Patent Description:
It is well known, particularly in the field of transporting and using particulate materials, commonly coarse powders, granules, pellets, and the like that it is important to keep product particles as free as possible of contaminants. Particulates are usually transported within a facility where they are to be mixed, packaged, or used in a pressurized tubular system that in reality produces a stream of material that behaves somewhat like a fluid. As these materials move through the pipes, considerable friction is generated not only among the particles themselves, but also between the tube walls and the particles in the stream. In turn, this friction results in the development of particle dust, broken particles, fluff, and streamers (ribbon-like elements that can "grow" into quite long and tangled wads that will impede the flow of materials or even totally block the flow). The characteristics of such a transport system are quite well known, as is the importance and value of keeping product particles as free as possible of contaminants.

The term "contaminant" as used herein includes a broad range of foreign material, as well as the broken particles, dust, fluff, and streamers mentioned in the preceding paragraph. In any case, contaminants are detrimental to the production of a high quality product, and in some situations a health risk to employees of the producer and possibly even a source of danger in that some contaminants can produce a dust cloud which, if exposed to an ignition source, may explode.

Considering product quality, and focusing on moldable plastics as a primary example, foreign material different in composition from the primary material, such as dust, non-uniform material of the primary product, fluff, and streamers, does not necessarily have the same melting temperatures as the primary product and causes flaws when the material is melted and molded. These flaws result in finished products that are not uniform in color, may contain bubbles, and often appear to be blemished or stained, and, therefore, cannot be sold. Heat in the injection molding machine can vaporize dust that leads to tiny gas bubbles in the finished product. Heat also burns dust and causes "black spots," which are carbonized dust. Sometimes dust pockets in the machine do not melt and cause "soft spots" or "white spots" as these defects are commonly called. It is important to note that, since these same non-uniform materials often do not melt at the same temperature as the primary product, the un-melted contaminants cause friction and premature wear to the molding machines, resulting in downtime, lost production, reduced productivity, increased maintenance and, thus, increased overall production costs.

Conventional particulate material dedusting devices, such as is disclosed in <CIT>, utilize first and second wash decks, formed as sloped planar surfaces within the apparatus and having openings therein for the passage of pressurized air therethrough to pass through particulate material flowing along the wash decks. Between the two wash decks, the particulate material passes through a Venturi zone, which combined with the passage of air through the particulate material on the wash decks, discharges dust and other contaminants upwardly with the air flow to be discharged from the apparatus.

In <CIT>, a compact dedusting apparatus having back-to-back wash deck assemblies, provides increased capacity by doubling the wash decks and the Venturi zones, which requires the inflow of particulate material to be equally divided between the two wash deck assemblies. In both <CIT> and <CIT>, a magnetic flux field is applied to the infeed of particulate material to neutralize the static charges attracting the contaminants to the particulate pellets to enhance the operation of the wash decks in separating contaminants from the particulate material.

Uniceltec, a Korean Corporation, developed and marketed a compact dedusting apparatus disclosed in <CIT>. This compact dedusting apparatus, with appropriate improvements to meet the demands of the U. market, has been marketed in the U. by Pelletron Corporation as the Model C-<NUM> dedusting apparatus. The present invention is concerned with an improvement of the latter dedusting apparatus.

Among the problems found in the presently marketed C-<NUM> dedusting apparatus is the provision of a metering device that wears through engagement with the particulate materials, adds a corresponding amount of dust into the flow of particulate material to be cleaned, and tends to clog, interrupting the flow of particulate material into the cleaning apparatus. Another problem with the metering device is the tendency for the metering device to clog with inflowing particulate material, which disrupts the operation of the cleaning apparatus.

In <CIT>, the compact dedusting apparatus with remote discharge to which the present application is an improvement is shown and described. In this Schneider patent, the particulate material infeed hopper is provided with a rotatable, fluted metering device, which requires a powered motor, preferably in the form of an electric motor, to provide rotative power to the fluted metering device. It would be desirable to provide a particulate material feeding device which is simpler in configuration and more effective in operation.

Document <CIT> shows a dedusting apparatus as described in the preamble of appended claim <NUM>. In this document, a compact dedusting apparatus includes a metering apparatus formed as a fixed shape device that closes against the floor of an infeed hopper to prevent the flow of particulate material into the dedusting apparatus. The fixed shape device is connected to a pneumatic cylinder mounted externally of the infeed hopper to provide selective vertical movement to the metering apparatus. Vertical movement of the metering apparatus is limited by slots formed in a mounting plate. The fixed shape member passes through the mounting plate for engagement with the pneumatic cylinder.

<CIT>, pollen grains are cleaned by means of a contra flow of air as the grains travel along an inclined tube. A dosage device is employed to regulate the introduction of the garnules into the inclined tube.

It would be desirable to provide a compact dedusting apparatus that would solve problems of the previously developed dedusting apparatus, particularly with respect to the particulate material feeding apparatus.

According to the present invention, there is provided a dedusting apparatus for cleaning contaminants from particulate material as hereinafter set forth in Claim <NUM> of the appended claims.

The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:.

Referring to <FIG>, a compact dedusting apparatus incorporating the principles of the instant invention can best be seen. The compact dedusting apparatus utilizes the general dedusting techniques disclosed in <CIT>, including the passage of air through a Venturi zone where particulate material passes and the flow of air removes the dust and debris from the particulate material. The particulate material is also subjected to ionization that directs negative ions onto the particulate material to separate the pellets from the minute dust particles. These generally known contaminant removing techniques are structured in a different configuration that is generally depicted in <CIT>. However, the product feeding mechanism has been improved from the metering device as shown and described in <CIT>.

The dedusting apparatus <NUM> is generally rectangular in shape and configuration. The outer housing <NUM> is preferably formed of a durable material such as steel or cast iron, and can be formed by casting techniques. The top of the housing <NUM> is formed with an attachment flange <NUM> that can be connected to a supply of particulate material (not shown) to pass through the infeed opening <NUM> in the attachment flange <NUM> for introduction into the vibratory feeding device <NUM>. Vibratory movement is provided by a pneumatically powered vibration generator <NUM> that is affixed to a feed pan <NUM> which receives particulate material passing through the infeed opening <NUM>. The vibration in the feed pan <NUM> induces movement of the particulate material toward an outlet opening <NUM> through which the particulate material passes into a receiving bowl <NUM> for feeding into the cleaning area <NUM>. The feed pan <NUM> is isolated from the attachment flange <NUM> by elastomeric isolators 17a, which prevent the transmission of vibration to the outer housing <NUM> and other components of the dedusting apparatus <NUM>.

The higher the pressure of the compressed air, the greater the throughput rate of particulate material will be. The particulate material flows out of the receiving bowl <NUM> and into a first chamber <NUM> of the cleaning area <NUM>. A series of ionizing pins <NUM> induce negative ions onto the individual pellets as the particulate material passes downwardly through a vertical portion <NUM> of the first chamber <NUM>. The particulate material then encounters a downwardly sloped floor <NUM> that creates a sloped portion <NUM> of the first chamber <NUM> to direct the ionized particulate material into the vertical Venturi chamber <NUM> which oriented parallel to, but offset from, the vertical portion <NUM> by the sloped portion <NUM>. A flow of cleaning air is fed upwardly, as will be described in greater detail below, through the Venturi chamber <NUM> so that the air will lift the dust particles and the debris, which are both significantly lighter that the individual pellets of the particulate material, thereby removing the dust and debris and cleaning the particulate material. The dust and debris laden air is then discharged from the cleaning area <NUM>, as will also be described in greater detail below. The cleaned particulate material then passes downwardly by gravity through the product discharge opening <NUM> at the bottom of the housing <NUM>.

The air flow through the Venturi chamber <NUM> is counter to the movement of the particulate material and is preferably generated by a compressed air operated vacuum generator <NUM> in the form of a line vac mounted on the conduit <NUM> supported from the housing <NUM> to create an air flow through the discharge opening <NUM> and to a conduit <NUM> passing from the cleaning area <NUM> to the dust collector <NUM> offset from the dedusting apparatus <NUM>. The interchangeable carryover deflector frame <NUM> has an extension member <NUM> that projects into housing <NUM> and aligns with the internal structure to modify the cross-sectional area of sloped portion <NUM> and to allow for varying grades of particulate material to be cleaned in the dedusting apparatus <NUM>. Further, the interchangeable carryover deflector frame <NUM> reduces carryover by projecting into the vertical section between the Venturi chamber <NUM> and discharge transition chamber 26a, thus deflecting any particulate material entrained in the air flow and directing it toward the discharge opening <NUM>.

The extension member <NUM> can be formed in varying thicknesses. Since the extension member <NUM> is integral with the interchangeable carryover deflector frame <NUM>, a changing of the desired thickness of the extension member <NUM> requires the interchangeable carryover deflector frame <NUM> to be replaced by one with a differently sized extension member <NUM>. The different thickness of the extension member <NUM> increases or decreases the cross-sectional area of sloped portion <NUM>. This allows the dedusting apparatus <NUM> to effectively clean particulate materials which have a smaller particle size and regular particle shape such as pelletized materials, as well as particulate material with larger particle size and irregular particle shape such as ground materials [for the recycling industry]. The larger-sized and irregular-shaped particulate material would otherwise create a blockage inside the cleaning area <NUM> of the dedusting apparatus <NUM>, as particulate material could not pass through to be cleaned. Without the ability to change the cross-sectional area of the sloped portion <NUM>, the dedusting apparatus <NUM> would be limited to a more narrow range of applications.

One skilled in the art will recognize that the location of the vacuum generator <NUM> could also be placed elsewhere in the housing <NUM> depending on the configuration of the housing <NUM>. The conduit <NUM> is in open communication with the Venturi chamber <NUM> at a discharge transition chamber 26a forming an upper portion of the Venturi chamber <NUM> to draw the dust and debris laden air from the Venturi chamber <NUM> into the conduit <NUM>. This vacuum draws air into the Venturi chamber <NUM> from the product discharge opening <NUM> at the bottom of the housing <NUM>.

The vacuum generator <NUM> receives compressed air for the operation thereof from a supply of compressed air connected to the compressed air connector 46a on the back side of the housing <NUM>, as best seen in <FIG>. The compressed air flows through an inlet air filter <NUM> and is fed into a Wye connector port <NUM> to divide the flow of compressed air into two paths, as best seen in <FIG>. A first flow path delivers compressed air to the compressed air operated vacuum generator <NUM> which converts the relatively high pressure, low volume air flow into a relatively low pressure, high volume air flow through the vacuum generator <NUM> to draw air through the discharge conduit <NUM> and induce a cleansing air flow through the Venturi chamber <NUM>. This first flow path is split again before the vacuum generator <NUM> to deliver a flow of compressed air to the ionizer pins <NUM> to where the compressed air flows around the ionizer pins <NUM> to force ions into the flow of particulate material passing through the vertical portion <NUM> of the first chamber <NUM>. The second flow path formed by the Wye connector port <NUM> delivers compressed air to the pneumatically powered vibration generator <NUM> to operate the vibratory feeding device <NUM>.

Under certain circumstances relating to the use of the compact dedusting apparatus <NUM>, the mounting flange <NUM> at the bottom of the housing <NUM> can be connected to a receiving device (not shown) that receives the cleaned product. The receiving device can seal against the mounting flange <NUM> which would prevent the vacuum generator <NUM> from drawing air through the product discharge opening <NUM>. In such circumstances, a filtered auxiliary port <NUM> is opened to allow air to be drawn through a clean air inlet port <NUM> positioned adjacent the product discharge opening <NUM> so that the air will enter the Venturi chamber <NUM> through the product discharge opening <NUM>.

The upward movement of cleaning air through the Venturi chamber <NUM> is moving at a selected velocity, which can vary depending on the particulate material being cleaned, to carry the dust and debris upwardly while allowing the particulate material to fall downwardly. Sometimes, however, particulate material gets entrained in the upward air flow, which is commonly referred to as carryover. Once the entrained air flow reaches the conduit <NUM>, which has a smaller cross-sectional area than the Venturi chamber <NUM>, the velocity of the air flow increases, which further entrains carryover particulate material. To allow carryover particulate material to drop back downwardly toward the product discharge opening <NUM>, the discharge transition chamber 26a of the Venturi chamber <NUM> is widened, as is best seen in <FIG>, to have a larger cross-sectional area than the Venturi chamber <NUM> below the sloped floor <NUM>, which causes the velocity of the air flow to decrease and provides an opportunity for the carryover particulate material to fall out of entrainment and drop toward the product discharge opening <NUM> before being drawn into the conduit <NUM>.

As is best seen in <FIG>, the conduit <NUM> extends through the vacuum generator <NUM> toward the dust collector <NUM>. Although the dust collector <NUM> can be formed in different configurations, including filters, scrubbers, and cyclones, among others, a compact dust collector <NUM> that spins the dust and debris laden air to separate the dust particles and debris therefrom is effective. The separated dust and debris is collected in a removable container <NUM> at the bottom of the dust collector <NUM>, while the cleaned air is discharged through vents <NUM> at the top of the dust collector <NUM>. In certain circumstances, the dust collector <NUM> can be located at a remote location where the discharge of the cleaned air is acceptable, and the conduit <NUM> extended to the remote location.

The placement of the vacuum generator <NUM> within the housing <NUM> enables the dust collector <NUM> to be remotely located without adversely changing the air flow through the dedusting apparatus <NUM>. For this reason, the conduit <NUM> terminates at an appropriate distance outside of the housing <NUM> so that the inlet conduit <NUM> of the dust collector <NUM> can be connected to the conduit <NUM> and secured by clamps <NUM>. In circumstances where the dust collector <NUM> is to be remotely located, the clamps <NUM> are disconnected to allow the dust collector <NUM> to be appropriately positioned while a length of conduit extension (not shown) is interconnected between the conduit <NUM> and the inlet conduit <NUM> to carry the dust and debris laden air to the remotely located dust collector <NUM>.

The housing <NUM> has a transparent glass window assembly <NUM> in the front of the housing <NUM> corresponding to the location of the Venturi chamber <NUM>. The transparent window assembly <NUM> is shaped to correspond to the shape of the sloped portion <NUM> of the first chamber and the lower vertical portion of the Venturi chamber <NUM> to permit the operator to observe the operation of the dedusting apparatus <NUM> so that appropriate adjustments can be made to the flow rate of the particulate material fed into the first chamber <NUM> or the rate of velocity of the air flow through the Venturi chamber <NUM> to provide an effective cleansing of the particulate material. As seen in exploded view of <FIG>, the transparent glass window <NUM> is trapped between a pair of gaskets <NUM> and sealed between an interchangeable carryover deflector frame <NUM> and a securement flange <NUM>. Insertion of fasteners <NUM> compresses the frames <NUM>, <NUM> and the gaskets <NUM> together to seal against the housing <NUM>.

Modification of the flow of particulate material and the flow of air through the Venturi chamber <NUM> and into the conduit <NUM> can be effected by the chamber extension member <NUM> that is formed to be an integral part of the interchangeable carryover deflector frame <NUM>. The thickness of the chamber extension member <NUM> can be changed by disassembling the window assembly <NUM> and swapping out the interchangeable carryover deflector frame <NUM> for a different configuration of a chamber extension member <NUM>. One skilled in the art will understand that a sensor <NUM>, shown in <FIG> and <FIG>, mounted below the discharge opening <NUM> can be used to detect particulate material collecting in the dedusting area <NUM>.

In operation, the compact dedusting apparatus <NUM> is positioned to receive a supply of particulate material into the infeed opening <NUM> at the top of the housing <NUM>. The particulate material is received through the infeed opening <NUM> by a vibratory feed pan <NUM> that directs the particulate material to an outlet opening <NUM> and, ultimately, to a cleaning area <NUM>. The particulate material is subjected to ionization by the ionization pins <NUM> located in the vertical portion <NUM> of the first chamber <NUM>. The ionized particulate material then lands on the sloped floor <NUM> to guide the particulate material into the Venturi chamber <NUM> where a flow of air coming upwardly through the product discharge opening <NUM> removes the dust particles and debris from the particulates so that the cleaned material can continue to fall by gravity downwardly and pass through the product discharge opening <NUM>. The presence of the interchangeable carryover deflector frame <NUM>, with the integral extension member <NUM>, keeps the flow of ionized particulate material directed to the Venturi chamber <NUM> to clean dust particles and debris therefrom.

The dust and debris laden air continues to flow upwardly to a discharge conduit <NUM> located at the top of a discharge transition chamber 26a of the Venturi chamber <NUM>. Between the lower vertical portion of the Venturi chamber <NUM> and the discharge conduit <NUM>, the discharge transition chamber 26a of the Venturi chamber <NUM> expands in size and cross-sectional area so that the velocity of the air flow is reduced to allow any carryover pellets to drop out of entrainment in the air flow before moving into the discharge conduit <NUM>. The dust and debris laden air continues through the vacuum generator <NUM> to the dust collector <NUM>, which can be located at a remote location and connected to the conduit <NUM> by a supplemental conduit (not shown). Since the vacuum generator <NUM> is located within the housing <NUM>, the dust collector <NUM> can be positioned remotely from the dedusting apparatus <NUM> without deteriorating the flow of air through the Venturi chamber <NUM>.

The housing <NUM> has an opening therein covered by a transparent window <NUM>, which could be glass, polycarbonate, acrylic or other clear material, mounted between a pair of gaskets <NUM> and secured to the housing <NUM> by fasteners <NUM> sealing the gaskets <NUM> between the interchangeable carryover deflector frame <NUM> and a securement flange <NUM>, as described in greater detail above, so that the operator can observe the operation of the dedusting area <NUM> and make operational adjustments as needed. When the lower mounting flange <NUM> is sealed against a receiving device (not shown) the flow of cleaning air can pass through a clean air inlet port <NUM> that extends from the side of the housing <NUM> to an opening in said lower mounting flange adjacent the product discharge opening <NUM> so that air can be drawn through the clean air inlet port <NUM> and then upwardly through the product discharge opening <NUM> to and through the Venturi chamber <NUM> and remove dust and debris from the particulate material.

It will be understood that changes in the details, materials, steps and arrangements of parts, which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles of the invention within the scope of the claims.

The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description may be employed in other embodiments without departing from the scope of the claims.

Claim 1:
A dedusting apparatus (<NUM>) for cleaning contaminants from particulate material, comprising:
a housing (<NUM>) defining a cleaning area (<NUM>) for removing contaminants from particulate material to create cleaned particulate material and a product discharge opening (<NUM>) through which cleaned particulate material can be discharged from said housing;
an infeed apparatus (<NUM>) located at an upper portion of said housing (<NUM>) to receive a supply of particulate material, said infeed apparatus including attachment flange (<NUM>) having an infeed opening (<NUM>) therein for the passage of particulate material to be cleaned of contaminants,
a Venturi chamber (<NUM>) positioned to receive particulate material passing through said infeed opening and to remove contaminants from the particulate material by a flow of air passing upwardly through the product discharge opening and into the Venturi chamber, while cleaned particulate material falls through the product discharge opening; and
a discharge conduit (<NUM>) positioned above the Venturi chamber (<NUM>) to receive dust and debris laden air moving upwardly from said Venturi chamber, said discharge conduit moving said dust and debris laden air remotely from said cleaning area (<NUM>),
characterized in that
said infeed apparatus further including a vibratory feed pan (<NUM>) urging said particulate material to an outlet opening in said vibratory feed pan and into said cleaning area;
a vibration generator (<NUM>) operably connected to said vibratory feed pan (<NUM>) to induce vibrations therein, the rate of flow of particulate material into said cleaning area being dependent upon the magnitude of the vibrations of the feed pan (<NUM>) induced by the vibration generator (<NUM>);
a connector port (<NUM>) is provided for dividing air from a compressed air supply connectible to the apparatus into two flows, a first flow serving to cause the upward air flow into the Venturi chamber and a second flow serving to power the vibration generator (<NUM>) to determine the rate of flow of particulate material into the cleaning area.