Method for producing BTX and high-quality gasoline from inferior heavy oil

Abstract

A method for producing BTX and high-quality gasoline from inferior heavy oil comprises the following steps: 1) introducing the inferior heavy oil into a heavy oil riser of a double-riser catalytic cracking device to obtain catalytic gasoline and catalytic diesel oil; 2) cutting and fractionating the catalytic gasoline to obtain a catalytic gasoline light fraction and a catalytic gasoline heavy fraction, wherein the catalytic gasoline light fraction and a part of the catalytic gasoline heavy fraction are directly used as gasoline blending components; 3) hydrofining the catalytic diesel oil to obtain hydrogenated catalytic diesel oil, and simultaneously introducing the hydrogenated catalytic diesel oil and the other part of the catalytic gasoline heavy fraction into a second riser of the double-riser catalytic cracking device to obtain cracked gasoline and cracked diesel oil; and 4) carrying out cutting fractionation on the cracked gasoline to obtain a cracked gasoline light fraction and a cracked gasoline heavy fraction, carrying out aromatic hydrocarbon extraction and aromatic hydrocarbon separation on the cracked gasoline light fraction to obtain BTX and raffinate gasoline, using the raffinate gasoline as a gasoline blending component, and using BTX and high-quality gasoline as final products to obtain a high-added-value product and a high-quality gasoline product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reprocessing of inferior heavy oil feedstock in the field of petroleum refining, in particular to a method for producing BTX and high-quality gasoline from inferior heavy oil. BACKGROUND

[0002] The catalytic cracking unit produces 70% of the total production of vehicle gasoline and 1 / 3 of the total production of vehicle diesel in China. Technical transformation of the catalytic cracking unit for producing chemical raw materials and improving product added value is an effective way to solve the overcapacity of finished oil products and improve the economic benefits of refining enterprises at present.

[0003] The gasoline products and diesel products produced by the catalytic cracking unit contain a large amount of aromatic hydrocarbon resources, while BTX as an important organic chemical raw material has been in short supply for a long time. Therefore, the patent applied for by the applicant in 2022 provides a method for maximizing the production of light aromatic hydrocarbons from inferior heavy oil. Specifically, the gasoline and diesel products obtained from the heavy oil riser are selectively separated, and the heavy gasoline fraction, light diesel fraction and hydrotreated heavy diesel fraction obtained are selectively cracked in the second riser to maximize the yield of light aromatic hydrocarbons in the gasoline product; the light gasoline fraction is used as a gasoline blending component. However, in the actual application process, the final product of this method is C6-C9 light aromatic hydrocarbon, among which the additional value of C9 is relatively low; and the olefin content in the gasoline product obtained by this method is relatively high (more than 40%), which needs to be further blended. SUMMARY

[0004] In order to further increase the production of BTX high-value-added products and produce high-quality gasoline, the present application provides a method for producing BTX and high-quality gasoline from inferior heavy oil, which obtains C6-C8 light aromatic hydrocarbons, i.e. high-value-added products; at the same time, the properties of the gasoline product are significantly improved, the olefin content in the gasoline product is greatly reduced, and high-quality gasoline product is obtained.

[0005] In order to achieve the above-mentioned purpose, the specific scheme adopted by the present application is as follows: a method for producing BTX and high-quality gasoline from inferior heavy oil, characterized in that it comprises the following steps:

[0006] 1) introducing inferior heavy oil into the heavy oil riser of the dual-riser catalytic cracking unit to obtain catalytic gasoline, catalytic diesel and other products;

[0007] 2) cutting and fractionating the catalytic gasoline to obtain a catalytic gasoline light fraction and a catalytic gasoline heavy fraction, the catalytic gasoline heavy fraction being divided into two parts, and the catalytic gasoline light fraction and a part of the catalytic gasoline heavy fraction being directly used as a gasoline blending component;

[0008] 3) catalytically cracking diesel is hydrogenated to obtain hydrogenated catalytically cracking diesel, hydrogenated catalytically cracking diesel and another part of catalytically cracking diesel are introduced into the second riser of the dual riser catalytic cracking device to obtain cracking gasoline and cracking diesel;

[0009] 4) cutting fractionation of cracking gasoline to obtain cracking gasoline light fraction and cracking gasoline heavy fraction, cracking gasoline light fraction is subjected to aromatic extraction and aromatic separation to obtain BTX and raffinate gasoline, raffinate gasoline is used as gasoline blending component, BTX and high-quality gasoline are final products.

[0010] As an optimization of the above-mentioned method for producing BTX and high-quality gasoline from inferior heavy oil, the mass ratio of catalytically cracking diesel used as gasoline blending component to catalytically cracking diesel introduced into the second riser is 0.1-20:1.

[0011] As another optimization of the above-mentioned method for producing BTX and high-quality gasoline from inferior heavy oil, in step 1), the reaction temperature of inferior heavy oil in the heavy oil riser of the dual riser catalytic cracking device is 480-550℃, the catalyst / oil ratio is 4-10, the reaction pressure is 0.1-0.4 MPa, the reaction time is 2-5 s, and the amount of atomized water vapor is 3-8 w% of the feed.

[0012] As another optimization of the above-mentioned method for producing BTX and high-quality gasoline from inferior heavy oil, in step 2), the cutting point of catalytically cracking gasoline cutting fractionation is 70-75℃, so that more than 95% of aromatics in catalytically cracking gasoline are enriched in catalytically cracking diesel heavy fraction.

[0013] As another optimization of the above-mentioned method for producing BTX and high-quality gasoline from inferior heavy oil, in step 3), the reaction temperature of catalytically cracking diesel hydrogenation is 320-390℃, the hydrogen partial pressure is 5.0-10.0 MPa, the volume space velocity is 0.5-1.5 h -1 , and the hydrogen / oil volume ratio is 300-800:1.

[0014] As another optimization of the above-mentioned method for producing BTX and high-quality gasoline from inferior heavy oil, in step 3), the active metal in the hydrogenation catalyst is one or more of nickel, cobalt and tungsten.

[0015] As another optimization of the above-mentioned method for producing BTX and high-quality gasoline from inferior heavy oil, in step 3), the reaction temperature of hydrogenated catalytically cracking diesel and catalytically cracking diesel heavy fraction in the second riser of the dual riser device is 550-650℃, the catalyst / oil ratio is 8-14, the reaction pressure is 0.1-0.4 MPa, the reaction time is 2-5 s, and the amount of atomized water vapor is 1-4 w% of the feed.

[0016] As another optimized solution of the above method for producing BTX and high-quality gasoline from inferior heavy oil: in step 3), cracked diesel and catalytic diesel are mixed and hydrotreated.

[0017] As another optimization scheme of the above method for producing BTX and high-quality gasoline from inferior heavy oil: in the step 4), the cut point of the cracked gasoline cut fractionation is 140-160°C.

[0018] As another optimization scheme for the above-mentioned method of producing BTX and high-quality gasoline from inferior heavy oil: the extraction solvent used for extracting aromatics from the light fraction of cracked gasoline in step 4) is one or more of sulfolane, dimethyl sulfoxide, dimethylformamide, N-methylmethylpyrrolidone, N-formylmorpholine, triethylene glycol, tetraethylene glycol, pentaethylene glycol, methanol, and acetonitrile.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention provides a method for producing BTX and high-quality gasoline from inferior heavy oil. The inferior heavy oil is introduced into a heavy oil riser to obtain catalytic gasoline and catalytic diesel. The catalytic gasoline is selectively separated to obtain a catalytic gasoline light fraction free of aromatics and a catalytic gasoline heavy fraction rich in aromatics. A portion of the catalytic gasoline heavy fraction and the catalytic gasoline light fraction are used as gasoline blending components, thereby improving the properties of the gasoline product and reducing the olefin content of the gasoline product.

[0021] 2. In the present invention, after hydrorefining, the catalytic diesel is mixed with another portion of the heavy fraction of catalytic gasoline and fed into a second riser to obtain cracked gasoline. The cracked gasoline is selectively separated to obtain a heavy fraction of cracked gasoline rich in C9 and above aromatics and a light fraction of cracked gasoline rich in C6-C8 aromatics. The cracked gasoline is fed into an aromatics complex for pre-hydrogenation and aromatics extraction to obtain a high-value-added BTX product. This improves economic efficiency and solves the problem of outlet of inferior heavy oil in refineries, resulting in significant economic and social benefits.

[0022] 3. In the present invention, the processing load of the second riser can be reduced, and excessive cracking of the hydrocatalytic diesel and energy waste can be avoided, that is, the energy utilization efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the process flow of the present invention;

[0024] Figure 2 Schematic diagram of the process flow of the comparative example. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be further described in detail below in combination with specific embodiments. The parts not described and disclosed in the following embodiments of the present application should be understood as the prior art known or should be known by the skilled in the art.

[0026] A method for producing BTX and high-quality gasoline from inferior heavy oil, comprising the following steps:

[0027] 1) The inferior heavy oil is subjected to property analysis, and is introduced into a heavy oil riser of a dual riser catalytic cracking device, and under optimized operating conditions, the reaction depth is reasonably controlled to obtain catalytic gasoline, catalytic diesel and other products; in this step, the reaction temperature of the inferior heavy oil in the heavy oil riser of the dual riser catalytic cracking device is 480-550 ℃, the catalyst / oil ratio is 4-10, the reaction pressure is 0.1-0.4 MPa, the reaction time is 2-5 s, and the atomized water vapor accounts for 3-8 w% of the feed amount.

[0028] 2) The catalytic gasoline is subjected to property analysis, and the appropriate cutting point is determined, so that the catalytic gasoline is cut and fractionated to obtain catalytic gasoline light fraction and catalytic gasoline heavy fraction, and the catalytic gasoline heavy fraction is divided into two parts; the catalytic gasoline light fraction and a part of the catalytic gasoline heavy fraction are directly used as gasoline blending components, which significantly improves the properties of the gasoline and reduces the olefin content of the gasoline product, and the olefin content can be reduced to 25%.

[0029] In this step, the analysis method of the catalytic gasoline is distillation range, elemental composition or hydrocarbon group composition, and the cutting point is determined to be 70-75 ℃ according to the analysis data, so that more than 95 w% of the aromatics in the catalytic gasoline are enriched in the catalytic gasoline heavy fraction. The catalytic gasoline is separated by using a conventional fractionating column, and the operating conditions of the fractionating column are as follows: the feed temperature is 50-100 ℃, the bottom temperature is 50-200 ℃, the top temperature is 50-150 ℃, the top pressure is 0.01-1 MPa, the catalytic gasoline light fraction is located at the top of the fractionating column, and the catalytic gasoline heavy fraction is located at the bottom of the fractionating column.

[0030] 3) The catalytic diesel is subjected to hydrofining to obtain hydrofined catalytic diesel, and the hydrofined catalytic diesel and the other part of the catalytic gasoline heavy fraction are simultaneously introduced into a second riser of a dual riser catalytic cracking device to obtain cracked gasoline and cracked diesel; the reaction temperature of the catalytic diesel hydrofining is 320-390 ℃, the hydrogen partial pressure is 5.0-10.0 MPa, the volume space velocity is 0.5-1.5 h -1 , and the hydrogen / oil volume ratio is 300-800:1; the active metal in the hydrofining catalyst is one or more of nickel, cobalt and tungsten, and the content of the active metal is 12%-30%.

[0031] In this step, the reaction temperature of the hydrocatalytic diesel and catalytic gasoline heavy fraction in the second riser of the dual riser catalytic cracking device is 550-650℃, the catalyst to oil ratio is 8-14, the reaction pressure is 0.1-0.4 MPa, the reaction time is 2-5 s, the atomized water vapor is 1-4 w% of the feed amount, and the catalyst is selected from conventional catalytic cracking catalysts.

[0032] In this step, the cracked diesel is mixed with the catalytic diesel for hydrofining.

[0033] The mass ratio of the catalytic gasoline heavy fraction used as a gasoline blending component to the catalytic gasoline heavy fraction introduced into the second riser is 0.1-20:1. High-quality gasoline can be obtained, and high-value-added products can be obtained.

[0034] 4) The cracked gasoline is cut and fractionated to obtain a cracked gasoline light fraction and a cracked gasoline heavy fraction, the cut point of the cracked gasoline is 140-150℃, the cracked gasoline heavy fraction is rich in C9+ aromatic hydrocarbons, and the cracked gasoline light fraction is rich in C6-C8 aromatic hydrocarbons; the cracked gasoline light fraction is subjected to pre-hydrogenation, aromatic hydrocarbon extraction and aromatic hydrocarbon separation to obtain BTX and raffinate gasoline, the raffinate gasoline is used as a gasoline blending component, and the BTX and high-quality gasoline are final products.

[0035] In this step, the cracked gasoline heavy fraction is introduced into the second riser of the dual riser catalytic cracking device for cracking to obtain C6-C8 aromatic hydrocarbons, further improving the yield of high-value-added products.

[0036] In this step, the reaction temperature of the pre-hydrogenation is 300-420℃, the hydrogen partial pressure is 2.5-3.5 MPa, the hydrogen / oil volume ratio is 300-500:1, the volume space velocity is 1.5-4 h -1 When the cracked gasoline light fraction is subjected to aromatic hydrocarbon extraction, the extraction solvent used is one or more of sulfolane, dimethyl sulfoxide, dimethyl formamide, N-methyl methylpyrrolidone, N-formyl morpholine, triethylene glycol, tetraethylene glycol, pentaethylene glycol, methanol, and acetonitrile. The mass ratio of the extraction solvent to the cracked gasoline light fraction is 3-8:1, the overhead temperature of the extraction column used for extraction is 130-190℃, and the pressure is 1.1-2.0 MPa.

[0037] The present application can obtain high-value-added BTX products, solve the problem of outlet of poor heavy oil in a refinery, and improve economic and social benefits. The second riser processing load can be reduced, excessive cracking of hydrocatalytic diesel and energy waste can be avoided, and the energy utilization efficiency is improved.

[0038] Example 1

[0039] A method for producing BTX and high-quality gasoline from poor heavy oil, comprising the following steps:

[0040] 1) The inferior heavy oil is analyzed for its properties, and the inferior heavy oil is introduced into the heavy oil riser of the dual riser catalytic cracking unit, and under the optimized operating conditions, the reaction depth is properly controlled to obtain catalytic gasoline, catalytic diesel and other products. In this step, the reaction temperature of the inferior heavy oil in the heavy oil riser of the dual riser catalytic cracking unit is 480℃, the catalyst / oil ratio is 4, the reaction pressure is 0.1 MPa, the reaction time is 2s, and the atomized water vapor accounts for 3w% of the feed amount.

[0041] 2) The catalytic gasoline is analyzed for its properties, and the appropriate cutting point is determined, and the catalytic gasoline is cut and fractionated to obtain catalytic gasoline light fraction and catalytic gasoline heavy fraction, and the catalytic gasoline heavy fraction is divided into two parts, and the catalytic gasoline light fraction and a part of the catalytic gasoline heavy fraction are directly used as gasoline blending components.

[0042] In this step, the analysis method of the catalytic gasoline is distillation range, elemental composition or hydrocarbon group composition, and the cutting point is determined to be 70℃ according to the analysis data, so that more than 95w% of the aromatics in the catalytic gasoline are enriched in the catalytic gasoline heavy fraction. The catalytic gasoline is separated by using a conventional fractionating column, and the operating conditions of the fractionating column are as follows: the feed temperature is 50℃, the bottom temperature is 50℃, the top temperature is 50℃, the top pressure is 0.01 MPa, the catalytic gasoline light fraction is located at the top of the fractionating column, and the catalytic gasoline heavy fraction is located at the bottom of the fractionating column.

[0043] 3) The catalytic diesel is hydrotreated to obtain hydrotreated catalytic diesel, and the hydrotreated catalytic diesel and the other part of the catalytic gasoline heavy fraction are introduced into the second riser of the dual riser catalytic cracking unit at the same time to obtain cracked gasoline and cracked diesel; the reaction temperature of the catalytic diesel hydrotreating is 320℃, the hydrogen partial pressure is 5.0 MPa, the volume space velocity is 0.5h -1 , the hydrogen / oil volume ratio is 300:1; the active metal in the hydrotreating catalyst is nickel, and the content of the active metal is 12%.

[0044] In this step, the reaction temperature of the hydrotreated catalytic diesel and the catalytic gasoline heavy fraction in the second riser of the dual riser catalytic cracking unit is 550℃, the catalyst / oil ratio is 8, the reaction pressure is 0.1 MPa, the reaction time is 2s, the atomized water vapor accounts for 1w% of the feed amount, and the catalyst is a conventional catalytic cracking catalyst.

[0045] In this step, the cracked diesel is mixed with the catalytic diesel for hydrotreating.

[0046] The mass ratio of the catalytic gasoline heavy fraction used as a gasoline blending component to the catalytic gasoline heavy fraction introduced into the second riser is 0.1:1. High-quality gasoline can be obtained, and high-value-added products can be obtained.

[0047] 4) The cracked gasoline is cut and fractionated to obtain a light fraction and a heavy fraction of cracked gasoline. The cut point of the cracked gasoline is 140°C. The light fraction of the cracked gasoline is pre-hydrogenated, aromatics are extracted, and aromatics are separated to obtain BTX and raffinate gasoline. The raffinate gasoline is used as a gasoline blending component, and BTX and high-quality gasoline are the final products.

[0048] In this step, the heavy fraction of cracked gasoline is introduced into the second riser of the double-riser catalytic cracking unit for cracking to obtain C6-C8 aromatics, thereby further improving the yield of high value-added products.

[0049] In this step, the reaction temperature of the pre-hydrogenation was 300 ° C, the hydrogen partial pressure was 2.5 MPa, the hydrogen / oil volume ratio was 300:1, and the volume space velocity was 1.5 h -1 The extraction solvent used for aromatics extraction from the light fraction of cracked gasoline was sulfolane. The mass ratio of the extraction solvent to the light fraction of cracked gasoline was 3:1. The top temperature of the extraction tower used for extraction was 130°C and the pressure was 1.1 MPa.

[0050] Example 2

[0051] A method for producing BTX and high-quality gasoline from low-quality heavy oil comprises the following steps:

[0052] 1) analyzing the properties of low-quality heavy oil and introducing the low-quality heavy oil into a heavy oil riser of a dual-riser catalytic cracking unit. Under optimized operating conditions, the reaction depth is rationally controlled to obtain catalytic gasoline, catalytic diesel, and other products. In this step, the low-quality heavy oil in the heavy oil riser of the dual-riser catalytic cracking unit has a reaction temperature of 550° C., a catalyst-to-oil ratio of 10, a reaction pressure of 0.4 MPa, a reaction time of 5 seconds, and atomized water vapor accounting for 8% by weight of the feed.

[0053] 2) Analyze the properties of FGA and determine the appropriate cut point. Cut and fractionate the FGA to obtain a FGA light fraction and a FGA heavy fraction. The FGA heavy fraction is divided into two parts. The FGA light fraction and a portion of the FGA heavy fraction are directly used as gasoline blending components.

[0054] In this step, the FCG gasoline is analyzed by distillation range, elemental composition, or hydrocarbon group composition. Based on the analytical data, a cut point of 75°C is determined, resulting in the enrichment of at least 95% by weight of aromatic hydrocarbons in the FCG gasoline into the FCG heavy fraction. The FCG gasoline is separated using a conventional fractionating tower operating under the following conditions: a feed temperature of 100°C, a bottom temperature of 200°C, a top temperature of 150°C, and a top pressure of 1 MPa. The FCG light fraction is located at the top of the fractionating tower, while the FCG heavy fraction is located at the bottom.

[0055] 3) The catalytic diesel is hydrogenated to obtain hydrogenated catalytic diesel, and the hydrogenated catalytic diesel and another part of the catalytic gasoline heavy fraction are introduced into the second riser of the dual riser catalytic cracking device to obtain cracking gasoline and cracking diesel; the reaction temperature of the catalytic diesel hydrogenation is 390°C, the hydrogen partial pressure is 10.0 MPa, the volume space velocity is 1.5h -1 , and the hydrogen / oil volume ratio is 800:1; the active metal in the hydrogenation catalyst is nickel, and the content of the active metal is 30%.

[0056] In this step, the reaction temperature of the hydrogenated catalytic diesel and the catalytic gasoline heavy fraction in the second riser of the dual riser catalytic cracking device is 650°C, the catalyst / oil ratio is 14, the reaction pressure is 0.4 MPa, the reaction time is 5s, the atomized water vapor accounts for 4w% of the feed amount, and the catalyst is a conventional catalytic cracking catalyst.

[0057] In this step, the cracking diesel is mixed with the catalytic diesel for hydrogenation.

[0058] The mass ratio of the catalytic gasoline heavy fraction used as a gasoline blending component to the catalytic gasoline heavy fraction introduced into the second riser is 20:1. High-quality gasoline can be obtained, and high-value-added products can be obtained.

[0059] 4) The cracking gasoline is cut and fractionated to obtain a cracking gasoline light fraction and a cracking gasoline heavy fraction, the cut point of the cracking gasoline is 150°C, the cracking gasoline light fraction is pre-hydrogenated, aromatics are extracted, and aromatics are separated to obtain BTX and raffinate gasoline, the raffinate gasoline is used as a gasoline blending component, and the BTX and high-quality gasoline are final products.

[0060] In this step, the cracking gasoline heavy fraction is introduced into the second riser of the dual riser catalytic cracking device for cracking to obtain C6-C8 aromatics, further improving the yield of high-value-added products.

[0061] In this step, the reaction temperature of the pre-hydrogenation is 420°C, the hydrogen partial pressure is 3.5 MPa, the hydrogen / oil volume ratio is 500:1, and the volume space velocity is 4h -1 . The extraction solvent used for the aromatics extraction of the cracking gasoline light fraction is sulfolane. The mass ratio of the extraction solvent to the cracking gasoline light fraction is 8:1, the overhead temperature of the extraction tower used for extraction is 190°C, and the pressure is 2.0 MPa.

[0062] Example 3

[0063] A method for producing BTX and high-quality gasoline from poor heavy oil, comprising the following steps:

[0064] 1) The inferior heavy oil is analyzed for its properties, and the inferior heavy oil is introduced into the heavy oil riser of the dual riser catalytic cracking unit, and under the optimized operating conditions, the reaction depth is properly controlled to obtain catalytic gasoline, catalytic diesel and other products. In this step, the reaction temperature of the inferior heavy oil in the heavy oil riser of the dual riser catalytic cracking unit is 500℃, the catalyst / oil ratio is 8, the reaction pressure is 0.3MPa, the reaction time is 3s, and the atomized water vapor accounts for 5w% of the feed amount.

[0065] 2) The catalytic gasoline is analyzed for its properties, and the appropriate cutting point is determined, and the catalytic gasoline is cut and fractionated to obtain catalytic gasoline light fraction and catalytic gasoline heavy fraction, and the catalytic gasoline heavy fraction is divided into two parts, and the catalytic gasoline light fraction and a part of the catalytic gasoline heavy fraction are directly used as gasoline blending components.

[0066] In this step, the analysis method of the catalytic gasoline is distillation range, elemental composition or hydrocarbon group composition, and the cutting point is determined to be 73℃ according to the analysis data, so that more than 95w% of the aromatics in the catalytic gasoline are enriched in the catalytic gasoline heavy fraction. The catalytic gasoline is separated by using a conventional fractionating column, and the operating conditions of the fractionating column are as follows: the feed temperature is 80℃, the bottom temperature is 120℃, the top temperature is 120℃, the top pressure is 0.5MPa, the catalytic gasoline light fraction is located at the top of the fractionating column, and the catalytic gasoline heavy fraction is located at the bottom of the fractionating column.

[0067] 3) The catalytic diesel is hydrotreated to obtain hydrotreated catalytic diesel, and the hydrotreated catalytic diesel and the other part of the catalytic gasoline heavy fraction are introduced into the second riser of the dual riser catalytic cracking unit at the same time to obtain cracked gasoline and cracked diesel; the reaction temperature of the catalytic diesel hydrotreating is 350℃, the hydrogen partial pressure is 8.0MPa, the volume space velocity is 1h -1 , the hydrogen / oil volume ratio is 500:1; the active metal in the hydrotreating catalyst is nickel, and the content of the active metal is 20%.

[0068] In this step, the reaction temperature of the hydrotreated catalytic diesel and the catalytic gasoline heavy fraction in the second riser of the dual riser catalytic cracking unit is 600℃, the catalyst / oil ratio is 10, the reaction pressure is 0.3MPa, the reaction time is 3s, the atomized water vapor accounts for 3w% of the feed amount, and the catalyst is a conventional catalytic cracking catalyst.

[0069] In this step, the cracked diesel is mixed with the catalytic diesel for hydrotreating.

[0070] The mass ratio of the catalytic gasoline heavy fraction used as a gasoline blending component to the catalytic gasoline heavy fraction introduced into the second riser is 10:1. High-quality gasoline can be obtained, and high-value-added products can be obtained.

[0071] 4) The cracked gasoline is cut and fractionated to obtain a cracked gasoline light fraction and a cracked gasoline heavy fraction, the cut point of the cracked gasoline is 145°C, the cracked gasoline light fraction is pre-hydrogenated, aromatic hydrocarbon extracted and separated to obtain BTX and raffinate gasoline, the raffinate gasoline is used as a gasoline blending component, the BTX and high-quality gasoline are final products.

[0072] In this step, the cracked gasoline heavy fraction is introduced into the second riser of the dual-riser catalytic cracking device to be cracked to obtain C6-C8 aromatic hydrocarbons, further improving the yield of high-value-added products.

[0073] In this step, the reaction temperature of the pre-hydrogenation is 360°C, the hydrogen partial pressure is 3 MPa, the hydrogen / oil volume ratio is 400:1, and the volume space velocity is 2.5 h -1 When the cracked gasoline light fraction is subjected to aromatic hydrocarbon extraction, the extraction solvent used is sulfolane. The mass ratio of the extraction solvent to the cracked gasoline light fraction is 5:1, the overhead temperature of the extraction column used for extraction is 150°C, and the pressure is 1.5 MPa.

[0074] In order to verify the advantages of the present application compared with the prior art, the following examples 4-6 and comparative examples are carried out. The properties of the heavy oil used in examples 4-6 are shown in Table 1, and the specific process flow used in examples 4-6 is shown in Table 2: Figure 1

[0075] 1) The inferior heavy oil is introduced into the heavy oil riser of the dual-riser catalytic cracking device, and under optimized operating conditions, the reaction depth is reasonably controlled to obtain catalytic gasoline, catalytic diesel and other products;

[0076] 2) The properties of the catalytic gasoline are analyzed to determine the appropriate cut point, and the catalytic gasoline is cut and fractionated to obtain a catalytic gasoline light fraction and a catalytic gasoline heavy fraction. The catalytic gasoline heavy fraction is divided into two parts, and the catalytic gasoline light fraction and a part of the catalytic gasoline heavy fraction are directly used as a gasoline blending component.

[0077] 3) The catalytic diesel is hydrofinished to obtain hydrofinished catalytic diesel, and the hydrofinished catalytic diesel and the other part of the catalytic gasoline heavy fraction are introduced into the second riser of the dual-riser catalytic cracking device to obtain cracked gasoline and cracked diesel; the cracked diesel is mixed with the catalytic diesel for hydrofining.

[0078] 4) The cracked gasoline is cut and fractionated to obtain a cracked gasoline light fraction and a cracked gasoline heavy fraction, the cracked gasoline light fraction is pre-hydrogenated, aromatic hydrocarbon extracted and separated to obtain BTX and raffinate gasoline, the raffinate gasoline is used as a gasoline blending component, the BTX and high-quality gasoline are final products, and the cracked gasoline heavy fraction is introduced into the second riser of the dual-riser catalytic cracking device to be cracked.

[0079] ​Examples 4-6 used different operating conditions (main operating conditions are shown in Table 2, other process parameters not specified, should be understood as known or should be known by those skilled in the art as parameters required to maintain the operation of the equipment), and finally obtained product distribution, product distribution as shown in Table 3, gasoline properties as shown in Table 4.

[0080] Comparative Example

[0081] The comparative example used inferior heavy oil with the same properties as the inferior heavy oil of Examples 4-6, as shown in Table 1, and used the process flow shown in Table 2: the inferior heavy oil passed through the heavy oil riser to obtain catalytic gasoline and catalytic diesel; the catalytic gasoline was cut and fractionated to obtain catalytic gasoline light fraction and catalytic gasoline heavy fraction, wherein the catalytic gasoline light fraction was used as a gasoline blending component; the catalytic diesel was cut and fractionated to obtain catalytic diesel heavy fraction and catalytic diesel light fraction, and the catalytic diesel heavy fraction was subjected to hydrofining to obtain hydrofined catalytic diesel, and the hydrofined catalytic diesel, catalytic diesel light fraction and catalytic gasoline heavy fraction were introduced into the second riser for reaction to obtain cracking gasoline and cracking diesel; the cracking gasoline was saturated by hydrogenation and then cut and fractionated to obtain light fraction and heavy fraction, the light fraction was used as a gasoline blending component, and the heavy fraction entered the aromatics complex for aromatics extraction to obtain raffinate gasoline, heavy aromatics and C6-C9 light aromatics, the raffinate gasoline and heavy aromatics were used as gasoline blending components, and the C6-C9 light aromatics were the final product. Figure 2

[0082] The main operating conditions in the process flow are shown in Table 2, the product distribution obtained is shown in Table 3, and the gasoline properties are shown in Table 4.

[0083] Table 1 Properties of inferior heavy oil

[0084] Table 2 Main operating conditions

[0085] Table 3 Product distribution

[0086] Result analysis: As shown in Table 3, the C6-C8 product yield of Examples 4-6 was greater than that of the comparative example, and the olefin content in the gasoline product was significantly lower than that of the comparative example, and at the same time, the octane number in Examples 4-6 was also significantly improved.

[0087] ​The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing BTX and high-quality gasoline from low-quality heavy oil, characterized in that: The following steps are involved: 1) Introducing low-quality heavy oil into the heavy oil riser of a double-rise catalytic cracking unit to obtain catalytic gasoline, catalytic diesel and other products; 2) FG gasoline is cut and fractionated to obtain a FG gasoline light fraction and a FG gasoline heavy fraction. The FG gasoline heavy fraction is divided into two parts. The FG gasoline light fraction and a portion of the FG gasoline heavy fraction are directly used as gasoline blending components; 3) Hydrofining the catalytic diesel to obtain hydrogenated catalytic diesel, and simultaneously introducing the hydrogenated catalytic diesel and another portion of the catalytic gasoline heavy fraction into the second riser of a double-riser catalytic cracking unit to obtain cracked gasoline and cracked diesel; 4) The cracked gasoline is cut and fractionated to obtain a light fraction and a heavy fraction of cracked gasoline. The light fraction of cracked gasoline is subjected to aromatic extraction and separation to obtain BTX and raffinate gasoline. The raffinate gasoline is used as a gasoline blending component, and BTX and high-quality gasoline are the final products.

2. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: The mass ratio of the catalytic gasoline heavy fraction used as a gasoline blending component to the catalytic gasoline heavy fraction introduced into the second riser is 0.1 to 20:

1.

3. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 1), the reaction temperature of the inferior heavy oil in the heavy oil riser of the double riser catalytic cracking unit is 480-550° C., the catalyst-to-oil ratio is 4-10, the reaction pressure is 0.1-0.4 MPa, the reaction time is 2-5 seconds, and the atomized water vapor accounts for 3-8w% of the feed amount.

4. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 2), the cutting point of the catalytic gasoline cutting fractionation is 70-75° C., so that more than 95% of the aromatic hydrocarbons in the catalytic gasoline are enriched in the catalytic gasoline heavy fraction.

5. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 3), the reaction temperature of the catalytic diesel hydrofining is 320-390°C, the hydrogen partial pressure is 5.0-10.0 MPa, and the volume space velocity is 0.5-1.5 h -1 , the hydrogen / oil volume ratio is 300~800:

1.

6. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 3), the active metal in the catalyst for hydrorefining is one or more of nickel, cobalt and tungsten.

7. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 3), the reaction temperature of the hydrogenated catalytic diesel and the catalytic gasoline heavy fraction in the second riser of the double-riser catalytic cracking unit is 550-650° C., the catalyst-oil ratio is 8-14, the reaction pressure is 0.1-0.4 MPa, the reaction time is 2-5 s, and the atomized water vapor accounts for 1-4 w% of the feed amount.

8. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 3), the cracked diesel is mixed with the catalytic diesel and subjected to hydrofining.

9. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: In the step 4), the cutting point of the cracked gasoline cutting fractionation is 140-160°C.

10. The method for producing BTX and high-quality gasoline from low-quality heavy oil according to claim 1, wherein: The extraction solvent used for extracting aromatics from the light fraction of cracked gasoline in step 4) is one or more of sulfolane, dimethyl sulfoxide, dimethylformamide, N-methylmethylpyrrolidone, N-formylmorpholine, triethylene glycol, tetraethylene glycol, pentaethylene glycol, methanol, and acetonitrile.

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