JP2002202289A - Two-wavelength photoionization mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-wavelength photoionization mass spectrometer capable of directly analyzing dioxins in exhaust gas. SOLUTION: This mass spectrometer is equipped with a sample introduction means 15 for introducing continuously exhaust gas 13 from a gas duct 12 into a vacuum chamber 11 as leakage molecular beams 14, a first laser irradiation means comprising a wavelength fixed laser 18a and a wavelength variable laser 18b for irradiating first pulse laser beams 17 into the introduced leakage molecular beams 14 through a condensing lens 16, a second laser irradiation means comprising the wavelength fixed laser 18a for irradiating the condensing position of the first laser beams 17 with second pulse laser beams 19 in the spatially overlapped state without the aid of the condensing lens, and a time-of- flight mass spectrometer 22 equipped with an ion detector 21 for analyzing molecular ion 20 generated by being ionized by irradiating the leakage molecular beams 14 with the first laser beams 17 and the second laser beams 19 in the spatially and temporally overlapped state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various incinerators such as municipal waste incinerators, industrial waste incinerators, sludge incinerators, etc.
A dual-wavelength photoionization mass spectrometer that directly analyzes, in real time, dioxins in exhaust gas discharged from a pyrolysis furnace, a melting furnace, etc. without time delay, and controls combustion in the furnace based on the analysis results of the analyzer. The present invention relates to a combustion control system.

[0002]

BACKGROUND ART Dioxin has a high toxicity in a trace amount, and development of a highly sensitive analytical method is desired. Therefore, it is conceivable to apply a laser analysis method that enables high-sensitivity analysis.
In recent years, it has been proposed that by combining the supersonic jet method and the resonance-sensitized multiphoton ionization method, it is possible to measure the spectrum of a chlorine-substituted product which is a kind of dioxins (C. Weickhardt, R. Zimmermann, U.
Bosel, EWSchlag, Papid Commun, Mass Spectron, 7,198
(1993)).

[0003]

However, the above-mentioned proposal is a method for analyzing a gas in which the spectrum is simplified by jetting a gas sample into a vacuum and instantaneously cooling the gas sample to near absolute zero. The detection limit of dioxin and its derivatives (hereinafter referred to as “dioxins”) is about ppb, and the actual dioxin analysis requires 5 to 6 digits of concentration, which takes time and labor for detection. is there.

In the conventional manual analysis, it takes one to two months for the analysis result to be obtained. The daily generation of dioxins in the incinerator is measured, and the combustion control is performed as needed. It is difficult to drive to meet the appropriate regulation values.

Further, the sample molecules are irradiated with laser light,
A method for detecting sample molecules by selectively ionizing them has been previously proposed (see JP-A-8-222181).

An example of this measuring device will be described with reference to FIG. As shown in FIG. 7, for example, an exhaust gas 03 is sucked from a flue 01 of an incinerator or the like via a sampling probe 02 and a nozzle 05 having a pulse valve for forming a supersonic jet stream 04 using the exhaust gas as a sample gas is provided. A jetting means for jetting into the vacuum chamber 06 and irradiating the jetted supersonic jet stream 04 with a laser beam 07 to form a molecular ion 08 of a homologue of dioxins in a resonance-sensitized ionization process. It comprises laser irradiation means 09 comprising a fixed wavelength laser 09a and a variable wavelength laser 09b, and a time-of-flight mass spectrometer 011 provided with an ion detector 010 for analyzing dioxins of generated molecular ions 08. is there. In FIG. 7, reference numeral 012 denotes a pulse driver, reference numeral 13 denotes a pulse delay circuit, reference numeral 014 denotes a digital oscilloscope, reference numeral 015 denotes a mirror, reference numeral 016 denotes a condenser lens, and reference numeral 017 denotes a laser introduction window.

[0007] However, the laser light is applied for nanoseconds (1).
0 ^-9 seconds) When a pulsed laser, the spectral width is narrow, it is necessary to use a tunable laser, with the device configuration becomes large-scale, as the number of chlorine atoms increases, the so-called heavy atom effect As a result, crossover occurs in the triplet system and the excitation lifetime is shortened. As a result, no ion signal is observed and sufficient sensitivity cannot be obtained.

[0008] In addition, when sample molecules are selectively ionized, it is impossible to detect other than the target sample, and it is impossible to perform real tile analysis of the present homologues of dioxins in exhaust gas. There's a problem. In the case of selective ionization, laser light of nanoseconds having good detection sensitivity is used, but as described above, direct analysis of dioxins is impossible. That is, since only one specific isomer can be measured in the proposal,
When measuring other substances, it is necessary to perform a wavelength sweep, and when performing this wavelength sweep, it is necessary to make adjustments to change the wavelength each time. Real-time analysis of is impossible. In the proposal, the selective ionization has a wavelength of several pm.
Since the detection peak does not appear due to the change of (picometer), the wavelength must be calibrated at all times, and when detecting dioxins adjacent to the incinerator in which the packaging industry is operated, vibration is prevented. Therefore, there is a problem that large-scale seismic measures are required, and measurement of dioxins is interrupted every time the wavelength is calibrated.

Further, the laser light is applied to a femtosecond (10
^(-15 seconds) In the case of using a pulse laser, the influence of the heavy atom effect is reduced, but the spectrum width is wide, so that non-selective detection is possible, but there is a problem that the photon utilization rate is poor.

[0010] Therefore, it has been proposed to improve the ionization efficiency by using a second wavelength that ionizes molecules in the excited triplet.

An example of this measuring device will be described with reference to FIG. Note that the same members as those in the apparatus configuration of FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 8, the two-wavelength ionization mass spectrometer includes a wavelength-fixed laser 09a for irradiating a first laser beam 07 into the jetted supersonic jet stream 04, and a wavelength-tunable laser 09a. It further includes a laser irradiating means 09 composed of a laser 09b, a laser irradiating means 21 composed of a fixed wavelength laser 021a for irradiating the second laser light 020 and a wavelength variable laser 021b, and a prism 023 for adjusting the optical path length of the laser 020. It is.

Here, the first wavelength and the second wavelength must irradiate the sample with a laser temporally and spatially. However, the pulse delay circuit 013 alone cannot perform control of 5 picoseconds or less. Therefore, it is necessary to provide the prism 022 that can arbitrarily adjust the optical path length of the second wavelength, and there is a problem that the device configuration becomes complicated.

Further, in a supersonic jet, the first wavelength needs to be stabilized with an accuracy of several pm because the spectrum width of the molecule is narrow, and it is difficult to make a practical measurement method. There's a problem.

Further, in order to monitor the combustion control of the incinerator, the influence of vibration and the like cannot be avoided due to the provision of the measuring means in the vicinity of the incinerator. However, the apparatus shown in FIG. This is particularly problematic for continuous measurement over a long period of time. That is, although it is difficult to apply the optical axis alignment of one wavelength to an actual machine, it takes more time to align the optical axis of two wavelengths.

On the other hand, it has been conventionally proposed to estimate the concentration of dioxins by measuring the CO concentration and control the combustion in an incinerator or the like.
It has been confirmed that when the concentration is as high as 0 ppm, there is a correlation between the CO concentration and the dioxin concentration. However, as shown in FIG. 6, when the CO concentration is in a low concentration region of 50 ppm or less, there is no concentration correlation between the dioxin concentration and the CO concentration.
There is a problem that effective combustion control that prevents generation of dioxins cannot be performed. In particular, in recent years, as a result of the establishment of low CO concentration combustion control, it has been demanded to appropriately prevent the generation of dioxins by instantaneous measurement of dioxins directly measured.

Furthermore, when measuring dioxin precursors such as chlorobenzene (CB) and dichlorobenzene (DCB), which are conventionally considered to have a concentration correlation with dioxins, dioxins are not directly measured. Therefore, the in-incinerator state cannot be determined properly, and real-time analysis in exhaust gas is demanded, and it is desired to use the result for combustion control.

Further, when measuring the concentration correlated substance of dioxins, as described above, since a specific kind of substance is measured in the selective ionization, the deviation of the optical axis of the laser beam and the sampling pipe are not measured. When dioxins are actually detected due to other factors such as clogging but cannot be detected, there is a problem that the concentration of dioxins cannot be measured properly. In order to solve this problem, it is necessary to provide two measuring devices and perform the analysis while referring to them. However, there is a problem that the analyzing device becomes large.

[0019]

Means for Solving the Problems A first method for solving the above problems is described below.
The invention of the present invention is a sample introducing means for introducing a sample into a vacuum vessel, a laser irradiating means for irradiating the introduced sample with laser beams having different wavelengths with a spatial overlap, and a molecular ion generated by the laser irradiation. A time-of-flight mass spectrometer for performing the analysis, wherein the irradiation of the laser light having the different wavelength is performed while the first laser light is irradiated while the laser light is narrowed down by the condenser lens, and the second laser light is irradiated. Is characterized in that the laser light is irradiated while being narrowed down without using a condenser lens.

According to a second aspect, in the first aspect, the intensity of the first laser light is higher than the intensity of the second laser light.

According to a third aspect, in the first aspect, the first laser is a tunable laser and the second laser is a fixed wavelength laser.

A fourth invention is characterized in that, in the first invention, the sample introduction means is a pulse valve for introducing the sample molecules into a pulse of a supersonic jet flow.

According to a fifth aspect, in the first aspect, the sample introduction means is a capillary column for continuously introducing the sample molecules so as to leak out.

In a sixth aspect based on the fifth aspect, the sample introduction means is a capillary column having a pore size of 2 μm.
It is characterized by being 50 to 530 μm.

In a seventh aspect based on the fifth aspect, the distance between the laser irradiation position of the leaked molecular beam introduced from the capillary column and the tip of the capillary column is 1 mm or less. .

An eighth invention is characterized in that, in the first invention, the sample is exhaust gas from an incinerator, a pyrolysis furnace, a melting furnace or the like.

According to a ninth aspect, in the first aspect, the time-of-flight mass spectrometer is a reflectron type mass spectrometer.

According to a tenth aspect of the present invention, there is provided a sampling means for directly collecting combustion gas containing dioxins in exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, or the like, and a real-time sampling of the collected gas containing dioxins. A dual-wavelength photoionization mass spectrometer according to any one of the first to ninth aspects of the present invention for analyzing is provided, and dioxins in combustion gas are directly analyzed.

According to an eleventh aspect of the present invention, a burned substance is charged into a furnace such as an incinerator, a pyrolysis furnace, a melting furnace, etc., so that the amount of heat generated by the combustion is kept constant and the generation of harmful gases such as dioxins is suppressed. A dual-wavelength photoionization mass spectrometer according to any one of the first to ninth, which can instantaneously measure dioxins in exhaust gas from an incinerator, a pyrolysis furnace, a melting furnace, etc. Air control means for detecting the concentration of dioxins without time delay, and changing the amount of combustion air in accordance with the detected concentration of dioxins.

According to a twelfth aspect, in the eleventh aspect,
The combustion air control means controls the air amount and oxygen concentration of one or both of the primary combustion air and the secondary combustion air.

According to a thirteenth aspect, in the eleventh aspect,
The emission control of the dioxins is controlled by any one of a furnace temperature, a furnace gas convection time, a furnace stirring force, or a combination thereof.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic diagram of a two-wavelength photoionization mass spectrometer according to the present embodiment. As shown in FIG.
The photoionization mass spectrometer according to the present embodiment includes a sample introduction unit 15 that leaks exhaust gas 13 from a flue 12 into a vacuum chamber 11 and continuously introduces it as a molecular beam 14.
And the condensing lens 1 in the introduced leaked molecular beam 14.
A first laser irradiating means comprising a fixed wavelength laser 18a and a variable wavelength laser 18b for irradiating the first pulsed laser light 17 through 6 and a condensing position of the first laser light 17 with a spatial overlap. A second laser irradiating means composed of a fixed wavelength laser 18a for irradiating the second pulse laser light 19 without passing through a condenser lens, and the first laser light 17 and the second laser light 19 are spatially and temporally It is provided with a time-of-flight mass spectrometer 22 having an ion detector 21 for irradiating the leaked molecular beam 14 with partial overlap and ionizing it and analyzing the generated molecular ion 20. In FIG. 1, 23 to 26 are electrodes, 27 is a mirror,
Reference numeral 28 denotes a digital oscilloscope and 29 denotes a laser introduction window.

Here, in the present embodiment, the same fixed wavelength laser 18a is used as the laser irradiation means, but a different laser device may be used.

Although no ion trap is provided in this embodiment, an ion trap may be provided if necessary.
You may make it capture only what is aimed. Alternatively, the filter may be used as a filter for removing substances lighter than benzene.

Here, when the sample introduction means 15 such as a capillary column is used, the temperature of the laser irradiation part becomes 100 K or more, so the leaked molecular beam is ionized without cooling, and the broadened molecular beam is cooled. A spectrum can be obtained.

The sample introducing means 15 may be any one that continuously supplies molecular beams. However, a capillary column is preferable because it is made of quartz, so that adhesion of organic molecules hardly occurs.

The pore diameter is desirably 250 to 530 μm, preferably about 320 μm. This is because if the pore diameter of the capillary column is out of the above range, a good leaked molecular beam 14 will not be obtained. The material of the capillary column is preferably a non-dielectric material such as quartz.

The distance between the laser irradiation position of the leaked molecular beam 14 introduced from the capillary column 15 and the tip of the capillary column 15 is 1 mm or less, preferably 0.1 mm.
It is desirable to set it to about 3 mm. This is because it is preferable that the distance between the tip of the capillary column and the laser be closer to each other because the ionization efficiency of the laser is high, but if the distance is too close, dielectric breakdown may occur at the tip of the capillary column, and the width of the capillary may be extremely large. Gives a broad mass spectrum of In this case, the mass resolution is greatly reduced, and it is difficult to apply the method to the analysis of a real gas containing a large number of components. Therefore, it is preferable to be as close as possible at a distance that is not affected by the laser irradiation.

It should be noted that the present invention is not limited to the leak-out molecular beam type means using a capillary column or the like as the sample introduction means, but it is also possible to use, for example, a pulse valve using a supersonic jet flow. In this case, a pulse driver and a pulse delay circuit are separately required as shown in FIG. 7 to adjust the pulse valve.

The laser pulse wavelength is 240 to 2
Preferably it is 70 nm. This is because the dioxins and the dioxin precursor can be ionized by setting the wavelength range.

The pulse width usable in the present invention is preferably a pulse width on the order of nanoseconds.

The apparatus of the present invention can be used to analyze any sample as long as it is an organic compound. In particular, dioxin in exhaust gas can be used for measurement of exhaust gas from incinerators, pyrolysis furnaces, melting furnaces and the like. It is suitable from the viewpoint of real-time analysis of a kind.

In the present invention, it is preferable to use a reflectron type mass spectrometer 19 from the viewpoint of improving mass resolution. This means that ions of the same mass, with higher (smaller) translational energies, fly longer (short) effectively by folding deeper (shallower) into the electric field upon folding. Therefore, ions having different energies can be converged on the detector at the same time.

Here, the difference between the measurement of the spectrum with the two-wavelength ions due to the focusing of the first laser beam and the non-focusing of the second laser beam according to the present invention will be described.

When the first laser beam 17 is condensed by the condensing lens 16 for about 100 μs, as shown in FIG. 2A, the laser beam applied to the molecule has a sharp shape. 2nd irradiation without using one condenser lens
In the case of the laser beam 19, the molecular beam 14
When the two molecules overlap each other spatially and temporally, an overlap 31 of both beams always occurs, resulting in a high ionization rate. On the other hand, when the first laser light 07 and the second laser light 020 shown in FIG. 8 of the related art are condensed together by the condensing lens 016, the optical axes are completely aligned. 2B, the beam overlaps 32 as shown in FIG. 2B. If the optical axis is slightly deviated, a spatial shift occurs, and FIG.
The beam overlap 33 as shown in FIG. 4 indicates that it is difficult to improve the ionization rate.

Further, the intensity of the first laser light is set to be higher than the intensity of the second laser light. This is to prevent one-wavelength ionization from occurring only with the second laser light. Therefore, when the second laser beam is irradiated, the laser beam intensity (photon density) is reduced so that only a signal of the background level can be obtained.

Regarding the necessity of adjusting the laser irradiation timing of the second laser beam, it is not necessary to make strict adjustment because the lifetime of the triplet state is as long as about μs.
Therefore, high sensitivity can be achieved by directly irradiating a fifth harmonic of a YAG laser used for excitation of a dye laser used for a wavelength tunable laser, for example, without using a conventional pulse delay circuit.

Next, the outline of identifying dioxin isomers using a two-wavelength ionization mass spectrometer will be described with reference to FIG.

FIG. 3 shows an excited state by laser irradiation.
The ions are ionized by reaching the ionization level from the ground state (S ₀ ).

Here, in the case of a molecule having a size of about benzene or monochlorobenzene, a laser having a wavelength ν ₁ capable of exciting the excited state S ₁ is irradiated, and subsequently, the molecule in the excited state S ₁ has a wavelength ν ₁ . It is ionized by absorbing laser light. On the other hand, in the case of dioxins, the absorption band is shifted to a longer wavelength range, and even if the molecule is excited by the laser wavelength ν ₁ that can excite the excited state S ₁ , the laser light of the wavelength ν ₁ is emitted by 2 nm.
If photon absorption is not performed, it will not ionize. Furthermore, since dioxins have a chlorine atom, the excited state S
_The energy of the molecule in ₁ is quickly transferred to another excited state T ₁ by the internal heavy atom effect. Another excited state T
_Since the lifetime of ₁ is about μs, which is longer than the lifetime of the excited state S ₁ , molecules can be ionized by irradiating a laser beam having a wavelength ν ₃ for ionizing molecules in another excited state T ₁ . T ₁ is at a lower energy than S ₁ , and wavelength ν ₃ must necessarily be shorter than wavelength ν ₁ . However, since the ionization level is in a continuous state, the wavelength ν ₃ does not need to be generated by a tunable laser,
For example, a fifth harmonic (wavelength: 213 nm) of a YAG laser or the like can be used. In addition, dioxin isomers having different chlorine numbers include those having excitation wavelengths close to each other,
This can be identified by the difference in the mass numbers.

Since the absorption cross section that transitions from T ₁ to the ionization level is larger than the cross section that transitions from the ground state S ₀ to the excited state S ₁ , the laser beam having the wavelength ν ₁ is condensed by the condenser lens. However, the laser light having the wavelength ν ₃ does not need to be focused by the focusing lens. Conversely, if a laser beam having a wavelength ν ₃ is condensed, there is a possibility that the highly excited state S ₂ or an even higher excited state may be excited, and selective excitation of the isomer becomes impossible.

As described above, in the present invention, by using a dual wavelength ionization method in which one laser beam is not focused and a time-of-flight mass spectroscopy (TOFMS), a homologue of dioxins can be obtained. It can be easily measured.

Here, in the present invention, the filter 41 interposed at the tip of the sampling tube 40 shown in FIG. 1 is preferably a ceramic filter which can withstand high temperatures, and prevents the sampling tube 40 from being clogged. Therefore, it is preferable to use a filter having a dust removal rate of 99% or more.

Further, in order to prevent the filter 41 of the sampling tube 40 from being clogged, a reverse cleaning means for performing reverse cleaning by, for example, purging with nitrogen gas or the like is provided. Since this clogging state uses a laser beam with a wide spectrum width and a plurality of organic molecules other than dioxins are simultaneously ionized, the organic molecules other than the dioxins (such as benzene) are used as indices, By monitoring the change in the signal intensity of the organic molecule, clogging can be monitored. Alternatively, regardless of the change in the signal intensity, the nitrogen gas may be purged every time a predetermined time elapses to perform the reverse cleaning.

Further, since the tip of the sampling pipe 40 is exposed to the high temperature of the combustion exhaust gas in the furnace or the flue, there is no risk of resynthesis of dioxins in this portion. Therefore, the distribution itself of the homolog of dioxins in the furnace or the flue can be directly collected.

A protective means 42 is provided around the collection tube 40.
, And the temperature is maintained so that the temperature of the collection tube is 120 to 200 ° C. If the temperature is lower than 120 ° C., the combustion gas 13 contains a large amount of moisture.
This is to prevent the aggregation, and to prevent the re-synthesis of the dioxins at a high temperature of 200 ° C. or more.

The exhaust gas suction speed is preferably about 0.5 to 1.0 liter / minute. This is to prevent submicron unit dust in the exhaust gas from adhering to the piping.

As the above laser, a semiconductor laser, an excimer laser, a third harmonic of a titanium sapphire laser, or the like can be used.

In the analysis of homologues of dioxins, in the case of samples having different molecular weights, it is possible to immediately discriminate them from the mass spectrum, and even in the case of the same molecular weight, the wavelength dependence of the ion signal of the target mass number is obtained. By detecting in advance, the isomer can be distinguished.

[0061]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below.

A sample gas (monochlorobenzene 50 ppm, nitrogen balance) was introduced into a vacuum chamber using a capillary column having an inner diameter of 320 μm and a length of 2 m. The laser for ionization is a YAG excitation / wavelength variable dye laser having a pulse wavelength of 269.8 nm, a pulse width of 10 ns, and a pulse energy of 500 μJ / pulse. The first laser beam was applied to a point within 1 mm downstream of the capillary column with a quartz lens having a focal length of 70 cm. As the second laser light, a fifth harmonic (wavelength: 213 nm) of the wavelength YAG laser was used, and irradiation was performed without using a condenser lens from the optical window on the opposite side of the optical window for irradiating the first laser light. The generated ions were detected by a time-of-flight mass spectrometer.

In this embodiment, since the leaked molecular beam is used, unlike the supersonic jet flow, the molecule is not cooled, so that the spectrum width of the molecule is expanded to 200 pm or more, and the utilization efficiency of laser photons is increased by one digit or more. It is possible to realize the simplification of the laser irradiation timing by improving the irradiation of the second laser beam and targeting the triplet,
Real-time detection becomes possible with practical sensitivity.

[Second Embodiment] Next, an embodiment of a furnace control method using the measuring apparatus of the present invention will be described. FIG. 4 is a schematic diagram of the combustion control system. As shown in FIG. 4, the control system according to the present embodiment includes an incinerator 51.
In the combustion control system in the incinerator, which keeps the calorific value generated by combustion constant and also suppresses the generation of harmful gases such as dioxins, the combustion control system such as an incinerator, a pyrolysis furnace, a melting furnace, etc. Dioxin analyzer 53 capable of instantaneously measuring dioxins in furnace 51
And a combustion air control means 54 for detecting the concentration of dioxins without delay and changing the amount of combustion air according to the detected concentration of dioxins. Here, the incinerator 51 in the present embodiment is a fluidized bed furnace,
It has a configuration having a fluidized bed 55 at the bottom. On the downstream side of the fluidized bed 55, an ash chute 56 for transporting ash after burning the combustibles 52 to a predetermined position is arranged.
A forced blower 59 is connected to the fluidized bed 55 via a pipe 58 having a primary combustion air amount control valve 57 interposed therebetween.

The primary combustion air is supplied from the lower part of the fluidized bed 55 to an arbitrary position. A forced blower 62 is connected to a lower portion of the fluidized-bed furnace 51 via a pipe 61 having a secondary combustion air amount control valve 60 interposed therebetween. Here, the secondary combustion air functions to burn the combustion gas generated in the primary combustion in the upper part of the fluidized bed furnace 51.

On the lower side wall of the fluidized bed furnace 51, there is provided a combustion material supply hopper 63 for introducing combustion materials such as municipal solid waste into the fluidized bed 55. A feeder 64 is provided below the hopper 63 and driven by a motor to push out the combustion products 52 to the fluidized bed 55. This feeder 6
The combustion products 52 sent by the gas turbine 4 are gasified in the fluidized bed 55 and burned in the fluidized bed furnace 51 above the fluidized bed 55.

In the upper stage of the fluidized bed furnace 51, a fluidized bed furnace 5 is provided.
Boiler 65 for cooling the high-temperature combustion gas obtained by burning in 1, exhaust gas treatment facility 6 for removing toxic gas and particulate matter
6. An induction blower 67 for inducing exhaust gas and a chimney 68 for discharging exhaust gas to the atmosphere are sequentially connected. Also,
A spraying device 6 for spraying slaked lime, activated carbon and the like into the equipment 66 as needed near the upper part of the exhaust gas treatment equipment 66.
9 are arranged.

A dioxin analyzer 53 is provided above the fluidized-bed furnace 51 as a measuring means capable of instantaneously measuring the concentration of dioxins in the combustion gas in the furnace. The analyzer 53 has the configuration shown in FIG. 1, and the measurement information is electrically connected to the controller 71.
The controller 71 controls the primary combustion air amount control valve 5
7 and secondary combustion air amount control valve 60 and oxygen amount adjustment valve 73
And an auxiliary combustion burner 72. Further, the controller 71 receives information 80 on the boiler evaporation amount and temperature measurement information 81, and sends signals to a control unit 82 for controlling the supply feeder, a control unit 83 for controlling the stoker, and an oxygen supply amount unit 84. Sending and controlling.

The combustion control is based on the primary combustion air amount control or the secondary combustion air amount control according to the concentration of dioxins.
The control of the oxygen concentration of the combustion air or all of them may be performed as needed. Further, the control may be performed by any one of the furnace temperature, the furnace gas convection time, the furnace stirring force, or a combination thereof.

When the controller 71 includes a predictive control means, it is possible to predict a change in the concentration of dioxins from time-series data based on the result of measurement by the dioxin analyzer 53. The prediction control means includes, for example, a fuzzy controller that controls a baseline (average value) and a chaos controller that suppresses generation of dioxin concentration.

Here, the chaos controller predicts the concentration of dioxins at a certain point in time from the time-series data based on the measurement results obtained by the dioxins analyzer 53, and if it predicts that a peak will occur, the secondary combustion air An operation amount that increases the amount is calculated. The fuzzy controller calculates the difference between the measurement result of exhaust gas and the set value of dioxin concentration,
An operation amount that makes it zero is calculated. The primary combustion air amount control valve 57 and the secondary air amount control valve 60 are operated based on the operation amount obtained by combining the operation amount obtained by the chaos controller and the operation amount by the fuzzy controller 29 to reduce the concentration of dioxins in the plant. Control.

An example of the combustion control operation using the chaos theory of the combustion control device having such a configuration is shown below, but the combustion control of the present invention is not limited to the following. First, combustion products 52 such as municipal waste are charged from a combustion product supply hopper 63 into a fluidized bed 55 of a fluidized bed furnace 51. The input combustion material is gasified in the fluidized bed 55 and burns in the fluidized bed furnace 51.
Then, the exhaust gas is cooled by a boiler 65, and harmful gases and particulate matter are removed by an exhaust gas treatment facility 66 such as a filtration type dust collector. The exhaust gas is induced by an induction blower 67 and discharged into the atmosphere from a chimney 68. On the other hand, in the upper part of the fluidized-bed furnace 51, the dioxin concentration is instantaneously measured by the dioxin analyzer 53, and a signal based on the measurement result is sent to a prediction control device (not shown). After performing the fluctuation prediction based on the chaos theory, a signal from the prediction control device is sent to the controller 71, and the opening degrees of the primary combustion air amount control valve 57 and the secondary fuel air amount control valve 60 are adjusted to adjust the primary combustion air amount. Adjust the secondary combustion air amount.

As described above, the dioxin analyzer 53 is attached to the upper part of the fluidized-bed furnace 51, the dioxin concentration in the combustion gas in the furnace is measured in real time, and the prediction controller using the chaos theory is obtained from the time series data. And the primary combustion air amount and the secondary combustion air amount at the lower side of the fluidized-bed furnace 51 are adjusted based on the prediction, so that the peak of the dioxin concentration is reduced to a predetermined value or less. The amount of dioxins generated can be reduced.

The concentration of dioxins at the furnace outlet of a newly constructed furnace is targeted at 0.5 ng-TEQ / Nm ² , and it is necessary to measure the concentration. 0.1ng-
The concentrations of monochlorobenzene (precursor of dioxins) and pentachlorodibenzofuran (P ₅ CDF) corresponding to the dioxin concentration expected to be TEQ / Nm ² are 20 ng / Nm ³ and 0.5 ng / Nm ³ , respectively. The use of the device of the invention makes it possible to detect this concentration.

The use of the dioxin analyzer of the present invention enables real-time detection of the concentration of dioxins in the furnace and in the flue gas with a time delay of about 5 to 20 seconds. Therefore, as shown in FIG. 5, the measurement is performed in such a manner that the signal B detected by the measuring instrument follows the peak A of the dioxins (DXN) in the furnace, and
The improvement in the concentration of dioxins can be measured, and by performing the above control immediately, the peak C in which the generation of dioxins is controlled is detected.

The place where the exhaust gas is collected is not limited to the inside of the furnace as described above. Can be.

In particular, by installing the dioxin analyzer 53 between the boiler 65 and the exhaust gas treatment equipment 66, if no dioxins are generated in the furnace, the dioxin precursor is resynthesized downstream of the furnace. By this, it can be determined that dioxins have been generated, and by spraying activated carbon as an adsorbent from the spraying device 69, dioxins in exhaust gas can be adsorbed and discharge to the outside can be prevented.

Instead of spraying activated carbon, an auxiliary burner 72, which is a sub-combustion means, may be installed in the flue to burn off the generated dioxins.

[0079]

As described above, according to the first aspect of the present invention, the sample introducing means for introducing the sample into the vacuum vessel and the laser light having different wavelengths are irradiated on the introduced sample with spatial overlap. And a time-of-flight mass spectrometer for analyzing molecular ions generated by the laser irradiation. The laser beam is radiated while narrowing down, and the second laser light is radiated while narrowing down the laser beam without using a focusing lens. Therefore, a focusing lens is used for the first laser beam using the focusing lens. By irradiating the laser light that is not used, the second laser light is surely irradiated, and the ionization efficiency is improved.

According to a second aspect, in the first aspect, since the intensity of the first laser light is higher than the intensity of the second laser light, one-wavelength ionization by the second laser light does not occur. .

According to a third aspect, in the first aspect, since the first laser is a tunable laser and the second laser is a fixed-wavelength laser, an arbitrary wavelength can be selected for a target sample. Can be.

According to a fourth aspect of the present invention, in the first aspect, since the sample introduction means is a pulse valve for introducing sample molecules in a pulse shape of a supersonic jet stream, the sample can be selectively ionized.

According to a fifth aspect of the present invention, in the first aspect, the sample introduction means is a capillary column for continuously introducing the sample molecules so as to leak out, so that the molecules not cooled by the leaked molecular beam are absorbed. The line width is improved, and the ionization efficiency is improved.

According to a sixth aspect, in the first aspect, the sample introduction means is a capillary column having a pore size of 2 μm.
Since it is 50 to 530 μm, a leaked molecular beam is suitable.

According to a seventh aspect, in the third aspect, the distance between the laser irradiation position of the leaked molecular beam introduced from the capillary column and the tip of the capillary column is 1 mm or less. Efficiency is improved.

According to an eighth aspect, in the first aspect, since the sample is an exhaust gas from an incinerator, a pyrolysis furnace, a melting furnace, or the like, real-time analysis of dioxins and the like in the exhaust gas becomes possible.

According to a ninth aspect, in the first aspect, since the time-of-flight mass spectrometer is a reflectron mass spectrometer, detection sensitivity can be improved.

The tenth aspect of the present invention is directed to a sampling means for directly collecting combustion gas containing dioxins in exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, and the like, and a real-time sampling of the collected gas containing dioxins. Since the apparatus is provided with a two-wavelength photoionization mass spectrometer for analysis, it is possible to directly analyze homologs of dioxins in combustion gas in real time.

According to an eleventh aspect of the present invention, a burned material is put into a furnace such as an incinerator, a pyrolysis furnace, a melting furnace, etc., so that the amount of heat generated by the combustion is kept constant and the generation of harmful gases such as dioxins is suppressed. A combustion control system for an incinerator that includes a dual-wavelength photoionization mass spectrometer capable of instantaneously measuring dioxins in exhaust gas from an incinerator, a pyrolysis furnace, a melting furnace, and the like, and combustion air control means. Since the concentration of dioxins is detected without a time delay and the amount of combustion air is changed according to the detected concentration of dioxins, it is possible to perform combustion while preventing generation of dioxins.

The twelfth invention is the eleventh invention, wherein
The combustion air control means controls the air amount and oxygen concentration of one or both of the primary combustion air and the secondary combustion air.

A thirteenth invention is the eleventh invention, wherein
Since the emission control of the dioxins is controlled by the furnace temperature, the gas convection time in the furnace, or the stirring power in the furnace or a combination thereof, it is possible to perform combustion without generating dioxins according to the combustion state. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a two-wavelength photoionization mass spectrometer according to the present embodiment.

FIG. 2 is a diagram showing an overlapping state of laser light beams that irradiate molecules.

FIG. 3 is a diagram showing an excited state of a molecule.

FIG. 4 is a schematic diagram of a combustion control system.

FIG. 5 is a diagram showing before and after combustion control.

FIG. 6 is a correlation diagram between CO and dioxins.

FIG. 7 is a schematic diagram of a conventional photoionization mass spectrometer.

FIG. 8 is a schematic diagram of a conventional two-wavelength photoionization mass spectrometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Vacuum chamber 12 Flue 13 Exhaust gas 14 Leakage molecular beam 15 Condensing lens 17 First pulse laser beam 18a Wavelength fixed laser 18b Wavelength variable laser 19 Second pulse laser beam 20 Molecular ion 21 Ion detector 22 Flight time type Mass spectrometer 23 to 26 Electrode 27 Mirror 28 Digital oscilloscope 29 Laser introduction window 51 Furnace 52 Combustion material 53 Dioxins analyzer 54 Combustion air control means 55 Fluidized bed 56 Ash chute 57 Primary combustion air amount control valve 58 Pipe 59 Push-in blower Reference Signs List 60 Secondary combustion air amount control valve 61 Piping 62 Push-in blower 63 Combustion material supply hopper 64 Extruding feeder 65 Boiler 66 Exhaust gas treatment equipment 67 Induction blower 68 Chimney 69 Spray device 71 Controller 72 Burning burner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 49/40 H01J 49/40

Claims (13)

[Claims] 1. A sample introducing means for introducing a sample into a vacuum vessel, a laser irradiating means for irradiating the introduced sample with laser beams having different wavelengths with spatial overlap, and molecular ions generated by the laser irradiation A time-of-flight mass spectrometer that performs the analysis of the first laser light, the first laser light is irradiated while the laser light is narrowed down by a condenser lens, and the second laser A two-wavelength photoionization mass spectrometer characterized in that light is irradiated while focusing a laser beam without using a condenser lens. 2. The two-wavelength photoionization mass spectrometer according to claim 1, wherein the intensity of the first laser light is higher than the intensity of the second laser light. 3. The dual-wavelength photoionization mass spectrometer according to claim 1, wherein the first laser is a tunable laser, and the second laser is a fixed-wavelength laser. 4. The dual-wavelength photoionization mass spectrometer according to claim 1, wherein said sample introduction means is a pulse valve for introducing sample molecules in a pulse shape of a supersonic jet stream. 5. The dual-wavelength photoionization mass spectrometer according to claim 1, wherein the sample introduction means is a capillary column that continuously introduces sample molecules so as to leak out. 6. The dual-wavelength photoionization mass spectrometer according to claim 5, wherein the sample introduction means is a capillary column having a pore size of 250 to 530 μm. 7. The dual-wavelength photoionization mass according to claim 5, wherein the distance between the laser irradiation position of the leaked molecular beam introduced from the capillary column and the tip of the capillary column is 1 mm or less. Analysis equipment. 8. The two-wavelength photoionization mass spectrometer according to claim 1, wherein the sample is an exhaust gas from an incinerator, a pyrolysis furnace, a melting furnace, or the like. 9. The two-wavelength photoionization mass spectrometer according to claim 1, wherein the time-of-flight mass spectrometer is a reflectron type mass spectrometer. 10. A sampling means for directly collecting combustion gas containing dioxins in exhaust gas discharged from an incinerator, a pyrolysis furnace, a melting furnace, etc., and analyzing the collected gas containing dioxins in real time. A dioxins analyzer, comprising: the dual-wavelength photoionization mass spectrometer according to any one of 1 to 9, wherein the dioxins in the combustion gas are directly analyzed. 11. An incinerator in which incinerators, pyrolysis furnaces, melting furnaces, and the like are charged with combustion products to maintain a constant amount of heat generated by combustion and suppress generation of harmful gases such as dioxins. The dual-wavelength photoionization mass spectrometer and combustion air according to any one of claims 1 to 9, wherein a dioxin in exhaust gas from an incinerator, a pyrolysis furnace, a melting furnace, or the like can be instantaneously measured in the combustion control system. A combustion control system for an incinerator, comprising: control means for detecting the concentration of dioxins without time delay, and changing the amount of combustion air in accordance with the detected concentration of dioxins. 12. The combustion control in an incinerator according to claim 11, wherein the control means for the combustion air controls the air amount and oxygen concentration of one or both of the primary combustion air and the secondary combustion air. system. 13. The combustion in an incinerator according to claim 11, wherein the emission control of the dioxins is controlled by any one of a furnace temperature, a furnace gas convection time, a furnace stirring force, or a combination thereof. Control system.