JPS6219208B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moving bed filter, and more particularly to a moving bed filter that allows gas to pass through a moving bed of filler held between a plurality of louvers arranged at predetermined intervals. .

A moving bed filter is used as a dust collector, for example, in a device for removing hydrogen chloride (HCl) from exhaust gas from incineration of municipal waste. This type of moving bed filter can be expected to cause a reaction between unreacted powder and unreacted gas in the packing material layer, so it has the advantage of being able to shorten the residence time for gases to react. has. Therefore, the inventors set up a part for spraying the powder reactant in the front stage of the moving bed filter as shown in Figure 1, and by moving the filling material of the moving bed filter at an appropriate speed, the amount of air in the exhaust gas was reduced. An experiment was conducted to remove specific chemicals. The illustrated device includes a forced air blower 5 for introducing slaked lime in the hopper 1 into an inlet hood 12, and an inlet hood 12.
A moving bed filter 3 that passes gas and slaked lime powder introduced into the moving bed filter 2, a plurality of harbors 18 that support the filling material 2 of the moving bed 3 from both sides, and mixing from the filling material exiting the lower part of the moving bed filter 3. a separator 16 for separating dust 20; a bucket conveyor 17 for recycling the filler 2 separated by the separator to the feed chute 14 of the moving bed; It mainly consists of an exhaust gas blower 4 for discharging the exhaust gas. In the above experimental results, the desired HCl removal rate was obtained, but
When the amount of slaked lime powder sprayed or the gas flow rate was increased, a problem occurred in that part of the sprayed powder or adhesive dust adhered to the louver surface. This powder adhesion to the louver surface tends to cause problems such as obstruction of gas flow when the device is operated continuously for a long time.

On the other hand, a method can be considered in which the gas flowing toward the louver surface is rectified as much as possible to sufficiently disperse the powder particles, thereby avoiding local adhesion of the powder. This can be done by reducing the cone angle of the hood that guides the gas to the moving bed filter and gently expanding the gas flow path, by installing a dispersion plate to spread the flow uniformly, or by using the following methods:
As seen in No. 22178, a method of providing a flow cell 30 as shown in FIG. 2 has been proposed.
These methods disperse particles adhering to the louver surface and reduce the frequency of maintenance, but since the gas flow is at an angle close to perpendicular to the louver surface, There was a problem that the total amount of powder adhesion could not be reduced. For this reason, the present inventors previously considered a method of using a movable louver to brush off the adhered particles, but this method was intended for gases containing strong adhesion such as tar; The equipment becomes too complex to handle the deposition of

As described above, the conventional technology has the drawback that a portion of the sprayed powder adheres to the surface of the louver that supports the filler, causing problems such as blockage.

Although the above has described a moving bed filter used as a dry gas purification device, the above problems are not limited to this, and the above problem is not limited to moving bed filters that have louvers for capturing adhesive dispersed particles in gas. This was a common drawback.

An object of the present invention is to provide a moving bed filter that eliminates the drawbacks of the prior art, prevents powder from adhering to the louver surface that supports the filler, and is easy to maintain.

In order to achieve the above object, the present inventors conducted a thorough study on the state of powder adhesion to the louver surfaces, and found that this powder adhesion occurs when gas passes between the louver surfaces and enters the filler layer. It was discovered that because the gas flow path is bent, powder contained in the gas collides with the louver surface due to inertial force.

That is, in the present invention, the gas streamlines are directed in the direction of the louver surface so that the adhesion of powder to the surface of the louver that supports the filler is not affected by the angle between the louver surface and the gas streamline. The inclined surface of the louver on the gas inflow side is arranged so as to be approximately parallel to the gas inflow direction.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows an example of the present invention in exhaust gas.
FIG. 2 is a sectional view showing a dry HCl removal device. This dry removal device consists of a slaked lime feeder (hopper) 1, a moving bed filter 3 in which a filler 2 such as sand or sand is formed into a vertical flat moving bed, an exhaust gas blower 4, and an insert blower for supplying and spraying powder. 5, and piping 6A to 6C connecting them. The slaked lime feeder 1 also includes a rotary valve 8 disposed at the lower end of the slaked lime hopper 1, a slaked lime supply pipe 9 connected to the rotary valve 8, and a slaked lime attached to the tip of the supply pipe 9 to spray the slaked lime. It consists of a nozzle 10 for Furthermore, the moving bed filter 3 includes a filter section 11, an inlet hood 12 that guides gas to the filter section while enlarging the flow path, an outlet hood 13, a filler supply chute 14, and a filler supply chute 14 located at the bottom of the filter section 11. a discharging device 15 for forming a moving bed by discharging 2; a separating device 16 for powder and reaction products;
It is comprised of a bucket conveyor 17 that connects the separation device 16 and the supply chute 14 for the filling material 2, and the like. In the filter section 11, the filling material 2 is supported on both sides by louvers 18 formed by a plurality of plates inclined at an angle of 65 DEG to the horizontal direction. Inclined piping 6-C that sends gas to the inlet hood 12
As shown in Figure 3, the center line is 0 with respect to each plate forming the louver (the louver surface).
It is installed at an angle of °. A slaked lime spray nozzle 10 opens at the top of this inclined pipe 6C.

Next, the operation of the embodiment of the present invention will be explained.

Approximately HCl is contained in the exhaust gas from waste incinerators.
Contains 1000ppm. This exhaust gas 21 enters the inlet hood 12 via the horizontal pipe 6-A, the vertical pipe 6-B, and the inclined pipe 6-C. Inclined piping 6
Slaked lime powder 19 is blown from the nozzle 10 in -C. A certain amount of slaked lime powder 19 is cut out from the slaked lime storage tank 7 by a rotary valve 8, passes through a slaked lime supply pipe 9, and is sprayed from a nozzle 10 while being transported by a conveying gas. Here, the transport gas 22 may be air or exhaust gas. In addition, the particle size of the slaked lime powder 19 used in the example was 1 to 10μ.
(5μ on average). The slaked lime powder 19 sprayed into the gas is introduced into the inlet hood 12 together with the gas while being dispersed by turbulent mixing of the gas flow. During this time, a part of the slaked lime powder 19 reacts to form calcium chloride, which is an adhesive substance, and is present in the gas as mixed dust 20 together with the unreacted slaked lime powder, which is also adhesive. The flow path of the gas led from the inclined pipe 6-C to the inlet hood 12 is expanded here, and the flow velocity is reduced from about 10 m/s to 0.3 m/s. At this time, inside the inlet hood 12, the gas reaches the filter portion 11 while drawing a streamline as shown in FIG. This streamline differs depending on the position, but before the gas enters the inlet hood 12, it is given an inclination with respect to the horizontal direction by the action of the inertial force possessed by the inclined pipe 6-C. However, since the angle is close to parallel to each plate surface of the louvers 18 on the front surface of the filter portion 11, the layer of filler material 2 passes between the louvers without colliding violently with these surfaces. be blown inside. Therefore, the louver 1 due to the inertial force of the mixed dust in the gas
Adhesion to the 8 surfaces is minimized. Filler 2
The reaction of the gas that has entered the layer progresses as the mixed dust 20 is collected by the action of inertia and trapped particles. The cleaning gas 23 that has passed through the layer of filler passes through the outlet hood 13 between the plates of the louver 18 on the outlet side, where the flow path is reduced,
It is sent to the fan 4 from the outlet pipe 6-D and is discharged. On the other hand, the filler 2 that has captured the mixed dust 20 is
It gradually moves downward, and during this movement, unreacted slaked lime reacts with the gas it comes into contact with. Filler and mixed dust 20 taken out from the discharge device 15
is led to the separation device 16, where the mixed dust and the filler 2 are separated, and the filler 2 is conveyed to the top of the filter 3 via the bucket conveyor 17,
Reused.

FIG. 4 shows the relationship between the amount of mixed dust attached to the louver surface and the angle θ between the center line of the inclined pipe 6-C and each surface of the louver. It can be seen that when the angle becomes 30° or more, the amount of adhesion increases rapidly.

In this embodiment, in the outlet exhaust gas 23,
The HCl concentration was kept below 300 ppm, satisfying the target removal rate. Further, in the embodiment, the moving layer filter 3
The pressure loss at the inlet and outlet of the filter was reduced by 10 to 20 mmH ₂ O compared to when the conventional moving bed filter shown in FIG. 1 was used under the same conditions. This is because, according to the present invention, the pipe through which gas flows is substantially parallel to the louver surface, so that the gas naturally enters the gap between the filter fillers without being bent.

It should be noted that the present invention is not limited to the above embodiments, but can be similarly applied to gases containing adhesive dispersed particles. Further, even when the moving layer is an inclined moving layer and the louver holding the moving layer and the gas inflow direction are perpendicular, the same effects as in the above embodiment can be obtained.

As described above, according to the present invention, it is possible to minimize the adhesion of powder to the louver surface that supports the filler, thereby facilitating maintenance of the apparatus.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional moving layer filter, FIG. 2 is a sectional view showing an example of a louver of a conventional moving layer filter, and FIG. 3 is a sectional view showing an example of a moving layer filter of the present invention. A cross-sectional view of the device, FIG.
It is a graph showing an experimental example in the present invention. 1... Slaked lime supply machine, 2... Filler, 3... Moving bed filter, 4... Exhaust gas blower, 5... Forced blower,
17...bucket conveyor, 18...louver.

Claims (1)

[Claims] 1. In a moving bed filter that allows gas to pass through a moving layer of filler held between a plurality of louvers arranged at a predetermined interval, the inclination angle of the louver to which gas is supplied is determined by the inflow direction of the gas. A moving bed filter characterized in that a louver on the gas inlet side is arranged so as to be substantially parallel to the .