JPH0550324B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for processing dust-containing gas from a dust-containing gas generation source device.

[Prior Art] A dust removal device for dust-containing gas using a permeable porous cylinder as shown in FIG. 4 has been known for some time (see, for example, Japanese Patent Laid-Open No. 58-3620). That is, in FIG. 4, a cylinder 11 made of a plurality of breathable porous bodies
are vertically juxtaposed, closed at the bottom and open at the top. The upper end of the tube 11 has its outer side connected to the tube plate 71.
It is housed in the middle can body 22 while being airtightly supported. A dust-containing gas inlet 31 is provided in the body of the middle can 22, a dust outlet 52 equipped with a dust cutoff valve 51 is provided in the lower can 23, and a clean gas outlet 41 is provided in the upper can 21. ing.

When dust-containing gas from downstream of the dust-containing gas generation source device is supplied from the dust-containing gas inlet 31, the dust-containing gas enters the external space of each cylinder 11, and clean gas flows into the cylinder 11 due to the pressure difference between the inside and outside of the cylinder 11. passes through the cylinder wall of
The gas exits into the cylinder 11 and is taken out of the system through the clean gas outlet 41.

On the other hand, the dust that is blocked from passing by the outer wall of the cylinder 11 accumulates on the outer wall of the cylinder 11 over time, and in some cases, a part of it falls and falls into the lower can body.
3, the accumulated dust forms an overlayer, and precise filtration of the dust-containing gas is performed.

As the layer thickness of the accumulated dust increases, the pressure difference between the inside and outside of the cylinder 11 increases, so it is generally done to reduce ventilation resistance by removing this dust by backwashing at regular intervals, etc. It is.

[Problems to be Solved by the Invention] However, such conventionally used dust-containing gas treatment apparatuses have not been put to practical use on a large, industrial scale. Reasons for this include the following.

First, to treat high-temperature or corrosive dust-containing gases, it is desirable to use ceramic tubes, but long ceramic tubes are not easy to shape or fire, are heavy, and require a complicated hanging structure. Become. Alternatively, short ceramic tubes may be stacked longitudinally and used, but arms or supports for supporting the tubes would have to be provided in the dust-containing gas flow path, and dust would accumulate on these arms. There are also disadvantages such as the accumulation of material that prevents it from falling.
It is difficult to make the cylinder long, so the amount of gas to be processed per unit area is small, and it is not suitable for processing dust-containing gas with a large air volume.

Next, in the case of a dust-containing gas with a high dust concentration, all the dust except for some coarse dust is attracted to the outer wall of the cylinder 11, so the pressure difference between the inside and outside of the cylinder 11 increases at a high rate, making it difficult to backwash. This needs to be done frequently, which increases the cost of powering the backwashing blower, and it is also necessary to provide equipment with extra capacity to take into account the reduction in processing capacity during backwashing.

Furthermore, in the case of the apparatus shown in FIG. 4, the dust extraction valve 51 is closed during normal operation, and dust accumulates on the dust extraction port 52. When a certain amount of dust accumulates, it is necessary to stop the operation of the device and open the dust extraction valve 51 to take out the dust, forcing the operation of the device to be batch-type. Dust may be dispersed into the atmosphere. Further, even when the operation of the apparatus is not stopped, there is a problem that the operation becomes intermittently unsteady when the accumulated dust is taken out, and the dust and dust-containing gas are scattered and released into the atmosphere at that time.

In addition, if the dust-containing gas is high temperature, high pressure, pressure lower than atmospheric pressure, toxic, or flammable, or if the dust is toxic, flammable, flammable, or easily deteriorates by reacting with the atmosphere, etc. This required an extremely complex dust removal mechanism.

The present invention provides a method for treating dust-containing gas that solves the above-mentioned problems of the prior art.

[Means and effects for solving the problems] The present invention directs dust-containing gas from downstream of a dust-containing gas generation source device to the upper part of a space partitioned by a permeable porous partition wall disposed approximately vertically. The clean gas is passed through the partition wall and taken out, and the high dust-containing gas is taken out from the lower part of the space without passing through the partition wall, and the high dust-containing gas is sent to the dust-containing gas generation source. This is a method for treating dust-containing gas, which is characterized by refluxing the dust-containing gas upstream of the device.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

As can be seen from FIGS. 1 and 2, a plurality of hollow cylindrical tubes 1 with open upper and lower ends
0 are arranged approximately vertically side by side, and the upper and lower ends of each cylinder 10 are airtightly supported by tube plates 70 and 75, respectively, and housed in the middle can body 25. Each tube 10 is made of an air-permeable porous sintered body made of cordierite ceramic, for example.

A dust-containing gas inlet 30 is provided at the top of the upper can body 26.
A high dust content gas outlet 50 is provided at the bottom of the lower can body 27 to take out separated dust and high dust content gas, and a clean gas outlet 40 is provided at the body of the middle can body 25. A dust collector 60 is configured.

The dust-containing gas, which is high temperature and high pressure (e.g., approximately 120°C, gauge pressure 1 to 3 atm) and contains a lot of toxic carbon monoxide, is discharged from the top of the blast furnace downstream of the blast furnace 65, which is the dust-containing gas generation source device. The dust-containing gas is supplied to the inlet 30 through the dust-containing gas inlet 30. The dust-containing gas flows into each cylinder 10 at high speed, and due to the pressure difference between the inside and outside of the cylinder 10, it passes through the pipe wall of the clean gas cylinder 10, exits the cylinder 10, and is taken out to the clean gas outlet 40.

On the other hand, the dust that is blocked from passing by the inner wall of the cylinder 10 is accelerated by the viscosity of the downward flow of the dust-containing gas and the high-speed gas flow, and is mainly coarse-grained dust that settles downward at high speed due to inertia. The particles fall due to the scraping effect caused by the collision with the wall surface, and the particles collide with each other and aggregate, and fall due to the inertia and gravity of the particles themselves and enter the lower can body 27. During this time, a part of the dust coagulates and adheres to the vicinity of the inner wall of the cylinder 10 to form a dust overlayer, and most of the dust falls, and the dust-containing gas is continuously collected.

If the high dust content gas outlet 50 is closed, dust will accumulate around the high dust content gas outlet 50.
At the same time, the gas inside the lower can body 27 does not flow, and therefore the gas flow velocity around the lower end of the cylinder 10 also becomes zero, and the scraping effect of dust does not work sufficiently in the cylinder 10 at this part. Therefore, a thick layer of dust adheres to the inner wall of the cylinder 10, reducing the ability to over-process dust-containing gas.

Therefore, in the present invention, the high dust-containing gas outlet 5
0 is opened, and the gas in the lower can body 27 is continuously taken out. This gas is dust-containing gas inlet 3
This is a high dust-containing gas with a relatively high dust concentration compared to the dust-containing gas fed in from zero. It goes without saying that this highly dust-containing gas contains the dust that has fallen inside the cylinder 10 mentioned above.

Next, the highly dusty gas taken out from the highly dusty gas outlet 50 passes through the pipe, passes through the blower 66, and is refluxed to the raw material input port of the blast furnace 65. On the other hand, most of the introduced dust-containing gas becomes clean gas with almost no drop in temperature or pressure and is taken out from the clean gas outlet 40, guided through piping to the power recovery turbine 67, where the power is While being collected, the pressure is reduced to approximately atmospheric pressure, and the gas reaches a gas holder (not shown).

FIG. 3 shows an example in which the present invention is applied to a regeneration tower of a heavy oil catalytic cracker. The regeneration tower generates exhaust gas (eg, about 650° C., gauge pressure of about 2 atmospheres) containing a scattered catalyst such as a silica-alumina catalyst. Conventionally, this regeneration tower exhaust gas passes through the first stage cyclone and second stage cyclone inside the regeneration tower, and then the third stage cyclone installed outside the regeneration tower, where most of the dust of about 10 microns or more is removed, and then the power recovery turbine It was common for the gas to be guided into the air, recover the power, reduce the pressure to almost atmospheric pressure, and then pass through an electrostatic precipitator.

When the method of the present invention is applied, the first stage cyclone and the second stage cyclone are eliminated in the regeneration tower 68, and the regeneration tower exhaust gas is directly supplied to the dust collector 60 (the first stage cyclone).
Since the device is similar to that shown in FIG. 2, it is omitted in FIG. 3). The resulting clean gas is guided to a power recovery turbine 67 for power recovery, and is then discharged from a chimney (not shown) without the need for additional dust collection using an electrostatic precipitator or the like. On the other hand, the highly dust-containing gas from the bottom of the dust collector 60 passes through the pipe, passes through the blower 66, and is refluxed into the regeneration tower fluidized bed located upstream of the regeneration tower exhaust gas outlet of the regeneration tower 68. Note that instead of being directly refluxed to the regeneration column 68, it may be refluxed to a reaction column system (not shown) connected to this via piping, and this is also included in the present invention.

In the above description, an example is shown in which the shape of the air-permeable porous partition wall is a hollow cylinder. Such a shape is relatively easy to manufacture, has high strength, and has the advantage of being able to easily withstand the pressure difference on both sides of the partition wall, but the partition wall may be formed into a hollow rectangular tube shape or a flat plate shape, for example.
In addition, although FIG. 1 shows a cylinder that is integrated from the upper end to the lower end, it may be joined as appropriate in the longitudinal direction. A tube plate may be added to the

Although sintered metal can be used as the material for the partition wall, ceramic is preferable in order to effectively recover clean gas from high-temperature or corrosive dust-containing gas, or to effectively recover energy. However, it is preferable to use ceramics such as cordierite, mullite, fused silica, alumina, siyamoto, aluminum titanate, silicon carbide, and silicon nitride in terms of heat resistance, corrosion resistance, low thermal expansion, and thermal shock resistance.

It is generally preferable that the downward flow velocity of the dust-containing gas at the upper end of the space partitioned by the partition wall be high in terms of the scraping effect of coarse dust, and is 2 m/s.
In particular, a speed of 5 m/s or more is desired. However, if the speed is too high, the partition wall itself will be scraped and power loss will also increase, so a speed of 100 m/s or less, particularly 50 m/s or less is desired.

If the downward flow velocity of the dust-containing gas at the lower end of the space partitioned by the partition wall is too low, the scraping effect will not be sufficient, so it is preferably 0.3
m/s or more.

In the present invention, high dust-containing gas, dust-containing gas, and clean gas are relative concepts with respect to dust concentration.
This refers to those in which the dust concentration decreases in the order listed above, and does not specify an absolute specific dust concentration.

Further, the dust-containing gas generation source device is not limited to a blast furnace or a heavy oil catalytic cracker regeneration tower. Furthermore, the term "downstream of the dust-containing gas generation source device" refers to the part from which the dust-containing gas is discharged, whereas the term "upstream of the apparatus" refers to the part located upstream of the above-mentioned downstream part of the apparatus, and is preferably a part located upstream from the downstream part of the apparatus. This is the part where raw materials in physical or fluid form are supplied to the device.

[Effects] In the treatment method of the present invention, the partition support means such as the tube plate 75 can be easily provided on the clean gas flow path side instead of on the dust-containing gas flow path side, so that dust does not accumulate on the support means. . In addition, since the scraping effect of dust and high-speed gas flows effectively over the entire area from the top to the bottom of the partition wall, it is almost impossible for a thick dust layer to form on the partition wall surface. The frequency of backwashing can be significantly reduced compared to

Furthermore, when the blast furnace shown in Figure 1 is used as a dust-containing gas generation source, the conventional batch treatment method is dangerous because dangerous high-temperature, high-pressure carbon monoxide-rich gas leaks out when dust is removed. However, according to the present invention, most of the dust can be treated as a highly dust-containing gas that is easy to transport, rather than as dust that is difficult to handle. Furthermore, since this gas is returned to the blast furnace without being released outside the system, there is no risk of leakage of high temperature, high pressure carbon monoxide-rich gas.

In addition, when the heavy oil catalytic cracking equipment shown in Figure 3 is used as a dust-containing gas generation source, in the conventional batch treatment method, a considerable amount of the scattered catalyst is recovered as dust, but it is However, according to the present invention, such catalyst dust can be easily reused.However, according to the present invention, such catalyst dust can be easily reused.

As described above, according to the present invention, if the gas or dust constituting the dust-containing gas is dangerous to the human body, has a high chemical effect (for example, flammability or ignition), or has a high physical effect (for example, high temperature or high pressure), Even if it is, it can be treated without requiring a special dust removal mechanism, and useful dust can be actively reused.

Furthermore, by using ceramic bulkheads, the system can be operated at high temperatures and pressures, making it possible to eliminate the need for a composite dust collection system consisting of a bench scrubber, cyclone, electrostatic precipitator, etc., and to effectively recover power and other energy.

Furthermore, in the conventional batch processing method, dust bridging often occurs during dust extraction, making operations unstable, dust gets stuck in the dust removal valve, and the hopper section of the lower can body is closed to prevent bridging. There were problems such as the need to make a large angle with the horizontal. However, according to the present invention, since dust and gas are taken out at the same time, such bridging and jamming hardly occur, and the angle at the hopper part can also be made small, so that the height of the lower can body can be kept small. You can also do it.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention together with a vertical cross-sectional view of an example of a dust collector used in the present invention, and FIG. 2 is a cross-sectional view taken along the - line in FIG.
FIG. 3 is an explanatory diagram showing another embodiment of the present invention, and FIG.
The figure is a longitudinal sectional view of a conventional dust collector.

Claims (1)

[Claims] 1 Dust-containing gas from downstream of the dust-containing gas generation source device,
The gas is introduced from the upper part of a space divided by a permeable porous partition wall arranged approximately vertically, and the clean gas is taken out by passing through the partition wall, and the highly dust-containing gas is removed without passing through the partition wall. A method for processing dust-containing gas, which comprises taking out the highly dust-containing gas from a lower part of the space and causing the extracted highly dust-containing gas to flow back upstream of the dust-containing gas generation source device.