US 2970670 A
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Description (OCR text may contain errors)
Feb; 7, 1961 K. M. NODOLF 2,970,670
FLUID CLEANING APPARATUS Filed Aug. 6, 1958 30 GAS FLOW w, 35
KEITH M. NODOLF ATTORNEY F 7 4 INVENTOR.
United States Patent FLUID CLEANIN G APPARATUS Keith M. Nodolf, Minneapolis, Minn, assignorto Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Filed Aug. 6, 1958, Ser. No. 753,472
2 Claims. (Cl. 183-7) The present invention is concerned with an improvement in electrostatic gas cleaning apparatus. The improvement is in the use of sheets or plates of material for the collecting unit which are made of an insulating material coated on both sides with a conductive material. The coatings on opposite sides are connected to the opposite sides of a source of power.
The use of an insulating material coated to produce a conductive surface on a plate for an electrostatic air cleaner is old; however, the present invention recognizes the particular advantages obtained in using a plate or sheet of material which is coated with a conductive coating on opposite sides and the coatings are connected to opposite sides of a source of power. The conductive coating on one side of the insulating sheet is positive and the conductive coating on the other side is negative. This particular improvement makes the use of coated materials more adaptable for collecting surfaces in electrostatic air cleaners; in particular, when the coated plates are used in a parallel plate collector unit, the desired plate spacing can be attained with the adjacent surfaces of the plates oppositely charged.
It is therefore an object of the present invention to provide an improvement for electrostatic gas cleaning apparatus.
And still another object of the present invention is to provide in an electrostatic gas cleaning apparatus an improved collector surface made up of an insulating material coated on both sides with the coatings oppositely charged.
These and other objects of the present invention will become apparent upon a study of the following specification in which:
Figure l is a schematic representation of an electrostatic gas cleaning apparatus using the improved collector unit;
Figure 2 is a cross-sectional view of the collector unit of the apparatus shown in Figure 1 having the collector plate wrapped in a spiral form;
Figure 3 is a cross-sectional view of one portion of a typical sheet or plate material having the insulating portion which is coated on opposite sides with a conductive coating; and
Figure 4 is another embodiment of the present invention using the plates having the oppositely charged coating in a parallel plate collector unit.
Other objects of the present invention will become apparent upon a study of the following specification and claims.
Referring to Figure 1, an electrostatic A gas circulating means or fan i forces the gas through the cleaning apparatus. The gas cleaning apparatus comprises an ionization section 1'1 shown to the left of the unit and a collecting unit 12 j shown to the right. The ionization unit comprises the outer ground plates 13 and the spaced ground plates 14 which have parallel positively charged ionization Wires 15 which are strung between the plates in a conventional v lecting unit of Figure 2, surface 24 2,970,676 Patented Feb. 7, 1961 manner. As the gas passes through the ionization unit, the foreign material inthe gas is charged with an electrostatic charge. The collector unit is made up of portions of parallel plates which are oppositely charged, and the charged particles are attracted and collected on the plates.
Referring to Figure 2, a cross-sectional view of the collector unit 12 is shown. The grounded frame 20 has a number of rods 21 on which a composite sheet or plate material 22 is strung in a spiral form to form portions or sections of material 22 which are substantially parallel to other portions or sections. The plate material 22 is spaced from adjacent portions so that air can pass crosswise of the plate material between the adjacent portions. In Figure 2, the air flow is out of the drawing toward the observer.
The composite plate material 22 is shown in more detail in Figure 3. A small portion is blown up to show the insulating center material 23 which is coated on opposite sides by a conductive coating 24 and 25. Obviously the coating would not extend to the edge of the plate or sheet 23; so that, the conductive coatings on opposite sides were electrically insulated when connected to opposite sides of a power source as shown. In the colis contacting the rods 21 of the grounded frame and is connected to ground. Surface 25' is connected to the positive source; therefore, the adjacent plates have oppositely charged surfaces, and a voltage gradient exists across the gap'between the plates.
Another embodiment using the present invention is shown in Figure 4. A parallel plate gas cleaner is shown having three grounded plates 30 which extend throughout the ionization section 31 and the collecting section 32. Between the grounded plates in the ionization section are wires 33 which are connected to a positive source of power to form the conventional ionizer. The collecting section 32 is made up of a centered conductive plate 34 which is connected to a positive source and positioned in line with the ionization. wire 33. Between the positive plate 34 and the ground plates are placed a composite plate 35 made up of the center insulated section 40 and the conductive coatings 41 and 42 on opposite sides thereof. The coatings are connected to opposite sides of the source of power. In the collecting unit, the alternate plates have surfaces to provide a voltage gradient across a space between the plates- The embodiment shown in Figure 4 has several advantages over the conventional type of gas cleaning apparatus. As it is continually desired to keep the current drain of the collector unit at a minimum, the plate spacing is critical. At the same time, it is desired to have the center plate of each section of the collector unit which is in line with the ionization wire in the ionization section at a positive potential to prevent creating unusable current flow to the ionizer. The present invention provides for such an arrangement by making use of the composite plate between the center positively charged plate and the outer negatively charged plate. The use of an insulating plate coated on opposite sides so that the opposite side coatings can be connected to opposite sides of a source of power assists in the selection of the plate spacing between the adjacent plates in the collector unit to obtain the desired efiiciency in the collecting unit. The plate spacing determines current drain and efficiency of the unit, and generally to meet field requirements, such as Underwriters, some optimum plate spacing is used. The plate spacing is selected to obtain the right current consumption and yet have a reasonably high eficiency in the cleaning of the gas.
While the'present invention has been shown in selected embodiments, it is obvious that the scope of the invention 3 should only be limited by the appended claims, in which I claim:
1. In a gas cleaning apparatus, an ionization unit for charging particles of foreign material contained in the gas, a particlecollecting unit for collecting said charged particles to remove said particles from the gas, and circulating means for moving the gas first through said ionization unit and then through said collecting unit, said collecting unit comprising; a plurality of parallel plates, a source of power having two output terminals with a voltage difference between them, means supporting said plates in spaced relationship so that gas is free to flow parallel thereto with no gas flow restriction by said last mentioned means, at least one of said plates being made up of an insulating plate having a conductive layer attached on both sides, and means for electrically connecting all of said plates and said layers on opposite sides of said one plate to said terminals of said source of power whereby a voltage difference exists between said layers on opposite sides of said plate.
2. In an electrostatic air cleaning apparatus for cleaning air passing therethrough, an ionization section for charging foreign particles contained in the air, and a collection section comprising, a strip of thin insulating material, said material being covered on opposite sides with a conductive material, said insulating material and said conductive material forming an integral strip, means for wrapping said strip in a spiral form whereby adjacent sides of said strip are substantially parallel and spaced so air flows unrestricted between said strip, a source of power having a high voltage terminal and a ground, and means connecting one of said conductive sides to said terminal and the other conductive side of said ground so that adjacent surfaces of said strip are at a different voltage and a voltage gradient exists across the space between adjacent strips.
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