Electric dust collector
United States Patent [191 Nomura et al.  
 [451 Apr. 15, 1975 1 ELECTRIC DUST COLLECTOR [75] Inventors: Tsutomu Nomura, Kamakura;  
 Masakazu Sakai, Hiratsuka, both of Japan [73] Assignee: Sumitomo Shipbuilding &amp;  
 Machinery Co., Ltd., Tokyo, Japan [22] Filed: Sept. 5, 1973 [21] Appl. No.: 394,612  
 [52] US. Cl. 55/122; 55/126; 55/128;  
  55/155; 266/15 [51] Int. Cl. B03c 3/16 [58] Field of Search 55/122, 124, 126, 128,  
 2,979,158 4/1961 Vlier, Jr 55/126 X 3,064,409 ll/l962 Schmitt 55/124 X 3,248,857 5/1966 Weindcl et 81 55/118 3,421,290 1/1969 Cheney et a1..... 52/6 X 3,513,635 5/1970 Eishold et 55/157 X 3,618,659 l1/l971 Rawl 165/59 X 3,672,126 6/1972 Goettlc 261/116 X 3,765,154 10/1973 Hardt et a1 161/164 X FOREIGN PATENTS OR APPLICATIONS 1,019,617 2/1966 United Kingdom 55/126 1,037,701 5/1953 France 55/126 463,717 8/1928 Germany 55/133 509,404 10/1930 Germany 55/128 562,890 10/1932 Germany 55/129 140,696 9/1930 Switzerland 55/125 Primary ExaminerBernard Nozick Attorney, Agent, or FirmSughrue, Rothwell, Mion, Zinn and Macpeak [57] I ABSTRACT An electrostatic precipitator to be provided directly on the roof or top of the factory building, which is made light-weight by making the dust collecting electrodes with light-weight materials, such as polyvinyl chloride, fiber reinforced plastics, or the like synthetic resin, aluminum treated to have the corrosion resistance, duralmin, or the like light metals.  
 3 Claims, 6 Drawing Figures M NTEUAPR 1 5 I975 SHEET 2 0f 2 J J N ELECTRIC DUST COLLECTOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electrostatic precipitator, and more particularly to an electrostatic precipitator to be used for various types of factories including, for example, basic oxygen furnace, open hearth furnace, electric furnace, electrolytic furnace, casting and molding plants, casting bed for the blast furnace, wood working machines and bread making machines.  
 2. Description of the Prior Art It is the usual practice to provide the precipitator on a factory building to clean the waste gas from the building which may house a basic oxygen furnace, an open hearth furnace, an electrolytic furnace, molding and casting plants, or a casting bed for a blast furnace.  
  The electrostatic precipitator is the most advantageous among various types of dust collectors in view of the efficiency to collect even the finest dusts, the investing and running costs and the capacity to deal with the dusts.  
  The conventional electrostatic precipitator is provided isolated from the factory building, and the waste gas is sucked from the building through a flue duct, which connects the latter with the precipitator, by a large capacity blower, as shown in FIG. 1. Accordingly, the provision of the large sized flue duct and blower requires much cost and space, and the blower generates noise and vibration.  
  On the other hand, the fluorine gas generated from an aluminum electrolyzing factory is removed by spraying fluorine gas absorber (e.g. sodium hydroxide solution) through spraying nozzles provided on the upper zone of the factory building. In such a case, the mist of the fluorine gas unremoved is dispersed in and pollutes the atmospheric air.  
 SUMMARY OF THE INVENTION An object of this invention is to provide an improved precipitator for removing the dusts generated from, for example the converter, open hearth furnace, electric furnace, and molding and casting plants.  
  Another object of this invention is to provide an improved precipitator for sucking and removing the injurious gas generating from an aluminum electrolyzing furnace.  
  We, the inventors, have discovered that the waste gas in the factory building flows through the vent hole provided on the upper part of the building with a flow rate of 2-3 m/sec (in rare case, the flow rate reaches to 5 m/sec), even if an exhausting fan is not provided. We have hit upon a plan for providing an electrostatic precipitator on the upper part of the factory building on the basis of this discovery.  
  The usual electrostatic precipitator, however, is made from iron and accordingly too heavy to mount on the building (especially an existing building). The total weight of the electrostatic precipitator is composed of about 50 percent of outer shell, about 5 percent of discharging electrode and about 45 percent of dust collecting electrode.  
  According to this invention, the dust collecting electrode, which occupies about 45 percent of the total weight of the precipitator, is made from hard polyvinyl chloride (P.V.C), fiber reinforced plastic (F.R.P) or the like synthetic resin, aluminum, duralmin or the like conductive light metal. The specific weight of the P.V.C. or F.R.P. is about 1.4-1.5, while that of iron is 7.85, so that weight of the dust collecting electrode made from the P.V.C. or F.R.P. is reduced down to l/5.6 l/5.2 of that made from iron. As a result, the load to be applied on the outer shell of the precipitator is decreased to reduce also much of the weight of the outer shell which supports the dust collecting electrode. If spraying means for spraying the gas absorber solution is additionally provided below the electrostatic precipitator, which is mounted on the upper part of the factory building, the dusts and the injurious gases generated from the converter, open hearth furnace and electric furnace are converted into the mists which will be fully caught and removed by the upper precipitator. Accordingly, the injurious gases and dusts generated from the factory building can be removed effectively by providing a light weight electrostatic precipitator according to this invention on the upper part of the building without using an exhaust fan or blower.  
  These and other objects and advantages of this invention may be readily ascertained by referring to the following description and appended drawings.  
 BRIEF EXPLANATION OF THE DRAWINGS FIG. 1 is a schematic view of the conventional electrostatic precipitator plant, and  
  FIGS. 2, 3, 4, S and 6 are various examples of the electrostatic precipitator of this invention applied on the upper part of the factory building wherein arrows indicate the directions of gas flow.  
 PREFERRED EMBODIMENTS OF THE INVENTION Referring to the FIG. 2, a vertical flow type electrostatic precipitator 2 is provided on an upper part of a vent hole 5. A louver 6 is provided on the vent hole 5 to direct the flow of the waste gas and to prevent the washing water from flowing into the work shop through the vent hole 5. The electrostatic precipitator 2 is composed of an outer shell 7 attached to a roof 1 of the building, pluralities of dust collecting electrodes 8, and a series of discharging electrodes 9 which are arranged in regular intervals, assembled into a frame work and inserted between the neighboring two dust collecting electrodes.  
  In a case that the dust collecting electrode 8 is made from the synthetic resin and used in the dried state, the electrode must be made conductive by coating the surface with the carbonaceous material or by adding the latter preliminarily to the synthetic resin. In order to introduce the waste gas into the vent hole 5 as the constant flow, a small fan (not shown) for adjusting the pressure difference between the atmospheric pressure and the pressure in the factory building may be provided on the vent hole 5.  
  If washing nozzles 10 are provided on the louvers 6 and around the vent hole 5 to prevent the after scattering of the dusts heaped on the louvers 6, and the dusts are discharged by the washing liquid from the louvers 6 through the roof 1 of the building, the provision of a hopper for collecting the dusts can be omitted.  
  Referring to the FIG. 3, the vertical flow type electrostatic precipitator 2 is provided on the side part of the vent hole 5. In such a case, pluralities of adjustable dampers 1 1, are provided at the inlet part of the precipitator 2 and adjustable in angle for directing flow towards the latter. The amount of the gas to be introduced into the precipitator is adjusted by these dampers l1, and the gas can be supplied uniformly on the whole surface of the dust collecting electrode 8. The gas outlet of the electrostatic precipitator 2 is preferably provided on the upper part thereof so as to retain the gas in the precipitator for a long period of time and thereby to increase the dust collecting efficiency. Referring to the FIG. 4, a horizontal flow type electrostatic precipitator 2 is provided on the vent hole 5, and pluralities of dampers 12 are provided at the gas outlet part as an adjustable in angle. The blowing of the wind and rain into the precipitator can be prevented by adjusting the angles of the dampers 12.  
  Referring to the FIG. 5, an electrostatic precipitator 2, in the case that the strength of the surrounding portion of the vent hole is not enough to support the electrostatic precipitator, is provided on the building roof 1 at a position a short distance from the vent hole 5, and the waste gas is introduced into the precipitator 2 by a guide member 13.  
  Referring to the FIG. 6, the electrostatic precipitator of this invention is applied on the roof of an aluminum electrolyzing factory building to remove the injurious gas. In such an example, a spraying pipe 14 for spraying a gas absorbing agent, such as an aqueous solution of sodium hydroxide, is provided between the electrostatic precipitator 2 and the louver 6.  
  The injurious gas (fluorine gas in this case) rising through the vent hole 5 is thus converted into a mist of uninjurious sodium fluoride solution and caught by the precipitator 2.  
  As particularly described above, since the lightweight electrostatic precipitator of this invention, whose dust collecting electrode is made from a synthetic resin or light metal, is directly provided on the upper part of the factory building, and the waste gas generated from the factory building is introduced into the precipitator as a natural flow, the provision of the flue duct and large sized exhaust fan usually required becomes unnecessary.  
  The synthetic resin used for the dust collecting electrode is preferably hard, but a soft synthetic resin or a composite sheet made from the hard and soft synthetic resins can be also applicable.  
 What is claimed is:  
  1. An electrostatic precipitator overlying a vent hole within the roof of a factory building, said precipitator comprising:  
 an open ended outer shell extending upwardly fro said roof and surrounding said vent hole for effecting flow of air from said building through said shell by the thermal buoyancy of said air,  
 a plurality of laterally spaced, vertical dust collecting electrodes within said shell,  
 a series of vertical, discharging electrodes corresponding to said collecting electrodes arranged at regular intervals, and interleaved between said collecting electrodes and being connected to an electric power supply,  
 said dust collecting electrodes being in planar sheet form and formed of light weight material,  
 and sets of vertically spaced louvers positioned beneath said electrodes with said louvers being inclined outwardly and downwardly toward respective side walls of said shell relative to the center line of the precipitator in order to prevent the washing water from flowing into the work shop through the vent hole.  
  2. An electrostatic precipitator overlying a vent hole within the roof of a factory building, said precipitator comprising:  
 an open ended outer shell extending upwardly from said roof and surrounding said vent hole for effecting flow of air from said building through said shell by the thermal buoyancy of said air,  
 a plurality of laterally spaced, vertical dust collecting electrodes within said shell,  
 a series of vertical, discharging electrodes corresponding to said collecting electrodes arranged at regular intervals, and interleaved between said collecting electrodes and being connected to an electric power supply,  
 said dust collecting electrodes being in planar sheet form and formed of light weight material,  
 said collecting electrodes being formed of synthetic resin sheets having carbonaceous conductive material at least on the surfaces thereof, and sets of vertically spaced louvers beneath said electrodes to respective sides thereof, with said louvers being inclined outwardly and downwardly towards opposed sidewalls of said shell relative to the center line of said precipitator.  
  3. An electrostatic precipitator overlying a vent hole within the roof of a factory building, said precipitator comprising:  
 an open ended outer shell extending upwardly from said roof and surrounding said vent hole for effecting flow of air from said building interior through said shell by the thermal buoyancy of said air,  
 a plurality of laterally spaced, vertical dust collecting electrodes within said shell,  
 a series of vertical, discharging electrodes corresponding to said collecting electrodes arranged at regular intervals, and interleaved between said collecting electrodes and being connected to an electric power supply,  
 said dust collecting electrodes being in planar sheet form and formed of synthetic resin having carbonaceous conductive material at least on the surfaces thereof,  
 a water supply positioned centrally within said shell and beneath saidelectrodes, and  
 sets of vertically spaced louvers positioned within said shell beneath said water spray, with said louvers being inclined outwardly and downwardly toward opposed sidewalls of said shell, and  
 collector means on the inner periphery of the shell bottom for removing water dripping from said louvers and the dust entrained therein.