U.S. patent application number 15/222903 was filed with the patent office on 2016-11-17 for process for simultaneous cracking of lighter and heavier hydrocarbon feed and system for the same.
This patent application is currently assigned to INDIAN OIL CORPORATION LIMITED. The applicant listed for this patent is INDIAN OIL CORPORATION LIMITED. Invention is credited to Debasis BHATTACHARYYA, Satyen Kumar DAS, Reshmi MANNA, Santanam RAJAGOPAL, Tridib SARKAR, Saravanan SUBRAMANI.
Application Number | 20160333280 15/222903 |
Document ID | / |
Family ID | 44454673 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160333280 |
Kind Code |
A1 |
SUBRAMANI; Saravanan ; et
al. |
November 17, 2016 |
PROCESS FOR SIMULTANEOUS CRACKING OF LIGHTER AND HEAVIER
HYDROCARBON FEED AND SYSTEM FOR THE SAME
Abstract
The invention provides for a process and apparatus for
simultaneous conversion of lighter and heavier hydrocarbon
feedstocks into improved yields of light olefins in the range of C2
to C4, liquid aromatics in the range C6 to C8 mainly benzene,
toluene, xylene and ethyl benzene and other useful products
employing at least two different reactors operated in series with
respect to catalyst flow and parallel with respect to feed flow
under different regimes and process conditions with same catalyst
system.
Inventors: |
SUBRAMANI; Saravanan;
(Faridabad, IN) ; BHATTACHARYYA; Debasis;
(Faridabad, IN) ; MANNA; Reshmi; (Faridabad,
IN) ; DAS; Satyen Kumar; (Faridabad, IN) ;
SARKAR; Tridib; (Faridabad, IN) ; RAJAGOPAL;
Santanam; (Faridabad, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INDIAN OIL CORPORATION LIMITED |
Faridabad |
|
IN |
|
|
Assignee: |
INDIAN OIL CORPORATION
LIMITED
Faridabad
IN
|
Family ID: |
44454673 |
Appl. No.: |
15/222903 |
Filed: |
July 28, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13638460 |
Oct 1, 2012 |
9433912 |
|
|
PCT/IN2011/000223 |
Mar 30, 2011 |
|
|
|
15222903 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 11/182 20130101;
B01J 8/1863 20130101; C10G 2300/107 20130101; C10G 2300/703
20130101; C10G 2300/1074 20130101; C10G 2300/1077 20130101; B01J
35/0026 20130101; B01J 2208/00761 20130101; C10G 2300/4018
20130101; C10G 2300/708 20130101; C10G 2300/807 20130101; C10G
2300/301 20130101; B01J 8/0055 20130101; B01J 35/0006 20130101;
B01J 8/26 20130101; B01J 2208/00752 20130101; C10G 51/06 20130101;
C10G 2300/1044 20130101; B01J 8/28 20130101; B01J 35/023 20130101;
C10G 2400/02 20130101; C10G 2400/20 20130101; C10G 2400/28
20130101; C10G 2300/4093 20130101; B01J 29/088 20130101; C10G
2400/22 20130101; C10G 2300/104 20130101; C10G 2300/701 20130101;
C10G 11/185 20130101; C10G 2300/1059 20130101; B01J 35/08 20130101;
C10G 2400/30 20130101; C10G 2300/4025 20130101; B01J 21/04
20130101; B01J 2208/00902 20130101; B01J 2208/00911 20130101 |
International
Class: |
C10G 51/06 20060101
C10G051/06; B01J 29/08 20060101 B01J029/08; B01J 35/08 20060101
B01J035/08; B01J 35/00 20060101 B01J035/00; B01J 35/02 20060101
B01J035/02; B01J 8/26 20060101 B01J008/26; B01J 21/04 20060101
B01J021/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2010 |
IN |
793/DEL/2010 |
Claims
1. A FCC catalyst system for simultaneous cracking of lighter and
heavier hydrocarbon feedstocks in multiple reactors to produce
improved yields of light olefins and liquid aromatics and the like,
comprising Y-zeolite in rare earth ultra-stabilized form with
bottom cracking components consisting of peptized alumina, acidic
silica alumina or gamma alumina, pentasil shape selective zeolites
or a mixture thereof as the active components.
2. The catalyst system as claimed in claim 1, wherein the catalyst
comprises of solid micro-spherical acidic materials with average
particle size of 60-80 microns and apparent bulk density of 0.7 to
1.0 gm/cc.
3. The catalyst system as claimed in claim 1, wherein the active
catalyst components are supported on relatively inactive materials
such as silica/alumina or silica-alumina compounds, including
kaolinites or with active matrix components like pseudobomite
alumina.
4. A process for preparing a catalyst system for simultaneous
cracking of lighter and heavier hydrocarbon feedstocks in multiple
reactors to produce improved yields of light olefins and liquid
aromatics and the like, wherein Y-zeolite in rare earth
ultra-stabilized form and a bottom cracking component selected from
peptized alumina, acidic silica alumina or gamma alumina, pentasil
shape selective zeolites or a mixture thereof are mixed together or
separately bound, supported on relatively inactive materials and
spray-dried to get micro-spheres, washed, rare earth exchanged and
flash dried to produce the finished catalyst system.
5. The process as claimed in claim 4, wherein the active catalyst
components as finished micro-spheres in separate particles are
physically blended in the desired composition.
6. A multi-reactor fluidized bed catalytic cracking apparatus for
the production of light olefins and liquid aromatics and the like,
through simultaneous cracking of lighter and heavier hydrocarbon
feedstocks in separate reaction zones comprising at least a first
reaction zone in a first reactor, a second reaction zone in a
second reactor and a catalyst regenerator.
7. The apparatus as claimed in claim 6, wherein the first reactor
being connected at the bottom with a distributor inlet for entry of
preheated lighter hydrocarbon feed/recycled feed along with process
steam via a conduit, has an inlet for entry of hot regenerated
catalyst through a distributor via a slide valve from the catalyst
regenerator, a separation device for separation of coke laden
catalyst from the cracked products, a stripper means for stripping
coked catalyst from the cracked product vapor, an outlet for the
product vapor to reach to a main fractionator via a plenum chamber;
an outlet at the bottom for circulation of partially coked catalyst
to the bottom of the second reactor through a slide valve; an
outlet for removing coke laden spent catalyst to the regenerator;
the second reactor, preferably a riser, having an inlet for hot
fresh heavy feedstock with dispersion steam near the bottom through
a single or multiple feed nozzle, an inlet each for recycle feed
and dilution steam near the bottom at different elevations of the
riser and at the bottom for the regenerated catalyst through slide
valve stated above and for the lift/stabilization steam; a
termination device with separator for the separation of spent
catalyst and product vapor mixture, a stripper means for stripping
coke laden catalyst from the cracked hydrocarbons, an outlet for
the spent catalyst to the regenerator, an outlet for the product
vapor to the main fractionator via a plenum chamber; the catalyst
regenerator has an inlet for the source of coke laden spent
catalyst distributed through a distributor, an inlet at the bottom
for the source of air or an oxygen containing gas, an outlet for
the regenerated catalyst linked to the first reactor, a separation
device for separating flue gas from the regenerated catalyst, an
outlet for the flue gas and an outlet for the regenerated catalyst
linked to the first reactor.
8. The apparatus as claimed in claim 6, wherein the catalyst
regenerator is a single stage or multistage regenerator.
9. The apparatus as claimed in claim 6, wherein the distributor is
selected from manifold type, concentric ring type, perforated plate
type and the like.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 13/638,460, which is the U.S. national stage of International
Application No. PCT/IN2011/000223, filed Mar. 30, 2011, which
claims priority to Indian Application No. 793/DEL/2010, filed Mar.
31, 2010. The foregoing applications are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for simultaneous
cracking of lighter and heavier hydrocarbon feedstocks. In this
process the light and heavy feeds are processed in two different
reactors operated in series with respect to catalyst flow and
parallel with respect to feed flow to produce light olefins in the
range of C2 to C4 and aromatic products in the range C6 to C8
mainly benzene, toluene, xylene and ethyl benzene and other useful
products. The present invention also relates to an apparatus for
simultaneous cracking of lighter and heavier hydrocarbon feeds.
BACKGROUND OF THE INVENTION AND PRIOR ART
[0003] Light olefins like ethylene, propylene and butylenes are
considered as the major building blocks for the production of
various petrochemicals. These chemicals are widely used for the
production of polyethylene, polypropylene, di-isobutylene,
polyisobutylene etc. Conventional steam cracking process remains
the major source of light olefins, mainly ethylene and propylene to
the petrochemical industry. In the emerging scenario, the demand
growth of propylene as petrochemical feedstock is expected to be
much higher than that of ethylene. Propylene is the major byproduct
from the steam cracking process, which contributes about 70% of
world's propylene demand. About 30% of world's propylene demand is
from the conventional Fluid Catalytic Cracking (FCC) units. In
recent years, there is a significant gap between the demand and
supply of propylene. Consequently, the industry is in the lookout
for technology for augmenting production of light olefins. To
bridge the gap between the demand and supply of propylene, a new
catalytic process is required for production of propylene as the
primary product.
[0004] Fluid Catalytic Cracking (FCC) process is well known since
1942. The history and the evolution of FCC process at various
generations are detailed in the book "Fluid Catalytic Cracking
Handbook" by Reza Sadeghbeigi, Gulf publishing company, "Fluid
Catalytic Cracking" by Wilson, and various other literatures.
[0005] In general, cracking is defined as breaking down of
hydrocarbons of higher molecular weight into lower molecular weight
hydrocarbons. It can be carried out thermally or catalytically. In
fluid catalytic cracking process, the catalyst is a fluidizable
fine particle in the size range of 5-150 microns. The steps
involved in the conventional FCC process are described below:
[0006] i. Hydrocarbon feedstock is preheated to a temperature range
of 150-400.degree. C. to enhance the atomization/vaporization of
feed; [0007] ii. The preheated feed is mixed with the steam at
particular ratio and passed through a nozzle to disperse the feed
into fine droplets inside an up-flow riser; [0008] iii. The
dispersed feed gets contacted with the hot regenerated catalyst at
the bottom of the riser, where the reactions are initiated to take
place along the remaining length of the riser; [0009] iv. The
mixture of catalyst and products of catalytic cracking is separated
by a termination device; further, the entrained catalyst is
separated from the product vapor by cyclone separators and
transferred to the catalyst bed in the reactor stripper; [0010] v.
The entrapped hydrocarbon components are removed from the separated
catalyst by stripping using steam; [0011] vi. The coke laden
fluidizable catalyst, often referred as spent catalyst, is
transferred to a regenerator through spent catalyst standpipe and
spent catalyst slide valve; [0012] vii. The deposited coke in the
catalyst is burnt in the regenerator using air and the hot
regenerated catalyst is transferred to riser through regenerated
catalyst standpipe and regenerated catalyst slide valve for the
next cycle of operation.
[0013] In this manner, FCC process is termed as a cyclic process
where the reaction and regeneration takes place continuously in a
riser (reactor) and regenerator respectively. A particular amount
of fresh catalyst is added to the circulating inventory in order to
maintain the activity of the catalyst while keeping the inventory
at constant level.
[0014] In the present scenario, as worldwide crudes are becoming
heavier, processing of heavy crudes has become important,
especially to increase the profit margin. Because of this, it is
preferable to maximize the intake of vacuum residue or atmospheric
residue in feed to FCC/RFCC unit. However, increase in
concentration of heavy ends in FCC unit feed will have several
deleterious effects in the known resid FCC units. The associated
problems in processing heavy residue in the FCC units are as
follows: [0015] i. Excessive coke with the residue produces large
amount of excess heat in the regenerator and therefore, the heat
balance of the reactor regenerator results in lower conversion.
[0016] ii. Higher metal level on the resid leads to significant
deactivation of the catalyst and requires incremental catalyst
addition to keep the metal level on equilibrium catalyst within
acceptable range. Crackability of some of the residues, in
particular aromatic residues, are not quite good leading to lower
conversion. [0017] iii. Strippability of the heavier unconverted
residue inside the catalyst pores is not efficient resulting in
higher regenerator temperature and thereby lower conversion.
[0018] The excessive coke in the catalyst generates lot of heat
while burning in the regenerator, which limits the catalyst
circulation rate to the riser reactor zone, thereby reduces the
overall conversion. In order to mitigate this problem catalyst
coolers are used conventionally in the resid FCC units, which cools
the catalyst indirectly using steam/water as the coolant. These
coolers are disclosed in the U.S. Pat. Nos. 2,377,935, 2,38,6491,
2,662,050, 2,492,948, and 4,374,750.
[0019] U.S. Pat. No. 5,215,650 discloses the indirect cooling of
the hot regenerated catalyst via shell and tube heat exchanger type
reactor where cracking of light alkanes like ethane, propane and
butane takes place and then the cooled catalyst is transferred to
the riser reactor. U.S. Pat. No. 4,840,928 discloses the process of
converting lower alkanes to olefins in a third bed, external
catalyst cooler in which the excess heat from the regenerator is
used directly for thermal cracking of lower alkanes mainly propane
with a WHSV of not exceeding 5 hf.sup.1 in the said reactor.
[0020] Production of light olefins from feed stocks like VGO is
disclosed in the U.S. Pat. No. 6,656,346, U.S. Pat. No. 4,980,053,
U.S. Pat. No. 6,210,562, U.S. Pat. No. 5,846,402, U.S. Pat. No.
6,538,169, U.S. Pat. No. 5,326,465, and US2006/0108260.
[0021] Production of light olefins from naphtha range feed stocks
are disclosed in several documents like U.S. Pat. No. 4,287,048,
U.S. Pat. No. 5,232,580, U.S. Pat. No. 5,549,813, U.S. Pat. No.
6,288,298, U.S. Pat. No. 3,082,165, U.S. Pat. No. 3,776,838, U.S.
Pat. No. 5,160,424, U.S. Pat. No. 5,318,689, U.S. Pat. No.
5,637,207, U.S. Pat. No. 5,846,403, U.S. Pat. No. 6,113,776, U.S.
Pat. No. 6,455,750, U.S. Pat. No. 6,602,403, U.S. Pat. No.
6,867,341, U.S. Pat. No. 7,087,155, US2001/042700, US2002/003103,
US2003/220530, US2005/070422, US2006/10826, WO2000/18853,
WO2002/26628, WO2004/078881, WO2006/098712. Catalytic Cracking of
lighter feedstocks like propane, straight run naphtha, olefinic
naphtha to produce significant yields of light olefins has its own
limitation for commercial realization due to its less coke which
affects the heat balance of the unit i.e. the `coke produced during
the reaction is not sufficient to produce the enough heat which is
required for cracking of lighter feeds.
[0022] U.S. Pate. No. 7,611,622B2 discloses a dual riser Fluid
catalytic cracking (FCC) process with common regenerator involves
cracking of first hydrocarbon feed in first riser and cracking of
second hydrocarbon feed comprising light hydrocarbons including C3
and/or C4 hydrocarbons, in second riser to form second effluent
enriched in light olefins and aromatics. Moreover this invention
uses gallium included catalyst to promote aromatics formation.
[0023] Chinese patent CN 101522866A discloses a dual riser FCC
process, wherein first and second hydrocarbon feeds (first
hydrocarbon is olefin and the second hydrocarbon feed is
paraffinic) are supplied to the respective first and second risers
to make an effluent rich in ethylene, propylene and/or aromatics
and the respective risers can have different conditions to favor
conversion to ethylene and/or propylene.
[0024] Some patent literatures, like U.S. Pat. No. 6,113,776,
US2002/0003103, U.S. Pat. No. 7,128,827 disclose the concept of
dual riser or multiple riser cracking where the portion of the
catalyst is used for cracking the lighter hydrocarbons like naphtha
range feed stocks and the other portion of catalyst is used in the
conventional FCC riser. U.S. Pat. No. 5,846,403 discloses the
process in which the naphtha is injected in the same reaction zone
but at different elevations of the riser reactor.
[0025] None of the cited patents mention about the simultaneous
Catalytic cracking of lighter feed stocks and heavier feed stocks
in different reactors operating in different regimes and conditions
to produce significant amount of light olefins and aromatics like
benzene toluene, xylene, ethyl benzene etc.
[0026] An aim of the present invention is to provide a new
catalytic cracking process for simultaneously cracking lighter and
heavier hydrocarbon feedstock to produce light olefins and liquid
aromatic products.
[0027] Another aim is to provide a multiple reaction zone system
that enables the production of light olefins and liquid aromatic
products both from lighter and heavier hydrocarbon cracking.
[0028] Yet another aim of the invention is to provide a catalyst
system that can crack both lighter and heavier hydrocarbon under
wide range of operating conditions.
[0029] A further aim of the present invention is to reduce the
sulfur content of the cracked products boiling in the range of C5
to 150.degree. C. from first reaction zone by not less than 60
wt%.
[0030] Another aim of the invention is to utilize the excess heat
generated in the regenerator due to excess coke burning, which in
turn is due to processing of heavier feedstocks in the second
reaction zone, effectively in the first reaction zone for cracking
of lighter hydrocarbon feedstocks, thereby reducing the temperature
of the catalyst entering into the second reaction zone.
[0031] Another aim of the invention is to provide a suitable
apparatus for carrying out the said new catalytic process.
SUMMARY OF THE INVENTION
[0032] The present invention discloses a catalytic cracking process
in which lighter hydrocarbon feed stocks like propane, butane,
isobutane, n-butenes, isobutene, straight run naphtha, visbreaker
naphtha, coker naphtha, FCC naphtha, hydrocracker and hydrotreater
naphthas, natural gas condensate, LPG condensate, gas well
condensate are processed in the first reaction zone utilizing the
excess heat of regenerated catalyst due to processing of heavier
feedstocks in the second reaction zone using single catalyst
composition.
DESCRIPTION OF THE INVENTION
[0033] The present invention provides a process for simultaneous
catalytic cracking of lighter and heavier hydrocarbon feedstocks
into improved yields of light olefins, liquid aromatics and other
useful products in multiple reaction zones in different reactors
operating under different regimes and conditions comprising the
steps of: [0034] a) cracking the lighter hydrocarbon feedstock in a
first reaction zone in the first reactor to get a first reactor
effluent mixture; [0035] b) separating the first reactor effluent
mixture of step (a) into a vapor rich phase and a solid rich phase;
[0036] c) separating the vapor rich phase of step (b) in a product
separator into C5- fractions as the light olefins product and C5+
fractions; [0037] d) recycling the C5+ fractions back to the first
reaction zone and continuing the cracking operation until the
aromatics concentration in C5+ fraction reaches more than 90 wt %;
[0038] e) stripping a portion of the solid rich phase of step (b)
containing coke laden catalyst using steam to remove entrapped
hydrocarbons along with vapor rich phase entering the product
separator; [0039] f) transferring the remaining portion of the
solid rich phase of step (b) containing coke laden catalyst from
the first reaction zone to a second reaction zone of a second
reactor, cracking the heavier hydrocarbon feedstock therein at a
relatively lesser temperature and pressure as `compared with those
in the first reaction zone to get a second reactor effluent
mixture; [0040] g) separating the effluent mixture of step (f) into
a vapor rich phase and a solid rich phase containing coke laden
spent catalyst; [0041] h) fractionating the vapor rich phase of
step (g) to get different cracked products; [0042] i) stripping the
solid rich phase of step (g) using steam to remove entrapped
hydrocarbons along with vapor rich phase of step (g); [0043] j)
regenerating the coke laden stripped spent catalyst obtained from
step (i) and step (e) in a common catalyst regenerator using air
and/or an oxygen containing gas to produce an active regenerated
catalyst for recirculating to the first reaction zone through
regenerated catalyst standpipe and regenerated catalyst slide valve
for the next cycle of operation.
[0044] This invention also provides a multi-reactor fluidized bed
catalytic cracking apparatus for the production of light olefins
and liquid aromatics etc. through simultaneous cracking of lighter
and heavier hydrocarbon feedstocks in separate reaction zones
comprising at least a first reaction zone in a first reactor (4), a
second reaction zone in a second reactor (6) and a catalyst
regenerator (12).
[0045] According to the said process lighter hydrocarbon feed is
cracked with steam in a molar ratio in the range of 1:60 and 60:1
in a bubbling or turbulent bed first reaction zone with a hot
regenerated catalyst mixture operated in a temperature range of 500
to 750.degree. C. and pressure in the range of 1 to 5 kg/cm.sup.2
to obtain first reactor effluent mixture comprising cracked
hydrocarbon product vapor and a coke laden catalyst. The first
reactor effluent mixture is separated into a vapor rich phase and a
solid rich phase containing the coke laden catalyst. The vapor rich
phase is cooled and separated into C5- and C5+ fractions in a
separator and the C5+ fraction is recycled to the first reaction
zone until the aromatics concentration in C5+ product from the
first reaction zone reaches more than 90 wt %. A portion of the
solid rich phase containing coke laden catalyst is stripped using
steam to remove entrapped hydrocarbons along with the vapor rich
phase entering into the product separator. The remaining portion of
hot coke laden spent catalyst is transferred from first reaction
zone to second reaction zone comprising a riser operating in fast
fluidization regime or pneumatic conveying regime, the heavier
hydrocarbon feed stock is cracked in the second reaction zone
operated in the temperature range of 450 to 700.degree. C. and
pressure in the range of 0.9 to 4.9 kg/cm.sup.2 to obtain a second
reactor effluent. The second reactor effluent is separated into a
vapor rich phase and a solid rich phase containing coke laden
catalyst. The vapor rich phase is removed and fractionated to get
the cracked products. The solid rich phase is stripped from the
second reaction zone using steam to remove entrapped hydrocarbons
along with vapor rich phase entering into the fractionating column
for separation into products. The coke laden catalyst obtained from
second stripping zone and the coke laden catalyst obtained from
first stripping zone are regenerated in a common regenerator using
air and/or oxygen containing gas to produce hot regenerated
catalytic mixture.
[0046] An embodiment of the present invention provides a process
for simultaneous cracking of lighter and heavier hydrocarbon feeds,
further comprises transferring active hot regenerated catalytic
mixture to the first reaction zone for the next cycle of
operation.
[0047] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the lighter hydrocarbon feed comprises.
C3 fraction containing propane and propylene and C4 fraction
containing n-butane, isobutane, isobutene, butene-1, cis-2-butene,
trans-2-butene and hydrocarbons boiling upto 220.degree. C. (true
boiling point basis).
[0048] An embodiment of the present invention provides a process
for simultaneous cracking of lighter and heavier hydrocarbon feeds,
wherein the lighter hydrocarbon feed is selected from petroleum
based light feed stock, such as propane, butane, isobutene,
n-butenes, isobutane, straight run naphtha, visbreaker naphtha,
coker naphtha, FCC naphtha, hydrocracker naptha, hydrotreated
naphtha, natural gas condensate, LPG condensate and gas well
condensate or mixtures thereof.
[0049] Yet another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the lighter hydrocarbon feed is
preferably selected from straight run naphtha, visbreaker naphtha,
coker naphtha, FCC naphtha, Hydrocracker and hydrotreater naphtha,
natural gas condensate, LPG condensate, and Gas well condensate or
mixture thereof.
[0050] It is an embodiment of the present invention to provide a
process, wherein the cracking operation in the first reaction zone
is carried out at a temperature of 500-750.degree. C., preferably
at a temperature of 550-700.degree. C., pressure of 1 to 5
Kg/cm.sup.2 and WHSV of 1 to 200 hf' preferably at a WHSV of 6 to
120 hf', whereas the said operation is carried out in the second
reaction zone at a temperature of 450-700.degree. C., preferably at
480-600.degree. C., pressure of 0.9 to 4.9 Kg/cm.sup.2 and WHSV of
10 to 400 V.sup.1, preferably at 60-250 hf'.
[0051] Further embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the heavier hydrocarbon feed has an
initial boiling point of more than 220.degree. C.
[0052] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the heavier hydrocarbon feed is selected
from petroleum based heavy feed stock, such as vacuum gas oil
(VGO), visbreaker/coker heavy gas oil, fuel oil, coker fuel oil,
hydrocracker bottoms, vacuum slop, cycle oils, foots oil, slurry
oils, atmospheric gas oil, atmospheric residue and vacuum residue
or mixtures thereof.
[0053] Still another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the Conradson carbon residue of the
heavier hydrocarbon feeds is in the range of 0.1-15 wt %.
[0054] Yet another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the Conradson carbon residue of the
heavier hydrocarbon feeds is more than 3 wt %.
[0055] Hydrocarbon feed for the present invention comprises
hydrocarbon fractions starting from carbon number 3 to carbon
number 100 and above. The lighter hydrocarbon fraction could be
propane, butane, isobutane, n-butenes, isobutene, straight run
naphtha, visbreaker naphtha, coker naphtha etc. and the heavier
hydrocarbon fraction could be straight run, light and heavy vacuum
gas oil, hydrocracker bottom, heavy gas oil fractions from
hydrocracking, FCC, visbreaking or delayed coking, atmospheric
residue, vacuum residue, vacuum slops etc. The conditions in the
process of the present invention are adjusted depending on the type
of the feedstock so as to maximize the yield of light olefins and
liquid aromatic products like benzene, toluene, xylene, ethyl
benzene etc. The above feedstock types are for illustration only
and the invention is not limited in any manner to only these
feedstocks.
[0056] Further embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the catalyst is made up of solid
micro-spherical acidic materials with average particle size of
60-80 micron and apparent bulk density of 0.7-1.0 gm/cc.
[0057] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the catalyst is specifically designed to
handle both the lighter and heavier feed stocks in first and second
reaction zones respectively to selectively produce light olefins
like ethylene, propylene and aromatic liquid products like benzene,
toluene, xylene, ethyl benzene etc.
[0058] The catalyst employed in the process of the present
invention is having unique composition which comprises Y-zeolite in
rare earth ultra-stabilized form, bottom cracking components
consists of peptized alumina, acidic silica alumina or
gamma-alumina, pentasil shape selective zeolites or a mixture
thereof. It may be noted that both the first and second stage
reaction zone are charged with the same catalyst and its
composition is designed in such a way that it can optimally crack
both the lighter and heavier hydrocarbon feed. It may also be noted
that conventional FCC catalyst mainly consists of Y-zeolite in
different forms as active ingredient to accomplish catalytic
cracking reactions.
[0059] In the process of the present invention, the active catalyst
components are supported on relatively inactive materials such as
silica/alumina or silica-alumina compounds, including kaolinites or
with active matrix components like pseudobomite alumina. The active
components could be mixed together before spray drying or
separately binded, supported and spray-dried using conventional
spray drying technique. The spray-dried micro-spheres are washed,
rare earth exchanged and flash dried to produce finished catalyst
particles. The finished micro-sphereS containing active materials
in separate particles are physically blended in the desired
composition.
[0060] Still another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the lighter hydrocarbon and steam at
saturated or at superheated conditions are mixed in the zone prior
to the contact with the catalyst and uniformly distributed using
any of the conventional distributors like manifold type, concentric
ring type, perforated plate type, etc. into the first reaction
zone.
[0061] Further embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the lighter hydrocarbon feed and steam
at saturated or at superheated conditions are uniformly contacted
with hot catalyst from the common regenerator in the first reaction
zone.
[0062] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the ethylene to propylene ratio in the
first reaction zone can be varied by tuning the steam to
hydrocarbon feed mole ratio in the range of 1:60 and 60:1 along
with changes in the process variables.
[0063] Yet another embodiment of the present invention provide a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the coke on the catalyst from the first
reaction zone is not more than 0.35 wt %.
[0064] Further embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the regenerator can be a single stage or
multistage to burn the entire coke laden spent catalyst to form
regenerated catalyst with coke content not exceeding 0.09 wt %.
[0065] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the sum of yields of ethylene plus
propylene is not less than 25 wt % in the first reaction zone and
not less than 15 wt % in the second reaction zone.
[0066] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the excess heat generated in the
regenerator due to processing of heavy feedstocks in the second
reaction zone is utilized effectively for cracking the lighter
hydrocarbon feedstock at very high temperatures in the first
reaction zone.
[0067] Still another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the common regenerator can be a single
stage or multistage to burn the entire coke laden spent catalyst to
form regenerated catalyst with coke content not exceeding 0.09 wt %
and thus meeting the heat requirement of the first and second
reaction zones.
[0068] Another embodiment of the present invention is to provide a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the light and the heavy feeds are
processed in two different reactors operated in series with respect
to catalyst flow and parallel with respect to feed flow to produce
light olefins in the range of C2 to C4 and aromatic products in the
range C6 to C8 mainly benzene, toluene, xylene and
ethylbenzene.
[0069] Another embodiment of the present invention provides a
process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein C5+ fraction of the products from first
reaction zone is recycled to the first reaction zone and the
cracking operation is continued until the aromatics concentration
in C5+ fraction reaches more than 90 wt %.
[0070] Yet another embodiment of the present invention is to
provide a process for simultaneous cracking of lighter and heavier
hydrocarbon feeds, wherein the liquid product boiling in the range
of C5 to 220.degree. C. from both first and second reaction zones
rare separated to produce various petrochemical feedstocks
primarily benzene, toluene, xylene and ethylbenzenec.
[0071] Further embodiment of the present invention is to provide a
catalytically cracked product, wherein the propylene to ethylene
ratio in the products from second reaction zone is not less than
2.5:1.
[0072] The conversion in the second reaction zone defined as sum of
all products boiling less than or equal to 220.degree. C. plus coke
is not less than 70 wt %.
[0073] Yet another embodiment of the present invention is to
provide a process for cracking lighter and heavier hydrocarbon
feedstock simultaneously, wherein there is a multiple reaction zone
system that enables the production of light olefins and liquid
aromatic products both from lighter and heavier hydrocarbon
cracking.
[0074] An embodiment of the present invention is to provide a
catalyst system that can crack both lighter and heavier hydrocarbon
under wide range of operating conditions.
[0075] Further embodiment of the present invention is to reduce the
sulfur content of the cracked products boiling in the range of C5
to 150.degree. C. from first reaction zone by not less than 60
wt%.
[0076] Another embodiment of the present invention is to utilize
the excess heat generated in the regenerator due to burning of
excess coke produced by the cracking of heavier feedstocks in the
second reaction zone, effectively in the first reaction zone for
cracking of lighter hydrocarbon feedstocks thereby reducing the
temperature of the catalyst entering into the second reaction
zone.
[0077] The main products in the process of the present invention
are the light olefins and liquid aromatic products in the range C6
to C8 mainly benzene, toluene and xylene. Light olefins include
ethylene, propylene, isobutylene, trans-2-butene, cis-2-butene,
butene-1 etc. Other useful products of the present invention
comprise LPG (C3 and C4), Gasoline (C5-150.degree. C.), Heavy
naphtha (150.degree. C.-216.degree. C.), Light Cycle oil
(216-370.degree. C.) and Bottoms (370.degree. C.+).
DETAILED DESCRIPTION OF THE INVENTION
[0078] FIG. 1 shows a fluidized bed cracking apparatus with
multiple reaction zones according to the present invention.
[0079] Fluidized catalytic cracking (FCC) process of the present
invention to produce light olefins and aromatics rich liquid
products etc. through simultaneous cracking of light and heavy
feeds in separate reaction zones utilizes at least two reactors.
Fresh heavy feed (1) is injected at the bottom of the riser through
a single or multiple feed nozzle (2 ), wherein the heavy feed is
mixed with the dispersion steam (3) so as to enable the better
atomization of the feed molecules in the riser. The hot partially
coked catalyst from the first reactor 4) enters into the bottom of
the riser (6) through the slide valve (5) whereupon it comes into
contact with the atomized feed. The catalyst along with hydrocarbon
feed and product vapors ascend the riser, wherein the recycle
slurry (7) gets in to contact with the catalyst for re-cracking.
The entire mixture of catalyst, products and unconverted feed
ascend the riser and at the end of the riser coked spent catalyst
is separated from the hydrocarbon vapor in the riser termination
device (8). The hydrocarbon vapors leaving from the riser reactor
are sent to a main fractionator column via plenum chamber (9) for
separating into the desired products. The coked catalyst is
subjected to steam stripping in a stripper (10) to remove the
entrapped hydrocarbons from the catalyst. The stripped catalyst is
passed to a regenerator (12) through a slide valve (11) and
distributed via
spent catalyst distributor (13) where the coke deposited on the
catalyst is burnt off by means of air or any oxygen containing gas
which is distributed through the air distributor (14).
[0080] The clean hot catalyst from the regenerator passes through
the slide valve (15) and distributed in the fluidized dense bed
reactor (4) through the regenerated catalyst distributor (16).
Preheated fresh light feed (17) and recycled light feed (18) are
mixed with the process steam (19) at the bottom of the conduit (20)
and distributed in the light feed distributor (21) where upon it
gets contacted with the clean hot regenerated catalyst. The cracked
products along with entrained catalyst is separated in the
separation device (22) wherein the product of cracking is separated
from the entrained catalyst and sent to the fractionation column to
separate into various products. The partially coked catalyst from
reactor (4) is circulated back to the bottom of the riser through
the slide valve (5).
[0081] The invention and its embodiments are described in further
details hereunder with reference to the following examples which
should not be construed to limit the scope of the invention in any
manner. Various modifications of the invention that may be apparent
to those skilled in the art are deemed to be included within the
scope of the present invention.
EXAMPLE 1
[0082] Yield of Light Olefins at Different Conversions in
Conventional FCC Operation This example illustrates the change in
yield of the light olefins at different conversion levels under
conventional FCC conditions. 216.degree. C. conversion is defined
as the total quantity of products boiling below 216.degree. C.
including coke. The experiments were conducted in standard fixed
bed Micro Activity Test (MAT) reactor described as per ASTM D-3907
with minor modifications indicated subsequently as modified MAT.
The catalyst is steamed at 810.degree. C. for 3 hours in presence
of 100% steam prior to conducting the experiments. The properties
of Feed-A used in the modified MAT reactor are given in the
Table-1.
TABLE-US-00001 TABLE 1 Properties of Feed-A Unit Feed-A Property
Density @ 15.degree. C. gm/cc 0.9116 Sulfur wt % 1.37 CCR wt % 0.17
Basic Nitrogen ppmw 489 Saturates (Paraffin + naphthene) wt % 62.6
Aromatics wt % 37.4 Distillation, ASTM D-1160 5 vol % .degree. C.
395 10 vol % .degree. C. 410 30 vol % .degree. C. 445 50 vol %
.degree. C. 470 70 vol % .degree. C.' 495 90 vol % .degree. C. 545
95 vol % .degree. C. 570
[0083] The runs were, taken at a reaction temperature of
511.degree. C., feed injection time of 30 seconds with different
severities by varying feed rate with the same catalyst loading.
Catalysts used in this example catalyst A which is a commercially
available FCC catalyst having physicochemical characteristics as
shown in the Table below.
TABLE-US-00002 CAT-A Activity wt % 63.9 Al.sub.20.sub.3 wt % 40.42
Re.sub.2O.sub.3 wt % 2.63 SA .sub.mZ.sub.igni 145 PV cc/gm 0.293
ABD gm/cc 0.89 APS micron. 103 Crystalinity % 9.1 UCS .degree.A
24.30
[0084] In all the examples, Dry gas is defined as the product
comprising C 1 and C2 hydrocarbons, and hydrogen, while LPG is
defined as the product comprising C3 and C4 hydrocarbons.
TABLE-US-00003 TABLE 2 Effect of severity on product yields
Reaction Severity, W/F, min 0.69 0.86 1.07 1.46 Yields, wt %
Hydrogen 0.05 0.06 0.06 0.10 Ethylene 0.64 0.90 0.97 1.14 Dry gas
1.13 1.39 1.73 2.19 Propylene 2.79 3.47 3.98 4.55 But-l-ene 0.83
0.99 1.08 1.19 Isobutene 1.26 1.37 1.42 1.39 trans-2 Butene 1.31
1.54 1.63 1.73 Cis-2-Butene 0.80 0.94 1.00 1.06 LPG 7.35 9.13 11.00
13.09 Gasoline (C5-150.degree. C.) 24.01 28.36 31.42 35.40 Hy.
Naphtha (150-216.degree. C.) 13.01 14.04 14.80 14.96 LCO
(216-370.degree. C.) 25.68 25.23 24.20 21.93 216 Conversion, wt %
46.62 54.35 60.84 68.28
[0085] The product yields along with conversions are given in
Table-2 wherein it is observed that with increase in severity
conversions increases along with the increase in ethylene and
propylene yields.
EXAMPLE 2
Yields of Light Olefins and Aromatics from Naphtha Cracking in
Conventional FCC Operation
[0086] This example illustrates the yield of the light olefins at
conventional FCC naphtha cracking operation. Cracking experiments
are carried out at 500.degree. C. at the catalyst to oil ratio of
5.11. properties of the Feed-B used in the modified MAT reactor are
given in the following Table-3.
TABLE-US-00004 TABLE 3 Properties of Feed-B Property Unit Feed-B
Density @ 15.degree. C. gm/cc 0.7358 Sulfur PPM 18 Paraffin wt %
39.6 Olefin wt % Nil Naphthene wt % 47.7 Aromatics wt % 12.7
Benzene 0.83 Toluene 3.1 Xylene 4.25 Distillation D-86 5 vol %
.degree. C. 68.5 10 vol % .degree. C. 73.5 30 vol % .degree. C. 88
50 vol % _.degree. C. 100.8 70 vol % .degree. C. 113 90 vol %
.degree. C. 132 95 vol % .degree. C. 146.5
[0087] The light olefins yield is shown in the Table-4.
TABLE-US-00005 TABLE 4 Light olefins yield at 500.degree. C.
Reaction Severity, cat/oil 5.11 Yields, wt % Ethylene 2.21
Propylene 4.72 But-l-ene 0.46 Isobutene 1.23 trans-2 Butene 0.75
Cis-2-Butene 0.61
EXAMPLE 3
Effect of Recycle of Cracked Naphtha
[0088] This example illustrates the effect of recycle of cracked
naphtha on liquid aromatics yield. The product obtained from
Example-2 is recycled back i.e. cracked at similar conditions as
mentioned in Example-2. The yields of different aromatic products
are shown in Table-5. This clearly indicates that there is a
significant increase in aromatics yield in 2nd recycle product as
compared to the first recycle product.
TABLE-US-00006 TABLE 5 Total aromatics content, % wt/wt 2nd Recycle
Component 1st Recycle FCC product FCC product Benzene 3.8 5.3
Toluene 15.4 24.8 Ethyle benzene 1.6 2.3 m-p Xylene 10 15.6
o-xylene 2.8 4.8 n Propyl bebzene + methyl 1.4 0.3 ethyl benzene
Tri methyl benzene + methyl 0.5 0.6 butyl cyclopentane Tri methyl
benzene + methyl 1.4 2.9 propyl cyclohexane
EXAMPLE 4
Yields of Light Olefins in the First Reaction Zone Using Light
Feed
[0089] This example illustrates the yield of light olefins and
other useful products obtained in the first reaction zone of the
present invention. The properties of feed used, the operating
conditions maintained in the micro-reactor and the product yields
are given in the Table-6
TABLE-US-00007 TABLE 6 Feed B Feed C Feed properties Density, g/cc
@ 15.degree. C. 0.7358 0.7223 Sulfur content, PPM 18 1600 IBP,
.degree. C. 51 45 FBP, .degree. C. 153 160 Operating conditions
Reaction severity, W/F min 1.94 3.41 Reaction temperature, .degree.
C. 625 650 Yield, wt % Dry Gas 13.62 25.44 Ethylene 8.17 14.76 LPG
39.48 37.75 Propylene 14.23 19.63 Gasoline (C5-150.degree. C.)
38.63 30.42 Heavy naphtha (150-216.degree. C.) 3.87 3.97 LCO
(216-370.degree. C.) 2.06 0 CLO (370.degree. C.+) 0 0 Coke 2.34
2.42
EXAMPLE 5
Yields of Light Olefins in Second Reaction Zone Using Heavy
Feed
[0090] This example illustrates the yield of light olefins and
other useful products obtained in the second reaction zone of the
present invention. The properties of feed used, the operating
conditions maintained in the micro-reactor and the product yields
are given in the Table-7
TABLE-US-00008 TABLE 7 Feed D Feed E Feed properties Density, g/cc
@ 15.degree. C. 0.8938 0.845 CCR, wt % 0.3 0.013 IBP, .degree. C.
330 339 FBP, .degree. C. 560 523 Operating conditions Reaction
severity, W/F min 1.068 1.098 Reaction temperature, .degree. C. 580
580 Yield, wt % Dry Gas 10.53 4.4 Ethylene 6.74 2.66 LPG 49.31
61.41 Propylene 23.65 25.9 Gasoline (C5-150.degree. C.) 15.09 14.6
Heavy naphtha (150-216.degree. C.) 5.31 3.54 LCO (216-370.degree.
C.) 9.12 6.18 CLO (370.degree. C.+) 4.22 3.7 Coke 6.42 6.17
Conversion 216.degree. C. 86.66 90.12
EXAMPLE 6
Effect of Temperature in the First Reaction Zone
[0091] This example illustrates the effect of temperature on yield
of light olefins and other useful products obtained in the first
reaction zone of the present invention. The properties of feed
used, operating conditions maintained in the micro-reactor and the
product yields are given in the Table-8
TABLE-US-00009 TABLE 8 Feed F Feed F Feed properties Density, g/cc
@ 15.degree. C. 0.6952 0.6952 IBP, .degree. C. 52.8 52.8 FBP,
.degree. C. 179.8 179.8 Operating conditions WHSV, hr-1 24.43 22.64
Reaction temperature, .degree. C. 660 700 Product yields, wt % Dry
Gas 26.57 39.45 Ethylene 14.21 23.67 LPG 37.2 30.56 Propylene 20.92
18.72 Gasoline (C5-150.degree. C.) 28.97 18.94
[0092] It is evident that by increasing the temperature in the
first reaction zone, the yields of both ethylene and propylene
increases significantly.
EXAMPLE 7
Effect of Weighted Hour Space Velocity (WHSV) in First Reaction
Zone
[0093] This example illustrates the effect of WHSV on yield of
light olefins and other useful products obtained in the first
reaction zone of the present invention using the same feed (Feed-F)
as that of Example-6. The operating conditions maintained in the
micro-reactor and the product yields are given in the Table-9
TABLE-US-00010 TABLE 9 Operating conditions WHSV, hr-1 19.01 26.95
40.32 Reaction temperature, .degree. C. 660 660 660 Product yields,
wt % Dry Gas 27.71 26.65 24.35 Ethylene 13.11 12.26 11.51 LPG 38.54
37.01 35.35 Propylene 23.39 22.45 21.28 Gasoline (C5-150.degree.
C.) 25.4 27.98 30.35
[0094] It is clear that by increasing the WHSV in the first
reaction zone, the yields of both ethylene and propylene decreases.
From Example-6 & 7, it is clear that the process conditions as
well as the hydrodynamic regime is important in maximizing the
yields of light olefins.
EXAMPLE 8
Combined Cracking of Light and Heavy Feed in Conventional FCC
Operation Using Single Reaction Zone
[0095] This example illustrates the yield of light olefins and
other useful products obtained in the single reaction zone of the
conventional FCC operation. The feed to the reactor comprises 15 wt
% light feed mixed with 85 wt % of heavy feed. The combined feed
properties, operating conditions maintained in the micro-reactor
and the product yields are given in the Table-10
TABLE-US-00011 TABLE 10 Feed G Feed properties Density, g/cc @
15.degree. C. 0.8574 CCR 2.17 Sulfur, PPM 8500 Operating conditions
Reaction temperature, .degree. C. 540 Product yields, wt % Dry Gas
4.8 Ethylene 2.0 LPG 35.6 Propylene 12.5 Gasoline (C5-180.degree.
C.) 40.4 LCO 12.1 CLO 2.4
EXAMPLE 9
Effect of Simultaneous Cracking of Light and Heavy Feed at
Different Reaction Zone Operating at Different Conditions as
Present Invention
[0096] This example illustrates the yield of light olefins and
other useful products obtained in the first and second reaction
zone of the present invention. Light feed corresponding to 15 wt %
of total feed of Example-8 is cracked in the first reaction zone at
680.degree. C. and the heavy feed corresponding to 85 wt % of total
feed of Example-8 is cracked simultaneously in the second reaction
zone. The feed properties and the operating conditions maintained
in the micro-reactor for first and second reaction zone along with
product yields are given in the Table-11.
TABLE-US-00012 TABLE 11 Reaction zone First Second Feed H Feed I
(Light feed) (Heavy feed) Feed properties Density, g/cc @
15.degree. C. 0.6798 0.8988 CCR -- 2.55 Sulfur, PPM 5800 8980
Operating conditions Reaction temperature, .degree. C. 680 540
Product yields, wt % Dry Gas 31.78 5.1 Ethylene 17.48 2.3 LPG 35.36
39.7 Propylene 19.72 15.9 Gasoline (C5-180.degree. C.) 29.36 36.1
LCO -- 13.5
[0097] It is clearly evident from the Example-8 and Example-9 that
the sum of yields of ethylene and propylene is much superior in the
present invention than that in the conventional process.
[0098] The embodiments of the present invention referred to in the
above description and examples are for illustration only and not
construed to be limitative. Other possible embodiments of the
invention will be apparent to these skilled in the art from
consideration of the specification and practice of the invention
disclosed herein. The exact scope and spirit of the invention are
intended to be governed by the following claims.
* * * * *