CN112789345A

CN112789345A - Process for maximizing production of heavy naphtha from a hydrocarbon stream

Info

Publication number: CN112789345A
Application number: CN201980063654.XA
Authority: CN
Inventors: K·玛尼; D·比什特; K·P·贾达翁; N·古普塔; A·博塞; S·M·班纳吉; 拉贾拉曼·潘卡帕克森
Original assignee: UOP LLC
Current assignee: Honeywell UOP LLC
Priority date: 2018-09-29
Filing date: 2019-09-28
Publication date: 2021-05-11
Also published as: US20200102510A1; WO2020069469A1

Abstract

The present invention provides a process and apparatus for maximizing the production of heavy naphtha from a hydrocarbon stream. The process includes providing a hydrocarbon feedstream comprising vacuum gas oil to a first hydrocracking reactor. The hydrocarbon feed stream is hydrocracked at first hydrocracking conditions including a first hydrocracking pressure to provide a first hydrocracked effluent stream therein. At least a portion of the first hydrocracking effluent stream is fractionated in a fractionation column to provide a heavy naphtha fraction. The kerosene stream is hydrocracked in a second hydrocracking reactor operated at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream. In one aspect, the first hydrocracking pressure may be at least 6895kpa (g) greater than the second hydrocracking pressure. At least a portion of the second hydrocracking effluent stream is passed to a fractionation column to maximize the production of heavy naphtha.

Description

Process for maximizing production of heavy naphtha from a hydrocarbon stream

Technical Field

The art is particularly concerned with a process and apparatus for maximizing heavy naphtha production. More particularly, the technical field relates to hydrocracking of kerosene to maximize the production of heavy naphtha.

Background

Currently, demand for petrochemicals is increasing, and refineries are striving to maximize the production of petrochemicals. With the regulation of asian countries such as india on the use of LPG as a domestic fuel, the demand for kerosene has decreased. Furthermore, kerosene has limited application as a fuel or blend, and refining kerosene alone has economic limitations. Thus, refineries are looking for alternative uses for waste kerosene streams.

Heavy naphtha is used primarily as a petrochemical feedstock for operating aromatics complexes and naphtha crackers and produces more valuable petrochemicals. However, as the demand for heavy naphtha increases, refiners are looking for alternative methods to obtain heavy naphtha from less valuable hydrocarbons to produce more valuable products. Integrated refineries with petrochemical complexes are increasingly concerned with added value in the yield of olefins and aromatics from a barrel of crude oil.

Kerosene is a less valuable hydrocarbon and can be an alternative to producing more valuable products. However, refineries have difficulty finding an economical method for converting waste kerosene streams.

One of the widely used applications of kerosene is its use, typically as a blending stream with a diesel stream. However, kerosene is limited for use as a blending feedstock and has economic limitations. An alternative process for converting kerosene to valuable products involves hydrocracking of the kerosene. However, providing a separate hydrocracking unit for the kerosene increases capital expenditure. Furthermore, the conversion percentages of kerosene and the product thus obtained are not within the desired values/ranges, such as lower naphthenic and mono-aromatic retention.

Accordingly, it is desirable to provide new apparatuses and processes for converting lower value kerosene streams to higher value petrochemical feedstocks. Furthermore, there is a need for an alternative process that maximizes the conversion of kerosene to heavy naphtha with improved retention of naphthenes and mono-aromatics and that can be easily integrated with existing hydrotreating integrated plants. Furthermore, other desirable features and characteristics of the present subject matter will become apparent from the subsequent detailed description of the subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the subject matter.

Disclosure of Invention

Various embodiments contemplated herein relate to methods and apparatus for upgrading a hydrocarbon feedstock. Exemplary embodiments taught herein provide a process for maximizing the production of heavy naphtha from a hydrocarbon stream.

According to an exemplary embodiment, a process for maximizing the production of heavy naphtha from a hydrocarbon stream is provided that includes providing a hydrocarbon feed stream comprising vacuum gas oil to a first hydrocracking reactor. The hydrocarbon feed stream is hydrocracked in a first hydrocracking reactor in the presence of a hydrogen stream and a first hydrocracking catalyst at first hydrocracking conditions including a first hydrocracking pressure to provide a first hydrocracking effluent stream. At least a portion of the first hydrocracking effluent stream is fractionated in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction and a diesel fraction. The kerosene stream is hydrocracked in a second hydrocracking reactor operating at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream, the first hydrocracking pressure being at least 6895kpa (g) (1000psig) higher than the second hydrocracking pressure. At least a portion of the second hydrocracking effluent stream is passed to a fractionation column to maximize the production of heavy naphtha.

According to another exemplary embodiment, a method for maximizing the production of heavy naphtha from a hydrocarbon stream includes providing a hydrocarbon feedstream comprising vacuum gas oil to a first hydrocracking reactor. The hydrocarbon feed stream is hydrocracked in a first hydrocracking reactor operated at first hydrocracking conditions including a first hydrocracking pressure in the presence of a hydrogen stream and a first hydrocracking catalyst to provide a first hydrocracking effluent stream. At least a portion of the first hydrocracking effluent stream is passed to a first separator to provide a first vapor stream and a first liquid stream. At least a portion of the first liquid stream is fractionated in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction, and a diesel fraction. The kerosene stream is hydrocracked in a second hydrocracking reactor operated at second hydrocracking conditions including a second hydrocracking pressure, the first hydrocracking pressure being greater than the second hydrocracking pressure, to provide a second hydrocracking effluent stream. The second hydrocracking effluent stream is passed to a second separator to provide a second vapor stream and a second liquid stream. The entire second vapor stream is passed to the second hydrocracking reactor. At least a portion of the second liquid stream is passed to a fractionation column to maximize production of heavy naphtha.

According to yet another exemplary embodiment, a method for maximizing the production of heavy naphtha from a hydrocarbon stream includes providing a hydrocarbon feedstream comprising vacuum gas oil to a first hydrocracking reactor. The hydrocarbon feed stream is hydrocracked in a first hydrocracking reactor operated at first hydrocracking conditions including a first hydrocracking pressure in the presence of a hydrogen stream and a first hydrocracking catalyst to provide a first hydrocracking effluent stream. At least a portion of the first hydrocracking effluent stream is fractionated in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction and a diesel fraction. The make-up hydrogen stream is compressed in the at least two-stage compressor, and a portion of the compressed make-up hydrogen stream is withdrawn from the second compressor upstream of the at least two-stage compressor. The remaining portion of the make-up hydrogen stream is further compressed in at least a two-stage compressor and passed as a hydrogen stream to the first hydrocracking reactor. Hydrocracking the kerosene stream in the presence of the portion of compressed hydrogen into a second hydrocracking reactor operating at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream comprising predominantly naphtha, the first hydrocracking pressure being greater than the second hydrocracking pressure. At least a portion of the second hydrocracking effluent stream is passed to a fractionation column to maximize the production of heavy naphtha.

It is advantageous to have two separate hydrocracking reactors and to operate the first hydrocracking reactor at a pressure greater than at least 7240kpa (g) (1000psig) to maximize conversion of kerosene to heavy naphtha with improved retention of naphthenes and mono aromatics as compared to the second hydrocracking reactor operating at a low pressure of 2758kpa (g) (400psig) bar to 6550kpa (g) (950 psig). Furthermore, the flow diagram of the present invention advantageously allows for seamless integration of the second hydrocracker with existing hydrocracker units by sharing their common asset infrastructure, such as the recycle gas compressor and the make-up hydrogen compressor.

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following detailed description, drawings, and appended claims.

Drawings

Various embodiments are described below in conjunction with the following figures.

The FIGURE is a schematic diagram of a process and apparatus for maximizing the production of heavy naphtha from a hydrocarbon stream in accordance with one exemplary embodiment.

Definition of

As used herein, the term "stream" may include various hydrocarbon molecules and other materials.

As used herein, the term "column" means one or more distillation columns for separating the components of one or more different volatile materials. Unless otherwise noted, each column includes a condenser at the top of the column to condense the overhead vapor and reflux a portion of the overhead stream to the top of the column. A reboiler at the bottom of the column is also included to vaporize and return a portion of the bottoms stream to the bottom of the column to provide fractionation energy. The feed to the column may be preheated. The top pressure is the pressure of the overhead vapor at the column outlet. The bottom temperature is the liquid bottom outlet temperature. Overhead and bottoms lines refer to the net lines to the column from the column downstream of reflux or reboil. Alternatively, the stripping stream may be used for heat input at the bottom of the column.

As used herein, the term "overhead stream" may mean a stream withdrawn from the top of a vessel (such as a column) or a line extending at or near the top.

As used herein, the term "bottoms stream" can mean a stream withdrawn from the bottom of a vessel (such as a column) or a line extending at or near the bottom.

As used herein, the term "predominantly" may mean that the amount of a compound or class of compounds in a stream is typically at least 50 mole% or at least 75 mole%, preferably 85 mole% and optimally 95 mole%.

As used herein, the term "rich" may mean that the amount of a compound or class of compounds in a stream is typically at least 50 mole% or at least 70 mole%, preferably 90 mole% and optimally 95 mole%. Broadly, the term "rich" refers to the fact that the outlet stream from the column has a greater percentage of a certain component present in the inlet feed to the column.

As used herein, the term "true boiling point" (TBP) means a test method for determining the boiling point of a material consistent with ASTM D2892 for producing liquefied gases, distillate fractions and residues of standardized quality from which analytical data can be obtained, and determining the yields of such fractions by both mass and volume, according to which a plot of distillation temperature versus mass% is obtained in a column having a reflux ratio of 5: 1 using fifteen theoretical plates.

As used herein, the term "T5" or "T95" means the temperature at which a sample, derived using TBP or ASTM D-86, boils 5 volume percent or 95 volume percent (as the case may be) respectively.

As used herein, the term "heavy naphtha" refers to hydrocarbons boiling in the range between 20 ℃ (68 ° F) and 100 ℃ (212 ° F) using the true boiling point distillation process T5, and T95 between 140 ℃ (284 ° F) and 180 ℃ (356 ° F).

As used herein, the term "kerosene" means a hydrocarbon boiling in the range between 132 ℃ and 300 ℃ using a true boiling point distillation process. Further, kerosene has a T5 boiling point of 120 ℃ to 200 ℃ and a T95 boiling point of 250 ℃ to 300 ℃.

As used herein, the term "separator" means a vessel having an 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 storage tank (boot). The flash tank is one type of separator that may be in downstream communication with the separator. The separator may be operated at a higher pressure.

As used herein, the term "transfer" includes "feeding" and "filling" and means the transfer of a substance from a tube or container to an object.

As used herein, the term "N + 2A" is considered to be the reforming index, where 'N' represents the percentage of naphthenes and 'a' represents the percentage of mono-aromatics. "N + 2A" is calculated as the volume percent of naphthenes in the naphtha plus 2 times the volume of monoaromatic hydrocarbons. Feeds with higher N +2A are better quality feeds for producing high aromatics.

As used herein, the term "substantially free" means a molar concentration of less than 1.5 mol%.

Detailed Description

The following detailed description is merely exemplary in nature and is not intended to limit the various embodiments or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. The drawings are simplified by eliminating the large number of equipment typically employed in processes of this nature, such as vessel internals, temperature and pressure control systems, flow control valves, recirculation pumps, and the like, which are not particularly required to illustrate the performance of the invention. Furthermore, the description of the method of the present invention in the embodiments of the specific figures is not intended to limit the invention to the specific embodiments described herein.

As depicted, the process flow lines in the figures may be interchangeably referred to as, for example, lines, pipes, branches, distributors, streams, effluents, feeds, products, fractions, catalysts, withdrawals, recycles, aspirates, discharges, and char dust.

Embodiments of a process for maximizing the production of heavy naphtha from a hydrocarbon stream are illustrated with reference to a process and apparatus 100 according to the embodiments shown in the figures. Referring to the figures, the process and apparatus 100 includes a hydrotreating reactor 120, a first hydrocracking reactor 130, a fractionation column 180, a second hydrocracking reactor 200, and a multi-stage compression system 300. As shown, the hydrocarbon feedstream in line 102 comprising vacuum gas oil range components can be passed to a preheater 110 to preheat the hydrocarbon feedstream to obtain a preheated feedstream in line 112. Thereafter, the preheated feed stream in line 112 can be passed to the hydrotreating reactor 120. The preheater 110 may optionally be used to reduce the heat load on the downstream hydrotreating reactor. The preheated feed stream in line 112 can be combined with the compressed hydrogen stream in line 242 to obtain a combined stream in line 114, as described in detail below. The combined stream in line 114 can be passed to a hydrotreating reactor 120 for hydrotreating in the presence of a hydrotreating catalyst to provide a hydrotreated effluent stream in line 122. The compressed hydrogen stream may include recycled and/or make-up hydrogen, and thus may include other light hydrocarbon molecules, such as methane and ethane. Alternatively, in line 102The hydrocarbon feed stream is combined with the compressed hydrogen stream and thereafter passed to the preheater 110. Typical hydrotreating conditions for hydrotreating reactor 120 include a temperature of 260 ℃ to 426 ℃, a pressure of 6895kPa (g) (1000psig) to 21029kPa (g) (3050psig), and 0.1hr^-1To 10hr^-1LHSV of (1). Suitable hydrotreating catalysts include metals on refractory inorganic oxide supports selected from the group consisting of: nickel, cobalt, tungsten, molybdenum, and mixtures thereof.

In an alternative arrangement, both the stream in line 112, the preheated hydrocarbon feed stream, and the hydrogen stream in line 242 can be sent separately to the hydrotreating reactor 120. According to one embodiment, the hydrocarbon feed stream in line 112 to the hydrotreating reactor 120 may comprise one or more of Vacuum Gas Oil (VGO), Light Cycle Oil (LCO), deasphalted oil, and diesel.

The hydrotreating reactor 120 may include one or more hydrotreating catalyst beds to provide a hydrotreated effluent stream in line 122. Although not shown in the figures, the combined stream in line 114 can be split into multiple streams. Thus, streams from multiple streams may be sent to an overhead hydrocracking catalyst bed, and the remaining stream passed to a downstream hydrotreating catalyst bed in the hydrotreating reactor 120 as a quench stream for the stream from an upstream hydrotreating bed. Each bed may contain a similar or different catalyst as compared to the other beds of the hydrotreating reactor. Hydrotreating reactor 120 provides for the removal of sulfur and/or nitrogen from combined stream 114 to provide a hydrotreated effluent stream in line 122.

The hydrotreated effluent stream in line 122 may then be passed to a first hydrocracking reactor 130. Accordingly, the hydrocracking effluent stream in line 122 is hydrocracked in the first hydrocracking reactor 130 in the presence of the hydrogen stream and the first hydrocracking catalyst at first hydrocracking conditions including a first hydrocracking pressure to provide a first hydrocracking effluent stream in line 132. The first hydrocracking reactor 130 may include at least one or more hydrocracking catalyst beds for hydrocracking the hydrotreated effluent stream to provide a first hydrocracking effluent stream in line 132. The first hydrocracking pressure can be 13790kPa (g) (2000psig) to 17237kPa (g) (2500psig), or 14479kPa (2100psig) to 16547kPa (g) (2400 psig).

The catalyst bed of the first hydrocracking reactor 130 may include a hydrocracking catalyst that utilizes an amorphous silica-alumina base or a low level zeolite base in combination with one or more group VIII or group VIB metal hydrogenation components. Zeolite cracking binders are sometimes referred to in the art as molecular sieves and are typically composed of silica, alumina, and one or more exchangeable cations such as sodium, magnesium, calcium, rare earth metals, and the like. It is also characterized by crystal pores having a relatively uniform diameter between 4 and 14 angstroms. Zeolites having a relatively high silica to alumina mole ratio of between 3 and 12 may be employed. Suitable zeolites found in nature include, for example, mordenite, stilbite, heulandite, ferrierite, dachiardite, chabazite, erionite and faujasite. Suitable synthetic zeolites include, for example, B, X, Y and the L crystal type, such as synthetic faujasite and mordenite. Preferred zeolites are those having a crystalline pore size of between 8 angstroms and 12 angstroms, with a silica/alumina molar ratio of 4 to 6. One example of a zeolite falling within the preferred group is synthetic Y molecular sieve.

Naturally occurring zeolites are usually present in the sodium form, alkaline earth metal form or mixtures. Synthetic zeolites are almost always prepared first in the sodium form. In any case, for use as a cleavage binder, it is preferred that most or all of the original zeolitic monovalent metals be ion-exchanged with a polyvalent metal and/or with an ammonium salt, and then heated to decompose the ammonium ions associated with the zeolite, leaving in their place hydrogen ions and/or exchange sites from which cations have actually been removed by further removal of water. Zeolites such as Y zeolite can be steamed and acid washed to dealuminate the zeolite structure.

The mixed polyvalent metal-hydrogen zeolite can be prepared by first exchanging ions with an ammonium salt, then partially reverse exchanging with a polyvalent metal salt, and then calcining. In some cases, such as in the case of synthetic mordenite, the hydrogen form may be prepared by direct acid treatment of an alkali metal zeolite. In one aspect, preferred pyrolysis binders are those lacking at least 10 wt% and preferably at least 20 wt% of metal cations based on initial ion exchange capacity. In another aspect, a desirable and stable class of zeolites are those wherein the hydrogen ions satisfy at least 20 weight percent ion exchange capacity.

The active metals used as hydrogenation components in the preferred hydrocracking catalysts of the invention are the active metals of group VIII, i.e. iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. In addition to these metals, other promoters may be employed in combination, including group VIB metals, such as molybdenum and tungsten. The amount of hydrogenation metal in the catalyst may vary within wide limits. In general, any amount between 0.05 and 30 wt% may be used. In the case of noble metals, it is generally preferred to use from 0.05 to 2% by weight.

The above catalysts may be employed in undiluted form or the powdered catalyst may be mixed with other relatively less active catalysts, diluents or binders such as alumina, silica gel, silica-alumina cogels, activated clays, etc. in proportions ranging between 5 and 90 wt% and pelletized. These diluents may be employed as such, or they may contain minor proportions of added hydrogenation metals, such as group VIB and/or group VIII metals. Additional metal promoted hydrocracking catalysts may also be used in the process of the present invention, including, for example, aluminum phosphate molecular sieves, Crystalline chromosilicates (crystalloid chlorosilicates), and other Crystalline silicates.

The hydrocracking catalyst preferably has a high activity, such as containing at least 40 wt% to 60 wt% of dealuminated Y zeolite or at least 15 wt% to 35 wt% of non-dealuminated Y zeolite or at least 3 wt% to 10 wt% of beta zeolite, or some combination thereof that produces a similar activity. In each case, the expected mass transfer limitations were significant, so smaller diameter extrudates such as 1/16 inch cylinders or 1/16 inch trilobes could provide the best performance. The hydrocracking catalyst bed of the first hydrocracking reactor 130 may account for 30% to 60% of the total catalyst volume in the first hydrocracking reactor 130.

Referring back to the figure, at least a portion of the first hydrocracking effluent stream in line 132 is fractionated in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction and a diesel fraction. As shown, the first hydrocracking effluent stream in line 132 can be passed to a hot separator 140 to separate the first hydrocracking effluent stream into an overhead separator stream in line 142 and a bottoms separator stream in line 144. In one aspect, the hot separator 140 can be in direct communication with the first hydrocracking reactor 130 via the first hydrocracking effluent stream in line 132. Thus, the first hydrocracking effluent stream in line 132 may be passed directly to the hot separator 140. Suitable operating conditions for the hot separator 140 include, for example, temperatures of 260 ℃ to 320 ℃.

The first vapor stream in line 142 can be passed to a first cold separator 150 to provide a first vapor stream in line 152 and a first liquid stream in line 154. Suitable operating conditions for the first cold separator 150 include, for example, a temperature of 20 ℃ to 60 ℃ and a pressure just below the second hydrocracking reactor 130. The first liquid stream in line 154 can be combined with the separator bottoms stream in line 144 from the hot separator 140 to provide a first combined liquid stream in line 156. The first combined liquid stream in line 156 can be sent to a common stripper 160 along with another liquid stream as described in detail below for stripping. As shown, the second liquid stream from the second cold separator 210 in line 214 can be passed to the common stripper 160 along with the first combined liquid stream in line 156. Any suitable stripping medium can be used in common stripper 160 to separate the remaining gaseous fraction and provide a stripped liquid stream in line 162. Preferably, the stripping medium is steam. Thus, at least a portion of the first hydrocracking effluent stream and at least a portion of the second hydrocracking effluent stream may be passed to a common stripper 160 before being passed to the fractionation column 180. The first vapor stream in line 152 can be sent to a scrubber 230 to provide a hydrogen-rich stream in line 232.

Thereafter, the stripped liquid stream in line 162 can be passed to a preheater 164 to heat the stripped liquid stream to a predetermined temperature, and thereafter to a fractionation column 180 in line 166 to fractionate the stripped liquid stream into various fractions based on boiling ranges of the various fractions, including but not limited to a heavy naphtha fraction, a kerosene fraction, and a diesel fraction. In one aspect, the stripped liquid stream in line 162 can be sent directly to the fractionation column 180. As shown, a naphtha fraction is withdrawn in line 182, a kerosene fraction is withdrawn in line 184, a diesel fraction is withdrawn in line 186, and an unconverted fraction is withdrawn in line 188.

In the exemplary embodiment shown, the kerosene fraction in line 184 can be passed to side stripper 190 to provide a stripped kerosene fraction in line 192. A portion of the stripped kerosene fraction in line 192 can be withdrawn as a product stream in line 192A. The remaining portion of the stripped kerosene fraction in line 192 can be passed to the second hydrocracking reactor 200. As shown, the stripped kerosene fraction in line 192 can be preheated prior to being sent to the second hydrocracking reactor 200.

Turning now to the second hydrocracking reactor 200, the kerosene stream in line 196 is hydrocracked in the second hydrocracking reactor 200 in the presence of hydrogen and a second hydrocracking catalyst at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream in line 202. According to the exemplary embodiment as shown, the kerosene stream in line 196 can comprise a combination of the kerosene fraction in line 192 and the kerosene fraction from an external source in line 194. In an alternative arrangement, the kerosene stream in line 196 can include a kerosene fraction in line 194 solely from an external source.

The second hydrocracking reactor 200 may comprise one or more beds of a second hydrocracking catalyst. Further, each bed may contain a similar or different catalyst as compared to the other beds of the second hydrocracking reactor 200. The second hydrocracking catalyst of the second hydrocracking reactor may be similar to or different from the first hydrocracking catalyst of the first hydrocracking reactor 130, or may be a mixture thereof.

In one aspect, the second hydrocracking reactor 200 can be operated at second hydrocracking conditions including a second hydrocracking pressure, wherein the first hydrocracking pressure is at least 6895kpa (g) (1000psig) greater than the second hydrocracking pressure. In alternative embodiments, the first hydrocracking pressure may be at least 7240kPa (g) (1050psig) or at least 7584kPa (g) (1100psig) greater than the second hydrocracking pressure. Specifically, the second hydrocracking pressure may be 2758kPa (g) (400psig) bar to 6550kPa (g) (950psig), or 3999kPa (g) (580psig) to 3999kPa (g) (870 psig). Applicants have surprisingly found that operating the second hydrocracker pressure at this low pressure, and in particular at a pressure 6895kpa (g) (1000psig) lower than the first hydrocracking pressure, still results in a satisfactory yield of naphtha.

The second hydrocracking effluent stream withdrawn from the bottom of the second hydrocracking reactor 200 in line 202 may be passed to the fractionation column 180. As shown, the second hydrocracking effluent stream in line 202 may be passed to a second cold separator 210. The second cold separator 210 separates the second hydrocracking effluent stream to provide a second vapor stream in line 212 and a second liquid stream in line 214. Suitable operating conditions for the cold separator 140 include, for example, a temperature of 20 ℃ to 60 ℃ and a pressure just below the second hydrocracking reactor 200.

At least a portion of the second liquid stream can be passed to fractionation column 180. As shown, the second liquid stream in line 214 can be passed to common stripper 160, either together with or separately from the first combined liquid stream in line 156, and further processed as previously described. Thus, at least a portion of the first hydrocracking effluent stream and at least a portion of the stripped second hydrocracking effluent stream are passed to the fractionation column 180.

Referring to the second vapor stream in line 212, as shown, the entire second vapor stream can be passed to the second hydrocracking reactor 200. The second vapor stream in line 212 comprises primarily hydrogen and can be recycled to the second hydrocracking reactor 200 via recycle line 222 after being compressed to a predetermined pressure in compressor 220. Applicants have found that the second vapor stream is substantially free of impurities including hydrogen sulfide and ammonia. Thus, the entire vapor stream, also supplemented with a portion of the compressed make-up hydrogen stream in line 310A, can be advantageously used in the second hydrocracking reactor. As shown, the recycle stream in line 222 can be combined with the kerosene stream in line 196 and then passed to the second hydrocracking reactor 200 in line 198. Although not shown in the figure, the combined stream in line 198 can be preheated in a preheater and then passed to the second hydrocracking reactor 200. In another aspect, the second vapor stream in line 212 can be separately passed to the second hydrocracking reactor 200.

Further, as shown, a compression system 300 is provided to compress the make-up hydrogen stream in line 302. The compression system 300 may be a multi-stage compression system including at least two compressors. In the exemplary embodiment as shown, the compression system 300 of the method of the present disclosure may include at least three compressors, including a first compressor 310, a second compressor 320, and a third compressor 330. The compression system 300 can compress the make-up hydrogen stream in line 302 to provide a compressed make-up hydrogen stream.

In one aspect, because the second hydrocracking reactor 200 operates at a much lower pressure than the first hydrocracking reactor 130, a portion of the compressed make-up hydrogen stream may be withdrawn from the compression system upstream of the second compressor 320 via line 310A. Thus, the portion of the compressed make-up hydrogen stream in line 310A is passed to the second hydrocracking reactor 200. The remaining portion of the make-up hydrogen stream can be further compressed in the second compressor 320 and the third compressor 330 and passed in line 242 as a compressed hydrogen stream to the first hydrocracking reactor 130. The compressed hydrogen stream in line 332 can be combined with the hydrogen-rich stream in line 232 to provide the compressed hydrogen stream to the first hydrocracking reactor 130 via line 242.

Any of the above-described lines, conduits, units, devices, containers, surroundings, areas, or the like may be equipped with one or more monitoring components, including sensors, measurement devices, data capture devices, or data transmission devices. The signals, process or condition measurements, and data from the monitoring components can be used to monitor conditions in, around, and associated with the process tool. The signals, measurements, and/or data generated or recorded by the monitoring component may be collected, processed, and/or transmitted over one or more networks or connections, which may be private or public, general or private, direct or indirect, wired or wireless, encrypted or unencrypted, and/or combinations thereof; the description is not intended to be limited in this respect. Further, the figures show one or more exemplary sensors such as 10a, 10b, 10c, 10d, and 10e located on one or more catheters for sensing and transmitting data across a wired network or cloud for control and/or display purposes. However, there may be sensors on each stream so that the corresponding parameters may be displayed and/or controlled accordingly.

The signals, measurements, and/or data generated or recorded by the monitoring component may be transmitted to one or more computing devices or systems. A computing device or system may include at least one processor and memory storing computer-readable instructions that, when executed by the at least one processor, cause the one or more computing devices to perform a process that may include one or more steps. For example, one or more computing devices may be configured to receive data from one or more monitoring components relating to at least one piece of equipment associated with the process. One or more computing devices or systems may be configured to analyze the data. Based on the data analysis, one or more computing devices or systems may be configured to determine one or more recommended adjustments to one or more parameters of one or more processes described herein. One or more computing devices or systems may be configured to transmit encrypted or unencrypted data including one or more recommended adjustments to one or more parameters of one or more processes described herein.

The applicant has found that using the proposed flow scheme enables to maximize the conversion of kerosene to heavy naphtha while improving the retention of (N + 2A). In particular, applicants have found that operating the second hydrocracking reactor at a pressure of from 2758kpa (g) (400psig) to 6550kpa (g) (950psig) and at a pressure at least 6895kpa (g) (1000psig) lower than the first hydrocracking pressure results in improved N +2A retention and increased heavy naphtha yield.

Examples

The following is an example of a process for maximizing the production of heavy naphtha from a hydrocarbon stream according to an exemplary embodiment of the process of the present disclosure as shown in the drawing. The examples are provided for illustrative purposes only and are not intended to limit the various embodiments of the methods of the present disclosure in any way.

Several experiments were performed to examine the effect of pressure on the conversion of kerosene to heavy naphtha. VGO is used as feed and is subjected to hydrocracking in a first hydrocracking reactor and a second hydrocracking reactor.

In an exemplary operation, VGO is subjected to hydrocracking in a first hydrocracking reactor operating at 13790kpa (g) (2000psig) to provide a first hydrocracking effluent stream. The first hydrocracking effluent stream is then subjected to hydrocracking together with a kerosene stream in a second hydrocracking reactor operating at a second hydrocracking pressure lower than the first hydrocracking pressure. The second hydrocracking pressure was varied for pressure studies of the second hydrocracking reactor. The results thus obtained are listed in table 1 below:

TABLE 1

As is evident from Table 1, at 75 wt% conversion, the heavy naphtha yield is highest with high N +2A when the second hydrocracking pressure is between 5884kPa (g) (853psig) and 2943kPa (g) (427 psig). Applicants have found that when the second hydrocracking pressure is 9807kpa (g) (1422psig), i.e., when the second hydrocracking reactor is operated at a pressure differential of less than 6895kpa (g) (1000psig) as compared to the first hydrocracking reactor, the N +2A of the heavy naphtha is reduced. Further, when the second hydrocracking pressure is 1961kPa (g) (284 psig); i.e., less than 2758kPa (g) (400psig), the heavy naphtha yield is reduced to 55 wt%.

While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.

Detailed description of the preferred embodiments

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

A first embodiment of the invention is a process for maximizing the production of heavy naphtha from a hydrocarbon stream, the process comprising providing a hydrocarbon feedstream comprising vacuum gas oil to a first hydrocracking reactor; hydrocracking the hydrocarbon feed stream in the first hydrocracking reactor at first hydrocracking conditions including a first hydrocracking pressure in the presence of a hydrogen stream and a first hydrocracking catalyst to provide a first hydrocracking effluent stream; fractionating at least a portion of the first hydrocracking effluent stream in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction, and a diesel fraction; hydrocracking the kerosene stream in a second hydrocracking reactor operated at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream, the first hydrocracking pressure being greater than the second hydrocracking pressure 6895kpa (g) (1000 psig); and passing at least a portion of the second hydrocracking effluent stream to the fractionation column to maximize production of heavy naphtha. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the first hydrocracking pressure is greater than the second hydrocracking pressure by more than 7240kpa (g) (1050 psig). An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the kerosene stream entering the second hydrocracking reactor comprises a portion of the kerosene fraction from the fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the kerosene stream entering the second hydrocracking reactor comprises a kerosene fraction from an external source. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the hydrocarbon feedstream through a hydrotreating reactor prior to passing to the first hydrocracking reactor. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing at least a portion of the first hydrocracking effluent stream to a first separator to provide a first vapor stream and a first liquid stream, and passing at least a portion of the first liquid stream to a fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the second hydrocracking effluent stream to a second separator to provide a second vapor stream and a second liquid stream, and passing at least a portion of the second liquid stream to the fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein at least a portion of the first hydrocracking effluent stream and at least a portion of the stripped second hydrocracking effluent stream are passed to a common stripper prior to being passed to the fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising compressing the make-up hydrogen stream in an at least two-stage compressor, and withdrawing a portion of the compressed make-up hydrogen stream from a second compressor upstream of the at least two-stage compressor and passing to a second hydrocracking reactor. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the remaining portion of the compressed make-up hydrogen stream is further compressed in the at least two-stage compressor and passed to the first hydrocracking reactor. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising at least one of: sensing at least one parameter of the process for maximizing heavy naphtha production and generating a signal or data from the sensing; generating and transmitting a signal; or generate and transmit data.

A second embodiment of the invention is a process for maximizing the production of heavy naphtha from a hydrocarbon stream, the process comprising providing a hydrocarbon feedstream comprising vacuum gas oil to a first hydrocracking reactor; b) hydrocracking the hydrocarbon feed stream in the first hydrocracking reactor operated at first hydrocracking conditions including a first hydrocracking pressure in the presence of a hydrogen stream and a first hydrocracking catalyst to provide a first hydrocracking effluent stream; c) passing at least a portion of the first hydrocracking effluent stream to a first separator to provide a first vapor stream and a first liquid stream; d) fractionating at least a portion of the first liquid stream in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction, and a diesel fraction; e) hydrocracking the kerosene stream in a second hydrocracking reactor operated at second hydrocracking conditions including a second hydrocracking pressure, the first hydrocracking pressure being greater than the second hydrocracking pressure, to provide a second hydrocracking effluent stream; f) passing the second hydrocracking effluent stream to a second separator to provide a second vapor stream and a second liquid stream; g) passing the entire second vapor stream to the second hydrocracking reactor; and h) passing at least a portion of the second liquid stream to the fractionation column to maximize production of heavy naphtha. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the first hydrocracking pressure is from 13790kpa (g) (2000psig) to 17237kpa (g) (2500psig) and the second hydrocracking pressure is from 2758kpa (g) (400psig) to 6550kpa (g) (950 psig). An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the first liquid stream and the second liquid stream are passed to a common stripper prior to being passed to the fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the kerosene stream entering the second hydrocracking reactor comprises a portion of the kerosene fraction from the fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the kerosene stream entering the second hydrocracking reactor comprises a kerosene fraction from an external source.

A third embodiment of the invention is a process for maximizing the production of heavy naphtha from a hydrocarbon stream, the process comprising providing a hydrocarbon feedstream comprising vacuum gas oil to a first hydrocracking reactor; b) hydrocracking the hydrocarbon feed stream in the first hydrocracking reactor operated at first hydrocracking conditions including a first hydrocracking pressure in the presence of a hydrogen stream and a first hydrocracking catalyst to provide a first hydrocracking effluent stream; c) fractionating at least a portion of the first hydrocracking effluent stream in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction, and a diesel fraction; d) compressing a make-up hydrogen stream in at least two-stage compressor and withdrawing a portion of the compressed make-up hydrogen stream from a second compressor upstream of the at least two-stage compressor; e) the remaining portion of the make-up hydrogen stream is further compressed in the at least two-stage compressor and passed as the hydrogen stream to the first hydrocracking reactor; f) hydrocracking a kerosene stream in the presence of the portion of the compressed hydrogen into a second hydrocracking reactor operating at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream comprising primarily naphtha, the first hydrocracking pressure being greater than the second hydrocracking pressure; and g) passing at least a portion of the second hydrocracking effluent stream to the fractionation column to maximize production of heavy naphtha. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the first hydrocracking pressure is from 13790kpa (g) (2000psig) to 17237kpa (g) (2500psig) and the second hydrocracking pressure is from 2758kpa (g) (400psig) to 6550kpa (g) (950 psig). An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the kerosene stream entering the second hydrocracking reactor comprises a portion of the kerosene fraction from the fractionation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the kerosene stream entering the second hydrocracking reactor comprises a kerosene fraction from an external source.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent and can readily ascertain the essential characteristics of the present invention without departing from the spirit and scope thereof, to make various changes and modifications of the invention and to adapt it to various usages and conditions. Accordingly, the foregoing preferred specific embodiments are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever, and is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

In the foregoing, all temperatures are shown in degrees celsius and all parts and percentages are by weight unless otherwise indicated.

Claims

1. A process for maximizing the production of heavy naphtha from a hydrocarbon stream, the process comprising:

a) providing a hydrocarbon feed stream comprising vacuum gas oil to a first hydrocracking reactor;

b) hydrocracking the hydrocarbon feed stream in the first hydrocracking reactor at first hydrocracking conditions including a first hydrocracking pressure in the presence of a hydrogen stream and a first hydrocracking catalyst to provide a first hydrocracking effluent stream;

c) fractionating at least a portion of the first hydrocracking effluent stream in a fractionation column to provide a heavy naphtha fraction, a kerosene fraction, and a diesel fraction;

d) hydrocracking the kerosene stream in a second hydrocracking reactor operated at second hydrocracking conditions including a second hydrocracking pressure to provide a second hydrocracking effluent stream, the first hydrocracking pressure being at least 6895kpa (g) (1000psig) greater than the second hydrocracking pressure; and

e) passing at least a portion of the second hydrocracking effluent stream to the fractionation column to maximize production of heavy naphtha.

2. The process of claim 1, wherein the first hydrocracking pressure is greater than the second hydrocracking pressure by at least 7240kPa (g) (1050 psig).

3. The process of claim 1, wherein the kerosene stream entering the second hydrocracking reactor comprises a portion of the kerosene fraction from the fractionation column.

4. The method of claim 1, further comprising passing the hydrocarbon feedstream through a hydrotreating reactor prior to passing to the first hydrocracking reactor.

5. The process of claim 1, further comprising passing at least a portion of the first hydrocracking effluent stream to a first separator to provide a first vapor stream and a first liquid stream, and passing at least a portion of the first liquid stream to a fractionation column.

6. The process of claim 1, further comprising passing the second hydrocracking effluent stream to a second separator to provide a second vapor stream and a second liquid stream, and passing at least a portion of the second liquid stream to the fractionation column.

7. The process of claim 1, wherein at least a portion of the first hydrocracking effluent stream and at least a portion of the stripped second hydrocracking effluent stream are passed to a common stripper prior to being passed to the fractionation column.

8. The process of claim 1, further comprising compressing the make-up hydrogen stream in at least two-stage compressor, and withdrawing a portion of the compressed make-up hydrogen stream from a second compressor upstream of the at least two-stage compressor and passing to a second hydrocracking reactor.

9. The process of claim 8, wherein the remaining portion of the compressed make-up hydrogen stream is further compressed in the at least two-stage compressor and passed to the first hydrocracking reactor.

10. The method of claim 1, further comprising at least one of:

sensing at least one parameter of the process for maximizing heavy naphtha production and generating a signal or data from the sensing;

generating and transmitting a signal; or

Data is generated and transmitted.