MX2008007550A - Reactor for use in upgrading heavy oil admixed with a highly active catalyst composition in a slurry - Google Patents

Abstract

The instant invention relates to a reactor useful in upgrading heavy oils admixed with a catalyst composition in a slurry. The liquid recirculating reactor of this invention employs a dispersed bubble flow regime, which requires a high liquid to gas ratio. A dispersed bubble flow regime results in more even flow patterns, increasing the amount of liquid that can be upgraded in a single reactor.

Description

REACTOR FOR USE IN THE IMPROVEMENT OF HEAVY OIL MIXED WITH A COMPOSITION OF CATALYST HIGHLY ACTIVE IN ONE SUSPENSION FIELD OF THE INVENTION The present invention relates to a reactor useful in the improvement of heavy oils mixed with a catalyst composition in a suspension. BACKGROUND OF THE INVENTION A liquid recirculation reactor is highly effective for the improvement of heavy oils. The heavy hydrocarbons can be mixed with a highly active catalyst composition in the form of a suspension. The conventional upgrading of heavy oils via hydroprocessing utilizes relatively inefficient large extruded catalyst pellets to withstand the reactions. For a long time it has been recognized that there are significant advantages in using a finely divided suspension catalyst for the improvement of heavy oils via hydroprocessing. Past attempts to demonstrate the hydroprocessing of heavy oils in suspension on a large scale have fallen on upstream reactors employing bubble column technology. However, such reactors suffer from the difficulty of maintaining the desired dispersed bubble flow rate necessary for Ref .: 193908 the efficient use of reactor volume. Past problems with bubble column reactors and difficulties in maintaining the desired bubble flow regime have impeded the development of heavy oil improvement via hydroprocessing. There are examples in the prior art of rising reactors used in the hydroprocessing of heavy oils. U.S. Pat. No. 6,278,034 describes a process in which a reactor contains a bed in suspension and the feed is added to the bottom of the reactor. In the present invention a mixture of suspension and feed is added to the bottom of the reactor. There is not yet a suspension bed present in the reactor. U.S. Pat. Nos. 6,454,932 and 6,726,832 describe the hydrodisintegration of heavy hydrocarbons in upflow reactors containing serial beds of boiling catalysts. The present invention, as indicated above, employs a suspension and feed added at the bottom of the reactor. U.S. Pat. No. 4,684,456 discloses an upflow reactor employing a bed of expanded catalyst. The expansion of the bed is controlled automatically by the automatic change of the amount of speed of a recycle pump for the reactor. There is no teaching in this patent of the use of a reactor with a suspension. U.S. Pat. No. 6,660,157 describes a process for hydrodisintegration in suspension using a series of upflow reactors with separation between stages. The reactors are not liquid recirculation reactors, such as those employed in the present invention. BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a reactor useful in the improvement of heavy oils blended with a catalyst composition in a suspension. The liquid recirculation reactor of the present invention employs a flow regime of dispersed bubbles, which requires a high liquid to gas ratio. A flow regime of dispersed bubbles results in more uniform flow patterns, increasing the amount of liquid that can be improved in a single reactor. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a diagram of a liquid recirculation reactor. Figure 2 is a graph illustrating the beneficial effect of a higher ratio of liquid to gas in maintaining the flow of dispersed bubbles. Lower gas to liquid ratios result in a slow flow or continuous flow of gas.

DETAILED DESCRIPTION OF THE INVENTION The present invention is a liquid recirculation reactor suitable for hydroconversion using suspension feeds comprising heavy oil hydrocarbons and catalyst. The preparation of active suspension catalysts suitable for use in the present invention are described in the following pending applications together with the present. US Series Nos. 10/938202, 10/938269, 10/938200, 10/938438, and 10/938003. These requests are incorporated as a reference. The suspension composition is prepared by a series of steps, which include mixing a Group VIB metal oxide, such as molybdenum and aqueous ammonia to form an aqueous mixture, and sulfurizing the mixture to form a suspension. The suspension is then promoted with a Group VIII metal. The suspension is then mixed with a heavy hydrocarbon oil and combined with hydrogen gas to produce the active suspension catalyst. The catalyst is kept mixed in storage until it is combined with the feed in a hydroconversion process. The pending applications together with the present mentioned above are also suitable for additional information about the hydroconversion processes that can be used in this reactor. The processes of Hydroconversion include thermal hydrodisintegration, hydrotreating, hydrodesulfurization, hydrodenitrification and hydrodesmetalization. The feeds suitable for use in the hydroconversion processes of this reactor are selected from the group consisting of atmospheric residue, vacuum residue, tar from a deasphalting unit with solvents, atmospheric gas oils, vacuum gas oils, deasphalted oils, olefins, derived oils of bituminous sands or bitumen, oils derived from mineral coal, heavy crude oils, synthetic oils from Fischer-Tropsch processes, and oils derived from recycled waste and polymers. The recirculation reactor of the present invention is an upflow reactor in which the heavy hydrocarbon oil is mixed with a suspension comprising a catalyst and a hydrogen-rich gas at elevated pressure and temperature and hydroprocessed (preferably hydrodesintegrated) for removal of heteroatomic contaminants, such as sulfur and bnitrogen. Suitable pressures include a range of 71.82 to 167.58 KPa absolute (1500 to 3500 psia), preferably 95.76 to 143.64 KPa absolute (2000 to 3000 psia). Suitable temperatures include a range of 371.1 to 482.2 ° C (700 to 900 ° C), preferably 412.8 to 454.4 ° C (775 to 850 ° F).

The reactor generally includes a pump that recirculates liquid from near the top (outlet) of the reactor back to the bottom (inlet), typically 5-10 times the speed of the incoming heavy oil stream. In the use of the suspension catalyst, the particles are so small (such as 1-10 microns) that the recirculation of liquid with a pump is not usually necessary to create a sufficient movement of the catalyst to obtain a perfectly mixed flow effect. Pumps are used more often with extruded catalyst pellets (typically 1 mm in diameter by 2 mm in length). The material does not flow through the pump in the recirculation process, even in the use of the suspension catalyst. The conventional approach to the hydroprocessing of heavy oils has been based only on the flow of incoming liquid and gas to obtain the movement of the desired catalyst (called column of bubbles in suspension). However, a column of bubbles in suspension is limited in its ability to tolerate the large volumes of hydrogen-rich gas required for the treatment. The columns of bubbles in suspension tend to suffer due to the coalescence of bubbles (the formation of large bubbles of gas from small bubbles). The coalescence of the bubbles creates quite uneven flow patterns in the reactor that significantly reduce the performance. The amount of liquid that can be improved in a single reactor is limited. The non-economic use of multiple reactors in parallel is required. In contrast, the recirculation reactor is capable of handling larger amounts of gas (and therefore higher rates of fresh liquid feed) than conventional suspension bubble columns, while maintaining a flow of dispersed bubbles. This is due to the beneficial effect that the ratio of oil to gas (fresh feed plus recirculated liquid) has on the flow regime. The importance of this effect has not been appreciated before. Figure 1 illustrates a diagram of the preferred embodiment of the liquid recirculation reactor. The reactor 12 comprises a cylinder, which has a consistent diameter. The lower end of the reactor 12 is closed with a terminal part 17 while the upper end of the reactor is closed with a roof 18. A feed line 24, which is joined by means of the hydrogen feed line 22, reaches the lower end of reactor 12, below the inlet distributor tray. The feed comprises a mixture of heavy hydrocarbons and a catalyst suspension, together with hydrogen. The reaction occurs when moving the hydrocarbon suspension mixture and catalyst upwardly from the distributor tray. A line of product extraction from the dome 28 leaves the roof 18. Vapor comprising product and hydrogen, mixed with some suspension is transferred from the dome to spacers, while the liquid and suspension are recirculated. The gases also pass to the dome. The liquid product is separated from the catalyst particles either by internal separation or by external separation. None of these methods is shown in the diagram. A mixing device in the form of a downward duct 34 is located inside the reactor 12. The material that does not pass to the dome is recirculated through the downward duct 34. The downward duct 34 acts to maintain the profile of concentration of the catalyst and the profile of temperature along the length of the reactor 12 as uniform as possible, maintaining the bubble flow regime. The down conduit 34 comprises at its upper end a cone 38. The cone 38 contains ascending conduits that allow gases and liquids to flow upwards through the cone. The down conduit 34 has an open upper end 42, but the lower end terminates at the inlet of the recirculation pump 21. The outlet of the recirculation pump 21 (not shown) discharges material near the inlet distributor tray 20. The hydrogen is continuously combined with the feed line 24 through the line of flow 22. Sufficient hydrogen is introduced in such a manner that the surface gas velocity through the suspension bed 30 is from 2 to 6 cm / s. The suspension bed is typically maintained at a temperature in the range of about 371.1 to 482.2 ° C (700 to 900 ° F). The unreacted hydrogen is continuously withdrawn along the flow line 28. This hydrogen can be recirculated (not shown). The cone 38 of the downcomer 34 allows the volume of the gas bubbles to escape from the fluidized suspension entering the upper end 42 of the downcomer 34. The downcomer 34 transports the degassed suspension to a lower point in the reactor 12. Figure 2 illustrates the flow regimes in a three phase fluidized bed. The flow of bubbles (fluidi fication of particles), slow flow (transition zone) and continuous gas flow (fluidi fi cation of aggregation) are the three phases illustrated. The flow of bubbles, the target flow rate tends to occur in situations where there is a high ratio of liquid to gas. Figure 2 illustrates a flow of bubbles that occurs in the range of velocity relationships, u / uG that exceed 1.5 when the average superficial gas velocity is in the range of 2-6 cm / sec. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (16)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. An upflow reactor, suitable for use in a heavy oil hydroconversion process employing an active suspension catalyst, characterized in that it has an upper part, and an entrance and an exit.
2. 2. The reactor according to claim 1, characterized in that the reactor is a liquid recirculation reactor.
3. The reactor according to claim 1, characterized in that the process for heavy oil hydroconversion comprises the following steps: (a) combining, before the reactor, a heated heavy oil feed, the active suspension catalyst of claim 1 and a gas containing hydrogen to form a mixture; (b) transferring the mixture from step (a) through the reactor inlet, into a tube to the base of the reactor, the tube moving up to a distributor tray, the mixture is maintained at elevated temperature and pressure; (c) removing from the reactor outlet in the upper part of the reactor, as steam, a mixture comprising products and hydrogen, as well as unconverted material and catalyst in suspension, and transfer it to a separator before further processing; (d) recirculate material that did not pass to the dome by means of a descending conduit.
4. The reactor according to claim 2, characterized in that the liquid recirculation reactor maintains a flow of dispersed bubbles.
5. 5. The reactor according to claim 4, characterized in that the flow of dispersed bubbles is effected by a high ratio of liquid to gas.
6. 6. The reactor according to claim 5, characterized in that the speed ratios, uL / uG exceed 1.5 when the average superficial gas velocity is in the range of 2 to 6 cm / sec.
7. The reactor according to claim 1, characterized in that it additionally comprises a pump that recirculates liquid through the reactor.
8. The reactor according to claim 7, characterized in that the pump recirculates liquid typically 5 to 10 times the speed of the current entering the reactor inlet.
9. 9. The reactor according to claim 1, characterized in that the active suspension catalyst is prepared by means of a process comprising the following steps: (a) mixing a Group VIB metal oxide and aqueous ammonia to form an aqueous mixture; (b) sulfurizing the mixture to form a suspension; (c) mixing the suspension with a heavy hydrocarbon oil and hydrogen gas to produce the catalyst in active suspension.
10. 10. The reactor according to claim 9, characterized in that the metal oxide of Group VIB is molybdenum.
11. The reactor according to claim 1, characterized in that the feeds suitable for use in the hydroconversion process of claim 1 are selected from the group consisting of atmospheric residue, vacuum residue, tar from a deasphalting unit with solvents, atmospheric gas oils, vacuum gas oils, deasphalted oils, defines, oils derived from bituminous sands or bitumen, oils derived from mineral coal, heavy crude oils, synthetic oils from Fischer-Tropsch processes, and oils derived from recycled waste and polymers.
12. The reactor according to claim 1, characterized in that the hydroconversion process is selected from the group consisting of thermal hydrodisintegration, hydrotreating, hydrodesulfurization, hydrodenitrification and hydrodesmetalization.
13. The reactor according to claim 1, characterized in that the process employs a pressure in the range of 71.82 to 167.58 KPa absolute (1500 to 3500 psia).
14. The reactor according to claim 13, characterized in that the hydroconversion process employs a pressure in the range of 95.76 to 143.64 KPa absolute (2000 to 3000 psia).
15. 15. The reactor according to claim 1, characterized in that the hydroconversion process employs a temperature in the range of 371.1 to 482.2 ° C (700 to 900 ° C).
16. 16. The reactor according to claim 15, characterized in that the hydroconversion process employs a temperature in the range of 412.8 to 454.4 ° C (775 to 850 ° F).