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.
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.
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.
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.
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.
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.
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:
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.
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.
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.
As a quick overview of this disclosure,
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 D1 of the vacuum receiver cylinder 36 is at a minimum 2.5 times the outer diameter D2 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 D2 of the non-perforated pipe section 27. An annular air space 35 is provided between the outer diameter D1 of the pipe section 27 and inner diameter D2 of the vessel 36.
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.
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.
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 D2 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 D2 of the pipe section 27 and the inner diameter D1 cylinder 17 at a minimum of 1:2.5 and by the orientation of the plural second through-openings 24 in the lid.
The chart illustrated in
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.
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.
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.