Abstract:
A lid for the receiver vessel an centrally disposed intake opening and a plurality of outlet openings located on diametrically opposite sides of the intake opening, a non-perforated pipe of finite length connected to the intake opening and extending a finite distance that is at a minimum 2.5 times the diameter of the non-perforated pipe into the receiver vessel, the relationship of the diameter of the non-perforated pipe and the inside diameter of the receiver vessel which defines an air space therebetween being configured to a ratio that is equal to or greater than 1:2.5 to thereby cause the gas/air flow through the air space toward the plural outlet openings to be substantially uniform and substantially less than a pick-up velocity of the particulate so as to cause the particulate to become separated from the air flow.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to an assembly for separating air entrained particulate from an air stream in a pipe and, more particularly, to a lid assembly for a vacuum receiver vessel having a central intake opening and a non-perforated pipe of a finite diameter extending into the central portion of the receiver vessel a finite distance, the air space between the outer diameter of the non-perforated pipe and the inside diameter of the receiver vessel and plural outlet openings being configured to limit the air speed of the volume of air moving therethrough to the plural air outlet openings in the lid located circumferentially generally equidistantly spaced from the intake opening and each other to less than a pick-up velocity of the particulate. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the plastics industry, processors use a vacuum system to convey a product to a vacuum receiver which is located on the extruder or molding machine. A screen or filter is used to separate the incoming material from the air steam as the air and material flows to a vacuum Blower. The product is may be a virgin (pelleted) material, regrind (ground plastic, powder or a combination of some or all. During the conveying cycle, the screen or filter on the vacuum receiver will become clogged, creating an increase in the pressure drop of the system. The increase in pressure drop causes a loss in conveying efficiency. In order to rectify the problem, it then becomes necessary to add a special screen or filter and cleaning system which will automatically clean the filter or screen after each filling cycle. The cleaning system usually uses blasts of compressed air to clean the filter/screen, often creating dust problems as dust escapes from the vessel, into the atmosphere. 
         [0003]    In the aforesaid situations, a mixture of materials or selected materials enters the vacuum receiving vessel through a radial or tangential inlet in the hopper body. The screen/filter and cleaning assembly is located in the cover for the vessel. 
         [0004]    Accordingly, it is an object of the invention to provide a filter-less cover assembly embodying the invention which eliminates the need for the filter/screen, the filter cleaning systems, dust problems and losses in conveying efficiency due to increased pressure drop. 
         [0005]    It is a further object of the invention to provide a filter-less cover assembly as aforesaid which is designed to be simply substituted for the existing cover assembly having thereon the filter or screen equipment as well as the cleaning system therefor. 
       SUMMARY OF THE INVENTION 
       [0006]    The objects and purposes of the invention are met by providing on a lid for the receiver vessel an centrally disposed intake opening and plural outlet openings located circumferentially generally equidistantly spaced around the central intake opening and from each other, a non-perforated pipe of finite length connected to the intake opening and extending a finite distance that is at a minimum 2.5 times the diameter of the non-perforated pipe into the receiver vessel, the relationship of the diameter of the non-perforated pipe and the inside diameter of the receiver vessel which defines an air space therebetween being configured to a ratio that is equal to or greater than 1:2.5 to thereby cause the air flow through the air space toward the plural outlet openings to be to be substantially uniform and substantially less than a pick-up velocity of the particulate so as to cause the particulate to become separated from the air flow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Other objects and purposes of the invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings, in which: 
           [0008]      FIG. 1  is a schematic central cross-sectional view of a vacuum receiver lid assembly embodying my new invention mounted on a receiver vessel associated with a material hopper for collecting the particulate that has been separated from the gas (air) flow as well as a vacuum blower assembly; 
           [0009]      FIG. 2  is a central cross-sectional view of the lid assembly per se; 
           [0010]      FIG. 3  is a top view of the lid assembly; and 
           [0011]      FIG. 4  is a chart listing sample particulate pick-up velocities and sample receiver vessel diameters. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Certain terminology may be used in the following description for convenience and reference only and will not be limited. The words “up” and “down” will designate direction in the drawings to which reference is made. The words “upstream” and “downstream” will refer to the direction of material flow through the device, “upstream” to “downstream” being the normal flow direction. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. The words “gas”, “air”, “gas flow” and “airflow” will be used interchangeably and are not to be limiting. Such terminology will include the words above specifically mentioned, derivatives thereof and words of similar import. 
         [0013]    While the following discussion does not refer to the use of the device in conjunction with any specific type of equipment, it is to be understood that its application is broad based and can be applied in any type of vacuum system, continuous or intermittent, to provide the filling of a variety of extruders, injection molding machines, storage silos, mixers, and virtually any other receiving vessel or device to which the particulate material would have to be conveyed. 
         [0014]    The subject matter of my earlier issued U.S. Pat. Nos. 4,583,885, 5,776,217 and 6,251,152 are incorporated herein by reference. Environments into which this invention can be utilized are disclosed in my earlier issued U.S. Pat. No. 5,622,457 and the subject matter of this patent is to be incorporated by reference as well. In addition, a device for effecting the entrainment of particles into a gas stream is disclosed in my earlier issued U.S. Pat. No. 5,340,241 and the subject matter of this patent is to be incorporated herein by reference as well. 
         [0015]    As a quick overview of this disclosure,  FIG. 1  illustrates a vacuum receiver  10  adapted to separate a particulate material or particles P entrained in a gas-particle stream S from a particulate material source  11 . The particles at the source  11  are entrained into a gas-particle stream S by, for example, a pneumatic vacuum conveying system as shown in U.S. Pat. Nos. 4,583,885, 5,340,241 and 5,490,745, this latter patent being additionally incorporated by reference. As shown in  FIG. 1 , the vacuum blower  12  creates a gas flow within a gas tight gas flow system represented in  FIG. 1  by drawing gas into the inlet end of an inlet pipe  13 , and through an interior of the vacuum receiver  10  and thence through dual gas outlet pipes  14  and a manifold  16  which joins the dual outlet pipes  14  into a single pip  17 . 
         [0016]      FIGS. 1 and 2  both illustrate my unique lid or cover assembly  20  for a receiver vessel  21  part of the vacuum receiver  10 . The lid  20  is comprised of a flat plate  22  having a central opening  23  therethrough and a plurality of other through-openings  24  oriented circumferentially generally equidistantly spaced around the central opening  23  and from each other. In this particular embodiment, there are two other through-openings  24 , although it is to be recognized that more than two other through-openings  24  can be provided and be within the scope of the invention. When there is an even number of other through-openings  24 , a pair or pairs of the other through-openings are located generally equidistantly spaced from and on diametrically opposite sides of the central opening. The inlet pipe  13  is composed of two solid, non-perforated sections  26  and  27  having a right angle elbow construction  28  oriented between the two sections  26  and  27 . The section  27  of the inlet pipe is configured to be rotatably mounted in a bearing  29  and extend through the central opening  23 . The bearing  29  also is configured to prevent air from being sucked into the interior of the receiver vessel  21 . One end of the elbow construction between the two sections  26  and  27  is connected being connected to one end, here, the upper end of the section  27  and is configured to provide a flat abutment surface  31 , the plane of which is oriented either parallel to the longitudinal axis of the section  27  or, and preferably, inclined slightly away from the longitudinal axis of the of the section  27  as shown in  FIGS. 1 and 2  so as to define a chamber  32 . The section  26  is connected to the other end of the elbow construction upstream of the chamber  32  and extends to a terminal end whereat gas (air) can enter the open inlet end  33 . 
         [0017]    The vacuum receiver  10  includes a hollow interior hopper or vessel  34 . The vessel includes a cylindrical shell  36  mounted on a base  37  defining a funnel-like structure leading to an outlet opening  38 . A discharge valve  39  is provided in the outlet opening  38  and is rotatable between open and closed positions in relationship to the outlet opening  38 , the closed position being illustrated. The discharge valve  39  is configured to maintain a vacuum tight seal at the bottom of the hopper  37  at all times. The discharge valve  39  may also be a rotating sluice type valve which will maintain the vacuum tight seal while continuously discharging the particulate P. In this particular embodiment, the cylindrical shell  36  is welded together with the upper end of the conical section  37  with a bottom flange  41  being provided at the lower end of the hopper being bolted to a mating flange  42  on the discharge valve  39 . The inner diameter D 1  of the vacuum receiver cylinder  36  is at a minimum 2.5 times the outer diameter D 2  of the non-perforated pipe section  27 . The non-perforated pipe section  27  has a length L is at a minimum of 2.5 times the outer diameter D 2  of the non-perforated pipe section  27 . An annular air space  35  is provided between the outer diameter D 1  of the pipe section  27  and inner diameter D 2  of the vessel  36 . 
         [0018]    In this particular embodiment, the lid  20  is designed to be a removable lid which is tightly mounted onto the open top part of the vessel  36  for form a seal thereat. A conventional rubber-like seal (not shown) is provided between the upper end of the vessel  36  and the lid  20 . The outside of the upper end of the vessel  36  has plural protrusions  43  thereon. Conventional clips  44  operatively engage the protrusions  43  to affix the lid  20  to the upper end of the vessel  36  and compress the material of the rubber-like seal. It is to be recognized that a lid configuration that is welded or otherwise permanently affixed to the open top vessel  36  is to be considered within the scope of this invention. 
         [0019]      FIG. 2  illustrates the lid  20  independent of the receiver vessel  36 .  FIG. 3  illustrates a top view of the lid  20 , the arrow  46  indicating the ability of the pipe section  26  to swivel about the axis of the central opening  23  due to the support provided by the bearing  29 . 
       Operation 
       [0020]    Although the operation of the vacuum receiver described above will be understood from the foregoing description by skilled persons, a summary of such description is now given for convenience. 
         [0021]    When the suction blower  12  is activated, airflow of sufficient volume and velocity is drawing into the inlet end  33  of the pipe section  26  to pick up and convey the material P and entrain it in the airflow. The flow of the gas (or air) S and material P passes through the pipe section  26  to the elbow construction  28  and the kinetic energy of the material P causes it to impact against the abutment surface  31  to reduce the kinetic energy of the material prior to it entering the upper end of the pipe section  27 . The following material P impacts against the collected material in the chamber  32  to thus prevent any abrasive wear on the abutment surface  31 . The material and airflow enters the vessel  36  whereat the airflow undergoes a 180 degree turn into the air space  35  and the kinetic energy of the material causes it to me separated from the airflow and collect in the hopper  37 . The velocity of the gas S entering the air space  35 , the length of which is 2.5 time the outer diameter D 2  of the pipe section  27 , is less than 10% of the minimum velocity required to convey the material P. This low velocity is assured by maintaining the ratio of the outer diameter D 2  of the pipe section  27  and the inner diameter D 1  cylinder  17  at a minimum of 1:2.5 and by the orientation of the plural second through-openings  24  in the lid. 
         [0022]    The chart illustrated in  FIG. 4  shows the pick-up velocity of various materials and dimensions of the outer diameter D 2  of the pipe section  27  and inner diameter D 1  if of the receiving vessel  36  in order to achieve the aforesaid gas velocity that is less than 10% of the pick-up velocity of the particulate. 
         [0023]    The conveying gas S exits the vacuum receiver  10  through two (or more) circumferentially and generally equidistantly spaced pipes  14  surrounding the central opening  23  to create a uniform upward velocity in the air space  35  which is less than 10% of the minimum velocity required to convey the particulate P to cause the material to settle into the hopper  37 . No material is able to reach the outlet pipes  14 . 
         [0024]    For servicing the vacuum receiver as disclosed herein and with the suction blower means  12  rendered inactive, the machine operator need only to release the clips  44  and lift off the entire cover  20  thus providing immediate access to the entire interior of the vacuum receiver and the underside of the cover  20 . In addition, the pipe section  27  can at that be changed to a different diameter to achieve a different operation characteristic on the material. 
         [0025]    Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.