JPH0115816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sulfur dioxide gas analyzer. especially,
The present invention relates to a gas analyzer that can be used to analyze trace amounts of sulfur dioxide gas in gas.

The conventional trace sulfur dioxide gas analyzer in gas is
After oxidizing sulfur dioxide gas and dissolving it in the form of sulfuric acid in an absorption liquid, the conductivity of sulfuric acid in this absorption liquid is measured,
This method uses a method to analyze sulfur dioxide gas. This method does not use any chemicals other than an oxidizing agent, has a simple detection mechanism, and has the advantage of being able to detect with high sensitivity. However, this method has the drawback that if a substance that dissolves in the absorption liquid and becomes ionized coexists in the gas, the measurement results are greatly influenced by the coexisting substance. For example, if the gas contains 0.1 ppm of hydrochloric acid or hydrochloric acid, the sulfur dioxide concentration determined from the electrical conductivity will have a positive error of 0.05 ppm.

In view of the above circumstances, the present invention eliminates the above-mentioned drawbacks while taking advantage of the advantages of the conventional conductivity measurement method, and even if there are coexisting substances that can be ionized, such as chlorides and fluorides, in the gas, these coexist. The purpose of the present invention is to provide a sulfur dioxide gas analyzer that can obtain correct measurement values without being affected by substances.

In order to achieve this objective, the sulfur dioxide gas analyzer of the present invention includes a cation converter that converts all cations in the gas absorption liquid into hydrogen ions, and a cation-converted ion converter by the cation converter. Coexistence of a conductivity measurement section that measures the electrical conductivity of a test solution, a coexistence anion measurement section that selectively detects and measures coexisting anions other than sulfate ions in the test solution, and the coexistence anion measurement section. The apparatus further includes a correction device that corrects the measurement results of the conductivity measurement section based on the anion detection results.

Hereinafter, an example of implementation of the present invention will be described with reference to the drawings.

In the figure, numeral 1 is the sample gas intake port, and numeral 2 is the sample gas intake port.
is the absorption liquid inlet. The sample gas is sucked by the gas suction unit 7, sucked through the intake port 1, and mixed with the absorption liquid introduced from the absorption liquid introduction port 2 in the mixer 3 by spraying the absorption liquid into the gas. . The absorption liquid in this example uses water and contains hydrogen peroxide as an oxidizing agent. Therefore, the sulfur dioxide gas present in the sample gas in the mixer 3 is oxidized by the oxidizing agent to become sulfuric acid, which is absorbed into the absorption liquid. At this stage, components other than sulfur dioxide gas in the sample gas are partially dissolved and absorbed in the absorption liquid. The absorbed liquid and unabsorbed gas are led to a gas-liquid separator 5 through a pipe 4, where they are separated into gas and absorbed liquid. Of these, the gas is discharged from the gas pipe 6 through the gas suction section 7 and from the gas discharge port 8. On the other hand, the suction liquid will be guided to the cation exchange device 10.

That is, the absorption liquid separated from the gas is led to the cation exchange device 10 by the absorption liquid introduction pipe 9, and here, in the device 10, all the cations of the components dissolved in the absorption liquid from the sample gas and ionized are removed. exchanged into hydrogen ions.

The ion-exchanged absorption liquid, that is, the test liquid, is transferred to pipe 1.
1 to the conductivity measuring section 12, where the conductivity is measured. Next, it is led to the coexisting anion measuring section 14 through the pipe 14, where the coexisting anion concentration is measured. Thereafter, it is discharged from the absorption liquid discharge port 15.

The electrical conductivity measuring section 12 measures the electrical conductivity of sulfuric acid in the test liquid, and the sulfur dioxide gas in the original gas can be analyzed based on this measured value. However, as described above, the measurement performed by the measurement unit 12 causes a positive error if the sample contains chlorine ions or fluorine ions due to coexisting substances in the gas. Therefore, in order to compensate for the influence of coexisting ions in the test liquid derived from such coexisting substances, the coexisting anion measuring section 14 selectively detects and measures coexisting anions. Therefore, for example, a chloride ion selective electrode and a reference electrode are used in the coexistence anion measuring section 14, and a chloride ion potential proportional to the logarithm of the chloride ion concentration in the sample is measured by immersing these in the sample. By calculating the concentration from this measured value and compensating for the influence of conductivity from this concentration value,
The influence of hydrochloric acid in gas on analysis can be removed. Further, it is also possible to use a fluorine ion selective electrode in the coexisting anion measuring section 14 to eliminate the influence of fluorine acid in the gas. In addition to the coexisting anions whose concentration can be selectively measured using the ion electrode, this method also enables selective measurement of other anions derived from other coexisting substances in the gas depending on the properties of the gas to be measured. By configuring the coexisting anion measuring section 14, it is possible to correct the influence of coexisting substances on the measured values.

In the present invention, as described above, the measurement results of the conductivity measurement section 12 are corrected based on the coexistence anion detection results in the coexistence anion measurement section 14.
A correction device for this purpose is constituted by an arithmetic device 18 in this example.

That is, as shown in the figure, the measured value at the conductivity measuring section 12 is transmitted to the computing device 18 via the signal line 16, and the measured value at the coexisting anion measuring section 14 is also transmitted to the computing device 18 via the signal line 17. This computing device 18
Now, we calculate the influence of coexisting anions on conductivity measurement based on the detected measured values of coexisting anions.
This value is subtracted from the value measured by the conductivity measuring section 12.
Correction is made by such an operation, and a measured value that is accurately proportional to the sulfuric acid concentration in the absorption liquid (test liquid) can be obtained. Therefore, this is converted to the sulfur dioxide gas concentration in the sample gas, and this result is connected to the signal line 19.
The concentration is then transmitted to the display section 20, where the concentration is displayed and the analysis results are output.

In the above embodiment, when a column packed with a cation exchange resin is used in the cation exchange device 10, 99% or more of the cations in the absorption liquid are converted into hydrogen ions. Therefore, the measured value of conductivity is obtained as a value approximately proportional to the amount of anions, and furthermore, this can be almost completely corrected by the measured value of coexisting cations.

In addition, in the above embodiment, when a chlorine ion selective electrode and a fluorine ion selective electrode are used in the coexisting anion measuring section 14, even when analyzing a trace amount of sulfur dioxide gas containing 0.1 ppm of hydrochloric acid or hydrofluoric acid, We were able to reduce the error to 0.005ppm or less.

In the above example, the sulfur dioxide gas was oxidized using the oxidizing agent contained in the absorption liquid in the mixer 3, but at any stage before entering the cation exchanger 10, any Oxidation may be performed by any method. In addition, after the test liquid is measured in the conductivity measurement unit 12, it is measured in the coexisting anion measurement unit 14, but since this is the measurement of the same test liquid, simultaneous measurements may be performed, and the order may be changed. It's also good. The same applies when a plurality of coexisting anion measuring sections 14 are provided or a plurality of electrodes are provided in order to detect various kinds of coexisting anions.

As detailed above, the sulfur dioxide gas analyzer of the present invention includes a cation converter that converts all the cations in the gas absorption liquid into hydrogen ions, and an electric current of the sample liquid ion-converted by the cation converter. A conductivity measurement section that measures conductivity, a coexistence anion measurement section that selectively detects and measures coexisting anions other than sulfate ions in the same sample solution, and coexistence anion detection results from the coexistence anion measurement section. The present invention is characterized in that it is equipped with a correction device for correcting the measurement results of the conductivity measurement section, so that no chemicals other than an oxidizing agent are used, and the detection mechanism is simple.
While taking advantage of the conventional advantage of high detection sensitivity, this method has the effect of obtaining accurate analytical measurement results without being affected by coexisting substances that can be ionized in the gas. Therefore, even if halides such as hydrogen chloride and hydrogen fluoride are present in addition to sulfur dioxide gas, the effects of these can be removed by correction, which is highly effective in practical use. It can also be said that it can be suitably used for measuring trace amounts of sulfur dioxide gas in a gas containing coexisting substances that become anions.

It should be noted that, as a matter of course, the present invention is not limited to the illustrated embodiment.

[Brief explanation of drawings]

The drawing is a block diagram showing an example of the implementation of the sulfur dioxide gas analyzer according to the present invention. 10... Cation exchange device, 12... Conductivity measuring section, 14... Coexisting anion measuring section, 18... Correction device (computation device).

Claims (1)

[Scope of Claims] 1. An analyzer for analyzing sulfur dioxide gas in a gas, which includes a cation conversion device that converts all cations in a gas absorption liquid into hydrogen ions, and a cation conversion device that converts ions into hydrogen ions by the cation conversion device. A conductivity measurement section that measures the electrical conductivity of the test solution, a coexistence anion measurement section that selectively detects and measures coexisting anions other than sulfate ions in the test solution, and coexistence by the coexistence anion measurement section. A sulfur dioxide gas analyzer comprising: a correction device for correcting the measurement result of the conductivity measuring section based on the anion detection result. 2. The sulfur dioxide gas analyzer according to claim 1, wherein the correction device is an arithmetic device that corrects the measurement results of the conductivity measuring section based on the detection results of coexisting anions. 3. The sulfur dioxide gas analyzer according to claim 1 or 2, wherein the coexisting anion measuring section has at least one ion selection electrode. 4. The sulfur dioxide gas analyzer according to claim 3, wherein the ion selective electrode is a chlorine ion selective electrode or a fluorine ion selective electrode.