Abstract:
A pulse valve arrangement includes a valve housing on which is fixed a control valve The valve housing includes a circular cylindrical portion with a valve member movably arranged therein. The valve chamber has an inlet adapted to be connected to a pressure medium source for allowing pressure medium to flow into the valve chamber and an outlet through which pressure medium flows out of the valve chamber. The control valve may be closed in which the outlet of the valve chamber is moved to a closing position blocking the flow of pressure medium, or may be opened in which the outlet of the valve chamber is moved to an opening position allowing a pulse of pressure medium therethrough. The valve member within the valve housing is freely displaceable within the circular cylindrical portion of the valve housing based on the pressure within the valve chamber as controlled by the control valve.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a pulse valve. More particularly, the present invention relates to a pulse valve for higher pressure pulses of compressed air useful for cleaning filter elements in a filtering plant for cleaning polluted gases. 
       BACKGROUND OF THE INVENTION 
       [0002]    A known valve arrangement disclosed in U.S. Pat. No. 5,533,706 incorporated herein in its entirety by reference, is used for delivering pulses of compressed air to filter elements, such as filter bags, in a filtering plant useful for cleaning polluted gases. The compressed air pulses are delivered to the interior of the filter elements to clean the elements by shaking and blowing loose dust cakes which, in the cleaning of polluted gases, attach to the walls of the filter elements. For this purpose of cleaning filter elements, the known valve arrangement is mounted on a compressed air tank. The valve arrangement includes a valve housing having a circular cylindrical portion forming a valve chamber, a control valve and a valve member therein. The valve chamber has an inlet adapted to be connected to a pressure medium source for allowing a pressure medium to flow into the valve chamber, and an outlet through which pressure medium flows out of the valve chamber. The control valve is movable between a closed position in which the outlet of the valve chamber is closed and an open position in which the outlet of the valve chamber is open. The valve member is freely displaceable within the circular cylindrical portion of the valve housing based on the pressure within the valve chamber. The valve member includes a piston which is moveable between a closing position in which the piston is adapted to prevent the flow of pressure medium and an opening position in which the piston is adapted to permit the flow of pressure medium. The inlet of the valve chamber is defined by an annular gap formed between the piston and the circular cylindrical portion of the valve housing. The circular cylindrical portion of the valve housing preferably extends so far in the axial direction of the piston as to surround at least the major portion of and preferably the entire piston when the piston is in its opening or closing position. Pressure medium ports are formed in the wall of the circular cylindrical portion at a free end thereof. The pressure medium ports so formed at the free end of the circular cylindrical portion wall are limited in size so as to ensure the remaining wall provides sufficient guidance surface to support plunger movement and alignment. However, the remaining wall of the circular cylindrical portion restricts compressed air flow causing significant valve pressure loss. Development of a pulse valve with increased compressed air flow is needed in filtering plants useful for cleaning polluted gases. 
       SUMMARY OF THE INVENTION 
       [0003]    The subject pulse valve arrangement enables increased compressed air flow, increased pressure pulses of compressed air and increased valve reliability and performance. The subject pulse valve arrangement provides for an increased cross section area dedicated to pressure medium ports with the remaining circular cylindrical portion wall significantly limited in size to reduce undesirable pressure loss. By reducing pressure loss, the subject pulse valve achieves higher pressure pulses of compressed air to filter bag elements enabling more filtration area cleaning per pulse per valve. Additionally, an increased cross sectional area dedicated to pressure medium ports for increased compressed air flow means less wall to plunger contact. Unexpectedly, less wall to plunger contact results in fewer plunger malfunctions caused by grit on wall surfaces, wall dents, plunger misalignment, and the like, contrary to prior teachings. 
         [0004]    The subject pulse valve arrangement for cleaning filter units is useful for cleaning polluted gas. As such, the subject pulse valve arrangement comprises a valve housing with an interior area, a valve fixed on the valve housing and a valve member arranged within the valve housing. The valve fixed on the valve housing is opened to decrease pressure and lift the valve member causing free ends of the valve member to contact the valve housing. When the free ends of the valve member contact the valve housing, a compressed air pulse is supplied through housing openings and into a pressure tube to clean associated filter units. The housing openings through which the compressed air pulse is supplied, provide an open area suitable for increased fluid flow, increased pulse pressure, and reduced pressure drop over that of the prior art pulse valve arrangement. As described in more detail below, the subject housing openings provide about 25% to about 125% increased open area, or about 55% to about 95% increased open area. In doing so, valve housing causes a reduced pressure drop over that of the prior art. Further, the valve fixed on the valve housing may be closed to increase pressure and move the valve member outwardly so as to block compressed air flow from housing openings and the pressure tube between filter unit cleanings. 
         [0005]    Also disclosed herein is a method of using the subject pulse valve arrangement. The method comprises opening a valve fixed on a valve housing to cause a drop in pressure within the valve housing moving a valve member into an opening position to allow a pulse of compression air from a compression air tank to flow through housing openings and into a pressure pipe for filter cleaning. The subject method also includes closing the valve fixed on the valve housing to cause an increase in pressure within the valve housing to move the valve member into a closing position to block compression air from a compression air tank from flowing through housing openings and into the pressure pipe between filter cleanings. The subject method also provides for the housing having housing openings with an open area suitable for increased fluid flow, increased pulse pressure, and reduced pressure drop over that of the prior art. As such, the subject housing openings provide about 25% to about 125%, or about 55% to about 95% increased open area, and the valve housing causes a reduced pressure drop over that of the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The subject pulse valve is described in more detail below with reference to the accompanying drawings. 
           [0007]      FIG. 1  is a side cross-sectional view showing a valve arrangement according to the prior art in the closed position. 
           [0008]      FIG. 2  is a side partial cut away view of the valve arrangement of  FIG. 1  in the open position positioned within a compressed air tank. 
           [0009]      FIG. 3  is a side cross-sectional view showing a valve arrangement according to the present invention in the closed position. 
           [0010]      FIG. 4  is a side partial cut away view of a valve arrangement similar to that of  FIG. 3  in the open position positioned within a compressed air tank. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    The prior art valve arrangement  10  illustrated in  FIGS. 1 and 2  is used for delivering compressed-air “CA” pulses to vertically arranged, bag-shaped filter elements (not shown) in a filtering plant useful for cleaning polluted gases. The valve arrangement  10  is mounted in a pressure medium tank  12  through a circular opening  14  provided in the upper wall  16  of the tank  12 . The tank  12  is a compressed air tank. 
         [0012]    A vertical pressure tube  18  coaxial with opening  14 , extends through the lower wall  20  and into interior area  22  of tank  12 . An upper end  24  of pressure tube  18  is arranged a distance “D” below opening  14 . The upper end  24  of the pressure tube  18  forms a valve seat  24   a,  and the lower end  24   b  of pressure tube  18  opens outside tank  12  fluidly connected to openings in the bag-shaped filter elements (not shown). 
         [0013]    Valve arrangement  10  has a valve housing  28  consisting of two circular, coaxial parts, namely an upper part  28   a  and a tubular lower part  28   b  fixed together. A pipe socket  30 , in which lower part  28   b  is fixed, is welded or similarly fixed in opening  14 . The lower surface  32  of upper part  28   a  has an annular upper flange  34  engaging the upper end  30   a  of the pipe socket  30 , when the lower part  28   b  is arranged in pipe socket  30 . The upper part  28   a  also has and extended duct  36  with an open end  38 . A valve (not shown) such as a solenoid valve or the like is fluidly connected to duct  36  at open end  38 . 
         [0014]    A valve member  40  in the form of a circular-cylindrical piston with a substantially “U”-shaped cross section, is disposed in an interior area  42  of lower part  28   b.  The outer diameter “OD” of valve member  40  is slightly smaller than the inner diameter “ID” of lower part  28   b,  so as to provide an annular gap  44  between valve member  40  and interior wall surface  46  of the lower part  28   b.  Gap  44  provides a continuous fluid communication between the interior area  22  of pressure tank  12  and the interior area  48  of valve member  40 . Valve member  40  constitutes the main valve of valve arrangement  10  and is freely displaceable between an outer closing position, in which base  50  of valve member  40  sealingly contacts valve seat  24   a  of the pressure tube  18 , and an inner opening position ( FIGS. 1 and 2 ), in which base  50  of valve member  40  is lifted off valve seat  24   a  so that free ends  40   a  of valve member  40  contact lower surface  32  of upper part  28   a.  In the closing position of valve member  40 , the valve (not shown) fixed to extended duct  36  is in a closed position. 
         [0015]    When valve member  40  is to be opened from the closing position to deliver a compressed-air CA pulse of short duration to the bag-shaped filter elements via the pressure tube  18 , the valve fixed to extended duct  36  is opened creating a reduction in pressure lifting valve member  40  causing free ends  40   a  of valve member  40  to contact lower surface  32  of upper part  28   a.  As such, compressed air CA flows through openings  52  in lower part  28   b  and into pressure tube  18 . 
         [0016]    When valve member  40  is to be closed from the opening position illustrated in  FIGS. 1 and 2 , the valve fixed to extended duct  36  is closed to create an increase in pressure that forces valve member  40  to move outwardly until base  50  is in sealing contact with valve seat  24   a.  As such, compressed air CA is blocked from flowing through openings  52  in lower part  28   b  and into pressure tube  18 . 
         [0017]    Now referring to  FIGS. 3 and 4 , the subject pulse valve device  210  is illustrated. Pulse valve device  210  has features in common with those of pulse valve device  10  illustrated in  FIGS. 1 and 2 . As such, features illustrated in  FIGS. 3 and 4  common to those of  FIGS. 1 and 2  are signified using the same reference numbers but with the number “2” preceding them. 
         [0018]    The subject pulse valve arrangement  210  is useful for delivering increased pressure compressed-air “CA” pulses to vertically arranged, bag-shaped filter elements (not shown) in a filtering plant used to clean polluted gases. The subject pulse valve arrangement  210  is mounted in a pressure medium tank  212  through a circular opening  214  provided in the upper wall  216  of the tank  212 . The tank  212  is a compressed air tank. 
         [0019]    A vertical pressure tube  218  coaxial with opening  214 , extends through the lower wall  220  and into interior area  222  of tank  212 . An upper end  224  of pressure tube  218  is arranged a distance “D” below opening  214 . The upper end  224  of the pressure tube  218  forms a valve seat  224   a,  and the lower end  224   b  of pressure tube  218  opens outside tank  212  fluidly connected to openings in the bag-shaped filter elements (not shown). 
         [0020]    The subject pulse valve arrangement  210  has a valve housing  228  consisting of two circular, coaxial parts, namely an upper part  228   a  and a tubular lower part  228   b  fixed together. A pipe socket  230 , in which lower part  228   b  is fixed, is welded or similarly fixed in opening  214 . The lower surface  232  of upper part  228   a  has an annular upper flange  234  engaging the upper end  230   a  of the pipe socket  230 , when the lower part  228   b  is arranged in pipe socket  230 . The upper part  228   a  also has and extended duct  236  with an open end  238 . A solenoid valve (not shown) or the like is fluidly connected to duct  236  at open end  238 . 
         [0021]    A valve member  240  in the form of a circular cylindrical piston with a substantially “U”-shaped cross section, is disposed in an interior area  242  of lower part  228   b.  The outer diameter “OD” of valve member  240  is slightly smaller than the inner diameter “ID” of lower part  228   b,  so as to provide an annular gap  244  between valve member  240  and interior wall surface  246  of the lower part  228   b.  Gap  244  provides a continuous fluid communication between the interior area  222  of pressure tank  212  and the interior area  248  of valve member  240 . Valve member  240  constitutes the main valve of valve arrangement  210  and is freely displaceable between an outer closing position, in which base  250  of valve member  240  sealingly contacts valve seat  224   a  of the pressure tube  218 , and an inner opening position ( FIGS. 3 and 4 ), in which base  250  of valve member  240  is lifted off valve seat  224   a  so that free ends  240   a  of valve member  240  contact lower surface  232  of upper part  228   a.  In the closing position of valve member  240 , the solenoid valve (not shown) is in a closed position. 
         [0022]    When valve member  240  is to be opened from the closing position to deliver a compressed air pulse of short duration to the bag-shaped filter elements via the pressure tube  218 , the solenoid valve is opened creating a reduction in pressure lifting valve member  240  causing free ends  240   a  of valve member  240  to contact lower surface  232  of upper part  228   a.  As such, compressed air CA flows through openings  252  in lower part  228   b  and into pressure tube  218 . 
         [0023]    When valve member  240  is to be closed from the opening position illustrated in  FIGS. 3 and 4 , the solenoid valve is closed to create an increase in pressure that forces valve member  240  to move outwardly with base  250  in sealing contact with valve seat  224   a.    
         [0024]    A method of using the pulse valve arrangement  210  of the present invention comprises opening a solenoid valve to cause a drop in pressure within a valve housing  228  and valve member  240  to move valve member  240  to an opening position, and allowing a pulse of compression air from a compression air tank to flow through openings  252  in valve housing  228  and into pressure pipe  218  for filter cleaning. Also, the pulse valve arrangement  210  of the present invention may comprise closing a solenoid valve to cause an increase in pressure within a valve housing  228  and valve member  240  to move valve member  240  to a closing position, and blocking a pulse of compression air from a compression air tank from flowing through openings  252  in valve housing  228  and into pressure pipe  218  between filter cleanings. 
         [0025]    According to the teachings of the prior art valve arrangement  10 , the circular-cylindrical lower part  28   b  extends as far down as the upper end  24  of the pressure tube  18  so that the entire valve member  40  is surrounded by the lower part  28   b  when the valve member  40  is in its closing position. As a result, the valve member  40  is accurately guided during its entire displacement, thus obviating the risk of jamming. Also, lower part  28   b  has a plurality of openings  52  which prevent undesired throttling of the compressed air CA flow from the pressure tank  12  to the pressure tube  18  when valve member  40  is in its opening position. 
         [0026]    Unexpectedly and contrary to these prior teachings, it has been discovered that having the circular-cylindrical lower part  28   b  extending as far down as the upper end  24  of the pressure tube  18  so that the entire valve member  40  is surrounded by the lower part  28   b  when the valve member  40  is in its closing position is not necessarily desirable. As a result of the entire valve member  40  surrounded by the lower part  28   b  the valve member  40  may have a tendency to jam due to grit on interior wall surface  46 , dents in lower part  28   b,  or the like. To correct this problem, the subject valve arrangement  210  eliminates as much of lower part  228   b  by significantly expanding openings  252  while still providing structural integrity to the overall valve arrangement  210 . In correcting the problem, open area of openings  252  are increased resulting in increased fluid flow allowing for increased pulse pressure. Increased pulse pressure allows for more filtration area cleaning per pulse per valve. As such, in the subject valve, openings  252  provide about 25% to about 125% greater open area, or about 55% to about 95% greater open area for fluid flow than that provided by openings  52  on commercially available prior art pulse valves described herein. 
         [0027]    Additionally, lower part  28   b  was taught as having a plurality of openings  52  which prevented undesired throttling of the compressed air CA flow from the pressure tank  12  to the pressure tube  18  when valve member  40  is in its opening position. Unexpectedly, it has been discovered that the plurality of openings  52  taught by the prior art cause a significant pressure drop significantly limiting the pressure of the compressed air CA pulse delivered to the pressure tube  18 . To correct this problem, the subject valve arrangement  210  has significantly expanded open area provided by openings  252  for fluid flow as described above, to eliminate the observed significant pressure drop and hence significantly increase the pressure of the compressed air CA pulse delivered to the pressure tube  218 . Significantly increasing the pressure of the compressed air CA pulse delivered to the pressure tube is considered desirable by delivering higher pressure pulses of compressed air CA to filter bag elements enabling more filtration area cleaning per pulse per valve. 
         [0028]    While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.