WO1982000259A1

WO1982000259A1 - Electric filter

Info

Publication number: WO1982000259A1
Application number: PCT/FI1981/000053
Authority: WO
Inventors: A Artama; U Nurmi
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-07-15
Filing date: 1981-07-06
Publication date: 1982-02-04
Anticipated expiration: 1983-01-15
Also published as: FR2486823A1; ATA908781A; SE8204590L; FR2486823B1; NO157087B; DD206942A1; DE3152216C2; SE435140B; DE3152216T1; FI61815C; NL8120285A; NO157087C; FI802245A7; FI61815B; NO820783L; SE8204590D0; CS243462B2; GB2098509B; GB2098509A; DK109382A

Abstract

Un filtre electrique possede une chambre ou boitier (1), au travers duquel on envoie a l'aide d'un ventilateur (4) de l'air ou un autre gaz a epurer. Un dispositif d'ionisation est prevu pour le gaz a epurer, ce dispositif consistant en une ou plusieurs electrodes d'ionisation (9) et de contre-electrodes (10). Un champ electrostatique est forme par des electrodes positives et negatives (13, 14) dont les electrodes collectrices en forme de plaque (14) sont, au moins partiellement, en verre ou en un materiau correspondant et sur lesquelles les particules d'impuretes de l'air ou autre gaz a epurer, qui ont recues une charge par le dispositif d'ionisation, tendent a s'accumuler. Une pellicule d'eau s'ecoulant continuellement sur une plaque de verre ou autre materiau reagissant a l'eau de la meme maniere que le verre joue le role d'electrode collectrice (14). Ainsi, les particules solides et seches telles que les poussieres de quartz ou de carbone contenues dans le gaz a epurer sont transportees avec le film d'eau sans ricocher des electrodes lorsqu'elles echangent leur charge d'origine par une charge du meme signe que celui des electrodes collectrices. Dans le sens du bord superieur des plaques solides des electrodes collectrices (14) des organes de conduction de l'eau sont montes pour canaliser un courant d'eau sur la plaque, par exemple des tubes (15) ayant de petits trous ou des ouvertures longitudinales laissant passer un courant d'eau.An electric filter has a chamber or box (1), through which air or another gas to be purified is sent using a fan (4). An ionization device is provided for the gas to be purified, this device consisting of one or more ionization electrodes (9) and counter electrodes (10). An electrostatic field is formed by positive and negative electrodes (13, 14) of which the plate-shaped collecting electrodes (14) are, at least partially, made of glass or of a corresponding material and on which the particles of impurities of l air or other gas to be purified, which have received a charge by the ionization device, tend to accumulate. A film of water continuously flowing over a plate of glass or other water-reactive material in the same way that glass acts as a collecting electrode (14). Thus, solid and dry particles such as quartz or carbon dust contained in the gas to be purified are transported with the film of water without ricocheting electrodes when they exchange their original charge with a charge of the same sign as that of collecting electrodes. In the direction of the upper edge of the solid plates of the collecting electrodes (14) of the water conduction members are mounted to channel a stream of water on the plate, for example tubes (15) having small holes or openings longitudinal letting pass a stream of water.

Description

Electric filter

The object of the invention is a so-called electric filter, the purpose of which is to separate from air or other gas small solid particles by means of an electrostatic method known as such, and which is of such type as is specified more exactly in the introduction to patent claim 1.

In known electric filters particles attached to the collec tion plate are caused to drop to the bottom of the filter either by shaking the collection plate at specified time intervals or by rinsing down with water. They are then re moved from the base of the filter. Various drawbacks are however associated with this mode of operation. Thus some particles may adhere so firmly to the dry electrode that shaking at intervals or rinsing does not suffice to clean the electrode. This then requires interruption of the operation of the filter and special cleaning procedure.

Other particles, for example quartz dust and carbon dust, may bounce off the dry electrode when they exchange their original electric charge for that of the collection electrode. Continuous rinsing of the collection electrode may not be practicable due to complete coverage of the electrode not being attainable with moderate water consumption A layer of particles then gathers on the dry portions and causes a short circuit.

The purpose of the invention is to produce an electric filter from which the aforementioned drawbacks have been removed. In this continuous rinsing of the filter collection plate is carried out completely with comparatively low water consumption resulting in all types of solid particles over the whole electrode area being carried away by the flowing water film and removed with it from the electric field. The invention is characterized by the fact that the impure particle collection plates situated in the electrostatic field are made of glass or corresponding material which is wetted by water. In this way the rinsing water is caused to spread with great effectiveness over the surface of the plate and cover it completely yet in a thin layer. The water film thus acts as an electrode, since the glass does not conduct electricity. Because the rinsing takes place continuously, the dust particles do not come into contact with the plate, but are seized by the water film and immediately rinsed away from the electric field. The plates accordingly remain completely clean, and no separate cleansing measures are necessary. At the same time the danger of fire is removed which may appear in such environments in which the dust produced is flammable, as for example in wood processing industry, mills etc.

The invention is described in more detail in the following description in which with reference to the drawing a suitable embodiment of the invention is presented together with details and advantages of the invention.

In the accompanying drawings

Figure 1 shows diagrammatically the electric filter according to the invention seen from the side, partly sectioned, Figure 2 shows diagrammatically a horizontal cross-section of the electric filter along A-A in figure 1. The figure also shows a circuit diagram of the electrical connections,

Figure 3 shows diagrammatically a vertical cross—section of the electric filter along B-B in figure 1,

Figure 4 shows in part the ionisation electrodes enlarged of the electric filter. The electric filter shown in figures 1-4 includes a supporting case 1. The intake opening 2 for the air to be cleaned is at one end of the case and the output opening 3 for the cleaned air is at the opposite end. Associated with the output air opening is an electrically driven fan 4, which draws air in via the input opening 2 and then through the filter. The fan may also be placed together with the input opening, in which case it blows air through the filter. The case is also provided with an openable cover 5. through which the electrical equipment and other parts inside the case may be serviced. In the base part of the case there is further a sump 6, into which the filter rinsing water flows.

According to the invention near the input air opening of the case there is in the electric filter firstly an ionisation device, which ionises the air in a known manner. In the device is a group of positive ionisation electrodes in a construction known as such, which in this embodiment are attached to a rectangular supporting frame 7 for example to supporting heads 8 in the upper and lower frame members. The electrodes 9 are thick metal wire, for exampl tungsten wire. The other electrode group of the ionisation device is formed by the group 10 negative counter-electrod which are attached to another frame 11 between its upper and lower members in a vertical row with equal spacing. These electrodes 10 are materially thicker in cross-section made for example from stainless steel wire, which is coiled in the form of a helical spring (figures 2 and 4) . Both electrode groups are fitted so for example that they are situated in the same row parallel and at equal intervals, thinner electrodes alternating with thicker ones (figures 2 and 4) . The electrodes may naturally also be situated grouped in successive rows longitudinally along the filter. According to the invention the construction of the elec trodes is further special in that the said electrodes 10 are continuously rinsed with a water current so that charged dust particles possibly striking them do not remain attached but are washed off. The electrodes thus remain clean and the ionisation device functions without fault. For rinsing there is in the upper member of the electrode supporting frame 11 a water channel or pipe into holes (not shown in the figure) in the base of which the electrodes are placed, loosely fitting, so that water can run through the holes downwards onto the electrodes. In place of electrodes in the form of a helical spring there may also be used. some kind of corresponding thick metal braid, chain, or wire rope.

The air current from the above mentioned ionisation device goes to the filter electrostatic field, which is formed of a group of parallel plate electrodes 13 , 14 placed vertically relative to the direction of the air current. Of these each alternate plate 13 is connected to the positive pole of the voltage supply, and each other plate 14 to the negative. Solid particles acquiring a positive charge from the ionisation device travel to the negative collection electrode 14.

According to the invention the said negative collection plates 14 are made of glass or corresponding material.In addition according to the invention a continuous rinsing of them is arranged. Water comes to the collection plate 14 from parts such as the pipes 15 which are placed near to the upper edge of the plates and running in the same direction as the edge. In this embodiment small nozzle holes are made at equal intervals to the pipes 15, so that water jets are directed from the pipes 15 slantingly downwards to the side surfaces of the. said glass plates at their upper edge in the form of numerous fine sprays. Another possible embodiment is to arrange the water distribution to the glass plate through narrow downward directed apertures in the direction of length of the pipe 15. The water then spreads as a thin even film over the surface of the glass plate, so that ther remain no dry, unrinsed points which would weaken the cleansing ability of the filter.

The positive electrodes 13 on the other hand may be mad for example from stainless steel and do not need to be rinsed since the dust particles only accumulate on the collection electrode 14.

In practice the body of the device is earthed and the negative pole of the supply is connected to the earth lead, to which is also connected the negative electrodes 10 of the ionisation device and the pipes 15, which are therefore metal or contain conductive parts through which electricity is conducted to the rinsing water. The positive terminal of the supply is connected to the positive ionisation electrodes 1 of the ionisation device and similarly the plates forming the electrostatic field are connected to the positive plate electrodes 13.

Should the conductivity of the water not be sufficient, as is sometimes possible, water conductivity may be improved by the addition of some suitable salt. The rinsing water may be led directly to a drain together with the accumulated impurities. It may also be arrange in a closed circuit, in which the dust is separated fro the water by means of a suitable filter.

The constructional parts of the device, such as the ionisation device, the electrode groups and the electro static field electrodes etc. may be arranged so as to be easily removable and exchangeable in order to facilitate maintenance.

The embodiment of the device may vary within the patent claims.

Claims

Patent claims :

1. An electric filter, in which is a chamber or case (1), through which the air or other gas to be cleaned is directed by means of a fan (4), an ionisation device for the gas to be cleaned, the device consisting of one or several ionisation electrodes (9) and counter electrodes (10), and an electrostatic field formed by positive and negative electrodes (13, 14), of which the plate-like collector electrodes (14) are at least partly of glass or corresponding material and on which there tend to accumulate from the air or other gas to be cleaned the impurity particles which have received a charge from the ionisation device, c h a r a c t e r i z e d i n t h a t there acts as the collection electrodes (14) a water film continuously flowing over a plate made of glass or material reacting to water in the same fashion as glass, by means of which the dry and solid particles such as quartz or carbon dust contained in the gas to be cleaned are carried along with the water film without rebounding from the electrodes in exchanging their original charge for a charge with the same sign as that of the collection electrodes.

2. An electric filter according to patent claim 1 c h a r a c t e r i z e d i n t h a t in the direction of the upper edge of the solid plates of the collection electrodes (14) there are arranged for directi a water current to the plate water leading parts, for example pipes (15).

3. An electric filter according to patent claim 2, c h a r a c t e r i z e d i n t h a t small holes at equal intervals have been arranged to the pipes (15) the holes being directed towards the side surfaces of the upper edges of the plates.

4. An electric filter according to patent claim 2, c h a r a c t e r i z e d i n t h a t narrow downward directed apertures have been arranged to the pipe (15) in the direction of the length of the pipe, the apertures being directed towards the side surfaces of the upper edges of the plates.

5. An electric filter according to patent claims 1-2, c h a r a c t e r i z e d i n t h a t the said water pipes (15) and ionisation device counter electrodes (10) are both connected to the same pole of the supply voltage source.

6. An electric filter according to patent claims 1-2 and 5, c h a r a c t e r i z e d i n t h a t water is caused to flow continuously over"the counter electrodes (10) of the ionisation device in order to keep these electrodes clean.