JP2023130036A - estimation device - Google Patents

Abstract

To provide a technique which reduces a measurement delay of the density of a chemical species contained in mixed gas in an estimation device.SOLUTION: An estimation device comprises: an inlet flow rate detection unit which detects an inlet display flow rate Qdisplay_tank_in being a display flow rate of gas supplied to an inlet of a gas tank; an outlet flow rate detection unit which detects an outlet display flow rate Qdisplay_tank_out being a display flow rate of gas at an outlet of the gas tank; a pressure detection unit which detects a tank pressure measurement value Ptank being the pressure in the gas tank; a temperature detection unit which detects a tank temperature measurement value Ttank being the temperature in the gas tank; and an estimation unit which estimates the density XA_tank of a chemical species A and the density XB_tank of a chemical species B in the gas tank by using the inlet display flow rate Qdisplay_tank_in, the outlet display flow rate Qdisplay_tank_out, the tank pressure measurement value Ptank and the tank temperature measurement value Ttank.SELECTED DRAWING: Figure 1

Description

The present invention relates to an estimation device.

BACKGROUND ART Estimating devices that estimate the concentration of chemical species contained in a mixed gas have been known. The estimation device is applied, for example, to a methane production process that produces methane gas through a chemical reaction between carbon dioxide and hydrogen, and is used to grasp the composition of a mixed gas containing carbon dioxide and hydrogen. In such a methane production process, in order to stabilize the quality of methane gas, a gas concentration measuring device is used to continuously measure the concentration of carbon dioxide and hydrogen in the mixed gas. If it is outside the range, it is necessary to add new carbon dioxide or hydrogen and control the concentration.

Japanese Patent Application Publication No. 2019-142806 Japanese Patent Application Publication No. 2020-158403

However, with the gas concentration measuring device, it may take several tens of seconds until the concentration of the gas to be measured becomes clear. In the case of the above-mentioned methane production process, if there is a sudden change in the concentration of carbon dioxide or hydrogen in the mixed gas, the concentration may not be able to be controlled and the quality of the methane gas may not be stable.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a technique for estimating the concentration of chemical species contained in a mixed gas in a short time using an estimation device.

The present invention has been made to solve at least part of the above-mentioned problems, and can be realized as the following forms.

(1) According to one embodiment of the present invention, an estimation device is provided that estimates the composition of a mixed gas containing two different types of chemical species A and chemical species B. This estimating device includes an inlet flow rate detection unit that detects an inlet display flow rate Q _{display_tank_in} that is a display flow rate of gas at the inlet of the gas tank of the gas supplied from the mixed gas supply source to the gas tank; an outlet flow rate detection unit that detects an outlet display flow rate Q _{display_tank_out} that is a display flow rate of , a pressure detection unit that detects a tank pressure measurement value P _tank that is a measurement value of the pressure in the gas tank, and a pressure detection unit that measures the temperature in the gas tank. a temperature detection unit that detects the tank temperature measurement value T _tank , the inlet display flow rate Q _{display_tank_in} , the outlet display flow rate Q _{display_tank_out} , the tank pressure measurement value P _tank , and the tank temperature measurement value T _tank . The concentration of the chemical species A at the inlet of the gas tank X _{A_tank_in} and the concentration of the chemical species B X _{B_tank_in} , the concentration of the chemical species A in the gas tank X _{A_tank} and the concentration of the chemical species B X _{B_tank} , and an estimator that estimates at least one of an actual flow rate Q _{real_tank_in} at the inlet of the gas tank and an actual flow rate Q _{real_tank_out} at the outlet of the gas tank.

According to this configuration, the estimating unit receives the inlet display flow rate Q _{display_tank_in} of the inlet flow rate detection unit, the outlet display flow rate Q _{display_tank_out} of the outlet flow rate detection unit, the tank pressure measurement value P _tank of the pressure detection unit, and the temperature detection unit The concentration of chemical species A in the gas tank, X _{A_tank} , the concentration of chemical species B, X _{B_tank,} etc. in the gas tank is estimated using the tank temperature measurement value T _tank . As a result, the concentration of chemical species can be estimated in a relatively short time, compared to, for example, a gas analyzer that takes several tens of seconds to determine the concentration of the gas to be measured.

Δｎ_tank：ガスタンク内のガスのモル数変化量［ｍｏｌ］
Ｖ_tank：ガスタンクの内容積［Ｌ］
Ｒ：気体定数［Ｊ／Ｋ－ｍｏｌ］
ｔ：現在時刻［ｓ］
Δt：推定装置の制御周期［ｓ］
Ｃ_{real_tank_in}：現在時刻での入口流量検出部の制御定数［－］
Ｃ_{calib_tank_in}：キャリブレーション時の入口流量検出部の制御定数［－］
Ｃ_{A_tank_in}：入口流量検出部の化学種Ａについての制御定数［－］
Ｃ_{B_tank_in}：入口流量検出部の化学種Ｂについての制御定数［－］
この構成によれば、推定部は、タンク圧計測値Ｐ_tankの時間変化に基づいて、ガスタンクの入口の実流量Ｑ_{real_tank_in}を推定し、推定したガスタンクの入口の実流量Ｑ_{real_tank_in}と入口表示流量Ｑ_{display_tank_in}とに基づいて、ガスタンクの入口における化学種Ａの濃度Ｘ_{A_tank_in}と化学種Ｂの濃度Ｘ_{B_tank_in}とを推定することができる。 (2) In the estimating device of the above embodiment, the estimating unit estimates the actual flow rate Q _{real_tank_in} [slm] at the inlet of the gas tank using equation (1) and equation (2), and uses equation (3) and The concentration X _{A_tank_in} [mol%] of the chemical species A and the concentration X _{B_tank_in} [mol%] of the chemical species B at the inlet of the gas tank may be estimated using equation (4).

Δn _tank : Change in the number of moles of gas in the gas tank [mol]
V _tank : Internal volume of gas tank [L]
R: Gas constant [J/K-mol]
t: Current time [s]
Δt: Control period of estimation device [s]
C _{real_tank_in} : Control constant of inlet flow rate detection unit at current time [-]
C _{calib_tank_in} : Control constant of inlet flow rate detection section during calibration [-]
C _{A_tank_in} : Control constant for chemical species A in the inlet flow rate detection section [-]
C _{B_tank_in} : Control constant for chemical species B in the inlet flow rate detection section [-]
According to this configuration, the estimation unit estimates the actual flow rate Q _{real_tank_in} at the inlet of the gas tank based on the time change of the measured tank pressure value P _tank , and combines the estimated actual flow rate Q _{real_tank_in} at the inlet of the gas tank and the displayed inlet flow rate Q. _{display_tank_in} , the concentration X _{A_tank_in} of chemical species A and the concentration X _{B_tank_in} of chemical species B at the inlet of the gas tank can be estimated.

この構成によれば、混合ガスは、化学種Ａのガスと化学種Ｂのガスとの２種類のガスから構成されていることから、式（４）に加えて、化学種Ａのガスのモル濃度と化学種Ｂのガスのモル濃度とを足すと１００となる式（５）を用いて、ガスタンクの入口における化学種Ａの濃度Ｘ_{A_tank_in}と化学種Ｂの濃度Ｘ_{B_tank_in}とを推定することができる。 (3) In the estimating device of the above embodiment, the estimating unit calculates the concentration X _{A_tank_in} [mol%] of the chemical species A at the inlet of the gas tank and the concentration X _{B_tank_in} [mol%] of the chemical species B at the inlet of the gas tank, using equation (5). mol%] may be estimated.

According to this configuration, since the mixed gas is composed of two types of gas, the gas of chemical species A and the gas of chemical species B, in addition to equation (4), the molar amount of the gas of chemical species A is The concentration of chemical species A at the inlet of the gas tank, X _{A_tank_in} , and the concentration of chemical species B, X _{B_tank_in} , can be estimated using equation (5) in which the sum of the concentration and the molar concentration of chemical species B gas is 100. can.

Ｃ_{A_tank_out}：出口流量検出部の化学種Ａについての制御定数［－］
Ｃ_{B_tank_out}：出口流量検出部の化学種Ｂについての制御定数［－］
Ｃ_{calib_tank_out}：キャリブレーション時の出口流量検出部の制御定数［－］
この構成によれば、現在時刻での出口流量検出部の制御定数Ｃ_{real_tank_out}と、キャリブレーション時の出口流量検出部の制御定数Ｃ_{calib_tank_out}との比とに基づいて、ガスタンクの出口の実流量Ｑ_{real_tank_out}を推定することができる。これにより、式（２）を用いて、ガスタンクの入口の実流量Ｑ_{real_tank_in}を容易に推定することができる。 (4) In the estimating device of the above embodiment, the estimating section estimates the control constant C real_tank_out [-] of the outlet flow rate detection section using Equation (6), and estimates the control constant C _{real_tank_out} [-] of the outlet flow rate detection section using Equation (7). The actual flow rate Q _{real_tank_out} [slm] at the outlet of may be estimated.

C _{A_tank_out} : Control constant for chemical species A of the outlet flow rate detection section [-]
C _{B_tank_out} : Control constant for chemical species B of the outlet flow rate detection section [-]
C _{calib_tank_out} : Control constant of outlet flow rate detection section during calibration [-]
According to this configuration, the actual flow rate Q _{real_tank_out at the outlet of the gas tank is calculated based on the ratio between the control constant C real_tank_out} of the outlet flow rate detection unit at the current time and the control _constant C _{calib_tank_out} of the outlet flow rate detection unit at the time of calibration. can be estimated. Thereby, the actual flow rate Q _{real_tank_in} at the inlet of the gas tank can be easily estimated using equation (2).

この構成によれば、現在時刻より、推定装置の制御時間分だけ前の時刻でのガスタンクの入口の化学種Ａの濃度Ｘ_{A_tank}（ｔ－Δｔ）と化学種Ｂの濃度Ｘ_{B_tank}（ｔ－Δｔ）とを用いて、ガスタンク内の化学種Ａの濃度Ｘ_{A_tank}（ｔ）と化学種Ｂの濃度Ｘ_{B_tank}（ｔ）とを推定することができる。 (5) In the estimating device of the above form, the estimating unit estimates the number of moles of gas n _tank [-] in the gas tank using equation (8), and may be used to estimate the concentration X _{A_tank} [mol%] of the chemical species A and the concentration X _{B_tank} [mol%] of the chemical species B in the gas tank.

According to this configuration, the concentration of chemical species A X _{A_tank} (t-Δt) and the concentration of chemical species B X _{B_tank} (t-Δt) at the inlet of the gas tank at a time before the current time by the control time of the estimation device ), the concentration of chemical species A in the gas tank X _{A_tank} (t) and the concentration of chemical species B in the gas tank X _{B_tank} (t) can be estimated.

(6) In the estimating device of the above embodiment, a regulating gas supply section that is provided downstream of the outlet of the gas tank and supplies a gas containing one of the chemical species A and the chemical species B; The adjusted gas supply is performed according to at least one of the concentration X _{A_tank} of the chemical species A, the concentration X _{B_tank} of the chemical species B, the actual flow rate Q _{real_tank_in} at the inlet of the gas tank, and the actual flow rate Q _{real_tank_out} at the outlet of the gas tank. The control unit may also include a control unit that changes the flow rate of gas supplied by the unit. According to this configuration, the control unit changes the flow rate of the gas supplied by the adjustment gas supply unit using the estimated concentration X _{A_tank} of chemical species A and the estimated concentration X _{B_tank} of chemical species B in the gas tank. This makes it possible to estimate the concentration of the gas to be measured in a relatively short period of time, so that even if the concentration of the gas changes rapidly, it can be quickly brought to a desired concentration.

Ｑ_A：化学種Ａのガスの流量［ｓｌｍ］
Ｃ：制御定数（-）
ξ_target：化学種Ａ／化学種Ｂの目標値（-）
この構成によれば、制御部は、ガスタンクの出口の実流量Ｑ_{real_tank_out}と、化学種Ａ／化学種Ｂの目標値ξ_targetを用いて、調整ガス供給部が供給する化学種Ａのガスの流量を変更することができる。したがって、比較的容易に化学種Ａのガスの濃度を所望の濃度とすることができる。 (7) In the estimation device of the above embodiment, the adjustment gas supply section supplies a gas containing the chemical species A, and the control section controls the flow rate of the gas of the chemical species A supplied by the adjustment gas supply section. , the flow rate may be changed to one calculated using equation (11).

Q _A : Flow rate of gas of chemical species A [slm]
C: Control constant (-)
ξ _target : Target value of chemical species A/chemical species B (-)
According to this configuration, the control unit uses the actual flow rate Q _{real_tank_out} at the outlet of the gas tank and the target value ξ _target of chemical species A/chemical species B to determine the flow rate of the gas of chemical type A supplied by the adjustment gas supply unit. can be changed. Therefore, the concentration of the chemical species A gas can be set to a desired concentration relatively easily.

Ｑ_B：化学種Ｂのガスの流量［ｓｌｍ］
この構成によれば、制御部は、ガスタンクの出口の実流量Ｑ_{real_tank_out}と、化学種Ａ／化学種Ｂの目標値ξ_targetを用いて、調整ガス供給部が供給する化学種Ｂのガスの流量を変更することができる。したがって、比較的容易に化学種Ｂのガスの濃度を所望の濃度とすることができる。 (8) In the estimation device of the above embodiment, the adjustment gas supply section supplies a gas containing the chemical species B, and the control section controls the flow rate of the gas of the chemical species B supplied by the adjustment gas supply section. , the flow rate may be changed to the flow rate calculated using equation (12).

Q _B : Flow rate of gas of chemical species B [slm]
According to this configuration, the control unit uses the actual flow rate Q _{real_tank_out} at the outlet of the gas tank and the target value ξ _target of chemical species A/chemical species B to determine the flow rate of the gas of chemical species B supplied by the adjustment gas supply unit. can be changed. Therefore, the concentration of the chemical species B gas can be set to a desired concentration relatively easily.

Note that the present invention can be realized in various aspects, such as a mixed gas supply system including an estimation device, a method for controlling these devices and systems, and a method for estimating gas concentration in these devices and systems. It can be realized in the form of a computer program, a server device for distributing the computer program, a non-temporary storage medium storing the computer program, and the like.

FIG. 1 is a schematic diagram showing a schematic configuration of an estimation device according to a first embodiment. 3 is a first flowchart of a gas composition control method. It is a 2nd flowchart of a gas composition control method. It is a figure explaining the result of the evaluation test of the gas composition estimation method of 1st Embodiment. FIG. 2 is a schematic diagram showing a schematic configuration of an estimation device of a comparative example. FIG. 3 is a diagram illustrating characteristics of a gas composition estimation method of a comparative example.

<First embodiment>
FIG. 1 is a schematic diagram showing a schematic configuration of an estimation device according to a first embodiment. The estimation device 1 of this embodiment is included in a methane generation system 5 that generates methane (CH ₄ ) from a mixed gas of carbon dioxide (CO ₂ ) and hydrogen (H ₂ ). The methane generation system 5 includes a mixed gas supply section 6 , a gas tank 7 , a methanation reactor 8 , and an estimation device 1 . The mixed gas supply unit 6 supplies a mixed gas consisting of CO ₂ and H ₂ to the methanation reactor 8 via the gas tank 7 and the estimation device 1 . The estimation device 1 determines that the composition of the mixed gas (combination of CO ₂ concentration and H ₂ concentration) supplied to the methanation reactor 8 is such that both CO ₂ and H ₂ react stably with no excess or deficiency. The composition is controlled to be the same. Thereby, the methanation reactor 8 can produce stable and high quality CH ₄ . That is, the estimation device 1 has a function of alleviating and stabilizing fluctuations in gas concentration so that the composition of the mixed gas does not change over time.

The estimation device 1 includes a first flow path 11, a second flow path 12, an inlet flow rate detection section 21, an outlet flow rate detection section 22, a pressure gauge 23, a thermometer 24, and an adjustment gas supply section 31. , a supply channel 32 , and a control section 40 . The estimation device 1 adjusts the composition of the mixed gas flowing through the second flow path 12 using the adjusted gas supplied by the adjusted gas supply unit 31 based on the estimated CO ₂ concentration and H ₂ concentration of the mixed gas. do.

The first channel 11 is a channel that connects the mixed gas supply section 6 and the gas tank 7, and the mixed gas supplied by the mixed gas supply section 6 flows therethrough. The mixed gas flowing through the first channel 11 is temporarily stored in the gas tank 7, thereby being rectified and homogenized. The second flow path 12 connects the gas tank 7 and the methanation reactor 8 and supplies the mixed gas stored in the gas tank 7 to the methanation reactor 8.

The inlet flow rate detection section 21 is a thermal mass flow meter (T-MFM) provided in the first flow path 11. The inlet flow rate detection unit 21 detects a temperature change due to heat transfer with the gas flowing through the first flow path 11 and calculates the flow rate of the gas flowing through the first flow path 11 . Here, the flow rate calculated by the inlet flow rate detection unit 21 is referred to as the "inlet display flow rate." The inlet flow rate detection unit 21 is electrically connected to a control unit 40 described later, and outputs the calculated “inlet display flow rate” to the control unit 40.

The outlet flow rate detection unit 22 is a thermal mass flowmeter provided in the second flow path 12. The outlet flow rate detection unit 22 detects a temperature change due to heat transfer with the gas flowing through the second flow path 12, and calculates the flow rate of the gas flowing through the second flow path 12. Here, the flow rate calculated by the outlet flow rate detection unit 22 is referred to as the "exit display flow rate." The outlet flow rate detection unit 22 is electrically connected to the control unit 40 and outputs the calculated “inlet display flow rate” to the control unit 40.

The pressure gauge 23 is provided in the gas tank 7 and detects the pressure inside the gas tank 7. Here, the pressure detected by the pressure gauge 23 is referred to as a "tank pressure measurement value." The pressure gauge 23 is electrically connected to the control unit 40 and outputs the detected “tank pressure measurement value” to the control unit 40.

The thermometer 24 is provided in the gas tank 7 and detects the temperature inside the gas tank 7. Here, the temperature detected by the thermometer 24 is referred to as a "tank temperature measurement value." The thermometer 24 is electrically connected to the control unit 40 and outputs the detected “tank temperature measurement value” to the control unit 40.

The adjustment gas supply section 31 is connected to the second flow path 12 via a supply flow path 32. The adjustment gas supply section 31 is electrically connected to the control section 40 . In the present embodiment, the adjustment gas supply unit 31 stores CO ₂ gas and H ₂ gas separately, and supplies CO ₂ gas or H 2 gas to the second flow path 12 according to a command from the control unit 40. Supply either of the _two gases. Note that the adjustment gas supply section 31 may store either CO ₂ gas or H ₂ gas.

The control unit 40 includes a storage medium such as a hard disk, and a CPU that expands a computer program stored in a ROM into a RAM and executes it. The control unit 40 is electrically connected to the inlet flow rate detection unit 21, the outlet flow rate detection unit 22, the pressure gauge 23, the thermometer 24, and the adjustment gas supply unit 31. The control unit 40 uses the displayed flow rate of the inlet flow rate detection unit 21, the displayed flow rate of the outlet flow rate detection unit 22, the detected value of the pressure gauge 23, and the detected value of the thermometer 24, to determine the flow rate at the inlet of the gas tank 7. Estimate at least one of the following: CO ₂ concentration and H ₂ concentration, CO ₂ concentration and H ₂ concentration in the gas tank 7, the actual flow rate of the mixed gas at the inlet of the gas tank 7, and the actual flow rate of the mixed gas at the outlet of the gas tank. do. The control unit 40 controls the adjustment gas according to at least one of the CO ₂ concentration and H ₂ concentration in the gas tank 7 , the actual flow rate of the mixed gas at the inlet of the gas tank 7 , and the actual flow rate of the mixed gas at the outlet of the gas tank 7 . The flow rate of gas supplied by the supply unit 31 is changed.

Next, details of the gas composition control method of this embodiment will be explained. The gas composition control method of the present embodiment controls the composition of the mixed gas of CO ₂ and H ₂ supplied by the mixed gas supply section 6 when the methane generation system 5 starts producing CH ₄ . As a result, the mixed gas having a predetermined composition is supplied to the methanation reactor 8, so that the methanation reactor 8 can generate CH ₄ of stable quality and constant concentration. The gas composition control method of the present embodiment uses a gas composition estimation method for estimating the composition of the mixed gas in the gas tank 7 and the estimated composition of the mixed gas in the gas tank 7 to supply the gas to the methanation reactor 8. and a gas composition adjustment method for adjusting the composition of a mixed gas.

FIG. 2 is a first flowchart of the gas composition control method, and is a flowchart of the gas composition estimation method. The gas composition estimation method is started when the methane production system 5 starts producing CH ₄ . In the gas composition estimation method, first, the composition and pressure in the immediately preceding gas tank 7 are acquired (step S11). In step S11, the control unit 40 obtains the composition and pressure in the gas tank 7 immediately before the start of the gas composition control method as initial values. In this embodiment, the control unit 40 acquires the concentration of CO ₂ and H ₂ in the gas tank 7, which are measured before the gas composition control method starts, and the tank pressure measurement value.

The composition and pressure inside the gas tank 7 acquired by the control unit 40 in step S11 can be expressed as follows, where the current time is t [s] and the control period of the estimation device 1 is Δt [s]. Here, for convenience, the time before starting the gas composition control method is defined as the time obtained by subtracting the control period of the estimating device 1 from the current time. In step S11, the control unit 40 also obtains the internal volume V _tank [L] of the gas tank 7 as a setting value regarding the estimation device 1.
_CO2 molar concentration in gas tank 7: X _{CO2_tank} (t-Δt) [mol%]
_H2 molar concentration in gas tank 7: X _{H2_tank} (t-Δt) [mol%]
Tank pressure detection value: P _tank [kPa]

式（６）において、Ｃ_{CO2_tank_out}［－］は、出口流量検出部２２のＣＯ₂についての変換係数であり、Ｃ_{H2_tank_out}［－］は、出口流量検出部２２のＨ₂についての変換係数である。本実施形態では、出口流量検出部２２のＣＯ₂およびＨ₂についての変換係数は、例えば、熱式質量流量計の製造者から提供される。 Next, the actual flow rate of gas at the gas tank outlet is estimated from the composition in the gas tank 7 before the start (step S12). In step S12, the control unit 40 first selects the CO ₂ molar concentration X _{CO2_tank} (t-Δt) and the H ₂ molar concentration X _{H2_tank} (t-Δt) in the gas tank 7 from among the initial values acquired in step S11. Based on the equation (6), the conversion coefficient C _{real_tank_out} [-] of the outlet flow rate detection unit 22 at the current time t is estimated.

In equation (6), C _{CO2_tank_out} [-] is a conversion coefficient for CO ₂ of the outlet flow rate detection section 22, and C _{H2_tank_out} [-] is a conversion coefficient for H ₂ of the outlet flow rate detection section 22. In this embodiment, the conversion factors for CO ₂ and H ₂ of the outlet flow rate detector 22 are provided, for example, by the manufacturer of the thermal mass flow meter.

Here, the conversion coefficient of the thermal mass flowmeter will be explained. A thermal mass flowmeter generally includes a main flow path through which most of the target gas flows, and a bypass flow path through which the remainder of the target gas flows. The thermal mass flow meter calculates the flow rate based on the extent to which the target gas flowing through the bypass channel carries away heat from the heating element built into the thermal mass flow meter. For this reason, thermal mass flowmeters must be calibrated for each type of target gas to calculate the flow rate, depending on the relationship between the division ratio between the main flow path and the bypass flow path and the constant pressure specific heat of the target gas. Conversion coefficients are set for In other words, the thermal mass flowmeter has a different conversion coefficient depending on the type of target gas. Therefore, in this embodiment, the conversion coefficient of the thermal mass flowmeter is calculated according to the composition of the gas using equation (6) so as to correspond to a mixed gas whose composition changes. The conversion coefficient C _{real_tank_out} of the outlet flow rate detection unit 22 at the current time t calculated by equation (6) is the conversion coefficient C real_tank_out for measuring the flow rate of gas flowing through the second flow path 12 at the time t. -Δt). The conversion coefficient of the thermal mass flowmeter of this embodiment corresponds to the "control constant" described in the claims.

式（７）において、Ｑ_{display_tank_out}［ｓｌｍ］は、出口流量検出部２２の表示流量であり、Ｃ_{calib_tank_out}［－］は、キャリブレーション時の出口流量検出部２２の変換係数［－］である。 In step S12, further, based on the conversion coefficient C _{real_tank_out} of the outlet flow rate detection unit 22 at the current time t estimated by the equation (6), the actual flow rate Q of the mixed gas at the gas tank outlet is calculated using the equation (7). Estimate _{real_tank_out} [slm].

In equation (7), Q _{display_tank_out} [slm] is the display flow rate of the outlet flow rate detector 22, and C _{calib_tank_out} [-] is the conversion coefficient [-] of the outlet flow rate detector 22 during calibration.

式（１）において、Ｔ_tank［Ｋ］は、温度計２４のタンク温計測値である。なお、Ｒ［Ｊ／Ｋ－ｍｏｌ］は、気体定数である。 Next, the amount of change in the number of moles of gas in the gas tank 7 is estimated from the pressure change in the gas tank 7 (step S13). In step S13, the control unit 40 calculates the amount of change in the number of moles of gas Δn _tank [mol] in the gas tank 7 based on the tank pressure measurement value P _tank [kPa] of the pressure gauge 23 using equation (1). presume.

In equation (1), T _tank [K] is the tank temperature measured by the thermometer 24. Note that R[J/K-mol] is a gas constant.

Next, the actual flow rate of gas at the gas tank inlet is estimated from the actual flow rate of gas at the gas tank outlet and the amount of change in the number of moles in the gas tank 7 (step S14). In step S14, the control unit 40 calculates equation (2) based on the actual gas flow rate Q _{real_tank_out} at the gas tank outlet estimated in step S12 and the amount of change in the number of moles in the gas tank Δn _tank estimated in step S13. is used to estimate the actual gas flow rate Q _{real_tank_in} [slm] at the gas tank inlet.

式（３）において、Ｃ_{calib_tank_in}［－］は、キャリブレーション時の入口流量検出部２１の変換係数［－］である。 Next, the conversion coefficient of the inlet flow rate detector 21 at the current time is estimated based on the actual gas flow rate at the gas tank inlet and the inlet display flow rate of the inlet flow rate detector 21 (step S15). In step S15, the control unit 40 uses equation (3) from the actual gas flow rate Q _{real_tank_in} at the gas tank inlet estimated in step S14 and the inlet display flow rate Q _{display_tank_in} [slm] of the inlet flow rate detection unit 21. The conversion coefficient C _{real_tank_in} [-] of the inlet flow rate detection unit 21 at the current time t is determined.

In equation (3), C _{calib_tank_in} [-] is the conversion coefficient [-] of the inlet flow rate detection section 21 during calibration.

式（４）において、Ｃ_{CO2_tank_in}［－］は、入口流量検出部２１のＣＯ₂についての変換係数であり、Ｃ_{H2_tank_in}［－］は、入口流量検出部２１のＨ₂についての変換係数である。本実施形態では、入口流量検出部２１のＣＯ₂およびＨ₂についての変換係数は、例えば、熱式質量流量計の製造者から提供される。 Next, the composition of the gas at the gas tank inlet is estimated based on the conversion coefficient of the inlet flow rate detector 21 at the current time (step S16). In step S16, the control unit 40 uses equations (4) and (5) based on the conversion coefficient C _{real_tank_in} of the inlet flow rate detection unit 21 at the current time t estimated in step S15 to Estimate the CO ₂ molar concentration X _{CO2_tank_in} (t-Δt) [mol%] and the H ₂ molar concentration X _{H2_tank_in} (t-Δt) [mol%]. Note that equation (5) is an equation that indicates that the mixed gas is composed of only CO ₂ gas and H ₂ gas.

In equation (4), C _{CO2_tank_in} [-] is a conversion coefficient for CO ₂ of the inlet flow rate detection section 21, and C _{H2_tank_in} [-] is a conversion coefficient for H ₂ of the inlet flow rate detection section 21. In this embodiment, the conversion factors for CO ₂ and H ₂ of the inlet flow rate detector 21 are provided, for example, by the manufacturer of the thermal mass flow meter.

Next, the composition in the gas tank 7 is estimated based on the detected pressure value in the gas tank 7, the amount of change in the number of moles in the gas tank 7, and the composition of the gas at the gas tank inlet (step S17). In step S17, the control unit 40 first estimates the number of moles n _tank [mol] in the gas tank 7 using equation (8) based on the measured tank pressure value P _tank [kPa].

In step S17, the amount of change in the number of moles in the gas tank 7 Δn _tank [mol], the composition of the gas at the gas tank inlet (CO ₂ molar concentration at the gas tank inlet X _{CO2_tank_in} (t-Δt), H ₂ molar _{concentration} Based on Δt)), using equations (9) and (10), the CO ₂ molar concentration in the gas tank 7 X _{CO2_tank} (t) [mol%] and the H ₂ molar concentration X _{H2_tank} (t) [ mol%].

When the gas composition estimation method shown in FIG. 2 proceeds to step S17, the control period Δt of the estimation device 1 has elapsed (step S18), and then the actual flow rate Q _{real_tank_out} of the gas at the gas tank outlet is estimated again (step S12). In this case, the "previous composition in the gas tank 7" required to estimate the actual gas flow rate Q _{real_tank_out} at the gas tank outlet is the CO ₂ molar concentration X in the gas tank 7 estimated in step S17 before proceeding to step S12. _{co2_tank} and _H2 molar concentration X _{H2_tank} are used.

FIG. 3 is a second flowchart of the gas composition control method, and is a flowchart of the gas composition adjustment method. In the gas composition adjustment method, when the composition of the gas in the gas tank 7 is estimated in step S17 described above, the adjustment gas supply section 31 supplies the adjustment gas to the second flow path 12 according to the estimation result.

式（１１）において、Ｑ_CO2は、ＣＯ₂ガスの流量［ｓｌｍ］であり、Ｃは、変換係数（-）であり、ξ_targetは、Ｈ₂／ＣＯ₂の目標値（-）である。

式（１２）において、Ｑ_H2は、Ｈ₂ガスの流量［ｓｌｍ］である。 In the gas composition adjustment method, first, the flow rate of chemical species to be supplied to the second channel 12 is calculated from the composition of the gas in the gas tank 7 (step S19). In step S19, the control unit 40 calculates the CO ₂ molar concentration X _{co2_tank} and H ₂ molar concentration X _{H2_tank} in the gas tank 7 estimated in step S17, and the actual gas flow rate Q _{real_tank_out} at the gas tank outlet estimated in step S12. Based on this, either the flow rate of CO ₂ gas is calculated using equation (11) or the flow rate of H ₂ gas is calculated using equation (12).

In equation (11), Q _CO2 is the flow rate [slm] of CO ₂ gas, C is the conversion coefficient (-), and ξ _target is the target value (-) of H ₂ /CO ₂ .

In equation (12), Q _H2 is the flow rate [slm] of H ₂ gas.

Next, a command to supply a predetermined chemical type of gas to the second flow path 12 is output to the adjustment gas supply section 31 (step S20). In step S20, the control unit 40 outputs a command to supply the second flow path 12 to the adjustment gas supply unit 31 based on the flow rate calculated in step S19. Specifically, either the CO ₂ gas flow rate Q _CO2 or the H ₂ gas flow rate Q _H2 calculated in step S20 is supplied to the second flow path 12 . Thereby, the composition of the gas supplied to the methanation reactor 8 can be set to the target value of H ₂ /CO ₂ .

Next, the effects of the gas composition estimation method using the estimation device 1 of this embodiment will be explained. Here, the temporal change in the gas composition estimated by the gas composition estimation method of the present embodiment and the actual temporal change in the gas composition were experimentally measured and compared.

FIG. 4 is a diagram illustrating the results of an evaluation test of the gas composition estimation method of the first embodiment. In FIG. 4, the horizontal axis shows time, and the vertical axis shows H ₂ /CO ₂ (=X _{H2_tank} /X _{co2_tank} ) in the gas tank 7. In FIG. 4, the measured value (true value) of H ₂ /CO ₂ in the gas tank 7 is shown by a solid line, and the estimated value by the gas composition estimation method of this embodiment is shown by a dotted line. As shown in FIG. 4, it has become clear that the estimated value rises and falls at the same timing as the measured value rises and falls. Therefore, it has become clear that the gas composition estimation method of this embodiment can predict H ₂ /CO ₂ in the gas tank 7 well.

In manufacturing processes that produce gas products through chemical reactions, it is necessary to precisely control the composition of the raw material gas for the chemical reaction in order to maintain a high quality of the gas produced by the chemical reaction. For example, CH ₄ gas produced in a methane production process is strongly influenced by the H ₂ /CO ₂ value of the raw gas. Specifically, when the H ₂ /CO ₂ ratio of the raw material gas is 4.0 and the CO ₂ conversion rate is 99%, the CH ₄ concentration in the generated gas is 95%. However, when H ₂ /CO ₂ is 4.1, the CH ₄ concentration in the produced gas decreases to 87% even if the CO ₂ conversion rate is 99%. As described above, in order to ensure the quality of the produced gas, it is necessary to precisely control and stabilize the composition of the raw material gas.

Further, when the target chemical reaction requires gases of two or more chemical species as raw material gases, the gases of each chemical species are not necessarily supplied separately and independently. In some cases, a mixed gas in which chemical gases have already been mixed may be supplied to the chemical reaction device as a raw material. In this case, if the composition of the mixed gas is suitable for the intended chemical reaction and is stable over time, the mixed gas may be directly supplied to the reactor. However, for example, when trying to effectively utilize gases emitted from other processes, such conditions are difficult to meet, and the composition of the mixed gas changes over time, so it is necessary to adjust it in some way. be.

FIG. 5 is a schematic diagram showing a schematic configuration of an estimation device of a comparative example. The chemical reaction system 2 shown in FIG. 5 includes an estimation device 90 in addition to a mixed gas supply section 6, a gas tank 7, and a methanation reactor 8. The estimation device 90 of the comparative example includes a first mass flow controller (first MFC) 91, a gas analyzer 92, a regulating gas supply section 93, and a second mass flow controller (second MFC) 94. In the chemical reaction system 2, the composition of the mixed gas flowing through the second flow path 12 is measured by the gas analyzer 92, and the first mass flow is adjusted according to the difference between the measurement result and the target value of H ₂ /CO ₂ of the mixed gas. The controller 91 and the second mass flow controller 94 that adjusts the flow rate of the mixed gas supplied by the adjustment gas supply section 93 are controlled. Thereby, the composition of the mixed gas supplied to the methanation reactor 8 is set to the target value of H ₂ /CO ₂ . However, measurement of gas concentration by the gas analyzer 92 tends to be delayed.

FIG. 6 is a diagram illustrating the characteristics of the gas composition estimation method of the comparative example. Generally, a gas analyzer takes several tens of seconds to identify the analysis result (“measurement delay” shown in Figure 6(a)). Therefore, changes in H ₂ /CO ₂ in the mixed gas , if the period _from time t1 to time t2 in FIG. ₂ fluctuations remain (symbol A1 in FIG. 6(b)). If fluctuations in H ₂ /CO ₂ remain, it is difficult for the composition of the mixed gas to reach a value suitable for the intended chemical reaction, and it is also not stable.

Furthermore, gas analyzers that can continuously measure gas concentration are generally expensive. Furthermore, since the gas analyzer needs to extract a portion of the gas supplied to the reactor, exhausting the extracted raw material gas leads to loss of the raw material gas. Furthermore, since the concentration inside the gas analyzer is generally measured at atmospheric pressure, in order to recycle the extracted raw material gas, it is necessary to raise the pressure again using a blower, compressor, or the like. Therefore, power is required and energy loss occurs.

According to the estimation device 1 of the present embodiment described above, the control unit 40 controls the inlet display flow rate Q _{display_tank_in} of the inlet flow rate detection unit 21, the outlet display flow rate Q _{display_tank_out} of the outlet flow rate detection unit 22, and the pressure gauge 23. Using the tank pressure measurement value P _tank and the tank temperature measurement value T _tank of the thermometer 24, the CO ₂ molar concentration X _{CO2_tank} , the H ₂ molar concentration X _{B_tank} , etc. in the gas tank 7 are estimated. As a result, the concentration of the gas to be measured can be estimated in a relatively short time compared to a gas analyzer that takes several tens of seconds to determine the concentration of the gas to be measured.

Further, according to the estimation device 1 of the present embodiment, the flow rate of the mixed gas is detected by the inlet flow rate detection unit 21 and the outlet flow rate detection unit 22, which are thermal mass flowmeters, and the pressure inside the gas tank 7 is detected by the pressure gauge 23. To detect. Unlike gas analyzers, thermal mass flow meters and pressure gauges have sufficiently small measurement delays on the order of sub-seconds. Therefore, the measurement delay of the CO ₂ molar concentration X _{CO2_tank} , H ₂ molar concentration X _{B_tank,} etc. in the gas tank 7 is small, and the H ₂ /CO ₂ control by the gas composition control method is also less likely to have a delay. Therefore, the composition of the mixed gas supplied to the methanation reactor 8 can be stabilized.

Furthermore, according to the estimation device 1 of this embodiment, the thermal mass flowmeter used as the inlet flow rate detection section 21 and the outlet flow rate detection section 22 is cheaper than a gas analyzer. Thereby, a gas concentration estimating device can be manufactured at a lower cost.

Furthermore, according to the estimation device 1 of the present embodiment, the thermal mass flowmeter used as the inlet flow rate detection unit 21 and the outlet flow rate detection unit 22 detects the flow rate using a part of the mixed gas; The used mixed gas is supplied to the methanation reactor 8. As a result, unlike gas analyzers that discard part of the mixed gas, there is no loss of the raw material mixed gas due to estimation of gas concentration. Furthermore, thermal mass flowmeters use the flow of the mixed gas as is to detect the flow rate, so compared to gas analyzers that generally detect gas concentrations at normal pressure, There is no need to boost the pressure. Therefore, CH ₄ gas can be produced more economically.

Further, according to the estimation device 1 of the present embodiment, the control unit 40 uses equations (1) and (2) to determine the actual value of the inlet of the gas tank 7 based on the time change of the measured tank pressure value P _tank . Estimate the flow rate Q _{real_tank_in} . The control unit 40 uses equations (3) and (4) to determine the CO ₂ molar concentration X at the inlet of the gas tank 7 based on the estimated actual flow rate Q _{real_tank_in} at the inlet of the gas tank 7 and the inlet display flow rate Q _{display_tank_in} Estimate _{CO2_tank_in} and H ₂ molar concentration X _{H2_tank_in} . Thereby, by using the inlet flow rate detection section 21 and the pressure gauge 23, the composition of the mixed gas at the inlet of the gas tank 7 can be easily estimated.

Further, according to the estimation device 1 of this embodiment, since the mixed gas is composed of two types of gases, CO ₂ gas and H ₂ gas, in addition to equation (4), CO ₂ The concentration of chemical species A, X _{A_tank_in} , and the concentration of chemical species B, X _{B_tank_in} , at the inlet of the gas tank can be estimated using equation (5) in which the molar concentration and the H ₂ molar concentration add up to 100. In this way, in the case of a mixed gas consisting of two types of chemical gases, the composition of the mixed gas can be easily estimated.

According to the estimation device 1 of the present embodiment, the control constant C _{real_tank_out} of the outlet flow rate detector 22 at the current time and the outlet flow rate detector at the time of calibration are calculated using equations (6) and (7). The actual flow rate Q _{real_tank_out} at the outlet of the gas tank 7 can be estimated based on the ratio with the conversion coefficient C _{calib_tank_out} of 22. Thereby, the actual flow rate Q _{real_tank_in} at the inlet of the gas tank 7 can be easily estimated using equation (2).

Further, according to the estimation device 1 of the present embodiment, the control unit 40 estimates the number of moles of gas in the gas tank n _tank using equation (8). Furthermore, the control unit 40 uses equations (9) and (10) to determine the CO ₂ molar concentration X _{CO2_tank} (t−Δt) and the H ₂ molar concentration X _{H2_tank} (t−Δt) at the inlet of the gas tank 7. Based on this, the CO ₂ molar concentration X _{CO2_tank} (t) and the H ₂ molar concentration X _{H2_tank} (t) in the gas tank 7 can be estimated. Thereby, the composition of the mixed gas in the gas tank 7 at the current time can be estimated using the composition of the mixed gas at the inlet of the gas tank 7 immediately before.

Further, according to the estimation device 1 of the present embodiment, the control unit 40 adjusts the estimated CO 2 molar concentration in the gas tank 7 using the estimated CO ₂ molar concentration X _{CO2_tank} (t) and H ₂ molar concentration X _{H2_tank} (t). The flow rate of gas supplied by the gas supply unit 31 is changed. Thereby, the estimating device 1 can estimate the concentration of the gas to be measured in a relatively short period of time, so that even if the concentration of the gas changes rapidly, it can quickly reach the desired concentration.

Further, according to the estimation device 1 of the present embodiment, the control unit 40 uses the actual flow rate Q _{real_tank_out} at the outlet of the gas tank 7 and the target value ξ _target of H ₂ /CO ₂ to determine the amount of gas supplied by the adjustment gas supply unit 31. The flow rates of CO ₂ gas and H ₂ gas can be changed. Therefore, the H ₂ /CO ₂ of the mixed gas can be set to the target value of H ₂ /CO ₂ relatively easily.

<Modification of this embodiment>
The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit thereof. For example, the following modifications are also possible.

[Modification 1]
In the embodiment described above, the composition of the mixed gas is estimated using equations (1) to (10), and the composition of the mixed gas is controlled using equations (11) and (12). However, the method for estimating the gas composition of the mixed gas and the method for controlling the gas composition are not limited to this. For example, using equations (1) to (4), the actual flow rate Q _{real_tank_in} at the inlet of the gas tank, the CO ₂ molar concentration X _{CO2_tank_in} (t-Δt), and the H ₂ molar concentration X _{H2_tank_in} (t -Δt), and then the CO ₂ molar concentration X _{CO2_tank} (t) and the H ₂ molar concentration X _{H2_tank} (t) in the gas tank 7 may be estimated using equations (9) and (10).

[Modification 2]
In the embodiment described above, the concentration X of the mixed species A in the gas tank 7 is determined using the inlet display flow rate Q _{display_tank_in} , the outlet display flow rate Q _{display_tank_out} , the tank pressure measurement value P _tank , and the tank temperature measurement value T _tank . It is assumed that _{A_tank} and the concentration of chemical species B, X _{B_tank,} are estimated. The estimation device may be used only to estimate the concentration of chemical species A at the inlet of the gas tank, X _{A_tank_in} , the concentration of chemical species B, X _{B_tank_in,} the actual flow rate at the inlet of the gas tank, Q _{real_tank_in} , and the actual flow rate, Q _{real_tank_out} , at the outlet of the gas tank. .

[Modification 3]
In the embodiment described above, the tank temperature measurement value T _tank is detected by the thermometer 24 provided in the gas tank 7 . Since the temperature of the gas tank 7 matches the environmental temperature of the estimation device 1, the environmental temperature may be used as the tank temperature measurement value T _tank .

[Modification 4]
In the above-described embodiment, the conversion coefficients for CO ₂ and H ₂ (C _{CO2_tank_out} , C _{H2_tank_out} , C _{CO2_tank_in} , C _{H2_tank_in} ) for each of the inlet flow rate detection unit 21 and the outlet flow rate detection unit 22 are determined by the thermal mass flowmeter. provided by the manufacturer. However, the conversion coefficients are not limited to this. In estimating the gas composition in the estimating device 1, adjustments may be made to improve estimation accuracy. Usually, the conversion coefficients provided by the manufacturer are assumed to be used in a steady state, so the estimation accuracy of the estimation device 1 can be improved by adjusting them at the site where the thermal mass flowmeter is used. can. Specifically, the conversion coefficients C _{calib_tank_out} , C _{A_tank_out} , C _{B_tank_out} , C _{calib_tank_in} , C _{A_tank_in} , and C _{B_tank_in} of the inlet flow rate detection unit 21 and the outlet flow rate detection unit 22 are calculated based on the estimated values and the concentrations shown in FIG. It is possible to adjust the value by comparing it with the true value of .

[Modification 5]
In the above embodiment, a thermal mass flowmeter is used as the inlet flow rate detection section 21 and the outlet flow rate detection section 22, but a mass flow controller (T-MFC) which is a thermal mass flowmeter with a flow control function added may be used. May be used. T-MFC has an additional adjustment valve inside, and operates to keep the displayed flow rate constant by adjusting the opening degree of the adjustment valve (therefore, under conditions where the composition fluctuates, the actual flow rate cannot be kept constant). (I can't stand it). The displayed flow rate of T-MFC is detected using the same principle as T-MFM, so even when using T-MFC, from the displayed flow rate of T-MFC, the CO ₂ molar concentration in the gas tank 7 X _{CO2_tank} and H ₂ mol Concentration X _{B_tank} etc. can be estimated.

Although the present aspect has been described above based on the embodiments and modified examples, the embodiments of the above-described aspect are for facilitating understanding of the present aspect, and do not limit the present aspect. This aspect may be modified and improved without departing from the spirit and scope of the claims, and this aspect includes equivalents thereof. Furthermore, if the technical feature is not described as essential in this specification, it can be deleted as appropriate.

1...Estimation device 6...Mixed gas supply unit 7...Gas tank 21...Inlet flow rate detection unit 22...Outlet flow rate detection unit 23...Pressure gauge 24...Thermometer 31...Adjusted gas supply unit 40...Control unit Q _{display_tank_in} ...Inlet display flow rate Q _{display_tank_out} ...Displayed flow rate at the _outlet Q _{real_tank_in} ...Actual flow rate at the _inlet of the gas tank Q _{real_tank_out} ...Actual flow rate at the outlet _of the gas tank X _{CO2_tank_in} ... _Molar concentration of _CO2 at the inlet of the gas tank Concentration X _{H_tank} … _H2 molar concentration in the gas tank

Claims (8)

An estimation device for estimating the composition of a mixed gas containing two different types of chemical species A and chemical species B,
an inlet flow rate detection unit that detects an inlet display flow rate Q _{display_tank_in} , which is a display flow rate of gas at the inlet of the gas tank, of the gas supplied from the mixed gas supply source to the gas tank;
an outlet flow rate detection unit that detects an outlet display flow rate Q _{display_tank_out} that is a display flow rate of gas at the outlet of the gas tank;
a pressure detection unit that detects a tank pressure measurement value P _tank that is a measurement value of the pressure in the gas tank;
a temperature detection unit that detects a tank temperature measurement value T _tank that is a measurement value of the temperature inside the gas tank;
Using the inlet display flow rate Q _{display_tank_in} , the outlet display flow rate Q _{display_tank_out} , the tank pressure measurement value P _tank , and the tank temperature measurement value T _tank ,
The concentration of the chemical species A at the inlet of the gas tank X _{A_tank_in} and the concentration of the chemical species B X _{B_tank_in} ,
The concentration of the chemical species A in the gas tank X _{A_tank} and the concentration of the chemical species B X _{B_tank} ,
the actual flow rate Q _{real_tank_in} at the inlet of the gas tank, and
Actual flow rate Q _{real_tank_out} at the outlet of the gas tank,
an estimation unit that estimates at least one of the
Estimation device. The estimation device according to claim 1,
The estimation unit is
Using equations (1) and (2), estimate the actual flow rate Q _{real_tank_in} [slm] at the inlet of the gas tank,
Estimating the concentration of the chemical species A X _{A_tank_in} [mol%] and the concentration of the chemical species B X _{B_tank_in} [mol%] at the inlet of the gas tank using equations (3) and (4);
Estimation device.

Δn _tank : Change in the number of moles of gas in the gas tank [mol]
V _tank : Internal volume of gas tank [L]
R: Gas constant [J/K-mol]
t: Current time [s]
Δt: Control period of estimation device [s]
C _{real_tank_in} : Control constant of inlet flow rate detection unit at current time [-]
C _{calib_tank_in} : Control constant of inlet flow rate detection section during calibration [-]
C _{A_tank_in} : Control constant for chemical species A in the inlet flow rate detection section [-]
C _{B_tank_in} : Control constant for chemical species B in the inlet flow rate detection section [-] The estimation device according to claim 2,
The estimation unit estimates the concentration of the chemical species A X _{A_tank_in} [mol%] and the concentration of the chemical species B X _{B_tank_in} [mol%] at the inlet of the gas tank using equation (5).
Estimation device.

The estimation device according to claim 2 or 3,
The estimation unit is
Using equation (6), estimate the control constant C _{real_tank_out} [-] of the outlet flow rate detection section,
Estimate the actual flow rate Q _{real_tank_out} [slm] at the outlet of the gas tank using equation (7);
Estimation device.

C _{A_tank_out} : Control constant for chemical species A of the outlet flow rate detection section [-]
C _{B_tank_out} : Control constant for chemical species B of the outlet flow rate detection section [-]
C _{calib_tank_out} : Control constant of outlet flow rate detection section during calibration [-] The estimation device according to any one of claims 2 to 4,
The estimation unit is
Using equation (8), estimate the number of moles of gas n _tank [-] in the gas tank,
Estimating the concentration X _{A_tank} [mol%] of the chemical species A and the concentration X _{B_tank} [mol%] of the chemical species B in the gas tank using equations (9) and (10);
Estimation device.

The estimation device according to any one of claims 1 to 5 further comprises:
a regulating gas supply unit that is provided downstream of the outlet of the gas tank and supplies a gas containing one of the chemical species A and the chemical species B;
According to at least one of the concentration X _{A_tank} of the chemical species A in the gas tank, the concentration X _{B_tank} of the chemical species B, the actual flow rate Q _{real_tank_in} at the inlet of the gas tank, and the actual flow rate Q _{real_tank_out} at the outlet of the gas tank. , a control unit that changes the flow rate of the gas supplied by the adjustment gas supply unit,
Estimation device. The estimation device according to claim 6,
The adjustment gas supply unit supplies a gas containing the chemical species A,
The control unit changes the flow rate of the chemical species A gas supplied by the adjustment gas supply unit to a flow rate calculated using equation (11).
Estimation device.

Q _A : Flow rate of gas of chemical species A [slm]
C: Control constant (-)
ξ _target : Target value of chemical species A/chemical species B (-) The estimation device according to claim 6 or 7,
The adjustment gas supply unit supplies a gas containing the chemical species B,
The control unit changes the flow rate of the chemical species B gas supplied by the adjustment gas supply unit to a flow rate calculated using equation (12).
Estimation device.

Q _B : Flow rate of gas of chemical species B [slm]

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