Electrode elements of high resistivity for two-step electrofilter

Abstract

A device comprising a group of electrode elements for a condenser separator of a two-step electrofilter, which group of electrode elements comprises at least two electrode elements in the form of strips or flat planar sheets, the electrode elements being mostly comprised of a core. At least one of the electrode elements or group of electrode elements is formed of at least two different polymers with different electrical properties. A first portion of the electrode element that is disposed closest to an adjacent second electrode element in the condenser separator is formed of an insulating polymer, and a second portion of the electrode element is comprised of at least one current conductive element in the form of a thin coating on the core of the electrode element, or is embedded in the core.

Claims

1. A device comprising a group of electrode elements for a condenser separator of a two-step electrofilter, the group of electrode elements comprises at least two electrode elements, each consisting of two different polymers, wherein: a. the electrode elements are provided in the form of strips or groups of flat sheets, b. the electrode elements include a core constituting a majority of each of the electrode elements, c. at least one current conductive element is provided on a first side of each of the electrode elements either in the form of a polymer coated on the core of the electrode elements, or embedded in the core, wherein the at least one current conductive element extends the entire length of the first side of each of the electrode elements, d. the at least one current conductive element has smaller dimensions in width and depth than corresponding dimensions of the core in width and depth, e. a first portion of a back side of each of the electrode elements that is opposite to the first side of each of the electrode elements and arranged closer to an adjacent one of the electrode elements is formed of an insulating polymer, f. a second portion of the electrode elements comprises at least one said current conductive element, g. the electrode elements are offset with respect to each other in such a way that no two adjacent electrode elements have the current conductive element located at a same corresponding position, and h. the current conductive element on the first side of each of the first electrode elements is located at a first distance from a first edge of the respective electrode element and farther away than the first distance from a second edge of the respective electrode element, and the current conductive element on the adjacent one of the second electrode elements is located at the first distance from the second edge of the respective electrode element and farther away than the first distance from the first edge of the respective electrode element.

2. The device according to claim 1, wherein an insulation layer encloses edge sections of the electrode elements.

3. The device according to claim 1, wherein several of the current conductive elements are offset with respect to each other and perpendicular to air flow direction through the condenser separator.

4. The device according to claim 3, wherein several separate connections to a high voltage source are provided by an edge connection of respective current conductive elements by means of a conductive material.

5. The device according to claim I, wherein the core of the electrode elements is thinner than 0.7 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a first embodiment of the present invention. FIG. 2 shows a second embodiment of the present invention, in which the electrode elements are coated on at least one side with a thin film of insulating polymer.

(2) FIG. 3 shows a third embodiment of the present invention, in which a thin film of insulating polymer surrounds the entirety of each of the electrode elements.

(3) FIG. 4 shows a modification of the present invention, in which the electrode elements each include a plurality of current conductive elements.

DETAILED DESCRIPTION

(4) As shown in FIG. 1, the electrode elements A, B in the form of thin strips consisting of two polymers are assembled with each other during the manufacturing process.

(5) A major layer consists of a thin core M1 of a polymer of high ohmic resistance and with a surface resistivity that is greater than 1×10.sup.10 ohm/sq or a volume resistivity that is greater than 1×10.sup.9, and preferably with a surface resistivity that is greater than 1×10.sup.12 ohm/sq or a volume resistivity that is greater than 1×10.sup.11.

(6) At least one current conductive element M2 of a conductive polymer extends to one edge section of the core M1, with an extension that is substantially smaller than the extension of the core M1 with respect to both the width and the thickness. In the shown embodiment, the current conductive elements M2 run along the whole length of the electrode element A, B, on one side of said electrode element.

(7) The surface resistivity of the current conductive elements M2 is preferably less than 1×10.sup.8 ohm/sq or their volume resistivity should be less than 1×10.sup.7 ohm-cm and preferably less than 1×10.sup.5 ohm/sq and 1×10.sup.4 ohm-cm, respectively.

(8) If two electrode elements in a condenser separator are designed in accordance with the present invention, these should advantageously be mirror images of one another, i.e. the current conductive elements M2 in the respective electrode elements A, B should be arranged at opposite edge sections. I.e. if a current conductive element M2 on a first side of a first electrode element A is located at a first distance from the first edge of the electrode element A and thus clearly farther away from the second edge of the electrode element A, then a current conductive element M2 on an adjacent second electrode element B should advantageously be located at said first distance from the second edge of the electrode element B and hence clearly farther away from the first edge of the electrode element B.

(9) FIG. 2 shows a modified embodiment of the invention wherein the respective electrode elements A, B, at least on one side thereof, are coated with a thin film of insulating polymer M3′, i.e. a polymer with higher surface resistivity than 1×10.sup.12 ohm/sq and at least 10 times as high surface resistivity (or volume resistivity) as the resistivity of the core M1.

(10) Preferably, the back side of the electrode elements A, B are coated with said thin film of insulating polymer M3′, the back side being the side electrode elements A, B which are not coated with current conductive elements M2.

(11) FIG. 3 shows yet another modified embodiment of the embodiment shown in FIG. 2.

(12) In this embodiment, an insulating polymer M3 is arranged to enclose the entire electrode elements A or B, one of them or both, including its edge sections and including the current conductive elements M2.

(13) Possible Modifications

(14) Of course, it is not necessary that the electrode elements A, B have the shape of long strip-like elements. As illustrated in FIG. 4, the elements A, B may be in the form of rectangular/square sheets consisting of the core M1 and preferably several current conductive elements M2′, M2″ arranged at a distance from each other and embedded in the core or arranged as a thin coating on the core M1. FIG. 4 schematically shows flat electrode elements A, B with several current conductive elements M2′ and M2″.

(15) In the embodiment shown in FIG. 4 the current conductive elements M2, M2′, M2″ are all arranged at the same corresponding side. However, the present invention is not limited to current conductive elements M2, M2′, M2″ provided only on one side of core M1. Current conductive elements M2, M2′, M2″ may very well be provided on both sides of the core M1.

(16) With several current conductive elements (coatings) M2, M2′, M2″, several individual high voltage connections can be arranged, which is of particular importance when the electrode elements in question are flat electrode elements arranged with a gap with respect to each other in a condenser separator with a square or rectangular inlet area. In such an embodiment, the current conductive elements M2, M2′, M2″ should preferably be arranged perpendicular to the air flow direction L through the condenser separator, as shown in FIG. 4.

(17) With a mutual displacement of the current conductive elements on the closest electrode elements A, B, the respective groups of the electrode elements A, B can be connected to different poles of the high-voltage source, preferably with an edge connection formed of a conductive material such as conductive rubber, conductive foam plastic, conductive hot-melt adhesive or the like.

(18) For example, the current conductive coating M2, M2′, M2″ may be Polypropylene specified as PP 1379 with a volume resistivity of less than 1×10.sup.3 ohm-cm and a surface resistivity of less than 1×10.sup.4 ohm/sq.

(19) The core M1 can, for example, be formed of polypropylene with a volume resistivity that is preferably greater than 1×10.sup.10 ohm-cm.