CA1233425A - Fluid catalytic cracking systems - Google Patents
Fluid catalytic cracking systemsInfo
- Publication number
- CA1233425A CA1233425A CA000443269A CA443269A CA1233425A CA 1233425 A CA1233425 A CA 1233425A CA 000443269 A CA000443269 A CA 000443269A CA 443269 A CA443269 A CA 443269A CA 1233425 A CA1233425 A CA 1233425A
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- Canada
- Prior art keywords
- feed
- liquid
- hydrocarbon
- orifice
- stream
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
Abstract An improved liquid hydrocarbon feed method is disclosed wherein substantially all of the liquid is converted to mist sized particles over a wide angled dispersion pattern without a concurrent shroud of steam or water. Such dispersion promotes vapor phase catalytic reaction between hydrocarbon vapors and fluidized catalyst in a reaction time of 1 to 3 seconds. In a preferred form, the liquid feed is introduced into the transition section of a riser reactor. The misting nozzle is characterized by a swirl chamber to which the full hydrocarbon feed is supplied for centrifugal rotation by vane members and the flow is released through a reduced area orifice having a short throat to maintain a low pressure drop through the nozzle and a cylindrically confined stream flow into the riser reactor produces a wide angled conical dispersion pattern. Introduction of such a hydrocarbon dispersion into the reactor riser at high flow rate is maintained so that the liquid is substan-tially instantaneous vaporized. Coking of the feed nozzle is thus avoided without requiring assistance of steam or water flow therearound. Generation of misted hydrocarbon particles without steam or water substan-tially improves the economics of processing the resul-ting fluidized catalyting cracking products distilled from the evolved vapors by reducing sour (acid) water disposal.
Coking in the feed nozzle is avoided by maintaining high liquid velocities in the nozzle. The large open area of the ports and exit orifice minimize the opportunity for physical plugging of the nozzle by coke or other foreign materials. Short straight cylindrical flow from the orifice allows the nozzle to be recessed out of the flowing catalyst stream. This keeps the nozzle cooler and minimizes mechanical ero-sion of the nozzle by the heated catalyst.
Coking in the feed nozzle is avoided by maintaining high liquid velocities in the nozzle. The large open area of the ports and exit orifice minimize the opportunity for physical plugging of the nozzle by coke or other foreign materials. Short straight cylindrical flow from the orifice allows the nozzle to be recessed out of the flowing catalyst stream. This keeps the nozzle cooler and minimizes mechanical ero-sion of the nozzle by the heated catalyst.
Description
~233~25;
METIIOD AND APPARATUS FOR LIQUID FEUD DISPERSION L
IN FLtJID CATALYTIC CRACI~ING SYSTEMS
I___ _ Field of the Invention _ The present inventlon re1ates to fluid cata-lytic cracking of hydrocarbons. More particulary lt relates to an improved method of dispersing feed of liquid hydrocarbons into a stream of heated catalyst particles in a riser reac-tor to promote ca-taly-tic action between the hot catalyst particle surfaces and finely divided liquia drops.
It is a particular objec-t of the invention f to assure that finely divided hydrocarbon liquid drops directly contact hot catalyst particle surfaces rather than a liquid surface or gas evolving from liquid on 15 the catalyst. Such contact between liquid drops and hot catalyst is promoted by disposing at least one mist generating hydrocarbon spray nozzle for discharge into the riser reactor. In accordance with this ff.
invention, the misting nozzle includes a swirl or F~
centrifugal chamber directly adjacent an orifice hav-ing a full flow area whose diameter is substantially f' smaller than the diameter and area of the swirl cham-ber or the hydrocarbon liquid feed line connected to it. Desirably at least a pair of vanes having a pitch 25 of at least 20 to the axes of the feed line and cham- !
ber initiate swirl or centrifugal rotation to the flowing liquid as it enters the chamb3r and there is no obstruction to flow therethrough except for the reduced diame-ter of the orifice through which the entire feed is misted in-to the riser reactor. The orifice area is preferably substantially equal to the area for 10w througil the vanes. Preferably, a plur-ality oE such nozzles are equally spaced circulneren v ' .
.
, ~233~5
METIIOD AND APPARATUS FOR LIQUID FEUD DISPERSION L
IN FLtJID CATALYTIC CRACI~ING SYSTEMS
I___ _ Field of the Invention _ The present inventlon re1ates to fluid cata-lytic cracking of hydrocarbons. More particulary lt relates to an improved method of dispersing feed of liquid hydrocarbons into a stream of heated catalyst particles in a riser reac-tor to promote ca-taly-tic action between the hot catalyst particle surfaces and finely divided liquia drops.
It is a particular objec-t of the invention f to assure that finely divided hydrocarbon liquid drops directly contact hot catalyst particle surfaces rather than a liquid surface or gas evolving from liquid on 15 the catalyst. Such contact between liquid drops and hot catalyst is promoted by disposing at least one mist generating hydrocarbon spray nozzle for discharge into the riser reactor. In accordance with this ff.
invention, the misting nozzle includes a swirl or F~
centrifugal chamber directly adjacent an orifice hav-ing a full flow area whose diameter is substantially f' smaller than the diameter and area of the swirl cham-ber or the hydrocarbon liquid feed line connected to it. Desirably at least a pair of vanes having a pitch 25 of at least 20 to the axes of the feed line and cham- !
ber initiate swirl or centrifugal rotation to the flowing liquid as it enters the chamb3r and there is no obstruction to flow therethrough except for the reduced diame-ter of the orifice through which the entire feed is misted in-to the riser reactor. The orifice area is preferably substantially equal to the area for 10w througil the vanes. Preferably, a plur-ality oE such nozzles are equally spaced circulneren v ' .
.
, ~233~5
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t.ially around -the riser reactor and are retracted suf:Eicientl.y from the catalyst flow area to prevent bo-th ero.sion of the nozzles ancl direct hea-tiny by the hot cata:lys-t. ~lowever, such retractlon within the 5 wall of the riser reactor ls only enough 50 that the walL does no-t interfere with liquid flow from the orifice into the catalyst s-tream or break up o:E -the stream in-to finely divided liquid par-ticl.es forming the desired mist. because such finely divided drop-10 lets are more rapidly vaporized from liquid to gas by direct con-tact with the heated catalyst particles, catalytic reactions of gas and catalyst surface are w favored, rather than thermal decomposition of the hydrocarbons. Such catalytic reaction to mid-range 15 hydrocarbon product is favored because the catalyst-hydrocarbon interaction, particularly one using zeo-lite containing catalyst, is primarily a gas-phase cracking process. In contrast, a liquid-hydrocarbon and catalyst reaction is primarily thermal cracking 20 which favors gas and coke production. Thus, more i-economically attractive mid range (boiling point) hydrocarbons, pentanes and hither molecular weight i liquids, are produced. Further such increase in de-sirable hydrocarbons is without significant increase 25 in "coke" make on spent catalyst since -the small drop-lets of feed are more fully vaporized for catalytic conversion and less liquid remains on the catalyst particles when -they are separated from overhead vapor after discharge from the riser reactorO
__,_ ", .. I__ _ ,' , '
t.ially around -the riser reactor and are retracted suf:Eicientl.y from the catalyst flow area to prevent bo-th ero.sion of the nozzles ancl direct hea-tiny by the hot cata:lys-t. ~lowever, such retractlon within the 5 wall of the riser reactor ls only enough 50 that the walL does no-t interfere with liquid flow from the orifice into the catalyst s-tream or break up o:E -the stream in-to finely divided liquid par-ticl.es forming the desired mist. because such finely divided drop-10 lets are more rapidly vaporized from liquid to gas by direct con-tact with the heated catalyst particles, catalytic reactions of gas and catalyst surface are w favored, rather than thermal decomposition of the hydrocarbons. Such catalytic reaction to mid-range 15 hydrocarbon product is favored because the catalyst-hydrocarbon interaction, particularly one using zeo-lite containing catalyst, is primarily a gas-phase cracking process. In contrast, a liquid-hydrocarbon and catalyst reaction is primarily thermal cracking 20 which favors gas and coke production. Thus, more i-economically attractive mid range (boiling point) hydrocarbons, pentanes and hither molecular weight i liquids, are produced. Further such increase in de-sirable hydrocarbons is without significant increase 25 in "coke" make on spent catalyst since -the small drop-lets of feed are more fully vaporized for catalytic conversion and less liquid remains on the catalyst particles when -they are separated from overhead vapor after discharge from the riser reactorO
__,_ ", .. I__ _ ,' , '
3~
t background of the Invention Description of the Prior Art Fluidized catalytic crackiny of heavy petro-leum fractions is one o:E the major refining methods to 5 convert crude or partially refined petroleum oil to useful products, such as fuels for internal combustion engines and heating oils. In such fluidized catalytic cracking, (known popularly as "FCC") high molecular weight hydrocarbon liquids are contacted with hot, lO finely divided solid catalyst particles in an elon-gated riser or transfer line reactor. The reactor is l;
usually in the form of a riser tube and the contact rtime of the material is on the order of a few seconds, say one to ten seconds, and generally no-t over about 15 three seconds. This short contact time is necessary to optimize generation of gasoline and mlddle distil-late fractions. By proper selection of temperatures and reaction times the catalytic cracking reac-tion is "quenched" so that economically undesirable end pro-20 ducts of such a reactlon, methane and carbon, are held to a minimum, and yield of desired products, gasoline-and middle distillate oils, is at a maximum. During this short reaction period a hydrocarbon feed stock, fre~uen-tly in the form of vacuum gas oil, cycle oil or 25 the like, at an initial tem~era-ture of from about 300F to ~00F, is sprayed onto catalyst at tempera-tures in the range of abou-t 1100F to 1400E`. The -present invention, as no-ted ahove is particularly directed.to a sys-tem of uniformly mis-ting such feed ,~
onto the hot catalyst.
Generally the mixture is fluidized by steal!l and the hydrocarbon gases evolved by the llydrocarbona-ceous feecl vaporizirlg upon contact with the hot ca-ta-,.
I.
~33~12S
_4_ lys-t. Reac-t:ion of the mixture is one of essentially L
instantaneous genera-tion of :Large volumes of yaseous hydrocarbons. The hydrocarbon vapors and catalyst mixture flow out of the riser tube into a separator or 5 disengaging vessel. The spent ca-talyst is separa-ted, r primarily by gravity and inertia forces acting on the catalyst in the separator vessel, and passed down wardly through a stripper section for return -to a regenerator. Fluidizing steam also generally flows up 10 through the down-flowing catalyst to assist in strip-ping hydrocarbon vapor from the spent catalyst. Heat -.
for the process is obtained by burning the coke, pri-marily carbon, on the spent catalyst by flowing oxygen '`
through a bed of spent catalyst in a regenerator ves-15 sel. The regenera-ted and heated catalyst is then recirculated to -the riser reactor. The desired pro-duct, hydrocarbon vapor, is recovered overhead from the separator vessel. GeneralIy, this recovery is I;
through one or more cyclone separators connected to a 20 plenum chamber or common piping and directly piped to a distillation column. Vapor flow through -the cyclone separa-tors extracts residual or entrained catalyst fines. The catalys-t fines are recovered from the cyclone separators through "dip legs" connec-ted to the 25 stripper, at the bottom or below the disengaging ves-sel, for return to the regenerator.
A particular problem in the ini-tial genera-tion of hydrocarbon vapor is that if the hydrocarbon liquid does not directly contact catalyst upon injec-30 tion into the reactor riser, thermal cracking appears r to be favored over the catalytic reaction. Such ther-mal cracking tends to generate end products of methane and coke. That is, complete conversion of hydrocar-bons in the weed pro-luces gas and coke, rather than .. . .
I.
_ . .. . .. _. . .. .. . _.. _ . _ .. , I.. ___ _ . _ . _ ._ . .. ... _ .. .. ... _ . . .. , _ . _ _._ _ . _ _ .. , .. .. . _ ,.. _ . _. ... __ . _ . _. . ... .. _~
,
t background of the Invention Description of the Prior Art Fluidized catalytic crackiny of heavy petro-leum fractions is one o:E the major refining methods to 5 convert crude or partially refined petroleum oil to useful products, such as fuels for internal combustion engines and heating oils. In such fluidized catalytic cracking, (known popularly as "FCC") high molecular weight hydrocarbon liquids are contacted with hot, lO finely divided solid catalyst particles in an elon-gated riser or transfer line reactor. The reactor is l;
usually in the form of a riser tube and the contact rtime of the material is on the order of a few seconds, say one to ten seconds, and generally no-t over about 15 three seconds. This short contact time is necessary to optimize generation of gasoline and mlddle distil-late fractions. By proper selection of temperatures and reaction times the catalytic cracking reac-tion is "quenched" so that economically undesirable end pro-20 ducts of such a reactlon, methane and carbon, are held to a minimum, and yield of desired products, gasoline-and middle distillate oils, is at a maximum. During this short reaction period a hydrocarbon feed stock, fre~uen-tly in the form of vacuum gas oil, cycle oil or 25 the like, at an initial tem~era-ture of from about 300F to ~00F, is sprayed onto catalyst at tempera-tures in the range of abou-t 1100F to 1400E`. The -present invention, as no-ted ahove is particularly directed.to a sys-tem of uniformly mis-ting such feed ,~
onto the hot catalyst.
Generally the mixture is fluidized by steal!l and the hydrocarbon gases evolved by the llydrocarbona-ceous feecl vaporizirlg upon contact with the hot ca-ta-,.
I.
~33~12S
_4_ lys-t. Reac-t:ion of the mixture is one of essentially L
instantaneous genera-tion of :Large volumes of yaseous hydrocarbons. The hydrocarbon vapors and catalyst mixture flow out of the riser tube into a separator or 5 disengaging vessel. The spent ca-talyst is separa-ted, r primarily by gravity and inertia forces acting on the catalyst in the separator vessel, and passed down wardly through a stripper section for return -to a regenerator. Fluidizing steam also generally flows up 10 through the down-flowing catalyst to assist in strip-ping hydrocarbon vapor from the spent catalyst. Heat -.
for the process is obtained by burning the coke, pri-marily carbon, on the spent catalyst by flowing oxygen '`
through a bed of spent catalyst in a regenerator ves-15 sel. The regenera-ted and heated catalyst is then recirculated to -the riser reactor. The desired pro-duct, hydrocarbon vapor, is recovered overhead from the separator vessel. GeneralIy, this recovery is I;
through one or more cyclone separators connected to a 20 plenum chamber or common piping and directly piped to a distillation column. Vapor flow through -the cyclone separa-tors extracts residual or entrained catalyst fines. The catalys-t fines are recovered from the cyclone separators through "dip legs" connec-ted to the 25 stripper, at the bottom or below the disengaging ves-sel, for return to the regenerator.
A particular problem in the ini-tial genera-tion of hydrocarbon vapor is that if the hydrocarbon liquid does not directly contact catalyst upon injec-30 tion into the reactor riser, thermal cracking appears r to be favored over the catalytic reaction. Such ther-mal cracking tends to generate end products of methane and coke. That is, complete conversion of hydrocar-bons in the weed pro-luces gas and coke, rather than .. . .
I.
_ . .. . .. _. . .. .. . _.. _ . _ .. , I.. ___ _ . _ . _ ._ . .. ... _ .. .. ... _ . . .. , _ . _ _._ _ . _ _ .. , .. .. . _ ,.. _ . _. ... __ . _ . _. . ... .. _~
,
4 ~,~9~
~5 ~5--middle distilla-te hydrocarhorls. Prolonge-l contact Oc the unvaporized licIuid hydrocarbons with catalyst after discharge into a separation vessel may result in further thermal cracking which tends to favor such end reactions particularly at high velocities. Further, it is essential to such catalytic cracking that hydro-carbon vapor contacts the catalyst because such reac-tion is primarily a vapor phase reaction.
While it has been proposed heretofore to use misting or fine droplet nozzles in the riser reactor pipe, in general such fine dispersions have been ob-tained by the use of steam or other vaporizing mater-ials which forms a two phase fluid. A particular problem with such two-phase fluids is that in general they produce a higher pressure drop through the spray nozzles than either fluid phase alone. This is impor-tant because pressure drop across the nozzle unit for a given size nozzle and a given rate of feed has a significant influence on the size of droplets that can ye formed by the nozzle. It is oL course also unde-sirable to add additional steam to the hydrocarbon feed. Such added steam must be recoverecl in the ovcr-head distillation column and generally creates a "sour" water disposal problem, because oxides of sul-fur, nitrogen, and carbon in the recovered hydrocarbonvapors combine with the water to form acids. In spite of such problems, steam has been used heretofore pri-marily because it reduces the hydrocarbon partial pressure and accordingly reduces resistance to vapori-zation of the feed stream by the catalyst.
U.S. Patent 3,152,065 Sharp et al, U.S.Patent 3,812,029 Snyder, U.S. Patent 3,654,1~0 Griff-l et al, and U.S. Patent 3,071,5~0 McMahon et al are examples of feed nozzles for fluid catalytic crac~iincJ
~;~33~2~i En systems in which steam or water is concurrently injec-ted with -the hydrocarbon feed through an annuLar area surrounding the hydrocarbon feed nozzle. These patents indicate the advantages of using a "shroud" of steam around a nozzle disposed directly in the riser reactor for spraying hydrocarbon feed into the cata- I:
l~s-t flow stream. In Sharp et al, s-team is swirled by spiral vanes around a straight flow pipe for hydrocar-bon liquid opening in-to a mixing charnber before release of the mixture through an orifice to improve misting of toe hydrocarbon feed. The nozzle is posi- -tioned in the catalyst flow stream. The patentees also disclose interchange of the liquid and gas flow through the concen-tric nozzle, so that steam flows 15 through the center and liquid is swirled around the steam for mixing and release of the mixture. The Snyder et al patent discloses hydrocarbon feed flow through a surrounding water nozzle which concurrently cools the feed nozzle to prevent coking and disperses 20 the mixture of water and feed into finer droplets.
GriffeI et al disclose the use of a venturi in the supply line to act as a nozzle disposed in the riser reactor for combined steam and hydrocarbon feed flow. Alternatively, the patentees disclose a spiral 25 member in the hydrocarbon feed nozzle itself and a surrounding flow of steam to induce breakup of the flowing hydrocarbon feed to droplets. 7 In -the arrangement shown by McMahon et al, - steam and hydrocarbon liquid are fed concentrically 30 through a nozzle arrangement. This is similar -to appara-tus disclosed hy Snyder for concurrent water and hydrocarbon liquid. The concentric nozzles are positioned in the center of the riser reactor with annular flow of catalyst particles around -the 35 nozzles.
I. _ ,""_ _ . . , .. . ., .. . . ., . . . ... _._ _ ___ _ __ __,__..... , .. _ .. , , ' , , t t, ~3~
.S. Patent 4,097,2~3 to Bartho1ic discloses a hydrocarbon feed dis-tributor in which a divergent conical header supplies a center nozzle and a plural-lty of surroun~lng divergen-t nozzles. The feed dis-tribu-tor or header is disposed in the cen-ter of a riser reactor with catalyst flow around the nozzle. I' .S. Patent 3,848,811 Fryhack discloses a fluid discharge nozzle for injecting hydrocarbon feed into the riser reactor as a plurality of discreet concentric streams. A plurality of circumerentially spaced holes diverge outwardly relative to the ;--direction of flow through the nozzle, as do a pair of frusto-conical members arranged in line with the I-direction of flow. One of the frusto-conical members includes adclitional port members so tha-t in general feed is sprayed from a multiplicity of nozzles all directed generally outwardly and upwardly from the nozzle into the riser pipe. The nozzle is positioned in the center of the riser reactor to contac-t catalyst flowing downwardly over the nozzle, with steam flowing upwardly with catalyst around the nozzle.
Brief Summary of the Invention As particulary dis-tinguished from the noz-zles for feeding hydrocarbon fluids into a riser pipe shown in the above noted patents, it is a particular object of the present invention to assure tllat sub-stantially all hydraulic energy of the hydrocarbon feed is used in a single flow passage to disperse the feed stream into mist size droplets without two phase pressure drop through the nozzle or by concurrently flowing a stream of steam or water through the nozzle or by multiple flow passages. Suet droplet size per-~;~33~;~5 mi-ts almosk instantaneous vaporiza-tion of the liquid hydrocarbon droplets hy the hot ca-talyst partieles in the riser so that gas phase catalytic reac-tions, pri-marily Favoriny middle distillate, or low boiling
~5 ~5--middle distilla-te hydrocarhorls. Prolonge-l contact Oc the unvaporized licIuid hydrocarbons with catalyst after discharge into a separation vessel may result in further thermal cracking which tends to favor such end reactions particularly at high velocities. Further, it is essential to such catalytic cracking that hydro-carbon vapor contacts the catalyst because such reac-tion is primarily a vapor phase reaction.
While it has been proposed heretofore to use misting or fine droplet nozzles in the riser reactor pipe, in general such fine dispersions have been ob-tained by the use of steam or other vaporizing mater-ials which forms a two phase fluid. A particular problem with such two-phase fluids is that in general they produce a higher pressure drop through the spray nozzles than either fluid phase alone. This is impor-tant because pressure drop across the nozzle unit for a given size nozzle and a given rate of feed has a significant influence on the size of droplets that can ye formed by the nozzle. It is oL course also unde-sirable to add additional steam to the hydrocarbon feed. Such added steam must be recoverecl in the ovcr-head distillation column and generally creates a "sour" water disposal problem, because oxides of sul-fur, nitrogen, and carbon in the recovered hydrocarbonvapors combine with the water to form acids. In spite of such problems, steam has been used heretofore pri-marily because it reduces the hydrocarbon partial pressure and accordingly reduces resistance to vapori-zation of the feed stream by the catalyst.
U.S. Patent 3,152,065 Sharp et al, U.S.Patent 3,812,029 Snyder, U.S. Patent 3,654,1~0 Griff-l et al, and U.S. Patent 3,071,5~0 McMahon et al are examples of feed nozzles for fluid catalytic crac~iincJ
~;~33~2~i En systems in which steam or water is concurrently injec-ted with -the hydrocarbon feed through an annuLar area surrounding the hydrocarbon feed nozzle. These patents indicate the advantages of using a "shroud" of steam around a nozzle disposed directly in the riser reactor for spraying hydrocarbon feed into the cata- I:
l~s-t flow stream. In Sharp et al, s-team is swirled by spiral vanes around a straight flow pipe for hydrocar-bon liquid opening in-to a mixing charnber before release of the mixture through an orifice to improve misting of toe hydrocarbon feed. The nozzle is posi- -tioned in the catalyst flow stream. The patentees also disclose interchange of the liquid and gas flow through the concen-tric nozzle, so that steam flows 15 through the center and liquid is swirled around the steam for mixing and release of the mixture. The Snyder et al patent discloses hydrocarbon feed flow through a surrounding water nozzle which concurrently cools the feed nozzle to prevent coking and disperses 20 the mixture of water and feed into finer droplets.
GriffeI et al disclose the use of a venturi in the supply line to act as a nozzle disposed in the riser reactor for combined steam and hydrocarbon feed flow. Alternatively, the patentees disclose a spiral 25 member in the hydrocarbon feed nozzle itself and a surrounding flow of steam to induce breakup of the flowing hydrocarbon feed to droplets. 7 In -the arrangement shown by McMahon et al, - steam and hydrocarbon liquid are fed concentrically 30 through a nozzle arrangement. This is similar -to appara-tus disclosed hy Snyder for concurrent water and hydrocarbon liquid. The concentric nozzles are positioned in the center of the riser reactor with annular flow of catalyst particles around -the 35 nozzles.
I. _ ,""_ _ . . , .. . ., .. . . ., . . . ... _._ _ ___ _ __ __,__..... , .. _ .. , , ' , , t t, ~3~
.S. Patent 4,097,2~3 to Bartho1ic discloses a hydrocarbon feed dis-tributor in which a divergent conical header supplies a center nozzle and a plural-lty of surroun~lng divergen-t nozzles. The feed dis-tribu-tor or header is disposed in the cen-ter of a riser reactor with catalyst flow around the nozzle. I' .S. Patent 3,848,811 Fryhack discloses a fluid discharge nozzle for injecting hydrocarbon feed into the riser reactor as a plurality of discreet concentric streams. A plurality of circumerentially spaced holes diverge outwardly relative to the ;--direction of flow through the nozzle, as do a pair of frusto-conical members arranged in line with the I-direction of flow. One of the frusto-conical members includes adclitional port members so tha-t in general feed is sprayed from a multiplicity of nozzles all directed generally outwardly and upwardly from the nozzle into the riser pipe. The nozzle is positioned in the center of the riser reactor to contac-t catalyst flowing downwardly over the nozzle, with steam flowing upwardly with catalyst around the nozzle.
Brief Summary of the Invention As particulary dis-tinguished from the noz-zles for feeding hydrocarbon fluids into a riser pipe shown in the above noted patents, it is a particular object of the present invention to assure tllat sub-stantially all hydraulic energy of the hydrocarbon feed is used in a single flow passage to disperse the feed stream into mist size droplets without two phase pressure drop through the nozzle or by concurrently flowing a stream of steam or water through the nozzle or by multiple flow passages. Suet droplet size per-~;~33~;~5 mi-ts almosk instantaneous vaporiza-tion of the liquid hydrocarbon droplets hy the hot ca-talyst partieles in the riser so that gas phase catalytic reac-tions, pri-marily Favoriny middle distillate, or low boiling
5 point hydrocarbon liquids, are produced by the inter- , action. In accordance with the present invention it has been found that misting of a single feed stream may be accompIished by passing the liquid stream through deflection vanes in-to a single full-flow cen-trifugal or helical acceleration chamber which termi-nates in an orifice of substantially smaller diameter for feeding the liquid hydroearbons direetly into the I-eatalyst -Elow stream in the riser reactor. Such an arrangemen-t of centrifugal chamber and orifice is partieulary effective for dispersing the hydrocarbon feed into mist size droplets. To inerease further both diffusion and the spray angle of the misted par-ticles into the catalyst, the area of the orifice opening is made substantially equal to the open areas through the throat of the vanes creating the helical flow. Both are substantially smaller than the cross sectional area of -the feed stream line supplying such it liquid flow and the area of the centrifugal or helical acceleration ehamber. The vane members indueing sueh helical or centrifugal rotation of the stream prior to release through reduced area orifice are disposed at a shallow angle to the flow axis -to create as little pressure drop as possible in the feed line and through -the orifice.
In a preferred form, the cylindrical or helicaL swirl chamber and the exit orifice are axialLy aligned wi-th the hydrocarbon feed line so that as little pressure clrop as possible is experienced by fluid flowing through -the no7zle. Desirably, the .
t .
~33~
ori:Eice exit throat i5 substantially shorter than the length of -the centrifugal swirl chamber. Thus, substantially all hydrau-lic energy in the Elowing fluid is converted to dispersion or misting of the droplets.
The large open areas throuyh the swirling vanes and exit orifices are also an advantage relative to previous nozzle designs because they minimize plugging problems in the nozzle, particularly with the nozzle recessed within the wall of the riser reactor sufficiently to avoid abrasion and direct heating of the nozzle by hot catalysts flowing over it, but without interference wi-th the mistiny or break-up flow pattern from the orifice. In a preferred form of the invention a plurality of nozzles are equally distributed around the circumference of a transi.tion section of the riser reactor where catalyst flow be-comes a mixture of catalyst and hydrocarbonaceous material.
Thus in a first embodiment this invention provides a fluid catalytic hydrocarbon cracking system wherein heated catalyst is circulated through a riser reactor tube for contact with a liquid hydrocarbon feed, with or without water or steam to improve atomization and/or vaporization by reducing hydro-carbon partial pressure of said feed, which comprises: intro-ducing said feed as a single liquid phase into said riser reactor tube to contact a stream of heated catalyst flowing therethrough by first imparting centrifugal rotation to said single phase liquid feed about its axis of flow, said centri-fugal rotation being imparted by flow of said liquid phase through a cylindrical chamber positioned in line with and as a cylindrical extension of a conduit supplyln~ said feed to said riser reactor, and then passing said single phase fluid feed durlng sa:i.d :rotati.on -through an ori:Eice recessed suf:EI.ci.ently ~23~
- 9a - 193~-1587 within an opening in a side wall of said riser reactor tube to malntain said cylindrical chamber and said orifice out of said stream of heated catalyst, said orifice having a diameter less than the diameter of said ehamber and having a throat substan-tially shorter than the length of said chamber, and maintaining the hydraulic pressure of said liquid phase feed flowing through said supply line to retain a eylindrical form during free flow of said liquid phase from said orifice through said opening in said reactor side wall and into said reactor tube before dis-persion of said feed into a uniform mist of liquid drops o'er a uniform conical volume for contact with said stream of heated catalyst particles flowing in said reactor riser.
In a seeond embodiment this invention provides a method of deereasing the residenee time of hydrocarbon liquid on heated catalyst to increase the initial yield of cracked hydrocarbon product and to decrease secondary cracking and coke lay-down by residual hydrocarbonsadhering to catalyst after initial hydrocarbon liquid contact therewith in a fluid cata-lytic hydrocarbon processing system which comprises: contacting a flowing stream of hea-ted hydrocarbon catalytic cracking par-ticles with a uniform spray of single phase hydrocarbonaceous fluid particles, said single phase fluid particles being created by positioning a nozzle having a eentrifugal aeceleration cham-ber between the hydrocarbon fluid feed line and a lateral open-ing into the flow path of said stream of heated eatalyst partieles through the side wall of a reactor riser in sald processing system, said acceleration ehamber being an in-line, solid cylinder axial extension of said single phase fluid feed li.ne and having an exit orifice formed in the end wal.l o:E saicl chamber, saicl exlt orifice being disposed within saicl riser - 9b - 1936-1587 side wall and adjacent to said opening into said reactor riser and the flow passage through said orifice having an area substan~
tially smaller than the cross-sectional area of said chamber r said nozzle including at least a pair of vanes between said hydrocarbon feed line and said centrifugal chamber, the flow passages through said vanes having a combined area substantially equal to said orifice area, said orifice being recessed in said opening sufficiently so that said fluid feed is delivered as an unrestrained and undispersed fluid flow stream through said sidewall opening for contact with said flowing stream of heated catalyst and then forms a break-up pattern over a wide-angle conical volume for contact with said heated catalyst stream as a mist of liquid particles to improve production of low boiling range hydrocarbon fluids and to reduce conversion of said hydro-carbon fluids to both gas and coke.
In a third embodiment this invention provides apparatus for improving the rate of reaction of a hydrocarbon liquid with a heated fluidized catalyst in a fluid catalytic hydrocarbon cracking system which comprises: disposing at least one nozzle unit for spraying a feed of liquid hydrocarbons into the reactor riser of the fluid catalytic hydrocarbon cracking system; said nozzle unit being recessed within a wall of said reactor riser and having a cylindrical swirl chamber positioned between a liquid hydrocarbon feed conduit and the exit orifice from said chamber, stationary vane members between said feed line and said chamber for i.mparting centrifugal ro-tation to said liquid relative to the flow axis through said orifice and said chamber, said exit orifice being smaller in diameter and sub.stant:lally shorter in length than said swirl chamber, and both sald or:l:Eice and sa:Ld chamber be:Lng open Eor Eull flow - 9c 1936-1587 throughout the full cylindrical volumes thereof.
In a fourth embodiment this invention provides a fluid catalyti.c hydrocarbon cracking system wherein hot catalyst is circulated through a riser reactor tube for contact with a liquid hydrocarbon feed, with or without water or steam incor-porated therein to assist atomization and/or vaporization of said liquid hydrocarbon by reducing the partial pressure of the resultant single phase liquid stream, which cornprises: prior to introducing a single phase stream of liquid hydrocarbonaceous Lo materials into a riser reactor tube having a stream of heated catalyst particles flowing therethrough imparting to said single phase liquid stream centrifugal rotation about its own axis of flow, said centrifugal rotation being generated in a cylindrical chamber formed as a solid cylindrical extension of the feed line of said single phase liquid stream, said chamber being recessed within a sidewall of said riser reactor, and then pass-ing the rotating liquid stream through an end wall of said chamber having an orifice formed therein, said orifice being positioned adjacent to but within an opening into said riser reactor tube, said orifice having a diameter less than the dia-meter of said chamber and having a throat substantially shorter than the length of said chamfer, and controlling the hydraulic pressure ox said single phase liquid stream flowing through the supply line to said centrifugal chamfer to maintain the in-tegrity of said liquid stream flowing from said orifice through at least said reactor sidewall opening so that said liquid stream is converted to a conical dispersion of single phase liquid par-tlcles after passage into said stream of heated ca-talyst partlcles.
In a fifth ernbod:lment this invention provldes a ~33~5 - 9d - 1936-1587 method of introducing a single phase hydrccarbonaceous feed in-to a stream oE heated catalyst particles Elowing in a reactor tube of a fluid catalytic cracking system without abrasion of or coke build up on the nozzle system for said feed which com-prises forming said single phase feed as a :Eluid mixture of a liquid hydrocarbon and steam in a single flow line, passing said flow through at least a pair of turning vanes under sufficient hydraulic pressure to generate significant axial rotation of said feed about its own flow axis in said line and without sub-stantial increase in the cross-sectional area of said flow line, and then passing said single phase liquid feed during said rotation through an orifice recess sufficiently within an open-ing in a sidewall of said reactor tube to recess said orifice out of said stream of heated catalyst particles, and maintaining said hydraulic pressure of said single phase feed adequate to retain substantially the diameter of said orifice in the feed stream during free flow thereof from said orifice through said opening in said reactor tube sidewall and into said reactor tube before dispersion of said feed into a uniform conical volume of disperse particles for contact with said stream of heated cata-lyst particles.
Further objects and advantages of the present inven-tion will become apparent from the following detailed description taken in conjunction with the accompanying drawings which form a integral part of the present specification.
Brief Description of the Drawings Figure 1 is an elevation v:iew o:E a lower portion of a fLuid catalytic cracking system to which the feed nozz:Le sys-tem of the present :lnvention has been applied and generally :in-d:Lcates a r:Lser reactor to wh:Lch heatecl cata:Lyst :Ls supp.l:Led ~3~
- 9e - 1936-1587 from a regenerator and the return line for spent catalyst flowing from the separator vessel back to the regenerator.
Figure 2 is a cross-sectional view taken in the direction of arrows 2 - 2 in E'igure 1 which lllus-~;~;33~ 5 --10-- r I;
trates an arrangement of a plurality of feed nozzles constructed in accordance with the present invention for flow,ing hydrocarbon feed from a circular header to a plurality of misting,nozzles dis-tributeA around a 5 riser reactor.
Figure 3 is a cross-sectional view of one " suitable form of nozzle constructed in accordance with the inven-tion for assuring full flow of hydrocarbon feed as a mist into the riser reactor from within the lO side wall oE the fluidized catalyst flow line, taken in the direction of arrows 3-3 through one of the noz-zles shown in Figure 2.
Figure 4 is a cross sectional view taken in _ the direction of arrows 4-~ in Figure 3 particularly 15 illustrating the vane members inducing centri-Eugal or helical motion to flow of the hydrocarboll feed as i-t enters the centrifugal chamber and which directly supplies feed to catalyst through the reduced diameter orifice of -the nozzle.
20 Description of Preferred embodiments of the Invention Referring now to -the drawings and in parti- I, cular Figure l, there is shown a portion of a flui-dized catalytic cracking unit to which the present invention has been applied. The sys-tem generally 'I
25 cornprises a riser reactor pipe lO in which heated catalyst, supplied from regenerator 12 is reacted with liquid hydrocarbons. Catalyst flows from regenerator 12 to pipe lO through U-tube 14. Catalyst is par- s,~
tially fluidized in U-tube 14 by gas, preferably 30 steam, supplied by a series of nozzle rings 13 along - the length of U-tube 14. I'he steam entrains and par tially fluidizes catalyst particles suppLiecl by gra-vity from intake 15 in regenerator 12 and conveys them to riser pipe lO.
' .. ; .
o r I
~233 ~2S
A stream of hydrocarbon liquid is supplied to riser pipe 10 by line 21 under control of valve 22. As indicated in Figure 2, line 21 may supply a ring of feed nozzles 20 con-nected to a annular header 23. Because the catalyst particles are on the order of 20 to 120 microns in diameter it is impor--tant what liquid feed from line 21 and header 23 be as evenly distributed as possible and in proper droplet size for intimate contact and substantially instantaneous vaporization ox the liquid droplets. This is essential because the vapor-phase catalytic reaction time to generate desired low boiling range liquids by contact between hot catalyst particles and hydrocar-bon liquid droplets is on the order of 1 to 10 seconds; more properly, a reaction time range of 1 to 3 seconds and frequent-ly about 1 second, is required for optimum catalytic reaction to generate middle distillate hydrocarbons rather than to gas or coke.
Substantially instantaneous reaction o-E misted hydro-carbon droplets with heated catalyst particles generates large volumes of hydrocarbon vapor which primarily fluidize and carry the mixture upwardly in reactor 10 for prompt discharge and separation in separator vessel 24. The reacted hydrocarbon vapor and catalyst are separated in the upper portion of vessel 2~ in the manner described in copending Canadian applications Serial No. 395,902; 407,150 and 415,510. These applications describe overall structures and arrangements of suitable fluid catalytic cracking systems to which the present invention may be appliecl, and particularly the misting feed nozzle system herein disclosed and claimed. As disclosed in said applica-~33~5 tions, the catalyst is released or discharged from riser 10 and by inertia and gravity ef-fect the catalyst is separated from -the vapor. The spent catalyst i5 recovered in a s-tripping section, indicated as 32, at or in -the lower end of vessel 24.
The generated vapor is recovered overhead and condensed in a distillation column (not shown).
Catalyst recovered in the separa-tion process contains a certain amount of residual hydrocarbons in the form of coke primarily carbon' adhering to the spent catalyst. Such carbon, or coke laden spent catalyst is returned to regenerator 12 through stripper means 32. Residual hydrocarbon vapor is removed from the spent catalyst in stripper 32 by introduction of steam, such as by line 3'1, feeding nozzles 35 at the lower end of stripper 32. Stripper 32 generally includes a plurality of baffles or sheds (not shown) to prolong residence time of the spent catalyst therein. Catalyst is assisted in returning to regenerator 12 by introduction of steam through a serles of nozzle rings 36 along return U-tube 38. Spent catalyst is regenerated by addition of oxygen as by line 40, to turn resi-dual coke, from the catalyst particles supported for oxidationon grid 42. This supplies heat to the catalyst that circulates in the system and returns to riser 10 from bed 47 through intake l Offgas -from the burned coke is vented from regener-ator 12 through cyclones and a 1ue pipe (not shown).
As noted above, the present invention is particularly concerned with a method of vaporizing the liquid hydrocarbon feed as rapidly as possible in riser reac-tor 10 so that the essential reaction of : L~339~2~
I, vaporized hydrocarbons in gas-phase wlth -the catalys-t partlcles, may proceed as the mixture flows through riser 10 i.n the alloted time of one -to -ten seconds, and mos-t preferably in the range of one to three 5 seconds.
For such short reaction times i-t is essen-` tial that all of the ]iqui.d feed be substantially P
instantaneously converted to gas to effect -the neces-sary catalys-t-gas phase reaction. Such reaction 10 cracks the heavier hydrocarbon molecules to the desired middle boiling range hydrocarbons. To achieve such prompt gasification the flow pattern of the liquid eed into the fluidized catalyst stream must be uniform both as to droplet size and distribution at 15 reasonable commercially available flow rates and pres- 'I
sures. Further, nozzles for creating such patterned flow must be capable of extended service without plug-ging (as hy formation of coke from the hot hydrocar-bons fl.owing through it) or mechanical wear (as by : 20 ab.rasion of the fluidized catalyst particles).
Whi.le as noted above, it has been proposed heretofore to use steam or water as the prirnary dis-persing fluid for atomizing the flow of hydrocarbon feed, we have found superior results, without addition 25 of steam,~can be obtained in accorclance with our invention, by use of a nozzle having a single swirl chamber, acting as a helical or centr:ifugal accelera-tion compartment, placed between the full flow liquid feed line and a reduced area orifice formed in the 30 discharge end of the swirl chamher. For this purpose, .
as shown in Figure 3, swirl chamber 51 is substan-tially the same diameter as the full bore of flow nozzle 20. Preferabl.y, nozzle 20 does not extend into the flow path of reactor riser 10, as in -transltion . i -- . .. .... _ . . ... _ .. .. .. .. . .... ... , _ . _ _, _ _ _ .. _ . _, .. _ . . , _ _, . _, , _, . _ _ _ . _,, _ _, _ l'h33925 : , . I, section 17, bu-t ls only sufficiently deep in wall 11 and insulation-abrasion layer 19 to insure full flow of the liquid stream, as indica-ted, wi-thout dispersion of the output through orifice 54 until the break-up pattern i5 well within the flow pat of catalyst, as in transition section 17. The pitch of vanes 53, the size and length of chamber 51 relative to the diame-ter I-and the depth or length of orifice 54 are selectecl to con-trol the angle of dispersion from nozzle 20 so that the break-up pattern creates properly sized droplets and occurs a short distance away from the orifice. In this way, the nozzle, including the orifice end, may be recessed within the reactor riser side wall so that the droplets will contact the flowing catalyst in riser 10 rather than the sidewalls thereof.
Fur-ther, i-t is importan-t to assure that virtually all hydraulic energy is available from the hydrocarbon feed through nozzle 20 to genera-te the j helical or centrifugal ac-tion on the feed to generate 20 the desired pattern of straight cylindrical flow hav- ;
ing a diameter substantially the same as -the orifice diameter for a short distance, say 1/2 to 2 inches, as I.
schematically indicated in Figure 3,and then full break-up of the stream into a wide angled conical mist-like spray of droplets. For such a flow pattern, a single pair of deflection vanes 53 are disposed -transverse and angled to the axis of flow through nozzle 20. Vanes 53, which generate the rotation or helical motion to liquid flowing therethrough, create such a pattern. These vanes may have a pitch of from I-15 to 45 to the axis of the feed line an<l chamber 51. Preferably, the pitch angle is from 25 to 35, and most preferably about 30. Wi-th vanes 53 so I.
.... . .
~3~25 angled, the two flow areas 52 may be made with a combined area substantially equal to the flow area of exit orifice 5~. This permits full pressure of the weed line to be applied to rota-Zion of the stream in chamber 51 and subsequent release of the liquid in the required pattern.
As indicated, swirl or centriEugal action is trans-verse and circular to the direction of flow and results in full rotation of the en-tire flow coming through the noz~]e prior to exit through the reduced diameter of the throat 55 oE orifice 54. While orifice 54 is shown as a single, circular or cylin-drical opening, the area may include various other configura-tions such as serrations in the cylindrical surface of throat 55 of end wall 56. As indicated, the length of throat surface 55 is only sufficiently long to form a solid flow for a short distance away -from orifice 54. Such distance is sufficient to permit recessing the nozzle in the side wall of riser pipe 10 including the erosion resistant coating without interference with the wide angle conical dispersion pattern. In practice the angle "A" ox the apex of such a conical or parabolic volume should be in excess of 90 and preferable about 120, as indi-ca-ted in Figure 3.
As indicated in Figure 2, nozzles 20 may be equally distributed around riser pipe 10. The number may be varied in accordance with the diameter and flow rate of catalyst there-through and may vary from 1 or 2 to a multiplicity, such as 6 as shown in Figure 2, or an even greater number, say 12 -to 15.
As shown, the angle of the nozzle axis is from 20 to 70 rela-tive to the axis of the riser reactor, and more desirable about 30 to 50, to assi.st in dispersion of the particles in the directiorl ox catalysl:-hy~rocarbon mixture Elow.
3~
,~, While i-t is conteMplated in the present invention that -the entire feed will be a hydrocarbon liquid, it is also expectecl that steam rnay be added directly to the feed liquid for the purpose of 5 reducing the partial pressure of hydrocarbon liquid after it enters riser pipe 10. However, it is essen- I, tial that such steam and hydrocarbon be mixed before the fluid is introAuced into nozæle 20 ancl the mix-ture rotated together in chamber 51 for dispersion by ori-fice 54. This assures miniMurn pressure drop through the nozzle so -that the mixture wi]l not significantly decrease the fulL flow at the highest available hydraulic pressure to atomize the hydrocarbon feed ~~
into liquid droplets to the desired fineness after break up of the stream from orifice 54. In this way, -the desired mist is formed in the riser so that such droplets are immediately and completely vaporized upon ; contact with the heated catalyst particles.
us noted before, the use of steam in the _-initial reaction of hydrocarbon fluids with the cata-lyst is generally undesirable in fluid ca-talytic cracking. This is because the steam passes overhead with the vapor recovered in vessel 24 and must be treatecl with -the condensed hydrocarbon product. Such condensa-tion results in a "sour" water disposal since any water soluble materials, and part:icularly oxides of sulfur, nitrogen and carbon, in the condensate result in an acidic water disposal problem. Further, the need to recover and dispose of "sour water" in the condensate results in loss of efficiency of the con-version process and is an added cost in operation of the system.
s used herein, it is contemplated that catalyst particles wilL be heated -to a telnperature oF
.. ,,_ . . .. . .. ... .. .. ... , . .. .. . . . . . . . _ . .__ _ .. _ _ .
.
~23342~i;
:Erom lOOODF to 1400F and preferably a-t a -temperature of about 1200F to 1300~F. ~hi:Le the present sys-tem will produce nearly instantaneous misti.ng and vapori-zation at hiyher -temperatures, say up to 1500, com-5 mercial catalytlc cracking sys-tems capable of such high temperature operation are not yet common. Dow- I-.. ever, the present invention is particularly suitable for such high tempera-ture operation, because in gen-eral, full flow of the hydrocarbon fluid is preserved 10 under what otherwise might be coking conditions in the nozzle. Such coking is particularly to be avoided to rmain-tain high flow rates -through the nozzles. Accor- ~~
dingly, problems of coking, avoided in prior ar-t devices by use ox a s-team shroud in a surrouncling 15 atmosphere or vice-versa, are solved by nozzles operating in accordance with the present invention to disperse the hydrocarbon feed into well dispersed, mist-like droplets.
In modern forms of fluid catalytic cracking, 20 typical catalys-t includes a combination of amorphous materials toge-ther with crystalline materials, such as : molecular sieves. The-predominant components of such .
cracking catalyst are silica and alumina in weight ratios of from abou-t loo to about 60o alumina in 25 silica. Various combinations of rare earth elements may also be present. Silica-magnesia and other mixed oxide catalyst may be used. The cata:Lyst used may include particles having a wide range of free settling rates. Commercially available, powdered cracking 30 catalyst have a particle size distrihu-tion from 60-90 weight i.n the ranye of 20-120 microns.
A particular advalltaye of fluiclized cata-lytic cracking is that a wide range ox hydrocarbon Eeedstocks may be processed in such a method. These ., I.
_v .~ ", -- .................................... ----. ... -- .. -- -- . , . -- --. ,, .. . .-- ,.. _., , _ _ _ _ _ __.
_,~, __, ,_, ., _ _ .. _ , _ ., _, _ _ .. __ .. I___.. , .. _ .. ... .. .. . _~ _.. .. .~ . . .. ~.~ .. I_ .. I. ._.. I. .__.. _.__ __~_____ I
. _~_ _~ _.. _.. .
_ .
~233~5 .
I, may include virgin petroleum distillates, residual petroleum fractlons, deasphalted oils, hydrocarbon oil and mixtures -thereoE. Other heavy petroleum hydro-carbon Eractions, that is, those having boiling points 5 of 600F ancl heavier, may be advantageously converted to lower boiling, more valuable, hydrocarbon pro-ducts. In such a reaction, the temperature o the P
feedstock in general will be from ambient temperatures to from 350F or 400E-'. While the feed may be 10 vaporized before release into the stream of ho-t regenerated catalyst particles flowing in the riser reactor, in general it is econornically preferable to vaporize the-hydrocarbon prirnarily by contact wi-th the hot catalyst. A wide range of catalyst to oil 15 feed/weight ra-tios may be used bu-t preferably the catalyst/oiL feed weight ratio is from about 2:1 to about 20:1 with a range of hydrocarborl/catalyst con-tact times in the range of 1 to about 10 seconds. and I, mos-t preferably from 1 to 3 seconds.
The full reasons that the present arrangement of a cylindrical swirl charnber and an orifice having both a reduced diameter and a short throat area is so effective in vaporizing the Eeed in the desired pattern is not fully unders-tood. However, i.t is believed that the mis-ting action of -the nozzle is achieved by vir-tue of fluid passing from axial flow to circular or centrifugal flow throu(3h passageways to the turning vanes having a small pres,ure drop there-through and a flow area about equal to the orifice area. Thus, full passage ox the en-tire spray Erom the swirl chamber through a rela-tively short orifice quickly forms a short cylinclrical flow section which then expancls over a large conical section. This pat-tern is not only effective to create proper sized _ t:
.... . , .-- . __. . _ . .
:~233~
. - 1 C3 _ . . - I.
droplets Eor rapid eonversion to gas by the eatalyst but most importantly permi-ts recessiny the nozzle in the riser sicle wall -to avoid both catalyst abrasion and direct heating by the hot catalyst. because of 5 the rapid expansion of the feed in-to finely divided particLes over a wide angle conical pattern, a highly ;
turbulen-t gas flow stream is created by the voluminous production of hydrocarbon vapor when the hot liquid droplets contaets the hot eatalyst. Preferably Elow 10 from the nozzle orifice into the catalys-t stream is a-t a point where the catalyst is slightly slowed by an increase in area from U-tube 14 in-to riser 10. Tran- I:
sition section 15 provides such an increasing eross-sectional area ancl aids in the sudden aeeeleration of 15 the feed and catalys-t mixture due to vapor evolution s from hydrocarbons reaeting with hot catalyst.
While the reason for such sudclen and more eomplete evolutiorl of desirable hydrocarbons is not jt fully unclers-tood, comparison of a eommereial Fluid _-; 20 eatalytie cracking sys-tem using conven-tional nozzles, where no particular effort was made to obtain a mist-ing spray, with a system of nozzles for vaporizing t feed in accordance with -the presen-t invention is par-ticularly impressive. The condi.tions of such changes 25 in yield of hydroearbon fluids frorn the improved hydrocracking system are illustrated in the following table. r pi .
..
.
....... _. . ..... , .. I__ .. _.. I. -- .. . . . _ . .. ... ... .. . _ .___ .. _ .. _ .. _ ..... .. .. _.. ... _. ...... _ .....
.. I_.. __ .. .... _ _ .. ._ _ _ . _.~.
:~233~2~ii Table 1 Comparison of Yield Changes between . _ _ Conventional (Old) and Mist Feed Nozzles _ _ ............................ . ...
Operating Conditions Old New % change_ Reactor Temp, F 953 935 -18 I-- Regen Temp, F 1240 1235 -5 Ca1:alyst/Oil 6.0 S.9 -0.L
Conversion, LV %
430-F 71.9 72.6 +0.7 f 650-F .89.6 91.3 ~1.7 Yields _ _ .
C2 wt % 2.1 1.8 -0.3 C3=, ~,V % 7.1 6.5 -0.6 ~C3, LV % 9.2 8.2 -1.0 15 O , LV % 7 5 7 3 -0.2 to ~C4, LV 13.6 12.8 -0.8 C5-430F, LV % 60.8 ~3.5 ~2.7 430-650E`, LV % 17.~ 1~.7 ~0.9 650F-~, LV 10.4 8.7 -1.7 20 Coke, wt % 4.0 3.9 -0.1 From the foregoing Table 1 it will be seen that by use ox nozzles in accordance ilk this inven-tion, hydrocarbons of 4 carbon atoms or less as in bu-tane, propane and e-thane, are each reduced signifi-cantly at the same time, those in the ranc3e from ~5 to those hazing boiling points of about 650F are sub- I:
stantially increased. It is also to he noted in the regard that heavier hydrocarhons, such as those from 650F up, whicll represent increased coke or coking ox the catalyst, are sirnilarly reduced. In a fulL com-.. . ...
.. I!
I, ... . _ .. . . _ _ . . .. _ . ,.. _, . _ ... I_ _ .. .. .. .. . . . _ .. . . _ .. _,, _, .. . , . _, , . ", _ . , .
_, . I, _ I, ., I, _ ,_ ., __., _ .. ___ _ . _ ,1 .
..
~Z33~2S
mercial plant operation, based upon the above identi-Eied comparison, lt may he shown that such :incremental values of desired products, estima-ted to be more valu-able a-t a rate of 25~ per gallon, and obtained by using the nozzle arrangements of the present invention resulted in a $2500/per day profit improvement. On an annualized basis, -this represents a net gain in value of products oE from $750,000 to $900,000 per year.
While only a few embodimen-ts of -the present invention have been disclosed it will be apparent that the opera-ting principals and structures disclosed will suggest to tl-ose swilled in the ar-t various modifica-tions ancl changes which can be made in the present invention wi-thout departing from the spirit thereof.
All such modiEications and changes coming within the scope of the appended claims are intended to be inclu-decl therein.
:, . a
In a preferred form, the cylindrical or helicaL swirl chamber and the exit orifice are axialLy aligned wi-th the hydrocarbon feed line so that as little pressure clrop as possible is experienced by fluid flowing through -the no7zle. Desirably, the .
t .
~33~
ori:Eice exit throat i5 substantially shorter than the length of -the centrifugal swirl chamber. Thus, substantially all hydrau-lic energy in the Elowing fluid is converted to dispersion or misting of the droplets.
The large open areas throuyh the swirling vanes and exit orifices are also an advantage relative to previous nozzle designs because they minimize plugging problems in the nozzle, particularly with the nozzle recessed within the wall of the riser reactor sufficiently to avoid abrasion and direct heating of the nozzle by hot catalysts flowing over it, but without interference wi-th the mistiny or break-up flow pattern from the orifice. In a preferred form of the invention a plurality of nozzles are equally distributed around the circumference of a transi.tion section of the riser reactor where catalyst flow be-comes a mixture of catalyst and hydrocarbonaceous material.
Thus in a first embodiment this invention provides a fluid catalytic hydrocarbon cracking system wherein heated catalyst is circulated through a riser reactor tube for contact with a liquid hydrocarbon feed, with or without water or steam to improve atomization and/or vaporization by reducing hydro-carbon partial pressure of said feed, which comprises: intro-ducing said feed as a single liquid phase into said riser reactor tube to contact a stream of heated catalyst flowing therethrough by first imparting centrifugal rotation to said single phase liquid feed about its axis of flow, said centri-fugal rotation being imparted by flow of said liquid phase through a cylindrical chamber positioned in line with and as a cylindrical extension of a conduit supplyln~ said feed to said riser reactor, and then passing said single phase fluid feed durlng sa:i.d :rotati.on -through an ori:Eice recessed suf:EI.ci.ently ~23~
- 9a - 193~-1587 within an opening in a side wall of said riser reactor tube to malntain said cylindrical chamber and said orifice out of said stream of heated catalyst, said orifice having a diameter less than the diameter of said ehamber and having a throat substan-tially shorter than the length of said chamber, and maintaining the hydraulic pressure of said liquid phase feed flowing through said supply line to retain a eylindrical form during free flow of said liquid phase from said orifice through said opening in said reactor side wall and into said reactor tube before dis-persion of said feed into a uniform mist of liquid drops o'er a uniform conical volume for contact with said stream of heated catalyst particles flowing in said reactor riser.
In a seeond embodiment this invention provides a method of deereasing the residenee time of hydrocarbon liquid on heated catalyst to increase the initial yield of cracked hydrocarbon product and to decrease secondary cracking and coke lay-down by residual hydrocarbonsadhering to catalyst after initial hydrocarbon liquid contact therewith in a fluid cata-lytic hydrocarbon processing system which comprises: contacting a flowing stream of hea-ted hydrocarbon catalytic cracking par-ticles with a uniform spray of single phase hydrocarbonaceous fluid particles, said single phase fluid particles being created by positioning a nozzle having a eentrifugal aeceleration cham-ber between the hydrocarbon fluid feed line and a lateral open-ing into the flow path of said stream of heated eatalyst partieles through the side wall of a reactor riser in sald processing system, said acceleration ehamber being an in-line, solid cylinder axial extension of said single phase fluid feed li.ne and having an exit orifice formed in the end wal.l o:E saicl chamber, saicl exlt orifice being disposed within saicl riser - 9b - 1936-1587 side wall and adjacent to said opening into said reactor riser and the flow passage through said orifice having an area substan~
tially smaller than the cross-sectional area of said chamber r said nozzle including at least a pair of vanes between said hydrocarbon feed line and said centrifugal chamber, the flow passages through said vanes having a combined area substantially equal to said orifice area, said orifice being recessed in said opening sufficiently so that said fluid feed is delivered as an unrestrained and undispersed fluid flow stream through said sidewall opening for contact with said flowing stream of heated catalyst and then forms a break-up pattern over a wide-angle conical volume for contact with said heated catalyst stream as a mist of liquid particles to improve production of low boiling range hydrocarbon fluids and to reduce conversion of said hydro-carbon fluids to both gas and coke.
In a third embodiment this invention provides apparatus for improving the rate of reaction of a hydrocarbon liquid with a heated fluidized catalyst in a fluid catalytic hydrocarbon cracking system which comprises: disposing at least one nozzle unit for spraying a feed of liquid hydrocarbons into the reactor riser of the fluid catalytic hydrocarbon cracking system; said nozzle unit being recessed within a wall of said reactor riser and having a cylindrical swirl chamber positioned between a liquid hydrocarbon feed conduit and the exit orifice from said chamber, stationary vane members between said feed line and said chamber for i.mparting centrifugal ro-tation to said liquid relative to the flow axis through said orifice and said chamber, said exit orifice being smaller in diameter and sub.stant:lally shorter in length than said swirl chamber, and both sald or:l:Eice and sa:Ld chamber be:Lng open Eor Eull flow - 9c 1936-1587 throughout the full cylindrical volumes thereof.
In a fourth embodiment this invention provides a fluid catalyti.c hydrocarbon cracking system wherein hot catalyst is circulated through a riser reactor tube for contact with a liquid hydrocarbon feed, with or without water or steam incor-porated therein to assist atomization and/or vaporization of said liquid hydrocarbon by reducing the partial pressure of the resultant single phase liquid stream, which cornprises: prior to introducing a single phase stream of liquid hydrocarbonaceous Lo materials into a riser reactor tube having a stream of heated catalyst particles flowing therethrough imparting to said single phase liquid stream centrifugal rotation about its own axis of flow, said centrifugal rotation being generated in a cylindrical chamber formed as a solid cylindrical extension of the feed line of said single phase liquid stream, said chamber being recessed within a sidewall of said riser reactor, and then pass-ing the rotating liquid stream through an end wall of said chamber having an orifice formed therein, said orifice being positioned adjacent to but within an opening into said riser reactor tube, said orifice having a diameter less than the dia-meter of said chamber and having a throat substantially shorter than the length of said chamfer, and controlling the hydraulic pressure ox said single phase liquid stream flowing through the supply line to said centrifugal chamfer to maintain the in-tegrity of said liquid stream flowing from said orifice through at least said reactor sidewall opening so that said liquid stream is converted to a conical dispersion of single phase liquid par-tlcles after passage into said stream of heated ca-talyst partlcles.
In a fifth ernbod:lment this invention provldes a ~33~5 - 9d - 1936-1587 method of introducing a single phase hydrccarbonaceous feed in-to a stream oE heated catalyst particles Elowing in a reactor tube of a fluid catalytic cracking system without abrasion of or coke build up on the nozzle system for said feed which com-prises forming said single phase feed as a :Eluid mixture of a liquid hydrocarbon and steam in a single flow line, passing said flow through at least a pair of turning vanes under sufficient hydraulic pressure to generate significant axial rotation of said feed about its own flow axis in said line and without sub-stantial increase in the cross-sectional area of said flow line, and then passing said single phase liquid feed during said rotation through an orifice recess sufficiently within an open-ing in a sidewall of said reactor tube to recess said orifice out of said stream of heated catalyst particles, and maintaining said hydraulic pressure of said single phase feed adequate to retain substantially the diameter of said orifice in the feed stream during free flow thereof from said orifice through said opening in said reactor tube sidewall and into said reactor tube before dispersion of said feed into a uniform conical volume of disperse particles for contact with said stream of heated cata-lyst particles.
Further objects and advantages of the present inven-tion will become apparent from the following detailed description taken in conjunction with the accompanying drawings which form a integral part of the present specification.
Brief Description of the Drawings Figure 1 is an elevation v:iew o:E a lower portion of a fLuid catalytic cracking system to which the feed nozz:Le sys-tem of the present :lnvention has been applied and generally :in-d:Lcates a r:Lser reactor to wh:Lch heatecl cata:Lyst :Ls supp.l:Led ~3~
- 9e - 1936-1587 from a regenerator and the return line for spent catalyst flowing from the separator vessel back to the regenerator.
Figure 2 is a cross-sectional view taken in the direction of arrows 2 - 2 in E'igure 1 which lllus-~;~;33~ 5 --10-- r I;
trates an arrangement of a plurality of feed nozzles constructed in accordance with the present invention for flow,ing hydrocarbon feed from a circular header to a plurality of misting,nozzles dis-tributeA around a 5 riser reactor.
Figure 3 is a cross-sectional view of one " suitable form of nozzle constructed in accordance with the inven-tion for assuring full flow of hydrocarbon feed as a mist into the riser reactor from within the lO side wall oE the fluidized catalyst flow line, taken in the direction of arrows 3-3 through one of the noz-zles shown in Figure 2.
Figure 4 is a cross sectional view taken in _ the direction of arrows 4-~ in Figure 3 particularly 15 illustrating the vane members inducing centri-Eugal or helical motion to flow of the hydrocarboll feed as i-t enters the centrifugal chamber and which directly supplies feed to catalyst through the reduced diameter orifice of -the nozzle.
20 Description of Preferred embodiments of the Invention Referring now to -the drawings and in parti- I, cular Figure l, there is shown a portion of a flui-dized catalytic cracking unit to which the present invention has been applied. The sys-tem generally 'I
25 cornprises a riser reactor pipe lO in which heated catalyst, supplied from regenerator 12 is reacted with liquid hydrocarbons. Catalyst flows from regenerator 12 to pipe lO through U-tube 14. Catalyst is par- s,~
tially fluidized in U-tube 14 by gas, preferably 30 steam, supplied by a series of nozzle rings 13 along - the length of U-tube 14. I'he steam entrains and par tially fluidizes catalyst particles suppLiecl by gra-vity from intake 15 in regenerator 12 and conveys them to riser pipe lO.
' .. ; .
o r I
~233 ~2S
A stream of hydrocarbon liquid is supplied to riser pipe 10 by line 21 under control of valve 22. As indicated in Figure 2, line 21 may supply a ring of feed nozzles 20 con-nected to a annular header 23. Because the catalyst particles are on the order of 20 to 120 microns in diameter it is impor--tant what liquid feed from line 21 and header 23 be as evenly distributed as possible and in proper droplet size for intimate contact and substantially instantaneous vaporization ox the liquid droplets. This is essential because the vapor-phase catalytic reaction time to generate desired low boiling range liquids by contact between hot catalyst particles and hydrocar-bon liquid droplets is on the order of 1 to 10 seconds; more properly, a reaction time range of 1 to 3 seconds and frequent-ly about 1 second, is required for optimum catalytic reaction to generate middle distillate hydrocarbons rather than to gas or coke.
Substantially instantaneous reaction o-E misted hydro-carbon droplets with heated catalyst particles generates large volumes of hydrocarbon vapor which primarily fluidize and carry the mixture upwardly in reactor 10 for prompt discharge and separation in separator vessel 24. The reacted hydrocarbon vapor and catalyst are separated in the upper portion of vessel 2~ in the manner described in copending Canadian applications Serial No. 395,902; 407,150 and 415,510. These applications describe overall structures and arrangements of suitable fluid catalytic cracking systems to which the present invention may be appliecl, and particularly the misting feed nozzle system herein disclosed and claimed. As disclosed in said applica-~33~5 tions, the catalyst is released or discharged from riser 10 and by inertia and gravity ef-fect the catalyst is separated from -the vapor. The spent catalyst i5 recovered in a s-tripping section, indicated as 32, at or in -the lower end of vessel 24.
The generated vapor is recovered overhead and condensed in a distillation column (not shown).
Catalyst recovered in the separa-tion process contains a certain amount of residual hydrocarbons in the form of coke primarily carbon' adhering to the spent catalyst. Such carbon, or coke laden spent catalyst is returned to regenerator 12 through stripper means 32. Residual hydrocarbon vapor is removed from the spent catalyst in stripper 32 by introduction of steam, such as by line 3'1, feeding nozzles 35 at the lower end of stripper 32. Stripper 32 generally includes a plurality of baffles or sheds (not shown) to prolong residence time of the spent catalyst therein. Catalyst is assisted in returning to regenerator 12 by introduction of steam through a serles of nozzle rings 36 along return U-tube 38. Spent catalyst is regenerated by addition of oxygen as by line 40, to turn resi-dual coke, from the catalyst particles supported for oxidationon grid 42. This supplies heat to the catalyst that circulates in the system and returns to riser 10 from bed 47 through intake l Offgas -from the burned coke is vented from regener-ator 12 through cyclones and a 1ue pipe (not shown).
As noted above, the present invention is particularly concerned with a method of vaporizing the liquid hydrocarbon feed as rapidly as possible in riser reac-tor 10 so that the essential reaction of : L~339~2~
I, vaporized hydrocarbons in gas-phase wlth -the catalys-t partlcles, may proceed as the mixture flows through riser 10 i.n the alloted time of one -to -ten seconds, and mos-t preferably in the range of one to three 5 seconds.
For such short reaction times i-t is essen-` tial that all of the ]iqui.d feed be substantially P
instantaneously converted to gas to effect -the neces-sary catalys-t-gas phase reaction. Such reaction 10 cracks the heavier hydrocarbon molecules to the desired middle boiling range hydrocarbons. To achieve such prompt gasification the flow pattern of the liquid eed into the fluidized catalyst stream must be uniform both as to droplet size and distribution at 15 reasonable commercially available flow rates and pres- 'I
sures. Further, nozzles for creating such patterned flow must be capable of extended service without plug-ging (as hy formation of coke from the hot hydrocar-bons fl.owing through it) or mechanical wear (as by : 20 ab.rasion of the fluidized catalyst particles).
Whi.le as noted above, it has been proposed heretofore to use steam or water as the prirnary dis-persing fluid for atomizing the flow of hydrocarbon feed, we have found superior results, without addition 25 of steam,~can be obtained in accorclance with our invention, by use of a nozzle having a single swirl chamber, acting as a helical or centr:ifugal accelera-tion compartment, placed between the full flow liquid feed line and a reduced area orifice formed in the 30 discharge end of the swirl chamher. For this purpose, .
as shown in Figure 3, swirl chamber 51 is substan-tially the same diameter as the full bore of flow nozzle 20. Preferabl.y, nozzle 20 does not extend into the flow path of reactor riser 10, as in -transltion . i -- . .. .... _ . . ... _ .. .. .. .. . .... ... , _ . _ _, _ _ _ .. _ . _, .. _ . . , _ _, . _, , _, . _ _ _ . _,, _ _, _ l'h33925 : , . I, section 17, bu-t ls only sufficiently deep in wall 11 and insulation-abrasion layer 19 to insure full flow of the liquid stream, as indica-ted, wi-thout dispersion of the output through orifice 54 until the break-up pattern i5 well within the flow pat of catalyst, as in transition section 17. The pitch of vanes 53, the size and length of chamber 51 relative to the diame-ter I-and the depth or length of orifice 54 are selectecl to con-trol the angle of dispersion from nozzle 20 so that the break-up pattern creates properly sized droplets and occurs a short distance away from the orifice. In this way, the nozzle, including the orifice end, may be recessed within the reactor riser side wall so that the droplets will contact the flowing catalyst in riser 10 rather than the sidewalls thereof.
Fur-ther, i-t is importan-t to assure that virtually all hydraulic energy is available from the hydrocarbon feed through nozzle 20 to genera-te the j helical or centrifugal ac-tion on the feed to generate 20 the desired pattern of straight cylindrical flow hav- ;
ing a diameter substantially the same as -the orifice diameter for a short distance, say 1/2 to 2 inches, as I.
schematically indicated in Figure 3,and then full break-up of the stream into a wide angled conical mist-like spray of droplets. For such a flow pattern, a single pair of deflection vanes 53 are disposed -transverse and angled to the axis of flow through nozzle 20. Vanes 53, which generate the rotation or helical motion to liquid flowing therethrough, create such a pattern. These vanes may have a pitch of from I-15 to 45 to the axis of the feed line an<l chamber 51. Preferably, the pitch angle is from 25 to 35, and most preferably about 30. Wi-th vanes 53 so I.
.... . .
~3~25 angled, the two flow areas 52 may be made with a combined area substantially equal to the flow area of exit orifice 5~. This permits full pressure of the weed line to be applied to rota-Zion of the stream in chamber 51 and subsequent release of the liquid in the required pattern.
As indicated, swirl or centriEugal action is trans-verse and circular to the direction of flow and results in full rotation of the en-tire flow coming through the noz~]e prior to exit through the reduced diameter of the throat 55 oE orifice 54. While orifice 54 is shown as a single, circular or cylin-drical opening, the area may include various other configura-tions such as serrations in the cylindrical surface of throat 55 of end wall 56. As indicated, the length of throat surface 55 is only sufficiently long to form a solid flow for a short distance away -from orifice 54. Such distance is sufficient to permit recessing the nozzle in the side wall of riser pipe 10 including the erosion resistant coating without interference with the wide angle conical dispersion pattern. In practice the angle "A" ox the apex of such a conical or parabolic volume should be in excess of 90 and preferable about 120, as indi-ca-ted in Figure 3.
As indicated in Figure 2, nozzles 20 may be equally distributed around riser pipe 10. The number may be varied in accordance with the diameter and flow rate of catalyst there-through and may vary from 1 or 2 to a multiplicity, such as 6 as shown in Figure 2, or an even greater number, say 12 -to 15.
As shown, the angle of the nozzle axis is from 20 to 70 rela-tive to the axis of the riser reactor, and more desirable about 30 to 50, to assi.st in dispersion of the particles in the directiorl ox catalysl:-hy~rocarbon mixture Elow.
3~
,~, While i-t is conteMplated in the present invention that -the entire feed will be a hydrocarbon liquid, it is also expectecl that steam rnay be added directly to the feed liquid for the purpose of 5 reducing the partial pressure of hydrocarbon liquid after it enters riser pipe 10. However, it is essen- I, tial that such steam and hydrocarbon be mixed before the fluid is introAuced into nozæle 20 ancl the mix-ture rotated together in chamber 51 for dispersion by ori-fice 54. This assures miniMurn pressure drop through the nozzle so -that the mixture wi]l not significantly decrease the fulL flow at the highest available hydraulic pressure to atomize the hydrocarbon feed ~~
into liquid droplets to the desired fineness after break up of the stream from orifice 54. In this way, -the desired mist is formed in the riser so that such droplets are immediately and completely vaporized upon ; contact with the heated catalyst particles.
us noted before, the use of steam in the _-initial reaction of hydrocarbon fluids with the cata-lyst is generally undesirable in fluid ca-talytic cracking. This is because the steam passes overhead with the vapor recovered in vessel 24 and must be treatecl with -the condensed hydrocarbon product. Such condensa-tion results in a "sour" water disposal since any water soluble materials, and part:icularly oxides of sulfur, nitrogen and carbon, in the condensate result in an acidic water disposal problem. Further, the need to recover and dispose of "sour water" in the condensate results in loss of efficiency of the con-version process and is an added cost in operation of the system.
s used herein, it is contemplated that catalyst particles wilL be heated -to a telnperature oF
.. ,,_ . . .. . .. ... .. .. ... , . .. .. . . . . . . . _ . .__ _ .. _ _ .
.
~23342~i;
:Erom lOOODF to 1400F and preferably a-t a -temperature of about 1200F to 1300~F. ~hi:Le the present sys-tem will produce nearly instantaneous misti.ng and vapori-zation at hiyher -temperatures, say up to 1500, com-5 mercial catalytlc cracking sys-tems capable of such high temperature operation are not yet common. Dow- I-.. ever, the present invention is particularly suitable for such high tempera-ture operation, because in gen-eral, full flow of the hydrocarbon fluid is preserved 10 under what otherwise might be coking conditions in the nozzle. Such coking is particularly to be avoided to rmain-tain high flow rates -through the nozzles. Accor- ~~
dingly, problems of coking, avoided in prior ar-t devices by use ox a s-team shroud in a surrouncling 15 atmosphere or vice-versa, are solved by nozzles operating in accordance with the present invention to disperse the hydrocarbon feed into well dispersed, mist-like droplets.
In modern forms of fluid catalytic cracking, 20 typical catalys-t includes a combination of amorphous materials toge-ther with crystalline materials, such as : molecular sieves. The-predominant components of such .
cracking catalyst are silica and alumina in weight ratios of from abou-t loo to about 60o alumina in 25 silica. Various combinations of rare earth elements may also be present. Silica-magnesia and other mixed oxide catalyst may be used. The cata:Lyst used may include particles having a wide range of free settling rates. Commercially available, powdered cracking 30 catalyst have a particle size distrihu-tion from 60-90 weight i.n the ranye of 20-120 microns.
A particular advalltaye of fluiclized cata-lytic cracking is that a wide range ox hydrocarbon Eeedstocks may be processed in such a method. These ., I.
_v .~ ", -- .................................... ----. ... -- .. -- -- . , . -- --. ,, .. . .-- ,.. _., , _ _ _ _ _ __.
_,~, __, ,_, ., _ _ .. _ , _ ., _, _ _ .. __ .. I___.. , .. _ .. ... .. .. . _~ _.. .. .~ . . .. ~.~ .. I_ .. I. ._.. I. .__.. _.__ __~_____ I
. _~_ _~ _.. _.. .
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~233~5 .
I, may include virgin petroleum distillates, residual petroleum fractlons, deasphalted oils, hydrocarbon oil and mixtures -thereoE. Other heavy petroleum hydro-carbon Eractions, that is, those having boiling points 5 of 600F ancl heavier, may be advantageously converted to lower boiling, more valuable, hydrocarbon pro-ducts. In such a reaction, the temperature o the P
feedstock in general will be from ambient temperatures to from 350F or 400E-'. While the feed may be 10 vaporized before release into the stream of ho-t regenerated catalyst particles flowing in the riser reactor, in general it is econornically preferable to vaporize the-hydrocarbon prirnarily by contact wi-th the hot catalyst. A wide range of catalyst to oil 15 feed/weight ra-tios may be used bu-t preferably the catalyst/oiL feed weight ratio is from about 2:1 to about 20:1 with a range of hydrocarborl/catalyst con-tact times in the range of 1 to about 10 seconds. and I, mos-t preferably from 1 to 3 seconds.
The full reasons that the present arrangement of a cylindrical swirl charnber and an orifice having both a reduced diameter and a short throat area is so effective in vaporizing the Eeed in the desired pattern is not fully unders-tood. However, i.t is believed that the mis-ting action of -the nozzle is achieved by vir-tue of fluid passing from axial flow to circular or centrifugal flow throu(3h passageways to the turning vanes having a small pres,ure drop there-through and a flow area about equal to the orifice area. Thus, full passage ox the en-tire spray Erom the swirl chamber through a rela-tively short orifice quickly forms a short cylinclrical flow section which then expancls over a large conical section. This pat-tern is not only effective to create proper sized _ t:
.... . , .-- . __. . _ . .
:~233~
. - 1 C3 _ . . - I.
droplets Eor rapid eonversion to gas by the eatalyst but most importantly permi-ts recessiny the nozzle in the riser sicle wall -to avoid both catalyst abrasion and direct heating by the hot catalyst. because of 5 the rapid expansion of the feed in-to finely divided particLes over a wide angle conical pattern, a highly ;
turbulen-t gas flow stream is created by the voluminous production of hydrocarbon vapor when the hot liquid droplets contaets the hot eatalyst. Preferably Elow 10 from the nozzle orifice into the catalys-t stream is a-t a point where the catalyst is slightly slowed by an increase in area from U-tube 14 in-to riser 10. Tran- I:
sition section 15 provides such an increasing eross-sectional area ancl aids in the sudden aeeeleration of 15 the feed and catalys-t mixture due to vapor evolution s from hydrocarbons reaeting with hot catalyst.
While the reason for such sudclen and more eomplete evolutiorl of desirable hydrocarbons is not jt fully unclers-tood, comparison of a eommereial Fluid _-; 20 eatalytie cracking sys-tem using conven-tional nozzles, where no particular effort was made to obtain a mist-ing spray, with a system of nozzles for vaporizing t feed in accordance with -the presen-t invention is par-ticularly impressive. The condi.tions of such changes 25 in yield of hydroearbon fluids frorn the improved hydrocracking system are illustrated in the following table. r pi .
..
.
....... _. . ..... , .. I__ .. _.. I. -- .. . . . _ . .. ... ... .. . _ .___ .. _ .. _ .. _ ..... .. .. _.. ... _. ...... _ .....
.. I_.. __ .. .... _ _ .. ._ _ _ . _.~.
:~233~2~ii Table 1 Comparison of Yield Changes between . _ _ Conventional (Old) and Mist Feed Nozzles _ _ ............................ . ...
Operating Conditions Old New % change_ Reactor Temp, F 953 935 -18 I-- Regen Temp, F 1240 1235 -5 Ca1:alyst/Oil 6.0 S.9 -0.L
Conversion, LV %
430-F 71.9 72.6 +0.7 f 650-F .89.6 91.3 ~1.7 Yields _ _ .
C2 wt % 2.1 1.8 -0.3 C3=, ~,V % 7.1 6.5 -0.6 ~C3, LV % 9.2 8.2 -1.0 15 O , LV % 7 5 7 3 -0.2 to ~C4, LV 13.6 12.8 -0.8 C5-430F, LV % 60.8 ~3.5 ~2.7 430-650E`, LV % 17.~ 1~.7 ~0.9 650F-~, LV 10.4 8.7 -1.7 20 Coke, wt % 4.0 3.9 -0.1 From the foregoing Table 1 it will be seen that by use ox nozzles in accordance ilk this inven-tion, hydrocarbons of 4 carbon atoms or less as in bu-tane, propane and e-thane, are each reduced signifi-cantly at the same time, those in the ranc3e from ~5 to those hazing boiling points of about 650F are sub- I:
stantially increased. It is also to he noted in the regard that heavier hydrocarhons, such as those from 650F up, whicll represent increased coke or coking ox the catalyst, are sirnilarly reduced. In a fulL com-.. . ...
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I, ... . _ .. . . _ _ . . .. _ . ,.. _, . _ ... I_ _ .. .. .. .. . . . _ .. . . _ .. _,, _, .. . , . _, , . ", _ . , .
_, . I, _ I, ., I, _ ,_ ., __., _ .. ___ _ . _ ,1 .
..
~Z33~2S
mercial plant operation, based upon the above identi-Eied comparison, lt may he shown that such :incremental values of desired products, estima-ted to be more valu-able a-t a rate of 25~ per gallon, and obtained by using the nozzle arrangements of the present invention resulted in a $2500/per day profit improvement. On an annualized basis, -this represents a net gain in value of products oE from $750,000 to $900,000 per year.
While only a few embodimen-ts of -the present invention have been disclosed it will be apparent that the opera-ting principals and structures disclosed will suggest to tl-ose swilled in the ar-t various modifica-tions ancl changes which can be made in the present invention wi-thout departing from the spirit thereof.
All such modiEications and changes coming within the scope of the appended claims are intended to be inclu-decl therein.
:, . a
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fluid catalytic hydrocarbon cracking system wherein heated catalyst is circulated through a riser reactor tube for contact with a liquid hydrocarbon feed, with or with-out water or steam to improve atomization and/or vaporization by reducing hydrocarbon partial pressure of said feed, which comprises:
introducing said feed as a single liquid phase into said riser reactor tube to contact a stream of heated catalyst flowing therethrough by first imparting centrifugal rotation to said single phase liquid feed about its axis of flow, said centrifugal rotation being imparted by flow of said liquid phase through a cylindrical chamber positioned in line with and as a cylindrical extension of a conduit supplying said feed to said riser reactor, and then passing said single phase liquid feed during said rotation through an orifice recessed suffi-ciently within an opening in a side wall of said riser reactor tube to maintain said cylindrical chamber and said orifice out of said stream of heated catalyst, said orifice having a dia-meter less than the diameter of said chamber and having a throat substantially shorter than the length of said chamber, and maintaining the hydraulic pressure of said liquid phase feed flowing through said supply line to retain a cylindrical form during free flow of said liquid phase from said orifice through said opening in said reactor side wall and into said reactor tube before dispersion of said feed into a uniform mist of liquid drops over a uniform conical volume for contact with said stream of heated catalyst particles flowing in said reac-tor riser.
introducing said feed as a single liquid phase into said riser reactor tube to contact a stream of heated catalyst flowing therethrough by first imparting centrifugal rotation to said single phase liquid feed about its axis of flow, said centrifugal rotation being imparted by flow of said liquid phase through a cylindrical chamber positioned in line with and as a cylindrical extension of a conduit supplying said feed to said riser reactor, and then passing said single phase liquid feed during said rotation through an orifice recessed suffi-ciently within an opening in a side wall of said riser reactor tube to maintain said cylindrical chamber and said orifice out of said stream of heated catalyst, said orifice having a dia-meter less than the diameter of said chamber and having a throat substantially shorter than the length of said chamber, and maintaining the hydraulic pressure of said liquid phase feed flowing through said supply line to retain a cylindrical form during free flow of said liquid phase from said orifice through said opening in said reactor side wall and into said reactor tube before dispersion of said feed into a uniform mist of liquid drops over a uniform conical volume for contact with said stream of heated catalyst particles flowing in said reac-tor riser.
2. A fluid catalytic hydrocarbon cracking system in accordance with claim 1 wherein liquid feed is from a plurality of uniformly distributed recessed opening around a transition section of said riser reactor tube wherein the diameter of said tube increases to accommodate the increased flow rate of heated catalyst contacting said liquid hydrocarbon feed to form a hydrocarbon-catalyst mixture for reaction flow in said riser reactor tube.
3. A method of decreasing the residence time of hydro-carbon liquid on heated catalyst to increase the initial yield of cracked hydrocarbon product and to decrease secondary crack-ing and coke lay-down by residual hydrocarbons adhering to catalyst after initial hydrocarbon liquid contact therewith in a fluid catalytic hydrocarbon processing system which com-prises:
contacting a flowing stream of heated hydrocarbon cata-lytic cracking particles with a uniform spray of single phase hydrocarbonaceous fluid particles, said single phase fluid particles being created by positioning a nozzle having a cen-trifugal acceleration chamber between the hydrocarbon fluid feed line and a lateral opening into the flow path of said stream of heated catalyst particles through the side wall of a reactor riser in said processing system, said acceleration chamber being an in-line, solid cylinder axial extension of said single phase fluid feed line and having an exit orifice formed in the end wall o-f said chamber, said exit orifice being disposed within said riser side wall and adjacent to said open-ing into said reactor riser and the flow passage through said orifice having an area substantially smaller than the cross--23a-sectional area of said chamber, said nozzle including at least a pair of vanes between said hydrocarbon feed line and said centrifugal chamber, the flow passages through said vanes having a combined area substantially equal to said orifice area, said orifice being recessed in said opening sufficiently so that said fluid feed is delivered as an unrestrained and undispersed fluid flow stream through said sidewall opening for contact with said flowing stream of heated catalyst and then forms a break-up pattern over a wide-angle conical volume for contact with said heated catalyst stream as a mist of liquid particles to improve production of low boiling range hydrocarbon fluids and to reduce conversion of said hydrocarbon fluids to both gas and coke.
contacting a flowing stream of heated hydrocarbon cata-lytic cracking particles with a uniform spray of single phase hydrocarbonaceous fluid particles, said single phase fluid particles being created by positioning a nozzle having a cen-trifugal acceleration chamber between the hydrocarbon fluid feed line and a lateral opening into the flow path of said stream of heated catalyst particles through the side wall of a reactor riser in said processing system, said acceleration chamber being an in-line, solid cylinder axial extension of said single phase fluid feed line and having an exit orifice formed in the end wall o-f said chamber, said exit orifice being disposed within said riser side wall and adjacent to said open-ing into said reactor riser and the flow passage through said orifice having an area substantially smaller than the cross--23a-sectional area of said chamber, said nozzle including at least a pair of vanes between said hydrocarbon feed line and said centrifugal chamber, the flow passages through said vanes having a combined area substantially equal to said orifice area, said orifice being recessed in said opening sufficiently so that said fluid feed is delivered as an unrestrained and undispersed fluid flow stream through said sidewall opening for contact with said flowing stream of heated catalyst and then forms a break-up pattern over a wide-angle conical volume for contact with said heated catalyst stream as a mist of liquid particles to improve production of low boiling range hydrocarbon fluids and to reduce conversion of said hydrocarbon fluids to both gas and coke.
4. Apparatus for improving the rate of reaction of a hydrocarbon liquid with a heated flui-dized catalyst in a fluid catalytic hydrocarbon crack-ing system which comprises:
disposing at least one nozzle unit for spraying a feed of liquid hydrocarbons into the reac-tor riser of the fluid catalytic hydrocarbon cracking system;
said nozzle unit being recessed within a wall of said reactor riser and having a cylindrical swirl chamber positioned between a liquid hydrocarbon feed conduit and the exit orifice from said chamber, stationary vane members between said feed line and said chamber for imparting centrifugal rotation to said liquid relative to the flow axis through said orifice and said chamber, said exit orifice being smaller in diameter and substantially shorter in length than said swirl chamber, and both said orifice and said chamber being open for full flow throughout the full cylindrical volumes therof.
disposing at least one nozzle unit for spraying a feed of liquid hydrocarbons into the reac-tor riser of the fluid catalytic hydrocarbon cracking system;
said nozzle unit being recessed within a wall of said reactor riser and having a cylindrical swirl chamber positioned between a liquid hydrocarbon feed conduit and the exit orifice from said chamber, stationary vane members between said feed line and said chamber for imparting centrifugal rotation to said liquid relative to the flow axis through said orifice and said chamber, said exit orifice being smaller in diameter and substantially shorter in length than said swirl chamber, and both said orifice and said chamber being open for full flow throughout the full cylindrical volumes therof.
5. Appartus in accordance with claim 4 wherein a plurality of nozzles are substantially uni-formly distributed around the circumference of a tran-sition section of said reactor.
6. Apparatus in accordance with claim 4 wherein said nozzle is disposed at an angle of from 20° to 70° relative to the axis of said riser reactor.
7. Apparatus in accordance with claim 4 wherein said stationary vanes have an angle to the axis of said chamber of from 15° to 45°.
8. Apparatus in accordance with claim 7 wherein said angle is from 25° to 35°.
9. Apparatus in accordance with claim 7 wherein said angle is from l5° to about 30°.
10. A fluid catalytic hydrocarbon cracking system wherein hot catalyst is circulated through a riser reactor tube for contact with a liquid hydrocarbon feed, with or without water or steam incorporated therein to assist atomization and/or vaporization of said liquid hydrocarbon by reducing the partial pressure of the resultant single phase liquid stream, which comprises:
prior to introducing a single phase stream of liquid hydrocarbonaceous materials into a riser reactor tube having a stream of heated catalyst particles flowing therethrough imparting to said single phase liquid stream centrifugal rota-tion about its own axis of flow, said centrifugal rotation being generated in a cylindrical chamber formed as a solid cylindrical extension of the feed line of said single phase liquid stream, said chamber being recessed within a sidewall of said riser reactor, and then passing the rotating liquid stream through an end wall of said chamber having an orifice formed therein, said orifice being positioned adjacent to but within an opening into said riser reactor tube, said orifice having a diameter less than the diameter of said chamber and having a throat substantially shorter than the length of said chamber, and controlling the hydraulic pressure of said single phase liquid stream flowing through the supply line to said centrifu-gal chamber to maintain the integrity of said liquid stream flowing from said orifice through at least said reactor side-wall opening so that said liquid stream is converted to a conical dispersion of single phase liquid particles after pas-sage into said stream of heated catalyst particles.
prior to introducing a single phase stream of liquid hydrocarbonaceous materials into a riser reactor tube having a stream of heated catalyst particles flowing therethrough imparting to said single phase liquid stream centrifugal rota-tion about its own axis of flow, said centrifugal rotation being generated in a cylindrical chamber formed as a solid cylindrical extension of the feed line of said single phase liquid stream, said chamber being recessed within a sidewall of said riser reactor, and then passing the rotating liquid stream through an end wall of said chamber having an orifice formed therein, said orifice being positioned adjacent to but within an opening into said riser reactor tube, said orifice having a diameter less than the diameter of said chamber and having a throat substantially shorter than the length of said chamber, and controlling the hydraulic pressure of said single phase liquid stream flowing through the supply line to said centrifu-gal chamber to maintain the integrity of said liquid stream flowing from said orifice through at least said reactor side-wall opening so that said liquid stream is converted to a conical dispersion of single phase liquid particles after pas-sage into said stream of heated catalyst particles.
11. A method of introducing a single phase hydrocarbon-aceous feed into a stream of heated catalyst particles flowing in a reactor tube of a fluid catalytic cracking system without abrasion of or coke build up on the nozzle system for said feed which comprises forming said single phase feed as a fluid mixture of a liquid hydrocarbon and steam in a single flow line, passing said flow through at least a pair of turning vanes under suffi-cient hydraulic pressure to generate significant axial rotation of said feed about its own flow axis in said line and without substantial increase in the cross-sectional area of said flow line, and then passing said single phase liquid feed during said rotation through an orifice recessed sufficiently within an opening in a side wall of said reactor tube to recess said orifice out of said stream of heated catalyst particles, and maintaining said hydraulic pressure of said single phase feed adequate to retain substantially the diameter of said orifice in the feed stream during free flow thereof from said orifice through said opening in said reactor tube side wall and into said reactor tube before dispersion of said feed into a uniform conical volume of disperse particles for contact with said stream of heated catalyst particles.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US46412183A | 1983-02-04 | 1983-02-04 | |
| US464,121 | 1983-02-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1233425A true CA1233425A (en) | 1988-03-01 |
Family
ID=23842653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000443269A Expired CA1233425A (en) | 1983-02-04 | 1983-12-14 | Fluid catalytic cracking systems |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS59145287A (en) |
| CA (1) | CA1233425A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9681609B2 (en) | 2014-09-09 | 2017-06-20 | Michael Anthony Kaminski | Garden plot watering enclosure |
| EP1954356A4 (en) * | 2005-11-29 | 2017-12-13 | Bete Fog Nozzle, Inc. | Spray nozzles |
| CN110038487A (en) * | 2019-05-23 | 2019-07-23 | 洛阳智邦石化设备有限公司 | A kind of riser reactor nozzle of easy access dismounting |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7221128B2 (en) | 2002-05-30 | 2007-05-22 | Sanken Electric Co., Ltd. | Converter with start-up circuit |
| US9030855B2 (en) | 2011-07-14 | 2015-05-12 | Macronix International Co., Ltd. | Semiconductor device, start-up circuit having first and second circuits and a single voltage output terminal coupled to a second node between the semiconductor unit and the first circuit, and operating method for the same |
-
1983
- 1983-12-14 CA CA000443269A patent/CA1233425A/en not_active Expired
-
1984
- 1984-02-03 JP JP1727484A patent/JPS59145287A/en active Granted
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1954356A4 (en) * | 2005-11-29 | 2017-12-13 | Bete Fog Nozzle, Inc. | Spray nozzles |
| US9681609B2 (en) | 2014-09-09 | 2017-06-20 | Michael Anthony Kaminski | Garden plot watering enclosure |
| CN110038487A (en) * | 2019-05-23 | 2019-07-23 | 洛阳智邦石化设备有限公司 | A kind of riser reactor nozzle of easy access dismounting |
| CN110038487B (en) * | 2019-05-23 | 2024-04-12 | 洛阳智邦石化设备有限公司 | Riser reactor nozzle convenient to overhaul and disassemble and assemble |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0250156B2 (en) | 1990-11-01 |
| JPS59145287A (en) | 1984-08-20 |
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