Heavy oil slurry reactor hydrocracking method

Abstract

The invention discloses a heavy oil slurry bed hydrocracking method, which comprises a heating furnace, a slurry bed reactor, a circulating pump, a circulator, a cooler, a hot separator, a cold separator and a product fractionating tower, the hot separator is provided with a circulating pump, thereby effectively reducing temperature difference in the reactor. Compared with the conventional scheme of arranging cold hydrogen, the invention can reduce the flow of the circulator, lower the differential pressure of the reaction system and lower the overall energy consumption of the device. The bottom of the slurry bed reactor is provided with a mixed feed inlet, a hydrogen distributor and a circulating oil distributor, under the comprehensive action of the scheme, the two-phase mixing effect in the reactor is greatly enhanced, and the overall heavy oil conversion rate is increased.

Description

Technical Field

[0001] This invention relates to hydrocracking technology for coal tar and residual oil in the fields of coal chemical and petrochemical industries, specifically to a slurry-bed hydrocracking method for heavy oil. Background Technology

[0002] In recent years, with the increasing deterioration and heavier nature of crude oil, the growing demand in the consumer market for light oil products, aromatics, and chemical products made from light oil products, coupled with increasingly stringent environmental regulations, heavy oil lightening technology and heavy oil hydrocracking technology have received increasing attention. The deep processing and upgrading of heavy oil, especially low-quality residue oil / coal tar, is of great significance for the rational utilization of petroleum resources, improving product quality, and increasing the yield of light oil.

[0003] Heavy oil hydrocracking technology, based on reactor type, is generally divided into three types: fixed-bed, fluidized-bed, and slurry-bed hydrocracking. Fixed-bed heavy oil hydrocracking has high requirements for feedstocks, such as restrictions on residual carbon content and metal content, making it difficult to process low-quality heavy oil, thus limiting its widespread adoption. Fluidized-bed hydrocracking technology can process relatively low-quality heavy oil, but operating conditions are demanding and investment in the equipment is high. Slurry-bed hydrocracking technology, on the other hand, can process various low-quality feedstocks, with a relatively simple process and high conversion rate. In recent years, with the commissioning of several imported slurry-bed technologies in China, these advantages have been proven by industrial performance.

[0004] CN1349554 discloses a method for hydrogenating heavy feedstocks using an upflow reactor system with a layered catalyst bed. The method utilizes an upflow fixed-bed reactor with at least two catalysts of different hydrogenation activities to hydrogenate heavy feedstocks containing metals, sulfur, and residual carbon. However, this method has a short operating cycle, generally not exceeding one year.

[0005] CN00110714.3 discloses a method for treating heavy residue oil. Before the heavy residue oil hydrotreating system, an adsorption filter bed or a combination of an adsorption filter bed and an adsorption filter catalyst bed is used simultaneously. This not only maximizes the removal of suspended particles carried in the feedstock oil but also removes ferric naphthenate from the crude oil to form ferrous sulfide and most of the easily coking substances, minimizing scaling in the residue oil reactor system and reducing the number of start-ups and shutdowns caused by scaling during the unit's operation cycle. However, this method requires the use of two adsorption filter systems, which, with frequent switching, is detrimental to the long-term stable operation of the unit, especially with heavy residue oil as the medium.

[0006] As can be seen from the technology disclosed in the above patent applications, existing heavy oil hydrocracking technology is difficult to process low-quality heavy oil in a long-term, high-conversion-rate manner. Summary of the Invention

[0007] The purpose of this invention is to provide a heavy oil slurry bed hydrocracking method that reduces the temperature difference within the slurry bed reactor, increases the overall yield of light oil, extends the operating cycle of the unit, and reduces energy consumption and investment.

[0008] This invention includes the following steps:

[0009] 1) Heavy oil, catalyst, supplementary hydrogen and some recycled hydrogen are mixed, heated and sent to the bottom of the slurry bed reactor, mixed with recycled oil and then sent into the slurry bed reactor.

[0010] 2) The top product of the slurry bed reactor is sent to a thermal separator for flash separation. Part of the hot separated oil is returned to the slurry bed reactor as circulating oil, and the other part of the hot separated oil is sent to the product fractionation tower. The hot separated gas is cooled and sent to a cold separator for flash separation again.

[0011] 3) The cold separation gas is pressurized and mixed with the supplementary hydrogen as part of the circulating hydrogen, while the other part is heated and directly injected into the slurry bed reactor; the cold separation oil is sent to the product fractionation tower.

[0012] 4) The product fractionation tower separates dry gas, naphtha, diesel oil, wax oil and unconverted oil into other products.

[0013] A method for hydrocracking heavy oil in a slurry bed is further characterized by setting up one slurry bed reactor or multiple slurry bed reactors in series, depending on factors such as plant scale and conversion rate.

[0014] A method for hydrocracking heavy oil in a slurry bed is further characterized in that: a circulating pump is installed outside the thermal separator, and a circulating oil distributor is installed at the bottom of the slurry bed reactor; the circulating oil is pressurized by the circulating pump, and then mixed with hydrogen, catalyst, supplementary hydrogen and part of the circulating hydrogen, and then sent to the bottom of the reactor through the circulating oil distributor; the ratio of the volumetric flow rate of the circulating pump to the liquid phase volumetric flow rate of the mixed feed to the slurry bed reactor is 2 to 15.

[0015] A method for hydrocracking heavy oil in a slurry bed is further characterized in that: the reaction temperature of the slurry bed reactor is 300-400℃, the reaction pressure is 18.0-22.0 MPaG, and the temperature difference inside the reactor is below 10℃.

[0016] A method for hydrocracking heavy oil in a slurry bed is further characterized in that: at least one hydrogen distributor is provided in the slurry bed reactor, and circulating hydrogen can be injected into the slurry bed reactor at a single point or at multiple points as needed. Under the combined effect of single-point or multi-point hydrogen injection and circulating oil injection from the bottom of the reactor, the temperature difference in the reactor is reduced, the two-phase mixing effect is enhanced, and the overall conversion rate of the reactor is improved.

[0017] A method for hydrocracking heavy oil in a slurry bed is further characterized by an overall conversion rate of 93-97% wt for the heavy oil.

[0018] A method for hydrocracking heavy oil in a slurry bed is further characterized in that: the hydrogen distributor includes a hydrogen injection pipe, a cross-shaped connector, and a hydrogen distribution pipe; the cross-shaped connector includes four short pipes, each of which is clockwise connected to a hydrogen distribution pipe of different lengths. The hydrogen injection pipe is connected from top to bottom to the center of the cross-shaped connector and the outer ends of the four short pipes.

[0019] A method for hydrocracking of heavy oil in a slurry bed is further characterized in that: the hydrogen distribution pipe has two rows of holes at the bottom of the slurry bed reactor, with the two rows of holes spaced 40-100° apart; the holes in the hydrogen distribution pipe are round, rectangular, rhomboid, or square.

[0020] A method for hydrocracking of heavy oil in a slurry bed is further characterized in that: the circulating oil distributor includes a circulating oil distribution pipe, a distribution plate, and a pre-distributor, the circulating oil distribution pipe is connected above the distribution plate, and the pre-distributor is connected below the distribution plate; the pre-distributor has an opening on its side, the opening area of ​​which is 2 to 3 times the cross-sectional area of ​​the circulating oil distribution pipe.

[0021] A method for hydrocracking of heavy oil in a slurry bed is further characterized in that: the circulating oil distribution pipes are distributed in a concentric circle manner, and the circulating oil distribution pipes are arranged perpendicularly to the distribution plate or at an angle of 5 to 15°; the top of the circulating oil distribution pipe is provided with a 90° elbow, and the outlet direction of the elbow is arranged tangentially to the concentric circle; the inner diameter of the circulating oil distribution pipe is in the range of 15 to 32 mm.

[0022] The heavy oil used in this invention mainly refers to coal tar from coal chemical plants, atmospheric residue from refineries, and vacuum residue from atmospheric and vacuum distillation units. This heavy oil has high levels of sulfur, nitrogen, asphaltenes, and metals. The heavy oil undergoes a series of reactions with mixed hydrogen in a slurry bed reactor, including desulfurization, demetallization, decarbonization, denitrification, and hydrocracking.

[0023] The beneficial effects of this invention are as follows:

[0024] 1) The thermal separator is equipped with a circulating pump, which effectively reduces the temperature difference inside the reactor. Compared with the previous solution of setting cold hydrogen, this patent can reduce the flow rate of the circulating pump, reduce the differential pressure of the reaction system, and reduce the overall energy consumption of the device.

[0025] 2) A mixing inlet is installed at the bottom of the slurry bed reactor, and a circulating oil distributor is installed inside the mixing inlet. The gas-liquid two-phase medium enters the distributor from the bottom side and flows out through the distribution pipes. The distribution pipes are evenly distributed on the distribution plate, and the overall material flow forms a swirling flow, which enhances the fluid flow on the reactor sidewall. At the same time, a hydrogen distributor is installed, with hydrogen entering from the top and exiting from the bottom, contacting the mixing feed in the opposite direction. The hydrogen is evenly distributed in each dispersion channel of the distribution pipe, and fully contacts and mixes with the two-phase feed. Under the combined effect of the above scheme, the two-phase mixing effect in the reactor is greatly enhanced, and the overall heavy oil conversion rate is improved. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the present invention;

[0027] Figure 2 Top view of the hydrogen distributor;

[0028] Figure 3 Side view of the hydrogen distributor;

[0029] Figure 4 A bottom view of the hydrogen distributor's distribution pipe;

[0030] Figure 5 Top view of the distribution pipe arrangement for the circulating oil distributor;

[0031] Figure 6 Side view of the circulating oil distributor;

[0032] In the diagram: 1. Heating furnace; 2. Slurry bed reactor; 3. Circulating pump; 4. Circulating oil distributor; 5. Circulating machine; 6. Cooler; 7. Thermal separator; 8. Cold separator; 9. Product fractionation tower; 10. Hydrogen distributor; 11. Hydrogen injection pipe; 12. Short pipe; 13. Hydrogen distribution pipe; 14. Circulating oil distribution pipe; 15. Distribution plate; 16. Pre-distributor. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings:

[0034] like Figures 1-6 As shown, the mixed hydrogen, consisting of supplementary hydrogen and some recycled hydrogen, is mixed with heavy oil and catalyst, and heated to the reaction temperature by heater 1 before being sent to the bottom of slurry bed reactor 2. Some recycled hydrogen, after being heated by heater 1, is injected at multiple points into hydrogen distributors 10 at different heights to enhance the mixing effect of hydrogen, mixed feed, and recycled oil. The circulating liquid at the bottom of thermal separator 7 is sent to circulating pump 3, where it is pressurized and mixed with heavy oil, catalyst, and mixed hydrogen before being sent to circulating oil distributor 4 at the bottom of the reactor.

[0035] The reaction products flow from the top of the slurry bed reactor 2 to the hot separator 7 for flash separation. The hot-separated gas phase is cooled by the cooler 6 and then flows to the cold separator 8. The hot-separated oil and the cold-separated oil are sent to the product fractionation tower 9. The gas phase in the cold separator 8 is circulating hydrogen rich in hydrogen gas. It is pressurized by the circulating machine 5. Part of the circulating hydrogen is mixed with supplementary hydrogen and then mixed with heavy oil and catalyst; the other part is heated by the heater 1 and then injected into the slurry bed reactor. The oil phase flows to the product fractionation tower 9 and is separated into dry gas, naphtha, diesel, wax oil, and unconverted oil, etc.

[0036] The hydrogen distributor 10 includes a hydrogen injection pipe 11, a cross-shaped connector, and a hydrogen distribution pipe 13. The cross-shaped connector includes four short pipes 12, each of which is connected clockwise to a hydrogen distribution pipe 13 of different lengths. The hydrogen injection pipe 11 is connected from top to bottom to the center of the cross-shaped connector and the outer ends of the four short pipes 12. Each distribution pipe has two rows of circular holes extending towards the bottom of the slurry bed reactor, with the two rows of holes spaced 70° apart.

[0037] The circulating oil distributor 4 includes a circulating oil distribution pipe 14, a distribution plate 15, and a pre-distributor 16. The circulating oil distribution pipe 14 is connected above the distribution plate 15, and the pre-distributor 16 is connected below the distribution plate 15. The pre-distributor 16 has an opening on its side, and the opening area is 2.5 times the cross-sectional area of ​​the circulating oil distribution pipe. The circulating oil distribution pipes are distributed in a concentric circle manner, and the circulating oil distribution pipes are arranged at an inclination of 10° to the distribution plate. The top of the circulating oil distribution pipe is provided with a 90° elbow, and the outlet direction of the elbow is tangential to the concentric circle.

[0038] In this embodiment, the ratio of the circulating pump volumetric flow rate to the liquid phase volumetric flow rate of the slurry bed reactor feed is 2–15; the preferred range for the circulation rate / feed rate is 3–6 m³ / s. 3 / m 3 The reaction temperature in the slurry bed reactor is 300–400℃, with a preferred range of 320–360℃; the reaction pressure is 18.0–22.0 MPaG, with a preferred range of 19–20 MPaG; and the temperature difference within the reactor is below 10℃. The overall heavy oil conversion rate is 93–97% wt.

[0039] The above are merely typical embodiments of the present invention. Those skilled in the art can make appropriate modifications and improvements based on them, but they are substantially the same as the present invention and also fall within the protection scope of the present invention.

Claims

1. A method for hydrocracking heavy oil in a slurry bed, characterized in that... Includes the following steps: 1) Heavy oil, catalyst, supplementary hydrogen and some recycled hydrogen are mixed, heated and sent to the bottom of the slurry bed reactor, mixed with recycled oil and then sent into the slurry bed reactor. 2) The top product of the slurry bed reactor is sent to a thermal separator for flash separation. Part of the hot separated oil is returned to the slurry bed reactor as circulating oil, and the other part of the hot separated oil is sent to the product fractionation tower. The hot separated gas is cooled and sent to a cold separator for flash separation again. 3) The cold separation gas is pressurized and mixed with the supplementary hydrogen as part of the circulating hydrogen, while the other part is heated and directly injected into the slurry bed reactor; the cold separation oil is sent to the product fractionation tower. 4) The product fractionation tower separates dry gas, naphtha, diesel oil, wax oil and unconverted oil into other products.

2. The method for heavy oil slurry bed hydrocracking according to claim 1, characterized in that: The thermal separator is equipped with an external circulation pump, and the bottom of the slurry bed reactor is equipped with a circulation oil distributor. The circulation oil is pressurized by the circulation pump, and then mixed with hydrogen, catalyst, supplementary hydrogen and part of the circulation hydrogen before being sent to the bottom of the reactor through the circulation oil distributor. The ratio of the volumetric flow rate of the circulation pump to the liquid phase volumetric flow rate of the mixed feed in the slurry bed reactor is 2 to 15.

3. The method for heavy oil slurry bed hydrocracking according to claim 1, characterized in that: The reaction temperature of the slurry bed reactor is 300-400℃, the reaction pressure is 18.0-22.0 MPaG, and the temperature difference inside the reactor is less than 10℃.

4. The method for heavy oil slurry bed hydrocracking according to claim 1, characterized in that: The slurry bed reactor is equipped with at least one hydrogen distributor; circulating hydrogen is injected into the slurry bed reactor at one or more points.

5. The method for heavy oil slurry bed hydrocracking according to claim 2, characterized in that: The circulating oil distributor includes a circulating oil distribution pipe, a distribution disc, and a pre-distributor. The circulating oil distribution pipe is connected above the distribution disc, and the pre-distributor is connected below the distribution disc. The pre-distributor has an opening on its side, and the opening area is 2 to 3 times the cross-sectional area of ​​the circulating oil distribution pipe.

6. The method for heavy oil slurry bed hydrocracking according to claim 5, characterized in that: The circulating oil distribution pipes are distributed in a concentric circle pattern. The circulating oil distribution pipes are arranged perpendicular to the distribution plate or at an angle of 5 to 15°. The top of the circulating oil distribution pipe is equipped with a 90° elbow, and the outlet direction of the elbow is tangential to the concentric circle. The inner diameter of the circulating oil distribution pipe is 15 to 32 mm.

7. The method for heavy oil slurry bed hydrocracking according to claim 4, characterized in that: The hydrogen distributor includes a hydrogen injection pipe, a cross connector, and a hydrogen distribution pipe. The cross connector includes four short pipes, each of which is connected clockwise to a hydrogen distribution pipe of different lengths. The hydrogen injection pipe is connected from top to bottom to the center of the cross connector and the outer ends of the four short pipes.

8. The method for heavy oil slurry bed hydrocracking according to claim 7, characterized in that: The hydrogen distribution pipe has two rows of holes at the bottom of the slurry bed reactor, with the two rows of holes spaced 40-100° apart; the holes in the hydrogen distribution pipe can be round, rectangular, diamond-shaped or square.

9. The method for heavy oil slurry bed hydrocracking according to claim 1, characterized in that: The overall conversion rate of heavy oil is 93-97% wt.

10. A method for heavy oil slurry bed hydrocracking according to claim 1, characterized in that: Set up one slurry bed reactor or multiple slurry bed reactors in series.

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