EP0212007B1 - Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels - Google Patents
Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels Download PDFInfo
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- EP0212007B1 EP0212007B1 EP19850201308 EP85201308A EP0212007B1 EP 0212007 B1 EP0212007 B1 EP 0212007B1 EP 19850201308 EP19850201308 EP 19850201308 EP 85201308 A EP85201308 A EP 85201308A EP 0212007 B1 EP0212007 B1 EP 0212007B1
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- solids
- particulate solids
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G9/28—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid material
- C10G9/32—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid material according to the "fluidised-bed" technique
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G51/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more cracking processes only
- C10G51/06—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more cracking processes only plural parallel stages only
Definitions
- This invention relates to the production of olefins and liquid hydrocarbon fuels from heavy hydrocarbons, and, more particularly, to the production of olefins in a thermal cracking environment.
- Residual oils are customarily identified as residual, reduced crude oils, atmospheric tower bottoms, vacuum residual oils, topped crudes and most hydrocarbons heavier than gas oils.
- the problem with the residual oils is that they contain contaminants, such as sulphur and metals.
- Heavy metals are particularly troublesome in catalytic cracking operations.
- the heavy hydrocarbons also contain a greater abundance of coke precursors (asphaltenes, polynuclear aromatics, and the like). Coke precursors to convert to coke during the cracking operation and tend to foul the equipment and catalyst or inert particles used in the cracking process.
- FR-A 2 247 527 discloses a process in which petroleum is split into fractions by subjecting the fractions which pass above a temperature of from 350 ° C to 500 ° C to a thermal transformation by contacting with a fluidized bed of a heat-carrier held at a temperature between 500 ° C and 670°C, for a time from 10 to 15 s, in the presence of from 25% to 100% of steam, on a weight basis, and subsequently subjecting the fractions passing above temperatures of from 360 ° C to 500 ° C to a co-current transformation with a heat-carrier at a temperature of from 560 ° C to 800 ° C, for a time of from 0,3 s to 3,0 s, the fractions passing below a temperature of from 350 ° C to 500 ° C being so transformed as to have the transformation products reaching the fluidized bed environment.
- the comparatively low temperatures ranges selected in FR-A 2 247 527 require long residence times and the use of a fluidized bed and of added steam contribute towards rendering the process cumbersome.
- EP-A 0 026 674 discloses a thermal regenerative cracking (TRC) process using coke particles as heat-carriers, which are then centrifugally separated from the diluted mixed-phase stream of gas and solids.
- the objects of the present invention thus are to crack heavy hydrocarbon to produce olefins and liquid fuels, and, additionally, to crack atmospheric tower bottoms by first processing the atmospheric tower bottoms through a vacuum tower and separately cracking the vacuum oil and the vacuum resid.
- a process for the production of olefins or light hydrocarbon fuels comprising the steps of: (a) separating a heavy hydrocarbon into a light hydrocarbon fraction and a heavy hydrocarbon fraction; (b) thermally cracking the light hydrocarbon fraction with heat supplied by hot particulate solids; (c) separating the cracked product from the hot particulate solids; (d) delivering the separate particulate solids to a stripper-coker; (e) introducing the heavy hydrocarbon in the stripper-coker to produce vaporized hydrocarbon and coke; (f) combusting the coke produced in the reactor and stripper-coker to heat the particulate solids, and (g) returning the heated particulate solids to the thermal cracking reactor.
- the thermal cracking temperature is about 816°C (1500 ° F)
- the ratio of solids to light hydrocarbon by weight is between 5 and 60
- the reaction residence time is from 0,05 to 0,50 s.
- the process of the present invention is directed to producing olefins and liquid fuels from a heavy hydrocarbon feed.
- Atmospheric tower bottoms are well suited for processing by the process of the present invention.
- any heavy feed such as residual oil, that can be separated into a light and a heavy stream can be processed by the present invention.
- the system is comprised essentially of a vacuum tower 2 and a thermal regenerative cracking assembly.
- the thermal regenerative cracking assembly is comprised of a thermal regenerative cracking reactor 6, a reactor feeder 4, a separator 8 and a coke stripper vessel 10.
- the system also includes means for regenerating solids particles separated from the cracked product after the reaction.
- the system shows illustratively an entrained bed heater 16, a transport line 12 and a fluid bed vessel 14 in which the solids can be regenerated.
- atmospheric tower bottoms are delivered through line 3 to a conventional vacuum tower 2 (operated at about 26,66 millibar) wherein the atmospheric tower bottoms (ATB) are separated into a light overhead vacuum oil stream and a heavier bottoms vacuum resid.
- the vacuum gas oil is condensed and then passed through line 20 to the thermal regenerative cracking reactor 6.
- the vacuum gas oil is delivered to the reactor 6 with hot solids particles that are passed through the reactor feeder 4 (best seen in FIGURE 2). Immediate intimate mixing of the hot solids and the vacuum gas oil occurs in the reactor and cracking proceeds immediately.
- the temperature of the solids entering the reactor is in the range of 954 ° C (1750 ° F).
- the vacuum gas oil is delivered to the reactor at approximately 371 ° C (700 ° F).
- the solids to feed weight ratio is 5 to 60, and the reaction proceeds at 816 ° C (1500 ° F) for a residence time of about 0.05 to 0.50 seconds, preferably from 0.20 to 0.30.
- the product gases are separated from the solids in separator 8 (best seen in FIGURE 3) and the product gases pass overhead through a line 22 and are immediately quenched with typical quench oil that is delivered to line 22 through line 36.
- the quenched product is passed through a cyclone 24 where entrained solids are removed and delivered through line 45 to the coker stripper 10.
- the separated solids leave the separator 8 through line 26 and pass to the stripper coker 10.
- vacuum resid from line 32 is delivered to the stripper coker 10 and is cracked by the solids which are now at a temperature of approximately 704 ° C (1300 ° F) to 871 ° C (1600 ° F).
- the weight ratio of solids to vacuum resid in the stripper coker ranges from 5 to 1 to 60 to 1.
- the vacuum resid is elevated to a temperature of 510 ° C-677 ° C (950 ° F-1250 ° F).
- the vaporized product from the vacuum resid is taken ouverhead through line 30 and either delivered for processing in line 34 or taken directly out of the system through line 42.
- the solids which have accumulated coke in both the tubular reactor 6 and the stripper coker 10 are passed to the entrained bed heater 16 and combusted with air delivered to the system through line 44 to provide the heat necessary for thermal regenerative cracking in the reactor 6.
- the reactor feeder 4 of the TRC processing system is particularly well suited for use in the system due to the capacity to rapidly admix hydrocarbon feed and particulate solids.
- the reactor feeder 4 delivers particulate solids from a solids receptacle 70 through vertically disposed conduits 72 to the reactor 6 and simultaneously delivers hydrocarbon feed to the reactor 6 at an angle into the path of the particulate solids discharging form the conduits 72.
- An annular chamber 74 to which hydrocarbon is fed by a toroidal feed line 76 terminates in angled openings 78.
- a mixing baffle or plug 80 also assists in effecting rapid and intimate mixing of the hydrocarbon feed and the particulate solids.
- edges 79 of the angled openings 78 are preferably convergently beveled, as are the edges 79 at the reactor end of the conduits 72.
- the gaseous stream from the chamber 74 is angularly injected into the mixing zone and intercepts the solids phase flowing from conduits 78.
- a projection of the gas flow would form a cone shown by dotted lines 77, the vortex of which is beneath the flow path of the solids.
- ratio of shear surface to flow area (S/A) of infinity defines perfect mixing; poorest mixing occurs when the solids are introduced at the wall of the reaction zone.
- the gas stream is introduced annularly to the solids which ensures high shear surface.
- penetration of the phases is obtained and even faster mixing results.
- mixing is also a known function of the L/D of the mixing zone. A plug creates an effectively reduced diameter D in a constant L, thus increasing mixing.
- the plug 80 reduces the flow area and forms discrete mixing zones.
- the combination of annular gas addition around each solids feed point and a confined discrete mixing zone greatly enhances the conditions for mixing.
- the time required to obtain an essentially homogenous reaction phase in the reaction zone is quite low.
- this preferred method of gas and solids addition can be used in reaction systems having a residence time below 1 second, and even below 100 milliseconds. Because of the environment of the reactor 6 and reactor feeder 4, the walls are lined with an inner core 81 of ceramic material. The detail of the reactor feeder is more fully described in United States Letters Patent No. 4,388,187, which is incorporated herein by reference.
- the separator 8 of the TRC system seen in FIGURE 3, can also be relied on for rapid and discrete separation of cracked product and particulate solids discharging from the reactor 6.
- the inlet to the separator 8 is directly above a right angle corner 90 at which a mass of particulate solids 92 collect.
- a weir 94 downstream from the corner 90 facilitates accumulation of the mass of solids 92.
- the gas outlet 22 of the separator 8 is oriented 180 ° from the separator gas-solids inlet 96 and the solids outlet 26 is directly opposed in orientation to the gas outlet 22 and downstream of both the gas outlet 22 and the weir 94.
- centrifugal force propels the solid particles to the wall opposite inlet 96 of the chamber 93 while the gas portion having less momentum, flows through the vapor space of the chamber 93.
- Solids impinging upon the bed 92 are moved along the curvilinear arc to the solids outlet 95, which is preferably oriented for downflow of solids by gravity.
- the exact shape of the arc is determined by the geometry of the particular separator and the inlet stream parameters such as velocity, mass flowrate, bulk density, and particle size.
- separator efficiency defined as the removal of solids from the gas phase leaving through outlet 97 is, therefore, not affected adversely by high inlet velocities, up to 45,75 m/s (150 ft./sec), and the separator 8 is operable over a wide range of dilute phase densities, preferably between 1,6033 kg/m 3 and 160,33 kg/m 3 (0,1 lbs./ft3 and 10,0 lbs./ft 3 ).
- the separator 8 of the present invention achieves efficiences of about 80%, although the preferred embodiment can obtain over 90% removal of solids.
- the height of the flow path H should be at least equal to the value of Di, or 101,6 mm (4 inches) in height, whichever is the greater.
- Practice teaches that, if H is less than D; or 101,6 mm (4 inches), the incoming stream is apt to disturb the bed solids 92, thereby re-entraining solids in the gas product leaving through outlet 97.
- H is on the order of twice D;, to obtain even greater efficiency. While not otherwise limited, it is apparent that too large an H eventually merely increases residence time without substantive increases in efficiency.
- the width W of the flow path is preferably between 0.75 and 1.25 times Di most preferably between 0.9 and 1.10 Di.
- Outlet 97 may be of any inside diameter. However, velocities greater than 22,875 m/s (75 ft./sec) can cause erosion because of residual solids entrained in the gas.
- the inside diameter of outlet 97 should be sized so that a pressure differential between the stripping vessel 10 shown in FIG. 1 and the separator 8 exist such that a static height of solids is formed in solids outlet line 26.
- the static height of solids in line 26 forms a positive seal which prevents gases from entering the stripping vessel 10.
- the magnitude of the pressure differential between the stripping vessel 10 and the separator 8 is determined by the force required to move the solids in bulk flow to the solids outlet 95 as well as the height of solids in line 26. As the differential increases the net flow of gas to the stripping vessel 10 decreases. Solids, having gravitational momentum, overcome the differential, while gas preferentially leaves through the gas outlet.
- FIG. 4 shows a cutaway view of a the separator along section 4-4 of FIG. 3. It is essential that longitudinal side walls 101 and 102 should be rectilinear, or slightly arcuate as indicated by the dotted lines 101a and 102a.
- the flow path through the separator 8 is essentially rectangular in cross section having a height H and width W as shown in Fig. 4.
- the embodiment shown in FIG. 4 defines the geometry of the flow path by adjustment of the lining width for walls 101 and 102.
- baffles, inserts, weirs or other means may be used.
- the configuration of walls 103 and 104 transverse to the flow path may be similarly shaped, although this is not essential.
- the separator shell and manways are preferably lined with erosion resistent linings 105, which may be required if solids at high velocities are encountered.
- Typical commercially available materials for erosion resistent lining include Carborundum Precast Carbofrax D, Carborundum Precast Alfrax 201 or their equivalent.
- a thermal insulation lining 106 may be placed between the shell land the lining 105 and between the manways and their respective erosion resistent linings when the separator is to be used in high temperatures service. Thus, process temperatures above 1500 ° F (816 ° C) can be used.
- An atmospheric tower bottoms (ATB) having essentially 44% vacuum resid and 56% vacuum gas oil has the following composition: 28 465,8 kg (62,700 pounds) of atmospheric tower bottoms are delivered through line 3 to the vacuum tower 2. 15935,4kg (35,100 pounds) of vacuum gas oil is taken from the vacuum tower 2 to line 20 and 12 530,4 kg (27,600 pounds) per hour of vacuum resid is taken through line 32.
- the vacuum gas oil is delivered to the reactor 6 and cracked with particulate solids which have been elevated in temperature to 954 ° C (1750 ° F).
- the solids to hydrocarbon feed ratio by weight is 22.
- the 12 530,4 kg (27,600 pounds) per hour of vacuum resid is delivered to the coker 10 at approximately 343 ° C (650 ° F).
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Description
- This invention relates to the production of olefins and liquid hydrocarbon fuels from heavy hydrocarbons, and, more particularly, to the production of olefins in a thermal cracking environment.
- It has long been known that naturally occurring hydrocarbons can be cracked at high temperatures to produce olefins and liquid fuel. Both catalytic and non-catalytic cracking processes exist to produce olefins and hydrocarbon fuel from heavy, naturally occurring, hydrocarbons.
- However, as lighter hydrocarbons are consumed, the petroleum- and the petrochemical industry has had to focus on the use of heavier hydrocarbons, such as residual oils. Residual oils are customarily identified as residual, reduced crude oils, atmospheric tower bottoms, vacuum residual oils, topped crudes and most hydrocarbons heavier than gas oils. The problem with the residual oils is that they contain contaminants, such as sulphur and metals. Heavy metals are particularly troublesome in catalytic cracking operations. The heavy hydrocarbons also contain a greater abundance of coke precursors (asphaltenes, polynuclear aromatics, and the like). Coke precursors to convert to coke during the cracking operation and tend to foul the equipment and catalyst or inert particles used in the cracking process.
- Many methods have been developed to deal with the problem of cracking residual oils, generally by pretreating the residual oil before cracking. Solvent deasphalting, fluid or delayed coking or hydrotreating are residual feed pretreating processes: they are essentially carbon-rejecting processes which result in a substantial loss of feedstock. Hydrotreating typically takes a heavy toll on the economics of the processing due to the poisonous effect of the contaminants on the catalyst and on the consumption of hydrogen.
- FR-
A 2 247 527 discloses a process in which petroleum is split into fractions by subjecting the fractions which pass above a temperature of from 350°C to 500°C to a thermal transformation by contacting with a fluidized bed of a heat-carrier held at a temperature between 500°C and 670°C, for a time from 10 to 15 s, in the presence of from 25% to 100% of steam, on a weight basis, and subsequently subjecting the fractions passing above temperatures of from 360°C to 500°C to a co-current transformation with a heat-carrier at a temperature of from 560°C to 800°C, for a time of from 0,3 s to 3,0 s, the fractions passing below a temperature of from 350°C to 500°C being so transformed as to have the transformation products reaching the fluidized bed environment. - The comparatively low temperatures ranges selected in FR-A 2 247 527 require long residence times and the use of a fluidized bed and of added steam contribute towards rendering the process cumbersome.
- EP-
A 0 026 674 discloses a thermal regenerative cracking (TRC) process using coke particles as heat-carriers, which are then centrifugally separated from the diluted mixed-phase stream of gas and solids. - Also this process is cumbersome and economically unsatisfactory.
- The objects of the present invention thus are to crack heavy hydrocarbon to produce olefins and liquid fuels, and, additionally, to crack atmospheric tower bottoms by first processing the atmospheric tower bottoms through a vacuum tower and separately cracking the vacuum oil and the vacuum resid.
- To achieve these objects, the present invention, therefore, provides: A process for the production of olefins or light hydrocarbon fuels comprising the steps of: (a) separating a heavy hydrocarbon into a light hydrocarbon fraction and a heavy hydrocarbon fraction; (b) thermally cracking the light hydrocarbon fraction with heat supplied by hot particulate solids; (c) separating the cracked product from the hot particulate solids; (d) delivering the separate particulate solids to a stripper-coker; (e) introducing the heavy hydrocarbon in the stripper-coker to produce vaporized hydrocarbon and coke; (f) combusting the coke produced in the reactor and stripper-coker to heat the particulate solids, and (g) returning the heated particulate solids to the thermal cracking reactor.
- According to a preferred embodiment of the present invention, the thermal cracking temperature is about 816°C (1500°F), the ratio of solids to light hydrocarbon by weight is between 5 and 60, and the reaction residence time is from 0,05 to 0,50 s.
- The process of the present invention is exemplarily illustrated in the accompanying drawings, wherein:
- FIGURE 1 is a schematic view of the instant process.
- FIGURE 2 is a cross-sectional elevational view of the reactor feeder in the thermal regenerative (TRC) cracking system.
- FIGURE 3 is a cross-sectional elevational view of the separator of the thermal regenerative (TRC) cracking process, and
- FIGURE 4 is a sectional view through line 4-4 of FIGURE 3.
- The process of the present invention is directed to producing olefins and liquid fuels from a heavy hydrocarbon feed. Atmospheric tower bottoms (ATB) are well suited for processing by the process of the present invention. However, any heavy feed, such as residual oil, that can be separated into a light and a heavy stream can be processed by the present invention.
- As best seen in FIGURE 1, the system is comprised essentially of a
vacuum tower 2 and a thermal regenerative cracking assembly. The thermal regenerative cracking assembly is comprised of a thermalregenerative cracking reactor 6, areactor feeder 4, aseparator 8 and acoke stripper vessel 10. The system also includes means for regenerating solids particles separated from the cracked product after the reaction. The system shows illustratively anentrained bed heater 16, atransport line 12 and afluid bed vessel 14 in which the solids can be regenerated. - In the process of the present invention, atmospheric tower bottoms are delivered through
line 3 to a conventional vacuum tower 2 (operated at about 26,66 millibar) wherein the atmospheric tower bottoms (ATB) are separated into a light overhead vacuum oil stream and a heavier bottoms vacuum resid. The vacuum gas oil is condensed and then passed throughline 20 to the thermalregenerative cracking reactor 6. - The vacuum gas oil is delivered to the
reactor 6 with hot solids particles that are passed through the reactor feeder 4 (best seen in FIGURE 2). Immediate intimate mixing of the hot solids and the vacuum gas oil occurs in the reactor and cracking proceeds immediately. The temperature of the solids entering the reactor is in the range of 954°C (1750°F). The vacuum gas oil is delivered to the reactor at approximately 371 °C (700°F). The solids to feed weight ratio is 5 to 60, and the reaction proceeds at 816°C (1500°F) for a residence time of about 0.05 to 0.50 seconds, preferably from 0.20 to 0.30. The product gases are separated from the solids in separator 8 (best seen in FIGURE 3) and the product gases pass overhead through aline 22 and are immediately quenched with typical quench oil that is delivered toline 22 throughline 36. The quenched product is passed through acyclone 24 where entrained solids are removed and delivered through line 45 to thecoker stripper 10. - The separated solids leave the
separator 8 throughline 26 and pass to thestripper coker 10. At the same time, vacuum resid fromline 32 is delivered to thestripper coker 10 and is cracked by the solids which are now at a temperature of approximately 704°C (1300°F) to 871 °C (1600°F). The weight ratio of solids to vacuum resid in the stripper coker ranges from 5 to 1 to 60 to 1. Thus, the vacuum resid is elevated to a temperature of 510°C-677°C (950°F-1250°F). The vaporized product from the vacuum resid is taken ouverhead throughline 30 and either delivered for processing inline 34 or taken directly out of the system throughline 42. - The solids which have accumulated coke in both the
tubular reactor 6 and thestripper coker 10 are passed to theentrained bed heater 16 and combusted with air delivered to the system through line 44 to provide the heat necessary for thermal regenerative cracking in thereactor 6. - The
reactor feeder 4 of the TRC processing system is particularly well suited for use in the system due to the capacity to rapidly admix hydrocarbon feed and particulate solids. As seen in FIGURE 2, thereactor feeder 4 delivers particulate solids from asolids receptacle 70 through vertically disposedconduits 72 to thereactor 6 and simultaneously delivers hydrocarbon feed to thereactor 6 at an angle into the path of the particulate solids discharging form theconduits 72. Anannular chamber 74 to which hydrocarbon is fed by atoroidal feed line 76 terminates inangled openings 78. A mixing baffle orplug 80 also assists in effecting rapid and intimate mixing of the hydrocarbon feed and the particulate solids. Theedges 79 of theangled openings 78 are preferably convergently beveled, as are theedges 79 at the reactor end of theconduits 72. In this way, the gaseous stream from thechamber 74 is angularly injected into the mixing zone and intercepts the solids phase flowing fromconduits 78. A projection of the gas flow would form a cone shown bydotted lines 77, the vortex of which is beneath the flow path of the solids. By introduing the gas phase angularly, the two phases are mixed rapidly and uniformly, and form a homogeneous reaction phase. The mixing of a solid phase with a gaseous phase is a function of the shear surface between the solids and gas phases, and the flow area. As ratio of shear surface to flow area (S/A) of infinity defines perfect mixing; poorest mixing occurs when the solids are introduced at the wall of the reaction zone. In the system of the present invention, the gas stream is introduced annularly to the solids which ensures high shear surface. By also adding the gas phase transversely through an annular feed means, as in the preferred embodiment, penetration of the phases is obtained and even faster mixing results. By using a plurality of annular gas feed points and a plurality of solid feed conduits, even greater mixing is more rapidly promoted, since the surface to area ratio for a constant solids flow area is increased. Mixing is also a known function of the L/D of the mixing zone. A plug creates an effectively reduced diameter D in a constant L, thus increasing mixing. - The
plug 80 reduces the flow area and forms discrete mixing zones. The combination of annular gas addition around each solids feed point and a confined discrete mixing zone greatly enhances the conditions for mixing. Using this preferred embodiment, the time required to obtain an essentially homogenous reaction phase in the reaction zone is quite low. Thus, this preferred method of gas and solids addition can be used in reaction systems having a residence time below 1 second, and even below 100 milliseconds. Because of the environment of thereactor 6 andreactor feeder 4, the walls are lined with aninner core 81 of ceramic material. The detail of the reactor feeder is more fully described in United States Letters Patent No. 4,388,187, which is incorporated herein by reference. - The
separator 8 of the TRC system seen in FIGURE 3, can also be relied on for rapid and discrete separation of cracked product and particulate solids discharging from thereactor 6. The inlet to theseparator 8 is directly above aright angle corner 90 at which a mass ofparticulate solids 92 collect. Aweir 94 downstream from thecorner 90 facilitates accumulation of the mass ofsolids 92. Thegas outlet 22 of theseparator 8 is oriented 180° from the separator gas-solids inlet 96 and thesolids outlet 26 is directly opposed in orientation to thegas outlet 22 and downstream of both thegas outlet 22 and theweir 94. In operation, centrifugal force propels the solid particles to the wall oppositeinlet 96 of thechamber 93 while the gas portion having less momentum, flows through the vapor space of thechamber 93. Initially, solids impinge on the wall opposite theinlet 96 but subsequently accumulate to form a static bed ofsolids 92 which ultimately form in a surface configuration having a curvilinear arc of approximately 90° of a circle. Solids impinging upon thebed 92 are moved along the curvilinear arc to thesolids outlet 95, which is preferably oriented for downflow of solids by gravity. The exact shape of the arc is determined by the geometry of the particular separator and the inlet stream parameters such as velocity, mass flowrate, bulk density, and particle size. Because the force imparted to the incoming solids is directed against thestatic bed 92 rather than theseparator 8 itself, erosion is minimal. Separator efficiency, defined as the removal of solids from the gas phase leaving throughoutlet 97 is, therefore, not affected adversely by high inlet velocities, up to 45,75 m/s (150 ft./sec), and theseparator 8 is operable over a wide range of dilute phase densities, preferably between 1,6033 kg/m3 and 160,33 kg/m3 (0,1 lbs./ft3 and 10,0 lbs./ft3). Theseparator 8 of the present invention achieves efficiences of about 80%, although the preferred embodiment can obtain over 90% removal of solids. - It has been found (see EP-
A 0 026 674, page 37,line 2 to page 38, line 24) that separator efficiency is dependent upon separator geometry, and, more particularly, the flow path must be essentially rectangular, and there is an optimum relationship between the height H and the sharpness of the U-bend in the gas flow. - It has been found that, for a given height H of the
chamber 93, efficiency increases as the 3,14 rad (1800) U-bend betweeninlet 96 andoutlet 97 is brought progressively closer toinlet 96. Thus, for a given H, the efficiency of the separator increases as the flow path decreases and, hence, residence time decreases. Assuming an inside diameter D; ofinlet 96, the preferred distance CL between the centerlines ofinlet 96 andoutlet 97 is not greater than 4,0 Di, while the most preferred distance between said centerlines is between 1,5 and 2,5 Di. - Below 1,5 Di, better separation is obtained, but difficulty in fabrication makes this embodiment less attractive in most instances. Should this latter embodiment be desired, the
separator 8 would probably require a unitary casting design becauseinlet 96 andoutlet 97 would be too close to one another to allow welded fabrication. - It has been found that the height of the flow path H should be at least equal to the value of Di, or 101,6 mm (4 inches) in height, whichever is the greater. Practice teaches that, if H is less than D; or 101,6 mm (4 inches), the incoming stream is apt to disturb the
bed solids 92, thereby re-entraining solids in the gas product leaving throughoutlet 97. Preferably, H is on the order of twice D;, to obtain even greater efficiency. While not otherwise limited, it is apparent that too large an H eventually merely increases residence time without substantive increases in efficiency. The width W of the flow path is preferably between 0.75 and 1.25 times Di most preferably between 0.9 and 1.10 Di. -
Outlet 97 may be of any inside diameter. However, velocities greater than 22,875 m/s (75 ft./sec) can cause erosion because of residual solids entrained in the gas. The inside diameter ofoutlet 97 should be sized so that a pressure differential between the strippingvessel 10 shown in FIG. 1 and theseparator 8 exist such that a static height of solids is formed insolids outlet line 26. The static height of solids inline 26 forms a positive seal which prevents gases from entering the strippingvessel 10. The magnitude of the pressure differential between the strippingvessel 10 and theseparator 8 is determined by the force required to move the solids in bulk flow to thesolids outlet 95 as well as the height of solids inline 26. As the differential increases the net flow of gas to the strippingvessel 10 decreases. Solids, having gravitational momentum, overcome the differential, while gas preferentially leaves through the gas outlet. - FIG. 4 shows a cutaway view of a the separator along section 4-4 of FIG. 3. It is essential that
longitudinal side walls lines 101a and 102a. Thus, the flow path through theseparator 8 is essentially rectangular in cross section having a height H and width W as shown in Fig. 4. The embodiment shown in FIG. 4 defines the geometry of the flow path by adjustment of the lining width forwalls walls - The separator shell and manways are preferably lined with erosion
resistent linings 105, which may be required if solids at high velocities are encountered. Typical commercially available materials for erosion resistent lining include Carborundum Precast Carbofrax D, Carborundum Precast Alfrax 201 or their equivalent. A thermal insulation lining 106 may be placed between the shell land thelining 105 and between the manways and their respective erosion resistent linings when the separator is to be used in high temperatures service. Thus, process temperatures above 1500°F (816°C) can be used. - The detail of the
separator 8 is more fully described in United States Letters Patent No. 4 288 235. - The following example illustrates the process of the present invention. An atmospheric tower bottoms (ATB) having essentially 44% vacuum resid and 56% vacuum gas oil has the following composition:
line 3 to thevacuum tower 2. 15935,4kg (35,100 pounds) of vacuum gas oil is taken from thevacuum tower 2 toline line 32. The vacuum gas oil is delivered to thereactor 6 and cracked with particulate solids which have been elevated in temperature to 954°C (1750°F). The solids to hydrocarbon feed ratio by weight is 22. - Cracking proceeds at 816°C (1500°F) for 0.20 seconds. Approximately 462,172 kg (1018 pounds) per hour for coke is produced on the particles in the
reactor 6. - The 12 530,4 kg (27,600 pounds) per hour of vacuum resid is delivered to the
coker 10 at approximately 343°C (650°F). -
Claims (10)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/587,952 US4552645A (en) | 1984-03-09 | 1984-03-09 | Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels |
DE8585201308T DE3574987D1 (en) | 1985-08-13 | 1985-08-13 | METHOD FOR CRACKING HEAVY HYDROCARBONS FOR THE PRODUCTION OF OLEFINS AND LIQUID HYDROCARBON FUELS. |
EP19850201308 EP0212007B1 (en) | 1985-08-13 | 1985-08-13 | Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19850201308 EP0212007B1 (en) | 1985-08-13 | 1985-08-13 | Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0212007A1 EP0212007A1 (en) | 1987-03-04 |
EP0212007B1 true EP0212007B1 (en) | 1989-12-27 |
Family
ID=8194049
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19850201308 Expired EP0212007B1 (en) | 1984-03-09 | 1985-08-13 | Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0212007B1 (en) |
DE (1) | DE3574987D1 (en) |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3172840A (en) * | 1965-03-09 | Light ends | ||
US2871183A (en) * | 1954-09-21 | 1959-01-27 | Exxon Research Engineering Co | Conversion of hydrocarbons |
US3019272A (en) * | 1956-08-02 | 1962-01-30 | Basf Ag | Process of thermally cracking a petroleum oil |
FR2247527A1 (en) * | 1973-10-12 | 1975-05-09 | Inst Pererabotke Nefti | Thermal cracking of petroleum fractions in coke fluidised beds - to produce unsaturates, aromatics, coke and fuel fractions |
EP0026674A3 (en) * | 1979-10-02 | 1982-01-20 | Stone & Webster Engineering Corporation | Improvements in thermal regenerative cracking apparatus and process |
US4552645A (en) * | 1984-03-09 | 1985-11-12 | Stone & Webster Engineering Corporation | Process for cracking heavy hydrocarbon to produce olefins and liquid hydrocarbon fuels |
-
1985
- 1985-08-13 EP EP19850201308 patent/EP0212007B1/en not_active Expired
- 1985-08-13 DE DE8585201308T patent/DE3574987D1/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
DE3574987D1 (en) | 1990-02-01 |
EP0212007A1 (en) | 1987-03-04 |
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