JPH11223582A - Analytical method for unvolatile organic halogen in exhaust combustion gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an analytical method in which unvolatile organic halogens as an index of the concetration of dioxins are analyzed simply and in which a contamination inside a laboratory is prevented by a method wherein exhaust combustion gas inside a gas flue is sucked into an activated carbon column which is held in a specific temperature range. SOLUTION: Exhaust combustion gas inside a gas flue 9 is sampled without cooling them, and it are sucked into an activated carbon column 4 which is held at a nearly constant temperature in a range of 110 to 130 deg.C. Then, inorganic halogenides are removed from the activated carbon column 4, activated carbon is then burned, and generated hydrogen halogenides are measured. A pump 6 is used to suck a sample gas into the activated carbon column 4, and a flowmeter 7 is used to confirm an isokinetic sampling operation in the activated carbon column 4. An integrating flowmeter 8 is used to compute the concentration in flue gases of unvolatile organic halogens. Thereby, it is possible to simply analyze the unvolatile organic halonges, in the flue gases, which can be used effectively as an index of the concentration of dioxins in the exhaust combustion gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for analyzing non-volatile organic organic halogens in flue gas. The analysis value of the non-volatile organic halogen according to the present invention can be effectively used as an index of the concentration of dioxins in the combustion exhaust gas.

[0002]

2. Description of the Related Art In addition to organic halogens, toxic dioxins are included as harmful substances in combustion exhaust gas generated when incineration of municipal garbage and industrial wastes is performed. In particular, dioxins are becoming a global problem because of their high toxicity. Dioxins are
It is said that organic halogen is generated as a precursor,
The details of its generation mechanism are complex and have not yet been elucidated.

[0003] On the other hand, a method for measuring dioxins has not been well established, but as a current standard method, two water traps, an empty trap, an XAD-2 resin column, and two With a capturing device in which diethylene glycol traps are sequentially placed in a cooling bath (ice-cooled bath, etc.),
A method is known in which dioxins in a combustion exhaust gas are captured, and after each operation of solvent extraction and concentration, each component is identified by mass spectrometry, and toxicity conversion is performed for each component. However, such a normal method requires a great deal of time (1-2 months) and cost (hundreds of thousands of yen) for extraction, purification, concentration, mass spectrometry, etc. There is a problem of causing contamination, and it is necessary to take measures to prevent dioxins from leaking out of the facility by setting a negative pressure in the laboratory.

In view of the above, various simple measurement methods which are simplified versions of the above-mentioned normal method have been conventionally studied. For example, the method described in the 8th Annual Meeting of the Waste Management Society of Japan, 562-564, has been known. ing. Although such a method is simple,
As is clear from FIG. 7 on page 564, there is a problem in accuracy.

On the other hand, as a method of relatively high accuracy, a method utilizing a correlation between a hardly volatile organic halogen and dioxins is known (Chemical Substances and the Environment, May 1997, No. 23, No. 11). １３13). Specifically, the dioxins in the combustion exhaust gas are captured by the above two traps of a capturing device including a water trap and an ethylene glycol trap and an active carbon column for safety measures arranged sequentially in an ice-cooled bath, After extraction with toluene, organic halogens (refractory organic halogens including chlorobenzenes) are measured by a combustion method, and the concentration of dioxins is estimated from a calibration curve of the refractory organic halogens and dioxins.

However, in the case of the above simple measuring method, since the dioxins that have passed through the trap are ignored, the measurement accuracy is not always sufficient. In addition, there is a need for concentration operation using an evaporator after toluene extraction, and there are safety measures such as cleaning of contaminated instruments used for concentration operation and storage of measured samples. The state of pollution has not yet been resolved.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for measuring the concentration of dioxins in flue gas which can be effectively used as an indicator of the concentration of dioxins in flue gas. An object of the present invention is to provide a method for analyzing volatile organic halogen which is simple and does not cause contamination in a laboratory.

[0008]

Means for Solving the Problems The present inventors have made various studies focusing on the above-mentioned method utilizing the correlation between a hardly volatile organic halogen and dioxins, and as a result, have found the following idea. Obtained. (1) As long as the analysis method is reproducible,
Even the analysis value of the refractory organic halogen analyzed by another simple method different from the above can be effectively used for the correlation with dioxins in the same manner as described above, and (2)
If all the organic halogens containing dioxins are concentrated in an activated carbon column and the whole amount is burned for analysis, the problem of contamination by dioxins in the laboratory can be solved at once.

The present invention has been completed by further study based on the above idea. The gist of the present invention is to collect flue gas in a flue without cooling it,
Combustion, characterized in that the activated carbon column is sucked into an activated carbon column maintained at a substantially constant temperature in the range of, and then the inorganic carbon is removed from the activated carbon column, and then the activated carbon is burned and the generated hydrogen halide is measured. The present invention relates to a method for analyzing non-volatile organic halogen in exhaust gas.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of an example of a hard-to-evaporate organic halogen capturing device used in the present invention.

First, the configuration and function of the non-volatile organic halogen capturing apparatus used in the present invention will be described. This trapping device mainly comprises an activated carbon column (4) and a heating mechanism (10). 1, reference numeral (1) denotes a liquid medium trap, (2) denotes an empty trap, (3) denotes a cooling bath,
(5) is a sampling tube, (6) is a pump, (7) is a flow meter, (8) is an integrating flow meter, and (9) is a flue. Further, the above-mentioned hard-to-evaporate organic halogen trapping device is provided with a flue (9)
It is installed outdoors near.

The sampling pipe (5) penetrating through the side wall of the flue (9) is adapted to be able to collect the flue gas in the flue (9) without cooling it by a suitable heat retaining means. The temperature of the combustion exhaust gas (sample gas) to be sampled is usually in the range of 110 to 300 ° C.

The activated carbon column (4) is composed of a column having a removable structure and activated carbon filled therein. As the activated carbon, activated carbon having a low chlorine content is used. The chlorine content in the activated carbon is preferably 20 ppm (particularly 10 ppm) or less. The average particle size of the activated carbon is preferably in the range of 1 to 10 mm in consideration of pressure loss. The amount of activated carbon packed in the activated carbon column (1) is set to an amount corresponding to an amount capable of sufficiently capturing the hardly volatile halogen in the sample gas.

[0014] The activated carbon may be filled in either a single-stage type or a multi-stage type. In the case of the multi-stage format, the non-volatile halogen was analyzed for each stage, and compared with the former stage having the same concentration, there was no leakage of the non-volatile halogen from the activated carbon column (1). Thus, it can be confirmed that the amount of activated carbon packed in the activated carbon column (1) was an amount suitable for an amount capable of sufficiently capturing the non-volatile halogen in the sample gas.

Further, in the case of the above-mentioned multistage type, the amount of chlorine derived from activated carbon can be measured. That is, the chlorine amount in the next stage where the non-volatile halogen concentration becomes the same is not derived from the combustion exhaust gas, and can be regarded as the chlorine amount derived from the activated carbon. Such measurement of the amount of chlorine derived from activated carbon can be used for correction to calculate the true non-volatile halogen amount in the combustion exhaust gas in the below-described total organic halogen analysis. In other words, different chlorine contents can be corrected depending on the lot of activated carbon.

In the present invention, the activated carbon column (1)
It is important that the heating mechanism (10) is maintained at a substantially constant temperature in the range of 110 to 300 ° C (preferably ± 5 ° C). As a result, in the present invention, chlorobenzene and particularly high-boiling components including dioxins can be reliably trapped as the hardly volatile organic halogen which has been recognized to have a correlation with dioxins. At this time, the moisture in the combustion exhaust gas passes through the activated carbon column without dew condensation in the activated carbon column (1). As a result, in the activated carbon column (1), since the formation of a water film on the surface is prevented, the adsorption ability of the gas component exerted together with the capture of the solid component (fine particles) is maintained at a high level.

The liquid medium trap (1) and the empty trap (2) are arranged in a cooling bath (3). They are,
Optional equipment used for pump (6) protection described below. As a medium of the liquid medium trap (1), water, ethylene glycol, or the like is used. As a cooling medium of the cooling bath (3), an appropriate medium (for example, ice water) that does not solidify the medium of the liquid medium trap (1) is used. Etc.) are used. Further, the leading end of the introduction pipe into the liquid medium trap (1) is located in the medium.

The pump (6) is used for sucking a sample gas into the activated carbon column (4), and the flow meter (7)
Is used to confirm the constant velocity suction in the activated carbon column (4). The integrating flow meter (8) is used for calculating the concentration of the non-volatile organic halogen in the combustion exhaust gas.

The inside diameter of an example of the activated carbon column (1) used in the above-mentioned hard-to-evaporate organic halogen trapping device is about 1
5 mm, the particle size range of activated carbon is 1.0 to 1.7 mm, and an example of the activated carbon filling amount is about 0.5 g / 1 column.

Next, the method for analyzing a non-volatile organic halogen according to the present invention will be described. In the present invention, the combustion exhaust gas is treated using the above-described trapping device, and after removing the inorganic halide from the activated carbon column (1), the activated carbon is burned and the generated hydrogen halide is measured. Therefore, in the present invention, an operation such as concentration of the extract is not required.

After removing the inorganic halide from the activated carbon column, the activated carbon is burned, and the generated hydrogen halide is measured to measure all organic halogens (refractory organic halogens such as chlorobenzene trapped in the activated carbon column). The method itself is known in the art, for example, the “Total Organic Halogen Analysis System” by Mitsubishi Chemical. This system is based on the official method No. 9020 of the US EPA, and includes “TOX-100” and “TOX-10”.
Σ ”is commercially available. In the case of using this commercial system, the measurement of total organic halogen is shown in the following table (1) to (1).
This is performed by the step (4).

[0022]

(1) A nitrate solution (about 1% by weight) is passed through an activated carbon column to remove inorganic halides. (2) The activated carbon taken out of the activated carbon column is extruded into a boat, the boat is inserted into a combustion tube, and the activated carbon is burned in an oxygen stream. Thereby, all the organic halogens are converted into hydrogen halide. (3) The generated hydrogen halide is introduced into a titration cell, and is automatically titrated with silver ions generated coulometrically. (4) The amount of halogen (converted to chlorine) is digitally displayed based on the amount of electricity required for titration based on Faraday's law.

[0023]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 An exhaust gas at 120 ° C. from a garbage incinerator was sampled using a total organic halogen trapping apparatus shown in FIG. 1 having the specifications shown in Table 2 below, and the total organic halogen therein was analyzed. .

[0025]

[Table 2]

First, the combustion exhaust gas was supplied at 13 L / min (S.
T. 0.5Nm by suction at a constant speed with pump (2)
^ThreeSampled. Next, the activated carbon column (4) was removed.
1% by weight KNO _ThreeInorganic halide through aqueous solution
Was removed. After that, manufactured by Dia Instruments
With TOX-100, each column connected is difficult
Emitted organic halogen (in terms of chlorine) was measured. Table of results
3 is shown.

[0027]

[Table 3]

From the results shown in Table 3, it can be seen that the refractory organic halogens in the fourth and fifth activated carbon columns were originally contained in the activated carbon itself. Therefore, the amount of non-volatile organic halogen (μg-Cl / N
m ³ ) can be calculated as follows. {(156.3 + 47.4 + 11.2) -3.3 × 3} ×
2 = 410 (μg-Cl / Nm ³ )

[0029]

According to the present invention described above, there is provided a simple method for analyzing non-volatile organic halogens in flue gas which can be effectively used as an index of the concentration of dioxins in flue gas. . Further, according to the present invention,
The laboratory is not contaminated with highly toxic dioxins, and there is no need for capital investment such as negative pressure in the laboratory, and the analysis can be performed in a normal laboratory. Can be done.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an example of a non-volatile organic halogen capturing device used in the present invention.

[Explanation of symbols]

 1: liquid medium trap 2: empty trap 3: cooling bath 4: activated carbon column 5: sampling tube 6: pump 7: flow meter 8: integrating flow meter 9: flue 10: heating mechanism

Claims (1)

[Claims] 1. A combustion flue gas in a flue is collected without cooling, sucked into an activated carbon column maintained at a substantially constant temperature in a range of 110 to 300 ° C., and then an inorganic halide is removed from the activated carbon column. After that, the activated carbon is burned, and the generated hydrogen halide is measured.