JP2010096688A - Pyrolytically decomposing apparatus for analyzing mercury, mercury analyzer, and its method - Google Patents

Abstract

An object of the present invention is to provide a thermal decomposition apparatus, a mercury analysis apparatus and a method for preventing iodine from being generated from activated carbon that has collected mercury in a sample, and to improve the sensitivity and accuracy of mercury analysis.
A thermal decomposition apparatus 10 according to the present invention includes a sample container 12 that stores activated carbon C that collects mercury in a sample S, a sample heating furnace 11 that heats activated carbon C stored in the sample container 12, A first carrier gas channel 16 for flowing a carrier gas G for carrying the mercury gas generated by heating the activated carbon C in the sample heating furnace 11, and generating the mercury gas from the activated carbon C;
Activated carbon C stored in the sample container 12 is heated to a predetermined temperature in the sample heating furnace 11 while flowing at least one of nitrogen gas, argon gas, neon gas, and helium gas as the carrier gas G.
[Selection] Figure 1

Description

  The present invention relates to a thermal decomposition apparatus and a mercury analysis apparatus that thermally decomposes activated carbon that collects mercury contained in a sample, a mercury collection method, and a mercury analysis method. In particular, it relates to the field of atomic absorption analysis or atomic fluorescence analysis.

  Conventionally, mercury analysis by atomic absorption spectrometry has been widely used in environmental analysis and quality control analysis for many years, and mercury analysis by atomic fluorescence analysis has also been used for a long time. For example, mercury in flue exhaust gas from waste incinerators and thermal power reactors is measured by various methods.

  For example, in Patent Document 1, analysis of mercury in gas is continuously measured. Mercury analysis in the exhaust gas discharged from the chimney of a garbage incinerator, the exhaust gas is introduced from the pipe by facing the tip of the pipe constituting the reduction device in the chimney and operating the suction pump Mercury reduced and passed through the reduction reactor is sent to the analyzer through the piping of the reduction device together with the exhaust gas, and mercury is analyzed by this analyzer.

  However, batch measurement, which is offline measurement, is also performed depending on the purpose and application. Conventionally, there is a mercury analyzer by thermal decomposition for batch measurement. For example, a sample is placed in a sample container, the sample container is inserted into a sample heating furnace, and the sample is heated and decomposed in a sample heating furnace while flowing a predetermined flow of air by an air pump, and mercury generated from the sample is collected by mercury. There is a mercury analyzer that collects in a tube and measures by atomic absorption spectrometry.

US EPA's Clean Air Mercury Rule stipulates collection measurement with a scavenger as a method for measuring mercury in coal exhaust gas. This method is a mercury collection column packed with activated carbon that has been specially treated. Coal exhaust gas is collected for a certain period of time, and after collection, each activated carbon in the mercury collection column is wet-decomposed to form a solution. Mercury is measured by atomic absorption spectrometry using reductive vaporization. However, wet decomposition of activated carbon requires sufficient knowledge and experience and takes time and effort. Moreover, since the activated carbon which collected coal exhaust gas is made into a solution, a sample density | concentration is diluted and a highly sensitive measurement cannot be performed.
JP 2001-33434 A

  Using a conventional mercury analyzer based on thermal decomposition, activated carbon that collects mercury in the exhaust gas for a certain period of time by the above-mentioned US EPA method is placed in a ceramic or quartz sample container, inserted into a sample heating furnace, and an air pump The activated carbon is heated in the sample heating furnace while flowing the air at a predetermined flow rate, and the compound mercury generated from the activated carbon is decomposed into zero-valent mercury in the oxidation promotion furnace, and this is collected as gold amalgam in the mercury collecting tube. Then, when measurement is performed by atomic absorption spectrometry, the measurement signal of mercury cannot be detected and measurement is impossible. In order to collect mercury more efficiently, iodine supported on activated carbon is vaporized by heating and adheres to the inner wall of the air flow path of the apparatus, forming a compound with the vaporized mercury. To trap mercury.

  The present invention has been made in view of the above-described conventional problems, and provides a thermal decomposition apparatus, a mercury analysis apparatus, and a method for preventing iodine from being generated from activated carbon that has collected mercury in a sample, and sensitivity of mercury analysis. And aim to improve accuracy.

  In order to achieve the above object, a thermal decomposition apparatus according to a first configuration of the present invention includes a sample container that contains activated carbon that collects mercury in a sample, and a sample that heats the activated carbon contained in the sample container. A heating furnace and a first carrier gas channel for flowing a carrier gas for carrying mercury gas generated by heating the activated carbon in the sample heating furnace, and generating mercury gas from the activated carbon The decomposition apparatus, wherein the activated carbon stored in the sample container is heated to a predetermined temperature in the sample heating furnace while flowing at least one of nitrogen gas, argon gas, neon gas, and helium gas as the carrier gas. To do.

  According to the thermal decomposition apparatus of the first configuration of the present invention, iodine can be prevented from being generated from the activated carbon that has collected mercury in the sample.

  It is preferable that the pyrolysis apparatus having the first configuration further includes a halogen removal furnace provided on the downstream side of the sample heating furnace in the first carrier gas flow path for removing halogen generated from the activated carbon. Even when a small amount of iodine is generated from activated carbon in which mercury in the sample is collected, the iodine can be removed.

  A mercury analyzer according to a second configuration of the present invention is configured to heat the pyrolysis device according to the first configuration, a mercury collection unit that collects mercury gas generated by the thermal decomposition device, and the mercury collection unit. A heating and vaporizing device for generating mercury gas and a mercury gas generated by heating the mercury collecting unit connected to the first carrier gas flow path and heated by the thermal decomposition device A carrier gas flow channel for flowing a carrier gas for the first carrier gas, carrier gas control means for controlling the flow rate of the carrier gas flowing through the first and second carrier gas flow channels, and quantifying the mercury content in the sample And a mercury analyzer.

  According to the unit of the second configuration of the present invention, iodine can be prevented from being generated from the activated carbon that has collected mercury in the sample, and the sensitivity and accuracy of mercury analysis can be improved.

  In the mercury collecting method according to the third configuration of the present invention, activated carbon in which mercury in a sample is collected is stored in a sample container, the activated carbon stored in the sample container is heated to a predetermined temperature, and the activated carbon is At least one carrier gas of nitrogen gas, argon gas, neon gas, and helium gas is allowed to flow through a carrier gas channel for carrying mercury gas generated by heating, and mercury contained in the activated carbon is converted into mercury. Collect in the collection unit.

  According to the method of the third configuration of the present invention, it is possible to improve the efficiency of collecting mercury in the sample by preventing iodine from being generated from the activated carbon that has collected mercury in the sample.

  In the mercury analysis method according to the fourth configuration of the present invention, the mercury collected in the mercury collection unit by the method of the third configuration is heated and vaporized, and the carrier gas flow path for carrying the vaporized mercury gas is supplied with nitrogen. The mercury gas is introduced into the analyzer by flowing at least one carrier gas out of gas, argon gas, neon gas, and helium gas, and the content of mercury in the sample is quantified by the analyzer.

  According to the method of the fourth configuration of the present invention, iodine can be prevented from being generated from the activated carbon in which mercury in the sample is collected, and high sensitivity and high accuracy analysis can be performed.

  Hereinafter, a mercury analyzer according to a first embodiment of the present invention will be described. This mercury analyzer 1 is an apparatus for quantifying the mercury content in flue exhaust gas, for example. As shown in FIG. 1, the activated carbon C that collects mercury in the flue exhaust gas as the sample S is thermally decomposed. Generated by the pyrolysis apparatus 10 that generates mercury gas, the carrier gas G that carries the generated mercury gas, for example, the dehumidifier 2 that removes the moisture carried along with the nitrogen gas G, and the pyrolysis apparatus 10. Mercury collecting unit 4 for collecting mercury gas, heating vaporizer 5 for heating mercury collecting unit 4 to generate mercury gas, and carrier gas from sample inlet 13 of decomposing apparatus 10 to dehumidifier 2 The second carrier gas channel 3 connected to the first carrier gas channel 16 which is the G channel, the carrier gas control means 6 for controlling the flow rate of the nitrogen gas G, and the mercury content in the sample S Analyzer for quantitative determination And a certain atomic absorption spectrometer 20.

  The thermal decomposition apparatus 10 contains activated carbon C that collects mercury in the sample S, for example, a sample vessel 12 made of ceramic, a sample heating furnace 11 that heats activated carbon C contained in the sample vessel 12, and activated carbon. Catalytic furnace 14 that reduces divalent mercury produced by heating C by sample heating furnace 11 to metallic mercury, and sulfur and halogen produced by activated carbon C being heated by sample heating furnace 11 are captured. The halogen removal furnace 15 collects and removes, and the 1st carrier gas flow path 16 which flows the nitrogen gas G for conveying these gas and mercury gas which are produced | generated by the sample heating furnace 11 is provided. The mercury analyzer 1 includes the halogen removal furnace 15 so that halogen such as iodine does not flow downstream of the halogen removal furnace 15 and improves the collection efficiency of mercury in the sample S, thereby achieving high sensitivity and high accuracy. Can be analyzed. The halogen removing furnace 15 is filled with, for example, granular silver oxide / cobalt oxide as a halogen removing agent.

  The mercury collecting unit 4 includes, as a filler, for example, a granular material such as gold or silver that reacts with metallic mercury to produce amalgam, a woolen fine wire, or a surface of a porous carrier coated with gold or silver. Used and connected to the second carrier gas flow path 3. The heating vaporizer 5 stores a mercury collection unit 4 that collects the mercury generated by the thermal decomposition apparatus 10 in a heating furnace, and vaporizes the collected mercury by heating the mercury collection unit 4. Let The carrier gas control means 6 includes a pump 61 for sucking a carrier gas G supplied from a carrier gas supply means (not shown) from the sample inlet 13 of the sample heating furnace 11 which is an introduction part of the carrier gas G, and a carrier gas G. And a flow meter 62 for controlling the flow rate. The carrier gas supply means is, for example, a nitrogen cylinder equipped with a pressure reducing valve. The carrier gas G is not limited to nitrogen gas, and at least one of nitrogen gas, argon gas, neon gas, and helium gas is flowed.

  As shown in FIG. 2, the atomic absorption spectrometer 20 includes a mercury lamp 21 that emits mercury analysis lines into a measurement cell 22 into which mercury vaporized by heating in the heating vaporizer 5 is introduced, and mercury that has passed through the measurement cell 22. And a detection processing unit 24 for calculating the mercury content in the sample S based on the detected intensity.

  Next, as one example of measuring mercury in flue exhaust gas, a method for collecting mercury used in, for example, a mercury-regulated coal exhaust gas mercury measurement method in coal exhaust gas of the US EPA will be described.

  This method is a method of collecting mercury using a commercially available mercury collection column, and as shown in FIG. 3 (a), mercury collection in which activated carbon C carrying iodine is packed in three layers. The column 40 is used to collect mercury in the exhaust gas. The mercury collection column 40 is filled with the same amount of three layers of activated carbon C, a sample collection layer 41, a leak amount display layer 42, and a mercury-added layer 43, and each activated carbon C is more efficiently filled with mercury. For example, iodine is supported in an amount of 0.5 wt% with respect to the weight of the activated carbon C.

  The sample collection layer 41 is filled with, for example, 0.5 g (g) of activated carbon C that collects mercury in coal exhaust gas. After collecting mercury in the exhaust gas, the sample container of the mercury analyzer 1 is collected. 12 is measured.

  The leak amount display layer 42 is filled with activated carbon C that collects mercury that has leaked without being collected by the sample collection layer 41, and is filled with 0.5 g (g) of the same amount as the sample collection layer 41. Then, after collecting mercury in the exhaust gas, it is measured in the same manner as the sample collection layer 41, and a leak amount from the sample collection layer 41 is detected, and this detected leak amount is the mercury in the coal exhaust gas. When the predetermined value determined by the regulation is exceeded, it is considered that some interference action occurs in the sample collection layer 41, and the measured value of the sample collection layer 41 cannot be used as an effective quantitative value.

  The mercury-added layer 43 is filled with activated carbon C to which a predetermined amount of mercury, for example, 1000 nanograms (ng) is added, and 0.5 gram (g) of the same amount as the sample collection layer 41. After collecting mercury, it is measured in the same way as the sample collection layer 41, and when the recovery rate of the added mercury amount is outside the range of the predetermined value determined by the mercury regulations in the coal exhaust gas, It is considered that some kind of interference occurs in the collection layer 41, and the measured value of the sample collection layer 41 cannot be used as an effective quantitative value.

  In the above description, the mercury collection column 40 having the three layers of activated carbon C has been described. However, a two-layer mercury collection column 50 including a sample collection layer 41 and a leak amount display layer 42 (see FIG. 3B), or A two-layer mercury collection column 60 composed of a sample collection layer 41 and a mercury addition layer 43 is also commercially available (see FIG. 3C). Further, mercury collection columns having activated carbon C filled in 0.2, 0.5, 1.0 gram (g), etc. are commercially available.

  Next, for example, a method for collecting and analyzing mercury in coal flue gas in a flue will be described. Mercury is collected from coal flue gas in the flue for a certain time using a two-layer mercury collection column 50 comprising a sample collection layer 41 and a leak amount display layer 42 by the method determined by the mercury regulations in the coal flue gas. Gathered. This mercury collecting column 50 is filled with 1.0 gram (g) of activated carbon C in each layer, 2 to 5 times the amount of mercury collecting column filled with 0.2 gram or 0.5 gram. Since the activated carbon C is filled, it can be collected for a long time, and even if the mercury in the coal exhaust gas has a low concentration, it can be measured with high sensitivity.

  Mercury in the coal exhaust gas is analyzed using the mercury collecting column 50 and the mercury analyzer 1 that collect mercury from the coal exhaust gas for a certain time by the above method. First, a total amount of 1 gram of activated carbon C of the sample collection layer 41 of the mercury collection column 50 is put into a boat-shaped sample container 12 made of, for example, ceramic or quartz, from the sample inlet 13 to the position of the sample heating furnace 11. The activated carbon C is gradually introduced from the room temperature in the sample heating furnace 11 while nitrogen gas G is supplied from the carrier gas supply means to the sample inlet 13 and a predetermined flow rate (for example, 0.2 L / min) is supplied by the pump 61. It heats to predetermined temperature 550-650 degreeC, Preferably it is 600 degreeC for a fixed time. The gas generated from the activated carbon C heated in the sample heating furnace 11 is carried by the nitrogen gas G, passes through the catalyst furnace 14, the halogen removal furnace 15, the dehumidifier 2, that is, the second carrier gas flow path 3, and the heating vaporizer 5. The mercury is collected in the mercury collecting unit 4 which is accommodated in the heating furnace and heated to 150 to 200 ° C., and mercury is collected. At the time of collecting mercury, the heating temperature of the mercury collecting unit 4 is preferably 150 to 200 ° C. so that other gases other than the mercury gas are not collected.

  Since nitrogen gas G, which is a carrier gas, does not contain oxygen, activated carbon C does not undergo an oxidation reaction even when heated to 550 to 650 ° C., so that combustion does not occur, and activated carbon C becomes steamed and activated carbon Mercury adsorbed on C is thermally decomposed into metallic mercury, but iodine supported on activated carbon C is not vaporized. When activated carbon C is heated to about 800 ° C. in a nitrogen gas atmosphere, a small amount of iodine is vaporized, and when heated at about 400 ° C., mercury does not seem to be sufficiently vaporized, and the heating temperature in the sample heating furnace 11 is 550 to 650 ° C. Is preferable, and about 600 ° C. is more preferable.

  The divalent mercury remaining in the gas generated from the activated carbon C heated in the sample heating furnace 11 is reduced to metallic mercury in the catalyst furnace 14 heated to 600 ° C., and the halogen removing furnace 15 heated to 400 ° C. Although passing through, halogen gas such as sulfur and remaining iodine is removed by the halogen removing furnace 15.

  After mercury is collected by the mercury collecting unit 4, the mercury collected by heating and vaporizing the mercury collecting unit 4 in the heating furnace of the heating vaporizer 5 to 600 to 700 ° C. is converted into nitrogen gas G by the pump 61. The flow rate is adjusted to a flow rate of, for example, 0.5 L / min with the flow meter 62 while sucking the gas and introduced into the measurement cell 42 of the atomic absorption spectrometer 20 for measurement. A mercury analysis line is emitted from the mercury lamp 21 to the measurement cell 22 into which the mercury gas has been introduced, and the detector 23 detects the intensity of the mercury analysis line that has passed through the measurement cell 22, and a detection processing unit based on the detected intensity. 24, the mercury content in the activated carbon C is calculated, and the mercury in the sample S is quantified.

  Next, the whole amount of 1 gram of activated carbon C of the leak amount display layer 42 of the mercury collection column 50 is put into the sample container 12, and the activated carbon C in the leak amount display layer 42 is contained in the same manner as the sample collection layer 41. Measure the mercury content. When the content of the leak amount display layer 42 does not exceed a predetermined value determined by the mercury regulation in the coal exhaust gas, the quantitative value of the sample collection layer 41 can be used as an effective measurement value. Thus, the mercury content in the coal exhaust gas collected in the mercury collecting column is quantified.

  Thus, in this embodiment, nitrogen gas is used for the carrier gas G, the activated carbon C of the sample collection layer 41 and the leak amount display layer 42 is in a steamed state, and the mercury adsorbed on the activated carbon C is thermally decomposed. However, since the iodine supported on the activated carbon C is not vaporized, iodine does not adhere to the inner wall of the carrier gas flow path of the mercury analyzer 1, and the mercury in the activated carbon C is analyzed with high sensitivity and high accuracy. can do. Even if a small amount of iodine is vaporized from the steamed activated carbon C, since the halogen removal furnace 15 is provided, the small amount of iodine can also be removed. In addition, in the case of a sample container that can contain only 0.2 g (g) or 0.5 g (g) of activated carbon C, when the mercury content in the exhaust gas is small, it is decomposed once. Since sufficient sensitivity cannot be obtained by itself, it is necessary to collect the activated carbon C repeatedly and thermally decompose it 2 to 5 times and collect mercury in the mercury collecting unit 4, but in the apparatus of this embodiment, One gram (g) can be accommodated and can be measured with only one collection.

  Hereinafter, the mercury analyzer 2 according to the second embodiment of the present invention will be described. As shown in FIG. 1, this mercury analyzer 2 is an apparatus in which an atomic absorption spectrometer 20 that is an analyzer of the mercury analyzer 1 according to the first embodiment is replaced with an atomic fluorescence analyzer 30. The configuration of is the same as that of the mercury analyzer 1. Accordingly, in FIG. 1, the mercury analyzers are labeled 1 and 2, and the analyzers are labeled 20 and 30. As shown in FIG. 4, the atomic fluorescence analyzer 30 includes a mercury lamp 31 that radiates a mercury analysis line to a measurement cell 32 into which mercury heated and vaporized by the heating vaporizer 5 is introduced, and radiation from the mercury lamp 31. A detector 33 disposed at a position where the analyzed line is not incident and at a position where mercury fluorescence generated from the mercury present in the sample gas S introduced into the measurement cell 32 can be detected; and A detection processing unit 34 that quantifies the mercury content in the sample gas S according to the detected fluorescence intensity of mercury is provided.

  In the mercury collection method and analysis method using the mercury analyzer 2 of the second embodiment, for example, argon gas G is supplied as a carrier gas from a carrier gas supply means that is an argon cylinder equipped with a pressure reducing valve, Since the detection processing unit 34 quantifies the mercury content in the sample gas S according to the fluorescence intensity of mercury detected by the detector 33, the description is omitted because it is the same as the method of the first embodiment. .

  According to the present embodiment, the operation and effect are the same as those of the first embodiment, and the analyzer is the atomic fluorescence analyzer 30. Therefore, when argon gas is used as the carrier gas G, nitrogen gas is used. Highly sensitive analysis can be performed.

  In the above-described embodiment, the method using the two- or three-layer mercury collection columns 40, 50, and 60 has been described. However, in the present invention, a mercury collection column having only the sample collection layer 41 is used. Mercury in sample S may be collected and measured. In the above embodiment, nitrogen gas and argon gas are used as the carrier gas G. However, any gas that does not contain oxygen and has low reactivity may be used, neon gas or helium gas may be used, and any combination of these may be used. A mixed gas may be used. In the first and second embodiments described above, the wavelength non-dispersion type atomic absorption or atomic fluorescence analyzer is shown. However, in the present invention, the wavelength dispersion type atomic absorption or atomic fluorescence analyzer is shown. May be.

It is a schematic block diagram of the mercury analyzer which is the 1st and 2nd embodiment of the present invention. 1 is a schematic block diagram of an atomic absorption spectrometer of a mercury analyzer that is a first embodiment of the present invention. (A) It is the schematic of a mercury collection column of 3 layers. (B) Schematic of one two-layer mercury collection column. (C) It is the schematic of another one two-layer mercury collection column. It is a schematic block diagram of the atomic fluorescence analyzer of the mercury analyzer which is the 2nd Embodiment of this invention.

Explanation of symbols

1 2 Mercury analyzer 3 Second carrier gas flow path 4 Mercury collection unit 5 Heating vaporizer 6 Carrier gas control means 10 Thermal decomposition apparatus 11 Sample heating furnace 12 Sample container 15 Halogen removal furnace 16 First carrier gas flow path 20 Atomic absorption analyzer 30 Atomic fluorescence analyzer C Activated carbon G Carrier gas S Sample

Claims (5)

A sample container containing activated carbon that collects mercury in the sample;
A sample heating furnace for heating the activated carbon contained in the sample container;
A first carrier gas flow path for flowing a carrier gas for carrying mercury gas generated by heating the activated carbon in the sample heating furnace;
A pyrolysis apparatus for producing mercury gas from the activated carbon,
A pyrolysis apparatus that heats the activated carbon contained in the sample container to a predetermined temperature in the sample heating furnace while flowing at least one of nitrogen gas, argon gas, neon gas, and helium gas as the carrier gas. In claim 1,
Furthermore, the thermal decomposition apparatus which has a halogen removal furnace which is provided in the said 1st carrier gas flow path downstream from the said sample heating furnace, and removes the halogen which generate | occur | produced from the said activated carbon. The thermal decomposition apparatus according to claim 1 or 2,
A mercury collecting unit for collecting the mercury gas generated by the thermal decomposition apparatus;
A heating vaporizer for heating the mercury collecting unit to generate mercury gas;
A second carrier gas that is connected to the first carrier gas flow path and flows a mercury gas generated by the thermal decomposition apparatus and a carrier gas for carrying the mercury gas generated by heating the mercury collecting unit. A flow path;
Carrier gas control means for controlling the flow rate of the carrier gas flowing through the first and second carrier gas flow paths;
An analyzer for quantifying the mercury content in the sample;
Mercury analyzer with Store activated carbon that collects mercury in the sample in the sample container,
Heating the activated carbon contained in the sample container to a predetermined temperature;
Flowing at least one carrier gas of nitrogen gas, argon gas, neon gas, helium gas through a carrier gas flow path for carrying mercury gas generated by heating the activated carbon,
A mercury collecting method for collecting mercury contained in the activated carbon in a mercury collecting unit. The mercury collected by the mercury collecting unit by the method according to claim 4 is vaporized by heating,
At least one carrier gas of nitrogen gas, argon gas, neon gas, helium gas is flowed into a carrier gas flow path for carrying vaporized mercury gas, and the mercury gas is introduced into the analyzer,
A mercury analysis method for quantifying mercury content in a sample with the analyzer.

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