JPS6249931A - Refining device for waste gas - Google Patents

Abstract

PURPOSE:To remove fine liquid drops by providing a liquid drop generator to the lower part of a wetted wall column, suspending a cathode bar to the central part of the column and impressing a voltage to said bar and column in such a manner that the column wall acts as an anode thereby forming an electrostatic liquid drop separator. CONSTITUTION:Gas to be treated enters the column 1 from a gas duct 3a and is mixed with the liquid ejected from a water pipe 3b of a spray generator 3 provided in the lower part of the column in an injection part 3c. The mixture ascends in the form of the gas contg. the fine liquid drops in the column 1. THe voltage is impressed between the cathode bar 4 and the wetted wall 2 acting as the anode. The fine liquid drops charged negative is attracted in the state of contg. an acidic gas, dust, etc., to the wetted wall anode. An absorbent liquid is injected from an annular spray generator 5 provided in the upper part of the column to drop the liquid from the upper part of the wetted column, by which the gas absorption is further executed.

Description

[Detailed Description of the Invention] Industrial Application Field: The present invention processes exhaust gas as it is or in a near-insulated state using a wet gas absorption device to remove acid gas and remove dust. By bringing the gas to be treated into a supersaturated state (a state in which the gas saturated with water vapor contains fine droplets of water), particle growth is promoted using the fine droplets containing acid gas and dust as nuclei, and electrostatic droplets are generated. The present invention relates to a device for cleaning exhaust gas by removing fine droplets using a separator. It goes without saying that dust removal is carried out at the same time.0 Conventional technology: When sulfur-containing fuel (heavy oil obtained from Middle Eastern crude oil, residual oil produced at fine oil refineries, etc.) is burned, it contains so-called SO+C and dust such as soot. Exhaust gas is generated. When this exhaust gas is treated with a known wet desulfurization device (one that has a packed bed, a bubble bell, a net shelf layer, etc., and has gas and liquid in countercurrent contact),
SO! In the case of gases such as Keg, NH, etc., which have a high reaction rate with water and whose absorption rate is substantially dominated by diffusion to the interface, they can be quickly removed. However, when the SOS gas dissolves into microdroplets, the droplets containing 803ft formed by first dissolving into microdroplets have a slow particle growth rate, and therefore, when the escaped gas is released into the air, smoke growth occurs. This also causes acid rain.

However, it is well known that no countermeasures have been established and troubles continue to occur.

Problems to be Solved: The main purpose of the present invention is to remove the permeate Mi containing S08 from the exhaust gas.

The present inventor has focused on a method for removing SO, and at the same time
As a result of conducting various research on methods of removing S03
Containing water droplets absorb water vapor in the gas, and small water droplets floating in the gas bond with each other and become larger, but at the same time the concentration of sulfuric acid that makes up the droplets decreases and the temperature rises due to the heat of reaction. It was learned that as a result, the water vapor pressure of the microdroplets becomes large VC, causing water vapor movement to occur, which delays the particle growth rate and causes difficulty in removal.

I also learned that if the gas to be treated is cooled, the droplets will also be cooled, and if the gas to be treated is supersaturated, the size of the droplets will quickly increase. It goes without saying that under these conditions, water droplets grow with the dust as the core, making it easier to remove them.

Means for Solving the Problem: In the present invention, in order to supersaturate the gas to be treated, a liquid (preferably at a low temperature by being quenched with water or an aqueous solution) is directly included in the gas. The impurity-containing droplets (the impurities are at least one of a gas mainly composed of SO8 and a solid represented by dust) that have grown by trapping the fine droplets are later removed by an electrostatic droplet separator.

In the present invention, the droplet generator for creating a supersaturated state is a spray generator (a type of C filtration system that spouts a liquid into a gas) or an entrainment generator (a type of droplet generator that blows gas into a liquid). A boiling state (meaning a type that causes droplet entrainment) is used.

Therefore, a droplet generator for creating a supersaturated state and a silent four-gas droplet remover are placed in a wet wall tower type gas absorption tower, with the former placed in the lower part.
The latter is disposed at the top, and droplets captured by the electrostatic droplet remover are caused to fall along the wetting wall 1 to form a wet nutrient solution.

Additionally, if necessary, an annular spray generator is installed at the top of the wet wall tower to spray onto the deposited metal.

In order to use multiple wetted wall towers τ in parallel, new surface shapes such as a square well girder structure or a hexagonal honeycomb structure are used so that both sides of the partition walls function as wetted walls.

It goes without saying that gases with a high absorption rate are completely absorbed under the conditions in which S08 is absorbed. Regardless of whether it is absorbed or removed,
S03 dust removal may be performed.

Effect: A supersaturated state is a two-phase dispersion system in which a liquid is dispersed in a gas, and an irreversible change occurs spontaneously in the direction in which the surface energy decreases, that is, in the direction in which the dispersion liquid condenses. When the liquid particles are small, even at the same supersaturation degree (unit: d width of liquid weight/steam weight), there are many liquid particles and the total surface area is large, which is favorable for particle growth, but on the other hand, the size of the colloid As the value approaches , Brownian motion becomes more intense and it becomes difficult to increase t4 due to particle collisions.

When ejecting liquid from the nozzle, the most part is 50
The particles are larger than μm and do not contain so-called colloid-sized particles.

Now, the adiabatic saturation temperature of the combustion exhaust gas is 50°C or higher at berth, and when wet desulfurization is performed, fine water droplets containing SO8 etc. are suspended.

This exhaust gas is cooled by the low-temperature spray-like liquid spray ejected from the nozzle, becomes supersaturated, and forms exposed ζ fine droplets, but these fine droplets contain coexisting SOa or fine liquid droplets. Sprayed water droplets combine and gradually become large droplets, but at this time, since the sprayed water droplets have a relatively large particle size (50-2000 μm), they move at a slower speed than fine droplets in the gas. Collisions with the drop and captures it, thus S
Contributes to the absorption of gases such as 02. Furthermore, as is well known,
The vapor pressure of a small droplet is higher than that of a large droplet due to surface tension (for example, Moore: Physie
al Chemistry5 th Ed, p, 48
1tLOngman), so, 2-containing droplets have a low vapor pressure, so they are always in a state of being steamed and collected from the outside.Generally, droplets that do not contain 808 have the highest water vapor pressure, followed by droplets that do not contain 808fc. The large tube is followed by the water droplet containing 803 ('), and the droplet containing 5Ost becomes larger through the phase metal. Furthermore, if the gas to be treated is unsaturated, the droplets contained therein will evaporate and approach the wet bulb temperature, which will reduce the particle size and terminal velocity of the droplets and reduce the temperature of the gas to be treated. It becomes easier to entrain due to rising current (in the air, 2 m, 1
The terminal velocity of a droplet of 00 μm and 120 μm is 6
．． 8 m/sec, 0.33 m/see, 1.2
1c4/see o).

The electrostatic droplet separator (to) is located at the top of the spray generator, and a cathode rod (4) is suspended from the column core, and a voltage is applied so that the column wall becomes an anode, making it negatively charged. It has a normal structure in which droplets move to the tower wall and discharge there,
One feature of the present invention is that droplets discharged on the tower wall overflow and fall onto the wall, forming a wet wall. Of course, wet walls
Contributes to gas absorption as a wet wall tower.

In the present invention, the main reason for spraying the liquid downward at the top of the tower as necessary is to secure a wet nutrient solution at the top of the tower.The other reason is to prevent gas absorption and droplet bonding by the spray itself. furthermore, providing electrostatically separated microdroplets at a sufficient rate,
For example, it is desirable to eject the liquid downward at a rate of IQm/sec or more so that the fine droplets do not end up in the rising process target.

Example: In Figure VC, a spray generator (
3) is installed, and the gas to be treated is placed in a gas duct)(:(
a) The liquid enters from the water pipe (3b) and mixes with the liquid ejected from the water pipe (3b) at the ejection part (3C), forming a gas containing fine droplets, as in the case of well-known water jet scrubbers, etc. (1) Rise within. Figure 2 shows an example of the structure of a sprue generator.
A portion of the gas is inhaled and contributes to the formation of liquid droplets.

Fig. 3 also shows two other examples of spray generator nozzles, in which (&) in the figure impinges on the inverted cone (b) the liquid rising through the lower conduit (2); (2) is a type in which minute droplets are dispersed in the gas rising outside the pipe (6), and the liquid rising through the liquid conduit (6) is ejected from a small hole a3, and the gas rising outside g. This is a type of liquid in which fine droplets are dispersed. An example of an entrainment generator that generates microdroplets in the form of p1 flying bed entrainment is shown at the bottom of FIG. In the figure, the gas to be treated is introduced from the conduit into the multi-tube wet wall tower (1),
It is discharged from conduit 4. (2ga), (2ob), (2
Qc) 6 is an L# wetted wall tower with a square cross section and a hexagonal cross section, and is shared with the adjacent unit wetted wall as a t-le wall such as )4 walls (2a) and (20). The rice is fed from 4.♂(a) onto the perforated plate. Perforated plate CAv means net, turbo grid, perforated plate in a narrow sense, etc. When gas rises up the perforated plate, it forms many bubbles, which speeds up the gas velocity so as to cause the liquid to splash on the plate. (An overflow weir may be provided, but it is not necessary.) In this way, when the entrainment/mention generator CID wi is used in a multi-tube wet wall tower, it is economical because it is not necessary to install a spray generator in each unit wall tower.

It is desirable that the gas rising rate in the cinnabar column be 5 to Q m/see for the relationship with the subsequent electrostatic droplet separator (c) and for effective operation of the device; under this condition,
IfLm with a representative diameter of 211II or less is end laned to 4 gases there.

In FIGS. 1 and 4, a cathode rod (4) and a known high voltage generator (not shown) (motor generator,
A voltage of tens of thousands of volts is applied between the wetted wall (anode) by M) of the mercury flow device, and as a result, the negatively charged minute droplets are in a state containing acid gas, dust, etc. It is attracted to the n-wall/- pole, discharges, and is removed from the gas to be processed. Needless to say, the removed droplet force flows down the wetted wall as a nutrient solution and participates in gas absorption by the TI4 wall tower.

The present invention has the above configuration, a water jet scrubber,
Both of them show excellent performance as an electrostatic droplet separator and a memorized electric rating, but in addition, by spraying the liquid downward from the top of the tower, a wet electrolytic liquid fp is prepared at the top of the tower.
The performance as a ni tower can be increased, and the performance as a countercurrent water jet scrubber can also be improved.

An annular spray generator (5) installed at the top of the wetted electrical grid shown in Figure 1 or 4, the structure of which is illustrated in Figure 5, sprays the absorbent liquid in the direction F, spraying the wetting liquid from the top of the wetted wall. By dropping the nutrient solution and spraying fine droplets in the F direction, the gas purification effect is increased. At this time, entrainment of droplets can be almost completely eliminated by making the ejection speed greater than the rising speed of the gas to be treated. In Figure 5: Catfish (5a
) is an annular liquid pipe, to which liquid is supplied from a liquid reservoir (not shown), and liquid is ejected from a spray nozzle (5b).

Figure 6 shows that when configuring the multi-pipe wetted electric grid cIQ (Figure 4) with unit wetted electric grids, the unit wetted electric grids are arranged in a parallel cross-sectional shape and the adjacent tower walls are shared, thereby saving space and equipment material. In another example, by forming a wetted electric grid with a honeycomb-shaped hexagonal cross section, both sides of the partition wall can be used as a wetted moss wall, and the same effect can be obtained. It goes without saying that it can be done. (support) is the liquid outlet.

Effects of the invention: When the present invention removes the exhaust gas containing impurities using a wet electric potential, the present invention allows minute droplets of an absorption liquid to be present in the gas to be treated to absorb the acidic gas, and The absorption liquid at low temperature becomes supersaturated by fcI history, and the particles are made into large particles by the agglomeration and coarsening action of the microparticles, and separated using an electrostatic droplet separator. Since the filtered liquid is made to flow down the column wall as a wet nutrient solution and is used as a wet nutrient solution using the same tower, two or three operations can be carried out in a single device. However, it greatly contributes to streamlining and economicalization of processes.

Moreover, as is obvious; the removal efficiency is increased, and the exhaust gas to be treated can be purified to a high degree.

By arranging such wetted electrical grids in the form of square grids or hexagonal honeycombs, adjacent towers can use both sides of the bulkhead as a barrier and a wetting grid, respectively, further increasing the economic effect. In this multi-tube wet electric grid type, only one entrainment generator that utilizes the droplet entrainment phenomenon is installed as a droplet generator installed at the bottom of the tower. By allocating it to each unit wet voltage rating, the JA installation can be further simplified and made more economical.

In addition, a downward spray generator is placed above the unit wetted electric grid to increase the wetted nutrient solution and increase the amount of spray, thereby further increasing the purification effect.

[Brief explanation of drawings]

FIG. 1 is a branch plan view showing the configuration of an embodiment of the present invention. FIGS. 2, 3(a) and 3(b) are side views showing four structures of the spray generator. In FIG. 4, a single entrainment generator is placed at the bottom of a multi-pipe wetted electric grid, and an annular spray generator is provided above each snow. FIG. 3 is a branch plan view of an embodiment of the pond of the present invention. FIG. 5 is a diagram of the upper part of the wet N44 tower with an annular spray generator. Figure 6 shows the horizontal 1f of a Tahiko wet electric grid with a square well-shaped cross section.
It is an r-plane view. (1)..., J electric rating, (2), (2a), (2b)
, (2e)・g Wall, (3)...Spray generator, (4)...Cathode formation, (5)...Annular spray generator (6)...Inverted cone, (To )...Small hole...Multi-tube wetting electric rating, (2)...Entrainment generator, Rock...Exhaust gas inlet, (E)...Exhaust gas outlet, ■...Static electricity Droplet separator, 4...Liquid inlet, (E)...Perforated plate (to)...
Liquid outlet Fig. 1 (a) (b) Fig. 3 Fig. 5 Fig. 6

Claims (1)

[Scope of Claims] 1. Droplets that produce fine droplets at the bottom of a wetted wall tower in which a wetted wall liquid falls on the tower wall and the gas to be treated rises in the tower in a countercurrent to the wetted wall liquid. A generator is installed, a cathode rod is suspended in the core of the column, and a voltage is applied between the two electrodes so that the column wall acts as an anode, forming an electrostatic droplet separator and causing the inside of the column to flow. An exhaust gas purification device characterized in that after a gas to be treated moving from below to above contains minute droplets, the droplets are separated by the electrostatic droplet separator. 2. The exhaust gas purification device according to claim 1, wherein the droplet generator is a spray generator. 3. The exhaust gas purification device according to claim 1, wherein the droplet generator is an entrainment generator. 4. The exhaust gas purification device according to any one of claims 1 to 3, wherein an annular spray generator for spraying liquid downward is provided at the top of the wet wall column. 5. A waste gas exhaust system according to any one of claims 1 to 4, in which a plurality of wet wall towers with a square cross section share a tower wall in a cross-section shape, and both surfaces of the walls each act as a wet wall. Purification equipment. 6. The exhaust gas according to any one of claims 1 to 4, in which a plurality of wetted wall towers having a hexagonal cross section share a tower wall in a honeycomb manner, and both surfaces of the walls each act as a wetted wall. purification equipment.