Patent Application
20200308498
The field relates to an integrated processes and apparatuses for maximizing recovery of liquid petroleum gas (LPG). More particularly, the technical field relates to integration of various processes for maximizing recovery of LPG.
Various catalytic processes are known for converting low value hydrocarbons to high quality petroleum products. One of the widely-employed process is catalytic reforming to produce high quality petroleum products in the gasoline boiling range. Typically, in catalytic reforming, naphtha boiling range hydrocarbons are passed to a reforming zone wherein it is contacted with a reforming catalyst in the presence of hydrogen to provide a reforming reactor effluent. The catalytic reforming of the naphtha boiling range hydrocarbons produces reformate that includes aromatic hydrocarbons and also produces significant quantities of valuable lighter hydrocarbons, such as liquefied petroleum gas (LPG) containing primarily C3 and C4 hydrocarbons. Refiners are striving to maximize the recovery of valuable lighter hydrocarbons, such LPG.
Further, there are various other processes which also produce LPG boiling range hydrocarbons along with the primary product e.g. hydrocracking process. The stripper off gas obtained from the conventional hydrocracking process comprises significant amount of LPG boiling range hydrocarbons. However, LPG boiling range hydrocarbons are not efficiently recovered from the stripper off gas and removed with fuel gas stream. Accordingly, a significant portion of LPG boiling range hydrocarbons is lost in stripper off gas. Also, the stripper off gas is passed through the sponge oil absorber and a various fractionation column to the lower hydrocarbons and the LPG boiling range hydrocarbons.
Thus, the known processes for the recovery of LPG range hydrocarbons from refinery gas streams require complex equipment to separate the LPG range hydrocarbons and for the purification of the LPG range hydrocarbons separated from the refinery gas streams. Further, some of the streams need several separation/purification steps to recover the LPG range hydrocarbons. However, these streams do not undergo rigorous or efficient separation steps to recover the LPG range hydrocarbons present therein. These streams are removed as fuel gases from the processes and therefore LPG range hydrocarbons present therein are lost in fuel gas system. Further, processes which employ recovery or separation steps for LPG range hydrocarbons install various additional columns and/or compressors. Setting up these separation machineries for the recovery of LPG range hydrocarbons for the individual processes increases the capital and operational expenditures of the plant.
Accordingly, it is desirable to provide new apparatuses and processes for providing cost benefits in terms of lower capital and operational expenditures. Further, there is a need for an alternative approach for an improved process to maximize recovery of valuable lighter hydrocarbons, such as LPG to meet the globally rising demand. 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.
Various embodiments contemplated herein relate to processes and apparatuses for maximizing recovery of LPG. The exemplary embodiments taught herein provide an integrated process for maximizing recovery of LPG by integrating various processes.
In accordance with an exemplary embodiment, a process is provided for maximizing recovery of liquid petroleum gas (LPG). The process comprises providing a hydrocarbonaceous feed comprising naphtha, and a hydrogen stream to a reforming zone. In the reforming zone, the hydrocarbonaceous feed comprising naphtha is reformed in the presence of the hydrogen stream and a reforming catalyst to provide a reformate effluent stream. At least a portion of the reformate effluent stream and at least one stream comprising C6− hydrocarbons from one or more of a hydrocracking zone, an isomerization zone, and a transalkylation zone to a debutanizer column of the reforming zone to provide a fraction comprising liquid petroleum gas (LPG) and a debutanizer column bottoms stream.
In the current integrated process, streams from various processes are passed to the reforming zone to maximize recovery of LPG. The current process envisages that the stripping column overhead streams from a hydrocracking, an isomerization, and a transalkylation processes, which are usually separated and passed to downstream recovery system of the respective processes, can be passed to the debutanizer column of the reforming zone to maximize recovery of LPG. The current integrated process eliminates the use of separate debutanizer column in the hydrocracking zone and the isomerization zone by integrating these zones via the debutanizer column of the reforming zone. Also, the current process integrates the compressor of the reforming zone with the hydrocracking zone, the isomerization zone, and the transalkylation zone. Accordingly, the present process provides a seamless integration of the hydrocracking zone, the isomerization zone, and the transalkylation zone, with the reforming zone with reduced capital expenditure and/or operating expenditure of the entire process to maximize recovery of LPG.
These and other features, aspects, and advantages of the present invention will become better understood upon consideration of the following detailed description, drawings and appended claims.
The various embodiments will hereinafter be described in conjunction with the following FIGURES, wherein like numerals denote like elements.
As used herein, the term “stream” can include various hydrocarbon molecules and other substances.
As used herein, the term “column” means a distillation column or columns for separating one or more components of different volatilities. Unless otherwise indicated, each column includes a condenser on an overhead of the column to condense the overhead vapor and reflux a portion of an overhead stream back to the top of the column. Also included is a reboiler at a bottom of the column to vaporize and send a portion of a bottom stream back to the bottom of the column to supply fractionation energy. Feeds to the columns may be preheated. The top pressure is the pressure of the overhead vapor at the outlet of the column. The bottom temperature is the liquid bottom outlet temperature. Overhead lines and bottom lines refer to the net lines from the column downstream of the reflux or reboil to the column. Alternatively, a stripping stream may be used for heat input at the bottom of the column.
As used herein, the term “overhead stream” can mean a stream withdrawn in a line extending from or near a top of a vessel, such as a column.
As used herein, the term “bottoms stream” can mean a stream withdrawn in a line extending from or near a bottom of a vessel, such as a column.
The term “Cx−” wherein “x” is an integer means a hydrocarbon stream with hydrocarbons have x and/or less carbon atoms and preferably x and less carbon atoms.
The term “Cx+” wherein “x” is an integer means a hydrocarbon stream with hydrocarbons have x and/or more carbon atoms and preferably x and more carbon atoms.
As used herein the term “communication” means that material flow is operatively permitted between enumerated component.
As used herein, the term “downstream communication” means that at least a portion of material flowing to the subject in downstream communication may operatively flow from the object with which it communicates.
As used herein, the term “upstream communication” means that at least a portion of the material flowing from the subject in upstream communication may operatively flow to the object with which it communicates.
As used herein, the term “direct communication” or “directly” means that flow from the upstream component enters the downstream component without undergoing a compositional change due to physical fractionation or chemical conversion.
As used herein, the term “passing” includes “feeding” and “charging” and means that the material passes from a conduit or vessel to an object.
As used herein, the term “separator” means a vessel which has an inlet and at least an overhead vapor outlet and a bottoms liquid outlet and may also have an aqueous stream outlet from a boot. A flash drum is a type of separator which may be in downstream communication with a separator. The separator may be operated at higher pressure than the flash drum.
As used herein, the term “portion” means an amount or part taken or separated from a main stream without any change in the composition as compared to the main stream. Further, it also includes splitting the taken or separated portion into multiple portions where each portion retains the same composition as compared to the main stream.
As used herein, the term “zone” can refer to an area including one or more equipment items and/or one or more sub-zones. Equipment items can include one or more reactors or reactor vessels, heaters, separators, drums, exchangers, pipes, pumps, compressors, and controllers. Additionally, an equipment item, such as a reactor, dryer, or vessel, can further include one or more zones or sub-zones.
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 Figures have been simplified by the deletion of a large number of apparatuses customarily employed in a process of this nature, such as vessel internals, temperature and pressure controls systems, flow control valves, recycle pumps, etc. which are not specifically required to illustrate the performance of the invention. Furthermore, the illustration of the process of this invention in the embodiment of a specific drawing is not intended to limit the invention to specific embodiments set out herein.
As depicted, process flow lines in the figures can be referred to, interchangeably, as, e.g., lines, pipes, branches, distributors, streams, effluents, feeds, products, portions, catalysts, withdrawals, recycles, suctions, discharges, and caustics.
An embodiment of an integrated process for maximizing recovery of liquid petroleum gas (LPG) is addressed with reference to an integrated process and apparatus according to an embodiment as shown in
As shown, the hydrocarbonaceous feed comprising naphtha in line 102 may be mixed with a hydrogen stream in line 104 and a recycle gas stream in line 192 to provide a combined feed stream in line 108. The combined feed stream in line 108 may be heat exchanged with a reformate effluent stream in line 132 in the combined feed exchanger 110 to preheat the combined feed stream in line 108. The preheated feed stream in line 112 may be passed to the reforming reactor 130 of the reforming zone 100. As shown, the reforming reactor 130 may comprise a plurality of reaction zones 130a, 130b, 130c, and 130d. The reaction zones may be stacked one on top of another for a stacked reactor configuration to form a compact unit that minimizes plot area requirements. Each of the plurality of reaction zones may be adaptable to contain one or more beds of a reforming catalyst. Each of the plurality of reaction zones is in fluid communication with an interzone heater 120 to heat the feed stream to the plurality of reaction zones to a predetermined temperature. Although not shown in
The hydrocarbonaceous feed may be reformed in the reforming reactor 130 of the reforming zone 100 in the presence of the hydrogen stream and the reforming catalyst to provide a reformate effluent stream. The reaction zones of the reforming reactor 130 may be operated with a feed inlet temperature from about 450° C. to about 540° C. In the reaction zones, reforming reactions take place. The primary reforming reactions convert paraffins and naphthenes of the hydrocarbonaceous feed through dehydrogenation and cyclization to aromatics. The dehydrogenation of paraffins may yield olefins, and the dehydrocyclization of paraffins and olefins may yield aromatics. The reforming process is an endothermic process, and to maintain the reaction, the reforming reactor 130 can be a catalytic reactor that may comprise a plurality of reaction zones with an interzone heater.
As shown, the preheated feed stream in line 112 may be passed to the interzone heater 120 to provide a first heated feed stream in line 122 which may be passed to the first reaction zone 130a. The first reaction zone effluent in line 122′ may be passed to the interzone heater 120 to provide a second heated feed stream in line 124. The second heated feed stream in line 124 is passed to the second reaction zone 130b. The second reaction zone effluent in line 124′ is passed to the interzone heater 120 to provide a third heated feed stream in line 126. The third heated feed stream in line 126 is passed to the third reaction zone 130c. The third reaction zone effluent in line 126′ is passed to the interzone heater 120 to provide a fourth heated feed stream in line 128. The fourth heated feed stream in line 128 is passed to the fourth reaction zone 130d. Thereafter, a reformate effluent stream in line 132 from the fourth reaction zone may be removed and passed to the combined feed exchanger 110 to preheat the combined feed stream. Although, the reforming zone 100 comprises four reaction zones as shown in
Reforming catalysts generally comprise a metal on a support. The support can include a porous material, such as an inorganic oxide or a molecular sieve, and a binder. Inorganic oxides used for support include, but are not limited to, alumina, magnesia, titania, zirconia, chromia, zinc oxide, thoria, boria, ceramic, porcelain, bauxite, silica, silica-alumina, silicon carbide, clays, crystalline zeolitic aluminasilicates, and mixtures thereof. Reforming catalysts may comprise one or more Group VIII noble metals. In an exemplary embodiment, the reforming catalyst may comprise one or more of a noble metal selected from platinum, palladium, rhodium, ruthenium, osmium, and iridium. The catalyst can also include a promoter element from Group IIIA or Group IVA. These metals include gallium, germanium, indium, tin, thallium and lead.
At least a portion of the reformate effluent stream may be passed to a debutanizer column 170 of the reforming zone 100 to provide a fraction comprising liquid petroleum gas (LPG) in line 206 and a debutanizer column bottoms stream in line 176. Also, a hydrocracked C6− hydrocarbons stream in line 388, an isomerized C6− hydrocarbons stream in line 478, and/or a transalkylated C6− hydrocarbons stream in line 558 may also be passed to the debutanizer column 170 of the reforming zone 100 via compressor 180 to provide the fraction comprising liquid petroleum gas (LPG) in line 206 and the debutanizer column bottoms stream in line 176. As shown, the reformate effluent stream in line 132 may be passed to the combined feed exchanger 110 to provide a heat exchanged reformate effluent stream in line 134. The reformate effluent stream in line 134 may be further cooled in a cooler 150 and passed to the separator 160 in line 152. The cooler 150 is optionally used. Accordingly, the reformate effluent stream in line 134 may be passed to the separator 160 without further cooling in the cooler 150. In the separator 160, the reformate effluent stream in line 134 may be separated, perhaps after cooing, to provide a reformate vapor stream in line 162 and a reformate liquid stream in line 168. At least a portion of the reformate vapor stream in line 164 and the hydrocracked C6− hydrocarbons stream in line 388, the isomerized C6− hydrocarbons stream in line 478, and/or the transalkylated C6− hydrocarbons stream in line 558 may be passed to the compressor 180 to provide a compressed liquid stream in line 244. In an alternate scheme, the at least portion of the reformate vapor stream in line 162, and the hydrocracked C6− hydrocarbons stream in line 388, the isomerized C6− hydrocarbons stream in line 478, and/or the transalkylated C6− hydrocarbons stream in line 558 may be combined and passed to the compressor 180 to provide the compressed liquid stream in line 244. As shown in
An embodiment of the compressor 180 of the reforming zone 100 is addressed with reference to an embodiment as shown in
Referring back to
The current process provides higher LPG recovery from the hydrocracked C6− hydrocarbons stream in line 388, the isomerized C6− hydrocarbons stream in line 478, and/or the transalkylated C6− hydrocarbons stream in line 558 which generally is lost in fuel gases. By passing these streams to the compressor 180 of the reforming zone 100 as shown in
In an exemplary embodiment, the hydrocracked C6− hydrocarbons stream in line 388, the isomerized C6− hydrocarbons stream in line 478, and/or the transalkylated C6− hydrocarbons stream in line 558 may be obtained from a stripper overhead stream in line 388 of a hydrocracking process, a stripper overhead stream in line 478 of an isomerization process, and/or a stripper overhead stream in line 558 of a transalkylation process, respectively.
In another exemplary embodiment, the at least one stream comprising C6− hydrocarbons is obtained from an integrated process and apparatus as shown in
A hydrogen containing stream in line 392a may also be provided in between the catalyst beds of the hydrocracking reactor 330a to maintain an adequate supply of hydrogen in the first stage hydrocracking reactor 330a for hydrocracking reactions. The first hydrocracked effluent stream in line 324 from the first stage hydrocracking reactor 330a may be passed to a second stage hydrocracking reactor 330b for further hydrocracking the first hydrocracked effluent stream in line 324 to provide a second hydrocracked effluent stream in line 332. The first hydrocracked effluent stream in line 324 may be combined with the hydrogen containing stream in line 392a as shown in
Suitable hydrocracking catalysts may comprise catalysts that utilize amorphous silica-alumina bases or low-level zeolite bases combined with one or more Group VIII or Group VIB metal hydrogenating components. The zeolite cracking bases are sometimes referred to in the art as molecular sieves and are usually composed of silica, alumina and one or more exchangeable cations such as sodium, magnesium, calcium, rare earth metals, etc. The active metals employed in preferred hydrocracking catalysts as hydrogenation components are those of Group VIII, i.e., iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. In addition to these metals, other promoters may also be employed in conjunction therewith, including the metals of Group VIB, e.g., molybdenum and tungsten.
At least a portion of the hydrocracked effluent stream in line 332 may be separated in a hydrocracking separator to provide a gas stream in line 352 and a liquid stream in line 354. In an exemplary embodiment, the hydrocracking separator comprises a cold separator 340 and a cold flash drum 350. As shown, the hydrocracked effluent stream in line 332 may be cooled in a cooler to provide a relatively cooled hydrocracked effluent stream in line 336. The cooled hydrocracked effluent stream in line 336 may be passed to the cold separator 340. The cooler is optionally used and the hydrocracked effluent stream in line 332 may be passed to the cold separator 340 without further cooling. In the cold separator 340, the hydrocracked effluent stream in line 332 may be separated in to a vapor stream in line 342 and a liquid stream in line 344. A wash water stream in line 334 may also be mixed with the hydrocracked effluent stream in line 332 to absorb any corrosive compounds or salts present therein that might cause plugging. And, the mixed stream may be passed to the cold separator 340 to provide the vapor stream in line 342 and the liquid stream in line 344. The vapor stream in line 342 may be recycled to the hydrocracking reactor 330 as shown in
Conventionally, in the hydrocracking process, the stripping column off gas containing LPG, after scrubbing, may be passed through a sponge oil absorber to recover LPG range hydrocarbons and then be sent to a fuel gas system. The recovered LPG range hydrocarbons are routed to a debutanizer column of the hydrocracking zone after being stabilized in a deethanizer column. In the current process, it is proposed that instead of passing the stripping column off gas stream in line 372 through the sponge oil absorber and the deethanizer and the debutanizer columns of the hydrocracking zone 300, the stripping column off gas stream in line 372 and the gas stream in line 352 both comprising LPG range hydrocarbons are routed to the compressor 180 of the reforming zone 100 for the recovery of LPG present in these streams. Accordingly, the present process eliminates the sponge oil, the deethanizer column, and the debutanizer column of the hydrocracking zone 300 while maximizing recovery of LPG. Thus, the current process reduces capital expenditure and/or operating expenditure of the process by integrating the debutanizer column 170 of the reforming zone 100 with the hydrocracking zone 300 via stripping column overhead stream of the hydrocracking zone in line 362 while eliminating the sponge oil absorber, the debutanizer column, and the deethanizer column of the hydrocracking zone 300 for maximizing recovery of LPG. Also, the present flow scheme provides seamless integration of the reforming zone 100 and the hydrocracking zone 300 via stripping column overhead stream of the hydrocracking zone in line 362 to maximize recovery of LPG. The present scheme uses a single compressor or compressor train 180 of the reforming zone 100 to integrate the hydrocracking zone 300 with the reforming zone 100 to maximize recovery of LPG.
In an exemplary embodiment, the stripping column off-gas stream comprises C6− hydrocarbons in an amount from about 10 wt % to about 50 wt %. The stripping column off-gas stream comprising C6− hydrocarbons in line 372 may be passed to the scrubber column 380a. In the scrubber column 380a, the stripping column off-gas stream may be washed with an amine solution introduced in to the scrubber column in line 384. H2S present in the stripping column off-gas stream in line 372 may be removed and withdrawn with the stream in line 386 from the scrubber column 380a. Similarly, the gas stream in line 352 may also be subjected to a suitable method to remove any contaminants present therein and thereafter passed to the compressor 180 of the reforming zone 100. In an exemplary embodiment, the gas stream in line 352 may be passed to a scrubber column 380b to remove the contaminants present therein. The gas stream in line 352 may be washed with an amine solution introduced into the scrubber column in line 306. Contaminants present in the gas stream in line 352 are removed and withdrawn with the stream in line 308 from the scrubber column 380b. A treated stripping column off-gas stream in line 382 and a treated gas stream in line 352′ both comprising C6− hydrocarbons may be combined and passed to the compressor 180 of the reforming zone 100 as the hydrocracked C6− hydrocarbons stream in line 388 as shown in
The vapor stream in line 342 from the cold separator 340 may comprise hydrogen along with other hydrocarbons that may be recycle for hydrocracking. As shown in
In another exemplary embodiment, the at least one stream comprising C6− hydrocarbons is obtained from an integrated process and apparatus as shown in
Typical isomerization catalysts contain a catalytically-effective amount of molecular sieve and a catalytically-effective amount of one or more hydrogenation metal components. Examples of molecular sieves include MFI, MEL, EUO, FER, MFS, MTT, MTW, TON, MOR, UZM-8 and FAU types of zeolites. Pentasil zeolites such as MFI, MEL, MTW and TON are preferred, and MFI-type zeolites, such as ZSM-5, silicalite, Borolite C, TS-1, TSZ, ZSM-12, SSZ-25, PSH-3, and ITQ-1 are especially preferred. The catalysts may contain hydrogenation metal components and may contain suitable binder or matrix material such as inorganic oxides and other suitable materials. A refractory binder or matrix is typically used to facilitate fabrication of the isomerization catalyst, provide strength and reduce fabrication costs. The binder should be uniform in composition and relatively refractory to the conditions used in the process. Suitable binders include inorganic oxides such as one or more of alumina, aluminum phosphate, magnesia, zirconia, chromia, titania, boria and silica.
The isomerized effluent stream in line 422 may be passed to the stripping column 460 to provide an overhead stream comprising C7− hydrocarbons in line 462 and a bottoms stream comprising C8+ hydrocarbons in line 468. The isomerized effluent stream in line 422 may be cooled in the heat exchanger with the p-xylene lean stream in line 404. A heat exchanged isomerized effluent stream in line 424 may be further cooled in a cooler and passed to the hot separator 430 in line 426 for separation. Suitable operating conditions of the hot separator 430 include, for example, a temperature of about 260° C. to 320° C. The hot separator 430 may be operated at a slightly lower pressure than the isomerization reactor 420 accounting for pressure drop of intervening equipment. In the hot separator 430, the isomerized effluent stream in line 422 may be separated to provide an overhead vapor stream in line 432 and a bottoms liquid stream in line 438. Although not shown in
The bottoms liquid stream in line 446 from the cold separator 450 and the bottoms liquid stream in line 438 from the hot separator 430 may be combined. A combined stream in line 448 may be passed to the stripping column 460 to provide the overhead stream comprising C7− hydrocarbons in line 462 and the bottoms stream comprising C8+ hydrocarbons in line 468. As shown, the combined stream in line 448 may be heat exchanged in a heat exchanger and passed to the stripping column 460 in line 454. Any suitable stripping media may be used in the stripping column 460. In an exemplary embodiment, steam may be used as stripping media instead of using a reboiler 480. In the stripping column 460, the combined stream in line 448 may be stripped off the heavy hydrocarbons with the stripping media to provide the overhead stream comprising C7− hydrocarbons in line 462 and the bottoms stream comprising C8+ hydrocarbons in line 468. In an aspect, the stripping column 460 is a deheptanizer column. Accordingly, the isomerized effluent stream may be passed to the deheptanizer column 460 to provide the overhead stream comprising C7− hydrocarbons in line 462 and the bottoms stream comprising C8+ hydrocarbons in line 468. In an aspect, the overhead stream comprising C7− hydrocarbons comprises C6− hydrocarbons in an amount from about 90 wt % to about 98 wt %. At least a portion of the overhead stream comprising C7− hydrocarbons in line 462 may be compressed to obtain the at least one stream comprising C6− hydrocarbons. As shown, the overhead stream comprising C7− hydrocarbons in line 462 may be heat exchanged in the heat exchanger with the combined stream in line 448 to provide a heat exchanged overhead stream in line 464. The heat exchanged overhead stream in line 464. The heat exchanged overhead stream in line 464 may be further cooled in a cooler and passed to the receiver 470 of the stripping column 460 in line 466. The cooler is optionally used and the overhead stream in line 464 may be passed to the receiver 470 without further cooling in the cooler.
In the receiver 470, the overhead stream comprising C7− hydrocarbons in line 462 may be separated in to liquid and vapor. A portion of the liquid may be passed to the stripping column 460 as reflux stream in line 476. Another portion of the liquid in line 474 and a vapor stream in line 472 may be passed to the reforming zone 100 for LPG recovery. In an exemplary embodiment, the liquid stream in line 474 and the vapor stream in line 472 may be combined and passed as the isomerized C6− hydrocarbons stream in line 478 to the compressor 180 of the reforming zone. In an alternate scheme, at least a portion of the overhead stream comprising C7− hydrocarbons in line 462 may be passed directly to the compressor 180 of the reforming zone. The isomerized C6− hydrocarbons stream in line 478 is compressed in the compressor 180 as described herein above. In an alternate scheme, the liquid stream in line 474 and the vapor stream in line 472 may be passed to the compressor 180 separately. The compressor 180 of the reforming zone 100 is in downstream fluid communication with the isomerization zone 400 via the isomerized C6− hydrocarbons stream in line 478. In an exemplary embodiment, the compressor 180 of the reforming zone 100 is in downstream fluid communication with the isomerization zone 400 via the liquid stream in line 474 and the vapor stream in line 472.
Typically, the isomerization zone 400 includes a stabilizer or a debutanizer column downstream of the stripping column 460 for recovery of lower hydrocarbons. This debutanizer column is sometimes provided with a vent condenser or a chiller to recover LPG range hydrocarbons. Applicants have found that instead of placing a dedicated debutanizer column for the isomerization process, the overhead stream from stripping column 460 may be passed to the reforming zone 100 to maximize recovery of LPG in the debutanizer column 170 of the reforming zone 100. Particularly, the stripping column overhead stream in line 462 from the isomerization zone 400 is passed to the debutanizer column 170 of the reforming zone 100 via the compressor 180 of the reforming zone 100 to maximize recovery of LPG. Therefore, the current process eliminates the use of an additional debutanizer column of the isomerization zone 400 while maximizing recovery of LPG as shown in
In yet another exemplary embodiment, the at least one stream comprising C6− hydrocarbons is obtained from an integrated process and apparatus as shown in
The transalkylation catalysts that may be used are based on a solid-acid material combined with a metal component. Suitable solid-acid materials include all forms and types of mordenite, mazzite (omega zeolite), beta zeolite, ZSM-11, ZSM-12, ZSM-22, ZSM-23, MFI type zeolite, NES type zeolite, EU-1, MAPO-36, MAPSO-31, SAPO-5, SAPO-11, SAPO-41, silica-alumina mixtures thereof or ion exchanged versions of such solid-acids. Refractory inorganic oxides, combined with the above-mentioned catalysts are usually found useful in transalkylation process. A refractory binder or matrix is optionally utilized to facilitate fabrication of the catalyst, provide strength and reduce fabrication costs. The binder should be uniform in composition and relatively refractory to the conditions used in the process. Suitable binders include inorganic oxides such as one or more of alumina, magnesia, zirconia, chromia, titania, boria, thoria, phosphate, zinc oxide and silica. Alumina is a preferred binder. The catalyst may optionally contain additional modifier metal components. Preferred metal modifier components of the catalyst include, for example, tin, germanium, lead, indium, platinum, palladium and mixtures thereof.
The transalkylation zone effluent stream in line 522 may be removed and cooled by heat exchange in the heat exchanger with the combined stream in line 504. At least a portion of the transalkylation zone effluent stream in line 522 may be stripped in the stripping column 540 to provide a stripping column overhead stream in line 542 and a stripping column bottoms stream in line 546. As shown, the transalkylation zone effluent stream in line 522 may be further cooled in a cooler and passed to the separator 530 in line 526. The separator 530 may operate at a pressure below the pressure of the reactor 520 accounting for pressure drop of intervening equipment. In the separator 530, transalkylation zone effluent stream in line 522 may be separated to provide a vapor stream in line 532 and a bottoms liquid stream in line 534. A portion of the vapor stream in line 532b may be removed as a purge stream. The remaining portion of the vapor stream in line 532a may be recycled to the reactor 520. Although not shown in
In conventional transalkylation process, the stripping column overhead stream in line 542 is passed to separate recovery system to recover C5− hydrocarbons from stripping column overhead stream wherein the stripping column overhead stream is further compressed, cooled, and passed to various columns for separation. However, the applicants have found that instead of passing the stripping column overhead stream in line 542 to a separate recovery system of the transalkylation zone 500, the stripping column overhead stream in line 542 from the transalkylation zone 500 can be passed to the reforming zone 100 to maximize recovery of LPG. Accordingly, the stripping column overhead stream in line 542 from the transalkylation zone 500 is passed to the compressor 180 of the reforming zone 100 to compress the stripping column overhead stream in line 542 along with the other process streams to maximize recovery of LPG. Thereby, the current process allows seamless integration of the transalkylation zone 500 with the reforming zone 100 via the stripping column overhead stream in line 542 to maximize recovery of LPG. And, also eliminates the use of separate recovery system of the transalkylation zone 500 that conventionally is used for the recovery of C5− hydrocarbons in the transalkylation zone 500.
Generally, fuel gas produced from the hydrocracking process, the isomerization process, and the transalkylation process are removed and passed to their respective fuel gas system without further recovery of the components present therein. Applicants have found that these streams may contain a substantial amount of LPG range hydrocarbons and therefore can be used for recovery. Accordingly, the present process provides integration of the hydrocracking zone 300, the isomerization zone 400, and the transalkylation zone 500 via the at least one stream comprising C6− hydrocarbons with the reforming zone 100 to maximize recovery of LPG. Also, the current process avoids the use of intervening equipment such as a debutanizer column and a recycle compressor that are used in the conventional hydrocracking, isomerization, and transalkylation processes by integration of these processes via the C6− hydrocarbons stream with the compressor 180 of the reforming zone 100 to maximize recovery of LPG.
Further, by integrating the hydrocracking zone 100, the isomerization zone 400, the transalkylation zone 500, with the reforming zone 100 via the compressor 180, the current process eliminates the need of separate compressors present in aforesaid zones while maximizing recovery of LPG as described herein above. The current process also eliminates the use of separate recovery unit comprising various compressors and separators for each of the reforming zone 100, the isomerization zone 400, and the transalkylation zone 500 and integrates these zones by using a single compressor 180 or compressor train system 180 of the reforming zone 100 via the hydrocracked C6− hydrocarbons stream in line 388 from the hydrocracking zone 100, the isomerized C6− hydrocarbons stream in line 478 from the isomerization zone 400, and the transalkylated C6− hydrocarbons stream in line 558 from the transalkylation zone 500, to maximize the recovery of LPG as shown in
Any of the above lines, conduits, units, devices, vessels, surrounding environments, zones or similar may be equipped with one or more monitoring components including sensors, measurement devices, data capture devices or data transmission devices. Signals, process or status measurements, and data from monitoring components may be used to monitor conditions in, around, and on process equipment. Signals, measurements, and/or data generated or recorded by monitoring components may be collected, processed, and/or transmitted through one or more networks or connections that may be private or public, general or specific, direct or indirect, wired or wireless, encrypted or not encrypted, and/or combination(s) thereof; the specification is not intended to be limiting in this respect. Further, the figure shows one or more exemplary sensors such as 11, 12, 13, 14, 31 32, 33, 41, 42, 51, and 52 located on one or more conduits. Nevertheless, there may be sensors present on every stream so that the corresponding parameter(s) can be controlled accordingly.
Signals, measurements, and/or data generated or recorded by monitoring components may be transmitted to one or more computing devices or systems. Computing devices or systems 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, the one or more computing devices may be configured to receive, from one or more monitoring component, data related to at least one piece of equipment associated with the process. The one or more computing devices or systems may be configured to analyze the data. Based on analyzing the data, the 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. The one or more computing devices or systems may be configured to transmit encrypted or unencrypted data that includes the one or more recommended adjustments to the one or more parameters of the one or more processes described herein.
While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.
A first embodiment of the invention is an integrated process for maximizing recovery of liquid petroleum gas (LPG), comprising providing a hydrocarbonaceous feed comprising naphtha, and a hydrogen stream to a reforming zone; reforming the hydrocarbonaceous feed in the reforming zone in the presence of the hydrogen stream and a reforming catalyst to provide a reformate effluent stream; and passing at least a portion of the reformate effluent stream, and at least one stream comprising C6− hydrocarbons from one or more of a hydrocracking zone, an isomerization zone, and a transalkylation zone, and to a debutanizer column of the reforming zone to provide a fraction comprising liquid petroleum gas (LPG) and a debutanizer column bottoms stream. 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 separating the reformate effluent stream in a separator to provide a reformate vapor stream and a reformate liquid stream; passing at least a portion of the reformate vapor stream and the at least one stream comprising C6− hydrocarbons to a compressor from one or more of the hydrocracking zone, the isomerization zone, and the transalkylation zone to provide a compressed liquid stream; passing the compressed liquid stream and the reformate liquid stream to the debutanizer column of the reforming zone to provide a debutanizer column overhead stream and the fraction comprising LPG; and passing the debutanizer column overhead stream to the compressor. 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 at least one stream comprising C6− hydrocarbons is obtained from the hydrocracking zone, the process further comprising hydrocracking a first hydrocarbonaceous feed in a hydrocracking zone in the presence of a hydrocracking catalyst and hydrogen to provide a hydrocracked effluent stream; separating at least a portion of the hydrocracked effluent stream in a hydrocracking separator to provide a gas stream and a liquid stream; stripping at least a portion of the liquid stream in a stripping column to provide a stripped liquid stream and a stripping column off-gas stream comprising C6− hydrocarbons; and compressing the gas stream and the stripping column off-gas stream comprising C6− hydrocarbons to obtain the at least one stream comprising C6− hydrocarbons. 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 at least one stream comprising C6− hydrocarbons is obtained from the isomerization zone, the process further comprising isomerizing a p-xylene lean stream in an isomerization zone in the presence of hydrogen to provide an isomerized effluent stream; passing the isomerized effluent stream to a stripping column to provide an overhead stream comprising C7− hydrocarbons and a bottoms stream comprising C8+ hydrocarbons; and compressing at least a portion of the overhead stream comprising C7− hydrocarbons to obtain the at least one stream comprising C6− hydrocarbons. 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 stripping column is a deheptanizer 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 at least one stream comprising C6− hydrocarbons is obtained from the transalkylation zone, the process further comprising passing a hydrocarbonaceous feed comprising C7+ hydrocarbons to a transalkylation zone comprising transalkylation catalyst to produce a transalkylation zone effluent stream; stripping at least a portion of the transalkylation zone effluent stream in a stripping column to provide a stripping column overhead stream and a stripping column bottoms stream; and compressing at least a portion of the stripping column overhead stream to obtain the at least one stream comprising C6− hydrocarbons. 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 hydrocracking zone is a slurry hydrocracking zone. 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 reforming catalyst comprises one or more of a noble metal selected from platinum, palladium, rhodium, ruthenium, osmium, and iridium. 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 at least one stream comprising C6− hydrocarbons from one or more of the hydrocracking zone, the isomerization zone, and the transalkylation zone is passed to a first stage compressor of a multistage compressor train. 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 hydrocarbonaceous feed comprises one or more of vacuum gas oil (VGO), diesel, light cycle oil (LCO), heavy thermally cracked gas oil, kerosene, vacuum residue, and deasphalted oil (DAO). 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 separator is a cold flash drum. 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 gas stream comprises LPG and dissolved hydrogen. 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 integrated process for maximizing recovery of LPG and generating a signal or data from the sensing; generating and transmitting a signal; or generating and transmitting data.
A second embodiment of the invention is an integrated process for maximizing recovery of liquid petroleum gas (LPG), comprising providing a hydrocarbonaceous feed comprising naphtha, and a hydrogen stream to a reforming zone; reforming the hydrocarbonaceous feed in the reforming zone in the presence of the hydrogen stream and a reforming catalyst to provide a reformate effluent stream; and passing at least a portion of the reformate effluent stream and at least one stream comprising C6− hydrocarbons from one or more of a stripping column overhead to a debutanizer column of the reforming zone to provide a fraction comprising liquid petroleum gas (LPG). 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 at least one stream comprising C6− hydrocarbons is obtained from one or more of a stripping column overhead of a hydrocracking zone, a stripping column overhead of an isomerization zone, and a stripping column overhead of a transalkylation zone. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising separating the reformate effluent stream in a separator to provide a reformate vapor stream and a reformate liquid stream; passing at least a portion of the reformate vapor stream, and the at least one stream comprising C6− hydrocarbons from the stripping column overhead of the hydrocracking zone, the stripping column overhead of the transalkylation zone, and the stripping column overhead of the isomerization zone to a multistage compressor train to provide a compressed liquid stream; passing the compressed liquid stream and the reformate liquid stream to the debutanizer column of the reforming zone to provide a debutanizer column overhead stream and the fraction comprising LPG; and passing the debutanizer column overhead stream to the multistage compressor train.
A third embodiment of the invention is an integrated process for maximizing recovery of liquid petroleum gas (LPG), comprising reforming a hydrocarbonaceous feed comprising naphtha in a reforming zone in the presence of a reforming catalyst and hydrogen to provide a reformate effluent stream; and passing at least a portion of the reformate effluent stream, and a stream comprising C6− hydrocarbons to a debutanizer column of the reforming zone to provide a fraction comprising LPG, wherein the stream comprising C6− hydrocarbons is obtained from one or more of the following processes a hydrocracking process, an isomerization process, and a transalkylation process; wherein the hydrocracking process comprises hydrocracking a first hydrocarbonaceous feed in a hydrocracking zone in the presence of a hydrocracking catalyst and hydrogen to provide a hydrocracked effluent stream; separating at least a portion of the hydrocracked effluent stream in a hydrocracking separator to provide a gas stream and a liquid stream; stripping at least a portion of the liquid stream in a stripping column to provide a stripped liquid stream and a stripping column off-gas stream comprising C6− hydrocarbons; and passing the gas stream and the stripping column off-gas stream to a compressor to provide the stream comprising C6− hydrocarbons; wherein the isomerization process comprises passing a hydrocarbonaceous feed comprising C8+ hydrocarbons to a xylene column to provide an overhead stream comprising a mixture of xylenes and a bottoms stream comprising C9+ hydrocarbons; separating p-xylene from the overhead stream comprising the mixture of xylenes to provide a p-xylene lean stream; isomerizing the p-xylene lean stream in an isomerization zone in the presence of an isomerization catalyst and hydrogen to provide an isomerized effluent stream; passing the isomerized effluent stream to a stripping column to provide an overhead stream comprising C7− hydrocarbons and a bottoms stream comprising C8+ hydrocarbons; and passing the overhead stream to the compressor to provide the stream comprising C6− hydrocarbons; or the transalkylation process comprises passing a hydrocarbonaceous feed comprising C7+ hydrocarbons to a transalkylation zone comprising transalkylation catalyst to produce a transalkylation zone effluent stream; stripping at least a portion of the transalkylation zone effluent stream in a stripping column to provide a stripping column overhead stream and a stripping column bottoms stream; and passing the stripping column overhead stream to the compressor to provide the stream comprising C6− hydrocarbons. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising passing the isomerized effluent stream to a deheptanizer column to provide the overhead stream comprising C7− hydrocarbons and the bottoms stream comprising C8+ hydrocarbons. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising separating the reformate effluent stream in a separator to provide a reformate vapor stream and a reformate liquid stream; compressing at least a portion of the reformate vapor stream to provide a compressed liquid stream; passing the compressed liquid stream and the reformate liquid stream to the debutanizer column of the reforming zone to provide a debutanizer column overhead stream and the fraction comprising LPG; and passing the at least portion of the reformate vapor stream, the debutanizer column overhead stream and the at least one of the gas stream, the stripping column off-gas stream comprising C6− hydrocarbons, the overhead stream comprising C7− hydrocarbons, and the at least portion of the stripping column overhead stream to a multistage compressor train to provide the compressed liquid stream. 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 at least one of the gas stream, the stripping column off-gas stream comprising C6− hydrocarbons, the overhead stream comprising C7− hydrocarbons, and the at least portion of the stripping column overhead stream is passed to a first stage compressor of the multistage compressor train.
Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of this 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. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.
In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.
