WO2005035131A1 - Appareil et procede destines a la separation en continu des particules magnetiques et des fluides de particules non magnetiques - Google Patents

Appareil et procede destines a la separation en continu des particules magnetiques et des fluides de particules non magnetiques Download PDF

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Publication number
WO2005035131A1
WO2005035131A1 PCT/US2004/033387 US2004033387W WO2005035131A1 WO 2005035131 A1 WO2005035131 A1 WO 2005035131A1 US 2004033387 W US2004033387 W US 2004033387W WO 2005035131 A1 WO2005035131 A1 WO 2005035131A1
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WIPO (PCT)
Prior art keywords
magnetic
separation chamber
magnetic separator
particles
port
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PCT/US2004/033387
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English (en)
Inventor
Robin R. Oder
Russell E. Jamison
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Exportech Company, Inc.
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Priority to US10/574,859 priority Critical patent/US7658854B2/en
Publication of WO2005035131A1 publication Critical patent/WO2005035131A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03C1/00—Magnetic separation
    • B03C1/02—Magnetic separation acting directly on the substance being separated
    • B03C1/035—Open gradient magnetic separators, i.e. separators in which the gap is unobstructed, characterised by the configuration of the gap
    • B03C1/0355—Open gradient magnetic separators, i.e. separators in which the gap is unobstructed, characterised by the configuration of the gap using superconductive coils

Definitions

  • This invention relates to the art of continuous separation of magnetic particles from a non-magnetic fluid; more specifically it relates to the continuous separation of such types as they pass through a uniform applied magnetic field; and more specifically it relates to the continuous separation of sub-micron size magnetic particles from viscous flows such as the continuous separation of magnetic catalysts from Fischer-Tropsch wax at operating temperature and pressure or separation of particles of wear from transformer oil or spent engine oil and other non-magnetic hydrophobic or hydrophilic liquids.
  • U.S. Patent No. 4,605,678 describes the application of high gradient magnetic separation technology to separation of iron catalysts employed in Fischer-Tropsch synthesis.
  • This batch operated technology originally developed for separation of very low concentration and weakly magnetic particles from kaolin clay [R. R. Oder and C. R. Price, "Brightness Beneficiation of Kaolin Clays by Magnetic Treatment,” TAPPI 56, 75 (1973); R. R. Oder, “High Gradient Magnetic Separation: Theory and Applications,” IEEE Transactions on Magnetics, Vol MAG-12, No. 5, pp. 418-425 (September, 1976)] is not well suited to the Fischer-Tropsch application because of the strongly magnetic character of the catalyst particles employed.
  • the concentration of these particles in the wax-rich overflow from the reactors employed is so high that the batch process and quasi-continuous versions of it are plugged with the catalyst too rapidly for commercial application. Batch processes, no matter what the nature of the separation mechanism, are not preferred for separating high concentrations of ultra-fine sized particles from high throughput commercial process flows.
  • U.S. Patent No. 5,868,939 describes a continuous magnetic separator for breaking emulsions in which a magnetic additive is placed in one phase of the emulsion.
  • the emulsion containing the magnetic additive is made to flow through a vessel containing magnetized rods.
  • the magnetic component of the emulsion coalesces and is drawn to the surfaces of the rods by the localized gradient magnetic fields produced by the rods.
  • the magnetic droplets captured by the rods then flow down the surface of the rods to a pool of coalesced material in the bottom of the separator.
  • the two immiscible phases are taken from the separator in separate streams.
  • WIPO Application No. PCT/US03/02877 describes a continuous magnetic separator for separating magnetic particles from viscous flow in which at least one magnetizable rod is located inside and aligned along the length of a separation chamber to attract magnetic particles from flow around the rods.
  • the rods can be permanent magnets which are magnetized transverse to the rod lengths or can be similarly aligned magnetic rods which are magnetized by an externally applied magnetic field.
  • the magnetic particles are suspended as a slurry in a non-magnetic fluid which enters the chamber between the top where an exit port is located for removing fluid which is low in particle concentration and the bottom of the chamber where an exit port is located for removing a concentrated stream of magnetic particles.
  • the magnetic particles agglomerate by self attraction in the magnetic field surrounding the rods.
  • the agglomerates form chains along the field lines and are attracted to the surfaces of the rods. Fluid flow and gravity drag the chained particles down the rods to the exit port at the bottom of the separation chamber. External means are employed to assure that the greater portion of the mass flow exits the bottom of the separation chamber.
  • the lower ends of the rods and the bottom edge of the magnet generally terminate abruptly at the same elevation in this invention so that there is a large magnetic field gradient at the exit port which tends to hold the magnetic particles inside the separation chamber. This results in a possible buildup of catalyst particles in the bottom of the chamber which can lead to plugging.
  • U.S. Patent Nos. 4,605,678 and 5,868,939 and WIPO Application No. PCT/US03/02877 employ the strong field gradients near magnetized surfaces placed in the way of flows containing the magnetic particles to be separated from the flow. While this results in strong magnetic forces for capture, it can also make continuous operation problematical because of the tendency of solid particles to stick and not to release from the magnetized capture surfaces.
  • the invention revealed here overcomes this limitation by use of a separation chamber which contains no magnetic capture elements and which employs means to lessen magnetic forces which would hold the particles in the chamber resulting in plugging.
  • the method and apparatus of this invention has achieved filtration rates in continuous throughput which are over 60 times greater than that of the dynamic settler at the same catalyst concentration.
  • the throughput limitation of the dynamic settler is impractical because of the high temperature and pressure employed in the Fischer-Tropsch synthesis.
  • the size and number of dynamic settlers alone would make the method cost prohibitive.
  • the object of the invention is to provide an improved process and apparatus for true continuous separation of micron and sub-micron sized magnetic particles from flowing non-magnetic viscous fluids at elevated temperature and pressure.
  • the particles can be catalyst particles such as precipitated iron catalyst in Fischer-Tropsch wax or particles of wear such as are found in spent engine oil and other non-magnetic hydrophobic and hydrophilic liquids.
  • the present invention includes a device and a method for using the device to continually separate magnetic particles from the non-magnetic fluid in which they are slurried.
  • the particles can be discrete or agglomerates or clusters of particles and can be of very broad particle size and density ranges.
  • Micron sized ferrimagnetic agglomerates containing particles so small that they exhibit superparamagnetism have been separated from viscous diamagnetic fluids at 500°F using this apparatus and method.
  • the upper and lower bounds of particle size which can be separated by this apparatus are not known at this time.
  • the method is unaffected by pressure and a requirement is that the applied magnetic field be reasonably uniform inside the empty separator chamber and of such strength and so directed that the magnetic particles form stable agglomerates stretched out along the lines of the magnetic field, which agglomerates can be moved by the fluid flow at the process temperature and flow conditions.
  • a dispersion of magnetic particles in a non-magnetic fluid is passed through an empty chamber made from non-magnetic materials which are located between the poles of a magnet which produces a uniform magnetic field directed transverse to the direction of flow.
  • the connecting tubing, pumps, valves, and separation vessel may be thermally insulated and of such construction as to withstand the pressure and temperature differences between those of the operating system and the ambient environment (e.g., temperatures up to and including 500°F and pressures up to and including 500 psi).
  • the separation chamber is empty except for the non-magnetic inlet pipes and the slurry contained therein.
  • the slurry of fluid containing the magnetic particles is released into the chamber from above through downwardly directed inlet ports located against the inside walls of the separation chamber adjacent to the magnet pole faces at an elevation below the top and above the bottom of the chamber.
  • the poles may be so disposed that the lines of the magnetic field are substantially perpendicular to the length of the separation chamber. Exit ports are located at the top and the bottom of the chamber.
  • the magnetic particles which themselves may be clusters of particles, become magnetized by the externally applied magnetic field as they enter the separation chamber and attract one another to form agglomerates or chains of particles joined end to end strung out along the lines of the magnetic field.
  • the magnetic field is applied transverse to the direction of flow which is along the axis of the separation chamber.
  • the slurry of particles enters the separation chamber as plumes of slurry extending downward along the inside walls of the chamber nearest the magnet poles.
  • the plumes of flow bring the magnetic particles into the separation chamber where they subsequently form chains of agglomerates.
  • the chained particles provide a source of intense gradient magnetic fields for capture of additional particles.
  • the flushing action of the plumes of slurry prevents the chains of magnetic particles from sticking to the inside walls of the separation chamber by sweeping the chained particles downward to the exit port at the bottom of the separation chamber.
  • the slurry may be comprised of both magnetic and non-magnetic particles suspended in a non-magnetic fluid.
  • the elevation at which the slurry flow is released into the separation chamber is adjusted so as not to stir up particles which have concentrated in the bottom of the separation chamber where magnetic particles exit the apparatus.
  • Non-magnetic particles and fluid follow the lines of flow and exit at the top and the bottom of the apparatus in relation to the rates of flow.
  • the bottom of the chamber extends below the bottom edge of the magnet return frame and is sloped to a final exit diameter outside of the magnetic field region. This slope is introduced to minimize effects such as frictional drag which would tend to hold the magnetic particles inside the separation chamber.
  • An overflow outlet port is located at the top of the chamber where non-magnetic fluid and some particles flow from the separator.
  • the upper surfaces of the magnet poles terminate abruptly at a distance below the top of the separation chamber for the purpose of creating a field gradient which serves to keep magnetic particles from exiting the top of the separator.
  • the lower edges of the magnet poles extend to the bottom of the straight section of the separation chamber below the bottom of the magnet iron return frame and are tapered outward.
  • the elongated poles serve to lengthen the flow path through the magnetic field which in turn permits higher rates of feed to the separation chamber without the plumes of slurry disturbing the concentrated magnetic particles located at the bottom of the chamber. Additionally, the outward slope of the poles minimizes the upward directed magnetic force which would hold magnetic particles in the lower regions of the separator and cause plugging.
  • Flow created by the source, hydrostatic pressure, and/or optional external means, such as a pump, can be employed to force the fluid from the slurry source through the separation chamber.
  • Valves can be employed with the external flow source, hydrostatic pressure, and/or pump to control the rates of high-solids underflow and low-solids overflow, respectively.
  • flow ratios (underflow rate divided by the overflow rate) generally greater than five, provide flows strong enough to sweep the chained particles downward without disrupting the magnetic particles in the bottom of the separation chamber. Flow ratios greater than or equal to ten are especially preferred.
  • the magnetic fields employed need only be large enough to magnetize the particles to a degree which will permit mutual attraction and formation of stable agglomerates.
  • the magnetic field need only be strong enough to achieve a reasonable degree of magnetic saturation.
  • nominally 30% of the particles were separated in a magnetic field of 500 gauss while greater than 96% separation of catalysts from the wax product has been achieved in magnetic fields of nominally 1500 gauss.
  • the filtration rate for both cases was between 110 and 130 kg/min/m 2 .
  • the external means is a pump
  • the configuration of pump and valves is redundant.
  • the pump and the underflow valve can be interchanged.
  • the high-solids slurry exiting the bottom of the separation chamber may be returned to the slurry source, if appropriate.
  • the low-solids slurry exiting the top of the separation chamber through an overflow valve may be subjected to additional separation employing this or other means such as cross-flow filtration, barrier filtration, electrostatic separation, sedimentation, centrifugation, or other magnetic means such as High Gradient Magnetic separation.
  • the low-solids slurry exiting the top of the separator may be returned to the slurry source if appropriate.
  • This apparatus has been found to be especially useful in true continuous separation of micron sized particles and especially sub-micron sized iron catalyst particles from Fischer- Tropsch wax at elevated temperatures. Magnetic fields of 1500-2000 gauss are sufficient to separate submicron size precipitated iron catalyst particles from Fischer-Tropsch wax at 500°F. This method is capable of separating 20 - 25 wt.% concentration sub-micron sized iron catalyst to produce a Fischer-Tropsch wax concentrate with catalyst concentration in the 0.1 - 0.5 wt.% range on a continuous basis at throughputs much greater than can be achieved by sedimentation or filtration. When high gradient magnetic separation is employed as a second stage of separation, diamagnetic wax slurries with particle concentrations in the 0.01 - 0.05 wt.% range have been prepared.
  • FIG. 1 is a front cutaway view of a continuous magnetic separator in accordance with the present invention.
  • FIG. 2 is a front cutaway view of the separation vessel of the continuous magnetic separator of FIG. 1;
  • FIG. 3 is a front perspective view of magnet poles of the magnetic separator of FIG. i;
  • FIG. 4 is a front cutaway view of a preferred embodiment of the present invention as applied to Fischer-Tropsch synthesis
  • FIG. 5 is a front cutaway view of an alternate embodiment of the present invention as applied to Fischer-Tropsch synthesis, wherein the separator is located inside a reactor; and [0024] FIG. 6 is a front perspective view of a transverse field electromagnet.
  • FIGS. 1 and 2 A preferred embodiment of the separation vessel and accompanying hardware and equipment is shown in FIGS. 1 and 2.
  • the separation vessel is shown a vertical section through the midplane of the separator wherein the separation chamber is an elongated empty vessel 1 oriented generally vertically and housed between poles 2 of an electromagnet 3.
  • Magnet coils 4 form loops around the magnet poles and rise vertically behind and in front of the vessel out of the plane of the drawing.
  • the magnetic field thus generated is in a horizontal plane transverse to the length of the separation vessel shown in FIG. 2.
  • Flow is introduced in a downward direction from the top of the vessel as high velocity streams through dual inlet ports 5 located opposite one another against the inside walls of the separation chamber adjacent to the magnet pole faces.
  • the inlet on each side of the vessel can be a single pipe, multiple pipes, or have orifices designed to flush the inside surfaces of the separation vessel adjacent to the magnet poles.
  • the elevation of these inlets into the separation vessel can be arranged to prevent excessive mixing in the bottom of the separation vessel caused by the plumes of slurry introduced through the inlet ports.
  • Means such as pump 29 can be used on the feed line to the inlet ports 5 or the underflow port at 6 to force the flow; however, any source of driving pressure could be used to generate the flow.
  • Magnetic particles carried into the cell by the downward directed flow will be attached to the chains if fluid flow brings them within the range of the gradient fields.
  • the rate of fluid flow is adjusted so that, working with gravity, the chains of particles are made to move down the inside walls of the separation vessel, thus preventing sticking which would lead to plugging, without stirring up the particles in the bottom of the separation vessel which would lead to excessive amounts of unchained particles or short chains of particles being inadvertently carried upward by the exiting fluid flow toward an overflow outlet 9.
  • a slurry of concentrated particles is withdrawn from the bottom of the vessel through underflow port 6.
  • the outlet at the bottom of the chamber must be sufficiently open so that the concentration of particles accumulating there does not become so high that the slurry can no longer be pumped because of high viscosity.
  • the magnet poles 2 shown in perspective view in FIG. 3, extend below the bottom of the magnet frame and are curved outward to slowly increase the local magnet pole opening as one proceeds along the vertical direction down away from the bottom of the magnet. This lowers the strength of the magnetic field in the region of the bottom of the separation vessel and reduces the vertical component of the magnetic field gradient which in turn reduces the upward directed magnetic force which tends to keep the magnetic particles in the separation vessel thus causing plugging. Additionally, lengthening the magnet poles as described above allows for a longer slurry plume extending downward from the inlet ports without disrupting the concentrated particles exiting the bottom of the separation vessel. This permits increased flow into the separation vessel thus increasing the system throughput without sacrificing separation efficiency.
  • FIG. 4 is a flow diagram of one preferred embodiment of the invention.
  • a Fischer-Tropsch reactor 20 with a slurry zone 22 contains a mixture of liquid comprising waxes made in the reactor, gases, and solid magnetic catalyst particles.
  • Synthesis gas comprising hydrogen and carbon monoxide is added at the bottom of the reactor at line 21.
  • Vapors are removed from the reactor through line 23.
  • Slurry is drawn from the slurry zone 22 through line 26 into a vapor liquid separator 25. Vapors are returned through line 24.
  • the slurry flows through line 27 and then through optional valve 28 into the slurry inlet ports 5 of the continuous magnetic separation vessel 1 which is magnetized by electromagnet 3.
  • the magnetic particles in the slurry proceed to agglomerate and chain in the applied magnetic field and then, under influence of the flow and gravity forces, move down the walls of the separation vessel.
  • the particles separated from the slurry form a magnetic concentrate 16 at the bottom of the continuous separator.
  • the magnetic concentrate exits through underflow port 6 to the inlet of optional pump 29 from where it flows back into the reactor to recycle the catalyst particles.
  • the exit stream is shown passing through a demagnetizing coil 41 which is energized through a power supply 42.
  • the coil and supply are of the type supplied by R. B. Annis Co., Inc., Indianapolis, IN, and can be purchased from McMaster Carr Supply Company of Cleveland, OH.
  • the demagnetization operation is optional.
  • a clarified liquid forms from the slurry with the magnetic particles removed at the top of the continuous magnetic separator.
  • the clarified liquid exits through line 33 and then through valve 31 to a secondary separator 36 wherefrom a further clarified liquid is withdrawn through line 40 and additional magnetic particles are withdrawn through line 38.
  • the exit stream from separator 36 passes through optional demagnetization coil 43 which is energized by a power supply 44.
  • a preferred secondary separator is an additional separator of the type described here or a high gradient magnetic separator, though other filters may be used as well.
  • the secondary separator 36 is shown as a conceptual block and the feed and product arrows are not indicative that the process conducted therein is a continuous process. It is not as important that this process step be continuous since it is not integrated into the synthesis process.
  • Operation of the separation vessel 1 shown in FIG. 4 is redundant. In the figure, operation of the separation vessel 1 is controlled by optional inlet valve 28, overflow valve 31, and optional slurry pump 29.
  • Flow restrictors, such as valves or pipe orifices, and pumps are an integral part of this invention and are required for control of its operation. However, in most cases control devices are not necessary on all three connections to the separator, feed, overflow, and underflow.
  • the valve 28 may be required to keep a constant slurry level in the reactor 20.
  • any two control devices can be used and in the special case where flow from the column reactor is reasonably steady and sufficient to force flow through the separator, and the weight of the column of underflow from the separator is sufficient to cause it to flow back into the reactor 20 only one overflow valve 31 is required. In this case pump 29 is unnecessary. In some cases, two controls may be used, one on the overflow and one on the underflow to assure the greater part of the flow exits the underflow port 6.
  • the valve 31 is primarily used to control the recycle ratio R, which is the ratio of the underflow rate to that of the overflow.
  • the separator can be operated with recycle ratios greater than or equal to 5 to 10 and preferably greater than or equal to 10.
  • the separation vessel 1 and electromagnet 3 are located within the reactor slurry zone 22 of a Fischer-Tropsch reactor 20 so that the clarified liquid is removed from the slurry zone through an outlet from the reactor 20 and the magnetic concentrate slurry is returned to the reactor slurry zone 22 through a separator outlet line 46 preferably at a position near the bottom of the slurry zone 22.
  • the slurry is preferably continuously pumped into the slurry inlet by a pump 48 that draws slurry from the reactor slurry zone.
  • the pump may be of the type that is internal to the reactor, such as a canned pump, or may be outside of the reactor drawing slurry through a nozzle 49 extending through the reactor wall.
  • the split between the separator overflow exiting at reactor outlet 45 and underflow exiting at separator outlet line 46 is preferably controlled by control valve 31 and a flow restrictor on the separator outlet line 46 or flow restrictors on both the reactor outlet 45 and the separator outlet line 46 or both.
  • the exit stream at separator outlet line 46 is shown passing through demagnetizing coil 41 which is energized through power supply 42.
  • the coil and supply are of the type described earlier.
  • the demagnetization operation is optional. It can be employed if desired to break up magnetic agglomerates for catalyst particles which exhibit hysteresis with a large remnant magnetization. Otherwise it is unnecessary.
  • a clarified liquid forms when the magnetic particles coalesce and moves to the top of the separator.
  • the clarified liquid exits through line 45 and then through valve 31 to vapor liquid separator 25.
  • Gas separated from the clarified liquid moves through line 24 and exits from the top of the reactor through line 23.
  • the gas-free clarified liquid moves through line 60 to secondary separator 36 wherefrom a further clarified liquid is withdrawn through line 40 and additional particles are withdrawn through line 38.
  • the line 38 from separator 36 passes through optional demagnetization coil 43 which is energized by power supply 44.
  • a preferred secondary separator is an additional separator of the type described here or a high gradient magnetic separator, though other filters may be used as well.
  • the secondary separator 36 is shown as a conceptual block and the feed and product arrows are not indicative that the process conducted therein is a continuous process. It is not important that this process step be continuous since it is not integrated into the synthesis process.
  • the coils, iron return frame, and magnet poles be thermally isolated from the surrounding liquid by means 50. It is further preferred to use a superconducting magnet, because of the large working gap required by thermal isolation. Use of large-scale high temperature superconductors would substantially reduce the cost of this option.
  • the continuous magnetic separator shown in FIGS. 4 and 5 is of the type shown in FIGS.
  • FIGS 1 and 2 where the magnet could be an electromagnet, a superconducting magnet, or a permanent magnet.
  • the electromagnet structure shown in FIGS 1 and 2 is a conventional iron frame electromagnet of the type pictured on page 53 of the book entitled “Adsorption and Collective Paramagnetism” by Pierce W. Selwood and published by Academic Press, New York, 1962, except that the pole gap in the research magnet illustrated in Selwood is much smaller than that anticipated for magnetic particle separation envisioned here. If it is desirable to employ a more uniform magnetic field than that possible with the conventional transverse access magnet of the type shown in Selwood, then a magnet of the type shown in FIG. 6 can be employed. In FIG.
  • magnet coil windings 51 can be wound so as to pass up through the pole gap on either side of the poles and be folded over at the top and bottom surfaces of the electromagnet 3 so as to permit transverse access to the working volume.
  • the reactor and reaction system have been described in terms of a Fischer- Tropsch reactor, the invention could just as well be another reaction carried out in a slurry comprising a non-magnetic liquid and a strongly magnetic solid slurried therein.
  • the separator may be employed in different applications such as when the low solids overflow exiting from the separation vessel 1 at overflow port 9 is to be recycled to the source 19. While not limiting, examples of such applications would be clean-up of used engine oils or transformer oils.
  • a separator of the type described in this invention is highly preferable when using iron catalyst in the Fischer-Tropsch reactor.
  • the iron oxide reacts with carbon monoxide and hydrogen to produce surface layers of iron carbide which fractures the catalyst particle structure. This in turn causes minute catalyst particles to slough off the catalyst agglomerate surface leading to sub-micron sized particles which must be removed from the wax downstream of the Fischer-Tropsch reactor.
  • Iron is a desirable catalyst when processing synthesis gas produced by gasification of coal, petroleum coke, or other materials with low ratios of hydrogen to carbon. Further, iron is less costly and more easily disposed than is cobalt, another magnetic material of choice in the Fischer-Tropsch synthesis.
  • the novel magnetic separator is capable of separating agglomerates of nanometer iron catalyst particles with a very broad range of magnetic moments and agglomerate sizes.
  • 1-100 micron-sized magnetite catalyst agglomerates composed of nanometer sized magnetite particles with magnetic moments of the order of 50 emu/g and sizes of the order of 10 microns have been separated from diamagnetic slurry with kinematic viscosities up to 600 cS at filtration rates in the order of 200 kg/min/m 2 .
  • Individual particles which were agglomerated in the field ranged from 2 nm to 60 nm. Similar iron particles with magnetic moments of 213 emu/g could be separated as well. If the filtration rate is lowered, then the sizes and magnetic moments at which magnetic particles can be separated from the diamagnetic fluid decrease.
  • a Model HD-70A lobe pump manufactured by The Pump Division of Tuthill Corporation, 12500 South Pulaski Road, Chicago, IL 60658 was used to pump a slurry of Fischer-Tropsch wax at 500°F containing iron catalyst particles through a continuous magnetic separator of the type shown in FIG. 1. Pipe connections and sampling ports were employed such that the overflow and underflow streams could be sampled independently and the flows recycled to the source.
  • the test material had been taken from an operating Fischer-Tropsch synthesis reactor.
  • the slurry material used in testing contained up to 35 wt.% iron catalyst particles. Portions of the catalyst particles had been converted to iron carbides upon exposure to carbon monoxide and hydrogen in the Fischer-Tropsch reactor.
  • the individual particle size ranged from 2 to greater than 60 nm. Cluster sizes ranged from sub-micron to nominally 100 microns.
  • the kinematic viscosity of the slurries ranged from less than 1 cS to greater than 600 cS for solids ranging from 0.5 to 35 wt.% at nominal 500°F. A Brookfield viscometer was employed to measure the viscosity. Slurry density was calculated from mass and volume measurements made at 500°F.
  • the separation vessels were thermally insulated and housed within the pole gap of an electromagnet which produced a magnetic field oriented in the horizontal plane transverse to the length of the separation vessel.
  • the pole gap volume had a parallelepipedal shape. It was 10 inches wide and had a maximum pole gap of 9 l ⁇ inches when used with a thermally insulated 6-inch inside diameter chamber and three and 3 % inches when used with a thermally insulated 2-inch inside diameter chamber.
  • the magnet iron return frame extended 9 inches along the length of the canister.
  • the maximum magnetic field was 2200 gauss for the nominal 6-inch chamber and 7700 gauss for the nominal 2-inch canister.
  • magnet poles were extended below the bottom of the iron return frame and were shaped to facilitate a smaller vertical component of the magnetic field gradient there.
  • magnet poles were fabricated to gradually curve away from one another as shown in FIG. 3. This reduced the magnetic field gradients at the lower edge of the magnet return frame by approximately 90% and lowered the tendency for plugging. This also improved the operation of the separator by effectively lengthening the separation vessel.
  • Use of the extended poles also serves to improve the homogeneity of the magnetic field inside the separation chamber by effectively improving the ratio of the core length along the canister to the gap opening and width.
  • the total length of the separation vessel from the domed top to the outlet at the tapered bottom depends upon the vessel diameter and the fittings used to terminate the bottom. With nominal 3 ⁇ -inch pipe fitting on the bottom of the 6-inch diameter chamber, the overall length of the vessel is approximately 28 inches. It is to be understood that the separation vessel may assume various dimensions including but not limited to, substantially elongate cylindrical or parallelepipedal shapes. Additionally, the cross section of the top portion of the separation chamber may be greater than a cross section of the elongate portion. Furthermore, the cross section of the elongate portion may be greater than a cross section of the bottom portion.
  • a slurry containing 21.45 wt.% catalyst was fed at the rate of 17.53 gpm into a 6- inch diameter separation vessel through two sets of down-directed feed lines located across from one another next to the elongated tapered poles of the electromagnet.
  • a vessel with a 6- inch inside diameter was employed.
  • the overall canister length was 21 inches from the top of the dome at the overflow port to the bottom of the straight section which terminated 5 inches below the bottom of the magnet return frame.
  • the volume of the six inch canister is 10 liters.
  • Each set of feed lines consisted of one %-inch outer diameter tube and two '/.-inch tubes on either side of the 3 ⁇ -inch inlet.
  • the magnetic field was 2000 gauss.
  • the underflow was withdrawn through a 2-inch pipe (nominal 2.067 inch inner diameter) at a rate of 16.1 gpm and contained 23.33 wt.% ash.
  • the overflow was withdrawn through a '/_-inch tube with 0.035-inch wall thickness at the rate of 1.43 gpm and contained 0.35 wt.% ash.
  • the ash level in the overflow was 98.4% less than that in the feed.
  • the residence time in the apparatus was 11 seconds.
  • the total process flow during the 2 hour run had a volume equal to 660 times that of the empty separation chamber. Thus, a volume equal to 660 times that of the chamber was processed without signs of plugging.
  • the slurry was fed at an average rate of 11.3 gpm to a 6 inch diameter vessel through two 3 ⁇ -inch outside diameter down-directed stainless pipes located next to the inside walls of the separation chamber adjacent to the magnet poles as described above.
  • the pipe outlets open into the separation chamber at an elevation which is 3 inches below the top of the electromagnet return frame.
  • the opening at the chamber overflow was ' .-inch tubing; the opening at the underflow was nominally 1-inch pipe.
  • the magnetic field strength was varied from the locked-in field of the electromagnet with no current in the energizing coils up to 2200 gauss. Valves were used to maintain a recycle ratio of approximately 11 :12. The ash levels in the feed, underflow, and the overflow were measured.
  • the applied magnetic field has a major effect on the separation process.
  • the field should be sufficient to saturate the magnetism of the particles to be separated if they exhibit collective magnetism, i.e., they exhibit hysteresis.
  • the iron catalyst particles were found to be saturated at fields between 1500 and 2000 gauss.
  • the separator performance reflects the saturation magnetization of the iron particles in the Fischer-Tropsch wax.
  • the slurry was fed at an average rate of 11.3 gpm to a 6-inch diameter vessel through two %-inch outside diameter down-directed stainless pipes as described above.
  • the feed pipe outlets open into the separation chamber at various elevations ranging from 3 inches above the top of the iron return frame to 6 inches below.
  • the opening at the chamber underflow was nominally 1 inch diameter.
  • the applied magnetic field strength was held constant at 2000 gauss.
  • Overflow and underflow valves were used to maintain a recycle ratio of approximately 10 to 11.
  • the ash levels and flow rates in the feed, underflow, and the overflow were measured. The percentage reduction in ash was calculated as described above.
  • the best elevation for entrance of the slurry into the separator can be seen to be at or near the top of the electromagnet iron return frame.
  • the plume of slurry is released in the magnetic field and the presence of the plume does not have a detrimental effect on the ash level in the overflow stream.
  • the separator performance drops rapidly.

Abstract

Une cuve de séparateur magnétique (1) destinée à la séparation de particules magnétiques d'un fluide non magnétique comprend une chambre de séparation possédant une paroi externe, une paroi interne, une partie de fond et une partie de haut, un aimant (3) comprenant un premier et un deuxième pôles (2) disposés adjacents à la paroi externe, le premier pôle étant diamétralement opposé au deuxième pôle, un orifice d'entrée (5) orienté vers la partie de haut de la chambre de séparation, ledit port d'entrée (5) étant disposé adjacent au premier ou au second pôle (2) et conçu pour transporter un mélange vers la chambre de séparation, un orifice pour sous-écoulement (6) communiquant avec la partie de fond, ledit orifice pour sous-écoulement (6) étant conçu pour recevoir les particules magnétiques, et un orifice de débordement (9) en communication avec la chambre de séparation, l'orifice de débordement (9) étant conçu pour recevoir le fluide non magnétique.
PCT/US2004/033387 2003-10-09 2004-10-08 Appareil et procede destines a la separation en continu des particules magnetiques et des fluides de particules non magnetiques WO2005035131A1 (fr)

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Cited By (7)

* Cited by examiner, † Cited by third party
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US20090069450A1 (en) * 2007-09-10 2009-03-12 Rentech, Inc. Commercial fischer-tropsch reactor
US8603343B2 (en) 2007-10-18 2013-12-10 IFP Energies Nouvelles Device for separating a finely divided solid in suspension in a viscous liquid
CN103846159A (zh) * 2012-11-30 2014-06-11 中国石油化工股份有限公司 一种固液分离装置
US8871096B2 (en) * 2007-09-10 2014-10-28 Res Usa, Llc Magnetic separation combined with dynamic settling for fischer-tropsch processes
CN105921269A (zh) * 2016-06-08 2016-09-07 镇江电磁设备厂有限责任公司 一种管道式除铁器
CN108640400A (zh) * 2018-05-08 2018-10-12 吉林建筑大学 一种水处理磁性光催化剂快速覆膜的方法与装置
WO2019099905A1 (fr) * 2017-11-17 2019-05-23 Saint-Gobain Ceramics & Plastics, Inc. Procédé et ensemble de filtration

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WO2003064052A2 (fr) * 2002-02-01 2003-08-07 Exportech Company, Inc. Procede et separateur magnetiques continus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003064052A2 (fr) * 2002-02-01 2003-08-07 Exportech Company, Inc. Procede et separateur magnetiques continus

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090069450A1 (en) * 2007-09-10 2009-03-12 Rentech, Inc. Commercial fischer-tropsch reactor
US8871096B2 (en) * 2007-09-10 2014-10-28 Res Usa, Llc Magnetic separation combined with dynamic settling for fischer-tropsch processes
US9011696B2 (en) 2007-09-10 2015-04-21 Res Usa Llc Magnetic separation combined with dynamic settling for fischer-tropsch processes
US9168501B2 (en) * 2007-09-10 2015-10-27 Res Usa, Llc Commercial Fischer-Tropsch reactor
US8603343B2 (en) 2007-10-18 2013-12-10 IFP Energies Nouvelles Device for separating a finely divided solid in suspension in a viscous liquid
CN103846159A (zh) * 2012-11-30 2014-06-11 中国石油化工股份有限公司 一种固液分离装置
CN103846159B (zh) * 2012-11-30 2016-06-22 中国石油化工股份有限公司 一种固液分离装置
CN105921269A (zh) * 2016-06-08 2016-09-07 镇江电磁设备厂有限责任公司 一种管道式除铁器
WO2019099905A1 (fr) * 2017-11-17 2019-05-23 Saint-Gobain Ceramics & Plastics, Inc. Procédé et ensemble de filtration
US11786840B2 (en) 2017-11-17 2023-10-17 Saint-Gobain Ceramics & Plastics, Inc. Filtration process and assembly
CN108640400A (zh) * 2018-05-08 2018-10-12 吉林建筑大学 一种水处理磁性光催化剂快速覆膜的方法与装置

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