U.S. patent application number 14/479161 was filed with the patent office on 2016-03-10 for catalyst regenerators and methods for regenerating catalysts.
The applicant listed for this patent is UOP LLC. Invention is credited to Lev Davydov, Mohammad Reza Mostofi-Ashtiani, Paolo Palmas.
Application Number | 20160067701 14/479161 |
Document ID | / |
Family ID | 55314499 |
Filed Date | 2016-03-10 |
United States Patent
Application |
20160067701 |
Kind Code |
A1 |
Davydov; Lev ; et
al. |
March 10, 2016 |
CATALYST REGENERATORS AND METHODS FOR REGENERATING CATALYSTS
Abstract
Catalyst regenerators and methods of their use are provided. A
catalyst regenerator includes a combustion chamber with a
combustion chamber diameter and a combustion chamber bottom. A
mixing chamber is fluidly coupled to the combustion chamber at the
combustion chamber bottom, where the mixing chamber has an exterior
wall and a mixing chamber diameter less than the combustion chamber
diameter. A first and second catalyst inlet are fluidly coupled to
the mixing chamber, and a mixing cylinder is within the mixing
chamber. The mixing cylinder and the exterior wall define an
annular space there-between, and the mixing cylinder includes a
cylinder opening.
Inventors: |
Davydov; Lev; (Northbrook,
IL) ; Mostofi-Ashtiani; Mohammad Reza; (Naperville,
IL) ; Palmas; Paolo; (Des Plaines, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UOP LLC |
Des Plaines |
IL |
US |
|
|
Family ID: |
55314499 |
Appl. No.: |
14/479161 |
Filed: |
September 5, 2014 |
Current U.S.
Class: |
502/38 ;
422/144 |
Current CPC
Class: |
B01J 8/0055 20130101;
B01J 2208/00929 20130101; B01J 2208/0084 20130101; B01J 2208/00893
20130101; C10G 11/182 20130101; B01J 38/12 20130101; B01J 8/0025
20130101; B01J 8/1872 20130101; B01J 2208/00849 20130101; B01J
8/1863 20130101; B01J 8/1818 20130101; B01J 2208/00858 20130101;
B01J 2208/00991 20130101; B01J 8/005 20130101; B01J 8/24 20130101;
B01J 2208/00902 20130101; B01J 8/1881 20130101; B01J 2208/00761
20130101; B01J 8/1827 20130101; B01J 8/26 20130101; B01J 2208/00938
20130101; B01J 8/003 20130101; B01J 2208/00752 20130101 |
International
Class: |
B01J 38/12 20060101
B01J038/12; B01J 8/24 20060101 B01J008/24; B01J 8/18 20060101
B01J008/18; B01J 8/00 20060101 B01J008/00 |
Claims
1. A catalyst regenerator comprising: a combustion chamber having a
combustion chamber diameter and a combustion chamber bottom; a
mixing chamber fluidly coupled to the combustion chamber at the
combustion chamber bottom, wherein the mixing chamber has an
exterior wall and a mixing chamber diameter less than the
combustion chamber diameter; a first catalyst inlet fluidly coupled
to the mixing chamber; a second catalyst inlet fluidly coupled to
the mixing chamber; and a mixing cylinder within the mixing
chamber, wherein the mixing cylinder and the exterior wall define
an annular space there-between, and wherein the mixing cylinder
comprises a cylinder opening.
2. The catalyst regenerator of claim 1 wherein the cylinder opening
extends from below a lower most portion of the first catalyst inlet
to above an upper most portion of the first catalyst inlet.
3. The catalyst regenerator of claim 1 wherein the mixing cylinder
comprises a cylinder top that is closed, and wherein the cylinder
opening terminates below the cylinder top.
4. The catalyst regenerator of claim 1 wherein the mixing cylinder
comprises a cylinder wall section, and wherein the cylinder wall
section is positioned facing the first catalyst inlet and the
second catalyst inlet.
5. The catalyst regenerator of claim 1 wherein the cylinder opening
faces one of the first catalyst inlet or the second catalyst
inlet.
6. The catalyst regenerator of claim 1 wherein the mixing chamber
comprises a frustoconical section, wherein the mixing cylinder
comprises a closed cylinder top, and wherein the closed cylinder
top is within the frustoconical section.
7. The catalyst regenerator of claim 1 further comprising: a swirl
arm coupled to the mixing cylinder, wherein the swirl arm defines
an arcuate path from an interior of the mixing cylinder to the
annular space.
8. The catalyst regenerator of claim 1 further comprising: a mixing
gas distributor positioned within the mixing chamber exterior to
the mixing cylinder.
9. The catalyst regenerator of claim 1 further comprising: a
catalyst separator fluidly coupled to the combustion chamber; a
riser coupled to the catalyst separator; and wherein one of the
first or second catalyst inlets is fluidly coupled to the catalyst
separator, and the other of the first or second catalyst inlet is
fluidly coupled to the riser.
10. The catalyst regenerator of claim 1 further comprising: a third
catalyst inlet fluidly coupled to the mixing chamber.
11. The catalyst regenerator of claim 1 further comprising: a
helical mixing vane positioned within the mixing cylinder, wherein
the cylinder opening is at a bottom of the mixing cylinder, wherein
the cylinder opening is positioned above a mixing chamber bottom,
and wherein the mixing chamber is fluidly coupled to the combustion
chamber through the mixing cylinder; and a mixing gas distributor
within the mixing chamber, wherein the mixing gas distributor is
positioned within the mixing chamber below the mixing cylinder.
12. A catalyst regenerator comprising: a combustion chamber having
a combustion chamber diameter and a combustion chamber bottom; a
mixing chamber fluidly coupled to the combustion chamber at the
combustion chamber bottom, wherein the mixing chamber comprises an
exterior wall; a first catalyst inlet fluidly coupled to the mixing
chamber; an upspout fluidly coupled to the mixing chamber, wherein
the upspout includes an upspout wall extending into the mixing
chamber from a mixing chamber bottom, wherein the upspout wall and
the exterior wall define an annular space there-between; and a
second catalyst inlet fluidly coupled to the upspout.
13. The catalyst regenerator of claim 12 further comprising: a
fluidizing gas inlet positioned within the upspout; and a mixing
gas distributor positioned within the mixing chamber.
14. The catalyst regenerator of claim 12 wherein the upspout wall
has a frustoconical shape within the mixing chamber.
15. The catalyst regenerator of claim 12 wherein the mixing chamber
comprises a frustoconical section.
16. The catalyst regenerator of claim 12 further comprising helical
mixing vanes within the annular space, wherein the mixing vanes
extend from the exterior wall to the upspout.
17. The catalyst regenerator of claim 12 wherein the upspout wall
defines an upspout gap, the catalyst regenerator further
comprising: an upspout baffle extending between the exterior wall
and the upspout wall at an elevation above the upspout gap, wherein
the upspout baffle extends across the entire annular space such
that the first catalyst inlet is fluidly coupled to the combustion
chamber through the upspout and the upspout gap.
18. The catalyst regenerator of claim 12 further comprising: a
catalyst separator fluidly coupled to the combustion chamber; a
riser coupled to the catalyst separator; and wherein one of the
first or second catalyst inlets is fluidly coupled to the catalyst
separator, and the other of the first or second catalyst inlets is
fluidly coupled to the riser.
19. The catalyst regenerator of claim 12 further comprising: a
third catalyst inlet fluidly coupled to one of the mixing chamber
or the upspout.
20. A method of regenerating catalyst, the method comprising the
steps of: adding a spent catalyst to a mixing chamber, wherein the
mixing chamber is positioned below a combustion chamber, and
wherein the mixing chamber is in fluid communication with the
combustion chamber; adding a recovered catalyst to the mixing
chamber; mixing the spent catalyst and the recovered catalyst in a
mixing cylinder positioned within the mixing chamber; and
discharging the mixed spent catalyst and recovered catalyst from
the mixing chamber into the combustion chamber.
Description
TECHNICAL FIELD
[0001] The present disclosure generally relates to catalyst
regenerators and methods for regenerating catalysts using the same,
and more particularly relates to catalyst regenerators for fluid
catalytic cracking processes and methods for regenerating catalysts
using the same.
BACKGROUND
[0002] Fluid catalytic cracking (FCC) is primarily used to convert
high boiling, high molecular weight hydrocarbons into lower
boiling, lower molecular weight compounds. The lower molecular
weight compounds include gasoline, olefinic compounds, liquid
petroleum gas (LPG), diesel fuel, etc. An FCC unit typically uses a
catalyst that is repeatedly deactivated and regenerated in a riser
and a catalyst regenerator. Air is used to combust (burn off) coke
from the deactivated catalyst in the regeneration process, and
produces combustion gases such as carbon dioxide and water. Many
FCC units use the energy generated from burning the coke from the
catalyst to drive the endothermic reaction in the riser.
[0003] In a typical FCC units, a hydrocarbon feed stream is
contacted with the catalyst at reaction conditions in the riser,
and a layer of coke is deposited on the catalyst as the
hydrocarbons are cracked into smaller molecules. The deposited coke
shields the deactivated catalyst (often referred to as spent
catalyst), and the coke is oxidized in the catalyst regenerator so
the catalyst can be used again. In many FCC units, the catalyst
feed to the catalyst regenerator includes some spent catalyst from
the riser combined with some recovered catalyst that has passed
through the catalyst regenerator. The spent catalyst produces more
heat and combustion gases than the recovered catalyst because it
has more coke, so the recovered catalyst is combined with the spent
catalyst to better control the temperature in the catalyst
regenerator. The spent catalyst and the recovered catalyst are
typically combined near the bottom of a combustion chamber of the
catalyst regenerator, and the two different catalyst streams
normally do not mix well during the prescribed residence time. When
the two streams of catalyst are fed into the chamber, they tend to
rise straight up or otherwise move side by side without mixing so
the spent catalyst distribution in the combustor remains uneven.
The side of the combustor that has the spent catalyst tends to
operate hotter than the side with the recovered catalyst, as well
as producing more combustion gases. The uneven coke loading results
in nonuniform combustion, although most combustors are designed for
consistent operating conditions. The uneven heat and gas flow rates
in the combustor can result in some carbon monoxide or other
combustible gas rising into a catalyst separator of the catalyst
regenerator, where it can further oxidize and produce undesired
heat.
[0004] Accordingly, it is desirable to provide catalyst
regenerators and methods for regenerating catalyst that mix spent
catalyst with recovered catalyst before the mixed catalyst is
introduced into the combustor. In addition, it is desirable to
provide catalyst regenerators and methods for regenerating
catalysts that reduce combustible gases in the catalyst separator
of the catalyst regenerator. Furthermore, other desirable features
and characteristics of the present embodiment will become apparent
from the subsequent detailed description and the appended claims,
taken in conjunction with the accompanying drawing and this
background.
BRIEF SUMMARY
[0005] Catalyst regenerators and methods of using the same are
provided. A catalyst regenerator includes a combustion chamber with
a combustion chamber diameter and a combustion chamber bottom. A
mixing chamber is fluidly coupled to the combustion chamber at the
combustion chamber bottom, where the mixing chamber has an exterior
wall and a mixing chamber diameter less than the combustion chamber
diameter. A first and second catalyst inlet are fluidly coupled to
the mixing chamber, and a mixing cylinder is within the mixing
chamber. The mixing cylinder and the exterior wall define an
annular space there-between, and the mixing cylinder includes a
cylinder opening.
[0006] In another embodiment, a catalyst regenerator includes a
combustion chamber with a combustion chamber diameter and a
combustion chamber bottom. A mixing chamber is fluidly coupled to
the combustion chamber at the combustion chamber bottom, where the
mixing chamber includes an exterior wall. A first catalyst inlet is
fluidly coupled to the mixing chamber. An upspout is fluidly
coupled to the mixing chamber, where the upspout includes an
upspout wall extending into the mixing chamber from a mixing
chamber bottom. The upspout wall and the exterior wall define an
annular space there-between. A second catalyst inlet if fluidly
coupled to the upspout.
[0007] A method of regenerating catalyst is also provided. The
method includes adding a spent catalyst to a mixing chamber, where
the mixing chamber is positioned below a combustion chamber and
where the mixing chamber is in fluid communication with the
combustion chamber. A recovered catalyst is added to the mixing
chamber, and the spent catalyst and the recovered catalyst are
mixed in a mixing cylinder positioned within the combustion
chamber. The mixed spent and recovered catalysts are discharged
from the mixing chamber into the combustion chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Various embodiments will hereinafter be described in
conjunction with the following drawing figures, wherein like
numerals denote like elements, and wherein:
[0009] FIG. 1 is a cross-sectional view of an exemplary embodiment
of a fluid catalytic cracking unit;
[0010] FIG. 2 is a plane sectional view of an exemplary embodiment
of a mixing chamber for a fluid catalytic cracking unit, where FIG.
2 is taken along plane 2-2 from FIG. 1;
[0011] FIGS. 3, 5, 7, 9, 10, and 12 are side sectional views of
various exemplary embodiments of a mixing chamber for a fluid
catalytic cracking unit;
[0012] FIGS. 4, 6, 8A, 8B, 8C and 11 are plane sectional views of
various exemplary embodiments of a mixing chamber for a fluid
catalytic cracking unit, where FIG. 4 is taken along plane 4-4 from
FIG. 3, FIG. 6 is taken along plane 6-6 from FIG. 5, FIGS. 8A-8C
are taken along plane 8-8 from FIG. 7, and FIG. 11 is taken along
plane 11-11 from FIG. 10.
DETAILED DESCRIPTION
[0013] The following detailed description is merely exemplary in
nature and is not intended to limit the application or uses of the
embodiment described. Furthermore, there is no intention to be
bound by any theory presented in the preceding technical field,
background, brief summary, or the following detailed
description.
[0014] Catalyst regenerators and methods for regenerating catalysts
using the same are provided herein. Deactivated (spent) catalyst is
transferred from a riser to a catalyst regenerator in an FCC unit,
where the coke on the catalyst is combusted. Additional catalyst
from the catalyst regenerator (recovered catalyst) is combined with
the spent catalyst, where the coke has been removed from the
recovered catalyst by combustion. The spent catalyst and the
recovered catalyst are combined and mixed in a mixing chamber
before being introduced into a combustion chamber of the catalyst
regenerator for combustion. Recovered catalyst is added to the
spent catalyst to better control the temperature in the catalyst
regenerator. The mixing chamber includes a mixing cylinder or an
upspout configured to mix the two streams of catalyst, so the spent
and activated catalyst are mixed together (instead of being just
combined) before being introduced into the combustion chamber.
Several embodiments of the mixing chamber are possible. Coke is
combusted more consistently and more completely when the spent and
recovered catalysts are mixed instead of just being combined,
because the oxidizer (in the form of oxygen) will not pass any
portion of the combustor without encountering the fuel which is
present uniformly throughout the combustor cross section in the
form of coke on the spent catalyst.
[0015] Reference is made to the exemplary embodiment illustrated in
FIG. 1. A fluid catalytic cracker 10 (FCC) includes a riser 12 and
a catalyst regenerator 30. A hydrocarbon feed 14 is added to the
riser 12 and combined with a recovered catalyst 32, where the
hydrocarbon feed 14 and recovered catalyst 32 is fluidized by a
riser fluidizing gas distributor 16. The hydrocarbon feed 14 and
the recovered catalyst 32 rise up the riser 12, where hydrocarbons
within the hydrocarbon feed 14 are cracked and at least a portion
of the reactive sites of the recovered catalyst 32 are covered and
deactivated by coke to produce spent catalyst 18. The spent
catalyst 18 is separated from the cracked hydrocarbons in a riser
cyclone 20, where the spent catalyst 18 is collected and the
cracked hydrocarbons are removed from the riser 12 and separated in
various fractions, such as by distillation (not illustrated). Solid
and gaseous separators other than cyclones can be used in place of
the riser cyclone 20 in alternate embodiments. Some of the spent
catalyst 18 may optionally be combined with the recovered catalyst
32 at a base of the riser 12 for the cracking reaction. In an
exemplary embodiment, the ratio of recovered catalyst 32 to spent
catalyst 18 is from about 0.5 to about 3.
[0016] The spent catalyst 18 and the recovered catalyst 32 are any
of a variety of catalysts suitable for an FCC unit, as understood
by those skilled in the art. Suitable catalysts for use herein
include high activity crystalline alumina silicate and/or zeolite,
which are dispersed in a porous inorganic carrier material such as
silica, aluminum, zirconium, or clay. An exemplary embodiment of a
catalyst includes crystalline zeolite as the primary active
component, a matrix, a binder, and a filler. The zeolite ranges
from about 10 to about 50 weight percent of the catalyst, and is a
silica and alumina tetrahedral with a lattice structure that limits
the size range of hydrocarbon molecules that can enter the lattice.
The matrix component includes amorphous alumina, and the binder and
filler provide physical strength and integrity. Silica sol or
alumina sol are used as the binder and kaolin clay is used as the
filler. Standard reaction conditions for fluid catalytic cracking
are used in the riser 12, as understood by those skilled in the
art.
[0017] Spent catalyst 18 is transferred to the catalyst regenerator
30 to combust the coke and regenerate the spent catalyst 18 into
recovered catalyst 32. The catalyst regenerator 30 includes a
combustion chamber 34 and a catalyst separator 36 where the
recovered catalyst 32 is separated from flue gas created in the
combustion chamber 34. An oxygen supply gas is coupled to the
combustion chamber 34 and carries the spent catalyst 18 through the
combustion chamber 34 into the catalyst separator 36. The coke is
burned off the spent catalyst 18 by contact with the oxygen supply
gas at regeneration conditions. In an exemplary embodiment, air is
used as the oxygen supply gas, because air is readily available and
provides sufficient O.sub.2 for combustion, but other gases with a
sufficient concentration of O.sub.2 could also be used, such as
purified O.sub.2. If air is used as the oxygen supply gas, about 10
to about 15 kilograms (kg) of air is required per kg of coke burned
off of the spent catalyst 18. Exemplary regeneration conditions
include a temperature from about 500.degree. C. to about
900.degree. C. (900.degree. F. to 1,700.degree. F.) and a pressure
of about 150 kPa to about 450 kPa (20 PSIG to 70 PSIG) in the
combustion chamber 34. The superficial velocity of the oxygen
supply gas is typically less than about 2 meters per second (6 feet
per second), and the density within the combustion chamber 34 is
typically about 80 to about 400 kilograms per cubic meter (about
5-25 lbs. per cubic foot). However, the catalyst regenerator 30 may
be designed and sized based on the expected duty, so the catalyst
regenerator 30 may be larger or smaller than as described
above.
[0018] The catalyst separator 36 may include one or more
regenerator cyclones 38 or other solid/gaseous separator devices to
separate the recovered catalyst 32 from the flue gas. The recovered
catalyst 32 collects within the catalyst separator 36, and from
there is transferred to the riser 12 for re-use in cracking
hydrocarbons. The combustion chamber 34 has a combustion chamber
diameter indicated by the double headed arrow 40, where the
combustion chamber diameter 40 is measured at the widest point of
the combustion chamber 34. A combustion chamber bottom 42 is along
the lowest portion of the combustion chamber 34, such as the
portion below the essentially vertical walls of the combustion
chamber 42.
[0019] In an exemplary embodiment, a mixing chamber 150 is fluidly
coupled to the combustion chamber 34 at the combustion chamber
bottom 42, as illustrated in FIG. 2 with continuing reference to
FIG. 1, where FIG. 2 is taken along plane 2-2 from FIG. 1. The
mixed catalyst, including the spent catalyst 18 and the recovered
catalyst 32, is discharged from the mixing chamber 150 into the
combustion chamber 34. The mixing chamber 150 may be centered along
the combustion chamber bottom 42, so the combustion chamber 34 and
the mixing chamber 150 have a common longitudinal axis (not
illustrated). There are several different embodiments of the mixing
chamber 150, and like elements are represented by the same two last
digits of the reference number, with the preceding digits varying
from one embodiment to the next. The various embodiments represent
options for mixing the spent catalyst 18 and the recovered catalyst
32 before the mixture is introduced into the combustion chamber 34,
and components of different embodiments may be combined for a new
embodiment not specifically illustrated or described herein.
[0020] The spent catalyst 18 and the recovered catalyst 32 are
separately added to the mixing chamber 150 and then mixed before
exiting the mixing chamber 150 and entering into the combustion
chamber 34. In alternate embodiments, the spent and recovered
catalyst 18, 32 are mixed in an upspout before entering the
combustion chamber 34 (described below). Mixed spent and recovered
catalyst 18, 32 is different than combined spent and recovered
catalyst 18, 32 because the mixed spent and recovered catalyst 18,
32 does not have a significant concentration gradient of coke from
one area to another, where coke is present on the spent catalyst 18
at about 1 to about 2.5 weight percent but the recovered catalyst
32 has essentially no coke. For example, when spent and recovered
catalyst 18, 32 are merely combined at a 50/50 ratio, any standard
sample of catalyst may be all spent catalyst 18, all recovered
catalyst 32, or any combination in between. Therefore, in a
combination of 50% spent catalyst 18 and 50% recovered catalyst 32,
the total weight of coke may vary from about 0 grams to about 2.5
grams in a 100 gram sample (0 grams if the combination is all
recovered catalyst 32, and 2.5 grams if the combination is all
spent catalyst 18.) The same analysis applies for ratios other than
50/50. The concentration gradient of coke for a combined catalyst
can vary significantly from the average coke concentration, where
the average coke concentration for the example described above is
1.25 grams of coke per 100 grams of sample.
[0021] For mixed catalyst (as compared to merely combined
catalyst), the total weight percent of coke for any one sample may
vary from the average coke concentration by about 10 weight percent
or less, or about 5 weight percent less, or about 3 weight percent
or less in various embodiments. Therefore, "mixed catalyst" is
defined as catalyst with an insignificant concentration gradient of
coke, where an insignificant concentration gradient of coke is such
that the weight percent of coke on any standard sample size (such
as one hundred grams of catalyst) varies from the average coke
concentration by about 10 percent or less, 5 percent or less, or 3
percent or less in various embodiments. To illustrate, for a 50/50
mixture of spent and recovered catalyst 18, 32 with 2.5 grams of
coke per 100 grams of spent catalyst 18, the average coke
concentration will be 1.25 grams of coke per 100 grams of sample
(1/2 spent catalyst 18 with 2.5 grams coke per 100 grams of spent
catalyst 18, and 1/2 recovered catalyst 32 with 0 grams coke per
100 grams of recovered catalyst 32). In an exemplary embodiment
with 5 weight percent variation or less, any sample of mixed
catalyst will have within 5 weight percent of 1.25 grams of coke
per 100 grams of sample, so any 100 gram sample will have from
about 1.1875 grams to about 1.3125 grams of coke.
[0022] In an exemplary embodiment, the mixing chamber 150 has a
mixing chamber diameter indicated by the double headed arrow 152,
where the mixing chamber diameter 152 is less than the combustion
chamber diameter 40. The mixing chamber 150 may be cylindrical in
some embodiments. A first catalyst inlet 154 is fluidly coupled to
the mixing chamber 150, and a second catalyst inlet 156 is also
fluidly coupled to the mixing chamber 150. The first catalyst inlet
154 discharges one of the spent catalyst 18 or the recovered
catalyst 32 through a first catalyst line 160 into the mixing
chamber 150, and the second catalyst inlet 156 discharges the other
through a second catalyst line 162. Valves 165 may be included in
the first and second catalyst lines 160, 162 (and any other
catalyst lines as described below) to control the rate of flow of
the catalyst to the mixing chamber 150. The first and second
catalyst inlets 154, 156 are fluidly coupled to the riser 12 or the
catalyst separator 36 of the catalyst regenerator 30 through the
first and second catalyst lines 160, 162 such that catalyst flows
through the first and second catalyst lines 160, 162 into the
mixing chamber 150. In some embodiments, the catalyst is fluidized
in the first and/or second catalyst lines 160, 162 to facilitate
catalyst flow. One or both of the first and second catalyst inlets
154, 156 may optionally be tangentially connected to the mixing
chamber 150 (tangential connection not illustrated) to impart an
angular motion to the catalyst to promote mixing. Additionally,
ramps (not illustrated) may be installed at the first and/or second
catalyst inlet 154, 156 to further promote mixing. The ramps may
direct the flowing catalyst upward, downward, or to one side or the
other in various embodiments. A mixing gas distributor 166
fluidizes the catalyst within the mixing chamber 150 and carries
the catalyst from the mixing chamber 150 into the combustion
chamber 34. The gas discharged from the mixing gas distributor 166
may be air or other gases in various embodiments.
[0023] A mixing cylinder 168 may be positioned within the mixing
chamber 150 in some embodiments, where the mixing cylinder 168 and
an exterior wall 169 of the mixing chamber 150 define an annular
space 170 there-between. The first and second catalyst inlets 154,
156 open into the annular space 170 in some embodiments, where the
catalyst inlets 154, 156 are positioned below the section line in
FIGS. 2, 4, 6, 8A, 8B, 8C, and 11 such that they are not visible,
but are indicated with reference numbers to illustrate the
location. The mixing cylinder 168 may be radially centered within
the mixing chamber 150, and the mixing cylinder 168 may be
cylindrical in shape. In other words, the mixing cylinder 168 may
have a central longitudinal axis (not illustrated) aligned with a
central longitudinal axis (not illustrated) of the mixing chamber
150. A cylinder wall section 176 of the mixing cylinder 168 may be
vertical in some embodiments. The mixing gas distributor 166 is
positioned within the annular space 170 in some embodiments, where
the annular space 170 is a portion of the mixing chamber 150.
[0024] In an exemplary embodiment, one or more cylinder openings
172 are defined in the cylinder wall section 176 of the mixing
cylinder 168. The cylinder opening 172 serves as an entrance into
an interior 174 of the mixing cylinder 168, and the cylinder
opening 172 can also serve as an exit from the interior 174. In an
exemplary embodiment, one or more of the cylinder openings 172 has
an elongated configuration that is spaced from the near the top of
the mixing cylinder 168 (referred to herein as a cylinder top 178,)
such as from within about 1 to about 10 centimeters from the
cylinder top 178. In alternate embodiments (not illustrated), one
or more of the illustrated cylinder openings 172 (in this
embodiment and in the embodiments described below) may include two
or more openings, with one opening above the other such that the
openings are radially aligned on the mixing cylinder 168. Without
wishing to be bound by theory, it is believed that the spent and
recovered catalyst 18, 32 from the first and second catalyst lines
160, 162 may enter the interior 174, mix, and then exit the
interior 174 through the cylinder opening 172 as a mixed catalyst
ready for the combustion chamber 34. The mixed catalyst produces a
more consistent temperature in the combustion chamber 34 than a
mere combination of the spent catalyst 18 and the recovered
catalyst 32 that has not been mixed before entering the combustion
chamber 34, and also produces less combustible gas exiting the
combustion chamber 34 and entering the catalyst separator 36.
[0025] The interior 174 is in fluid communication with the annular
space 170 through the cylinder opening 172. In an exemplary
embodiment, the upper most portion of the cylinder opening 172 is
above the lower most portions of the first and second catalyst
inlets 154, 156, and is optionally above the upper most portions of
the first and second catalyst inlets 154, 156 as well. The upper
most portion of the first catalyst inlet 154 is the highest
elevation of the intersection of the first catalyst inlet 154 with
the mixing chamber 150, the lowest most portion is the lowest
elevation of the intersection of the first catalyst inlet 154 with
the mixing chamber 150, and the same applies to other inlets. In
embodiments with the upper most portion of the cylinder opening 172
above the upper most portion of the first and/or second catalyst
inlets 154, 156, the catalyst from the first and/or second catalyst
inlets 154, 156 can flow upward with the fluidizing gas from the
mixing gas distributor 166 through the cylinder opening 172 and
into the interior 174 of the mixing cylinder 168.
[0026] Reference is made to FIG. 2 with continuing reference to
FIG. 1, where FIG. 2 is taken along plane 2-2 from FIG. 1. FIG. 2
illustrates three cylinder wall sections 176 of the mixing cylinder
168 that have an arcuate cross section, where FIGS. 1 and 2
illustrate the same embodiment. One of the arcuate cylinder wall
sections 176 faces the first catalyst inlet 154 such that catalyst
exiting the first catalyst inlet 154 enters the annular space 170
between the first catalyst inlet 154 and one of the arcuate
cylinder wall sections 176 of the mixing cylinder 168. Another of
the arcuate cylinder wall sections 176 faces the other of the
second catalyst inlet 156 such that catalyst enters the annular
space 170 between the other of the second catalyst inlet 156 and
the other arcuate cylinder wall section 176. The arcuate cylinder
wall sections 176 facing the first and second catalyst inlets 154,
156 may be narrower or wider than the openings of the first and/or
second catalyst inlets 154, 156. The third arcuate cylinder wall
section 176 is optional. In an exemplary embodiment, one of the
three cylinder openings 172 has a larger width than the other two
cylinder openings 172, and the two smaller cylinder openings 172
have about the same width, such as within about 1 centimeter of
each other.
[0027] Without wishing to be by bound by theory, it is believed
that in operation the catalyst from the first catalyst inlet 154
enters the annular space 170 and encounters an arcuate cylinder
wall section 176. The catalyst passes along the cylinder wall
section 176 and enters the interior 174 of the mixing cylinder 168
through one of the cylinder openings 172. The catalyst from the
second catalyst inlet 156 follows a similar flow pattern and enters
the interior 174 of the mixing cylinder 168. The catalyst from the
first and second catalyst inlets 154, 156 then mix in the interior
174 and exit the interior 174 back into the annular space 170 and
then into the combustion chamber 34. The spent and recovered
catalyst 18, 32 also commingle and mix in the annular space 170 and
other areas within the mixing chamber 150 before entering the
combustion chamber 34.
[0028] The mixing cylinder 168 may have a cylinder top 178 that is
closed, so catalyst from the interior 174 must pass laterally
through one of the cylinder openings 172 to enter the annular space
170 or the upper portions of the mixing chamber 150. The cylinder
top 178 may have a hemispherical shape, and the cylinder top 178
may be sized such that the cross sectional area of the annular
space 170 at the elevation of the cylinder top 178 is about half
the cross sectional area of the mixing chamber 150 (including the
area of the mixing cylinder 168) at the elevation of the cylinder
top 178. For example, the cross sectional area of the annular space
170 may be about 40 to about 60 percent of the cross sectional area
of the mixing chamber 150 at the elevation of the cylinder top 178.
Consequently, the superficial velocity within the mixing chamber
150 at the elevation of the cylinder top 178 is about twice the
superficial velocity at other locations within the mixing chamber
150. The changing superficial velocity may promote mixing of the
catalyst. In some embodiments, at least one of the cylinder
openings 172 is spaced from the cylinder top 178 by about one
quarter of a diameter of the mixing chamber 150, such as about 20
to about 30 percent of the diameter of the mixing chamber 150.
[0029] In an exemplary embodiment, the mixing chamber 150 may be
made of stainless steel, such as 300 Series stainless steel lined
with refractory. The edges of the cylinder openings 172 may be
designed to resist erosion, such as with thicker edges than the
rest of the cylinder wall sections 176. The edges of the cylinder
openings 172 may also be cured to deflect eroding catalyst
particles, and a weld beam can be formed at the edges to further
resist erosion. The mixing chamber 150 and mixing cylinder 168 may
be made of or coated with a ceramic or other material that helps
resist erosion.
[0030] FIGS. 3 and 4 illustrate other embodiments of the mixing
chamber 250, with continuing reference to FIG. 1, where the
components of the riser 12 and the catalyst regenerator 30 not
illustrated in FIGS. 3 and 4 (and the remaining FIGS.) are the same
as in FIG. 1. FIG. 3 illustrates an embodiment with a first and
second catalyst inlet 254, 256, and FIG. 4 illustrates an
embodiment with a first, second, and third catalyst inlet 254, 256,
258 and associated first, second, and third catalyst lines 260,
262, 264. FIG. 4 is taken along plane 4-4 from FIG. 3, with the
exception that FIG. 4 is an alternate embodiment with three inlets.
Other embodiments discussed herein may include two, three, or more
catalyst inlets and associated catalyst lines, and the third and
additional catalyst lines may convey either spent catalyst 18 or
recovered catalyst 32 in various embodiments. Additional catalyst
inlets may convey catalyst from various sources, such as recovered
catalyst 32 that has been cooled in a catalyst cooler (not
illustrated), spent catalyst 18 from a second riser (not
illustrated) coupled to the catalyst regenerator 30, or other
catalyst sources.
[0031] In an exemplary embodiment, the mixing chamber 250 has a
frustoconical section 279 where the cross sectional area of the
mixing chamber 250 decreases within the frustoconical section 279
as the elevation increases. The frustoconical section 279 may be
near the top of the mixing chamber 250. The frustoconical section
279 increases the superficial velocity, and may promote mixing. The
cylinder top 278 may be located within the frustoconical section
279 in some embodiments, but the cylinder top 278 may be below the
frustoconical section 279 in alternate embodiments. In the
illustrated embodiment, the mixing cylinder 268 is radially
centered in the mixing chamber 250, and the annular space 270 is
defined between the mixing cylinder 268 and the exterior wall 269
of the mixing chamber 250. The first, second and third catalyst
lines 260, 262, 264 are in fluid communication with the annular
space 270, and the first, second and third catalyst lines 260, 262,
264 are also in fluid communication with the interior 274 of the
mixing cylinder 268 through the cylinder opening 272, similar to as
described above. The cylinder opening 272 is aligned with one of
the first, second, or third catalyst inlets 154, 156, 158, so
catalyst from the selected inlet (the first catalyst inlet 254 for
illustration purposes) enters the annular space 270 and flows
directly into the interior 272 of the mixing cylinder 268 through
the cylinder opening 272. A portion of the catalyst from the first
catalyst inlet 254 and the catalyst from the other catalyst inlets
256, 258 may travel along the cylinder wall section 276 and pass
into the interior 272 indirectly. A second cylinder opening 272
(not illustrated) may be aligned with another inlet, such as the
second or third catalyst inlet 256, 258 in alternate embodiments.
The different streams of catalyst may mix when entering and exiting
the interior 274, and when moving within the mixing chamber 150 as
described above.
[0032] One or more swirl arms 280 may be coupled to the mixing
cylinder 268 in some embodiments. The swirl arms 280 are located in
a vertical portion of the cylinder wall section 276 and provide an
exit from the interior 274. The swirl arms 280 define a path from
the interior 274 to the annular space 270 of the mixing chamber 250
outside of the mixing cylinder 268, and the path is configured to
create a swirling motion for catalyst, gases, or fluids passing
from the interior 274 through the swirl arms 280. The
swirl-imparting configuration may be an arcuate tube, and the cross
section of the arcuate tubes may be rectangular, round or other
shapes in various embodiments. The exit of the swirl arm 280 may be
tangential or nearly tangential to the round cross sectional shape
of the mixing cylinder 268, and the exit may point horizontally or
at other angles to promote the swirling action. In embodiments with
more than one swirl arm 280, the swirl arms 280 may be curved in
the same direction so each swirl arm 280 imparts a swirling motion
in the same direction. The swirl arm(s) 280 may have a lower most
portion that is at an elevation above the lower most portion of the
cylinder opening 272, and the swirl arm's lower most portion may
also be at an elevation above the upper most portion of the
cylinder opening 272. As such, at least some of the catalyst may
enter the interior 274 through the cylinder opening 272 and exit
the interior 274 through the swirl arms 280 as the catalyst travels
upwards within the mixing chamber 150. Fluidizing gas from the
mixing gas distributor 266 propels the catalyst into the interior
274 and upward through the swirl arms 280. The swirling motion
imparted by the swirl arms 280 may further promote catalyst
mixing.
[0033] Yet another embodiment is illustrated in FIGS. 5 and 6, with
continuing reference to FIG. 1. In this embodiment, the bottom of
the mixing cylinder 368 is suspended above a mixing chamber bottom
386. The mixing cylinder 368 is connected to the top of the mixing
chamber 350, and there are one or more mixing vanes 382 in the
interior 374 of the mixing cylinder 368. A cylinder wall section
376 of the lower portion of the mixing cylinder 368 in FIG. 5 is
removed to illustrate the mixing vanes 382, and the cylinder wall
section 376 of the upper portion of the mixing cylinder 368 blocks
the view of the mixing vanes 382. FIG. 6 is taken along plane 6-6
from FIG. 5.
[0034] The catalysts from the first and second catalyst lines 360,
362 combine in the mixing chamber 350 and are lifted by fluidizing
gas from the mixing gas distributor 366 into the cylinder opening
372 at the bottom of the mixing cylinder 368. The cylinder opening
372 may be at an elevation above a bottom portion of the first
and/or second catalyst inlets 354, 356, and below an elevation of a
top portion of the first and/or second catalyst inlets 354, 356.
The cylinder top 378 is open in the embodiment illustrated in FIGS.
5 and 6, and all the catalyst exits the mixing cylinder 368 through
the cylinder top 378. The spent and recovered catalyst 18, 32
passes from the mixing chamber 350 into the mixing cylinder 368 and
then flows upward into the combustion chamber 34, so the mixing
chamber 350 is fluidly coupled to the combustion chamber 34 through
the mixing cylinder 368.
[0035] The catalyst is swirled by one or more mixing vanes 382 as
the catalyst travels through the mixing cylinder 368. The mixing
vanes 382 inside the mixing cylinder 368 extend from the cylinder
wall section 376 into the interior 374 with a curved shape, and the
mixing vane 382 may have a helical shape as it extends upward
within the mixing cylinder 368 to impart angular momentum and
create a swirling motion. The mixing vane 382 may be located
anywhere within the mixing cylinder 368, and may extend for all or
any portion of the length of the mixing cylinder 368. The
superficial velocity increases as the fluidized catalyst enters the
smaller area of the mixing cylinder 368 relative to the larger area
of mixing chamber 350, and the swirling motion and increased
superficial velocity promote mixing. A vertical baffle (not
illustrated) may be positioned within the annular space 370 to help
minimize commingling of the spent and recovered catalyst 18, 32 in
the stagnant annular space 370. Alternatively, a horizontal baffle
(not illustrated) may prevent catalyst from entering the stagnant
annular space 370.
[0036] Reference is made to the exemplary embodiment illustrated in
FIGS. 7 and 8A-8C, with continuing reference to FIG. 1. FIGS. 8A-8C
are taken along plane 8-8 of FIG. 7 and illustrate various
embodiments. In the embodiment illustrated in FIGS. 7 and 8A-8C,
one of the first or second catalyst inlets 454, 456 (the first
catalyst inlet 454 for illustration purposes) opens into the mixing
chamber 450, and the other of the first or second catalyst inlets
454, 456 (the second catalyst inlet 456 for illustration purposes)
opens into an upspout 484. The upspout 484 extends into the mixing
chamber 450 from a mixing chamber bottom 486 such that the annular
space 470 is between an upspout wall 488 and the exterior wall 469
of the mixing chamber 450. The upspout 484 is radially centered
within the mixing chamber 450 in some embodiments. In the
illustrated embodiment, the upspout wall 488 defines an upspout gap
490 positioned in a vertical section of the upspout wall 488 below
a closed upspout top 492. The upspout gap 490 may be at an
elevation above a lower most portion of the first catalyst inlet
454, and it may also be at an elevation above an upper most portion
of the first catalyst inlet 454 so some of the catalyst from the
first catalyst inlet 454 travels upward to reach the upspout gap
490.
[0037] The catalyst from the second catalyst line 462 enters the
upspout 484 and is fluidized by gas coming from a fluidizing gas
inlet 494 positioned within the upspout 484 at an elevation below
the lower most portion of the second catalyst inlet 456. The
catalyst travels upward and exits the upspout 484 through the
upspout gap 490 into the annular space 470. The spent and recovered
catalyst 18, 32 are mixed in the annular space 470 and in the
frustoconical section 479 of the mixing chamber 450 before entering
the combustion chamber 34. The mixing gas distributor 466 is
positioned within the mixing chamber 450 in the annular space 470
below the lower most portion of the upspout gap 490 and the lower
most portion of the first catalyst inlet 454. The mixed catalyst is
fluidized and carried upward by gas from the mixing gas distributor
466, as described above. A third catalyst inlet and an associated
third catalyst line (not illustrated) may be fluidly coupled to one
of the mixing chamber 450 or the upspout 484, as described above,
where the third catalyst line may be configured to transport spent
catalyst 18 or recovered catalyst 32. Additional catalyst lines are
also possible, as described above.
[0038] FIG. 8A illustrates an embodiment where the upspout wall 488
defines the upspout gap 490 as a simple void area within the
upspout wall 488. FIG. 8B illustrates an embodiment where the
upspout gap 490 includes projections 491 to direct catalyst into
the annular space 470, where the projections 491 extend from into
the annular space 470 from opposite sides of the upspout gap 490.
FIG. 8C illustrates an embodiment where the upspout gap 490 is
configured to swirl the catalyst as it exits the upspout gap 490.
In FIG. 8C, the upspout gap 490 includes a swirl arm 480 coupled to
the upspout gap 490 so catalyst exiting through the upspout gap 490
flows through the swirl arm 480. The swirl arm 480 includes a tube
having an arcuate shape that bends as it extends into the annular
space 470. The tube of the swirl arm 480 may have an exit that is
radial to an upspout longitudinal axis (not illustrated) to promote
a swirling motion and promote mixing, similar to the swirl arms
described above.
[0039] Referring to FIG. 9 with continuing reference to FIG. 1, an
embodiment of the mixing chamber 550 with an upspout 584 is
illustrated. The upspout 584 includes a frustoconical upspout wall
588 within the mixing chamber 550 with an open upspout top 592. The
catalyst from the second catalyst line 562 is fluidized by the
fluidizing gas inlet 594 in the upspout 584, and the catalyst from
the first catalyst line 560 is fluidized by the mixing gas
distributor 566 in the annular space 570 between the exterior wall
569 of the mixing chamber 550 and the upspout wall 588. The
exterior wall 569 of the mixing chamber 550 also includes a
frustoconical section 579 above the upper most portion of the first
catalyst inlet 554. The increasing superficial velocity produced by
the frustoconical sections promotes mixing.
[0040] Reference is made to FIGS. 10 and 11, with continuing
reference to FIG. 1, where FIG. 11 is taken along plane 11-11 from
FIG. 10. The embodiment of FIG. 10 illustrates the mixing chamber
650 with a section of the exterior wall 669 removed to show the
lower portions of mixing vanes 682, where the exterior wall 669
covers the upper portions of the mixing vanes 682, and the upper
most portion of the upspout 684 is shown with dashed lines because
it is hidden behind the mixing vanes 682. The second catalyst inlet
656 opens into the upspout 684, and catalyst from the second
catalyst line 662 is fluidized and carried upward by the fluidizing
gas inlet 694 positioned below a lower most portion of the second
catalyst inlet 656. The first catalyst inlet 654 opens into the
annular space 670 and is fluidized and carried upward by gases from
the mixing gas distributor 666. The upspout top 692 is open in the
illustrated embodiment, so catalyst freely flows upward out of the
upspout 684. Mixing vanes 682 extend from the exterior wall 669 of
the mixing chamber 650 to the upspout wall 688 to impart a swirling
motion beginning in the annular space 670. The mixing vanes 682 may
be helical to increase the swirling motion of the fluidized
catalyst. In some embodiments, the mixing vanes 682 extend above
the upspout top 692, but in other embodiments (not illustrated) the
mixing vanes 682 terminate at or below the upspout top 692. The
lower most portions of the mixing vanes 682 may be at an elevation
above the upper most portion of the first catalyst inlet 654.
[0041] FIG. 12 illustrates yet another embodiment with a mixing
chamber 750 and an upspout 784. The second catalyst inlet 756 opens
into the upspout 784, and the first catalyst inlet 754 opens into
the mixing chamber 750. The fluidizing gas inlet 794 and the mixing
gas distributor 766 are positioned within the upspout 784 and the
mixing chamber 750 below the lower most portion of the second
catalyst inlet 756 first catalyst inlet 754, respectively, as
described above. An upspout baffle 796 extends from the upspout
wall 788 to the exterior wall 769 of the mixing chamber 750 and
prevents catalyst from entering the stagnant section of the annular
space 770 above the upspout gap 790. The upspout baffle extends
across the entire annular space 770 to completely block the
stagnant section of the annular space 770. The upspout gap 790 is
at an elevation above the lower most portion of the first catalyst
inlet 754 and also at an elevation above the upper most portion of
the first catalyst inlet 754 in some embodiments. The upspout gap
790 is also at an elevation below the upspout baffle 796. Catalyst
from the first catalyst line 760 enters the annular space 770 of
the mixing chamber 750 and passes through the upspout gap 790 to
mix with the catalyst from the second catalyst line 762 in the
upspout 784. The mixed catalyst then flows through the upspout 784
into the combustion chamber 34. As such, the mixing chamber 750 is
fluidly coupled to the combustion chamber 34 through the upspout
gap 790 and the upspout 784.
[0042] While at least one exemplary embodiment has been presented
in the foregoing detailed description, it should be appreciated
that a vast number of variations exist. It should also be
appreciated that the exemplary embodiment or exemplary embodiments
are only examples, and are not intended to limit the scope,
applicability, or configuration of the application in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing one
or more embodiments, it being understood that various changes may
be made in the function and arrangement of elements described in an
exemplary embodiment without departing from the scope, as set forth
in the appended claims.
* * * * *