A method for solvent assisted heavy oil upgrading and viscosity reduction

Abstract

The application provides a method for modifying and reducing viscosity of heavy oil by solvent intervention, comprising the following steps: (1) cutting heavy oil to obtain light oil fraction and heavy oil fraction; (2) mixing the heavy oil fraction with a solvent, and performing a first step cracking reaction under a supercritical environment of the solvent to obtain an intermediate product, and contacting the intermediate product with a hydrogen donor to occur a second step cracking reaction to obtain a reaction product; and (3) separating the reaction product to obtain recovered solvent and cracking product. The heavy oil modification and viscosity reduction process provided in the application can ensure the stability of modified oil while improving the depth of viscosity reduction cracking, and has the advantages of simple process flow, low production cost and suitability for industrial popularization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy oil modification and viscosity reduction, and particularly relates to a method for heavy oil modification and viscosity reduction with solvent intervention. BACKGROUND

[0002] Visbreaking is a mature thermal processing technology without coke formation, which is generally used for treating heavy oil with high viscosity, and the main purpose is to improve the flowability of heavy oil, improve the pour point and viscosity, and the oil treated by visbreaking can provide raw materials for catalytic cracking or coking process, and can also be used for producing fuel oil meeting certain specification requirements.

[0003] The current visbreaking process generally has the problem that the depth of viscosity reduction and the stability of modified oil are difficult to be considered. In addition, the cracking products obtained after high-temperature cracking of heavy oil often need to be further subjected to hydrogenation treatment, which is limited in industrial application due to the influence of high cost of hydrogen source and hydrogenation process.

[0004] Therefore, it is urgent to provide a heavy oil modification and viscosity reduction process which can improve the depth of viscosity reduction and ensure the stability of oil after visbreaking. SUMMARY

[0005] The purpose of the present application is to overcome the problem that the depth of viscosity reduction and the stability of oil are difficult to be considered in the prior art, and to provide a heavy oil modification and viscosity reduction process.

[0006] To achieve the above-mentioned purpose, the present application provides a method for heavy oil modification and viscosity reduction with solvent intervention, comprising the following steps:

[0007] (1) cutting heavy oil to obtain light oil fraction and heavy oil fraction;

[0008] (2) mixing the heavy oil fraction with a solvent, and performing a first step cracking reaction under a supercritical environment of the solvent to obtain an intermediate product, and contacting the intermediate product with a hydrogen donor to occur a second step cracking reaction to obtain a reaction product;

[0009] (3) separating the reaction product to obtain recovered solvent and cracking product.

[0010] In the method for heavy oil modification and viscosity reduction with solvent intervention, the amount of heavy oil fraction, solvent and hydrogen donor can be determined by the person skilled in the art according to conventional technical knowledge, which is not specifically limited herein. In the present application, the mass ratio of the heavy oil fraction to the solvent is 1:0.5-5, preferably 1:1-3; and the hydrogen donor accounts for 0.1-10% of the mass of the heavy oil fraction, preferably 0.3-2%.

[0011] In the method for modifying and reducing viscosity of heavy oil by solvent intervention, in step (2), the solvent is divided into A part solvent and B part solvent, the A part solvent is mixed with the heavy oil fraction and preheated to a temperature of ≤350℃, and then mixed with the B part solvent which is preheated to a temperature 5-40℃ higher than the temperature of the cracking reaction; the A part solvent accounts for 5%-50% of the mass of the heavy oil fraction, preferably 10%-30%.

[0012] In the method for modifying and reducing viscosity of heavy oil by solvent intervention, the reaction conditions of the cracking reaction can be determined by the person skilled in the art according to conventional technical knowledge, which is not specifically limited herein. In the present application, the reaction conditions of the first step cracking reaction and the second step cracking reaction are the same, or are appropriately adjusted according to the actual reaction condition in the second step reaction. In the present application, the reaction conditions of the first step cracking reaction include: the reaction temperature is 320-430℃, preferably 380-420℃; the reaction pressure is 6-15MPa, preferably 8-12MPa; the reaction time is 1-45min, preferably 1-20min; and the reaction conditions of the second step cracking reaction include: the reaction temperature is 320-430℃, preferably 380-420℃; the reaction pressure is 6-15MPa, preferably 8-12MPa; and the reaction time is 1-30min, preferably 1-15min. In the present application, the reaction temperature of the second step cracking reaction is preferably the same as that of the first step cracking reaction. In the present application, the first step cracking reaction and the second step cracking reaction can be carried out in one reactor, or can be carried out in two reactors. When the first step cracking reaction and the second step cracking reaction are carried out in one reactor, the reactor can be divided into two reaction zones by controlling the feeding position of the hydrogen donor in the second step cracking reaction.

[0013] In the present application, the solvent is divided into A part and B part, the A part is mixed with the heavy oil fraction and fed into the reaction system, and the A part solvent plays a dilution role, so that the viscosity of the mixed system is reduced, the flowability in the pipeline and heating furnace tube is good, and the phenomenon of slow coking caused by wall sticking of high viscosity heavy oil and long time operation of the heating furnace tube is avoided. This technical solution is especially suitable for heavy naphthenic base heavy oil.

[0014] The hydrogen donor can saturate the condensed ring aromatic carbon free radicals by providing active hydrogen, so that the condensation reaction in the heavy oil thermal cracking process is partially inhibited. It should be noted that the presence of the hydrogen donor in the cracking system not only saturates the aromatic carbon free radicals, but also saturates the alkyl carbon free radicals that initiate the thermal cracking reaction network, resulting in a decrease in the free radical concentration. This greatly prolongs the initiation time of thermal cracking and reduces the thermal cracking reaction efficiency. Therefore, the traditional method of directly adding a hydrogen donor component to the cracking feedstock simultaneously with thermal cracking generally causes the initiation and chain propagation efficiency of the heavy oil thermal cracking network to lag. The present application adds the hydrogen donor in the later stage of the reaction, which does not affect the free radical concentration of the hydrocarbon produced in the early stage of the cracking reaction, and the added hydrogen donor can be fully used to saturate the condensed ring aromatic carbon free radicals that have a tendency to coke, without causing unnecessary waste.

[0015] The solvent intervention heavy oil modification and viscosity reduction method provided by the present application, the hydrogen donor also includes a supplemental solvent, the supplemental solvent accounts for 5%-25% of the mass of the heavy oil fraction, preferably 10%-20%. The addition of the supplemental solvent in the process can play a role in strengthening mass transfer, improve reaction efficiency and shorten the reaction time of the second step reaction under the premise of ensuring the viscosity reduction effect and the stability of the product. The supplemental solvent in the present application is the same as or different from the solvent used in the first step cracking reaction, and in the present application, the two are preferably the same for the convenience of operation.

[0016] The solvent intervention heavy oil modification and viscosity reduction method provided by the present application, the separation in step (3) is a commonly used separation method in the art, which can be flash evaporation, which is carried out in a flash evaporator. The operation of the flash evaporator is not specially limited in the present application, and can be carried out according to the conventional operation in the art. The recovered solvent can be returned to step (2) for recycling. When the solvent in the first step cracking reaction is different from the supplemental solvent in the second step cracking reaction, the recovered solvent can be separated and then returned to the first step cracking reaction and the second step cracking reaction for recycling, respectively.

[0017] The solvent intervention heavy oil modification and viscosity reduction method provided by the present application further comprises step (4) of mixing the light oil fraction and the cracking product to obtain a modified oil. Mixing the light oil fraction and the cracking product or the pretreated product can further reduce the viscosity of the modified oil and improve the stability of the modified oil.

[0018] The solvent intervention heavy oil modification and viscosity reduction method provided by the present application, before mixing the light oil fraction and the cracking product, the cracking product is pretreated to obtain a pretreated product; the light oil fraction and the pretreated product are mixed to obtain a modified oil;

[0019] The pre-treatment includes: first, the cracking product is subjected to rectification to obtain light oil and heavy oil; the cutting temperature of the light oil and the heavy oil is 200-280 DEG C; then, the light oil is subjected to sedimentation to remove diene; and then, the light oil after the sedimentation and the heavy oil are mixed to obtain a pre-treatment product.

[0020] The solvent intervention heavy oil modification viscosity reduction method of the application, the sedimentation is carried out at 10-30 DEG C, and the sedimentation time is 4-10 days, preferably 5-7 days. After the sedimentation, the oil product is filtered at room temperature, and the filtering mode is not specially limited in the application.

[0021] The solvent intervention heavy oil modification viscosity reduction method of the application, the stability of the modified oil is 1-2, and the 50 DEG C kinematic viscosity is ≤300 mm 2 / s, preferably 50-200 mm 2 / s.

[0022] In the prior art, the heavy oil fraction and the solvent are respectively preheated by independent heating furnaces, the two separate streams are from the heating furnace to the merging pipeline, and the pipeline between the merging pipeline and the cracking reactor is long, and heat dissipation is serious. In order to make up for it, the actual preheating temperature of the solvent is much higher than the theoretical temperature calculated by specific heat capacity.

[0023] The solvent intervention heavy oil modification viscosity reduction method of the application, the heavy oil fraction, the solvent and the hydrogen donor are preheated by a three-tube preheating furnace before the first step of the cracking reaction, the preheating furnace is gradiently heated from top to bottom, and the materials located at different outlet positions reach the corresponding temperature by setting the heating furnace wall to a suitable temperature. The heavy oil fraction is preheated in the upper furnace tube of the preheating furnace and then discharged from the heating furnace, all the solvent is preheated in the lower furnace tube of the preheating furnace and then discharged from the heating furnace, and the preheated heavy oil fraction and the solvent enter the premixing pipeline; or the A part of the solvent and the heavy oil fraction are preheated in the upper furnace tube of the preheating furnace and then discharged from the heating furnace, the B part of the solvent is preheated in the lower furnace tube of the preheating furnace and then discharged from the heating furnace, and the preheated A part of the solvent and the heavy oil fraction mixture enter the premixing pipeline, and the premixing pipeline inlet is close to the uppermost furnace tube outlet. The premixing pipeline outlet and the furnace tube of the preheated hydrogen donor are directly connected to the cracking device.

[0024] 350℃ is considered to be the temperature at which free radicals begin to initiate in heavy oil, and long-term heating at a temperature above 350℃ will slowly coke, and long-term use at a temperature below 350℃ reduces the risk of coking of the furnace tube. In the present application, the heavy oil fraction is preheated at the uppermost part of the preheating furnace, and the preheating temperature is not higher than 350℃, and the preheating furnace tube is discharged; the preheating temperature of the solvent is increased to 350℃, and the preheating furnace is further heated to the target temperature, and the furnace tube is returned to the furnace from the preheating furnace at the position near the heavy oil fraction preheating furnace. The material containing the hydrogen donor is heated to the reaction temperature and discharged from the heating furnace. Compared with the prior art, the preheating temperature of the solvent is lower, which has a significant energy saving effect, and one heating furnace is saved, and the overall process layout is more simple.

[0025] The solvent intervention heavy oil modification and viscosity reduction method described in the present application, the purpose of the premixing pipeline is to enhance the mass transfer of the solvent and the heavy oil fraction, and the specific structure form is not limited, the premixing pipeline in the present application can be one or several of a static mixer, a venturi tube and a diameter expansion pipeline, when a static mixer is selected, the material can enter the static mixer in a Y-shaped pipeline, and after instant collision, it is further mixed uniformly in the static mixer, the static mixer can have a cross-flow type rotating screw inner member, or can adopt an internal packing way to increase the residence time; when a venturi tube is selected, the venturi tube can be a one-stage or multi-stage venturi tube, all the solvent or the preheated B part of the solvent is directly connected into the venturi tube, and the heavy oil fraction or the preheated A part of the solvent and the heavy oil fraction enters the pipeline from the diameter reduction part of the venturi tube; when a diameter expansion pipeline is selected, the inner diameter of the diameter expansion pipeline is 2-3 times the inner diameter of the furnace tube, the heavy oil fraction or the preheated A part of the solvent and the heavy oil fraction directly enters the diameter expansion pipeline, and all the solvent or the preheated B part of the solvent enters the diameter expansion pipeline from the side 1 / 4-3 / 4 position of the diameter expansion pipeline, on the one hand, the material reduces the linear velocity, increases the residence time, and strengthens the mixing, on the other hand, the mixing space is increased, the heavy oil fraction directly flows through the injected supercritical fluid and is instantaneously dispersed and mixed into the solvent, and then is discharged from the mixing pipeline, so that sufficient mass transfer is ensured.

[0026] In the present application, the preheating temperature of the solvent is not particularly specified, and is determined according to the type and amount of the solvent used, and is calculated according to the specific heat capacity and amount of the heavy oil fraction and the solvent, the material containing the heavy oil fraction is preheated from room temperature 20℃ to 320-350℃, the reaction temperature is 390-430℃, and the solvent needs to be preheated to a temperature of 390-500℃ when the solvent to oil ratio is 1:1-3:1. The material containing the hydrogen donor is directly set to the reaction temperature.

[0027] In the present application, the measures for making the mixture flow reach the reaction temperature mainly depend on the temperature reached after mixing the heavy oil fraction and the solvent and the influence of heat dissipation. In order to reduce the heat dissipation of the pipeline, two points need to be paid attention to. One is that the distance between the preheating furnace outlet material and the pre-mixing pipeline and the viscosity reduction reactor inlet should be as short as possible. The other is that the pipeline heat tracing insulation measures must be good, and the temperature is slightly higher than the outlet temperature of the pre-mixing reactor, so that the temperature at the inlet of the cracking reactor is just the reaction temperature. The setting temperature of the cracking reactor is not particularly mentioned, which essentially plays a heat preservation role. According to the wall temperature setting at the inlet of the reactor, the mixture flow is kept at the reaction temperature condition within the residence time in the cracking reactor.

[0028] In the method for modifying and reducing the viscosity of heavy oil by using a solvent according to the present application, the cutting temperature of the light oil fraction and the heavy oil fraction can be selected by the person skilled in the art according to the specific type of the actual heavy oil, which is not particularly limited herein. In the present application, the cutting temperature of the light oil fraction and the heavy oil fraction is 200-540 DEG C. The cutting of the heavy oil is carried out in a distillation column. In the present application, the operation of the distillation column is not particularly limited, which can be carried out according to the conventional operation in the art.

[0029] In the method for modifying and reducing the viscosity of heavy oil by using a solvent according to the present application, the type of the heavy oil is not particularly limited herein. In the present application, the heavy oil is selected from one or more of paraffin-based crude oil, intermediate-based crude oil and naphthenic-based crude oil having a condensation point of 30 DEG C or higher. When the heavy oil is paraffin-based crude oil, the cutting temperature is 350-540 DEG C, preferably 420-520 DEG C. When the heavy oil is intermediate-based crude oil, the cutting temperature is 280-540 DEG C, preferably 300-500 DEG C. When the heavy oil is naphthenic-based crude oil, the cutting temperature is 200-500 DEG C, preferably 200-450 DEG C.

[0030] In the method for modifying and reducing the viscosity of heavy oil by using a solvent according to the present application, the type of the solvent and the hydrogen donor is not particularly limited herein, which is a commonly used substance in the art. Preferably, the solvent in the present application is selected from one or more of monocyclic naphthenes and / or monocyclic aromatics. The monocyclic naphthene is selected from cyclopentane and / or cyclohexane. The monocyclic aromatic is selected from benzene, toluene and xylene. The hydrogen donor is a naphthenic aromatic hydrocarbon, which is selected from one or more of tetrahydro naphthalene, decaline and dihydro anthracene.

[0031] The present application has the following beneficial effects:

[0032] The heavy oil modification and viscosity reduction process provided in the present application can ensure the improvement of the viscosity reduction depth and the stability of the modified oil, has a simple process flow and low production cost, and is suitable for industrial promotion.

[0033] The hydrogen donor is added in the later reaction stage, which does not affect the free radical concentration of hydrocarbon produced in the early cracking reaction, and the added hydrogen donor can be fully used to saturate the condensed coke-prone free radicals of the condensed ring aromatic carbon, and does not cause unnecessary waste.

[0034] The present application uses a preheating furnace to preheat heavy oil fractions, solvents and hydrogen donors, and cooperates with a premixing pipeline to enhance mass transfer, so as to reduce the number of preheaters and reduce heat dissipation. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is the stability test result of the modified oil prepared in Example 1;

[0036] Figure 2 is the stability test result of the modified oil prepared in Example 2;

[0037] Figure 3 is the stability test result of the modified oil prepared in Example 3;

[0038] Figure 4 is the stability test result of the modified oil prepared in Example 4;

[0039] Figure 5 is the stability test result of the modified oil prepared in Comparative Example 1;

[0040] Figure 6 is the stability test result of the modified oil prepared in Comparative Example 2. DETAILED DESCRIPTION

[0041] The present application will be described in detail below by examples. It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content of the present application.

[0042] Example 1 (naphthenic base crude oil, two-stage reaction, containing hydrogen donor)

[0043] (1) Introduce Canadian oil sand pitch (naphthenic base oil) into a distillation column, cut, and the cutting temperature is 420℃, to obtain a light oil fraction with a boiling point <420℃ and a heavy oil fraction with a boiling point ≥420℃;

[0044] (2) The heavy oil fraction and the A portion of cyclohexane are mixed and preheated to 330°C in the upper furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, and then mixed with the B portion of cyclohexane preheated to 422°C in the lower furnace tube of a one-furnace three-tube preheating furnace at 10 MPa in a static mixer, and introduced into a shell-and-tube cracking reactor from the bottom of the shell-and-tube cracking reactor; the heavy oil fraction, the A portion of cyclohexane, and the B portion of cyclohexane undergo a first step reaction in the shell-and-tube cracking reactor to obtain an intermediate product;

[0045] wherein the mass ratio of the heavy oil fraction to the cyclohexane (the sum of the masses of the A portion of cyclohexane and the B portion of cyclohexane) is 1:2, the A portion of cyclohexane accounts for 20% of the mass of the heavy oil fraction, the temperature of the first step reaction is 410°C, the pressure of the first step reaction is 10 MPa, and the time of the first step reaction is 10 min;

[0046] (3) The supplemental cyclohexane and tetrahydronaphthalene are mixed and heated to 410°C in the middle furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, introduced into a shell-and-tube cracking reactor from the upper middle portion of the shell-and-tube cracking reactor, and contacted with the intermediate product to undergo a second step reaction to obtain a reaction product;

[0047] wherein the tetrahydronaphthalene accounts for 0.5% of the mass of the heavy oil fraction, the supplemental cyclohexane accounts for 15% of the mass of the heavy oil fraction, the temperature of the second step reaction is 410°C, the pressure of the second step reaction is 10 MPa, and the time of the second step reaction is 5 min;

[0048] (4) The reaction product is introduced into a flash evaporator to perform flash evaporation to obtain recovered solvent and a cracking product; the cracking product is introduced into a rectifying column to perform rectification, light oil with a boiling point of ≤280°C is collected from the top of the rectifying column, and heavy oil with a boiling point of >280°C is collected from the bottom of the rectifying column; the recovered cyclohexane is returned to steps (2) and (3) for recycling; the light oil is introduced into a settler to perform settling treatment, left to stand at room temperature for 7 days, and then filtered to remove dienes, and mixed with the heavy oil to obtain a pretreated product.

[0049] (5) The light oil fraction and the pretreated product are mixed to obtain a modified oil.

[0050] Example 2 (paraffin-based crude oil, two-stage reaction, containing a hydrogen donor)

[0051] (1) The Chadian crude oil (paraffin-based crude oil with a freezing point higher than 30°C) is introduced into a distillation column to perform cutting at a cutting temperature of 500°C to obtain a light oil fraction with a boiling point of <500°C and a heavy oil fraction with a boiling point of ≥500°C;

[0052] (2) The heavy oil fraction and the A portion of benzene are mixed and preheated to 330°C in the upper furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, and then mixed with the B portion of benzene preheated to 433°C in the lower furnace tube of a one-furnace three-tube preheating furnace at 10 MPa in a Venturi tube, and introduced into a columnar cracking reactor from the bottom thereof; the heavy oil fraction, the A portion of benzene and the B portion of benzene are subjected to a first step reaction in the columnar cracking reactor to obtain an intermediate product;

[0053] wherein the mass ratio of the heavy oil fraction to the benzene (the sum of the masses of the A portion of benzene and the B portion of benzene) is 1:3, the A portion of benzene accounts for 10% of the mass of the heavy oil fraction, the temperature of the first step reaction is 425°C, the pressure of the first step reaction is 10 MPa, and the first step reaction time is 5 min;

[0054] (3) The make-up benzene is mixed with tetrahydronaphthalene and heated to 425°C in the middle furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, and introduced into a columnar cracking reactor from the upper middle portion thereof to contact the intermediate product and undergo a second step reaction to obtain a reaction product;

[0055] wherein the tetrahydronaphthalene accounts for 1.0% of the mass of the heavy oil fraction, the make-up benzene accounts for 10% of the mass of the heavy oil fraction, the temperature of the second step reaction is 425°C, the pressure of the second step reaction is 10 MPa, and the second step reaction time is 5 min;

[0056] (4) The reaction product is introduced into a flash evaporator to perform flash evaporation to obtain a recovered solvent and a cracking product; the recovered solvent is returned to steps (2) and (3) for recycling;

[0057] (5) The cracking product is mixed with a light fraction oil to obtain a modified oil.

[0058] Example 3 (intermediate base crude oil, two-stage reaction, containing hydrogen donor)

[0059] (1) A Russian crude oil (intermediate base crude oil) is introduced into a distillation column to perform cutting at a cutting temperature of 450°C to obtain a light oil fraction having a boiling point < 450°C and a heavy oil fraction having a boiling point > 450°C;

[0060] (2) The heavy oil fraction and the A portion of cyclohexane are mixed and preheated to 330°C in the upper furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, and then mixed with the B portion of cyclohexane preheated to 428°C in the lower furnace tube of a one-furnace three-tube preheating furnace at 10 MPa in a diameter-expanded pipe, and introduced into a columnar cracking reactor from the bottom thereof; the heavy oil fraction, the A portion of cyclohexane and the B portion of cyclohexane are subjected to a first step reaction in the columnar cracking reactor to obtain an intermediate product;

[0061] wherein the mass ratio of the heavy oil fraction and the cyclohexane (the sum of the masses of the A-part cyclohexane and the B-part cyclohexane) is 1:3, the A-part cyclohexane accounts for 20% of the mass of the heavy oil fraction, the temperature of the first step reaction is 415°C, the pressure of the first step reaction is 10 MPa, and the time of the first step reaction is 8 min;

[0062] (3) the supplemental cyclohexane is mixed with decalin, heated to 415°C in the middle furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, introduced into the array tube cracking reactor from the middle upper part of the array tube cracking reactor, contacted with the intermediate product, and a second step reaction occurs to obtain a reaction product;

[0063] wherein the decalin accounts for 0.5% of the mass of the heavy oil fraction, the supplemental cyclohexane accounts for 15% of the mass of the heavy oil fraction, the temperature of the second step reaction is 415°C, the pressure of the second step reaction is 10 MPa, and the time of the second step reaction is 4 min;

[0064] (4) the above reaction product is introduced into a flash evaporator to perform flash evaporation to obtain recovered solvent and a cracking product; the obtained cracking product is introduced into a rectifying column to perform rectification, light oil with a boiling point of ≤200°C is collected from the top of the rectifying column, heavy oil with a boiling point of >200°C is collected from the bottom of the rectifying column, the recovered cyclohexane is returned to step (2) and step (3) for recycling, and the above light oil is introduced into a settler to perform settling treatment, left to stand at room temperature for 7 days, and then filtered to obtain a pretreated product after removal of diene.

[0065] (5) the above light oil fraction and the pretreated product are mixed to obtain a modified oil.

[0066] Example 4 (paraffin-based crude oil, two-stage reaction, hydrogen donor contained, hydrogen donor not dispersed with solvent)

[0067] (1) the Chadian crude oil (paraffin-based crude oil with a condensation point higher than 30°C) is introduced into a distillation column to perform cutting at a cutting temperature of 500°C to obtain a light oil fraction with a boiling point of <500°C and a heavy oil fraction with a boiling point of ≥500°C;

[0068] (2) the above heavy oil fraction and the A-part cyclohexane are mixed, preheated to 330°C in the upper furnace tube of a one-furnace three-tube preheating furnace at 10 MPa, and then mixed with the B-part cyclohexane preheated to 433°C in the lower furnace tube of a one-furnace three-tube preheating furnace at 10 MPa in a Venturi tube, introduced into the array tube cracking reactor from the bottom of the array tube cracking reactor; the heavy oil fraction, the A-part cyclohexane, and the B-part cyclohexane perform a first step reaction in the array tube cracking reactor to obtain an intermediate product;

[0069] wherein the mass ratio of the heavy oil fraction and the cyclohexane (the sum of the masses of the A-part cyclohexane and the B-part cyclohexane) is 1:2, the A-part cyclohexane accounts for 20% of the mass of the heavy oil fraction, the temperature of the first step reaction is 425°C, the pressure of the first step reaction is 10 MPa, and the time of the first step reaction is 5 min;

[0070] (3) heating tetralin to 425°C in the middle tube of a three-tube preheating furnace at 10 MPa, introducing the tetralin into the middle upper part of the column-tube cracking reactor to contact with the intermediate product to generate a second step reaction, and obtaining a reaction product;

[0071] wherein the tetralin accounts for 1.0% of the mass of the heavy oil fraction, the temperature of the second step reaction is 425°C, the pressure of the second step reaction is 10 MPa, and the time of the second step reaction is 5 min;

[0072] (4) introducing the reaction product into a flash evaporator to perform flash evaporation, obtaining a recycled solvent and a cracking product; and returning the recycled solvent to step (2) for recycling;

[0073] (5) mixing the cracking product and the light fraction oil to obtain a modified oil.

[0074] Comparative Example 1 (naphthenic base crude oil, one-step reaction, no hydrogen donor)

[0075] (1) introducing Canadian oil sand bitumen into a distillation column to perform cutting, with a cutting temperature of 420°C, to obtain a light oil fraction with a boiling point < 420°C and a heavy oil fraction with a boiling point ≥ 420°C;

[0076] (2) heating the heavy oil fraction to 330°C, heating cyclohexane to 415°C at 10 MPa, and introducing the heated heavy oil fraction and the cyclohexane into the column-tube cracking reactor from the bottom of the column-tube cracking reactor to generate a one-step reaction, and obtaining a reaction product;

[0077] wherein the mass ratio of the heavy oil fraction and the cyclohexane is 1:2.2, the temperature of the one-step reaction is 410°C, the pressure of the one-step reaction is 10 MPa, and the time of the one-step reaction is 15 min;

[0078] (3) introducing the reaction product into a flash evaporator to perform flash evaporation, obtaining a recycled solvent and a cracking product; introducing the obtained cracking product into a rectification column to perform rectification, collecting light oil with a boiling point ≤ 280°C from the top of the rectification column, and collecting heavy oil with a boiling point > 280°C from the bottom of the rectification column; returning the recycled cyclohexane to step (2) for recycling; introducing the light oil into a settler to perform settling treatment, standing for 7 days at room temperature, and then performing filtration to obtain a pretreated product after removing diene hydrocarbons and mixing with the heavy oil;

[0079] (4) mixing the light oil fraction and the pretreated product to obtain a modified oil.

[0080] Comparative Example 2 (Naphthenic base crude oil, one-step reaction, hydrogen donor contained, no supercritical solvent intervention)

[0081] (1) The Canadian oil sand bitumen was introduced into a distillation column, and cutting was performed at a cutting temperature of 420°C to obtain a light oil fraction having a boiling point < 420°C and a heavy oil fraction having a boiling point > 420°C;

[0082] (2) The heavy oil fraction was heated to 330°C, tetralin was heated to 330°C, and cyclohexane was heated to 415°C under 0.6 MPa; the heated heavy oil fraction, cyclohexane, and tetralin were introduced into a tubular cracking reactor from the bottom of the tubular cracking reactor to perform one-step reaction to obtain a reaction product;

[0083] The mass ratio of the heavy oil fraction and cyclohexane was 1:2.2, tetralin accounted for 1.5% of the mass of the heavy oil fraction, the one-step reaction temperature was 410°C, the one-step reaction pressure was 0.6 MPa, and the one-step reaction time was 15 min;

[0084] (3) The reaction product was introduced into a flash evaporator to perform flash evaporation to obtain recovered solvent and a cracking product; the obtained cracking product was introduced into a rectifying column to perform rectification, light oil having a boiling point < 280°C was collected from the top of the rectifying column, and heavy oil having a boiling point > 280°C was collected from the bottom of the rectifying column; the recovered cyclohexane was returned to step (2) for recycling; the light oil was introduced into a settler to perform settling treatment, and was left to stand at room temperature for 7 days, followed by filtration, mixing with the heavy oil after removal of diene, and obtaining a pretreated product;

[0085] (4) The light oil fraction and the pretreated product were mixed to obtain a modified oil.

[0086] Test Example 1

[0087] The heavy oil fraction, the cracking product, and the modified oil obtained in Examples 1-5 and Comparative Examples 1-2 were subjected to kinematic viscosity testing according to GB / T 269, and the test results are shown in Table 1 and Table 2:

[0088] Table 1

[0089]

[0090]

[0091] Note: In Table 1, — indicates that the viscosity of the sample to be tested was too high to be measured at the test temperature.

[0092] Table 2

[0093] 50 °C viscosity (mm 2 / s) Example 1 52.8 Example 2 14.2 Example 3 87.2 Example 4 14.6 Comparative Example 1 172.6 Comparative Example 2 201.5

[0094] As shown in Table 1, the method provided in the present application can reduce the viscosity of the cracking product at 50℃ to below 200 mPa.s, which can meet the requirements of heavy oil transportation. As shown in Table 2, mixing the cracking product with a light oil fraction can further reduce the viscosity of the oil product.

[0095] Test Example 2

[0096] The upgraded oils obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to stability tests according to the spot test experiment specified in ASTM D4740-04(2014), and the stability rating standards were as follows.

[0097] Level 1: uniform spots, no ring inside;

[0098] Level 2: fine and blurred rings inside the spots;

[0099] Level 3: obvious thin rings inside the spots, slightly darker than the original color;

[0100] Level 4: thicker rings than the level 3, also slightly darker than the original color;

[0101] Level 5: the rings inside the spots are almost solid or close to solid, the center of the ring is much darker than the background color.

[0102] wherein, Figures 1-6 The stability test results of the upgraded oils prepared in Examples 1-4 and Comparative Examples 1-2 are shown in Table 3, and by analyzing Figures 1-6 it can be known that the spots in Examples 1-3 are uniform, and there is no ring inside, and the stability is level 1; the spots in Example 4 are uniform, and there is fine and blurred color difference inside, and the stability is between level 1 and level 2. In Comparative Example 1, there are fine and blurred rings, and the center part is darker, and the stability is level 2. In Comparative Example 2, there are thicker rings than the level 3, and also slightly darker than the original color, and the stability is level 3.

[0103] According to the results of the viscosity test and the stability test, under conditions higher than the supercritical state of the solvent, introducing the hydrogen donor into the heavy oil fraction cracking reaction can meet the requirements of viscosity reduction and stability of the upgraded oil, and is an upgrading technology that takes into account the cracking depth and product stability.

[0104] Of course, the present application can also have other various embodiments, and those skilled in the art can make various corresponding changes and modifications to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for solvent-based modification and viscosity reduction of heavy oil, characterized in that, Includes the following steps: (1) The heavy oil is cut to obtain light oil fraction and heavy oil fraction; (2) The heavy oil fraction is mixed with a solvent and subjected to a first-step cracking reaction in the supercritical environment of the solvent to obtain an intermediate product. The intermediate product is then contacted with a hydrogen donor to undergo a second-step cracking reaction to obtain the reaction product. The reaction conditions for the first step of the cracking reaction include: a reaction temperature of 320-430℃ and a reaction pressure of 6-15MPa; (3) The reaction products are separated to obtain the recovered solvent and cracking products; Before the first step of the cracking reaction, the heavy oil fraction, solvent, and hydrogen donor are preheated in a three-tube preheating furnace. The preheating furnace is heated in a gradient from top to bottom. The heavy oil fraction is preheated in the upper furnace tube and exits the preheating furnace, while all the solvent is preheated in the lower furnace tube and exits the preheating furnace. The solvent and the preheated heavy oil fraction then enter a premixing pipe. Alternatively, in step (2), the solvent is divided into a solvent A and a solvent B. The solvent A and the heavy oil fraction are preheated in the upper furnace tube and exit the preheating furnace, while the solvent B is preheated in the lower furnace tube and exits the preheating furnace. The solvent and the preheated solvent A and the heavy oil fraction then enter a premixing pipe. The inlet of the premixing pipe is close to the outlet of the uppermost furnace tube. The solvent is a monocyclic cycloalkanes and / or monocyclic aromatics. The hydrogen donor is a cycloalkyl aromatic.

2. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, In step (2), the mass ratio of the heavy oil fraction to the solvent is 1:0.5-5; the hydrogen donor accounts for 0.1-10% of the mass of the heavy oil fraction.

3. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, In step (2), the mass ratio of the heavy oil fraction to the solvent is 1:1-3; the hydrogen donor accounts for 0.3-2% of the mass of the heavy oil fraction.

4. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The solvent in part A is mixed with the heavy oil fraction and preheated to a temperature ≤350°C, and then mixed with the solvent in part B, which is preheated separately to a temperature 5-40°C higher than the temperature of the cracking reaction; the solvent in part A accounts for 5%-50% of the mass of the heavy oil fraction.

5. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The solvent in part A accounts for 10%-30% of the mass of the heavy oil fraction.

6. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The reaction time for the first step of the cracking reaction is 1-45 min; the reaction conditions for the second step of the cracking reaction include: a reaction temperature of 320-430℃; a reaction pressure of 6-15 MPa; and a reaction time of 1-30 min.

7. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The reaction conditions for the first step of the cracking reaction include: a reaction temperature of 380-420℃; a reaction pressure of 8-12MPa; and a reaction time of 1-20min. The reaction conditions for the second step of the cracking reaction include: a reaction temperature of 380-420℃; a reaction pressure of 8-12MPa; and a reaction time of 1-15min.

8. The method for solvent-assisted heavy oil modification and viscosity reduction according to claim 1, characterized in that, The hydrogen supply agent also includes a supplemental solvent, which accounts for 5%-25% of the mass of the heavy oil fraction.

9. The method for solvent-assisted heavy oil modification and viscosity reduction according to claim 8, characterized in that, The supplemental solvent accounts for 10%-20% of the mass of the heavy oil fraction.

10. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, It also includes step (4), in which the light oil fraction and cracking products are mixed to obtain modified oil.

11. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 10, characterized in that, Before mixing the light oil fraction and the cracking products, the cracking products are pretreated to obtain pretreated products. The light oil fraction and the pretreatment product are mixed to obtain the modified oil; The pretreatment includes: first, distilling the cracking products to obtain light oil and heavy oil; wherein the cutting temperature of the light oil and heavy oil is 200-280℃; then, settling the light oil to remove dienes; and then mixing the settled light oil and heavy oil to obtain the pretreated product.

12. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 10, characterized in that, The modified oil has a kinematic viscosity at 50°C ≤300 mmHg. 2 / s.

13. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 10, characterized in that, The modified oil has a kinematic viscosity of 50-200 mmHg at 50°C. 2 / s.

14. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 11, characterized in that, The settling was carried out at 10~30℃ and the settling time was 4~10 days.

15. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 11, characterized in that, The settling process is carried out at 10-30℃ and takes 5-7 days.

16. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The premixed pipeline is one or more of the following: a static mixer, a venturi tube, and an expanded diameter pipeline.

17. The method for solvent-assisted heavy oil modification and viscosity reduction according to claim 1, characterized in that, The cutting temperature for the light oil fraction and the heavy oil fraction is 200-540℃.

18. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The heavy oil is selected from one or more of paraffinic crude oil, intermediate crude oil, and naphthenic crude oil with a pour point above 30°C.

19. The method for solvent-assisted heavy oil upgrading and viscosity reduction according to claim 1, characterized in that, The monocyclic cycloalkane is selected from cyclopentane and / or cyclohexane, and the monocyclic aromatic hydrocarbon is selected from one or more of benzene, toluene, and xylene; the cycloalkyl aromatic hydrocarbon is one or more of tetrahydronaphthalene, decahydronaphthalene, and dihydroanthracene.

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