JPH04277005A - Exhaust gas treatment apparatus of urban garbage incinerator - Google Patents

Abstract

PURPOSE:To miniaturize equipment by treating harmful substances such as soot, hydrogen chloride, NOx, SOx, dioxin or heavy metals in a short process. CONSTITUTION:Exhaust gas is passed through an electric precipitator 10 and subsequently mixed with ammonia to be passed through an adsorbing tower 14 packed with activated carbon to simultaneously treat and remove harmful substances. Activated carbon is discharged from the lower part of the adsorbing tower 14 while the exhaust gas is subjected to adsorbing treatment to be regenerated in a desorbing tower 16 and the regenerated activated carbon is again returned to the upper part of the adsorbing tower 14 and activated carbon is continuously supplied to perform continuous operation.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is particularly useful for municipal waste that can simultaneously process harmful substances such as soot, chlorine, fluorine, nitrogen oxides, sulfur oxides, dioxins, and heavy metals discharged from the exhaust gas of municipal waste incinerators. This invention relates to an incinerator exhaust gas treatment device.

0002

[Prior Art] As shown in Table 1 below, the exhaust gas emitted from municipal waste incinerators contains soot, hydrogen chloride (HCl), nitrogen oxides (NOx), and sulfur oxides (SOx). , chemical substances such as dioxins, and solid and gaseous harmful substances such as heavy metals, it is extremely important to remove these harmful substances from exhaust gas in order to preserve the surrounding environment and the global environment.

0003

[Table 1]

[0004] Conventionally, measures to remove the above-mentioned harmful substances include dust collection to remove soot, denitrification to remove NOx, and SOx.
Each unit operation, such as desulfurization to remove hydrogen chloride and desalination to remove hydrogen chloride, can be carried out using, for example, exhaust gas treatment equipment connected in series.
This is done by treating exhaust gas in stages and treating harmful substances individually.

[0005]

However, the above-mentioned exhaust gas treatment equipment that treats harmful substances individually and in stages has the disadvantage that it requires a large installation space and is therefore expensive.

[0006] Furthermore, since the conventional treatment equipment described above is not technically capable of removing dioxins and heavy metals, it is necessary to add new equipment to remove them. There is also the problem that a larger installation space is required.

[0007] The present invention was made to solve the above-mentioned conventional problems, and it
It is an object of the present invention to provide a municipal waste incinerator exhaust gas treatment device that can remove harmful substances such as x, dioxins, heavy metals, etc. by substantially simultaneous treatment, and can therefore reduce the equipment space.

[0008]

[Means for Solving the Problems] The present invention provides an electrostatic precipitator for removing soot and dust from the exhaust gas, and an electrostatic precipitator for removing soot and dust from the exhaust gas, in an exhaust gas treatment device for a municipal garbage incinerator that removes harmful substances from the exhaust gas of the municipal garbage incinerator. A means for injecting and mixing ammonia, an adsorption tower filled with activated carbon that allows exhaust gas after soot and dust removal to pass together with ammonia, and adsorbs and removes harmful substances in the exhaust gas, and activated carbon in the adsorption tower. means for moving the activated carbon in a direction substantially perpendicular to the passing direction of the exhaust gas and cutting it out of the adsorption tower; a desorption tower that regenerates the cut activated carbon;
The above problem has been solved by providing means for returning the regenerated activated carbon into the adsorption tower.

The present invention also provides the above-mentioned municipal waste incinerator exhaust gas treatment device, in which the adsorption tower is partitioned into a plurality of filling chambers along the exhaust gas passage direction, and these filling chambers include one near the exhaust gas inlet. Activated carbon of larger particle size is filled in order from 1 to 3, and the activated carbon in each filling chamber is moved in a direction substantially perpendicular to the exhaust gas passage direction to cut it out of each filling chamber, and the cut activated carbon is desorbed. After being regenerated in the tower, the structure is equipped with a means for classifying the activated carbon according to particle size and a means for returning the classified activated carbon to each of the filling chambers according to the particle size.
This more reliably solves the above problem.

0010

[Operation] Generally, city gas contains a lot of soot and dust, but in the present invention, the exhaust gas is first treated with an electrostatic precipitator. As a result, most of the soot and dust is removed at this stage.

Next, when the exhaust gas containing soot and other harmful substances that could not be completely removed is passed through an adsorption tower together with ammonia, hydrogen chloride contained in the exhaust gas is removed as it passes through the adsorption tower. (HCl), hydrogen fluoride (
HF) and sulfur dioxide (SO2) react with mixed ammonia as shown in the following equations (1) to (3), so these harmful substances can be easily adsorbed onto activated carbon as reaction products. Can be removed. In addition, (A) in the formula is “
It represents "adsorption".

(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)

[0013] Furthermore, NOx contained in the exhaust gas is
Activated carbon acts as a catalyst, and as shown in the following equations (4) and (5), it can be reduced to harmless nitrogen by ammonia, so it can be removed reliably.

(4) NO+NH3 +1/4O2

→ N2 +3/2H2 O (
5) NO2 +4/3NH3 → 7/6N
2 +2H2 O

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

In the present invention, the activated carbon packed in the adsorption tower moves in a direction substantially perpendicular to the direction in which the exhaust gas passes and is cut out of the adsorption tower, so the contact time with the exhaust gas is extended. , activated carbon whose adsorption capacity has decreased can be sequentially removed from the system. Since the cut activated carbon is regenerated in the desorption tower and returned to the adsorption tower, the activated carbon whose adsorption capacity has been recovered can be sequentially replenished into the adsorption tower.

In addition, the adsorption tower is divided into a plurality of packed chambers along the exhaust gas passage direction, and the closer the packed chamber is to the exhaust gas inlet, the larger the particle size (coarse particles) of activated carbon is filled, and the closer to the exhaust gas outlet is filled with activated carbon. Since the activated carbon having a smaller particle size is filled in the filling chamber, the removal efficiency of soot and dust is greatly improved, and since the passage of exhaust gas can be prevented from being obstructed, 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 substantially simultaneous short-step processing, the equipment space can be significantly reduced.

Furthermore, since the activated carbon whose adsorption capacity has decreased can be regenerated while treating the exhaust gas, the exhaust gas treatment apparatus can be operated continuously.

[0020] Furthermore, when performing a thermal desorption operation in an inert gas atmosphere, the desorption tower is used at a relatively low temperature (for example, 300 to 40
Dioxy, etc. can be decomposed at 0℃).

[0021]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an exhaust gas treatment device for a municipal waste incinerator according to a first embodiment of the present invention.

This embodiment includes an electrostatic precipitator 10 that initially processes exhaust gas from a municipal garbage incinerator (not shown), and an ammonia injection means 12 that injects and mixes ammonia into the exhaust gas treated by the dust collector. , an adsorption tower 14 that passes through and processes exhaust gas mixed with ammonia, and a desorption tower 16 that regenerates the activated carbon cut out from the adsorption tower 14.

[0024] The electrostatic precipitator 10 is designed to intensively remove soot and dust contained in large amounts in the exhaust gas of municipal waste, and the collected soot and dust are transferred to the roll feeder 18a at the lower end.
It can be taken 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 4 to 10 m.
Filled with m granular activated carbon. The exhaust gas mixed with ammonia passes through the adsorption tower 12 in the right direction in the figure,
After being adsorbed with activated carbon, it is discharged into the chimney via a pipe attached to the upper right corner.

In addition, in the adsorption tower 14, the charged activated carbon moves downward (in a direction perpendicular to the direction in which the exhaust gas passes), and the activated carbon that has been in contact with the exhaust gas for a longer time is sequentially transported to the outside by the roll feeder 18b at the lower end. It is designed to be cut out.

The activated carbon cut out of the adsorption tower 14 and having a reduced adsorption capacity is supplied to the upper part of the desorption tower 16 by a transfer conveyor 20a.

In the desorption column 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
An appropriate temperature can be selected within the range of 0°C.

[0029] As a result of the above indirect heating, the unnecessary gas desorbed from the activated carbon is introduced into the off-gas treatment device 22 and undergoes a predetermined treatment. On the other hand, the regenerated activated carbon whose adsorption capacity has been recovered due to the removal 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 recycled activated carbon cut into the screen 24 is separated from 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 operations are continuously repeated.

Next, the operation of this embodiment will be explained.

The exhaust gas from the municipal waste incinerator is first introduced into the electrostatic precipitator 10, and most of the soot and dust is removed by this device.

[0034] The soot and dust and exhaust gas that could not be completely removed are:
Together with the ammonia injected from the ammonia injection means 12, it is introduced into the next adsorption tower 14.

[0035] Soot and dust are completely captured by the packed activated carbon, and hydrogen chloride, hydrogen fluoride, and sulfur oxide undergo the reactions shown in equations (1) to (3) above in the presence of ammonia. Nitrogen oxides are easily adsorbed on activated carbon, and nitrogen oxides are converted into harmless substances according to the above equations (4) and (5). Furthermore, dioxins and heavy metals are also adsorbed on activated carbon.

In this manner, the adsorption tower 14 collects soot, dust, hydrogen chloride, hydrogen fluoride, sulfur oxides, nitrogen oxides,
Furthermore, it becomes possible to remove all of dioxins, heavy metals, etc., which were difficult to deal with in the past, by simultaneous treatment.

[0037] Furthermore, the activated carbon that has adsorbed the harmful substances is cut out from the lower part of the adsorption tower 14 in descending order of adsorption amount, is regenerated in the desorption tower 16, and is again supplied to the upper part of the adsorption tower 14. . Therefore, it is also possible to constantly operate the exhaust gas treatment device of the municipal waste incinerator under sufficient adsorption capacity.

When the exhaust gas treatment device for a municipal waste incinerator of this example 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 example has an extremely excellent exhaust gas purification ability.

In this embodiment, as shown in FIG.
The electrostatic precipitator 10 and the adsorption tower 14 may be directly connected, and ammonia may be injected into the adsorption tower 14 in front of the entrance louver 25.

FIG. 3 is a schematic diagram showing an adsorption tower which is a main part of an exhaust gas treatment device for a municipal waste incinerator according to a second embodiment.

The exhaust gas treatment system for a municipal waste incinerator according to this embodiment has substantially the same basic structure as the first embodiment except for the adsorption tower.

In this embodiment, the adsorption tower 14 has first, second and third filled chambers 14a, 1 along the exhaust gas passage direction.
It is divided into 4b and 14c. The boundaries of each filling chamber are designed to allow gas to pass through but not activated carbon.

[0045] The first filling chamber 14a contains particles with a particle size of 15
Coarse activated carbon with a particle size of ~10 mm is placed in the second filling chamber 14b, medium activated carbon with a particle size of 10 to 6 mm is placed in the third filling chamber 14c.
are each filled with thin activated carbon having a particle size of 4 to 3 mm.

[0046] Also, each filling chamber 14a, 14b, 14c
At the bottom of the roll feeder 18d for cutting activated carbon,
18e and 18f are provided, and the cut activated carbon is transferred all at once to a desorption tower, where it is regenerated.

[0047] The activated carbon regenerated in the desorption tower is passed through the sieve machine 26.
The particles are classified into predetermined particle sizes and returned to the corresponding filling chambers 14a, 14b, and 14c.

According to this embodiment, the adsorption tower 1 due to soot and dust
4 can be prevented from clogging, the same effects as those of the first embodiment can be further exhibited, and the soot and dust can also be efficiently removed.

Although the present invention has been specifically explained above, it goes without saying that the present invention is not limited to what has been shown in the above embodiments.

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

The treatment apparatus of the present invention can be used not only for treating exhaust gas from municipal waste incinerators, but also for general exhaust gas treatment.

[0052]

[Effects of the Invention] As explained above, according to the present invention, dust collection, desalination, denitrification, and
Since desulfurization, dioxin removal, and heavy metal removal can be performed simultaneously, the exhaust gas treatment equipment can be simplified and space efficiency can be greatly improved, which is an excellent effect.

[0053] Furthermore, if the adsorption tower is divided into a plurality of packed chambers along the exhaust gas passage direction, and the particle size of the activated carbon is made larger in the packed chambers closer to the gas inlet, there is an advantage that the exhaust gas treatment efficiency can be further improved. You can get the same effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a municipal garbage incinerator exhaust gas treatment device according to a first embodiment.

FIG. 2 is a schematic configuration diagram showing main parts of a modification of the first embodiment.

FIG. 3 is a schematic configuration diagram showing main parts of a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10... Electrostatic precipitator, 12... Ammonia injection means, 14... Adsorption tower, 14a-14c... Filling chamber, 16... Desorption tower, 18a-18f... Roll feeder, 20a, 20
b...Transfer conveyor, 26...Sieving machine.

Claims (2)

[Claims] Claim 1: An exhaust gas treatment device for a municipal garbage incinerator that removes harmful substances from the exhaust gas of a municipal garbage incinerator, comprising an electrostatic precipitator that removes soot and dust from the exhaust gas, and a means for injecting and mixing ammonia into the exhaust gas. , an adsorption tower filled with activated carbon that passes through the exhaust gas after soot and dust removal together with ammonia and adsorbs and removes harmful substances in the exhaust gas; and the activated carbon in the adsorption tower is arranged approximately perpendicular to the direction of passage of the exhaust gas. Municipal garbage, comprising means for moving the activated carbon in the direction and cutting it out of the adsorption tower, a desorption tower for regenerating the cut activated carbon, and a means for returning the regenerated activated carbon into the adsorption tower. Incinerator exhaust gas treatment equipment. 2. In claim 1, the adsorption tower is partitioned into a plurality of packed chambers along the exhaust gas passage direction, and these packed chambers are filled with activated carbon having a larger particle size in order from the one closest to the exhaust gas inlet. In addition, the activated carbon in each filling chamber is moved in a direction substantially perpendicular to the exhaust gas passage direction and cut out of each filling chamber, and after the cut activated carbon is regenerated in a desorption tower, it is separated by particle size. 1. An exhaust gas treatment device for a municipal waste incinerator, comprising means for classifying the activated carbon into particles, and means for returning the classified activated carbon to each of the filling chambers according to the particle size.