Jan. 1, 1952
w. w. ODELL
2,581,134
APPARATUS FOR CONTACTING souns AND GASES
Filed March 15, 1947
REACTANT F LU")v
FIGI
INVENTOR
-
.WlL-LIAM w. ODELL v
BZW
ATTORNEY
'
Patented Jan. 1, 1952
2,581,134
UNITED
PATENT OFFICE
.AND GASE
William wilo’delliw‘a'shington', D. 0.; assignor to”
Standard" Oil Development Company,-_ a corpo
ration ‘of. Delaware -
1
AppIi'cationMarch' 15, 1947‘,_Serial No. 734,940
3l?laiihsz= (Cl. 183-4-2)
This invention relates to‘ a. process: and an
apparatus for-‘effecting intimate contact between?
gases and solids. It relates in particular-‘to the’
?uidization of amass of‘?nely‘ dividedlsolidsf
by passing a? gaseous stream upwardly "there-‘
through at'such a velocity that‘the: particlesr'of"
which said‘ mass is'comprised are‘ maintainedfinl
a state‘ of" controlled ebullient" motionlftol e?ect‘
improved contact between the gaseous ?uid’a'ndi‘
bed" is ‘deeper than the‘ limiting- depth defined by‘
tube-diameter‘ and? particle size, large slugs‘
of powder are formed which surge up and down
the‘ contacting zone: This slugging and'surging
I results‘ from large pockets or bubbles of‘ gas
passing upwardly and carrying'sl'ugs' of solids
ahead of them. This condition is undesirable,
since it destroys the otherwise intimate’ contact
between the powder and‘ gas.
the solids. Still more speci?cally; thi‘s'i inven== 10
' In accordance with the present invention, I
tion? relates to? the passage‘ of"v a‘ gasiform'l fluid?
prevent back circulation of the gas and‘ avoid
upwardly through a bed of ‘?nely divided- solids,
slugging which would‘. otherwise occur in deep‘,
under conditions which will‘ maintain‘l-the; solids’ '
narrow contacting zones by‘ providing specially
in a ?uidized state and at the same time-deduce
or‘ prevent back circulation» or back’mix'ing‘of 15. designed: de?ecting, open-mesh, horizontal baf
?es or‘ gridsrspaced longitudinally= ofv the con
the gasiform '?uid'ian'd'the1solidsfin1the contact-‘i
tacting zone.
ing zone;
The invention will be’ best understood‘ by- ref
It has been found;- for example; thatiwhenl-ai
erence to the accompanying drawing wherein
hydrocarbonv in‘ the vaporousr phase-5 is‘ passed
Fig. 1 shows partly diagrammatically and part
upwardly througha‘ bed of"con?ned;- ?nelyidl-l
ly schematically‘ one'type of apparatus; in ele
vided catalyst» at‘ a cracking temperature fall‘llof‘
vation, in which the process de?ned herein can
the cracked» products ' formed‘ do‘ not" immediately‘
be‘ practiced;
leave‘ the‘ con?ned catalyst:v bed‘.- A? portion of?‘
Fig; 2 is a top' view of one type of'grid ba?‘l'e
the products is recirculated in. thei' ebullient?
adapted to‘ be‘ used‘ in the contacting zone;
I motion in said bed and ‘contacts the solids for a
Fig; 3 shows a, vertical sectional view of a dif
prolonged period oftim'e'; In other’ words;- the”
ferent type‘ of baffle‘ having-three connected con
hydrocarbon‘; vapors do not pass" up through the
centric'circular‘elements’; and
’
?uidized bed: of catalyst solids in verticals: p8.1"'-'
Fig. 4' isia top‘ view‘ of' the type of. ba?le shown
allel paths, but'a' substantial‘portionisi recircui
in Fig. 3.
lated back downwardly througlt- ther-bedir This" 30
In the‘ operation of‘the process, it maybe said
backi circulation of.‘ reaction products‘withithe
in‘ generalv that the known practice employing
resulting prolonged timeof contact-with‘? thecat
?uidized solids technique is followed; Referring
alyst solids, due to‘ ebullientimotion, causes an
to Fig. 1, abed of catalyst solids in- av ?ne‘ state
excessive‘ degradation- into‘ low-grade products;
of subdivision is ?uidized in reactor l by intro
such as‘ coke‘ and‘ gas;
ducing a, reactantf?-uid through conduit 2- and
One of the objects-“of. this‘ i'nventionxisg torproe
valve 3 at a velocity‘ such that the said solids
vide means to reduce" the: back: circulation of
gaseous- material in‘ the contacting zone‘;
which are-supportedon porous grid support 4' as
sume‘ebullient motion and the‘properti'es of a liq-t
uid”
having upper level indicated at'5. There
of the solids in‘ the?uidi'z'ed bed'. Aw-fu'rthe'n ob? 40
actant ?uid passes out overhead through off
ject is to‘ prevent the formation: of large gas‘
take Shaving. control valve 1. Ba?lesr are shown
pockets~ which‘ cause‘ surging or‘ slugging. of: the
at IU; H, I [and I13; A stream of ?nely divided
powder‘ in the: reactor;
solids may be introduced into the reactor I either
Still‘ another object-is to reduce-- the‘ amount
of carbon' deposit on- cracking catalyst: used: 45 continuously‘ or intermittently through conduit
l’4~~h‘aving a control‘ valve l5. A similar stream
in‘ they cracking of hydrocarbon» materials;
of'powder is‘ withdrawn from the bottom of the
Other more speci?c objects-will be?‘ apparent
reactor above the grid‘ 4' through conduit‘ I6
A» from" the detailed"v description hereinafter."
having a control valve [-1. If desiredha- part or
It has been: found, when employing;v ?uidized
solids’ technique- wherein gases are‘ contacted 50 all of the powder withdrawn through line l6
may be recirculated to the top’ in any desired
with' a relatively densepturbulent'bed of- ?nely?
manner (not shown); Furthermore, the stream
divided so‘lids,~ that‘ for‘ solids; having.‘ a1’ given
of: powder before being returned may bevv re
state‘ of vsubdivision there is‘a limiting relationship
generated or it may be heated or cooled to add
between the depth of the-‘bed’? and 'the§diametei"
of the contacting zonea~ For'ex‘amplef Wherirthe 55 heat ‘to- or extract heat from the reactor.
The/bai?es? or grids may takethe'iormof the
Another‘ object is'ltormaintainz better ‘mixing:
2,581,184
>
grid illustrated at the top of Fig. 1 and Fig. 2 or
in the form of radially de?ecting baflies illus
trated in the lower portion of Fig. l and in Figs.
3 and 4. The grid illustrated in Fig. 2 may com
prise a plurality of spaced rings i9, 20, 2| and
4
as its diameter, it has been found that a ba?ie
such as is shown in Fig. 2 placed substantially
midway between top and bottom of the ?uidized
bed prevents slugging and materially reduces
back mixing of the gases. By using a plurality
of such baffles, additional bene?ts are obtained
22 separated by radially extending spacing ele
and the per cent of open or free space in the
ments 23. This grid should have a minimum of
bailies may be larger than when one ba?le only
open space amounting to at least 50% of the
is used. When it is merely desirable to minimize
cross-sectional area of the reactor, and prefer
wall eiiect, a baiiie of the type shown in Figs. 3
10
ably '75% or 90% or more. By providing an
and 4 may be employed. .In this instance, the <
open-mesh grid of this type, no substantial re
open space in the baffle may be very great.
sistance is offered to the ?ow of the gases up
When it is particularly desirable to retard the
wardly through the grid. As a result, there is
downward travel of the solids in the reactor, the
no phase separation of the bed'into separate
baffles such as shown in Figs. 3 and 4 may be
layers within the reactor. The annular mem 15 used in multiples.‘ These ba?les may be so ar
bers and the spacing elements, however, tend
ranged in the reactor to de?ect the solids alter
to prevent formation of large gas pockets and
nately inwardly and outwardly as shown by
also assist in preventing back circulation of the
ba?le's H‘ and I2 of Fig. 1, as previously de
reactant gases downwardly through the grid.
Referring to Figs. 3 and 4, the ba?ie may com '20 scribed.
When employing a plurality of grid ba?ies in
prise a plurality of spaced rings or ?anges dis
the ?uidized bed of the’ type previously described
posed at an angle to the axis of the reactor so
and preferably spaced apart from one another,
as to divert or de?ect the mixture of ?uids and
the particles of solids fed into the bed at the
gases either inwardly toward the center of the
top are retarded in their downward travel by
reactor or outwardly toward the circumference.
virtue of the said baf?es so that they approach
The angle of the ?anges with respect to the
acondition where all of the particles withdrawn
axis should be greater than the angle of respose
through conduit or ofitake [6 have a common
of the powdered material so as to prevent the
residence time in the reactor l. The duration
powder from accumulating on the upper surface
of residence time is controlled by regulating the
30
of the annular members. The annular de?ect
rate of feed of solids through the reactor by
ing baffle illustrated in Figs. 3 and 4 should also
means of valves l6 and I1. summarily, it may
have suf?cient open spaces to offer little, if any,
be said that the ba?ies perform the following
resistance to the ?ow of gases upwardly through
functions:
,
the reactor. The grids or baf?es may be secured
(a) They retard and break up downward-swirl
to the wall of the reactor l‘ in any suitable man 35 ing eddy currents of the ?uidized solids and gas.
ner. For example, as shown in Figs. 2 and 4,
(12) They retard the travel of the solids from
the‘outer ring may be provided with horizontal
the top to the bottom of the ?uidized bed.
?anges or tabs 24 which may be welded or other
(c) They insure a more truly countercurrent
wise secured to the wall of the reactor.
?ow of solids and gas in the reactor and thus
:40
In Fig. 1 there are shown two spaced de?ect
reduce intermixing of freshly charged solids with
ing ba?ies H and I2 superimposed one above the
solids about to be withdrawn from the ?uidized
other so that the lower deflecting ba?le de?ects
bed and back mixing of gases downwardly through
the material toward the center of the reactor,
the reactor.
whereas the upper ba?le tends to de?ect the ma
(d) They tend to prevent slugging in cases
terial toward the outer walls of the reactor.
where
relatively deep beds are used.
This type of arrangement materially assists in
(c) They decrease the tendency for the ?ner
reducing the amount of back mixing of the gases
size particles of solids to be entrained in the
and assures a more intimate contact between the
fluid stream as it passes out through the top of
. gases and solids.
In ordinary practice, without baffles, the same
degree of ?uidization is not obtained through
out the full cross-sectional area of the reactor.
The solids travel throughout the bed rapidly
from top to bottom and back in swirling motion.
As the solids travel in this swirling motion, eddy
'
currents are formed which carry some of the
gaseous reactants from the top back into the
lower portion of the bed. Again, as the velocity
of flow of the reactant ?uid up through the bed
increases, a point'is reached where slug ?ow
occurs and uniform contact of solids with the
fluid no longer prevails. This critical point is
reached at different velocities for different mate
rials and different sizes of materials ?uidized.
For a given material the relation of the depth
of the bed which may be used satisfactorily is a
quite de?nite multiple of the diameter, and it
is also related to the viscosity of the ?uidized
mass.
This slugging does not occur when the
depth of the bed is not greater than approxi
mately three times the diameter. When em
ploying the same velocity of ?ow of the ?uid
stream in the reactor with the same diameter
as in the'foregoing case, but with an apprecia
bly deep bed, namely, a bed‘ six times as deep
the ?uidized bed.
One application of the invention is in the se—
lective absorption of constituents from a mixed
gas stream. In such a process it is desirable that
the relatively lean gases leaving the top of the
absorber contact the relatively fresh absorbent
material so as to obtain more ef?cient and com
plete absorption of the constituents. It is also
desirable in many cases that the individual par
ticles of absorbent material be maintained within
the absorber for a uniform period.
This latter
makes it possible to selectively control the nature
of the materials absorbed. For example, in treat
ing a natural gas for removal of natural gasoline
it is desirable in some cases to remove only the
pentane and higher boiling hydrocarbons, where
as in other cases it may be desirable to remove
also the butane and perhaps some of the pro
pane from the gas. This can be most effectively
‘accomplished by insuring that the absorbent
70 medium be retained in the abosrber for a uni
form period‘of time rather than by a widely vary
ing'period of time, as in the case of a highly
turbulent ?uidized bed of absorbent material.
The provision of the ba?les in su?icient number
within the absorber insures a more truly coun
2,681,184
tercurrent ?ow and also to a considerable degree
insures that the absorbent material be retained
within the absorber for a more uniform period
of time.
The rate of ?ow of the absorbent solids down
wardly through the absorber is controlled to ob
tain the required degree of saturation of the par
ticles discharging through line l6. The particles
so removed may thereafter be passed to a suit
able desorber which may be of a construction
similar to that illustrated in Fig. 1 in which the
solids are treated with a second stream of gas
or subjected to elevated temperature to effect a
liberation of the gases absorbed. The desorbed
particles may again be passed into the top of the
absorber through line l4 having control valve l 5.
‘It has previously been mentioned that the open
free space in the grids should be equal to 50%
solids from accumulating upon the upper sur
faces of said annular members, and spacing ele
ments separating said annular members.
‘
2. An apparatus for contacting solids and gases
which comprises an outer shell forming an en
closed vessel adapted to contain a bodyof sub
divided solids, means for introducing a stream of
said subdivided solids into the upper portion of
said vessel, means to remove a stream or said
solids from the lower portion of said vessel, sep
arate single means for introducing a stream of
gas into the bottom portion of said vessel at a
velocity adjustable to maintain said solids in a
dense turbulent ?uidized state, means for dis
15 tributing the gas so introduced over the full hori
zontal area of said vessel, means for withdrawing
a stream of gas from the upper portion of said
vessel, and a horizontal ba?‘le disposed within the
lower portion of said vessel comprising a plurality
or more of the total cross-sectional area of the
grid or ba?les. It has been found, for example, 20 of annular members having spacing elements
that, when the open spaces in the ba?les are
therebetween said annular members being dis
relatively small as compared with the closed area,
posed at an angle to the axis of the vessel greater
there is a tendency for the ?uidized particles to
than the angle of repose of the subdivided solids.
segregate into separate layers on opposite sides of
3. An apparatus for contacting solids and gases
the ba?les or grids. When this happens, the 25 which comprises an outer shell forming an en
e?ective volume of the reactor is reduced. The
closed vessel adapted to contain a body of sub
angle of the de?ecting walls from the horizon
divided solids, means for introducing a stream of
tal should be at least 40° and preferably greater
said subdivided solids into the upper portion of
than 45° in order to prevent the powder set
said vessel, means for removing a stream of said
tling on the upper surface thereof.
30 solids from the lower portion of said vessel, sep
While the drawings illustrate a countercurrent
arate means for introducing a stream of gas into
type of reactor in which the powder passes down
the bottom portion of said vessel at a velocity
wardly countercurrently to the rising gas, it will
adjusted to maintain said solids in a dense turbu
be understood that the powder may be introduced
lent ?uidized state, means for distributing the
into the bottom of the reactor either in admix— 35 gas so introduced over ‘the full horizontal area of
ture with the gas or independently thereof. The
said vessel, means for withdrawing a stream of
powder may also be introduced at an intermedi
gas from the upper portion of said vessel, and a
ate point in the reactor. The powder may be
plurality of vertically spaced coacting horizontal
withdrawn either from the top, bottom or inter
ba?les disposed in said vessel for controlling the
mediate portion of the reactor. In the latter two 40 ?ow of ?uidized solids therein each of said ba?les
cases the powder is withdrawn separately from
comprising a plurality of annular members dis
the gas, and in the first case the powder may be
posed at an angle to the axis of the vessel greater
withdrawn separately or jointly with the gas.
than the angle of repose of the subdivided solids
This invention has ‘many applications other
and spacing elements separating said annular
than those discussed.
45 members.
Having described the preferred embodiment of
WILLIAM W. ODELL.
my invention, it will be understood that it em
REFERENCES CITED _
braces such other variations and modi?cations
as come within the spirit and scope thereof.
The following references are of record in the
I claim:
file of this patent:
1. An apparatus for contacting solids and gases
which comprises an outer shell forming an en
closed vessel adapted to contain a body of sub
Number
UNITED STATES PATENTS
Name
Date
divided solids, single means for introducing a
1,873,783
Osterstrom et a1. ____ Aug. 23, 1932
stream of gas into the bottom of said vessel at a ‘
velocity adjusted to maintain said solids in a
dense turbulent ?uidized state, means for dis
2,270,903
2,344,449
2,351,793
Rudbach ________ __ Jan. 27, 1942
Ogorzaly ________ __ Mar. 14, 1944
Voorhees ________ __ June 20, 1944
tributing the gas so introduced over the full hori
zontal area of said vessel, means for Withdrawing
2,370,816,
Schonberg ________ __ Mar. 6, 1945
2,394,814
Snuggs __________ __‘ Feb. 12, 1946
2,447,116
2,461,958
2,492,349
2,495,842
Collins __________ __ Aug. 17,
Bonnell __________ __ Feb. 15,
Beck et a1 _________ __ Dec. 27,
Gilliland ________ __ Jan. 31,
a stream of gas from the upper portion of said
vessel, a horizontal lba?le disposed within said
vessel, said ba?‘le comprising a plurality of annu
lar members disposed at an angle to the axis of
said vessel greater than the angle of repose of the
subdivided solids to thereby de?ect the gases 65 Number
rising therethrough and prevent the subdivided
574,892
FOREIGN PATENTS
Country
1948
1949
1949
1950
Date
Great Britain ____ __ Jan. 24, 1946