JPH0779943B2 - Exhaust gas treatment equipment for municipal waste incinerators - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention particularly relates to municipal waste capable of simultaneously treating harmful substances such as soot, chlorine, fluorine, nitrogen oxides, sulfur oxides, dioxins and heavy metals discharged from the exhaust gas of an urban refuse incinerator. The present invention relates to an exhaust gas treatment device for an incinerator.

[0002]

2. Description of the Related Art Exhaust gas emitted from an incinerator for municipal solid wastes contains, as shown in Table 1 below, soot, hydrogen chloride (HCl), nitrogen oxides (NOx) and sulfur oxides (SOx). Since it contains chemical substances such as dioxin, and solid or gaseous harmful substances such as heavy metals, it is extremely important to remove these harmful substances from the exhaust gas in order to preserve the surrounding environment and the global environment.

[0003]

[Table 1]

Conventionally, the above-mentioned measures for removing harmful substances include unit operations such as dust collection for removing soot and dust, denitration for removing NOx, desulfurization for removing SOx, desalting for removing hydrogen chloride, for example, in series. It is performed by a method of treating exhaust gas stepwise and individually for harmful substances using connected exhaust gas treatment equipment.

[0005]

However, the above-mentioned exhaust gas treatment equipment for treating harmful substances individually and stepwise has a drawback that the equipment cost is too high because it requires a large installation space.

Further, in the above-mentioned conventional treatment equipment, since it is not technically possible to remove dioxin and heavy metals, new equipment must be added in order to remove them, therefore There is also a problem that a larger installation space is required.

The present invention has been made to solve the above-mentioned conventional problems. Soot, hydrogen chloride, NOx, SOx
It is an object of the present invention to provide an exhaust gas treatment device for an urban refuse incinerator, which can remove harmful substances such as dioxin, heavy metals and the like by substantially simultaneous treatment, and therefore can reduce the equipment space.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to an exhaust gas treatment apparatus for an urban refuse incinerator that removes harmful substances from the exhaust gas of an urban refuse incinerator, and an electric dust collector for removing soot and dust from the exhaust gas and an exhaust gas A means for injecting and mixing ammonia, an exhaust gas after soot removal is passed together with ammonia, and adsorbing and removing harmful substances in the exhaust gas, an adsorption tower filled with activated carbon, and an activated carbon in the adsorption tower, A means for moving the exhaust gas in a direction substantially orthogonal to the passing direction and cutting out the adsorption tower, and a desorption tower for regenerating the cut out activated carbon,
And means for returning the regenerated activated carbon to said adsorption tower, before
The adsorption tower is divided into a plurality of filling chambers along the passage direction of the exhaust gas, these filling chambers are filled with activated carbon having a large particle size in order from the one closer to the inlet of the exhaust gas, and
The activated carbon of each filling chamber is moved in the passing direction in a direction substantially perpendicular to the exhaust gas, and hand stage cut into each filling outdoor, after playing cut activated carbon in the desorption column, means for classifying the grain each diameter When, by means of returning the classified activated carbon in the respective filling chambers in accordance with the particle size is in the installed configuration, it is obtained by solving the previous SL problems.

[0009]

[0010]

In general, city gas contains a large amount of soot and dust, but in the present invention, the exhaust gas is first treated by the electric dust collector. As a result, most of the soot is removed at this stage.

Then, the exhaust gas containing the soot dust and other harmful substances that cannot be completely removed is passed through the adsorption tower together with ammonia. When the exhaust gas passes through the adsorption tower, the hydrogen chloride contained in the exhaust gas is passed. (HC1), hydrogen fluoride (H
F) and sulfur dioxide (SO2) react with the mixed ammonia, respectively, as shown in the following formulas (1) to (3), so that these harmful substances are easily adsorbed on the activated carbon as their reaction products. Can be removed. In the formula (A), "adsorption" is represented.

(1) HCl + NH3 → NH4 Cl (A) (2) HF + NH3 → NH4 F (A) (3) SO2 + 1 / 2O2 + NH3 + H2 O → NH4 (H) SO4 (A) SO2 + 1 / 2O2 + H2 O → H2 SO4 (A)

The NOx contained in the exhaust gas can be reliably removed because the activated carbon serves as a catalyst and can be reduced to harmless nitrogen by ammonia as shown in the following equations (4) and (5).

(4) NO + NH3 + 1 / 4O2 → N2 + 3 / 2H2O (5) NO2 + 4 / 3NH3 → 7 / 6N2 + 2H2O

Further, dioxins and heavy metals contained in the exhaust gas can be removed because they are adsorbed on the activated carbon.

In the present invention, the activated carbon filled in the adsorption tower moves in a direction substantially orthogonal to the passage direction of the exhaust gas and is cut out of the adsorption tower, so that the contact time with the exhaust gas is long. It is possible to sequentially take out the activated carbon from the activated carbon having a reduced adsorption ability. Since the cut-off activated carbon is regenerated in the desorption tower and returned to the adsorption tower, the activated carbon whose adsorption capacity has been restored can be sequentially replenished into the adsorption tower.

Further, the adsorption tower is divided into a plurality of filling chambers along the passage direction of the exhaust gas, and the activated carbon having a larger particle size (coarse particles) is filled in the filling chamber closer to the exhaust gas inlet and closer to the exhaust gas outlet. Since the filling chamber is filled with activated carbon having a smaller particle size, the efficiency of removing soot and dust can be significantly improved, and the passage of exhaust gas can also be prevented, so that the exhaust gas treatment effect is also improved.

Therefore, according to the present invention, since the harmful substances contained in the exhaust gas are removed by the short-time treatment of substantially the same treatment, the equipment space can be greatly reduced.

Further, since the activated carbon having a reduced adsorption capacity can be regenerated while treating the exhaust gas, the exhaust gas treatment device can be continuously operated.

Further, the desorption tower has a relatively low temperature (for example, 300 to 40) when the heat desorption operation is carried out in an inert gas atmosphere.
Dioxy and the like can be decomposed at 0 ° C.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the basic configuration of the first embodiment of the present invention.
It is a schematic block diagram which shows the exhaust gas processing apparatus of a corresponding municipal waste incinerator.

The basic configuration of the present invention is an electrostatic precipitator 10 for initially treating exhaust gas from an unillustrated municipal refuse incinerator,
Ammonia is injected into the exhaust gas treated by the dust collector.
Ammonia injection means 12 for mixing, an adsorption tower 14 for treating the exhaust gas mixed with ammonia for treatment, and a desorption tower 16 for regenerating the activated carbon cut out from the adsorption tower 14.
It has and.

The above-mentioned electric dust collector 10 focuses on removing soot and dust contained in the exhaust gas of municipal waste, and the collected soot and dust is the roll feeder 18a at the lower end.
It is possible to take out from.

The adsorption tower 12 is composed of an inlet louver, an activated carbon layer, and an outlet louver (not shown), and has a particle size of 3 to 15
It is filled with mm granular activated carbon. The exhaust gas mixed with ammonia passes through the adsorption tower 12 in the right direction in the figure,
After receiving the adsorption treatment with activated carbon, it is discharged to the chimney through the pipe attached to the upper right part.

In addition, in the adsorption tower 14, the activated carbon filled moves downward (in a direction orthogonal to the passage direction of the exhaust gas), and from the one having a long contact time with the exhaust gas to the outside by the roll feeder 18b at the lower end. It is designed to be cut out.

The activated carbon, which is cut out of the adsorption tower 14 and has a reduced adsorption capacity, is supplied to the upper part of the desorption tower 16 by the transfer conveyor 20a. The specific structure of the adsorption tower 14 will be described later.
Will be described in detail.

In the desorption tower 16, an inert carrier gas is introduced and the activated carbon is indirectly heated in the presence of the carrier gas. The heating temperature is, for example, 300 to 65
A suitable temperature can be selected in the range of 0 ° C.

The unnecessary gas desorbed from the activated carbon as a result of the indirect heating is introduced into the off-gas treatment device 22 and subjected to a predetermined treatment. On the other hand, the regenerated activated carbon that has recovered its adsorption ability due to the desorption of unnecessary gas is cut out to the screen 24 from the roll feeder 18c at the lower end of the desorption tower 16.

The regenerated activated carbon cut out on the screen 24 is separated into dust by the screen 24, conveyed by the transfer conveyor 20b, and supplied to the upper part of the adsorption tower 14.

In this embodiment, the above operation is continuously repeated.

Next, for convenience of explanation, first, this basic structure will be described.
Therefore, the operation obtained will be described.

Exhaust gas from the municipal refuse incinerator is first introduced into the electric dust collector 10 and most of the dust is removed by this device.

The soot dust and exhaust gas that cannot be completely removed are
It is introduced into the next adsorption tower 14 together with the ammonia injected from the ammonia injection means 12.

Soot and dust are completely caught by the activated carbon that has been filled, and hydrogen chloride, hydrogen fluoride and sulfur oxides undergo the reactions shown in the above formulas (1) to (3) in the presence of ammonia. Then, the nitrogen oxides are easily adsorbed on the activated carbon, the nitrogen oxides are converted into harmless substances according to the above formulas (4) and (5), and further, dioxins and heavy metals are also adsorbed on the activated carbon.

As described above, in the adsorption tower 14, all of soot dust, hydrogen chloride, hydrogen fluoride, sulfur oxides, nitrogen oxides, as well as dioxins, heavy metals and the like, which have been difficult to be dealt with in the past, are simultaneously removed. It becomes possible to do.

The activated carbon having adsorbed the harmful substances is cut out from the lower part of the adsorption tower 14 in the order of the adsorbed amount, regenerated in the desorption tower 16 and supplied again to the upper part of the adsorption tower 14. . Therefore, it is possible to continuously operate the exhaust gas treatment device of the municipal refuse incinerator at a sufficient adsorption capacity.

When the exhaust gas treating apparatus for an urban refuse incinerator according to this basic structure was actually applied to exhaust gas treatment, the results shown in Table 2 below were obtained.

[0039]

[Table 2]

From Table 2 above, it is clear that this basic configuration has an extremely excellent exhaust gas purification treatment capacity.

In this basic structure , as shown in FIG. 2, the electrostatic precipitator 10 and the adsorption tower 14 are directly connected to each other, and ammonia is injected in front of the inlet louver 25 of the adsorption tower 14.
It may be deformed .

FIG. 3 shows the adsorption tower 14 in the basic structure.
It is a schematic block diagram which shows the specific example of .

[0043]

The adsorption tower 14 has first, second and third filling chambers 14a, 14b and 14 along the passage direction of the exhaust gas.
Divided into c. Each filling chamber 14a, 14b and 14
At the boundary of c , gas can pass but activated carbon cannot pass.

The particle size of the first filling chamber 14a is 15 to 15
Coarse activated carbon of 10 mm has a particle size of 10 in the second filling chamber 14b.
Medium activated carbon of ˜6 mm is filled in the third filling chamber 14c, and fine activated carbon having a particle size of 4 to 3 mm is filled in the third filling chamber 14c.

Further, roll feeders 18d, 18e for cutting out the activated carbon are provided below the filling chambers 14a, 14b, 14c, respectively.
18f is provided, and the activated carbon that has been cut out is collectively transferred to the desorption tower for regeneration treatment.

The activated carbon regenerated in the desorption tower is passed through the sieving machine 26.
The particles are classified to have a predetermined particle diameter and are returned to the corresponding filling chambers 14a, 14b and 14c again.

According to this embodiment, the adsorption tower 1 using soot and dust
Since the fourth clogging can be prevented, on the same effects as those of the basic configuration is further exerted, it is possible to further efficiently remove the soot dust.

Although the present invention has been specifically described above, it is needless to say that the present invention is not limited to those shown in the above embodiments.

For example, when the adsorption tower is partitioned into a plurality of packing chambers, the number of the adsorbing towers may be two or four or more.

The treatment apparatus of the present invention is not limited to the exhaust gas of the municipal waste incinerator, but can be used for general exhaust gas treatment.

[0052]

As described above, according to the present invention, dust collection, demineralization, denitration, and
Since desulfurization, dioxin removal, and heavy metal removal can be performed at the same time, the exhaust gas treatment equipment can be simplified and the space efficiency can be greatly improved, which is an excellent effect.

Further, at that time, the adsorption tower is divided into a plurality of filling chambers along the exhaust gas passage direction, and the particle size of the activated carbon is increased in the filling chamber closer to the gas inlet, so that the exhaust gas treatment efficiency is further enhanced. The excellent effect that it can improve is acquired.

[Brief description of drawings]

[1] of the municipal solid waste incinerator exhaust gas treatment apparatus according to the present invention
Schematic diagram showing the basic configuration

FIG. 2 is a schematic configuration diagram showing a main part of a modified example of the basic configuration .

FIG. 3 is a schematic configuration diagram showing a main part of an adsorption tower according to an embodiment of the present invention .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 53/94 B03C 3/02 B B01D 53/36 102 F

Claims (1)

[Claims] 1. An exhaust gas treatment device for an urban waste incinerator that removes harmful substances from the exhaust gas of an urban waste incinerator, and an electric dust collector that removes soot and dust from the exhaust gas, and means for injecting and mixing ammonia in the exhaust gas. The adsorption tower filled with activated carbon, which allows the exhaust gas after soot removal to pass through together with ammonia to adsorb and remove harmful substances in the exhaust gas, and the activated carbon in the adsorption tower, are substantially orthogonal to the passage direction of the exhaust gas. Direction, and means for cutting out outside the adsorption tower, a desorption tower for regenerating the cut out activated carbon, and means for returning the regenerated activated carbon into the adsorption tower , wherein the adsorption tower passes through the exhaust gas. It is divided into a plurality of filling chambers along the direction, and these filling chambers are filled with activated carbon with a larger particle size in order from the one closer to the exhaust gas inlet. And is moved in a direction substantially perpendicular to, and hand stage cut into each filling outdoor, after playing cut activated carbon in the desorption column, and means for classifying the grain each diameter, corresponding classified activated carbon to the particle diameter An exhaust gas treatment device for an urban refuse incinerator, characterized in that: means for returning to each of the filling chambers are installed.