SEPARATION OF COMPONENTS OF MIXTURES

Abstract: An apparatus for separating the components of a mixture, the mixture is admitted to a first inlet which communicates with a working region which may be defined by a cylindrical tube. A fluid under pressure is admitted to a chamber through a second inlet. The chamber also communicates with the working region. The fluid forms a spiralling flow which draws the mixture into the working region in the form of a vortex. In the apparatus, the chamber communicates with the working region by way of a throat, and the mixture is conveyed from the working region along an outlet.

Description: SEPARATION OP COMPONENTS OF MIXTURES FIELD OF THE INVENTION This invention relates to an apparatus for separating the components of a mixture, as in the de-watering of slurries such as sewage or coal slurries, and the removal of moisture from sludges, animal manure and other solid materials. BACKGROUND OF THE INVENTION Conventional methods of removing water from slurries generally consume large amounts of energy. For example, one known method involves the application of large quantities of heat in order to vaporize the water from the slurry. The invention aims to provide a simpler and more efficient apparatus. Published British application (GB-2 268 418-A) discloses a prior drying apparatus of the same general type as the present invention. The prior appratus is illustrated in Figs. 1-4 of the drawings of the present application, and is described in detail hereinafter. The apparatus improved upon the prior art by providing superior drying without the use of heated air. While the prior apparatus constituted an improvement over previous drying apparatus, in some circumstances it was still unable to produce the drying needed and did not permit a sufficiently high rate of throughput. It is believed that by increasing the kinetic energy of the drying air within the working tube according to the present invention, improved drying is achieved. Referring to Figs. 1-4, the prior art apparatus is shown to comprise an open-ended cylindrical outer sleeve or casing 6 having at each end a respective outer, radial, annular flange 8 and 10 for attachment to an end piece 3 and an inner sub-assembly 4. As can be seen from Fig. 4, the casing 6 includes an opening 7 which communicates with an inlet pipe 9 so as to provide an inlet for a pressurized fluid. The sub-assembly 4 includes a cylindrical tubular structure or working tube 12 which extends axially into the casing 6 and is screwed at its downstream end to the inner circumference of a ring 14. The terms "downstream" and "upstream" as used herein refer to the direction D of flow of matter through the working tube 12. The ring 14 is, in turn, bolted onto the flange 10 by means of a plurality of nuts and bolts such as at 16 which extend through corresponding pairs of aligned bores in the ring 14 and flange 10. The downstream end of the working tube 12 is also connected to an outlet tube 18 of the same internal diameter as the working tube by means of a screw threaded connection. The opposite end of the working tube 12 includes a bevel 20 at an angle of 45° with the circumferential outer surface of the working tube 12. It is to be understood that the angle of the bevel 20 may be other than 45° and still fall within the scope of the present invention. The end piece 3 comprises a tubular mounting collar 22 having a radial flange 24 bolted to the flange 8 in a similar fashion to the connection between the ring 14 and flange 10. The mounting collar 22 includes a central internally screw threaded aperture 26 which is engaged by a corresponding screw-threaded portion 28 of an inlet tube 30 to allow adjustment of the axial position of the tube 30 relative to the working tube 12. The tube 30 includes an end connector 32 at its upstream end adapted to be connected to a supply line for the mixture to be processed and extends into the interior of the casing 6 as far as the region of the end 20 of the working tube 12. The working tube 12 is spaced from the casing 6 and the end piece 3 so as to define an annular chamber 34 surrounding and generally co-axial with the working tube. The chamber 34 communicates with the inlet pipe 9 and with the inner volume of the working tube 12 through a throat defined between the downstream end of the inlet tube 30 and the bevel 20 of the working tube. It will be seen that the effective width of the throat may be varied by appropriate axial movement of the tube 30. The pipe 9 is connected to a pump (not shown) which, in use, supplies atmospheric air to the chamber 34 at a pressure of 1.5-4 pounds per square inch and a speed of 8- 10 thousand feet per minute. Since the inlet pipe 9 admits air to the chamber 34 in a tangential direction, that air forms a spiralling flow in the chamber 34 with a mean axial component in the direction of the end 20 of the working tube 12. The air thus travels along the chamber 34 until it reaches the throat formed between the bevel 20 and the tube 30. As the air passes through the throat it accelerates, creating a region of low pressure in the region of the throat, and then forms a vortex in the working tube 12, which vortex travels toward the outlet pipe 18. A slurry, for example coal slurry, is fed through the tube 30 towards the end 20 of the working tube 12, where the zone of low pressure tends to draw the slurry into the working tube 12. It is believed that as the air passes through the throat at the end 20 of the working tube 12, it undergoes an adiabatic expansion, causing a substantial drop in temperature. This makes the apparatus particularly useful for de-watering coal slurries, in which high temperatures may lead to a risk of explosion. In one specific example of the apparatus, the distance between the axis of the inlet pipe 9 and the flange 10 is 4.6 inches; the external diameter of the casing 6 is 10 inches, the external diameter of the working tube 12 is 6 inches; the diameter of the flanges 8, 10, 24 and of the ring 14 is 14.6 inches; and the range of axial adjustment of the tube 30 is such that the position of the downstream end of the tube 30 may be level with the apex of the end 20 of the working tube 12 or may project into the working tube by a distance of up to 1 inch beyond the bevel 20 or may be at any intermediate position. SUMMARY OF THE INVENTION Among the several objects and features of the present invention may be noted the provision of apparatus for separating the components of a mixture which is energy efficient; the provision of such apparatus which is readily adjustable for drying mixtures of various composition and liquid content; the provision of such apparatus which is capable of rapidly processing large amounts of the liquid; and the provision of such apparatus which is economical to manufacture and easy to use. According to one aspect of the invention, apparatus for separating the components of a mixture comprises a casing defining a chamber having a central axis and a tubular structure defining a working region. A first inlet admits the mixture into an upstream end of the working region and a second inlet for admitting pressurized fluid into the chamber. The fluid admitted into the chamber from the second inlet moves in a spiralling fashion from the second inlet toward the first inlet. The upstream end of the working region communicates with the chamber by way of a throat through which the spiralling fluid is drawn into the working region. The chamber decreases in cross sectional dimension generally from the second inlet toward the first inlet thereby to increase the velocity of the fluid in the chamber as it approaches the throat of the working region. A dried component may be separated from the remainder of the mixture by any convenient known means, such as a cyclone separator. In its normal application for the de-watering of slurries, the mixture has a solid component which is the desired component, but it will be appreciated that the other component may be readily condensed and recovered if it is the desire component. Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the prior art apparatus; FIG. 2 is a longitudinal section of the apparatus of Fig. 1; FIG. 3 is a section on the line III-III of Fig. 1; FIG. 4 is a section on the line IV-IV of Fig. 1; FIG. 5 is a side elevation of apparatus of a first embodiment of the present invention; FIG. 6 is a longitudinal section of the apparatus of Fig. 5; FIG. 7 is an enlarged, fragmentary view of Fig. 6; FIG. 8 is a section on the line VIII-VIII of Fig. 6; FIG. 9 is a fragmentary section on line IX-IX of Fig. 5; FIG. 10 is a section on the line X-X of Fig. 5 and showing an imaginary projection of an opening of a second inlet of the apparatus; FIG. 11 is an enlarged, fragmentary view similar to Fig. 7, but showing a second embodiment of the present invention having an auger to feed the mixture; and FIG. 12 is a schematic of a mixture separating system including the apparatus. Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figures 5-10, improved apparatus of the present invention is shown. A casing of the apparatus (generally indicated at 106) includes a frustoconically shaped upstream portion 106A and a cylindrically shaped downstream portion 106B. The apparatus is supported by two saddles 150 under the casing 106 which cradle the casing. As shown in Fig. 6, the cross sectional dimension of the upstream portion 106A of the casing decreases generally from a first inlet pipe 109 toward a first inlet tube assembly (generally indicated at 130) . A working tube 112 is surrounded by a chamber 134 and shares a common central axis C. The working tube 112 ("tubular structure") defines the inner periphery of the chamber 134 and is cylindrical so that the chamber is constricted toward the first inlet tube assembly 130 because of the decreasing cross sectional dimension of the upstream portion of the casing 106A. It has been found that the constriction of the chamber 134 toward the inlet end results in high air velocities within the working tube 112 which produces greater drying and permits the mixture to be fed at a higher rate through the apparatus. Inside the casing 106, the working tube 112 includes an outer cylindrical jacket 112A surrounding a cylindrical inner portion 106B of the working tube. The outlet tube 118 is the extension of the inner portion 112B of the working tube through a ring 114 to outside of the casing 106. At their upstream ends, the jacket 112A and inner portion 112B define an annular opening in which is received an annular throat end piece, generally indicated at 152. As shown in Fig. 7, the throat end piece 152 includes an end face having a bevel 120. The upstream end of the jacket 112A lies in an annular recess 152A at the downstream end of the throat end piece, and a portion 152B of the end piece upstream from the recess is flush with the cylindrical exterior surface of the jacket. In this way a smooth exterior surface of the working tube 112 is presented which does not substantially interfere with the spiralling flow of air in the chamber 134 around the working tube. Referring now particularly to Figs. 7 and 8, an annular end surface 154 generally adjacent to the upstream end of the working tube 112 facilitates redirection of the spiralling flow of air from an upstream direction in the chamber to a downstream direction in the working tube. The end surface 154 does not lie in a plane which is perpendicular to the direction of flow D of matter through the working tube, but is shaped to facilitate changing the direction of flow of the air. Instead of permitting the pressurized fluid to impact against the inlet end of the chamber 134 and move downward, the end surface 154 guides the air toward the throat. In the preferred embodiment, the end surface 154 is defined on the exterior surface of a throat member (generally indicated at 156) located in the chamber 134 generally adjacent the upstream end of the working tube 112. The throat member 156 extends axially inward from the inlet end of the chamber toward the working tube 112. The throat is defined between the end surface 154 ("first annular surface") on the throat member 156 and the bevelled end face 120 ("second annular surface") . Both the end surface 154 and the bevelled end face 120 slope radially inward in a downstream direction with respect to the central axis C of the working tube 112. The throat member 156 is movable to control the effective width of the throat, through which the inner portion 112B of the working tube communicates with the chamber 134. The inlet tube assembly 130 includes a first feed tube 130A and a second feed tube 130B. The throat member 156 extends around the second feed tube 130B and is sealingly, but slidingly engaged with the second feed tube by a pair of O-rings 158 received in internal, annular grooves in the throat member. The throat member 156 is fixedly connected to a tubular mounting collar (indicated generally at 122) sealingly and slidingly received in a central opening of a mounting ring 124 bolted to an annular flange 108 of the casing 106. Sealing engagement of a mounting collar 122 in the central opening is achieved by another pair of O-rings 162 received in annular grooves on the internal diameter of a mounting ring 124. The mounting collar 122 includes a cylindrical upstream portion 122A and a cylindrical downstream portion 122B having a larger diameter than the upstream portion. As shown in Fig. 9, the downstream portion 122B has four tabs 164 extending radially outwardly to respective threaded positioning bolts 166 fixedly connected to the mounting ring 124. Each tab 164 has a slot 164A at its radially outward end which receives a corresponding positioning bolt 166. The tab 164 is captured on the positioning bolt 166 between nuts 168 threaded onto the bolt on opposite sides of the tab (Fig. 7) . A washer 170 is interposed between each nut 168 and the tab 164. The axial position of the nuts 168 on the positioning bolts 166 can be changed by threading the nuts in an axial direction on the bolts, permitting the axial position of the mounting collar 122 to be changed. The throat member 156 is movable conjointly with the mounting collar 122 such that its axial position in the chamber 134 and spacing of the conical end surface 154 from the bevelled end face 120 of the working tube 112 may be changed. Axially inward repositioning of the throat member 156 reduces the cross sectional area of the throat in communication with the chamber 134, while axially outward repositioning of the throat member increases the cross sectional area of the throat in. communication with the chamber. The second feed tube 130B passes through the mounting collar 122 into the chamber 134, and is releasably secured to the mounting collar by a first annular cap 172 and first elastomeric ring 174. The first cap 172 has internal threads adapted for threaded engagement with external threads on the upstream portion 122A of the mounting collar 122. The elastomeric ring 174 is disposed around the second feed tube 130B and partially within the annular open end of the upstream portion 122A. The first cap 172 may be screwed onto the upstream portion 122A to compress the elastomeric ring 174 against the second feed tube 130B with the ring sealing with and gripping the exterior surface of the second feed tube to hold it in fixed relation to the mounting collar 122. As shown in Fig. 7, the first feed tube 130A passes through the second feed tube 130B and the mounting collar 122, and has fins 176 which are engageable with the second feed tube to locate the first feed tube within the second feed tube. The upstream end of the second feed tube 13OB is threaded and receives a second internally threaded annular cap 178 for compressing a second elastomeric ring 180 against the exterior surface of the first feed tube 130A to seal with and grip the first feed tube and hold it in fixed relation to the second feed tube and mounting collar 122. Thus, the first feed tube 130A can be positioned axially relative to the working tube 112 and throat member 156 by unscrewing the second cap 178 from the threaded end of the second feed tube 130B to release the grip of the second elastomeric ring 180. The first feed tube 130A is then free to slide axially relative to the working tube 112 and the throat member 156 to position the downstream end of the first feed tube in the optimal location for the particular type of mixture. The first and second caps 172, 178 and elastomeric rings 174, 180 constitute "holding means". The mounting ring 124, mounting collar 122, and first and second caps 172, 178 and elastomeric rings 174, 180 constitute "mounting means". The pipe 109 introducing drying air into the chamber is located at the outlet end of the casing 106, and is formed as part of the casing. As shown in Fig. 10, the pipe 109 is secured to a feeder pipe 109A leading to a source of air under pressure (described below) . A temperature gage 182 and pressure gage 184 are provided on the pipe 109 to monitor the pressure and temperature of the air entering the chamber 134. As may be seen in Fig. 7, the pipe 109 has an opening 109B positioned in the chamber for delivering drying air into the chamber 134 in a direction which is generally circumferential to the chamber. The opening 109B and working tube 112 are arranged such that there is not substantial impact of fluid exiting the pipe 109 into the chamber 134 against the working tube. More specifically, an imaginary projection P (Fig. 10) of the opening 109B into the chamber 134 would not intersect a plane parallel to the longitudinal axis LA of the projection and including the central axis C of the working tube. In fact, less than one quarter of the projected opening P lies on the jacket 112A of the working tube. Thus, the path of the air admitted into the chamber from the pipe 109 does not substantially intersect the working tube 112. In this way, the flow is not split by the working tube 112 and undesired turbulence is not introduced into the flow of air within the chamber 134. Instead, the flow of air is directed by the tubular/frustoconical interior walls of the casing 106 into the desired spiralling flow. The casing 106, working tube 112 and throat member 156 are made of a suitable corrosion resistant material such as 304 stainless steel. The casing 106 is electro-polished to a mirror finish on its interior surface and the working tube 112 is similarly polished on the exterior surface of the jacket 112A and interior surface of the inner portion 112B to facilitate free spiralling flow of air within the chamber 134 and working tube. The end surface 154 defined on the throat member 156 is also electro-polished. A second embodiment of the apparatus shown in Fig. 11 discloses the purpose of the second feed tube 130A of the second embodiment. Parts of the apparatus of the second embodiment corresponding to similar parts of the first embodiment will be identified by the same reference numerals. Certain mixtures do not flow readily and are not easily pumped through the first feed tube 130A of the second embodiment. In that event, the first feed tube 130A can be removed entirely, and an auger 300 can be installed in the second feed tube 130B to feed the mixture into the working tube 112. Once in the working tube, the mixture is caught up in the vortex as before. The second feed tube 13OB can be positioned relative to the working tube 112 and throat member 156 by releasing the first cap 172 and elastomeric ring 174 and sliding the second feed tube axially. It will be understood by those of ordinary skill in the art that if the apparatus will be always used to dry one type of mixture, it will be unnecessary to provide both a first feed tube 130A and a second feed tube 13OB. Referring now to Fig. 12, a system for drying a mixture using the apparatus of the present invention is shown to comprise a feed hopper 186 which holds the mixture (e.g., a coal slurry) requiring removal of moisture. The mixture moves from the feed hopper 186 into the first feed tube 130A by action of gravity, a pump 188 and/or under the vacuum being drawn in the working tube 112. Drying air is drawn into the system through a filtering and muffling tower 190 by a pump 191. The pump 191 is preferably selected, based on the size of the apparatus, to achieve an air flow through in the working tube 112 in the range of about 180.to 185 feet per second. Air leaving the pump 191 passes through a discharge muffling tower 192 before entering the feeder pipe 109A leading to the casing 106. The air exiting the pipe 109 in the casing 106 is deflected by the interior walls of the casing into a spiralling flow travelling toward the first inlet tube assembly 130. As shown in Fig. 7, the spiralling flow of air is constricted by the upstream portion 106A of the casing as it travels toward the inlet end of the chamber 134. At the inlet end of the chamber 134, the spiralling flow engages the sloped end surface 154 of the throat member 156 which facilitates turning the direction of flow from generally upstream in the chamber to downstream in the working tube 112. The spiralling air enters the working tube 112 through the throat which has been regulated by the throat member 156 to achieve the constriction needed to produce the velocity and air mass flow in the working tube for the particular mixture. The operation of the apparatus is further adjusted for the particular mixture by axial location of the first feed tube 130A relative to the working tube 112. The violent spiralling action in the working tube 112 breaks apart and mixes the material in the mixture to produce uniform drying. The dried mixture and water exit the casing 106 and enter the outlet tube 118 to pass to a cyclone separator 193 (or other suitable separator device) which separates the water from the denser solid components. The water and any fine particulate matter entrained therein pass out of the top of the separator through a pipe 194 to a bag house 195 for filtering the particulates out of the air before it is discharged to the atmosphere. The desired component (e.g., coal) is recovered through an outlet 196 at the bottom of the separator 193. In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims: CLAIMS 1. Apparatus for separating the components of a mixture comprising, a casing defining a chamber having a central axis, a tubular structure defining a working region, a first inlet for admitting the mixture into an upstream end of the working region, a second inlet for admitting pressurized fluid into the chamber, the fluid admitted into the chamber moving in a spiralling fashion from the second inlet toward the first inlet, the upstream end of the working region communicates with the chamber by way of a throat through which the spiralling fluid is drawn into the working region, characterized in that : the chamber decreases in cross sectional dimension generally from the second inlet toward the first inlet thereby to increase the velocity of the fluid in the chamber as it approaches the throat of the working region. 2. Apparatus according to claim 1 wherein said chamber is annular in shape, and wherein the tubular structure is generally coaxial with and surrounded by the annular chamber, characterized in that the cross sectional dimension of the casing decreases generally from the second inlet toward the first inlet. 3. Apparatus according to claim 1 characterized by an end surface generally adjacent the upstream end of the working region which does not lie in a plane perpendicular to the direction of flow of the mixture through the chamber, the end surface being shaped to facilitate redirection of the spiralling fluid flow as it passes from the chamber to the working region. 4. Apparatus according to claim 3 characterized in that the end surface comprises a first annular surface around the first inlet, the first annular surface cooperating with a second annular surface on the tubular structure at the upstream end of the working region to define the throat. 5. Apparatus according to claim 4 characterized in that the first and second annular surfaces slope radially inwardly in downstream direction with respect to a central axis of the tubular structure defining the working region. 6. Apparatus according to claim 1 wherein the first inlet comprises a tube, and characterized in that the apparatus further comprises an annular throat member encircling the first inlet tube, and means for mounting the throat member for axial movement toward and away from the upstream end of the tubular structure. 7. Apparatus according to claim 6 characterized in that the first inlet tube is axially adjustable relative to the throat member and relative to the tubular structure defining the working region, and further characterized by means for holding the first inlet tube in a selected position of axial adjustment relative to the throat member and tubular structure defining the working region. 8. Apparatus as set forth in claim 7 characterized in that said mounting means comprises a tubular mounting collar through which the first inlet tube is received, and in that said holding means releasably grips an exterior surface of the first inlet tube and is adapted to hold the first inlet tube in a fixed position relative to the mounting collar. 9. Apparatus as set forth in claim 8 characterized in that said holding means comprises an elastomeric ring around the first inlet tube and an annular cap around the first inlet tube adapted for threaded attachment to the mounting collar of said mounting means, the cap being adapted to compress the elastomeric ring into gripping engagement with the first inlet tube upon attachment of the cap to the mounting collar. 10. Apparatus as set forth in claim 1 wherein the second inlet comprises a second inlet tube, characterized in that the second inlet tube communicates with the chamber via an opening which, as projected inwardly into the chamber in the direction of fluid flow through the opening, projects less than one-quarter of the total projected area of the opening onto the tubular structure. 11. Apparatus for separating the components of a mixture comprising, a casing defining a chamber having a central axis, a tubular structure defining a working region, a first inlet for admitting the mixture into an upstream end of the working region, a second inlet for admitting pressurized fluid into the chamber, the fluid admitted into the chamber moving in a spiralling fashion from the second inlet toward the first inlet, the upstream end of the working region communicates with the chamber by way of a throat through which the spiralling fluid is drawn into the working region, characterized by: an end surface generally adjacent the upstream end of the working region which does not lie in a plane perpendicular to the direction of flow of the mixture through the chamber, the end surface being shaped to facilitate redirection of the spiralling fluid flow as it passes from the chamber to the working region.

Inventors: CARRA ALEX R, MCKEE PATRICK C, ROBERTSON BROOKS A, CARRA, ALEX, R., MCKEE, PATRICK, C., ROBERTSON, BROOKS, A.
Applicants: PRECISION STAINLESS INC, PRECISION STAINLESS, INC.
Application year: 1995
Main classification: B01D1
IPC codes: B01D1, F26B17