JPH0738853Y2 - Reduction device for mercury compounds - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention measures the atomic mercury after reducing mercury compounds contained in the flue gas of a refuse incineration facility to atomic mercury with a reducing liquid. The present invention relates to a mercury compound reduction device that is introduced into a vessel.

[Conventional technology]

When garbage is incinerated in an incineration facility, the exhaust gas may contain mercury, which has recently been taken up as a pollution problem. Since mercury present in soot and smoke contains various mercury compounds in addition to the atomic state, first, the exhaust gas is thermally decomposed, and then the reducing liquid and the exhaust gas are brought into contact with each other to be reduced and vaporized. After all the mercury compounds are atomized, the exhaust gas containing vaporized mercury and the reducing solution are separated (gas-liquid separation) to measure the concentration of mercury. As a method for reducing such a mercury compound, conventionally, there are a circulation method in which a reducing solution is circulated and used many times, and a disposable method in which the reducing solution is discarded.

FIG. 2 shows an outline of a conventional circulation type reduction apparatus.

In FIG. 2, an extraction pipe 21 for extracting the exhaust gas G as a sample is inserted into the flue 20. Exhaust gas G
In addition to atomic mercury, a mercury compound is contained therein.
A heating conduit for heating the exhaust gas G is provided downstream of the extraction pipe 21.
22 communicates with each other, which prevents moisture from being condensed and does not interfere with the measurement. A gas-liquid contact flow path 23 communicates with the downstream of the heating conduit 22.

At the upstream end 23a of the gas-liquid contact flow path 23, the reducing liquid tank 10
A supply flow path 24 for supplying the reducing liquid 11 therein to the upstream end 23a.
Are in communication. In the gas-liquid contact flow path 23, the reducing liquid 11 for reducing the mercury compound and the exhaust gas G flow while making contact with each other to reduce the mercury compound and reduce most of the mercury into atoms. , Most of it vaporizes.

A gas-liquid separator for separating the reducing liquid 11 and the exhaust gas G containing the reduced gaseous mercury is provided downstream of the gas-liquid contact flow path 23.
25 are connected. The exhaust gas G containing gaseous mercury separated by the gas-liquid separator 25 passes through the gas flow path 27 and is subjected to a predetermined treatment, and then the mercury concentration is automatically measured by a measuring device (not shown). To be measured. On the other hand, the reducing liquid 11 separated by the gas-liquid separator 25 passes through the return flow path 26 and is returned to the reducing liquid tank.
Returned to 10, used many times.

[Problems to be solved by the device]

However, in the above circulation type reduction method, some mercury compounds that could not be reduced and atomic mercury dissolved in the reducing liquid 11 circulate together with the reducing liquid 11. for that reason,
Since the concentration of mercury in the reducing liquid 11 gradually increases, the flue 20
Concentration of mercury in the exhaust gas G extracted from the gas flow path
The ratio with the concentration of mercury in the exhaust gas G introduced into the measuring instrument from 27 is not constant. As a result, the so-called blank test value becomes high, and the reliability of the measured mercury concentration value decreases.

Further, the reducing liquid 11 makes gas-liquid contact with the exhaust gas G in the gas-liquid contact flow path 23 to absorb oxygen in the exhaust gas G, and also reacts with atmospheric oxygen in the reducing liquid tank 10. Therefore, not only the reducing ability of the reducing liquid 11 is deteriorated, but also an insoluble oxide is generated in the reducing liquid 11 to clog the narrow supply passage 24 and the like. Unable to do long-term unattended operation of some automatic measurements.

Due to such a problem, the circulation type reduction apparatus is still in the stage of the experimental machine, and conventionally, the disposable type which does not circulate the reducing liquid has been adopted.

This disposable system has a large reducing solution tank that stores a large amount of reducing solution and an effluent recovery tank that collects the used reducing solution (gas liquid contact), and the reducing solution is collected once a week. The reducing liquid is supplied to the tank and the drainage is collected from the drainage recovery tank. Although this method has a high reliability of the measured value of the mercury concentration, it requires a large reducing liquid tank and a waste liquid recovery tank, and therefore the apparatus becomes large and the installation place is limited. Moreover, since the reducing solution is manually supplied to the reducing solution tank, long-term unattended operation of automatic measurement cannot be performed.

It is an object of the present invention to improve the reliability of measured values of mercury concentration and enable long-term unmanned operation in a mercury compound reducing apparatus in which a reducing liquid is circulated.

[Means for Solving the Problems]

In order to achieve the above object, the present invention relates to a mercury compound reducing apparatus in which a reducing solution is circulated. First, in a reducing solution tank, the reducing solution is blocked from the outside air to prevent the reducing solution from oxidizing. Means are provided. An oxygen removing unit filled with an oxygen adsorbent that adsorbs oxygen in the reducing liquid is provided in the return flow path for returning the reducing liquid to the reducing liquid tank. The return passage or the supply passage is provided with a mercury removing section filled with a mercury adsorbent that adsorbs mercury in the reducing liquid.

[Action]

According to this invention, oxygen is dissolved in the reducing solution by gas-liquid contact, but oxygen is adsorbed by the oxygen adsorbent in the oxygen removing section, and in the reducing solution tank, the reducing solution is shielded from the outside air by the oxidation preventing means. Therefore, the reducing ability is not deteriorated and insoluble oxide is not generated.

On the other hand, since the mercury in the reducing solution is adsorbed by the mercury adsorbent in the mercury removing section, there is no possibility that the reducing solution supplied to the gas-liquid contact channel contains mercury.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a mercury-oxygen removing section 30 in which a mercury removing section and an oxygen removing section are integrated is provided in the return flow path 26 for returning the reducing solution 11 to the reducing solution tank 10. The mercury oxygen removal unit 30 has both functions of a mercury adsorbent that adsorbs mercury in the reducing liquid 11 and an oxygen adsorbent that adsorbs oxygen. For example, a mercury oxygen adsorbent such as porous activated carbon. It is filled with the agent 31.

The reducing solution tank 10 is filled with a reducing solution 11 which easily reacts with oxygen, such as sulfuric acid acid stannous chloride.
The reducing liquid tank 10 is made of a material having no air permeability, such as glass.

The reducing liquid 11 contains an oxygen adsorbent 12 such as porous activated carbon. The surface of this reducing liquid 11 is
A protective fluid 13 that has a specific gravity smaller than that of the reducing liquid 11 and spreads like a liquid film on the surface of the reducing liquid 11 to shut off outside air.
Is covered by. As the protective fluid 13, a fluid that does not pass air is used, and for example, liquid paraffin is used.

In the upper part of the reducing liquid tank 10, the insertion holes 15 into which the tubes 14 and 16 that configure the supply flow path 24 or the return flow path 26 are inserted.
Is provided. The tips 17 of the tubes 14 and 16 face the reducing solution. In addition, in the upper part of the reducing liquid tank 10,
An inlet (not shown) for pouring the reducing liquid 11 into the reducing liquid tank 10 is provided.

At the upstream part of the gas flow path 27 led out from the gas-liquid separator 25,
A distilled water supply passage 42 that joins the distilled water 41 from the distilled water tank 40 to the gas passage 27 is joined. The exhaust gas G comes into gas-liquid contact with the distilled water 41 in the gas washing section 27a of the gas flow path 27, and is bubbled in the air washing bottle 43 to be washed. The washed exhaust gas G is introduced into the dehumidifying bottle 44 through the subsequent gas passage 28 to be dehumidified, and is supplied as a measurement gas from the measurement gas passage 29 to a measuring device (not shown). A drainage channel 45 is in contact with the air washing bottle 43 and the dehumidification bottle 44, and the distilled water 41
Can be collected in the distilled water tank 40.

The drainage channels 45, 45 can be switched by a three-way valve. Also,
A pump P is provided in each of the supply passage 24, the return passage 26, the distilled water supply passage 42, and the drainage passage 45.

Other configurations are similar to those of the conventional example of FIG. 2, and the same portions or corresponding portions are denoted by the same reference numerals and detailed description thereof will be omitted.

In the above configuration, the exhaust gas G comes into gas-liquid contact with the reducing liquid 11 in the gas-liquid contact flow path 23, and the mercury compound in the exhaust gas G is reduced to atomic mercury, while the reducing liquid 11 contains oxygen and oxygen. Mercury melts in. However, the dissolved oxygen and mercury are absorbed by the mercury-oxygen adsorbent 31 in the mercury-oxygen removing section 30 provided in the return flow path 26.
Adsorbed by. Therefore, the reducing ability of the reducing liquid 11 is not deteriorated, and the gas-liquid contact flow passage from the supply flow passage 24
Since the reducing liquid 11 supplied to 23 does not contain mercury, the ratio between the concentration of mercury in the flue 20 and the concentration of mercury introduced into the measuring device becomes constant. As a result, the reliability of the measured mercury concentration is improved.

Further, the reducing liquid 11 which has recovered its reducing ability is protected from contact with the outside air by the protective fluid 13 in the reducing liquid tank 10, and therefore, there is no risk of oxidation. Therefore, the reducing ability is not deteriorated, and insoluble oxide is not generated, so that the supply passage 24 is not clogged. Therefore, long-term unmanned operation becomes possible.

By the way, in the above-described embodiment, the mercury-oxygen removing section 30 filled with the mercury-oxygen adsorbent 31 such as activated carbon that serves as both the mercury-adsorbent and the oxygen-adsorbent is provided. The mercury removing unit filled with the adsorbent and the oxygen removing unit filled with the oxygen adsorbent that adsorbs oxygen may be separately provided. In this case, the oxygen removing unit needs to be provided in the return flow passage 26, but the mercury removing unit may be provided in at least one of the return flow passage 26 and the supply flow passage 24. In addition,
The mercury adsorbent includes, for example, ALM-25 (manufactured by Nippon Soda Co., Ltd.), while the oxygen adsorbent includes, for example, molecular sieves (manufactured by Gascro Industrial Co., Ltd.).

Further, in the above embodiment, the protective fluid 13 is used as the oxygen prevention means.
Was provided in the reducing liquid tank 10, but the oxidation prevention means is not limited to this embodiment. As another oxidation preventing means, for example, a protective film made of a Teflon-based thin film having acid resistance and alkali resistance is used to close the opening of the reducing solution tank whose upper part is opened and to cover the surface of the reducing solution with this protective film. It may be cut off from the outside air (Practical application Hei 2-69726
No. (Actual Kaihei No. 4-30039)).

Further, the gas-liquid separator 25 may be separated by a membrane separation method using a porous tube in addition to the separation tube method shown in this figure. In this case, the mixture of the exhaust gas G and the reducing liquid 11 is caused to flow in the tube of the porous tube, and the exhaust gas G is guided to the outside in the radial direction of the porous tube to be separated. According to the membrane separation method, since the crystal particles of the reducing agent can be removed from the porous tube, the air washing section 27a and the air washing bottle 43 are unnecessary.

[Effect of device]

As described above, according to the present invention, it is possible to remove the mercury and oxygen dissolved in the reducing solution by gas-liquid contact, and prevent the reducing solution from oxidizing in the reducing solution tank. The reliability of the measured mercury concentration is improved, and long-term unmanned operation is possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a mercury compound reducing apparatus showing an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing a conventional example. 10 ... reducing liquid tank, 11 ... reducing liquid, 13 ... oxidation preventing means (protective fluid), 23 ... gas-liquid contact flow path, 23a ... upstream end, 24 ... supply flow path, 25 ... gas Liquid separator, 26 ... Return channel, 27 ... Gas channel, 30 ... Mercury oxygen removal section, 31 ... Mercury oxygen adsorbent, G ... Exhaust gas.

Claims (1)

[Scope of utility model registration request] 1. A gas-liquid contact channel for reducing a mercury compound by flowing an exhaust gas containing a compound of mercury and a reducing solution for reducing the mercury compound in contact with each other, and an upstream end of the gas-liquid contact channel. A supply flow path for supplying the reducing liquid in the reducing liquid tank,
A gas-liquid separator which is connected to the downstream end of the gas-liquid contact flow path and separates the reducing liquid and the exhaust gas containing reduced gaseous mercury, and the exhaust gas containing gaseous mercury from the gas-liquid separator In a reducing device of a mercury compound, which comprises a gas flow path for guiding the measuring liquid to a measuring instrument, and a return flow path for returning the reducing liquid from the gas-liquid separator to the reducing liquid tank. The reducing solution tank is provided with an oxidation preventing means for preventing the reducing solution from oxidizing by shutting off from the outside air, and an oxygen removing section filled with an oxygen adsorbent for adsorbing oxygen in the reducing solution is provided in the return flow path. A mercury compound reducing apparatus, characterized in that a mercury removing section filled with a mercury adsorbent for adsorbing mercury in the reducing liquid is provided in at least one of the return flow path and the supply flow path.