JP2022181347A - Composition estimation device and fluid mixture system - Google Patents

Abstract

To provide a composition estimation device and a fluid mixture system which can supply fluid with a required composition.SOLUTION: A composition estimation device 1A comprises: a thermal type flowmeter 2; a volume flowmeter 3; and a calculation device 4A. The thermal type flowmeter 2 measures a mass flow rate Qa of measurement fluid M different from reference fluid with a specific composition. The volume flowmeter 3 measures a volume flow rate Qb of the measurement fluid M flowing in a pipeline 5. The calculation device 4A obtains an inherent coefficient b of the measurement fluid M with b=a×Qa/Qb when an inherent coefficient of the reference fluid set in the thermal type flowmeter 2 is a, the mass flow rate of the measurement fluid M measured by the thermal type flowmeter 2 is Qa, and the volume flow rate of the measurement fluid M measured by the volume flowmeter 3 is Qb, and estimates the composition of the measurement fluid M on the basis of the inherent coefficient b of the measurement fluid M.SELECTED DRAWING: Figure 1

Description

The present invention relates to composition estimating devices and fluid mixing systems.

2. Description of the Related Art Various combustion equipment such as gas burners used in industrial furnaces and the like are configured to burn fuel gas and combustion air at a predetermined mixture ratio. In addition to city gas, propane, hydrogen, and the like may be used as fuel gas. In this case, the composition of the fuel gas will be different, and in order to perform proper combustion, it is necessary to appropriately change the mixing ratio of the fuel gas and the combustion air.

For example, in the fuel supply system described in Patent Document 1, in order to perform suitable fuel supply even when the properties of the gas fuel change, a thermal flow meter and a A composition-independent flow meter capable of measuring the flow rate is used. When the degree of divergence between the measured value of the thermal flow meter and the measured value of the composition-independent flow meter is large enough to indicate an abnormal state, the amount of gas fuel supplied to the supply target by the fuel supply device is adjusted. It is

WO2013/111776

In the fuel supply system of Patent Document 1, for example, when the composition (kind) of the fuel gas is intentionally different, by using the difference in the characteristic coefficient in the thermal flowmeter according to the composition of the fluid, No effort has been made to appropriately change the mixing ratio of the fuel gas and the combustion air. Further, in the fuel supply system of Patent Document 1, there is no device for estimating the composition of the fuel gas when the composition (kind) of the fuel gas is intentionally changed. Therefore, further ingenuity is required in order to more appropriately generate a mixed fluid with a required composition.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object thereof is to provide a composition estimation device and a fluid mixing system capable of more appropriately generating a fluid having a required composition.

One aspect of the present invention is
a thermal flow meter configured to measure the mass flow rate of a reference fluid of a specific composition and configured to measure the mass flow rate of a measurement fluid different from the reference fluid flowing through the pipe;
a volumetric flowmeter arranged in series with the thermal flowmeter in the pipe and measuring a volumetric flow rate of the fluid to be measured flowing through the pipe;
a is the characteristic coefficient of the reference fluid set in the thermal flowmeter, Qa is the mass flow rate of the measurement fluid measured by the thermal flowmeter, and the volumetric flow rate of the measurement fluid is measured by the volumetric flowmeter is Qb, the characteristic coefficient b of the fluid to be measured is obtained by b=a×Qa/Qb, and an arithmetic device for estimating the composition of the fluid to be measured based on the characteristic coefficient b of the fluid to be measured. in the estimation device.

Another aspect of the invention is
A fluid mixing system that generates a mixed fluid in which a first fluid and a second fluid are mixed and sets a mixing ratio of the first fluid and the second fluid in the mixed fluid to a target mixing ratio,
a first pipe to which the first fluid is supplied;
a second pipe to which the second fluid is supplied;
a confluence pipe where the first pipe and the second pipe are joined;
a thermal flow meter arranged in the junction pipe and configured to measure a mass flow rate of a reference fluid having a specific composition and measuring a mass flow rate of the mixed fluid flowing through the junction pipe;
a volumetric flowmeter arranged in series with the thermal flowmeter in the confluence pipe and measuring a volumetric flow rate of the mixed fluid flowing through the confluence pipe;
a control valve for adjusting the mixing ratio of the first fluid and the second fluid;
a control device that controls the thermal flowmeter, the volumetric flowmeter, and the adjustment valve;
The control device is
an information acquisition unit that acquires information on the composition of the first fluid, the composition of the second fluid, and the target mixing ratio;
A mass flow rate measured by the thermal flowmeter and a volumetric flow rate measured by the volumetric flowmeter for the mixed fluid having the target mixing ratio when the composition of the first fluid, the composition of the second fluid, and the target mixing ratio are determined. A relationship setting unit in which a target flow rate relationship or a target specific coefficient is set based on the relationship of
so that the measured flow rate relationship between the measured mass flow rate measured by the thermal flow meter and the measured volume flow rate measured by the volume flow meter matches the target flow rate relationship, or the measured mass flow rate and the measured volume flow rate and an opening adjustment unit that adjusts the opening of the adjustment valve so that the measured specific coefficient based on the specific coefficient of the reference fluid matches the target specific coefficient.

(Composition estimating device of one aspect)
In the composition estimating device of the above aspect, a configuration in which a thermal flow meter and a volumetric flow meter are arranged in series in a pipe, a specific coefficient a of the reference fluid set in the thermal flow meter, and the thermal flow meter Using the measured mass flow rate Qa of the measurement fluid and the volumetric flow rate Qb of the measurement fluid measured by the volumetric flowmeter, the composition of the measurement fluid whose mass flow rate is measured by the thermal flowmeter is estimated. A specific coefficient in a thermal flowmeter indicates a specific value according to the composition of the fluid whose mass flow rate is measured by the thermal flowmeter, and is determined according to the composition of the fluid.

In the composition estimating device of the aspect, the composition of the fluid to be measured whose mass flow rate is measured by the thermal flowmeter is estimated by utilizing the difference in the characteristic coefficients of the thermal flowmeter according to the composition of the fluid. Specifically, focusing on the fact that the product of the characteristic coefficient a of the reference fluid and the mass flow rate Qa of the measurement fluid is equivalent to the product of the characteristic coefficient b of the measurement fluid and the volumetric flow rate Qb of the measurement fluid, determines the characteristic coefficient b of the fluid to be measured by b=a×Qa/Qb, and estimates the composition of the fluid to be measured based on the characteristic coefficient b of the fluid to be measured. The relationship between the characteristic coefficient b of the fluid to be measured and the composition of the fluid to be measured may be obtained by tests, theoretical calculations, or the like.

With this configuration, the composition of the fluid to be measured can be estimated when the composition of the fluid to be measured differs from the composition of the reference fluid by using a pipe in which the thermal flowmeter and the volumetric flowmeter are arranged in series. can. Therefore, for example, when the fluid to be measured is fuel gas or a mixture of a known fuel gas and combustion air, the composition of the fuel gas or mixture can be estimated. can be appropriately mixed.

Therefore, according to the composition estimating device of the aspect, by estimating the composition of the fluid to be measured, it is possible to more appropriately generate the fluid having the required composition.

(Fluid Mixing System of Another Embodiment)
In the fluid mixing system of the other aspect, a configuration in which a thermal flow meter and a volumetric flow meter are arranged in series in a confluence pipe through which a mixed fluid in which the first fluid and the second fluid are mixed is used. Therefore, when using a mixed fluid having a composition different from the composition of the reference fluid set in the thermal flowmeter, the mixing ratio of the first fluid and the second fluid is devised to be the target mixing ratio. In the fluid mixing system of the other aspect, the control device utilizes the difference in characteristic coefficients in the thermal flowmeter according to the composition of the fluid to obtain information on the composition of the first fluid and the composition of the second fluid. is obtained, the opening degree of the regulating valve is adjusted to bring the mixture ratio of the first fluid and the second fluid to the target mixture ratio.

Specifically, the control device has an information acquisition section, a relationship setting section, and an opening adjustment section. Then, the information acquiring unit acquires each information of the composition of the first fluid, the composition of the second fluid, and the target mixing ratio, and the relationship setting unit acquires the composition of the first fluid, the composition of the second fluid, and the target mixing ratio. A target flow rate relationship or a target specific coefficient is set based on the relationship between the mass flow rate by the thermal flow meter and the volume flow rate by the volumetric flow meter for the mixed fluid of the target mixing ratio when determined. The target flow relationship reflects the relationship between the specific coefficient of the reference fluid in the thermal flow meter and the target specific coefficient of the mixed fluid of the target mixing ratio in the thermal flow meter.

Then, the opening adjustment unit adjusts the measured flow rate relationship between the measured mass flow rate measured by the thermal flow meter and the measured volume flow rate measured by the volumetric flow meter to match the target flow rate relationship, or , the opening of the regulating valve is adjusted such that the measured characteristic coefficient based on the measured volumetric flow rate and the characteristic coefficient of the reference fluid matches the target characteristic coefficient. When the measured flow rate relationship matches the target flow rate relationship within an allowable range, or when the measured specific coefficient matches the target specific coefficient within an allowable range, it can be determined that a mixed fluid with the target composition has been generated. can. Therefore, for example, when the first fluid is fuel gas and the second fluid is combustion air, the mixture ratio of fuel gas and combustion air can be set to the target mixture ratio.

Therefore, according to the fluid mixing system of the other aspect, the mixed fluid with the desired composition can be more appropriately generated by generating the mixed fluid with the target mixing ratio.

FIG. 1 is an explanatory diagram showing a composition estimation device according to a first embodiment. FIG. 2 is an explanatory diagram showing a fluid mixing system according to Embodiment 2. FIG. FIG. 3 is a graph showing the target flow rate relationship between the volumetric flow rate and the mass flow rate, and the relationship between the intrinsic coefficient of the reference fluid and the intrinsic coefficient of the mixed fluid according to the second embodiment. FIG. 4 is a graph showing the relationship between the volumetric flow rate and the mass flow rate according to the second embodiment using measured values and theoretical values. FIG. 5 is a flow chart showing a main routine of a fluid mixing system control method according to the second embodiment. FIG. 6 is a flow chart showing a first adjustment routine of a fluid mixing system control method according to the second embodiment. FIG. 7 is a flow chart showing a second adjustment routine of the fluid mixing system control method according to the second embodiment.

Preferred embodiments of the composition estimation device and fluid mixing system described above will be described with reference to the drawings.
<Embodiment 1>
A composition estimating device 1A of the present embodiment, as shown in FIG. 1, includes a thermal flowmeter 2, a volumetric flowmeter 3, and an arithmetic device 4A. The thermal flow meter 2 is set to measure the mass flow rate Qa of a reference fluid having a specific composition, and is configured to measure the mass flow rate Qa of a measurement fluid M flowing through the pipe 5 that is different from the reference fluid. The volumetric flowmeter 3 is arranged in series with the thermal flowmeter 2 in the pipe 5 and configured to measure the volumetric flow rate Qb of the measurement fluid M flowing through the pipe 5 .

Arithmetic device 4A calculates a characteristic coefficient of the reference fluid set in thermal flowmeter 2, Qa the mass flow rate of measured fluid M measured by thermal flowmeter 2, and Qa the measured fluid measured by volumetric flowmeter 3. When the volume flow rate of M is Qb, the characteristic coefficient b of the fluid to be measured M is obtained by b=a×Qa/Qb, and the composition of the fluid to be measured M is estimated based on the characteristic coefficient b of the fluid to be measured M. ing.

Below, composition estimation device 1A of this embodiment is explained in full detail.
As shown in FIG. 1, the composition estimating device 1A makes it possible to supply an air-fuel mixture as a fluid having a required composition to a combustion device 6 that burns the air-fuel mixture of fuel gas and combustion air. be. A pipe 5 constituting the composition estimating apparatus 1A is connected to a combustion device 6 and is for supplying an air-fuel mixture as a measurement fluid M to the combustion device 6 .

The measurement fluid M and the reference fluid in this embodiment are mixtures of fuel gas and combustion air as gas. Fuel gas includes city gas, propane, hydrogen, and the like. Combustion air includes air (fresh air), mixed air of air and exhaust gas, and the like. The pipe 5 is connected to a supply source 50 of the fluid M to be measured.

(Thermal flow meter 2)
As shown in FIG. 1, the thermal flow meter 2 measures the gas mass flow rate Qa [g/s]. The thermal flow meter 2 detects the mass flow rate Qa based on the change in the amount of heat associated with the movement of the fluid M to be measured per unit time. The thermal flowmeter 2 includes a heater, a temperature sensor arranged upstream of the heater, and a temperature sensor arranged downstream of the heater. The thermal flow meter 2 includes a temperature difference measurement method that measures the flow rate based on the difference between the temperature of the fluid upstream of the heater and the temperature of the fluid downstream of the heater, and the temperature difference measurement method of the fluid upstream of the heater. and the temperature of the fluid on the downstream side of the heater, the heater is controlled so that the temperature difference is constant.

The thermal flowmeter 2 causes an error in the measurement result of the mass flow rate Qa when the composition of the fluid M to be measured changes. In the thermal flowmeter 2, a specific coefficient is set according to the composition of the fluid in order to correctly measure the mass flow rate Qa. The amount of heat H [J] taken away by the measuring part of the thermal flowmeter 2 is the mass flow rate Qa [g/s] of the thermal flowmeter 2, the density ρ [g/m ³ ], the low-pressure specific heat c [J/(g ·K)], and using the thermal conductivity λ [W/(m·K)], it is expressed by H∝Qa·ρ·c/λ. In other words, H is proportional to Qa·ρ·c/λ. While the mass flow rate Qa and the heat quantity H change as appropriate, ρ·c/λ, which is determined by the density ρ, the low-pressure specific heat c, and the thermal conductivity λ, takes unique values according to various gas mixtures.

The composition estimating apparatus 1A of this embodiment intentionally causes an error in the mass flow rate Qa measured by the thermal flowmeter 2 by making the measurement fluid M different from the reference fluid set in the thermal flowmeter 2. , the error is used to estimate the composition of the fluid M to be measured. This error is caused by a difference in the eigenvalue of ρ·c/λ, which is the coefficient of measurement by the thermal flowmeter 2, depending on the composition of the fluid M to be measured.

(Volume flow meter 3)
As shown in FIG. 1, the volumetric flowmeter 3 measures the gas volumetric flow rate Qb [m ³ /s]. The volumetric flowmeter 3 detects the volumetric flow rate Qb of the fluid M to be measured flowing through the pipe 5 based on the change in volume of the fluid M to be measured per unit time. The volumetric flowmeter 3 is a volumetric flowmeter that measures the flow rate using the rotation of two elliptical gears that mesh with each other. There are vortex flowmeters that measure the flow rate, and turbine flowmeters that measure the flow rate using the rotation of the impeller. The volumetric flowmeter 3 can appropriately measure the flow rate of the fluid M to be measured regardless of the composition of the fluid M to be measured.

(Arithmetic device 4A)
As shown in FIG. 1, the arithmetic unit 4A is composed of a computer such as a sequencer (programmable computer). The computing device 4A is configured to receive information on the mass flow rate Qa of the measurement fluid M from the thermal flowmeter 2 and to receive information on the volumetric flow rate Qb of the measurement fluid M from the volumetric flowmeter 3 . Further, the arithmetic unit 4A is configured to receive information on the characteristic coefficient a of the reference fluid set in the thermal flowmeter 2. FIG.

The intrinsic coefficient a of the reference fluid is indicated by the eigenvalue of ρ1·c1/λ1, which is the coefficient measured by the thermal flowmeter 2, using the density ρ1, the low pressure specific heat c1 and the thermal conductivity λ1 for the reference fluid. The characteristic coefficient b of the fluid M to be measured is indicated by the characteristic value of ρ2·c2/λ2, which is the coefficient of measurement by the thermal flowmeter 2, using the density ρ2, the low-pressure specific heat c2, and the thermal conductivity λ2 of the fluid M to be measured. . When the composition of the fluid to be measured M differs from that of the reference fluid, the arithmetic unit 4A calculates the characteristic coefficient a that is the characteristic value of ρ1·c1/λ1 of the reference fluid and the characteristic value of ρ2·c2/λ2 of the measurement fluid M. The fact that the coefficient b is different is used.

While the composition of the reference fluid is known, the composition of the measurement fluid M is unknown. In the arithmetic device 4A, characteristic coefficients, which are characteristic values of ρ·c/λ, are obtained for mixtures as various gases. The specific coefficient may be obtained by actually measuring the mass heat quantity Qa when the gas is flowed through the pipe 5 in which the thermal flow meter 2 is arranged, and the density ρ, the low pressure specific heat c, and the heat conduction It may be obtained by calculation using the value of the rate λ. Then, the calculation device 4A estimates the composition of the measurement fluid M, which is various gases, based on the characteristic coefficients.

If the composition of the measurement fluid M is different from that of the reference fluid, the value of the mass flow rate Qa measured by the thermal flowmeter 2 will be different from the value of the volumetric flow rate Qb measured by the volumetric flowmeter 3. . Then, using the characteristic coefficient a of the reference fluid, the mass flow rate Qa and the volumetric flow rate Qb, the arithmetic unit 4A obtains the characteristic coefficient b of the measured fluid M by b=a×Qa/Qb, and obtains the characteristic coefficient b of the measured fluid M It becomes possible to estimate the composition of the measurement fluid M based on.

(Effect)
In the composition estimating apparatus 1A of this embodiment, the composition of the fluid M to be measured is estimated using the characteristic coefficient a of the reference fluid, the mass flow rate Qa of the fluid M to be measured, and the volumetric flow rate Qb of the fluid M to be measured. The specific coefficient in the thermal flowmeter 2 indicates a specific value according to the composition of the fluid whose mass flow rate Qa is measured by the thermal flowmeter 2, and is determined according to the composition of the fluid.

In the composition estimating device 1A of this embodiment, the difference in the characteristic coefficient in the thermal flowmeter 2 according to the composition of the fluid, in other words, the product of the characteristic coefficient a of the reference fluid and the mass flow rate Qa of the measurement fluid M is Utilizing the fact that it is equivalent to the product of the characteristic coefficient b of the measured fluid M and the volumetric flow rate Qb of the measured fluid M, the characteristic coefficient b of the measured fluid M is obtained by b=a×Qa/Qb, and the measured fluid M The composition of the measured fluid M is estimated based on the characteristic coefficient b of . With this configuration, the composition of the measurement fluid M can be estimated when the composition of the measurement fluid M whose flow rate is to be measured is different from the composition of the reference fluid. Therefore, for example, when the measurement fluid M is a fuel gas or a known mixture of fuel gas and combustion air, the composition of the fuel gas or the mixture can be estimated, and the composition of the fuel gas and combustion air can be estimated. can be appropriately mixed with.

Therefore, according to the composition estimation device 1A of the present embodiment, by estimating the composition of the measurement fluid M, it is possible to more appropriately generate the fluid having the required composition.

<Embodiment 2>
This embodiment shows a fluid mixing system 1B that obtains a mixed fluid M1 having a target mixing ratio using a pipe 5 in which a thermal flowmeter 2 and a volumetric flowmeter 3 are arranged in series. The fluid mixing system 1B of this embodiment generates the mixed fluid M1 in which the first fluid R1 and the second fluid R2 are mixed, and sets the mixing ratio of the first fluid R1 and the second fluid R2 in the mixed fluid M1 to the target mixing ratio. It is a ratio.

As shown in FIG. 2, the fluid mixing system 1B includes a first pipe 5A, a second pipe 5B, a confluence pipe 5C, a thermal flowmeter 2, a volumetric flowmeter 3, adjustment valves 51 and 52, and a controller 4B. The first pipe 5A is supplied with the first fluid R1. The second pipe 5B is supplied with the second fluid R2. The confluence pipe 5C is a combination of the first pipe 5A and the second pipe 5B. The thermal flow meter 2 is arranged in the confluence pipe 5C, is set to measure the mass flow rate Qa of the reference fluid having a specific composition, and It is arranged to measure the mass flow rate Qa.

The volumetric flowmeter 3 is arranged in series with the thermal flowmeter 2 in the confluence pipe 5C, and is configured to measure the volumetric flow rate Qb of the mixed fluid M1 (measurement fluid M) flowing through the confluence pipe 5C. . The adjustment valves 51 and 52 are for adjusting the mixing ratio of the first fluid R1 and the second fluid R2. The control device 4B is configured to control the thermal flowmeter 2, the volumetric flowmeter 3, and the control valves 51,52.

The control device 4B has an information acquisition section 41 , a relationship setting section 42 and an opening adjustment section 43 . The information acquisition unit 41 is configured to acquire information on the composition of the first fluid R1, the composition of the second fluid R2, and the target mixing ratio. The relationship setting unit 42 calculates the mass flow rate Qa by the thermal flowmeter 2 and the volumetric flowmeter for the mixed fluid M1 having the target mixing ratio when the composition of the first fluid R1, the composition of the second fluid R2, and the target mixing ratio are determined. 3 is configured to set a target flow rate relationship based on the relationship with the volumetric flow rate Qb. The relationship setting unit 42 may be configured to set the target specific coefficient b _r based on the relationship between the mass flow rate Qa and the volumetric flow rate Qb for the mixed fluid M1 having the target mixing ratio.

The opening adjustment unit 43 adjusts the measured flow rate relationship between the measured mass flow rate Qa measured by the thermal flowmeter 2 and the measured volumetric flow rate Qb measured by the volumetric flowmeter 3 to match the target flow rate relationship. It is configured to adjust the opening degrees of the valves 51 and 52 . The opening adjustment unit 43 adjusts the adjustment valves 51 and 52 so that the measured specific coefficient b _m based on the measured mass flow rate Qa, the measured volumetric flow rate Qb, and the specific coefficient a of the reference fluid matches the target specific coefficient b _r . may be adjusted.

The fluid mixing system 1B of this embodiment will be described in detail below.
As shown in FIG. 2, the fluid mixing system 1B supplies an air-fuel mixture as a mixed fluid M1 having a target mixture ratio to a combustion device 6 that burns an air-fuel mixture of fuel gas and combustion air. The confluence pipe 5C is connected to the combustion equipment 6 and is for supplying the mixture as the mixed fluid M1 to the combustion equipment 6 . The first pipe 5A is connected to a fuel gas supply source 53A, and the second pipe 5B is connected to a combustion air supply source 53B such as a fan.

The regulating valves 51 and 52 include a first regulating valve 51 arranged on the first pipe 5A and a second regulating valve 52 arranged on the second pipe 5B. The thermal flowmeter 2 and volumetric flowmeter 3 are the same as those shown in the first embodiment.

The thermal flow meter 2 of this embodiment is set to measure the mass flow rate Qa of a mixture of city gas and combustion air (fresh air) as a reference fluid of a specific composition. In other words, in the thermal flow meter 2, a specific coefficient is set for the mixture of city gas and combustion air. In this embodiment, the first fluid R1 is a gas such as propane or hydrogen, which has a different composition from city gas, and the second fluid R2 is combustion air. Both the first fluid R1 and the second fluid R2 may be fuel gas. For example, the first fluid R1 and the second fluid R2 may be city gas and hydrogen, or propane and hydrogen.

(Information acquisition unit 41)
As shown in FIG. 2, the information acquisition unit 41 of the control device 4B obtains the composition of propane as the first fluid R1, the composition of the combustion air as the second fluid R2, and the composition of the first fluid R1 and the second fluid R2. It is configured to acquire each information of the target mixture ratio of. The target mixture ratio is set as an air ratio (excess air ratio) or an air-fuel ratio at which propane and combustion air can be stably combusted without misfiring. Information on the type of the first fluid R1, the type of the second fluid R2, and the target mixing ratio is input to the information acquisition unit 41 by an input operation by the administrator of the fluid mixing system 1B. Further, in the information acquisition unit 41, the characteristic coefficient b1 of the first fluid R1 and the characteristic coefficient b2 of the second fluid R2 are obtained. These specific coefficients b1 and b2 are used to determine whether the opening degree of the first control valve 51 or the second control valve 52 should be increased or decreased.

(Relationship setting unit 42)
As shown in FIG. 2, in the relationship setting unit 42 of the control device 4B, various kinds of the first fluid R1 and the second fluid R2 are set, and the mixing ratio of the first fluid R1 and the second fluid R2 is set appropriately. A target flow rate relationship between the mass flow rate Qa by the thermal flow meter 2 and the volumetric flow rate Qb by the volumetric flow meter 3 when changed is set. Further, in the relationship setting unit 42 of the present embodiment, when the composition of the first fluid R1 and the composition of the second fluid R2 are determined, the target flow rate when the mixing ratio of the first fluid R1 and the second fluid R2 changes relationship is set. When the composition of the mixed fluid M1 flowing through the confluence pipe 5C changes, the volumetric flow rate Qb determined by the volumetric flowmeter 3 does not change, while the mass flow rate Qa determined by the thermal flowmeter 2 changes. The ratio of the mass flow rate Qa determined by the thermal flowmeter 2 to the volumetric flow rate Qb determined by the volumetric flowmeter 3 changes according to the change in the composition of the mixed fluid M1.

As shown in FIG. 3, the target flow rate relationship changes the ratio of the flow rate of the second fluid R2 to the flow rate of the first fluid R1 when the composition of the first fluid R1, in other words, the type of fuel gas is determined. , or the relationship between the characteristic coefficient a of the reference fluid and the characteristic coefficient b of the mixed fluid M1 (measurement fluid M). The relationship between the volumetric flow rate Qb and the mass flow rate Qa is a linear proportional relationship, which is also expressed as the ratio between the characteristic coefficient a of the reference fluid and the characteristic coefficient b of the mixed fluid M1 (measurement fluid M).

As in the first embodiment, this embodiment also utilizes the relationship that the product of the characteristic coefficient a of the reference fluid and the mass flow rate Qa is equivalent to the product of the characteristic coefficient b of the measurement fluid M and the volumetric flow rate Qb. This relationship is expressed as a·Qa=b·Qb, or rewritten as Qb=(a/b)·Qa. The relationship between volumetric flow rate Qb and mass flow rate Qa is represented by a straight line having a gradient of a/b.

The target flow rate relationship Qa _r /Qb _r between the mass flow rate Qa _r and the volumetric flow rate Qb _r for the mixed fluid M1 with the target mixing ratio is obtained by the formula b _r =a·(Qa _r /Qb _r ) and the characteristic of the reference fluid Based on the fact that the coefficient a is known, it is also expressed as the characteristic coefficient _br of the mixed fluid M1 of the target mixing ratio. This eigencoefficient b _r is given by the eigenvalue of b _r =ρ·c/λ, using the density ρ, the low pressure specific heat c and the thermal conductivity λ for the mixed fluid M1 at the target mixing ratio.

Also, in this case, the measured flow rate relationship Qa/Qb between the measured mass flow rate Qa and the measured volumetric flow rate Qb is given by the formula b _m =a·(Qa/Qb), and the characteristic coefficient a of the reference fluid is known. , it is also expressed as the measurement specific coefficient b _m of the measured mixed fluid M1. This measured characteristic coefficient b _m is calculated using the characteristic coefficient a of the reference fluid, the measured mass flow rate Qa and the measured volumetric flow rate Qb.

In FIG. 4 , the thermal flowmeter 2 is set as a mixture of city gas and combustion air as the reference fluid, and the mixture of propane and combustion air is used as the mixed fluid M1. A relationship between the volumetric flow rate Qb and the mass flow rate Qa when the flow rate Qa is measured and the volumetric flow rate Qb is measured by the volumetric flowmeter 3 is shown as a first straight line L1. In FIG. 4, the relationship between the calculated volumetric flow rate Qb and the mass flow rate Qa obtained from the ratio of the characteristic coefficient a of the reference fluid and the characteristic coefficient b of the mixed fluid M1 (measured fluid M) is represented by a second straight line Denoted as L2. There is a slight difference between the first straight line L1 and the second straight line L2. The target flow rate relationship and the target specific coefficient _br may be determined by calibrating between actual measurements and theoretical values.

When setting the target flow rate relationship, a correction coefficient is obtained so that the second straight line L2, which is the relationship of the theoretical values, becomes closer to the first straight line L1, which is the relationship of the actual measured values. Then, the target flow rate relation is the corrected target flow rate relation obtained by correcting the second straight line L2 by the correction coefficient.

On the other hand, the correction coefficient may be obtained so that the first straight line L1, which is the relationship of the measured values, becomes closer to the second straight line L2, which is the relationship of the theoretical values. In this case, the opening adjusting unit 43 adjusts the relationship between the measured mass flow rate Qa and the measured volumetric flow rate Qb, which is corrected by the correction coefficient, so that the corrected measured flow rate relationship matches the target flow rate relationship. Adjust the valves 51,52.

(Opening adjustment unit 43)
As shown in the figure, the opening adjusting unit 43 adjusts the opening of the first adjusting valve 51 to determine the supply amount of the fuel gas as the first fluid R1 used for combustion, and then the second adjusting valve 52 is adjusted to determine the amount of combustion air supplied as the second fluid R2 used for combustion. Then, the opening degree adjustment unit 43 adjusts the second adjustment valve 52 so that the measured flow rate relationship matches the target flow rate relationship, and the mixture supplied to the combustion device 6 as the mixed fluid M1 having the target mixture ratio. configured to determine an air ratio;

(Control method of fluid mixing system 1B)
A method of controlling the fluid mixing system 1B will be described below with reference to the flow charts of FIGS. 5 to 7. FIG. Each flow chart also shows a case where the relationship setting unit 42 uses the target specific coefficient b _r instead of the target flow rate relationship.

In the main routine of FIG. 5, the control device 4B causes the information acquisition unit 41 to determine the type of fuel gas used for the first fluid R1, the use of combustion air for the second fluid R2, and the Each piece of information on the target mixing ratio with the fluid R2 is acquired (step S101 in FIG. 5). At this time, the characteristic coefficient b1 of the first fluid R1 and the characteristic coefficient b2 of the second fluid R2 are acquired. These unique coefficients b1 and b2 are obtained based on the database in the information acquisition unit 41 (step S102). Further, the control device 4B obtains and sets the target specific coefficient b _r of the mixture (mixed fluid M1) of the fuel gas and the combustion air having the target mixture ratio in the relationship setting unit 42 (step S103 ).

Next, the control device 4B adjusts the opening degree of the first adjustment valve 51 by the opening degree adjustment unit 43, and determines the flow rate of the fuel gas as the first fluid R1 flowing from the first pipe 5A to the confluence pipe 5C. (Step S104). Next, the control device 4B adjusts the opening degree of the second adjustment valve 52 by the opening degree adjustment unit 43 to change the flow rate of the combustion air as the second fluid R2 flowing from the second pipe 5B to the confluence pipe 5C. (step S105).

Next, the control device 4B measures the mass flow rate Qa of the air-fuel mixture with the thermal flowmeter 2, and measures the volumetric flow rate Qb of the air-fuel mixture with the volumetric flowmeter 3 (step S106). Then, the controller 4B obtains the measured specific coefficient b _m of the air-fuel mixture using the specific coefficient a of the reference fluid, the measured mass flow rate Qa, and the measured volumetric flow rate Qb (step S107). .

Next, the control device 4B determines whether the measured specific coefficient b _m of the air-fuel mixture is within the allowable range of the target specific coefficient b _r of the air-fuel mixture having the target mixture ratio (step S108). The allowable range for the target specific coefficient b _r is expressed as b _r ±α. When the measured specific coefficient b _m is within the allowable range of the target specific coefficient b _r , the mixing ratio of the first fluid R1 and the second fluid R2 in the air-fuel mixture is within the allowable range of the target mixing ratio. Then, the degree of opening of the second control valve 52 is fixed (step S109).

On the other hand, if the measured specific coefficient b _m is not within the allowable range of the target specific coefficient b _r , the control device 4B determines whether the specific coefficient b1 of the first fluid R1 is greater than the specific coefficient b2 of the second fluid R2. (step S110). If the characteristic coefficient b1 of the first fluid R1 is greater than the characteristic coefficient b2 of the second fluid R2, the control device 4B executes a first adjustment routine (step S111).

In the first adjustment routine in FIG. 6, it is determined whether or not the measured specific coefficient b _m exceeds the allowable range of the target specific coefficient b _r (step S201 in FIG. 6). If the measured specific coefficient b _m exceeds the allowable range of the target specific coefficient b _r , the degree of opening of the second control valve 52 is increased by a predetermined amount (step S202). On the other hand, when the measured specific coefficient b _m does not exceed the allowable range of the target specific coefficient b _r , it is determined that the measured specific coefficient b _m is less than the allowable range of the target specific coefficient b _r , and the second control valve 52 is opened. degree is reduced by a predetermined amount (step S203).

For example, when the first fluid R1 is propane, the characteristic coefficient b1 calculated by ρ·c/λ using the density ρ, the low-pressure specific heat c, and the thermal conductivity λ is 0.2042. Further, the characteristic coefficient b2 calculated by ρ·c/λ for the combustion air (fresh air) as the second fluid R2 is 0.0538. When the characteristic coefficient b1 of the first fluid R1 is larger than the characteristic coefficient b2 of the second fluid R2 and the measured characteristic coefficient _bm exceeds the allowable range of the target characteristic coefficient b _r , as the second fluid R2 is determined to be insufficient for combustion air, and the degree of opening of the second control valve is increased by a predetermined amount. On the other hand, when the characteristic coefficient b1 of the first fluid R1 is larger than the characteristic coefficient b2 of the second fluid R2 and the measured characteristic coefficient b _m does not exceed the allowable range of the target characteristic coefficient b _r , the second fluid R2 is determined to be excessive, and the degree of opening of the second control valve is reduced by a predetermined amount.

Next, returning from the first adjustment routine to the main routine, the controller 4B measures the mass flow rate Qa of the air-fuel mixture again with the thermal flowmeter 2, and measures the volumetric flow rate Qb of the air-fuel mixture with the volumetric flowmeter 3 again. (Step S106 in FIG. 5). Then, the control device 4B uses the reference fluid specific coefficient a, the measured mass flow rate Qa, and the measured volumetric flow rate Qb to obtain again the measured specific coefficient _bm of the air-fuel mixture (step S107 ).

In step S110, if the characteristic coefficient b1 of the first fluid R1 is not greater (smaller) than the characteristic coefficient b2 of the second fluid R2, the control device 4B executes a second adjustment routine (step S112). In the second adjustment routine in FIG. 7, it is determined whether or not the measured specific coefficient b _m exceeds the allowable range of the target specific coefficient b _r (step S301 in FIG. 7). If the measured specific coefficient b _m exceeds the allowable range of the target specific coefficient b _r , the degree of opening of the second control valve 52 is decreased by a predetermined amount (step S302). On the other hand, when the measured specific coefficient b _m does not exceed the allowable range of the target specific coefficient b _r , it is determined that the measured specific coefficient b _m is less than the allowable range of the target specific coefficient b _r , and the second control valve 52 is opened. degree is increased by a predetermined amount (step S303).

For example, when the first fluid R1 is hydrogen, the specific coefficient b1 is 0.0076. Further, the characteristic coefficient b2 for combustion air (fresh air) as the second fluid R2 is 0.0538. When the characteristic coefficient b1 of the first fluid R1 is smaller than the characteristic coefficient b2 of the second fluid R2, and the measured characteristic coefficient b _m exceeds the allowable range of the target characteristic coefficient b _r , as the second fluid R2 is excessive, and the degree of opening of the second control valve is reduced by a predetermined amount. On the other hand, when the characteristic coefficient b1 of the first fluid R1 is smaller than the characteristic coefficient b2 of the second fluid R2 and the measured characteristic coefficient b _m does not exceed the allowable range of the target characteristic coefficient b _r , the second fluid R2 It is determined that the combustion air is insufficient, and the degree of opening of the second control valve is increased by a predetermined amount.

Next, returning from the second adjustment routine to the main routine, the control device 4B measures the mass flow rate Qa of the air-fuel mixture again with the thermal flowmeter 2, and measures the volumetric airflow rate Qb of the air-fuel mixture with the volumetric flowmeter 3 again. (Step S106 in FIG. 5). Then, the control device 4B uses the reference fluid specific coefficient a, the measured mass flow rate Qa, and the measured volumetric flow rate Qb to obtain again the measured specific coefficient _bm of the air-fuel mixture (step S107 ).

After that, steps S106 to S112 are repeated until the measured specific coefficient b _m is within the allowable range of the target specific coefficient b _r . Then, when the mixture ratio of the air-fuel mixture falls within the allowable range of the target mixture ratio, the degree of opening of the second control valve 52 is fixed (step S109). Thus, the mixture ratio (air ratio) of the air-fuel mixture supplied to the combustion equipment 6 is set within the allowable range of the target mixture ratio.

In the control method of the fluid mixing system 1B of this embodiment, the case where the first fluid R1 is the fuel gas and the second fluid R2 is the combustion air has been described. In addition to this, the first fluid R1 and the second fluid R2 may be various fuel gases having different compositions.

(Effect)
In the fluid mixing system 1B of this embodiment, the control device 4B utilizes the difference in the characteristic coefficients of the thermal flowmeter 2 according to the composition of the fluid to determine the composition of the first fluid R1 and the composition of the second fluid R2. is obtained, the opening degrees of the adjustment valves 51 and 52 are adjusted to bring the mixture ratio of the first fluid R1 and the second fluid R2 to the target mixture ratio.

Specifically, the control device 4B has an information acquisition section 41 , a relationship setting section 42 and an opening adjustment section 43 . Then, the information acquisition unit 41 acquires the composition of the first fluid R1, the composition of the second fluid R2, and the target mixing ratio, and the relationship setting unit 42 acquires the composition of the first fluid R1, the composition of the second fluid R2, and the composition of the second fluid R2. Target flow rate relationship or target specific coefficient b based on the relationship between the mass flow rate Qa by the thermal flow meter 2 and the volume flow rate Qb by the volume flow meter 3 for the mixed fluid M1 with the target mixing ratio when the composition and the target mixing ratio are determined _r is set. The target flow rate relationship reflects the relationship between the specific coefficient a of the reference fluid in the thermal flow meter 2 and the target specific coefficient b _r of the mixed fluid M1 of the target mixing ratio in the thermal flow meter 2 .

Then, the opening adjustment unit 43 adjusts the measured flow rate relationship between the measured mass flow rate Qa measured by the thermal flowmeter 2 and the measured volumetric flow rate Qb measured by the volumetric flowmeter 3 to match the target flow rate relationship. Alternatively, the opening degrees of the regulating valves 51 and 52 are adjusted so that the measured specific coefficient b _m based on the measured mass flow rate Qa, the measured volumetric flow rate Qb, and the specific coefficient a of the reference fluid matches the target specific coefficient b _r . When the measured flow rate relationship matches the target flow rate relationship within an allowable range, or when the measured specific coefficient b _m matches the target specific coefficient b _r within an allowable range, the mixed fluid M1 having the target composition is generated. can be determined. Therefore, when the fuel gas is used as the first fluid R1 and the combustion air is used as the second fluid R2, the mixture ratio of the fuel gas and the combustion air can be set to the target mixture ratio.

Therefore, according to the fluid mixing system 1B of the present embodiment, by generating the mixed fluid M1 with the target mixing ratio, it is possible to more appropriately generate the mixed fluid M1 with the required composition.

Other configurations, effects, and the like in the fluid mixing system 1B of the present embodiment are the same as the configuration, effects, and the like of the composition estimation device 1A of the first embodiment. Also in the present embodiment, constituent elements indicated by the same reference numerals as those in the first embodiment are the same as those in the first embodiment.

<Other embodiments>
The first fluid R1 and the second fluid R2 may be fuel gases having different compositions, and the mixed fluid M may be a mixture of multiple types of fuel gases. In addition, the fluid mixing system 1B is configured in two stages, and is used to generate a mixed fluid having a target mixing ratio in which three types of fluids, ie, the first fluid R1, the second fluid R2, and the third fluid are mixed. good too. In this case, the first-stage fluid mixing system 1B generates a mixed fluid M in which the first fluid R1 and the second fluid R2 are mixed at a target mixing ratio, and the second-stage fluid mixing system 1B produces: The final mixed fluid is generated by mixing the mixed fluid M and the third fluid at the target mixing ratio.

The present invention is not limited to only each embodiment, and further different embodiments can be configured without departing from the scope of the invention. In addition, the present invention includes various modifications, modifications within the equivalent range, and the like. Further, the technical idea of the present invention also includes combinations, forms, and the like of various constituent elements assumed from the present invention.

1A composition estimation device 1B fluid mixing system 2 thermal flowmeter 3 volumetric flowmeter 4A arithmetic device 4B control device 41 information acquisition unit 42 relationship setting unit 43 opening adjustment unit 5 pipe 5A first pipe 5B second pipe 5C confluence pipe 51 First adjusting valve 52 Second adjusting valve 6 Combustion device Qa Mass flow rate Qb Volumetric flow rate M Measured fluid R1 First fluid R2 Second fluid M1 Mixed fluid

Claims (3)

a thermal flow meter configured to measure the mass flow rate of a reference fluid of a specific composition and configured to measure the mass flow rate of a measurement fluid different from the reference fluid flowing through the pipe;
a volumetric flowmeter arranged in series with the thermal flowmeter in the pipe and measuring a volumetric flow rate of the fluid to be measured flowing through the pipe;
a is the characteristic coefficient of the reference fluid set in the thermal flowmeter, Qa is the mass flow rate of the measurement fluid measured by the thermal flowmeter, and the volumetric flow rate of the measurement fluid is measured by the volumetric flowmeter is Qb, the characteristic coefficient b of the fluid to be measured is obtained by b=a×Qa/Qb, and an arithmetic device for estimating the composition of the fluid to be measured based on the characteristic coefficient b of the fluid to be measured. estimation device. A fluid mixing system that generates a mixed fluid in which a first fluid and a second fluid are mixed and sets a mixing ratio of the first fluid and the second fluid in the mixed fluid to a target mixing ratio,
a first pipe to which the first fluid is supplied;
a second pipe to which the second fluid is supplied;
a confluence pipe where the first pipe and the second pipe are joined;
a thermal flow meter arranged in the junction pipe and configured to measure a mass flow rate of a reference fluid having a specific composition and measuring a mass flow rate of the mixed fluid flowing through the junction pipe;
a volumetric flowmeter arranged in series with the thermal flowmeter in the confluence pipe and measuring a volumetric flow rate of the mixed fluid flowing through the confluence pipe;
a control valve for adjusting the mixing ratio of the first fluid and the second fluid;
a control device that controls the thermal flowmeter, the volumetric flowmeter, and the adjustment valve;
The control device is
an information acquisition unit that acquires information on the composition of the first fluid, the composition of the second fluid, and the target mixing ratio;
A mass flow rate measured by the thermal flowmeter and a volumetric flow rate measured by the volumetric flowmeter for the mixed fluid having the target mixing ratio when the composition of the first fluid, the composition of the second fluid, and the target mixing ratio are determined. A relationship setting unit in which a target flow rate relationship or a target specific coefficient is set based on the relationship of
so that the measured flow rate relationship between the measured mass flow rate measured by the thermal flow meter and the measured volume flow rate measured by the volume flow meter matches the target flow rate relationship, or the measured mass flow rate and the measured volume flow rate and an opening adjustment unit that adjusts the opening of the adjustment valve so that the measured specific coefficient based on the specific coefficient of the reference fluid matches the target specific coefficient. In the relationship setting unit, when the composition of the first fluid and the composition of the second fluid are determined, the target flow relationship or the 3. The fluid mixing system of claim 2, wherein target specific coefficients are set.

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