JPS6028545B2 - Method and device for separating fine particles in gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to gas dust collection, and in particular to a method for separating solid particles suspended in gas by the action of static electricity, and an electrostatic precipitator for carrying out this method. It is.

Electrostatic precipitation methods are based on the transfer of electrically charged particulates to an electrode exhibiting an opposite potential to the particulates.

The electrostatic precipitator includes means for passing a gaseous fluid containing dust into a dust collection chamber, means for charging the dust, and electrodes for attracting the dust. According to conventional technology, a corona discharge is generated in the gas stream to be purified, and the lamps contained in this gas are charged.

For this purpose, while passing the gas between a first electrode formed of a pointed conductor or wire and a second electrode having a relatively flat surface, such as a flat plate or cylindrical shape,
A potential difference of about several tens of kilovolts is applied to both electrodes. Then, a strong electric field is formed near the first electrode, and a so-called electron avalanche occurs in a small area called an active area, generating a large amount of ions and electrons. However, electrons with high mobility tend to leave the active area quickly while collecting positive ions or negative ions in the active area depending on whether the first electrode has a positive potential or a negative potential with respect to the second electrode.
This concentration of ions forms a space charge. Dust passing through a space charge area is charged positively by diffusion or bombardment (electron bombardment) if the space charge is at a positive potential, and negatively if the space charge is at a negative potential. The final charge of each particle of dust is then determined by the size of the particle, the residence time in said area, the amount of ionized particles produced per volume of space to be considered, and the charge of the particle. It depends on the value of charge. If the dust-laden gas is flammable and potentially explosive, such as gluten particles in the air inside a grain silo, it is forbidden to generate a corona discharge, and a small spark can cause unforeseen damage. It may also be the cause.

Furthermore, the efficiency of corona discharge decreases as the temperature of the gas passing through it increases. This is due to the thermal motion of the molecules of the gas fluid, and if one of these molecules collides with a negative ion, it liberates the electrons of this ion and increases the electron current of the discharge, but as a result, the space This lowers the efficiency of generating charges and makes the discharge unstable. For this reason, it is actually impossible to use corona discharge to collect dust from combustible gases discharged from furnaces such as fluidized bed furnaces that burn coal or regeneration furnaces that utilize low heat.

However, until now, it has been considered difficult to combine the above-mentioned furnace directly with a piston engine or gas star pin and to perform efficient dust collection. Similarly, electrostatic precipitator techniques without corona discharge are known, but with fine droplets containing dust or particles to be removed. For example, methods have been used in which compressed air is used to atomize the liquid in an atomizer and spray it against the gas stream to be purified.

The nozzle of this sprayer applies a high electrical potential to the entire device, so the water particles passing through the nozzle become electrically charged and attach to the dust particles, guiding them to the metal parts that are earthed throughout the installation. to purify the gas. The remaining dust particles are then guided by the charged water particles and are deposited at the appropriately energized electrodes. Another known technique of the above-mentioned type involves ejecting water particles from a nozzle placed in front of a ring-shaped electrode to which a high voltage is applied and which is connected to earth, thereby charging the particles to a predetermined potential. It is something.

The dust to be removed in the gas is charged by the above-mentioned jet and becomes a mist and precipitates together with the water particles. In both of these known techniques, the gas to be purified is washed with water, and since the gas or air is not dried, sludge tends to form in the apparatus.

Further, if the temperature of the gas is such that the water particles are vaporized before combining with the dust particles to be removed, no excellent dust collection effect can be expected. However, the present invention relates to a method for efficiently collecting fine solid particles or dust suspended in a gas using static electricity, and eliminates the above-mentioned inconveniences that occur when collecting dust from potentially explosive gases or high-temperature gases. It is something to do.

The method for separating fine particles according to the present invention involves generating corona discharge in one chamber of a precipitator through which the gas to be purified passes, and ions generated in the chamber are transferred to fine particles of ice emitted inside the precipitator. The ice particles are captured by crystals, and the captured ions are released by evaporation of the ice microcrystals inside the dust collector, thereby generating a space charge.

Microcrystals of ice are microcrystals of ice obtained by supersonic expansion of moist air in a corona discharge, and these crystals contact the gas to be purified inside the precipitator and evaporate into this area. Forms a space charge. Thus, an electric charge is generated in the first medium of the precipitator and transferred to the second medium through which the gas to be purified forms a space charge.

The first medium and the second medium are independent from an electrical point of view, and a spark emitted in the first medium does not propagate to the second medium. Furthermore, the inherent characteristics of the first medium that generates ions are
It is not affected by the characteristics of the second medium, which is where these ions are used to electrostatically charge the particles to be separated. Since the value of the space charge in the flow path of the gas to be purified is kept below the value that would cause a corona discharge, the risk of discharges or sparks is eliminated if the gas is explosive. It has been shown that even such a weak space charge value is sufficient to charge fine particles of dust in order to perform electrostatic precipitate collection. According to another feature of the invention, in the first chamber there is a negative current.

This method uses a discharge. This allows for stable transfer of negative ions into the stream of the liquid to be purified and also provides excellent energy efficiency. The method according to the invention when purifying hot gases involves generating a corona discharge in a room at a sufficiently low temperature to obtain a space charge of good efficiency;
From this chamber, ions are transferred into the hot gas to be purified.

Preferably, positive ions generated by positive corona discharge are emitted. Therefore, the existence of electrons caused by collision between negative ions and gas molecules excited by thermal motion can be prevented. It is likewise possible to adjust the space charge in order to limit the probability that electrons will become ionized in the hot gas to be purified.

This adjustment is made by controlling the potential of the central electrode at which the corona discharge occurs in the first chamber, changing the current carried by the particles to the second chamber. The present invention also includes a chamber through which a gas flow containing floating particles passes, an ion generator using corona discharge to charge the particles, and means for electrostatically collecting the charged particles in the gas flow path. The ion generator has means for defining a chamber of the precipitator and communicates with this chamber by an orifice, and further includes a means for generating a corona discharge in the gas flow directed toward the orifice in the chamber. and means for forming microcrystals of ice in the area of said corona discharge suitable for trapping ions before being emitted from said orifice to said precipitator. It also relates to

Hereinafter, details of the present invention will be explained with reference to the drawings in which embodiments are shown.

This device is a parallelepiped dust collector 10 defined by two parallel vertical plates 11 and 12, a bottom plate 13, and a top plate 15 (not shown in Fig. 1). reference).

The dust collector 10 has an inlet 14 for sucking in air to be purified, and an outlet 16 for removing solid particulate dust contained in the air and then discharging it. The inlet 14 leads to a charging zone 17 through which the air to be purified passes through a plurality of charged plates 20 parallel to the two vertical plates 11, 12 and alternately charged with positive and negative charges. The electrostatic dust collection area 19 is reached. In the charging area 17 there are a plurality of injectors 21 arranged along vertical rows 23, 24, each passing through the vertical plates 11 and 12. At the tips of these injectors are injection nozzles 25 (see Figures 2A and 2B).
The main body 26 is connected to the vertical plates 11, 12, and the rear end 28 is connected to a common conduit 29 supplying moist compressed air and a cable 42 supplying high voltage (see Figure 2A). ). In Figure 2A, the engine 21 is in each vertical column 2.
Five 3,241 nozzles are mounted on the vertical plates 11 and 12, and the nozzles 25 are arranged opposite to those in the opposite row.

On the other hand, the injector 21 shown in FIG.
', 24', four pieces each are arranged offset from those in the opposite row. Each injector 21 consists of a cylindrical tube 30 defining a passage 32 (see FIG. 3). A nozzle tip 34 forming a nozzle throat 35 is attached to the tip of the cylindrical tube 30, and a mouthpiece 36 that becomes the injection nozzle 25 is further attached. The rear end 28 of the cylindrical tube 30 is sealed at the rear end and has a stopper hole 39 on the side surface to form the compressed air conduit 29.
The hollow tube 38 connected to the is competed. This hollow tube 38
A power supply cable 42 passes through the rear wall 40 via an insulating member 41 and reaches a needle 45 fixed to the cylindrical tube 301 with a washer 44 . This washer 44 is made of an insulating material and is, for example, star-shaped with three radial legs.
Further, the needle 45 is made of metal, is arranged in alignment with the axis of the cylindrical tube 30, and its tip is adjacent to the nozzle throat 35 of the nozzle tip 34. This nozzle tip 34
is made of conductive material and is connected to a power source 48 by a cable 49.
and the needle 45 is grounded by a cable 51.
This becomes the counter electrode. That is, the needle 45 is connected to the cable 42
This means that it is connected to the opposite pole of the power source 48. However, when the lever device starts operating and the voltage reaches a certain value, a corona discharge occurs between the needle 45 and the nozzle tip 34, and moist air passes through the nozzle throat 35.

If the electrode of the needle 45 is a negative electrode, positive ions are collected and electrons diffuse away from the needle. In a gas fluid undergoing a discharge, electrons rapidly combine with electronegative gas molecules, creating a space charge that makes negative ions more difficult to move than these electrons. It has been found that the electrical energy efficiency of generating a negative space charge is further improved because the gas where the discharge takes place facilitates the formation of negative ions. The movement of negative ions creates a stable space charge around the needle 45, which is the same even in dry air.
In the case of weakly electronegative gases, one must be careful of the instability phenomenon in which electrons that do not combine in the form of negative ions can form ionized filaments across the gas, shorting out the needle and damaging the enchantment. No. Waka needle 4
If electrode No. 5 is a positive electrode, electrons will rapidly gather in this needle, leaving enough ions to form an ionized channel to generate a dense plasma.

This channel advances while pushing the active area, which is an electron avalanche, from the electrode of the needle toward the opposite electrode of the nozzle tip. When this ionized channel reaches the opposing electrode, a short circuit occurs between these two electrodes. Limiting the advancement of the active area by limiting the potential difference applied between the electrodes such that the discharge is maintained without causing dangerous short circuits and surrounding the active area with a space charge formed by positive ions. becomes possible. The air flowing into the three cylindrical tubes has an average humidity of, for example, 50% under normal temperature and pressure conditions. That is, the air that this device purifies has a humidity of 10
% or more is optimal; if it is less than this, the air is compressed to the pressure necessary to obtain supersonic expansion and then humidified by a greening device before flowing into the cylindrical tube 30. The humid air that has passed through the nozzle throat 35 of the nozzle tip 34 suddenly expands and forms ice particles with a diameter of several hundred microns, and the air passes through the nozzle throat 35 of the nozzle tip 34 and forms ice particles with a diameter of several hundred microns.
This occurs due to the potential difference between the two. Captures ions caused by discharge. The charged particles are ejected from the injection nozzle 25 and reach the charged area 17 of the dust collector 10. These fine particles are then transferred to metal plates 11, 12,
It diffuses into said area 17 by the characteristic space charge effect until it is collected by 13,15. The value of the space charge generated as described above is ko.

The discharge can be controlled by varying the parameters of the discharge, in particular the potential difference between the electrodes, the velocity and pressure of the air, the flow of the nozzle tip causing the expansion of the compressed air, etc. Although the value of this space charge is small compared to the value of the corona discharge generated inside the injector 21, the dust carried in the gas stream is charged with this charge so that it is later removed in the electrostatic collection area 19. It has sufficient ionization density to cause charging in area 17. The current generated by the charged particles in the charged areas 1 and 7 is relatively weak compared to the current injected from the injector 21. That is, most of this current flows through the metal plates 11, 12, in the form of ionic current.
13 and 15 and is grounded in parallel with the nozzle tip 34, it serves a role similar to the auxiliary electrode in a conventional corona discharge type precipitator. The gaseous fluid containing dust enters the precipitator 10 from the inlet 14 in the direction of the arrow 52, and as it passes through the charging zone 17, the dust particles are diffused and charged by space charges, and then pass through the electrostatic precipitator zone. After being attached to the two charged plates 19, the purified air is sent out in the direction of the arrow 53.

In this example, if the conduit 29 supplies the injector 21 with moist air at a flow rate of 20 per hour (measured under normal pressure and temperature conditions) with a pressurizer of 6 bar, the diameter Supersonic expansion of approximately Mach 1.5 occurs at the nozzle throat 35 of the nozzle tip 34 on the 2.3 side, and a negative potential of 12 kiloports is applied to the needle 45 with respect to the nozzle tip 34. is 5
A current of 0 microamperes is generated.

This dust collector 101 has a height of approximately 100 mm and a width of 40 mm.

The charging area is 20 arcs and the injector is placed opposite this area, the distance between its nozzles being 30 arcs. A pair of opposed injectors pass a total current of 100 microamps, creating a positive or negative ionic space charge of 1 and 3 per force in the charged area 17, taking into account the mobility of the ions. Air, previously mechanically purified by a filter or the like, enters through the inlet 14 at a speed of 2 meters per second and contains dust particles having an average diameter of 3 microns.

Each particle then passes through the charging zone in 0.1 seconds and becomes electrically charged. Therefore, the air flow containing the charged particles flows into the dust collection area 19, and the standards for this area are 100 meters high, 100 meters long, and the distance between the charged plates is 2.60 meters. The plates are connected alternately to a positive and negative potential of 10 kilovolts. The velocity of the gas stream carrying the charged dust particles is 2.8 per second in the area, passing through this area at 0.39 dust to deposit almost all of the dust. The embodiment shown in FIG. 4 has plates 111, 112 which correspond to the metal plates 11, 12, 13 in the embodiment shown in FIG.
, 113, with a first filter layer 115 disposed between the inlet 114 and the outlet 116 in this embodiment.

The charging area 117 has a plurality of injectors 121 arranged in vertical rows 123, 124, each penetrating the vertical plates 111 and 112. The structure of these injectors 121 is similar to that shown in FIGS. 1-3, but a second filter layer 119 is placed next to the charged area 117. This filter layer 11
9 is formed by wire meshes 125, 126 arranged at right angles to the vertical plates 111, 112, and the charging area 117
Each of them is connected to the positive and negative electrodes of a high-voltage direct current or to two terminals of an alternating current power source in order to electrostatically collect fine particles contained in the gas flow that has passed through. Air to be purified is arrow 1
It flows into the inlet 114 from the direction 52 and is discharged from the outlet 116 in the direction of the arrow 153 after being purified.

Although the dust collector of this example has a smaller capacity than the example shown in FIG. 1, both examples have better dust collection ability than conventional dust collectors. be. The precipitator shown in Figs. 5 and 6 is used to purify exhaust gas which exhibits a pressure of, for example, 12 bar and a temperature of 900 qo, such as when coal or waste materials are combusted under pressure in a furnace. It is something.

This precipitator for purifying high-temperature gas is made of a cylindrical filter member, and the gas is circulated so that the temperature of the gas does not drop to a minimum between the time when the gas enters from the inlet and is discharged from the outlet. This gas is generated from a fluidized bed furnace that feeds preheated air. The gas to be purified is pipe 20
1 flows into a tank 202 under pressure, and the inside of this tank 202 is covered with a heat insulating material 203, and the overall shape of the tank is a dome 205 with a hemispherical top and bottom.
and 206, and the middle part is cylindrical.

A series of ventilation nets 20 are provided between the insulation material 203 and the metal plate 211.
8 are arranged and serve to circulate fresh air.
Inside the space defined by this ventilation network 208, there is a granular layer filter 207 coaxially arranged with the tank 202. This filter 207 is connected to the outer partition wall 2
It consists of a granular layer 210 filled with small alumina particles having two diameters between the inner partition wall 214 and the inner partition wall 214. The outer bulkhead 212 has an opening in its upper part, and the tank 20
The fine particles 218 are connected to a conduit 216 passing through the upper dome 205 of 2 to circulate within the granular layer 210 according to the direction of the arrow 22. An arrow conduit 222 is connected to the lower part and passes through the lower dome 206, and the fine particles 218 are discharged from this conduit according to the arrow 224. Partition wall 21
The fine particles packed between 2 and 214 move from the top to the bottom at a slow speed of, for example, lm/hour. The space defined by the metal plate 211 and partition wall 212 adjacent to the ventilation network 208 inside the tank is divided into two halves by an annular ring 225, with the high-temperature gas inlet 201 closed in the lower space 227 and the upper space 228 closed. The purified gas outlet 230' is closed. The partition walls 212 and 214 serve as annular sieves at 232 in the lower space 227 and at 234 in the upper space 228, so that the high-temperature gas containing dust entering from the inlet 201 is first filtered through the sieves. When passing through the sieve 232, it is physically purified by the granular layer 21 and enters the central chamber 250, and then further purified through the upper sieve 234 and discharged through the outlet 2301. Now, the second sieve 234 is used for electrostatic dust collection.

An upper insulating ring 240 and a lower insulating ring 242 are interposed at the boundary between the inner partition wall 214 and this sieve 234, and an upper insulating ring 243 and a lower insulating ring 244 are similarly interposed at the outer partition wall 212 to provide insulation. The sieve area of the inner diaphragm 214 is connected to a high voltage DC positive electrode 32, and the sieve area of the outer diaphragm 212 is connected to a negative electrode 321 to inductively charge the alumina particles incorporated into the sieve 234. These sieve areas can also be connected to high pressure alternating current. The central chamber 25 defined by the inner partition wall 214 is an area where the particulate dust remaining in the gas after passing through the first sieve 232 is charged, and therefore the two ion injectors 252 and 25
4 protrudes from the top and bottom and emits ions as an aerosol. The nozzles of injectors 252 and 254 are in tank 2.
02, and each emits ions facing each other along this central axis. After the remaining fine particles are charged in this central chamber 250, they are transferred to the second sieve 23.
4, the electrostatic dust is collected. Furthermore, the granular layer inside this sieve is gradually replaced with new ones as shown by the arrow 22, but the fine particles 218 that have passed through the sieve 234 are transferred to the first sieve 232 where they are physically purified. It will soon be used again. The electrostatically concentrated purified gas discharged from the outlet 230 undergoes an intermediate step of chemical filtration to remove alkali compounds or vanadium, and then is sent to a gas turbine or piston engine.

In the illustrated embodiment, the distance between injectors 252 and 254 is approximately one skin, and the diameter of central chamber 250 is 0.4 mm.
The gas to be purified is at a pressure of 12 bar and a temperature of 900 qo. Injectors 252 and 254 are supplied with moist compressed air, the metal nozzle tips are grounded, and the nozzle throats are one diameter.

A needle 45 corresponding to the needle 45 shown in FIG. 3 is built-in and connected to a 20 to 25 kilovolt power source. The current radiated by each injector is 1 at 27 bar, measured under normal pressure and temperature conditions.
When supplied through conduit 29 at a flow rate of 15 per hour, it is on the order of 250 microamperes. If this precipitator is used in a device such as a gas turbine with a megawatt output, assuming that the gas contains 100 ml of dust, the first sieve 23 will be removed from the cyclone.
Approximately 93% of the water was purified during the second stage, and the remaining 7 evenings were the second stage.
Electrostatic dust is collected by a sieve 234. The electric field generated in the central chamber 250 of the illustrated embodiment is about 50 V/m at an ion density of about 1 and 4 per meter, which is due to the fine particles charged inside the sieve 234. 0.9 sand corresponds to enough space charge to give an elementary charge of about 30 m to fine-grained dust with an average diameter of 3 microns to ensure that it is deposited by the 0.9 µm.

Under these conditions, the current carried by the charged particles to the second sieve 234 is 12 microamps. The reason why this current is small compared to the total amount of current emitted by the above-mentioned injector is that most of the current is absorbed by the metal inner partition wall 214 that is connected to earth. As already mentioned, the particles passing through the central chamber 250 via the injectors 252 and 254 are positive ions, and the value of the space charge caused by the movement of these positive ions is the same as the space charge generated in the corona discharge inside the injector. This is very small compared to the electric charge value.

In addition, in order to prevent the electric field from locally increasing inside the central chamber 250 and causing undesirable local discharge, the surface of the metal inner partition wall 214 that defines the central chamber 250 is polished to a glossy finish. It is something that has. As a result, the fine particles are uniformly charged inside the central chamber from which minute protrusions that induce electron avalanche are removed, and the efficiency of electrostatic dust collection by the second sieve is further enhanced. As in the above-described embodiment, when purifying high-temperature gas at 900 pm, for example, it is advisable to use structures of the injectors 252 and 254 that are slightly different from those shown in FIG.

In fact, when the temperature is very high, the charged particles contained in the gas rapidly fuse or sublimate near the nozzle of the injector. The released ions therefore return to the injector and are captured by it, thereby reducing the necessary space charge to charge the particulates carried in the gas to be purified. Two types of devices are possible to prevent or limit such leakage. One method is to apply a positive potential to the injector against a metal partition wall through which the gas to be purified circulates, and distribute an electric field so that ions generated from the metal pieces of the injector are diffused by a discharge action. Another method, which may be used in combination with the above devices or independently, is to cool the current of particles emitted by the injector.

This cooling is achieved by directing a path of cold air around the flow of the particles, which greatly retards heat transfer between the bulkhead and the particles, ensuring that the sublimation of the particles is far enough away from the injector. Since it is carried out in different locations, it is possible to prevent it from being captured by criminals. 7th
The injector 3101 shown in the figure consists of an injector tube 312 defining a chamber 314, through which moist air under pressure flows along an arrow 316.
The tip 318 of the tube 312 is an internal contour called the estuary.
Sent to the opening □ department.

An electrically conductive needle 320 is disposed on the central axis of the injection tube 312, and its tip 322 is connected to the nozzle throat 3.
Adjacent to 24. Needle 320 and Inzeku Tube 3
12 are each connected to a high voltage DC power supply 328, which tubes 312 are maintained at a relatively high positive potential of, for example, 20 kilovolts with respect to ground by power supply 33. The injector tube 312 is coaxially arranged inside the metal tube 332, but the tip 334 of this metal tube is bent slightly inward toward the barrier hole 336, and this tip 334 is connected to the chamber 314.
The injector tube 312 is located downstream of the tip 318 of the injector tube 312 with respect to the gas outflow direction. The metal tube 332 is fitted into an aperture formed in a metal partition 340' of a hot gas electrostatic precipitator 342 as shown in FIG. 7, for example. The partition wall 340 is connected as a whole. tube 33
2 is electrically connected to a high voltage source 331 such that the potential is the same as or different from that of the tube 312. Tube 332 is coupled to septum 340 by insulating member 333. Inside the electrostatic precipitator 342, a serpentine tube 344 is wrapped around the tube 332, through which a non-conductive cooling fluid flows. Snake pipe 3
A pipe supplying cooling fluid to 44 is connected to a high voltage source 3 with a positive potential.
31 and is made of an insulating material that can withstand. Means is also provided for venting from the annular passageway between the injector tube 312 and the metal tube 332 toward the interior of the precipitator 342 along arrow 346 (not shown).

Next, to explain the function, the flow direction 350 of the charged particulates radiated into the inside of the dust collector 342 is caused by the flow east 350 of the metal pipe 332
Surrounded by a stream of cold air emitted from injector tube 312, the particulate stream is delayed in being reheated and sublimation does not occur until it is sufficiently far from injector tube 312.

Furthermore, since this injector tube is maintained at a high potential with respect to the partition wall 340', it tends to move the emitted fine particle ions away from the injector tube 312. There is no particular inconvenience if the gas to be purified is cooled by the cooling air or cooling gas discharged from the opening in the metal tube 332. This is because the temperature of the gas emitted from the combustion furnace is far above 90,000 ℃, so even if the gas emitted from the injector is cooled down a little, it can be used sufficiently for gas turbines and the like. To this end, it will be necessary to have means for adjusting the temperature and flow rate of the cooling air according to the amount of gas discharged from the combustion furnace so that a desired gas temperature can be obtained at the inlet of the gas turbine or the like. Although the embodiment shown in FIG. 7 is also different from the embodiment described above, FIG. It shows.

Similar to that of FIG. 7, the injector tube 312 is maintained at a high potential against the grounded bulkhead 340'. However, cooling air does not flow around the particulate flow east. FIG. 9 shows the dust collector 3 of the injector tube 312 shown in FIG.
42 A flexible pipe 4 through which the cooling liquid flows on the outer peripheral surface protruding into the interior.
02 is shown in the figure.

A non-conductive liquid such as oil is used as the coolant.
The supply of oil to the serpentine tube 402 is provided by an insulated pipe of sufficient length to maintain the high voltage applied to the injector tube 312. Moreover, water deionized by a known method can be used instead of oil. Further, the flexible tube 402 is made of an insulating material in view of the high pressure applied to the injector tube 312.

In the version shown in FIG. 10, the injector tube 312 is connected to a high voltage source 408. This injector tube is surrounded by a metal tube 332 and emits cooling air around the stream of emitted particulates. The metal tube 332 is joined to the partition wall 340' via an insulating section 406, and a positive potential is applied by a high voltage DC power source 408. In the embodiment shown in FIG. 11, an injector 412 as shown in FIG. 7 is located at the tip of the pendant tube 410, and the injector 412 is opened in the same direction as the gas flowing in the direction of arrow 441 at a speed of 3 skin per second. There is.

The pend pipe 410 is for sending moist air to the injector 412, cooling air to the metal pipe 332, and cooling liquid to the above-mentioned corrugated pipe, and passes through the partition wall 440. As previously mentioned, the injector 412 is oriented such that the cooling air is ejected in the same direction as the gas stream to be purified and at the same rate (3 per second in this example).
The diameter of the metal tube 332 is about 4 degrees, the amount of cooling air is about 2% of the flow rate of the gas to be purified, and the temperature of the gas is slightly above 900°C. The radial area of the injector is approximately 15 arc radii from the tip of the injector 412.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional perspective view of an embodiment of a precipitator according to the present invention, and FIGS. 2A and 2B show a first arrangement of the dust collectors.
Figure 3 is a cross-sectional view of the injector in the vertical direction, Figure 4 is a local cross-sectional perspective view showing a dust collector for high-temperature gas, and Figure 5 is a side view taken from plane 1-1 in the figure. A sectional view in the mari direction showing another embodiment of the vessel, FIG. 6 is taken along the chain line W- in FIG. 5.
FIG. 7 is a schematic cross-sectional view showing another embodiment of the ion injector, and FIGS. 8, 9, and I0 show three modified examples of the injector shown in FIG. The explanatory diagram shown in FIG. 11 is a sectional view showing an example of the arrangement of the injector. 10,110,342...dust collector, 11,12,111
, 112... Vertical plate, 13... Bottom plate,
14,114,201...Entrance, 15...Top plate, 16,
116,230...exit, 17,117...charged area,
19... Electrostatic dust collection area, 20... Charging plate, 21, 121, 252, 254, 310, 412
...Injector, 30...Cylindrical tube, 4
2,49,51...Cable, 45,320...Needle, 48...Power supply, 119...Filter layer, 202...Tank, 203...Insulation Material, 208... Ventilation network, 210... Granular layer, 212, 214... Partition wall, 218...
... Fine particles, 225 ... Annular ring, 250.
...Central room, 243,244. ...Insulation ring, 3
32...Metal pipe, 400...Insulating member, 402...Serpentine pipe. Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 Figure 8 Figure 10 Figure 11 Figure 6

Claims (1)

[Scope of Claims] 1. In a method for separating fine particles in which the gas is passed through a precipitator to collect fine particles suspended in the gas due to static electricity, supersonic expansion of air is used to cause cooling. At the same time, the moisture present in the air is cooled, and at the same time the ions generated at the nozzle throat are captured by the ice microcrystals that are generated.The ice microcrystals that have captured the ions are brought into contact with the gas to be purified and evaporated. A method for separating fine particles in a gas, characterized in that the fine particles floating in the gas generate a space charge by ions liberated from fine crystals of ice, and are then electrostatically collected. 2. The method of claim 1, wherein the humidity of the humid air is greater than or equal to 10% as measured under normal humidity and pressure conditions. 3. According to claim 1 or 2, the flow rate of the ice microcrystals into the precipitator is adjusted to maintain the space charge at a predetermined value. Method described. 4. According to claims 1 to 3, the gas is a high-temperature gas and captures positive ions in order to generate a positive potential space charge in the flow path of the high-temperature gas. the method of. 5. Claims 1 to 3 above, characterized in that the gas is air containing gluten particles and captures negative ions in order to generate a negative potential space charge in the air flow path. The method described in. 6. In a device consisting of a chamber through which the gas passes, an ion generator using corona discharge to charge the fine particles, and a means for electrostatically collecting the charged fine particles in the gas flow path, the ion generation The vessel has means for defining a chamber of the precipitator and communicates with the chamber by an orifice, and further means for generating a corona discharge in the gas stream directed toward the orifice in the chamber. and means for forming by supersonic expansion of moist air in the area of said corona discharge microcrystals of ice suitable for trapping ions before being emitted from said orifice to said precipitator. Features: A device for separating fine particles suspended in gas. 7 This is for removing combustible particulates contained in the air inside the grain silo, and the means for generating corona discharge is a negative electrode with respect to the counter electrode to generate corona discharge between the counter electrode and the counter electrode. 7. Device according to claim 6, characterized in that it consists of a central electrode maintained at an electrical potential. 8 This is for removing particulates contained in high-temperature combustion gas, and the means for generating the corona discharge is such that the space charge induced in a part of the precipitator becomes a positive potential and the space between the part of the precipitator and the second electrode is 7. A device as claimed in claim 6, characterized in that it comprises a central first electrode which is maintained at a positive potential with respect to this second electrode to generate a corona discharge. 9. Apparatus according to claim 8, characterized in that the inner wall of the precipitator in the space charge area is polished and shiny. 10. The means for forming ice microcrystals comprises a nozzle located at least in the region of the orifice and means for directing moist compressed air into the precipitator to cause supersonic expansion at the nozzle; The means for generating a corona discharge comprises a pointed electrode reaching the nozzle throat and means for applying a high DC voltage between the nozzle and the electrode to generate a corona discharge in the air passing through the nozzle. An apparatus according to any one of claims 6 to 8, characterized in that: 11. Claim 6, characterized in that the orifice is formed inside the injector and has means for limiting the capture of ions in the vicinity of the injector emitted into the precipitator. The apparatus according to any one of items 1 to 10. 12. The means for limiting the capture of ions comprises means suitable for creating an electric field distribution in the vicinity of the injector which directs the emitted ions away from the injector. equipment. 13. The device according to claim 12, wherein the means for creating the electric field distribution is to create a potential difference between the injector and the partition of the precipitator. 14. The apparatus of claim 13 further comprising means for withstanding high voltages for supplying non-conductive coolant to the injector. 15 In particular for the collection of hot gases, the means for limiting the capture of ions shall consist of means suitable for retarding the evaporation of the ice microcrystals in the vicinity of the injector inside the precipitator. Claim 11 is characterized in that:
15. The apparatus according to any one of items 1 to 14. 16. The device according to claim 15, wherein the means for delaying the evaporation of the ice microcrystals comprises means for spraying a cooling gas around the aerosol flux radiated into the precipitator. Device. 17. The above-mentioned patent claim, characterized in that the means for spraying the cooling gas is a tube attached around the injector and passes through a partition of the precipitator, and the cooling gas is blown between the injector and the tube. Apparatus according to scope 16. 18. Apparatus according to claim 17, further comprising means for cooling the tube. 19. The device according to claim 17 or 18, wherein the tube is insulated from the partition wall of the dust collector and has means for creating a potential difference between the tube and the partition wall. .