JP2003057221A - Method and instrument of continuously analyzing exhaust gas from incinerator for hazardous air pollutant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide gas chromatography used as an exhaust gas monitor for incinerator, that measures the total amount (TVOC) of volatile organic compounds which are noxious gas-containing bands in batch and having boiling points of about 50-260 deg.C. SOLUTION: By a method and instrument for continuously analyzing exhaust gas from incinerator for hazardous air pollutants, an exhaust gas collected from the exhaust gas flue 2 of an incinerator 1 is introduced to a TVOC- monitoring system composed of a flow passage change-over valve 18, a weighing tube 19, a hydrocarbon-based gas separation column 20, and a hydrocarbon detector 21 via a sample heating conduit tube 3 heated to a temperature, at which the moisture in the exhaust gas will not condense. Then a fixed amount of the exhaust gas collected in the weighing tube 19 is supplied to the column 20 as a sample gas, and C1-C5 hydrocarbon components are eluted. After the components are eluted, the column 20 is back-flushed and hydrocarbon components of C6 or higher are sent out in reverse and are detected as a batch peak by means of the detector 21.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a continuous analysis method and apparatus for harmful air pollutants in exhaust gas from an incinerator.

[0002]

2. Description of the Related Art In recent years, air pollution caused by chemical substances has been regarded as a problem that has a direct or indirect adverse effect on the human body, and there is a problem with the furnace capacity or discharge from an incinerator depending on the type of incineration. It is desired to build a steady and reliable monitoring system for harmful gases, especially dioxins, as the most serious environmental pollution. These harmful gas components are considered to be volatile organic compounds (VOC), semi-volatile organic compounds, etc., but for dioxin, precursors such as chlorobenzene and chlorophenol are produced in the process of their production. Is said.

Conventionally, in measuring these harmful substances and dioxins or their precursors, a gas chromatograph-mass spectrometer (GC-MS) method has been mainly used.
It is intended to measure the peak of the component itself,
Troublesome pretreatment was also required. However, in this type of application, which belongs to a trace amount analysis, this method generally requires an expensive apparatus configuration completed by sequentially connecting the sampling means, pretreatment means, metering means, and gas chromatograph-mass spectrometer, The operation was complicated and required a high degree of skill.

On the other hand, focusing on the relationship between volatile organic compounds and harmfulness, the total amount of volatile organic compounds (TVOC) having a boiling point of about 50 ° C. to 260 ° C. contains various harmful gases and is a dioxin precursor. It is said to be one indicator of whether or not it contains (chlorobenzene, chlorophenol, etc.).

[0005]

DISCLOSURE OF THE INVENTION The present invention, as described above, has a boiling point of about 50 ° C., which is considered to be a band containing harmful gas.
By establishing a gas chromatographic method for collectively measuring the total amount of volatile organic compounds (TVOC) at 260 ° C., it is intended to provide a simple and highly sensitive incinerator exhaust gas monitoring method.

The present invention is also intended to provide a device for effectively carrying out the above-mentioned method, particularly, a device configuration for introducing and measuring harmful components from exhaust gas of an incinerator into a measuring system without being lost together with condensed water. To do. This is because the temperature at the sampling point of the incinerator is generally 200-400 ° C.
Since it becomes a sample gas that is high in temperature and contains a lot of water, if it is rapidly cooled by a sampling conduit, it may condense water and carry away a large amount of the organic gas to be measured. Is.

[0007]

In order to solve the above problems, the present invention provides a sample heating conduit in which exhaust gas collected from an exhaust gas flue of an incinerator is heated to a temperature at which water in the exhaust gas does not condense. Via a flow path switching valve, a metering tube, a hydrocarbon gas separation column, and a hydrocarbon detector into a TVOC monitor system, and a fixed amount of exhaust gas sampled in the metering tube as a sample gas to the separation column. After supplying and eluting C1 to C5 hydrocarbon components, the separation column is backflushed, and C6 or more hydrocarbon components are collectively sent back and detected as a batch peak by the hydrocarbon detector. It constitutes a continuous analysis method for harmful air pollutants in incinerator exhaust gas.

According to the above constitution, C having a boiling point of 50 ° C. or lower is used.
When the column is backflushed after the hydrocarbon components of 1 to C5 are rapidly eluted, the hydrocarbon components of C6 or higher including the dioxin precursor are absorbed by the carrier gas from the outlet side of the column and the adsorption time difference to the column is increased. The total amount (TVOC) can be rapidly and clearly detected because the eluates are offset from each other and are collectively eluted from the inlet side.

Further, according to the above-mentioned second problem, in order to collect and measure an exhaust gas sample from the incinerator exhaust gas flue without loss of harmful gas components, the present invention is installed by being pulled out from the incinerator exhaust gas flue. , A sample heating conduit that is heated to a temperature at which water in the exhaust gas does not condense,
A carrier gas source, a sample pretreatment unit having a constant temperature chamber for heating a suction pump for actively sucking exhaust gas from the sample heating conduit, a filter for blocking soot and dust in the exhaust gas to about 60 ° C., A TVOC monitor system comprising a flow path switching valve, a metering tube, a sample outlet, a hydrocarbon-based gas separation column, and a hydrocarbon detector,
The flow path switching valve includes: a) a metering flow path for filling the measuring tube with the exhaust gas sample introduced from the sample pretreatment unit; and b) a carrier for supplying the exhaust gas sample filling the measuring tube from a carrier gas source. A sample introduction flow path that supports the gas and sends it to a separation column, and introduces the column elution component into the hydrocarbon detector to detect the C1 to C5 hydrocarbon components, and c) the carrier gas to the separation column. On the other hand, a backflush flow path for collectively detecting a hydrocarbon component of C6 or more by supplying in a direction opposite to the sample introduction flow path and sending a backflush flow based on the flow into the hydrocarbon detector. A continuous analyzer for harmful air pollutants in exhaust gas from an incinerator, which occupies a position where it is selectively formed.

The sample heating conduit described above has a temperature of about 60-80 ° C.
Since about 10% of the water vapor contained in the exhaust gas is not condensed, the harmful gas component is not washed away.

Further, the flow path switching valve in the above-mentioned structure has an OFF position for forming the metering flow path and the backflush flow path simultaneously and in parallel, and an ON position for forming the sample introduction flow path.
With the structure that selectively occupies the position and the position, the continuous monitoring operation of the exhaust gas can be easily performed around the ON / OFF alternate reversal of the switching valve.

As the hydrocarbon detector, a hydrogen flame ionization detector, a photoionization detector, a mass spectrometer or the like can be adopted.

[0013]

1 is a schematic diagram showing the overall structure for carrying out the method of the present invention. The sample gas heating conduit 3 is installed so as to be pulled out from an appropriate position in the chimney 2 of the incinerator 1, and the end thereof is the exhaust gas TVOC of the present invention.
Connect to monitor 4. The TVOC monitor 4 has a sample pretreatment unit 5 directly connected to the end of the sample gas heating conduit 3.
And a TVOC analyzer 6 and a recorder 7 that form the monitor body.
It consists of In this overall structure, the sample gas heating conduit 3 preferably covers the conduit main body (pipe) with a heating or heat insulating jacket in order to prevent condensation of water vapor in the flue gas that is positively sucked from the sample pretreatment unit 5. The inside of the conduit is maintained at about 60 to 80 ° C. (The switching valve 18, the measuring pipe 19, the column row 20, and the detector 21 which constitute the TVOC analyzer 6 will be described later with reference to FIG. 3.)

FIG. 2 is a flow chart showing the structure of the sample pretreatment section 5. From the upstream end connected to the heating conduit 3, TVO
A line filter 8, a suction pump 9, a three-way solenoid valve 10, in the same section 5 to the downstream end connected to the C analyzer 6.
Guard filter 11, flow meter 12, and two-way solenoid valve 13
Are sequentially arranged and housed in a constant temperature bath whose temperature is maintained at about 60 to 70 ° C. as a whole. Line filter 8
Is a solid content such as soot and dust in the sample gas and has a particle diameter of about 5 to 10 μm, and then causes the suction pump 9 to suck the gas. The suction pump 9 and the three-way solenoid valve 1
The bypass line 14 is drawn out from between 0 and 0, and unnecessary sample gas can be discharged from the bypass outlet 14a.

The three-way solenoid valve 10 has a sample gas supplied from the suction pump 9 and a standard gas (for example, n-hexane) supplied from the TVOC standard gas introduction line 15.
Is a switching valve for selectively introducing and to the downstream guard filter 11, and the standard gas introduction line 15 has an inlet 15a.
Further, the standard gas is introduced through the flow path resistance CT formed of a capillary tube. The guard filter 11 is a filter that further filters the sample gas supplied from the suction pump 9 with a sieve mesh size (particle diameter) of about 1 to 2 μm. It is led to the second heating conduit 16 via 12 and the two-way solenoid valve 13. The heating conduit 16 is surrounded by a heating jacket at about 60 to 80 ° C, and the TVOC analyzer 6 (Fig. 3) connected to the heating conduit 16 is housed in a thermostatic chamber and maintained at about 60 to 70 ° C.

The channel structure of the TVOC analyzer 6 is as shown in FIG. The main body of the TVOC analyzer 6 is a thermostatic chamber 17
A ten-way switching valve 18 housed inside, a metering pipe 19, a column array 20 including first to third columns 20a, 20b, and 20c, a hydrocarbon detector, in this case, a flame ionization detector 21. Composed of and. In addition to the flame ionization detector, a photoionization detector or a mass spectrometer is adopted depending on the tendency of the components of the measurement object or the purpose of analysis. The ten-way switching valve 18 has a total of 10 left and right five valves formed on both side walls 22a and 22b of the valve cylinder.
By switching the mutual connection of the individual flow path ports, the normal elution (C1 to C5 elution) system and the backflush (C6 or more batch return) system of the column are selectively formed.

In the left side wall 22a of the ten-way switching valve 18, the upper flow path port is connected to the analysis gas flow path 23, and the second flow path from the top is connected to the upper flow path port of the right side wall 22b.
The third flow path is the column row outlet flow path 25, the fourth flow path is the carrier gas supply flow path 26, and the fifth (lowermost) flow path is the metering pipe inlet flow path 27. It is connected. On the other hand, in the right side wall 22b, the upper end channel is the above-mentioned connecting channel 24, the second channel from the top is the column row inlet channel 28, and the third channel is the metering tube outlet channel 29,
The fourth channel is connected to the sample gas outlet channel 30, and the fifth channel (lowermost) channel is connected to the sample gas inlet channel 31.

A capillary 32 is inserted in the middle of the analysis gas flow path 23, and the other end is a flame ionization detector 21.
Connected to the analysis gas inlet of the. The sample gas inlet channel 31 is connected to the second heating conduit 16 extending from the pretreatment unit 5 via the guard filter 33, receives the sample gas from the second heating conduit 16, and the sample gas outlet channel 30 analyzes the sample gas outlet channel 30. It is connected to the sample gas outlet 34 of the total 6 and is adapted to discharge the sample gas to the outside of the system. The carrier gas supply passage 26 receives an inert gas of helium or the like at an appropriate pressure from the carrier gas inlet 35 of the analyzer 6 through the pressure regulating valve 35, the pressure gauge 36, and the purification pipe 37 filled with the molecular sieve. , Is sent to the ten-way switching valve 18.

There are a hydrogen gas supply line 38 to the hydrogen flame ionization detector 21 and an auxiliary combustion gas (clean air) supply line 39 to the hydrogen flame ionization detector 21 as flow paths not involved in the ten-way switching valve 18. First and second compressed air lines 40 and 41 are installed for driving the valve 18. In the hydrogen gas supply line 38, from the hydrogen gas inlet 42 of the analyzer 6, an electromagnetic opening / closing valve 43, a buffer pipe 44, a pressure regulating valve 45,
Pressure gauge 46, purification tube 4 filled with molecular sieve
7, and hydrogen gas is supplied to the hydrogen flame ionization detector 21 via the capillary 48. Further, the auxiliary combustion gas supply line 39 is branched from an air branch port 50 formed at a position immediately downstream of the compressed air inlet 49 in the analyzer 6.
The dehydrated / purified compressed air is supplied to the hydrogen flame ionization detector 21 via the pressure regulating valve 51, the dehydration pipe 52, the capillary 53, and the purification furnace 54.

The main flow line from the air branch port 50 communicates with a four-way solenoid valve 55, from which first and second compressed air lines 40, 41 are branched. When the four-way solenoid valve 55 allows compressed air to pass through the first line 40 and the second line 41 leads to the air outlet 56 through the four-way solenoid valve 55, the ten-way switching valve 18 causes the diaphragm that drives the valve piston 57. The compressed air supplied to the upper chamber drives the diaphragm, and hence the valve piston 57, downward (ON position) from the OFF position in FIG. Therefore, from the second line 41 communicating with the lower chamber of the diaphragm, surplus air accompanying the contraction of the chamber is discharged from the air outlet 56. On the contrary, when the four-way solenoid valve 55 allows the compressed air to flow to the second line 41 and the first line 40 to the air outlet 56 via the four-way solenoid valve 55, the ten-way switching valve 18 causes the valve piston 57 to move. It is clear to return to the original OFF position.

[0021]

EXAMPLE FIG. 4 is a time chart of 12 minutes in total showing a timing example of the TVOC analyzer in the incinerator exhaust gas continuous analysis system of the present invention shown in FIGS.
The system operation of each step will be described with reference to FIGS. 5A and 5B in which the flow path configuration in the thermostat 17 of the analyzer 6 is enlarged.

Step (1) is atmospheric pressure equilibrium (AP), and the exhaust passage 58 of the hydrogen flame ionization detector 21 is set at the OFF position of the ten-way switching valve 18 shown in FIG. 3 (and FIG. 5B). Thus, the communication flow path system including the detector 21 before that is in a state of being in equilibrium with the atmospheric pressure. Step (2)
Is the sample introduction stage, and the ten-way switching valve 18 expands the diaphragm upper chamber 59 by the compressed air from the first compressed air line 40, as shown in FIG.
It becomes the ON position which lowered the level of 7.

In FIG. 5A, the carrier gas supply channel 2
The carrier gas flowing into 6 enters the lower metering pipe inlet channel 27 through a new “U” -shaped valve channel formed in the lower left part of the ten-way switching valve 18, and further exists in the metering pipe 19. The sample gas to be discharged is extruded and guided to the column row 20 through the column row inlet flow path 28, each hydrocarbon component in the sample gas is adsorbed, and the one having a short retention time is eluted,
Column outlet channel 25, "K" in the upper left part of the valve 18
The hydrogen flame ionization detector 21 is sequentially supplied through the V-shaped valve flow path, the connection flow path 24, and the analysis gas flow path 23. As a result, the O2 to C5 peaks of the chromatogram shown in the upper right section of the time chart of FIG. 4 are detected.

The baseline setting of the detector output is
As an auto-zero (AZ) step (4), the time until the first sharp O2 peak appears after entering the sample introduction step (2), and the level of the flat base signal continuously observed is used. This is an operation for automatically setting the zero base, and is performed every 12-minute analysis cycle.

Next, in the backflush step (3), the ten-way switching valve 18 moves to the second compressed air line 41.
The diaphragm lower chamber 60 is expanded by the compressed air from and the level of the piston 57 is raised to the OFF position. At this position, the carrier gas flowing into the carrier gas supply passage 26 enters the upper column outlet passage 25 through the “U” shaped valve passage formed at the lower left side of the ten-way switching valve 18, and enters the column outlet passage 25. C remaining in each column through row 22 in reverse
6 or more components are backflowed (backflushed), and the column row inlet flow passage 28, the “U” -shaped valve flow passage at the upper right side of the ten-way switching valve 18, the connection flow passage 24, the analysis gas flow passage 23
Through the hydrogen flame ionization detector 21 at once. This is the TVOC peak portion of the chromatogram shown in the upper right section of the time chart of FIG.

The TVOC peak portion is designed to appear in the middle portion of the backflushing time zone, and the detector output is input to an integrating amplifier (not shown) in order to perform its quantification, that is, area calculation (integration). The TVOC gate step (5) to be performed is set in a time period that can sufficiently cover the first half of the backflush time period. The measured value (integrated value) thus obtained is obtained at the start of the next analysis cycle after the end of the backflush time period (hence,
It is held in the measurement value holding step (6) executed by the time (at the start of the next atmospheric pressure equilibrium), and is displayed and recorded during that time.

On the other hand, in parallel with the backflush time zone of step (3), sample gas measurement for the next analysis cycle is performed. That is, in FIG. 5B, the exhaust gas sample from the incinerator that has flowed from the heating conduit into the sample gas inlet passage 31 passes through the lower linear valve passage of the ten-way switching valve 18 to reach the metering pipe inlet passage 27, Measuring pipe 19
After replacing (measuring) the inside with the sample gas, the excess amount passes through the measuring pipe outlet flow passage 29, the lower right "U" shaped valve flow passage of the ten-way switching valve 18, and the sample gas outlet flow passage 30. Will be discharged.

FIGS. 6 to 8 are chromatograms showing the results of testing how accurate and reproducible the system of the present invention having the above-described operation form is. First, in FIG. 6, a considerable amount of n-pentane (nP) is adopted as a component corresponding to the so-called "C1 to C5" peak, and 5.551 mg / Nm ³ is selected as a component corresponding to TVOC of "C6" or more. Is a graph when n-hexane (nH) is adopted, and after sampling at the point S on the time axis scale 10, "C1 to C5" around 10.5
A sharp nP peak corresponding to the component was obtained, and the column was backflushed by 11 to obtain a significant nH peak in a range centered at 11.4.

FIG. 7 is a graph measured by mixing a small amount of n-hexadecane (nHD) in an air sample. In this case as well, after obtaining a sharp peak corresponding to the "C1 to C5" components, backflushing is performed to obtain a sufficiently quantifiable nH.
The D peak was obtained. In the atmosphere, "C1-C"
It is considered that almost all methane is detected as a component corresponding to the 5 "component, and such a sharp peak is formed.

FIG. 8 shows the air in the laboratory of the inventor,
TVO of "C6" or more, as well as "C1-C5" compatible components
Even if the C component is not actively mixed with the specific substance,
It was measured in the same manner as in. Even in such a case, the peak of the component corresponding to "C1 to C5" is obtained.

As described above, according to the system of the present invention, one in which a considerable amount of TVOC-compatible component (n-hexane 5.551 mg / Nm ³ ) is positively mixed (FIG. 6), to some extent (trace amount). The corresponding peak areas become smaller in the order of the one in which the TVOC corresponding component (n-hexadecane) was mixed (FIG. 7) and the one in which the TVOC corresponding component was not positively mixed (FIG. 8), which means that the TVOC component concentration Can be sufficiently specified from the peak area, and T
The fact that a considerable TVOC peak was obtained even from indoor air in which VOC-compatible components were not positively mixed in means that measurement of sample gas, which is highly likely to contain TVOC, such as incinerator exhaust gas, is reliable. It is clear that it can be done well.

[0032]

As described above, according to the present invention, a unit structure which has not existed in the past can be continuously measured in a cycle of, for example, 12 minutes, and a harmful component analysis system for exhaust gas from an incinerator is provided. The present invention provides a system that does not require a high degree of skill and is inexpensive in manufacturing and operating costs.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an incinerator exhaust gas TVOC monitor according to the present invention.

FIG. 2 is a sample line flow diagram of the TVOC monitor of FIG.

3 is a main part of the TVOC monitor shown in FIG.
It is a flow-path block diagram of a VOC analyzer.

FIG. 4 is a time chart of the TVOC analyzer.

FIG. 5 is a partial channel diagram showing an ON position (A) and an OFF position (B) of the channel switching structure of the TVOC analyzer.

FIG. 6 shows what is called “C1 to C5” by the system of the present invention.
When a considerable amount of n-pentane (nP) was adopted as a component corresponding to the peak and 5.551 mg / Nm ³ of n-hexane (nH) was adopted as a component corresponding to TVOC of "C6" or more. It is a chromatogram.

FIG. 7 is a chromatogram obtained by mixing a small amount of n-hexadecane (nHD) into an air sample by the system of the present invention.

FIG. 8 is a graph showing the in-laboratory air of the inventor, which includes the components corresponding to “C1 to C5” and “C6” by the system of the present invention.
It is a chromatogram measured without actively mixing a specific substance as the above TVOC component.

[Explanation of symbols]

1 incinerator 2 chimney 3 sample gas heating conduit 4 TVOC monitor 5 Sample pretreatment section 6 TVOC analyzer 7 recorder 18 ten way switching valve 19 Measuring tube 20 columns 21 detector

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01N 30/68 G01N 30/68 A 30/72 30/72 A 30/88 30/88 M (72) Invention Yo Doi 1-26-2, Fushiodai, Ikeda-shi, Osaka (72) Inventor Ryuichiro Kuboshima 2-19-19, Yokoki, Otsu-shi, Shiga Inventor Kazumasa Matsuzawa 1-12-1 Kita, Kunitachi, Tokyo issue

Claims (6)

[Claims] 1. A flow path switching valve, a metering pipe, and a hydrocarbon system through an exhaust gas collected from an exhaust gas flue of an incinerator through a sample heating conduit heated to a temperature at which water in the exhaust gas is not condensed. It is introduced into a TVOC monitor system consisting of a gas separation column and a hydrocarbon detector, and a fixed amount of exhaust gas collected in a measuring pipe is supplied as a sample gas to the separation column to elute the C1 to C5 hydrocarbon components, A method for continuous analysis of harmful air pollutants in exhaust gas from incinerators, characterized in that the separation column is backflushed, hydrocarbon components of C6 or higher are collectively sent back, and the hydrocarbon detector detects them as a collective peak. . 2. A sample heating conduit which is installed by being pulled out from an exhaust gas flue of an incinerator and heated to a temperature at which water in the exhaust gas is not condensed, a carrier gas source, and the sample heating conduit are positively operated. TV comprising a pretreatment unit including a suction pump for sucking exhaust gas and a filter for blocking soot and dust in the exhaust gas, a flow path switching valve, a metering pipe, a hydrocarbon gas separation column, and a hydrocarbon detector.
An OC monitor system, wherein the flow path switching valve comprises: a) a metering flow path for filling the measuring pipe with the exhaust gas sample introduced from the pretreatment unit; and b) a carrier gas for filling the exhaust gas sample in the measuring pipe. A sample introduction channel for supporting a carrier gas supplied from a source and sending it to a separation column, and introducing the column elution component into the hydrocarbon detector to detect C1 to C5 hydrocarbon components; and c) the carrier A gas is supplied to the separation column in the direction opposite to the sample introduction flow path, and a backflush flow based on the gas is sent to the hydrocarbon detector to detect a hydrocarbon component of C6 or more all at once. Continuous analysis of harmful air pollutants in incinerator exhaust gas, characterized in that it occupies a position to selectively form a flash channel Location. 3. An OFF flow path switching valve for simultaneously and concurrently forming the metering flow path and the backflush flow path.
The analyzer according to claim 2, wherein the position and an ON position forming the sample introduction flow channel are selectively occupied. 4. The analyzer according to claim 2, wherein the hydrocarbon detector is a hydrogen flame ionization detector. 5. The analyzer according to claim 2, wherein the hydrocarbon detector is a photoionization detector. 6. The analyzer according to claim 2, wherein the hydrocarbon detector is a mass spectrometer.