JP3777786B2 - Total nitrogen meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a TN meter that measures TN (total nitrogen) in an aqueous solution sample. In particular, the present invention converts nitrogen (N) in a sample into NO (nitrogen monoxide) and emits light by reaction between ozone and NO. The present invention relates to a chemiluminescence type (chemiluminescence, abbreviated to chemilumine or CLM) TN meter for measuring TN. The CLM type TN meter may be incorporated in a water quality analyzer having a function of analyzing other components other than TN such as TOC (total organic carbon) and TC (total carbon) contained in a sample.
The TN meter is used as a TN monitor for monitoring nitrogen components contained in sewage and river water, or as a TN monitor in a sea area where environmental standards are established or in a factory where drainage standards are established. Yes.
[0002]
[Prior art]
The CLM type TN meter is an oxidation reaction part that converts a nitrogen component in a sample into NO, a sample injection part that collects a certain amount of an aqueous solution sample and injects it into the oxidation reaction part, and supplies a carrier gas to the oxidation reaction part A carrier gas supply unit, and a NO detection unit that includes an ozone generator and measures luminescence due to the reaction between ozone supplied from the ozone generator and NO in the sample vaporized gas sent together with the carrier gas from the oxidation reaction unit It has. Furthermore, an ozonolysis device is provided for removing ozone in the exhaust gas from the NO detection section by a catalyst containing activated carbon, manganese dioxide, or the like. Examples of the conversion method of the oxidation reaction part include a conversion by combustion, a conversion by a reagent, and a conversion by ultraviolet rays.
[0003]
NOx (nitrogen oxides) such as NO and NO ₂ (nitrogen dioxide) is contained in the exhaust gas from the NO detector, and this NOx is adsorbed on the catalyst of the ozone decomposer and the life of the catalyst is shortened. was there. In order to solve such problems, the catalyst is heated to about 100 ° C. to suppress NOx adsorption on the catalyst.
In a CLM type TN meter equipped with a combustion furnace in the oxidation reaction section, the temperature of the combustion furnace is about 600 to 900 ° C., so the heat of the combustion furnace is used to heat the catalyst of the ozone decomposer to about 100 ° C. is doing.
In addition, in a CLM TN meter that does not include a heat supply means such as a combustion furnace, a temperature increasing device such as a furnace is separately attached to increase the temperature of the catalyst of the ozonolysis device.
[0004]
[Problems to be solved by the invention]
In the CLM type TN meter that uses the heat of the combustion furnace to heat the catalyst of the ozonolysis device, the temperature of the combustion furnace is about 600 to 900 ° C., and this heat is directly used for heating the catalyst of the ozonolysis device. Is too hot. Therefore, the ozonolysis device has to be installed at a position where the temperature of the catalyst of the ozonolysis device is about 100 ° C., and there is a restriction on the structure of the apparatus.
Further, in the method of heating the catalyst of the ozonolysis apparatus to prevent NOx adsorption, NOx, which is a harmful gas, is released as it is, so that an exhaust facility for absorbing or decomposing NOx is required.
[0005]
Accordingly, the object of the present invention is to suppress the release of NOx and the decrease in the life of the catalyst of the ozonolysis device in the CLM type TN meter.
[0006]
[Means for Solving the Problems]
The total nitrogen meter according to the present invention comprises an oxidation reaction unit that converts nitrogen compounds in an aqueous solution sample into nitric oxide, ozone supplied from the ozone generator and a carrier gas from the oxidation reaction unit. A detection unit equipped with a chemiluminescence type nitric oxide detector that measures light emission by reaction with nitrogen monoxide in the sample vaporized gas, and nitrogen that removes nitrogen oxides contained in the exhaust gas from the detection unit And an exhaust gas treatment unit provided with an ozonolysis device for removing ozone in the exhaust gas from the oxide absorber and the nitrogen oxide absorber.
[0007]
A nitrogen compound in the aqueous solution sample is converted to NO in the oxidation reaction unit, and the NO and ozone supplied from the ozone generator are reacted in the detection unit. The exhaust gas from the detection unit contains NO, NO ₂ , ozone, and the like. NOx such as NO and NO ₂ in the exhaust gas is absorbed and removed by a nitrogen oxide absorber, and ozone in the exhaust gas is removed by an ozone decomposer and then discharged.
[0008]
【Example】
FIG. 1 schematically shows an embodiment in which the present invention is applied to a TN / TOC meter. The TN / TOC meter detects TOC and TN in the same sample by a series of operations.
Reference numeral 2 denotes an oxidation reaction section, in which a quartz glass combustion tube 6 filled with a metal oxide or an oxidation catalyst 4 of a noble metal catalyst is heated to a predetermined temperature by an electric furnace 8. A certain amount of aqueous solution sample is collected by a sample sampling unit (not shown) and injected into the combustion tube 6 from above. The aqueous solution sample injected into the combustion tube 6 contacts the heated oxidation catalyst 4 to be thermally decomposed and vaporized, and the nitrogen component in the sample is converted to NO. At the same time, the carbon component (C) is converted to CO ₂ (carbon dioxide). ). From the upper part of the combustion pipe 6, purified air from which carbon has been removed is controlled at a constant flow rate and supplied as a carrier gas.
[0009]
The sample gas vaporized in the combustion tube 6 is sent by a carrier gas, and is guided to a non-dispersive infrared CO ₂ meter (hereinafter abbreviated as NDIR) 10 as a CO ₂ detector via a dehumidifying part (not shown). ₂ concentration is measured. The sample gas that has passed through the NDIR 10 is guided to the CLM type NO meter 12, and chemiluminescence generated by the reaction of NO in the sample gas with ozone supplied from the ozone generator 14 is detected, and the NO concentration is measured. The The sample gas that has passed through the CLM-type NO meter 12 passes through, for example, NOx absorber 16 filled with granular soda lime that absorbs NOx in the sample gas, and further removes ozone, for example, as activated carbon and a catalyst. It is discharged through an ozonolysis device 18 filled with manganese dioxide.
[0010]
Air is led to the ozone generator 14 as an ozone source. After some oxygen molecules contained in the air are converted into ozone by the ozone generator 14, the air containing ozone is guided to the CLM type NO meter 12 and mixed with the sample gas. The mixed gas of the sample gas and air that has passed through the CLM type NO meter 12 is exhausted through the NOx absorber 16 and the ozone decomposer 18.
[0011]
Next, the operation of this embodiment will be described.
The oxidation catalyst 4 in the combustion tube 6 is heated to a predetermined temperature of 680 to 900 ° C. by the electric furnace 8, and purified air is supplied as a carrier gas to the combustion tube 6 at a flow rate of 150 ml / min, for example. In this state, 100 μl of the aqueous solution sample is collected by a syringe or the like by the sample sampling unit and injected into the combustion tube 6. The nitrogen component in the aqueous solution sample is converted to NO, and the carbon component is converted to CO ₂ . The sample gas vaporized in the combustion tube 6 is sent by the carrier gas, and is guided to the NDIR 10 through a dehumidifying section (not shown) to measure the CO ₂ concentration. Thereafter, the sample gas is guided to the CLM type NO meter 12, and the ozone supplied from the ozone generator 14 reacts with NO in the sample gas to measure the NO concentration.
[0012]
The exhaust gas from the CLM type NO meter 12 contains NO ₂ , ozone, and a small amount of NO. NOx such as NO and NO ₂ in the exhaust gas is absorbed by the NOx absorber 16, ozone in the exhaust gas is removed by the ozone decomposer 18, and then discharged. Since NOx is removed from the exhaust gas sent from the NOx absorber 16 to the ozonolysis device 18, NOx is not adsorbed on the catalyst of the ozonolysis device 18, and the lifetime reduction of the catalyst of the ozonolysis device 18 is suppressed. Can do.
[0013]
In this embodiment, the present invention is applied to a TN / TOC meter. However, the present invention is not limited to this. For example, a TN meter in which NDIR is omitted from the embodiment may be used. You may combine.
Further, in this embodiment, an oxidation reaction section provided with a combustion furnace that converts a nitrogen component into NO by combustion is used. However, the present invention is not limited to this. For example, an oxidation reaction section that converts by a reagent or ultraviolet rays is used. May be used.
[0014]
【The invention's effect】
In the total nitrogen meter according to the present invention, a NOx absorber is provided between the CLM type NO meter and the ozonolysis device. Since it is sent, it is possible to prevent NOx from being adsorbed on the catalyst of the ozonolysis device and shortening the life of the catalyst. Further, since harmful gases such as NOx and ozone are processed in the apparatus, no exhaust equipment is required, and the system can be used in an environment without exhaust equipment.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing an embodiment in which the present invention is applied to a TN / TOC meter.
[Explanation of symbols]
2 Oxidation reaction section 4 Oxidation catalyst 6 Combustion tube 8 Electric furnace 10 Non-dispersive infrared CO ₂ meter (NDIR)
12 Chemiluminescence NO meter (CLM NO meter)
14 Ozone generator 16 NOx absorber 18 Ozone decomposer

Claims (1)

An oxidation reaction part that converts nitrogen compounds in the aqueous solution sample into nitric oxide;
A chemiluminescent nitric oxide which has an ozone generator and measures luminescence due to the reaction between ozone supplied from the ozone generator and nitrogen monoxide in the sample gas sent from the oxidation reaction section together with the carrier gas. A detector with a detector;
A nitrogen oxide absorber that removes nitrogen oxides contained in the exhaust gas from the detection unit, and an exhaust gas treatment unit that includes an ozone decomposition unit that removes ozone in the exhaust gas from the nitrogen oxide absorber. Total nitrogen meter.

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