JP2010122160A - Mercury analyzing apparatus and method therefor - Google Patents

Abstract

An object of the present invention is to provide a mercury analyzer and a method for eliminating mercury residue in a flow path for collecting mercury in a sample, and to analyze mercury with high sensitivity and high accuracy.
A mercury analyzer of the present invention includes a sample gas introduction channel 2 for flowing a sample gas S to a mercury collecting tube 4 for collecting mercury in the sample gas S, and a mercury collecting device for collecting mercury. A heating vaporizer 5 for heating the tube 4 to vaporize mercury, a mercury measuring device 6 for measuring the vaporized mercury, and a flow channel connection 3 on the upstream side of the mercury collecting tube 4 of the sample gas introduction flow channel 2. And a carrier gas supply flow path 7 for flowing a carrier gas G for transporting vaporized mercury to the mercury measuring device 6. The flow path connection portion 3 includes an inner tube 25 in the hollow portion of the outer tube 75. This is a double tube that penetrates, and either the sample gas S or the carrier gas G flows through the hollow portion 251 of the inner tube 25, and the other gas flows between the outer wall 252 of the inner tube 25 and the inner wall 752 of the outer tube 75. It has a double flow path flowing through the tubular space 753 therebetween.
[Selection] Figure 1

Description

  The present invention relates to a mercury analyzer for collecting mercury in a sample gas in a mercury collecting tube, and then heating the mercury collecting tube with a heating vaporizer to vaporize the mercury collected in the mercury collecting tube for analysis. And its mercury analysis method. In particular, it relates to the field of atomic fluorescence analysis or atomic absorption 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, mercury in gas is continuously measured. This measurement is an analysis of mercury 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. Then, the mercury reduced and passed through the reduction reactor is sent to the analyzer together with the exhaust gas through the piping of the reduction device, 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 the sample heating furnace while flowing a predetermined flow of air with 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 it by atomic absorption spectrometry or atomic fluorescence spectrometry. In addition, for example, a predetermined amount of exhaust gas discharged from a chimney of a garbage incinerator is flowed by a suction pump, and mercury in the sample gas is collected by a mercury collecting tube and then measured by atomic absorption spectrometry or atomic fluorescence spectrometry. There is a mercury analyzer.
JP 2001-33434 A

  When mercury in the sample gas is collected and measured in a mercury collection tube, mercury remains in the flow path from the sample gas inlet to the mercury collection tube, and the mercury-free gas is sampled. Even if the residual mercury in the pipe is trapped by the filler of the mercury collecting pipe, the blank value increases. This phenomenon is particularly noticeable during blank measurement after sampling a gas containing high-concentration mercury, and it is necessary to perform idle operation for a long time to sample a gas that does not contain mercury in order to lower the blank. There was a problem that analysis became difficult. In particular, atomic fluorescence analysis measures a very small amount of mercury with high sensitivity, and this residual mercury greatly affects the measured value.

  The present invention has been made in view of the above-described conventional problems, and provides a mercury analyzer and a method for eliminating mercury residue in a flow path for collecting mercury in a sample. The purpose is to analyze.

    In order to achieve the above object, the mercury analyzer of the present invention includes a sample gas introduction channel for flowing a predetermined amount of sample gas into a mercury collecting tube for collecting mercury in the sample gas, and mercury collected. A heating vaporizer for heating the mercury collecting tube to vaporize mercury, a mercury measuring device for measuring mercury vaporized by the heating vaporizer, and an upstream side of the mercury collecting tube in the sample gas introduction channel Mercury analysis for analyzing mercury in a sample gas, comprising a carrier gas supply channel for flowing a carrier gas for transporting the mercury vaporized by the heating vaporizer to the mercury measuring device In the apparatus, the flow path connecting portion is a double tube in which the inner tube penetrates the hollow portion of the outer tube, and either one of the sample gas and the carrier gas flows through the hollow portion of the inner tube, The other gas flows between the outer wall of the inner pipe and the outer Having a dual channel through the tubular space between the inner wall of.

  The mercury analysis method of the present invention comprises heating a sample gas introduction channel for flowing a predetermined amount of sample gas into a mercury collection tube for collecting mercury in the sample gas, and the mercury collection tube in which mercury is collected. A vaporizer for vaporizing mercury, a mercury measuring device for measuring mercury vaporized by the vaporizer, and a flow path connecting portion upstream of the mercury collecting pipe in the sample gas introduction flow path. A carrier gas supply channel for flowing a carrier gas for transporting the mercury vaporized by the heating vaporizer to the mercury measuring device, and the inner tube penetrates the hollow portion of the outer tube through the channel connection portion. Formed by a double pipe, and either the sample gas or the carrier gas is allowed to flow through the hollow portion of the inner pipe, and the other gas is tubular between the outer wall of the inner pipe and the inner wall of the outer pipe. Flow through the space to analyze mercury in the sample gas.

  According to the mercury analyzer or mercury analysis method of the present invention, the sample gas introduction channel and the carrier gas supply channel are independent at the channel connection portion, and the sample gas does not contact the carrier gas supply channel. The carrier gas does not contain residual mercury from the sample gas, and mercury can be analyzed with high sensitivity and high accuracy.

  In this invention, it is preferable that sample gas flows through the hollow part of the said inner tube, and carrier gas flows through the tubular space between the outer wall of the said inner tube, and the inner wall of an outer tube. With this configuration, the surface area of the inner wall of the inner tube is considerably smaller than the surface area of the outer wall of the inner tube of the tubular space and the inner wall of the outer tube, and since the structure is not complicated, mercury in the sample gas S does not remain and adsorption is unlikely to occur. Contamination of the inner surface of the pipe can be prevented. Thus, since residual mercury can be eliminated and contamination can be prevented, a heating member for heating the piping is not required, and the cost can be reduced.

  In the present invention, the mercury measuring device is preferably an atomic fluorescence analyzer. By using a mercury analyzer as an atomic fluorescence analyzer, analysis with higher sensitivity can be performed.

  Hereinafter, a mercury analyzer according to a first embodiment of the present invention will be described. This mercury analyzer 1 is a mercury analyzer 1 that quantifies the content of mercury in a sample gas. As shown in FIG. 1, the sample gas S is introduced from a sample gas inlet 21 and is contained in the sample gas S. A sample gas introduction channel 2 for flowing a predetermined amount of the sample gas S to the mercury collecting tube 4 for collecting mercury, a heating vaporizer 5 for heating the mercury collecting tube 4 to vaporize the collected mercury, The mercury measuring device 6 that measures mercury vaporized by the heating vaporizer 5 is connected to the sample gas introduction flow channel 2 upstream of the mercury collecting tube 4 by the flow channel connecting portion 3, and is vaporized by the heating vaporizer 5. The carrier gas supply channel 7 for supplying the carrier gas G for transporting the mercury to the mercury measuring device 6 and the measurement channel 8 connected to the gas outlet 42 of the mercury collecting tube 4 are provided. The measurement flow path 8 includes a mercury measuring device 6, a gas switching valve 81, a mercury removal filter 82, a suction pump 83, and a first gas flow rate control means 84 in order from the upstream side. A bypass passage 9 for bypassing the mercury measuring device 6 is provided.

  The sample gas S is not limited to a sample in which the sample itself is gaseous, for example, flue exhaust gas, but the mercury in the solid sample can be obtained by storing the solid sample in a quartz boat and thermally decomposing it with a thermal decomposition apparatus. It may be a gas sample, a solution sample obtained by reducing vaporization of mercury as a solution sample, or the like.

  As shown in FIG. 2, the flow path connecting portion 3 includes, for example, a T-shaped three-way pipe 31, a different diameter joint 32, and a same diameter joint 33, the pipe 25 of the sample gas introduction flow path 2 and the carrier gas supply flow path 7. A pipe 75 is connected. Specifically, the pipe 25 of the sample gas introduction flow channel 2 and the three-way pipe 31 are connected by the different-diameter joint 32 on the upstream side of the three-way pipe 31, and the three-way pipe is connected by the same-diameter joint 33 on the downstream side of the three-way pipe 31. 31 and the pipe 75 of the carrier gas supply flow path 7 are connected, and the pipe 25 of the sample gas introduction flow path 2 passes through the hollow portion of the three-way pipe 31 and the pipe 75 of the carrier gas supply flow path 7.

  The pipe 25 of the sample gas introduction flow path 2 is, for example, a Teflon (registered trademark) pipe having an outer diameter of 3 mm and an inner diameter of 2 mm or 1 mm, the three-way pipe 31 is, for example, a glass tube having an outer diameter of 6 mm, an inner diameter of 4 mm, and the carrier gas supply flow path 7 The pipe 75 is, for example, a Teflon (registered trademark) pipe having an outer diameter of 6 mm and an inner diameter of 4 mm, and an inner pipe that is a pipe of the sample gas introduction flow path 2 in a hollow portion of the outer pipe 75 that is a pipe of the carrier gas supply flow path 7. Reference numeral 25 denotes a double tube penetrating. Specifically, as shown in FIG. 3, the sample gas S flows through the hollow portion 251 of the inner tube 25, and the carrier gas G flows through the tubular space 253 between the outer wall 252 of the inner tube 25 and the inner wall 752 of the outer tube 75. A heavy flow path is formed. As shown in FIG. 2, the inner tube 25 extends to the vicinity of the heater 51 of the heating vaporizer 5 that heats the mercury collecting tube 4, and the sample gas S is introduced into the mercury collecting tube 4. The three-way pipe 31 may be a Teflon (registered trademark) joint.

  As a modification of the flow path connecting portion 3, the pipe material of the inner tube 25 shown in FIG. 2 is a heat-resistant, for example, glass tube, and the tip of the glass tube 26 is heated by a heater 51 as shown in FIG. It extends to the vicinity of the filler 45 of the mercury collecting tube 4. By extending the tip of the inner tube 25 to the end of the heater 51, the mercury remaining at the tip of the inner tube 25 can be surely vaporized. Furthermore, since it extends to the inside of the mercury collecting tube 4, the region separated from the outer tube 75 further expands, and the residual mercury is less contained in the carrier gas G.

  As a filler 45 for collecting mercury, the mercury collecting tube 4 is a porous material whose surface is coated with granular materials such as gold and silver, wool-like fine wires, gold and silver, etc., which react with metallic mercury to produce amalgam. A quality carrier or sea sand is used. The gas switching valve 81 releases the measurement flow path 8 and closes the bypass flow path 9 when measuring mercury. When collecting the mercury of the sample gas S in the mercury collecting tube 4, the gas switch valve 81 releases the bypass flow path 9 and measures the flow. Road 8 is closed. The first gas flow rate control means 84 is, for example, a mass flow controller, and controls the gas flow rates of the measurement flow path 8 and the bypass flow path 9. The heating vaporizer 5 accommodates a mercury collection tube 4 for collecting mercury in a heating furnace, and heats the mercury collection tube 4 to vaporize the collected mercury.

  The mercury measuring device 6 is an atomic fluorescence analyzer 6 that quantifies the content of mercury in the sample gas S, and argon gas G is used as the carrier gas G in order to measure with high sensitivity. This is because when air is used as the carrier gas G, 253.7 nm (nanometers) of ultraviolet rays, which are mercury analysis lines, are absorbed. Therefore, normally, air G is used in the stage of collecting mercury from the sample gas S, and argon gas G is used in the measurement stage.

  The carrier gas supply flow path 7 is an argon gas supply source 71 such as an argon cylinder that supplies the argon gas G, a second gas flow rate control means 72 that controls the flow rate of the argon gas G, for example, a mass flow controller, and an argon gas. And a mercury removal pipe 73 for removing mercury in G. As a filler for collecting mercury, the mercury removing tube 73 is coated with, for example, gold or silver particles or wool-like fine wires that react with metallic mercury to produce amalgam, or gold or silver on the surface of the porous carrier. The mercury removal filter 82 is filled with activated carbon.

  As shown in FIG. 5, the atomic fluorescence analyzer 6 was introduced into the measurement cell 62 and the mercury lamp 61 that radiates mercury analysis lines into the measurement cell 62 into which the mercury vaporized by heating is introduced. A detector 63 for detecting the fluorescence of mercury generated from the mercury present in the sample gas S and a detection processing unit 64 for calculating the mercury content in the sample gas S based on the detected intensity are provided.

  Next, in order to clarify the difference between the mercury analyzer 1 of the present invention and the conventional mercury analyzer, a conventional mercury analyzer using an atomic fluorescence analyzer as a mercury measuring device, particularly a flow path connection portion will be described. To do.

  In the conventional mercury analyzer, the flow path connection portion 30 is not a double tube in which the inner tube 25 penetrates the hollow portion of the outer tube 75 as in the flow path connection portion 3 of the first embodiment, but is shown in FIG. As described above, the sample gas introduction channel 12 and the carrier gas supply channel 17 are connected by a three-way tube 123 having a single tube structure. The three-way pipe 123 connects the sample gas Teflon (registered trademark) pipe 125 and the mercury collecting pipe 4 having an outer diameter of 6 mm and an inner diameter of 4 mm, for example, with the same-diameter joint 121 and the same-diameter joint 122.

  In the conventional three-way pipe 123, even if the mercury in the sample gas S remains on the inner surfaces of the joints 121 and 122 having the same diameter and the inner surface of the three-way pipe 123 or is adsorbed, a gas containing no mercury is sampled. Residual mercury in the pipe is trapped in the filler 45 of the mercury collecting tube 4 and the blank value becomes high. This phenomenon is particularly noticeable during the blank measurement after sampling a gas containing a high concentration of mercury. Analysis of mercury was difficult.

  Next, an analysis method for analyzing the sample gas S using the mercury analyzer 1 of the present invention will be described. As shown in FIG. 1, the sample gas S is, for example, 0.5 L / min. Mercury traps introduced from the sample gas inlet 21 by the suction pump 83 and the first flow rate control means 84 so as to have a flow rate of (liter / minute) and housed in the heating furnace of the unheated heating vaporizer 5. Mercury is collected by entering the collecting tube 4. At this time, the gas switching valve 81 releases the bypass flow path 9 and closes the measurement flow path 8.

  Next, the first argon gas purge for purging the bypass channel 9 with the argon gas G is started. The argon gas G from the carrier gas supply channel 7 is, for example, 0.5 L / min. The flow rate is controlled by the second flow rate control means 72 to be introduced into the carrier gas supply flow path 7, the bypass flow path 9 is purged with the argon gas G, and the bypass flow path 9 is purged from the air with the argon gas G. Replaced with atmosphere. At this time, the flow rate of the bypass passage 9 is set to 0.2 L / min. The flow rate is controlled to be

  Next, a second argon gas purge in which the measurement flow path 8 is purged with the argon gas G is entered. At this time, the argon gas flow rates in the carrier gas supply channel 7 and the measurement channel 8 are the same as those in the first argon gas purge, and the gas switching valve 81 releases the measurement channel 8 and closes the bypass channel 9. is doing.

  After the first and second argon gas purges, the mercury collecting tube 4 in the heating furnace of the heating vaporizer 5 is set to 600 in a state where the gas switching valve 81 releases the measurement channel 8 and closes the bypass channel 9. Mercury heated and vaporized by heating to ˜800 ° C., argon gas G is allowed to flow from the carrier gas supply channel 7 at a flow rate of, for example, 0.17 L / min, and the suction pump 83 and the first flow rate control means 84 are used. For example, 0.07 L / min. The flow rate is adjusted so that the flow rate of the atomic fluorescence analyzer 6 is introduced into the measurement cell 62 and measured. A mercury analysis line is emitted from the mercury lamp 61 to the measurement cell 62 into which the sample gas S has been introduced, and the detector 63 detects the intensity of the mercury analysis line that is fluorescence generated from the mercury present in the measurement cell 62. Based on the detected intensity, the detection processing unit 64 quantifies mercury in the sample gas S. In addition, in order to vaporize only the mercury collected by the mercury collection tube 4 and not to vaporize other gases, the heating temperature at the time of mercury collection of the mercury collection tube 4 is preferably 150 to 200 ° C.

  A predetermined amount of standard sample gas S corresponding to a mercury amount of 12 ng (nanogram) is measured by the above analysis method using the mercury analyzer 1 of the first embodiment and the conventional mercury analyzer, and immediately after the measurement. The blank measurement values obtained by measuring each blank measurement twice are shown in the table below.

  As shown in the above table, the blank value measured with the mercury analyzer 1 of the first embodiment is 1/10 compared to the blank value measured with the conventional mercury analyzer, and the mercury analyzer 1 has a residual value. It can be seen that mercury is extremely low.

  As described above, in the flow path connecting part 30 of the conventional mercury analyzer, the three-way pipe 123 has the same diameter joint 121 and the joint 122, for example, a Teflon (registered trademark) pipe for sample gas having an outer diameter of 6 mm and an inner diameter of 4 mm, and mercury. The collection tube 4 is connected. For this reason, the inner diameter of the pipe is large, the contact area with the sample gas S is large, and the structure of the flow path connection portion 30 is complicated. Therefore, mercury in the sample gas S tends to remain, but the flow of the first embodiment The inner pipe 25 of the path connecting part 3 has a small inner diameter, and the hollow part 251 is a straight pipe having no joint or the like, and mercury hardly remains. Therefore, as in the first embodiment, in order to eliminate mercury from remaining in the flow path connection portion 3, the pipe of the sample gas introduction flow path 2 is the inner pipe 25, and the pipe of the carrier gas supply flow path 7 is the outer pipe. A tube 75 is preferred.

  According to the first embodiment, the sample gas introduction channel 2 and the carrier gas supply channel 7 are independent in the channel connection unit 3, and the sample gas S does not contact the carrier gas supply channel 7. Residual mercury is not contained in the carrier gas G, and mercury can be analyzed with high sensitivity and high accuracy. Further, the inner pipe 25 which is a pipe of the sample gas introduction flow path 2 is a straight pipe having a thin inner diameter, and the structure is not complicated, so that mercury in the sample gas S does not remain and adsorption is difficult to occur, thereby preventing contamination of the inner surface of the pipe. can do. Thus, since residual mercury can be eliminated and contamination can be prevented, a heating member for heating the piping is not required, and the cost can be reduced.

  Hereinafter, the mercury analyzer 10 according to the second embodiment of the present invention will be described. As shown in FIG. 1, the mercury analyzer 10 includes an atomic absorption analyzer 60 that replaces the atomic fluorescence analyzer 6 that is a mercury measuring instrument of the mercury analyzer 1 according to the first embodiment. The apparatus uses air, and the other configuration is the same as that of the mercury analyzer 1. The carrier gas supply channel 7 supplies air G, for example, an air supply source 75 that is an air compressor, a second gas flow rate control means 76 that controls the flow rate of the air G, and removes mercury in the air. And a mercury removal pipe 77. As shown in FIG. 6, the atomic absorption spectrometer 60 radiates from a mercury lamp 601 that emits a mercury analysis line to a measurement cell 602 into which mercury vaporized by heating and vaporizing apparatus 5 is introduced, and radiation from the mercury lamp 601. A detector 603 that detects the intensity of the analytical line to be detected, and a detection processing unit 604 that quantifies the mercury content in the sample gas S according to the intensity of the analytical line detected by the detector 603.

  In the mercury analysis method using the mercury analyzer 10 of the second embodiment, air G is supplied as a carrier gas from the air compressor 75 and the analysis line emitted from the mercury lamp 601 detected by the detector 603 is used. The detection processing unit 604 is the same as the method of the first embodiment except that the detection processing unit 604 quantifies the mercury content in the sample gas S according to the strength, and thus the description is omitted.

  According to 2nd Embodiment, it has the same effect | action and effect as 1st Embodiment.

  In the above embodiment, the sample gas S flows through the hollow portion 251 of the inner tube 25 and the carrier gas G flows through the tubular space 253 between the outer wall 252 of the inner tube 75 and the inner wall 752 of the outer tube 75. Although the flow path is formed, the sample gas S flows through the tubular space 253 between the outer wall 252 of the inner tube 75 and the inner wall 752 of the outer tube 75, and the carrier gas G flows through the hollow portion 251 of the inner tube 25. The flow path may be formed. Further, in the above embodiment, the wavelength non-dispersion type atomic fluorescence analyzer 6 or the atomic absorption analyzer 60 is illustrated. However, in the present invention, the wavelength dispersion type atomic fluorescence analyzer or the atomic absorption analyzer is used. May be.

It is a schematic block diagram of the mercury analyzer which is the 1st and 2nd embodiment of the present invention. It is the schematic of the flow-path connection part of the same mercury analyzer. It is sectional drawing of the flow-path connection part of the mercury analyzer. It is the schematic of the other flow-path connection part of the mercury analyzer. 1 is a schematic block diagram of an atomic fluorescence analyzer of a mercury analyzer that is a first embodiment of the present invention. It is a schematic block diagram of the atomic absorption analyzer of the mercury analyzer which is the 2nd Embodiment of this invention. It is the schematic of the flow-path connection part of the conventional mercury analyzer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 10 Mercury analyzer 2 Sample gas introduction flow path 3 30 Flow path connection part 4 Mercury collection pipe 5 Heating vaporizer 6 60 Mercury measuring device 7 Carrier gas supply flow path 8 Measurement flow path 9 Bypass flow path G Carrier gas S Sample

Claims (6)

A sample gas introduction flow path for flowing a predetermined amount of sample gas into a mercury collecting tube for collecting mercury in the sample gas;
A heating and vaporizing apparatus for vaporizing mercury by heating the mercury collecting tube in which mercury is collected;
A mercury measuring device for measuring mercury vaporized by the heating vaporizer;
A carrier gas supply flow for flowing a carrier gas for transporting the mercury vaporized by the heating vaporizer to the mercury measuring device, which is connected to the upstream side of the mercury collecting pipe in the sample gas introduction channel. Road,
A mercury analyzer for analyzing mercury in a sample gas comprising:
The flow path connecting portion is a double tube in which an inner tube passes through a hollow portion of an outer tube, and either one of a sample gas or a carrier gas flows through the hollow portion of the inner tube, and the other gas is A mercury analyzer having a double flow path that flows in a tubular space between an outer wall of an inner tube and the inner wall of the outer tube. In claim 1,
A mercury analyzer in which a sample gas flows through a hollow portion of the inner tube, and a carrier gas flows in a tubular space between the outer wall of the inner tube and the inner wall of the outer tube. In claim 1 or 2,
A mercury analyzer in which the mercury measuring instrument is an atomic fluorescence analyzer. A sample gas introduction flow path for flowing a predetermined amount of sample gas into a mercury collecting tube for collecting mercury in the sample gas;
A heating and vaporizing apparatus for vaporizing mercury by heating the mercury collecting tube in which mercury is collected;
A mercury measuring device for measuring mercury vaporized by the heating vaporizer;
A carrier gas supply flow for flowing a carrier gas for transporting the mercury vaporized by the heating vaporizer to the mercury measuring device, which is connected to the upstream side of the mercury collecting pipe in the sample gas introduction channel. Road,
Prepare
The flow path connection part is formed by a double pipe in which the inner pipe penetrates the hollow part of the outer pipe,
Either the sample gas or the carrier gas is caused to flow in the hollow portion of the inner tube, and the other gas is caused to flow in a tubular space between the outer wall of the inner tube and the inner wall of the outer tube. Mercury analysis method for analyzing mercury. In claim 4,
A mercury analysis method in which a sample gas is caused to flow in a hollow portion of the inner tube, and a carrier gas is caused to flow in a tubular space between the outer wall of the inner tube and the inner wall of the outer tube. In claim 4 or 5,
A mercury analysis method using an atomic fluorescence analyzer as the mercury measuring instrument.

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