JPS62186925A - Treatment of exhaust gas - Google Patents

Abstract

PURPOSE:To simultaneously remove Hg and acidic gas contained in an exhaust gas and also to easily remove these as the treated ashes by injecting both S or water insoluble S compd. and a neutralizing agent for acidic gas in a pow dery state into the exhaust gas. CONSTITUTION:Both S or water insoluble S compd. such as FeS, ZnS and a neutralizing agent for acidic gas such as slaked lime are injected in a powdery state of 10-300 mesh in a dust 2 through the nozzles 6, 6' for feeding powder into combustion exhaust gas generated in a generating source 1 of combustion exhaust gas and allowed to react with Hg to form HgS, and acidic gas is neutralized and fixed to the powder side. Thereafter Hg reactant and the neutralizing agent are collected together with soot and dust in an electrostatic precipitator 3 and discharged as the collected ashes to the outside of the system. The clarified gas is discharged through a stack 5 via an exhaust fan 4.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a dry exhaust gas treatment method that can be applied to exhaust gas treatment equipment such as municipal waste incinerators, industrial waste incinerators, human waste/sewage sludge incinerators, etc. , relates to a waste treatment method for removing mercury components and acid gas components from exhaust gas.

[Conventional technology]

Conventionally, only a wet removal method has been known as a method for simultaneously removing mercury, mercury compounds, and acid gas from combustion exhaust gas, and there has been no dry method as in the present invention. The wet removal method uses a caustic soda aqueous solution, carbonic acid or slaked lime slurry solution, and transfers mercury and acid gas in the gas to the liquid side through gas-liquid contact.

The conventional wet removal method has the disadvantage that it requires complicated equipment to treat wastewater containing mercury. Therefore,
If mercury could be removed using a dry method, and acid gases could be removed at the same time, it was expected that the problems of wastewater treatment would be resolved, and that mercury and acid gases could be treated in the same system, which would be highly effective.

[Problem that the invention seeks to solve]

The present invention eliminates the drawbacks of conventional exhaust gas treatment methods containing mercury and acidic gases, makes it possible to simultaneously treat mercury and acidic gases by a dry method, and uses the treated powder in an electrostatic precipitator or the like. The purpose is to provide a method for treating exhaust gas that can be easily removed.

[Means for solving problems]

The present invention injects sulfur or a water-insoluble sulfur compound and an acid gas neutralizer in powder form into exhaust gas, converts the mercury component in the exhaust gas into chemically stable mercury sulfide powder, and This is an exhaust gas treatment method characterized by neutralizing and removing gas with an acidic gas neutralizer.

Note that the water-insoluble sulfur compound is FeS.

Powder of ZnS, Cab, Cue, etc. can be used. Since the reaction between these mercury reactants made of sulfur or water-insoluble sulfur compounds and mercury and mercury compounds in exhaust gas is a solid-gas phase reaction, in order to accelerate the reaction, the surface area of the reactant particles must be increased, i.e. , it is necessary to make the particles as small as possible.

However, the particle size of the reactant is 10 to 300 mesh, preferably 200 to 300 mesh, because the reactant needs to be sprayed into the flue and carried by the airflow, and it needs to be collected by an electrostatic precipitator or the like. This is the range of Metsuyu.

Further, as the acidic gas neutralizing agent, hydroxide, carbonate, oxide, etc. of μsium or magnesium can be used.

The injection amount of powder is 0.1 per exhaust gas amount for mercury reactant.
~10 jj/Nm", 1 to 10 for neutralizing agent
g/N@3 is preferred.

The mercury reactant and the neutralizer can be injected into the flue individually, or the two types of powder can be mixed in advance and injected from the same nozzle.

Regarding the reaction temperature, the dew point of normal combustion exhaust gas is 100
It is necessary to operate at 120℃ or higher, as if the temperature is lower than that, dew condensation will occur and the reactant will become wet, causing problems such as the reactant sticking or sticking and clogging the nozzle. . In addition, thermal decomposition occurs at high temperatures, so 12
It is preferable to carry out the reaction at a temperature in the range of 0 to 400°C.

[Effect]

FIG. 1 is a block diagram of an apparatus for carrying out the present invention.

In the combustion exhaust gas containing mercury and mercury compounds and acid gases (e.g. hydrogen chloride, sulfur oxides, etc.) generated at the combustion exhaust gas source 1, 1! A mercury reactant and an acidic gas neutralizer are injected into the exhaust gas duct 2 in front of the gas flow of the L-air dust collector 3 by a powder supply nozzle/L'6.6'. The mercury reactant and the neutralizing agent are stored in a powder silo 7, 7', and the supply amount is adjusted by powder metering feeders 8, 8' and sent to the powder supply nozzle p. . Moreover, the position of this nozzle may be either the front or the rear. Among the powders injected into the exhaust gas, the mercury reactant quickly reacts with mercury and mercury compounds in the exhaust gas, fixing mercury from the gas side to the powder side, while the acid gas neutralizer reacts with the mercury and mercury compounds in the exhaust gas, while the acid gas neutralizer reacts with acidic gas (e.g., hydrogen chloride, sulfur oxide) to fix the acidic gas from the gas side to the powder side.

The mercury reactant that fixed mercury and the neutralizing agent that neutralized and fixed acidic gas are placed in the electrostatic precipitator 3 at the rear of the exhaust gas flow.
Collected together with soot and dust in combustion exhaust gas, collected ash10
is discharged from the system as The exhaust gas from which mercury and acid gas have been removed becomes clean gas and is discharged from the chimney 5 via the exhaust fan 4.

〔Example〕

The following experiment was conducted using the apparatus shown in FIG.

Hydrogen chloride 700ppm, sulfur oxide 50ppm.

200 containing mercury and mercury compounds
32 as a Nero agent in acid gas in exhaust gas at ~250℃
5 mesh bath 96% slaked lime t-5g/N 7FL
8. 200-500 mesh pass 95 as mercury reactant
% ZnS was injected at 19/N1rL4.

As a result, hydrogen chloride, sulfur oxides and mercury a in exhaust gas
m is 140ppm, 35ppm, Q, 121 respectively
By reducing M to 1197NrIL, we were able to remove 80.30% and 60% of the initial concentration, respectively.

〔Effect of the invention〕

The present invention eliminates acid gases such as hydrogen chloride and sulfur oxides and mercury in the flue gas by injecting sulfur or sulfur compounds and slaked lime or similar acid gas neutralizer in powder form into the flue in the flue gas. and mercury compounds can be easily removed as collected ash using an electrostatic precipitator, and combustion exhaust gas can be effectively purified.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus for carrying out the present invention. Sub-Agents 1) Meifuku Agent Ryo Hagiwara − Sub-Agent Atsuo Anzai

Claims (1)

[Claims] Sulfur or a water-insoluble sulfur compound and an acidic gas neutralizer are injected into the exhaust gas in powder form to convert the mercury component in the exhaust gas into chemically stable mercury sulfide powder, and to make the acidic gas in the exhaust gas acidic. A method for treating exhaust gas, characterized by neutralizing and removing it with a gas neutralizer.