JPS6038024A - Removal of hydrogen chloride in exhaust gas - Google Patents

Abstract

PURPOSE:To enhance the removal efficiency of HCl, by blowing a powdery alkali agent into a reaction chamber after grinding the same into a fine powder with a specific particle size or less. CONSTITUTION:Exhaust gas generated in a garbage incinerator 1 is introduced into a reaction chamber 3 through waste heat utilizing machinery 2 and a powdery alkali agent S such as slaked lime supplied from a silo 1 is blown into the reaction chamber 3 while ground into a fine powder with a particle size of 10mum or less by a finely grinding machine 10. HCl in the exhaust gas is removed through the reaction with the fine powder and the purified gas is exhausted through a dust collector 4. The chemical agent S' in the collected ash collected by the dust collector 4 is recovered in a hopper 11 and the reaction product on the surface of each particle is released by a finely grinding machine 10' and the regenerated chemical agent is blown into the reaction chamber 3 along with the powdery chemical agent S supplied from the side of the silo 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing hydrogen chloride from exhaust gas generated from a garbage incinerator or the like.

There are three methods for removing hydrogen chloride from exhaust gas generated from garbage incinerators: dry, semi-dry, and wet. The dry method is preferred due to its low equipment costs and ease of operation and maintenance. Although this is a good method, it has the disadvantage that its hydrogen chloride removal performance is poorer than semi-dry or wet methods.

The dry method was developed in 1972, when legal regulations were imposed on hydrogen chloride in waste gas from waste incinerators, in an attempt to meet the legal regulations using a simple device, primarily as a countermeasure for existing incinerators.

This method is carried out in an exhaust gas containing hydrogen chloride, in which gaseous molecules of basic hydrogen chloride and solid particles of alkaline agent powder encounter each other in the exhaust gas.

By the way, hydrogen chloride 14' (jp
, f-J, they are evenly scattered as gas molecules, and the diameter is approximately 3X (3X10 μ), and their number is large (on the order of 1021 pieces/m3). On the other hand, alkaline agent powder, such as commonly commercially available slaked lime powder, exists as solid particles (average particle size 20 to 50μ),
The number of these molecules is about 108 AJ at a normal injection amount, which is extremely small compared to the number of hydrogen chloride molecules. For this reason, the probability that solid particles of slaked lime powder and gaseous molecules of hydrogen chloride will encounter each other in the reaction chamber is low, making it impossible to increase the hydrogen chloride removal rate from exhaust gas. In addition, in order to increase the probability of encountering ′ in the reaction chamber, methods of increasing the residence time in the reaction chamber and increasing the momentum are known.
The former method has economical problems such as increasing the size of the reaction chamber, and the latter method also has its own limitations in terms of removal rate.

As a result of various studies based on the above background, the present inventor found that the probability that hydrogen chloride molecules in the exhaust gas and solid particles of alkaline agent powder encounter each other in the reaction chamber is proportional to the total surface area of the three. If the total surface area of the alkaline agent powder blown into the reaction chamber is increased, the above-mentioned probability, that is, the hydrogen chloride removal rate can be improved. If the hydrogen chloride removal rate was 75Ls or less,
We have discovered that we can improve this even further.

This invention was made based on the above-mentioned research, and the first invention was based on alkali powders commonly used in the past, mainly slaked lime powder (average particle size 20-50μ).
The second invention is characterized in that the alkali agent powder, mainly slaked lime powder, is pulverized into a fine powder of 0μ or less and blown into the reaction chamber (the amount of blown in this case is the same as the conventional one). The powder is classified, and powders larger than 10μ are finely ground to smaller than 10μ.

This method is characterized in that the classified fine powder of μ or less is directly blown into the reaction chamber.

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows equipment for removing chlorinated water and elemental elements from exhaust gas containing hydrogen chloride generated from a garbage incinerator. Room 3
→Through the dust collector 4, the chimney 671 is activated by the induced transport R machine 5.
) P1 The reaction chamber 3 contains alkaline agent powder S which is a chemical for removing hydrogen chloride in the silo 7.
(slaked lime powder in the embodiment) is blown in by the operation of the blower 8.

Accordingly, in this invention, finely pulverized -1,1A1o is incorporated into the pipe 9 for blowing the alkali powder S into the reaction chamber 3, and the alkali powder S (average particle diameter 2
0 to 50μ of slaked lime powder) to 10μ in the pulverizer lO.
It is characterized by pulverizing it into the following fine powder and blowing it into the reaction chamber 3. In this case, the blowing chamber is carried out in the same way as before, and for example, the molar ratio is slaked lime powder/hydrogen chloride = 3. . In order to reduce the consumption of the alkaline agent powder S, the agent S' (slaked lime particles whose surface is coated with a reaction product) in the dust collected by the dust collector 4 is placed in the hopper 11. This is collected and re-pulverized or ground by a pulverizer or crusher 10' to peel off the reaction products on the particle surface and generate a new reaction surface, and this regenerated agent is supplied from the silo 7 side. It is also possible to adopt a method in which the chemical powder (alkaline powder) is blown into the reaction chamber 3 together with the chemical powder (alkaline powder) S. In FIG. 1, reference numeral 12 indicates a blower for blowing the regenerating agent into the reaction chamber 3, and 13 indicates the blowing conduit.

FIG. 2 shows a hydrogen chloride removal method according to another embodiment (second invention) of the present invention, in which alkaline agent powder S (slaked lime powder with an average particle size of 20 to 50 μm, 10μ The following fine powders (containing 20~3o
Divided into fine powders with a diameter of less than μ, powders with a diameter of more than 10μ are divided into branch pipes 9.
The powder is sent from a to the pulverizer 1o and pulverized into a fine powder of 10 μm or less, and the classified fine powder of 10 μm or less is directly blown into the reaction chamber 3 through a branch pipe 9b. FIG. 3 is an explanatory diagram showing in a graph the relationship between the powder particle size of slaked lime blown into the reaction chamber 3 and the hydrogen chloride removal rate in the exhaust gas,
The molar ratio (ratio of slaked lime powder and hydrogen chloride) = 3, and the hydrogen chloride concentration in reaction chamber 3 = 600 ppm (12% 0
2 conversion value) is shown.

As is clear from this figure, when conventional slaked lime powder (average particle size 20-50μ) is directly blown into the reaction chamber at a hemolar ratio of 3, a hydrogen chloride removal rate of less than 75 cm can be obtained. On the other hand, when slaked lime powder is crushed into a fine powder of 10μ or less and blown into the reaction chamber 3 at a molar ratio of 3 (by the method of the present invention), the hydrogen chloride removal rate is 80% or more (the particle size is In the case of 5 μ, a high removal rate of 90 μ) was able to be obtained.

Since the method for removing hydrogen chloride from exhaust gas according to the present invention is as explained above, the hydrogen chloride removal efficiency can be improved by a simple method of pulverizing the alkaline agent powder into a fine powder of 10μ or less and blowing it into the reaction chamber. can be improved.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing two examples of hydrogen chloride removal equipment implementing the method of this invention, and Figure 3 is a graph showing the relationship between slaked lime powder blown into the reaction chamber and the hydrogen chloride removal rate. It is an explanatory diagram of the effect according to the experimental results shown in FIG. L... Garbage incinerator, 3... Reaction chamber, 4... Dust collector, 5... Induced blower, 6... Chimney, 7... Silo, S... Alkali agent powder, 8... ...Blower, 9...
Blowing line with alkaline agent powder, 9a r 91)・
... Branch pipe line, 10... Fine grinder, 14... Classifier.

Claims (2)

[Claims] (1) In a hydrogen chloride removal method using a dry method in which hydrogen chloride in exhaust gas is removed by blowing an alkaline agent powder such as slaked lime into a reaction chamber into which exhaust gas is introduced, the alkali agent powder is A method for removing hydrogen chloride from exhaust gas, characterized by pulverizing it into the following fine particles and blowing them into a reaction chamber. (2) In a hydrogen chloride removal method using a dry method, in which hydrogen chloride in exhaust gas is removed by blowing an alkaline agent powder such as slaked lime into a reaction chamber into which exhaust gas is introduced, the alkaline agent powder is classified. Powder with a particle size of 10μ or more is crushed into a fine powder of 10μ or less, and the powder with a particle size of 10μ or more is