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WO2015119127A1 - Dispositif de détection de concentration en gaz - Google Patents

Dispositif de détection de concentration en gaz Download PDF

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Publication number
WO2015119127A1
WO2015119127A1 PCT/JP2015/053034 JP2015053034W WO2015119127A1 WO 2015119127 A1 WO2015119127 A1 WO 2015119127A1 JP 2015053034 W JP2015053034 W JP 2015053034W WO 2015119127 A1 WO2015119127 A1 WO 2015119127A1
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Prior art keywords
concentration
gas
temperature
output value
calibration curve
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PCT/JP2015/053034
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English (en)
Japanese (ja)
Inventor
直輝 大串
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis

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  • the present invention relates to a gas concentration detection device that detects the concentration of a gas in consideration of the temperature characteristics of the amount of infrared absorption by the gas.
  • a technique for detecting the concentration of a gas from the amount of infrared absorption of a detection target gas using a NDIR (Non-dispersive Infrared Analyzer) type (non-dispersion type) gas concentration detection device is known.
  • NDIR Non-dispersive Infrared Analyzer
  • Japanese Patent No. 4154274 Patent Document 1 uses a correction amount determined by the magnitude of the average output change rate in the temperature region between the detected temperature and the reference temperature.
  • a technique for detecting the gas concentration by correcting the detection output value is disclosed.
  • Patent Document 1 a plurality of calibration curve data for a plurality of temperatures are prepared in order to improve the detection accuracy of the gas concentration in consideration of such temperature characteristics. Therefore, there has been a problem that it takes a long time to acquire calibration curve data, or a long processing time due to a large amount of calibration curve data.
  • the present invention has been made in order to solve the above-described problems, and its purpose is to suppress the increase in the amount of data required in advance and to control the gas concentration in consideration of the temperature characteristics of the infrared absorption amount.
  • the object is to provide a gas concentration detection device that detects with high accuracy.
  • a gas concentration detection apparatus includes a concentration detection unit that outputs a signal indicating a concentration output value corresponding to a gas concentration, and a temperature detection that outputs a signal indicating a temperature output value corresponding to the temperature of the gas.
  • a calculation unit that calculates a gas concentration based on the first calibration curve shown.
  • the first calibration curve includes a correction coefficient proportional to the temperature output value.
  • the gas concentration can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared absorption by the gas. .
  • the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress an increase in the calibration curve data creation time and the amount of calibration curve data.
  • the calculation unit calculates a correction coefficient corresponding to the light absorption rate by the gas that varies inversely with the temperature change of the gas.
  • the gas concentration can be calculated with high accuracy.
  • the calculation unit calculates the reference output value based on the temperature output value and a second calibration curve indicating the relationship of the reference output value to the temperature output value.
  • the gas concentration can be calculated with higher accuracy using the calculated reference output value.
  • the second calibration curve is set by deriving an approximate expression of a predetermined order based on a plurality of concentration output values acquired in advance corresponding to each of a plurality of gas temperatures at the reference concentration.
  • the gas concentration can be calculated with higher accuracy based on the second calibration curve.
  • the first calibration curve derives an approximate expression of a predetermined order multiplied by a correction coefficient based on a plurality of concentration output values acquired in advance corresponding to each of the plurality of concentrations of the gas at the reference temperature. Is set.
  • the gas concentration can be calculated with higher accuracy based on the first calibration curve.
  • the concentration detection unit is provided between the light receiving sensor and the light source, an optical path portion into which the gas to be detected is introduced, a light source that emits infrared light, a light receiving sensor that detects infrared light emitted from the light source, and the light receiving sensor.
  • Bandpass filter is provided between the light receiving sensor and the light source, an optical path portion into which the gas to be detected is introduced, a light source that emits infrared light, a light receiving sensor that detects infrared light emitted from the light source, and the light receiving sensor.
  • the gas concentration can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared absorption by the gas. .
  • the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress an increase in the calibration curve data creation time and the amount of calibration curve data. Therefore, it is possible to provide a gas concentration detection device that can suppress an increase in a necessary data amount in advance and detect a gas concentration with high accuracy in consideration of a temperature characteristic of an infrared absorption amount.
  • FIG. 1 shows the structure of the gas concentration detection apparatus which concerns on this Embodiment. It is a circuit block diagram of the gas concentration detection apparatus which concerns on this Embodiment. It is a figure for demonstrating the 1st calibration curve in reference
  • FIG. 6A is a diagram illustrating an error of a detection value with respect to the concentration under a plurality of temperature environments according to the comparative example.
  • FIG. 6B is a diagram illustrating an error of a detection value with respect to the concentration under a plurality of temperature environments in the present embodiment.
  • FIG. 1 is a diagram showing a configuration of a gas concentration detection apparatus 10 according to the present embodiment.
  • the configuration of the gas concentration detection device 10 shown in FIG. 1 is an example, and is not particularly limited to the configuration shown in FIG.
  • the gas concentration detection device 10 is an infrared absorption (NDIR) gas sensor.
  • NDIR infrared absorption
  • the gas that is a concentration detection target by the gas concentration detection apparatus 10 in the present embodiment will be described as being carbon dioxide, the gas that is the detection target is not particularly limited to carbon dioxide.
  • the gas concentration detection device 10 is, for example, a ventilation control based on the carbon dioxide concentration in a BEMS (Building Energy Management System), a control for keeping the indoor carbon dioxide concentration within a predetermined range in a plant cultivation facility, or the like. Used for.
  • BEMS Building Energy Management System
  • the gas concentration detection device 10 includes a concentration detection unit 30 that performs a gas concentration detection operation, a thermistor 28 that is a temperature detection unit that detects the temperature of the gas, lighting control and concentration of the light source 20. And a drive circuit 40 for performing predetermined processing on the gas concentration detection signal output from the detection unit 30 and the temperature detection signal output from the thermistor 28.
  • a concentration detection unit 30 that performs a gas concentration detection operation
  • a thermistor 28 that is a temperature detection unit that detects the temperature of the gas, lighting control and concentration of the light source 20.
  • a drive circuit 40 for performing predetermined processing on the gas concentration detection signal output from the detection unit 30 and the temperature detection signal output from the thermistor 28.
  • Each of the component parts of the concentration detection unit 30 and the thermistor 28 is provided at a predetermined position on one surface of the circuit board 12.
  • the components of the drive circuit 40 are provided at predetermined positions on the circuit board 12.
  • the concentration detector 30 includes a light source 20, a holding base 22, a pyroelectric sensor 24, and an optical filter 26 as components.
  • the light source 20 is provided at a position separated from the pyroelectric sensor 24 by a predetermined distance.
  • An optical path 18 is provided between the light source 20 and the pyroelectric sensor 24.
  • the light source 20 emits infrared rays toward the pyroelectric sensor 24.
  • the light source 20 is described as being a filament lamp, for example, but may be a light source that emits infrared rays, such as an LED (Light Emitting Diode).
  • the light source 20 is held by a holding table 22 fixed to the circuit board 12.
  • the light source 20 is controlled to blink at a predetermined cycle.
  • the cross-sectional shape of the holding table 22 has a semi-elliptical shape opened to the pyroelectric sensor 24 side.
  • a mirror surface is formed inside the semi-elliptical shape. That is, the holding table 22 is an elliptical mirror.
  • the light source 20 is provided at a semi-elliptical focal position of the holding table 22. Therefore, the infrared rays radiated from the light source 20 pass through the optical path 18 and enter the pyroelectric sensor 24 directly, or reflect the mirror surface formed on the holding base 22 and then pass through the optical path 18. Or incident on the pyroelectric sensor 24.
  • the pyroelectric sensor 24 is a pyroelectric infrared sensor using bulk ceramics.
  • the pyroelectric sensor 24 is provided with an incident window, which is a part that receives infrared rays emitted from the light source 20, facing the light source 20.
  • An optical filter 26 is provided in the incident window.
  • the optical filter 26 is, for example, a bandpass filter that passes infrared rays in a predetermined wavelength band.
  • the predetermined wavelength band is, for example, a wavelength band including the vicinity of 4.26 ⁇ m, which is an infrared wavelength having a high absorption rate by carbon dioxide molecules.
  • the predetermined wavelength band has a wavelength corresponding to the type of gas that is the concentration detection target (that is, the absorption rate of the gas that is the concentration detection target is high).
  • a wavelength band based on (wavelength) is selected. That is, the pyroelectric sensor 24 receives infrared rays in a predetermined wavelength band among infrared rays emitted from the light source 20.
  • the thermistor 28 is provided around the pyroelectric sensor 24 and is fixed to the circuit board 12. In the thermistor 28, a constant current flows when a voltage is applied from the drive circuit 40, and a voltage generated when the constant current flows is detected in the drive circuit 40 as an output voltage.
  • the cover 14 is provided so as to cover the components of the concentration detection unit 30 and the thermistor 28, and is fixed to the circuit board 12.
  • the cover 14 is provided with an intake port 16 for taking in gas from the outside of the cover 14 and discharging gas inside the cover 14.
  • the intake port 16 is provided with an air filter.
  • the detection of the concentration of carbon dioxide by the gas concentration detection device 10 is performed in a state where gas is taken into the cover 14 from the intake port 16.
  • the pyroelectric sensor 24 When infrared rays are emitted from the light source 20 toward the pyroelectric sensor 24, the emitted infrared rays are received by the pyroelectric sensor 24.
  • the pyroelectric sensor 24 outputs a voltage in response to infrared light reception. At this time, the output voltage varies depending on the concentration and temperature of carbon dioxide in the optical path section 18.
  • the optical filter 26 since the optical filter 26 transmits infrared rays having a wavelength with high carbon dioxide absorption, it is possible to convert the output value of the pyroelectric sensor 24 into the concentration of carbon dioxide.
  • FIG. 2 is a circuit configuration diagram of the gas concentration detection apparatus 10 according to the present embodiment.
  • the drive circuit 40 includes an amplifier circuit 42, an AD conversion circuit 44, and a density conversion processing circuit 46.
  • the density conversion processing circuit 46 corresponds to a calculation unit in the claims of the present application.
  • the circuit configuration of the gas concentration detection apparatus 10 shown in FIG. 2 is an example, and is not limited to the circuit configuration shown in FIG.
  • the amplifying circuit 42 is configured by, for example, an amplifier, and amplifies the signal strength of the concentration detection signal (output voltage) of the concentration detector 30 and the signal strength of the temperature detection signal (output voltage) of the thermistor 28.
  • the AD conversion circuit 44 converts the analog signal whose signal intensity is amplified in the amplification circuit 42 into a digital signal.
  • a well-known technique may be used for amplification of signal intensity and conversion from an analog signal to a digital signal.
  • the concentration conversion processing circuit 46 performs a predetermined process on the digital signal converted by the AD conversion circuit 44 to detect the concentration C of carbon dioxide contained in the gas introduced into the cover 14.
  • the density conversion processing circuit 46 is realized by, for example, a CPU (Central Processing Unit).
  • the CPU executes predetermined arithmetic processing and control processing by executing a program stored in a storage unit (not shown). For example, the CPU executes a control process for lighting the light source 20 and a control process for applying a voltage to the thermistor 28 in addition to a calculation process for calculating the concentration of carbon dioxide.
  • the detection of the concentration of carbon dioxide in the gas concentration detection apparatus 10 is performed in the following procedure.
  • a temperature detection signal is acquired from the thermistor 28.
  • the light source 20 is turned on.
  • the output value V of the pyroelectric sensor 24 is acquired.
  • Predetermined signal processing is executed on the acquired output value V of the pyroelectric sensor 24.
  • the output value V of the pyroelectric sensor 24 corresponds to the concentration output value of the present invention. Further, the temperature detection signal of the thermistor 28 corresponds to the temperature output value of the present invention.
  • the predetermined signal processing includes, for example, processing for removing noise from the output waveform of the pyroelectric sensor 24 using a moving average method, processing for amplifying the signal intensity by the amplifier circuit 42, and digital data by the AD conversion circuit 44. And the process of converting to. These processes are also performed on the temperature detection signal. Further, the thermistor temperature Th [K] is calculated from the temperature detection signal. The calculation of the thermistor temperature Th may be performed in the above (1).
  • the concentration C of carbon dioxide is calculated from the thermistor temperature Th and the output value V of the pyroelectric sensor 24.
  • the light source 20 is turned off.
  • the gas concentration detection apparatus 10 performs the processes (1) to (6) at regular intervals, for example.
  • the concentration conversion processing circuit 46 calculates the concentration of carbon dioxide based on the output value V of the pyroelectric sensor 24, the first calibration curve obtained in advance, the thermistor temperature Th, and the second calibration curve.
  • the data relating to the first calibration curve and the data relating to the second calibration curve are acquired in advance at the time of manufacturing the gas concentration detection device 10 and stored in a storage medium such as a memory provided in the drive circuit 40.
  • the first calibration curve indicates the relationship between the carbon dioxide concentration C and the output value V of the pyroelectric sensor 24 at a predetermined reference temperature (for example, 25 ° C.). More specifically, the first calibration curve shows the relationship between the value (V / V0) obtained by normalizing the output value V of the pyroelectric sensor 24 with the reference output value V0 and the concentration C of carbon dioxide. An output value of the pyroelectric sensor 24 corresponding to each of the plurality of carbon dioxide concentrations at the reference temperature is acquired in advance, and the first calibration curve is based on the output values of the plurality of pyroelectric sensors 24 acquired in advance. Thus, an approximate expression of a predetermined order multiplied by the correction coefficient ⁇ is derived and set.
  • the reference output value V0 is an output value of the pyroelectric sensor 24 corresponding to the thermistor temperature Th when the concentration of carbon dioxide is a predetermined reference concentration (for example, 0 ppm).
  • the reference output value V0 is calculated using a second calibration curve described later based on the thermistor temperature Th.
  • the first calibration curve is represented by the following equation.
  • C (carbon dioxide concentration) ⁇ (correction coefficient) ⁇ f1 (V / V0) (Equation 1)
  • F1 in the above (Expression 1) is a function of a predetermined order, and may be, for example, a quadratic function or a cubic function.
  • f1 is a cubic function
  • the gas concentration C is expressed by the following equation.
  • a1 to a4 are calculated based on a combination of the concentrations of a plurality of types of carbon dioxide and the output value of the pyroelectric sensor 24 obtained in advance through experiments or the like at the reference temperature. For example, as shown in FIG.
  • output values of a plurality of pyroelectric sensors 24 respectively corresponding to a plurality of predetermined carbon dioxide concentrations (for example, concentrations of 0 ppm, 400 ppm, 1000 ppm, and 2000 ppm) at the reference temperature are obtained in advance.
  • A1 to a4 are calculated based on the acquired output values acquired by experiments or the like.
  • Equation 2 The above (Equation 2) and the calculated values of a1 to a4 are stored in a storage medium such as a memory provided in the drive circuit 40.
  • Th 25 indicates the thermistor temperature [K] at 25 ° C. That is, the correction coefficient ⁇ is proportional to the temperature output value.
  • B represents a constant
  • Vth represents the output voltage of the thermistor 28
  • Vcc represents the voltage applied from the drive circuit 40 to the thermistor 28.
  • the above (Equation 3) and the constant B are stored in a storage medium such as a memory provided in the drive circuit 40.
  • the correction coefficient ⁇ is a coefficient proportional to the thermistor temperature Th.
  • the correction coefficient ⁇ is stored in a storage medium such as a memory provided in the drive circuit 40.
  • the first calibration curve expressed by the above is indicated by a solid line in FIG.
  • the horizontal axis of FIG. 4 indicates the carbon dioxide concentration C
  • the vertical axis of FIG. 4 indicates the normalized value (V / V0).
  • the concentration C and the normalized value (V / V0) are normalized as the concentration C increases, the normalized value (V / V0) decreases, and the concentration C decreases.
  • the value (V / V0) has an increasing relationship.
  • the correction coefficient ⁇ is set in consideration of the temperature characteristics of the amount of absorption by which carbon dioxide absorbs infrared rays.
  • the molar concentration n (mol / l), which means the number of molecules of carbon dioxide, follows the gas equation of state (PV nRT). Therefore, in an environment where the pressure P and the volume V are constant, the temperature Proportional to inverse (inversely proportional to temperature). Therefore, even in an environment with the same carbon dioxide concentration, the amount of absorbed infrared light decreases between the temperature of the gas containing carbon dioxide and the amount of absorbed infrared light as the temperature of the gas containing carbon dioxide increases. There is a relationship in which the amount of infrared absorption increases as the temperature of the gas containing carbon dioxide decreases.
  • the output value V of the pyroelectric sensor 24 is changed to a value higher than the original output value when the infrared absorption amount is decreased. Therefore, the output value V of the pyroelectric sensor 24 is converted to a value lower than the original density.
  • the output value V of the pyroelectric sensor 24 changes to a value lower than the original output value. Therefore, the output value V of the pyroelectric sensor 24 is converted to a value higher than the original density.
  • the concentration of carbon dioxide to be calculated is the ratio of the volume of carbon dioxide gas to the volume inside the cover 14, the relationship between the temperature and the concentration to be calculated differs from the relationship between the temperature and the molar concentration n.
  • FIG. 5 shows the relationship between the wavelength of infrared rays emitted from the light source and the absorption rate of infrared rays by carbon dioxide molecules.
  • the vertical axis in FIG. 5 indicates the infrared absorption rate, and the horizontal axis in FIG. 5 indicates the infrared wavelength.
  • the infrared absorption rate indicates the amount of infrared absorption at a specific wavelength.
  • the thick solid line in FIG. 5 is an absorption spectrum when the gas concentration is ⁇ 50 ° C.
  • the thick broken line in FIG. 5 is an absorption spectrum when the gas concentration is 0 ° C.
  • the thin solid line in FIG. 5 is an absorption spectrum when the gas temperature is 25 ° C.
  • the thin broken line in FIG. 5 is an absorption spectrum when the gas temperature is 50 ° C.
  • the dashed-dotted line in FIG. 5 is an absorption spectrum when the gas temperature is 100 ° C.
  • the concentration of carbon dioxide can be calculated with higher accuracy by setting the correction coefficient ⁇ in consideration of the temperature characteristics of the amount of absorption by which carbon dioxide absorbs infrared rays.
  • the absorption ratio B / A (absorption amount B is the absorption amount A) between the infrared absorption amount A at a predetermined reference temperature Ta (for example, 25 ° C.) and the infrared absorption amount B at the temperature Tb.
  • the normalized value is similar to the reciprocal Ta / Tb of the temperature ratio. That is, the error in the density C occurs in proportion to Ta / Tb.
  • the correction coefficient ⁇ may be a coefficient proportional to the temperature, and is not particularly limited to the above formula, and may be adjusted by experiments or the like.
  • the first calibration curve is corrected by the correction coefficient ⁇ . For example, when the thermistor temperature Th is 50 ° C., the first calibration curve is located above the first calibration curve (solid line in FIG. 4) at the reference temperature (25 ° C.) as shown by the broken line in FIG. Since it is located, the density is corrected downward. Further, when the thermistor temperature Th is 0 ° C., the first calibration curve is located below the first calibration curve at the reference temperature as shown by the one-dot chain line in FIG. Is done.
  • the gas concentration can be calculated with high accuracy in consideration of the temperature characteristic of the infrared absorption amount.
  • the concentration conversion processing circuit 46 calculates the reference output value V0 using the second calibration curve.
  • the second calibration curve shows the relationship between the thermistor temperature Th and the reference output value V0 at a predetermined reference concentration (for example, 0 ppm).
  • the second calibration curve is set by deriving an approximate expression of a predetermined order based on the output values of the plurality of pyroelectric sensors 24 acquired in advance corresponding to each of the plurality of carbon dioxide temperatures at the reference concentration. .
  • the second calibration curve is represented by the following equation.
  • V0 f2 (Th) (Formula 4)
  • F2 in the above (Formula 4) is a function of a predetermined order, and may be, for example, a cubic function or a quartic function.
  • f2 is a quartic function
  • the reference output value V0 is expressed by the following equation.
  • V0 b1 ⁇ Th 4 + b2 ⁇ Th 3 + b3 ⁇ Th 2 + b4 ⁇ Th + b5 (Formula 5)
  • b1 to b5 are calculated based on a combination of a plurality of types of temperatures (thermistor temperature Th) obtained in advance by experiments or the like at the reference concentration and the output value of the pyroelectric sensor 24.
  • the gas concentration detection device 10 replaces a plurality of types of temperatures (thermistor temperature Th) previously acquired by experiments or the like at the reference concentration with the voltage values of a plurality of types of temperatures previously acquired by experiments or the like at the reference concentration (thermistor temperature Th).
  • the output voltage Vth of the thermistor may be used. That is, the reference output value V0 may be obtained from the output voltage Vth of the thermistor. Therefore, in the above (Formula 4) and (Formula 5), Th may be replaced with Vth.
  • the output values of a plurality of pyroelectric sensors 24 respectively corresponding to a plurality of temperatures (for example, 0 ° C., 10 ° C., 25 ° C., 40 ° C., and 50 ° C.) at the reference concentration are previously tested.
  • b1 to b4 are calculated based on the acquired output values.
  • the pyroelectric infrared sensor used in the experimental example is E472SW1 manufactured by Murata Manufacturing Co., Ltd., but generally the same effect can be obtained if the infrared sensor uses bulk piezoelectric ceramics or MEMS (Micro Electro Mechanical Systems). Is expected to be obtained.
  • FIG. 6 (A) shows errors in detection values corresponding to concentrations in a plurality of temperature environments when the correction coefficient ⁇ is not included in the first calibration curve.
  • the vertical axis in FIG. 6A indicates an error, and with 0 as a reference, the upward direction in FIG. 6A is a positive direction, and the downward direction in FIG. 6A is a negative direction.
  • the horizontal axis of FIG. 6A shows the concentration of carbon dioxide.
  • the broken line in FIG. 6 (A) shows the relationship between error and concentration when the temperature (thermistor temperature Th) is 0 ° C.
  • the solid line in FIG. 6A shows the relationship between error and concentration when the temperature is 25 ° C. (reference temperature).
  • the dashed line in FIG. 6A shows the relationship between error and concentration when the temperature is 50 ° C.
  • the error in concentration corresponding to each of the plurality of concentrations is almost zero. This is because the first calibration curve is set based on the output value (actually measured value) of the pyroelectric sensor 24 corresponding to each of a plurality of concentrations at the reference temperature.
  • the output value of the pyroelectric sensor 24 is the original value. It changes to a higher side than the output value (the output value of the pyroelectric sensor 24 for the same density when the temperature is 25 ° C.). For this reason, an error in density occurs on the lower side than an error in density when the temperature is 25 ° C.
  • the infrared absorption amount increases more than the infrared absorption amount when the temperature is 25 ° C. Therefore, the output value of the pyroelectric sensor 24 is higher than the original output value. Also changes to the lower side. For this reason, an error in density occurs on the higher side than an error in density when the temperature is 25 ° C.
  • FIG. 6 (B) shows errors in detected values corresponding to concentrations in a plurality of temperature environments when the correction coefficient ⁇ is included in the first calibration curve.
  • the vertical axis in FIG. 6B represents an error, and with 0 as a reference, the upward direction in FIG. 6B is the positive direction, and the downward direction in FIG. 6B is the negative direction.
  • the horizontal axis in FIG. 6B indicates the concentration of carbon dioxide. Note that the vertical scale in FIG. 6A and the vertical scale in FIG. 6B are the same.
  • the broken line in FIG. 6B shows the relationship between the error and the concentration when the temperature (thermistor temperature Th) is 0 ° C.
  • the solid line in FIG. 6B shows the relationship between error and concentration when the temperature is 25 ° C.
  • the alternate long and short dash line in FIG. 6B shows the relationship between the error and the concentration when the temperature is 50 ° C.
  • the correction coefficient ⁇ proportional to the thermistor temperature Th can be included in the first calibration curve, and therefore the infrared ray proportional to the inverse of the thermistor temperature Th. It is possible to correct the density error caused by the change in the amount of absorption. Therefore, the concentration C of carbon dioxide can be calculated with high accuracy in consideration of the temperature characteristics of the amount of infrared rays absorbed by carbon dioxide.
  • the calibration curve data for a plurality of temperatures can be reduced, it is possible to suppress the time for creating the calibration curve data and the increase in the data amount of the calibration curve data. Therefore, it is possible to provide a gas concentration detection device that can suppress an increase in a necessary data amount in advance and detect a gas concentration with high accuracy in consideration of a temperature characteristic of an infrared absorption amount.
  • a value corresponding to the amount of infrared rays absorbed by the gas that changes in inverse proportion to the change in the thermistor temperature Th specifically, a value Th / standardized by the thermistor temperature Th 25 of the reference temperature (25 ° C.).
  • the reference output value V0 corresponding to the thermistor temperature Th can be calculated based on the second calibration curve, the carbon dioxide concentration C is calculated using the first calibration curve and the calculated reference output value V0. It is possible to calculate with high accuracy.
  • the carbon dioxide concentration C can be calculated using the first calibration curve represented by (Equation 1) and the second calibration curve represented by (Equation 4) including the correction coefficient ⁇ , data acquired in advance While suppressing an increase in the amount, the calculation load can be reduced. Moreover, the increase in the manufacturing cost and design cost of a product can be suppressed by suppressing the increase in the data acquired beforehand and reducing the calculation load.
  • the output values of the pyroelectric sensor 24 corresponding to each concentration are acquired in advance by using four concentrations of 0 ppm, 400 ppm, 1000 ppm, and 2000 ppm as measurement points.
  • the a1 to a4 of the first calibration curve are calculated using the output values, but for example, the output values of the pyroelectric sensor 24 corresponding to the concentrations of four or more points may be acquired in advance, The output value of the pyroelectric sensor 24 corresponding to the density of the measurement points other than the above four points may be acquired in advance, or a plurality of pyroelectrics corresponding to a plurality of densities having a density higher or lower than 2000 ppm as an upper limit value. The output value of the electric sensor 24 may be acquired in advance.
  • pyroelectric sensors corresponding to each temperature are measured at five temperatures of 0 ° C., 10 ° C., 25 ° C., 40 ° C., and 50 ° C.
  • the output values of 24 are acquired in advance, and b1 to b5 of the second calibration curve are calculated using the acquired output values.
  • the output of the pyroelectric sensor 24 corresponding to a temperature of 5 points or more is used.
  • the value may be acquired in advance, the output value of the pyroelectric sensor 24 corresponding to the temperature of the measurement point other than the above five points may be acquired in advance, or a temperature higher or lower than 50 ° C.
  • Output values of a plurality of pyroelectric sensors 24 corresponding to a plurality of temperatures may be acquired in advance, or a plurality of pyroelectrics corresponding to a plurality of temperatures having a lower value or a value lower than 0 ° C. Even if the output value of the sensor 24 is acquired in advance There.
  • each of the concentration measurement points is set to 0, R / 4, R / 2, and R when the measurement range is 0 to R.
  • the correction coefficient ⁇ is proportional to the temperature output value, but is not limited thereto.
  • the correction coefficient ⁇ may be proportional to the power of the temperature output signal.

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Abstract

　L'invention concerne un dispositif de détection de concentration en gaz (10) comportant : une unité de détection de concentration (30) destinée à produire un signal indiquant une valeur de sortie de concentration conformément à la concentration d'un gaz ; une thermistance (28) destinée à produire un signal indiquant une valeur de sortie de température conformément à la température d'un gaz ; et un circuit de traitement de conversion de concentration permettant de calculer des valeurs de sortie standard qui correspondent aux valeurs de sortie de température aux concentrations standard prédéfinies d'un gaz, et de calculer la concentration du gaz sur base d'une première courbe d'étalonnage indiquant une relation entre les valeurs obtenues par normalisation de valeurs de sortie de concentration par les valeurs de sortie standard, et la concentration en gaz par rapport aux valeurs normalisées. La première courbe d'étalonnage comprend un coefficient de correction qui est proportionnel à la valeur de température de sortie.
PCT/JP2015/053034 2014-02-07 2015-02-04 Dispositif de détection de concentration en gaz Ceased WO2015119127A1 (fr)

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JP2014022369 2014-02-07
JP2014-022369 2014-02-07

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WO2015119127A1 true WO2015119127A1 (fr) 2015-08-13

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CN110161181A (zh) * 2018-02-13 2019-08-23 中国石油化工股份有限公司 混合气体的组分浓度识别方法及系统
WO2020066769A1 (fr) * 2018-09-28 2020-04-02 株式会社フジキン Procédé de mesure de concentration
CN112557991A (zh) * 2020-11-12 2021-03-26 珠海一多监测科技有限公司 基于摩尔数量与温度的电流互感器故障诊断方法
JP2022027068A (ja) * 2020-07-31 2022-02-10 株式会社Lixil 分析方法、当該分析方法を採用する分析装置、およびプログラム
CN115931759A (zh) * 2023-03-15 2023-04-07 浙江新寰科环保科技股份有限公司 一种烟气排放的分析系统及方法
CN116046693A (zh) * 2021-10-28 2023-05-02 北京小米移动软件有限公司 气体检测电路及检测方法、存储介质、移动终端
JP2023132864A (ja) * 2022-03-11 2023-09-22 三菱電機株式会社 冷凍サイクル装置

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JP2019045240A (ja) * 2017-08-31 2019-03-22 株式会社堀場製作所 分光分析装置及び分光分析方法
CN110161181A (zh) * 2018-02-13 2019-08-23 中国石油化工股份有限公司 混合气体的组分浓度识别方法及系统
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JP2023132864A (ja) * 2022-03-11 2023-09-22 三菱電機株式会社 冷凍サイクル装置
CN115931759A (zh) * 2023-03-15 2023-04-07 浙江新寰科环保科技股份有限公司 一种烟气排放的分析系统及方法

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