Gas concentration estimation device, gas concentration estimation method, and program

Abstract

To estimate real-time gas concentrations, from gas concentrations measured with an infrared gas analyzer.SOLUTION: A gas concentration estimation device according to an embodiment of the present invention is a gas concentration estimation device for estimating a gas concentration for controlling a combustion furnace, comprising receiving means of receiving a delayed gas concentration measured value obtained by measuring a concentration of gas discharged from the combustion furnace to a flue using an infrared gas analyzer, and one or more physical quantity measured values obtained by measuring one or more specified physical quantities relating to the combustion furnace each measured by a sensor, and estimation means of calculating an estimated value of the real-time gas concentration measured value as a gas concentration for use in controlling the combustion furnace, from the delayed gas concentration measured value and the one or more physical quantity measured values, using a model for estimating a real-time gas concentration.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas concentration estimation device, a gas concentration estimation method, and a program. [Background technology]

[0002] Generally, in order to achieve both energy conservation and pollution prevention in combustion furnaces, it is important to control the gas concentrations (CO concentration and O2 concentration) inside the combustion furnace, and for this purpose, gas concentrations are measured using various methods.

[0003] For example, a method of measuring gas concentration using a laser gas analyzer is known (for example, Non-Patent Document 1). While a laser gas analyzer can measure gas concentration in real time, it has problems such as being expensive and data loss occurring when the laser receiving section is blocked.

[0004] Another known method is to measure gas concentration using, for example, an infrared gas analyzer. Although infrared gas analyzers are cheaper than laser gas analyzers, they measure the gas concentration of gas discharged into the flue, and therefore can only measure the gas concentration at a time later than the actual gas concentration inside the combustion furnace. Specifically, if the gas concentration inside the combustion furnace at time t is y(t), the infrared gas analyzer measures the gas concentration y(t-τ) at a certain time lag τ from the current time t. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Yoshitaka Yuki, Akihiro Murata, "Optimal Combustion Control Solution Using the TDLS200 Laser Gas Analyzer," Yokogawa Technical Report 53(1), 19-22, 2010 Summary of the Invention [Problem to be solved by the invention]

[0006] While infrared gas analyzers are inexpensive and easy to introduce, as mentioned above, there is a time delay in measuring gas concentrations, which means that controlling a combustion furnace based on gas concentrations measured by an infrared gas analyzer can result in a deterioration in performance in terms of combustion efficiency and energy conservation.

[0007] An embodiment of the present invention has been made in view of the above points, and has an object to estimate a gas concentration without time delay from a gas concentration measured by an infrared gas analyzer. [Means for solving the problem]

[0008] In order to achieve the above object, a gas concentration estimation device according to one embodiment is a gas concentration estimation device that estimates a gas concentration for controlling a combustion furnace, and includes: a receiving means that receives a time-delayed gas concentration measurement value obtained by measuring the concentration of gas discharged from the combustion furnace into a flue using an infrared gas analyzer; and one or more physical quantity measurement values ​​obtained by measuring one or more predetermined physical quantities related to the combustion furnace using sensors; and an estimation means that uses a model for estimating gas concentrations without a time delay to calculate an estimate of the time-delayed gas concentration measurement value as a gas concentration for controlling the combustion furnace from the time-delayed gas concentration measurement value and the one or more physical quantity measurement values. [Effects of the Invention]

[0009] The gas concentration can be estimated without time delay from the gas concentration measured by the infrared gas analyzer. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing an example of the overall configuration of a combustion control system according to an embodiment of the present invention; [Figure 2] 3A and 3B are diagrams schematically showing the relationship between the excess air ratio and heat loss and the relationship between the excess air ratio and thermal efficiency. [Figure 3] FIG. 1 is a diagram illustrating an example of a hardware configuration of a gas concentration estimation device according to an embodiment of the present invention. [Figure 4]FIG. 2 is a diagram illustrating an example of a functional configuration of the gas concentration estimation device according to the present embodiment. [Figure 5] 10 is a flowchart illustrating an example of a model estimation process according to the present embodiment. [Figure 6] 4 is a flowchart illustrating an example of a gas concentration estimation process according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described below. The following describes a combustion control system 1 including a gas concentration estimation device 10 that estimates the gas concentration in a combustion furnace at the current time from the gas concentration (i.e., the gas concentration including a time delay) measured using an infrared gas analyzer when the gas concentration of gas (exhaust gas) discharged from a combustion furnace into a flue is measured.

[0012] <Overall configuration of combustion control system 1> The overall configuration of a combustion control system 1 according to this embodiment is shown in Fig. 1. As shown in Fig. 1, the combustion control system 1 according to this embodiment includes a gas concentration estimation device 10, an exhaust gas concentration measuring instrument 20, a control device 30, a valve 40, a peripheral sensor 50, a combustion furnace 60, and a flue 70.

[0013] The combustion furnace 60 is, for example, a heating furnace, boiler, incineration, or other type of equipment in a plant. The flue 70 is equipment that serves as a passageway for gas (exhaust gas) discharged from the combustion furnace 60. The exhaust gas that passes through the flue 70 is drawn into the exhaust gas concentration measuring instrument 20 and is ultimately discharged to equipment such as a chimney.

[0014] The flue gas concentration measuring instrument 20 is an infrared gas analyzer that measures the gas concentration (for example, CO concentration or O2 concentration) of the flue gas in the flue and outputs the measurement value to the gas concentration estimation device 10. Here, since the flue gas concentration measuring instrument 20 measures the gas concentration of the flue gas drawn in from the flue 70, a time delay occurs in the measurement value. Specifically, if the gas concentration in the combustion furnace 60 at time t is y(t), the flue gas concentration measuring instrument 20 measures the gas concentration y(t-τ) in the combustion furnace 60 a certain time lag τ ago from the current time t.

[0015] The time delay τ is generally the time it takes for the flue gas discharged from the combustion furnace 60 to reach the flue gas concentration measuring instrument 20, but the time required for the flue gas concentration measuring instrument 20 to make a measurement may also be taken into consideration. That is, if the time it takes for the flue gas discharged from the combustion furnace 60 to reach the flue gas concentration measuring instrument 20 is τ1 and the time required for the flue gas concentration measuring instrument 20 to make a measurement is τ2, then τ may be equal to τ1 or τ may be equal to τ1 + τ2. Furthermore, if there is any other time that affects the time delay τ, that time may also be taken into consideration. Note that τ1 can be calculated from the distance of the flue duct 70 from the combustion furnace 60 until the flue gas reaches the flue gas concentration measuring instrument 20 and the flow velocity of the flue gas in the flue duct 70.

[0016] The peripheral sensors 50 are various sensors that measure various physical quantities around or in the vicinity of the combustion furnace 60 and various physical quantities of equipment related to the combustion furnace 60 (for example, the flue 70, etc.), and output the measurement values ​​to the gas concentration estimation device 10. In the following, the total number of peripheral sensors 50 is n, and when the peripheral sensors 50 are not distinguished from one another, they are referred to as "peripheral sensors 50," and when the peripheral sensors 50 are to be distinguished from one another, they are referred to as "peripheral sensor 501," "peripheral sensor 502," ..., "peripheral sensor 50" n For i=1, 2, . . . , n, at time t, the peripheral sensor 50 i The measured value is x iHere, examples of physical quantities measured by the peripheral sensor 50 include the temperature inside the combustion furnace 60, the pressure inside the combustion furnace 60, the temperature inside the flue 70, the flow velocity of the exhaust gas inside the flue 70, the outside air temperature, and the wind speed. However, these physical quantities are merely examples, and it goes without saying that the physical quantities measured by the peripheral sensor 50 are not limited to these.

[0017] The gas concentration estimation device 10 receives the gas concentration y(t-τ) from the exhaust gas concentration measuring instrument 20 at each time t, and also receives the physical quantities x1(t), x2(t), . . . , x from each peripheral sensor 50. n (t) and estimate the gas concentration y(t) at that time t.

[0018]

number

[0019] That is, the gas concentration estimation device 10 calculates the gas concentration y(t-τ) with a time delay and the physical quantities x1(t), x2(t), . . . , x at each time t. n The gas concentration y^(t) at time t (i.e., the gas concentration without time delay) is estimated from (t). In other words, the gas concentration estimation device 10 functions as a software sensor that estimates the gas concentration y^(t) at each time t.

[0020] Here, the gas concentration estimation device 10 executes a model estimation process for estimating a gas concentration without time delay (hereinafter, this model will be represented by f and will also be referred to as a "gas concentration estimation model f"), and a gas concentration estimation process for estimating a gas concentration without time delay using this gas concentration estimation model f. The model estimation process is a process executed offline (i.e., when the combustion furnace 60 is not operating), whereas the gas concentration estimation process is a process executed online (i.e., when the combustion furnace 60 is operating).

[0021] The control device 30 calculates the optimal opening / closing angle (or opening / closing amount) of the valve 40 based on the gas concentration y^(t) received from the gas concentration estimation device 10, and outputs a control command including the opening / closing angle to the valve 40. The valve 40 is a fuel valve that adjusts the amount of fuel flowing into the combustion furnace 60, and an air valve that adjusts the amount of air (oxygen) flowing into the combustion furnace 60.

[0022] Here, the heat loss and thermal efficiency in the combustion furnace 60 fluctuate depending on the amount of fuel and air flowing into the combustion furnace 60, and as a result, the gas concentration in the combustion furnace 60 also fluctuates. For this reason, the control device 30 calculates the opening / closing angle (or opening / closing amount) of the valve 40 using a known control technique so as to optimize the heat loss and thermal efficiency in the combustion furnace 60, and outputs the opening / closing angle (or opening / closing amount) to the valve 40. There are various known control techniques such as this, and an example is the technique described in Japanese Patent No. 6135831.

[0023] In general, the relationship between the excess air ratio and heat loss, and the relationship between the excess air ratio and thermal efficiency are shown in Figure 2. In Figure 2, the vertical axis represents heat loss or thermal efficiency, and the horizontal axis represents the excess air ratio. The excess air ratio is the ratio of the amount of air actually flowing into the combustion furnace 60 to the theoretical amount of air required for combustion per unit of fuel. In Figure 2, line 1001 represents heat loss due to excess air, and curve 1002 represents heat loss due to incomplete combustion. As shown by line 1001, the greater the excess air ratio is above 1, the greater the heat loss due to heating of excess air. On the other hand, as shown by curve 1002, a small excess air ratio causes incomplete combustion, resulting in greater heat loss due to CO generation, and if it exceeds a certain threshold, smoke will be generated. Also in Figure 2, curve 2001 represents the thermal efficiency of the combustion furnace 60. As shown by curve 2001, thermal efficiency is maximized in region D, which includes an excess air ratio where the heat loss due to excess air and the heat loss due to incomplete combustion are approximately the same, and decreases as the excess air ratio moves away from region D. Therefore, control device 30 calculates the opening and closing angles (or opening and closing amounts) of valves 40 (fuel valve and air valve) so that the heat loss and thermal efficiency are within region D, and outputs a control command including the opening and closing angles to valves 40.

[0024] The overall configuration of the combustion control system 1 shown in FIG. 1 is an example, and is not limited to this. For example, the system may include various facilities, equipment, devices, etc. that are not shown.

[0025] <Hardware Configuration of Gas Concentration Estimation Device 10> An example of the hardware configuration of the gas concentration estimation apparatus 10 according to this embodiment is shown in Fig. 3. As shown in Fig. 3, the gas concentration estimation apparatus 10 according to this embodiment includes an input device 101, a display device 102, an external I / F 103, a communication I / F 104, a processor 105, and a memory device 106. These pieces of hardware are connected to each other via a bus 107 so as to be able to communicate with each other.

[0026] The input device 101 is, for example, a keyboard, a mouse, a touch panel, various physical buttons, etc. The display device 102 is, for example, a display, a display panel, etc. Note that the gas concentration estimation device 10 does not necessarily have to include at least one of the input device 101 and the display device 102, for example.

[0027] The external I / F 103 is an interface with an external device such as a recording medium 103a. Examples of the recording medium 103a include a CD (Compact Disc), a DVD (Digital Versatile Disk), an SD memory card (Secure Digital memory card), and a USB (Universal Serial Bus) memory card.

[0028] The communication I / F 104 is an interface for connecting the gas concentration estimation apparatus 10 to a communication network. The processor 105 is, for example, a central processing unit (CPU) or a graphics processing unit (GPU), etc. The memory device 106 is, for example, a solid state drive (SSD), a random access memory (RAM), a read only memory (ROM), a flash memory, etc.

[0029] 3 is an example, and the gas concentration estimation apparatus 10 may have other hardware configurations. For example, the gas concentration estimation apparatus 10 may have multiple processors 105 and multiple memory devices 106, or may have various types of hardware other than the hardware shown in the figure.

[0030] <Functional Configuration of Gas Concentration Estimation Device 10> An example of the functional configuration of the gas concentration estimation apparatus 10 according to this embodiment is shown in Fig. 4. As shown in Fig. 4, the gas concentration estimation apparatus 10 according to this embodiment includes a model estimation processing unit 201 and a gas concentration estimation processing unit 202. These units are realized, for example, by a processor 105 executing one or more programs installed in the gas concentration estimation apparatus 10. The gas concentration estimation apparatus 10 according to this embodiment also includes a performance data storage unit 203. The storage unit 203 is realized, for example, by the memory device 106, but may also be realized by a database server connected via a communication network.

[0031] The actual data storage unit 203 stores the gas concentration y(t) measured by the exhaust gas concentration measuring instrument 20 and the physical quantities x1(t), x2(t), . . . , x measured by each peripheral sensor 50. n (t) and the actual data z(t):=(y(t),x1(t),x2(t),...,x n That is, the actual data storage unit 203 stores an actual data set {z(t)}, which is a set of actual data. At each time t, the gas concentration estimation device 10 calculates the gas concentration y(t-τ) with a time lag τ and the physical quantities x1(t), x2(t), . . . , x n (t), and the gas concentration y(t-τ) and the physical quantities x1(t-τ), x2(t-τ), . . ., x received at time t-τ in the past are n (t-τ) and the actual data at time t-τ are associated with each other, and the actual data at time t-τ is z(t-τ)=(y(t-τ),x1(t-τ),x2(t-τ),...,x n (t-τ)) is obtained.

[0032] The model estimation processing unit 201 estimates a gas concentration estimation model f from the actual data set {z(t)}. Here, the model estimation processing unit 201 includes a data acquisition unit 211 and a model estimation unit 212. The data acquisition unit 211 acquires the actual data set {z(t)} from the actual data storage unit 203. The model estimation unit 212 estimates a gas concentration estimation model f using the actual data set {z(t)} acquired by the data acquisition unit 211. Note that the gas concentration estimation model f is, for example, a statistical model or a machine learning model, and has a parameter θ. In the following, when it is specified that the gas concentration estimation model f has a parameter θ, it will be referred to as "f θ " is expressed as ".

[0033] At each time t, the gas concentration estimation processing unit 202 uses the gas concentration estimation model f estimated by the model estimation processing unit 201 to calculate the gas concentration y(t-τ) with a time lag τ and each physical quantity x1(t), x2(t), . . . , x n (t), the gas concentration y^(t) at the current time t is estimated from y(t-τ), x1(t), x2(t), . . . , x n (t) is the explanatory variable and y(t) is the target variable, y^(t)=f(y(t-τ),x1(t),x2(t),···,x n (t)) calculates the estimated value y^(t) of the gas concentration y(t) at the current time t.

[0034] <Model estimation process> The model estimation process according to this embodiment will be described with reference to Fig. 5. In the following, it is assumed that an actual data set {z(t)|z=1, ,T} for a certain period in the past is stored in the actual data storage unit 203. Note that in the following model estimation process, time t is a time in the past.

[0035] The data acquisition unit 211 of the model estimation processing unit 201 acquires the actual data set {z(t)|z=1, . . . , T} from the actual data storage unit 203 (step S101).

[0036] The model estimation unit 212 of the model estimation processing unit 201 estimates a gas concentration estimation model f using the actual data set {z(t)|z=1, . . . , T} acquired in step S101 (step S102). That is, the model estimation unit 212 estimates the gas concentration estimation model f at time t by using the actual data set {z(t)|z=1, . . . , T} as learning data. θ (y(t-τ),x1(t),x2(t),···,x n The parameter θ is learned so that the estimation accuracy of (t) is high.

[0037] For example, when a multiple regression model is adopted as the gas concentration estimation model f, the gas concentration estimation model f is expressed as follows:

[0038]

number

[0039] At this time, the model estimation unit 212 updates (learns) the parameter θ so as to minimize the error E between y(t) and y^(t), for example, by a known optimization method. Note that various errors can be used as the error E, but when the mean square error is used, for example, the error E is expressed as follows:

[0040]

number

[0041] <Gas concentration estimation processing> The gas concentration estimation process according to this embodiment will be described with reference to FIG. 6. This gas concentration estimation process is repeatedly executed at every time t, but the following describes the gas concentration estimation process for a certain time t. Note that in the following gas concentration estimation process, time t is the current time. In addition, the gas concentration estimation model f=f θ The parameter θ is assumed to have been learned in the above model estimation process.

[0042] The gas concentration estimation processing unit 202 calculates the gas concentration y(t-τ) with a time delay τ and the physical quantities x1(t), x2(t), . . . , x n (t) is received as measurement data (step S201).

[0043] The gas concentration estimation processing unit 202 uses the gas concentration estimation model f to estimate the measured data y(t-τ), x1(t), x2(t), . . . , x n (t), the gas concentration y^(t) at the current time t is estimated from (t) (step S202). That is, the gas concentration estimation processing unit 202 calculates y^(t)=f(y(t-τ),x1(t),x2(t), . . . ,x n The gas concentration y^(t) at the current time t is estimated using the calculated gas concentration y^(t). This gas concentration y^(t) is output to the control device 30, which controls the opening / closing angle (or opening / closing amount) of the valve 40. This controls the gas concentration in the combustion furnace 60.

[0044] <Summary> As described above, in the combustion control system 1 according to this embodiment, the gas concentration estimation device 10 can estimate the gas concentration y^(t) without a time delay from the gas concentration y(t-τ) with a time delay measured by the exhaust gas concentration measuring instrument 20, which is an infrared gas analyzer. Therefore, the control device 30 can perform high-performance control of the combustion furnace 60 (that is, control that achieves stable high combustion efficiency and high energy savings) using this gas concentration y^(t) without a time delay.

[0045] The gas concentration estimation device 10 of this embodiment uses a gas concentration estimation model f realized by a statistical model or a machine learning model when estimating the gas concentration at the current time t. However, for example, a pre-designed physical model may be used as the gas concentration estimation model f, and the gas concentration at the current time t may be estimated using this physical model.

[0046] The present invention is not limited to the above-described specifically disclosed embodiments, and various modifications, changes, and combinations with known technologies are possible without departing from the scope of the claims. [Explanation of symbols]

[0047] 1. Combustion control system 10 Gas concentration estimation device 20 Exhaust gas concentration measuring instrument 30 Control device 40 valves 50 Peripheral Sensors 60 Combustion Furnace 70 Flue 101 Input Device 102 Display device 103 External I / F 103a Recording media 104 Communication I / F 105 processors 106 Memory Device 107 Bus 201 Model estimation processing unit 202 Gas concentration estimation processing unit 203 Performance data storage unit 211 Data Acquisition Unit 212 Model Estimation Unit

Claims

1. A gas concentration estimation device that estimates a gas concentration representing a CO concentration or an O 2 concentration in a combustion furnace in order to control the combustion furnace, comprising: A receiving means for receiving a gas concentration measurement value with a time delay from the measurement time, which is measured by an infrared gas analyzer to measure the concentration of CO or O2 emitted from the combustion furnace to the flue, and a plurality of physical quantity measurement values, which are obtained by measuring a plurality of predetermined physical quantities related to the combustion furnace by sensors; an estimation means for calculating an estimate of the measured gas concentration value without a time delay as a gas concentration for controlling the combustion furnace from the measured gas concentration value with a time delay and the plurality of measured physical quantities using a model for estimating the gas concentration without a time delay; and a gas concentration estimation device, wherein the plurality of physical quantity measurement values ​​include at least a temperature inside the combustion furnace, a pressure inside the combustion furnace, a flow velocity of gas discharged into the flue, an outside air temperature outside the combustion furnace, a wind speed outside the combustion furnace, physical quantities measured in the vicinity of or around the combustion furnace, and physical quantities measured in equipment related to the combustion furnace.

2. the model is a statistical model or a machine learning model having parameters to be learned, a learning means for learning parameters of the model using the gas concentration measurement values ​​and the plurality of physical quantity measurement values ​​over a predetermined period in the past as learning data; The estimation means 2. The gas concentration estimation device according to claim 1, wherein an estimate of the gas concentration measurement value without a time delay is calculated as a gas concentration for controlling the combustion furnace from the gas concentration measurement value with a time delay and the plurality of physical quantity measurement values ​​using the model having learned parameters.

3. The time delay is τ, the gas concentration measurement value at time t is y(t), the number of the plurality of physical quantities is n, and the plurality of physical quantity measurement values ​​at time t is x １ (t), ..., x ｎ As (t), The receiving means At each time t, the time-delayed gas concentration measurement value y(t-τ) and the plurality of physical quantity measurement values ​​x １ (t), ..., x ｎ (t) and The estimation means At each time t, the model is used to calculate the time-delayed gas concentration measurement value y(t-τ) and the plurality of physical quantity measurement values ​​x １ (t), ..., x ｎ 3. The gas concentration estimation device according to claim 1, wherein an estimated value of the gas concentration measurement value y(t) without time delay is calculated from the measured gas concentration value y(t).

4. The time it takes for the gas discharged from the combustion furnace into the flue to reach the infrared gas analyzer is τ １ , the time required to measure the concentration of the gas by the infrared gas analyzer is τ ２ Then, the time delay τ is τ=τ １ or τ = τ １ +τ ２ The gas concentration estimation device according to claim 3, wherein the gas concentration is expressed by:

5. A gas concentration estimation device that estimates a gas concentration representing a CO concentration or an O 2 concentration in a combustion furnace in order to control the combustion furnace, a receiving step of receiving a gas concentration measurement value with a time delay from the measurement time, which is measured by an infrared gas analyzer to measure the concentration of CO or O2 emitted from the combustion furnace into the flue, and a plurality of physical quantity measurement values, which are measured by sensors to measure a plurality of predetermined physical quantities related to the combustion furnace; an estimation procedure for calculating an estimate of the measured gas concentration value without a time delay as a gas concentration for controlling the combustion furnace from the measured gas concentration value with a time delay and the plurality of measured physical quantities using a model for estimating the gas concentration without a time delay; Run a gas concentration estimation method, wherein the plurality of physical quantity measurement values ​​include at least a temperature inside the combustion furnace, a pressure inside the combustion furnace, a flow velocity of gas discharged into the flue, an outside air temperature outside the combustion furnace, a wind speed outside the combustion furnace, physical quantities measured in the vicinity of or around the combustion furnace, and physical quantities measured in equipment related to the combustion furnace.

6. A gas concentration estimation device that estimates a gas concentration representing a CO concentration or an O 2 concentration in a combustion furnace in order to control the combustion furnace, a receiving step of receiving a gas concentration measurement value with a time delay from the measurement time, which is measured by an infrared gas analyzer to measure the concentration of CO or O2 emitted from the combustion furnace into the flue, and a plurality of physical quantity measurement values, which are measured by sensors to measure a plurality of predetermined physical quantities related to the combustion furnace; an estimation procedure for calculating an estimate of the measured gas concentration value without a time delay as a gas concentration for controlling the combustion furnace from the measured gas concentration value with a time delay and the plurality of measured physical quantities using a model for estimating the gas concentration without a time delay; Execute The program, wherein the plurality of physical quantity measurement values ​​include at least the temperature inside the combustion furnace, the pressure inside the combustion furnace, the flow velocity of gas discharged into the flue, the outside air temperature outside the combustion furnace, the wind speed outside the combustion furnace, physical quantities measured in the vicinity of or around the combustion furnace, and physical quantities measured in equipment related to the combustion furnace.

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