Method and apparatus for recovering catalyst from a product stream

Abstract

The present invention discloses a method for recovering catalyst from a fluidized catalytic reactor effluent, the method comprising reacting by contacting a reactant stream with a stream of a fluidized catalyst to provide a steam reactor effluent stream comprising a catalyst and a product. The steam reactor effluent stream is contacted with a liquid coolant stream to cool the steam reactor effluent stream and transfer the catalyst to the liquid coolant stream. The catalyst-depleted steam reactor effluent stream is separated from the catalyst-rich liquid coolant stream. A return catalyst stream is separated from the catalyst-rich liquid coolant stream to provide a catalyst-depleted liquid coolant stream, and the return catalyst stream is transported back to the reaction step.

Description

[0001] Priority declaration

[0002] This application claims priority to provisional application 63 / 011,634 filed April 17, 2020, which is incorporated herein in its entirety. Technical Field

[0003] The field is the recovery of catalysts from reactor effluent streams, and in particular the recovery of catalysts from fluidized catalytic reactor effluent streams. Background Art

[0004] Fluidized catalytic reactions are carried out at high temperatures using a fluidized catalyst that is free to move out of the reactor. The hot steam effluent leaving the fluidized catalytic reactor carries a load of catalyst fines, although equipment design either retains the catalyst in the reactor or removes it from the reactor effluent. Downstream equipment is required to cool the reactor effluent and remove the catalyst from it. Fluidized catalytic processes include fluidized catalytic cracking (FCC), methanol to olefins (MTO), toluene methylation (TM), and paraffin dehydrogenation (PDH). If not captured, the reactor effluent containing the catalyst may contaminate downstream equipment.

[0005] In applications, light olefin production is critical to producing enough plastics to meet global demand. PDH is a process in which light alkanes such as ethane and propane can be dehydrogenated to produce ethylene and propylene, respectively. Dehydrogenation is an endothermic reaction that requires external heat to drive the reaction to completion. In PDH, heavy hydrocarbon byproducts are produced that must be separated from the light olefin products.

[0006] Fluid catalytic cracking (FCC) is another endothermic process for producing ethylene and propylene.

[0007] In PDH and FCC reactions with fluidized catalysts, coke can be deposited on the catalyst while catalyzing the reaction. The catalyst can be regenerated in a catalyst regenerator by burning the coke from the catalyst in the presence of oxygen. The hot regenerated catalyst can then be transferred back to the reactor to catalyze the reaction.

[0008] There is a need for improved methods of recovering catalyst from reactor effluents. Fluidized catalytic systems rely on effective capture of the catalyst to maintain the catalyst within the system. Such catalyst capture methods vary depending on the application. One common capture approach is to use one or more disengagement steps in series utilizing impingement, flow redirection, and / or cyclonic separation. Cyclone dust collectors are widely used in industry and are particularly suitable for separating catalyst from fluidized media.

[0009] Cyclone dust collectors can exhibit high efficiencies, such as greater than 99.99% for particles greater than 20 microns. However, as the solid size decreases below 20 microns, the efficiency of particle capture drops rapidly. Higher cyclone dust collector capture efficiencies can be obtained at the expense of additional pressure drop. The velocities required for cyclonic separation are high, typically exceeding 20 m / s. High velocities result in additional attrition of entrained solids, thereby generating additional fines, most less than 20 μ in diameter, that are not captured by the cyclone dust collector.

[0010] Filters are very effective for capturing entrained particles. Filters can be placed directly in the fluidized catalyst discharge line as an alternative to cyclones, or as a secondary capture device downstream of cyclones. Although effective, filters are expensive and may be cost-prohibitive. Filters also introduce additional pressure drop, scaling, and plugging issues. Filters are more suitable for regenerator flue gases, where heavy hydrocarbon byproducts are not present and there is not much risk of scaling.

[0011] There is a need for improved methods for recovering catalyst particles from reactor effluent streams. Summary of the invention

[0012] A method for recovering catalyst from a fluidized catalytic reactor effluent stream is disclosed, the method comprising reacting by contacting a reactant stream with a stream of a fluidized catalyst to provide a steam reactor effluent stream comprising a catalyst and a product. The steam reactor effluent stream is contacted with a liquid coolant stream to cool the steam reactor effluent stream, wash catalyst particles, and transfer the catalyst to the liquid coolant stream. The catalyst-depleted steam reactor effluent stream is separated from the catalyst-rich liquid coolant stream. A return catalyst stream is separated from the catalyst-rich liquid coolant stream to provide a catalyst-depleted liquid coolant stream, and the return catalyst stream is transported back to the reaction step. The coolant can be a solvent that absorbs heavy hydrocarbon byproducts from the effluent stream.

[0013] The method described herein is an alternative to using a filter to directly recover solids from a fluidized catalytic reactor effluent. The benefit of the method is an efficient method for recovering catalyst from the method. The method can also simultaneously remove heavy hydrocarbon byproducts, which can promote equipment fouling and plugging. In addition, the catalyst recovery method and the fluidized catalytic dehydrogenation method require a combination of fines recycling in the method to provide a surprising synergy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawing is a schematic diagram of the method of the present disclosure.

[0015] definition

[0016] The term "communication" means that fluid flow is operatively allowed between the enumerated components, which can be characterized as "fluid communication".

[0017] The term "downstream communication" means that at least a portion of the fluid flowing to the body in the downstream communication can operatively flow from the object in fluid communication therewith.

[0018] The term "upstream communication" means that at least a portion of the fluid flowing out of the body in the upstream communication can be operatively flowed to the object in fluid communication therewith.

[0019] The term "direct communication" means that the fluid flows from the upstream component into the downstream component without passing through any other intervening container.

[0020] The term "indirect communication" means that the fluid flow from the upstream component enters the downstream component after passing through an intervening container.

[0021] The term "bypass" means that the object loses downstream communication with the bypassed body at least within the scope of the bypass.

[0022] The term "fuel gas" includes hydrocarbons, hydrogen, and mixtures thereof.

[0023] As used herein, the term "predominantly" or "majority" means greater than 50%, suitably greater than 75%, and preferably greater than 90%.

[0024] The term "tower" means one or more distillation towers for separating one or more components with different volatilities. Unless otherwise specified, each tower includes a condenser at the top of the tower for condensing a portion of the overhead stream and refluxing it back to the top of the tower, and a reboiler at the bottom of the tower for vaporizing a portion of the bottom stream and sending it back to the bottom of the tower. The feed to the tower can be preheated. The top pressure is the pressure of the overhead vapor at the vapor outlet of the tower. The bottom temperature is the liquid bottom outlet temperature. The top line and the bottom line refer to the net line from any reflux or reboil to the tower downstream of the tower. The stripping tower can omit the reboiler at the bottom of the tower, and instead provide the heating requirements and separation power for the liquefied inert medium (such as steam). The stripping tower is usually fed from the top tray and the main product is taken out from the bottom of the tower.

[0025] As used herein, the term "separator" means a vessel having one inlet and at least one overhead vapor outlet and one bottom liquid outlet, and may also have an outlet for an aqueous stream from a boot. A flash tank is a type of separator that may be connected downstream to a separator that may operate at a higher pressure.

[0026] The term "Cx" is understood to refer to molecules having the number of carbon atoms represented by the letter "x". Similarly, the term "Cx-" refers to molecules containing less than or equal to x, and preferably x and fewer carbon atoms. The term "Cx+" refers to molecules having greater than or equal to x, and preferably x and more carbon atoms.

[0027] As used herein, the term "component-rich stream" refers to a rich stream exiting a vessel having a greater concentration of a component than the feed to the vessel.

[0028] As used herein, the term "component-lean stream" means that the lean stream exiting a vessel has a lesser concentration of a component than the feed to the vessel. DETAILED DESCRIPTION

[0029] The present disclosure provides a method for cooling a hot steam reactor effluent and recovering catalyst therefrom to return to the method and apparatus. The teachings herein may be applicable to any method and apparatus utilizing a catalyst fluidized in a reactor. PDH, MTO, TM, and FCC are examples of such methods. For example, FCC catalysts are used to crack larger hydrocarbon molecules into smaller hydrocarbon molecules at approximately atmospheric pressure and 427°C (800°F) to 538°C (1000°F) and a catalyst to oil ratio of 5 to 30. MTO catalysts are used to convert oxygenates such as methanol or dimethyl ether into olefins at pressures of 200°C to 575°C and 65kPa to 500kPa (standard size). PDH catalysts are used in dehydrogenation reaction processes to catalyze the dehydrogenation of ethane and / or propane to ethylene and propylene. The PDH method will be described exemplarily to illustrate the disclosed apparatus and method. The method also has a synergistic effect with the PDH method by removing heavy hydrocarbon byproducts while removing the catalyst.

[0030] An exemplary PDH process is shown in the accompanying drawings. The reactant stream concentrated in propane in the pipeline 10 can be prepared by depropanizing the liquefied petroleum gas stream to separate the reactant stream concentrated in propane and ethane from heavier hydrocarbons. The reactant stream is preheated in a heat exchanger including a feed effluent heat exchanger and fed into the reactor 12. In the reactor 12, the reactant stream can be fed into the riser 14 and reacted by contacting with a stream of a fluidized regenerated catalyst from the conduit 16. Both the reactant stream and the stream of the fluidized catalyst travel upward to the riser 14 while catalytically converting the reactants into products. The initial separation of the product gas and the catalyst can be performed by an initial separator 24 with tangential arms that tangentially throw the catalyst and the product gas in a cylindrical protective container 26. The rotational angular movement of the product gas and the catalyst achieves the separation of the catalyst from the product gas through centripetal acceleration. The separated catalyst loses momentum and falls into the catalyst bed while the separated product gas rises in the reactor 12. The initial separator may also be a ballistic separator. Gas recovery conduit 28 carries the product gas upward to be further separated from the entrained catalyst in a device such as a cyclone 27. A steam reactor effluent stream containing a light load of residual catalyst and all gaseous products is discharged from the reactor 12 through a reactor outlet 29 in a pipeline 30. The hot product gas may be quenched downstream of the initial separation of the catalyst in the initial separator 24 in the reactor 12, such as in a gas recovery conduit 28 between the initial separator 24 and the reactor outlet 29. The quenching may occur between the initial separator 24 and the cyclone 27. The quenching medium may be delivered to the reactor 12 via a pipeline 32, such as to the gas recovery conduit 28.

[0031] The conditions in the dehydrogenation reaction may include a temperature of 500° C. to 800° C., a pressure of 40 kPa to 310 kPa, and a catalyst to oil ratio of 5 to 100. The dehydrogenation reaction may be carried out in a fluidized manner such that a gas, which may be a reactant alkane or a fluidizing inert gas, is distributed to the reactor in a manner that lifts the dehydrogenation catalyst in the reactor vessel while catalyzing the dehydrogenation of propane, ethane, and / or other hydrocarbons. During the catalytic dehydrogenation reaction, coke is deposited on the dehydrogenation catalyst so as to reduce the activity of the catalyst. The dehydrogenation catalyst must then be regenerated.

[0032] The spent dehydrogenation catalyst is transported to the regenerator 20 through the conduit 18 to burn the coke and regenerate the spent catalyst into a regenerated catalyst. The catalyst regenerator 20 includes a combustion chamber 21 and a catalyst separator 23, which separates the regenerated catalyst from the exhaust gas produced in the combustion chamber 20 when the exhaust gas enters the separation chamber 25. An oxygen supply gas is provided to the combustion chamber 21, which lifts the spent catalyst in the combustion chamber 21 into the separation chamber 25. The coke is burned off the spent catalyst by contacting with the oxygen supply gas under regeneration conditions. In an exemplary embodiment, air is used as the oxygen supply gas because air is easily available and provides sufficient oxygen for combustion. 10kg to 15kg of air is required for each kilogram of coke that burns out the spent catalyst. Exemplary regeneration conditions include a temperature in the regenerator 20 of from 500°C (900°F) to 900°C (1700°F) and a pressure of 103kPa (abs) (15psia) to 450kPa (abs) (70psia).

[0033] The regenerated catalyst is returned to reactor 12 in conduit 16. Hydrocarbon fuel may be added to the regenerator, such as via line 22, to enhance the heat generated therein.

[0034] The dehydrogenation catalyst can be any one of a variety of catalysts suitable for fluidized dehydrogenation units. The selected dehydrogenation catalyst should minimize cracking reactions and be conducive to dehydrogenation reactions. Suitable catalysts for use herein include amorphous materials or molecular sieves that can be dispersed in porous inorganic carrier materials such as silica, aluminum, zirconium or clay. Exemplary embodiments of the catalyst include crystalline silica-alumina or silica-alumina-phosphate as the main active component, matrix, binder and filler.

[0035] The matrix component may include amorphous alumina or silica, and the binder and filler provide physical strength and integrity. Silica sol or alumina sol may be used as a binder, and kaolin may be used as a filler. The catalyst particles may have a nominal diameter of 20 microns to 150 microns, with an average diameter of 70 microns to 90 microns.

[0036] The dehydrogenation catalyst may support a dehydrogenation metal. The dehydrogenation metal may be one or a combination of transition metals. A noble metal may be a preferred dehydrogenation metal; however, a IIB or IIIB metal may be a suitable dehydrogenation metal, alone or in combination with other dehydrogenation metals. Iron, tungsten, gallium, copper, zinc or zirconium, alone or in combination with each other or with a noble metal, may be a suitable dehydrogenation metal. In addition to the catalyst, a combustion promoter may also be utilized. The metal may be incorporated into the lattice structure of the molecular sieve.

[0037] The acid functionality of the catalyst should be minimized to prevent cracking and facilitate dehydrogenation. Alkali metals and alkaline earth metals may also be included in the catalyst to reduce the acidity of the catalyst. Rare earth metals may be included in the catalyst to control the activity of the catalyst. Metals may be incorporated into the catalyst at a concentration of 0.05 wt % to 10 wt %. With respect to noble metals, it is preferred to use 0.05 wt % to 2 wt % of noble metals.

[0038] The steam reactor effluent stream in line 30 includes light hydrocarbons and heavy hydrocarbon products and entrained catalyst. The catalyst is mainly catalyst fines with a maximum diameter of no more than 40μ and preferably no more than 20μ. The steam reactor effluent stream can be cooled in a cooler 15 (such as an effluent cooler) and fed to a contact cooler 34 through a cooler inlet nozzle 35. The contact cooler 34 may have a top 33 including a hemispherical top cover. The contact cooler 34 may also include a first chamber 36, an outer wall 38 and a first steam-liquid separator 42 that may be defined by the top 33 of the contact cooler 34. The cooler inlet nozzle 35 may include a nozzle located in the outer wall 38, but it may be located in the top 33 of the contact cooler. The cooler inlet nozzle 35 may be communicated with the reactor 12 downstream and feed the hot steam reactor effluent stream to the first chamber 36 and the contact cooler 34.

[0039] The contact cooler 34 includes a co-current contact of the steam reactor effluent stream and a cooling liquid. Although co-current contact is a preferred embodiment, counter-current contact can be utilized in one or more of the various contact sections. Counter-current contact increases the effectiveness of cooling and therefore allows the temperature between the reactor effluent and the quenching medium to be closer. In order to enhance the capture of catalyst fines, co-current contact is preferred. However, there may be other override issues that may exceed the benefits of co-current contact, thereby favoring counter-current contact.

[0040] The first coolant distributor 40 with an array of lower liquid nozzles is located directly above the reactor effluent inlet nozzle 35, or directly below the nozzle when the nozzle is located in the top. The lower liquid nozzle feeds the first liquid coolant stream from line 41 and sprays downward onto the hot steam reactor effluent stream to cool the hot steam reactor effluent stream. The first liquid coolant stream contacts the steam reactor effluent stream to cool the steam reactor effluent stream to its dew point while leaving it in the vapor phase. In addition, the contact also transfers the catalyst from the steam reactor effluent stream to the first liquid coolant stream to provide a catalyst-rich liquid coolant stream. In addition, the first liquid coolant stream can be a solvent that absorbs heavier hydrocarbons (such as C4+ hydrocarbons) into the solvent liquid phase while leaving C3- hydrocarbons in the vapor phase.

[0041] The first liquid coolant stream in line 41 may include a first cooling pump circulating coolant stream in line 44, a first recirculating coolant stream in line 46, and a supplemental coolant stream in line 48, which are combined to provide the first liquid coolant stream in line 41. The first liquid coolant stream may have a temperature in the range of 30°C to 65°C. The nozzle generally has a conical spray shape and a favorable droplet size distribution to maximize the capture of liquid phase particles. The nozzle may be directed downward, but additional nozzles on the first coolant distributor 40 may be directed upward on the top of the contact cooler 34 to prevent accumulation of fine catalyst particles on the top of the container.

[0042] The liquid coolant stream should be capable of selectively absorbing the heavy hydrocarbon products in the reactor effluent stream while leaving the light hydrocarbon products in the reactor effluent stream. The coolant can be a C9+ hydrocarbon stream that will be easily separated from the heavy hydrocarbon products in the reactor effluent stream. Suitable coolant streams can include streams containing C9-C11 hydrocarbons, such as a bottoms stream from a heavy aromatics column of an aromatics complex. Suitably, at least 50 wt%, and preferably at least 70% of the coolant stream comprises hydrocarbons having at least nine carbon atoms.

[0043] The amount of coolant stream pumped to the first coolant distributor 40 will be 100% to 110% of the coolant required to bring the temperature in the first chamber 36 to a temperature of 60° C. to 90° C. The nozzle will be positioned with sufficient clearance from the interior surface in the contact cooler 34 to enable the desired spray pattern to be fully formed. Typical clearances are 0.3 meters to 3 meters. The space directly below the reactor effluent inlet nozzle 35, where the coolant stream will contact the hot steam reactor effluent stream, can be referred to as a desuperheating zone 45, because the steam hot reactor effluent stream is desuperheated, but remains in the vapor phase.

[0044] In the first chamber 36, the liquid coolant stream also captures catalyst particles to transfer them into the liquid phase. The first bed 50 may be located below the desuperheating zone 45 and the reactor effluent inlet nozzle 35 to facilitate particle capture. The droplets from the first coolant distributor 40 are sized to capture catalyst particles and wet the first bed 50 to enable capture of the particles into the liquid phase. Additional coolant liquid distributors may be used to further wet the first bed 50 for particle capture.

[0045] The first bed 50 may include structured packing, which may include a grid composed of adjacent corrugated metal sheets stacked one above the other to promote circuitous travel in the bed, thereby promoting contact between the liquid and the vapor. The packing in the first bed 50 should be resistant to fouling in harsh environments. Suitable packing should have a minimum horizontal surface to minimize catalyst holdup, such as a surface area per unit volume of less than 90 m 2 / m 3 , suitably less than 70m 2 / m 3 , and preferably less than 40m 2 / m 3 Suitable structured packing may have a free volume of at least 95%. Random packing may also be used in bed 40, but it should be resistant to fouling. Typical examples of structured packing that may be used are Proflux from Koch Glitsch, Raschig GridPacking from Sulzer, and Mellagrid.

[0046] The liquid coolant sprayed onto the first bed 50 wets the packing. The coolant liquid will fully wet the packing in the first bed 50 to prevent particle accumulation and fouling in the bed. Adequate wetting of the packing will also maximize catalyst wetting and capture in the liquid phase throughout the first bed 50. The coolant stream distributor 40 and the reactor effluent inlet nozzle 35 should preferably be disposed on the same vertical side of the first bed 50, and preferably above the bed to provide a downward co-current flow in the bed in one embodiment. However, counter-current flow is also contemplated.

[0047] The coolant stream and the steam reactor effluent stream are passed together through the first bed 50 in a co-current arrangement, while separating the catalyst from the steam reactor effluent stream to reduce its catalyst loading and transferring the catalyst to the coolant stream to increase its catalyst loading. Particle transfer and additional heat exchange from the steam reactor effluent stream to the liquid coolant stream will occur in the first bed 50. The bed will also promote mixing to increase the absorption of heavy hydrocarbon products by the coolant stream, thereby increasing its heavy hydrocarbon product concentration.

[0048] In the first steam-liquid separator 42 below the first bed 50, the liquid coolant stream containing the first catalyst-rich heavy hydrocarbon-rich coolant stream with increased catalyst load is separated from the steam reactor effluent stream containing the catalyst-depleted heavy hydrocarbon-depleted steam reactor effluent stream at the bottom of the first chamber 36 with reduced catalyst load and reduced heavy hydrocarbon product concentration. The first steam-liquid separator 42 can be a chimney tray. The first steam-liquid separator 42 can have one or more flues 52, each of which includes an open vertical tube extending upward from the tray and sealed to the tray and aligned with a corresponding opening or steam channel 54 in the tray, with a top cover on the corresponding open tube. The tubes of the flue 52 allow a liquid level to be formed on the tray, which is designed to rise below the top of the open tube. The top cover on the tubes of the flue 52 prevents the descending liquid from passing through the flue and through the steam channel 54 in the tray. Typically, only the catalyst-lean, heavy hydrocarbon-lean steam reactor effluent stream takes a circuitous route through the flue 52 from the first chamber 36 through the steam passage 54 to the other vertical side of the first steam-liquid separator 42, such as below, to the outlet or downstream chamber.

[0049] The holes 56 at the periphery of the tray of the first vapor-liquid separator 42 collect the catalyst-rich heavy hydrocarbon-rich liquid coolant stream separated from the steam. The first catalyst-rich liquid heavy hydrocarbon-rich coolant stream collected in the holes is discharged from the liquid outlet of the first chamber 36 into the pipeline 58. A portion of the first catalyst-rich heavy hydrocarbon-rich liquid coolant stream is recycled through the cooler as the first cooling pump circulation coolant stream in the pipeline 44 and fed back to the first coolant distributor 40. The rest of the first catalyst-rich heavy hydrocarbon-rich liquid coolant stream is fed to the catalyst separation vessel 60 in the pipeline 62. The catalyst load and heavy hydrocarbon concentration in the first coolant stream in the liquid coolant stream fed to the first chamber 36 are determined by the ratio of the coolants added from the pipelines 44 and 46 so that the liquid coolant stream is fed to the first coolant distributor 40 in the pipeline 41. The catalyst-rich coolant stream is taken from the contact cooler at an intermediate position in the contact cooler 34.

[0050] The vapor liquid separator 52 may require agitation or flushing to prevent catalyst accumulation and disruptive operation. Additional nozzles and liquid inlet devices may be provided near the vapor liquid separator 52 to reduce the risk of particle accumulation in stagnant areas of the tray, which may otherwise cause catalyst agglomeration. The chimney tray may be tilted toward the well 56 to promote particle collection, thereby reducing the risk of disruptive operation.

[0051] The contact cooler 34 may include a second chamber 64. The catalyst-lean heavy hydrocarbon-lean reactor effluent stream enters the second chamber 64 through the steam passage 54.

[0052] A second coolant stream distributor 66 having an array of liquid nozzles is located below the steam channel 54. The lower liquid nozzle feeds the second liquid coolant stream from line 67 and sprays downward onto the catalyst-depleted heavy hydrocarbon reactor effluent stream to cool the catalyst-depleted heavy hydrocarbon reactor effluent stream. The second liquid coolant stream contacts the steam-depleted catalyst-depleted heavy hydrocarbon reactor effluent stream to cool the catalyst-depleted heavy hydrocarbon reactor effluent stream to its dew point while leaving it in the vapor phase. In addition, the contact also transfers the remaining catalyst from the catalyst-depleted heavy hydrocarbon reactor effluent stream to the second liquid coolant stream to provide a second catalyst-rich liquid coolant stream. In addition, the second liquid coolant stream can be a solvent that absorbs heavier hydrocarbons (such as C4+ hydrocarbons) into the solvent liquid phase to provide a second heavy hydrocarbon-rich liquid coolant stream while leaving C3- hydrocarbons in the vapor phase.

[0053] The second liquid coolant stream in line 67 may include a second cooling pump circulating coolant stream taken from the liquid outlet 74 of the second chamber 64. The second liquid coolant stream may have a temperature in the range of 30°C to 70°C or preferably 40°C to 65°C. The nozzle generally has a conical spray shape and a favorable droplet size distribution to maximize the capture of liquid phase particles. The nozzle may be directed downward, but additional nozzles on the second coolant distributor 66 may be directed upward on the top of the contact cooler 34 to prevent accumulation of fine catalyst particles on the top of the container.

[0054] The liquid coolant stream should be able to selectively absorb the heavy hydrocarbon products in the catalyst-depleted heavy hydrocarbon reactor effluent stream while leaving the light hydrocarbon products in the reactor effluent stream. The coolant can be a C9+ hydrocarbon stream that will be easily separated from the heavy hydrocarbon products in the reactor effluent stream. Suitable coolant streams may include streams comprising C9-C11 hydrocarbons, such as the bottoms stream of a heavy aromatics tower from an aromatics complex. Suitably, at least 50% by weight, and preferably at least 70% of the coolant stream includes hydrocarbons having at least nine carbon atoms. The second coolant stream may have the same bottom composition as the first coolant stream, and both may ultimately be supplied by the same supplementary pipeline 48.

[0055] The amount of coolant stream pumped to the second coolant distributor 66 will be 100% to 110% of the coolant required to achieve a temperature of 30°C to 70°C in the second chamber 64. The nozzle will be positioned with sufficient clearance from the interior surface in the second chamber 64 to fully form the intended spray pattern. A typical clearance is 0.3 to 3 meters.

[0056] In the second chamber 64, the liquid coolant stream also captures additional catalyst particles to transfer them into the liquid phase. The second bed 68 may be located below the steam inlet 54 and the second coolant distributor 66 to facilitate particle capture. The liquid droplets from the second coolant distributor 66 are sized to capture catalyst particles and wet the second bed 68 to enable capture of the particles into the liquid phase.

[0057] The second bed 68 may include structured packing, which may include a grid composed of adjacent corrugated metal sheets stacked one above the other to promote circuitous travel in the bed, thereby promoting contact between the liquid and the vapor. The packing in the second bed 68 should be resistant to fouling in harsh environments. Suitable packing should have a minimum horizontal surface to minimize catalyst holdup, such as a surface area per unit volume of less than 90 m 2 / m 3 , suitably less than 70m 2 / m 3 , and preferably less than 40m 2 / m 3 Suitable structured packing may have a free volume of at least 95%. Random packing may also be used in the second bed 68, but it should be resistant to fouling. Typical examples of structured packing that may be used are Proflux from Koch Glitsch, Raschig Grid Packing and Mellagrid from Sulzer.

[0058] The second liquid coolant sprayed onto the second bed 68 wets the packing. The second coolant liquid will fully wet the packing in the second bed 68 to prevent particle accumulation and fouling in the bed. Adequate wetting of the packing will also maximize catalyst wetting and capture in the liquid phase throughout the second bed 68. The second coolant distributor 66 and the steam channel 54 should be located on the same side of the second bed 68, and preferably above the bed to provide downward flow in the bed in one embodiment.

[0059] The second coolant stream and the catalyst-depleted heavy hydrocarbon reactor effluent stream are passed together in a co-current arrangement through the second bed 68, while separating the catalyst from the catalyst-depleted heavy hydrocarbon reactor effluent stream to further reduce its catalyst loading and transferring the catalyst to the second coolant stream to increase its catalyst loading. Particle transfer and additional heat exchange from the catalyst-depleted heavy hydrocarbon reactor effluent stream to the second liquid coolant stream will occur in the second bed 68. The second bed 68 will also promote mixing to increase the absorption of heavy hydrocarbon products by the second coolant stream, thereby increasing its heavy hydrocarbon product concentration.

[0060] The second liquid coolant stream obtains an increased catalyst load, thereby comprising a second catalyst-rich heavy hydrocarbon coolant stream. The catalyst-poor heavy hydrocarbon reactor effluent stream obtains a reduced catalyst load and a reduced heavy hydrocarbon product concentration, thereby producing a catalyst-poor heavy hydrocarbon steam reactor effluent stream. At the bottom of the second chamber 64, the second catalyst-rich heavy hydrocarbon coolant stream is separated from the catalyst-poor heavy hydrocarbon steam reactor effluent stream in the second steam-liquid separator 70 below the second bed 68. The second steam-liquid separator 70 can be configured to be located above the liquid outlet 74 and above the second steam channel 72 of the bottom 78 of the second chamber 64. The second catalyst-rich heavy hydrocarbon coolant stream is extracted into the pipeline 76 through the liquid outlet 74. The liquid outlet 74 can be located in the bottom 78 of the second chamber 64. The lean additional catalyst lean additional heavy hydrocarbon steam reactor effluent stream is removed at a height above the liquid outlet 74 through the second steam channel 72, thereby achieving separation of the lean additional catalyst lean additional heavy hydrocarbon steam reactor effluent stream and the rich second catalyst rich heavy hydrocarbon coolant stream. The steam channel 72 may be configured with a baffle 79 above the steam channel to ensure that the descending material must reverse direction when it is below the lower edge of the baffle before passing through the steam channel to prevent liquid from passing through the steam channel. It is also envisioned that the liquid outlet 74 may be located on the side of the second chamber 74. In the illustrated embodiment, the second chamber 90 is defined by the first steam-liquid separator 42, the outer wall 38 and the tower bottom 78.

[0061] The contact cooler 34 may operate at a pressure of 0 kPa to 50 kPa (standard size).

[0062] The second catalyst-rich heavy hydrocarbon-rich coolant stream in line 76 is split between the second coolant stream in line 67 and the final catalyst-rich heavy hydrocarbon-rich coolant stream in line 77. The second coolant stream in line 67 is cooled and pumped back to the second coolant distributor 66 to be distributed back to the second chamber 64. The final catalyst-rich heavy hydrocarbon-rich coolant stream in line 77 must be fractionated to separate the absorbed heavy hydrocarbon products from the coolant. Prior to fractionation, the final catalyst-rich heavy hydrocarbon-rich coolant stream may be fed to the first catalyst filter 80.

[0063] The first catalyst filter 80 can be a centrifuge, a hydrocyclone, a barrier filter, or other device for separating solids from liquids. In an embodiment, the catalyst filter 80 is a filter screen 81. The filter screen 81 may include a series fluid channel 82, wherein a tube basket 84 is inserted in the channel at a complementary angle to the channel. The basket 84 may have perforations that allow fluid to pass through the channel 82, but tend to capture solids discharged through the overhanging end of the basket. The first catalyst slurry stream is removed from the basket 84 in the catalyst filter 81 through pipeline 86, and the final heavy hydrocarbon-rich coolant stream enters the coolant fractionation tower 90 through pipeline 88.

[0064] By removing the bulk catalyst, the rich final heavy hydrocarbon coolant stream enters the coolant fractionation tower 90. Since it is desirable to obtain a coolant stream and a heavy product stream, the coolant fractionation tower 90 is operated to separate two fractions, one being a heavy hydrocarbon purge stream rich in heavy hydrocarbon products, including C4+ hydrocarbons in the tower top line 92 in one embodiment, and the other being a lean heavy hydrocarbon coolant stream in the tower bottom line 94. The heavy hydrocarbon purge stream is withdrawn from the top of the coolant tower 90 in the tower top line 92, condensed in the cooler and fed to the separator. A portion of the condensed heavy hydrocarbon purge stream is recycled to the coolant fractionation tower 90 as a reflux through the reflux line, and the remaining portion of the condensed heavy hydrocarbon purge stream is withdrawn through the net heavy hydrocarbon purge stream in the net tower top line 93. The heavy hydrocarbon purge stream in the pipeline 93 can be transported and fed to the regenerator 20 in the pipeline 22 to be used as a fuel to enhance the heat generated therein.

[0065] A coolant stream lean in heavy hydrocarbons is withdrawn from the coolant tower 90 through a bottom line 94, from which a portion of the bottom flows through a reboiler line and a reboiler heater and is returned for heating to the coolant tower 90. After being mixed with a supplementary coolant stream in line 44 and a first cooling pump circulating coolant stream, the remaining portion of the coolant stream lean in heavy hydrocarbons and also lean in catalyst flows through a bottom line 95 to a line 46, and is recycled to the contact cooler 34 via a line 41 as a coolant.

[0066] The coolant tower may be operated at a top pressure of 25 kPa to 50 kPa (standard size) and a bottom temperature of 200°C to 240°C.

[0067] The first catalyst-rich heavy hydrocarbon-rich liquid coolant stream in return line 62 has a heavier catalyst loading than the second catalyst-rich heavy hydrocarbon-rich liquid coolant stream in line 76 because it contacts the reactor effluent stream having a heavier concentration of catalyst. Catalyst must be removed from the first catalyst-rich heavy hydrocarbon-rich liquid coolant stream in line 62, so it is fed to the catalyst separation vessel 60.

[0068] The catalyst separation vessel 60 may include a housing and a plurality of cyclone separators 100. The first catalyst-rich heavy hydrocarbon-rich liquid coolant stream in line 62 may be fed to the cyclone inlet in the cyclone dust collector 100 disposed in the inlet chamber 102 between two tube sheets. The cyclone dust collector 100 swirls the incoming catalyst-rich coolant to centripetally separate the heavier solid catalyst particles from the lighter liquid coolant. The catalyst-poor liquid coolant stream leaves the cyclone dust collector above the inlet chamber 102 through line 104, and the catalyst return stream including the catalyst slurry leaves the cyclone dust collector below the inlet chamber 102 through line 106. The catalyst separation vessel 60 may alternatively be a filter or other similar device for separating the first catalyst-rich heavy hydrocarbon-rich liquid coolant stream into the catalyst-poor liquid coolant stream and the catalyst return stream in line 62.

[0069] The catalyst-lean liquid coolant stream in line 104 may be further filtered in filter 108 as described above for filter 80 to provide a more catalyst-lean liquid coolant stream in line 110 and a second catalyst slurry stream in line 112. After mixing with the heavy hydrocarbon-lean coolant stream in bottoms line 95, the more catalyst-lean liquid coolant stream may be cooled and returned to the contact cooler, thereby replenishing the coolant stream in line 48 to produce a first recirculating coolant stream in line 46. The first recirculating coolant stream in line 46 is mixed with the first cooling pump circulating coolant stream in line 44 to produce a first coolant stream in line 41, which is fed to the contact cooler 34 via the first coolant distributor 40.

[0070] The second catalyst slurry stream in line 112 may merge with the return catalyst stream in line 106. The return catalyst stream in line 106 supplemented with the second catalyst slurry stream in line 112 may be further supplemented with the first catalyst slurry stream in line 86 and transported back to reactor 12 via line 116.

[0071] The return catalyst stream can be returned to the reactor 12 in at least one of two ways. In one way, the return catalyst stream is delivered directly to the reactor 12. In one aspect, the return catalyst stream can be used as a quenching medium in the pipeline 32, which contacts the hot steam reactor effluent stream in the reactor 12 where the fluid catalytic reaction occurs. In this way, the control valve on the pipeline 32 is opened. When delivered to the gas recovery conduit 28, hydrocarbons will flash out the catalyst slurry in the return catalyst stream and be recovered with the steam product discharged from the reactor 12 through the reactor outlet 29 in the pipeline 30. The dried catalyst from the slurry will be separated from the gaseous product in the cyclone dust collector 27 and returned to the catalyst bed, some of which is returned to the reactor riser 14 to contact with the feed. The remaining catalyst from the bed will be returned to the regenerator 20 for regeneration and returned to the reactor 12 after regeneration. It is also envisioned that the pipeline 32 can deliver the return catalyst stream to other parts of the reactor 12.

[0072] In another approach, the return catalyst stream in line 116 is fed to the catalyst regenerator 20 before it is fed to the reactor 12. Line 118 can feed the return catalyst stream to the catalyst regenerator 20 through an open control valve thereon. Line 120, which has an open control valve thereon, preferably delivers the return catalyst stream from line 118 to the lower bed of catalyst in the catalyst regenerator 20. Alternatively, line 122, which has an open control valve thereon, delivers the return catalyst stream from line 118 to the upper collection bed of catalyst in the catalyst regenerator. However, other inlets of the catalyst regenerator 20 can receive the return catalyst stream. The hydrocarbons in the slurry can be burned in the hot regenerator, leaving regenerated catalyst, which can be returned to the reaction step in the reactor 12 through conduit 16.

[0073] The disclosed process provides a way to cool the reactor effluent from a fluidized catalytic reactor while recovering catalyst in the reactor effluent for recycle and recovering heavy hydrocarbon by-products in the reactor effluent.

[0074] Specific implementation plan

[0075] While the following is described in conjunction with specific embodiments, it should be understood that this description is intended to illustrate and not to limit the scope of the foregoing description and the appended claims.

[0076] The first embodiment of the present invention is a method for recovering catalyst from a fluidized catalytic reactor effluent, the method comprising reacting by contacting a reactant stream with a stream of a fluidized catalyst to provide a steam reactor effluent stream comprising catalyst and product; contacting the steam reactor effluent stream with a liquid coolant stream; cooling the steam reactor effluent stream; transferring the catalyst to the liquid coolant stream; separating a catalyst-depleted steam reactor effluent stream from a catalyst-rich liquid coolant stream; separating a return catalyst stream from the catalyst-rich liquid coolant stream to provide a catalyst-depleted liquid coolant stream; and conveying the return catalyst stream back to the reaction step. An embodiment of the present invention is one, any one, or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, wherein the steam reactor effluent stream comprises light hydrocarbon products and heavy hydrocarbon products, and the liquid coolant stream is a solvent, and the method further comprises absorbing the heavy hydrocarbon products into the liquid coolant stream to provide a catalyst-depleted heavy hydrocarbon reactor effluent stream and a catalyst-rich heavy hydrocarbon-rich liquid coolant stream. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, and the method further includes separating the heavy hydrocarbon purge stream from the heavy hydrocarbon-rich liquid coolant stream to provide a lean heavy hydrocarbon liquid coolant stream. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, and the method further includes recycling the lean heavy hydrocarbon liquid coolant stream to the contacting step. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, and the method further includes filtering the catalyst from the rich heavy hydrocarbon liquid coolant stream. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, and the method further includes recycling the lean catalyst liquid coolant stream back to the contacting step. An embodiment of the invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, wherein the method further comprises filtering catalyst from the catalyst-depleted liquid coolant stream prior to recycling the catalyst-depleted liquid coolant stream to the contacting step. An embodiment of the invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, wherein the catalyst-rich coolant stream is taken from the contact cooler at an intermediate position in the contact cooler.An embodiment of the invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, the method further comprising contacting the catalyst return stream with a hot steam reactor effluent stream in the reactor where the reaction step occurs. An embodiment of the invention is one, any or all of the previous embodiments in this paragraph to the first embodiment in this paragraph, the method further comprising separating a spent catalyst stream from the steam reactor effluent stream and transferring the spent catalyst stream to a regenerator, and conveying the catalyst return stream to the regenerator before conveying the catalyst return stream to the reaction step.

[0077] The second embodiment of the present invention is a method for recovering catalyst from a fluidized catalytic reactor effluent, the method comprising reacting a reactant stream on a fluidized catalyst stream to provide a steam reactor effluent stream comprising a catalyst and products comprising light hydrocarbons and heavy hydrocarbons; contacting the steam reactor effluent stream with a liquid coolant stream; cooling the steam reactor effluent stream; transferring the catalyst and absorbing the heavy hydrocarbon products into the liquid coolant stream to provide a catalyst-rich heavy hydrocarbon-rich liquid coolant stream; separating a catalyst-depleted light hydrocarbon-rich steam reactor effluent stream from the catalyst-rich heavy hydrocarbon-rich liquid coolant stream. An embodiment of the present invention is one, any one or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, the method further comprising separating a heavy hydrocarbon purge stream from the heavy hydrocarbon-rich liquid coolant stream to provide a heavy hydrocarbon-depleted liquid coolant stream. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, and the method further includes recycling the lean heavy hydrocarbon liquid coolant stream to one of the contacting steps. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, and the method further includes filtering catalyst from the catalyst-rich heavy hydrocarbon liquid coolant stream. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, and the method further includes recycling the lean catalyst liquid coolant stream back to one of the contacting steps. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, and the method further includes filtering catalyst from the lean catalyst liquid coolant stream before recycling the lean catalyst liquid coolant stream to one of the contacting steps. An embodiment of the present invention is one, any one or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, and the method further includes separating the return catalyst feed stream from the catalyst-rich liquid coolant feed stream to provide a catalyst-depleted liquid coolant feed stream, and conveying the return catalyst feed stream back to the reaction step.

[0078] The third embodiment of the present invention is a method for recovering catalyst from a fluidized catalytic reactor effluent stream, the method comprising reacting a reactant stream on a fluidized catalyst stream to provide a reactor effluent stream comprising catalyst and product; separating the steam reactor effluent stream from a spent catalyst stream; contacting the steam reactor effluent stream with a liquid stream; transferring the catalyst to the liquid stream to provide a catalyst-rich liquid stream; separating a catalyst-depleted steam reactor effluent stream from the catalyst-rich liquid stream; separating a return catalyst stream from the catalyst-rich liquid coolant stream to provide a catalyst-depleted liquid coolant stream; and contacting the return catalyst stream with the steam reactor effluent stream. An embodiment of the present invention is one, any one, or all of the previous embodiments in this paragraph to the third embodiment in this paragraph, the method further comprising absorbing a heavy hydrocarbon product into the liquid coolant stream to provide a heavy hydrocarbon-rich liquid coolant stream. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph to the third embodiment in this paragraph, and the method further includes separating the heavy hydrocarbon purge stream from the heavy hydrocarbon-rich liquid coolant stream to provide a heavy hydrocarbon stream.

[0079] Although there is no further detailed description, it is believed that those skilled in the art can make the most of the present disclosure by using the foregoing description and can easily determine the essential features of the present disclosure without departing from the spirit and scope of the present invention, and can make various changes and modifications of the present disclosure and adapt it to various usages and conditions. Therefore, the aforementioned preferred specific embodiments should be understood as merely illustrative and not to limit the rest of the present disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0080] In the foregoing, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

Claims

1. A method for recovering a catalyst from an effluent of a fluidized catalytic reactor, the method comprising: reacting by contacting the reactant stream with a stream of fluidized catalyst to provide a steam reactor effluent stream comprising catalyst, light hydrocarbon products, and heavy hydrocarbon products; contacting the steam reactor effluent stream with a liquid coolant stream in a contact cooler, wherein the liquid coolant stream is a solvent; cooling the steam reactor effluent stream; transferring the catalyst into the liquid coolant stream; absorbing the heavy hydrocarbon product into the liquid coolant stream to provide a catalyst-depleted heavy hydrocarbon-depleted reactor effluent stream and a catalyst-enriched heavy hydrocarbon-enriched liquid coolant stream; separating a catalyst-depleted, heavy hydrocarbon-depleted reactor effluent stream from a catalyst-rich, heavy hydrocarbon-rich liquid coolant stream; separating a return catalyst stream from the catalyst-rich heavy hydrocarbon-rich liquid coolant stream to provide a catalyst-depleted heavy hydrocarbon-rich liquid coolant stream; as well as The return catalyst stream is conveyed back to the reaction step.

2. The method according to claim 1, comprising: The steam reactor effluent stream is passed to the top of the contact cooler where it is contacted with a liquid coolant stream.

3. The method of claim 1 or 2, further comprising separating a heavy hydrocarbon purge stream from the heavy hydrocarbon-rich liquid coolant stream to provide a heavy hydrocarbon-depleted liquid coolant stream.

4. The method of claim 3, further comprising recycling the heavy hydrocarbon-depleted liquid coolant stream to the contacting step.

5. The method of claim 3, further comprising filtering catalyst from the heavy hydrocarbon-rich liquid coolant stream.

6. The process of claim 1 or 2, further comprising recycling the catalyst-lean liquid coolant stream back to the contacting step.

7. The method of claim 5, further comprising filtering catalyst from the catalyst-lean liquid coolant stream prior to recycling the catalyst-lean liquid coolant stream to the contacting step.

8. The process of claim 6, wherein the catalyst-rich coolant stream is withdrawn from a contacting tower at an intermediate location in the tower.

9. The process of claim 1 or 2, further comprising contacting the catalyst return stream with a hot steam reactor effluent stream in the reactor where the reacting step occurs.

10. The method of claim 1 or 2, further comprising separating a spent catalyst stream from the steam reactor effluent stream and transferring the spent catalyst stream to a regenerator, and transferring the catalyst return stream to the regenerator before transferring the catalyst return stream to the reaction step.

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