JPS634139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydrogen chloride measuring device that measures the concentration of hydrogen chloride in exhaust gas generated during the incineration of industrial waste.

In recent years, with the development of the chemical industry, the concentration of hydrogen chloride gas in the exhaust gas generated when industrial waste is incinerated has increased, and this trend is particularly noticeable with the increase in the amount of vinyl chloride used. From the viewpoint of material corrosion and air pollution, it is necessary to measure the concentration continuously over a long period of time. Conventionally, there are methods for measuring the concentration of hydrogen chloride in exhaust gas that utilize the fact that hydrogen chloride gas is highly soluble in water. In other words, exhaust gas is continuously brought into contact with an absorption liquid whose main component is water, hydrogen chloride gas in the exhaust gas is absorbed by the absorption liquid, and the concentration of chlorine ions produced in this absorption liquid is analyzed using a chlorine ion electrode. This method continuously measures the concentration of hydrogen chloride gas in exhaust gas. In this case, in order to reduce the juncture potential of the reference electrode used in combination with the chloride ion electrode and stabilize the electrode potential, a PH buffer reagent or a neutral salt, etc. is added to the absorption solution in advance. It is used after being slightly dissolved. However, when using an absorption liquid containing a PH buffer reagent, etc., it is necessary to use a large amount of such absorption liquid for a long period of time while completely preventing chlorine ion contamination and contamination due to the continuous operation of a device for measuring hydrogen chloride in exhaust gas. Since it is practically difficult to carry out continuous automatic operation for one to two weeks at most,
It has had problems such as requiring a great deal of effort to maintain and inspect it.

As a result of various studies to solve these problems, the present inventors measured hydrogen chloride in exhaust gas using ion-exchanged water in which no pH buffer reagent or neutral salts were dissolved as an absorption liquid. If there are large amounts of coexisting gases such as carbon dioxide, sulfur dioxide, and nitrogen oxides in the flue gas (for example, flue gas usually contains about 10% carbon dioxide, and sulfur dioxide and nitrogen oxides).
Contains about 10ppm. ) is absorbed and dissolved in the absorption liquid together with hydrogen chloride, and carbonate ions, sulfite ions,
Since various ions such as nitrite ions are generated, the conductivity is high, and the chloride ion electrode operates stably and accurately without using a PH buffer reagent, allowing for good detection of chloride ion concentration. The present invention was completed by learning that it is possible to deionize the absorption liquid after measurement, make it absorb exhaust gas again, and use it for circulation. An object of the present invention is to provide a device for measuring hydrogen chloride in exhaust gas that is capable of continuous automatic operation for a period of time.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the figure, reference numeral 1 denotes a chimney, into which a heating probe 2 is inserted to open one side wall of the chimney and take out the exhaust gas in the flue.
is connected to. Note that 5 and 6 are temperature controllers, respectively, and areas A and B are temperature controllers 5 to ensure that the flue gas inside the area from the heating probe 2 to the absorption tube 4 is cooled and does not drop below the dew point. ，
Heated at 6. Further, a thermometer 7 is inserted into the tube 3 at its distal end.

The absorption liquid outlet 4b of the absorption tube 4 is connected to a gas-liquid separator 9 via a reaction tube 8, and the lower end of this separator 9 is connected to a chlorine electrode 11 via a Teflon (registered trademark) coil 10. and the sample inlet 13a of the measuring device 13 in which the reference electrode 12 is disposed, and the absorption liquid separated from the gas by the separator 9 is introduced into the measuring device 13, and the chloride ion concentration therein is measured. be done. The measured value is electrically amp 1
4 and displayed on the recorder 15. Further, the sample outlet section 13b of the measuring device 13 is connected to an absorption liquid tank 19 via a drain pump 16, a liquid meter 17, and a valve 18. The drain pump 16 is provided to ensure that the flow rate of the absorption liquid flowing through the measurement cell 13 remains constant even if the flue pressure fluctuates.

The tank 19 is connected to a regenerator 20 filled with negative or both negative and positive ion exchange resin, and the absorption liquid sent from the tank 19 to the regenerator 20 is deionized and converted into ion exchange water (deionized water). ) is now available. The regenerator 20 is connected to the absorption liquid inlet portion 4c of the absorption pipe 4 via a trap 21, a three-way tank 22, and a liquid feed pump 23. Incidentally, a tap water inlet pipe 25 is connected to the tank 19 and has a valve 24 interposed therein for feeding tap water into the tank 19 if necessary.
6 is an equivalent liquid container connected to the three-way pot 20.

Further, the upper side of the gas-liquid separator 9 is connected to an electronic dehumidifier 27, and the gas component separated from the absorption liquid in the separator 9 flows into the dehumidifier 27 and is dried. The dried gas component then passes through a filter 28, a flow meter 29, a gas suction pump 30 whose discharge amount is constant, and is discharged from an exhaust port 31. In this case, the amount of exhaust gas suction is determined by the flowmeter 29.
The flow rate control circuit 32 and reversible electric motor 33 are operated by a signal from a flow rate detector (not shown) disposed in the flow rate control valve 34 to open and close the flow rate adjustment valve 34, thereby controlling the amount of atmospheric air sucked from the atmospheric air intake port 35 through the filter 36. It is automatically controlled by increasing and decreasing. Further, the water condensed in the electronic dehumidifier 27 is temporarily collected in the drain trap 37, and then the valve 39 and the pinch valve 4 are
0 opens and the liquid is discharged from the drain port 41. Note that this drain port 41 communicates with the absorption liquid tank 19 via a valve 42. Also, in the drawings,
A temperature controller 43 is installed in an area C surrounded by a dashed line, which includes the absorption tube 4, the reaction tube 8, the Teflon coil 10, the measurement cell 13, the trap 21, and the flowmeter 29, so as to be heated to a predetermined temperature. In the figure, thick lines indicate liquid flow paths, thin lines indicate gas flow paths, and dashed lines indicate electrical connections.

Next, to explain the case of measuring the hydrogen chloride concentration contained in the flue gas in the flue using the device for measuring the hydrogen chloride concentration in the flue configured as described above, first, the gas suction pump 30 is activated, and the hydrogen chloride concentration in the flue is of exhaust gas is introduced into the heating probe 2. Note that the amount of introduced exhaust gas (amount of suction) is automatically controlled as described above. The exhaust gas that has entered the heating probe 2 then passes through a heating sampling tube 3 and then into an absorption tube 4. During this time, the exhaust gas is kept at a high temperature, for example 120°C or higher, to prevent moisture from condensing.

On the other hand, the liquid sending pump 23 is activated to cause ion-exchanged water (deionized water) to flow from the absorption liquid tank 19 to the regenerator 20, where it is deionized, and then flows through the trap 21 and the three-way tank 22. The gas is introduced into the absorption tube 4 and mixed with the exhaust gas. The exhaust gas mixed with ion-exchanged water then passes through the reaction tube 8 and then flows into the gas-liquid separator 9, but when passing through the reaction tube 8 from the absorption tube 4, sufficient gas-liquid contact is made.
Hydrogen chloride, CO ₂ , SOx, NOx, etc. in the exhaust gas are absorbed by ion exchange water.

Next, the absorption liquid from which the gas has been separated by the gas-liquid separator 9 flows through the Teflon coil 10 into the measuring device 13, where Cl ^- ions are detected by the chlorine electrode 11, and this detected value is transferred to the amplifier 14. is amplified by
It is recorded on the recorder 15. Note that the device 13
The flow rate of the absorption liquid in the chamber is kept constant by the drain pump 16, ensuring the accuracy of the measured values. The absorption liquid is then pumped through the pump 16, liquid meter 17, and valve 18.
The absorbent liquid enters the absorption liquid tank 19 through the passageway and is stored therein.
Various ions (carbonic acid, sulfurous acid, nitrous acid, etc. and chlorine ions based on flue gas) are removed from the absorbent liquid in the tank 19 in the regenerator 20, and it becomes deionized water and enters the trap 21 to remove bubbles. Thereafter, the liquid is sent to the liquid feeding pump 23 via the three-way tank 22, flows into the absorption tube 4, and circulates through the above-mentioned route.

On the other hand, the gas separated by the gas-liquid separator 9 passes through an electronic dehumidifier 27, a filter 28, a flow meter 29, and a gas suction pump 30, and is discharged to the outside of the system from an exhaust port 31.

Therefore, in the above-described measurement of the hydrogen chloride gas concentration in the exhaust gas, the absorption liquid flowing inside the measuring device 13 brought the exhaust gas into contact with ion-exchanged water and absorbed hydrogen chloride and the coexisting CO ₂ , SOx, and NOx gases. The absorption liquid exhibits considerable electrical conductivity due to ions such as H ⁺ , CO ₃ ^2- , SO ₃ ^2- , NO ^- _2, etc., and since it is an aqueous solution in which each of these ions coexists,
When measuring the Cl ^- ion concentration using a combination of the chlorine ion electrode 11 and the comparison electrode 12, the electrode potential is stabilized and good due to the presence of each ion due to absorption of the coexisting gas and the resulting conductivity of the aqueous solution. to
Cl ^- ions can be detected. Therefore, there is no need to use an alkaline solution, a buffer solution, etc. as an absorption liquid, and the hydrogen chloride gas in the exhaust gas can be sufficiently collected by simply introducing ion-exchanged water (deionized water) as an absorption liquid into the absorption tube 4. , and the measurement of Cl ^- ions by the chlorine ion electrode 11 is also performed accurately because the electrode potential is stabilized. Furthermore, the absorption liquid whose Cl ^- ion concentration has been measured is deionized in the regenerator 20 and can be sent to the absorption tube 4 in an ion-free state and used for circulation, so the absorption liquid cannot be replenished or replaced. long-term continuous operation and continuous measurement. For example, in the case of a conventional device that uses a PH buffer reagent, neutral salt, etc. as an absorption liquid, the automatic continuous operation period is at most one to two weeks due to the absorption liquid stock. When measuring hydrogen chloride at a high concentration of about 200 to 300 ppm using 2 regenerators and 10 absorption liquid tanks, such a device can be automatically operated continuously for more than 5 months without maintenance of the absorption liquid. was possible. Further, according to the above-mentioned device, the regenerator 2
Since the lifespan of the ion exchange resin in 0 is displayed by a change in color, it is easy to know when it is time to replace it, and since the ion exchange resin can be recycled and reused, the cost of maintaining and managing the equipment is reduced.

As explained above, according to the present invention, even if hydrogen chloride gas is absorbed using deionized water in which PH buffer reagents, neutral salts, etc. are not dissolved as the absorption liquid, other coexisting gases are also absorbed at the same time. Since the conductivity of the liquid increases, it is possible to accurately measure the concentration of hydrogen chloride gas, and the absorption liquid can be used in circulation, allowing continuous automatic operation over a long period of time without maintenance of the absorption liquid, reducing industrial waste. It has the advantage of being able to continuously measure the concentration of hydrogen chloride gas in the exhaust gas generated when incinerating materials.

In addition, if the absorption liquid that has absorbed various coexisting gases in the exhaust gas contains substances that seriously degrade the ion exchange resin, tap water or the like can be supplied to the absorption liquid tank instead of circulating the absorption liquid. After being deionized through a regenerator, it is sent to the absorption tube as an absorption liquid, while the absorption liquid containing components that seriously degrade the ion exchange resin can also be discharged outside the system after measuring Cl ^- ions. However, measurements can be continued for a long period of time without maintenance of the absorption liquid.

[Brief explanation of the drawing]

The drawing is a flow sheet showing one embodiment of the present invention. 1... Chimney, 2... Heating probe, 4... Absorption tube, 13... Measuring device, 20... Regeneration device.

Claims (1)

[Claims] 1 Equipped with an absorption tube to which exhaust gas whose concentration of hydrogen chloride is to be measured and deionized water that absorbs hydrogen chloride and coexisting gases in this exhaust gas are supplied, a chlorine ion electrode and a comparison electrode, and a chlorine ion electrode and a comparison electrode. a measuring device that measures the hydrogen chloride concentration in deionized water that has absorbed the hydrogen chloride and coexisting gas with an electrode; a regenerator that deionizes and regenerates the deionized water in which the hydrogen chloride concentration has been measured using an ion exchange resin; An apparatus for measuring hydrogen chloride in exhaust gas, comprising means for supplying deionized water regenerated by the regenerator to the absorption tube.