June 16, 1942.
T. |A=. SIMPSON EJTAL
METHOD FOR HEAT TR'EATMEITT vFOR SOLID PARTICLES
Filed i’eb. '28, 1940 '
2,286,654
Patented June 16, 194-2
2,286,654
,3)
UNITED STATES PATENT OFFICE‘
’“
2,286,654
METHOD FOR HEAT TREATMENT FOR SOLID
PARTICLES
‘
‘
Thomas P. Simpson, Vladimir A. Kalichevsky, and
John W. Payne, Woodbury, N. J., assignors to
Socony-Vacuum Oil Company, Incorporated,
New York, N. Y., a corporation of New York
Application February 28, 1940, Serial No. 321,185
4 Claims. , (01. 252-281)
This invention relates to a method of treating
This invention has for an object the provision
solid materials in particle form with gases or
of a method of and apparatus for treating a
vapors, under exothermic or endothermic con
i moving stream of solid particles at elevated tem
ditions, at closely controlled temperatures. Such
peratures with accurate temperature control over
operations are used in the regeneration of spent
the solids being treated throughout the period
adsorbent materials, the roasting or calcining of
of their treatment.
I
ores, and similar processes. The: regeneration or
Another object is the provision of a method of
reactivation of spent solid granular adsorbent
and apparatus for subjecting stream of solid
material, such as fuller‘s earth used in a decolor
particlesto'the action of gases or vapors wherein
izing ?ltration, as for example on petroleum oils,
accurate and ‘constant control of an elevated
is typical and presents most of the problems pre
temperature of treatment is utilized to effect a
sented by any similar operation.
treatment of more uniform degree.
In regeneration of petroleum ?lter clays, for
A further object is the provision of av process
instance, as carried out today, the clay su?ers
and apparatus wherein a granular adsorptive
a loss in e?iciency with each burning or regen
material is suitably ?owed in contact with and
eration until ?nally it cannot be regenerated to
generally countercurreltlt to an activating gaseous
a sufficiently high activity to warrant further re
medium while controlled temperature conditions
generation, at which time the clay is discarded
are maintained.
‘
i1
to waste. Since clays which have'had a different
Still another speci?c object of the invention is
‘ number of burnings have di?erent efficiencies,
‘to provide a practical method of and apparatus '
they are usually kept separate and,‘ separately}
classi?ed. In general ?lter clays are only re'gen-i
erated about ?ve to eight times arid practically
for regenerating a'moving stream of spent ad
sorptive material such as ?lter clays, catalysts
and the like having carbonaceous impurities de
never more than ten to ?fteen times before'they
posited thereon. by reacting said carbonaceous
are thrown away.
impurities'with a gaseous oxidizing medium‘
l
'
The problem of regenerating clays is ‘compli
cated by the sensitivity of the clays to high
temperatures. While temperatures around 900°-v
which method suitably ?owstthe adsorptive ma
terial countercurrent to the gaseous medium and
controls the temperature of the adsorptive ma
1150° F. are desired to burn off impuiities from i terial such,‘ that e?icient regeneration will be ef
the clay, temperatures around 1300", F. may per 30 fected, without subjecting the material to dele
terious temperatures.
manently injure the clay. Moreover, if the tem- '
perature falls too low, inefficient regeneration
Another object is the provision of a method
results. The problem of keeping the temperature
and apparatus capable of accomplishing high
of the clay Within safe limits is greatly. increased
unit throughput per unit of capital invested and
since the combustion reaction involved in burn 35 space occupied.
ing o? the impurities evolves ‘ ’consid’erable I
A further object is the provision of a method
amounts of heat and can very easily become so
{and apparatus which permits more ei?cient utili
rapid as to get beyond control temporarily, either
zation of the heat developed in the apparatus.
generally or locally. Probably one of the prin
These and other objects will appear from the fol
cipal reasons for the successive losses in activity 40 lowing description of my invention.
'
of regenerated clay is the fact a certain amount
In this present invention, moving, particle form
is overheated or underheated each treatment.
solids are treated with ?owing gaseous agents, "
In view of the fact most clays to be regenerated
vunder closely controlled conditions of elevated
have more than enough carbonaceous material
temperature, by passing them countercurrently
deposited thereon to furnish the heat required 45 to the gases through a treating zone wherein re
for regenerating, it is quite probable that present
peatedcontact of the solids and gases are ac
methods in general permit overheating; this ap
complished and Wherein' every particle of solid,
pears ‘to be true, moreover, from the fact it
is repeatedly brought into contact with tempera
would be extremely difiicult to control precisely
ture control means and, is thereby'kept within
the temperature of all the clay in present meth 50 a suitable treating temperature range without‘,
ods and apparatus.
being subjected to undesirable temperatures.
It has been found that considerable increases
Provision is made ,not only for longitudinal flow
in ef?ciency may be achieved by applying accui
of the solids through the treating zone, but also
rate temperature control to existing methods and
for repeated agitation, redistribution and added
apparatus.
55 contact of ,the solids with the gases, being so ar
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9,986,054
ranged that each portion of solids receives a sub
stantially uniform treatment.
As has been indicated above, the present in
vention may be used in the treatment of ?nely
divided solids in general. Particularly typical of
materials that may be treated by our invention
are those spent ?lter clays and adsorbents de
rived from the ?ltration of mineral oil products
such as waxes, turbine and transformer oils and
particularly the usual lubricating oils; also from
the ?ltration of vegetable oils; sugar liquors; etc.
These spent clays or other adsorbents contain
adsorbed combustible materials such as tarry,
material to be treated may be introduced into
the kiln.
Internally, however, we have modi?ed the kiln
by the introduction thereunto of the tube bundle
composed of tubes l2, disposed in cross section
as shown in Figure 2, for a purpose later dis
cussed. Each tube |2 extends substantially
throughout the length of the kiln, and is equipped
with extended surface, which may takethe form
of ?ns l3, which are more clearly shown in Fig
ures 2 and 3. Each of the tubes I2 is arranged
to act as a conduit for a ?uid heat exchange
medium l4, and the tubes, in one form of con
struction enter into an internal surge tank I5,
oily or carbonaceous matters and are regen
erated for re-use by the heating or burning of 15 placed within and near the inlet end of the kiln.
Surge tank I! is provided internally with a baf
the carbonaceous material adsorbed thereon. In .
?e I6, placed at about its midsection and with
some instances it may be desirable to burn off
two vent pipes II, as shown particularly in Figure
only inactive carbonaceous impurities while car
2. The entire assembly of tube bundle and surge
bonizing a part of the carbonaceous impurities
to form an active carbon layer on the adsorbent. 20 tank is a?ixed to the kiln shell, as indicated at
|8-|8, and rotates therewith. When the tubes
Other typical materials which we may treat
and surge tank are ?lled with a ?uid-heat trans
are solid particles of catalytic materials which
fer medium to a point above the middle of surge
have been used in some catalytic process of re
?ning or conversion until sufficiently contami
tank l5, and rotated, there is provided‘a con
nated with impurities that regeneration or re 25 tinuous cyclic circulation of the ?uid medium
through the tubes l2 and the tank l5, assisted
viviiication is required or desirable and wherein
by the action of the partition I8 and vents I'I.
the inactive impurities deposited on the catalyst
At the opposite end of the kiln from the surge
are removed by treating the catalytic material
tank, further modi?cations are made, while pre
at elevated temperatures. For instance, in the
catalytic cracking of petroleum oils using a ?nely 30 serving the usual exit for treated solid at l9 and
the usual inlet for treating gases at 20. At this
divided solidcatalyst material, e. g., clay-type
end, there is provided a chamber 2|, which may
catalysts, the catalyst becomes contaminated
be isolated from the interior of the kiln, as by
with a carbonaceous deposit of the nature of
plate 22. Chamber 2| is provided with a stack
coke which must be removed from time to time
in order to regenerate the catalyst, and this re 35 23 and may be provided with either a fan 24
or a burner 25 or both. Tubes l2 extend into
moval is usually effected by burning oil! the im
purities at closely controlled elevated tempera
chamber 2| and are joined in a circular header
26 and throughout their length exposed in 2|
are preferably equipped with extended surface in
For convenience the present invention will be
described in detail with respect to regeneration 40 the form of ?ns 21. It is to be understood, how
ever, that any other feasible construction might
of spent petroleum ?lter clay. However, it is to
be used for providing the heat transfer tubes
‘be understood the invention is not limited there
tures.
"
to but is directed to the whole ?eld of regenera
within the kiln and for circulating a temperature
tion of spent adsorbents and catalysts by bum
controlled ?uid heat exchange medium through
ing off inactive impurities as well as to the initial 45
preparation of same when necessary including
the tubes.
.
In operation‘ solid material in divided form,
such as fuller’s earth to be revivi?ed, is fed in
at H and passes down through the inclined, ro
tating kiln to exit at l9. While so passing, it
vantage for the heat treatment of, ?nely divided 50 encounters and passes countercurrent to treat
ing gas introduced at 20 and departing by the
solids in general, as, for instance, roasting of
?ue I0. Due to the rotation, the solid material
ores, showing decided advantages for treatments
not only advances, but is repeatedly carried up
wherein close temperature control is a necessity
the side of the kiln and showered upon the heat
or a highly desirable condition and reactions are
transfer tubes II. If desired, shell bailles, as at
involved which produce or consume a consider
28, (see Figure 2), may be added to assist and
able amount of heat.
‘
enhance this action.
In order that the invention may be readily un
The desired temperature conditions for the
derstood, reference is now made to the draw
ing attached to this speci?cation, wherein Figure _ reaction are established by means of a ?uid heat
1 is a longitudinal section of an apparatus suit 60 transfer medium circulated in tubes [2, and
adjusted in temperature in chamber 2|. If the
able for the practice of our invention, Figure 2
reaction in kiln 4 evolves too much heat such
is a cross section thereof, and Figure 3 is a de
as certain highly exothermic reactions, heat may
tail cross, section of one element of the appa
be removed by operating fan 24 to cool the heat
ratus". ' ' 'v
The apparatus as shown in Figure 1, consists 65 transfer medium I4 in tubes l2 by extracting
heat therefrom by the ?nned extensions of tubes
essentially of a modi?ed rotary kiln. In the
I2 into chamber 2|. If the reaction consumes
diagrammatic longitudinal section of Figure 1,
heat such as certain endothermic reactions, heat
4 denotes the shell of the rotary kiln, which may
may be supplied by burner 25. If, as is more
be externally covered by an insulating Jacket 5
usually the case, the reaction requires addition
and may be lined with an internal insulating or
of heat through a portion of the length of kiln
refractory lining 6. As is usual, the kiln 4 is
4 and requires extraction of heat through an
supported by roll rings 1 and ‘I, and is rotated
other portion of the length, the ?uid heat trans
through the agency of a gear ring 8 and drive
fer medium circulating through tubes |2' will
pinion 9. At its upper end, the kiln is provided
with the usual stack I0 and feed pipe |l whereby 76 serve to transfer heat, 1, e., adding or abstract
activating, dryin'g, hardening and the like by the
application of heat. Likewise the present inven
tion, as has been stated, may be used to ad
o
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‘r
_
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2,286,654
‘ing, along the length of kiln 4 as needed, leav
ing only the overall surplus or de?ciency ad
Justment to be performed in chamber 2|. Since
this method permits the convenient introduc
tion of heat into a rotary kiln without necessi
tating the introduction of combustion gases
thereunto, and since in many instances the re
action- conducted may be self supporting from
a fuel basis, a separate entry for treating gas
is normally. provided at 20 and isolating plate
22 is used, although in some cases, as where a re
ducing atmosphere is desired, it may be provided .
by removing plate 22, and utilizing chamber 2|
as a source of ‘?ue gas for treating.
The heat transfer medium in tubes I2 trans
fers heat to or from the reaction by a combina
tion _of radiation and conduction'both to the
ture changes whereby no deleterious tempera:- '
tures occur,
._
When the operation is ?rst started the heat
exchange medium‘ may add some heat to help
initiate the reaction or treatment, or at least the
medium should not be at such a low temperature
as to substantially hinder such initiation. After
the operation is started the exchange medium is
circulated throughout the zone adding or ab
stracting heat as required. In our invention the
heat exchange medium is maintained at all points
in the regenerating zone at a temperature below
temperatures which cause substantial damage to
the clay (or if other operations are being con
ducted, below temperatures which cause heat
damage thereto), and, of course, at a temperature
above which undue cooling occurs so that the
regeneration (or other treatment) cannot proceed
_ gaseous atmosphere and to the solids which are
e?iciently. For instance, in the usual regenera
' brought into contact with the tubes I2 and ?ns
I3. Consequently the detailed proportioning of 20 tion of ‘filter clays and the like we preferably
maintain the heat exchange medium at a temper
the tubes l2, ?ns l3, and ?ns 21 may vary widely
ature around 850°~900° F.'and never above about
for different purposes.‘
1050° F. Byv so controlling the heat exchange
. The heat exchange tubes should, however, be
medium
and ?owing a su?icient amount within
so arranged that efficient contacting with solid
su?iciently
close indirect heat exchange with each
undergoing treatment can be had, and to this, 25
particle, a close uniform temperature control‘is
end a peripheral position may be preferred, since
tubes placed near the interior wall of the kiln . maintained over every particle so that no delete
rious temperatures occur which cause injury to
will be buried at least partially when at the bot
the particles or treating operation. Moreover,
tom of the kiln and will be showered with solid
as they rise. Further, the arrangement of ?ns, 30 the entire zone will be maintained under the
same close uniform conditions.
if used, can be such as to promote contactof
While temperature-controlled, circulating gase
this nature as well as to further heat trans
ous heat exchange mediums of high specific heat
fer between the heat transfer medium and the _
might be used in some instances, we greatly pre-‘
fer the use of liquid heat exchange mediums since
Further, the amount of heat transfer surface,
necessary pumping and pressure facilities for
the temperature of the heat transfer medium,
proper use of even the best gaseous mediums,
and the rate of circulation of the heat transfer
e. g., hydrogen, would, in many‘instances, render
medium should be such that desired conditions
the operation commercially impractical. _
can be maintained. For example, upon mate
The liquid heat exchange medium to be used
rials of the nature of contaminated fuller’s 40 is preferably one which at the temperatures en
earth from petroleum ?ltration, or contaminated
countered is possessed of a low vapor‘ pressure, a
clay-like catalyst particles, both of which must
high speci?c heat, a suitable viscosity and is‘ not
be at or above‘ about 800° F. to burn and both
corrosive to the usual metals and other materials
of which are usually damaged by temperatures
which may be used in construction of the ap
much above 1200” F., the rate of heat removal
paratus. Many normally solid materials in their
should be such as to permit removal of car
fused state form excellent heat exchange medi
bonaceous matter at rates ranging from about
ums such as fused salts and fused metals and
gases.
,
1% to about 10% of carbon (based upon weight
alloys. In the regeneration of clay, we prefer
"of clay fed per hour) with probable preferred
the use of fused salts. A particularly preferable
ranges of operation being around 3% to 6% of 50 mixture of this kind isa mixture of the alkali
carbon per hour, while not permitting rise of
metal salts of nitric and nitrous acids. In cer
clay temperature above about 1100° F.
tain cases suitable liquid heat exchange media
An important feature of the present invention
might be found which have a boiling point around
is the proper use of ?uid heat exchange medium ,
the desired operating temperature, in which case,
and the structure whereby the solids are inti 55 the heat exchange medium, although mostly in
mately contacted with counter?owing gases
the liquid state,’ might undergo some transition
while each individual particle of the solids, dur
whereby advantage could be taken of its heat of
ing substantially the entire duration of'the re
action, is withinclose proximity to the heat ex
change medium so that no deleterious tempera
" vaporization or condensation.
By the use of liq
uid heat exchange medium and by having them
60
in sufficiently close proximity to all particles un
ture condition is created.
,
dergoing reaction an extremely close and uni—
In order to obtain proper temperature contro ,
form temperature control may be maintained.
the heat exchange medium must be adjusted to a
. In the preferred practice the heat exchange
proper temperature, for extracting or adding the
medium is maintained at substantially the tem
65
necessary heat. Moreover, heat exchange me
perature of the treatment being controlled. Such
dium must be ?owed in suf?cient amount in
practice may be carried out because the heat
close- indirect heat exchange with every solid '
exchange medium is a liquid and has a relatively
particle and then cooled or heated to readjust
high speci?c heat and the structure of the ap
paratus is such that heat exchange medium is
its temperature by means extraneous of the re
brought within close proximity to every granule
action heat before the medium’s temperature
in the apparatus. Hence considerable ?uctua
reaches an undesired value. In this way the
tions in temperature in either direction can'be
heat exchange medium in our invention con
compensated by the liquid heat exchange medium
tinuously controls the temperature of the zone
making immediate compensations for temperae 75 without substantially altering its temperature
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2,286,654
and if the" fluctuation is too great suitable cooling
or heating of the heat exchange medium in its '‘
circuit will still maintain the liquid at the treat
ing temperature: Thus if a sharp brief rise in
temperature occurs which normally woulddam
age the clay before it is indicated, if ever,‘on a
temperature responsive device and suitable ma
nipulation effected to offset the rise, in the pres
ent method the liquid heat exchange medium
would immediately and automatically offset the
rise by absorbing any excess heat so that delete
rious temperatures would not be created. Like
wise if the temperature fell off sharply so that
normally the temperature would go so low that
the shell 4.
Or the surge tank may be dis
pensed with and circulation afforded by means
" of a pump.
Or in another form, the tube bundle
need not be rotated with and supported by the
shell 4, but may be independently supported and
stationary, extending into shell 4. However, all
of these obviously provide in one form or an
other, a tube bundle transversing the reaction
space, wherein a fluid heat transfer medium may
be circulated to control temperature condition
in that reaction space, and we deem all such to
be within the con?nes of our invention.
Throughout this speci?cation and in the claims,
the terms solid particles, solids, solid materials,
ineiiicient regeneration would result, this ?uctua
tion likewise would be immediately and automati
etc., where applicable, mean not only the solid
tant advantages are obtained. For instance, in
the regeneration of ?lter clays the customary loss
in efficiency with each regeneration may be sub
terial with a gaseous oxidizing agent, wherein
but also any other solid or liquid matter that
cally offset by the liquid heat exchange medium _
may be associated therewith, as, for example, the
which would add heat to the cooling granules.
carbon and oil associated with a spent ?lter clay
As a result ofthe close uniform temperature
which is undergoing treatment.
control aiiorded by our invention many impor-‘ 20 We claim:
stantially reduced or even eliminated. Further,
the operation may be substantially changed. In 0 \
customary practice great excesses of air over the
theoretical amount required for combustion are
used in order to a?ord cooling. As a conse
quence the combustion is not conducted as e?i
,ciently as an exothermic reaction might be and 30
, 1. In a method of reacting solid particle ma
the solid material is flowed downwardly ‘through
an inclined oxidizing zone while the gaseous
agent is ?owed upwardly through the zone in
direct contact with the particles under oxidiz
ing conditions, and wherein the solid material
is continuously mechanically agitated by con
tinually rotating the said zone, .the improvement
which comprises maintaining the temperature of
generally additional fuel must be added to the
all the particles in said zone within the tem
clay. Since we have close uniform control over
perature range between the minimum oxidizing
the apparatus the amount of excess air used may
temperature and the maximum oxidizing tem
be substantially reduced or eliminated whereby ‘ perature that does not cause substantial heat
the expense bf added fuel is correspondingly re-. 35 damage, said temperature range being main—
duced and further the heat exchange medium
tained by circulating a liquid heat exchange
may even extract heat rather than add heat.
. medium through the interior of said rotating
As will be obvious from‘ the above descrip
zone in close indirect heat exchange relationship
tion, the operation of the regeneration process
with all the particles in said zone while main
‘is controlled by regulating, in connection with 40 taining the temperature of said heat exchange
' the rate of ?ow of the adsorbent, ?rst, quantity
medium substantially within said temperature
of air used and, second, the temperature and rate
range whereby heat immediately may be added
of circulation of the heat transfer medium
to or extracted from said particles as becomes
- through the heat transfer tubes.
necessary during operation.
An important feature of this invention is the
ability to obtain accurate temperature control.
That accurate temperature control is of impor
tance is readily proven by the fact that spent
petroleum ?lter clay when treated under condi
tions usual in the art must be discarded after
about ?ve burns, while, if treated under proper
and accurate temperature control, it is substan
tially unimpaired in ?ltration ei?ciency even after
2. In a method of regenerating spent absorbent
particles such as clay and the like which are
15 to 20 regenerations.
Since one may now dispense with the enor
mous quantities of excess air normally ‘used for
the usual inaccurate temperature control, a more
ef?cient utilization of exothermic heat of regen
carrying combustible impurities by burning off
the impurities with air, wherein the particles are
flowed downwardly thrdugh an inclined combus
tion zone while the air is ?owed upwardly through
the zone in direct contact with the particles
under combustion conditions, and wherein the
particles are continuously mechanically agitated
by continually rotating the said zone, the im
provement which comprises maintaining the
temperature of all the particles in said zone
within the temperature range between the mini
mum combustion temperature and the maximum
eration is possible, so much so that most spent
combustion temperature for said impurities that
filter clays will be found to contain enough com 60 does not --cause substantial heat damage to said
bustibles for their own regeneration without
particles, said temperature range being main
burning added fuel. A particular advantage of
tained by circulating a liquid heat exchange
this invention is that a considerable increase in
medium through the interior of said rotating zone
capacity over the usual rotary kiln may be at
in close indirect heat exchange relationship with
tained. In fact, it appears that with some ma
all the particles in said zone while maintaining
terials, much better operation may be attained
the temperature of said heat exchange medium
with throughput rates leading to what would nor
substantially within said temperature range
mally be considered a “?ooded” condition.
whereby heat immediately may be added to or
Many departures may be made from the con
extracted from said particles as becomes neces
struction shown diagrammatically herein without 70 sary during operation.
'
departing from the spirit of our invention. For
3. The method of claim 2, wherein the spent ’
example, the chamber 2| may be formed as an
' extension of the shell 4 instead of separately
absorbent particles being regenerated are spent
petroleum percolation clays, the liquid heat ex
change medium is maintained at a temperature
used, with the surge tank inside or outside of 75 around 850 to 900° F. and the temperature of
as shown. Other arrangements of tubing may be
5
2,286,654
‘900° FQ and the temperature of all the particles
all the particles in the rotating zone is main
in the rotating zone is maintained between said
tained between said minimum combustion: tem
minimum combustion temperature and about
perature and about 1200° F.
1200° F, ‘
4. The method of claim 2 wherein the spent
THOMAS P. SIMPSON.
5
adsorbent particles are spent adsorbent contact
VLADIMIR A. KALICHEVSKY.
mass particles derived from a petroleum conver
sion operation, the liquid heat exchangemedium
is maintained at a temperature around 850° to
JOHN W. PAYNE.