DE2235531A1 - METHOD AND DEVICE FOR REMOVING FOREIGN MATERIALS AND THE LIKE. FROM A FLOW OF GAS - Google Patents

Description

PATENT LAWYERS

DlPL-ING. BUSCHHOFF

DlPL-lNG. HENNICKE

DlPL-lNG. VOLLBACH

5 COLOGNE / RH.

KAISER WILHELM RING 24

File:

Registration number.

Tc 402 I COLOGNE, July 18, 1972

please specify VO / WHERE

Patent application

the company ^

The Ceilcote Company, 140 Sheldon Road, Berea, Ohio 44017 (USA)

Method and device for removing foreign matter particles

and the like from a gas stream

The invention relates to a method and a device for removing foreign matter particles and the like from a gas stream with a liquid-gas contact zone through which the gas stream flows, in which the gas stream loaded with the particles comes into intimate contact with a liquid flowing through the contact zone with a large surface < >

It is known to have impurities or extremely fine foreign matter particles loaded gas streams to be subjected to wet cleaning

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draw. For this, working with low energy consumption washer used with success, the interior of which with a Mass of randomly oriented! Packing is filled, through which a cleaning liquid, such as water, under gravity flows through. The gas to be cleaned flows through the Washer at low speed in the direction of the liquid flow, in the opposite direction or across the liquid flow, the larger particles mainly due to the impact on the packing elements and the liquid flow be removed from the gas stream. The fine particles contained in the gas come into contact with the liquid The washing liquid drips and is carried away by it or they bump when passing through the washer on the surface of the packing elements. The particles carried along by the liquid droplets migrate through the Packing space to a sump, while the particles adhering to the surfaces of the packing are removed from the washing liquid rinsed and thus also fed to the sump by the washing liquid.

Gas scrubbing devices of the aforementioned type provided with packing elements can, depending on the type of packing elements used has been used with good success in removing particulate matter 1 micron or larger in size from a gas stream will. In this way, particles of 3 microns or more can be extracted almost completely from a gas flow. Those Particles between 1 and 5 microns in size

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as well as the even finer particles, however, remain for the most part in the gas flow.} They move in the gas flow past the I ¹ liquid droplets and the filler elements and get to the outside with the purified gas flow. Although scrubbers of the aforementioned type, as mentioned, are extremely effective for cleaning contaminated gas streams, they have the disadvantage that extremely fine particles are not removed from the gas stream but are led out of the gas scrubber with it. With a view to avoiding pollution and pollution of the air, however, it is generally advisable to remove even the finest particles from the gas flow, which have previously been discharged into the open with the gas flow.

For removing foreign matter particles from a gas stream other washing devices with low energy requirements are also known. For example, wet cyclone scrubbers are used for this purpose, Trickle towers and trickle chambers, columns with baffle plates, bell-bottom towers and the like, although the latter Devices are quite useful for cleaning gas streams, but they are generally in their effectiveness according to the filler washers. None of the latter devices are capable of producing ultrafine "particles micron size or significantly less to any appreciable extent.

In the past, you have such very fine particles with you

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With the help of fabric filters, electrostatic precipitators or those that work with high energy requirements Venturi-type scrubbers removed from gas streams. Devices of this type are indeed the finest for removal Particles from gas streams can be used} however, they have several disadvantages. Fabric filters are space consuming and require high investment costs. They are also sensitive to temperature and therefore only in certain temperature ranges usable. In addition, they cannot absorb gases. They are easily damaged by sticky substances and cannot be used or can only be used to a limited extent in a corrosive environment. Also, the use of Bag filters are associated with extraordinarily high operating and maintenance costs.

Electrostatic precipitators for deposition Very fine particles are also undesirable large-scale systems, especially when they are for use are intended in a corrosive environment, cause extremely high investment costs. When the from the gas flow The impurities to be removed are wet or sticky, there are considerable operational difficulties. Should with such separators particles in the size range be removed below 1 micron, this can only be achieved with a substantial increase in the size of the entire system. Electrostatic precipitators cannot absorb gases; their running costs are also extraordinary high.

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The Venturi-type hate washers also require one extremely high energy requirements and are therefore very expensive in terms of their operating costs. For example, the Pressure drop on passage of a gas stream through this scrubber 254 to 2540 mm column of water, the gas velocity being when passing through the Yenturi throat in general 38 to 152 m / sec. It goes without saying that such a high-performance system also requires considerable maintenance and operating costs.

The main object of the invention is to overcome the aforementioned disadvantages of the known devices sided. In particular, the invention aims at a method and a device which are highly effective and good efficiency in gas cleaning, with one with low energy consumption for gas cleaning working scrubber should be used, with which even the finest particles, be it solid particles or extract them in liquid form from gas streams permit.

The method according to the invention is characterized in that the particles carried along in the gas stream are electrically charged and the gas flow is washed by means of a washing liquid which is kept electrically neutral, the flow velocity of the gas in the contact zone is set so low that the electrically charged particles due to the attraction of the in fine distribution

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"located liquid against the drag force of the Gas stream are pulled out of this.

According to the invention, the cleaning effect and the efficiency of the gas cleaning device can thus be considerably improved increase that the solid or liquid particles entrained in the gas stream are electrostatically charged in the gas stream and the gas stream is passed at low velocity through a contact zone in which it is electrically connected comes into contact with neutral surfaces. A wet gas scrubber is expediently used as the contact zone used, which has only a low energy requirement, causes low system and operating costs and is also in can be used in a corrosive atmosphere. Such a washer also has the advantage that he at the same time absorb polluting or harmful gases with the removal of the fine particles from the gas stream. With The method according to the invention can thus be used using a method that operates with a low energy requirement Wet scrubber not only contains the larger particles, but also very fine particles of micron size and below remove effectively.

The method according to the invention and the device according to the invention intended for its implementation thus offer the possibility of simultaneously larger and small particles in solid or liquid form and / or particles as well as contaminating Remove foreign gases from gas streams, whereby

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there is also the possibility of condensing vapors with the formation of fine liquid particles, which then form can be extracted from the gas flow. For example, they can be found in the exhaust gases of a cupola furnace in a gray iron works effectively remove any particles contained in it. It is also possible, e.g., ELSCL particles in the mist or the vapors of a Separate sulfuric acid plant. The simultaneous deposition of particles and gases can be advantageously used e.g. in aluminum reduction systems, in which, in addition to foreign matter particles Hydrogen fluoride gases arise in phosphate fertilizer plants, in which, in addition to foreign matter particles, hydrogen fluoride gas is produced, as well as in the case of fossil fuels. operated boiler systems and the like, which produce sulfur dioxide and fly ash. Furthermore you can according to the invention gases which are mixed with odorous substances in the form of extremely fine liquid particles are cleaned.

As mentioned, according to the present invention, there is one loaded with foreign matter Gas stream cleaned by the fact that the gas stream is ionized, whereby the foreign matter particles are electrically charged are, whereupon the gas stream is passed through the contact zone in which it is in contact with a electrically neutral washing liquid arrives, which expediently has a large number of moving neutral surfaces forms, as is the case, for example, with a trickle process. Difi charged particles are then separated from the neutral ones

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Liquid surfaces attracted and thus out of the gas flow brought out. The device for ionization, with which a negative charge is imposed on the particles, for example, is located in the path of the gas stream to be cleaned. The particles entrained by the gas stream through the contact zone all have the same polarity so that they do not attract each other. To the attractions to the To utilize purification of the gas as much as possible, the gas is expediently at such a low speed passed through the contact zone that the forces of attraction the velocity of the particles and the overcome viscous attractive force exerted on the particles by the gas. Would the speed of the gas flow be too large compared to the neutral surface, the smaller particles were not removed from the gas flow, but taken along by this through the contact zone and the gas outlet.

The invention is of the wet working electrostatic To distinguish separating devices! it also does not provide any Coordination of the electrostatic precipitators with wet scrubbers. The conventional electrostatic precipitators work in such a way that initially the particles to be deposited are charged in an ionization part and then passed through an electrostatic field in which the particles are under the action of the Coulomb's see forces to deposit on a quilt

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to be brought. The Coulomb 'see forces are those Forces that are charged in an electrostatic pressure Particles work. Accordingly, "the operation of a conventional electrostatic precipitator is based on both Charge of the particles as well as the application of an electrostatic charge. In contrast, according to the invention without Electrostatic field worked, so that there is no dependence on the Coulomb's forces. A conventional one Wet electrostatic precipitator works with a flushing liquid that flows over the collecting surface runs and thus removes the material attached to it. Such a separator is also based on the effect of a electrostatic field.

The device according to the invention can be designed structurally in various ways. According to the general basic idea, it has surface elements with a large number of moving electrically neutral surfaces, which are formed by a washing or cleaning liquid, which the contact zone in a thin veil or in a fine distribution in the form of individual liquid streams, liquid droplets or the like. flows through, in such a way that these surfaces come into contact with the gas to be cleaned. The amount of liquid is transversely preferably about 4880 to 488,000 kg / m per hour, as measured to the flow direction of the liquid "The contact zone may have more surfaces, for example, by the Gerätewandungen, silica or drip plates ₉ in which

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AO

the washing liquid flows along, splash plates on which the liquid impinges, guide elements which the Direct liquid over a curved path, a permeable mass, which e.g. from packing elements in random Distribution exists, or can be formed by other surfaces. The washing liquid can alone under the action of gravity or forced through the contact zone} it can be in any suitable Manner, such as by means of spray nozzles, overflow gutters, perforated distribution containers or the like. Introduced into the contact zone will. The gas stream to be cleaned can move at low speed in the same direction as the scrubbing liquid flow through the contact zone. However, it can also be in the opposite direction to the washing liquid or transversely to the direction of flow the liquid are passed through the contact zone. The gas velocity is preferably approximately 60 to 1070 mm / sec. There are those Gas speed and the flow rate of the liquid so coordinated that at a higher gas speed worked with a smaller amount of liquid or a lower liquid passage speed will. If the gas velocity is increased, the amount of liquid must be reduced to account for the pressure drop to keep it low and to avoid flooding. In any case, the gas flow must be opposite the neutral surface have a low speed, so that the charged particles either hit the neutral surface

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surface, or "over" in the dense Yorbeigang on the Surface due to the attraction from the surface be attracted.

According to a preferred embodiment of the invention, a scrubber is used which has a packing material is provided. For the! Filler elements or the like are preferably made of wire elements. existing packing in random Orientation used, the material of the filling body consists of a dielectric material. Die'under gravity the liquid flowing through the packing material vertically is divided into numerous partial flows, the move down curved flow paths, with the gas loaded with the charged particles also moving on curved flow paths the contact zone in any flows through any direction. The packing elements have narrow, elongated wire elements with numerous Surfaces against which the washing liquid droplets when passing through the packing material, causing the liquid droplets to be torn open and / or in their direction of flow are deflected. · When the gas mixed with the charged particles passes through the packing mass pushes those carried along by the gas stream Particles either against a packing surface or they move with the gas flow in the vicinity of these surfaces past. Other particles carried along by the gas hit the drops of washing liquid or at some point

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they move past these droplets at a close distance. In any case, the force of attraction between the charged particles and the neutral packing elements as well as the neutral washing liquid that the particles are attracted by the scrubbing liquid or the packing elements and thus taken out of the gas stream, wherein they are carried along by the washing liquid flow through the packing material. When using wire-shaped packing elements the number of individual filler surfaces is increased and thus the formation of droplets is increased. the Areas of the wire-shaped filler elements are each only very small and, because of the resulting large ones Number of surfaces particularly effective. Increasing the area and increasing the formation of drops increases the likelihood of that charged particles are so close to the surfaces and droplets as they pass through the contact zone wander past that the force of attraction for the separation of the particles from the gas stream can be effective.

The ionization device used to electrostatically charge the particles entrained in the gas flow can be of any suitable design and e.g. from a wire and plate system or a pipe and Wire system or the like. exist. To achieve the best possible corona discharge, the amount contained in the gas flow is used Particles usually have a negative charge imposed on them, although the charge can also be positive. There is also the

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Possibility of successive parts of the gas stream contained particles alternately a positive and negative To give charge, with the ionizing elements in this pail can be applied to an alternating current. The nature of the particles to be removed from the gas stream determines in part the polarity that is used to obtain the best results. The device according to the invention can so be designed so that you can work with different air velocities. Above all, it is essential that the residence time of the particles in the ionization zone is sufficiently long for the particles to be charged. the The device according to the invention can have a short ionization zone at a low gas velocity or a longer one Be provided ionization zone at higher gas velocity. Under certain circumstances, e.g. when hot gases or cleaned gases laden with sticky-viscous particles are to be, it is appropriate to cool or shower the gas stream before entering the scrubber housing. This can be achieved with Yorteil in that the gas flow between the ionization device and the scrubber housing is sprayed with a neutral liquid, this spray treatment the deposition of the particles in the favored way according to the invention. For the washing liquid, water is used in most cases, though it is also possible to work with other washing liquids. The washing liquid can also be used for spraying or. Away-

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roaring of the gas can be used.

The charging of foreign matter particles in a gas stream and the subsequent separation of the particles from the gas stream can be found in US patents 2,621,754, $ 218,781 and ^y j $ 65,403, as well as in German patent 1,025 and French patent 500,775 . The present invention differs significantly from the methods and devices described here. In US Pat. No. 2,621,754, a gas stream loaded with foreign matter particles is ionized and then passed at high speed through a purifier of the Venturi type which operates with high energy requirements. The gas stream loaded with the particles to be deposited flows at a speed of at least 12 to 76 m / sec into a spray tank or the like filled with water. At these high gas velocities, the gas hits the surface of the water with considerable force, creating turbulence in the tank. Such a device differs considerably from the device according to the invention, which operates with low energy requirements, in which the gas velocity is a maximum of about 10.7 m / sec and in the gas-liquid contact no high-energy turbulence is caused. In the USA patent specification 5 363 403 a cleaner of the Venturi type which operates with high energy requirements is also disclosed. In this case, the gas ti'om is first supersaturated with steam and then in a venturi

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The nozzle is suddenly relaxed, with some of the steam coming on condenses the particles contained in the gas stream, whereby particle enlargement and coating of the particles can be achieved with a liquid film. The gas flow A rapid rotary movement is also given with the help of wings and the like, whereupon those encased in the steam film Particles in an electrostatic precipitation system, consisting of a conventional rod and pipe system, in which the particles are charged and under the Deposited under the effect of an electrostatic field will."

U.S. Patent 3,218,781 discloses a device in which the gas laden with the foreign matter particles is passed through a liquid such as water. The gas is ionized to charge the particles, while the water through which the gas bubbles is kept neutral. When the gas laden with the particles passes through the water, the particles are thus separated out by the water. Although this device is used to extract particles from a gas stream using a force of attraction, this device differs v / e sent borrowed from the device according to the invention. A disadvantage of this earlier device is primarily that it has an extremely low efficiency and therefore only small amounts of Gan can be enforced. There is also a risk of constipation in the small JfurMJ). hur, VJ.'i ;;;: ej-bnd must have a considerable depth,

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which results in considerable pressure drops in the gas flow. The pressure drop increases further when the number the bubble trays or bubble plates is increased.

German patent specification 1 025 590 discloses a system in which the particles carried along in a gas stream are charged and then made to attach to a film of water will. The device works here on the principle of an electrostatic separation device, as the water film surrounds an electrode and serves as a collecting surface on which the particles are due to the electrostatic field attach. French patent specification 500 775 discloses also an electrostatic wet cleaner, in which the particles contained in the gas stream are given an electrostatic charge, whereupon the particles are deposited on collecting surfaces under the action of an electrostatic field will. The collecting surfaces are arranged here axially behind grid electrodes in the direction of flow. Between a voltage difference is maintained between the grid electrodes and the collector plates, so that those contained in the gas flow Particles are charged as they move through the gap between the grid electrodes and the collector plates move through. The distance between the parts mentioned in the direction of the gas flow complements the effect of the applied electrostatic field in which the particles under the action of the Coulomb's forces counteract in the direction of gas flow the collecting plates are pulled. The grid electrode is

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Not suitable for oneself alone, those streaming past it Charge particles. Rather, the particles must be in the zone or space between the grid electrode and the collector plates cycle through to achieve a charge.

With the invention one is working with a low energy requirement Wet scrubber created, which compared to the known facilities by higher performance and characterized by higher efficiency. The higher degree of effectiveness with regard to the lowering effect is due to the combination effects low energy flowing gas, wet cleaning, and particle charging. In addition, in the device according to the invention, at the same time as the removal of solid and / or gases polluting liquid prematerial particles are absorbed. The device according to the invention is characterized through high performance, high economic efficiency and comparatively low investment, operating and Maintenance costs.

Further details of the invention emerge from the following explanation of the drawings. In these show:

Pig. 1 shows a device according to the invention in plan

seesj.

Pig. 2- the facility according to Pig. 1 in side view,

partly in section}
Pig. 3 when setting up according to the Pig. I and 2

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provided ionization part in a section along line 3-3 of FIG. 1;

4 shows a schematic illustration for explanation the forces acting during the separation of the particles j

5 shows a single wire-shaped packing element and, in connection with this, the process of separating the particles from the gas stream |

6 likewise shows a schematic illustration to explain the deposition process.

The drawing, in which a preferred embodiment of the invention is shown, shows in FIGS. 1 to a facility that consists of a. Cleaning part or a washer 10 and an ionization device 12 consists. The two parts 10 and 12 are assembled to form a closed structural unit j they thus form a single unit Device.

The cleaning part 10 has a housing which, in the illustrated embodiment, has a rectangular cross section s shape and from opposite side walls 14, an upper wall surface 16 and a bottom wall 18 consists. The walls 14, 16 and 18 can be made of any suitable metallic material or non-metallic material, e.g. a glass fiber reinforced Polyester resin to protect the device from the effects of a corrosive atmosphere.

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The housing encloses a contact zone j it is with a Inlet end 20 for the entry of the gas to be purified and provided with an outlet 22 through which the purified Gas is discharged. A support element 24 is arranged in each case within the contact zone in the vicinity of the inlet and outlet, which is used to support the packing compound accommodated in the housing. The packing mass consists from individual packing elements 26, which are in the packing mass are in a random, unregulated orientation. The packing elements preferably consist of wire elements made of a dielectric plastic material such as polyethylene, polypropylene, polyvinyl chloride, nylon etc. However, other non-conductive materials could also be used, like ceramic materials, or also'conductive ones Substances for the packing are used. The support elements 24 are open for gas passage; They consist, for example, of nets, grids, grids or the like, with their openings are of course so small that the packing elements cannot get through.

The filler elements 26 are randomly poured into the housing, they therefore form in the space between the side walls 14, the bottom wall 18 and the top wall 16 r; like the support elements 24, a porous, permeable mass that forms the space The filling body - ii '. \ cmhSito uiid. the housing walls form ntata r.che surfaces within the contact zone, but this does not exclude that

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8AD ORIGINAL

these surfaces can move within the contact zone, e.g. when the cleaning device or the packing elements of a vibrator or the like. be set in vibration to a displacement and displacement of the packing elements to effect within the contact zone. The term "static surface" means that it is This concerns areas which are enclosed within or essentially within the contact zone. At the top Wall 16 is provided with a spray device 28, with which a liquid can be introduced into the contact zone. This spraying device 28 consists of one larger number of spray nozzles 30, the nozzle openings of which are above the packing mass and which are each in groups are connected to a common manifold 52. The two parallel manifolds 32 are connected to a common Feed line 34- connected to a circulation pump for the washing liquid is connected. The washing liquid is finely distributed with the aid of the nozzles 30 sprayed onto the surface of the packing mass. Guide plates 36 or the like can be used between two pairs of nozzles 30. be provided, which prevent the gas stream from flowing over the surface of the Füllkorpermasse and thus the Filling body bypasses. The washing liquid flows through the filling body under the action of gravity below and collects in a collecting space or sump 38, which is arranged below the bottom wall 18 of the housing. That part of the packing manse that is in the area doi;

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Gas outlet located behind the last nozzles in the rows below the head surface area 37 is preferred not sprinkled with the washing liquid from above; it therefore forms a dehumidification section in the packing mass, in which the liquid mist is removed from the gas stream before it leaves the device.

The bottom wall 18 has a number of drainage openings 40 through which the washing liquid runs off into the sump 38. The pump 42 is connected to the sump 38}, it has an inlet pipe 44 _f which above the bottom surface. of the sump, in which a certain level of liquid is maintained. The pump outlet line 46 leads to the pump manifold 34, via which the spray nozzles are fed. The washing liquid therefore flows through the packing material and "enters the sump, from which it is drawn off by the pump and fed back to the spray nozzles Sump 38, - a certain proportion of which is deposited at the bottom of the sump. The deposited substances can be drawn off if required via a drain opening 48 on the bottom surface of the sump the fresh washing liquid is fed to the system, with continuously contaminated via the overflow 50

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Washing liquid is withdrawn from the sump.

A spray line 54 is located between the inlet 20 of the scrubber housing and the adjacent packing support element 24 arranged, provided spray nozzles 56 distributed over their length which are directed against the support element 24 and the sieve-like support element 24 from any deposits Keep clear of the substances to be removed. The inlet end 58 of the conduit 54 can be connected to any liquid source, e.g. connected to the washing liquid supply of the pump 42, openings 60 in the bottom 18 serve for drainage the rinsing liquid sprayed from the nozzles 56 towards the sump.

The passage of the gas stream laden with the foreign matter through the scrubber can be in any suitable manner, e.g. can be achieved by means of a fan or blower 62 which is connected in one to the outlet 22 of the washer Outlet line 64 is arranged. The fan 62 or the like. can be of different training; it is designed so that the gas with the necessary for the cleaning process Speed flows through the washer. The outlet 65 of the fan can be connected to a shaft, flue or chimney or the like. be connected.

An ionizing device 12 is connected to the inlet 20 of the scrubber housing via a line 66. The ionizer can also directly with the scrubber housing, so

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without intermediate line. It has the task of electrostatically charging the foreign matter particles entrained in the gas flow, regardless of the respective location and assignment of the scrubber housing inlet or the contact zone. The ionizing device can be of different design. In the embodiment shown, it has a housing of rectangular outline form, which is formed by side walls 68, a bottom 70 and an upper head wall 72. Corona wires 74 and tubes 76 are provided in an alternating sequence between the base 70 and the top wall 72, approximately parallel to one another and aligned with the side walls 68. The wires 74- are kept under tension by cross members or cross rails 78 made of conductive material. The transverse rails 78 have insulating elements 80 at their ends, by means of which they are supported on conductive plates 79 on the top and bottom of the ionization housing. The tubes 76 lie between the wires and are also conductively connected to plates 79. Spray lines 82 and 84 (Fig. 2) extend from top to bottom through the ionizer housing; they have Sprühdüsen.auf, which are directed against the wires 74 and 76 bores. With the help of this spray nozzle, the elements of the ionizing device can be sprayed continuously or intermittently in order to prevent foreign matter particles from spreading to the ionizing device . The spray nozzles are (not) supplied by a (not) "" toi! Lfen) "Tüijnigkeitijquelle" via lines 86, 88 and

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BATH ORIGINAL

90 fed. The ionizing elements can also be cleaned in another way. For example the tubes 76 can be provided with openings directed towards one another and even connected to a cleaning agent source be connected, via the water, a solvent, steam or the like. is fed to the individual tubes, so that the cleaning agent emerging from the pipes sprays the adjacent pipe. One or the other Spray cleaning can also be provided in conjunction with or independently of spray lines 82 and 84. The bottom of the ionization housing is provided with a sump 92 in which the liquid collects and exits from which the liquid is drawn off via an outlet line 94 can be. The washing liquid can again be fed to the spray lines of the ionizing device or else can be discharged will. It will be understood that in conjunction with, or independently of, liquid spray cleaning this can also be used with other cleaning devices for cleaning the ionizing device. For example the ionizing elements can also be cleaned mechanically, e.g. by means of knockers, scratches etc. Cleaning by means of a steam or air jet is also possible. A steam heating of the surfaces of the Ionizing elements can be provided to loosen and remove baking-prone viscous substances.

The corona wires 74 are via a line 98 and one of the

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Seemed transversely. 78 to one side of a Ho cn voltages direct current source 96 connected, the other side of which is connected to earth. The tubes 76 and the rest Parts of the ionization housing are by means of a line 100, which over the metal plate 79 with one end of the Pipes connected, grounded. The output power of the power source depends on various factors, such as the wire and pipe spacing. In general, it comes with an output voltage worked from 5 to 150 kV.

The inlet of the ionization housing is connected via line 102 to a device or system from which the gas to be cleaned which is loaded with the foreign matter is withdrawn will. Instead of the ionization device described above, other devices, e.g., a radiation ionizer can be used.

In order to ensure that the scrubber, the washing liquid and the filling bodies remain electrically neutral and are not influenced by the charged particles, the device is earthed, which, for example _; is accomplished with the aid of the line 103 connected to the scrubber sump 38. The washing liquid circulates in contact with the wall surfaces of the washer housing and the surfaces of the filler bodies and, due to its conductivity, has the effect that these surfaces are constantly neutralized. If the washing liquid gets into the sump as it circulates, the neutralization of the

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Liquid brought about due to the grounding of the sump. If the wall surfaces and / or the fillers are conductive, their neutralization is supported by earthing the device. The liquid droplets naturally form collecting areas, which move through the packing mass and neutralize it when they come into contact with a charged particle, whereby the charge is transferred to the droplet. However, the total amount of water droplets is in proportion to the The mass of the foreign matter particles is large, so that the charge given to the droplets is only of a size that is the neutral one The character of the droplets is not noticeably influenced. In addition, the total mass is the constantly trickling through the washer neutral droplets are considerably larger than the total mass of the charged ones present in each case in the scrubber Particles, so that the neutral character of the liquid and the other surface elements of the scrubber through the transition the particle charges are not affected.

The separation of the large foreign matter particles from the gas flow is mainly due to the impact of these particles on the liquid droplets and the other wall surfaces of the scrubber. This effect is supported by the Attractive forces between the charged particles and the neutral surfaces. It can be assumed that the deposition of the fine particles, namely those of the micron size range and below, mainly by attraction thereof Particles on the neutral surfaces comes about. A sol-

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before attraction arises when the particles are in immediate Come close to the neutral surfaces and have such a slow speed that the force of attraction between the particles and the areas the particle velocity and d. that exerted on the particles by the gas flow Entrainment force overcomes, so that the particles are taken out of the gas stream and in contact with the respective Area. It is further assumed that the forces of attraction cause the inertial impact of the finest particles in the micron range and below on the neutral surfaces bring about, while an inertial impact of such small particles has not previously been achievable. Furthermore is of it to assume that the mutually repelling charged particles have less of a tendency as they move in the gas stream have to approach each other, but rather have brought them closer to the neutral surfaces due to the repulsive forces so that the forces of attraction leading to their separation can be effective. Another effect which occurs during the gas cleaning in the device according to the invention, should consist in the fact that small charged Particles and those particles that have also become neutral due to their contact with a neutral surface are, mutually attract and close together, which also improves the deposition effect. the mutual repulsion of the particles should lead to them being driven more towards the outer boundary layers of the gas flows werdon, which makes them so close to the wall surfaces of the

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Washer and the packing reached that the forces of attraction overcome the particle velocity and the drag force of the gas exerted on the particles.

The force of attraction between a charged particle and a neutral surface can be seen from a consideration of the Understand the schematic of FIG. If a particle A has an electrostatic charge, e.g. a negative Polarity, comes close to an electrostatically neutral surface B, it induces an electrostatic charge opposite polarity in face B, creating an attractive force between the negatively charged particle A and the now positively charged surface B. The size of the attraction depends on the size of the charged particle A and the distance D between the particles and the surface B. The attractive force between the charged particles and the surface carrying the induced charge is comparable to a force of attraction that is between a charged particle A and a charged particle C with the same charge but opposite polarity sets, which is located on the other side of the surface B at the same distance D. This comparison with a charge arranged in mirror image to the surface is referred to as a so-called "pixel force". For example, the Attractive force between particle A and surface B is a pixel force that is that between particles A and C acting force is equal. It is such a pixel

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force or attraction _r which is effective in the method according to the invention and the device according to the invention between a charged particle and a neutral surface due to the charging of the particles in the gas flow and the electrically neutral setting of the surfaces.

In Figs. 5 and 6, the manner in which the forces of attraction presumably act in the sense of a separation of the particles. In Fig. 5 is a single packing element 26 is shown which according to the preferred embodiment from a wire element formed into an annular helical body Plastic material or the like. consists of »kill bodies of this kind are known from US Pat. No. 2,867-425 and under the trademark "TELLERETTE" available in stores. In the Representation according to FIG. 5 is assumed that the packing element has such a spatial position that its axis runs in the direction of the vertical axis of the washer housing.

Each packing element 26 has a plurality of surfaces which lie in the path of the washing liquid trickling through the packing mass from top to bottom and in the flow path of the gas flowing through the scrubber from left to right, i.e. in the transverse direction in the exemplary embodiment A packing element applies _s so it flows around this winding along its surfaces "Since the gas flow zuvor.die lonisierungsvorriclitung has passed through ₃

3 0 9 8 0 7/1174 - 30 -

are the foreign matter particles carried along by the gas stream loaded. These charged particles also flow around the winding surfaces of the packing element, whereby they either come into contact with neutral drops of liquid or with the neutral surfaces of the packing element and can thereby be removed from the gas flow. This contact is made by the forces of attraction between the charged Particles and the neutral surfaces favored or brought about.

In Fig. 5 several charged particles P, to P, - are shown, after passing through the ionization device with the gas flow in the direction of arrow 104 into the scrubber enter. Since the gas flow flows around the packing element 26 at low speed and the washing liquid drops move from top to bottom across the gas flow, the particles P to Pg are roughly as follows from the Gas flow taken out: The particle P- has when flowing past such a distance from the packing element that it remains in the gas stream and over the packing element is carried along, where it reaches a liquid drop 106 at such a close distance that the airspeed of the particle and the entrainment force of the gas flow from the force of attraction between the liquid drop and the particle is overcome. The particle P is therefore taken out of the gas flow and arrives with the liquid, Keitstrop 106 over the packing material in the sump. That Particle P.-, also asked a?;, Such a distance from that

3Ü9 3Ü7 / 1 1 lh

Packing element that it remains in the gas stream. As it flows around the packing element, it encounters a drop of liquid 108, for example, the force of attraction between the particle P.sub.1 and the drop of liquid 108 promoting the impact of the particle on the drop. The particle P flows with the gas at such a close distance past the surface 110 of the packing element that the force of attraction overcomes the intrinsic speed of the particle or the entrainment force of the gas flow and the particle thus comes into contact with the contact surface 110. The particle P ^ is oriented in the gas flow in such a way that it is deposited on the surface 110 due to the inertial impact force, which is again promoted here by the force of attraction. The particle P ₁ - comes laterally past the surface 112 of the packing element, whereby it is also taken out of the gas flow due to the force of attraction. The particle P, - is caught by a drop of washing liquid 114 in front of the filler element due to the force of attraction.

A further explanation of the relationships results from FIG. 6. Here, 116, 118 and 120 denote neutral surfaces, which are formed, for example, by the wires of a pair of filler elements. A gas stream with the charged particles P ₁ - ,, Pg and Pq flows in the direction of arrow 122 past the surfaces mentioned. The gas stream flowing through between the surfaces 116 and 118 guides the particles P ₁₇

3 0 9 B 0 7/1 1 7

and Po with, which are brought closer to each other due to the narrowed gas flow path. However, since the particles carry the same charge and thus repel one another, they are driven towards the surfaces 116 and 118, the forces of attraction acting between the particles and the surfaces additionally assisting the separation of the particles. The particle Pq is guided past the surface 120 on the outside with the gas flow. A particle 110 is already on the packing surface 120; the mutual repulsion of the particles Pq and Pi Q », provided the latter has not lost its charge, the particle Pq pushes outwards, where it comes into the vicinity of a liquid drop 124, which it catches due to the forces of attraction. A particle P1 moves at a small distance past a liquid drop 126 and is drawn out of the gas flow by the latter. The drop 126 already carries a particle P-, ρ with it, but this is neutral because it has given its charge to the drop. The particle P ₁ -, is also neutralized on contact with the drop 126. As mentioned above, the droplet mass in relation to the particle mass is so great that the particle charge delivered to the droplets does not noticeably impair the neutral character of the droplets. There is therefore an attractive force between the drop 126 and the particle P ₁₁ , although the drop has the charge of the particle P-. has ρ.

It goes without saying that the above explanation of the

3 0 9 8 0 7/1 1 7 U

2 "^ ^ t Γ * P" O Ί / 'ί π "Λ"> ι & ν ^ \ J \ J \ J I

The mechanics of particle separation from a gas stream shows the processes only schematically and that the separation process depends on the size of the charge _s, the distance between the charged particle and the neutral surface, and ultimately also on the speed at which the charged particle moves on the surface moved past. Of course, a charged particle entrained by the gas flow can pass numerous drops of liquid or other surfaces before it is finally removed from the gas flow in the manner described above. It goes without saying that the probability with which a particle is drawn out of the gas flow under the effect of the force of attraction ₉ is greater, the greater the number of collecting surfaces present in the gas path between inlet and outlet. The fan or other gas feed device is operated so that the gas stream in the contact zone has such a low velocity _v that the probability of removal of the particles is increased under the effect of the attractive forces. With a washer or a trickle tower or the like. of the type described above, in which the gas stream flows transversely through the contact zone, is preferably carried out with a scrubbing liquid throughput of approximately 4850 to 58 * 250 kg / h · m packing area, measured transversely to the gas flow direction, and preferably with a gas velocity of approximately 0.3 to 3 »0 m / sec worked«,

- 34 309807/1174

The extraordinarily high effectiveness of the gas cleaning according to the invention can be proven by experiments. In the experiments carried out, a gas laden with foreign matter particles was passed through a liquid contact zone of a scrubber of the type described above, but which, apart from the packing in the unhumidified dehumidification zone, which prevents the mist from passing through the contact zone outlet, contained no packing. Particles of 50% dioctyl phthalate and > 0% kerosene were generated and introduced into the gas stream. The particle size was less than 0.1 micron. The core loading at the scrubber outlet was measured using a cascade type Andersen sampler. The gas passage rate was 56.6 m / min and the gas velocity through the contact zone was 2.1 m / sec. Water was used as the washing liquid,

ο which the contact zone in an amount of 19 * 995 kg / h * m Contact zone - measured transversely to the direction of flow of the water - flowed through. The voltage of the ionizer was 21 kV and the current was 15 mA. The total core exposure with the ionization device switched off, measurements were taken at about 0.3 cores per m, while with the Ionizer was about 0.148 per meter. When using the ionization device, the Particle separation effect in wet washing by about 51 ^ elevated. The table below shows the results this experiment is given for the different particle sizes:

3 0 9807/1174 " ^ ~

Test results in different particle size ranges

Size range
the particle
(in microns) Core loading
at the inlet
(Cores / m ^) Core loading
at the outlet
(Cores / m?) Divorce s-
efficiency
(in ⁰ zo) 0 - 0.1 0.162 0.081 50 0.1-0.3 0.081 0.038 52 0.3 - 1.0 0.017 0.014 20th 1.0-2.0 0.021 0.007 67 2.0-3.3 0.017 0.007 60 All in all 0.298 0.147 51

Further experiments were carried out using the apparatus described above in accordance with the preferred embodiment. These tests were carried out with a horizontal flow washer with a normal gas throughput of 56.6 mVmin. The device for generation of the foreign particles was formed ₉ on the one hand could be Kerοsinteilchen prepared and on the other hand from a mixture of kerosene and dioctyl existing particles in different size ranges, including a particle size below 0.1 microns »samples of the outlet of the scrubber leaving purified gas were a sampler of the aforementioned type together with a Gellman type "A" filter with glass filter paper (98.7% v / effective above 0.025 microns). When carrying out the tests, constant conditions were

807/117 ^

genes were maintained and tests were taken both with the ionization device switched on and with the ionization device switched off. The tests showed that the proportion of foreign matter particle emissions at the outlet of the scrubber can be increased by 70 to 85% by switching on the ionization device compared to the ionization device switched off. The efficiency of particle removal is; apparently independent of the particle size. The results show relatively equal effectiveness in the areas below 0.1 microns, from 0.3-1 / 0 microns, from 1.0-2.0 microns, and 2-3.3 microns. As noted above, the scrubber typically removes about 100% of the foreign matter particles above the latter
Size. The following values were obtained in the tests:

Particulate matter

Total airflow

Air conditioning
(Amount of passage, each

m ² h)

Bulking pack

Test A

Kerosene

56.6 m ^ / min

Test B

50% kerosene

50% dioctyl phthalate

56.6 m ^ / min

kg / nr · h 9060 kg / m ^£

Inch normal ^{size '1} TELLEEET-TES "

Depth of the pack in

Direction of air flow 60.9 cm

Air speed through ionizing device and

Washer 21;), 3 cm / sec

1 inch normal size "^{'I 1 EIjLEIiETTES"}

60.9 cm

213.3 cm / sec

3 i) 9807/1174

- 37 -

read A

Test B

Water impact ring of the scrubber

19,595 kg / m »h

Particle loading of the ^

Air at the väscher outlet 1.24 cores / no ( without electrostatic charge)

Particle loading of,

Air at the väscher outlet 0.197 cores / m ( with electrostatic particle charge)

% Reduction in emissions with electr. Parti- 84% charge

% Reduction in emissions with electr. Particle Charge in Different Particle size ranges:

2.0-3.3 microns 1.0-2.0 microns 0.3-1.0 microns 0.1-0.3 microns below 0.1

80% 92%. 74% 77%

(not measured)

19,595 kg / nr.h 12.0 cores / m ⁵

0.17 cores / m ^ 85%

(Particles in these sizes not created)

71% 92% 87%

Additional tests were carried out with regard to the effectiveness of gas cleaning on gases from an aluminum reduction device with so-called ^l! Soderberg "crucibles. The contaminant particles in the exhaust gases from this facility consisted of alumina, cryolite, carbon and hydrocarbons in the form of tar. The gases were pre-cleaned by being passed through spray towers to remove the large contaminant particles

- 38 -

309807/1174

the gases passed through a wet cleaner of the type described here provided with a packing compound. The gas flowed through a bed of "TELLERET-TES" packings with a nominal size of 25.4 mm, the depth of the Packed bed in the direction of gas flow was 60.9 cm. The gas velocity through the ionizer and the scrubber was 121.8 cm / secj the total amount of gas 31.15 m / min. The gas throughput amounted to

5144 kg / h m. The washing liquid was water in βίο A throughput of 19 * 595 kg / m · h is used. The ionization system had a wire-to-rod spacing of 50.8 mm; the ionization voltage was 34 kV, the current intensity 6.2 mA. Samples were taken with the aid of the sampler mentioned above. It was determined by measurement that the gas flow foreign matter particles below 5 »5 microns contained in a proportion of 89%. In the size range below 5 »5 microns, the inlet core loading was approximately 0.94 cores per nr and the outlet core loading about 0.14 Cores per m. The efficiency of particle separation in the The area below 5 »5 microns was therefore about 85%. The table below shows the results for the various measured particle sizes indicated:

Test results. in different particle size ranges

309807/1174

Core loading
at the inlet
(Cores / m ^) Core loading
at the outlet
(Cores / mr) 2235531 Size range
the particle
(in microns) O ₅ 180 0.060 Deposition
efficiency
(in %) 0 - 0.1 0.222 O _s O38 67 0.1-0.3 0.190 0.024 83 0.3 - 1.0 0.236 0.017 87 1.0-2.0 0.077 O ₉ OOO 92 2.0-5.3 0.055 0 gOOO 100 5.3-5.5 100.

All in all

O ₉ 940

0.139

85%

The results of the above test are compared with the results of a basic experiment with deactivated, loni si augmentation SVO rri chttmg 'particularly significant In the basic experiment the total Gasdurehflußmenge was 58 ₉ 8 m / min at a gas velocity of 2 _f 04 m / sec _o the kill body bed consisted of 25.4 mm "TELLESETTEB" with a bed depth of 122 cm in a gas flow direction _o water was used as washing liquid in a flow rate of 19 »595 kg / m ° h. The samples were taken using the Andersen sampler mentioned above. The total inlet core loading was found to be 0.38 cores per Br and the total outlet core loading was 0.03 cores per Br. The overall efficiency was about 10,

The scrubber or scrubbers _$ of the methods of the invention in which and the apparatus of the invention uses

3 0 9 8.0 7/1 1 7 h

is, preferably has a contact zone with a Packing mass is filled with irregular packing distribution. However, the invention can be used in the same way with cleaning devices that work with low energy requirements, in which the contact zone has other static surface elements instead of the filler bodies. For example, the wet cleaner can only have such surfaces as the wall surfaces surrounding the contact zone and / or from splash plates, guide plates, drip and 'Rieselplatt en and the like. In the case of a cleaner provided with a packed bed, the porous mass also from other packing elements including a coherent packing mass from a wire or Thread mix or the like. exist. As a packing can different elements, such as balls, stacked packing pieces, corrugated packing elements of the modular type and the like., Use saddle elements, ring elements and the like. Although it is advisable to absolutely ground the quilts, for example to keep neutral to prevent particle accumulation by the forces of attraction to effect, the surfaces can also have a negligibly small charge or a charge with have opposite polarity to the particle charge. The gas flow and the liquid flow through the wet cleaners can be aligned or, as described above, set at an angle to one another. It is also possible to work in countercurrent. Furthermore

30 9 807/1 1 7 A

- ■■■ "■ - 41 -

there is the possibility of using the device described above with two or more successively connected stages to provide an even higher separation efficiency to achieve. When using random packings,. the packing volume adapted to the size of the contact zone j the packing depth in the direction of the gas flow can be changed, in order to be able to adjust the depth to the best possible value.

An increase in the packing volume and the packing depth is of course with an increase in the available areas within the contact zone and thus with associated with an increase in the separation effect. Using of coiled single-body elements of the type described above (Fig. 5) is the number of existing ones Areas practically indeterminable, since around 1000 25 »4 are now filler elements are required in unregulated distribution to fill a contact zone space of 28.3 dm.

309807/1 17

Claims (3)

Expectations ίΐ, ϊ device for removing foreign matter particles and the like. from a gas stream with a liquid-gas contact zone through which the gas stream flows, in which the with the Particle-laden gas stream in intimate contact with a flowing through the contact zone with a large surface Liquid passes, characterized in that in the direction of flow of the gas in front of the contact zone Device (12) is arranged for electrically charging the particles entrained by the gas stream, and that a device for achieving an attractive force acting between the liquid surface and the particles (10J) is provided with which the liquid is electrically is kept neutral. 2. Device according to claim 1, characterized by a device for adjusting the gas passage speed through the contact zone. 3. Device according to claim 1 or 2, characterized in that the gas passage speed in the contact zone is approximately 0.6 to 10.7 m / sec, preferably about 0.3 to 3 »0 m / sec. 4. Device according to one of claims 1 to 3, characterized characterized in that in the contact zone standing in contact with the gas and the liquid surface are static Surface elements (26) are arranged. 309807/117 4-4; - 5. Device according to claim 4, characterized in that that the surface elements consist of a gas-permeable mass, preferably a filler material (26). 6. Device according to one of claims 1 to 5? characterized in that the liquid is the permeable mass in an amount of 4880 to 488,000 kg / h - m ² , preferably about 4880 to 58,600 kg / h · m, measured transverse to the direction of flow of the liquid, flows through " 7. Device according to one of claims 1 to 6, characterized characterized in that the liquid and gas inlet so are arranged that the liquid is the contact zone or the permeable mass flows through opposite or transversely to the gas flow. 8. Device according to claim 7 »characterized in that the liquid flows through the contact zone from top to bottom, while the gas flows through the contact zone transversely to the direction of the liquid flows through at a speed of preferably about 60 mm to 10.7 m / sec. 9. Device according to one of claims 1 to 8 _S, characterized in that the device (12) for electrically charging the particles entrained by the gas stream is arranged at the gas inlet of the contact zone. 10. Device according to one of claims 1 to 9, characterized in that 3 (J H 8 0 7/1 1 7 _ ιμ \. _ indicates that the device forming the contact zone (10) and the device (12) for electrically charging the particles entrained by the gas stream a Βγλιeinheit are connected. 11. Device according to one of claims 5 to 10, characterized characterized in that the Püllkörperelemente (26) from one dielectric material. 12. Method for removing foreign matter particles from a Gas flow by placing the gas flow in a liquid-gas contact zone is washed, characterized in that the particles entrained in the gas stream are electrically charged v / earth and the gas flow with one electrical neutral washing liquid is washed, the flow rate of the gas in the contact zone is set so low that the electrically charged particles due to the attraction of the Finely distributed liquid is attracted against the drag force of the gas flow. Y'j. Process according to Claim 12, characterized in that the gas stream and the liquid are passed through the contact zone in different directions. .Vy. Method according to claim 12 or 1;>, characterized in that that the gas velocity in the contact zone is adjusted to about 60 mm to 11 m / sec. - 45 309807/1174 15. The method of claim 1>^; , characterized in that the liquid flows through the Koiibakbzone under the action of gravity from top to bottom, while that gas flows through at an angle to the vertical dLo Konbaktzone. 16. The method according to any one of claims 12 to 15> characterized in that as a contact zone elements with large Surface, especially a filler material, can be used. 17- The method according to any one of claims 12 to 16, characterized characterized in that the liquid the Kontnktaone in a Henge of 4880 to 488,000 kg / h * m ~, preferably about 4880 to 58.600 kg / h * m, measured transversely to the direction of flow of the liquid, flows through. 3 0 ^c ) 8 0 7 7 1 1 7 Λ BAD ORIQIKAi. Le e rs ei \ e