Abstract:
An electrostatically charged rotating plate or cylinder is used to attract electrostatically charged particles in smoke to avoid pollution and improve the efficiency of the filtering process. The rotating plate is constantly cleaned from the ionized particles adhering to it and the particles so collected are removed without polluting the environment. This filtering system reduces capital and running costs compared with the present filtering systems.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention is in the field of civil engineering, particularly in the cleansing of smoke emissions from industrial plants. In particular, the invention assists in reducing harmful particle emissions from electricity generating utilities. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is well known that smoke and the microscopic particles found within the smoke are a major cause of air pollution. This pollution can be hazardous to health, especially to the elderly as well as bronchial and asthma sufferers. In order to minimize these hazards and dangers, legislation has been enacted forcing air polluting industries to actively find ways of minimizing air pollution to an acceptable level. 
         [0003]    Amongst the methods used are electrostatic filters which remove the microscopic particles found within the smoke. The smoke-laden air ejected by the turbines firstly passes across negatively-charged electrodes, the particles become ionized and then, as they pass the positively charged plates become attracted, like a magnet, to these plates and become deposited on them. The plates eventually become filled with the ionized particles and the efficiency of the absorption diminishes considerably and the filters then require periodic cleaning. This method is not very efficient as it requires a large number of plates. In addition, the present system of cleaning involves mechanical cleaning methods that are unsatisfactory as they use a large amount of energy to shake, or “rap,” the plates for cleaning. Another disadvantage of the currently used cleaning methods is that through this cleaning process, particles are released into the atmosphere, thus causing a considerable amount of pollution. It has been reported that power plants release into the atmosphere around 150 tons of particles per day, which is over 50,000 tons per year! In fact, the offices of the Environmental or Pollution Control Authorities sometimes require the electric company to obtain permission from them before carrying out the “cleaning” process of these plates. Present day units typically comprise many collection plates, with a very large surface area. 
         [0004]    Furthermore, the filters used in the state of the art apparatus cause a resistance to the flow of exhaust gases. This is a disadvantage as the uninterrupted flow of these gases increases the efficiency of the power plant as a whole. 
         [0005]    Present day units have a holed plate at the entrance to the filter system to cause the smoky air to be evenly distributed. This plate causes resistance to the airflow and some power plants install fans after the plate to increase the air flow. What is needed therefore is a system that cleans the collection plates without causing pollution, and a system where the plates are cleaned while in place and in use. What is further needed is that the space required for the collection plates in the emission chimneys be greatly reduced. Also needed is a filtering system that does not interfere with the flow of polluted air as it passes through the filtering system. 
         [0006]    For the above reasons and more, it can be seen that there will be considerable demand for this invention by the power generating industry and by environmentally conscious governments. 
       SUMMARY OF THE INVENTION 
       [0007]    It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention and are intended to provide an overview, or framework, for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operations of the invention. 
         [0008]    The new improved electrostatic filter of this invention employs the same basic principle as that used today. That is to say, the smoke-laden emission gas passes over negatively charged electrodes, the particles in the smoke become negatively ionized and are then attracted to the positively charged plates. This invention employs rotary plates which rotate at a speed close to that of the smoke-laden emission gas that passes by the said rotary plates. The smoke particles, having previously been ionized by a high voltage electrical charge, pass through the negatively charged electrodes and are attracted to and deposited on the positively charged rotating plates. The rotating plates can be of a smaller surface area than a fixed plate since it is constantly being cleaned and also because of the comparable speed of the rotating plates and the smoke. The rotating plate is contained partially within a closed box and thus the particles, after having been removed by a brush, will not be released back into the environment. The particles will instead be deposited at the bottom of a box where a collection hopper is located. 
         [0009]    An advantage of this invention is that this unit does not have to be taken out of service for cleaning, as it is constantly being cleaned. 
         [0010]    Another advantage of this invention is an improvement of the present filtering method, as it is so designed that there is negligible build-up of particles on the collection plates because they are being constantly cleaned. 
         [0011]    Additionally, the space required for such units with the equivalent filtering capacity is greatly reduced. 
         [0012]    This will allow for greater efficiency of smoke and particle cleansing. At the same time manufacturing costs are lowered because the unit is considerably smaller than present day units and running costs are greatly reduced. 
         [0013]    Furthermore, the cleaning process takes place while the gases are being emitted, thereby avoiding the need to house additional sets of plates or having to wait until the gases cease to flow from a particular emission tower or having to wait for environmental officers&#39; approval to clean the plates before carrying out the cleaning process. As a result of the constant cleaning process there is negligible spraying of carbon particles into the atmosphere. 
         [0014]    A further way of removing carbon particles from the ionized filter drums is by acoustic methods. The vibration of certain pitches of sounds causes the particles to be released from the filter and fall into the collection container. 
         [0015]    All these factors contribute to the production of electricity at power plants, with greater efficiency, increased uninterrupted production time, lower capital costs, lower running costs and a vast improvement of the state of the surrounding environment. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]    The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain, by way of example only, the principles of the invention: 
           [0017]      FIG. 1  shows a schematic sectional view of the electrostatic cleaner of this invention. 
           [0018]      FIG. 2  shows the same device from the plan view. 
           [0019]      FIG. 3  shows another embodiment of this invention from the sectional view. 
           [0020]      FIG. 4  shows the embodiment of  FIG. 3  from the plan view. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0021]    As will be appreciated, the present invention is capable of other and different embodiments than those discussed above and described in more detail below, and its several details are capable of modifications in various aspects, all without departing from the spirit of the invention. Accordingly, the drawings and description of the embodiments set forth below are to be regarded as illustrative in nature and not restrictive. 
         [0022]      FIG. 1  shows the improved electrostatic smoke cleaner from the sectional view. A positively-charged rotating plate  100 , negatively charged electrodes  102 , a collection hopper  108  and fixed brushes  106 . 
         [0023]    The particle-laden smoke enters the electrostatic cleaner from the direction of the arrow  120  and flows through the negatively charged electrodes  102 . The smoke particles are now negatively ionized and continue flowing through the cleaner until they pass by the positively charged circular plate  100 . 
         [0024]    The positively charged circular plate  100  rotates in the same direction and at a speed close to that of the smoke passing over it. The continuous rotation and cleansing of the plate  100  will expose constantly to the polluted smoky air a clean positively charged surface. Thus, only a thin layer of negatively charged particles will accumulate on the plate  100 . As the plate  100  rotates, it is cleaned by the cleaning brushes  106  and the particles fall into the bottom of the collection hopper  108  from where they are collected and disposed of. 
         [0025]    The cleaned smoke is then vented out of the electrostatic cleaner in the direction of arrow  122 . 
         [0026]    Another advantage of this invention is that the collection hopper  108  is sealed, thus the particles are not released back into the air-flow, but instead drop to the bottom of hopper  108 . 
         [0027]    The collection plate  100  can have small fins  110  on its edges so that the smoke passing through will drive and rotate the collection plate  100 . Thus, no extra cost would be entailed in order to rotate the collection plate  100 . 
         [0028]    Optionally a small electric motor could be used to rotate the plate  100  at the required speed. 
         [0029]      FIG. 2  shows the electrostatic smoke cleaner from the plan view. The particle filled smoke enters from the direction shown by the arrow  120 . The particles are negatively charged by passing by the electrodes  102  and are attracted to the positively charged cleaning disc  100 . The disc  100  rotates and the brushes  106  constantly clean the disc by means of the disc&#39;s rotating movement. 
         [0030]      FIG. 3  shows the sectional view of a different embodiment of the electrostatic cleaner, the main difference from the embodiment described in  FIG. 1  is the shape of the disc. In this embodiment the charged cleaning device is a cylinder-shaped drum  126  closed at both ends. The drum  126  exposes more surface area and therefore attracts more particles onto its surface. The brushes  106  clean the ends of the drum  126  in a similar way to the cleaning of the disc  FIG. 1   100 . The brushes  107  rest against and touch the drum  126  along its length so that when the drum rotates, the brushes  107  clean off any particles that have been attracted to drum  126 . 
         [0031]    In other respects this embodiment works in a similar way to that in  FIG. 1  and  FIG. 2 . The particle filled smoke flows in the direction of the arrow  120  passing the electrodes  102  which charge the smoke particles with a negative ionization. The drum  126  is charged with a positive charge and thereby attracts the said particles onto its surface. The drum  126  turns either by the inertia of the air moving past it, with or without fins as described in  FIG. 1   110 , or with the aid of a motor. 
         [0032]    The brushes  106  and  107  clean off the particles from the surface of the drum  126 . The particles fall to the bottom of the hopper  108  and are periodically removed therefrom. 
         [0033]    The cleaned air flows in the direction of arrow  122 . 
         [0034]      FIG. 4  shows the embodiment in  FIG. 3  from the plan view. The smoke flows in the direction of the arrow  120  past the electrodes  102  over the drum  126  and out in the direction of the arrow  122 . The drum turns on its central axis in the direction of arrow  127  and the brushes  106  at each end of the drum  126  clean off the particles. The brushes  107  under the drum  126  are shown with a broken line as they are not ordinarily visible from the plan view. 
         [0035]    The present invention is not intended to be limited to the embodiments described above, but to encompass any and all embodiments within the scope of the following claims.