Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
  • F27B15/02—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B15/09—Arrangements of devices for discharging
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/0015—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
  • B01J8/0025—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor by an ascending fluid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/005—Separating solid material from the gas/liquid stream
  • B01J8/0055—Separating solid material from the gas/liquid stream using cyclones
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
  • B01J8/1809—Controlling processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
  • B01J8/1836—Heating and cooling the reactor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B9/00—Combinations of apparatus for screening or sifting or for separating solids from solids using gas currents; General arrangement of plant, e.g. flow sheets
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
  • F27D17/20—Arrangements for treatment or cleaning of waste gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/0061—Controlling the level
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00743—Feeding or discharging of solids
  • B01J2208/00761—Discharging

Definitions

• This invention relates generally to the field of deposition reactors and more specifically to an apparatus and method for top removal of granular material from a fluidized bed deposition reactor.
• Fluidized bed reactors have a long tradition in the chemical industry where the bed usually consists of a finely divided valuable catalyst which makes it necessary to design the reactors to prevent catalyst losses.
• a concept called total disengaging height, or TDH was developed to estimate the height where all the particles that would settle out by gravity had settled out. Internal cyclones were provided at this height to capture the finer dust and return it to the bed. Whenever the catalyst was removed it was removed from the bottom ' by gravity.
• deposition reactors Since some fine dust is always made, most deposition reactors have external cyclones or filters to trap the dust and prevent damage to the equipment used to recover the effluent gases. Thus the historic approach has been to have removal of the product from the bottom, provide a large disengaging height to minimize product loss, and use external dust removal.
• the primary use for deposition reactors is in high purity silicon deposition and Lord in US 6,451 ,277 in Fig. 1b describes a bed heating method which removes beads from near the top of the bed and then heats them and returns them to the bed. It is notable that the product, 3, is still removed from the bottom.
• the bottom temperature must be maintained above 800° C to provide the needed crystallization, and some seeds are lost to the product which is in turn contaminated with broken "seed beads.”
• the combination of high temperature and high deposition gas concentration leads to rapid reactions, increased wall deposits and increased risk of agglomeration and plugging.
• the primary object of the invention is to provide a shorter reactor with greater production.
• Another object of the invention is to provide a passive method of level control. Another object of the invention is to provide a better quality product. A further object of the invention is to reduce the need for high temperature at the bottom of the reactor. Yet another object of the invention is to reduce the risk of plugging.
• Still yet another object of the invention is to reduce the thickness of wall deposits. Another object of the invention is to reduce the pressure in the product removal system. Another object of the invention is to recover energy.
• an apparatus and method for top removal of granular material from a fluidized bed deposition reactor comprising: removal of the product from the top of the reactor together with the effluent gas, separation of the granular product from the effluent gas, simultaneous recovery of heat from the product and the gas and optional further dust and heat recovery.
• Figure 1 is a schematic diagram illustrating the operation of a fluidized bed deposition reactor of the prior art with bottom removal and a large disengaging space.
• Figure 2a is the same diagram modified to show the benefits of the invention.
• Figure 2b is a detailed schematic of the top of the reactor showing the granular particle removal mechanism.
• Figure 3 is a schematic of a product separator with integrated heat recovery.
• Fig 1 there is shown a schematic of a typical fluidized bed deposition reactor comprising a containment vessel or liner, 111 , of a height, 144, a gas introduction means, 112, an optional gas distribution means, 113, a bottom product removal means, 114, a bed heating means, 115, a gas/dust mixture exit, 116, a connecting means, 127, a dust/gas separation means, 117, a dust removal means, 118, and a gas exit, 119.
• a typical fluidized bed deposition reactor comprising a containment vessel or liner, 111 , of a height, 144, a gas introduction means, 112, an optional gas distribution means, 113, a bottom product removal means, 114, a bed heating means, 115, a gas/dust mixture exit, 116, a connecting means, 127, a dust/gas separation means, 117, a dust removal means, 118, and a gas exit, 119.
• the containment vessel, 111 surrounds a bed of granules, 120, fluidized by gas bubbles, 121 , and having an average top level, 122, above which product granules, 123, thrown up above the bed describe arcs as they rise from random impact within the bed then fall under gravity in a reduced disengaging space, 124, while the small entrained dust particles, 125, continue up and leave with the effluent gas, 126, through the gas/dust mixture exit, 116, through the connecting means, 127, then enter the dust/gas separation means, 117, where most of the dust, 125, is removed from the gas, 126, and then ultimately leaves the system via the dust removal means, 118, while the gas, 126, and residual dust leaves via an exit, 119.
• the differential pressure meter, 128, measures the difference in pressure between the bottom product removal means, 114, and the gas exit, 119. This measurement indicates the level, 122, of the bed of granules, 120.
• the bottom removal means, 114 is used to control the top level, 122, to maintain the dise ' ngaging space, 124, so that the product granules, 123, are returned to the bed of granules, 120, and are thus removed by the bottom product removal means, 114.
• Fig 2a shows a schematic similar to Fig 1 but modified to remove the granular product from the top via a gas/granular separator means, 230, inserted before the effluent gas enters the gas/dust separation means, 217.
• a further modification is the removal of the differential pressure transmitter, 128, shown in Fig 1 , which is not required for bed level control.
• the invention thus comprises a containment vessel or liner, 211 , of a height, 244, a gas introduction means, 212, an optional gas distribution means, 213, an optional bottom product removal means, 214, a bed heating means, 215, a gas/dust/granular mixture exit, 216, a first connecting means, 241 , a gas/granular separator means, 230, with a granular removal means, 231 , an optional heat recovery means, 242, a further connecting means, 229, a gas/dust separation means, 217, a further optional heat recovery means, 243, a dust removal means, 218, and a gas exit, 219.
• the containment vessel, 211 surrounds a bed of granules, 220, fluidized by gas bubbles, 221 , and slugs, 240, and having an average top level, 222, above which some granules, 223, thrown up above the bed describe arcs as they rise from random impact within the bed then fall under gravity in a reduced disengaging space, 224, while some granules, 236, and the small entrained dust particles, 225, continue up and leave with the effluent gas, 233, through
• the average top level, 222 is very close to the gas/dust/granular mixture exit, 216, and consequently some of the product granules, 236, thrown up above the bed do not describe arcs as they rise then fall under gravity in the disengaging space, 224, but continue with the entrained dust, 225, out the
• Fig 2b there is shown in detail the various mechanisms which cause the product granules, 236, to be carrried out the gas exit, 216.
• the basic mechanism is the o random ejection of product granules, 236, from the top of the bed, 222, and the pneumatic conveying of these granules out the gas/dust/granular exit, 216.
• the bed level oscillates up and down due to the formation of gas slugs, 240, which lift sections of the bed up to the high level, 232, until they break through and the bed level recedes to the low level, 234. It is also possible for the bed to reach extra high levels, 235, where the bed is above the exit briefly.
• the exit tube, 241 can be attached to the exit, 216, at 90° as shown or sloped above or below the horizontal. The angle chosen can be determinecTby the application of standard pneumatic conveying calculations using the gas velocity in the exit tube, 241.
• Fig 3 there is shown a more detailed schematic of a product separator, 330, with an integrated heat recovery system, 301 , suitable for high temperature and high purity applications.
• the gas/dust/granular mixture, 333 enters the product separator, 330, through an inlet, 357, which goes through the heat recovery system, 301 , via a penetration, 358; the gas and dust, 356, then separate to the top and exit via the exit tube, 329, while the granules, 336, separate to the bottom exit, 331 , where it is fluidized by a purge stream, 359, and withdrawn as needed.
• the heat recovery system, 301 is comprised of a heat transfer fluid, 360, contained in a container, 351 , which is shaped to capture heat, 350, from the wall of the product separator and has an inlet, 354, and an outlet, 355, for the heat transfer fluid, 360.
• the container can use various heat transfer fluids such as water or hot oil. It is usually advantageous for the container to be a pressure vessel to permit heat recovery at higher temperatures.
• the heat may be transferred from the wall to the container by radiation, conduction or convection and well-known heat transfer techniques can be used to enhance the heat transfer from the gas and solids to the wall. Similarly, well- known gas-solids removal techniques, such as cyclones or filters, can be used to enhance the gas-solids separation.
• the heat is transferred by radiation from the hot surface of the product separator to a pressurized container which has water, 352, coming in through the inlet, 354, and steam, 353, leaving through the exit, 355.
• Fig 2 An example using Fig 2 would be as follows.
• the diameter of the container is 300 mm
• the overall height of the liner, 244, is 7 meters
• the average bed level, 222 is 6 meters
• the high level is about 6.6 meters
• the low level is about 5.4 meters.
• the gas superficial velocity at the top of the container is 4.7 ft/s (1.4 m/s).
• the average particle size of the granules is 1mm and the terminal velocity is 21.8 ft/s (6.56 m/s).
• the particle terminal velocity is thus about 4 times the superficial gas velocity. This means that in order to carry the granules out of the reactor, the local velocity in areas just above the bed must have local surges where it is 4 times higher than average.
• Velocity surges of this magnitude occur close to the top of the bed at about 20 cm above the bed.
• the slug, 240 has a maximum length of about 1.2 meter, and so the periodic growth and bursting of the slug provides the variation in height of 1.2 meters between low and high level. As the slug bursts, it also accelerates the granular particles which are then entrained out of the reactor. Thus the granular removal varies with the pulsing of the slugs, 240
• the granules and gas at the bottom of the reactor are at 700 °C, then are heated up and leave the reactor as stream, 233, via exit, 216, at a temperature of 800 0 C. They enter the cyclonic product separator, 230, through a tangential inlet which forces the gas and solids to the wall of the vessel to improve gas to wall heat transfer.
• the diameter of the cyclone is 10 inches (250 mm) and the length is 6 ft (1.8m). This is longer than needed for solely the solids removal in order to provide sufficient surface area for heat transfer.
• the gas and granules both leave at 600 °C.
• the dust/gas separator, 217 is of a similar size but only removes about half the heat because of the reduction in the temperature difference. The gas and dust then leave the dust/gas separator at 500 0 C. Both heat recovery systems recover the heat as 150 psig steam, which is a standard utility useful in the facility for a variety of purposes and thus always in demand.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Dispersion Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
• Cyclones (AREA)
• Silicon Compounds (AREA)

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• 2007
  • 2007-06-04 US US11/810,422 patent/US20080299015A1/en not_active Abandoned
• 2008
  • 2008-07-10 WO PCT/US2008/008569 patent/WO2008150552A2/en not_active Ceased
  • 2008-07-10 EP EP08780156.9A patent/EP2167227B1/en not_active Not-in-force
  • 2008-07-10 JP JP2010511225A patent/JP2011527625A/ja active Pending
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  • 2008-07-10 CN CN200880018753.8A patent/CN101743057B/zh not_active Expired - Fee Related
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