JP2009543899A - Ancillary disassembly of paraffinic naphtha using FCC unit operation - Google Patents

Abstract

Production of light hydrocarbons consisting of ethylene, propylene, butylene, and gasoline is the same as that used in an adjacent FCC unit to crack naphtha from an unused paraffinic naphtha feed stream derived from an external source Introducing the catalyst composition into an attached downflow reactor to recover the desired light hydrocarbon reaction product stream from the downflow reactor and regenerate the spent catalyst from the FCC unit Regenerate with the same regenerator used. The desired light olefinic hydrocarbon recovery efficiency is maximized by limiting the feed stream to the downflow reactor since paraffinic naphtha can be processed under relatively harsh conditions, and Minimizes the formation of unwanted by-products and suppresses the formation of coke on the catalyst.
[Selection] Figure 2

Description

  The present invention relates to an increase in production of light hydrocarbons such as ethylene, propylene and butylene, and gasoline, combined with fluid catalytic cracking treatment.

  Propylene is the second most important petrochemical raw material component after ethylene. Propylene has traditionally been obtained as a by-product of steam cracking to produce ethylene and refined fluid catalytic cracking processes to produce gasoline. The expected increase in propylene demand begins to exceed that of ethylene, which prevents existing treatments from meeting future propylene demand. To meet the anticipated market demand for propylene, a catalytic cracking treatment of paraffinic naphtha can be utilized.

  Catalytic cracking of olefinic naphtha is well known and is currently practiced in all types of FCC units that process various feedstocks. Recycled cracked naphtha from bisbreakers or cokers, FCC-derived olefinic naphtha, is easily converted to propylene using basic feedstock in an FCC reaction riser. Gasoline produced from recycle is rich in octane and aromatics. Using the FCC process without significant changes to effectively decompose light straight run (“LSR”) naphtha has never been in the prior art.

  Fluid catalytic cracking, or FCC, is well known and is a process that is extensively performed to convert heavy hydrocarbons, light oils, residues to lighter hydrocarbon fractions. In general, the cracking of hydrocarbon feedstock relies on contact with particles of catalyst fluidized by heating in a reaction zone maintained at an appropriate temperature and pressure. When heavier feeds are contacted with this hot catalyst and decomposed into lighter products, a carbon-rich deposit, commonly called coke, is formed on the catalyst and deactivates it. To do. The deactivated or spent catalyst is separated from the cracked products, and the removable hydrocarbons are separated and transferred to a regeneration vessel to produce a substantially regenerated catalyst. It is. The coke is then burned from the catalyst in the presence of air to produce a substantially regenerated catalyst. The combustion products are removed from the container as flue gas. Thereafter, the catalyst regenerated by heating is recycled to the reaction zone in the FCC unit. General FCC processing is described in US Pat. No. 5,372,704, the entire disclosure of which is incorporated by reference.

  Various methods and apparatus have been proposed to increase or expand the output of specific product streams from FCC units. In some cases, ancillary reactions and containers for other processes were provided to process specific fractions or reaction product streams. In one example, multiple reactions were provided, each using a different feedstock, to obtain a particular desired product stream.

  For example, US Pat. No. 4,090,949 describes a method for improving the quality of low quality olefinic gasoline using two reaction risers. One of them accepts a typical gas feed stream and the other is used to crack a feed stream consisting mainly of low quality olefinic gasoline. The reaction temperature is 450 ° F to 900 ° F. The ratio of catalyst to olefinic gasoline is in the range of 1 to 40 with a residence time in the range of 1 to 30 seconds.

  A process that uses multiple cracking zones in either a fluidized bed or parallel riser reactor is described in US Pat. No. 3,856,659. In one aspect of this integrated process, paraffinic naphtha feed from unpurified units is mixed with recycled cracked naphtha (olefin) and fed to one of the riser reactors. Typical run temperatures are 900 ° F to 1,300 ° F, catalyst / oil ratio used is 3 to 20, and residence time is 1 to 10 seconds.

  A process using a plurality of flow reaction systems separated in an upwardly extending transfer line or riser is disclosed in US Pat. No. 4,297,203. The cracked naphtha feed from the first riser reactor is recovered and recycled to the second riser along with another hydrocarbon feed. The reaction temperature is somewhat lower than in the previous example.

  A method for improving or cracking the quality of unused naphtha using a single catalyst of Y-type zeolite or a combination of Y-type and ZSM-5-type zeolite is disclosed in US Pat. No. 4,830,728. In the process, ethylene is mixed with unused naphtha in a riser reactor. The treatment also refers to improving the quality of straight-run naphtha and is mixed with the recycled cracked feed and put into a separate upflow riser reactor. Is done. The purpose of the treatment is to improve the quality of naphtha using light oil and / or residual oil cracked by catalyst in the first riser in two riser reaction zones, and naphtha recycle broken down by ethylene and catalyst and Or improving the quality of other naphtha cracked by the catalyst in the second riser and dense flow reactor.

  US Pat. No. 5,372,704 describes a spent catalyst for limited conversion to lighter products while increasing the octane number of FCC naphtha or other heat-generated olefinic naphtha in a recracking reactor. A method of using is disclosed. The temperature at which the treatment is performed is relatively gentle, the temperature ranges from 800 ° F. to 1,100 ° F., and the residence time is 1 to 100 seconds.

  Like the other prior art, the above patent disclosure also describes unused paraffins using FCC units to produce primarily light olefins consisting of ethylene, propylene and butylene, and gasoline. The process by which the raw naphtha stream is broken down is not specified.

  Accordingly, it is an object of the present invention to use an unused paraffinic system recovered as a fraction from an external source such as an atmospheric distillation column or topper of crude oil and as a by-product stream from a hydrotreater or hydrocracker unit To provide a process that further decomposes a naphtha feed stream, or other highly paraffinic naphtha stream from an extraction process, to provide a light reaction product stream.

  A further object of the present invention is to provide a process that can be carried out efficiently utilizing the same catalyst used in the FCC unit.

  Another object of the present invention is to provide a novel process for efficiently cracking paraffinic naphtha feedstock in order to produce lighter hydrocarbon product streams consisting of ethylene, propylene, butylene and gasoline. Each reaction product stream is collected individually and further fractionated to recover individual components for further fractionation or combined with the effluent stream from the FCC unit for further fractionation.

  “Paraffinic naphtha feedstock” is a hydrocarbon feedstock that contains almost no olefinic components and has a range of 40% to 80% pentane (C5) hydrocarbons in paraffinic components when boiled to approximately 450 ° F. Will be understood to include. The remaining components are naphthene, aromatic compounds, and olefins in the order of component content. The paraffinic naphtha feedstock is usually derived from crude oil or other atmospheric fractionation columns, as well as from other processes that produce paraffin-containing hydrocarbons. Hydroprocessing known in the refining and petrochemical arts produces paraffinic hydrocarbons from olefin-aromatic feed streams that can be used in the practice of the invention. It is understood that “paraffinic naphtha” also includes light straight run (LSR) naphtha, or unused naphtha, such as from a crude distillation unit. It is also understood that highly paraffinic naphtha raw materials obtained as a result of extraction processing, which are well known in the art, are also included.

  The above objectives and further advantages are achieved by the improved process and apparatus of the present invention in which a download flow fluidized catalyst reactor is added to an existing FCC unit operation as an attached reactor. . The attached downflow reactor system utilizes the same regenerated catalyst containing heat as used in the FCC unit. An unused paraffinic naphtha feed stream derived from a source different from the regenerated catalyst and FCC unit is introduced to the top of the downflow reactor located on the reaction zone and thoroughly mixed.

  The mixture passes through a reaction zone with an operating temperature of 900 ° F. to 1200 ° F. with a residence time of 0.1 seconds to 5 seconds, preferably 0.2 seconds to 2 seconds. The ratio of catalyst to naphtha in the reaction zone, in other words, the ratio of catalyst to oil, is in the range of 10 wt% to 80 wt%, and the preferred operating range is 20 wt% to 50 wt%. The measurement of the catalyst to oil ratio indicates the operating severity and the measurement is well known in the art.

  Efficient implementation of the process relies on the introduction of a single feed stream consisting of unused paraffinic naphtha feed. The relatively short residence time and the higher ratio of catalyst to oil that is 20% to 50% by weight are typical of paraffinic naphtha feed streams. The introduction of other hydrocarbons into the feed stream of the second downflow reactor will adversely affect the yield of light hydrocarbon reaction products.

  A downflow reactor has several advantages, including the relative ease of separating the desired end product from other components.

  For conventional FCC units in any case using riser cracking or bed cracking in an upper or lower flow reaction scheme to convert naphtha to the desired light hydrocarbons by catalyst. Improved processing can be utilized.

Existing FCC catalysts can be utilized in the implementation of the improved process of the present invention.
Typical FCC catalysts with or without catalyst additives are suitable for use in improving the process.

FIG. 1 is a diagram showing an outline of a conventional typical FCC apparatus. FIG. 2 shows an overview of an embodiment of the apparatus and method of the present invention.

  The apparatus and method of the present invention will be described in more detail with reference to the drawings.

  As mentioned above, the method and apparatus according to the present invention can be used with many FCC processing units known in the prior art. FIG. 1 shows an outline of a typical prior art FCC process. In the reaction vessel, hydrocarbon, oil, or raw material (12) is introduced from the lower end of the reaction riser (14) and mixed with the unused or regenerated catalyst conveyed by the conduit (22). Is done. In order to simplify the figures and description, many valves, temperature sensors, electronic controls, etc., conventionally used and well known to those skilled in the art are not included.

  In the continuous process, the mixture of catalyst and FCC reaction feed stream moves upward to the reaction zone via the riser. The temperature, pressure, and residence time of the reaction zone may vary depending on the standard, one or more catalysts in the process, equipment configuration, feed type and characteristics, and various other well known to those skilled in the art It is controlled again within the range of the parameter action characteristics. These do not form part of the present invention. The reaction product is recovered via conduit (16) for recovery and / or further processing in the refinery.

  Spent catalyst from the FCC is recovered via a transfer line (18) for delivery to the lower part of the regenerator (20). In most cases, the regenerator (20) is provided at a position relatively close to the FCC unit (10). The spent catalyst input via the transfer line (18) contacts at least the air stream introduced via the conduit (24) for controlled combustion of the deposited coke. Combustion gas is removed from the regenerator by conduit (26). Also, the temperature of the regenerated catalyst is raised to provide heat in the endothermic decomposition reaction in the reactor (10).

  The method of the present invention will be described with reference to FIG. It will be appreciated that the reactor (10) and the regenerator (20) include a common configuration as shown in FIG. Therefore, those descriptions and functions will not be repeated. The novel apparatus and method of implementation shown in FIG. 2 relates to a downflow reactor (30) into which the regenerated catalyst is introduced by being introduced into the upper part of the vessel (30) by means of a transfer line (28). The feed line (32) introduces paraffinic naphtha from a different source than the FCC unit for mixing with the regenerated catalyst coming from the regenerator (20). The mixture of naphtha and catalyst passes through a reaction zone (34) where the temperature is maintained in the range of 900 ° F to 1200 ° F. The catalyst to naphtha ratio ranges from 20% to 50% by weight. The residence time of the mixture in the reaction zone is approximately 0.2 to 2 seconds.

  Various catalysts can be used in the process, but the same catalyst used in the main FCC unit may also be used in the catalytic cracking of the paraffinic naphtha feed stream in the downflow reactor (20). Will be understood. In the practice of the present invention, it is preferred that the Y-type zeolite catalyst is used alone or in combination with a ZSM-5 type catalyst. As will be appreciated by those skilled in the art, catalyst additives can also be used for any of these systems. The choice of catalyst system does not form part of the present invention.

  As shown in FIG. 2, a light reaction product stream is recovered via line (34). According to the process of the present invention, light hydrocarbon reaction products including ethylene, propylene, butylene, gasoline and other by-products from cracking reactions are recovered. It may then be separated and recovered in a separate recovery section (not shown) or combined with the reaction product stream from the FCC unit for further fractional distillation and final recovery.

  Separating steam is introduced from line (36) to remove the removable hydrocarbons from the spent catalyst. These gases are discharged from the downflow reactor (30) and introduced into the upper part of the stripper vessel (37). These gases are discharged from the downflow reactor (30) and introduced into the upper part of the separator (37). It is then mixed with gas or vapor and passes out of the separator through a cyclone separator (39) and line (34) for product recovery based on methods well known in the art.

  Spent catalyst from the downflow reactor (30) is discharged through the transfer line (40) and extends from the lower side of the modified catalyst regenerator (20), or a dip tube or lift riser (29) It is introduced into the lower end of. In this embodiment, air is introduced from below the spent catalyst transfer line (40) at the end of the dip tube or lift riser via a pressurized air line (25). A more detailed description of the function of the second downflow reactor (30) is given below.

  The material composition and selection of the downflow reactor (30) depends on the nature and flow rate of the paraffinic naphtha feed introduced into the feed line (32) as well as the specific operating characteristics and parameters, and the feed source Depends on. More detailed operational characteristics are described below.

The present invention relates to a method for producing a product stream consisting of light olefins, primarily ethylene, propylene and butylene, and gasoline, using crude feedstock processing in a fluid catalytic cracking (FCC) unit comprising a catalyst of a specific composition. Inclusion will be widely understood. The catalyst feedstock of the FCC and the connected downstream reactor is regenerated from the spent catalyst, and the method comprises:
providing a separated paraffinic naphtha feed stream and directing it to the top of the downflow reactor adjacent to the FCC unit;
b. Regenerated with the same identity as that used in the FCC unit in the downflow reactor for mixing with the paraffinic naphtha feed stream in a ratio of catalyst to feed stream ranging from 10 wt% to 80 wt%. Introducing a catalyst;
c. Reaction zone in a downflow reactor in which the catalyst and paraffinic naphtha mixture is maintained in the range of 900 ° F. to 1200 ° F. with a residence time of 0.1 second to 5 seconds to decompose the naphtha. Passing;
d. Separate spent catalyst from the reaction product stream containing light olefins and gasoline, and:
e. recovering the reaction product stream; and
f. Transfer spent catalyst from the downflow reactor to a separate regenerator that also contains the spent catalyst from the FCC unit for regeneration and recycling to the FCC unit and downflow reactor.

  As shown in FIG. 2, the regenerated catalyst containing heat, which is approximately 1250 ° F. to 1500 ° F., is transferred from the FCC process regenerator (20) by conventional means, eg, a normal transfer line or standpipe. Is transferred to a recovery well or hopper (31), which is the upper end of the downflow reactor above the reaction zone (33) by a conduit or pipe (28) leading downward. This makes it possible to stabilize the heat-containing catalyst flow in order to lead uniformly to the raw material input part of the mixing zone or reaction zone. The pressure stabilization line (38) connects the upper end of the recovery well to the existing regenerator (20).

The naphtha raw material is charged into the mixing zone via the raw material charging / nozzle (32a) disposed in the vicinity of the regenerated catalyst introduction portion into the downflow reactor (30). These multiple injection nozzles (32a) thoroughly mix and homogenize the catalyst and oil. When the paraffinic naphtha raw material comes into contact with the heat-containing catalyst, a decomposition reaction occurs. The reaction steam of hydrocarbon cracking products and the mixture of unreacted naphtha feed and catalyst are passed through the remainder
) Through the rapid separator (35) in the lower part of the reactor. The residence time of the mixture in the reaction zone is controlled according to equipment and methods known in the art.

  If temperature control is required, quenching near the bottom of the reaction zone (33) just prior to the separation, for naphtha feed, recycled cracked naphtha or other light olefinic hydrocarbons A quench injection is provided. The quenching input section can be used for rapidly controlling or stopping the decomposition reaction, controlling the degree of decomposition severity, and adding flexibility to the processing.

  The reaction temperature, in other words, the outlet temperature of the downflow reactor, is controlled by opening and closing a catalyst slide valve (not shown) that controls the flow of the regenerated catalyst from the recovery well (31) to the mixing zone. The heat required for the endothermic decomposition reaction is supplied by the regenerated catalyst. By varying the flow rate of the regenerated catalyst containing heat, the operating severity and cracking conditions can be controlled to produce the desired yield of light olefin hydrocarbons and gasoline.

  The rapid separator (35) provided along the end of the downflow reactor (30) is accommodated in an upper part of a large container called a catalyst separation part (37). The rapid separator directs the vapor and catalyst from the reaction directly to the upper end portion of the separator (37).

  The reaction vapor stream moves upward from the discharge portion of the rapid separator to the separation portion, mixes with the released hydrocarbon product vapor, deprives the catalyst separation portion of the vessel, and is conventional like a cyclone (39). After passing through the separation means, further mixed catalyst particles are separated from the vapor. The catalyst from the cyclone recovered separator is led to the bottom of the separator via a cyclone dipleg for release to the bed of catalyst recovered from the rapid separator in the separator. It is burned.

  After the mixed steam passes through the cyclone and is discharged from the separator, it is led to a conventional product recovery section known in the FCC field via a conduit or pipe, commonly referred to as a reaction steam line (34).

  Catalyst from the rapid separator and cyclone dipleg flows to the bottom of a separation reactor (37) containing a catalyst separation section into which a suitable separation gas, such as steam, is introduced via a steam line (36). The separation section is provided with several baffles or structured packing (not shown), and allows the catalyst that flows downward to flow in the direction opposite to the separation gas that flows. The upwardly separated separation gas, typically steam, is used to “separate” or remove excess hydrocarbons remaining between the catalyst pores or catalyst particles.

  The separated catalyst is fed by a combustion air stream (25) to a lift riser (29) that terminates an existing regenerator (20) in a typical FCC process for burning coke, a byproduct of the naphtha cracking process. Be transported. In the regenerator, the coke combustion and downflow reactor (30), a byproduct produced in the first reaction zone (10 and 14) of a typical FCC process from heavy hydrocarbons to be cracked. The heat generated from the decomposition of naphtha in zone (33) is converted to a catalyst.

  The regenerator (20) can be of conventional known design and can be used with the improved processing and downflow reaction zone of the present invention. The installation of the conduit between the regenerator and the reactor or the transfer line for the recovered catalyst for the regenerator is a substantial amount of the regenerated catalyst required to meet the maximum use requirements of the downflow reactor. Installed to ensure a stable and continuous flow.

  Catalyst requirements for the treatment of the present invention include catalysts conventionally used in FCC treatments such as zeolites, silica-alumina, carbon monoxide combustion promoting additives, residual oil cracking additives, light olefin production additives and To be determined in relation to other additives commonly used in FCC processing. Preferred cracked zeolites in FCC treatment are Y-type, REY-type, USY-type, and RE-USY-type zeolite. The preferred shaped selected catalyst additive typically used in FCC processing for light olefin production and FCC gasoline octane increase is ZSM-5 zeolite crystals or other pentazyl-type zeolite structures. . The ZSM-5 additive mixed with cracked catalyst zeolite and the matrix structure in conventional FCC catalyst are used in the process of the present invention to maximize and optimize the degradation of paraffinic naphtha in the downflow reactor. It is preferable.

  A particular advantage of the present invention over existing FCC processes for typical FCC heavy hydrocarbon feeds is the amount of coke produced from these cracking reactions. In naphtha cracking, the overall unit operational efficiency is adversely affected by the limited amount of coke produced during the cracking reaction. The amount of coke produced to cause the paraffinic naphtha cracking reaction in the downflow reactor is not sufficient to produce enough heat to allow regeneration of the catalyst. In comparison, the coke produced during heavy oil or light oil cracking in a typical FCC process is more than sufficient to supply the heat required for the downflow reactor. In the method of the invention, the heat is transferred from the regenerator to the downflow reactor by the regenerated catalyst by mixing spent catalyst from the two sources during the regeneration process in the container (20). Transferred.

  A further advantage of the present invention as an improvement over existing FCC processes for co-processing of paraffinic naphtha is that the product can be recovered in the existing recovery section of the unit. Unconverted paraffinic naphtha can be recycled with olefinic naphtha in FCC processing to produce additional lighter olefins from the cracking of olefinic naphtha and used as a blend of the gasoline produced can do. The process combines two sequences for partial recirculation to the FCC unit or for gasoline mixing and separate recovery of naphtha from each reactor for further separated downstream processing. It has the advantage that it can be provided.

  A bench scale pilot plant was used to determine the operating conditions to obtain the desired product yield from the decomposition of a typical paraffinic naphtha feed. A pilot plant unit was used to represent the cracking conditions in the downflow reactor.

  In the following examples, two catalyst systems were utilized to demonstrate the ability to crack paraffinic naphtha to produce light olefins. The first catalyst is a commercially available, low hydrogen transfer USY zeolite catalyst that is a typical low rare earth. As the second catalyst, the same commercially available USY zeolite cracking catalyst mixed with a shape selective ZSM-5 zeolite cracking catalyst additive was used.

  The following table summarizes the effect of changing the cracking severity by changing the reaction temperature in the pilot plant for both catalyst systems.

  “Selectivity” used in the table is defined as the ratio of the amount of a particular component to the total gas, eg propylene / total gas.

  It will be understood that the embodiments described above are illustrative of the invention and that various modifications may be made by those skilled in the art without departing from the scope of the invention as determined by the following claims of the invention. Will.

Claims (15)

A method of facilitating the conversion of a paraffinic naphtha feed stream derived from a crude oil distillation unit into a light hydrocarbon product stream comprising ethylene, propylene, butylene and gasoline,
a. directing the separated paraffinic naphtha feed stream to a downflow reactor containing fresh catalyst or regenerated catalyst having the same composition as the catalyst used in the connected FCC unit;
b. The residence time of the feed stream in the reaction zone with an operating temperature of 900 ° F to 1200 ° F is 0.1 seconds to produce light hydrocarbon reaction products by cracking the paraffinic naphtha feed stream. 5 seconds and operating the downflow reactor so that the catalyst to raw material ratio is 10% to 80% by weight,
c. separating the light hydrocarbon reaction product stream produced in the cracking process in the downstream reactor from the spent catalyst downstream in the reaction zone;
d. A method for recovering a light hydrocarbon reaction product stream.   The method of claim 1, wherein the downflow reactor is operated such that the feed stream residence time is in the range of 0.2 to 2 seconds.   The process according to claim 1, wherein the ratio of the catalyst to the feed stream is from 20% to 50% by weight.   The process of claim 1, wherein the recovered light hydrocarbon reaction product stream from the downflow reactor is subjected to fractionation.   The method of claim 1, wherein the recovered light hydrocarbon reaction product stream from the downflow reactor is combined with an effluent stream from the FCC unit for fractional distillation.   Mixing spent catalyst from the downflow reactor in combination with spent catalyst from the FCC unit and regenerating the combined spent catalyst for reuse in the FCC unit and the downflow reactor. The method of claim 1 comprising:   The method according to claim 6, which is carried out continuously.   The method of claim 1, wherein the hydrocarbon reaction product stream is separated from the spent catalyst by a cyclone separator process.   The method of claim 1 comprising applying a fluid quench treatment to the reaction product and catalyst below the reaction zone.   The process of claim 1 comprising stripping the downstream stream of spent catalyst in the reaction zone. A process for producing a product stream consisting of light olefins and gasoline, mainly ethylene, propylene and butylene, using the treatment of crude feed in a fluid catalytic cracking (FCC) unit comprising a catalyst of a predetermined composition comprising the FCC The catalyst raw material is regenerated from the spent catalyst,
introducing a separated paraffinic naphtha feed stream at the top of the downflow reactor adjacent to the FCC unit;
b. Regenerated with the same identity as that used in the FCC unit in the downflow reactor for mixing with the paraffinic naphtha feed stream in a ratio of catalyst to feed stream in the range of 10 wt% to 80 wt%. Introducing a catalyst;
c. passing the catalyst and paraffinic naphtha mixture through a reaction zone in a downflow reactor maintained at a temperature in the range of 900 ° F. to 1200 ° F. with a residence time of 0.1 seconds to 5 seconds; ;
d. separating the resulting light olefin and gasoline reaction product stream from the spent catalyst;
e. recovering the reaction product stream; and
f. A method of transferring spent catalyst from a downflow reactor to a separate regenerator that also contains spent catalyst from the FCC unit for regeneration.   12. The method of claim 11, wherein the downflow reactor is operated such that the feed stream residence time ranges from 0.2 seconds to 2 seconds.   12. A process according to claim 11 wherein the ratio of catalyst to feed stream is 20% to 50% by weight.   The method of claim 11, wherein the recovered reaction product stream from the downflow reactor is combined with an effluent stream from the FCC unit for fractional distillation.   The method of claim 11, wherein the recovered reaction product stream from the downflow reactor is subjected to fractional distillation.

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