q _{A + S} = (Q _{A + S} ) _{1 according} to the equation (3), the following equation (4) is obtained.

Q _A = K ₁ · (ΔP _A / γ _A ) ^1/2 ··· (2) Q _{A + S} = K ₂ · (ΔP _{A + S} / γ _{A + S} ) ^1/2 ··· ·· (3) γ _{A + S} = γ _A · (ΔP _{A + S} / ΔP _A ) (K ₂ / K ₁ ) ² ··· (4)

From the volume content of solid particles φs, the two-phase fluid A
Equation (6) is obtained from the following equation (5), which is a basic equation for calculating the density γ _{A + S} of _{+ S,} and equation (4). γ _{A + S} = γ _A · (1−φs) + φs · γ _S (5) φs = [(ΔP _{A + S} / ΔP _A ) · (K ₂ / K ₁ ) ² −1] / [ (Γ _S / γ _A ) −1] (6) Let φs obtained from the equation (6) be the first approximate value φ ₁ of the volume content of the solid particles S.

The expression (5) is derived based on FIG.
That is, the density of the two-phase fluid A + S is γ _{A + S} , the density of the solid particles S is γs, the density of the air A is γ _A , the volume flow rate of the two-phase fluid A + S is Q _{A + S} , The volume flow rate of _A is Q _A , the volume flow rate of the solid fluid S is Qs, and the volume content rate of the solid particles S is φs, and the volume content rate of the air A is expressed by (1−φs). In this case, Q _{A + S} · γ
If _{A + S = Q A · γ} A · (1-φs) + Qs · φs · γs next, the Q _{A + S} 1 and the above equation (5) is derived.

[Second approximation calculation] φ ₁ calculated by equation (6)
Then, the first approximation value (Q _{A + S} ) ₁ of the equation (1) is corrected to create the following equation (7). Q _A = (Q _{A + S} ) ₁ ′ · (1−φ ₁ ) (7) From the equation (7), (Q _{A + S} ) ₁ ′ = Q _A / (1−φ ₁ ) (8), (Q _{A + S} ) ₁ ′ is obtained, and this (Q _{A + S} ) ₁ ′ is used as the second approximate value (Q _{A + S} ) ₂ of the volume flow rate Q _{A + S.} .

By substituting the second approximate value (Q _{A + S} ) ₂ into the equation (3), the following equation (9) is created. (Q _{A + S} ) ₂ = K ₂ · (ΔP _{A + S} / γ _{A + S} ) ^1/2 (9) From the equation (9), γ _{A + S} = [K ₂ / (Q _{A + S} ) ₂ ] ² · ΔP _{A + S} ... (10), γ _{A + S} is obtained, and this γ _{A + S} is a second approximate value of the density of the two-phase fluid (γ _{A + S} ). _{Assume 2} .

Next, the second approximation value (γ _{A + S} ) ₂ is substituted into the equation (5) to produce the following equation (11). (Γ _{A + S} ) ₂ = γ _A · (1−φs) + φs · γ _S (11) From the equation (11), the following equation (12) is formed, and φs = ｛[(γ _{A + S} ) ₂ / γ _A ] -1｝ / {[γ _S / γ _A ] -1} (12) φs obtained from the equation (12) is a second approximation of the volume content of the solid particles S. the value φ _2.

[Third approximation calculation] φ calculated by equation (12)
_{In step 2} , the first approximation value (Q _{A + S} ) ₁ in equation (1) is corrected to create equation (13) below. Q _A = (Q _{A + S} ) ₁ ′ · (1−φ ₂ ) (13) From the expression (13), (Q _{A + S} ) ₁ ′ = Q _A / (1−φ ₂ ) as ... (14), and (Q _{a +} S) 'seek, the _{(Q a + S) 1'} 1 the third approximation of the volumetric flow rate _{Q a + S (Q a +} S) 3 .

By substituting the third approximate value (Q _{A + S} ) ₃ into the equation (3), the following equation (15) is created. (Q _{A + S} ) ₃ = K ₂ · (ΔP _{A + S} / γ _{A + S} ) ^1/2 (15) From the equation (15), γ _{A + S} = [K ₂ / (Q _{A + S} ) ₃ ] ² · ΔP _{A + S} ... (16), γ _{A + S} is obtained, and γ _{A + S} is a third approximate value of the density of the two-phase fluid (γ _{A + S} ). _{Assume 3} .

Next, the third approximation value (γ _{A + S} ) ₃ is substituted into the equation (5) to produce the following equation (17). (Γ _{A + S} ) ₃ = γ _A · (1−φs) + φs · γ _S (17) From the expression (17), the following expression (18) is created, and φs = ｛[(γ _{A + S} ) ₃ / γ _A ] -1｝ / {[γ _S / γ _A ] -1} (18) φs obtained from the equation (18) is the third approximation of the volume content of the solid particles S. the value φ _3. Hereinafter, the calculation is repeated in the same procedure, and the process proceeds to the n-th approximation.

[N-th approximation calculation] The first approximation value (Q _{A + S} ) ₁ of the equation (1) is corrected by φ _n-1 obtained by _n-1 repetitive calculations, and the following equation (19) is obtained. create. Q _A = (Q _{A + S} ) ₁ ′ · (1−φ _n−1 ) (19) From this equation (19), (Q _{A + S} ) ₁ ′ = Q _A / (1−φ as _{n-1) ···· (20)} , (Q a + S) ' seek, the _{(Q a + S) 1'} 1 the n-th approximation of the volumetric flow rate _{Q a + S (Q a +} S ) _N.

By substituting the n-th approximate value (Q _{A + S} ) _n into the equation (3), the following equation (21) is created. (Q _{A + S} ) _n = K ₂ · (ΔP _{A + S} / γ _{A + S} ) ^1/2 (21) From the equation (21), γ _{A + S} = [K ₂ / (Q _{A + S} ) _n ] ² · ΔP _{A + S} (22), γ _{A + S} is obtained, and this γ _{A + S} is calculated as the n-th approximate value of the density of the two-phase fluid (γ _{A + S} ). _Let it be _n .

Next, the n-th approximate value (γ _{A + S} ) _n is substituted into the equation (5) to produce the following equation (23). (Γ _{A + S} ) _n = γ _A · (1−φs) + φs · γ _S (23) From the expression (23), the following expression (24) is created, and φs = ｛[(γ _{A + S} ) _n / γ _A ] -1} / {[γ _S / γ _A ] -1} (24) The φs obtained from the equation (24) is the n-th approximation of the volume content of the solid particles S. the value φ _n.

[Stop of repetition of approximation calculation] The difference between φ _n-1 obtained in the ( _n−1) th approximation calculation and φ _n obtained in the nth approximation calculation is divided by φ _n to obtain a percentage δ, That is, 100
・ Calculate (φ _n-1 −φ _n ) / φ _n and calculate the calculated value δ
= 100 · (φ _n-1 −φ _n ) / φ _n is compared with a predetermined value ε. When δ <ε, ie, the following (25)
When the formula holds, the calculation is repeatedly stopped. 100 · (φ _n-1 −φ _n ) / φ _n <ε (25)

[Demonstration] In the above-described iterative calculation method,
The fact that the density γ _{A + S} and the volume flow rate Q _{A + S of} the two-phase fluid A + S and the volume content φs of the solid particles S can be measured are as follows.
Demonstrate based on an example. In this demonstration, the fluid specifications of the orifice flow meter 3 and the two-phase flow meter 7 are as follows.

[Orifice flow meter 3 side: air] Air flow rate Q _A : 1000 [m ³ / h] Air density: γ _A : 1.2929 [kg / m ³ ] Pressure: p = 0 [MPa. G] Temperature: t = 0 [° C.] Piping inner diameter: D = 100 [mm] Restriction diameter ratio: β = 0.60 [−−−] Differential pressure: ΔP _A = 14.772 [KPa] Flow meter coefficient: K ₁ = 1000 / (14.772 / 1.2
929) ^1/2 = 295.84 Discharge coefficient: c = 0.6064

[Two-phase flow meter 7 side: Mixed two-phase flow of air and fine powder] Flow rate of two-phase fluid: Q _{A + S} = 1010 [m ³ / h] Density of solid particles: γs = 1000 [ kg / m ³ ] Volume content of solid particles: φs = 0.999999
[−−−] Density of two-phase fluid: γ _{A + S} = 1.2929 × (1.0−
0.0099999) + 1000 × 0.009900
99 = 11.1811 [kg / m ³ ] Pressure: p = 0 [MPa. G] Temperature: t = 0 [° C.] Piping inner diameter: D = 100 [mm] Diameter ratio: β = 0.60 [−−−] Differential pressure: ΔP _{A + S} = 53.515 [KPa] Flow meter coefficient _{: K 2 = 1010 / (53.515} / 11.
1811) ^1/2 = 461.66 Outflow coefficient: c = 0.95

[Iterative calculation] The density γ _{A + S} , the volume flow rate Q _{A + S} of the two-phase fluid A + S, and the content φs of the solid particles S are obtained by iterative calculation. The available data are only the measured differential pressure ΔP _A from the orifice flow meter 3 and the measured differential pressure ΔP _{A + S} from the two-phase flow meter 7. Using these differential pressures, calculations are repeated until the content φs of the solid particles S converges. In the actual measurement, the convergence is confirmed by the equation (25). However, this time, as shown in the above-mentioned fluid specification, the volume fraction φs of the solid particles is known in advance as φs = 0.999999, so Content φs = 0.0
0990099 as the theoretical content, and the theoretical content φs
And compared.

[First approximation calculation] By the equation (4), γ_{A + S} = Γ_A・ (ΔP_{A + S}/ ΔP_A ) ・ (K_Two/ K₁)
^Two = 1.2929 · (53.515 / 14.772) ·
(461.66 / 295.84)^Two = 11.406 [k
g / m^Three] Is obtained. From equation (6), φ₁= [(ΔP_{A + S}/ ΔP_A ) ・ (K_Two/ K₁)^Two −
1] / [(γ_S / Γ_A) -1] = [(53.515 / 1
4.772) (461.66 / 295.84) ^Two −
1] / [(1000 / 1.2929) -1] = 0.01
0126 is obtained.

If the theoretical content φs of the solid particles S is φs = 0.
0999999, this φs = 0.999
0099 and φ ₁ = 0.010126 obtained by calculation
From this, δ = 100 · (φ ₁ −φs) / φs = 100 ·
(0.010126-0.0099099) /0.0
Calculate 099099. In this case, δ = 2.27%
Becomes

[Second approximation calculation] From the equation (7), Q _A = (Q _{A + S} ) ₂ · (1-φ ₁ ) (Q _{A + S} ) ₂ = Q _A / (1-φ ₁ ) ( Q _{A + S} ) ₂ = 1000 / (1-0.010126) =
1010.2 [m ³ / h] are obtained. By substituting (Q _{A + S} ) ₂ = 1010.2 into equation (10), (γ _{A + S} ) ₂ = [K ₂ / (Q _{A + S} ) ₂ ] ² · ΔP _{A + S} =
[461.66 / 1010.2] ² × 53.515 = 1
1.1765 [kg / m ³ ] are obtained.

(Γ _{A + S} ) ₂ = 1 obtained by this calculation
Substituting 1.1765 into equation (12) gives φ ₂ = {[(γ _{A + S} ) ₂ / γ _A ] −1} /｝ [γ _S / γ
_A ] -1} = {[(11.1765 / 1.2929]-
1 / {[1000 / 1.2929] -1} = 0.00
98965 are obtained.

The theoretical content φs of the solid particles S is φs = 0.
0999999, this φs = 0.999
0099 and φ ₂ = 0.009896 obtained by calculation
From 5, δ = 100 · (φ ₂ −φs) / φs = 100
(0.0098965-0.0099099) / 0.
0999999 is calculated. In this case, δ = 0.04
6%.

[Third approximation calculation] From the equation (13), Q _A = (Q _{A + S} ) ₃ · (1-φ ₂ ) (Q _{A + S} ) ₃ = Q _A / (1-φ ₂ ) ( Q _{A + S} ) ₃ = 1000 / (1-0.0098965)
= 1009.995 [m ³ / h]. The calculated (Q _{A + S} ) ₃ = 1009.9995 is calculated as (1
Substituting into equation 6), (γ _{A + S} ) ₃ = [K ₂ / (Q _{A + S} ) ₃ ] ² · ΔP _{A + S} =
[461.66 / 1009.995] ² × 53.515
= 11.1810 [kg / m ³ ].

(Γ _{A + S} ) ₃ = 1 obtained by this calculation
By substituting 1.1810 into equation (18), φ ₃ = {[(γ _{A + S} ) ₃ / γ _A ] −1} / ｛[γ _S / γ
_A ] -1} = {[(11.1810 / 1.2929]-
1 / {[1000 / 1.2929] -1} = 0.00
99009 is obtained.

The theoretical content φs of the solid particles S is φs = 0.
0999999, this φs = 0.999
0099 and φ ₃ = 0.009900 obtained by calculation
From equation 9, δ = 100 · (φ ₃ −φs) / φs = 100
(0.0090909-0.0090099) / 0.
0999999 is calculated. In this case, δ = 0.00
1%.

[Fourth approximation calculation] In the same manner as the third approximation calculation
Q_A= (Q_{A + S})_Four・ (1-φ_Three(Q_{A + S})_Four= Q_A/ (1-φ_Three(Q_{A + S})_Four = 1000 / (1-0.0099009)
= 1010.00 [m ^Three/ H]. This calculated (Q_{A + S})_Four = 1010.00 to (γ
_{A + S})_Four, And (γ_{A + S})_Four = [K_Two/ (Q_{A + S})_Four ]^Two・ ΔP_{A + S} =
[461.66 / 1010.00]^Two× 53.515 =
11.1809 [kg / m^Three] Is obtained.

(Γ _{A + S} ) ₄ = 1 obtained by this calculation
From 1.1809, φ ₄ = {[(γ _{A + S} ) ₄ / γ _A ] -1} / ｛[γ _S / γ
_A ] -1} = {[(11.1809 / 1.2929]-
1 / {[1000 / 1.2929] -1} = 0.00
990081 is obtained.

The theoretical content φs of the solid particles S is φs = 0.
0999999, this φs = 0.999
0099 and φ ₄ = 0.009900 obtained by calculation
From 81, δ = 100 · (φ ₄ −φs) / φs = 10
0 · (0.0090081-0.0090099)
/0.00999999 is calculated. In this case, δ =
0.002%.

FIGS. 3A and 3B show verification results from the first approximation to the fourth approximation. In this example, it can be seen that the convergence is completed if the calculation is repeatedly performed up to the third approximation, and the further repeated calculation is meaningless. Also, it can be seen that when an error of about 3% is allowed, iterative calculation is not necessary and the first approximation can be completed.

[Calculation Processing Flow for Repeating Approximation Calculation] FIG. 4 shows a calculation processing flow of the density γ _{A + S} , the volume flow rate Q _{A + S} of the two-phase fluid A + S, and the content φs of the solid particles S in the measuring section 11. Show.

The measuring section 11 first sets the orifice flow meter 3
From the measured differential pressure ΔP _{A according} to the above equation (2).
The volumetric flow rate Q of the determined _A, the obtained Q _A two-phase fluid A +
The first approximate value Q of the volume flow rate QA _{+ S} of _S (step 4)
01). Also, the measured differential pressure ΔP from the orifice flow meter 3
_A and the measured differential pressure ΔP _{A + S} from the two-phase flow meter 7 are substituted into the above equation (6) to obtain solid particles S in the two-phase fluid A + S.
A first approximation value φ (= φ ₁ ) of the volume content ratio φs is obtained (step 402).

The first approximate value φ is substituted into the above equation (8), and the second approximate value Q ′ of the volume flow rate Q _{A + S} (= (Q _{A + S} )
₂ ) is obtained (step 403). In this calculation, the volume flow rate Q _A of the air A obtained in step 401, that is, the first approximate value Q of the volume flow rate Q _{A + S} is substituted for Q _A in the equation (8), and Q ′ = Q _A / (1-φ) = Q / (1-
_A second approximate value Q ′ of the volume flow rate Q _{A + S} is obtained as φ).

Then, the second of the obtained volume flow rate Q _{A + S}
Approximate value Q ′ and measured differential pressure ΔP from two-phase flow meter 7
_{A + S} is substituted into the above equation (10) to obtain a second approximate value γ ′ (= (γ _{A + S} ) ₂ ) of the density γ _{A + S} of the two-phase fluid A + S (step 404). Then, the obtained second approximate value γ ′ is substituted into the equation (12), and the second approximate value φ ′ (= φ) of the volume content φs of the solid particles S in the two-phase fluid A + S is obtained.
₂ ) is obtained (step 405).

Then, the measuring section 11 determines in step 402
The determined volume content of the solid particles S in the two-phase fluid A + S
The first approximation φ of φs and the second approximation obtained in step 405
The difference from the value φ ′ is divided by the second approximation φ ′ to obtain the percentage δ
Calculated, that is, 100 · (φ _n-1−φ_n ) / Φ_n Calculate
Then, the calculated value δ = 100 · (φ_n-1−φ_n ) / Φ
_n Is compared with a predetermined value ε (step 406). δ ≧ ε
If so, proceed to step 407 and replace φ with φ ′
That is, the second approximate value φ 'is replaced with the first approximate value φ.
And the approximation of steps 403 to 406 until δ <ε
Repeat the calculation. In the present embodiment, ε is, for example,
It is set as 0.05%.

In step 406, if δ <ε, that is, the first approximate value φ (= φ _n-1 ) and the second approximate value φ ′ (=) of the volume fraction φs of the solid particles S in the two-phase fluid A + S If the difference from φ _n ) is almost equal, step 4
08, the φ ′ at this time, that is, the final second approximate value φ ′ (= φ _n ) obtained in step 405 is defined as the volume content rate φs of the solid particles S in the two-phase fluid A + S. Further, Q ′ at this time, that is, the final second approximate value Q ′ (= (Q _{A + S} ) _n ) obtained in step 403 is defined as the volume flow rate Q _{A + S} of the two-phase fluid A + S. Also, γ 'at this time
That is, the final second approximate value γ ′ (= (γ _{A + S} ) _n ) obtained in step 404 is used as the density γ _{A + S of the} two-phase fluid _{A + S.}
And

As described above, according to the two-phase fluid measuring device of the present embodiment, the measured differential pressure ΔP from the orifice flow meter 3
_{From A} and the measured differential pressure ΔP _{A + S} from the two-phase flow meter 7,
Density gamma _{A + S} phase fluid A + S, since the volumetric flow rate Q _{A + S} and volume content φs of the solid particles S are determined, that is, without using a measurement of volumetric flow rate Qs of the solid particles S from the load cell 4, Measurement accuracy is improved.

In this embodiment, the load cell 4
Is not used, the volume flow Qs of the solid particles S is not known, and the two-phase fluid A +
It is possible to measure the density γ _{A + S of S} , the volume flow rate Q _{A + S} , and the volume content φs of the solid particles S. Therefore, there is no need to measure the volume flow rate Qs, and it is not necessary to provide a flow meter at the outlet of the solid particles S from the load cell 4.

If the volume flow rate Qs of the solid particles S from the load cell 4 is constant (the feed amount from the load cell 4 is fixed), the flow meter 6 can be omitted in the method of the prior application (FIG. 7). It is. However, in this case, the volume flow rate Qs of the solid particles S from the load cell 4 is a known value.
It must be set in the controller 10B. On the other hand, in the present embodiment, the volume flow rate Qs of the solid particles S from the load cell 4 does not need to be known, and the volume flow rate Qs of the solid particles S is set in the measurement unit 11. Need not be performed.

Further, in this embodiment, during the repeated approximate calculation, the second approximate value φ ′ of the volume content of the solid particles S is obtained.
(= Φ _n ) and the first approximation value φ (= φ _n-1 ) stop the approximation calculation when they are almost equal to each other. You may make it stop. Actually, the density γ close to the true value of the two-phase fluid A + S is obtained by repeating the approximation calculation about twice.
_{A + S} , the volume flow rate Q _{A + S} , and the volume content φs of the solid particles S can be obtained.

In this embodiment, the two-phase fluid A + S
, The density γ _{A + S} , the volume flow rate Q _{A + S} , and the volume fraction φs of the solid particles S are all determined. However, it is not necessary to determine all of these values, and only the required values are determined. It may be. Further, from the density gamma _{A + S} volumetric flow rate Q _{A + S} and two-phase fluid A + S, as _{W A + S = Q A +} S · γ A + S, it is also possible to determine the mass flow rate W _{A + S} .

In this embodiment, the two-phase fluid A + S
Is a mixture of air A and solid particles S, but another gas may be used instead of air. Alternatively, a two-phase fluid in which a liquid and a solid are mixed may be used. Further, in the present embodiment, the density γ _{A of} the air and the density γ of the solid particles S
Although s is set to the measuring unit 11 as a known parameter, it may be provided to the measuring unit 11 as a measured value.

Further, in the present embodiment, the principal parts have been extracted and described for explaining the principle of measurement of the two-phase fluid.
It can be used in a two-phase fluid control system as shown in FIGS. FIG. 5 shows a system configuration in this case. In the two-phase fluid control system, the controller 10C uses the measured differential pressure ΔP _A from the orifice flow meter 3 and the measured differential pressure ΔP _{A + S} from the two-phase flow meter 7 to determine the density γ _{A + of the} two-phase fluid A + S. _S and the volume flow rate Q _{A + S} and the volume content φs of the solid particles S are obtained by repeating approximation calculations, and the density γ _{A + S} and the volume flow rate Q _{A + S} are within predetermined ranges according to the use of the two-phase fluid A + S. The opening of the regulating valve 5 is controlled so that

In this embodiment, the flow meter 3 is not limited to the orifice flow meter, and the two-phase flow meter 7 is not limited to the venturi type flow meter. As a function of the two-phase flow meter 7, it is desired that clogging hardly occurs in the flow of the solid particles. In the configuration shown in FIG. 5, the air A is sent to the mixing section with the solid particles S using the blower 1, but a suction device is provided on the outflow side of the two-phase fluid A + S to pull the air. It may be.

[0066]

As is apparent from the above description, according to the present invention, the measured differential pressure (ΔP _A ) from the first flow meter (for example, orifice flow meter) and the second flow meter (for example, From the measured differential pressure (ΔP _{A + S} ) from the venturi type two-phase flow meter, the density (γ _{A + S} ), volumetric flow rate (Q _{A + S} ) and volumetric content of solid particles of the two-phase fluid Since at least one of (φ _{A + S} ) is obtained by repeating the approximate calculation, that is, since the measured value of the volume flow rate of the solid particles to the mixing section is not used, it is possible to improve the measurement accuracy. In the state where the volume flow rate of the solid particles to the mixing section is unknown, the density (γ _{A + S} ), the volume flow rate (Q _{A + S} ) of the two-phase fluid, and the volume content rate (φs) of the solid particles S are determined. It becomes possible to measure.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a two-phase fluid measurement device according to an embodiment of the present invention.

FIG. 2 is a diagram from which an equation of γ _{A + S} = γ _A · (1−φs) + φs · γ _S is derived.

FIG. 3 is a diagram showing verification results from a first approximation to a fourth approximation.

FIG. 4 shows two phases in a measuring section of the two-phase fluid measuring device.
Density γ of fluid A + S _{A + S}, Volume flow Q_{A + S}And solid grains
FIG. 9 is a diagram showing a calculation processing flow of a volume content rate φs of a child S.
You.

FIG. 5 is a system configuration diagram of a two-phase fluid control system using the two-phase fluid measurement device.

FIG. 6 is a system configuration diagram of a two-phase fluid control system using a conventional two-phase fluid measurement device.

FIG. 7 is a system configuration diagram of a two-phase fluid control system using the two-phase fluid measurement device shown in the prior application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Blower, 2 ... Adjusting valve, 3 ... Orifice flow meter, 4 ...
Load cell, 5: regulating valve, 6: flow meter, 7: two-phase flow meter, 9: first controller, 10C: second controller, 11: measuring unit, A: air, S: solid particles (powder ), A + S: two-phase fluid.

Claims (8)

[Claims] 1. A first flowmeter for mixing a solid particle with a fluid to form a two-phase fluid, and detecting a flow rate of the fluid as a differential pressure in a flow path of the fluid before being mixed with the solid particles. A second flow meter for detecting a flow rate of the two-phase fluid as a differential pressure in the flow path of the two-phase fluid, and measuring a differential pressure from the first flow meter and measuring from the second flow meter; A two-phase fluid measurement method, wherein at least one of the density, the volume flow rate and the volume content of solid particles of the two-phase fluid is obtained from the differential pressure by repeating approximation calculation. 2. A first flow meter for mixing a solid particle with a fluid to form a two-phase fluid and detecting a flow rate of the fluid as a differential pressure in a flow path of the fluid before being mixed with the solid particles. A second flowmeter for detecting a flow rate of the two-phase fluid as a differential pressure in the flow path of the two-phase fluid, and determining a volume flow rate of the fluid obtained from a measured differential pressure from the first flowmeter; The first approximate value of the volume flow rate of the two-phase fluid is obtained. From the measured differential pressure from the first flow meter and the differential pressure measured from the second flow meter, the volume content of solid particles in the two-phase fluid is calculated. Determining a first approximate value; determining a second approximate value of the volume flow rate of the two-phase fluid from the first approximate value of the volume content of the solid particles and the first approximate value of the volume flow rate of the two-phase fluid; The two-phase fluid is obtained from a second approximate value of the volume flow rate of the two-phase fluid and a measured differential pressure from the second flow meter. The second approximation of the density of the solid particles in the two-phase fluid is obtained from the second approximation of the density of the two-phase fluid, and the volume of the solid particles in the two-phase fluid is obtained. A two-phase fluid measurement method, wherein the second approximate value of the content is replaced with a first approximate value, and the above-described approximate calculation is repeated until a predetermined condition is satisfied. 3. The two-phase fluid measurement method according to claim 2, wherein the predetermined condition is such that a difference between a second approximate value and a first approximate value of the volume content of solid particles in the two-phase fluid is substantially equal to the first approximate value. ２ A two-phase fluid measurement method characterized in that it is equal. 4. The two-phase fluid measurement method according to claim 2, wherein the predetermined condition is that the number of repetitions of the approximate calculation reaches a predetermined value. 5. A fluid flow means for flowing a fluid, solid particle mixing means for mixing solid particles into a flowing fluid to form a two-phase fluid, and a fluid flow path before being mixed with the solid particles. A first flow meter provided to detect the flow rate of the fluid as a differential pressure; a second flow meter provided in the flow path of the two-phase fluid to detect the flow rate of the two-phase fluid as a differential pressure; From the measured differential pressure from the first flow meter and the differential pressure measured from the second flow meter, at least one of the density, the volume flow rate, and the volume content of the solid particles of the two-phase fluid is obtained by repeating approximate calculation. A two-phase fluid measurement device comprising: an approximation calculation unit. 6. A fluid flow means for flowing a fluid, solid particle mixing means for mixing solid particles with a flowing fluid to form a two-phase fluid, and a fluid flow path before being mixed with the solid particles. A first flow meter provided to detect the flow rate of the fluid as a differential pressure; a second flow meter provided in the flow path of the two-phase fluid to detect the flow rate of the two-phase fluid as a differential pressure; The volume flow rate of the fluid obtained from the measured differential pressure from the first flow meter is defined as a first approximate value of the volume flow rate of the two-phase fluid, and the measured differential pressure from the first flow meter and the second flow meter A first approximation of the volume content of solid particles in the two-phase fluid from the measured differential pressure from A second approximate value of the volumetric flow rate of the two-phase fluid from The from the measurement differential pressure from the second approximate value second flowmeter density of the two-phase fluid 2
An approximate value is determined, a second approximate value of the volume content of solid particles in the two-phase fluid is determined from the second approximate value of the density of the two-phase fluid, and a second approximate value of the volume content of solid particles in the two-phase fluid is determined. A two-phase fluid measurement device, comprising: approximation calculating means for replacing the approximation value with a first approximation value and repeating the approximation calculation until a predetermined condition is satisfied. 7. The two-phase fluid measurement device according to claim 6, wherein the predetermined condition is that a difference between a second approximate value and a first approximate value of the volume content of solid particles in the two-phase fluid is approximately equal. ２ A two-phase fluid measurement device characterized in that it is assumed to be equal. 8. The two-phase fluid measurement apparatus according to claim 6, wherein the predetermined condition is that the number of repetitions of the approximate calculation reaches a predetermined value. apparatus.