Heavy oil supercritical extraction separation method and separation device

Abstract

The invention discloses a heavy oil supercritical extraction separation method and a separation device, and the method comprises the following steps: (1) carrying out extraction separation on a heavy oil raw material and an extraction solvent in an extraction tower to obtain an extraction phase and a raffinate phase; the extraction solvent is composed of a main solvent and a cosolvent, the main solvent is selected from one or more of C4-C5 hydrocarbons, and the cosolvent is carbon dioxide; (2) carrying out supercritical solvent recovery on the extraction phase to obtain a supercritical recovery solvent and an extraction oil solution in which a small amount of extraction solvent is dissolved; (3) carrying out first solvent recovery on the extracted oil solution dissolved with a small amount of solvent to obtain deasphalted oil; and carrying out second solvent recovery on the raffinate phase to obtain deoiled asphalt. According to the supercritical extraction separation method of the heavy oil, the main solvent and the carbon dioxide are mixed to serve as the extraction solvent, the dissolving capacity and selectivity of C4-C5 hydrocarbons are adjusted, the agent-oil ratio in the heavy oil extraction separation process can be reduced, rapid and efficient extraction separation of the heavy oil is achieved under the condition of the low agent-oil ratio, and energy consumption is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of petroleum chemical industry, and relates to a method and a device for selective extraction, more particularly, to a method and a device for separating heavy oil by using a mixed organic and inorganic solvent. BACKGROUND

[0002] Under the influence of multiple factors such as overcapacity of oil refining, impact of new energy, etc., the competition in the product oil market is intensified, and the demand is sluggish. Therefore, the traditional fuel type refinery needs to be transformed into a refinery-chemical integration. Component refining can select appropriate components as raw materials according to target products, avoid the "running suit" behavior of materials in the processing process, reduce molecular structure changes, reduce energy consumption and processing cost, and realize the use of suitable components. Component separation is the basis for realizing component refining, and the difficulty and key of component separation is how to realize high selectivity and economy of separation.

[0003] Solvent deasphalting technology can realize component separation of heavy oil. The traditional solvent deasphalting is a subcritical extraction-supercritical solvent recovery process, and a large solvent-to-oil ratio is used, and the solvent-to-oil ratio is 3-5 by mass. At present, the solvent-to-oil ratio used in the solvent deasphalting industrial device is 2.5-3:1 by mass, and the energy consumption is relatively high. In order to obtain a higher deasphalted oil yield, the main means is to reduce the extraction temperature and increase the solvent ratio, which leads to an increase in energy consumption. The viscosity of heavy oil raw material is high at low temperature, which affects the mass transfer efficiency, and the deasphalted oil yield corresponding to a high softening point of the deoiled asphalt product is easy to cause blockage and affect the reliability of the device. The operating temperature of supercritical extraction technology is high, the viscosity of heavy oil raw material is small, the extraction solvent has the density and solubility of liquid, and the diffusion speed is fast, but the density of the solvent under supercritical conditions changes very sensitively with temperature and pressure, and generally a pressure of more than 10 MPa is needed, which leads to a large investment of the device.

[0004] Supercritical carbon dioxide extraction is a green and environmentally friendly extraction technology, which is often used for extracting active ingredients from natural plants, fine chemical products, etc. For heavy oil extraction, high-pressure equipment (>20 MPa) is needed to control temperature and pressure, which increases the cost of equipment. The solubility of supercritical carbon dioxide is greatly affected by factors such as temperature and pressure, and the process conditions need to be accurately controlled, which has high operation requirements. The extraction effect of some polar and high molecular compounds is poor, the oil yield is low, and the scope of application has certain limitations.

[0005] CN102690678A discloses a processing method for inferior heavy crude oil. The atmospheric residue of inferior heavy crude oil is mixed with a solvent into an extraction tower, and the volume ratio of the solvent to the atmospheric residue is 3-12:1. The solvent is separated by a solvent extraction process under supercritical conditions to obtain solvent refined oil and solvent refined residual oil. The solvent is selected from one or more of C3-C5 alkanes or alkenes.

[0006] CN107177373A discloses a supercritical residue and / or catalytic slurry oil treatment system and treatment method, which extracts residue and / or slightly oxidized catalytic slurry oil under subcritical conditions, and then recovers solvent under supercritical conditions, thereby greatly reducing device energy consumption and simplifying process operation.

[0007] CN104740894A discloses an extraction system and method for coal liquefaction residue, which comprises a supercritical carbon dioxide generating unit and an extraction unit in communication with the supercritical carbon dioxide generating unit. The extraction method comprises: performing carbon dioxide supercritical extraction on coal liquefaction residue to obtain an extraction liquid containing heavy liquefied oil in the coal liquefaction residue. The carbon dioxide supercritical extraction is performed in the presence of an entraining agent (n-hexane and / or coal liquefaction light oil), the weight ratio of the entraining agent to the supercritical state carbon dioxide is 10:100-40:100, the temperature of the supercritical carbon dioxide extraction is 40-80℃, and the pressure is 30-45MPa.

[0008] CN110114442A discloses a method for producing deasphalted oil by combining a supercritical water stream with a hydrocarbon-based composition in a mixing device and then introducing into a supercritical reactor to produce deasphalted oil, and the critical conditions of water are 374.15℃ and 22.13MPa.

[0009] CN103979757A discloses a method for treating oily sludge by supercritical fluid multi-stage extraction-coupling cracking, which uses supercritical water to crack oily sludge, and then performs gradient extraction on the heavy components by using a mixture of supercritical carbon dioxide, supercritical propane, supercritical fluorine 134a, supercritical n-pentane and supercritical iso-pentane as an extraction agent, with a mass ratio of 5-6:1. The operation conditions are harsh, and the device is complex. The above technologies have the limitations of large device investment, high operation requirement, large solvent consumption and high energy consumption. SUMMARY

[0010] The technical problem to be solved by the present application is to provide a heavy oil separation method with low solvent consumption, so as to solve the problems of large solvent consumption and high recovery energy consumption in the prior art.

[0011] In a first aspect, the present application provides a heavy oil supercritical extraction separation method, comprising:

[0012] (1) performing extraction separation on heavy oil raw materials and extraction solvent in an extraction tower to obtain an extraction phase and a raffinate phase; the extraction solvent is composed of a main solvent and a cosolvent, the main solvent is selected from one or more of C4-C5 hydrocarbons, and the cosolvent is carbon dioxide;

[0013] (2) the extraction phase is subjected to supercritical solvent recovery to obtain recovered solvent and an extraction oil solution containing a small amount of solvent;

[0014] (3) the extraction oil solution containing a small amount of solvent is subjected to first solvent recovery to obtain deasphalted oil; the raffinate phase is subjected to second solvent recovery to obtain deoiled asphalt.

[0015] In the present application, the heavy oil feedstock has a distillation range > 350℃, a density of 900-1200 kg / m 3 at 20℃, a carbon residue value of 5-30%, and an asphaltene content of 0.5-20 wt%. Preferably, the heavy oil feedstock is atmospheric residue and / or vacuum residue.

[0016] In a second aspect, the present application provides a heavy oil extraction separation device, which comprises: an extraction column for extracting and separating heavy oil and extraction solvent to obtain an extraction phase and a raffinate phase; the extraction column is provided with an upper heavy oil feedstock inlet, a lower extraction solvent inlet, a top outlet and a bottom outlet;

[0017] a solvent recovery column for recovering extraction solvent in the extraction phase under supercritical conditions to obtain extraction solvent and an extraction oil solution; the solvent recovery column is provided with an inlet, a top outlet and a bottom outlet, the top outlet of the extraction column is connected to the solvent recovery column, and the top outlet of the recovery column is connected to the lower extraction solvent inlet of the extraction column;

[0018] a first solvent recovery column for further recovering extraction solvent in the extraction oil solution to obtain extraction oil and extraction solvent; the bottom of the solvent recovery column is connected to the feed inlet of the first solvent recovery column;

[0019] a second solvent recovery column for recovering extraction solvent in the raffinate phase to obtain raffinate oil and extraction solvent; the bottom of the extraction column is connected to the second solvent recovery column;

[0020] a carbon dioxide mixer for mixing liquid-phase carbon dioxide and main solvent to obtain extraction solvent; the carbon dioxide mixer comprises a static mixer, a carbon dioxide pipeline connected to a first inlet of the static mixer through a pressurizing pump, a main solvent pipeline connected to a second inlet of the static mixer through a solvent pump, and an outlet of the static mixer connected to the lower inlet of the extraction column.

[0021] The heavy oil supercritical extraction separation method and separation device provided by the present application have the following beneficial effects:

[0022] The extraction solvent used in the present application mainly uses C4-C5 hydrocarbons as the main solvent and uses carbon dioxide as the cosolvent to adjust the solubility and selectivity of the C4-C5 hydrocarbon solvent and to exert the excellent diffusion capacity thereof, so that the solvent-oil ratio of the heavy oil extraction separation process can be reduced. Compared with the prior art, the solvent-oil ratio is 1.0-2.0:1, which is reduced by 30%-50% compared with the existing solvent deasphalting industrial device, and the rapid and efficient extraction separation of heavy oil can be realized under the condition of low solvent-oil ratio, and the energy consumption is significantly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] BRIEF DESCRIPTION OF DRAWINGS Figure 1 The flowchart of the heavy oil supercritical extraction separation method provided by the present application is shown.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] I-extraction column II-supercritical solvent recovery column III-first solvent recovery column

[0026] IV-second solvent recovery column V-gas-liquid separation column VI-carbon dioxide liquefaction device

[0027] VII-static mixer 1-heavy oil raw material 2-extraction solvent

[0028] 3-extraction phase 4-extracted phase 5-supercritical recovery solvent

[0029] 6-extracted oil solution 7-deasphalted oil 8-first solvent

[0030] 9-second solvent 10-gaseous carbon dioxide 11-liquid main solvent

[0031] 12-liquid carbon dioxide 13-deoiled asphalt DETAILED DESCRIPTION

[0032] The specific embodiments of the present application will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0033] In the present application, the terms "upper", "lower", "bottom" are based on the relative position relationship of the container or component. Among them, the "bottom" refers to the position of 0-10% from the bottom to the top of the container, and the "top" refers to the position of 90-100% from the bottom to the top of the container.

[0034] In a first aspect, the present application provides a heavy oil supercritical extraction separation method, which comprises the following steps:

[0035] (1) extracting and separating the heavy oil feedstock and an extraction solvent in an extraction column to obtain an extraction phase and a raffinate phase; the extraction solvent is composed of a main solvent and a cosolvent, the main solvent is selected from one or more of C4-C5 hydrocarbons, and the cosolvent is carbon dioxide;

[0036] (2) supercritical solvent recovery of the extraction phase to obtain a supercritical recovery solvent and an extraction oil solution with a small amount of solvent;

[0037] (3) first solvent recovery of the extraction oil solution with a small amount of solvent to obtain deasphalted oil; and second solvent recovery of the raffinate phase to obtain deoiled asphalt.

[0038] In the present application, the distillation range of the heavy oil feedstock is > 350℃, the density at 20℃ is 900-1200 kg / m 3 , the carbon residue value is 5-30%, and the asphaltene content is 0.5-20 wt%.

[0039] Preferably, the heavy oil feedstock is selected from atmospheric residue and / or vacuum residue.

[0040] Preferably, the weight ratio of the extraction solvent to the heavy oil feedstock is 1.0-2.0:1, preferably 1.5-2.0:1, and more preferably 1.5-1.8:1, and the mole fraction of carbon dioxide in the extraction solvent is 2-55%, preferably 5-30%.

[0041] In the present application, the extraction separation is carried out in an extraction column, specifically, the heavy oil feedstock is fed from the middle of the column, countercurrently contacted with the extraction solvent fed from the bottom of the column for extraction, the extraction phase flows out from the top of the column, and the raffinate phase flows out from the bottom of the column.

[0042] Preferably, the conditions of the extraction separation include a pressure of 4.5-10 MPa and an extraction temperature of 50℃ below the virtual critical temperature Tc of the main solvent, wherein the virtual critical temperature Tc is the sum of the critical temperature and the mole fraction of each component in the extraction solvent.

[0043] Preferably, the conditions of the extraction separation include a pressure of 5.0-7.5 MPa and a temperature of (Tc-40)-(Tc-5)℃.

[0044] In the present application, the supercritical solvent recovery of the extraction phase is carried out in a supercritical solvent recovery column. Specifically, the extraction phase is fed from the middle of the supercritical solvent recovery column after being heated and warmed up, the supercritical recovery solvent flows out from the top of the column, and the extraction oil solution with a small amount of solvent is discharged from the bottom of the column. The carbon dioxide content of the supercritical recovery solvent is slightly higher than that of the extraction solvent, and the mole fraction of carbon dioxide is 3-60%. Preferably, the supercritical recovery solvent obtained in step (2) is recycled after being heated and returned to the extraction column. The content of the extraction solvent in the obtained extraction oil solution is 10-20 wt%, and the content of the deasphalted oil is 80-90 wt%.

[0045] Preferably, the supercritical solvent recovery in step (2) is carried out at a pressure of 4.5-8 MPa and a temperature higher than the virtual critical temperature Tc of the extraction solvent.

[0046] Preferably, the supercritical solvent recovery is carried out at a pressure of Pc-7.5 MPa and a temperature of (Tc+20)-(Tc+60) °C, where Pc is the virtual critical pressure, which is the sum of the critical pressure of each component in the extraction solvent and its mole fraction.

[0047] In a specific embodiment of the present application, the main solvent is C4 alkane, the critical temperature of which is 135-151.9 °C, and the critical pressure is 3.65-3.79 MPa. The cosolvent is carbon dioxide, the critical temperature of which is 31.3 °C, and the critical pressure is 7.38 MPa. In the extraction solvent, the mole fraction of C4 alkane is 70-95%, and the mole fraction of carbon dioxide is 5-30%. The virtual critical temperature Tc of the extraction solvent is 100-149 °C, and the virtual critical pressure Pc is 4.0-7.2 MPa. The extraction separation is carried out at a temperature of 50-149 °C, preferably 80-143 °C, and a pressure of 5.0-7.5 MPa. After separation, the content of the extraction solvent in the extraction phase is 55-90 wt%, and the content of the deasphalted oil is 10-50 wt%. The content of the extraction solvent in the raffinate phase obtained by separation is 25-40 wt%, and the content of the deoiled asphalt is 60-75 wt%.

[0048] The supercritical solvent recovery in step (2) is carried out at a pressure of 4.5-7.5 MPa and a temperature higher than Tc, preferably 170-210 °C. The composition of the extraction solvent obtained by supercritical solvent recovery is 5-35% carbon dioxide, the temperature is 170-210 °C, and the pressure is 4.5-7.5 MPa. The recovered solvent obtained by separation is recycled. The content of the extraction solvent in the extraction oil solution obtained by separation is 10-20 wt%, and the content of the deasphalted oil is 80-90 wt%. Further solvent separation is required to obtain the extraction solvent and the deasphalted oil. The obtained deasphalted oil can be used as a lubricating oil, a ship fuel, a catalyst, etc.

[0049] The raffinate phase separated by the extraction column is subjected to solvent separation to obtain extraction solvent and deoiled asphalt. The deoiled asphalt is used as raw material for coking, asphalt, gasification and the like.

[0050] In one embodiment of the present application, the main solvent is C5 alkane, the critical temperature of which is 187.8-196.4℃, and the critical pressure is 3.33-3.37 MPa; the cosolvent is carbon dioxide, the critical temperature of which is 31.3℃, and the critical pressure is 7.38 MPa; in the extraction solvent, the molar fraction of C5 alkane is 70-95%, and the molar fraction of carbon dioxide is 5-30%, the pseudo-critical temperature Tc is 123-191℃, and the pseudo-critical pressure Pc is 3.5-7.2 MPa. The temperature of the extraction separation is 80-190℃, preferably 110-185℃; the extraction separation pressure is 4.5-7.5 MPa. After the separation, the content of the extraction solvent in the extraction phase is 50-80 wt%, and the content of the deasphalted oil is 20-50 wt%; the content of the extraction solvent in the raffinate phase obtained by the separation is 25-40 wt%, and the content of the deoiled asphalt is 60-75 wt%.

[0051] In step (2), the pressure of the supercritical solvent recovery is 4.5-7.5 MPa, and the temperature is higher than Tc, preferably 180-230℃; the composition of the extraction solvent obtained by the supercritical solvent recovery is carbon dioxide with a mass fraction of 5-35%, the temperature is 180-230℃, and the pressure is 4.5-7.5 MPa; the extraction solvent obtained by the separation is recycled.

[0052] In one embodiment of the present application, the main solvent is C4 and C5 alkane, the main components of which are: n-butane with a molar fraction of 5-95%, and the cosolvent is carbon dioxide, the pseudo-critical temperature Tc of which is 100-191℃, and the pseudo-critical pressure Pc is 3.5-7.2 MPa. The temperature of the extraction separation is 50-190℃, preferably 80-180℃; the extraction separation pressure is 4.5-7.5 MPa. After the separation, the content of the extraction solvent in the extraction phase is 50-90 wt%, and the content of the deasphalted oil is 10-50 wt%; the content of the extraction solvent in the raffinate phase obtained by the separation is 25-40 wt%, and the content of the asphaltene is 60-75 wt%. In step (2), the pressure of the supercritical solvent recovery is 4.5-7.5 MPa, and the temperature is higher than Tc, preferably 170-230℃; the composition of the extraction solvent obtained by the supercritical solvent recovery is carbon dioxide with a mass fraction of 5-35%, the temperature is 170-230℃, and the pressure is 4.5-7.5 MPa.

[0053] In the present application, the mass fraction of the extraction solvent in the extraction oil solution from the bottom of the solvent recovery column is 10-20wt%, and the extraction solvent is further recovered in the first solvent recovery column. Specifically, the recovery method can be conventional flash evaporation or stripping, and the column is provided with trays, the gaseous phase recovery solvent flows out from the top of the column, and the liquid phase deasphalted oil is pumped out from the bottom of the column through a deasphalted oil product pump; the raffinate phase from the extraction column contains 25-40wt% of the extraction solvent, and the extraction solvent is recovered in the second solvent recovery column. Specifically, the recovery method can be conventional flash evaporation or stripping, and the column is provided with trays, the gaseous phase recovery solvent flows out from the top of the column, and the liquid phase deoiled asphalt is pumped out from the bottom of the column through a deoiled asphalt product pump.

[0054] The first solvent recovery conditions in step (3) are as follows: the temperature is (Tc+50)-(Tc+100)℃, more preferably (Tc+60)-(Tc+80)℃, and the pressure is 0.2-1MPa, more preferably 0.5-0.8MPa.

[0055] The second solvent recovery conditions in step (3) are preferably as follows: the temperature is (Tc+50)-(Tc+100)℃, more preferably (Tc+60)-(Tc+80)℃, and the pressure is 0.2-1MPa, more preferably 0.5-0.8MPa.

[0056] Preferably, the separation method further comprises: mixing the extraction solvents recovered by the first and second solvent recovery columns, and cooling and separating the mixture into a liquid phase main solvent and a gaseous phase carbon dioxide, and then mixing the gaseous phase carbon dioxide after being pressurized and cooled into a liquid phase carbon dioxide with the liquid phase main solvent to return to the extraction column as the extraction solvent for recycling.

[0057] In a second aspect, the present application provides a heavy oil extraction and separation device, which comprises:

[0058] an extraction column for extracting and separating heavy oil and an extraction solvent to obtain an extraction phase and a raffinate phase; the extraction column is provided with an upper heavy oil raw material inlet, a lower extraction solvent inlet, a top outlet and a bottom outlet;

[0059] a solvent recovery column for recovering the extraction solvent in the extraction phase under supercritical conditions to obtain an extraction solvent and an extraction oil solution; the solvent recovery column is provided with an inlet, a top outlet and a bottom outlet, the top outlet of the extraction column is connected to the solvent recovery column, and the top outlet of the recovery column is connected to the lower extraction solvent inlet of the extraction column;

[0060] a first solvent recovery column for further recovering the extraction solvent in the extraction oil solution to obtain extraction oil and extraction solvent; the bottom of the solvent recovery column is connected to the feed inlet of the first solvent recovery column;

[0061] a second solvent recovery column for recovering the extraction solvent in the raffinate phase to obtain raffinate oil and extraction solvent; the bottom of the extraction column is connected to the second solvent recovery column;

[0062] a carbon dioxide mixer for mixing liquid carbon dioxide and main solvent to obtain extraction solvent; the mixer comprises a static mixer, a carbon dioxide pipeline connected to the first inlet of the static mixer through a pressurized pump, a main solvent pipeline connected to the second inlet of the static mixer through a solvent pump, and the outlet of the static mixer connected to the lower inlet of the extraction column.

[0063] In a preferred embodiment, the separation device further comprises:

[0064] a gas-liquid separation column for separating gaseous carbon dioxide; the top of the first solvent recovery column and the top of the second solvent recovery column are respectively connected to the gas-liquid separation column;

[0065] a carbon dioxide liquefying device for pressurized liquefaction of gaseous carbon dioxide to obtain liquid carbon dioxide; the gaseous phase outlet of the gas-liquid separation column is connected to the carbon dioxide liquefying device, and the outlet of the carbon dioxide liquefying device and the liquid phase outlet of the gas-liquid separation column are respectively connected to the static mixer.

[0066] The heavy oil extraction separation device provided by the present application further comprises necessary heat exchangers, solvent pumps and pipelines, which are conventional devices in the field, and will not be described in detail herein.

[0067] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, but the drawings and embodiments do not constitute limitations on the present application.

[0068] Fig. 1 is a flow diagram of a heavy oil supercritical separation method provided by the present application. Figure 1 Fig. 1 is a flow diagram of a heavy oil supercritical separation method provided by the present application. Figure 1 As shown in Fig. 1, pressurized and heated heavy oil raw material 1 is fed into the upper part of extraction column I, and extraction solvent 2 is fed into the lower part of extraction column I, and the two are countercurrently extracted in extraction column I. Extraction column I can be a rotating disc column, sieve plate column or packed column known to all, or can be an empty column, and the form is not limited. Extraction phase 3 flows out from the top of extraction column I, and the extraction phase is oil extracted by the solvent and most of the extraction solvent. Extraction phase 3 enters solvent recovery column II for supercritical solvent recovery to separate most of the solvent and extraction oil. Extraction oil solution 6 containing a small amount of solvent flows out from the bottom of solvent recovery column II and enters first solvent recovery column III to separate extraction solvent and extraction oil, which generally adopts the method of stripping recovery and / or flashing. Raffinate phase 4 flows out from the bottom of extraction column I and enters second solvent recovery column IV to separate solvent and raffinate oil, which generally adopts the method of stripping recovery and / or flashing.

[0069] The gas phase extraction solvent recovered by the first and second recovery units is cooled and then enters a gas-liquid separation tower V for gas-liquid separation. The liquid phase main solvent 11 flows out from the bottom of the tower, and the gaseous phase carbon dioxide 10 flows out from the top of the tower and then enters a carbon dioxide liquefaction unit VI. After being pressurized by a compressor, the carbon dioxide is liquefied and then further cooled. Then, the carbon dioxide is mixed with the main solvent in a static mixer VII and then enters the lower part of the extraction tower for recycling.

[0070] The method and technical effects of the present application are specifically described below through examples. However, the protection scope of the present application is not limited in this way.

[0071] In the examples and comparative examples,

[0072] The residual oil feedstock A is taken from the Jilin Petrochemical Branch Company of China Petroleum Natural Gas Co., Ltd., the residual oil feedstock B is taken from the Hunan Petrochemical Branch Company of China Petroleum Chemical Industry Co., Ltd., and the residual oil feedstock C is taken from the Yanshan Petrochemical Branch Company of China Petroleum Chemical Industry Co., Ltd.

[0073] The analysis methods involved are 20℃ density (SH / T 0604), kinematic viscosity (GB / T11137), carbon residue value (GB / T17144), CH content (SH / T 0656), sulfur content (GB / T17040), nitrogen content (SH / T 0704), four components (SH / T0753), and metal content (ICP).

[0074] The energy consumption is estimated according to the “Standard for Energy Consumption Calculation of Petroleum and Chemical Engineering Design” (GB / T50441-2016).

[0075] Example 1

[0076] The heavy oil feedstock used is the residual oil feedstock A of a conventional butane deasphalting device, and its properties are shown in Table 1.

[0077] In the solvent extraction unit, the mixed solvent of n-butane and carbon dioxide is used as the extraction solvent, the molar fraction of carbon dioxide is 10%, the critical temperature of n-butane is 151.9℃, and the critical pressure is 3.79MPa; the critical temperature of carbon dioxide is 31.3℃, and the critical pressure is 7.38MPa; Tc=0.9*151.9+0.1*31.3=139.8, Pc=0.9*3.79+0.1*7.38=4.15, the Tc of the extraction solvent is 139.8℃, and the Pc is 4.15MPa.

[0078] The temperature of the extraction column was 130°C, the pressure was 5.0 MPa, and the solvent / oil ratio was 1.7:1 by mass. The temperature of the supercritical solvent recovery column was 180°C, and the pressure was 7.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The properties of the extracted oil and the raffinate oil obtained are shown in Table 2. The energy consumption results are shown in Table 2.

[0079] Comparative Example 1

[0080] The extraction separation feedstock used was the same as in Example 2. A conventional subcritical extraction-supercritical solvent recovery solvent deasphalting method was used. In the solvent extraction unit, a mixed solvent of n-butane and carbon dioxide was used as the extraction solvent, the mole fraction of carbon dioxide was 10%, Tc was 179.9°C, and Pc was 3.77 MPa. The temperature of the extraction column was 150°C, the pressure was 5.0 MPa, and the solvent / oil ratio was 1.5:1 by mass. The temperature of the supercritical solvent recovery column was 220°C, and the pressure was 7.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The properties of the extracted oil and the raffinate oil obtained are shown in Table 2. The energy consumption results are shown in Table 2.

[0081] The temperature of the extraction column was 140°C, the pressure was 5.0 MPa, and the solvent / oil ratio was 2.6:1 by mass. The temperature of the supercritical solvent recovery column was 210°C, and the pressure was 4.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The energy consumption results are shown in Table 2.

[0082] Example 2

[0083] The heavy oil feedstock used was Residual Oil Feedstock B of a conventional pentane deasphalting unit, the properties of which are shown in Table 1.

[0084] In the solvent extraction unit, a mixed solvent of n-pentane and carbon dioxide was used as the extraction solvent, the mole fraction of carbon dioxide was 10%, Tc was 179.9°C, and Pc was 3.77 MPa. The temperature of the extraction column was 150°C, the pressure was 5.0 MPa, and the solvent / oil ratio was 1.5:1 by mass. The temperature of the supercritical solvent recovery column was 220°C, and the pressure was 7.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The properties of the extracted oil and the raffinate oil obtained are shown in Table 2. The energy consumption results are shown in Table 2.

[0085] Comparative Example 2

[0086] The extraction separation feedstock used was the same as in Example 2. A conventional subcritical extraction-supercritical solvent recovery solvent deasphalting method was used. In the solvent extraction unit, a mixed solvent of n-pentane and carbon dioxide was used as the extraction solvent, the mole fraction of carbon dioxide was 10%, Tc was 179.9°C, and Pc was 3.77 MPa. The temperature of the extraction column was 150°C, the pressure was 5.0 MPa, and the solvent / oil ratio was 1.5:1 by mass. The temperature of the supercritical solvent recovery column was 220°C, and the pressure was 7.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The properties of the extracted oil and the raffinate oil obtained are shown in Table 2. The energy consumption results are shown in Table 2.

[0087] The temperature of the extraction column was 195°C, the pressure was 5.0 MPa, and the solvent to oil ratio was 2.5:1 by mass. The temperature of the supercritical solvent recovery column was 230°C, and the pressure was 4.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The energy consumption results are shown in Table 2.

[0088] Example 3

[0089] The heavy oil feedstock used was a residual oil feedstock C from a conventional pentane deasphalting unit, the properties of which are shown in Table 1.

[0090] In the solvent extraction unit, a mixed solvent of n-butane and n-pentane was used as the main solvent, the mole fraction of n-butane was 40%, the mole fraction of n-pentane was 50%, and the mole fraction of carbon dioxide was 10%. The calculated Tc was 162.1°C, and the Pc was 3.94 MPa.

[0091] The temperature of the extraction column was 140°C, the pressure was 5.0 MPa, and the solvent to oil ratio was 1.8:1 by mass. The temperature of the supercritical solvent recovery column was 240°C, and the pressure was 4.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The properties of the extracted oil and the raffinate oil obtained are shown in Table 2. The energy consumption results are shown in Table 2.

[0092] Comparative Example 3

[0093] The extraction separation feedstock used was the same as in Example 3. A conventional subcritical extraction-super critical solvent recovery solvent deasphalting method was used. In the solvent extraction unit, n-pentane with a mole fraction of greater than 99% was used as the extraction solvent, the critical temperature was 196.4°C, and the critical pressure was 3.37 MPa.

[0094] The temperature of the extraction column was 175°C, the pressure was 5.0 MPa, and the solvent to oil ratio was 3.0:1 by mass. The temperature of the supercritical solvent recovery column was 240°C, and the pressure was 4.5 MPa. The overhead stream of the extraction column was subjected to supercritical solvent recovery and then flashed to obtain an extracted oil, and the bottoms stream of the extraction column was flashed to obtain a raffinate oil, which was recycled after solvent recovery. The energy consumption results are shown in Table 2.

[0095] Table 1 Properties of the heavy oil feedstock

[0096]

[0097]

[0098] Table 2, Extraction separation results

[0099]

[0100]

[0101] Table 3

[0102]

[0103]

[0104] Table 4

[0105]

[0106] From the above comparison, it can be seen that the method of the present application uses carbon dioxide under near-critical / supercritical conditions as a cosolvent, adjusts the solubility and selectivity of C4-C5 hydrocarbon solvents, and exerts excellent diffusion capacity, so that fast and efficient extraction separation of different heavy oils is realized under low solvent / oil ratio conditions, and the solvent consumption is reduced and energy consumption is decreased.

Claims

1. A supercritical fluid extraction and separation method of heavy oil, characterized by, The method comprises the following steps: (1) extracting and separating a heavy oil feedstock and an extraction solvent in an extraction column to obtain an extraction phase and a raffinate phase; the extraction solvent is composed of a main solvent and a cosolvent, the main solvent is selected from one or more of C4-C5 hydrocarbons, and the cosolvent is carbon dioxide; (2) recovering the extraction solvent in a supercritical state to obtain supercritical recovered solvent and an extraction oil solution containing a small amount of extraction solvent; (3) recovering the extraction solvent in a first solvent recovery to obtain deasphalted oil, and recovering the raffinate phase in a second solvent recovery to obtain deoiled asphalt.

2. The supercritical fluid extraction method according to claim 1, wherein The heavy oil feedstock has a distillation range of greater than 350°C, a density of 900-1200 kg / m 3 at 20°C, a carbon residue value of 5-30%, and an asphaltene content of 0.5-20 wt% Preferably, the heavy oil feedstock is selected from atmospheric residue and / or vacuum residue.

3. The supercritical fluid extraction method for heavy oil according to claim 1 or 2, characterized by, The weight ratio of the extraction solvent to the heavy oil feedstock is 1.0-2.0:1, preferably 1.5-2.0:1, and the mole fraction of carbon dioxide in the extraction solvent is 2-55%, preferably 5-30%.

4. The supercritical fluid extraction method for heavy oil according to claim 1 or 2, characterized by, The extraction separation conditions include a pressure of 4.5-10 MPa and an extraction temperature of (Tc-50)-Tc ℃, where Tc is the virtual critical temperature of the extraction solvent, which is the sum of the critical temperature of each component in the extraction solvent and the mole fraction of each component. Preferably, the extraction separation conditions include a pressure of 5.0-7.5 MPa and a temperature of (Tc-40)-(Tc-5) ℃.

5. The supercritical fluid extraction method according to claim 4, wherein The supercritical solvent recovery conditions in step (2) include a pressure of 4.5-8 MPa and a temperature higher than the virtual critical temperature Tc of the extraction solvent. Preferably, the supercritical solvent recovery conditions include a pressure of (Pc-7.5) MPa and a temperature of (Tc+20)-(Tc+60) ℃, where Pc is the virtual critical pressure of the extraction solvent.

6. The supercritical fluid extraction method for heavy oil according to claim 1 or 2, characterized by, The first solvent recovery and the second solvent recovery in step (3) each independently include a temperature of (Tc+50)-(Tc+100) ℃ and a pressure of 0.2-1 MPa. Preferably, the temperature is (Tc+60)-(Tc+80) ℃ and the pressure is 0.5-0.8 MPa.

7. The supercritical fluid extraction method according to claim 1, wherein The supercritical recovered solvent obtained in step (2) is directly returned to the extraction column for recycling after heat exchange.

8. The supercritical fluid extraction process according to any one of claims 1 to 6, wherein The separation method further comprises mixing and cooling the extraction solvent obtained from the first solvent recovery and the extraction solvent obtained from the second solvent recovery to separate them into liquid-phase main solvent and gaseous-phase carbon dioxide, and mixing the liquid-phase carbon dioxide obtained by pressurizing and cooling the gaseous-phase carbon dioxide with the liquid-phase main solvent to return them to the extraction column as the extraction solvent for recycling.

9. A heavy oil extraction separation apparatus characterized by, The separation device comprises: an extraction column for extracting and separating a heavy oil and an extraction solvent to obtain an extraction phase and a raffinate phase, the extraction column being provided with a heavy oil feedstock inlet at the upper part, an extraction solvent inlet at the lower part, a top outlet, and a bottom outlet; a solvent recovery column for recovering the extraction solvent in the extraction phase under supercritical conditions to obtain extraction solvent and an extraction oil solution, the solvent recovery column being provided with an inlet, a top outlet, and a bottom outlet, the top outlet of the extraction column being connected to the solvent recovery column, and the top outlet of the recovery column being connected to the lower extraction solvent inlet of the extraction column; a first solvent recovery column for further recovering the extraction solvent in the extraction oil solution to obtain extraction oil and extraction solvent; the bottom of the solvent recovery column is connected to the feed inlet of the first solvent recovery column; a second solvent recovery column for recovering the extraction solvent in the raffinate phase to obtain raffinate oil and extraction solvent; the bottom of the extraction column is connected to the second solvent recovery column; a carbon dioxide mixer for mixing liquid carbon dioxide and main solvent to obtain extraction solvent; the mixer comprises a static mixer, a carbon dioxide pipeline connected to the first inlet of the static mixer through a pressurized pump, a main solvent pipeline connected to the second inlet of the static mixer through a solvent pump, and the outlet of the static mixer is connected to the lower inlet of the extraction column.

10. The apparatus according to claim 9, wherein The separation device further comprises: a gas-liquid separation column for separating gaseous carbon dioxide; the top of the first solvent recovery column and the top of the second solvent recovery column are respectively connected to the gas-liquid separation column; a carbon dioxide liquefaction device for pressurized liquefaction of gaseous carbon dioxide to obtain liquid carbon dioxide; the gaseous phase outlet of the gas-liquid separation column is connected to the carbon dioxide liquefaction device, and the outlet of the carbon dioxide liquefaction device and the liquid phase outlet of the gas-liquid separation column are respectively connected to the static mixer.

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