Title of Invention

MICROFINES PNEUMATIC FINE CLASSIFIER FOR THE CLASSIFICATION OF FINE POWDERS

Abstract

Microfines pneumatic fine classifier for the classification of fine powders comprising a vertically oriented chamber having an upper linear portion and a lower U-shaped portion, a cluster of nozzle venturi system provided at the top of the chamber, through the nozzles of which compressed air is sent into the linear portion, the suction ports of the nozzle-venturi being open to atmosphere enable the atmospheric air also to get sucked into the system and provide a uniform laminar flow of air therein; a pneumatic feeder, provided with a rotational feed entry arrangement, disposed at the junction of the upper and lower portions of the chamber, the said lower portion of the chamber ending in a plurality of channels for carrying away the classified fractions of the powders.

Full Text

This invention relates to microfines pneumatic fine classifier for the classification of fine powders. As the boundaries of fine particles get redefined to sub-micron ranges and as industries become increasingly aware of the advantages of ultra-fine particles for their manufacturing methods and processes the classification of such powders into different size fractions has become a necessity. This invention proposes microfines pneumatic fine classifier which fulfills the above need, the mechanism of classification being based on distinct trajectories taken by the particles while traversing in a uniform fiow stream of air, based on their size and density. Various features of this invention will be apparent from the following description thereof Microfines pneumatic fine classifier for the classification of fine powders, according to this invention, comprises a vertically oriented chamber having an upper linear portion and a lower U-shaped portion; a cluster of nozzle-venturi system provided at the top of the chamber, through the nozzles of which compressed air is sent into the linear portion, the suction ports of the nozzle-venturi being open to atmosphere so as to enable atmospheric air also to get sucked into the system and provide a uniform laminar flow of air therein; a pneumatic feeder provided with a rotational feed entry arrangement disposed at the junction of the upper and lower portions of the chamber, the said lower portion of the chamber ending in a plurality of channels for carrying away the classified fractions of the powders. This invention will now be described with reference to the accompanying drawings which illustrate, by way of example, in the single figure therein, one of the possible embodiments of the classifier proposed therein. A vertically oriented chamber C has an upper linear portion L and a lower Li-shaped portion U. A cluster of nozzle-venturi system N is provided at the top of the chamber through the nozzles of which compressed air is send in. The suction ports of the nozzle venturi system are open at M so that as much amount of atmospheric air also gets sucked into the system and moves through the linear portion of the chamber which has sufficient length to provide a uniform laminar flow of air therein as indicated by the arrow A. A pneumatic feeder F, provided with a rotational feed entry arrangement R, is disposed at the junction of the upper and lower portions of the chamber , the said lower portion ending in a plurality of channels D to carry the classified fractions of the powder. The rotational feed entry arrangement, in the embodiment under discussion, consists of a helical passage P which provides the rotational entry for the air-powder mixture into the lower portion U of the chamber. This arrangement imparts the requisite centrifugal force to the particles. As the air-material mixture enters the lower portion U of the chamber, it is assisted by the laminar flow of air, also entering the lower portion U of the chamber from the upper portion L of the chamber, for further travel of the particles towards the channels D at the end of the U-shaped lower portion U. The particles in their travel towards the said chaimels negotiates the U-shaped bend at J of the lower portion U of the chamber. Based on the centrifugal force imparted to the said particles due to rotation and the distinct trajectories they will take while traversing in a uniform laminar flow stream of air, they classify themselves into different grades of fineness, to enter different channels D, the finest fraction entering the first channel D1 and the coarsest in D4 with the two intermediate fractions in D2 and D3. Various fractions from these channels are taken to separate high efficiency cyclone separators for separation of the classified fines from air. Outlet of all the cyclone separators are connected to a common port and to a filter bag so that the downstream resistance for all the cyclone separators remain the same. For facilitating smooth entry of the classified fractions into the different channels without any rebounding, the partition walls of the channels are knife-edged at K. The terms and expressions in this specification are of description and not of limitation, there being no intention in the use of such terms and expressions of excluding any equivalents of the features illustrated and described; but it is understood that various other embodiments of the mill proposed herein are possible without departing from the scope and ambit of this invention. We Claim; 1. Microfines pneumatic fine classifier for the classification of fine powders comprising a vertically oriented chamber having an upper linear portion and a lower U-shaped portion; a cluster of nozzle venturi system provided at the top of the chamber, through the nozzles of which compressed air is sent into the linear portion, the suction ports of the nozzle-venturi being open to atmosphere enabing the atmospheric air also to get sucked into the system and provide a uniform laminar flow of air therein; a pneumatic feeder, provided with a rotational feed entry arrangement, disposed at the junction of the upper and lower portions of the chamber, the said lower portion of the chamber ending in a plurality of channels for carrying away the classified fractions of the powders. 2. Microfines pneumatic fine classifier as claimed in Claim 1 wherein the rotational feed entry arrangement consists of a helical passage. 3. Microfines pneumatic fine classifier as claimed in Claim 1 or 2 . wherein the channels are partitioned by knife-edged plates. 4. Microfines pneumatic fine classifier for the classification of fine powders, substantially as herein described with reference to, and as illustrated in, the accompanying drawings.

Documents:

534-mas-98 abstract.pdf

534-mas-98 claims duplicate.pdf

534-mas-98 claims.pdf

534-mas-98 correspondence-others.pdf

534-mas-98 correspondence-po.pdf

534-mas-98 description (complete) duplicate.pdf

534-mas-98 description (complete).pdf

534-mas-98 drawings.pdf

534-mas-98 form-1.pdf

534-mas-98 form-19.pdf

534-mas-98 form-26.pdf