Delayed coking system and method

Abstract

According to the delayed coking system and method, a light oil disperser is arranged in front of a raw oil inlet of a fractionating tower, so that heavy oil and a liquid-phase fractionation product produced by the system are fully mixed and then are used as raw oil for delayed coking, and complete processing of the heavy oil by a delayed coking process can be realized; the method not only can meet the production requirements of safety, stability, long period and full load of the system, but also is beneficial to improving the economic benefit of the delayed coking system.

Description

Technical Field

[0001] This disclosure relates to the field of delayed coking in the petrochemical industry, and more specifically, to a delayed coking system and method. Background Art

[0002] Delayed coking is a key processing unit in refineries for increasing light oil yield and producing petroleum coke. It transforms heavy, low-value oil products such as vacuum residue, atmospheric residue, viscous residue, heavy crude oil, heavy feedstock, and coal tar into high-value liquid and gaseous products through deep thermal cracking reactions, while simultaneously generating petroleum coke. In delayed coking, a horizontal tubular heater is typically used to heat the material to a reaction temperature of 490–510°C under high flow rate and short residence time conditions before it enters the coking tower. Under specific temperature, residence time, and pressure conditions within the coking tower, the material undergoes cracking and condensation reactions to produce gases, gasoline, diesel, wax oil, and coke.

[0003] With the increasing trend of heavy and inferior quality of global crude oil resources, heavy oils produced by various refinery processes, such as de-oiled bitumen from solvent deasphalting, vacuum residue from atmospheric and vacuum distillation units, and viscosity-reduced residue from viscosity-reducing units; heavy oil and oil sands bitumen directly processed by delayed coking units; and coal liquefaction bitumen produced by coal chemical enterprises, all have the characteristics of high sulfur content, high density, high viscosity, high residual carbon, high asphaltenes content, and high heavy metal content. When these heavy oil materials are fully processed by delayed coking units, the outlet temperature of the coking furnace exceeds the critical coking temperature of the coking oil, and coking inside the furnace tubes is inevitable. In addition to affecting the heat transfer effect and increasing the inlet pressure, coking inside the tubes will also reduce the unit's throughput, affecting the unit's operating cycle and efficiency. If the feedstock of the delayed coking unit is replaced with other heavy oils (such as deoiled bitumen), the coking tendency of the coking oil in the furnace tubes will be more pronounced due to the increased weight and lower quality of the feedstock oil. Although online steam cleaning or mechanical cleaning can alleviate the severe coking situation in the furnace tubes, frequent furnace tube cleaning has a significant impact on the long-term and stable operation of the unit. Summary of the Invention

[0004] The purpose of this disclosure is to provide a delayed coking system and method that enables the delayed coking process to fully process heavy oil of various qualities and meets the requirements of safe, stable, long-cycle, and full-load production.

[0005] To achieve the above objectives, the first aspect of this disclosure provides a delayed coking system, the system comprising: a coking furnace, a coke tower, a fractionation tower, and a light oil disperser;

[0006] The coking furnace has a furnace feed inlet and a furnace discharge outlet; the coke tower has a coke tower feed inlet and a coke tower top product outlet; the fractionation tower has a fractionation material inlet, a feed oil inlet, a fractionation tower bottom outlet, and a liquid phase fractionation product outlet; the light oil disperser has a disperser inlet and a disperser outlet. The furnace discharge outlet is connected to the coke tower feed inlet; the coke tower top product outlet is connected to the fractionation material inlet; the feed oil inlet is connected to the disperser outlet; the fractionation tower bottom outlet is connected to the furnace feed inlet; and the disperser inlet is connected to the liquid phase fractionation product outlet. The light oil disperser is used to mix heavy oil with at least a portion of the liquid phase fractionation product from the fractionation tower, wherein the density of the heavy oil is higher than that of the liquid phase fractionation product.

[0007] Optionally, the liquid phase fractionation product outlet includes a coking diesel oil outlet and a coking wax oil outlet;

[0008] The coking diesel outlet is connected to the disperser inlet via a first regulating valve, which is used to regulate the flow rate of coking diesel entering the light oil disperser; and / or

[0009] The coking wax oil outlet is connected to the disperser inlet via a second regulating valve, which is used to regulate the flow rate of coking wax oil into the light oil disperser.

[0010] Optionally, the system also includes a steam source for supplying steam to the pipeline between the bottom outlet of the fractionation tower and the feed inlet of the heating furnace.

[0011] Optionally, a heavy oil-steam emulsification device is provided between the steam source and the feed inlet of the heating furnace.

[0012] Optionally, the heavy oil includes at least one of deoiled bitumen, vacuum residue, heavy oil, oil sands bitumen, viscosity-reducing residue, and coal liquefaction bitumen.

[0013] A second aspect of this disclosure provides a method for delayed coking using the system described in the first aspect of this disclosure, the method comprising:

[0014] Heavy oil and recycled material are mixed in the light oil disperser to obtain feed oil, wherein the recycled material is at least a portion of the liquid phase fractionation product from the fractionation tower;

[0015] The feedstock oil is fed into the fractionation tower, and coking oil is obtained from the bottom outlet of the fractionation tower.

[0016] The coking oil is fed into the coking furnace for heat exchange to obtain heat-exchanged coking oil.

[0017] The heat-exchanged coking oil is fed into the coking tower for coking reaction to obtain coking products;

[0018] The coking product is fed into the fractionation tower for fractionation to obtain the liquid phase fractionation product.

[0019] Optionally, the weight ratio of the heavy oil to the recycled material is 1:(0.1 to 0.5);

[0020] The recycled material is coking diesel oil and / or coking wax oil.

[0021] Optionally, based on 100 parts by weight of the liquid phase fractionation product, the amount of the recycled material is 20 to 100 parts by weight.

[0022] Optionally, the method further includes: mixing and emulsifying the coking oil and steam through a heavy oil-steam emulsification device before entering the coking furnace for heat exchange.

[0023] Optionally, the weight ratio of the steam to the coking oil is (0.01 to 0.2):1.

[0024] The conditions for the mixed emulsification include: a steam temperature of 350–380°C and a steam pressure of 3.5–4.0 MPa; a coking oil temperature of 300–340°C and a coking oil pressure of 2.5–3.0 MPa.

[0025] Through the above technical solution, this disclosure sets up a light oil disperser before the feed oil inlet of the fractionation tower, so that the heavy oil is fully mixed with the liquid phase fractionation products produced by the system before being used as feed oil for delayed coking. This can realize the complete processing of heavy oil by the delayed coking process, which can not only meet the system's requirements for safe, stable, long-cycle, and full-load production, but also help improve the economic benefits of the delayed coking system.

[0026] Other features and advantages of the present disclosure will be described in detail in the following detailed description. Attached Figure Description

[0027] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0028] Figure 1 This is a schematic diagram of a delayed coking system and process according to a specific embodiment of the present disclosure.

[0029] Explanation of reference numerals in the attached figures

[0030] A—Coking furnace, B—Coke tower, C—Distillation tower, D—Four-way valve, E—Light oil disperser, F—Heavy oil-steam emulsification unit, G1—First regulating valve, G2—Second regulating valve, H—Steam source;

[0031] 1—Heavy oil, 2—Coking oil, 3—Coking oil after heat exchange, 4—Coking products, 5—Rich coking gas, 6—Coking gasoline, 7—Coking diesel, 8—Coking wax oil, 9—Coke products, 10—Steam injection pipeline for heating furnace. Detailed Implementation

[0032] The following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0033] In a first aspect, this disclosure provides a delayed coking system, with reference to... Figure 1 The system includes a coking furnace A, a coke tower B, a fractionation tower C, and a light oil disperser E.

[0034] The delayed coking system disclosed herein is used for delayed coking of heavy oil. By installing a light oil disperser before the feed oil inlet of the fractionation tower, the heavy oil is fully mixed with the liquid phase fractionation products produced by the system before being used as feed oil for delayed coking. This enables the complete processing of heavy oil by the delayed coking process and meets the system's requirements for safe, stable, long-cycle, and full-load production.

[0035] The term "heavy oil" is used in contrast to "light oil," referring to oils with a density higher than that of the liquid-phase fractionation products obtained from fractionation tower C. Specifically, the density of the heavy oil can be 0.95–1.2 g / cm³. 3 (20℃), preferably 1.05~1.2g / cm³ 3 (20℃); viscosity can be up to 2000 mm. 2 / s to 5.0×10 6 mm 2 / s (100℃), preferably 1.0×10 6 mm 2 / s to 5.0×10 6 mm 2 / s (100℃). In one specific embodiment, the heavy oil includes at least one of deoiled bitumen, vacuum (deep-extraction) residue, heavy oil, oil sands bitumen, viscosity-reduced residue, and coal liquefaction bitumen. The deoiled bitumen is a heavy component obtained by solvent deasphalting of residue, containing no solvent (i.e., solvent recovery). The solvent used for solvent deasphalting can be selected from propane, isobutane, n-butane, or n-pentane, etc. This disclosure does not impose any special restrictions on the source of the deoiled bitumen. The vacuum (deep-extraction) residue refers to residual oil obtained in a vacuum distillation tower or deep-extraction tower. The heavy oil refers to heavy crude oil or extra-heavy crude oil. The oil sands bitumen refers to sedimentary rocks containing bitumen or other heavy petroleum. The viscosity-reduced residue refers to heavy residue obtained after vacuum residue has undergone viscosity-reducing cracking. The coal liquefaction bitumen refers to heavy bitumen obtained during direct or indirect coal liquefaction. In a preferred embodiment, the heavy oil is at least one selected from deoiled bitumen, viscosity-reduced residue oil, and coal liquefaction bitumen. The delayed coking system disclosed herein can achieve complete processing of the above-mentioned oil products, and the system has a longer stable operating cycle, resulting in significant economic benefits.

[0036] The light oil disperser E is used to mix heavy oil with the liquid-phase fractionation product (i.e., circulating material) from the fractionation tower to obtain feedstock oil. The light oil disperser E has a disperser inlet and a disperser outlet. The disperser inlet is used to introduce heavy oil and circulating material, and is connected to the heavy oil supply equipment and the liquid-phase fractionation product outlet of the fractionation tower C, respectively. The disperser outlet is used to discharge feedstock oil and is connected to the feedstock oil inlet of the fractionation tower C. Using the light oil disperser E facilitates thorough mixing of the heavy oil and circulating material, thereby improving the delayed coking effect of the heavy oil. In one embodiment, the light oil disperser E can be installed on the heavy oil feed line of the fractionation tower C, and the liquid-phase fractionation product outlet of the fractionation tower C is connected to the heavy oil feed line via a pipeline. The structure of the light oil disperser E may specifically include a shearing and crushing component and a spray mixing component. The shearing and crushing component is used to shear and crush the mixture of heavy oil and circulating material to make the oil particles smaller and more uniform. The spray mixing component is used to spray and mix the sheared and crushed oil. The two materials are fully mixed by high-speed spraying, thereby achieving uniform dispersion of heavy oil and circulating material.

[0037] The coking heater A is used to exchange heat with coking oil 2 to obtain coking oil 3 after heat exchange. The coking oil 2 is a mixture of heavy oil from the bottom outlet of fractionation tower C and circulating materials. The coking heater A has a heater inlet and a heater outlet. The heater inlet is connected to the bottom outlet of fractionation tower C, and the heater outlet is connected to the coke tower inlet of coke tower B.

[0038] The specific internal structure of the coking furnace A can be as well known in the art, for example, it may include a convection chamber and a radiation chamber arranged from top to bottom. The furnace inlet is located in the convection chamber, and the furnace outlet is located in the radiation chamber. A furnace tube for heat exchange of coking oil is arranged between the furnace inlet and the furnace outlet. The furnace tube passes through the convection chamber and the radiation chamber, so that the coking oil passes through the convection chamber and the radiation chamber successively to obtain the target temperature.

[0039] The coking tower B is used to coke the heat-exchanged coking oil 3 to obtain coking product 4. The coking tower B has a coking tower inlet and a coking tower top product outlet. The coking tower inlet is connected to the furnace outlet of the coking heater A, and the coking tower top product outlet is connected to the fractionation material inlet of the fractionation tower C. The coking product 4 refers to coking oil gas, which is drawn out from the coking tower top product outlet and enters the fractionation tower C. In addition, the coking tower B may also have a coking tower bottom outlet for drawing out coke product 9.

[0040] The number of coke towers B can be one or more, and this disclosure does not limit this. In one specific embodiment, the number of coke towers B can be two, and the two coke towers can alternately carry out the coking reaction, that is, while one coke tower is carrying out green coking, the other coke tower is carrying out cold coking and coke cutting operations. Further, the discharge port of the coking furnace A can be connected to the coke tower inlets of the two coke towers through a four-way valve D. The four-way valve D has an inlet, a first outlet, and a second outlet. The inlet is connected to the discharge port of the coking furnace A, the first outlet is connected to the inlet of the first coke tower, and the second outlet is connected to the inlet of the second coke tower. When the two coke towers alternately carry out the coking reaction, the first outlet and the second outlet of the four-way valve do not open simultaneously.

[0041] The fractionation tower C is used to fractionate coking product 4 to obtain fractionated products, which include gas-phase fractionated products and liquid-phase fractionated products. At least a portion of the liquid-phase fractionated products are recycled into the light oil disperser E and mixed with heavy oil to obtain feedstock oil. The fractionation tower C has a fractionated material inlet, a feedstock oil inlet, a bottom outlet of the fractionation tower, and a liquid-phase fractionated product outlet. The fractionated material inlet is connected to the top product outlet of the coking tower B, the bottom outlet of the fractionation tower is connected to the furnace feed inlet of the coking furnace A, the feedstock oil inlet is connected to the disperser outlet of the light oil disperser E, and the liquid-phase fractionated product outlet is connected to the disperser inlet of the light oil disperser E. The fractionation tower C is also used to further mix the feedstock oil to obtain coking oil 2, which is drawn from the bottom outlet of the fractionation tower and fed into the furnace outlet of the coking furnace A. The feedstock oil can be buffered at the bottom of fractionation tower C, thereby ensuring the stable operation of subsequent pumps and turbines. In addition, it can also carry the coke powder at the bottom of fractionation tower C out of the fractionation tower, preventing the coke powder from agglomerating and solidifying.

[0042] In one embodiment, the gas-phase fractionation products include coking rich gas 5 from the top of the fractionation tower, and the liquid-phase fractionation products include coking gasoline 6 (distillation range 40–200°C), coking diesel 7 (distillation range 180–340°C), and coking wax oil 8 (distillation range 300–480°C). The liquid-phase fractionation product outlets include a coking gasoline outlet, a coking wax oil outlet, and a coking diesel outlet. The coking diesel outlet and / or the coking wax oil outlet are connected to the inlet of the disperser via pipelines, i.e., coking gasoline 6 and / or coking diesel 7 enter the light oil disperser E as circulating materials. Specifically, the coking diesel outlet is connected to the disperser inlet via a first regulating valve G1, which is used to regulate the flow rate of coking diesel entering the light oil disperser E; and / or, the coking wax oil outlet is connected to the disperser inlet via a second regulating valve G2, which is used to regulate the flow rate of coking wax oil entering the light oil disperser E. The mixing ratio of heavy oil with coking gasoline 6 and / or coking diesel 7 can be adjusted through the first regulating valve G1 and / or the second regulating valve G2 to meet the processing requirements of heavy oil of different qualities. At the same time, the product structure of the delayed coking system can be adjusted to further improve the economic efficiency of the system.

[0043] The fractionation material inlet and feedstock oil inlet can be located on one side wall of the fractionation tower C. The feedstock oil inlet is located below the fractionation material inlet and near the bottom of the fractionation tower C. The coking gasoline outlet, coking wax oil outlet, and coking diesel outlet can be located from top to bottom on the other side wall of the fractionation tower C. Furthermore, the fractionation tower C may also have a top outlet for drawing out the top coking rich gas 5.

[0044] In a preferred embodiment, the system further includes a steam source H for supplying steam to the pipeline (i.e., the coking oil feed pipeline) between the bottom outlet of the fractionation tower and the feed inlet of the heating furnace. Thus, the steam mixes with the coking oil in the coking oil feed pipeline, increasing the flow rate of the coking oil into the coking heating furnace A. The steam supplied by the steam source H can be introduced into the coking oil feed pipeline through the heating furnace steam injection pipeline 10, and the steam source H can supply steam to the coking oil feed pipeline of the coking heating furnace A through multi-point steam injection.

[0045] Furthermore, a heavy oil-steam emulsification device F is installed between the steam source and the feed inlet of the heating furnace. This device F is used to thoroughly mix the steam and coking oil before they enter the coking heating furnace A to form a coking oil emulsion, preventing coking inside the furnace tubes and promoting long-term, stable operation of the delayed coking process to fully process heavy oil. Specifically, the heavy oil-steam emulsification device F can be located on the coking oil feed line near the feed inlet of the heating furnace. The specific structure of the heavy oil-steam emulsification device F may include a steam injection nozzle and a vortex disperser. High-pressure steam is injected into the high-temperature coking oil through the steam injection nozzle, and then thoroughly mixed by the vortex disperser, causing the coking oil to emulsify. The emulsified coking oil can then be heated more uniformly in the furnace tubes.

[0046] In one specific embodiment, the system may further include a control unit for controlling and adjusting the output of the liquid-phase fractionation products (especially coking diesel and coking wax oil) of the fractionation tower C and the feed rate of the circulating material into the light oil disperser E as needed. This disclosed system can flexibly adjust the output of delayed coking products while processing heavy oil, further improving the system's economic efficiency by relying on changes in the system's product distribution.

[0047] A second aspect of this disclosure provides a method for delayed coking using the system described in the first aspect of this disclosure, with reference to... Figure 1 The method includes:

[0048] Heavy oil 1 is mixed with circulating material in the light oil disperser E to obtain feed oil, wherein the circulating material is at least a portion of the liquid phase fractionation product from the fractionation tower C;

[0049] The feedstock oil is fed into the fractionation tower C, and coking oil 2 is obtained from the bottom outlet of the fractionation tower.

[0050] The coking oil 2 is introduced into the coking furnace A for heat exchange to obtain the heat-exchanged coking oil 3;

[0051] The heat-exchanged coking oil 3 is fed into the coking tower B for coking reaction to obtain coking product 4.

[0052] The coking product 4 is fed into the fractionation tower C for fractionation to obtain the liquid phase fractionation product.

[0053] The meaning and specific types of heavy oil are as described above. The circulating material can be a liquid-phase fractionation product from the fractionation tower C with a distillation range of 180–480°C. The selection of the liquid-phase fractionation product as the circulating material and the adjustment of its dosage ratio are highly flexible. Specifically, the circulating material can be coking diesel oil 7 (distillation range of 180–340°C) and / or coking wax oil 8 (distillation range of 300–480°C), and the weight ratio of heavy oil to the circulating material can be 1:(0.1–1). In a preferred embodiment, the circulating material is coking diesel oil 7, and the weight ratio of heavy oil to coking diesel oil used as the circulating material is 1:(0.1–0.35). The mixing conditions of the heavy oil and the circulating material in the light oil disperser E can include: a pressure of 0.3–0.6 MPa and a temperature of 280–330°C. By adjusting the blending ratio of circulating materials, the needs of delayed coking units for processing heavy oil of different qualities can be met, thereby adjusting the product structure of the delayed coking system and optimizing the system's economic benefits.

[0054] The temperature of coking oil 2 drawn from the bottom outlet of fractionation column C can be 300-340℃, and the temperature of coking oil 3 after heat exchange can be 495-510℃.

[0055] In the coking tower B, the conditions for the coking reaction may include: a temperature of 495–510°C and a pressure of 0.15–0.3 MPa. The coking product 4 (coking oil and gas) obtained from the coking reaction enters the fractionation tower C, and the resulting coke product 9 can be discharged from the bottom of the coking tower C into the coke pool.

[0056] In the fractionation tower C, the fractionation conditions may include: a bottom feed temperature of 400–430°C and a top pressure of 0.1–0.25 MPa. The liquid fractionation product obtained from the fractionation tower C can be partially or entirely fed into the light oil disperser E as the circulating material, which can be controlled as needed. In one embodiment, based on 100 parts by weight of the liquid fractionation product, the amount of circulating material can be 20–100 parts by weight, preferably 50–80 parts by weight. The amount of circulating material can be adjusted using the first regulating valve G1 and the second regulating valve G2 mentioned above. By adjusting the proportion of the circulating material, reasonable control of the distribution of delayed coking products can be achieved, optimizing the economic efficiency of the system. When part of the liquid fractionation product is used as the circulating material, the remaining liquid fractionation product can be collected as delayed coking product.

[0057] In one specific embodiment, the method further includes: supplying steam through a steam source H to a pipeline between the bottom outlet of the fractionation tower and the feed inlet of the heating furnace, so as to mix the steam with the coking oil. In a preferred embodiment where the heavy oil-steam emulsification device F is provided between the steam source H and the feed inlet of the heating furnace, the method may further include: mixing and emulsifying the coking oil 2 and steam through the heavy oil-steam emulsification device F before entering the coking heating furnace A for heat exchange. Further, the weight ratio of the steam to the coking oil can be (0.01~0.2):1; the mixing and emulsification conditions may include: steam temperature of 350~380℃, steam pressure of 3.5~4.0MPag; coking oil temperature of 300~340℃, and coking oil pressure of 2.5~3.0MPag. Under the above ratio and conditions, it is beneficial to increase the flow rate of coking oil in the furnace tubes of the coking heating furnace A, prevent coking in the furnace tubes, and promote the long-term and stable operation of the delayed coking process to fully process heavy oil.

[0058] The system and method disclosed herein provide a novel processing approach for heavy oil, enabling the complete processing of heavy oil through delayed coking, and meeting the system's requirements for safety, stability, long cycle time, and full-load production. By adjusting the blending ratio of circulating materials, the processing needs of heavy oils of different qualities can be met, while simultaneously allowing for adjustments to the product structure of the delayed coking system, further improving the system's economic efficiency.

[0059] The following description, in conjunction with the accompanying drawings, illustrates a specific embodiment of the delayed coking system and method of this disclosure.

[0060] like Figure 1 As shown, the system includes a coking furnace A, a coke tower B, and a fractionation tower C connected in sequence. The feedstock inlet of fractionation tower C is connected to a light oil disperser E. There are two coke towers B, which are used alternately via a four-way valve D. A first regulating valve G1 is installed on the coking diesel oil to heavy oil feed line, and a second regulating valve G2 is installed on the coking wax oil to heavy oil feed line. Steam is supplied to the coking oil feed line of coking furnace A via a steam source H. A heavy oil-steam emulsification device F is installed on the coking oil feed line.

[0061] The weight ratio of heavy oil 1 to circulating material and the circulation rate of liquid products in fractionation tower C are controlled by adjusting the valve opening of the first regulating valve G1 and / or the second regulating valve G2. Heavy oil 1 and circulating material enter the light oil disperser E for thorough mixing. The resulting feedstock oil enters the fractionation tower C and coking oil 2 is obtained from the bottom outlet of the fractionation tower. Coking oil 2 is mixed with steam provided by steam source H and then mixed and emulsified by heavy oil-steam emulsification device F. Then it enters the coking heater A for heat exchange. The coking oil 3 after heat exchange is introduced into the coking tower B through a four-way valve for coking reaction. Coking product 4 (coking oil gas) enters the fractionation tower C for fractionation to obtain coking rich gas 5, coking gasoline 6, coking diesel 7, coking wax oil 8 and other products. The generated coke product 9 is discharged into the coke pool from the bottom of the coking tower B.

[0062] The system and method disclosed herein provide a novel processing approach for heavy oil, enabling the complete processing of heavy oil through delayed coking, and meeting the system's requirements for safety, stability, long cycle time, and full-load production. By adjusting the blending ratio of circulating materials, the processing needs of heavy oils of different qualities can be met, while simultaneously allowing for adjustments to the product structure of the delayed coking system, further improving the system's economic efficiency.

[0063] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0064] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0065] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A delayed coking system, characterized in that, The system includes a coking furnace, a coke tower, a fractionation tower, and a light oil disperser; The coking furnace has a furnace feed inlet and a furnace discharge outlet; the coke tower has a coke tower feed inlet and a coke tower top product outlet; the fractionation tower has a fractionation material inlet, a raw oil inlet, a fractionation tower bottom outlet and a liquid phase fractionation product outlet; and the light oil disperser has a disperser inlet and a disperser outlet. The furnace outlet is connected to the coke tower inlet, the coke tower top product outlet is connected to the fractionation material inlet, the feed oil inlet is connected to the disperser outlet, the fractionation tower bottom outlet is connected to the furnace inlet, and the disperser inlet is connected to the liquid phase fractionation product outlet. The light oil disperser is used to mix heavy oil with at least a portion of the liquid phase fractionation product from the fractionation tower, wherein the density of the heavy oil is higher than that of the liquid phase fractionation product.

2. The system according to claim 1, wherein, The liquid phase fractionation product outlets include coking diesel oil outlets and coking wax oil outlets; The coking diesel outlet is connected to the disperser inlet via a first regulating valve, which is used to regulate the flow rate of coking diesel entering the light oil disperser. And / or, The coking wax oil outlet is connected to the disperser inlet via a second regulating valve, which is used to regulate the flow rate of coking wax oil into the light oil disperser.

3. The system according to claim 1, wherein, The system also includes a steam source for supplying steam to the pipeline between the bottom outlet of the fractionation tower and the feed inlet of the heating furnace.

4. The method according to claim 3, wherein, A heavy oil-steam emulsification device is provided between the steam source and the feed inlet of the heating furnace.

5. The system according to claim 1, wherein, The heavy oil includes at least one of deoiled bitumen, vacuum residue, heavy oil, oil sands bitumen, viscosity-reducing residue, and coal liquefaction bitumen.

6. A method for delayed coking using the system according to any one of claims 1 to 5, characterized in that, The method includes: Heavy oil and recycled material are mixed in the light oil disperser to obtain feed oil, wherein the recycled material is at least a portion of the liquid phase fractionation product from the fractionation tower; The feedstock oil is fed into the fractionation tower, and coking oil is obtained from the bottom outlet of the fractionation tower. The coking oil is fed into the coking furnace for heat exchange to obtain heat-exchanged coking oil. The heat-exchanged coking oil is fed into the coking tower for coking reaction to obtain coking products; The coking product is fed into the fractionation tower for fractionation to obtain the liquid phase fractionation product.

7. The method according to claim 6, wherein, The weight ratio of the heavy oil to the recycled material is 1:(0.1~0.5); The recycled material is coking diesel oil and / or coking wax oil.

8. The method according to claim 6, wherein, Based on 100 parts by weight of the liquid phase fractionation product, the amount of the recycled material is 20 to 100 parts by weight.

9. The method according to claim 6, wherein, The method further includes: mixing and emulsifying the coking oil and steam through a heavy oil-steam emulsification device before entering the coking furnace for heat exchange.

10. The method according to claim 9, wherein, The weight ratio of the steam to the coking oil is (0.01-0.2):

1. The conditions for the mixed emulsification include: a steam temperature of 350–380°C and a steam pressure of 3.5–4.0 MPa; a coking oil temperature of 300–340°C and a coking oil pressure of 2.5–3.0 MPa.

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