Method for simultaneously producing low-sulfur coke and high-sulfur coke

Abstract

The invention discloses a method for simultaneously producing low-sulfur coke and high-sulfur coke, which is characterized in that on the basis of the original total processing flow of the whole plant, from crude oil processing, an atmospheric and vacuum distillation unit flexibly switches to process inferior crude oil with high sulfur content and high and low metal content according to the inventory of vacuum residuum with different properties produced by the atmospheric and vacuum distillation unit. The existing process technology of a residual oil hydrogenation device is utilized, hydrogenated residual oil with high and low carbon residue values is flexibly switched to be produced by adjusting raw materials, reaction parameters and the like, and the hydrogenated residual oil with the high carbon residue value is a raw material required by a delayed coking device to produce low-sulfur coke. The delayed coking device utilizes the existing process flow for producing high-sulfur petroleum coke, takes high-carbon-residue-value hydrogenated residual oil as a main raw material, and produces a low-sulfur coke product by adjusting the ratio of oil slurry raw materials. According to the method, the existing total processing flow of the whole plant is kept unchanged, and the low-sulfur petroleum coke meeting the standard is produced by fully utilizing the existing process technologies of the residual oil hydrogenation device and the delayed coking device.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum refining, and relates to a method for producing both low-sulfur coke and high-sulfur coke, and specifically relates to a method for switching a constant pressure reduction unit to process high-sulfur, high- and low-metal content inferior crude oils, a method for flexibly switching a residual oil hydrogenation unit to produce high- and low-carbon residue value hydrogenated residual oils, and a method for flexibly switching a delayed coking unit to produce high- and low-sulfur petroleum cokes. Background Art

[0002] Petroleum coke is a byproduct of the delayed coking process using residual oil and heavy oil as raw materials during the petroleum refining process. Petroleum coke can be classified into high-sulfur coke and low-sulfur coke according to the sulfur content. The sulfur content of petroleum coke is less than 3.0% and is called low-sulfur coke, while that of petroleum coke greater than 3.0% is called high-sulfur coke.

[0003] Low-sulfur coke is mainly used for ordinary graphite electrodes. The end application of graphite electrodes is the short-process electric furnace of steel, which is used for low- and medium-end lithium battery negative electrodes, and the end application is new energy vehicles and energy storage. It can also be used for high-end preparatory anodes and other carbon products. High-sulfur coke is mainly used as fuel and reducing agent. The downstream of fuel includes glass factories, power plants, cement plants, etc. It is mainly used as a reducing agent to smelt silicon, such as making calcium carbide and silicon carbide. The sulfur content of high-sulfur coke is too high. During the production process of electrolytic aluminum enterprises, SO2 emissions are high and pollution is easily exceeded. In addition, SO2 will corrode equipment and increase the resistivity of the anode. High-sulfur coke is rarely used in prebaked anodes in China.

[0004] The sulfur content of petroleum coke can be reduced by controlling the sulfur content during petroleum refining, but since refining is mainly for obtaining oil and gas, it is difficult for enterprises to modify the process to obtain low-sulfur residual oil. Therefore, in theory, the sulfur content of residual oil can be reduced, but it is difficult for enterprises to implement it. At present, the delayed coking process with low investment, strong raw material adaptability and mature process is mostly adopted in China, and it is difficult for coking process to reduce the sulfur content of petroleum coke. Petroleum coke desulfurization can also be carried out after the petroleum coke is generated. The main methods include high-temperature calcination desulfurization, hydrodesulfurization, solvent extraction desulfurization, etc. The cost of high-temperature desulfurization is relatively low and it is widely used by enterprises. High-temperature desulfurization requires heating the petroleum coke to above 1400℃ for obvious desulfurization effect. It needs to be heated to 1700-2300℃ to produce petroleum coke with a sulfur content of about 0.1%. High-temperature desulfurization to produce low-sulfur coke requires high-temperature resistant materials, especially the production of low-sulfur coke, which has high cost. In addition, the true density, porosity and reactivity of petroleum coke after high-temperature calcination are all deteriorated. The subsequent graphitization may affect the negative electrode material produced.

[0005] CN114540059A discloses a combined process for producing needle coke from heavy oil, a combined system and the needle coke produced by the combined process, the combined process comprising: a hydrogenation process, using heavy oil as raw material, performing hydrogenation treatment to remove the coke-prone components to obtain hydrogenated oil; a component cutting process, separating the hydrogenated oil into heavy components and light components; an electrostatic desolidification process, passing the light components into an electrostatic desolidification device to remove ash to obtain deashed oil; a solvent extraction process, separating the deashed oil into an extracted oil component and a raffinate oil component; and a delayed coking process, subjecting the extracted oil to delayed coking treatment to obtain needle coke. The combined process of the present invention can produce high-quality needle coke with a low thermal expansion coefficient. This process is complex and can only produce needle coke products.

[0006] CN103102986A discloses a combined process of residual oil hydroprocessing and delayed coking, which is to mix residual oil, coking wax oil and hydrogen together, enter a hydroprocessing unit for reaction in the presence of a catalyst, separate the reaction product after hydrogenation, wherein the hydrogenated residual oil and the separated vacuum gas oil are mixed together or enter a delayed coking unit together with other conventional raw materials, separate the coking product, wherein the coking gas oil is all circulated to the residual oil hydroprocessing unit. The method improves the product structure of the combined process, does not produce coking gas oil products, can produce the maximum amount of light oil products, and obtain high-quality needle coke. At the same time, the method can effectively reduce the generation of foam in the coking tower and delay the coking tendency of the coking heating furnace.

[0007] CN114540059A and CN103102986A both relate to a combined process, method and system for producing needle coke, wherein the processes and methods involved are complex, technically difficult, and can only produce needle coke products; CN114540059A and CN103102986A both obtain needle coke products by processing heavy oil, and do not mention the system balance problem of heavy oil in the production process.

[0008] CN111892950A discloses a method for producing needle coke by a combined process, the method is as follows: the raw oil is fractionated into light distillate oil and heavy distillate oil by a vacuum distillation device, the heavy distillate oil exits the device, the light distillate oil enters a hydrotreating device, the liquid phase product obtained after hydrotreating is separated into at least hydrogenated light distillate oil and hydrogenated heavy distillate oil by a fractionation device, the hydrogenated heavy distillate oil is heated by a heating furnace a as a mesophase material and then enters a coke tower, the coking gas generated by the coke tower is passed through a coking fractionation tower to obtain coking wax oil, the coking wax oil and the hydrogenated light distillate oil are mixed as a coke pulling material and heated by a heating furnace b and then enter a coke tower, the coke tower sequentially completes the mesophase forming stage and the coke pulling stage to obtain needle coke. The method can continuously produce high-quality needle coke with stable performance.

[0009] CN108998060A discloses a new process for producing low-sulfur coke, comprising: mixing residual oil with an oxidant, subjecting the mixture to microwave pretreatment and coking treatment to prepare a low-sulfur coke. The present invention starts from the raw materials for preparing petroleum coke, combines the characteristics of chemical oxidation and selective heating of microwave pretreatment, and proposes a new process for preparing low-sulfur petroleum coke by microwave pretreatment oxidation in one step. The process can realize the production of low-sulfur coke in one step, with low investment, quick effect, no pollution, and can realize clean production.

[0010] CN113122329A discloses a method and system for co-producing needle coke and low-sulfur coke, wherein the method feeds the refined oil obtained by hydrogenating the catalytic oil slurry into a vacuum distillation system, and separates the light fraction, middle distillate oil and heavy distillate oil; the oil and gas products of the middle distillate oil after coking reaction enter the stabilizing tower, and after separation, non-condensable gas, distillate oil and tower bottom oil are obtained; the tower bottom oil is divided into two paths after buffering, one of which returns to the stabilizing tower after temperature adjustment, and the other enters the fractionation system; the light fraction and heavy distillate oil are fed to a low-sulfur petroleum coke production device, and the reaction oil and gas products enter the fractionation system for separation to obtain gas, light oil and wax oil. The method uses part of the components in the catalytic oil slurry to produce needle coke, and the remaining components are used to produce low-sulfur petroleum coke, and the production method maximizes the raw material conversion rate.

[0011] The paper "Research on the Combined Process of Residue Hydrogenation-Delayed Coking for the Production of Low-Sulfur Petroleum Coke" (Liu Tao et al., Petroleum Refining and Chemical Industry, 2021-12-12) investigated the effects of hydrogenation process conditions on the hydrodesulfurization reaction of high-sulfur residue oil. The results show that increasing the reaction temperature and reducing the space velocity are beneficial to improving the activity of the hydrodesulfurization reaction; reducing the reaction temperature, reducing the hydrogen partial pressure and increasing the space velocity are beneficial to improving the hydrodesulfurization selectivity. When achieving the same desulfurization rate, increasing the reaction temperature can adopt a higher reaction space velocity, thereby reducing the processing cost of residue hydrogenation. The research results of the combined process of residue hydrogenation-delayed coking show that as the depth of hydrodesulfurization increases, the remaining sulfur-containing compounds in the hydrogenated residue are more inclined to generate petroleum coke; the combined process can significantly reduce the sulfur mass fraction of petroleum coke to below 3.0%, meeting the index requirements of low-sulfur coke; compared with the delayed coking process alone, the combined process can produce more and better high-value products.

[0012] The above methods and papers can produce low-sulfur coke products, but they have the disadvantages of complex process, single product, inflexible production, etc. In short, there is currently a lack of methods that deeply link low-quality crude oil processing, residue oil hydrotreating units, delayed coking units, heavy oil catalytic cracking units and heavy oil inventory to achieve flexible switching of low-sulfur coke and high-sulfur coke production. Summary of the invention

[0013] In order to solve the shortcomings of the prior art, the present invention provides a method for producing both low-sulfur coke and high-sulfur coke. This method does not affect the overall processing flow of the whole plant, crude oil processing and device operating technology, parameters, etc. from crude oil processing to the production of petroleum coke products, and has the advantages of flexibility, periodicity and efficient production.

[0014] The overall concept of the present invention is: on the basis of the original overall process of the whole plant, starting from crude oil processing, the atmospheric and vacuum unit can flexibly switch to process high-sulfur, high-metal content and low-metal content inferior crude oil according to the inventory of vacuum residue oil of different properties produced by it. By utilizing the existing process technology of the residue oil hydrogenation unit, by adjusting the raw materials, reducing the reactor bed temperature, increasing the circulating hydrogen flow rate, reducing the new hydrogen flow rate, etc., it is possible to flexibly switch to produce high and low residual carbon value hydrogenated residue oil. The high residual carbon value hydrogenated residue oil is the raw material required for the delayed coking unit to produce low-sulfur coke. The delayed coking unit utilizes the existing process flow for producing high-sulfur petroleum coke, takes high residual carbon value hydrogenated residue oil as the main raw material, and produces low-sulfur coke products by adjusting the oil slurry raw material ratio. This technology not only keeps the existing overall processing flow of the whole plant unchanged, but also makes full use of the existing process technology of the residue oil hydrogenation unit and the delayed coking unit to produce low-sulfur petroleum coke that meets the standards.

[0015] The technical solution of the present invention is:

[0016] A method for producing both low-sulfur coke and high-sulfur coke comprises the following steps:

[0017] S1, inferior crude oil processing and heavy oil balance stage

[0018] S1.1, the atmospheric vacuum unit processes high-sulfur, high-metal content inferior crude oil, and the vacuum residue B produced is stored in the vacuum residue B raw material tank of the delayed coking unit, and the storage capacity reaches 90wt.%, then the atmospheric vacuum unit switches to process high-sulfur, low-metal content inferior crude oil, and the vacuum residue A produced is stored in the vacuum residue A raw material tank of the residue oil hydrogenation unit, and the storage capacity reaches 90wt.%, then the atmospheric vacuum unit switches again to process high-sulfur, high-metal content inferior heavy oil. The mixed heavy oil produced during the atmospheric vacuum unit processing inferior crude oil is always used as part of the residue oil hydrogenation feedstock.

[0019] S1.2, the residue oil hydrogenation unit and the delayed coking unit are based on the inventory of the corresponding vacuum residue oil A and vacuum residue oil B. If the vacuum residue oil A raw material of the residue oil hydrogenation unit is used up to 20wt.% of the storage tank inventory, it will be fed back to the upstream atmospheric and vacuum vacuum unit to switch to processing high-sulfur, low-metal content inferior crude oil; if the vacuum residue oil B raw material of the delayed coking unit is used up to 20wt.% of the storage tank inventory, it will be fed back to the upstream atmospheric and vacuum vacuum unit to switch to processing high-sulfur, high-metal content inferior crude oil.

[0020] Furthermore, the type of low-quality crude oil that the atmospheric and vacuum distillation unit switches to process needs to be determined based on the existing crude oil varieties, the inventory of vacuum residue raw materials in the residue hydrotreating and delayed coking units, and the processing plans of the two units.

[0021] S2, the residue oil hydrotreating unit switches to produce high and low carbon residue value hydrotreating residue oil stage

[0022] S2.1, combined with the inventory of vacuum residue A raw material of the residue hydrogenation unit and the properties of vacuum residue A raw material, the residue hydrogenation unit uses the existing process flow to switch to produce high and low carbon residue value hydrogenated residues. In the process of switching to produce high and low carbon residue value hydrogenated residues, the residue hydrogenation unit mainly controls the proportion of vacuum residue A raw material to finally obtain high carbon residue value (above 5.0wt.%) and low carbon residue value (less than 5.0wt.%) hydrogenated residues while keeping the processing capacity of the unit and the proportion of mixed heavy oil raw materials unchanged.

[0023] S2.2, use GB / T 17144-2021 analysis method to evaluate the carbon residue value of vacuum residue A raw material. If the carbon residue value of vacuum residue A raw material is less than 20wt.% and the inventory of low carbon residue value hydrogenated residue raw material is at or below 20wt.% of the storage tank storage capacity, the residue hydrotreating unit will produce low carbon residue value hydrogenated residue oil at this stage. If the carbon residue value of vacuum residue A raw material is greater than 20wt.% and the inventory of high carbon residue value hydrogenated residue raw material is at or below 20% of the storage tank storage capacity, high carbon residue value hydrogenated residue oil will be produced at this stage.

[0024] Furthermore, in combination with the processing plan, before the delayed coking unit produces low-sulfur coke products, high-carbon-value hydrogenated residue oil is prepared in advance, and the residue oil hydrogenation unit in other stages continuously produces low-carbon-value hydrogenated residue oil as the raw material for the heavy oil catalytic cracking unit.

[0025] Furthermore, the proportion of vacuum residue A in the raw material of the residue hydrogenation unit is increased to more than 39.0wt.%, and the proportion of mixed heavy oil is correspondingly reduced to less than 61.0wt.%. The two raw materials enter the residue hydrogenation reaction system, and then the reactor catalyst bed temperature is controlled at 360-375℃, and the circulating hydrogen flow rate is controlled at 240000-250000Nm 3 / h, the flow rate of new hydrogen is controlled at 44000-48000Nm 3 / h, to obtain a high carbon residue value hydrogenated residue oil with a carbon residue value of more than 5.0wt.%.

[0026] S3, delayed coking unit switching to produce high and low sulfur petroleum coke products

[0027] S3.1, based on the storage capacity of high carbon residue value hydroprocessing residue and vacuum residue B raw material storage tanks, evaluate the inventory status of high carbon residue value hydroprocessing residue required for the delayed coking unit to produce low sulfur petroleum coke and vacuum residue B required for the production of high sulfur petroleum coke.

[0028] S3.2. When the inventory of vacuum residue B raw material reaches 20wt.% or less of the storage capacity of the tank, and the inventory of high carbon residue hydrogenated residue raw material reaches 90wt.% or more of the storage capacity of the tank, the delayed coking unit produces low-sulfur petroleum coke products until the inventory of high carbon residue desulfurized residue oil drops to 20wt.% of the storage capacity of the tank, and the inventory of vacuum residue B raw material reaches 90wt.% or more of the storage capacity of the tank, and the delayed coking unit switches to produce high-sulfur petroleum coke products.

[0029] Preferably, the production time and output of low-sulfur coke in the delayed coking unit are extended by controlling the ratio of high carbon value hydrogenated residue oil and catalytic oil slurry raw materials in the delayed coking unit.

[0030] The present invention comprises at least two inferior crude oils of different properties, vacuum residue oil tanks for storing two different properties, and desulfurized residue oil tanks for storing two different properties. The upper limit of the storage capacity of the storage tanks is 90wt.%, and the lower limit is 20wt.%. The devices and the devices and the tank areas are all connected systems, and the switching production plan of the devices is a continuous production process.

[0031] In the present invention, the residue oil hydrogenation unit and the delayed coking unit switch to produce products of different properties. On the basis of the storage capacity of the corresponding raw material storage tank, it is evaluated whether the corresponding raw material inventory of the residue oil hydrogenation unit or the delayed coking unit is at the upper limit of the storage capacity of the corresponding storage tank. If the storage tank is in a state where the storage material is at the upper limit, the device for producing the material must be switched to produce another material.

[0032] When the inventory of high carbon residue hydroresidue oil required for the delayed coking unit to produce low-sulfur coke is at the upper limit of its storage tank capacity, the delayed coking unit can switch to produce low-sulfur petroleum coke, otherwise it cannot produce low-sulfur coke petroleum coke. At the same time, when the high carbon residue hydroresidue oil produced by the residue hydrogenation unit corresponding to the production of hydroresidue oil reaches the upper limit of its storage tank capacity, it must switch to produce low carbon residue hydroresidue oil. At this time, the atmospheric vacuum unit must process high-sulfur and low-metal content inferior crude oil to produce vacuum residue oil for the raw materials required for residue hydrogenation to produce low carbon residue value. If the residue hydrogenation unit switches to produce high carbon residue hydroresidue oil, the atmospheric vacuum unit switches to process high-sulfur and high-metal content inferior crude oil to produce vacuum residue oil for the residue hydrogenation unit to produce high carbon residue hydroresidue oil, and the high carbon residue hydroresidue oil is then supplied to the delayed coking unit to produce low-sulfur petroleum coke. This process has the characteristics of cyclicity and reciprocity.

[0033] The beneficial effects of the present invention include:

[0034] The present invention can utilize the existing production processes and procedures of the residual oil hydrogenation unit and the delayed coking unit. Starting from crude oil processing, the atmospheric and vacuum devices can flexibly switch to process high-sulfur, high-metal content and low-metal content inferior crude oil according to the inventory of vacuum residual oil of different properties produced by them. By utilizing the existing process technology of the residual oil hydrogenation unit, by increasing the proportion of vacuum residual oil A to more than 39.0wt.%, correspondingly reducing the proportion of mixed heavy oil to less than 61.0wt.%, and at the same time reducing the reactor bed temperature to 360-375℃ and increasing the circulating hydrogen flow rate to 240000-250000Nm 3 / h, reduce the new hydrogen flow rate to 44000-48000Nm 3 / h, high carbon residue value hydrogenated residue oil can be obtained. Otherwise, the residue oil hydrogenation unit cannot produce high carbon residue value hydrogenated residue oil, and the balance of the heavy oil system will also be broken, which will directly lead to the delayed coking unit having no high carbon residue hydrogenated residue oil raw material to produce low-sulfur petroleum coke products. The delayed coking unit uses the existing process flow for producing high-sulfur petroleum coke, takes high carbon residue value hydrogenated residue oil as the main raw material, and produces low-sulfur coke products by adjusting the oil slurry raw material ratio. This method not only keeps the existing overall processing flow of the whole plant unchanged, but also makes full use of the existing process technology of the residue oil hydrogenation unit and the delayed coking unit to produce low-sulfur petroleum coke that meets the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Flow chart for switching the residue oil hydrotreating unit to produce high and low residual carbon value hydrotreating residue oil.

[0036] Figure 2 Flow chart for switching the delayed coking unit to produce high- and low-sulfur petroleum coke products.

[0037] Figure 3 is a flow chart of the method of the present invention.

[0038] Figure 4 A schematic diagram of the method of the present invention.

[0039] The symbols in the accompanying drawings are described as follows:

[0040] 1. Low-quality crude oil with high sulfur and low metal content;

[0041] 2. Atmospheric and vacuum device;

[0042] 3. Pipeline for vacuum residue A to enter the residue hydrogenation raw material tank;

[0043] 4. Pipeline for mixed heavy oil to feed residual oil hydrogenation raw material tank;

[0044] 5. Vacuum residue oil B enters delayed raw material tank pipeline;

[0045] 6. Delayed coking unit vacuum residue oil B raw material tank;

[0046] 7. Vacuum residue A raw material tank of residue oil hydrogenation unit;

[0047] 8. Residue oil hydrogenation unit mixed heavy oil raw material tank;

[0048] 9. Inlet of residue oil hydrogenation reaction system;

[0049] 10. Residue oil hydrogenation reaction system;

[0050] 11. Pipeline for low carbon residue value hydrogenated residue oil to enter heavy oil catalytic cracking raw material tank;

[0051] 12. Pipeline for high carbon residue value hydrogenated residue oil to enter delayed coking raw material tank;

[0052] 13. Low carbon residue value hydrogenation residue oil tank area;

[0053] 14. High carbon residue value hydrogenation residue oil tank area;

[0054] 15. Pipeline for low carbon residue value hydrogenated residue oil to enter heavy oil catalytic cracking unit;

[0055] 16. Pipeline for high carbon residue value hydrogenated residue oil to enter delayed coking unit;

[0056] 17. Low-quality crude oil with high sulfur and high metal content;

[0057] 18. Catalytic oil slurry raw materials;

[0058] 19. Delayed coking reaction system inlet;

[0059] 20. Delayed coking reaction system;

[0060] 21. Low sulfur petroleum coke;

[0061] 22. High sulfur petroleum coke. DETAILED DESCRIPTION

[0062] Example 1

[0063] Step 1

[0064] S1.1, according to the inventory of vacuum residue A and B raw materials of different properties, the high-sulfur, low-metal content inferior crude oil 1 enters the atmospheric vacuum unit 2, the production mixed heavy oil enters the residue hydrogenation raw material tank pipeline 4 and enters the residue hydrogenation unit mixed heavy oil raw material tank 8, the production vacuum residue A enters the residue hydrogenation unit vacuum residue A raw material tank 7 through the residue hydrogenation raw material tank pipeline 3. The high-sulfur, high-metal content inferior crude oil 17 enters the atmospheric vacuum unit 2, the production vacuum residue B enters the delayed coking unit vacuum residue B raw material tank 6 through the vacuum residue B delayed raw material tank pipeline 5.

[0065] S1.2. According to the inventory of hydrotreated residue oil raw materials of different properties, evaluate the switching of production of high and low carbon value hydrotreated residue oils. The low carbon value hydrotreated residue oil produced will enter the low carbon value hydrotreated residue oil tank area 13 via the low carbon value hydrotreated residue oil into heavy oil catalytic cracking raw material tank pipeline 11. Subsequently, the low carbon value hydrotreated residue oil will enter the heavy oil catalytic cracking unit via the low carbon value hydrotreated residue oil into heavy oil catalytic cracking unit pipeline 15 for processing.

[0066] Step 2

[0067] S2.1, the high carbon value hydrogenated residue oil produced by the residue oil hydrogenation unit enters the high carbon value hydrogenated residue oil tank area 14 through the high carbon value hydrogenated residue oil into delayed coking raw material tank pipeline 12, and then the high carbon value hydrogenated residue oil is sent to the delayed coking unit for processing through the high carbon value hydrogenated residue oil into the delayed coking unit pipeline 16.

[0068] S2.2, increase the proportion of vacuum residue A in the raw material of the residue hydrogenation unit to more than 39.0wt.%, and correspondingly reduce the proportion of mixed heavy oil to less than 61.0wt.%. The two raw materials enter the residue hydrogenation reaction system 10, control the reactor catalyst bed temperature at 360-375℃, and control the circulating hydrogen flow rate at 240000-250000Nm 3 / h, new hydrogen flow control 44000-48000Nm 3 / h (the control temperature of low carbon residue hydroprocessing residue oil is 371-386℃, the circulating hydrogen flow rate is 235000-248000Nm 3 / h, new hydrogen flow control 44500-56500Nm 3 / h) to obtain high carbon residue value hydrogenated residue oil (carbon residue value above 5.89wt.%) which enters high carbon residue value hydrogenated residue oil tank area 14 and is used as a raw material for producing low sulfur petroleum coke in a coking unit.

[0071] The residue oil hydrotreating unit switches from producing low carbon value hydrotreating residue oil to high carbon value hydrotreating residue oil. The switching production process is adjusted in a step-by-step manner under the premise of maintaining stable production of the unit, that is, under the premise of maintaining the feed amount of the unit unchanged, by reducing the mixed heavy oil and correspondingly increasing the vacuum residue A, the proportion is finally adjusted to produce high carbon value hydrotreating residue oil. The changes in the properties of the raw materials during the switching process are shown in Table 1.

[0072] Step 3

[0073] S3.1 Assess the inventory status of high carbon residue hydroprocessing residue and vacuum residue raw materials.

[0074] S3.2, when the delayed coking unit is in accordance with the production plan and the vacuum residue B raw material is in a high inventory state, the vacuum residue B (ratio 78wt.%) and the catalytic oil slurry raw material 18 (ratio 22wt.%) enter the coking unit reaction system 20 through the delayed coking reaction system inlet 19 to obtain high-sulfur petroleum coke 22.

[0075] S3.3, the delayed coking unit produces low-sulfur petroleum coke with high-carbon value hydrogenated residue oil as the main raw material. When the high-carbon value hydrogenated residue oil raw material is in a high inventory state, the delayed coking unit uses the high-carbon value hydrogenated residue oil raw material (above 58wt.%) from the high-carbon value hydrogenated residue oil tank area 14 and the catalytic oil slurry raw material 18 (below 42wt.%) through the delayed coking reaction system inlet 19 into the coking unit reaction system 20 to obtain low-sulfur petroleum coke 21.

[0076] The delayed coking unit switches from producing high-sulfur petroleum coke 22 to low-sulfur petroleum coke 21. The switching production process is adjusted in a step-by-step manner under the premise of maintaining stable production of the unit, that is, under the premise of maintaining the feed amount of the unit unchanged, by reducing the vacuum residue oil until it is completely stopped, correspondingly increasing the catalytic oil slurry 18 and the high carbon residue value hydrogenated residue oil to meet the production requirements of low-sulfur petroleum coke 21. The main properties of the raw materials of the delayed coking unit are shown in Table 2, and the changes in the properties of the raw materials when switching from high-sulfur petroleum coke 22 to low-sulfur petroleum coke 21 are shown in Table 3.

[0077] Through the raw material inventory of the residue oil hydrotreating unit and the delayed coking unit, the switching of different crude oil processing schemes is evaluated. In the process of switching to produce high and low residual carbon value hydrotreating residue oil and switching to produce high and low sulfur petroleum coke products, the raw material inventory of mixed heavy oil, vacuum residue oil, high residual carbon value hydrotreating residue oil, low residual carbon value hydrotreating residue oil and catalytic oil slurry is always sufficient for the normal production of the catalytic cracking unit, residue oil hydrotreating unit and delayed coking unit. The heavy oil inventory balance is shown in Table 4.

[0078] Table 1 Changes in properties of residual oil hydrogenation feedstock adjustment

[0079]

[0080] Table 2 Main properties of delayed coking unit raw materials

[0081]

[0082] Table 3 Changes in raw material ratio and sulfur content of petroleum coke in delayed coking unit

[0083]

[0084] Table 4 Heavy oil inventory balance

[0085]

[0086]

[0087] Comparative Example

[0088] The overall production process of this comparative example is basically consistent with the overall production process in the implementation, and the focus is on explaining the impact of changes in a certain link on the entire process.

[0089] Step 1

[0090] S1.1, the atmospheric and vacuum unit processes low-quality crude oil with high sulfur and low metal content, and the residue oil hydrogenation unit increases the proportion of vacuum residue oil A in the raw material to below 30wt.%, and correspondingly reduces the proportion of mixed heavy oil to above 70wt.%. The two streams of raw materials enter the residue oil hydrogenation reaction system 10 to obtain low residual carbon value hydrogenated residue oil (residual carbon value below 4.0wt.%), which enters the low residual carbon value hydrogenated residue oil tank area 13 as the raw material for the heavy oil catalytic cracking unit.

[0091] Step 2

[0092] S2.1, during this process, the proportion of vacuum residue A raw material in the residue hydrogenation unit decreases, resulting in the inventory of vacuum residue A raw material remaining in an increasing state until the inventory reaches the upper limit of the storage capacity of the storage tank. The vacuum unit switches to processing high-sulfur, high-metal content inferior crude oil. At this time, the residue hydrogenation needs to switch to producing high-carbon value hydrogenated residue oil. The vacuum residue B still needs to be sent to the residue hydrogenation unit for processing, and the residue hydrogenation unit keeps the ratio of vacuum residue B to mixed heavy oil raw materials unchanged. The properties of the produced hydrogenated residue are shown in Table 5 below.

[0093] Step 3

[0094] S3.1, the hydrogenated residue oil produced by the above-mentioned S2.1 residue oil hydrogenation unit is used as the raw material of the delayed coking unit. While the delayed coking unit maintains the production ratio of low-sulfur petroleum coke raw material, the hydrogenated residue oil raw material (ratio above 58wt.%) and the catalytic oil slurry raw material 18 (ratio below 42wt.%) enter the coking unit reaction system 20 through the delayed coking reaction system inlet 19. The main properties of the delayed coking unit raw materials are shown in Table 6, and the properties of the obtained petroleum coke product are shown in Table 7.

[0095] The delayed coking unit uses S2.1 hydrogenated residue oil as raw material to produce petroleum coke. This part of hydrogenated residue oil was originally processed as raw material for the heavy oil catalytic cracking unit. During this stage, the inventory of hydrogenated residue oil raw material of the heavy oil catalytic cracking unit continues to decline until it reaches a relatively low level. In order to maintain the normal production of the heavy oil catalytic cracking unit, the residue oil hydrogenation unit needs to always maintain the hydrogenated residue oil raw material required for the production of heavy oil catalytic cracking, and cannot switch to the production of hydrogenated residue oil with a high residual carbon value, otherwise the heavy oil catalytic cracking unit will not be able to produce normally.

[0096] Table 5 Changes in properties of residual oil hydrogenation feedstock adjustment

[0097]

[0098] Table 6 Main properties of delayed coking unit raw materials

[0099]

[0100] Table 7 Changes in raw material ratio and sulfur content of petroleum coke in delayed coking unit

[0101]

[0102] Table 8 Balance of heavy oil system before and after delayed coking unit produces low sulfur coke

[0103]

[0104] It can be seen from the above embodiments and comparative embodiments that the residue oil hydrogenation unit in the embodiment switches to produce high carbon residue value hydrogenated residue oil (carbon residue value 5.89wt.% or more) according to its vacuum residue oil raw material inventory and properties, and the low carbon residue value hydrogenated residue oil raw material inventory can also meet the normal production of the heavy oil catalytic cracking unit. The delayed coking unit produces low-sulfur petroleum coke (sulfur content 1.4wt.%) with high carbon residue value hydrogenated residue oil as the main raw material. Before and after the delayed coking unit switches to produce low-sulfur petroleum coke, according to the vacuum residue oil raw material inventory, the atmospheric vacuum unit switches to process inferior crude oil of different properties. In the process, the raw material inventory of hydrogenated residue oil, vacuum residue oil, etc. can meet the normal production of the residue oil hydrogenation unit, delayed coking and heavy oil catalytic cracking unit.

[0105] In the comparative example, the residual oil hydrogenation unit reduces the proportion of vacuum residue A to obtain low residual carbon value hydrogenated residue (residue value 4.0% or less). The vacuum residue B produced by switching the atmospheric and vacuum reduction unit to process high-sulfur, high-metal content inferior crude oil is processed by the residual oil hydrogenation unit, and the carbon value of the produced hydrogenated residue is up to 3.98wt.%, and the nickel + vanadium content is 12.3wt.%. The hydrogenated residue produced in this stage is processed by the delayed coking unit to produce a petroleum coke product with a sulfur content of 2.06wt.%, which does not meet the low-sulfur petroleum coke standard, that is, the low-sulfur petroleum coke product cannot be produced.

[0106] In the comparative example, since the residue oil hydrogenation unit cannot produce high carbon value hydrogenated residue oil, the inventory of high carbon value hydrogenated residue oil has always remained at 0 inventory, the inventory of vacuum residue oil A has continued to rise, and the balance of the entire heavy oil system cannot maintain a normal state, prompting the atmospheric vacuum unit, the residue oil hydrogenation unit and the delayed coking unit to continue to maintain the original production plan, and cannot achieve flexible switching to produce high and low sulfur petroleum coke products.

Claims

1. A method for producing both low-sulfur coke and high-sulfur coke, characterized in that: The following steps are involved: S1, inferior crude oil processing and heavy oil balance: the atmospheric and vacuum device obtains information on processing inferior crude oil of different properties and outputs vacuum residue of corresponding properties; S2, the residue oil hydrotreating unit switches to produce high and low residual carbon value hydrotreating residue oil: the residue oil hydrotreating unit obtains and processes vacuum residue oil of different properties, outputs hydrotreating residue oil of corresponding properties, and feeds back vacuum residue oil raw material inventory data of different properties, including: Combined with the inventory of vacuum residue A raw material of the residue hydrotreating unit, the properties of vacuum residue A raw material and the processing plan of the unit, the residue hydrotreating unit uses the existing process flow to switch to produce high- and low-carbon-residue-value hydrogenated residues; in the process of switching to produce high- and low-carbon-residue-value hydrogenated residues, the residue hydrotreating unit switches to produce high-carbon-residue-value hydrogenated residues by adjusting the raw materials, reducing the reactor bed temperature, increasing the circulating hydrogen flow rate and reducing the new hydrogen flow rate while keeping the processing volume and the mixed heavy oil ratio unchanged. The high-carbon-residue-value hydrogenated residue enters the high-carbon-residue-value hydrogenated residue tank area and is used as the raw material for producing low-sulfur petroleum coke in the coking unit; Evaluate the residual carbon value of vacuum residue A raw material. When the residual carbon value of vacuum residue A raw material is low and the inventory of low-carbon-residue hydroresidue raw material is in a low inventory state, the residue oil hydrogenation unit produces low-carbon-residue hydroresidue at this stage; when the residual carbon value of vacuum residue A raw material is high and the inventory of high-carbon-residue hydroresidue raw material is in a low inventory state, the residue oil hydrogenation unit produces high-carbon-residue hydroresidue at this stage; S3, delayed coking unit switching to produce high and low sulfur petroleum coke products, including: S3.1 Assess the inventory status of high carbon residue hydroprocessing residue and vacuum residue raw materials; S3.2, when the delayed coking unit is in a high inventory state according to the production plan and the vacuum residue B raw material, 78.0wt.% vacuum residue B and 22.0wt.% catalytic oil slurry raw material enter the coking unit reaction system through the delayed coking reaction system inlet to obtain high sulfur petroleum coke; S3.3, the delayed coking unit produces low-sulfur petroleum coke with high-carbon value hydrogenated residue oil as the main raw material. When the high-carbon value hydrogenated residue oil raw material is in a high inventory state, the delayed coking unit uses 58.0wt.% or more high-carbon value hydrogenated residue oil raw material from the high-carbon value hydrogenated residue oil tank area and 42.0wt.% or less catalytic oil slurry raw material to enter the coking unit reaction system through the inlet of the delayed coking reaction system to obtain low-sulfur petroleum coke.

2. The method according to claim 1, characterized in that In step S2: The proportion of vacuum residue A in the raw material of the residue hydrogenation unit is increased to more than 39.0wt.%, and the proportion of mixed heavy oil is correspondingly reduced to less than 61.0wt.%. The two streams of raw materials enter the residue hydrogenation reaction system, and then the reactor catalyst bed temperature is controlled at 360-375℃, and the circulating hydrogen flow rate is controlled at 240000-250000Nm 3 / h, the flow rate of new hydrogen is controlled at 44000-48000Nm 3 / h, to obtain a high carbon residue value hydrogenated residue oil with a carbon residue value of more than 5.0wt.%.

3. The method according to claim 1, characterized in that Step S1 includes: The atmospheric vacuum unit processes low-quality crude oil with high sulfur and high metal content. When the vacuum residue B produced is stored in the raw material tank of the delayed coking unit until the storage tank is full of vacuum residue, the atmospheric vacuum unit switches to processing low-quality crude oil with high sulfur and low metal content; when the vacuum residue A produced is stored in the raw material tank of the residue oil hydrogenation unit until the storage tank is full of vacuum residue, the atmospheric vacuum unit switches again to processing low-quality heavy oil with high sulfur and high metal content.

4. The method according to claim 3, characterized in that Step S1 includes: The mixed heavy oil produced during the processing of low-quality crude oil in the atmospheric and vacuum units is always used as part of the residual oil hydroprocessing feedstock.

5. The method according to claim 4, characterized in that Step S1 specifically includes: (1) According to the specific processing volume or processing plan of the delayed coking unit and the residue oil hydrotreating unit, if the vacuum residue oil B raw material of the delayed coking unit is used to a low inventory state, it is necessary to switch the atmospheric vacuum process to process high-sulfur, high-metal content inferior crude oil; if the vacuum residue oil A raw material of the residue oil hydrotreating unit is used to a low inventory state, it is necessary to switch the atmospheric vacuum process to process high-sulfur, low-metal content inferior crude oil; (2) The type of low-quality crude oil that the atmospheric and vacuum distillation unit switches to process needs to be determined based on the existing crude oil varieties, the inventory of vacuum residue oil raw materials in the residue oil hydrotreating and delayed coking units, and the processing plans of the two units.

6. The method according to claim 1, characterized in that: The residual carbon value of the vacuum residue oil A raw material is evaluated using the GB / T 17144-2021 analysis method.

7. The method according to claim 1, characterized in that In step S3: By controlling the ratio of high carbon value hydrogenated residue oil and catalytic oil slurry raw materials in the delayed coking unit, the production time and output of low-sulfur coke in the delayed coking unit can be extended.

8. The method according to any one of claims 1 to 7, characterized in that: It contains at least two kinds of inferior crude oil with different properties, two kinds of vacuum residue oil tanks with different properties, and two kinds of desulfurized residue oil tanks with different properties. The system is connected between the devices and between the devices and the tank area. The switching production plan of the devices is a continuous production process.

9. The method according to any one of claims 1 to 7, characterized in that: In step S2: Evaluate the residual carbon value of the vacuum residue A raw material. When the residual carbon value of the vacuum residue A raw material is low and the inventory of low carbon value hydrogenated residue raw material is in a low inventory state, the residue hydrogenation unit will produce low carbon value hydrogenated residue in this stage; when the residual carbon value of the vacuum residue A raw material is high and the inventory of high carbon value hydrogenated residue raw material is in a low inventory state, high carbon value hydrogenated residue will be produced in this stage.

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