Abstract:
Pulse valves and methods of using pulse valves are provided. The pulse valves include a dampening mechanism to decrease mechanical stresses, decrease operating noise, decrease compressed air waste and increase operational life expectancy. Such dampening mechanism is arranged within an internal area of the pulse valve housing. Additionally, fluid within the internal area of the pulse valve provides cushioning effects during operation of the pulse valve.

Description:
FIELD OF THE INVENTION 
       [0001]    In general, the present disclosure relates to a cleaning valve useful for cleaning at least a portion of a filter unit, such as filter bags, arranged in a filter installation useful for filtering polluted gas passed therethrough. More specifically, the present disclosure relates to a cleaning valve with a dampening mechanism that enables increased tank pressure for increased filter area cleaning per cleaning valve without jeopardizing cleaning valve reliability. 
       BACKGROUND OF THE INVENTION 
       [0002]    Commercial “bag house” type filter installations typically consist of a plurality of parallel filter units, each containing a plurality of parallel rows of vertically arranged filter elements in the form of filter bags. Each such filter bag has a top end opening. A gas polluted with particulates is channeled through the filter installation&#39;s filter units to filter and collect the particulates entrained in the gas. By filtering and collecting the particulates entrained in the gas, a cleaned gas is produced. More specifically, a cleaned gas is produced by channeling polluted gas into a filter installation for passage through one or more filter units arranged for gas flow from an exterior surface of a plurality of filter bags through to an interior area within the filter bags via gas movement through the sides of the filter bags. In passing from an exterior surface of the filter bags through to an interior area within the filter bags, particulate pollutants carried by the gas become trapped on the exterior surface of the filter bag. Hence, gas in the interior area of the filter bags is the so produced “cleaned gas”. Cleaned gas exits the interior areas of the filter bags via a top end opening formed in a top of each such filter bag. As such, cleaned gas flows from the top end openings through an outlet duct common to the filter units. 
         [0003]    During operation of the filter installation, a negative pressure is typically generated by a fan arranged downstream of the filter installation causing gas flow through the filter units and filter bags. As the gas passes through the sides of the plurality of filter bags, the gas is cleaned as dust and particulates entrained in the gas deposit on the exterior surfaces of the filter bags forming a dust cake. Cleaning of the filter bags to remove dust cakes is necessary for effective equipment operation and performance. 
         [0004]    Cleaning of the filter bags is accomplished using a pressure medium in the form of compressed air pulses injected into the filter bags in a direction opposite to that of gas filtering. The rows of filter bags are cleaned successively using compressed air pulses generated and transmitted at the same time to all filter bags in a given row. Such is accomplished by means of a cleaning unit arranged for successively cleaning each individual row of filter bags. Each cleaning unit comprises a nozzle pipe arranged above and extending along the length of the associated row of filter bags parallel thereto for cleaning thereof. Each nozzle pipe also includes a distribution pipe with a plurality of vertically downwardly projecting pipe sockets connected thereto with each individual pipe socket positioned straight above a filter bag top end opening in the row. The function of these pipe sockets is to direct via nozzles compressed air pulses into each of the respective filter bag top end openings. The pipe sockets usually have a diameter of about 1.5 to 2 times greater than the diameter of the nozzle associated therewith. The nozzles associated therewith consist of circular holes of varying diameter formed in the distribution pipe. The varying diameters of the circular holes in the distribution pipe are determined empirically based on the total number of pipe sockets/nozzles along the length of the distribution pipe requiring a uniform distribution of compressed air pulsed therethrough. As such, circular holes arranged in the distribution pipe a greater distance from the nozzle pipe are larger in diameter than those of circular holes arranged in the distribution pipe a lesser distance from the nozzle pipe. By so varying the diameter of the circular holes, a uniform distribution of compressed air pulsed therethrough is achieved. 
         [0005]    In the cleaning of filter bags using a pulse of compressed air, a valve is temporarily opened to establish a connection between a compressed air tank and the nozzle pipe to transmit a compressed air pulse through the nozzle pipe and its associated distribution pipe, pipe sockets and nozzles. As such, a single compressed air pulse is supplied to each of the filter bags in a row relatively simultaneously. Nozzle pipes as described above are thus used to effectively and efficiently clean individual rows of filter bags with compressed air pulses. In cleaning, compressed air pulses dislodge dust and particulates that collect and cake in and on the walls of the filter bags. Dust cakes that form on the filter bags are thereby loosened by the compressed air pulse moving from the interior area of the filter bags, through the filter bag side walls and out of the filter bags to an area in the filter unit exterior thereto. The resultant loosened dust cakes fall off the exterior of the filter bags for hopper collection. 
         [0006]    In operating a cleaning unit, it is essential that the above-described pulse valve delivers a cleaning pulse of compressed air at a relatively high pressure with a relatively low consumption of compressed air. Pulse valves function by a cavity behind a plunge or membrane emptying through either a solenoid valve or a pilot valve, whereby the plunge or membrane is displaced with rapid acceleration due to the differential pressure between an air tank pressure on one side of the plunge or membrane and the cavity pressure on the other side of the plunge or membrane. The plunge or membrane is displaced with considerable velocity as a result of the pressure differential and eventually hits an end position with very high momentum. The plunge or membrane hitting the end position with very high momentum creates a significantly loud noise upon impact. Likewise, when the plunge or membrane hits the end position, the impact thereof creates relatively high mechanical stresses. Mechanical stresses on the valve shorten the operational life expectancy of the valve and add to the system&#39;s operation costs when performance is hampered and/or replacement is necessary. Further, the plunge or membrane typically bounces with several pressure peaks upon hitting the end position causing compressed air waste. Hence, to increase system performance and decrease system operational costs, a valve with decreased mechanical stresses, decreased operational noise, decreased compressed air waste and increased operational life expectancy is desired. 
       SUMMARY OF THE INVENTION 
       [0007]    In view of the above, the present device is a pulse valve and a method of using the pulse valve for effective pulsed compressed air cleaning of a plurality of filter elements, such as filter bags, with decreased valve mechanical stresses, decreased valve operational noise, decreased compressed air waste and increased valve operational life expectancy. As such, a first embodiment of the subject pulse valve device useful for pulsed compressed air cleaning of at least a portion of a filter unit comprises a housing with a plunge slideably positioned therein. The housing is arranged in an opening of a pressure vessel, or compressed air tank, containing compressed air having a pressure of about 10 pounds per square inch (psi) to about 100 psi, or about 60 psi. A plurality of openings is formed in the housing for the flow of compressed air from the pressure vessel through the housing and into a nozzle pipe. Compressed air flows through the nozzle pipe for effective cleaning at least a portion of a filter unit when the plunge is in a first position, or “open” position. 
         [0008]    A fluid supply fluidly connected to or on the housing for supply of a fluid to an interior area or cavity within the housing causes displacement or movement of the plunge to a second position, or “closed” position. When in the second position, the plunge blocks the plurality of openings in the housing and thus blocks the flow of compressed air from the pressure vessel or compressed air tank to the nozzle pipe. 
         [0009]    Compressed air in the pressure vessel or compressed air tank has a pressure of about 10 psi to about 100 psi, or about 60 psi. When the plunge is in the first position, the fluid pressure within the interior area or cavity of the housing is significantly less than that of the compressed air within the pressure vessel. When the plunge is in the second position, the fluid pressure within the interior area or cavity of the housing is significantly greater than that of the compressed air within the pressure vessel. 
         [0010]    A dampening mechanism, such as cushions, is arranged inside the pulse valve housing to reduce or dampen the impact between the housing and the plunge upon movement of the plunge into the first position. The internal dampening mechanism likewise reduces the impact noise of the plunge upon movement of the plunge into the first position. In addition to the dampening mechanism, fluid within the interior area or cavity of the housing provides a cushioning effect that reduces impact and impact noise of the plunge upon displacement or movement thereof into the first position. 
         [0011]    To prevent the plunge within the pulse valve from “sticking” in the first position, the subject pulse valve may optionally include a spring member arranged in the interior area of the housing between the housing and the plunge to assist movement of the plunge into the second position upon the requisite change in pressure differential between that of the compressed air tank and the housing interior area. 
         [0012]    Another embodiment of the subject pulse valve includes a membrane extending between the plunge and the housing to fluidly separate or seal the valve interior area from that of the compressed air tank. 
         [0013]    The subject pulse valve devices also include a solenoid valve or the like associated with the housing for control of fluid flow to the interior area of the housing. This control of fluid flow controls the pressure differential between the housing interior area and the compressed air tank, thus controlling movement of the plunge for the cleaning of filter bags using compressed air pulses. 
         [0014]    A method of using the subject pulse valve device for cleaning at least a portion of a filter unit comprises reducing fluid pressure within an interior area or cavity of a valve housing to cause pressure differential movement of a plunge into a first position allowing flow of compressed air from a pressure vessel or compressed air tank through a nozzle pipe in fluid connection with a filter unit thereby cleaning the filter unit with a pulse of compressed air. Increasing fluid pressure within an interior area or cavity of the valve housing likewise causes pressure differential movement of the plunge into a second position blocking flow of compressed air from the pressure vessel or compressed air tank and hence from the nozzle pipe until a further pulse cleaning of the filter unit is indicated by buildup of a dust cake. 
         [0015]    For purposes of this method, the compressed air in the pressure vessel has a pressure of about 10 psi to about 100 psi, or about 60 psi. When the plunge is in the first position, the fluid pressure within the interior area of the housing is significantly less than that of the compressed air within the pressure vessel or compressed air tank. When the plunge is in the second position, the fluid pressure within the interior area of the housing is significantly greater than that of the compressed air within the pressure vessel. Pressure within the housing is controlled using a solenoid valve or the like for purposes of the subject method to control fluid flow to the interior area of the housing to thus control the pressure differential between that of the interior area and that of the compressed air tank. 
         [0016]    The subject method further comprises providing a dampening mechanism within the housing to reduce or cushion the impact between the housing and the plunge upon movement of the plunge into the first position. Providing a dampening mechanism as herein described also reduces the impact noise of the plunge with the housing upon movement of the plunge into the first position. Fluid within the interior area of the housing likewise provides a cushioning effect to reduce impact and impact noise of the plunge upon movement of the plunge into the first position. 
         [0017]    Optionally, a spring member may be used in the subject method by arranging the spring in the interior area of the housing between the housing and the plunge to assist movement of the plunge into the second position. Optionally, the subject method may likewise use a membrane to fluidly seal the housing interior area apart from the pressure vessel by fixing the membrane to extend between the plunge and the interior area of the housing. 
         [0018]    The subject pulse valve device and method for using the same to clean at least a portion of a filter unit, such as filter bags, arranged in a filter installation to filter polluted gas passed therethrough includes among other features noted, a dampening mechanism that enables increased tank pressure for increased filter area cleaning per cleaning valve without jeopardizing cleaning valve reliability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Embodiments according to the present invention will now be described in more detail with reference to the accompanying drawings, in which: 
           [0020]      FIG. 1  is a side cross-sectional view of a pulse valve device according to the present invention; and 
           [0021]      FIG. 2  is a side cross-sectional view of another embodiment of a pulse valve device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Pulse valves useful for effective compressed air pulsed cleaning of a plurality of filter elements, such as filter bags, with decreased valve mechanical stresses, decreased valve operational noise, decreased compressed air waste and increased valve operational life expectancy are described herein. As best illustrated in  FIG. 1 , a first embodiment of the subject valve device  10  comprises a plunge valve housing  12 . Plunge valve housing  12  is manufactured of a sturdy natural, e.g., iron, aluminum, or other metal, or synthetic, e.g., plastic, resin or other polymer, material suitably rigid and durable for robust industrial uses and forces. Plunge valve housing  12  is formed with sides  32  having openings  32   a , unitarily formed with or securely attached to a top  34 . Sides  32  include an exterior surface  36  and an interior surface  38 . Top  34  includes an exterior surface  40  and an interior surface  42 . At the juncture of interior surface  38  and interior surface  42  is a dampening mechanism or cushion  30 . Cushion  30  may be manufactured from natural or synthetic rubber, silicone or a like flexible material capable of providing cushioning effects upon repeated impact between solid surfaces. Top  34  extends outwardly beyond exterior surface  36  to form a lip  44 . As such, housing  12  is positioned within an opening  46  of a pressure vessel  24  with lip  44  abutting extended edge  48  of opening  46  with at least a portion of exterior surface  36  in contact with surface  50  of opening  46  for an airtight seal therebetween. In interior area  26  of pressure vessel  24  is compressed air “CA”. 
         [0023]    Slideably positioned within interior area  22  of housing  12  is a plunge  18 . Plunge  18  is likewise manufactured of a sturdy natural, e.g., iron, aluminum, or other metal, or synthetic, e.g., plastic, resin or other polymer, material suitably rigid and durable for robust industrial uses and forces. Exterior surfaces  52  of sides  54  of plunge  18  contacts interior surfaces  38  of sides  32  of housing  12  for an air tight seal therebetween. Free ends  56  of sides  54  abut ends  58  of pulse pipe  28  for an air tight seal therebetween. Extending between sides  54  of plunge  18  opposite free ends  56 , is a top  60  with a plug portion  62  on an exterior surface  64  thereof. Opposite exterior surface  64  is interior surface  66 . Interior surface  66  of plunge  18  is in fluid communication with interior  68  of nozzle pipe  28 . Between exterior surface  64  of plunge  18  and interior surface  42  of top  34  of housing  12  is interior area  22 . The area “A” of interior area  22  varies as plunger  18  moves or slides within housing  12 . The area A of interior area  22  is minimized when top  60  of plunge  18  moves inwardly within housing  12  to contact interior surface  42  of top  34  of housing  12 . In this first or “open” position, top  60  contacts pliable dampening mechanisms  30  and plug portion  62  fits into opening  20  to abut sealing seat  20   a  of housing  12  to block fluid “F” from flowing from cavity  16  of solenoid valve  14  integrally formed with or securely affixed to housing  12 . In this first or “open position, compressed air CA flows from interior area  26  of pressure vessel  24  through openings  32   a  and into nozzle pipe  28 . 
         [0024]    Another embodiment of the subject pulse valve device  210  is best illustrated in  FIG. 2 . Pulse valve device  210  has features in common with those of pulse valve device  10  illustrated in  FIG. 1 . As such, features illustrated in  FIG. 2  common to those of  FIG. 1  are signified using the same reference numbers but with the number “2” preceding them. As illustrated in  FIG. 2 , pulse valve device  210  comprises a housing  212 . Housing  212  is manufactured of a sturdy natural, e.g., iron, aluminum, or other metal, or synthetic, e.g., plastic, resin or other polymer, material suitably rigid and durable for robust industrial uses and forces. Housing  212  is formed with sides  232  unitarily formed with or securely attached to a top  234 . In  FIG. 2 , top  234  is illustrated as securely attached to sides  232  by means of screws  234   a . Sides  232  include an exterior surface  236  and an interior surface  238 . Top  234  includes an exterior surface  240  and an interior surface  242 . Housing  212  is positioned on an opening  246  of a pressure vessel  224  with a free edge  245  abutting extended edge  248  of opening  246  and a portion of free edge  245  in contact with surface  250  of opening  246  for an airtight seal therebetween. In interior area  226  of pressure vessel  224  is compressed air “CA”. 
         [0025]    Movably positioned within interior area  222  of housing  212  is a plunge  218 . Plunge  218  is likewise manufactured of a sturdy natural, e.g., iron, aluminum, or other metal, or synthetic, e.g., plastic, resin or other polymer, material suitably rigid and durable for robust industrial uses and forces. Sides  254  of plunge  218  are securely fixed to a membrane  254   a . Membrane  254   a  is securely fixed between sides  254  of plunge  218  and housing  212  at the point of attachment between top  234  and sides  232  for an air tight seal between interior area  222  and interior area  226  of pressure vessel  224 . Interior surface  257  of plunge  218  abuts pressure vessel  224  at opening  246 . Also fixed at opening  246  of pressure vessel  224  is nozzle pipe  228  with an air tight seal therebetween. Extending between sides  254  of plunge  218  opposite interior surface  257  is a top  260  with a plug portion  262  on an exterior surface  264  thereof. Exterior surface  264  of top  260  includes one or more dampening mechanisms or cushions  230 . Cushions  230  may be manufactured from natural or synthetic rubber, silicone or a like flexible material capable of providing cushioning effects upon repeated impact between solid surfaces. Between exterior surface  264  of plunge  218  and interior surface  242  of top  234  of housing  212  is interior area  222 . The area “A” of interior area  222  varies as pilot plunger  218  moves within housing  212 . The area A of interior area  222  is minimized when top  260  of plunge  218  moves inwardly in housing  212  to contact interior surface  242  of top  234  of housing  212 . In this first or “open” position, plug portion  262  contacts pliable cushions  230  and plug portion  262  sized to fit into opening  220  of housing  212  blocks fluid flow from cavity  216  of solenoid valve  214  integrally formed with or securely affixed to housing  212 . In this first or open position, the compressed air pressure inside interior area  226  of pressure vessel  224  is greater than the fluid pressure inside interior area  222 . When the subject pulse valve is in this first position, interior surface  257  of plunge  218  is distanced apart from opening  246  allowing compressed air to flow from interior area  226  through the openings  232   a  in sides  232  through opening  246  and into nozzle pipe  228 . To aid plunge  218  movement into the second or “closed” position, is a spring member  230   a . Spring member  230   a  likewise dampens or cushions the impact and resultant impact noise of plunge  218  against interior surface  242  of housing  212 . 
         [0026]    The area A of interior area  222  is maximized when top  260  of plunge  218  moves outwardly from housing  212  for contact of exterior surface  257  of plunge  218  over opening  246  of pressure vessel  224 . In this second or “closed” position, plunge  218  blocks compressed air flow from flowing through opening  246 . Likewise, plug portion  262  moves a distance away from opening  220  of housing  212  to allow fluid flow from cavity  216  of solenoid valve  214  to internal area  222  of housing  212 . In this second or closed position, the compressed air pressure inside interior area  226  of pressure vessel  224  is less than that of the fluid pressure inside interior area  222 . When the subject pulse valve is in this second position, interior surface  257  of plunge  218  is blocks opening  246  preventing compressed air from flowing from interior area  226  through the openings  232   a  in sides  232  through opening  246  and into nozzle pipe  228 . 
         [0027]    A method of using the subject pulse valve device  10 ,  210  for cleaning at least a portion of a filter unit comprises reducing fluid pressure within an interior area or cavity  22 ,  222  of a valve housing  12 ,  212  to cause pressure differential movement of a plunge  18 ,  218  into a first position allowing flow of compressed air CA from a pressure vessel or compressed air tank  24 ,  224  through a nozzle pipe  28 ,  228  in fluid connection with a filter unit thereby cleaning the filter unit with a pulse of compressed air CA. Increasing fluid pressure within an interior area or cavity  22 ,  222  of the valve housing  12 ,  212  likewise causes pressure differential movement of the plunge  18 ,  218  into a second position blocking flow of compressed air CA from the pressure vessel or compressed air tank  24 ,  224  and hence from the nozzle pipe  28 ,  228  until a further pulse cleaning of the filter unit is indicated by buildup of a dust cake. 
         [0028]    For purposes of this method, the compressed air CA in the pressure vessel  24 ,  224  has a pressure of about 10 psi to about 100 psi, or about 60 psi. When the plunge  18 ,  218  is in the first position, the fluid pressure within the interior area  22 ,  222  of the housing  12 ,  212  is significantly less than that of the compressed air CA within the pressure vessel or compressed air tank  24 ,  224 . When the plunge  18 ,  218  is in the second position, the fluid pressure within the interior area  22 ,  222  of the housing  12 ,  212  is significantly greater than that of the compressed air CA within the pressure vessel  24 ,  224 . Pressure within the housing  12 ,  212  is controlled using a solenoid valve  14 ,  214  or the like for purposes of the subject method to control fluid flow to the interior area  22 ,  222  of the housing  12 ,  212  to thus control the pressure differential between that of the interior area  22 ,  222  and that of the interior area  26 ,  226  of the compressed air tank  24 ,  224 . 
         [0029]    The subject method further comprises providing a dampening mechanism  30 ,  230  within the housing  12 ,  212  to reduce or cushion the impact between the housing  12 ,  212  and the plunge  18 ,  218  upon movement of the plunge  18 ,  218  into the first position. Providing a dampening mechanism  30 ,  230  as herein described also reduces the impact noise of the plunge  18 ,  218  with the housing  12 ,  212  upon movement of the plunge  18 ,  218  into the first position. Additionally, dampening mechanism  30 ,  230  enables the use of an increased tank pressure for increased filter area cleaning per cleaning valve without jeopardizing cleaning valve reliability. Without dampening mechanism  30 ,  230 , increased tank pressure jeopardizes cleaning valve reliability due to damage or wear caused by increased mechanical stresses from the resultant higher velocity impact of the plunge  18 ,  218  with the housing  12 ,  212 . Dampening mechanism  30 ,  230  cushions the impact of plunge  18 ,  218  with housing  12 ,  212  thus lessening mechanical stresses of such impacts and reducing damage or wear to the cleaning valve. Hence, with dampening mechanism  30 ,  230 , cleaning valve reliability is not jeopardized with increased tank pressure. 
         [0030]    Fluid “F” within the interior area  22 ,  222  of the housing  12 ,  212  likewise provides a cushioning effect to reduce impact and impact noise of the plunge  18 ,  218  upon movement of the plunge  18 ,  218  into the first position. 
         [0031]    Optionally, a spring member  230   a  may be used in the subject method by arranging the spring member  230   a  in the interior area  22 ,  222  of the housing  12 ,  212  between the housing  12 ,  212  and the plunge  18 ,  218  to assist movement of the plunge  18 ,  218  into the second position. Optionally, the subject method may likewise use a membrane  254   a  to fluidly seal the housing  12 ,  212  interior area  22 ,  222  apart from the interior area  26 ,  226  of the pressure vessel  24 ,  224  by fixing the membrane  254   a  to extend between the plunge  18 ,  218  and interior surfaces  38 ,  42 ,  238 ,  242  of the housing  12 ,  212 . 
         [0032]    While preferred embodiments have 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.