JPH08210954A - Method and device for collecting so3 gas in exhaust gas, and method and device for analyzing so3 concentration - Google Patents

Abstract

PURPOSE: To precisely measure SO3 concentration in exhaust gas within a short time in a device for passing the exhaust gas collected by a gas collecting pipe connected to a flue through a spiral tube kept at a temperature lower than sulfuric acid dew point, utilizing the inertial colliding action in the spiral tube to concentrate the SO3 gas in the exhaust gas, washing off the liquefied sulfuric acid component adhered to a sampling line with washing solution to provide a fixed quantity of an analyzing sample solution. CONSTITUTION: A compressed air is supplied to the top end of a gas collecting pipe 12 to purge it with the air so that exhaust gas does not flow into the gas collecting pipe 12, a washing solution is supplied so as not to be carried toward a flue, washing the gas collecting pipe top end to a spiral tube 16, and the sulfuric acid component in a sample line is washed away and put into a washing solution receiving tank 23. When the washing solution reaches a fixed quantity, it is sent to an analyzing sample receiving tank 26 to determine the sulfuric acid component in the analyzing sample solution by neutralization titration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention automatically and gas sampling method and apparatus for analyzing, SO ₃ concentration in the exhaust gas to SO ₃ concentration by continuously collecting sulfur trioxide (SO ₃₎ in the exhaust gas Analysis method and device.

[0002]

2. Description of the Related Art When a fuel such as heavy oil having a high sulfur content is burnt, sulfur dioxide (SO ₂ ) is generated in the exhaust gas, but a part of this SO ₂ is further oxidized in the combustion chamber or the high temperature heat transfer section. , Sulfur trioxide (SO ₃ ). Of these gases, the SO ₂ gas is in a gaseous state even when the gas temperature is lowered, so that the concentration can be easily measured.
B 7981) also specifies various automatic measurement methods, and continuous analysis is also possible.

On the other hand, SO ₃ becomes sulfuric acid gas in the temperature range of 200 to 250 ° C., and becomes SO ₂ mist when the temperature decreases and becomes lower than the acid dew point. For this reason, if the temperature of the sample gas decreases during the analysis of the SO ₃ gas concentration, or if there is a temperature part below the acid dew point in the sampling line between the gas sampling tube and the analyzer, the sulfuric acid gas will be converted into sulfuric acid in the sampling line. It becomes a mist and condenses and adheres to the line, giving a negative error in the concentration measurement.

Japanese Patent Laid-Open No. 54-143195 discloses, as a method for analyzing the concentration of SO ₃ in exhaust gas, a gas sampling pipe 2 heated to 200 to 300 ° C. in a flue 1 as shown in FIG. Spiral tube 3 attached to sample gas and then maintained at a temperature of 80 to 150 ° C below the acid dew point temperature
A method for sampling sulfuric acid in exhaust gas has been proposed in which gaseous sulfuric acid is converted into liquid sulfuric acid by condensing it by utilizing the inertial collision action in a spiral tube. It is also possible to determine the SO ₃ concentration by washing the sulfuric acid content collected by using this method with pure water passed through a sampling line, collecting an appropriate amount, and analyzing the sulfuric acid content by a neutralization titration method or the like. In this method, when the temperature of the sample gas to be sampled drops below the acid dew point temperature, SO ₃ gas condenses as sulfuric acid mist in the sampling line and adheres to the line, so measure the gas sampling pipe attached to the flue. Each time, the sulfuric acid content adhering to the inside of the sampling line had to be removed and washed, which was a drawback that continuous measurement was not possible. In particular, the equipment to be installed on site is large-scale and the sampling line is long, so it is very difficult to maintain the temperature inside the sampling line above the acid dew point, and it is difficult to completely wash out from the gas sampling pipe to the inside of the sampling line with the cleaning liquid. However, there was a drawback that an accurate analysis value could not be obtained.

[0005]

As described above, the state of SO ₃ gas in the exhaust gas changes depending on the temperature, and when it reaches a temperature below the acid dew point, it condenses into sulfuric acid mist and adheres to the sampling line. Therefore, an accurate analysis value cannot be obtained. The measurement using the apparatus as shown in FIG. 1 also causes the above-mentioned problems. Incidentally, after the SO ₃ in the exhaust gas in the flue 1 was collected by the conventional method of FIG. 1, the gas sampling pipe 2 was removed from the flue and washed, and as shown in FIG. By switching the three-way cock, the SO ₃ concentration in the exhaust gas when cleaning was performed without removing the gas sampling pipe was carried out by manual analysis as described in detail below. That is, the path from the gas sampling tube 2 to the spiral tube 3 in FIG.
Is removed from the flue 1 and washed with pure water, and the sulfuric acid content contained in a certain amount of the washing liquid is titrated with a sodium hydroxide (NaOH) solution by the neutralization titration method, and as shown in FIG. A three-way cock 4 is provided in the sampling line after the sampling tube 2, and the pure water in the cleaning liquid tank 5 is switched to the sampling line 6 and the spiral tube 3 by switching the three-way cock 4.
After washing through the column, the sulfuric acid content contained in a fixed amount of the washing solution was titrated with a NaOH solution by the neutralization titration method.

The results measured by both methods are shown in Table 1 below.

[0007]

[Table 1]

As can be seen in Table 1, compared to the SO ₃ amount measured by the device shown in FIG. 1, S measured by the device shown in FIG.
The amount of O ₃ was 13.9 ppm lower on average. In the apparatus shown in FIG. 2, when the gas sampling tube 2 was removed from the flue 1 and the tip of the gas sampling tube 2 was washed with pure water, almost the same measurement values as those obtained by the apparatus shown in FIG. 1 were obtained. It was This is because the temperature of the sampling line from the point where the gas sampling tube 2 heated by the heater 7 exits to the three-way cock 4 becomes below the acid dew point, and the sulfuric acid mist condenses in this part, which makes it impossible to completely clean it. is there.

The present invention improves upon the device shown in FIG.
SO in₃Quantitative analysis of concentration continuously and accurately
SO in exhaust gas for₃A gas sampling method and device;
SO ₃To provide a method and apparatus for analyzing concentration
Is.

[0010]

A method of collecting SO ₃ gas according to the present invention uses an exhaust gas containing SO ₃ gas in an amount of 200 to 300.
A certain amount of sample gas was sampled using a gas sampling tube heated to ℃, then passed through a spiral tube maintained at 80 to 150 ℃ below the acid dew point temperature, and the gas was generated by utilizing the inertial collision action in the spiral tube. In the method of collecting SO ₃ gas in the exhaust gas, in which gaseous sulfuric acid is converted into liquid sulfuric acid and after coagulation, the inside of the sampling pipe is washed with washing water and an appropriate amount is collected, air is added to the tip of the gas sampling pipe during washing. It is characterized in that the cleaning liquid is sent from the tip of the gas sampling pipe to the spiral pipe while being purged so as not to suck the exhaust gas and cleaning.

An apparatus for carrying out the above method is SO
_{In a} device for collecting SO ₃ gas in exhaust gas, which comprises a gas sampling pipe for sampling exhaust gas containing ₃ gases, a heating means for heating the gas sampling pipe, and a spiral pipe connected to the gas sampling pipe, A cleaning water supply port formed at the tip, an air outlet located closer to the tip of the pipe than the supply port, a device for supplying cleaning water to the supply port, and a device for supplying compressed air to the outlet. It is characterized by

The method of analyzing the SO ₃ concentration according to the present invention is such that a fixed amount of the wash water obtained by the above method is sampled, and then the neutralization titration method (coulometric titration method), the precipitation titration method, and the precipitation titration method specified in JIS K 0103 Nephelometry or JIS K 012
The SO ₃ concentration is analyzed by a sulfur oxide analysis method such as an ion chromatograph specified in 7.

An apparatus for carrying out the above method comprises a cleaning liquid receiving tank for receiving the cleaning liquid discharged from the spiral pipe,
A certain amount of cleaning liquid stored in the cleaning liquid receiving tank is transferred, and it comprises an analytical sample receiving tank in which a sulfur oxide analysis method such as neutralization titration method, precipitation titration method, turbidimetric method or ion chromatograph is carried out. .

[0014]

FIG. 3 shows an apparatus for collecting SO ₃ gas in exhaust gas and an apparatus for analyzing SO ₃ concentration.
In the gas sampling pipe 12 which is passed through the inside of the stack 1, the portion projecting into the chimney is heated by the heater 13 to 200 to 300 ° C., and the dust filter 14 is attached to the tip.
Is attached, and the rear end is connected to a spiral tube 16 immersed in a constant temperature bath 15. The spiral tube 16 has a chemically stable and electrically stable thermostatic bath 15 using silicone oil. 80 to 15 below acid dew point temperature
It is kept at 0 ° C.

The spiral pipe 16 is connected to branch pipes 17 and 18, and one of the branch pipes 17 measures an electromagnetic valve 19, a filter 20, a gas flow meter 21, a pump 22 and a flow rate of gas sucked by the pump 22. A dry gas meter 23 is sequentially installed, and the other branch pipe 18 has a cleaning liquid receiving tank 24, an analytical sample receiving tank 26 equipped with an analyzer, and solenoid valves 27 arranged before and after each receiving tank 24 and 26. The cleaning liquid receiving tank 24 further includes a liquid level gauge 30, a solenoid valve 31 for drain, and a pump 32 for sucking the cleaning liquid.

The cleaning liquid is supplied from the cleaning liquid tank 33 to the gas sampling pipe 12 by the tubing pump 34, and the compressed air for purging is supplied by the air pump 35 toward the tip side of the cleaning liquid. A solenoid valve 36 controls the supply or stop of air. Next, the collection of SO ₃ gas in the exhaust gas by this device will be described.

Stopping the tubing pump 34, the solenoid valve 2
7 and 36 are closed, the solenoid valve 19 is opened, and the pump 22 is driven to remove the exhaust gas in the flue 11 from the dust filter 14,
Gas sampling pipe 12, spiral pipe 16, filter 20,
The gas is passed through the gas flow meter 21 and the dry gas meter 23 and sucked. Then, when a certain amount is reached, the solenoid valve 19 is closed and the suction of the exhaust gas is stopped. Since the SO ₃ gas in the exhaust gas becomes liquid when the temperature becomes lower than the acid dew point temperature and exists as sulfuric acid mist in the gas, the exhaust gas passes through the spiral pipe 16 kept at a temperature lower than the acid dew point by the constant temperature bath 15 during suction. During this period, the SO ₃ gas in the exhaust gas is condensed due to the inertial collision in the spiral tube 16, and the sulfuric acid content is collected on the inner surface of the spiral tube.

Then, the collected sulfuric acid was washed out and SO ₃
The analysis of concentration will be described. The portion of the sampling line between the gas sampling pipe 12 and the spiral pipe 16 where the temperature drops below the acid dew point adheres to the sulfuric acid mist, which is condensed sulfuric acid. It is an important point to get the value.

Then, the electromagnetic valve 19 is closed to stop the suction of the exhaust gas, then the electromagnetic valves 28 and 31 are closed and the electromagnetic valves 27 and 36 are opened, and the air pump 35 is driven to supply compressed air to the gas sampling pipe 12. Is supplied, and compressed air is blown out from the tip of the gas sampling pipe 12. As a result, the inside of the pipe is purged to a positive pressure and purged, and the exhaust gas from the flue 11 is collected by the gas sampling pipe 12
So that it does not flow into. In this state, the tubing pump 34 is driven so that the cleaning liquid in the cleaning liquid tank 33 is supplied to the gas sampling pipe 1.
Supply to 2. And gas sampling tube 12 and spiral tube 1
6 is washed while driving the air pump 32 to suck it, the sulfuric acid content in the sampling line is washed away, and the washing liquid receiving tank 2
Send to 4. Since the outlet for compressed air in the gas sampling pipe 12 is located on the tip side of the supply port for the cleaning liquid, the cleaning liquid does not flow toward the flue 11 due to the air blown on the tip side of the gas sampling pipe 12 during cleaning. The whole amount will flow toward the spiral tube 16.

The washing is carried out until the washing liquid flowing into the washing liquid receiving tank 24 reaches a certain amount required for analysis, and when the liquid level reaches a certain level and the liquid level gauge 30 detects it, the air pump 32 is stopped, The electromagnetic valves 27, 29 and 36 are closed and the electromagnetic valves 28, 31 are opened to stop the flow of the cleaning liquid, and the cleaning liquid in the cleaning liquid receiving tank 24 is sent to the analytical sample receiving tank 26. The cleaning liquid in the cleaning liquid receiving tank is the analytical sample receiving tank 26.
After being sent to the inside, the sulfuric acid content in the analytical sample liquid in the receiving tank 26 is obtained by a neutralization titration method, a precipitation titration method, a turbidimetric method or a sulfur oxide analysis method such as an ion chromatograph in the analyzer 25. Then, the SO ₃ concentration in the constant amount of sucked exhaust gas is calculated.

After the analysis is completed, the electromagnetic pulp 29 is opened and the analytical sample liquid in the receiving tank 26 is discharged. After the completion of the analysis, it is desirable to wash the washing liquid receiving tank 24 and the analysis sample receiving tank 26 with the washing liquid to reduce the blank value.

[0022]

[Example] Using the apparatus shown in FIG. 3, the analysis of the SO ₃ concentration in the flue gas of a heavy oil-fired heating furnace was conducted as follows. That is, the gas sampling pipe 12 is heated to 25 by the heater 13.
At 0 ° C, the spiral tube 16 is placed in a constant temperature bath 15 for moisture and S.
The temperature is kept at 100 ° C. which is not affected by O ₂ , the solenoid valves 27 and 36 are closed, the solenoid valve 19 is opened, and the pump 22
Was driven to collect 20 L of exhaust gas in the flue 11 with the dry gas meter 23. After collection, sodium sulfate (Na ₂ S
The gas sampling tube 12 and the spiral tube 16 are washed with a cleaning solution of O ₄ ), and the sulfuric acid content in a fixed amount of the analytical sample solution collected in the analytical sample receiving tank 26 is sodium hydroxide (NaOH) solution by the neutralization titration method. Titrated with.

FIG. 4 shows an outline of the neutralization titration device. The pH electrode 41 and the constant current device 42 are provided in the analytical sample receiving tank 26 into which a fixed amount of cleaning liquid is fed from the cleaning liquid receiving tank 24.
An anode 43 and a cathode 44, which are connected to each other, are set, and the anode 43 has a liquid drop portion 45 that allows electricity to pass to the bottom but does not pass liquid.
The cleaning liquid in the cleaning liquid tank 47 is supplied to the bottom of the container by driving the tubing pump 48 and is discharged from the drain 49.

A constant direct current is passed from the constant current device 42 between the anode 43 and the cathode 44, and constant current electrolysis is performed with stirring by the stirrer 51 to analyze the sulfuric acid content in the analytical sample receiving tank 26. The pH point 41 is used to measure the neutralization point of the sample liquid, and the sulfuric acid content is obtained from the amount of electricity until the neutralization point is reached, and the amount of SO _{3 in} the exhaust gas is calculated.

In this example, the time required for measurement was about 4 minutes, and the measurement was performed at 10 minute intervals.

[0026]

[Comparative Example] Using the apparatus according to the conventional method of FIG. 1, the path from the gas sampling tube 2 to the spiral tube 3 is shortened as much as possible,
For each measurement, the gas sampling tube 2 was removed from the flue 1 and washed with pure water, and the sulfuric acid content contained in a fixed amount of the washing solution was titrated with a NaOH solution by the neutralization titration method. The measurement time by this manual analysis was about 5 minutes.

During the measurement in the above Examples and Comparative Examples, the heating furnace was operated by switching from high-sulfur heavy oil to low-sulfur heavy oil. The measurement results are shown in Table 2 below.

[0028]

[Table 2]

As can be seen from Table 2, the measured values obtained in the examples are 1.0 and those obtained by the manual analysis of the comparative example.
The agreement was very good with a difference within ppm. In the case of the embodiment, this means that the cleaning liquid receiving tank 2 starts from the tip of the gas sampling pipe 12.
This shows that the sampling lines up to 4 could be completely cleaned. In addition, the measurement time of the example is shorter than that of the comparative example, and since the gas sampling tube 12 does not have to be removed from the flue 11, the SO ₃ concentration can be continuously measured.

[0030]

The present invention is configured as described above and has the following effects. As described above, the method according to claim 1 and the device according to claim 2 pass the collected exhaust gas through the spiral tube kept at a temperature below the acid dew point, and utilize the inertial collision action in the spiral tube to extract the exhaust gas. In a method and apparatus for condensing SO ₃ gas in a liquid state, depositing it in a liquid state, and then washing it with a cleaning liquid to wash it out, while purging with the air sent to the tip of the gas sampling pipe, the cleaning liquid is spirally fed from the tip of the gas sampling pipe It is designed to be sent to a tube for cleaning, and the sulfuric acid mist adhering to the sampling line from the tip of the gas sampling tube to the spiral tube can be completely washed out without removing the gas sampling tube, and the analytical sample solution collected for a short time Can be obtained at

In the method according to claim 3 and the device according to claim 4, a certain amount of the analytical sample solution obtained by the above method and device is neutralized titration method, precipitation titration method, nephelometry or ion chromatography. Titration can be performed in a short time by a sulfur oxide analysis method such as fluff, and SO ₃ concentration can be continuously and automatically measured on site.

[Brief description of drawings]

FIG. 1 is a schematic view of a conventional SO ₃ gas sampling device in exhaust gas.

FIG. 2 is a schematic view of an SO ₃ gas sampling device equipped with a cleaning device.

FIG. 3 is a schematic view of an SO ₃ gas sampling device according to the present invention.

FIG. 4 is a schematic diagram of a neutralization titration device.

[Explanation of symbols]

1, 11 ・ ・ Flue 2, 12 ・ ・ Gas sampling pipe 3, 16 ・ ・ Spiral pipe 4 ・ ・ Three-way cock 5, 33,47 ・ ・ Cleaning liquid tank 13 ・ ・ Heater 14 ・ ・ Dust filter 15 ・ ・ Constant temperature tank 17, 18 ··· Branch pipe 19, 27, 28, 29, 31, 36 · · Solenoid valve 20 · · Filter 21 · · Gas flow meter 22 · · Pump 23 · · Dry gas meter 24 · · Cleaning liquid receiving tank 25 · · Analysis Equipment 26 ・ ・ Analytical sample receiving tank 30 ・ ・ Liquid level gauge 32, 35 ・ ・ Air pump 34,48 ・
・ Tuping pump 41 ・ ・ PH electrode 42 ・ ・ Constant current device 43 ・ ・ Cathode 44 ・ ・ Anode 45 ・ ・ Drying part 46 ・ ・ Cylinder vessel 51 ・ ・ Stirrer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Imamura 11-1 Showa-cho, Kure-shi, Hiroshima Inside the Kure Works, Nisshin Steel Co., Ltd. No.48 Labtech Co., Ltd. (72) Inventor Kei Yoshikawa No.48-15 Chuo, Itsukaichi Saiki-ku, Hiroshima City No.48 Labtech Co., Ltd.

Claims (4)

[Claims] 1. From the exhaust gas containing SO ₃ gas, 200 to ₃
A certain amount of sample gas was sampled using a gas sampling tube heated to 00 ° C, and then passed through a spiral tube maintained at 80 to 150 ° C below the acid dew point temperature to utilize the inertial collision action in the spiral tube. In the method of collecting SO ₃ gas in exhaust gas, in which the gaseous sulfuric acid is converted to liquid sulfuric acid and after coagulation, the inside of the sampling pipe is washed with washing water and an appropriate amount is collected. the feed, while purging so as not to suck the exhaust gas, sO ₃ gas sampling method characterized by the cleaning liquid for cleaning is sent to the spiral tube from the tip of the gas sampling tube. 2. SO in exhaust gas having a gas sampling pipe for sampling exhaust gas containing SO ₃ gas, heating means for heating the gas sampling pipe, and a spiral pipe connected to the gas sampling pipe.
_{3 In the} gas sampling device, a cleaning water supply port formed at the tip of the gas sampling pipe, an air outlet located closer to the tip of the pipe than the supply port, and a device for supplying cleaning water to the supply port, An SO ₃ gas sampling apparatus for carrying out the method according to claim 1, characterized in that the apparatus comprises a device for supplying compressed air to the air outlet. 3. A predetermined amount of the wash water obtained by the method according to claim 1, and then a neutralization titration method (coulometric titration method), a precipitation titration method, a turbidimetric method, or sulfur for ion chromatography. SO ₃ concentration analysis method, which comprises analyzing the SO ₃ concentration by oxidation analytical methods. 4. A cleaning liquid receiving tank for receiving the cleaning liquid discharged from the spiral tube, and a fixed amount of the cleaning liquid stored in the cleaning liquid receiving tank are transferred to a neutralization titration method, a precipitation titration method, a turbidimetric method or an ion chromatograph. An SO ₃ concentration analyzer for performing the method according to claim 3, comprising an analytical sample receiving tank in which the sulfur oxide analysis method is performed.