Flame-type atomic absorption spectrophotometer

Abstract

The present invention provides a flame atomic absorption photometer comprising: a burner 110 that forms a flame by burning a mixture of an atomized sample liquid and a mixed gas including a fuel gas and a combustion-assisting gas; flame light detection units 181, 182 that detect light radiated from the flame; and an expired flame determination unit 162 that determines that the flame has gone out when the intensity of the light detected by the flame light detection units is lower than a predetermined threshold value. The flame light detection units selectively detect light having a wavelength of 290 nm to 330 nm inclusive.

Description

Technical Field

[0005]

[0001] The present invention relates to a frame-type atomic absorption photometer.

Background Art

[0002] A frame-type atomic absorption photometer forms a flame by mixing a sample solution atomized by a nebulizer with a combustion gas in a chamber and burning the mixed gas while blowing it out from a slit opening of a burner head. In this flame, the components in the sample are atomized. When light is irradiated onto the flame containing the atomized sample components, only light of a specific wavelength corresponding to the type of atom (element) is absorbed. Therefore, by measuring the absorption of light by the sample atoms, the identification and quantification of elements in the sample can be performed.

[0003] The combustion gas for forming the flame is usually a mixed gas of a fuel gas composed of a hydrocarbon such as acetylene (C2H2) and an oxidizing gas composed of air or nitrous oxide (N2O) or the like. When the combustion gas is burning normally, the flame is stably formed at a position slightly above the upper surface of the burner head by the balance between the combustion rate and the flow rate of the gas blown out from the burner head.

[0004] However, when the balance between the combustion rate and the gas flow rate is disrupted for some reason or when wind flows in from the outside, the flame may disappear at an undesired timing (that is, flashback may occur). Therefore, some conventional frame-type atomic absorption photometers are provided with a light sensor near the flame to constantly monitor the intensity of the light emitted by the flame (flame light), and when the intensity becomes less than the light amount during normal combustion, automatically extinguish the fire and stop the supply of the combustion gas (for example, refer to Patent Document 1).

Prior Art Documents

Patent Documents

[0005] <母000022>

Patent Document 1

[0006] However, even with a flame-type atomic absorption spectrophotometer equipped with a light sensor for monitoring flame light as described above, depending on the operating environment, ambient light such as sunlight or indoor lighting may enter the light sensor, potentially leading to a false determination that the flame is burning normally even though the actual amount of light from the flame is less than that of normal combustion.

[0007] Furthermore, if the balance between the combustion speed of the burner and the flow rate of the gas blown out from the burner head is disrupted, flames may enter the inside of the burner, causing flashback, which is an unstable combustion. Conventionally, various mechanisms have been proposed to prevent such flashback in order to ensure the safety of flame-type atomic absorption spectrophotometers, but there is still room for improvement.

[0008] Furthermore, if the flow rate of the auxiliary combustion gas is insufficient compared to the flow rate of the fuel gas, incomplete combustion may occur, potentially generating toxic gases such as carbon monoxide, or causing the flame temperature to drop, resulting in insufficient atomization of the sample. For this reason, a mechanism to reliably detect incomplete combustion has been required.

[0009] Furthermore, in flame-type atomic absorption spectrophotometers, if the combustion state of the flame becomes temporarily or continuously unstable, soot is generated and accumulates on the burner head. This soot impairs the stability of the flame and therefore needs to be properly removed. However, conventionally, users checked the amount of soot accumulation by directly visually inspecting the burner head, which sometimes made it difficult to accurately assess the extent of soot accumulation.

[0010] The present invention has been made in view of these points, and its objective is to enable accurate detection of abnormalities related to the stability of the flame combustion state in a flame-type atomic absorption spectrophotometer. More specifically, the first objective is to provide a flame-type atomic absorption spectrophotometer that can reliably determine whether or not the flame is burning normally. The second objective is to enable the flame-type atomic absorption spectrophotometer to detect the occurrence of flashback before it occurs. The third objective is to enable the flame-type atomic absorption spectrophotometer to reliably detect the occurrence of incomplete combustion. The fourth objective is to enable the user to reliably understand the amount of soot accumulating on the burner head in a flame-type atomic absorption spectrophotometer. [Means for solving the problem]

[0011] A first aspect of the present invention, which was developed to solve the above problems, is a flame-type atomic absorption spectrophotometer. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit for detecting light emitted from the flame, A flame extinguishing determination unit determines that the flame has extinguished when the intensity of the light detected by the flame light detection unit is lower than a predetermined threshold, It has, The flame light detection unit selectively detects light with a wavelength between 290 nm and 330 nm.

[0012] A second aspect of the present invention, which was developed to solve the above problems, is a flame-type atomic absorption spectrophotometer. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit that detects light emitted from the flame, and selectively detects light with a wavelength of 290 nm to 330 nm, A swan-band light detection unit selectively detects C2 swan-band light from the light emitted from the flame, A flashback indicator determination unit determines that there is a flashback when the ratio of the light intensity detected by the swan-band light detection unit to the light intensity detected by the flame light detection unit falls below a predetermined threshold, It possesses the following characteristics.

[0013] A third aspect of the present invention, which was developed to solve the above problems, is a flame-type atomic absorption spectrophotometer. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit that detects light emitted from the flame, and selectively detects light with a wavelength of 290 nm to 330 nm, A luminous flame detection unit selectively detects light with wavelengths between 800 nm and 1100 nm from the light emitted from the flame, An incomplete combustion determination unit determines that incomplete combustion is occurring when the ratio of the light intensity detected by the flame detection unit to the light intensity detected by the flame light detection unit exceeds a predetermined threshold, It possesses the following characteristics.

[0014] A fourth aspect of the present invention, which was developed to solve the above problems, is a flame-type atomic absorption spectrophotometer. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit that detects light emitted from the flame, and selectively detects light with a wavelength of 290 nm to 330 nm, A bandpass filter that selectively transmits light with wavelengths between 800nm ​​and 1100nm, It has a plurality of photodetectors arranged in two dimensions, flame An image sensor that receives light emitted from and passing through the bandpass filter, For each of the plurality of light detection elements, obtain the ratio of the intensity of the light detected by the light detection element to the intensity of the light detected by the flame light detection unit. When there are a predetermined number or more of the plurality of light detection elements for which the ratio exceeds a predetermined threshold value, a soot deposition determination unit that determines that soot is deposited on the burner; A notification unit that notifies the user to that effect when the soot deposition determination unit determines that soot is deposited on the burner; It has.

Advantages of the Invention

[0015] According to the frame type atomic absorption photometer according to the first aspect, it is possible to reliably determine whether the flame is burning normally. According to the frame type atomic absorption photometer according to the second aspect, it is possible to detect the occurrence of backfire in advance. According to the frame type atomic absorption photometer according to the third aspect, it is possible to reliably detect the occurrence of incomplete combustion. According to the frame type atomic absorption photometer according to the fourth aspect, the user can surely grasp the soot deposition situation. Therefore, according to the frame type atomic absorption photometer according to the first aspect to the fourth aspect, it is possible to accurately detect an abnormality related to the stability of the combustion state of the flame.

Brief Description of the Drawings

[0016] [Figure 1] A diagram showing the main part configuration of a frame type atomic absorption photometer according to the first embodiment of the present invention. [Figure 2] A diagram showing the main part configuration of a frame type atomic absorption photometer according to the second embodiment of the present invention. [Figure 3] A diagram showing the main part configuration of a frame type atomic absorption photometer according to the third embodiment of the present invention. [Figure 4] A diagram showing the main part configuration of a frame type atomic absorption photometer according to the fourth embodiment of the present invention. [Figure 5] A diagram showing the main part configuration of a frame type atomic absorption photometer according to the fifth embodiment of the present invention. [Modes for carrying out the invention]

[0017] [Embodiment 1] Hereinafter, a flame-type atomic absorption spectrophotometer according to the first embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a diagram showing the main components of the flame-type atomic absorption spectrophotometer according to this embodiment. This flame-type atomic absorption spectrophotometer includes a burner 110, a gas supply unit 120, a sample supply unit 130, a light source 140, a spectroscopic unit 150, and a control / processing unit 160.

[0018] The burner 110 comprises a nebulizer 111 for atomizing the sample liquid, a chamber 112 for mixing the atomized sample liquid with a combustion gas, and a burner head 114 that forms a flame 113 by blowing the mixed gas upward and burning it. The burner 110 is also equipped with an ignition unit (not shown) for igniting the gas. A mixture of acetylene as fuel gas and air or nitrous oxide as a combustion aid is supplied to the chamber 112 from the gas supply unit 120 as the combustion gas.

[0019] The gas supply unit 120 includes a fuel gas supply pipe 122 that guides fuel gas from a fuel gas source 121 such as a gas cylinder to a burner 110, a fuel gas pipe on / off valve 123 and a fuel gas flow rate control valve 124 provided on the fuel gas supply pipe 122, a combustion aid gas supply pipe 126 that guides combustion aid gas from a combustion aid gas source 125 such as a gas cylinder or air compressor to a burner 110, a combustion aid gas pipe on / off valve 127 and a combustion aid gas flow rate control valve 128 provided on the combustion aid gas supply pipe 126, and a valve drive unit 129 that drives these valves 123, 124, 127, and 128.

[0020] The light source 140 is positioned to the side of the region where the frame 113 is formed (hereinafter referred to as the frame formation region). The spectroscopic unit 150 comprises a spectrometer 151 and a photodetector 152, and is positioned opposite the light source 140 across the frame formation region. The light source 140 emits light having an emission spectrum that includes the resonance line of the target element, and this light passes through the atomic vapor in the frame formation region. The light that has passed through the atomic vapor is spectrally analyzed by the spectrometer 151, and light of a specific wavelength corresponding to the emission line (usually the resonance line) with the highest absorption by the target element is extracted. This light of a specific wavelength is introduced into the photodetector 152, and a detection signal corresponding to the amount of incident light is output. The detection signal is amplified by an amplifier (not shown) and converted into a digital signal by an A / D converter (not shown), and input to the control / processing unit 160. The analysis data processing unit 161, a functional block provided in the control / processing unit 160, calculates the absorbance for the specific wavelength light based on this digital signal and performs quantitative analysis by further performing predetermined calculation processing.

[0021] The control / processing unit 160 is centered around a computer including a CPU and memory, and performs various calculations and outputs control signals for controlling the operation of the above-mentioned parts. In addition to the analysis data processing unit 161 described above, the control / processing unit 160 is equipped with a flame failure determination unit 162, a gas supply control unit 163, and a display control unit 164 as functional blocks. Furthermore, an operation unit 171 such as a keyboard and a display unit 172 such as a liquid crystal display are connected to the control / processing unit 160, and user instructions are input to the control / processing unit 160 via the operation unit 171, and analysis results and the like are displayed on the display unit 172.

[0022] Furthermore, near the flame formation region, an OH-derived light detection optical sensor 182 is provided for detecting light originating from OH radicals (hereinafter simply referred to as OH) in the flame 113. Between the OH-derived light detection optical sensor 182 and the flame formation region, an OH-derived light transmission bandpass filter 181 is provided, which selectively transmits light having a wavelength of approximately 310 nm (these OH-derived light transmission bandpass filter 181 and OH-derived light detection optical sensor 182 correspond to the flame light detection unit in the present invention). Here, approximately 310 nm means, for example, a range of 290 nm to 330 nm, preferably 300 nm to 320 nm. It is desirable that the OH-derived light detection optical sensor 182 receives light from the entire flame 113, but it may also receive light from only a part of the flame 113. In Figure 1, for illustrative purposes, the optical sensor 182 for detecting OH-derived light is positioned diagonally above the frame 113, but the position of the optical sensor 182 for detecting OH-derived light is not limited to this (the same applies to embodiments 2 to 5 below). For example, a phototransistor can be suitably used as the optical sensor 182 for detecting OH-derived light, but it is not limited to this, and any other type of device may be used, such as a photodiode, photocell, or photomultiplier tube.

[0023] The combustion flames of hydrocarbons such as acetylene contain emission spectra derived from OH groups. While OH-derived emission spectra exist in multiple regions of the ultraviolet spectrum, the band spectrum in the 310 nm band (3064 Å System) is particularly strong, exhibits high transmittance for optical elements, and provides high detection sensitivity for general light sensors. On the other hand, ambient light such as sunlight, incandescent lamps, fluorescent lamps, or white LEDs, which act as ambient light, all exhibit low intensity in the 310 nm band. Therefore, according to the flame-type atomic absorption spectrophotometer of this embodiment, by providing an OH-derived light transmission bandpass filter 181 that selectively passes light with wavelengths around 310 nm in front of the OH-derived light detection light sensor 182, it is possible to prevent the OH-derived light detection light sensor 182 from being affected by ambient light.

[0024] Light emitted from frame 113 and passing through the OH-derived light transmission bandpass filter 181 is incident on the OH-derived light detection photosensor 182, and a detection signal corresponding to the amount of incident light is output from the OH-derived light detection photosensor 182. This detection signal is amplified by an amplifier (not shown) and converted into a digital signal by an A / D converter (not shown), and input to the extinction determination unit 162. The extinction determination unit 162 compares the intensity of this digital signal with a predetermined threshold T1, and the digital signal Strength If the threshold T1 is below the threshold, it is determined that frame 113 has been extinguished. The threshold T1 may be set before the device is delivered to the user or during the installation of the device, or it may be set by the user.

[0025] If the flame failure detection unit 162 determines that the flame 113 has gone out, the gas supply control unit 163 controls the valve drive unit 129 to close the fuel gas pipe on / off valve 123 and the auxiliary gas pipe on / off valve 127.

[0026] After closing the fuel gas pipe valve 123 and the auxiliary gas pipe valve 127, the display control unit 164 controls the display unit 172 to display a predetermined message on its screen, notifying the user that the gas supply has been stopped due to flame failure. Alternatively, a message notifying the user that the flame 113 has gone out may be displayed on the screen of the display unit 172 before or simultaneously with the closing of the fuel gas pipe valve 123 and the auxiliary gas pipe valve 127. Alternatively, the system may only close the fuel gas pipe valve 123 and the auxiliary gas pipe valve 127 without providing such notification. Furthermore, the system may be configured to only notify the user that the flame 113 has gone out without closing the fuel gas pipe valve 123 and the auxiliary gas pipe valve 127.

[0027] [Embodiment 2] Next, a frame-type atomic absorption spectrophotometer according to a second embodiment of the present invention will be described with reference to Figure 2. Figure 2 is a diagram showing the main components of the frame-type atomic absorption spectrophotometer according to this embodiment. In this embodiment, components that are the same as or corresponding to those shown in Figure 1 are denoted by the same last two digits as reference numerals, and their descriptions are omitted as appropriate.

[0028] The flame-type atomic absorption spectrophotometer according to this embodiment has the same configuration as the flame-type spectrophotometer according to the first embodiment, plus a bandpass filter 283 for transmitting C2-derived light and an optical sensor 284 for detecting C2-derived light provided near the flame formation region, and a flashback indicator determination unit 265, which is a functional block provided in the control / processing unit 260. Of these, the bandpass filter 283 for transmitting C2-derived light and the optical sensor 284 for detecting C2-derived light correspond to the swan-band light detection unit in the present invention. In addition, in this embodiment, the gas supply control unit 263 corresponds to the flashback avoidance unit in the present invention.

[0029] Normally, in the burner 210 of a flame-type atomic absorption spectrophotometer, the ratio of the combustion aid gas flow rate to the fuel gas flow rate (i.e., the air-fuel ratio) is set to be significantly smaller than the stoichiometric air-fuel ratio (the air-fuel ratio at which the combustion rate is highest when the combustion aid gas and fuel gas in the combustion gas react in sufficient quantities). However, if this air-fuel ratio approaches the stoichiometric air-fuel ratio for any reason, the combustion reaction is accelerated, and the region of the outer flame in the flame 213, where the emission spectrum originating from OH is prominent, expands, while the region of the inner flame, which includes the emission spectrum originating from C2 (diatomic carbon) in the transient stage of the reaction, decreases. In this state, if the air-fuel ratio increases further and the combustion rate becomes excessive relative to the supply rate of the combustion gas, the flame 213 can no longer remain formed outside the burner 210 and penetrates into the burner 210, causing a backfire, which is an unstable combustion. The flame-type atomic absorption spectrophotometer according to this embodiment is equipped with a function to detect signs of flashback based on the intensity ratio of the light from the outer flame and the light from the inner flame, respectively, in order to prevent such flashback from occurring.

[0030] The C2-derived emission spectrum is known to be the band spectrum of the C2-Swan system. The C2-derived light transmission bandpass filter 283 in this embodiment selectively transmits light in the wavelength band spectrum of the C2-Swan system. The C2-Swan system has multiple spectral bands in the visible light region, and emission around 517 nm is particularly prominent. Therefore, it is desirable that the C2-derived light transmission bandpass filter 283 in this embodiment selectively transmits light with wavelengths of 507 nm to 527 nm (preferably 512 nm to 522 nm). However, the transmission wavelength range by the C2-derived light transmission bandpass filter 283 is not limited to this, and it may also selectively transmit light in the wavelength range of other band spectra included in the C2-Swan system, namely 464 nm to 484 nm (preferably 469 nm to 479 nm) or 554 nm to 574 nm (preferably 559 nm to 569 nm). The C2-derived light detection optical sensor 284 is a sensor that detects light emitted from the frame 213 and passed through the C2-derived light transmission bandpass filter 283. A phototransistor can preferably be used as the C2-derived light detection optical sensor 284, but it is not limited to this, and any other type of device such as a photodiode, photocell, or photomultiplier tube may be used. Furthermore, the C2-derived light detection optical sensor 284 may receive light from the entire frame 213, but it is most effective to receive light only from the lower region of the frame 213 where C2 is localized. Note that in Figure 2, for the sake of drawing convenience, the C2-derived light detection optical sensor 284 is positioned diagonally above the frame 213, but the position of the C2-derived light detection optical sensor 284 is not limited to this.

[0031] Light emitted from the flame 213 and passing through the C2-derived light transmission bandpass filter 283 is incident on the C2-derived light detection photosensor 284, and a detection signal corresponding to the amount of incident light is output from the C2-derived light detection photosensor 284. This detection signal is amplified by an amplifier (not shown) and converted into a digital signal by an A / D converter (not shown), and input to the flashback indicator determination unit 265 (this signal is hereinafter referred to as the "C2-derived light detection signal"). On the other hand, the detection signal from the OH-derived light detection photosensor 282 is amplified and digitally converted in the same manner as in Embodiment 1, and then input to the control / processing unit 260 (this signal is hereinafter referred to as the "OH-derived light detection signal"). This OH-derived light detection signal is input to the flame extinction determination unit 262 in the same manner as in Embodiment 1 and used to determine whether or not the flame 213 has extinct, and is also input to the flashback indicator determination unit 265. The flashback indicator determination unit 265 divides the intensity of the C2-derived photodetection signal by the intensity of the OH-derived photodetection signal (i.e., it obtains the ratio of the C2-derived photodetection signal to the OH-derived photodetection signal) and compares this value with a predetermined threshold T2. If the value obtained by dividing the intensity of the C2-derived photodetection signal by the intensity of the OH-derived photodetection signal is below the threshold T2, it is determined that there is an indication of flashback. The threshold T2 may be set before the device is delivered to the user or during the installation of the device, or it may be set by the user. In this way, by determining the presence or absence of flashback indications based on the ratio of the C2-derived photodetection signal to the OH-derived photodetection signal, the intensity change of the C2-derived light due to fluctuations in the frame 213 can be canceled out, and an accurate determination can be made.

[0032] If the flashback indicator detection unit 265 determines that there are signs of flashback, the gas supply control unit 263 controls the valve drive unit 229 to reduce the air-fuel ratio in the combustion gas supplied to the burner 210. Specifically, until the flashback indicator detection unit 265 determines that there are no signs of flashback (i.e., until the ratio of the C2-derived photodetection signal to the OH-derived photodetection signal is determined to be equal to or greater than the threshold T2), the opening of the fuel gas flow rate control valve 224 is gradually increased, or the opening of the auxiliary combustion gas flow rate control valve 228 is gradually decreased, or both are done.

[0033] After adjusting the opening of the fuel gas flow control valve 224 and / or the auxiliary gas flow control valve 228 (hereinafter simply referred to as gas flow adjustment), the display control unit 264 controls the display unit 272 to display a predetermined message on its screen, notifying the user that the gas flow adjustment was performed due to signs of flashback. Alternatively, the message notifying of signs of flashback may be displayed on the screen of the display unit 272 simultaneously with or before the gas flow adjustment. Alternatively, the system may only adjust the gas flow without providing such notification. Furthermore, the system may be configured to only provide notification of signs of flashback without adjusting the gas flow.

[0034] Alternatively, if the flashback indicator detection unit 265 determines that there is a flashback, a mechanism may be provided to reduce the combustion rate of the flame 213 by reintroducing exhaust gas from the burner 210 into the burner 210, in addition to or instead of adjusting the gas flow rate as described above. A flame-type atomic absorption spectrophotometer equipped with such a mechanism (a flame-type atomic absorption spectrophotometer according to the third embodiment of the present invention) will be described below.

[0035] [Embodiment 3] Figure 3 is a diagram showing the main components of a flame-type atomic absorption spectrophotometer according to a third embodiment of the present invention. In this embodiment, components that are the same as or corresponding to those shown in Embodiment 1 or 2 are denoted by the same last two digits as reference numerals, and their descriptions are omitted as appropriate.

[0036] The flame-type atomic absorption spectrophotometer according to this embodiment has the same configuration as the flame-type spectrophotometer according to the second embodiment, plus an exhaust reintroduction pipe 315 for returning a portion of the exhaust gas generated from the burner 310 back to the burner 310, an on / off valve (hereinafter referred to as the exhaust on / off valve 316) and a flow rate control valve (hereinafter referred to as the exhaust flow rate control valve 317) provided on the exhaust reintroduction pipe 315, an exhaust valve drive unit 318 for driving these valves 316 and 317, and an exhaust reintroduction control unit 366, a functional block provided in the control / processing unit 360 for controlling the exhaust valve drive unit 318. These exhaust reintroduction pipe 315, exhaust on / off valve 316, exhaust flow rate control valve 317, exhaust valve drive unit 318, and exhaust reintroduction control unit 366 correspond to the exhaust introduction section in the present invention. The exhaust reintroduction pipe 315 is a pipe that branches off from the exhaust pipe 391, which discharges exhaust gas from the burner chamber 390, where the burner 310 is housed, to the outside, and its tip is connected to the chamber 312 of the burner 310. The burner chamber 390 and the exhaust pipe 391 are also provided in the flame-type atomic absorption spectrophotometer according to Embodiments 1 and 2, but for simplicity, they are not shown in these embodiments (the same applies to Embodiments 4 and 5 described later).

[0037] In the flame-type atomic absorption spectrophotometer according to this embodiment, when the flashback indicator detection unit 365 determines that there is a flashback, the exhaust gas reintroduction control unit 366 controls the exhaust valve drive unit 318 to recirculate the exhaust gas generated in the burner 310 into the burner 310 chamber 312. Specifically, when a flashback is determined to be present, the exhaust on / off valve 316 is first opened, and then the opening of the exhaust flow rate control valve 317 is gradually increased until the flashback indicator detection unit 365 determines that there is no longer a flashback. This suppresses the combustion speed of the flame 313 and prevents the occurrence of a flashback.

[0038] In addition, in the flame-type atomic absorption spectrophotometer according to this embodiment, when the flashback indicator detection unit 365 determines that there is a flashback, the flow rate of the auxiliary combustion gas and / or fuel gas may be adjusted in the same manner as in Embodiment 2, in addition to the exhaust gas recirculation described above. The method for determining flashback indicators and the method for adjusting the flow rate of the auxiliary combustion gas and / or fuel gas in this embodiment are the same as in Embodiment 2, so their explanation is omitted here.

[0039] [Embodiment 4] Next, a frame-type atomic absorption spectrophotometer according to a fourth embodiment of the present invention will be described with reference to Figure 4. Figure 4 is a diagram showing the main components of the frame-type atomic absorption spectrophotometer according to this embodiment. In this embodiment, components that are the same as or corresponding to those shown in Embodiment 1 are denoted by the same last two digits as reference numerals, and their descriptions are omitted as appropriate.

[0040] The flame-type atomic absorption spectrophotometer according to this embodiment has the same configuration as the flame-type spectrophotometer according to the first embodiment, plus a bandpass filter 485 for transmitting luminous flame light and a light sensor 486 for detecting luminous flame light, provided near the flame formation region, and an incomplete combustion determination unit 467, which is a functional block provided in the control / processing unit 460. Of these, the bandpass filter 485 for transmitting luminous flame light and the light sensor 486 for detecting luminous flame light correspond to the luminous flame detection unit in the present invention. In this embodiment, the gas supply control unit 463 corresponds to the incomplete combustion elimination unit in the present invention.

[0041] The luminous flame light transmission bandpass filter 485 is a bandpass filter that selectively transmits light (luminous flame) emitted from soot in the frame 413, and specifically selectively transmits all or part of the light in the wavelength range of 800 nm to 1100 nm. The luminous flame light detection light sensor 486 is a sensor that detects light emitted from the frame 413 that has passed through the luminous flame light transmission bandpass filter 485. A phototransistor can preferably be used as the luminous flame light detection light sensor 486, but it is not limited to this, and any other type of device such as a photodiode, photocell, or photomultiplier tube may be used. Furthermore, it is desirable that the luminous flame light detection light sensor 486 receives light from the entire frame 413, but it may also receive light from only a part of the frame 413. Note that in Figure 4, for illustrative purposes, the light sensor 486 for detecting luminous flame light is positioned diagonally above the frame 413, but the position in which the light sensor 486 is installed is not limited to this.

[0042] In burner 410, if the air-fuel ratio becomes too low, incomplete combustion occurs, generating soot in the flame 413. The luminous flame, emitted from soot heated to a high temperature, has a high-luminosity, thermally equilibrium continuous spectrum. The continuous spectrum generated from soot at the temperature of flame 413 (~3000K) has almost no energy in the 310nm band where the aforementioned OH emits light. Therefore, the OH-derived light detection light sensor 482, which is equipped with an OH-derived light transmission bandpass filter 481 that selectively transmits the 310nm band, is not affected by the luminous flame and can monitor whether or not flame 413 is continuing to burn.

[0043] Light emitted from the flame 413 and passing through the luminous flame light transmission bandpass filter 485 is incident on the luminous flame light detection photosensor 486, and a detection signal corresponding to the amount of incident light is output from the luminous flame light detection photosensor 486. This detection signal is amplified by an amplifier (not shown) and converted into a digital signal by an A / D converter (not shown), and input to the incomplete combustion determination unit 467 (this signal is hereinafter referred to as the "luminous flame detection signal"). On the other hand, the detection signal from the OH-derived light detection photosensor 482 is amplified and digitally converted in the same manner as in Embodiment 1, and then input to the control / processing unit 460 (this signal is hereinafter referred to as the "OH-derived light detection signal"). This OH-derived light detection signal is input to the flame extinction determination unit 462 in the same manner as in Embodiment 1 and used to determine whether or not the flame 413 has gone out, and is also input to the incomplete combustion determination unit 467. The incomplete combustion determination unit 467 divides the intensity of the flame detection signal by the intensity of the OH-derived light detection signal (i.e., it obtains the ratio of the flame detection signal to the OH-derived light detection signal) and compares this value with a predetermined threshold T4. If the value obtained by dividing the intensity of the flame detection signal by the intensity of the OH-derived light detection signal exceeds the threshold T4, it is determined that incomplete combustion is occurring in the burner 410. The threshold T4 may be set before the device is delivered to the user or during the installation of the device, or it may be set by the user. In this way, by determining whether or not incomplete combustion is occurring based on the ratio of the flame detection signal to the OH-derived light detection signal, changes in the intensity of the flame light due to fluctuations in the flame 413 can be canceled out, and an accurate determination can be made.

[0044] If the incomplete combustion determination unit 467 determines that incomplete combustion is occurring, the gas supply control unit 463 controls the valve drive unit 429 to increase the air-fuel ratio in the combustion gas supplied to the burner 410. Specifically, until the incomplete combustion determination unit 467 determines that incomplete combustion is not occurring (i.e., until the ratio of the flame detection signal to the OH-derived photodetection signal falls below the threshold), the opening of the fuel gas flow rate control valve 424 is gradually reduced, or the opening of the auxiliary combustion gas flow rate control valve 428 is gradually increased, or both are done.

[0045] After adjusting the fuel gas flow rate control valve 424 and / or the auxiliary gas flow rate control valve 428 (hereinafter simply referred to as gas flow rate adjustment), the display control unit 464 controls the display unit 472 to display a predetermined message on its screen, thereby notifying the user that the gas flow rate has been adjusted due to incomplete combustion. Alternatively, the message notifying the user of incomplete combustion may be displayed on the display unit 472 screen simultaneously with or before the gas flow rate adjustment. Alternatively, the system may only adjust the gas flow rate without providing such notification. Furthermore, the system may only notify the user that incomplete combustion has occurred without adjusting the gas flow rate.

[0046] [Embodiment 5] Next, a flame-type atomic absorption spectrophotometer according to a fifth embodiment of the present invention will be described with reference to Figure 5. Figure 5 is a diagram showing the main components of the flame-type atomic absorption spectrophotometer according to this embodiment. In this embodiment, components that are the same as or corresponding to those shown in Embodiment 1 are denoted by the same two reference numerals, and their descriptions are omitted as appropriate.

[0047] The flame-type atomic absorption spectrophotometer according to this embodiment has the same configuration as the flame-type spectrophotometer according to the first embodiment, plus a burner head imaging unit 588 for imaging the burner head 514, a bandpass filter 587 for transmitting luminous flame light positioned between the burner head imaging unit 588 and the burner head 514, and a soot deposition determination unit 568, which is a functional block provided in the control / processing unit 560.

[0048] When the combustion state of the flame 513 in the burner 510 becomes temporarily or continuously unstable, soot is generated and accumulates on the burner head 514. The soot accumulated on the burner head 514 impairs the stability of the flame and therefore needs to be removed appropriately. The flame-type atomic absorption spectrophotometer according to this embodiment is equipped with a function to monitor the accumulation of soot on the burner head 514.

[0049] The burner head imaging unit 588 is an image sensor equipped with multiple photodetectors arranged in a two-dimensional matrix. It is desirable that the burner head imaging unit 588 be positioned to image the entire burner head 514, but it is not limited to this, and may be positioned to image only the area around the slit opening where soot tends to accumulate. In Figure 5, for the sake of drawing, the burner head imaging unit 588 is positioned diagonally above the frame 513, but the position in which the burner head imaging unit 588 is provided is not limited to this. The luminous flame light transmission bandpass filter 587 is a bandpass filter that selectively transmits light (luminous flame) emitted from soot heated to a high temperature, and selectively transmits light in the same wavelength range as the luminous flame light transmission bandpass filter 485 in Embodiment 4.

[0050] In the flame-type atomic absorption spectrophotometer according to this embodiment, the detection signals from each photodetector in the burner head imaging unit 588 are amplified by an amplifier (not shown) and converted into digital signals by an A / D converter (not shown), and then input to the soot deposition determination unit 568 of the control / processing unit 560. On the other hand, the detection signal from the OH-derived light detection photosensor 582 is amplified and digitally converted in the same manner as in Embodiment 1, and then input to the control / processing unit 560 (this signal is hereinafter referred to as the "OH-derived light detection signal"). This OH-derived light detection signal is input to the flame extinction determination unit 562 in the same manner as in Embodiment 1 and used to determine whether or not the flame 513 has gone out, and is also input to the soot deposition determination unit 568. The soot deposition determination unit 568 divides the intensity of the detection signals from each photodetector by the intensity of the OH-derived light detection signal (i.e., it obtains the ratio of the detection signals from each photodetector to the intensity of the OH-derived light detection signal), and compares this value with a predetermined threshold T5. The threshold T5 and the predetermined number N may be set before the device is delivered to the user or during the installation of the device, or they may be set by the user. If the number of photodetectors among the multiple photodetectors provided in the burner head imaging unit 588 whose detection signal intensity divided by the intensity of the OH-derived photodetector signal exceeds the threshold is greater than or equal to the predetermined number N (where N is an integer of 1 or more), the soot deposition determination unit 568 determines that soot has accumulated on the burner head 514. In this way, by determining soot deposition based on the ratio of the detection signal from each photodetector to the intensity of the OH-derived photodetector signal, changes in the intensity of the luminous flame light due to fluctuations in the flame 513 can be canceled out, and an accurate determination can be made.

[0051] If the soot accumulation determination unit 568 determines that soot has accumulated on the burner head 514, the display control unit 564 controls the display unit 572 to display a predetermined message on its screen to notify the user that soot has accumulated on the burner head 514. These display control unit 564 and display unit 572 correspond to the notification unit in the present invention. In addition to or instead of the above message, an image representing the area on the burner head 514 where soot has accumulated may be displayed on the screen of the display unit 572. In this case, the soot accumulation determination unit 568 identifies one or more photodetectors from the plurality of photodetectors whose detection signal divided by the OH-derived photodetector signal exceeds the threshold T5, and identifies the flame emission position on the burner head 514 (i.e., the position where soot has accumulated) based on the position of the photodetector on the burner head imaging unit 588. Then, under the control of the display control unit 564, a previously captured image of the burner head (or an illustration representing the burner head) is displayed on the screen of the display unit 572, and the soot accumulation area on the burner head 514 is indicated by adding a specific color to the area corresponding to the soot accumulation location on the image, or by adding a predetermined shape (for example, a line surrounding the area). In this case, the soot accumulation determination unit 568, the display control unit 564, and the display unit 572 correspond to the soot accumulation area presentation unit in the present invention.

[0052] Although specific examples of embodiments for carrying out the present invention have been described above, the present invention is not limited to the above embodiments, and modifications are permitted as appropriate within the scope of the spirit of the present invention.

[0053] For example, the flame-type atomic absorption spectrophotometers according to embodiments 1 to 5 described above constantly monitor for any abnormalities related to the stability of the flame's combustion state, such as flame extinction, signs of flashback, incomplete combustion, or soot accumulation, after the flame 113 has been lit, and notify the user when an abnormality is detected. Alternatively, the system may determine whether the aforementioned abnormality has occurred at a timing specified by the user or at a preset timing, and notify the user of the determination result regardless of the outcome.

[0054] Furthermore, in embodiments 1 to 4 described above, a bandpass filter (i.e., bandpass filters 181, 281, 381, 481 for transmitting OH-derived light, bandpass filters 283, 383 for transmitting C2-derived light, or bandpass filter 485 for transmitting luminous flame light) and an optical sensor for detecting the light that has passed through it (i.e., optical sensors 182, 282, 382, ​​482 for detecting OH-derived light, and optical sensors 284, 384 for detecting C2-derived light, or optical sensor 486 for detecting luminous flame light) are provided near the flame formation region. However, instead of providing these bandpass filters and optical sensors, the spectrometers 151, 251, 351, 451 and photodetectors 152, 252, 352, 452 provided in the spectroscopic units 150, 250, 350, 450 may also perform the roles of these bandpass filters and optical sensors. In this case, from the light incident on the spectroscopic units 150, 250, 350, and 450, wavelengths similar to those transmitted through the OH-derived light transmission bandpass filters 181, 281, 381, and 481 are selected by the spectrometers 151, 251, 351, and 451 and guided to the photodetectors 152, 252, 352, and 452. The detection signals (OH-derived light detection signals) from the photodetectors 152, 252, 352, and 452 at that time are input to the extinction determination units 162, 262, 362, and 462, thereby determining whether or not the combustion of the flames 113, 213, 313, and 413 is being maintained (i.e., whether or not extinction has occurred). Furthermore, from the light incident on the spectroscopic units 250 and 350, wavelengths similar to those transmitted through the C2-derived light transmission bandpass filters 283 and 383 are selected by the spectrometers 251 and 351 and guided to the photodetectors 252 and 352. The detection signals from the photodetectors 252 and 352 (C2-derived light detection signals) and the OH-derived light detection signals are then input to the flashback indicator determination units 265 and 365 to determine whether or not there are signs of flashback.Alternatively, the spectrometer 451 selects a wavelength from the light incident on the spectroscopic unit 450 that is similar to the wavelength transmitted through the aforementioned flame light transmission bandpass filter 485, and guides it to the photodetector 452. The detection signal from the photodetector 452 (flame detection signal) and the OH-derived light detection signal are then input to the incomplete combustion determination unit 467 to determine whether or not incomplete combustion has occurred. In these cases, the photodetection for determining the presence or absence of the above-mentioned abnormalities is performed at a different time than the photodetection for sample analysis. Specifically, for example, after lighting flames 113, 213, 313, and 413, and without supplying sample from sample supply units 130, 230, 330, and 430 to burners 110, 210, 310, and 410, a determination is made as to whether flames 113, 213, 313, and 413 have gone out. If it is determined that flames 113, 213, 313, and 413 have not gone out (i.e., combustion of flames 113, 213, 313, and 413 is maintained), a determination is made as to whether there are signs of flashback, or whether incomplete combustion is occurring, or both. If, as a result of all the determinations, no abnormalities have been found, then sample is supplied from sample supply units 130, 230, 330, and 430 to burners 110, 210, 310, and 410 to perform sample analysis.

[0055] Furthermore, the flame-type atomic absorption spectrophotometers according to embodiments 2 to 5 may not include the flame failure detection units 162, 262, 362, and 462, and may use the OH-derived photodetection signal only to determine whether there are signs of flashback, whether incomplete combustion has occurred, or whether there is soot accumulation.

[0056] Furthermore, the flame-type atomic absorption spectrophotometer according to the present invention may be equipped with two or more functions from among the following: a function to determine whether or not there are signs of flashback; a function to determine whether or not incomplete combustion is occurring; and a function to determine whether or not soot is accumulating. [Aspect] It will be obvious to those skilled in the art that the exemplary embodiments described above are specific examples of the following embodiments.

[0057] (Paragraph 1) The flame-type atomic absorption spectrophotometer relating to Paragraph 1 is, A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit for detecting light emitted from the flame, A flame extinguishing determination unit determines that the flame has extinguished when the intensity of the light detected by the flame light detection unit is lower than a predetermined threshold, It has, The flame light detection unit selectively detects light with a wavelength between 290 nm and 330 nm.

[0058] According to the flame-type atomic absorption spectrophotometer described in paragraph 1, it is possible to reliably determine whether or not a flame is continuing to burn normally without being affected by ambient light.

[0059] (Paragraph 2) The flame-type atomic absorption spectrophotometer relating to Paragraph 2 is, A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit that detects light emitted from the flame, and selectively detects light with a wavelength of 290 nm to 330 nm, A swan-band light detection unit selectively detects C2 swan-band light from the light emitted from the flame, A flashback indicator determination unit determines that there is a flashback when the ratio of the light intensity detected by the swan-band light detection unit to the light intensity detected by the flame light detection unit falls below a predetermined threshold, It possesses the following characteristics.

[0060] According to the flame-type atomic absorption spectrophotometer described in paragraph 2, it becomes possible to detect the occurrence of flashback before it happens.

[0061] (Article 3) The flame-type atomic absorption spectrophotometer relating to Article 3 is a flame-type atomic absorption spectrophotometer relating to Article 2, further comprising: A gas supply unit that supplies the fuel gas and the combustion aid gas to the burner, A flashback avoidance unit controls the gas supply unit to reduce the ratio of the flow rate of the auxiliary gas to the flow rate of the fuel gas when the flashback indication determination unit determines that there is a flashback indication, It possesses the following characteristics.

[0062] (Article 4) The flame-type atomic absorption spectrophotometer relating to Article 4 is a flame-type atomic absorption spectrophotometer relating to Article 2 or Article 3, further comprising: When the flashback indicator detection unit determines that there is a flashback, an exhaust introduction unit is provided to introduce a portion of the exhaust gas generated from the burner into the burner. It possesses the following characteristics.

[0063] According to the flame-type atomic absorption spectrophotometer described in paragraph 3 or 4, the occurrence of flashback can be automatically avoided.

[0064] (Article 5) The flame-type atomic absorption spectrophotometer relating to Article 5 is: A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit that detects light emitted from the flame, and selectively detects light with a wavelength of 290 nm to 330 nm, A luminous flame detection unit selectively detects light with wavelengths between 800 nm and 1100 nm from the light emitted from the flame, An incomplete combustion determination unit determines that incomplete combustion is occurring when the ratio of the light intensity detected by the flame detection unit to the light intensity detected by the flame light detection unit exceeds a predetermined threshold, It possesses the following characteristics.

[0065] According to the flame-type atomic absorption spectrophotometer described in paragraph 5, it becomes possible to reliably detect the occurrence of incomplete combustion.

[0066] (Paragraph 6) The flame-type atomic absorption spectrophotometer relating to Paragraph 6 is a flame-type atomic absorption spectrophotometer relating to Paragraph 5, further comprising: A gas supply unit that supplies the fuel gas and the combustion aid gas to the burner, If the incomplete combustion determination unit determines that incomplete combustion is occurring, the incomplete combustion elimination unit controls the gas supply unit to increase the ratio of the flow rate of the auxiliary combustion gas to the flow rate of the fuel gas, It possesses the following characteristics.

[0067] According to the flame-type atomic absorption spectrophotometer described in paragraph 6, incomplete combustion can be automatically eliminated.

[0068] (Paragraph 7) The flame-type atomic absorption spectrophotometer relating to Paragraph 7 is: A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A flame light detection unit that detects light emitted from the flame, and selectively detects light with a wavelength of 290 nm to 330 nm, A bandpass filter that selectively transmits light with wavelengths between 800nm ​​and 1100nm, It has a plurality of photodetectors arranged in two dimensions, flame An image sensor that receives light emitted from and passing through the bandpass filter, A soot accumulation determination unit determines that soot has accumulated on the burner if, for each of the plurality of photodetectors, the ratio of the light intensity detected by the photodetector to the light intensity detected by the flame light detection unit is determined, and if the ratio of the plurality of photodetectors exceeds a predetermined threshold for a predetermined number or more of them, it is determined that soot has accumulated on the burner. When the soot accumulation determination unit determines that soot has accumulated on the burner, a notification unit notifies the user accordingly. It possesses the following characteristics.

[0069] According to the flame-type atomic absorption spectrophotometer described in paragraph 7, users can reliably understand the state of soot accumulation in the burner.

[0070] (Paragraph 8) The flame atomic absorption spectrophotometer relating to Paragraph 8 is a flame atomic absorption spectrophotometer relating to Paragraph 7, further comprising: A soot deposit region presentation unit presents to the user the region on the burner corresponding to the region where the ratio of the multiple photodetectors exceeds a predetermined threshold, as a region where soot has accumulated. It possesses the following characteristics.

[0071] According to the flame-type atomic absorption spectrophotometer described in paragraph 8, the user can easily identify the area on the burner where soot is accumulating. [Explanation of symbols]

[0072] 110... Burner 120... Gas supply department 130...Sample supply unit 140...Light source 150... Spectroscopic Unit 151...Spectrometer 152... Photodetector 160...Control / Processing Unit 162... Disappearance detection unit 163...Gas Supply Control Unit 164...Display Control Unit 172...Display section 181...Bandpass filter for transmitting OH-derived light 182...Optical sensor for detecting OH-derived light

Claims

1. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A burner chamber is provided to house the aforementioned burner and to allow ambient light from the outside to enter the interior, A light detection unit for detecting light inside the burner room, A flame extinguishing determination unit determines that the flame has gone out when the intensity of the light detected by the light detection unit is lower than a predetermined threshold, It has, The aforementioned light detection unit comprises a detector and a selection means configured to selectively guide light with a wavelength of 290 nm to 330 nm to the detector, and selectively detects the flame light from the flame and the ambient light. Flame-type atomic absorption spectrophotometer.

2. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A burner chamber is provided to house the aforementioned burner and to allow ambient light from the outside to enter the interior, A light detection unit for detecting light inside the burner chamber comprises a detector and a selection means configured to selectively guide light with a wavelength of 290 nm to 330 nm to the detector, and the light detection unit selectively detects the flame light from the flame and the ambient light. Of the light in the aforementioned burner room, C ２ A swan-band light detection unit that selectively detects swan-band light, A flashback indicator determination unit determines that there is a flashback when the ratio of the light intensity detected by the swan-band light detection unit to the light intensity detected by the light detection unit falls below a predetermined threshold, A flame-type atomic absorption spectrophotometer.

3. Furthermore, A gas supply unit that supplies the fuel gas and the combustion aid gas to the burner, A flashback avoidance unit controls the gas supply unit to reduce the ratio of the flow rate of the auxiliary gas to the flow rate of the fuel gas when the flashback indication determination unit determines that there is a flashback indication, A flame-type atomic absorption spectrophotometer according to claim 2, having the features described above.

4. Furthermore, When the flashback indicator detection unit determines that there is a flashback, an exhaust introduction unit is provided to introduce a portion of the exhaust gas generated from the burner into the burner. A flame-type atomic absorption spectrophotometer according to claim 2, having the features described above.

5. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A burner chamber is provided to house the aforementioned burner and to allow ambient light from the outside to enter the interior, A light detection unit for detecting light inside the burner chamber comprises a detector and a selection means configured to selectively guide light with a wavelength of 290 nm to 330 nm to the detector, and the light detection unit selectively detects the flame light from among the flame light emitted from the flame, the luminous flame light emitted from the soot generated in the flame, and the ambient light. A flame detection unit selectively detects light with wavelengths between 800 nm and 1100 nm from the light inside the burner chamber, An incomplete combustion determination unit determines that incomplete combustion is occurring when the ratio of the light intensity detected by the flame detection unit to the light intensity detected by the light detection unit exceeds a predetermined threshold, A flame-type atomic absorption spectrophotometer.

6. Furthermore, A gas supply unit that supplies the fuel gas and the combustion aid gas to the burner, If the incomplete combustion determination unit determines that incomplete combustion is occurring, the incomplete combustion elimination unit controls the gas supply unit to increase the ratio of the flow rate of the auxiliary combustion gas to the flow rate of the fuel gas, A flame-type atomic absorption spectrophotometer according to claim 5, having the following features.

7. A burner that forms a flame by burning a mixture of fuel gas and combustion aid gas with an atomized sample liquid, A burner chamber is provided to house the aforementioned burner and to allow ambient light from the outside to enter the interior, A light detection unit for detecting light inside the burner chamber comprises a detector and a selection means configured to selectively guide light with a wavelength of 290 nm to 330 nm to the detector, and the light detection unit selectively detects the flame light from among the flame light emitted from the flame, the luminous flame light emitted from the soot generated in the flame, and the ambient light. A bandpass filter that selectively transmits light with wavelengths between 800 nm and 1100 nm, An image sensor having multiple photodetectors arranged in two dimensions, which receives light that has passed through the bandpass filter, A soot accumulation determination unit determines that soot has accumulated on the burner if, for each of the plurality of photodetectors, the ratio of the light intensity detected by the photodetector to the light intensity detected by the photodetector, and if the ratio of the plurality of photodetectors exceeds a predetermined threshold for a predetermined number or more of them, When the soot accumulation determination unit determines that soot has accumulated on the burner, a notification unit notifies the user accordingly. A flame-type atomic absorption spectrophotometer.

8. Furthermore, A soot deposit region presentation unit presents to the user the region on the burner corresponding to the region where the ratio of the multiple photodetectors exceeds a predetermined threshold, as a region where soot has accumulated. A flame-type atomic absorption spectrophotometer according to claim 7, having the following features.

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