ES2687197T3 - Hydrotreatment and hydrocracking process and apparatus - Google Patents

Abstract

Hydrocracking process for partially converting a hydrocarbon feedstock comprising the following steps: (a) hydrotreating a hydrocarbon feedstock with a hydrogen-rich gas to produce a hydrotreated effluent stream comprising a liquid/vapor mixture comprising is separated into a liquid phase and a gas phase, and (b) in a flash stage (or flash evaporation), which is a single-stage distillation in which the hydrotreated effluent stream comprising a liquid/ vapor is separated into a liquid portion and a more liquid vapor portion and in which no pressure change is required, divide the liquid phase into a controlled liquid portion established by conversion and an excess liquid portion by conversion. regulation of controlled liquid flow from the separation stage with a flow control valve and combining the entire gas phase with the excess liquid portion to forming a vapor plus liquid portion, (c) removal of the vapor plus liquid portion by overflow, and (d) subsequent separation of a liquid fraction containing the fluid catalytic cracking feed from the controlled liquid portion from the flash stage and simultaneously transferring the more liquid vapor portion from the flash stage to a hydrocracking stage to produce a diesel-containing fraction, or transferring the controlled liquid portion from the flash stage to a hydrocracking stage for producing a diesel-containing fraction and simultaneously separating a liquid fraction containing the fluid catalytic cracking feed from the vapor plus liquid portion of the flash stage.

Description

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DESCRIPTION

Hydrotreatment and hydrocracking process and apparatus

The invention relates to a process and a partial conversion hydrocracking apparatus, where the heavy oil feed is hydrotreated and partially converted in order to produce a feed for a fluid catalytic cracking unit (FCC). The invention is particularly useful in the production of ultra low sulfur (ULSD) and high quality FCC feed diesel, which can be used to produce ultra low sulfur (USLG) gasoline in the FCC unit without subjecting the gasoline from FCC to subsequent treatment to meet sulfur specifications.

Background of the invention

For many years, refiners have used partial conversion or "gentle" hydrocracking to produce incremental yields of medium distillate while improving the raw material for catalytic cracking of fluids (FCC). Initially, the specialized catalysts were adapted to the conditions of low or moderate pressure in the FCC feed desulfurizers to achieve a conversion of 20 to 30 percent of the heavy diesel in diesel and lighter products. The combination of low pressure and high temperatures used to achieve hydroconversion conditions generally resulted in heavy products, with high aromatic content and low cetane number. The new specifications for gasoline and diesel products require the manufacture of lighter and lower sulfur products, which fit into the ultra low sulfur content diesel and gasoline reserve tanks (ULSD and ULSG) of the refineries. The continuous increase in the demand for medium distilled fuel compared to gasoline has once again focused attention on hydrocracking and, particularly, on partial conversion hydrocracking as a key process alternative to adapt to current clean fuel requirements.

Both in the United States and in the European Union, the new specifications require dramatic reductions in diesel and gasoline sulfur levels. It is currently known that lower sulfur levels in these products provide substantial benefits in terms of decreased emissions from car and truck exhaust pipes. The pipeline transport system for products with low and high sulfur distillation levels remains a work in progress. Recent studies in the US indicate that up to 10% of diesel with ultra-low sulfur content (ULSD) will be degraded by the common pipeline transport system, and some carriers require that the ULSD have a sulfur content of no more than 5 ppm by weight in the limit of the refinery. The environmental benefits and logistics of product transport ensure that continuous pressures will be exerted to ensure that all fuels fall into the category of ultra low sulfur content.

Conventional partial conversion units used in many refineries around the world have been designed for pressure levels in the range of 50 to 100 barg, depending on the feed quality and life cycle objectives. They have been designed to achieve a net conversion of 20% to 30% of heavy vacuum diesel and total sulfur removal of approximately 95% to produce an adequate FCC feed to produce gasoline with low sulfur content. The process configuration has evolved to include high pressure separators for better heat integration and amine absorbers to mitigate the effects of the very high hydrogen sulfide content in the recycled gas.

An important deficiency of this technology is its lack of capacity to exercise independent control of hydroconversion and the severity of the hydrodesulfurization reaction. While the sulfur of the diesel product can be greatly reduced through the application of a greater amount of hydrotreatment catalyst, which achieves a deeper HDS severity, the only real option to improve the density and quality of the Cetane is to increase the operating pressure of the reactor or the severity of the hydrocracking.

Large increases in reactor pressure can increase the consumption of chemical hydrogen between 70% and 100%. The high capital and operating costs associated with large increases in hydrogen consumption constitute a significant disadvantage for using high pressure designs in order to achieve product improvement.

Patent application WO No. 99/47626 discloses an integrated hydroconversion process comprising hydrocracking a combined hydrogen stream and refinery to form liquid and gaseous components. The unreacted hydrogen from the hydrocracking stage is combined with a second refinery stream and hydrotreated. The product is separated into a stream of hydrogen and a portion of this stream is recycled in the hydrocracking stage. Higher gasoline and diesel yields and lower fuel oil yields were obtained. However, this process has the disadvantage of requiring a raw material with relatively low nitrogen, sulfur and aromatic content. This implies, in many cases, that the raw material must be previously treated before the disclosed process.

U.S. Patent No. 6294079 discloses an integrated low conversion process, which comprises separating the effluent from a hydrotreatment stage into three fractions: a light fraction, an intermediate fraction and a heavy fraction. The light fraction and a part of the intermediate and heavy fractions circle the hydrocracking zone and are sent

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to a separator. A series of high pressure separators is used. The remaining intermediate and heavy fractions are hydrocracked. FCC raw material is produced. An increased separator and other separators are used to separate the effluent from the hydrotreator in a stream of steam and two streams of liquid. The parts of each liquid stream are flow controlled and re-mixed with the cooled compressed steam stream, reheated and hydrocracked at high severity to obtain higher quality middle distillate products. The complex arrangement of multiple separators and the cooling of the steam stream result in the use of additional equipment and at an additional cost.

Increasing the overall severity of hydrocracking is sometimes not a viable option. When the objective of the process is to obtain a required amount of FCC feed, a high conversion leads to the formation of good quality diesel. However, high conversion also results in insufficient FCC feed production, as more diesel is produced.

WO 01/31087 A1 discloses a hydroprocessing process whereby liquids and vapors are separated from a hydroprocessed hydrocarbon liquid. The liquid is separated with a separation gas and the resulting vapor is combined with the separation steam and removed from the reactor vessel. The liquid is sent for later hydroprocessing. A reaction vessel comprising the first and second reaction stage (hydrotreatment and hydroprocessing, respectively) with two vapor-liquid separation sections is disclosed. The first separation section is a separation stage in which the effluent from the first reaction stage is contacted with a gas that flows up and removes the effluent that flows down. It is suggested to use fractionation trays or, alternatively, containers instead of trays. The second separation section is placed between the second and the first reaction stage and chimney type separation trays are used.

U.S. Pat. No. 4973396 A discloses a low pressure hydrotreatment process, followed by distillation or separation of the product stream into predominantly "sweet" fractions, some of which can be hydroprocessed with a noble metal catalyst. Hydrotreatment effluents are typically cooled in a heat exchanger and then passed to a gas-liquid separator and subsequently to another separator, where in both cases the gases are removed from the liquid that is then fractionated. Details of the gas-liquid separator are not provided.

EP 0537500 A2 discloses a method of hydrotreating heavy hydrocarbon oil in the presence of catalysts, which comprises hydrometallizing and hydrocracking the heavy hydrocarbon oil successively and then hydrodesulfurizing and hydrodesnitrogenating the treated heavy hydrocarbon oil. The separation into gas and liquid fractions is carried out by atmospheric distillation and vacuum.

The objective of the present invention is to provide a process and an apparatus in which the FCC feed is treated to produce an FCC feed of ultra low sulfur content suitable for the production of ultra low sulfur (USLG) gasoline, which is not It requires further treatment.

Another objective of the present invention is to provide a process and an apparatus for producing diesel with an ultra low sulfur content and a substantially improved ignition quality, measured by the cetane number, the cetane number, the aromatic content and the density.

A further objective of the present invention is to provide a simple apparatus for carrying out the process of the invention.

Summary of the invention

The process of the invention comprises hydrotreatment and partial conversion of a heavy oil feed stream that boils above 260 ° C and has a low asphaltene content (<0.1% by weight). By simultaneously producing a high quality FCC feed, the process provides the possibility of producing ultra low sulfur (USLG) gasoline from the FCC unit. Diesel and naphtha are also produced.

The process of the invention comprises a partial conversion hydrocracking process, which comprises the following steps:

(a) hydrotreating a hydrocarbon feedstock with a hydrogen-rich gas to produce a stream of hydrotreated effluent, which comprises a liquid / vapor mixture that separates into a liquid phase and a gas phase, and

(b) in a stage of instantaneous evaporation (or flash evaporation), which is a single stage distillation in which the stream of hydrotreated effluent comprising a liquid / vapor mixture is separated into a portion of liquid and a portion of vapor more liquid and in which a pressure change is not required, divide the liquid phase into a portion of controlled liquid established by the conversion and a portion of excess liquid by regulating the flow of controlled liquid from the separation stage with a flow control valve and combine the entire gas phase with the excess liquid portion to form a more liquid vapor portion,

(c) the removal of the portion of vapor plus liquid by overflow,

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(d) the subsequent separation of a liquid fraction containing the feed for catalytic cracking of fluids from the controlled liquid portion of the instant evaporation stage and simultaneously transferring the more liquid vapor portion from the instant evaporation stage to a stage hydrocracking to produce a fraction containing diesel, or

the transfer of the controlled liquid portion from the instant evaporation stage to a hydrocracking stage to produce a fraction containing diesel and simultaneously separating a liquid fraction containing the feed for catalytic cracking of fluids from the more liquid vapor portion of The instant evaporation stage.

The apparatus of the invention comprises an apparatus for the partial conversion hydrocracking process according to claim 7.

Summary of the figures

Fig. 1 shows a partial conversion hydrocracking process of the invention.

Fig. 2 shows an alternative partial conversion hydrocracking process of the invention.

Fig. 3 shows a section of the end of the hydrotreatment reactor.

Fig. 4 shows the process of the invention, where the liquid / vapor separation system is located between the hydrotreatment reactor and the hydrocracking reactor.

Detailed description of the invention

The process of the invention is a partial pressure medium conversion hydrocracking process, comprising a hydrotreatment stage and a hydrocracking stage. The process and apparatus of the invention provide a solution that meets the current and expected product specifications for both gasoline and diesel fuel without the need for additional processing or mixing with other lighter and higher quality components. An advantage of the process is that both hydrogen partial pressure and hydrocracking conversion can be used to improve diesel quality, while maintaining the relatively low conversion severity and HDS (hydrodesulphurization) requirements set by the applications of FCC pretreatment.

"Hydrotreatment" (HDT) is a process carried out in the presence of hydrogen by which heteroatoms, such as sulfur and nitrogen, are removed from the hydrocarbon feedstock and thus reduce their aromatic content. Hydrotreatment comprises hydrodesulphurization and hydrodesnitrogenation.

"Hydrodesulfurization" (HDS) is the process by which sulfur is removed from the hydrocarbon feedstock.

"Hydrodeneditrogenation" (HDN) is the process by which nitrogen is removed from the hydrocarbon feedstock.

"Hydrocracking" (HC) is a process whereby a hydrocarbon-containing feedstock decomposes catalytically into a chemical species of lower molecular weight in the presence of hydrogen.

In the process of the invention, the main loop of the process reactor has two reactors in series, a hydrotreatment reactor for pretreatment of the raw material and a hydrocracking reactor to hydrocrack a part of the effluent from the hydrotreatment reactor. "In series" means that the hydrocracking reactor is located downstream of the hydrotreatment reactor.

There is a liquid / vapor separation system integrated in the bottom of the hydrotreatment reactor or contained in a separator vessel located between the two reactors to separate the effluent, a mixture of liquid and vapor that emerges from the catalytic beds of the hydrotreatment reactor.

In the liquid / vapor separation system, an instant evaporation is carried out through the use of an outlet device and an outlet tube. The liquid / vapor mixture separates into a liquid phase and a gas phase in the separator vessel. The outlet device is a vertical internal overflow pipe to divide the liquid phase into a portion of controlled liquid and a portion of excess liquid. The gas phase is combined with the excess liquid portion and this vapor plus liquid portion can be introduced into the hydrocracking reactor. In this case, the controlled liquid portion is removed, bypasses the hydrocracking reactor and is directed to a separator to produce feed of FCC and naphtha and lighter products. It is also possible to send the controlled liquid portion to the hydrocracking reactor and simultaneously separate a fraction containing FCC feed from the liquid plus vapor portion.

The term "instantaneous" or "flash" refers to a single stage distillation in which the stream of hydrotreated effluent comprising a liquid / vapor mixture is separated into a portion of liquid and a portion of vapor

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more liquid No change in pressure is required.

An advantage of the process of the invention is that a simple stage of instant evaporation is used instead of a complex and multi-separator complex scheme to divide the effluent from the catalytic beds of the hydrotreatment reactor into the two parts. The more liquid vapor portion is sent to the hydrocracking reactor without substantially cooling the steam, apart from the cooling required for temperature control at the inlet of the hydrocracking reactor.

Part of the liquid phase in the hydrotreatment effluent is directed to an FCC feed separator. Optionally, a low pressure evaporation drum can be added. Only lighter gasoline and hydrocarbons are recovered. The diesel content in this part is of lower quality since it has a higher density, a higher aromatic content and a lower Cetane value than the diesel produced in the hydrocracking reactor, making it more suitable as an FCC feed . All diesel produced by the process of the invention is produced in the hydrocracking stage and has a much better quality.

An unconverted oil that has a boiling range greater than the diesel product (> 370 ° C +) is recovered from the hydrocracked effluent in a fractionator column. Said oil has not been converted and can be used as an FCC feed or as a raw material for an ethylene plant or a lubrication plant because it has a higher hydrogen content and a lower aromatic content than the FCC feed produced in the feed separator of FCC.

The suitable raw material for the process of the invention is vacuum diesel (VGO), heavy coke diesel (HCGO), diesel obtained by thermal cracking or visbroken (TCGO or VBGO) and deasphalting (DAO) derived from crude oil or other hydrocarbon synthetic. The boiling range of said feeds is in the range of 300 ° C to 700 ° C, with a sulfur content of 0.5 to 4% by weight and a nitrogen content of 500 to 10,000 ppm by weight.

The objective of the hydrotreatment reactor is mainly to desulfurize the feed to a sulfur level of 200 to 1000 ppm by weight, which will result in an FCC gasoline with an ultra-low sulfur content suitable for mixing, which meets both European specifications as Americans (10 and 30 ppm by weight, respectively), without the need to subject gasoline to subsequent hydrotreatment. The low sulfur content in the feed also has the benefit of drastically reducing sulfur oxides (SOx) emissions from the FCC regenerator. Second, the hydrotreatment reactor reduces the nitrogen content in the feed to the hydrocracking reactor. Thirdly, the aromatic content of the FCC feed is also reduced, which will result in higher conversion and higher gas mileage.

The hydrotreatment reactor comprises a hydrotreatment zone followed by a separation zone. The hydrotreatment zone contains one or more catalytic beds for hydrodesulfurization (HDS) and hydrodesnitrogenation (HDN) of the raw material. Products in the hydrotreatment zone comprise a mixture of liquid and steam. In a conventional hydrotreatment reactor, the catalyst beds are supported by bed support beams and the upper space of the lower reactor head is filled with inert spheres that support the last catalyst bed. The vapor and liquid mixture leaves the reactor through an outlet manifold, which is located in the lower head of the reactor.

In one embodiment of the process of the invention, the last catalytic bed in the hydrotreatment reactor is supported on bed support beams as well as the upper beds. However, instead of supporting a large volume of inert spheres, the upper space of the lower reactor head is used to separate the liquid / vapor mixture. The liquid / vapor separation system is used in the lower head to divide the mixture of liquid and vapor from the catalytic beds of the hydrotreatment reactor into a portion of liquid and a portion of steam containing a fraction of liquid, that is, a portion of steam plus liquid.

The more liquid vapor portion can be directed to the hydrocracking reactor and become suitable conditions to produce ULSD. The feed to the FCC unit consists mainly of the liquid part.

The liquid / vapor separation system is integrated in the hydrotreatment reactor and located in the upper space at the bottom of this reactor. It comprises an outlet device for transferring the portion of more liquid vapor to the hydrocracking reactor. The liquid portion is contained at the bottom of the reactor outside the outlet device and leaves the hydrotreatment reactor separately through the outlet tube to be transferred, for example, to a separator. The level of the liquid portion at the bottom of the reactor and, therefore, the amount of liquid transferred to the separator is controlled by conventional flow control valves. Excess liquid not required for transfer to the separator enters the outlet device with all the steam and leaves the reactor as the most liquid vapor portion.

The amount of liquid, that is, the portion of controlled liquid, removed by the outlet tube is established by the conversion of desired HVGO. The controlled liquid portion comprises between 30 and 100% by weight of the liquid phase and the excess liquid portion comprises between 0 and 70% by weight of the liquid phase. Preferably, the controlled liquid portion comprises between 60 and 95% by weight of the liquid phase and the excess liquid portion, between 5 and 40% by weight of the liquid phase.

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The integration of the liquid / vapor separation system into the hydrotreatment reactor has the advantage of reducing the amount of processing equipment when compared to conventional separation outside the reactor. Conventional separation outside the reactor would require the addition of a high pressure separator vessel with the additional disadvantage of a higher capital cost.

The controlled liquid portion is sent to a separator, where a vapor stream removes light hydrocarbons in the boiling range of naphtha, and hydrogen sulfide (H2S) and ammonia (NH3) dissolve in the liquid. The extracted product is used as feed for the FCC unit. The light air products of the separator are predominantly composed of light hydrocarbons of boiling range of naphtha together with ammonia and hydrogen sulfide.

The entire portion of more liquid vapor leaves the separation zone of the hydrotreatment reactor and is transferred to the hydrocracking reactor. The hydrocracking reactor also contains one or more catalytic beds. This reactor may contain some hydrotreatment catalyst to further reduce nitrogen to an optimal level (<100 ppm by weight) and a series of hydrocracking catalyst beds. Hydrocracking reactor products are cooled and transferred to an external high pressure separator vessel. A gaseous stream of hydrogen-rich product is separated from the cracked product and recycled to the hydrotreatment reactor. The liquid stream from the separator is sent to a distillation column where naphtha, diesel and unconverted petroleum products are fractionated.

Alternatively, in another embodiment of the invention, after leaving the separation zone where the products of the hydrotreatment zone are divided into a liquid portion and a more liquid vapor portion, the more liquid vapor portion is directed to a separator. for the elimination of a stream rich in hydrogen. The hydrogen rich stream can be further purified from hydrogen sulfide and ammonia by amine washing and water washing. The liquid product of the separators (a high pressure hot separator in series with a high pressure cold separator) is fed primarily with FCC and sent to the separator to remove light hydrocarbons, H2S and NH3 dissolved in the liquid. The extracted product is used as feed for the FCC unit.

The liquid portion of the separation zone is sent to the hydrocracking reactor, which operates with a cracking gravity sufficient to produce a diesel fraction with product properties in accordance with EN 590 ULSD specifications. The operating conditions in the hydrocracking reactor can be adjusted to provide a product that meets the requirements of the US market. This embodiment provides a lower hydrogen ammonia and sulfide environment in the hydrocracking reactor that increases the activity of the hydrocracking catalyst.

In another embodiment of the invention, a second feed can be added as feed to the hydrocracking reactor. In this embodiment, the second feed can be hydrotreated and hydrocracked in the hydrocracking reactor and the hydrotreatment reactor is circumvented. An example of a second feed is a light cycle oil (LCO) from the FCC, which needs additional hydrotreatment and hydrocracking for conversion into high-quality diesel, jet and gasoline.

Fig. 1 illustrates an embodiment of the invention in which the more liquid vapor portion of the separation zone is cracked in the hydrocracking reactor and the controlled liquid portion is sent to a separator.

A feed 1 is combined with hydrogen, for example, a recycled gas rich in hydrogen 2, and is sent to a hydrotreatment reactor 3 to undergo hydrodesulfurization and hydrodesnitrogenation in one or more catalytic beds. The effluent of the catalytic bed (s) is a mixture of vapor and liquid that separates into a liquid phase and a gas phase. In the downstream separation zone 4, the last separation of the catalytic bed into a more liquid vapor portion 5 and a liquid portion 6 is produced by the use of a liquid / vapor separation system integrated in the hydrotreatment reactor.

The liquid / vapor separation system comprises the outlet device and the outlet tube (as shown in Fig. 3). The liquid portion 6 consists solely of liquid and the vapor portion plus liquid 5 includes all steam. The flow of the liquid portion 6 is controlled by the conventional flow control valve 7 and the excess liquid not required leaves the separation zone 4 as an overflow through the outlet device along with all the steam and thus forms the portion of steam plus liquid 5.

The controlled liquid portion 6 is composed of heavy liquid hydrocarbons with sulfur and nitrogen content substantially reduced in relation to the feed 1. It exits the hydrotreatment reactor 3 and circles the hydrocracking reactor 8 to enter a separation column 9. The Light hydrocarbons, together with ammonia and hydrogen sulfide, are separated in the upper stream 10 from the separation column 9 and the resulting liquid stream from the bottom of the separation column 9 is suitable as a low sulfur FCC feed eleven.

The more liquid vapor portion 5 leaves the hydrotreating reactor 3. Optionally it can be combined with a second hydrocarbon feedstock 22. Then it enters the hydrocracking reactor 8 where it is catalytically cracked to form a hydrocracked effluent 12, which has suitable properties for the preparation of diesel fuel. One or more catalyst beds are present in this reactor. Effluent

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Hydrocracking 12 is sent to a separator vessel 13 and a stream of hydrogen-rich gas 14 is recycled from the separator vessel 13 to the hydrotreatment reactor 3 by a recycled gas compressor 15. The replacement hydrogen 16 can be added to the rich stream in hydrogen 14 upstream or downstream of compressor 15 to maintain the required pressure. The liquid product 17 of the separator vessel 13, which comprises light and heavy hydrocarbons, together with the dissolved ammonia and hydrogen sulfide, is then sent to the fractionator column 18, where a stream of naphtha 19 with ammonia and hydrogen sulfide is removed from the top. Heavy hydrocarbon components comprising a diesel stream 20 and an unconverted oil stream 21 are separated and recovered further down in the fractionator column 18. The gasoline stream 19 can be subjected to additional separation steps. The diesel stream 20 can also be further separated by boiling points in other valuable products, such as aviation jet fuel.

Streams 11 (low sulfur FCC feed) and 21 (unconverted oil stream) are typically combined as a single feed for the FCC unit. However, the unconverted oil stream 21 can also be kept separate for use as a valuable intermediate for manufacturing lubricating oils or as a feed for manufacturing ethylene.

The separation of the liquid phase into a portion of controlled liquid and a portion of excess liquid makes it possible to derive the portion of controlled liquid around the hydrocracking reactor. This allows a high conversion in the hydrocracking reactor and improves the quality of diesel, while maintaining a low overall conversion, so that the desired amount of FCC feed is produced.

Fig. 2 illustrates an embodiment of the invention in which the liquid portion of the separation zone is cracked in the hydrocracking reactor and the more liquid vapor portion is sent to the separation column.

A feed 1 is combined with hydrogen, for example, a recycled gas rich in hydrogen 2, and is sent to a hydrotreatment reactor 3 to undergo hydrodesulfurization and hydrodesnitrogenation in one or more catalytic beds. The hydrotreated effluent stream comprising a liquid / vapor mixture enters the downstream separation zone 4 of the last catalyst bed and is separated into a vapor portion plus liquid 5 and a controlled liquid portion 6 by using the device outlet, as described in Fig. 1. The flow rate of the controlled liquid portion 6 is controlled by the conventional flow control valve 7 and the excess liquid not required leaves the separation zone 4 as overflow through the device outlet (as shown in Fig. 3) together with all the steam and thus form the most liquid vapor portion 5.

The more liquid vapor portion 5 leaves the hydrotreatment reactor 3 and flows to the separator vessel 13A. A hydrogen rich vapor stream 900 is produced from the top of the separator and a stream of hydrocarbon liquid 10A from the bottom of the separator vessel 13A. The hydrocarbon liquid stream 10A also contains dissolved ammonia and hydrogen sulfide and flows to the separation column 9. A stream of light hydrocarbons 120, together with the ammonia and hydrogen sulfide, are separated from the separation column 9 and The liquid stream resulting from the bottom of the separation column 9 is suitable as a low sulfur FCC feed 11.

The controlled liquid portion 6 is composed of heavy liquid hydrocarbons with sulfur and nitrogen content substantially reduced in relation to the feed 1. Leave the hydrotreatment reactor through the flow control valve 7 and combine with the steam stream Hydrogen-rich 900 of the separator vessel 13A to form the mixed vapor and liquid stream 140. Optionally, a second hydrocarbon charge 26 may be added to the mixed vapor-liquid stream 140 if necessary. The mixed vapor-liquid stream 140, optionally combined with the second feed, enters the hydrocracking reactor 8, where it is catalytically cracked into the components of the stream vessel 12 having properties of hydrocracked effluent suitable for the preparation of diesel fuel. One or more catalyst beds are present in this hydrocracking reactor 8. Stream 12 flows to separator vessel 13, where a stream of hydrogen-rich vapor 14 is separated at the top and recycled to the hydrotreatment reactor through a recycle compressor 15. The replacement hydrogen 16 can be added to the hydrogen-rich stream 14 upstream or downstream of the compressor 15 to maintain the required pressure.

The liquid product 17 of the separator vessel 13, which comprises light and heavy hydrocarbons, together with the dissolved ammonia and hydrogen sulfide, is then sent to the fractionator column 18, where a stream of naphtha 19 with ammonia and hydrogen sulfide is removed from the top in the gasoline stream 19. The heavy hydrocarbon components comprising a diesel stream 20 and an unconverted oil stream 21 are separated and recovered further down in the fractionator column 18. The gasoline stream 19 can undergo additional separation steps. The diesel stream 20 can also be further separated by boiling points in other valuable products, such as aviation jet fuel.

Fig. 3 shows an embodiment of the invention in which the lower section of the hydrotreatment reactor is adapted to include the liquid / vapor separation system. The separating vessel, therefore, is integrated in the lower section of the hydrotreatment reactor. The outlet device is located under the support of the last catalytic bed 100 and the support can typically be provided by beams and grilles 200. A decoupling space 300 is created at the bottom of the reactor vessel to allow separation of the gas and liquid phases .

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In this embodiment of the invention, the outlet device is in the form of a vertical tube 40, provided with an anti-whirlpool deflector 50 at the upper open end of the vertical tube 40. A liquid interface level 60 is created at the height of the deflector 50, which It allows all steam in the reactor and a part of the liquid phase to overflow as a portion of more liquid vapor and out of the reactor through the transfer tube 70 to the downstream hydrocracking reactor (not shown).

An outlet tube 80 is provided to remove a controlled part of the liquid phase from the lower center point of the bottom of the reactor, also covered by an anti-whirlpool baffle 50. The flow of the liquid portion through the outlet tube 80 it is regulated by the flow control element 90 through a standard flow control valve 1000 through the transfer tube 110 to a downstream extractor (not shown).

Fig. 4 illustrates another embodiment of the invention in which a separator vessel 13 containing the outlet device and the outlet tube downstream of the hydrotreatment reactor is added. The separator vessel 13 is connected by the tube 120 which transfers all the vapor and liquid content from the lower catalytic bed 100 of the hydrotreatment reactor to the separator vessel 13. In this embodiment, the outlet device is in the form of a vertical tube 40, provided of an anti-whirlpool baffle 50 at the upper open end of the tube. A liquid interface level 60 is created at the height of the baffle 50, which allows all the steam in the reactor and a part of the liquid phase, that is, the most liquid vapor portion, to overflow and exit the reactor through the transfer tube 70 to the hydrocracking reactor downstream (not shown). An outlet tube 80 is provided to remove a controlled part of the liquid phase, that is, the controlled liquid portion, from the lower center point of the lower part of the reactor, also covered by an anti-whirlpool deflector 50. Flow through of this tube is regulated by the flow control element 90 through a standard flow control valve 1000 through the transfer tube 110 to a downstream extractor (not shown).

This embodiment of the invention is especially advantageous when existing plants must be renewed. In such cases, it may not be possible to install the liquid / vapor separation system in an existing hydrotreatment reactor. The installation of the liquid / steam separation system outside the hydrotreatment reactor in the form of a separating vessel containing the outlet device and the outlet tube directly downstream of the hydrotreatment reactor allows separation of the mixture of steam and liquid effluent from the Hydrotreatment reactor in a liquid stream and a vapor stream plus liquid suitable for further processing.

The effluent of the catalytic bed (s) in the hydrotreatment reactor is a mixture of vapor and liquid that separates into a liquid phase and a gas phase. The boiling range of the liquid phase is slightly less than the boiling range of the feed entering the hydrotreatment reactor. The liquid phase has a boiling range of between 200 and 580 ° C.

Partial conversion hydrocracking catalysts useful in the process of the invention must meet the following key functional requirements:

• Size and activity classification to minimize pollution and pressure drop

• Demetalization and reduction of carbon waste

• Hydrodesulfurization for pretreatment of FCC feed at sulfur levels typically between 100 and 1000 ppm by weight.

• Hydrodesnitrogenation for the pretreatment of the hydrocracking feed at nitrogen levels typically between 50 and 100 ppm by weight.

• Hydrocracking with high conversion activity and high diesel selectivity.

To maximize performance in each of these functional categories, stacked (multiple) catalyst systems are useful and provide better overall performance and lower cost compared to multifunctional single catalyst systems. The process described herein is useful to facilitate independent control of the severity of the reaction for multiple catalysts resulting in better performance and a longer shelf life.

Hydrotreatment catalysts are specified individually to optimize sulfur removal for FCC feed pretreatment and for nitrogen removal for hydrocracking feed pretreatment. The silica-zeolitic and amorphous alumina hydrocracking catalysts are also useful in the process of the invention to convert the heavy feed into lighter products with high diesel yield.

Hydrotreatment catalysts can be based, for example, on combinations of cobalt, molybdenum, nickel and tungsten (tungsten), such as CoMo, NiMo, NiCoMo and NiW and supported on suitable carriers. Some examples of such catalysts are TK-558, TK-559 and TK-565 from Haldor Tops0e A / S. Suitable carrier materials are silica, alumina, silica-alumina, titania and other support materials known in the art. Other components may be included in the catalyst, for example, phosphorus.

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Hydrocracking catalysts may include an amorphous cracking component and / or a zeolite, such as zeolite Y, ultrastable zeolite Y, de-illuminated zeolites, etc. Combinations of nickel and / or cobalt and molybdenum and / or tungsten may also be included. Some examples include TK-931, TK-941 and TK-951 from Haldor Tops0e A / S. Hydrocracking catalysts are also supported by suitable carriers, such as silica, alumina, silica-alumina, titania and other conventional carriers known in the art. Other components, for example, phosphorus, can be included as reactivity promoters.

The reaction conditions in the hydrotreatment reactor include a reactor temperature between 325 ° C and 425 ° C, a liquid hourly space velocity (LHSV) in the range of 0.3 h-1 and 3.0 h-1 , a gas / oil ratio of 500-1,000 Nm3 / m3 and a reactor pressure between 80 and 140 bar.

The reaction conditions in the hydrocracking reactor include a reactor temperature between 325 ° C and 425 ° C, a liquid hourly space velocity (LHSV) in the range of 0.3 h-1 and 3 h-1, a gas / oil ratio of 500-1,500 Nm3 / m3 and a reactor pressure between 80 and 140 bar.

The controlled liquid portion may comprise between 30 and 100% by weight of the liquid phase and the excess liquid portion may comprise between 0 and 70% by weight of the liquid phase. Preferably, the controlled liquid portion comprises between 60 and 95% by weight of the liquid phase and the excess liquid portion, between 5 and 40% by weight of the liquid phase.

The specifications for diesel in accordance with the current European standard EN 590 EU ULSD are as follows:

 Sulfur:

 10 - 50 ppm by weight

 Density:

 <845 kg / m3

 T95 (D-86):

 <360 ° c

 Cetane number D-630:

 > 51

 Cetane Index D-4737:

 > 46

 Polyaromatic:

 <11% by weight.

Specifications in accordance with current US standards they are less restrictive than the specifications in accordance with the European standard mentioned above.

The performance terms are defined with respect to true boiling point cuts (TBP) and the following definitions are used in the examples:

 component:

 TBP cut

 Naphtha:

 <150 ° c

 Kerosene:

 150-260 ° c

 Heavy diesel:

 260-390 ° c

 Full range diesel:

 150-390 ° c

 Unconverted:

 > 390 ° c

The conversion terms are defined below. The food and product values are expressed in%:

390 ° C + Net conversion = Feeding 390 "c + - Product 390" c +

390 ° C + Actual conversion = (Feed 390 ° C + - Product 390 ° C +) / Feed 390 ° C 390 ° C + gross conversion = 100 - Product 390 ° C +

EXAMPLES Example 1:

In this example, the liquid / vapor separation system is integrated in the hydrotreatment reactor. This example shows how the different boiling ranges of the effluent from the hydrotreatment reactor are divided into 5 instantaneous evaporation in the outlet device and the outlet tube in the liquid / vapor separation system.

The temperature and pressure of the hydrotreatment reactor are shown in the operating start conditions in Table 1 and the end operating conditions in Table 2.

Table 1

 Pressure = 87.5 bar g Temp. = 396 ° C

 Naphtha (C5-150 ° C) Jet (150-260 ° C) Diesel (260-390 ° C) Gas oil (390 ° C +)

 % by weight in vapor phase

 73.9 58.4 23.8 5.2

 % by weight in liquid phase

 26.1 41.6 76.2 94.8

10 Table 2

 Pressure = 87.5 bar g Temp. = 430 ° C

 Naphtha (C5-150 ° C) Jet (150-260 ° C) Diesel (260-390 ° C) Gas oil (390 ° C +)

 % by weight in vapor phase

 83.4 73.7 44.9 17.8

 % by weight in liquid phase

 16.7 26.3 55.1 82.2

The results show that the liquid phase mainly contains material from the boiling range of gas oil with some diesel material, but only a small portion of jet and naphtha. The diesel material of the boiling range of the hydrotreatment reactor has a relatively high sulfur content and high density and a high content of 15 monoaromatics, making it more suitable as an FCC feed than as a high quality ULSD.

The process of the invention produces substantial economic benefits, as illustrated in Table 2.

Example 2: (Comparative)

This example shows how the quality of diesel at 260-390 ° C improves with additional hydrocracking when compared to the hydrotreatment of an HVGO only. The results are shown in Table 3. Diesel at 260-390 ° C is produced at a hydrogen pressure of 80 bar.

Table 3

 Properties

 Hydrotreatment effluent 37% conversion in hydrocracker 66% conversion in hydrocracker

 Sulfur, ppm by weight

 45 <10 <10

 Specific gravity

 0.890 0.881 0.860

 Cetane Index D-976

 44.6 46.7 51.7

 Total aromatics,% by weight

 46.2 40.0 31.6

The results in Table 3 show that the qualities of an HVGO improve with conversion, as the specific gravity decreases and the cetane number increases.

25 Example 3 (Comparative):

This example illustrates a simplified comparison of a conventional medium pressure hydrocracking process and a high pressure hydrocracking process by a conventional hydrocracker, versus the process of the invention. Both the MHC and the process of the invention used the same pressure level. Enough catalyst was used to reach the ULSD sulfur level (10 ppm by weight). Table 4 shows the performance that can be achieved by the process of the invention.

Table 4

 Process type

 Medium pressure HC Partial pressure HC Process of the invention

 Reactor pressure, barg

 100 160 100

 Gross conversion '1',% vol.

 30 30 30

 Diesel yield 12-1,% vol.

 O co 31.5 28.0

 Diesel sulfur, ppm by weight

 10 10 10

 Density of diesel, kg / m3

 875 845 845

 Cetane Index, D-4737

 46 52 47

 Total installed cost13-1

 1.0 1.3 1.1

 Hydrogen demand

 1.0 1.8 1.3

(1) 100 minus volume percentage of FCC power fractionator funds

(2) Full-range diesel cut, TBP (true boiling point) 150-360 ° C

(3) Cost relative to the medium pressure HC unit (not including hydrogen generation)

5

The results shown in Table 4 indicate that it is not possible for an MHC process to produce an equivalent diesel density and Cetane quality compared to the process of the invention. Increasing the hydrogen pressure to achieve sufficient aromatic saturation to match the diesel density achieved with the invention requires an operating pressure approximately 60% higher for the conventional hydrocracking unit, as shown in the results of the Table 4

For a unit that processes 5,000 tons per day of total cargo, it is estimated that the process of the invention saves 10 to 20 million euros in capital costs when compared to a conventional high pressure partial conversion hydrocracker that produces the Same product quality. Hydrogen is also used more efficiently by the apparatus of the invention, which allows savings of 250,000 normal cubic meters of hydrogen per day. The annual savings in operating costs due to the demand for hydrogen would amount to 2 to 3 million euros. The costs of public services are reduced in relation to the option of high pressure hydrocracking, mainly as a result of the decrease in hydrogen composition and recycling compression requirements.

Claims (9)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 1. Hydrocracking process to partially convert a hydrocarbon raw material comprising the following stages: (a) hydrotreating a hydrocarbon feedstock with a hydrogen-rich gas to produce a stream of hydrotreated effluent, which comprises a liquid / vapor mixture that separates into a liquid phase and a gas phase, and (b) in a stage of instantaneous evaporation (or flash evaporation), which is a single stage distillation in which the stream of hydrotreated effluent comprising a liquid / vapor mixture is separated into a portion of liquid and a portion of vapor more liquid and in which a pressure change is not required, divide the liquid phase into a portion of controlled liquid established by the conversion and a portion of excess liquid by regulating the flow of controlled liquid from the separation stage with a flow control valve and combine the entire gas phase with the excess liquid portion to form a more liquid vapor portion, (c) the removal of the portion of vapor plus liquid by overflow, and (d) the subsequent separation of a liquid fraction containing the feed for catalytic cracking of fluids from the controlled liquid portion of the instant evaporation stage and simultaneously transferring the more liquid vapor portion from the instant evaporation stage to a stage hydrocracking to produce a fraction containing diesel, or the transfer of the controlled liquid portion from the instant evaporation stage to a hydrocracking stage to produce a fraction containing diesel and simultaneously separating a liquid fraction containing the feed for catalytic cracking of fluids from the more liquid vapor portion of The instant evaporation stage. 2. Method according to claim 1, wherein either the most liquid vapor portion or the controlled liquid portion is combined with a second hydrocarbon feedstock to provide a feed for the hydrocracking stage. 3. Method according to claim 1, wherein the portion of controlled liquid is hydrocracked to produce a fraction containing diesel and the fraction containing the feed for catalytic cracking of fluids is separated from the portion of vapor plus liquid by cooling, washing and phase separation in a vapor stream rich in hydrogen, low in ammonia and hydrogen sulfide and a liquid hydrocarbon stream comprising the fraction containing catalytic cracking fluid feed. 4. Method according to claim 3, wherein the hydrogen rich, low ammonia and hydrogen sulfide vapor stream is combined with the controlled liquid portion and hydrocracked to produce a fraction containing diesel. 5. Process according to claim 1, wherein the fraction containing the feed for catalytic cracking of fluids is separated from the portion of liquid controlled by dragging. 6. Method according to claim 3, wherein the fraction containing the feed for catalytic cracking of fluids is separated from the liquid hydrocarbon stream, which comprises the fraction containing the feed for catalytic cracking of drag fluids. 7. Apparatus for a hydrocracking process comprising a hydrotreatment reactor, having one or more catalytic beds and having a liquid / vapor separation system located in the free space downstream of the bed or of the catalytic beds of the hydrotreatment reactor ; the liquid / vapor separation system comprises an outlet device for the removal of excess liquid by overflow together with the steam and an outlet tube for the removal of a controlled liquid portion in a separator vessel, the outlet device comprises a tube extension above the bottom of the separation vessel and a transfer tube; The tube extension has an anti-whirlpool deflector at the upper open end, the outlet tube has a separator container at the bottom, the output tube has an anti-whirlpool deflector and a flow control element through a valve flow control, characterized in that the outlet device is connected through a transfer tube to a downstream hydrocracking reactor and the outlet tube is connected through a transfer tube to an extractor or is characterized in that the Exit device is connected through a transfer tube to an extractor and the exit tube is connected through a transfer tube to a downstream hydrocracking reactor. 8. Apparatus according to claim 7, wherein the separator vessel is integrated in the hydrotreatment reactor downstream of the last catalytic bed of one or more catalytic beds. 9. Apparatus according to claim 7, wherein the separator vessel is located downstream of the hydrotreatment reactor.