212:(CFB), where gases are at a higher velocity sufficient to suspend the particle bed, due to a larger kinetic energy of the fluid. As such the surface of the bed is less smooth and larger particles can be entrained from the bed than for stationary beds. Entrained particles are recirculated via an external loop back into the reactor bed. Depending on the process, the particles may be classified by a cyclone separator and separated from or returned to the bed, based upon particle cut size.
39:
258:
248:(NFB): For this case, the ratio between the tube and the grain diameters is equal or less than around 10. The dynamics of the bed is then different from the other types of fluidized beds because of strong confinement effects, and the presence of granular plugs, consisting of regions with high concentrations in solids alternating with low solids concentrations, is common.
274:. In order to transition from a packed bed to a fluidised condition, the gas velocity is continually raised. For a free-standing bed there will exist a point, known as the minimum or incipient fluidisation point, whereby the bed's mass is suspended directly by the flow of the fluid stream. The corresponding fluid velocity, known as the "minimum fluidisation velocity",
117:. This behavior in fluidised combustion beds enables good thermal transport inside the system and good heat transfer between the bed and its container. Similarly to the good heat transfer, which enables thermal uniformity analogous to that of a well mixed gas, the bed can have a significant heat-capacity whilst maintaining a homogeneous temperature field.
1059:
824:
The particles in this region are above 600 μm and typically have high particle densities. Fluidisation of this group requires very high fluid energies and is typically associated with high levels of abrasion. Drying grains and peas, roasting coffee beans, gasifying coals, and some roasting metal
833:
Typically, pressurized gas or liquid enters the fluidised bed vessel through numerous holes via a plate known as a distributor plate, located at the bottom of the fluidised bed. The fluid flows upward through the bed, causing the solid particles to be suspended. If the inlet fluid is disabled, the
101:
A fluidized bed consists of fluid-solid mixture that exhibits fluid-like properties. As such, the upper surface of the bed is relatively horizontal, which is analogous to hydrostatic behavior. The bed can be considered to be a heterogeneous mixture of fluid and solid that can be represented by a
804:
For this group the particle size is between 20 and 100 μm, and the particle density is typically less than 1.4g/cm. Prior to the initiation of a bubbling bed phase, beds from these particles will expand by a factor of 2 to 3 at incipient fluidisation, due to a decreased bulk density. Most
158:
Fluidized beds are also used for efficient bulk drying of materials. Fluidized bed technology in dryers increases efficiency by allowing for the entire surface of the drying material to be suspended and therefore exposed to the air. This process can also be combined with heating or cooling, if
797:
In 1973, Professor D. Geldart proposed the grouping of powders in to four so-called "Geldart Groups". The groups are defined by their locations on a diagram of solid-fluid density difference and particle size. Design methods for fluidised beds can be tailored based upon the particle's
Geldart
125:
Fluidized beds are used as a technical process which has the ability to promote high levels of contact between gases and solids. In a fluidised bed a characteristic set of basic properties can be utilised, indispensable to modern process and chemical engineering, these properties include:
183:) in the late 1940s. During this time theoretical and experimental research improved the design of the fluidised bed. In the 1960s VAW-Lippewerk in Lünen, Germany implemented the first industrial bed for the combustion of coal and later for the calcination of aluminium hydroxide.
110:. As the "density", (actually the solid volume fraction of the suspension), of the bed can be altered by changing the fluid fraction, objects with different densities comparative to the bed can, by altering either the fluid or solid fraction, be caused to sink or float.
817:
This group contains extremely fine and consequently the most cohesive particles. With a size of 20 to 30 μm, these particles fluidise under very difficult to achieve conditions, and may require the application of an external force, such as mechanical agitation.
62:. The usual way to achieve a fluidized bed is to pump pressurized fluid into the particles. The resulting medium then has many properties and characteristics of normal fluids, such as the ability to free-flow under gravity, or to be pumped using fluid technologies.
834:
bed may settle, pack onto the plate or trickle down through the plate. Many industrial beds use a sparger distributor instead of a distributor plate. The fluid is then distributed through a series of perforated tubes.
564:
386:
At the base of the vessel the apparent pressure drop multiplied by the cross-section area of the bed can be equated to the force of the weight of the solid particles (less the buoyancy of the solid in the fluid).
204:(also called Aggregative fluidized bed), the velocities of the fluid is high, thus forming of two separate phases – continuous phase (dense or emulsion phase) and a discontinuous phase (lean or bubble phase).
105:
Furthermore, an object with a higher density than the bed will sink, whereas an object with a lower density than the bed will float, thus the bed can be considered to exhibit the fluid behavior expected of
1085:
Chaudhari, Mitesh C., "Effect of Liquid-Solid
Contact on Thermal Cracking of Heavy Hydrocarbons in a Mechanically Fluidised Reactor" (2012). Electronic Thesis and Dissertation Repository. Paper 1009.
236:(AFB): A large nozzle at the center of a bubble bed introduces gas as high velocity achieving the rapid mixing zone above the surrounding bed comparable to that found in the external loop of a CFB.
228:(FR): At velocities higher than CFB, particles approach the velocity of the gas. Slip velocity between gas and solid is significantly reduced at the cost of less homogeneous heat distribution.
926:
155:. The fluid used in Fluidized beds may also contain a fluid of catalytic type; that's why it is also used to catalyse the chemical reaction and also to improve the rate of reaction.
656:
598:
341:
381:
714:
685:
302:
765:
627:
198:
is the classical approach where the gas at low velocities is used and fluidization of the solids is relatively stationary, with some fine particles being entrained.
242:(MFR): A mechanical stirrer is used to mobilize particles and achieve properties similar to that a well-mixed fluidized bed. It does not require fluidization gas.
787:
736:
392:
343:), the bed material will be suspended by the gas-stream and further increases in the velocity will have a reduced effect on the pressure, owing to sufficient
811:
The particle size lies between 40 and 500 μm and the particle density between 1.4-4g/cm. Bubbling typically forms directly at incipient fluidisation.
900:
Peng, Z.; Moghtaderi, B.; Doroodchi, E. (2017), "A simple model for predicting solid concentration distribution in binary-solid liquid fluidized beds",
933:
1284:
1001:
978:
113:
In fluidised beds, the contact of the solid particles with the fluidisation medium (a gas or a liquid) is greatly enhanced when compared to
927:"Wang, JK, 2003. Conceptual design of a microalgae-based recirculating oyster and shrimp system. Aquacultural Engineering 28, 37-46"
1366:
658:
is the bed voidage, i.e. the fraction of the bed volume that is occupied by the voids (the fluid spaces between the particles)
152:
270:
When the packed bed has a fluid passed over it, the pressure drop of the fluid is approximately proportional to the fluid's
147:. These Fluidized bed tunnels are typically used on small food products like peas, shrimp or sliced vegetables, and may use
220:
are similar to stationary beds, but add a mechanical vibration to further excite the particles for increased entrainment.
1341:
1361:
879:
959:
58:
particulate substance (usually present in a holding vessel) is under the right conditions so that it behaves like a
867:
28:
1346:
207:
855:
82:
78:
20:
107:
215:
143:
Taking an example from the food processing industry: Fluidized beds are used to accelerate freezing in some
1371:
861:
231:
70:
24:
957:
Grace, John R.; Leckner, Bo; Zhu, Jesse; Cheng, Yi (2008), "Fluidised Beds", in
Clayton T. Crow (ed.),
1269:
1223:
1117:
271:
843:
634:
1098:
Cúñez, F. D.; Franklin, E. M. (2019). "Plug regime in water fluidized beds in very narrow tubes".
573:
310:
1247:
1213:
1182:
1164:
1152:
1133:
1107:
350:
172:
167:
In 1922, Fritz
Winkler made the first industrial application of fluidization in a reactor for a
692:
663:
1280:
1239:
1032:
974:
825:
ores are such solids, and they are usually processed in shallow beds or in the spouting mode.
168:
1315:
1231:
1174:
1125:
966:
909:
277:
74:
743:
605:
1045:
1227:
1121:
873:
772:
721:
1355:
1319:
1251:
1186:
1137:
223:
849:
180:
66:
32:
38:
1201:
1178:
1129:
93:
for the production of shellfish in integrated multi-trophic aquaculture systems.
344:
176:
144:
90:
130:
Extremely high surface area contact between fluid and solid per unit bed volume
1336:
970:
114:
1243:
179:, with fluidisation technology applied to metallurgical processing (roasting
148:
870:– Application of fluidized beds to remove VOCs/HAPs from industrial exhaust
1153:"Mimicking layer inversion in solid-liquid fluidized beds in narrow tubes"
559:{\displaystyle \Delta p_{w}=H_{w}(1-\epsilon _{w})(\rho _{s}-\rho _{f})g=}
257:
133:
High relative velocities between the fluid and the dispersed solid phase.
43:
191:
Bed types can be coarsely classified by their flow behavior, including:
1065:
86:
1235:
913:
85:, heat or mass transfer or interface modification, such as applying a
42:
Oldest power station utilizing circular fluidized bed technology, in
1218:
1169:
1112:
256:
59:
55:
171:
process. In 1942, the first circulating fluid bed was built for
89:
onto solid items. This technique is also becoming more common in
1086:
159:
necessary, according to the specifications of the application.
864:– Application of fluidized beds to reactive chemical processes
1200:
Cúñez, Fernando David; Franklin, Erick M. (2020-08-01).
1151:
Cúñez, Fernando David; Franklin, Erick M. (March 2020).
139:
Frequent particle-particle and particle-wall collisions.
69:. Fluidized beds are used for several purposes, such as
1202:"Crystallization and jamming in narrow fluidized beds"
846:– A method of separating gases and particulate matter
775:
746:
724:
695:
666:
637:
608:
576:
395:
353:
313:
280:
136:
High levels of intermixing of the particulate phase.
1279:, Midland Information Technology & Publishing,
1342:US DOE Fluidized Bed Technology – Overview website
958:
781:
759:
730:
708:
679:
650:
621:
592:
558:
375:
335:
296:
1306:Geldart, D. (1973). "Types of gas fluidisation".
145:individually quick frozen (IQF) tunnel freezers
1000:Office of Communications (November 3, 1998),
858:– Application of fluidized beds to combustion
8:
1268:Holdich, Richard Graham (November 1, 2002),
1003:The Fluid Bed Reactor:Baton Rouge, Louisiana
347:of the gas flow. Thus the pressure drop for
54:is a physical phenomenon that occurs when a
1263:
1261:
805:powder-catalyzed beds utilize this group.
307:Beyond the minimum fluidisation velocity (
1217:
1168:
1111:
774:
751:
745:
723:
700:
694:
687:is the apparent density of bed particles
671:
665:
642:
636:
613:
607:
584:
575:
547:
538:
529:
516:
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464:
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394:
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352:
324:
312:
285:
279:
1027:Grace; Leckner; Zhu; Cheng, p. 5:75
37:
892:
852:– Principles and theory of fluidization
789:is the cross-sectional area of the bed
767:is the total mass of solids in the bed
716:is the density of the fluidising fluid
196:Stationary or Particulate fluidized bed
1041:
1030:
19:For other topics on fluidization, see
7:
1277:Fundamentals of Particle Technology
876:– Other Engineering unit operations
738:is the acceleration due to gravity
65:The resulting phenomenon is called
577:
396:
14:
1337:Video: Liquid-Solid Fluidized Bed
882:– Dual fluidized bed application
153:vapor-compression refrigeration
553:
535:
509:
506:
503:
479:
470:
444:
441:
422:
240:Mechanically Fluidized Reactor
1:
1087:http://ir.lib.uwo.ca/etd/1009
651:{\displaystyle \epsilon _{w}}
1320:10.1016/0032-5910(73)80037-3
1179:10.1016/j.powtec.2019.09.089
1130:10.1016/j.powtec.2019.01.009
593:{\displaystyle \Delta p_{w}}
336:{\displaystyle u\geq u_{mf}}
261:A diagram of a fluidized bed
1009:, American Chemical Society
965:, CRC Press, p. 5:71,
880:Chemical looping combustion
376:{\displaystyle u>u_{mf}}
1388:
868:Fluidized bed concentrator
225:Transport or flash reactor
209:Circulating fluidized beds
29:Fluidized bed concentrator
18:
1270:"Chapter 7: Fluidisation"
971:10.1201/9781420040470.ch5
709:{\displaystyle \rho _{f}}
680:{\displaystyle \rho _{s}}
600:is the bed pressure drop
961:Multiphase Flow Handbook
856:Fluidized bed combustion
383:is relatively constant.
217:Vibratory fluidized beds
83:fluidized bed combustion
79:fluid catalytic cracking
21:Fluidized bed combustion
1061:Fluidisation technology
1367:Combustion engineering
1347:US DOE NETL Fact Sheet
783:
761:
732:
710:
681:
652:
623:
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560:
377:
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298:
297:{\displaystyle u_{mf}}
262:
77:), solids separation,
71:fluidized bed reactors
47:
862:Fluidized bed reactor
784:
762:
760:{\displaystyle M_{s}}
733:
711:
682:
653:
624:
622:{\displaystyle H_{w}}
595:
561:
378:
338:
299:
260:
246:Narrow fluidized beds
233:Annular fluidized bed
202:In Bubbling fluidized
108:Archimedes' principle
102:single bulk density.
41:
25:Fluidized bed reactor
773:
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693:
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351:
311:
278:
272:superficial velocity
1228:2020PhFl...32h3303C
1122:2019arXiv190107351C
844:Cyclonic separation
187:Fluidized bed types
16:Physical phenomenon
1362:Chemical equipment
779:
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728:
706:
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648:
629:is the bed height
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173:catalytic cracking
48:
1308:Powder Technology
1286:978-0-9543881-0-2
1236:10.1063/5.0015410
1206:Physics of Fluids
1157:Powder Technology
1100:Powder Technology
1040:Missing or empty
980:978-1-4200-4047-0
914:10.1002/aic.15420
793:Geldart Groupings
782:{\displaystyle A}
731:{\displaystyle g}
169:coal gasification
75:chemical reactors
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747:
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123:
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17:
12:
11:
5:
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1331:External links
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1314:(5): 285–292.
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939:on 2013-10-20
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53:
52:fluidized bed
45:
40:
34:
30:
26:
22:
1372:Fluidization
1311:
1307:
1301:
1290:, retrieved
1276:
1209:
1205:
1195:
1163:: 994–1008.
1160:
1156:
1146:
1103:
1099:
1093:
1081:
1070:, retrieved
1060:
1054:
1042:|title=
1022:
1011:, retrieved
1002:
995:
984:, retrieved
960:
952:
941:. Retrieved
934:the original
921:
905:
901:
895:
850:Fluidization
832:
821:
820:
814:
813:
808:
807:
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769:
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718:
689:
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631:
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570:
567:
389:
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306:
269:
245:
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224:
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208:
201:
195:
190:
181:arsenopyrite
177:mineral oils
166:
157:
142:
124:
112:
104:
100:
67:fluidization
64:
51:
49:
33:Fluidisation
1106:: 234–246.
829:Distributor
345:percolation
266:Basic model
121:Application
115:packed beds
91:aquaculture
1356:Categories
1219:2007.15442
1170:1912.04989
1113:1901.07351
1068:, May 2007
943:2014-01-23
887:References
798:grouping:
253:Bed design
97:Properties
73:(types of
1252:220871672
1244:1070-6631
1187:209202482
1138:104312233
698:ρ
669:ρ
640:ϵ
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