JPS6258163A - Analyzer for sulfur compounds in process gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an analyzer for separating and quantifying sulfur compounds in process gases by component on-line.

Conventional technology Sulfur compounds contained in process gases can cause catalyst poisoning,
Since it causes corrosion, air pollution, etc., it is necessary to accurately understand its components and concentration.

The Japanese Industrial Standards specify methods for analyzing sulfur compounds such as total sulfur oxides, sulfur dioxide, carbon disulfide, and mercaptans in exhaust gas. Among these, as a representative example,
The analysis method for total sulfur oxide and sulfur dioxide is described below.

The total sulfur oxides were analyzed by the following method.

■Neutralization titration method: A method in which the sample gas is combusted, absorbed into hydrogen peroxide solution to convert sulfur oxides into sulfuric acid, and then titrated with sodium hydroxide solution.

■Precipitation titration method: After the sample gas is combusted, it is absorbed into a hydrogen peroxide solution to convert the sulfur oxide to sulfuric acid, then isopropyl alcohol and acetic acid are added, and titration is performed with a barium acetate solution using arsenazo■ as an indicator.

■Nephelometry: After the sample gas is burned, it is absorbed into a hydrogen peroxide solution to convert the sulfur oxide to sulfuric acid, then a glycerin solution and a sodium chloride solution are added, and barium chloride is added while stirring to create a white cloud due to barium sulfate. wavelength 420
A method of measuring absorbance near nm.

Sulfur dioxide was analyzed using a continuous analysis method using a moving measuring instrument.

(D solution conductivity method: A method in which a sample gas is absorbed into a sulfuric acid acidified hydrogen peroxide solution using a solution conductivity analyzer to measure changes in the conductivity of the solution.

■Infrared absorption method: A method that uses an infrared gas analyzer to introduce a sample gas into a cell and measure the light absorption of sulfur dioxide at around 7300 nm.

■Ultraviolet absorption method: A method of measuring the light absorption of sulfur dioxide at 280 to 320 nm using a 4-ultraviolet gas analyzer and introducing a sample gas into a cell.

■Flame photometric detection method: A method that uses a flame photometric detection analyzer to measure the luminescence intensity around 394 nm observed when a sample gas is diluted with air or nitrogen and introduced into a hydrogen flame.

■Potential-type solution method Using a two-potential electrolytic analyzer, the sample gas is introduced into the electrolytic cell through a gas-permeable diaphragm, and the sulfur dioxide diffused and absorbed into the electrolyte is electrolyzed at a predetermined oxidation potential. How to measure current.

However, although the above-mentioned method can measure all sulfur oxides or each component, when the sample gas contains many types of sulfur compounds, it is not possible to quantify the sulfur compounds as components.

Therefore, a method using a gas chromatograph equipped with a flame photometric detector has been attempted as a method for quantifying the various sulfur compounds contained in gas as components, and this method also enables online measurement. There is expected.

Problems to be Solved by the Invention However, according to the research of the present inventor, even with a method using a gas chromatograph equipped with a flame photometric detector,
You will face problems such as:

That is, the characteristic of the flame photometric detector is that the peak height on the chart is the square of the concentration, so the quantification range is relatively narrow. Therefore, for example, groups such as carbonyl sulfide, hydrogen sulfide, and carbon disulfide, which have short retention times and relatively high concentrations in a gas chromatograph separation column, coexist with groups such as thiophene, which have long retention times and low concentrations. When determining the sampling amount for process gases with the aim of quantifying the former group, the peak of the latter group becomes extremely small, making it difficult to quantify. If the sampling amount is set to 2, the former peak will scale over and quantification will become impossible.

In view of this situation, the present invention was made with the aim of finding an analytical device that can easily and accurately quantify sulfur compounds online even in systems where sulfur compounds of both groups are mixed.

Means for Solving the Problems The apparatus for analyzing sulfur compounds in process gas of the present invention has the following features:
From the process gas flow path (1) to the sampling pipe (2)
After sampling the measurement gas with a sampler (5), the measurement gas is supplied to a separation column (7) of a gas chromatograph equipped with a flame photometric detector (8) to separate each component and remove the measurement gas. In the apparatus for quantifying sulfur compounds in the sample, the sampling conduit (2) is provided with an acid treatment section (3), and the sampler (5) is provided with a plurality of concealment tubes (6) having different capacities. It is characterized by this.

Examples of the process gas include general chemical plant gas, coal chemical plant gas, petrochemical blunt gas, petroleum refinery plant gas, and natural gas. Depending on the type of gas, these process gases contain sulfur compounds such as hydrogen sulfide, carbon disulfide, sulfur disulfide, sulfur hexafluoride, dimethyl sulfide, ethyl methyl sulfide,
Diethyl sulfide, dimethyl disulfide, diethyl disulfide, thiophene, 3-methylthiophene, 2
- Sulfur compounds such as ethylthiophene, methyl mercaptan, ethyl mercaptan, dimethyl mercaptan, n-propyl mercaptan, inbutyl mercaptan, n-butyl mercaptan, thiophenol are contained in high or low concentrations. The present invention attempts to quantify these sulfur compounds for each individual component at once.

In the present invention, the measurement gas is sampled from the process gas flow path (1).1. At that time, an acid treatment section (3) is provided in the sampling pipe (2).

This acid treatment section (3) is to prevent hydrogen sulfide contained in the process gas from adhering to the pipe line in the sample measurement system, and if this acid treatment section (3) is missing, sulfur in the gas will Compounds cannot be quantified accurately. Acid treatment section (
3) 1 Usually consists of a filter in which phosphoric acid or other acid is supported on a suitable carrier such as glass fiber, but when the process gas contains a large amount of alkaline content, an aqueous solution of the acid is passed through the gas. It is preferable to use a washing bin method in combination.

The measurement gas that has passed through the acid treatment section (3) is sampled by a sampler (5). When supplying the measurement gas to the sampler (5), a switching cock (4) is provided to supply the gas from the plurality of process gas channels (1) to the sampler (5).
5) is advantageous.

According to the present invention, the sampler (5) is provided with a plurality of measuring tubes (6) having different capacities, thereby making it possible to sample a small volume of measurement gas and a large volume of measurement gas. There is no limit to the number of measuring tubes (6) as long as they are plural, but usually 2 to 3.
Often individual.

The measurement gas sampled in the small/large capacity metering tube (6) is sequentially transferred to the separation column (7) of a gas chromatograph equipped with a flame photometric detector (8) by introducing a carrier gas.
), where each component of the sulfur compound is separated, and the sulfur compound is quantified using an attached flame photometric detector (8).

The detection result of the flame photometric detector (8) is calculated by a computer (9), and the sulfur compound is determined thereby.

In order to automatically perform the above series of operations, the operation of the switching cock (4) and the operation of the sampler (5) are controlled by signals from the computer (9).

Function In the present invention, the acid treatment section (3) provided in the sampling pipe (2) serves to prevent hydrogen sulfide contained in the process gas from adhering to the pipe in the sample measurement system.

Furthermore, a small volume of measurement gas and a large volume of measurement gas are sampled by the plurality of measuring tubes (6) with different capacities provided in the sampler (5), and these measurement gases are transferred to the separation column (7). Continuous injection becomes possible.

The measurement gas continuously injected into the separation column (7) is
Here, each component is separated, and then a flame photometric detector (8)
Each component of the sulfur compound is quantified.

Example Next, the present invention will be explained in more detail with reference to Examples.

Example 1 FIG. 1 is a schematic diagram showing an example of an analyzer of the present invention.

Reference numerals (la) and (lb) are process gas channels through which process gas flows, and (2a) and (2b) are sampling pipes.

(3a) and (3b) are acid treatment parts, which are composed of filters made of glass fiber soaked in phosphoric acid, and are respectively connected to the sampling pipe (2a'),
It is installed near the entrance of (2b).

(4) is a sample switching cock, which enables switching between the gases from the above two systems.

(5) is a hexagonal cock-type sampler, and is equipped with a U-shaped 200 uLsLc7) small-capacity measuring tube (6a) and a U-shaped 2 ml large-capacity measuring tube (8b).

(7) is a separation column for a gas chromatograph, and by introducing carrier gas into the sampler (5) from the carrier gas supply path (10), it is connected to the small and large measuring tubes (f3a) and (eb). The sampled measurement gas can be supplied to this separation column (7).

(8) is a flame photometric detector, (11) is a combustion hydrogen line for obtaining a flame, and (14) is an auxiliary combustion air line.

(9) is a computer that calculates the detection results of this flame photometric detector (8) to quantify sulfur compounds, and controls the operation of the switching cock (4) and the sampler (5) at the same time as processing the data. It also plays a role.

In addition, (12) is a combustible gas detector installed as necessary,
(13a), (13b), and (13c) are emergency shutoff valves, which are designed to urgently shut off the combustible gas line outdoors when flammable gas is detected indoors.

In addition, sampling pipes (2a) and (2b)
, switching cock (4), sampler (5), small and large measuring tubes (6a), (eb), and separation column (7) are all made of fluorine resin to prevent hydrogen sulfide adsorption. Choose the one made by the manufacturer.

Using the above analyzer, the sulfur component in coke oven gas containing carbonyl sulfide (CO8), hydrogen sulfide (H2S), carbon disulfide (cs2゜) and thiophene CC4H4S) was analyzed using the following procedure. The method was followed.

First, the gas taken out from the process gas flow path (1d) is passed through an acid-treated filter (3a) provided in the sampling pipe (2a) to remove alkali content, mist, and dust from the gas.

The measurement gas that has passed through the filter (3a) is selected by a sample switching cock (4) and guided to a small volume metering tube (6a) attached to a sampler (5).

By rotating the sampler (5), the large capacity metering tube (6b) attached to the sampler (5) is
) and at the same time introduce the measurement gas into the small volume metering tube (6).
The measurement gas in a) is introduced into the separation column (7) by the carrier gas introduced from the carrier gas supply path (10).

Then, by rotating the sampler (5), the sampler (5) receives the J! At the same time as introducing the constant gas, the measurement gas in the measuring tube (6b) with a large capacity is introduced into the separation column (7) by means of the gear gas introduced from the carrier gas supply path (10).

That is, the measuring gas in the small-capacity metering tube (6a) and the measuring gas in the large-capacity metering tube (6b) are successively introduced into the separation column (7).

The sulfur compounds in these measurement gases are collected in a separation column (7
) and then separated into individual components by a flame photometric detector (8).
The detection result is calculated by a computer (9).

2 is a chart showing the analysis results in Example 1 described above.

In the figure, the number following the "x" is the reduction ratio of the figure, and the other numbers are the retention time (from when the sample gas is injected into the separation column (7) until each component is separated and its peak appears). It shows the time (unit: minutes).

From FIG. 2, it can be seen that high concentrations of CO3, H2,
It can be seen that even in a gas containing a mixture of S, C52, and low concentrations of C+H and S, all the sulfur compounds can be easily fixed.

If you go online and repeat the above operations, the process gas flow path (1
a) It is possible to determine A11l on-line for each component in the process gas flowing therethrough.

If you want to quantify the sulfur compounds in the process gas flowing through another process gas flow path (]b), rotate the switching cock (4) to adjust the process gas in the process gas flow path (1b). The sample may be guided through the filter (3b) to the sampler (5), and the same operation as above may be performed.

Since the operation of the switching cock (4) is also controlled by the signal from the calculator (9), two process gas flow paths (la)
, (lb) can be measured online.

Comparative Example 1 A sampler (5) equipped with only a small-capacity measuring tube (6a) was used, and gas sampled through the measuring tube (6a) was injected into a separation column (7) for analysis.

FIG. 3 is a chart showing the analysis results for Comparative Example 1.

From Figure 3, we can see that the high concentration components are CO3, H2, and 5C32.
It can be seen that it is possible to quantify CyaH4S, which is a low concentration component, but it is impossible to quantify CyaH4S.

Comparative Example 2 A sampler (5) equipped with only a large-capacity measuring tube (6b) was used, and the gas sampled through the measuring tube (6b) was injected into the separation column (7) for analysis.

FIG. 4 is a chart showing the analysis results for Comparative Example 2.

From Figure 4, it is possible to quantify the low concentration components C and H4S, but the high concentration components COS, H2, S, and C32.
It can be seen that scale over occurs and it is impossible to maintain a fixed t.

Effects of the Invention In the present invention, since a plurality of measuring tubes with different capacities are provided in the sampler, the sensitivity is high but constant (J i). However, the narrow quantification range can be overcome.For example, a group of sulfur compounds with a short retention time and relatively high concentration in a gas chromatograph separation column, and a group with a relatively high concentration of sulfur compounds with a long retention time on a gas chromatograph separation column. Even for process gases that contain a mixture of compound groups, the gas sampled in a small volume metering tube and the gas sampled in a large volume metering tube can be continuously injected into the separation column. Therefore, all the sulfur compounds can be easily quantified.

In addition, since a gas chromatograph is used, sulfur compounds can be separated quickly and with high precision using a small amount of sample.

Therefore, according to the present invention, sulfur compounds in a process gas can be measured online for each individual component.

In addition, since the gas from the process gas flow path is made to pass through the acid treatment section, the alkaline components in the gas are neutralized and removed, and there is almost no dissolution into the condensate in the pipe, which prevents the generation of condensate. There is no need to heat the pipes.

Since the analyzer of the present invention has such various advantages, it has great practical significance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the analyzer of the present invention. FIG. 2 is a chart showing the analysis results in Example 1. FIG. 3 and FIG. 4 are charts showing the analysis results in Comparative Example 1 and Comparative Example 2, respectively. (1), (la), (lb)...process gas flow path, (2), (2a),
(2b)...Sampling pipe line, (3),
(3a), (3b) --- acid treatment section, (4)
・Tumble switching cock, (5)... Sampler, (6
)...Measuring tube, (8a)...Small capacity measuring tube, (
6b)...Large capacity measuring tube, (7)...Separation column, (8)...Flame photometric detector, (9)...Calculator,
(10)...Carrier gas supply path, (11)...
Combustion hydrogen line, (12)... combustible gas detector,
(13a), (13b), (13c)...Emergency shutoff valve, (14)...Air line for auxiliary combustion Fig. 2 y Fig. 3 Q Fig. 4

Claims (1)

[Claims] 1. From the process gas flow path (1) to the sampling pipe (
After sampling the measurement gas by the sampler (5) through 2), the measurement gas is supplied to a separation column (7) of a gas chromatograph equipped with a flame photometric detector (8) to separate each component and measure it. In the apparatus for quantifying sulfur compounds in gas, the sampling pipe (2) is provided with an acid treatment section (3), and the sampler (5) is provided with an acid treatment section (3).
An apparatus for analyzing sulfur compounds in a process gas, characterized in that a plurality of measuring tubes (6) of different capacities are provided in the apparatus.