A process for the mild thermal upgrading of heavy oil and its application

Abstract

The application discloses a treatment process and application of heavy oil slight thermal modification, and specific operation steps are as follows: introducing a certain proportion of small molecule alkane, naphthene, aromatic hydrocarbon, light distillate oil with a distillation range of <300 DEG C or a solvent composed of two types / three types / four types of the above-mentioned solvents into a reaction device containing raw heavy oil to be treated, and performing in-situ hydrogenation thermal treatment on the heavy oil under the action of water, CO gas and a catalyst, then optimizing and screening the solvent type, solvent proportion, in-situ hydrogenation temperature, in-situ hydrogenation time, catalyst type and addition amount, CO pressure and water / CO molar ratio in the in-situ hydrogenation thermal treatment process, and finally, the in-situ hydrogenation product of the heavy oil can be directly used as modified oil, or the in-situ hydrogenation product of the heavy oil can be subjected to slight thermal cracking to obtain modified oil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy oil processing, in particular to a new mild thermal modification treatment process for heavy oil and application. BACKGROUND

[0002] With the decrease of conventional crude oil reserves year by year, heavy oil resources which account for 70% of the world's oil reserves have gradually become the main oil energy. The demand for energy in today's society is increasing, and the reasonable exploitation and efficient use of heavy oil are particularly important. Compared with conventional crude oil, heavy oil has the characteristics of high viscosity, poor flowability, high density, high asphaltene content, high sulfur and nitrogen heteroatom content, etc., which brings great challenges to its exploitation, transportation and processing. Therefore, the development of heavy oil viscosity reduction and lightening technology has become the key to the rational development of heavy oil.

[0003] At present, the heavy oil viscosity reduction technology mainly includes physical method and chemical method. The dilution viscosity reduction is a commonly used physical method to reduce the viscosity of heavy oil, which relies on the addition of a certain amount of diluent to the heavy oil to reduce the overall oil viscosity. However, this method is limited by the source and price of diluent, and the cost is high, and the quality of the produced oil is not high, which is not suitable for large-scale use. The thermal cracking modification method is a commonly used chemical method to reduce the viscosity of heavy oil, which has the characteristics of strong adaptability to raw materials. However, heavy oil is prone to condensation and coking during thermal cracking, which hinders the cracking depth, reduces the yield of light oil, and affects the stability of the product. The hydrogenation thermal cracking technology can inhibit coking to some extent, and improve the heavy oil cracking conversion rate and the yield of light oil. However, the solubility of hydrogen in heavy oil and the activation of hydrogen during hydrogenation are important factors limiting its development. In addition, the preparation process of external hydrogen is complex and the cost is high, which reduces the economic benefit of heavy oil thermal cracking modification. SUMMARY

[0004] In order to solve the problems existing in the prior art, the present application discloses a new mild thermal modification treatment process for heavy oil and application. The present application can not only greatly reduce the viscosity of heavy oil, but also maximize the cracking of heavy oil molecules into small molecules, significantly improve the yield and quality of light products, reduce the content of sulfur, nitrogen and other heteroatoms and olefins, and fundamentally inhibit the coking of the reaction device. In addition, the present application does not use external hydrogen, has the characteristics of mild operating conditions, low cost and wide application range.

[0005] In order to achieve the above purpose, the specific scheme of the present application is as follows:

[0006] A new mild thermal modification treatment process for heavy oil and application, comprising the following steps:

[0007] (1) Pump a certain proportion of small molecule alkanes, cycloalkanes, arenes, light distillate oil with distillation range <300℃ or solvent composed of two / three / four kinds of them into the reaction device containing heavy oil raw material, and carry out in-situ hydrotreating under the action of water, CO gas and catalyst, and optimize the solvent type, solvent ratio, in-situ hydrotreating temperature, in-situ hydrotreating time, catalyst type and addition amount, CO pressure, water / CO molar ratio in the in-situ hydrotreating process;

[0008] (2) Pump the in-situ hydrotreated product in step (1) into a separation device for solvent recovery, and the in-situ hydrotreated heavy oil after solvent recovery can be pumped into a cracking device for mild thermal cracking to obtain modified oil, or can be pumped into a target oil tank or equipment as modified oil.

[0009] Further, the heavy oil raw material in step (1) can be one or a mixture of several of heavy crude oil, topped crude oil, atmospheric residue, vacuum residue, deasphalted oil, deoiled pitch, cracking oil, cracking oil, catalytic slurry, coal tar, ethylene tar, shale oil, oil sand pitch, biomass tar.

[0010] Further, the in-situ hydrotreating process in step (1) can be used for one or more of benzene ring saturation in polycyclic aromatic hydrocarbons in heavy oil, removal of sulfur, nitrogen and oxygen heteroatoms, olefin double bond saturation, slowing down oil coking tendency, improving oil thermal stability, heavy oil viscosity reduction, upgrading and enhanced oil recovery.

[0011] Further, the in-situ hydrotreating conditions in step (1) are as follows: the solvent type is C1-C 14 one or more of normal or isomeric alkanes, cycloalkanes, arenes, light distillate oil with distillation range <300℃, the solvent ratio is 5%-50%, the in-situ hydrotreating temperature is 100-450℃, the in-situ hydrotreating time is 1-8h, the catalyst type is sulfide containing one or more combinations of Mo element, W element, Co element, Ni element metal, the CO pressure is 2-8MPa, and the water / CO molar ratio is 0.5-4. The in-situ hydrotreating process can be in the form of fixed bed or slurry bed; the catalyst addition amount is 5-5000μg / g when in-situ hydrotreating is carried out in slurry bed. The reaction device can be a ground equipment or an underground oil and gas reservoir. Further, by determining the viscosity, density, carbon residue value, elemental composition, four-component composition, hydrogenation degree of polycyclic aromatic hydrocarbons, relative hydrogen supply capacity, coking tendency under heating of heavy oil before and after in-situ hydrotreating, the optimized in-situ hydrotreating conditions are as follows: the solvent type is n-hexane, the solvent ratio is 50%, the in-situ hydrotreating temperature is 250℃, the in-situ hydrotreating time is 8h, the catalyst type is Co x Mo y S (x+2y)(x>0, y>0), the catalyst addition amount is 500 μg / g, the CO pressure is 6 MPa, and the water / CO molar ratio is 3 when in-situ hydrogenation is adopted in a slurry bed.

[0012] Further, the mild thermal cracking conditions in step (2) are as follows: the thermal cracking treatment temperature is 360-460°C, the treatment pressure is 0.1-6 MPa of nitrogen, and the treatment time is 3-360 min. Further, by measuring the coke formation rate, the light product yield, the olefin content of the cracking product, the stability of the cracking product, and the like, the preferred cracking treatment temperature is 420°C, the treatment pressure is 4 MPa of nitrogen, and the treatment time is 60 min.

[0013] Further, after the in-situ hydrogenation heat treatment of the raw heavy oil in step (1), the relative hydrogen supply capacity is increased by 50%-270%, the heteroatom removal rate is increased by 5%-50%, the olefin removal rate is increased by 50%-90%, the asphaltene removal rate is increased by 10%-60%, the carbon residue removal rate is increased by 10%-40%, the coke formation induction period is prolonged by 9-46 min, and the viscosity is reduced by 40%-90%; when the in-situ hydrogenation heat treatment is performed in an oil and gas reservoir, the recovery rate is increased by 5%-50%. Under the optimized conditions, after the in-situ hydrogenation heat treatment of the raw heavy oil, the relative hydrogen supply capacity is increased by 170%, the heteroatom removal rate is increased by 20%, the olefin removal rate is increased by 85%, the asphaltene removal rate is increased by 45%, the carbon residue removal rate is increased by 25%, the coke formation induction period is prolonged by 23 min, and the viscosity is reduced by 70%; when the in-situ hydrogenation heat treatment is performed in an oil and gas reservoir, the recovery rate is increased by 30%.

[0014] Further, after the in-situ hydrogenation heat treatment of the raw heavy oil in step (1), the relative hydrogen supply capacity is increased by 50%-270%, the heteroatom removal rate is increased by 5%-50%, the olefin removal rate is increased by 50%-90%, the asphaltene removal rate is increased by 10%-60%, the carbon residue removal rate is increased by 10%-40%, the coke formation induction period is prolonged by 9-46 min, and the viscosity is reduced by 40%-90%; when the in-situ hydrogenation heat treatment is performed in an oil and gas reservoir, the recovery rate is increased by 5%-50%. Under the optimized conditions, after the in-situ hydrogenation heat treatment of the raw heavy oil, the relative hydrogen supply capacity is increased by 170%, the heteroatom removal rate is increased by 20%, the olefin removal rate is increased by 85%, the asphaltene removal rate is increased by 45%, the carbon residue removal rate is increased by 25%, the coke formation induction period is prolonged by 23 min, and the viscosity is reduced by 70%; when the in-situ hydrogenation heat treatment is performed in an oil and gas reservoir, the recovery rate is increased by 30%.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] (1) The present application realizes the refining of heavy oil through in-situ hydrogenation heat treatment under low-severity operation conditions, does not need to use expensive external hydrogen, is simple to operate, and has low refining cost.

[0017] (2) Under low-severity in-situ hydrogenation conditions, the introduced small-molecule alkanes, cycloalkanes, arenes, or light distillate oil is in a subcritical or supercritical phase state, the solvent in the subcritical or supercritical state enhances the dissolution and dispersion properties of the viscous heavy oil system, promotes the in-situ generation of a large amount of hydrogen during the reaction process, and improves the effect of in-situ hydrogenation refining of heavy oil.

[0018] (3) The in-situ hydrogenation heat treatment method of the present application has strong flexibility, strong adaptability to raw materials, wide application range, and can be used for saturating benzene rings in heavy oil, removing heteroatoms such as sulfur, nitrogen and oxygen, saturating olefin double bonds, reducing the coking tendency of oil, improving the thermal stability of oil, reducing the viscosity of heavy oil, upgrading heavy oil, and improving the recovery rate.

[0019] (4) By slightly heat cracking and upgrading the heavy oil according to the present application, the upgrading depth of the heavy oil and the stability of the upgraded oil can be improved, the viscosity of the heavy oil can be significantly reduced, and the coking can be inhibited to realize the stable operation of the heat cracking and upgrading device in the industrial production process. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with examples and comparative examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application.

[0021] Example 1

[0022] A certain mass of vacuum residue and 50% of n-hexane by mass were pumped into a slurry bed reaction device, 500 μg / g of CoS-MoS2 catalyst was added, wherein the mass ratio of Co to Mo was 1:1, then a certain amount of water was added according to the water / CO molar ratio of 3, and finally 6 MPa of CO gas was introduced under stirring conditions for in-situ hydrogenation heat treatment. The in-situ hydrogenation heat treatment temperature was 250°C, and the in-situ hydrogenation heat treatment time was 8h. After the reaction was completed, the in-situ hydrogenation product was pumped into a separation device for solvent recovery to obtain in-situ hydrogenation residue. Subsequently, the in-situ hydrogenation residue was pumped into a cracking device for heat cracking at 420°C for 60 min to obtain a cracking product.

[0023] The basic properties of the original vacuum residue and the in-situ hydrogenation residue obtained in Example 1 are shown in Table 1, the hydrogen distribution is shown in Table 2, and the carbon distribution is shown in Table 3. The product distribution, olefin content and spot grade of the heat cracking product of the original residue and the in-situ hydrogenation residue obtained in Example 1 are shown in Table 4.

[0024] As shown in Table 1, after the in-situ hydrogenation heat treatment according to the present application, the viscosity of the residue was significantly reduced from 1384 mPa·s to 313 mPa·s, with a reduction of 77%, the density was reduced from 1.0032 to 1.0011, the carbon residue value was reduced from 22.4% to 16.7%, with a reduction of 25.4%, the hydrogen-carbon atomic ratio was increased from 1.39 to 1.60, the sulfur and nitrogen heteroatom content was significantly reduced, the asphaltene content was reduced from 2.73wt% to 1.99wt%. At the same time, the hydrogen-donating ability of the residue after the in-situ hydrogenation heat treatment according to the present application was significantly increased from 3.65 mg-H / g-Oil to 9.91 mg-H / g-Oil, with a growth rate of 171.5%.

[0025] As shown in Table 2 and Table 3, the content of condensed ring aromatics and heteroatom aromatics in the residual oil after in-situ hydrogenation heat treatment according to the present application is significantly reduced, and the content of naphthenes or hydrogenated aromatics is greatly increased.

[0026] As shown in Table 4, compared with the product obtained by cracking the original residual oil, after the residual oil treated by in-situ hydrogenation heat treatment according to the present application is cracked, the yield of gas and light distillate oil is increased, the content of coke is significantly reduced, the viscosity of the liquid phase product of thermal cracking is significantly reduced, the overall olefin content is reduced from 3.12% to 0.98%, the spot grade is improved to level 2, and the stability of the oil product is significantly enhanced.

[0027] Table 1 Basic properties of the original vacuum residual oil and the in-situ hydrogenated residual oil obtained in Example 1

[0028]

[0029]

[0030] Table 2 Hydrogen distribution of the original vacuum residual oil and the in-situ hydrogenated residual oil obtained in Example 1

[0031]

[0032] Table 3 Carbon distribution of the original vacuum residual oil and the in-situ hydrogenated residual oil obtained in Example 1

[0033]

[0034] Table 4 Product distribution, olefin content and spot grade of the thermal cracking product of the original residual oil and the in-situ hydrogenated residual oil of Example 1

[0035]

[0036]

[0037] Example 2

[0038] A certain amount of vacuum residual oil and 50% by mass of n-hexane were pumped into a slurry bed reaction device, 500 μg / g of CoS-MoS2 catalyst was added, wherein the mass ratio of Co to Mo was different from that of Example 1, which was 10:1, then a certain amount of water was added according to the water / CO molar ratio of 3, and finally 6 MPa of CO gas was introduced for in-situ hydrogenation heat treatment under stirring. The in-situ hydrogenation heat treatment temperature was 250°C, and the in-situ hydrogenation heat treatment time was 8h. After the reaction was completed, the in-situ hydrogenation product was pumped into a separation device for solvent recovery to obtain in-situ hydrogenated residual oil-1. Subsequently, the in-situ hydrogenated residual oil-1 was pumped into a cracking device for thermal cracking at 420°C for 60 min to obtain a cracking product.

[0039] The basic properties of the in-situ hydrogenated residue-1 obtained in Example 2 are shown in Table 5, the hydrogen distribution is shown in Table 6, and the carbon distribution is shown in Table 7. The product distribution, olefin content and spot grade of the thermal cracking product of the in-situ hydrogenated residue-1 obtained in Example 2 are shown in Table 8.

[0040] As can be seen from Table 5 and Table 1, even if the Co-Mo mass ratio of the in-situ hydrogenation treatment catalyst is changed to 10:1, the viscosity of the in-situ hydrogenated residue-1 obtained after the in-situ hydrogenation heat treatment of the application is still significantly reduced, from 1384 mPa-s to 341 mPa-s, a decrease of 75%, the density is reduced from 1.0032 to 1.0016, the carbon residue value is reduced from 22.4% to 17.4%, a decrease of 22.3%, the hydrogen-carbon atomic ratio is increased from 1.39 to 1.60, the sulfur-nitrogen heteroatom content is significantly reduced, and the asphaltene content is reduced from 2.73wt% to 2.01wt%. At the same time, the hydrogen-donating capacity of the residue oil after the in-situ hydrogenation heat treatment of the application is significantly increased, from 3.65 mg-H / g-Oil to 9.85 mg-H / g-Oil, an increase of 169.86%.

[0041] As can be seen from Table 6, Table 7, Table 2 and Table 3, after changing the in-situ hydrogenation treatment catalyst, the content of condensed ring aromatics and heteroatom aromatics in the in-situ hydrogenated residue-1 obtained after the in-situ hydrogenation heat treatment of the application is still significantly reduced compared with the original residue oil, and the content of naphthenes or hydrogenated aromatics is significantly increased.

[0042] As can be seen from Table 8 and Table 4, compared with the products obtained by thermal cracking of the original residue oil, after the in-situ hydrogenation heat treatment of the application, the in-situ hydrogenated residue-1 is subjected to thermal cracking, the gas and light oil yields in the product are increased to 2.9wt% and 41.3wt% respectively, the coke content is significantly reduced to 0.09wt%, the viscosity of the thermal cracking liquid phase product is significantly reduced, the overall olefin content is reduced from 3.12% to 0.99%, the spot grade is improved to grade 2, and the oil stability is significantly enhanced.

[0043] Table 5 Basic properties of the in-situ hydrogenated residue-1 obtained in Example 2

[0044]

[0045] Table 6 Hydrogen distribution of the in-situ hydrogenated residue-1 obtained in Example 2

[0046]

[0047] Table 7 Carbon distribution of the in-situ hydrogenated residue-1 obtained in Example 2

[0048]

[0049] Table 8 Product distribution, olefin content and spot rating of the thermal cracking product of the in-situ hydrogenated residue-1 of Example 2

[0050]

[0051] Example 3

[0052] A certain mass of vacuum residue and 50% by mass of n-hexane were pumped into a slurry bed reaction device, 500 μg / g of CoS-MoS2 catalyst was added, wherein the mass ratio of Co to Mo was different from that of Examples 1 and 2, being 1:10, then a certain amount of water was added according to a water / CO molar ratio of 3, and finally 6 MPa of CO gas was introduced to perform in-situ hydrogenation heat treatment under stirring. The in-situ hydrogenation heat treatment temperature was 250°C, and the in-situ hydrogenation heat treatment time was 8 h. After the reaction was completed, the in-situ hydrogenation product was pumped into a separation device to recover the solvent to obtain in-situ hydrogenated residue-2. Subsequently, the in-situ hydrogenated residue-2 was pumped into a cracking device to perform thermal cracking at 420°C for 60 min to obtain a cracking product.

[0053] The basic properties of the in-situ hydrogenated residue-2 obtained in Example 2 are shown in Table 9, the hydrogen distribution is shown in Table 10, and the carbon distribution is shown in Table 11. The product distribution, olefin content and spot rating of the thermal cracking product of the in-situ hydrogenated residue-1 of Example 2 are shown in Table 12.

[0054] As can be seen from Tables 9 and 1, even if the Co-Mo mass ratio of the in-situ hydrogenation treatment catalyst is changed to 1:10, the viscosity of the in-situ hydrogenated residue-2 obtained after in-situ hydrogenation heat treatment according to the present application is still significantly reduced, from 1384 mPa-s to 314 mPa-s, with a decrease of 77%, the density is reduced from 1.0032 to 1.0013, the carbon residue value is reduced by 24.6% from 22.4% to 16.9%, the hydrogen-carbon atomic ratio is increased from 1.39 to 1.60, the sulfur-nitrogen heteroatom content is significantly reduced, and the asphaltene content is reduced from 2.73 wt% to 1.99 wt%. At the same time, the hydrogen-donating ability of the in-situ hydrogenated residue-2 after in-situ hydrogenation heat treatment according to the present application is significantly increased to 9.87 mg-H / g-Oil, with a growth rate of 170.41%.

[0055] As can be seen from Tables 10, 11, 2 and 3, after changing the catalyst for in-situ hydrogenation treatment, the content of condensed ring aromatics and heteroatom aromatics in the in-situ hydrogenated residue-2 obtained after in-situ hydrogenation heat treatment according to the present application is still significantly reduced compared with the original residue, and the content of naphthenes or hydrogenated aromatics is significantly increased.

[0056] From Table 12 and Table 4, compared with the product obtained by cracking the raw residue, the gas and light oil yield of the product obtained by cracking the in-situ hydrogenated residue-2 obtained by in-situ hydrogenation and heat treatment of the raw residue according to the present application are increased to 3.0 wt% and 40.3 wt%, respectively, the coke content is significantly reduced to 0.09 wt%, the viscosity of the liquid product of the thermal cracking is significantly reduced, the overall olefin content is reduced from 3.12% to 0.99%, the spot level is improved to level 2, and the oil stability is significantly enhanced.

[0057] Table 9 Basic properties of the in-situ hydrogenated residue-2 obtained in Example 3

[0058]

[0059] Table 10 Hydrogen distribution of the in-situ hydrogenated residue-2 obtained in Example 3

[0060]

[0061] Table 11 Carbon distribution of the in-situ hydrogenated residue-2 obtained in Example 3

[0062]

[0063]

[0064] Table 12 Product distribution, olefin content and spot level of the thermal cracking product of the in-situ hydrogenated residue-2 of Example 3

[0065]

[0066] Comparative Example 1

[0067] The in-situ hydrogenation and heat treatment of the vacuum residue was carried out without adding solvent, i.e. a certain amount of vacuum residue was pumped into a slurry bed reaction device, 500 μg / g of CoS-MoS2 catalyst was added, wherein the mass ratio of Co to Mo was 1:1, then a certain amount of water was added according to the water / CO molar ratio of 3, and finally 6 MPa of CO gas was introduced for in-situ hydrogenation and heat treatment under stirring. The in-situ hydrogenation and heat treatment temperature was 250°C, and the in-situ hydrogenation and heat treatment time was 8 h. After the reaction, the in-situ hydrogenated residue was obtained. Then, the in-situ hydrogenated residue was pumped into a cracking device for thermal cracking at 420°C for 60 min to obtain the cracking product.

[0068] The basic properties of the in-situ hydrogenated residue obtained in Comparative Example 1 without adding solvent are shown in Table 13, the hydrogen distribution is shown in Table 14, and the carbon distribution is shown in Table 15. The product distribution, olefin content and spot level of the thermal cracking product of the in-situ hydrogenated residue obtained in Comparative Example 1 are shown in Table 16.

[0069] As shown in Table 1 and Table 13, compared with the original residue, the viscosity, density, carbon residue, sulfur and nitrogen heteroatom content, and asphaltene content of the in-situ hydrogenated residue obtained by in-situ hydrogenation of the vacuum residue without adding solvent are basically not reduced, and the hydrogen-carbon atomic ratio is not significantly increased. At the same time, the hydrogen-donating capacity of the in-situ hydrogenated residue obtained without adding solvent is only 3.94 mg-H / g-Oil, which is not significantly increased compared with the original residue (3.65 mg-H / g-Oil). As shown in Table 2, Table 3, Table 14 and Table 15, compared with the original residue, the content of condensed ring aromatics and heteroatom aromatics in the in-situ hydrogenated residue obtained without adding solvent is not significantly reduced, and the content of naphthenes or hydrogenated aromatics is basically unchanged.

[0070] Table 13 Basic properties of the in-situ hydrogenated residue obtained in Comparative Example 1

[0071]

[0072] Table 14 Hydrogen distribution of the in-situ hydrogenated residue obtained in Comparative Example 1

[0073]

[0074] Table 15 Carbon distribution of the in-situ hydrogenated residue obtained in Comparative Example 1

[0075]

[0076]

[0077] Table 16 Product distribution, olefin content and spot grade of the thermal cracking product of the in-situ hydrogenated residue of Comparative Example 1

[0078]

[0079] As shown in Table 4 and Table 16, after the in-situ hydrogenated residue obtained without adding solvent is subjected to thermal cracking, the gas and light distillate yields in the obtained product are basically unchanged compared with the thermal cracking product of the original residue, which are 2.6 wt% and 35.1 wt%, respectively, and the coke content is still as high as 1.2 wt%. In addition, compared with the thermal cracking liquid product of the original residue, the viscosity of the thermal cracking liquid product of the in-situ hydrogenated residue obtained without adding solvent is not significantly reduced, the overall olefin content is still as high as 2.65%, the spot grade is 4, and the oil product stability is poor.

[0080] As can be seen from Comparative Examples 1-3 and Comparative Example 1, the solvent in a subcritical or supercritical state can significantly enhance the dissolution and dispersion properties of a viscous heavy oil system, promote the in-situ generation of a large amount of hydrogen in the in-situ hydrotreating process, and greatly improve the in-situ hydrogenation effect on the vacuum residue, so that the viscosity, carbon residue value, sulfur and nitrogen heteroatom content, and asphaltene content of the vacuum residue can be significantly reduced, the naphthene and hydrogenated aromatic hydrocarbon content can be increased, and the hydrogen supply capacity can be greatly improved by the in-situ hydrotreating process under a relaxed severity operation condition. Based on this, the cracking selectivity and light cracking product yield of the in-situ hydrogenated residue oil obtained in Example 1 in a further mild thermal cracking process are significantly increased, the overall olefin content of the liquid product obtained after mild thermal cracking is significantly reduced, the stability of the oil product is significantly improved, and the viscosity of the oil product is greatly reduced.

[0081] Comparative Example 2

[0082] The vacuum residue was hydrotreated using exogenous hydrogen gas under the condition of adding a solvent, that is, a certain amount of vacuum residue and 50% by mass of n-hexane were pumped into a slurry bed reaction device, 500 μg / g of CoS-MoS2 catalyst was added, the mass ratio of Co to Mo was 1:1, then 6 MPa of exogenous hydrogen gas was introduced for hydrofining under stirring, the hydrofining temperature was 250°C, and the hydrofining time was 8 h. After the reaction was completed, the hydrofining product was pumped into a separation device for solvent recovery to obtain a hydrofining residue oil. Then, the hydrofining residue oil was pumped into a cracking device for thermal cracking at 420°C for 60 min to obtain a cracking product.

[0083] The basic properties of the hydrofining residue oil obtained in Comparative Example 2 are shown in Table 17, the hydrogen distribution is shown in Table 18, the carbon distribution is shown in Table 19, the product distribution, olefin content, and spot grade of the thermal cracking product of the hydrofining residue oil obtained in Comparative Example 2 are shown in Table 20.

[0084] As can be seen from Tables 1 and 17, under the same reaction severity, even if the vacuum residue is hydrotreated using exogenous hydrogen gas under the condition of adding a solvent, the hydrofining effect is poor, the viscosity, density, carbon residue value, sulfur and nitrogen heteroatom content, and asphaltene content of the obtained hydrofining residue oil are slightly smaller than those of the original residue oil, and the hydrogen-carbon atom ratio is slightly larger. At the same time, the hydrogen supply capacity of the hydrofining residue oil obtained by using exogenous hydrogen gas under the condition of adding a solvent is only 4.11 mg-H / g-Oil, which is not significantly larger than that of the original residue oil (3.65 mg-H / g-Oil).

[0085] As can be seen from Tables 2, 3, 18, and 19, under the same reaction severity, the content of condensed ring aromatics in the hydrofining residue oil obtained by hydrotreating the vacuum residue using hydrogen gas under the condition of adding a solvent is not significantly reduced compared with that of the original residue oil, and the content of naphthene or hydrogenated aromatic hydrocarbons is basically unchanged.

[0086] Table 17 Basic properties of the hydrogenated residue oil obtained from Comparative Example 2

[0087]

[0088] Table 18 Hydrogen distribution of the hydrogenated residue oil obtained from Comparative Example 2

[0089]

[0090]

[0091] Table 19 Carbon distribution of the hydrogenated residue oil obtained from Comparative Example 2

[0092]

[0093] Table 20 Product distribution, olefin content and spot rating of the thermal cracking product of the hydrogenated residue oil of Comparative Example 2

[0094]

[0095] As can be seen from Tables 4 and 20, after thermal cracking of the hydrogenated residue oil obtained by using external hydrogen gas for hydrogen thermal treatment of the vacuum residue under the condition of adding solvent, the product gas and light distillate oil yield are not obviously improved compared with the thermal cracking product of the original residue oil, being 2.6wt% and 35.3wt%, respectively, while the coke yield is higher, being 1.1wt%, and the overall olefin content of the thermal cracking product is as high as 2.47%, the spot rating is 4, and the oil product stability is poor.

[0096] As can be seen from Comparative Examples 1-3 and Comparative Example 2, the hydrogenation effect is also very limited when using external hydrogen gas for hydrogen thermal treatment of the vacuum residue under the condition of adding solvent, while the in-situ hydrogenation thermal treatment effect of the condensed ring aromatic hydrocarbons in the vacuum residue under the mild severity operating condition is obviously better than that of the external hydrogen gas, which not only avoids the cumbersome steps of using external hydrogen gas for hydrogenation, but also greatly reduces the production cost, and achieves the purpose of heavy oil refining.

[0097] The above description is only the preferred embodiment of the present application, and is not intended to limit the other forms of the present application. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments. However, any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application, without departing from the technical solution content of the present application, still belongs to the protection scope of the present application.

Claims

1. A method for slight thermal reforming of heavy oil, comprising the following steps: (1) A certain proportion of solvent is pumped into a reaction device containing raw material heavy oil, and in-situ hydrogenation heat treatment is carried out under the action of water, CO gas and catalyst. The solvent type, solvent ratio, in-situ hydrogenation temperature, in-situ hydrogenation time, catalyst type and addition amount, CO pressure and water / CO molar ratio are optimized and screened in the in-situ hydrogenation heat treatment reaction process to obtain in-situ hydrogenation products. The solvent is one or more of cycloalkanes, aromatics, light distillate oil with a distillation range of <300℃, and C1~C14 normal or isoalkanes. The solvent mass ratio is 5%~50%, the in-situ hydrogenation temperature is 100~450℃, the in-situ hydrogenation time is 1~8h, the catalyst type is a sulfide containing one or more of the elements Mo, W, Co and Ni, the CO pressure is 2~8MPa, and the water / CO molar ratio is 0.5~4. The solvent is in a subcritical or supercritical state. (2) The in-situ hydrogenation product in step (1) is pumped into a separation unit for solvent recovery. The in-situ hydrogenation product heavy oil after solvent recovery is pumped into a cracking unit for mild thermal cracking to obtain modified oil, or pumped into the target oil tank as modified oil.

2. The method according to claim 1, characterized in that: The raw material heavy oil mentioned in step (1) is one or more of the following: heavy crude oil, topped crude oil, atmospheric residue, vacuum residue, deasphalted oil, deoiled asphalt, cracked oil, catalytic slurry, coal tar, ethylene tar, shale oil, oil sands asphalt, and biomass tar.

3. The method according to claim 1, characterized in that: In step (1), in-situ hydrogenation heat treatment is used to saturate the benzene ring in the polycyclic aromatic hydrocarbons of heavy oil, remove sulfur, nitrogen and oxygen heteroatoms, saturate the olefin double bond, slow down the coking tendency of oil, improve the thermal stability of oil, reduce the viscosity and improve the quality of heavy oil, and improve the recovery rate of one or more of the following:

4. The method according to claim 1, characterized in that: In step (1), the in-situ hydrogenation heat treatment process can be carried out in a fixed bed or a slurry bed form; when using a slurry bed for in-situ hydrogenation, the amount of catalyst added is 5~5000μg / g; the reaction device is a surface equipment or an underground oil and gas reservoir.

5. The method according to claim 4, characterized in that: The solvent type in step (1) is n-hexane, the solvent mass ratio is 50%, the in-situ hydrogenation temperature is 250℃, the in-situ hydrogenation time is 8h, the catalyst type is CoxMoyS(x+2y), where x>0, y>0, the CO pressure is 6MPa, the water / CO molar ratio is 3, and the catalyst addition amount when using slurry bed in-situ hydrogenation is 500μg / g.

6. The method according to claim 1, characterized in that: The thermal cracking treatment temperature in step (2) is 360~460℃, the treatment pressure is 0.1~6MPa nitrogen, and the treatment time is 3~360min.

7. The application of the method according to any one of claims 1-6, characterized in that: Compared to feedstock heavy oil, in-situ hydrogenated heavy oil has a 50%–270% higher relative hydrogen supply capacity, a 5%–50% higher heteroatom removal rate, a 50%–90% higher olefin removal rate, a 10%–60% higher asphaltene removal rate, a 10%–40% higher residual carbon removal rate, a 9–46 min longer coking induction period, and a 40%–90% lower viscosity. When in-situ hydrogenation heat treatment is carried out in oil and gas reservoirs, the recovery rate is increased by 5%–50%.

8. The application according to claim 7, characterized in that: Compared to feedstock heavy oil, in-situ hydrogenated heavy oil has a 170% higher relative hydrogen supply capacity, a 30% higher heteroatom removal rate, a 90% higher olefin removal rate, a 30% higher asphaltene removal rate, a 25% higher residual carbon removal rate, a 23-minute longer coking induction period, and a 77% lower viscosity. When in-situ hydrogenation heat treatment is carried out in oil and gas reservoirs, the recovery rate is increased by 30%.

9. The application according to claim 8, characterized in that: When the coke production rate is less than 0.1 wt%, compared with the direct light thermal cracking of feedstock heavy oil, the yield of cracked light products of in-situ hydrogenated heavy oil is increased by 10-50%, the overall olefin removal rate of liquid products is increased by 50-90%, the oil stability is improved by 1-3 grades, and the viscosity is reduced by 40-90%.

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