JPH04687B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for removing harmful gases by blowing lime powder into exhaust gas containing harmful gases such as hydrogen chloride and sulfur oxides exhausted from an incinerator or the like. The present invention relates to a hazardous gas treatment device.

[Conventional technology]

The combustion exhaust gas exhausted from the incinerator is caused by the thermal decomposition of PVC plastics contained in the incinerated materials.
600-1000ppm hydrogen chloride and sulfur oxides (SOx)
Contains harmful gases such as

Traditionally, this harmful gas has been removed dryly by injecting lime powder such as slaked lime or quicklime into the exhaust gas, but the removal rate is low because there is insufficient contact between the exhaust gas and lime powder. There's a problem.

For this reason, hydrogen chloride is removed from the exhaust gas by passing it through a moving bed filled with quicklime or the like.
In other words, a punched plate, screen, or louver is placed facing the exhaust gas flow.
In the meantime, quicklime is filled and circulated downward to form a packed moving bed, and harmful gases are removed by passing exhaust gas through the moving bed.

[Problem that the invention seeks to solve]

However, this packed moving bed type exhaust gas treatment equipment is installed downstream of the electrostatic precipitator, and the cross-sectional area of the packed moving bed is The gas velocity is lowered to around 0.2m/sec. Therefore, there are problems in that the installation area is large and the price is high.

When attempting to increase the removal rate of harmful gases by blowing slaked lime powder etc. into the exhaust gas and installing a moving bed filled with a carrier downstream, if the filled moving bed is installed downstream of the electrostatic precipitator, the electrostatic precipitator will Slaked lime powder, etc. blown into the front of the vessel is collected by the electrostatic precipitator, which worsens the reaction within the moving bed. On the other hand, if slaked lime powder is blown into the wake of the electrostatic precipitator, it is necessary to install the electrostatic precipitator again in the wake of the moving layer.

Therefore, if you install the packed moving bed in front of the electrostatic precipitator, and if you try to install the packed moving bed in front of the electrostatic precipitator with the same cross-sectional area in order to make the device more compact, the filling moving bed inlet gas The conditions were high dust content gas, and the operation was to be carried out at a passage speed equivalent to the gas velocity in the electrostatic precipitator (approximately 0.6 m/sec), which was lower than that of a conventional packed moving bed (approximately 0.6 m/sec).
0.2m/sec), and measures to reduce pressure loss are required.

The present invention has been made in consideration of the above circumstances, and is a compact, highly dust-removal device that passes exhaust gas with high dust content and the same velocity as the gas velocity in the electrostatic precipitator through a packed moving bed. The purpose is to provide a gas removal device.

[Means and actions for solving problems]

In order to achieve the above object, the present invention blows lime powder into combustion exhaust gas containing harmful gases exhausted from an incinerator, etc., and removes lime powder that has reacted with the harmful gases and unreacted lime powder. In a hazardous gas treatment device that removes dust from exhaust gas, a carrier such as sand moves in the direction of gravity so as to be transverse to the flow of exhaust gas and captures the lime powder in the casing into which the exhaust gas is introduced. A layer is formed, louvers are provided at a predetermined interval above and below on both sides of the moving layer, the front and rear louvers are shifted vertically from each other, and each louver is tilted downward from the center of the moving layer; The carriers are alternately held by front and rear louvers and placed close to each other, and a dust collector is installed behind the casing in which the moving layer is formed to remove dust etc. scattered from the moving layer. First, lime powder is blown into the exhaust gas, and the lime powder that has reacted with harmful gases such as hydrogen chloride and unreacted lime powder are captured together with the dust in a moving layer, and the unreacted harmful gases in the exhaust gas are captured in the moving layer. By bringing the carrier into contact with unreacted lime powder, the removal rate of harmful gases is increased, and by placing the front and rear louvers close to each other and shifting them up and down, the carrier is held by the front and rear louvers and moves downward, removing exhaust gas. This ensures good contact between the gases and prevents clogging due to dust even at high gas velocities.Furthermore, an electrostatic precipitator is integrated into the casing downstream of this moving layer, allowing the gas to move while maintaining the same velocity. This makes it possible to remove dust etc. scattered from the layer.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a harmful gas treatment apparatus according to the present invention will be described below with reference to the accompanying drawings.

In Figure 1, 1 is an incinerator such as a fluidized bed;
A gas cooling device 2 is connected to the exhaust gas outlet, a harmful gas treatment device 4 is connected to its downstream side through a duct 3, and a chimney 6 is connected to its downstream side through an induced blower 5, thereby forming a garbage incineration plant. Ru.

A duct 3 leading from the gas cooling device 2 to the harmful gas treatment device 4 is supplied with lime powder for injecting lime powder such as slaked lime (Ca(OH) ₂ ) or quicklime (CaO) into the exhaust gas passing through the duct 3. Device 7 is connected.

The lime powder supply device 7 includes a hopper 8 for discharging lime powder, a blower 9 for supplying conveying air, and a conveying line 10 connected to the duct 3.

As shown in FIG. 2, the harmful gas treatment device 4 consists of a casing 11 into which the exhaust gas into which lime powder is blown is introduced, and inside the casing 11 there is a granular carrier that moves in the direction of gravity so as to be transverse to the flow of the exhaust gas. 12 is formed, and an electrostatic precipitator 14 is provided in the casing 11 on the downstream side of the moving layer 13.

As shown in FIGS. 2 and 3, the moving layer 13 is provided with a front louver 15 on its front side, a rear louver 16 on its rear side, and silica sand, silica sand, etc.
It is formed by being filled with a granular carrier 12 such as limestone, slag, cement clinker, etc.

The front and rear louvers 15 and 16 are connected to the casing 11
are provided at predetermined intervals along the vertical direction, and a front louver 15 and a rear louver 16, respectively.
and are provided so that their vertical positions are shifted from each other. Further, each of the louvers 15 and 16 is inclined downward from the center of the moving layer 13, and is provided so that the front and rear louvers 15 and 16 are close to each other.

At the top of the casing 11 are front and rear louvers 1.
A hopper 17 for supplying the granular carrier 12 is provided between 5 and 16, and a louver 1 is provided at the bottom.
A rotor 19 is provided for discharging the granular carrier 12 that has descended between 5 and 16 to a hopper 18 at the bottom of the casing 11.

As shown in FIG. 1, the granular carriers 12 and the like accumulated in the lower hopper 18 are discharged to a classifier 20, where lime powder and dust are separated from the granular carriers 12, and the granular carriers 12 are transported to the upper part via a vertical conveyor 21. It is designed to be circulated to the hopper 17.

The electrostatic precipitator 14 includes a plurality of dust collecting plates 22 arranged parallel to the exhaust gas flow as shown in FIG.
and a large number of linear discharge electrodes 23 arranged along between the dust collecting plates 22.

In the above, combustion exhaust gas containing harmful gases such as hydrogen chloride is exhausted from the incinerator 1 due to the thermal decomposition of the PVC plastics contained in the incinerated material, and after its heat is recovered by the gas cooling device 2, Flows into duct 3.

Lime powder is blown into the duct 3 from a lime powder supply device 7, and this lime powder reacts with hydrogen chloride in the exhaust gas to become calcium chloride and remove the hydrogen chloride. In the case of SOx, lime powder turns into calcium sulfate and removes SOx.

The exhaust gas into which the lime powder has been blown is introduced into the casing 11, where it passes through the front louver 15, the inside of the moving layer 13, and is exhausted from the rear louver 16, where lime powder and ducts in the exhaust gas are captured. That will happen. In this case, unreacted harmful gases in the exhaust gas will come into contact with the lime powder or the granular carrier 12 if limestone is used as the lime powder or granular carrier 12 that is trapped in the moving layer 13 while passing through the moving layer 13. Because of this reaction, the removal rate of harmful gases can be increased.

As shown in FIG. 3, the granular carriers descending on the moving layer 13 are moved by the front and rear louvers 15 and 16 being brought close to each other, as shown in FIG.
In addition, since they are arranged vertically shifted from each other, they alternately collide with the front louver 15 and the rear louver 16 while descending and moving as shown by the arrows in the figure. Therefore, the moving layer 13 is not consolidated and dust and harmful The lime powder that has reacted with the gas can be captured, and the pressure loss of the exhaust gas passing through the moving layer 13 can be reduced.

As shown in Fig. 4, the front and rear louvers 15, 16 have an inclination α of about 60 degrees, and a distance L between the upper and lower louvers 15, 16 of about 100 mm.
The distance d between the tips of the front and rear louvers 15 and 16 is −
By keeping the distance within the range of about 5 mm to 25 mm, lime powder and dust can be captured well and a moving layer 13 with low pressure loss can be formed. The descending speed of the carrier 12 within the moving layer 13 can be adjusted.

Next, the exhaust gas that has passed through the moving bed 13 contains some dust and lime powder scattered from between the rear louvers 16, but the dust and lime powder are removed by the electrostatic precipitator 14 installed integrally in the wake of the casing 11. Ru.

The exhaust gas flow rate passing through this electrostatic precipitator 14 is
Since it is approximately 0.6 m/sec, the flow velocity of the exhaust gas passing through the moving bed 13 is also set to be at this flow velocity.

The exhaust gas from which dust and harmful gases have been removed by the electrostatic precipitator 14 is discharged from the chimney 6 via the induced blower 5 as clean gas.

〔Effect of the invention〕

As is clear from what has been described in detail above, the present invention exhibits the following excellent effects.

(1) Lime powder is blown into exhaust gas containing harmful gases, and the lime powder in the exhaust gas captures dust through a moving layer of carrier formed by louvers, increasing the removal rate of harmful gases.

(2) By placing the front and rear louvers close to each other and shifting the positions of the front and rear louvers up and down, the carriers of the moving bed can be lowered while being held alternately by the front and rear louvers, so the moving bed is not consolidated and high content can be achieved. Even if the dust gas is used at the same gas speed as the electrostatic precipitator, the pressure loss of the exhaust gas can be reduced.

(3) By installing an electrostatic precipitator integrally in the casing on the downstream side of the moving bed and making the gas velocity the same, the device can be made compact and dust etc. scattered from the moving bed can be removed.

[Brief explanation of drawings]

FIG. 1 is an overall view showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view of the main part of the harmful gas treatment equipment in Figure 1, Figure 3 is a cross-sectional view showing details of the moving layer in Figure 2, and Figure 4 is a cross-sectional view showing the details of the moving layer in Figure 2.
The figure is a diagram showing details of the louver in FIG. 3. In the figure, 1 is an incinerator, 3 is a duct, 4 is a harmful gas removal device, 7 is a lime powder supply device, 11 is a casing, 12 is a carrier, 13 is a moving bed, 14 is an electrostatic precipitator, and 15 is a front louver. , 16 is a rear louver.

Claims (1)

[Claims] 1. In a harmful gas treatment device that blows lime powder into combustion exhaust gas containing harmful gases exhausted from an incinerator, etc., and removes lime powder that reacts with the harmful gas and unreacted lime powder from the exhaust gas along with dust. , a moving layer made of a carrier such as sand is formed in the casing into which exhaust gas is introduced, which moves in the direction of gravity so as to be transverse to the flow of the exhaust gas and captures the lime powder; louvers are provided at a predetermined interval above and below, the front and rear louvers are shifted vertically from each other, and each louver is tilted downward from the center of the moving layer;
In addition, the carriers of the moving layer are alternately held by front and rear louvers and placed close to each other, and a dust collector is integrated behind the casing in which the moving layer is formed to remove dust etc. scattered from the moving layer. A hazardous gas treatment device characterized by being installed in.