JP2007093409A - Tvoc meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TVCO meter capable of carrying out a measurement without being affected by amounts of carbon dioxide and oxygen in a sample gas. <P>SOLUTION: An oxygen concentration of the sample gas G1 flowing at a constant rate is measured by a magnetic type oxygen meter 2, and then the sample gas G1 is burned completely in a burning catalytic oxidizing furnace 3, and an oxygen concentration of the exhausted sample gas G2 is measured by a magnetic type oxygen meter 4, and an oxygen concentration difference is obtained by inputting electric signals E1, E2 proportional to respective measured values into an arithmetic processing device 5, and then the oxygen concentration difference is subjected to an arithmetic process, thereby obtaining the concentration of total volatile organic compounds (TVOC) of the sample gas G1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a TVOC meter that measures the total (total) volatile organic compound (TVOC) concentration contained in atmospheric gas or atmospheric gas.

  TVOC refers to the total amount of volatile organic compounds of up to 11 types such as benzene, xylene, and toluene, and is used as a building material and adhesive for work sites such as painting, bonding, printing, and chemical product manufacturing in offices such as factories. The volatile organic compounds are known to be causative substances such as chemical hypersensitivity and Six House syndrome.

特に、ＴＶＯＣに対しては、０．４ｍｇ／ｍ³（新築時１ｍｇ／ｍ³）が国の暫定目標値として定められている。また、環境省告示第６１号（平成１７年６月１０日）による大気汚染防止法により、ＴＶＯＣを水素炎イオン化形分析計（ＦＩＤ計）（例えば、特許文献１参照。）または非分散型赤外線ガス分析計（ＮＤＩＲ計）を用いて測定するよう通達されている。 For this reason, for each volatile organic compound, a regulation value as an indoor environment guideline shown in Table 1 is defined as a national guideline value (see, for example, Non-Patent Document 1).

In particular, for TVOC, 0.4 mg / m ³ (1 mg / m ³ at the time of new construction) is set as a provisional target value for the country. Further, according to the Air Pollution Control Act of Ministry of the Environment Notification No. 61 (June 10, 2005), TVOC is converted into a flame ionization analyzer (FID meter) (for example, see Patent Document 1) or non-dispersive infrared. It is notified to measure using a gas analyzer (NDIR meter).

FIG. 3 shows a configuration example in the case of measuring the TVOC concentration using an FID meter. In this FID meter, the tip of a quartz nozzle 101 and a collector 102 serving as an electrode are accommodated in a reaction furnace 103, and a high voltage 104 of about 300 V is applied to the nozzle 102 to the collector 102. The sample gas G1 and the hydrogen gas H1 are supplied, and the air A1 is supplied to the reaction furnace 103. In the hydrogen flame 105 at the tip of the nozzle 101, a reaction represented by the following reaction formula is performed.
^{CH + O 2 → CHO + +} e -
That is, the volatile organic compound in the sample gas G1 burns in the hydrogen flame 105, and an ionic current proportional to the organic compound concentration is collected in the collector 102. This current is converted into a TVOC concentration by the data processing device 106 and output / displayed.

FIG. 4 shows a configuration example in the case of measuring the TVOC concentration using a single cell type NDIR meter. The NDIR meter includes a bypass channel 201 that bypasses the sample gas G1 and an oxidation catalyst channel 203 that includes an oxidation catalyst 202, a switching valve 204 that switches between the bypass channel 201 and the oxidation catalyst channel 203, and the switching valve. The sample cell 205 that stores the sample gas G1 from 204, the light source 206 that emits infrared rays, the capacitance type detector 207, and the switching valve 204 are alternately switched, and the electrical signal from the detector 207 is converted into the sample gas. The signal converter 208 performs conversion processing to the TVOC density of G1. And requests the CO ² concentration and CO ² concentration measured volatile organic compound concentration from the CO ² concentration difference of sample gas through the oxidation catalyst flow path 203 in the sample gas G1 from the bypass passage 201.

Ministry of Health and Welfare, December 22, 2000, regarding the 4th to 5th summary of the interim report of the study group on the sick house (indoor air pollution) issue JP 2003-202324 A

When the TVOC concentration is measured using the FID meter, there is a problem that the measured value changes depending on the oxygen concentration in the sample gas, that is, so-called oxygen interference occurs. Further, when the TVOC concentration is measured using an NDIR meter, there is a problem that it is difficult to measure the TVOC concentration in combustion exhaust gas in which a large amount of carbon dioxide is contained in the sample gas in principle.
The present invention has been made in view of such circumstances, and an object thereof is to provide a TVOC meter capable of measuring a TVOC concentration without being affected by oxygen or carbon dioxide contained in a sample.

  In order to achieve the above object, the TVOC meter according to the present invention includes a suction means for sucking a sample gas at a constant flow rate, a measurement means for measuring the oxygen concentration of the sucked sample gas, and an oxidation for oxidizing and burning the sample gas after measurement. Combustion means, measurement means for measuring the oxygen concentration of the sample gas after oxidative combustion, and the difference in oxygen concentration between the sample gas before and after oxidative combustion are calculated. And an arithmetic means for calculating the organic compound concentration.

  The TVOC meter of the present invention is affected by the oxygen and carbon dioxide contained in the sample gas by oxidizing and burning the sample gas, measuring the oxygen concentration before and after that with the oxygen meter, and measuring the amount of decrease in the oxygen concentration. The concentration of TVOC can be measured.

  The TVOC meter of the best mode provided by the present invention includes an inhaling means for inhaling a sample gas at a constant flow rate, a measuring means for measuring the oxygen concentration of the inhaled sample gas, and oxidative combustion for oxidizing and burning the sample gas after measurement. Means, measuring means for measuring the oxygen concentration of the sample gas after oxidative combustion, and calculating the oxygen concentration difference between the sample gas before and after oxidative combustion, and performing a correction operation on the oxygen concentration difference to calculate the total volatile organics in the sample gas And an arithmetic means for calculating the compound concentration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a TVOC meter according to an embodiment of the present invention. This TVOC meter passed through the flow rate control system 1 for sucking the sample gas G1 at a constant flow rate, the magnetic oximeter 2 for measuring the oxygen concentration O1 of the sucked sample gas G1, and the magnetic oximeter 2 A combustion catalytic oxidation furnace 3 that completely burns an organic compound in the sample gas G1 to decompose it into carbon dioxide gas and water, and a magnetic oximeter 4 that measures the oxygen concentration O2 of the sample gas G2 that has passed through the combustion catalytic oxidation furnace 3 And an arithmetic processing unit 5 that subtracts the electric signals E1 and E2 of the magnetic oximeters 2 and 4 and converts them into a TVOC concentration. The flow rate control system 1 includes a flow rate control valve 12 and a flow rate sensor 13 a disposed in the gas flow path 11, a flow rate control device 13, and a pump 14. The combustion catalyst oxidation furnace 3 includes a combustion tube 31 made of quartz glass, a platinum net 32, a quartz wool 33, a platinum catalyst 34, and the like sequentially accommodated from below.

  As the magnetic oximeters 2 and 4, a known magnetic oximeter such as a magnetic wind type donut-shaped measurement chamber type or a magnetic wind type cylindrical measurement chamber type can be used. FIG. 2 shows the configuration of a magnetic oxymeter 2 of a magnetic wind type donut-shaped measurement chamber. A glass ring cell 21, a bypass pipe 22, a coil 23, a magnet 24, and a bridge circuit 25 are shown. It is configured. The ring cell 21 is provided with a sample gas inlet 27 and an outlet 28 at symmetrical positions of a ring-shaped sample gas flow path 26. The left and right sides of the coil 23 form one side of the bridge circuit 25. The magnetic oximeter 4 has the same configuration as the magnetic oximeter 2.

  In the above configuration, the sample gas G1 is sucked by the pump 14 and the flow rate thereof is detected by the flow rate sensor 13a. This detection signal is compared with the flow rate set value in the flow rate control device 13, and the flow rate control is performed so that the set flow rate is obtained. Controlled by valve 12. When this sample gas G1 is caused to flow from the inlet 27 to the outlet 28 of the magnetic oximeter 2, the oxygen in the sample gas G1 is attracted by the magnetic field formed by the magnet 24, thereby causing the oxygen inside the bypass pipe 22 to be viewed from the left. Oxygen magnetic wind is generated in the right direction, a difference occurs between the left and right resistance values of the coil 23, and an unbalanced voltage is detected as the electric signal E1. Since the electric signal E1 is detected for the sample gas G1 having a constant flow rate, the magnitude thereof is proportional to the oxygen concentration O1.

  The sample gas G1 sent from the magnetic oximeter 2 is then supplied to the combustion catalytic oxidation furnace 3. This sample gas G1 comes into contact with the platinum catalyst 34 in the combustion catalyst oxidation furnace 3 and burns at a complete combustion temperature of about 680 ° C., and the sample gas G1 combines carbon dioxide with a part of oxygen combined with a volatile organic compound. And converted into water to become the sample gas G2 and supplied to the magnetic oximeter 4.

The sample gas G2 is detected by the magnetic oximeter 4 as an electric signal E2 proportional to the oxygen concentration O2 by the same measurement method as the magnetic oximeter 2. The electric signals E1 and E2 are subtracted (E1−E2) by the arithmetic processing unit 5 and the difference ΔE is input to, for example, the following arithmetic expression (1) obtained experimentally in advance to calculate the TVOC concentration. Is output and displayed.
Y = f (ΔE) (1)
In the above equation, Y represents the TVOC concentration, and f (ΔE) represents a function of ΔE.

  The configuration of the TVOC meter of the present invention is not limited to the above embodiment, and various oximeters including a known zirconia oximeter can be used for measuring the oxygen concentration in the sample gases G1 and G2, for example. Moreover, you may accommodate the component shown in FIG. 1 in one housing | casing. When the amount of oxygen in the sample gas is small, oxygen or air may be added to the sample gas and supplied.

  The present invention is used for measuring the concentration of TVOC in a gas emitted from a work site such as painting, bonding, printing, and chemical product manufacturing at a business site such as a factory, or from building materials or adhesives in a house.

It is a figure which shows the structure of the TVOC meter by an Example. It is a figure which shows the structure of the magnetic-type oximeter concerning an Example. It is a figure which shows the structural example in the case of measuring TVOC density | concentration using an FID meter. It is a figure which shows the structural example in the case of measuring TVOC density | concentration using an NDIR meter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow control system 2 Magnetic oxygen meter 3 Combustion catalyst oxidation furnace 4 Magnetic oxygen meter 5 Arithmetic processing device 11 Gas flow path 12 Flow control valve 13 Flow control device 13a Flow sensor 14 Pump 21 Ring cell 22 Bypass pipe 23 Coil 24 Magnet 25 Bridge circuit 26 Sample gas flow path 27 Inlet 28 Outlet 31 Combustion pipe 32 Platinum net 33 Quartz wool 34 Platinum catalyst 101 Nozzle 102 Collector 103 Reactor 104 High voltage 105 Hydrogen flame 106 Data processing device 201 Bypass flow path 202 Oxidation catalyst 203 Oxidation Catalyst flow path 204 Switching valve 205 Sample cell 206 Light source 207 Detector 208 Signal converter A1 Air E1, E2 Electrical signal G1, G2 Sample gas H1 Hydrogen gas

Claims (1)

Inhalation means for inhaling the sample gas at a constant flow rate, measurement means for measuring the oxygen concentration of the inhaled sample gas, oxidation combustion means for oxidizing and burning the sample gas after measurement, and oxygen concentration of the sample gas after oxidation combustion Measuring means for measuring, and calculating means for calculating the difference in oxygen concentration of the sample gas before and after oxidative combustion and calculating the total volatile organic compound concentration in the sample gas by correcting the difference in oxygen concentration TVOC meter characterized by

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