Abstract:
A venturi booster mounted between axially aligned first and second filter elements in a dust collector of the type having a compressed air source for conveying pulses of compressed air to the filter elements for periodically reverse flow cleaning of the filter elements, the venturi booster being constructed and arranged to divide the compressed air flow to retain approximately 50% of the air flow within the first filter element and the balance passing through the venturi booster into the second filter element.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    In dust collectors of the type shown in my U.S. Pat. No. 4,610,704 dated Sep. 9, 1986, a plurality of individual filter elements are enclosed in a housing which admits particulate laden gases into the top of the housing to flow downwardly and radially inwardly of the individual filter units so that particulates accumulate on the exterior of the filters. The interior of the filter elements communicate with a common clean air duct at the bottom of the housing. In order to periodically clean the filter elements, a compressed air source is arranged to fire pulses of air upwardly through the filter elements to remove the particulates from the exterior surface of the filter element. The location of a pulsed air source with a respective filter element is known as a filter cleaning station. When there was only one filter element per cleaning station, the pulses of compressed air cleaned the filter element efficiently; but in collectors where a second filter was installed in alignment with a first filter at a cleaning station, it was found that the pressure wave was greatly reduced by the time it reflected back from the second filter element, whereby the first filter element was not cleaned sufficiently.  
           [0002]    This was noted particularly with cylindrical cartridge type filters having a pleated side wall extending the length of the cartridge and having annular channel caps at each end thereof. In these cartridge filters, the pulsed air jet rises within the filters upwardly through the center of the cartridges until it crashes against the far end clamping plate of the second filter to form a pressure wave which reflects back 180° expanding outwardly to force particulates back out of the second filter. This pressure wave expends itself in the second filter such that the pressure wave for cleaning the first filter is greatly reduced.  
           [0003]    After considerable research and experimentation, the venturi booster of the present invention has been devised to divert about 50% within the first filter. As each of these two high velocity flows crash into the ends of each filter, each high pressure wave reflects back within a respective filter, which pressure waves expand outwardly thereby driving the deposited dust away from each filter.  
         SUMMARY OF THE INVENTION  
         [0004]    The venturi booster of the present invention is mounted between axially aligned first and second filter elements, and comprises, essentially, an outwardly flared conical sleeve portion extending into a hollow central core of the first filter element and spaced radially inwardly from the side wall thereof. The sleeve portion is provided with an integral radially outwardly extending base portion constructed and arranged for centering the sleeve portion within the first filter and for supporting the sleeve portion vertically within the first filter.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a side elevational view of a dust collector with a portion of the housing broken away to show a pair of cleaning stations, each having first and second aligned filter elements having the venturi booster of the present invention mounted therebetween.  
         [0006]    [0006]FIG. 2 is a side elevational view of the booster of the present invention mounted between aligned first and second filter elements; and  
         [0007]    [0007]FIG. 3 is a perspective view of the venturi booster of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0008]    Referring to the drawings and more particularly to FIG. 1, the venturi booster  1  of the present invention is adapted to be installed in an industrial dust collector  2  of the type disclosed in my U.S. Pat. No. 4,610,704 dated Sep. 9, 1986, the disclosure of which is incorporated herein by reference. The dust collector  2  includes a housing having an inlet opening  3  at the top thereof for the admission of particulate-laden gases. An intermediate section  4  of the housing provides a dirty gas chamber, and the hopper or lower portion  5  of the housing tapers downwardly to a clean-out or dust discharge opening  6 . The intermediate section  4  of the housing encloses a plurality of rows of individual axially aligned filter elements  7  and  8  having the venturi booster  1  of the present invention mounted therebetween. A plurality of filter stations  9  are positioned below the filter elements  7  and communicate between the lower open ends of the filter elements  7  and a clean air duct  10  through which the clean air is conducted to the atmosphere.  
         [0009]    From the structure thus far described, it will be apparent that the particulate laden gases flowing downwardly through the inlet  3  surround the filter elements  7  and  8  and flow radially inwardly therethrough, leaving the lighter particulates entrained on the outer surface of each filter element  7  and  8 . While heavier particles will continue on to the lower portion  5  of the housing  4 , the thus cleaned gases exit from the center portions of the filter elements  7  and  8  into the filter station  9  and into the clean air duct  10  which conduct them to the atmosphere.  
         [0010]    Reverse flow cleaning of the filter elements  7  and  8  is provided by a plurality of pulsed compressed air sources  11 , one for each stack of filters  7  and  8 . The pulsed compressed air sources  11  are positioned within the clean air duct  10  and communicate with the lower open end of a respective filter element  7 . A compressed air line  12  extends through the clean air duct  10  and communicates with the pulsed compressed air sources and is provided with a plurality of compressed air outlet apertures aligned with the lower end of the venturis  11 . A source of compressed air and suitable valves (not shown) are connected to the compressed air line  12  to permit the pulsed firing of jets of air into the filters  7  and  8  at each cleaning station so as to clean the filters. Since the general flow of air through the housing  4  is from top to bottom, the shock wave created by the pulsed firing of air jets into the filters aids in the movement of the particulates removed from the filters  7  and  8  during a cleaning cycle towards the clean-out opening  6 .  
         [0011]    When there is only one filter element  7  per cleaning station, the pulses of compressed air cleans the filter element efficiently; but in collectors where a second filter element  8  is installed in alignment with the first filter  7  at a cleaning station, the pulsed jet air flow instantly reaches the far end of element  8  where its velocity is terminated producing a massive pressure wave. The return flow of this pressure wave cleans filter  8 ; however, the pressure wave quickly diminishes so as to clean filter  7  inadequately. This is experienced with cylindrical cartridge type filters  7 ,  8  as shown in FIG. 2 having a pleated side wall  7   a ,  8   a  extending the length of the cartridge and having annular channel caps  8   b ,  8   c ,  7   b  at each end thereof.  
         [0012]    To enhance the cleaning of the first filter  7 , the venturi booster  1  of the present invention is mounted between the upper end of filter cartridge  7  and the lower end of the filter cartridge  8  to allow about half of the rising pulsed air at the end of filter cartridge  7  to enter filter  8 . As the supersonic velocity of this jet flow reaches the ends of filters  7  and  8 , this flow is abruptly terminated resulting in a pressure wave which wave reverses its flow direction to force out dirt particles from filters  7  and  8  yielding uniform cleaning of both filters.  
         [0013]    As shown in FIGS. 2 and 3, the venturi booster  1  of the present invention comprises an outwardly flared conical sleeve portion  1   a  extending into the center  7   d  of filter  7  and spaced radially inwardly from the side wall  7   a  thereof. The sleeve portion  1   a  is provided with an outwardly bent portion  1   b  which together with the outwardly flared portion  1   a  forms a throat portion  1   c . The outwardly bent portion  1   b  is integral with a radially outwardly extending annular planar portion  1   d  which terminates at its periphery with an annular shoulder portion  1   e  having a peripheral lip  1   f . The annular planar portion  1   d  and shoulder portion  1   e  provide a base for supporting and centering the sleeve portion  1   a  within filter  7 . The shoulder portion  1   e  is supported on the filter end cap  7   b  and the lip  1   f  is positioned in a space  12  between the bottom end cap  8   c  having a gasket  13  affixed thereto. The lip  1   f  limits the downward movement of the filter  8  caused by heavy dust loading of the filter  8  which can result in overcompressing the gasket  13 , resulting in the filters  7  and  8  moving closer to each other but opening a space between a clamp plate  14  and the cap  8   b  on the filter  8 , thereby providing a gap between the dirty side and clean side of the filter.  
         [0014]    While the venturi booster of the present invention has been described as being mounted between vertically arranged filter cartridges  7  and  8 , it will be understood by those skilled in the art that the venturi booster  1  can also be mounted between horizontally arranged stacked cartridge filters, or any angle between 0 and 90°.  
         [0015]    It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to, without departing from, the spirit of the invention or scope of the subjoined claims.