JPH0356086B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention uses a cylinder made of a ceramic material having excellent thermal shock resistance, such as mullite or cordierite, and is capable of being used at high temperatures of, for example, about 1100°C. The present invention relates to a method for processing dust-containing gas that can also collect dust-containing gas.

[Prior art and its problems] In electric furnaces, converters, etc. that generate a large amount of dust, it is necessary to remove dust from the exhaust gas. For this reason, in the past, high-temperature exhaust gas was cooled to a temperature at which dust could be collected using a bag filter or an electric precipitator, that is, 250°C for a bag filter and 350°C for an electric precipitator, or it was washed with water using a scrubber, etc. Ta. When using a bag filter or electrostatic precipitator,
Due to the large amount of dust contained in the gas, it is difficult to effectively recover heat from the high-temperature gas during the process of cooling it to a usable temperature range. No collection was carried out. Small-scale dust collectors that use ceramic cylinders that can directly process high-temperature exhaust gases have been put into practical use for special purposes, but industrial-scale dust collectors that can continuously collect dust have not yet been developed. It has not yet been put into practical use.

The following are possible reasons why large-scale dust collectors using ceramic cylinders have not been put into practical use. (a) The strength of porous ceramic tubes before firing is generally very low, and long ones are easily deformed during handling and firing, so the length was at most about 2 meters; Although bonding techniques exist, there are problems with bonding strength; and (c) even if long ceramic perforated tubes could be manufactured by some method, there would be no countermeasures against earthquakes, self-excitation, and other forced vibrations. Therefore, it is necessary to elastically support a large number of ceramic porous cylinders standing upright in a high-temperature atmosphere, but no suitable method has been thought of to do so; and (d) to process the large volume of gas for this purpose. In some cases, a large installation area was required.

[Object of the Invention] Therefore, in view of the problems of the prior art as described above, an object of the present invention is to provide a system which can reduce the installation area and which can treat high-temperature exhaust gas on an industrial scale. An object of the present invention is to provide a method for treating dust-containing gas.

[Structure of the Invention] The present invention supports the upper end and the lower end of a cylinder made of ceramic material using an upper tube sheet and a lower tube sheet, respectively, while substantially sealing the flow of dust. The cylinder is housed in a can having an inlet and a clean gas outlet, and the dust-containing gas from the dust-containing gas inlet is introduced into the cylinder at a downward speed of 5 to 50 m/s, and the dust-containing gas is This is a method for treating high-temperature dust-containing gas, which is characterized in that it is made to flow while swirling inside a cylinder.

In a preferred embodiment of the present invention, the dust-containing gas also has an axial velocity at the lower part of the cylinder.

According to the present invention, dust-containing gas is introduced into the cylinder from the dust-containing gas inlet of the can body, dust is removed in the process of flowing out of the cylinder through the cylinder wall, and clean gas can be taken out from the clean gas outlet. .

Although the number of cylinders may be one, it is preferable that a plurality of cylinders are erected in parallel to each other to form a group of cylinders.

Each cylinder may be formed as a single piece from the upper end to the lower end, but generally, long single-piece ceramic cylinders are easily deformed during the handling and firing process, so they are formed into short units made of porous solids. It is preferable to connect the tubes to form a single tube. At this time, if the joints of the unit cylinders in the tube or group of tubes are sealed and supported by tube plates, the tube or group of tubes has sufficient vibration resistance and strength.

By introducing dust-containing gas downward from the top at a relatively high speed of 5 to 50 m/s into a cylinder, especially a long cylinder made by connecting unit cylinders, the processing air volume per cylinder can be increased. The installation space can be reduced.

In carrying out the invention, it is preferable to form a cooling jacket within the tube sheet that supports the tube or group of tubes. That is, this is to prevent the tube sheet from being thermally damaged by high-temperature gas when the tube sheet is made of metal.

Moreover, it is preferable to provide a heat insulating material on the inner wall of the can body. That is, the purpose is to minimize the amount of thermal energy of high-temperature gas lost by the dust collector and to increase the heat recovery rate as much as possible.

Note that if the downward velocity of the dust-containing gas when introduced into the cylinder is lower than 5 m/s, the erosion effect and dust aggregation effect described later will not be sufficient, and the
If it is larger than m/s, the erosion of the tube itself cannot be ignored.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 1, the cylinder 1 is formed by vertically connecting a plurality of unit cylinders, five in this embodiment. A plurality of cylinders 1 are housed within the can body 2. The can body 2 is formed of a steel plate lined with a heat insulating material 3, and has a tower shape as a whole. A dust-containing gas inlet 2a is formed at the upper end of the can body 2, a clean gas outlet 2b is formed at the side wall, and a dust hopper 2c is formed at the lower end. Also,
An upper tube plate 4c is provided at the upper end of the tube 1,
A lower tube plate 5 is provided at the lower end of the tube 1.
Middle tube plates 4d (four in this embodiment) are provided at locations corresponding to the connecting portions. These upper tube sheet 4c, middle tube sheet 4d, and lower tube sheet 5 are all water-cooled tube sheets, and are enclosed in the can body 1. and an upper tube sheet 4c and a middle tube sheet 4d.
support the upper end portions and connecting portions of the plurality of tubes 1, respectively, and the lower tube plate 5 supports the lower end portions of the plurality of tubes 1.

Referring also to FIG. 2, each tube plate 4c, 4
d, 5 have a water jacket inside, cooling water inlets 4a, 5a are formed at one location on the outer periphery, and cooling water outlets 4b, 5b are formed at locations on the outer periphery opposite thereto. Further, each of the tube sheets 4c, 4d, and 5 is formed of a steel plate, and a heat insulating material 6 is applied to the upper and lower surfaces. A clean gas chamber 2d is formed within the can body 2 by these tube plates 4c, 4d, and 5.

As shown in FIG. 3, the middle tube plate 4d supports the connecting portion of the tube 1 via the seal 7.
As shown in FIG. 4, the upper tube plate 4c supports the upper end of the cylinder 1 via a seal 7. Also, the fifth
As shown in the figure, the lower tube plate 5 supports the outer periphery of the cylinder 1 via the seal 7, and also supports the lower end of the cylinder 1 through the ribs 5c. The seal 7 may be any material that substantially seals the flow of dust in the dust-containing gas, and ceramic fiber rope, carbon fiber gland packing, metal fiber rope such as stainless steel, etc. are used.

The cylinder 1 is made of a ceramic material, preferably mullite, cordierite, silicon carbide, silicon nitride, etc., which have good thermal shock resistance. The average pore diameter of the porous body of cylinder 1 is selected appropriately depending on the average particle size and particle size distribution of the dust in the dust-containing gas, and the dust content rate of the target clean gas. The average pore diameter of the porous body is preferably 0.2 to 6 times, particularly 0.5 to 3 times, in order to obtain a high dust collection rate and a high processing speed.

The length of the unit cylinder that makes up the cylinder 1 is determined by the strength of the cylinder, the relationship between the natural frequency of the cylinder and the excitation frequency such as air column vibration, the ease of handling when installing and opening the cylinder, and the tube plate. 4c, 4d, 5, the cost, pore size, porosity, etc. must be taken into consideration when deciding, for example, β, which has high thermal shock resistance.
- When cordierite ceramics are used for the tube, the appropriate length is 0.8 m to 2 m. In addition, the unit cylinder may be formed by joining shorter porous cylinders in the longitudinal direction using a heat-resistant inorganic adhesive or the like, with or without a joint, as long as the above conditions are not impaired. .

Next, to explain the operation of this dust collector, in FIG.
It flows into the can body 2 from a, is dispersed by the upper tube plate 4c, and is introduced into each tube 1 at a flow rate of 5 to 50 m/s. In this case, unlike the bag filter, the cylinder 1 in the present invention is made of a highly hard and chemically stable ceramic material, so even if the dust-containing gas is introduced into the cylinder 1 at such a high speed, erosion will hardly occur. do not have. On the other hand, whatever the material,
For bag filters using cloth-like or felt-like cylinders, the flow velocity inside the cylinder is 2 m/s to prevent erosion.
Limited to: Then, the dust-containing gas gradually passes through the cylinder wall while descending inside the cylinder 1, becomes clean gas H, passes through the clean gas chamber 2d, and passes through each clean gas outlet 2b.
is discharged from.

The axial flow velocity of the dust-containing gas decreases almost linearly downward from the inlet of the cylinder 1, and becomes almost zero at the bottom. Since the dust-containing gas flows into the cylinder 1 at high speed, the coarse dust particles have large kinetic energy, and even if the axial flow velocity of the dust-containing gas decreases, they continue to move downward and collide with each other. This increases the degree of agglomeration and causes the particles to settle and separate in the hopper 2c while also attaching fine dust. The fine dust rides the radial gas flow under the influence of gas viscosity and fills the pores near the surface layer of the inner wall of cylinder 1 while forming bridges of dust particles (dust-containing gas is microfiltered by these bridges). ), due to the erosion effect caused by coarse dust descending at high speed,
It does not protrude and accumulate on the inner surface. Furthermore, this erosion effect can be enhanced by flowing the dust-containing gas while swirling. Therefore, backwashing with clean gas is not necessary at all, or even if it is necessary, only the lower clean gas chamber 2d is often sufficient.

In this way, by swirling and introducing the dust-containing gas into the plurality of long cylinders 1 at a relatively high speed, dust can be collected quickly on an industrial scale. Further, since the upper and lower ends and connecting portions of each tube 1 are supported by a plurality of tube plates 4c, 4d, and 5 via the seal 7, the tube 1 has sufficient strength, and the seal 7 and tube Vibration is damped by the plates 4c, 4d, and 5, and the plate also has vibration resistance.

During the treatment of dust-containing gas, the cooling water inlet 4a,
Since the cooling water flows from 5a through the tube sheets 4c, 4d, 5 to the cooling water outlets 4b, 5b, the tube sheet 4
Thermal damage of c, 4d, and 5 is prevented. Further, the can body 2 is lined with a heat insulating material 3, and the tube sheets 4c, 4
Since the upper and lower surfaces of tubes d and 5 are covered with heat insulating material 6, the clean gas flowing out from the tube 1 into the clean gas chamber 2d can be taken out with as little heat loss as possible, and the subsequent recovery of thermal energy is facilitated. It can be done efficiently. In addition, these insulation materials 3,
6 also prevents thermal damage to the can body 2 and water-cooled tube sheets 4 and 5.

In the present invention, the dust-containing gas is introduced into the cylinder 1, and the clean gas is taken out from the outer periphery of the cylinder 1. In this case, the downward speed at the time of introduction is set to 5.
~50 m/s, and for example, a swirling blade is provided at the inlet of each cylinder 1 so that the dust-containing gas flows through the cylinder 1 while swirling, giving a centrifugal effect to the dust of the dust-containing gas. Further, depending on conditions such as gas viscosity, dust specific gravity, particle size distribution, flow rate, etc., a swirling vane may be provided in the middle of the cylinder 1.

Furthermore, in order to increase the erosion effect on the dust particles adhering to the inner wall of the cylinder 1, a small amount of gas is extracted from the upper part of the dust hopper 2c, more precisely from the lower part of the cylinder 1 and above the accumulated dust layer. A slight axial velocity may be given to the dust-containing gas also in the lower part of the cylinder 1. That is, an extraction port may be opened in a part of the dust hopper 2c where dust does not accumulate and where dust does not fall, and an extraction pipe may be connected to the outside thereof. There are two methods for collecting dust from the extracted dust-containing gas.

One is to return the entire amount of extracted dust-containing gas to the dust-containing gas inlet 2a using a fan or blower.
When the extracted dust-containing gas has a large amount of dust or a high temperature, a fan or blower whose impeller is partially or entirely made of ceramics is preferably used.

The other method is to remove dust from the extracted dust-containing gas using a conventionally known dust collector. Bag filters are preferable for this dust collector because of their small size and high dust collection efficiency, but electric dust collectors, Multichron, etc. Alternatively, a scrubber etc. may be used. If the extracted dust-containing gas is at a high temperature, it may be cooled and then guided to the above-mentioned conventional dust collector, or directly to a scrubber.

Further, in the above embodiment, the tube sheets 4c, 4d, and 5 were water-cooled, but the temperature of the dust-containing gas was
Water cooling is not necessary as long as the temperature is within the allowable limit (generally 450° C. or less) for the steel material constituting d and 5. In that case, it is preferable to put the heat insulating material 3 on the outside of the can body 2 from the viewpoint of the heat insulating effect.

Furthermore, it is also possible to provide a through hole that communicates with the upper and lower parts of the middle tube plate 4d to enable communication between the upper and lower clean gas chambers 2d, and to unify the clean gas outlet 2b.

[Effects of the Invention] As explained above, according to the present invention, the upper and lower ends of the cylinder are supported by tube sheets, respectively, while being dust-tightly sealed, and a relatively high downward speed of 5 to 50 m/s is achieved. Since the dust-containing gas is introduced into the cylinder while being swirled, the erosion effect and dust aggregation effect are fully exhibited during the dust collection process from the dust-containing gas, and the erosion of the cylinder itself is also prevented. As a result, the amount of air processed per tube can be increased, and the installation space can be reduced.

Furthermore, unit cylinders are connected to form one cylinder,
By sealing the connecting portion dust-tight and supporting it with a tube plate, sufficient strength and vibration resistance can be provided even if the tube is made of a material such as ceramics.

Therefore, the present invention makes it possible to efficiently process high-temperature dust-containing gas on an industrial scale without cooling it, and to effectively recover thermal energy, so that its energy-saving effect will be felt throughout all industries. I'm sure it will be huge.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a plan view of the same embodiment, FIG. 3 is an enlarged sectional view of the R portion in FIG. 1, and FIG. An enlarged sectional view of the T part, FIG. 5 is the S in FIG. 1.
It is an enlarged sectional view of a part. 1... cylinder, 2... can body, 2a... dust-containing gas inlet, 2b... clean gas outlet, 2c... dust hopper, 4c... upper tube sheet, 4d... middle tube sheet, 5...
...Lower tube plate, 7...Seal.

Claims (1)

[Claims] 1. The upper and lower ends of a cylinder made of ceramic material are supported using an upper tube sheet and a lower tube sheet, respectively, while substantially sealing the flow of dust, and the dust-containing gas inlet and The cylinder is housed in a can having a clean gas outlet, and the dust-containing gas from the dust-containing gas inlet is introduced into the cylinder at a downward speed of 5 to 50 m/s, and the dust-containing gas is inside the cylinder. A method for processing high-temperature dust-containing gas, which is characterized in that the gas is made to flow while swirling. 2. The processing method according to claim 1 or 2, wherein the dust-containing gas has an axial velocity also at the lower part of the cylinder.