Note: Descriptions are shown in the official language in which they were submitted.
5~5
2 A composition of stabilized fluidized m~dia, said
3 medla comprising a fluid passing upwardly through a normal-
4 ly nonfluidized mass of a solid particulate materlal in-
cluding a plurality of æeparate discrete magnetizable par-
6 ticles at a rate sufficient to fluidize said mass, said
7 media being subjected to an applied uniform magnetic field
8 which is oriented with a substantial vertical component.
9 The strength of the magnetic field and its deviation from
o a vertical orlentation are maintainad so as to prevent form~
11 ation of bubbles in the media at a given fluid flow rate
12 and with a selected fluidized particles m2keup. With these
13 media, fluid throughput rates which are up to 10 to 20 or
14 more times the flow rate of said fluid a~ incipient fluid~
ization in the absence of the applied magnetic field are
16 ~ohieved, concomitant with the absence of bubbles. Such a
17 magnetically stabilized medium has the appearance of an ex
18 panded fixed bed; there i~ no gross solids circulation and
19 very little or no gas bypassingO A bed of the magnet1cally
stabilized medium shares many qualities of the normal fluido
21 ized bed, pressure drop is effectively equal to the weight
22 of the bed and independent of gas flow rate or of particle
23 size, the medla will flow, permitting continuous solids
24 throughputO Beds of the magnetically stabil~zed media also
share some of the qualities of a flxed bed, counterourrent
26 contacting can be readily attained; gas bypassing is small
27 or absent, making it possible to achieve high conversions;
28 and attrition i8 minimal.
29 The simultaneous possession of properties usually
associated with the media of fixed and of fluid beds is
1~569~
1 highlighted, for example~ in the use of a magnetically
2 stabillzed medium to trap particulates. Like the medium
3 of a fixed bed, it will trap the particulates, like the
4 medium of a fluid bed, it will not clog ~ the pre~sure drop
of a bed of the medium will increase only by as much as the
6 weight of the trapped mater~alO
7 ~ACKGR10ND 0/ rH~ PRIOR ART
8 It is known that when a fluid flows upward through
9 a bed of solid particles at a sufficient rate of flow, the
particles in the bed move freely instead of resting upon
each other and the bed behaves much a~ a liqu~dO These
2 fluidized solid particles exhibit buoyancy of floating obw
3 ject~, surface waves, and other propertie~ normally ~ssoci-
14 ated with fluid80 High rate of mixing and heat transfer is
provided by such con~entional bedsO T~e application to
16 various drying, roQsting, chemical snd petroleum processes
17 is well knownO A fur~her advantage in the use of a fluid~
18 ~zed bed in said proce~ses ~s that the continuou~ ~ddition
19 and removal of the sol~d~ which make up the fluldized bed
provides for convenient means for removal of fines formed
21 by the breakdown of the ~olids and ~pent catalyst particles
22 when ~aid fluidi~ed ~olid~ are uset in a catalytic manner~
23 A disadvan~age of ga~ flu~di~ed ~olids ha~ been
24 noted in the art~ A~Q the velocity of the ga~ i8 increased
to above a minimum value~ bubbles are formed in the bedO
26 A bubbling fluidized bed has regions of low solid density
27 co~pri8ing ga~ pockets or void~, ~hat are referred to as
28 gas bubbles~ The formation of bubbles lead~ to bypassing,
29 81ugging and channeling which re~ult8 in the 108S of the
intimate contact between the fluid and the solid~ expected
~9 S6~ 5
l in a fluidized bed process and can lead to a breakup of
2 the solid particles.
3 In reoent years patents have issued which des-
4 cr:ibe means for suppressing bubble formation in a fluidized
bed. For example, U.S. Patent No. 3,304,249 to Katz dis-
6 closes that a stabilized :luidized bed is obtained when a
7 bed containing solids having a moderate surface electrocon-
8 ductivity is fluidized by a gaseous medium having a suffi-
9 ciently high ioniza-potential to provide a corona discharge
without arcing and subjecting a high voltage to a portion
ll of the bed to cause a corona discharge in the fluidized bed.
12 In another patent, U.S. Patent No. 3,43~,899 to
13 Hershler, there is disclosed a process ~or producing a
14 fluidized bed free of bubbles by passing a fluid upwardly
through a particulate solid fluidizable material which in-
16 cludes a plurality of discrete magnet particles having a
17 coercive force exceeding 50 oersteds to impart an upward
18 force to the solid particulate fluidizable material and
19 subjecti~g the fluidizable material to a magnetic field
varying with time in direction and intensity to impart in-
21 divîdual motions to the magnet particles. ~. X. Nek~asov
22 and V. V. Chekin, in their articles appearing in Izv. Akacl.
23 Nauk._USSR, Otdel, rekh~ Nauk ~letallurgiya i Toplivo, 6,
24 25-29 (1961) and at 1) 56-59 (1962) disclose that the for-
mation of bubbles and slugs in a fluidized bed may be elim-
26 inated ov~r a wide range of variation of flow rates by a
27 laterally applied variable magnetic field due to the inter-
28 action of this ~ield with ~luiclized ferroma~netic p.articles.
29 ~U.S. ~atent No. 3,440,731 to ~`uthill ~iscloses a
process f~r stabilizin~ and suppressing bubble ormation in
3l a fluidized bed, cGntai~ing particulate solids having crro-
32 magnetic properties ~y subjcctin~ ~h~ fluidized bed to a
-4-
1~95695
I magnetic field. While it ls disclosed that either ~n alter-
2 na~ing current or a direct current electromagnet may be
3 used, the only exarnple in the patent describes an alternat-
4 ing current electromagnet, thus producing a magnetic field
varying with time in direction and intensity. Further dis-
6 cussion of this patent is provided in Example 6 below.
7 Numerous publications by Ivanov and coworkers and
~ a publication by Sonoliker et al disclose the applica~ion
9~ of a magnetic field produced from a direct current (nontime
varying) electromagnet to fluidize iron or iron-chromiurn
11 particles such as used in ammonia synthesis or carbon mon-
12 oxide conversion. These articles include: Sonoliker et
13 al, Indian Journal of Technology, 10, 377-379 (i972); Ivanov
14 -et al, Zhurnal Prikladnoi Khimii, 43, 2200-2204 (1970);
Ivanov et al, Zhurnal Prikladnoi Khimii, 45, 248-252 (1972);
16 Ivanov et al, International Chemical En~ineerin~, 15, 557-
17 560 (1975)(also published in Chemical Industry~ 11, 856-858
18 (1975)) and The Soviet Chemical Industry, 5, 713-715 (1974);
19 Ivanov et al, Comptes rendus de l'Academie bulgare des Science,
Tome 25, No. 8, 1053-1056 (1972); and Ivanov et al, Comptes
21 rendus de llAcademie bul~are des Science, Tome 23, No. 7,
22 787-790 (1970). ln some of the published work of Ivanov
23 and coworkers a gradient applied magnetic field is used to
24 generate body forces to hold fine particles in place and
thus perrnit higher flow rates than in conventional ~eds.
26 For example, the work reported in British Patent No. 1,148~51
27 and Ivanov et al, Kinet. Katel; 11, ~Jo. 5, 1214-19 (1970)
28 varied the direction of the ~ield f~orn tr~nsvefse to axial
29 il~ relation the ~lo~.
In general, the published works of Sonoliker et
31 al and Ivanov et al, teacll that higher gas velocities can
32 be used in the presence of an applied magnetic field than
-5-
~ 69 S
l in its absence. However, Sonoliker et al and Ivanov et al
2 pr~vide no recognition of the existence of the stably fluid-
3 ized non-bubbling bed and appear to erroneously interpret
4 the transition from the stably fluidized state to the un-
stably fluidized (bubbling) state as the transition from
6 fixed to fluidized states. Furthermore, they do not teach
7 the essential role played by orientation and the signifi-
8 cance of role played by uniformity of the applied magnetic
9 field. In a uniform applied magnetic field, the bed is free
o~ any net magnetic force.
ll H. Katz and J. T. Sears, Can. J. Chem. Eng., _,
12 50-53 (1969) described a process for the stabilization of
13 a fluidized bed of dielectric particles by use of an elec-
14 tric field wherein glass bead and silica gel particle beds
were observed to behave as packed beds at flow rates (and
16 pressure drops) of fluidizing gas up to 15 times the normal
17 incipient fluidization rate. It is disclosed that the use
~8 of an imposed axial magnetic field (alternating or unidirec-
19 tional) to stabilize a bed of iron particles under the in-
fluence of a strong magnetic field ~ill impart the iron par-
21 ticles in the form of a slug.
22 S~MMARy OF Tl-E INVENTION
23 The instant invention relates to a ~luidized med-
24 ium wherein said fluidized medium comprises a fluid passing
upwardly through a normally nonfluidized mass of a solid
26 particulate material, including a plurality of separate dis-
~7 crete magnetizable particles at a rate sufficient to fluid-
28 ize said mass, said mass being subjec~ed to a uniform mag-
29 netic field ~hich is oriented to provide a vertical compo-
nent of field. Bubble formation in the medium is eliminated
3l and thus the problems kno~n in the art of bypassingD slug-
32 ging, channeling, etc. are eliminated. In ~his bullc conpc-
1~9S695
sitioll of matter procosses may be operated at a greater velocity WitilOUt sub-
stantial loss of particles from the mass of entrainment. Alternatively, the
lèngth of the fluidized bed provided by the medium may be decreased while
obta:ining the same chemical conversion in a given process. Preferably the
magnetic field is oriented in a direction substantially axially to the fluid
flow and is substantially homogenous, i.e., uniform over the entire volume of
the fluidized bed. This Eield may be conveniently prepared, electromagnetical-
ly, by means of a current-carrying coil which substantially surrounds the
fluidized bed.
The present invention provides a process for controllably trans-
porting a flowable bed containing magnetizable particles, said bed being
expanded and levitated by a fluid stream, said process comprising the steps:
a) subjecting at least a portion of said bed to an applied magnetic
field having a substantial component along the direction of the external
force field within said bed; and
b) controllably transporting said bed in response to a pressure
differential in said bed.
Preferably, there is provided a process for controllably transporting
a flowable bed containing magnetizable particles, said bed being expanded and
levitated by a fluid stream, said process comprising the steps:
a) subjecting at least a portion of said bed to an applied magnetic
field having a substantial component along the direction of gravity of at least
10 guass within said b ed; and
b) controllably transporting said bed in response to a pressure diE-
ferential in said bed, wherein the superficial fluid velocity of said fluid
stream ranges between:
1) at least about 10% greater than the normal fluidization superficial
fluid velocity required to expand and levitate said bed in the absence of
-- 7 --
'~
..1 '
~CP95695
,a:id applied magnet:i.c [;elcl; and
2) less Lhan Lhc supcrfici.ll rlu:i(l veloci.ty rcqu:ircd Lo callse timc-
varying fluctuati.ons of pressure difference througll said expanded and levitated
bed over a fi.nite period of time during continuous operation in the presence
of said applied magnetic field.
In a more preferred aspect, the invention provides a process for con-
trollably transporting a flowable bed containing magnetizable composite
particles which contain 2-40 volume percent of ferro- or ferrimagnetic material
and the balance nonmagnetic material, said bed being expanded and levitated
by a fluid stream, said process comprising the steps:
a) subjecting at least a portion of said bed to a substantially uniform
magnetic field having a substantial component along the direction of gravity
such that said composite particles have a component of magneti7ation M along
the direction of the external force field of at least 100 gauss; and
b) controllably transporting said bed in response to a pressure dif-
ferential in said bed, wherein the superficial fluid velocity of said fluid
stream ranges between:
1) more than the normal minimum fluidization superficial fluid velocity
required to expand and levitate said bed in the absence of said applied magnetic
20field; and
2) less than the superficial fluid velocity required to cause time-
varying fluctuations of pressure difference through said bed over a 0.1 to 1
second interval during continuous operation in the presence of said applied
magnetic field.
In a final aspect, the invention provides a process for controllably
transporting a flowable bed containing magnetizable particles, said bed being
expanded and levitated by a gaseous stream, said process comprising the steps:
- 7a -
.~ .
1~95695
a) subjectii~g at least a portion oE said bed to an applied magnetic
field having a substantial component along the direction of gravity; and
b) controllably cransporting said bed medium in response to a pressure
differential in said bed, wherein the superficial gas velocity of said gas
stream is greater than the superficial fluid velocity required to cause time-
varying fluctuations of pressure difference through said expanded and levitated
bed in the presence of said applied magnetic field.
~ lile not wishing to be bound by any theory~ the following theoretical
explanation is offered for tne purpose of furtller illustratlon of the invention.
Hydrodynamic stability analysis has revealed that the uniformly magnet-
ized medium in a long bed undergoes transition from the stably fluidized state
in which there is no bubbling to the unstable bubbling state oE motion under
conditions specified by the following stability criterion which has been derived.
7 1 unstable
M v
~ 1 stable
The criterion for stability when met ensures that chance disturbance
of voidages in the medium will decay so that uniformity of the medium is
preserved. NM and N are dimensibnless groups having the following
definitions:
N =
M
- 7b -
r~
.~'
5695
~ and
2 Nv 2 [~ O)XO-(1-~O)(XO-X) cos ~7] 2
4 NM represents ~ ratio of l;inetic energy to magnetostatic energy
5 o the bed solid; P is particle density (g/cm3), U the gas
6 supe~ficial velocity (cm/s), and M denotes solids magnetiza-
7 t~on (gauss). M is a function of applied field H attalning
8 a sat~ration value at high levels o applied field. Nv, the
q voidage modulus, depends on the voida~e fraction o~ the
lo chord susceptibility xO= M/H, the tangent susceptibility
11 X ~ aM/ aE~, the angle ~ between the direction of flow
12 and the direction of a wave disturbance and the orientation
13 oi magnetic field relative to the disturbance wave as speci-
14 fied by the angle ~.
For disturbance waves oriented along the direction
16 of flow cos Y is unity ~nd Nv takes on its greatest value,
17 all other parameters held constant. Concomitantly, NM
18 takes on its least value at the point of transition, so for
19 a particle having given density p and magnetization M, the
velocity of throu~put U is then at a least value. Thus,
21 ~he a~:i.al orientation of dist~rb~nce waves is the most
22 dangerous orientation.
~3 With cos Y set equal to unity the ~urther influence
24 Of field orientation may then be noted from the functional
form of Nv. Thus, field applied transversely to the direction
26 Of 1ow ~nd hence corresponding to cos ~ of zero yields an
27 infinite value of Nv. In that case there is no finite value
28 Of NM which can satisfy the stability criterion, hence:
29 transversely oriented field cannot sta~ilizc the bed. The
least value o~ Nv, all otl-er parameters held constant, ob-
31 tains witll cos 9 o unity. Ilence~ the pre~erred orient2tio.
32 of m.gnetic ~ield is par.lllel with the f1O~J ~]irection, t-hat
-8~
~95695
1 is, vertically oriented. The stabi]ity criterion discus~ed
2 above relates to a modelled bed of unbound~d extent. Ob-
3 served throughputs for actual bounded beds range from "equal
4 to" to "greater than" the estimate o~ throughput provided
by the said criterion. ~ence it will be understood that the
6 instant invention is not meant to be limited by the said
7 criterion.
8 Ideally the magnetic field should be uniform through-
9 out the bulk of the bed con~aining the matter. A uniform
field e~:erts no net force on an isolated single particle
11 or a whole bed of particles. The stabilization o~ matter
12 achieved in the instant invention is duc to local gradient
13 ~ield magnetic forces originating within the bulk matter in
14 response to inhomogeneities in bulk matter distribution
that may occur. In practice, any actual applied Lielcl wil].
16 possess nonuniformities. A sufficie~tly uniform state of the
17 stabilized matter when stabilization exists may bè insured
18 by requiring systematic forces of magne~ic origin to be suf-
19 ficiently small.
The ~7idest range of stable behavior of the medium
21 is obtained when appliecl ~ield is uniform. Thus, when field
22 is applied having a subatantial vertical component to sta~-
23 ilize the fluidiæed medium, the variation o the vertical
24 component of the magnetic field to the mean ~ield in the
bed must be no greater than 125%, preferably no greater
26 than 50% and most preerably no gréater than 10%. As dem-
27 onstrated belo~, it has been unexpectedly found tha~ non-
28 time varying vertical fields are preferred over time vary-
29 ing fields~ that Ls, it is preferr2d tl-at a direct current
(DC) ra~her than an alte*~ating current (AC) is used to
31 ener~ize the electromagne~t positioned provide the verti.~
32 cally oriented
_9_
l~9S6~5
1 magnetic fieldO Because the power requlrement~ for a given
2 mean field are le~s w~th more uniform magnetic fields, it
3 is preferred that variation of the varylng magnetic field
4 to the mean field in the bed be no more than 100%, more pre
ferably les~ than 50%9 and mos~ preferably less than 10%.
6 Generally, it may be seen that the greater the uniformity
7 of the applied field, the g~eater will be the tendency to
8 form a homogeneous bed mediumO Certain ~pecific influences
9 of nonuniform field distribution are illustrated in Examples
3, 6 and 8 belowO
11 A spat~lly uniform ~C fleld having a ~uperposed
12 spatlally uniform AC component behave~ sub tantlally as a
13 DC field provided the DC field intenslty i~ substantially
14 greater than the amplitude of the AC field component.
The fluidized particles comprlse magnetizable
16 solidsO For general economy and flexibility) it i8 prefer~
17 red that the particles~ coercivity be low or zeroO All
18 ferromagnetic and ferrimagnetic sub~tance~, including but
19 not l~mited to magnetic Fe304, ~iron oxide 6Fe~03~, chrom-
20 ium dioxide, ferrites of the form XOoFe2O3, wherein X is a
21 metal or mlxture of metals such as ~n, Mn, Cu, etc., ferro-
22 magnetic element~ including iron9 nickel, cobalt and gado~
23 linium, alloys of ferromagnetic elements, etc~ may be used
24 in the matter composition of the instant invention~ The
25 Larger the msgneti~ation M of the particle, the hlgher will
26 be the transition velocity ut up to which the bed may be
27 operated without bubbling, all other factors held constant
28 Preferably a magnetizable particle of the medium will have
29 magnetization of at least 10 gau~sO
The flu~dized compc~ition of matter msy comprise
- 10 ~
~ 3 S
1 substantially 100% of the above magneti2able solid particles
2 or msy comprise admlxture~ of ~aid magneti~able solids with
3 nonmagnetic mater~alsO For example~ ~ilica~ alumina, metals,
4 catalysts, coal, etcO may be admixed with the above materD
ials and the advantages of the in~tant invention ~till obD
6 tained. However, it i8 preferred that the volume fr~ction
7 of m~gneti~able particles exceed 25%o In other instances,
8 particle mixtures may separate analogous to liquids of
9 limited solubilityO
0 Preferably, the fluidized material~ will range in
ll particle size of from oOOl mm to 50 mm, more preferably from
12 0.05 mm to loO mmO Particles of greater dimen~ions will be
13 difficult, of course, to fluidi~e, wh~le smaller size
14 particles ~ill be difficult to conta~n in any fluidized pro~
cessO
l6 The fluidi~ed c~mposition of matter of the instant
l7 invention may adv~ntageou~ly be used in variou~ applications9
8 including but not limited to catalytic oracking, fluid hy-
19 droforming, iso~erization, coking, polymerization, hydro-
fining, alkylation, partial oxidation, chlorination, dehy~
21 drogenation, desulfuri2ation or reduction, gasification of
22 coal, fluid bed combustion of C~al9 retorting of oil shale,
23 etcO In any of the above processes 9 the advantages of calm
24 flow may be realized when the composition of natter of the
instant invention is employed in the said processO
26 In general, it has been discovered that the in~
27 stant invention for preparing stabilized fluidized matter
28 can readily be carried out in a fluidi~ed bed reactor com-
29 prising a vessel for containing the bed, a bed made up of
fluidizable particulate ~olids9 said part~oulate solids in~
~ 5~ 5
1 cluding a plurallty of separate, discrete magnetizable
2 particles, a bed fluidi~ing medium9 preferably a gas, and
3 means for g~nerat~ng a magnetic field operably connected to
4 said vessel in ~uch a manner that the mQgnetic field per~
meates substantially the total volum~ of said fluidized
6 bed9 is of a uniform nature, and i~ oriented with a ~ub
~ stantial vertical component to the flow of fluid through
8 said fluidized bedO
9 The instant invention may be better understood
o ~y relation to the ~pecific embodiment~ de~cribed below~
However, it ~hould be evident that there is no intention
12 to be limited to the~e specific embodimentsO
13 EXAMPLE 1
14 Ten grams of a ferrom~gnetic nickel~containing
catalyst supplied commercially by Chemetron Corporation
C and known as Girdler G87RS wa~ charged to an open topped
17 rectangula-r fluidi~ation chamber having ~nner d~mensions
18 of one inc~ by one and one~half inches over the cross sec~
19 tion, and a height of s~x inche~ above a porous bron~e sup-
port gridO The catalyst had been crushed and ~i~ed by
21 screening to the range 0015 to 00 42 millimeters O G87RS
22 catalyst contain~ 40 wto % nickel on a refractory carrier
23 with 45 to 60% of the nickel in the elemental formO The
24 material is pre reduced and stabilized against oxidation by
the manufacturerO The material has a surface area of 55
26 m2/g and particle superficial density of 103 g/cm3 The
27 saturation magnetization of the material a~ determined by
28 a vibrating 8ample magnetometer is 1402 cmu/gO
29 Co~x~lly 8urrounding the bed wa~ an electromag
net comprising two field coils operating on direct c~rrent,
fr~ l~ h a ~
~9 5~ ~ S
1 wired in series and producing field in a common direction,
2 both coils having an inner diameter of six inches and square
3 cross section of wound conductor of four inches, with face-
4 to-face separation of the coils of 1 5 inches The coils
provided a uniform, axially oriented field o~8Q oersteds
6 per ampere over a six inch length of te~t region. The
7 field was probed with a Hall gaussmeter and it w~s estab-
8 lished that over the test region the field was uniform with-
9 in +5% of the mean value axially, and within +1% over cross
sections transverse to the flow direction. The midplane of
ll the coils was located 40 mm above the top of the bed support
12 grid~
13 With no current supplied to the coil, hence at
14 effectively zero applied field, the bed of catalyst parti-
cles e~hibited incipient fluidization at a superficial vel-
l6 ocity, i~e. volumetric flow rate divided by empty column
l7 cross section of 2~6 cm/s. Before the superficial velocity
18 was increased to 2.7 cm/s the bed bubbled continuously.
l9 Thus, the unm~gnetized bed exhibits virtudlly no range of
operation while in the fluidized state in which bubbles are
21 present.
22 In the test described above, the point of incip-
23 ient flu~dization was determined by measurement of pressure
24 differential across the bed as determ~ned by an oil man-
ometer connected to a pressure tap below the bed support
26 grid and the readings corrected for the grid pressure differ-
27 ential determined without particles in the chamber In this
28 manner, it was established that the pressure differential
29 multiplied by the bed cross-section area and dlvided by the
weight of the bed particles equalled unity in consistent
- 13 -
~9 S ~ 9 5
1 units, as it should~ at incipient fluidization, and that
2 the pressure differential passed through a calculus max~mum
3 and then remained substantially constant at increasing
4 flow ratèsO
The magnetic field was applied to the bed and the
6 flow rate of air increased from zero until the point where
7 bubbling began, as determined by vi8u81 observationO Tran-
8 sition to the bubbling state occurred at a deinite value
9 of flow that i8 reproducible for each value of applied field
intensityO A set of values determined in this manner is
11 given below as Table Io
12 TABLE I
13 Applied Field Transition Superficial Bed Depth,
14 Oersteds ~ mm
... . .
5 0 20 6 23
6 125 21 29
280 27 34
8 400 34 36
19 520 43 37
680 51 37
21 From Table I it is seen that increase of the mag-
22 netic field increa~ed the flow rate at which tr~nsition to
23 the bubbling ætate occurred5 At the maximum applied field
24 employed of 680 oer~ed~, t~e transition flow rate of air
was 1906 times greater through the magnetically stabili~ed
26 medium than through the medium of the unmagnetized, incipi~
27 ently fluidized bedO
28 At flow rates intermediate to the inc~p~ent fluid-
29 ization rate of 2.6 cm¦s and the transitional rates given
in Table I,l~ objects, eOgO, a cork stopper or a hollow
~ 14 ~
~P~3Stii95
1 celluloid ball floated when placed ~n such bedsO These ob~
2 jects, when submerged ~n a bed and then released, in~tantly
3 were buoyed to the bed top surface, proving the fluidized
4 condition Qf the bed in the ab ence of bubbling~ Addition
ally, the ball~ when spun, continued its rotation for sever~
6 al seconds, demonstrating a low level of frictlonal torque
7 associated with the fluidized matter in this stabilized
8 mode of aggregationO
9 As flow is increaæed through the stabili~ed matter,
the beds expand to a rem~rkable degreeO Maximum expansion
of the stabilized bed at the various applied fleld levels is
12 given in the last column of Table Io The bed exhibited an
13 expansion of up to 66% of itæ as-dumped depthO Deep beds
14 are less expansive than shallow bedsO
The instant inventio~ comprises a new composition
16 of mRtter exhibiting unique propertie~0 Figure 1 illuæ~
17 trates analog thermodynamic properties in the form of a
8 phaæe diagramO The ordinate U representing superficial vel-
19 oc~ty or agitating ~nfluence is the analog of ~hermodynamic
temperature T while the abscissa giving field inten~ities
21 H i8 the analog o thermodynamic pres~ure P0 ~or concrete~
22 ne~, data of Table I are employed to plot curve AB which
23 represents value~ of superficial velocity at the point of
24 trangltion fro~ the st~ble "liquid" state L to the bubbling
'~apor" state V. Thus, AB is analogous to the boiling point
26 curve of a true liquid and the hydrodynamic neutral stabil-
D ity criterion given NMNV of unity is the analog of the
28 Clausiuæ~Calpeyron relationship for ~hcrmodynamic phase
29 change. Line AC represents the minimum fluidi2ation speed
and dem~rcates the region of fi~ed bed or solild analog region
956~
1 S from the liquid analog region L Thus line AC is analog-
2 ous to a melting point curve. The llne from zero through
3 A towards D represents normal fluidization in the absence
4 of field with bubbling occurring virtually at the point of
s fluidiæation A, there being no range of stable operation.
6 Operation at any field intensity with downward flow insures
7 attainment of the "solid" state S or fixed bed conditionJ
8 Thus, it is seen that region L represents a broàd new
9 regime within which the new composition obtains and which
offers a novel medium heretofore unavailable for the contact
1 ing of gases with solids and for other technologica] tasks.
12 The new composition has a uniform bulk density
13 and reference to column three of Table I illustrates that
14 unli~e normal fluidized matter the bulk density may be con-
tinuously adjusted simply by varying the flow rate of the
16 fluidiæing gas
17 Transport properties of the new composition are
18 unique as well For example, heat conductivity is far lower
19 than for normal fluidized matter At the transition point
the matter undergoes a change in the nature of a phase
21 change becoming bubbling fluidized matter possessing dramat-
22 ic increase in heat conductivityO Many other examples could
23 be cited of distinctive properties such as the rheological
24 properties, electrical properties and so forth.
Later in Example 4 it is demonstrated that unlike
26 normal fluidized matter but like a true liqu~d the matter
D of region L shows limited solub~ lity effect:s,
28 EXAMPL~ 2
~. .
29 In thi8 example the direction of the magnetic
30 field was transverse to the direction of air flow. The
- 16 -
95695
1 field was provided by a pair of ceram~c permanent m~gnet
2 plates having pole face dimensions of 6 inches by 3 inches
3 and each a thickness of 1/2 inchO Spaced 1D1/2 inches from
4 face to face) these magnet~ produced a uniform magnetic
field of 570 + 20 oersteds over the test regionO The midw
6 plane of the magnetic plates wa~ located 1 inch above the
7 bed support gridO
8 The bed and bed solids were the ~ame as in Example
9 1.
The response of this bed to increasing air flow
11 rate is given in Table II bel~wO
12 TABLE II
13
14 -;~ Field Superficial Bed
Intensity, Flow Rate, Dep~h9 Fluid~ Bub~
16 Oersteds cm/s mm ization
17 570 0 22 No No
18 570 006 25 No No
19 570 1~2 26 No No
570 lo 8 28 No No
21 570 20 8~ 29 Yes Ye~
22 (a~Incipient fluidization
23 From T~ble Il it may be seen that, in common with
24 the case of Example 1 wherein the field w~s vertically ori~
ented, the magnetized bet expands a great deal in response
26 to ~creasing flow of the A~upport ga~ air~ However, unlike
27 in the case of vertical field, in the present case, the bed
28 exhibits no range of stable fluidization~ In this respect
29 it beh~ves in similar manner to the unm~gnetized bedO Thus,
at the point of lncipient fluidizatian, 208 cm/s in this
31 test, the transition to the fluidlzed state was accompanied
1~9569S
1 by transition to the bubbling state at the same time,
2 I~e flow rate at which flu~diz~tion occurred in
3 this test i.s comparable to the flow rate at which fluidiz~
4 ation occurs in.the unmagnetized bed as determined in
Example 1, Had the f~eld of 570.oersteds been applied in
6 the axi~l direction; the results of Example 1 indicate by
7 interpolation that transition to bubbling would not occur
8 until flow rate equalled 4So5 cm/S9 a flow rate that is 16
9 times greater than the flow rate at which bubbling actually
o occurred,
11 At all higher rates of flow in excess of 208 cm/s
12 the bed exhibited violent slugging with chaotic flow~ At
13 all flow rates of less than 2,8 cm~s the bed medium failed
14 to float a test corkO
In accord with well known principles of physics,
16 a single magnetizable particle placed in a uniform magnetic
7 field experiences no net force. In order to experience a
8 force, a magnetizable particle mus~ be subjected to a gradi~
19 ent of applied field magn~tude, The instant invention pre~
ferably employs uniorm applied magnetic fieldO As the re~
21 sult, when voidage nonuniformity tends to develop in the
22 medium, the uniformity of the field is perturbed locally,
23 and field gradient~ created that exert corrective forces
24 returning the medium to ~ initial state of uniformity.
Gradient magnetic field in the hori~ontal direc-
26 tion can prevent the m~dium from achieving the state of
27 fluidization, as illugtrated in Example 30
28 EXAMPLE 3 - EFFECT OF TRANSVERSE M~GNETIC~ FIELD GRADIENTS
29 The 1 inch x 1-1/2 inch x 6 inch fluidization
chamber with the G87RS bed particles of Example 1 was sub~
~ 18 -
la~s~ss
1 jected to the magnetic field of a ceramic permanent magnet
2 having the dimensions 2 inch x 1 inch x 3/8 lnch with the
3 direction of magnetization through the Y/8 inch dimension,
4 The magnetic field of the magnet is gi~en in Table III for
various positions along the perpendicular from the center of
6 the magnet's 2 inch by l inch pole face. The variation of
7 magnetic field in the transverse direction across the bed
8 is about 168% relative to the mean field.
9 IAB
Position~ s (i~l/4 in? Ma~etic Field H Oersteds
11 0 420
12 l 340
13 2 220
14 3 150
4 90
6 In the range of positions given, the gradient of
7 field is nearly constant, producing a maximum body force in
18 the direction transverse to the flow of about 1.3 times the
19 force of gravity. This force ratio was computed from the
relationship (47~ g)-l MdH/ds with ~ ~ 980 cm/s2, ~ ~ 1.3
21 g/cm3, dH/ds in units of oersteds/cm, asQuming the value
22 M ~ 168 g~auss.
23 The n~gnet's 2 inch x 1 inch pole face was station-
24 ed in juxtaposition with the outside of l/4 inch thick walls
of the v2ssel1 at various stations along the bed buLk. As
26 the result, fluidization was prevented at all flow rates
27 over the range O to 60 cm/8. The nonuniform applied magnet-
28 ic field locked the particles against each other and the con-
29 tainer wall, preventing fluidization
The utility o~ the ma~netically stabilized com
- 19 -
~956~S
1 positions is expanded using admixtures of magne~izable sol-
2 ids with nonmagnetizable particulates as shown in the next
3 example. In the instant invention there is minimum tendency
4 for the particles to segregate due to magnetic attraction
of the applied field since the applied field is specified
6 as preferably uniform. As a reRult, mixture~ may be fluid-
7 ized and stabilized, exhibiting the transition behavior and
8 bed expansion properties. Thus, such mixtures may be em-
9 ployed in stabilized bed processes in addition to beds com-
0 prised of all magnetic particlesO
11 EXAMPLE 4
~ . .
12 Admixtures were prepared of the nickel impregnated
13 catalyst having a particle size range determined by screen-
14 ing of 0.18 to 0,25 mm with a zeolite cracking catalyst
having particle sizes less than 007 mmO The admixture was
16 placed into the fluidization ve~sel described in Example 1
17 to a typical depth of 25 mm~ The field source of E~ample'l
18 was utilized to provide specified levels of applied magnetic
19 field. Flow rate and bed expansion at the transition from
the stably fluidized condition to the bubbling condition
21 were noted. Results of the tests are given in Tables IV
22 and V below.
23 TABLE IV
24
o ~--Applied Field (Oersteds~
26Wt.% Ma~netics O 100 300 500 700
27 lOO 2t5 7 21 33 37
28 75 300 4 12 l9 24
29 50 ~ 0.2 l 3 5 6
~ ~ 0~2 ~ ~
- ~0 -
la~9S69S
~l~
2Bed Expansion of Adm~xtures at Transition
3(h~of Initial Hei~ht)
4 ~ Applied Field (Oersteds)~
5Wt. /0 ~ lOo ~ 300 500 700
6 100 2 27 58 6~ 70
7 75 3 18 37 ~3 45
8 50 ~1 10 18 22 23
9 0 22 ~
Admixtures containing 25% by weight of magnetics
11 did not remain homogeneously mLxed during fluidi~ationO
l2 Such a phenomenon, re~embling limited mi~cibility in liquid~
13 liquid mixtures, must be determined on an individual basis
14 for any particular admixture of bed particles,
The utility of the magnetically ~tabilized compo~
16 sitions in applications ~uch as ab or ad~orptive separation
17 of vapor species, catalyst utilization and regeneration,
18 particulate filtration and ~ubsequent bed cleaning, reac~
19 tion of solids in moving beds and ~llied applications in
which bed solids must be transported to and from the bed de-
21 pend on the fluidiæed solids b~having as a medium capable
22 of flowing in response to a pressure differentialO The
23 following example illustrates that the ~olids in the instant
24 invention are imbued wi~h fluid~like properties to a degree
that is extremely well suited for such transport.
26 ~XAMPIE S
27 A tall, cylindrical, fluidi~at~on ves~el of trans-
28 parent plastic having inner d~meter, db, of 7~37 centi
29 meters and wPll thickness of 0.44 centimeters was provided
with a circular orifice having diameter, do~ of 0.83 centi-
95~95
l metersO The orif~ce center was located 7~5 centimeters
2 above the top of the bed ~ s porou$ support gridO Quantitles
3 of o40/+60 mesh G87RS magneti2able ~olids were admitted to
4 the bed for tests in which the initial bed depth L varied
from 80U to 1402 centimeter8 above the center of the orificeO
6 The superficial air speed in all tests W8~ constant at 1506
7 cm/s. Surrounding the bed was ~he source of uniform, axi
8 ally oriented magnetic field prov~ded with~n the bore of the
9 two six inch IoDo elee~romægnetsO The applied field in
these tests was of equal inten~ity on both sides of the ori-
ficeO When the orifice was sudden~y opened by removing a
2 plug, it was observed that the bed contents is~ued as a
3 well defined jetO
4 In a separate ~est with no flu~di~ing air flow,
and with no applied field it was established that the ~rl~'
lb powders jammed the orifice at once~ and would not pa~s :
l7 through of their own accord~
8 T~ble VI provides experimental result~ obtained
l9 for the discharge of the tabil~ed fluid~ed solids through
20 the orificeO The time for ~he solids to discharge to a
21 level Lo of 400 centimeters abo~e the orifice cen~er wa~ deo
22 termined using a stopwatch~ and ~ di~charge coefficient C
23 computed as
C Y ~ 0 1 (db ) 2
26 where T is the time interval an~ g ~ 980 cm/s2, the acceler
27 ation due to gravity. It may be seen from the table that
28 the orifice coeffic~ent was con~tant at 0014 to 0015 inde-
29 pendent of initial bed depth or applied magnetic field in~
tensity over the range studied,
~ 22 O
1~95695
T~ E'~E V ~
2 Discharge CoefLicicnt Eor ~low Through an Orif;ce
3 Opening rom a Bed o ~agneLically Stabili~ed Fluid
4 Solids
Discharve Coefficient, C, Di-
6 mensionless Ap~lied Field
7 IntensiLv
8 80 Oer~eds 400 Oersteds
9 Dischar~e Time, s 9.5 --~ .15
1004 .14 ~-~
11 120 6 -~o .15
12 - 16.0 ~15 ___
13 1604 ~~ .14
14 l9o 0 o 15 ---
1~ ~ 20.6 ~-~ o14
16 The above example and Table show that the stabil-
17 ized fluidized solids flow in the manner of a liquid and
18 hence are facilitated for transport between and within pro-
19 cessing vessels. No prior art workers has reported any
measurement or experiment demonstrating this behavior. Prior
21 to the present inv~ntion this behavior for the ma~etically
22 stabilized solids was unlcnown.
23 COMYARATIVE EXAMPLES
24 U,S. Patent No. 3,440,731 of Tuthill provides an
example teaching the use o magne.ic fi.cld to s~abilî~e a
26 fluid bed. The Tuthill Exar.~le in co.l~rnon with the instant
27 invention utilized an axi~l o~ientation cf ~ield colinear
28 with the 10w directionO HGwever, the instant invcntion is
29 distin$uishable from the ~uthill Ex~mple in specifying uni-
form field in order to obtain the w~ dest range of bed
31 stabiliæation,
32 Thus ~uthill re-i~eatedly te-~ches t~t the r~neLic
A~ ~ -23-
~1 ,,
,
1~5695
1 field exelts a force on the ~gnetizable particles. As al-
2 ready mentioned it is well known that a uni~orm magne~ic
3 field exerts no force on a m~gnetizable particle within
4 said field. Ln no manner does ~uthill teach, show, or
suggest that .~ uniform field which exerts no force can use-
6 fully change fluidizationO It is the new and entirely~sur~
7 prising discovery of this invention that a new and useful
8 fluidized compositio~ of m.atter may be achieved by use of
-
~ 3~-
~ *.
' '' " ' '
~P95~95
1 a uniform magnet~c field wh~ch exer~s no forc~ In direct
2 contradiction to ~uthill it i~ a necessary condltion that
3 the magnetic field be sufficiently uniform to exert little
4 or no force inorder to achieve said ne~ 1uidiæed composi~
tion of matter. ~ailure to u~e a ~niform l~gnetie field
6 will have the result that the field exerts ~ force on ~he
7 fluidized matter7 causing ~t to be nonuniform with ohvious
8 undesirable effectsO
9 To demonstrste the impro~ed performance attendant
0 to an increa~ed uniform~ty of field~ ~he Tuthill appara~us
11 was duplic~ted and comparative tests performed ~s de~rlbed
12 in the following exampleO
13 EXA
14 An electromagnetic coil having an ~nner diameter
of 2 in. and a squ~re cross $ee~ion of 1~1~4 in. was fabri-
16 cated of 14 gage copper w~reO When supplied with 60 cycle
17 current of 1. 25 amperes 9 3O 9 volts were measured across the
18 magnetls terminalsO The lDagnet res~s~ance was 0.76 ohms
l9 and thu~ the I R power di~s ipa~edl by the m~gnet was 1. 2
wattsO A Hal-l probe positioned 9/16 inch albove the top of
21 the coil measured a iEield interl~ity of 34 gaus~. At the
22 s~me position Tuthill reports a field intensity of 365 gauss,
23 or about ten times the value fou~d hereO It is well known
24 that the field generated by a eoil of a g~Ten conductor
having a given geometry depend$ only on the power inputO
26 If it is tak~n as a fact from Tuthill~ eocample, that his
27 m~gnet also dis~ipated 1,2 watts, corre$ponding to 0~8 amp-
28 eres o~ current and resictance of lo 9 ohm) his field should
29 be smaller. It appears t~t the ~ield intensity reported
by Tuthill would require 10 times the current or 100 times
= 2~ e~
69 S
1 the power he reported7 Most likely the Tuthill field in~
2 tensity is overstatedO
3 Notwithstanding the above variance, a duplicate
4 of the Tuthill bed was prepared compr~sing one hundred and
ninety~two grams of l/8 inO diame~er carbon steel balls
6 charged to an opentopped cylindrical glass fluidization
7 chamber having an inner diameter of lol/2 inO and a height
8 of 24 inchesO At the lower end of the column the diameter
g was tapered and fitted with a gas ~nlet of reduced diam
0 eterO Near the bottom of the columm and supported by the
tapered section were several layer~ of woven stainless steel
2 mesh having about l/8 inO openingsO The me~h 1Ayers were
3 arranged with their grid axes in nonoorthogonal alignment
14 to serve as a combin2tion support grid for the balls and as
a distribution plate for the fluidizing m~diumO As such
16 this apparatu~ duplica~ed the apparatus of Tuthillo
17 The height of the se~tled bed of balls extended
18 for 2-l/2 inches above the topmost layer of meshO
19 The electrom~gnetic coil ~s supported coaxially
with the fluldization columm with ~he mldQplane of the coil
21 at a height of 4 ~/2 in~ above the topmost layer of mesh.
22 A xotameter fed by a regulated souree of compres w;
23 ed air was provided to measure the flow rateO
24 The resul~s of a serles of tests ~hat ind~cate
the influence of field uniformity on bed stabili~ation is
26 summ~rized by Table VIIIo
27 In the absence of an applied field the bed fluid~
28 ized at a superficial velocity of 807 ft~s as evidenced by
29 motion of balls at the bed surf~ceO At 902 ft/s the bed
contents exhibited circulatory moticn9 rising at the center
O 25 o
1~569S
1 and deæcending at the walls~ At 1005 ft/s the bed slugged
2 to a height of lO mmO With further increa~es of flow rate
3 the bed contents could be made to slug to any desired
4 height within the columnO The value of lOo 5 ft/s was
S adopted as ~ reference velocity, with the last column of
6 Table VII represent~ng incremental ~ncrease~ in superfic-
7 ial velocity associated with the application of the mag-
8 netic fieldO
9 With the magnet positioned above the bed the field
0 nonunifonmity was 16S% as detailed in Tablas VII and VIII~
A com~arat~ve test at the nonuni~ormi~y of 51% corre~ponded
12 to po~itioning the magnet at the level of the center point
3 of the bedO An additional te~t at nonuniformity o ll~/o
14 utili~ed another m~gnet~ one having a 8iX inch bore and
four inch lengthO
16 In all ca e~, the application of magne~ic field
17 caused a deferral of slugging to a higher value of gas
8 throughputO
19 In the test described the bed contents were obo
~erved to recirculate prior to the onset of bed ~luggingO
21 Generally~ thi~ recircul~tion is unde~irable in applica~
22 tions of ~tabili~ed beds reqllr~ng a high degree of ~taging
23 or excellenee of countercurrent contactingO It was ~us~
24 pected that ~he cau~e of recirculation wa~ the low pres~ure
drop of the 8upport grid relative to the pressure drop of
26 the bed~ A grid of lO0 me~h screen described in the example
27 below was substituted for the l/8 inch mesh of the Tuthill
28 bed ~nd cured the problemO
~ 26
~95695
0 ~
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1~956~5
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1t~95695
1 Since Tuthlll employe~ m~gnet~c cource driven
2 by an a lternating currPnt~ the directicn of field reversed
3 with timeO If the bed of partieles po~se~ an appreciable
4 remanence the rever$al of field direction can cause the
particles to rota~e or agitate in attempting to track the
6 field directionO ~he following example demon~trates the ad
7 verse influence alternating magnetic field can exert on
8 stability of such fluidiæed ~ol~d~
9 EXAMPLE 7
o The fluidl~t~on eham~er of the example g~ven pre~
11 viously wa~ modifled by removing the coar~e grid ~nd adding
12 a grid of 100 mesh screen capable of supporting powders
that are screened to ~40~60 mesh~ A packing of 1/4 inch
plastic spheres was prov~ded up~tream of the mesh to insure
a uniform approach fl~wo ~he fir~t quadrant hysteresis loop
16 for G87RS powder was determ~ned u~ing a vibrating ~ample
17 magnetometerO The saturation moment was 1308 eOm~u./gO at
18 3500 gau~ and remanence wa~ about 3 eOmoul~go A 39 mm
19 depth of the G87RS powder was placed on the grid and a ~eries
of tests performed u6ing direct ~nd then alternatlng current
21 to energize the 1~ (9 x 1-1~4'~ cros~section magnet des~
22 cribed in the previous exampleO The results of these tests
23 are summQr~zed in Table I~o Here the term "transition
24 speed" is used with a special mean~hg in reference to the
AC tests wherein although the term denotes the observation
26 of surface bubbling the bed is not truly fluidized (lifted)0
0 ~9 c~
1~95~gS
TABLE IX = INFLUENCE OF ALTERNATI~G AND DIRECT CURRENT
2 FiELD SOURCES ~ S~RFACE BUBBLING OF A MAG-
3 NETIC P~WDER HAVING REMANENCE(a)
4 Peak Field,~b~ Transition Velocity, cm/s
Gauss DC A~
6 o 13.0 13.0
7 30 15 5 701
8 60 17~8 7.. 8
9 90 20,5 9,3
120 2~ lOo 0
11 (a)39 mm depth of Q401+60 me~h G87RS~
12 (b)D~ and AC sources both 20% nonQunifGrm over the bed
13 volumeO
14 From Table IX ~t may be seen that application of
the direct current field lncreased the tran~ition velocity
16 of the bed of powders while application of the alternating
17 current field decreased the transitlon speed relative to
18 the value observed in the absence of fieldO ~hus~ alter
19 nating field is undesirable in preparing the said stabili7-ed
compositions of matterO
21 The in~ant in~ention is distingui~hab1e from the
22 Tuthill art in that time steady mdgnetic fields are pre-
23 ferred in the in~tant invention,
24 Ideally in a fluidized bed an individual particle
of the bed m~y rotate with a minimum of frictional torque
26 due to the negligible contact with neighboring particles,
27 By considering the angular displacement of a bed particle
28 having remanent moment in re~ponse to the nagnetic torque
29 set up by a reversing field, with rotation re~i~ted by
particle inertla alone~ a criterion may be obtainet indicat-
Q 3~ ~
~g~6~s
inz the range over wnich alternat:i.ng field produccs an ap-
2 preciable rotation of the particle and h~n~e pres~lMa~
3 tends to upset the stability of the bed. The cri~erion ll~y
4 b~ s~a~cd as
j7l unstable
Nc
~l stable
8 where t
Nc ~ 5 a rH
0 2 2
11 The criterion applies for field cycle times that are smaller
12 than the duration of bed operation. Thus, direct current
13 beds, which have the greatest stability, are not described
14 by the criterion. In the formula a r is remanent moment
(e.m.u./g.), H is applied field (oersteds), R is equivalent
16 spherical radius of the particle (cm) and f is frequency (Hz).
17 Table X comparing conditions of Examples 6 and 7 illustrates
18 that the criterion predicts correctly the outcome of these
19 tests. Thus, the criterion i-s suggested to delineate the
combinations of particle magnetic moment and size, and ma~-
21 netic field intensity and frequency which permit bed stabi~
22 lization to be obtained in the fac~ of al~ernating field.
23 Stability in the ~ace of alternating applied field is favored
24 by la~ge particle size, high frequency, and small remanence.
As can be seen from the above Example, the use of al-
26 ternating applied magnetic fields can be deleterious to
27 the stability of fluidized magnetized solid particulates.
; ~ 31-
~5695
1 TABLE X - SIABILITY OF FLUIDI7.ED SOLIDS TQ ALTERNATING
2 M~GNETIC FIELD
~ `~
3 Example 6 Example 7
4 Bed Media Iron spheres Catalyst powder
Particle, size,
6 R, cm 0,16 021
7 Remanent moment,lo 5 3 ~ O
8 ~ , e.m.uO/g
g Field intensity,35 30
H, oersted
11 Frequency, f. Hz60 ~0
12 Nc (computed) 0.13 11
13 Prediction Stable Unstable
14 Observation Stable Unstable
Example 3 has already illustrated the very ad-
16 verse influence that an appreciable transverse gradient of
17 field may exert on the ability of a bed of magnetizable
18 particles to be fluidizedO In the following example, it is
19 de nstrated that whe~ the applied field is vertically ori
ented it is preferable in the interest of achieving the
21 widest possible stable range of the bed at the lowest con~
22 sumption of electrical power to utilize the most uniform
23 possible magnetic field.
24 EXAMPLE 8
Various configurations of magnets, magnet posi~
26 tion relative to the vessel and magnet current were set up
27 to pro~ide discrete levels of field nonuniformity at several
28 constant values of mean fleld applied over the volume of a
29 bed of ~40/+60 mesh G87RS solids having a settled bed depth
of 39 mm~ The magnets were those described in the previous
31 examples. The bed was.the 1~1/2 inch inner diameter glass
32 columnO
~ 32 -
1~95695
l The oper~ting conditions and test results are
2 given in Table XI where it may be seen that mean f~eld was
3 set st 0, 40, ca 120~ or 400 oersteds in any given test and,
4 likewise, the variation of field ov~r the volume of the bed
in any one test was established as 136%~ 17~/o or 4%0 Transi~
6 tion speed was established by noting for a bed whose con~
7 tents had previously been aerated in the absence of applied
8 field, the flow rate at which ~teady bubbling was observed
9 at the top ~urface after magnetic field had again been ap~
pliedO The last column of Table XI list~ the width of the
ll ~table range, measured in velocity units, between the normal
2 fluidization speed of the bed and the ~peed at which bubble
3 transition occursO At the low mean field of 40 oer~teds
14 where the stable range is very narrow, about 4 velocity
units (cm/s), the precision of the data does not permit any
16 conclusion regarding the influence of field nonuniformity
17 on transitionO However, at the mean field of about ~ 0
18 oersteds it i~ seen that the field with 4/0 variation ~tabil~
19 izes twice as broad a nonbubbli~g range as the nonu~iform
17% and 136% casesO The same striklng behav~o~ i8 exhibited
2l in the te~ts at 400 oersteds mean field in which ~tability
22 over a range of width 29~1 cm/~ was achieved at 4% spatlal
23 variation in applied field while 17Zo variation reduced the
24 stable r~nge to only 1708 cm/8 o
In addition to the super~or performance attendant
26 to use of uniform field ~t i8 noted that power consumption
27 to operate an electromagnet source of field ls vastly re-
28 ducedO For e~ample, referring to Table XI, for mean field
29 of 120 oersteds, the equivalent table range i5 obtained at
136% nonuniformity as at 17%, but the power consumption as-
0 33 -
1~956~5
1 suming the magnet~g~; resistance was unchanged, was larger
2 by the square of the ratio of current, This computes to
3 (25/3)2 or 6904 times the power consumption at 136% as at
4 17% nonuniformity of field,
~ 34
~95695
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1 Throughout the foregoing the dlscus~ion has util~
2 ized the art~fice of a fluidl~at~on chamb2r operated ln the
3 presence of a gravitatlonal force fieldO It will be evident
4 that the new compo~ition of mat~er can be generated as well
in other force fields p~ided ~he flow of fluidiæi~g gas i~
6 ~n the direction oppo~ng the external force fieldO Thu~,
7 the force field m~y be due to centrifugal forces of a rc~
8 tating systemJ or for the electrical force on charged m~tter
9 in an electro~tatic field9 or to dielectrophoretic force of
0 elec,trically polariæed matter ln an electroitatLc field
11 having a field gradlent, or to forces c.~used by pr~sence o
12 a magnetic field gradient9 or to Lorentæ orce due to pas~
sage of a current at an a~le to a magnet~c field~ or duP
14 to any other force field or ~o combinations of the foregoingO
In each in~tanoe the end resul~ is ~he achiev~g of a ~table
16 form of fluid~ed matter having ~he thrmodynamic anatog
17 properties~ tran~port propertiea and other properties in~
8 herent to the state of bulk matter already described~
19 It i~ noted that wh~le the in~tant i~vention h2~
been defined in term~ of a nove~ composition of matter~ the
21 process for obta~n~ng ~aid compo~ltion, a~ cla~med below~
22 i~ al~o a par~ of ~he instant inven~ion~ Also the compo~i~
23 tion of matter di~closed above may be arranged ~hroughout
2~ the contents of a bed, or alternatively~ ~f desired, at
points or regions within a bed~ It will be understood that
26 the term point denotes a locali2ed region which ln all dlmen~
27 ~ions i8 large compared to the spacing between particles
28 and is ~m~ll compared to any dimen~icns of the bed,
iL~95695
1 _xA~LE 9
2 Example 5 demonstrated that the solids in the
3 magnetically stabilized fluidiz~d bed will flow and dis-
charge through an orifice in the vessel sidewall. 'The pur-
pose of this example is to demonstrate further that ~ovement
6 of the solids may achieve piston displ~cement with no rela-
7 tive motion between bed solids when the bed discharges.
8 Twelve hundred and eighty five grams o~ 350 to
9 840 micron G87RS catalyst ~as placed in a 7.5 centimeter
transparent plastic vessel fitted with a porous disk dis-
11 tributor. The dumped bed height was about 28.4 centimeters.
12 Eight discharge ports were provided symmetically spaced
13 aro~nd the vessel sidewall, each having diameter 0064 centi- -
14 meter with the center of each hole 3.8 centimeter above the
top of the distributor. A rotary valve permitted opening
16 the discharge ports simultaneously.
17 -A por~ion of the normally black bed solids was
18 tagged with a surface co~ting of blue pigment par~icles,
1g Ultramarine 59-4933 of Cyanamid Company, and placed in the
~ bed in layers. In the settled bed the blue colored layers
21 varied from O.S0 to loO centimeter in thickness with the
22 bottom of the lowest layer located 9.7 centimeters above
23 the distributor and the remaining layers spaced 5.0 cen~i-
24 meters apart from each other with the uppermost layer
forming the ~op of the bed.
26 The f'eld source ~as a 20 centimeter bore by lO0
27 cen~imeter long electromagnet solenoid m~de up of 12 iden-
28 tical pancake moduleseacl- h~ving thickness of 4.1 centi-
~ meters and face to face scparation of 7.0 centi~cters over
the, region occupied by the vessel. The ~pplied ficld was
31 uniorm to within 2% ovcr the tcst volumc, and in the te~t
32 applicd ield intensit~y t7as constant a~ )0 ocrs~e(l,.
_ 37~
l~g569S
1 With the ~ield applied and the discharge ports
2 c~osed, a flow of air was admitted to the vessel. As mini-
3 mum fluidization speed was passed the bed expanded with
4 further increase of flow rate and the colored bands were
5 observed to rise with the bed. The flow ra~e was brought to
6 a superficial velocity of 30.~ cm/s. The in~erfaces between
7 the colored layers and the bed remained sharply defined.
8 The rotary valve was actuated to suddenly open the
9 eight discharge ports. The bed volume then suddenly con-
10 tracted due to reduction of air flow up the bed as a portion
11 of the flow bypassed through the discharge ports. Then a
12 slower process o~ bed movement continued in which the solids13 descended and the colored layers were observed to move do~n
14 the column as bed solids discharged through the vessel side-
15 wall openings. With the bed solids about half discharged
16 the rotary valve was rapidly closed, the full upward flow o~
17 air resumed, and the bed observed to expand and accommodate
1~ the increased air throughput that once again was established
19 With the bed then quiescent in stable batch opera-
20 tion, the colored layers could be examined at leisure. In-
21 spection of the layers illustrated they were free of distor-
22 tion and that the bed ~as free of solids backmixing insofar
23 as could be detected from the appearance at the bed side
24 sur~ace and the bed top. There was no adherence of solids
25 to the wall and it was concluded the solids descended with
26 uniform speed over the bed cross section. Sufficiently
27 close to the discharge ports the flow, of course, cannot
28 remain one dimensional in character but must flow sideways.
Inspection of the solids discharged from the ports
~ revealed the amounts to be closely equal and distrib~1ted in
31 piles at nearly equal distances from the discharge ports~
32 The rotary valve again was opened and the soli~s
38
~q~95~5
l permitted to discharge fully. Motion picture photo~raphs
2 were recorded of the test and verified the above description.
3 EXAMPLE 10
4 The purpose of this cxample ls to illustra~e by
5 measurement the absence of fluctuations of bed voidage in the
6 stably fluidized magnetized bed of the present invention and
7 the presence of ~luctuations when the bed bubbles.
8 One hundred and sixty six grams of -20/~30 U.S. sieve
9 G-87RS catalystr.ære placed in a 5 centimeter I~D. glass vessel
l0 fitted with a porous disk distributor. A magnetic field of
ll 569 oersted intensity was applied to the bed. Nitrogen at
12 ambient tempera~ure and pressure was passed upward at a
13 superficial velocity o~ 5104 cm/s yielding an expanded bed
14 height of about 15 centimeters. Minimum 1uidization velocity
15 previously was found to be 23.5 cm/s as determined from the
l6 breakpoint in a curve of measured values of pressure vs. flo~
17 rate.
18 A Hall effect gaussmeter probe (Bell Z OB4-321S)
l9 was mounted above the vessel with its active element in the
middle of the bed of solids. The probe is a flat ended
2l cylinder o 0.81 cm O.D~ sensin~ the magnetic field component
22 normal to the ~lat end, i.e. the axial component o~ field in
23 the vessel. The probe was connected to a Bell 620 gaussmeter,
24 whose output was amplified by a Tektronix AF 501~ A custom
25 low-pass ~ilter h~ving amplitucle response do~m 5Q% at 70 E~z
~6 to eliminate a 5 Kl~z gaussmeter ~scillator signal then fed
n a Disa 55 D 35 RMS unit operated with a 100 second averaging
28 time, whose out,put was rccorded on a Hewlett,-Pacl;ard 7004B
X-~ recorder.
TableXI present,s the sequence o~ mean axial maglletic
31 lield -lntensities applied to the bed, the ~luctuation o~ the
32 ield expressed as a pcrccnt-a~c o~' t,hc mcan ancl thc visual]y
, .
1~9 ~6~ ~
1 o~served s~ate of the bed. Fluctuations were absent within
2 t~le precision of the measurement at mean Ei~ld in.ensities
3 of 350 oersted and greater, corresponding to a visually ob-
4 served quiescent state of the bed. The fluctuation level
rises very sharply as the field is decreased through the
6 bubble point, and more gradually thereafter. The zero
7 measured values of H rms/H means in column ~ of Table XII in-
8 dicate the complete absence of bubbl~s in the fluidized
9 medium.
.
TABLE XII
11 MAGNETIC FIELD FLUCTUATION ~ASURE~ENTS
1~ IN ~,UIDIZE~ ~G~ETIZED MEDI~I
13 Hall Probe Measurements
14 H mean ~I rms~ mean
oe. % Sta~e of Bed
16 569 O ) quiescent
17 461 O ) quiescent
18 442 0 ) quiescent
19 400 o ~ (2) quiescent
360 O ) quiescent
21 350 ? quiescent
22 309 0.6 light bubbling
23 242 1.0 moderate bubbling
24 119 1.8 heavy bubbling
2.2 heavy bubbling
26 12 5.0 heavy bubbling
27 (l)rms is defined as the root mean square o the f]uctua-
28 tion signal.
29 (2)Values listed as zero in fact were somewhat less than
the noise level a~ter correcting for measured noise,
31 hence are neglected. The neglecte~ values ranged from
32 0.004 to 0.013 percent.
33 EXA~LE 11
34 This example demonstrates the influence of particle
size and bed mass on transition velocity.
36 The bed solids were various narrowly sieved sizes
37 o~ Monel (~erromagnetically soft copper nickel alloy) having
- ~0 -
~ 5~9 ~
1 specific gravity 8.45 and particle magnetization of 372
2 ~;auss at 5000 oersteds applied field. The transparen~
3 p,lastic cylindrical fluidization vessel was 7.~7 centi-
4 ~l~ter inside diameter and fitted with a porous disk dis-
S t~ibutor. ~le fluidizing gas was air. The field source
6 ~as the 20 centimeter bore elecctromagnet described in
7 Example 9. This electromagnet was water cooled through
8 its hollow copper conductive windings.
9 ~esults of tests in ~hich le~gth of the bed and
superficial velocity of the air were determined at the
11 transition point are tabulated in Table XIII for various
12 ~mounts of solids in the vessel. At every test condition
13 the bed was observed to fluidize smoothly, the bed top sur-
14 face was flat and finely structured, and transition to bub-
bling occurred suddenly with a reproducibility of 5% or less
16 of the superficial velocity.
17 It may be seen that transition velocity increases
18 with increase of particle si7,e and decreases ~ith increase of
19 bed length. l~e transition speed of long beds tends to be in-
variant o bed length.
21 The response and expansion of a bed having a con-
22 stant mass of Monel solids is given ~s Table XIV. ~s
23 superficial velocity increases from its initial zero value the
24 bed remains unchanged in length save for a minor restructurin~
of t~e bed tcp surface. At the point of minimum fluidization
26 the be~ begins to expand. Expansion is continuous as flo~
27 r~te increases with the medium remaining ~uiescent ln the
29 stably fluidized state ~mtil the point of transition to bub-
29 bling occurs. The break in the curve o bed length versus
flo~ rate furnishes ~ deinitive means o~ determining minimum
31 fluidizatlon speed as an alternative to determlning the break
32 in thc curve of pressure drop versus 10~ ratc.
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9S
T~BLE XIV
2 RESPONSE A21D EXP~NSION OF CONSTANT ~SS
3 . MONEL SOLIDS TO IIYCKEASI~G AIR FLOW R~TE
4 Superlcial Velocity, Bed Length
U, cm/s L, cm Con~ents
6 0 20.7 Unfluidized
7 12 20.7 Un1uidized
8 18 20.8 Unfluidized
9 22 20.8 Unfluidized
28 20.8 Min. Fluidiza~ion
ll 34 t 21.5 Stably Fiuidi~ed
12 40 22.3 Stably Fluidized
13 51 24.4 Stably Fluidi2ed
14 57 25.5 Stably Fluidized
61 26.0 Stably Fluidized
16 66 26.3 Transition Point
17 Mass of Monel 2840 grams.
18 Particle size 177-250 micron.
l9 Applied field 5000 oersteds
Vessel I.D. 7.57 centimeters.
21 EXAMPLE 12
22 This example demonstrates that minimum fluidization
23 velocity o~ a magnetizable particle bed is constan~ and un-
24 affected by the presence or intensity o an applied magnetic
field and that a higher velocity of gas throughput is re-
26 quired to cause the stably fluidized bed to undergo transitior
27 rom ~he quiescen~ state to a stat:e of bubbling or slu~ging
28 motion.
29 A cylindrical ~luidization vessel of 7.49 centimet~-
inside diameter and 41 centimeter height over a microporous
31 support grid is loaded wlth 3110 grams of C1018 iron spheres
3~ s~pplied by Nuclear Metals Corporation. The iron spheres
33 are screened to the size range of 177 to 250 microns. The
~4 bed length with initially loaded solids is 15 centimeters.
The ma~netic field source is the pair of 6 inch bore electro
36 magne~s, each havin~ len~th of 4 inches and face to ~ace
43 -
~ ~g 5~ 5
1 ~e~ar~tion of 1.5 inches. The magnetic field is orlente~
~ co~near with the bed flow axis, with the ~enter of the
3 m~gnet pair at the center of ~ravity of the bed contents.
4 T~e fluidizing gas is air.
A long straight glass tube of 6 mm O.D.and 4 mm
6 I.D. is inserted vertically into the bed to sense gas pressure
7 in the bed. The tub~ tip is positioned one centimeter above
the bed grid and a U-tube manometer connected to the other
g end of the tube. The bed is fluidized in the bubbling re-
gime in the absence of field, then collapsed by stopping the
11 gas flow before the beginning of a test sequence. The mag-
12 netic field is applied in the absence of flow, and pressure
13 measured in response to increases in 10w rate at the constant
14 magnetic field s2tting. -
Magnetometer measurement of the iron solids using
16 the vibrating sample technique gives the values of magnetic
17 moment listed in Table XV.
18 T~RLE XV
19 MAGh~ETIC MOMEN~ GF ],~7-250 ~CRON Cl018
20 STEEL SPHER~S~ IN APPLIED FIELDS
21 Applied Magnetic Magnetic ~Ioment ~agnetiz~-on
22 Field, H, Oersted _ a, emu/g M, gauss~
23 0.026 ` 2.6
24 16 0.6~ 67
32 1.~ 127
~6 48 l.SG 1$4
27 64 2.45 242
28 80 3.03 300
2g o(4) 0.030 3-0
(1) Sample mass of Q.3329 grams in cylindrical sample holder
31 of about 3 mm I.D.
3~ (2~ Saturation moment in 16,000 oersteds ~pplied ~ield o~ 212
33 emu/g or 20, 970 gauss.
34 (3) M ~ 4 ~pa with densi~y p taken as 7.~7 gram/cm3.
3~ (4) Reduced ~rom 80 oersteds.
_ 44 -
~ , ~
1~9~i6~5
l The remanent magnetization o 2.6 to 3.0 gauss is
2 ~mall compared to the magnetiæation values at the a~plied
3 field intensities, hence the material may be regarded as
4 ferromagnetically soft in this uorking range.
Table XVI lists ~alues of pressure drop across the
6 whole bed length versus superficial flow rate at various
7 intensities of applied magnetic field. Fig. 2 presents the
8 data plot for the field intensity of 48 oersteds. The
9 breakpoint of the curve is taken as the point of minimum
fluidization. Values of minimum fluidization vel¢city UMF
ll obtained in this manner are tabulated in the second column
12 of Table XVII. There it may be seen that minimum fluidization
l3 speed has a sensibly constant value independent of applied
14 field intensity.
From column three of Table XVII it is seen that
16 bed length is constant and unchanging below the point o~
17 minimum ~luidization. The bed expands at 10w rates greater
18 than minimum fluidization velocity, reaching the length given
19 in the ~fth column of Table XVII at ~he point of trarisition
to ~he bubbling state. The transitlon to bubbling or slug-
21 ging occurs suddenly as determined by v;sual pbservation.
22 S~eady surface bubbling or a minimum duration of about 30
23 seconds is taken as criterion ~or the transition, witll the
24 velocity at transition denoted UT . Values of UT are tabu-
lated in the ~ourth col~n of Table XVII. At H of 64 and
26 7~ oersteds, transi~ion was ~o slugging.
27 Fig. 3 presen~s the diagram that results from plot-
28 tingl~ and UT versus applied field. The magnetically stabil-
~ ized state of 1uidized so].ids is deined by tlle region be-
~een the curves o~UMF and and UT. This region provides a
31 broad operatlng range in ~hich thc medium is fluidlzcd yet~
32 quiescent and ree of bllbbl s or solids baclcmixing. The bed
7~ ''~
9S695
1 ~edium in this region is-facilitated for transport, e.g.
2 into or out o~ the containing vcssel.
3 TABLE XVI
4.INFLUENCE OF ~l~OW RATE ~ND APPLIED FIELD
5INTENSIT~ ON p~ sur~E DROP FOP~ FI~J OF
6AIR TIIROUGH A BEr~ Ol IRON SPIIERE~S(l) ~ (2)
... .... . .... _ . ~ _ _ _
7 Flow Rate, U ' ~ Applied Field Intensity,H, Oersteds---
~ cm/s 0 16 3~ 48 64 72
9 1.88 ~~ 0.54 0.65 0.570.60 0.~1
4.25 1.5 1.4 1.5 1.5 1.4 1.5
11 6.75 2.4 2.1 2.4 2.4 2.2 2.2
12 9.50 3.4 3.1 3.3 3.3 3.3 3.3
13 12.3 4.5 3.9 3.9 4.~ 4-3 4-3
14 16.7 4.6 4.5 4.2 5.1 5.4 5.4
17.9 4.6 4.6 4.3 5.1 5.7 ~.6
16 22.5 .'4.7 4.7 4.3 4.9 5.8 5.1
17 25.3 4.6 4.6 4.8 5.1 ~.6 5.3
18 29.5 4.6 4.6 4.8 5.3 .~.9 5.4
19 35.1 -- 4.6 4.8 5.3 5.4 5.5
42.2 ~- ~- 4-9. 5 3
21 49.2 -- -- -- 5.2 5.4 5.5
22 70.0 5.2 4.
23 g8.0 -- -- -- ~ 5-5
24 (1) Pres~ure units are centimeters of mercury~ extrapolated to
support grid surf2ce based on linear change with distance.
26 ~2) C1018 steel 1~7~250 microns.
27 The final column of Table XVII tabul~tes the platc2u
28 value o pressure drop normali,ed by the ratio of bed mass
2~ to bed cross section area A; this quantity th~eoreticall.y
equals unity when expressed in dimensi.onally consistent units.
31 The ex~erimental values are i.n reasonable agreement with the
32 the~retical expectation and verify thc existence of the fluid-
33 ized state of the bed in both the s,tabilized and bubbling
34 regimes, i.e. ~egions in which velocity U is less than ~nd
grea~er than UT, respectively.
36 Sonoliker, R.L. et al., Indian Journal of l'ec}lllolo~y,
37 ~0, 377 (1~7~) report observa~ions of fl.uidized iron pow~ers
38 subjected to an axially orlented applied magnetic field. In
~1~95695
.
1 pa~icular in Table I of Sonoliker et al., e~erimental re-
2 ~ults are given for the minimum fluidization velocity of iron
3 particles, including results for particles of 244 microns
4 dia~eter, hence comparable to the size range studied here.
~ The values of minimum fluidization velocity in Sonoliker et al
6 increase exponentally ~ith applied field intensity. This
7 is in marked contrast to the sPnsibly constant value of mini-
8 mum fluidization velocity characterizing the instant inven-
9 tion and illustrated by values in column t~o o Table XVII
below. It is possible that Sonoliker et al observed transi-
11 tion velocity UT and identified it as minimum fluidization
12 speed UMF. Accordin~ly, Sonoliker et al might have passed
13 through the stabilized region in a transitory manner in their
14 experiments. In any event it is clear that Sonoliker et al
provide no teaching of the existence of a stably fluidized
16 region as instantly claimed. In vie~J of the r~ ort of
17 Sonoliker et al the performance in the instant process and
18 the properties of the medi~ thcreby generated are totally
19 u~exFected and surprising.
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