Classifications

• • 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
  • B01J4/00—Feed or outlet devices; Feed or outlet control devices
  • B01J4/001—Feed or outlet devices as such, e.g. feeding tubes
  • B01J4/002—Nozzle-type elements
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/26—Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles
• • 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
  • B01J8/1818—Feeding of the fluidising gas
• • 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
  • B01J8/1872—Details of the fluidised bed reactor
• • 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
  • B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
  • B01J8/36—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with fluidised bed through which there is an essentially horizontal flow of particles

Definitions

• the invention relates to a method for fluidizing a fluidized bed, which forms a fluidized bed of solid particles, in a vessel with a base by feeding a fluidizing gas into the fluidized bed via at least one pipe, and to an apparatus for carrying out this method.
• fluidized beds have been fluidized by gas being supplied from below via open vertical holes, nozzle tubes with lateral holes with or without caps or porous plates (cf. "Handbook of Fluidization and Fluid-Particle Systems", Chapter 6: Gas Distributor and Plenum Design in Fluidized Beds pages 155-176, Ed. W.C. Yang, Dekker, New York, 2003).
• cap type nozzles Even fluidizing is achieved by virtue of the fact that each cap nozzle is equipped with a high pressure loss by virtue of small cross sections of flow.
• the high velocities and multiple diverting of the gas flow makes it difficult for solids to penetrate backwards into the gas supply. Nevertheless, when the gas supply is switched off, residual fluidization often causes solids to penetrate into the cap, and these solids are not generally flushed out again when the apparatus is started up again, which can even cause the cap to become blocked. Drainage measures then have to be undertaken, which represent an occupational safety problem in the case of processes carried out at a high temperature.
• Porous plates or fabrics produce a very uniform fluidization but have the drawback that the porous medium becomes clogged over the course of time and cannot be fully cleaned again, or that the porous medium loses pressure loss over the course of time as a result of erosion.
• the distributor equipped with caps or nozzles it is necessary to provide for the possibility of emptying the space through which the gas flows at least for the eventuality of the fabric breaking.
• the use temperature of the porous plates and in particular of the fabrics is limited.
• the invention achieved this object substantially by a method having the features of Claim 1 and an apparatus having the features of Claim 11.
• the new form of fluidization is distinguished by the fact that the gas stream is guided continuously downwards from a distributor above the fluidized bed and emerges from the pipe in the vicinity of the vessel base.
• the pipe does not have any narrowings in the direction of flow below the maximum height up to which the solids could rise in the pipe, i.e. the pipe has a cross section which remains constant or widens downwards below this height.
• the pressure loss required to make the fluidizing more uniform is in each pipe brought about by a flow resistance (e.g. an orifice) which, however, in any event lies in a part of the individual pipe which remains free of solids. It is preferable for the flow resistance to be located outside the fluidizing space, so that it is readily accessible. According to the invention, the pressure loss in the flow resistance should amount to between 10 and 1500 mbar, preferably between 20 and 200 mbar.
• the outlet velocity of the gas from the bottom end of the pipe depends on the sensitivity of the solids in the fluidized bed and its permissible stressing. If it is a sensitive, for example brittle, solid and fragmentation is undesirable, the velocity must be selected to be as low as possible.
• the outlet velocity should generally be between 2 and 50 m/s, preferably between 5 and 30 m/s.
• the pressure ratio across the orificecan be set to more than 2 to 1 , i.e. the absolute pressure up- stream of the orificeis at least double the absolute pressure downstream of the orifice. Consequently, sonic flow is reached in the narrowest cross section of the orifice.
• the sonic flow means that the volumetric flow in the pipe is accurately defined irrespective of the operating fluctuations and the outlet velocity at the bottom end of the pipe.
• the volumetric flows in the pipes may optionally also be determined in such a way that even a desired defined uneven distribution is achieved.
• the pipes may be introduced vertically or at an angle to the horizontal.
• the angle is in this case more than 1 ° with respect to the horizontal, preferably more than 30° with respect to the horizontal. This makes it possible to prevent the pipes from becoming blocked, or else solids which have penetrated are easy to blow out again when the fluidizing is started up.
• the pipes are preferably cut off horizontally at the end, in order to enable the gas to flow out as far down as possible, i.e. close to the base of the fluidized bed, generally at a distance of less than 250 mm, preferably a distance of less than 150 mm, from it.
• the pipe end can be provided with a "detachment lug" on the top side, which reduces the erosion to the pipe caused by the flow.
• a wear-resistant material e.g. stainless steel.
• This new design allows the gas distributor of the fluidized bed to be simple and inexpensive in form. Furthermore, the design prevents solids through-fall through the distributor.
• the flow resistance As an exchangeable apertured orifice between two flanges.
• the nozzle tubes themselves to be introduced into the vessel through connection pieces with flanges, in order to facilitate their replacement.
• the method according to the invention is suitable for all fluidized beds, but in particular for those in which what is known as nozzle through-fall can very easily occur, for example if the particles are very small or remain in the fluidized state for a very long time after the fluidizing has been stopped.
• Fig. 1 shows an apparatus according to the invention for fluidizing a fluidized bed
• Fig. 2a, b show alternative configurations of the pipe ends which open out above the vessel base
• Fig. 3 shows another embodiment of an apparatus according to the invention.
• the apparatus for fluidizing a fluidized bed which is diagrammatically depicted in Fig. 1 comprises a vessel 1 into which solid particles are introduced via a feed line 2.
• the solid particles are, for example, heat-treated in the vessel 1 in a fluidized bed 3 and then discharged again from the vessel 1 via a discharge line 4.
• the off-gas produced is discharged via an off-gas line 5.
• the fluidized bed 3 is fl ⁇ idized by supplying a fluidizing gas, the composition and properties, in particular temperature, of which depend on the desired treatment of the solid particles.
• the fluidizing gas is supplied via a line system 14 which divides the fluidizing gas, via a gas distributor (header) 6, between a plurality of pipes 7 distributed for example in the shape of a circle.
• a gas distributor header
• the pipes 7 extend substantially vertically from above into the fluidized bed formed by the fluidized bed 3, and their respective outlet openings 8, which are cut off horizontally, open out into the fluidized bed 3 just above the base 9 of the vessel 1.
• the distance between the outlet openings 8 and the vessel base 9 is, for example, 100 or 200 mm.
• an apertured orifice 10 is in each case provided as a flow resistance above the region which can be reached by the solid particles of the fluidized bed 3.
• the apertured orifice 10 is, for example, secured between two flanges 11, so that it can easily be replaced in order to optimize the operating properties and/or for maintenance or repair work.
• the passage opening of the apertured orifice 10 may be variable, in order to set the pressure loss and therefore the quality of even distribution of the gas. Given a sufficiently high admission pres- sure, the diameter of the apertured orifice 10 can alternatively be set in such a way that a pressure ratio of at least 2:1 is produced at the orifice, and sonic flow is achieved at the smallest cross section.
• the apertured orifices 10 lie outside the vessel 1. However, they may also be arranged inside it, provided that it is ensured that the solid particles cannot rise up as far as the flow resistance and block it and/or cause wear to it.
• the pipes 7 may also be inclined.
• Fig. 2a and 2b illustrate examples of an inclined pipe arrangement of this type, in which the pipes 7a and 7b are at an angle of approx. 30° (25°-35°) with respect to the horizontal.
• the pipe cross section is thickened in the region of the outlet opening 8a or 8b.
• a material thickening produced for example by a build-up weld 12 is provided around the opening region of the pipe 7a.
• fluidizing gas is introduced into the fluidized bed 3 through the pipes 7 and fluid- izes the solid particles.
• the pressure loss brought about by the flow resistance produces even fluidizing, while it is ensured that the solid particles cannot rise up as far as the flow resistance and block the pipe 7.
• Fig. 3 shows another example of the use of the fluidizing method according to the invention for solid conveying in what are known as "airlift sending pots".
• An airlift system is used for the pneumatic conveying of 100 t/h of aluminium hydrate with grain diameters of between 30 and 170 ⁇ m over a height of approx. 60m.
• the airlift sending pot 20 shown in Fig. 3 is for this purpose used to feed the conveying.
• the vessel 21 has a diameter of 1200 mm with a centrally arranged conveying pipe 22 with a diameter of 400 mm.
• a conveying air stream of approx. 6000 m 3 /h (s.t.p.) is passed through the central nozzle 23 and carries the solids with it.
• the surrounding solids have to be fluidized, so that they can always flow sufficiently into the region of the central nozzle 23.
• the vessel is fluidized via 30 pipe nozzles 24 (nominal width 1"), the bottom ends of which are arranged in two concentric rings of different diameters, so that the annular space between convey- ing pipe 22 and vessel wall 25 is uniformly supplied with air.
• the fluidizing pipes 24 are supplied with air from a common distributor 26 which lies above the region which can be loaded with solids.
• there is an orifice 27 just below the distributor 26, which with a pressure loss of 150 mbar is designed in such a way that each pipe 24 receives virtually the same volumetric flow of air.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Polymerisation Methods In General (AREA)

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• 2005
  • 2005-02-11 DE DE102005006570.8A patent/DE102005006570B4/de active Active
• 2006
  • 2006-02-08 WO PCT/EP2006/001113 patent/WO2006084682A1/en not_active Application Discontinuation
  • 2006-02-08 BR BRPI0608239A patent/BRPI0608239B8/pt active IP Right Grant
  • 2006-02-08 CN CN2006800045203A patent/CN101115552B/zh active Active
  • 2006-02-08 RU RU2007133826/05A patent/RU2410154C2/ru active
  • 2006-02-08 AU AU2006212416A patent/AU2006212416B2/en active Active
  • 2006-02-09 MY MYPI20060565A patent/MY146065A/en unknown

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