A combined production process and system for co-producing needle coke and low-sulfur petroleum coke

Abstract

This invention discloses a combined production process and system for co-producing needle coke and low-sulfur petroleum coke. The combined production process includes the following steps: a catalytic slurry is mixed with ethylene tar and subjected to a hydrogenation reaction; the hydrogenation reaction products are separated to obtain gas, naphtha, hydrogenated wax oil, and hydrogenated tail oil; the hydrogenated wax oil enters a cracking unit for a cracking reaction; the cracking reaction products are separated to obtain light oil, middle distillate oil, and residual oil; the middle distillate oil is used as feedstock for needle coke production in a needle coke production unit; the residual oil and hydrogenated tail oil are mixed and fed into a low-sulfur petroleum coke production unit to produce low-sulfur petroleum coke. This invention also provides a combined production system for co-producing needle coke and low-sulfur petroleum coke. This effectively solves the problem of excessive hydrogen supply during needle coke production from the hydrogenated slurry, and the problem of short start-up cycles for delayed coking units due to the poor thermal stability of ethylene tar.

Description

Technical Field

[0001] This invention belongs to the field of petroleum coke production technology, and specifically relates to methods and systems for producing needle coke and low-sulfur petroleum coke from aromatic oil. Background Technology

[0002] In delayed coking, aromatics, gums, and asphaltenes are the effective components for producing petroleum coke. However, vacuum residue with high gum and asphaltenes content often has a high sulfur content, resulting in petroleum coke with a sulfur content greater than 0.5 wt%, thus making it unsuitable for producing low-sulfur petroleum coke. Ethylene tar, rich in aromatics and gums and with very low sulfur content, is an excellent raw material for producing low-sulfur petroleum coke. Needle coke is a type of low-sulfur petroleum coke, but due to its properties and preparation process, it requires aromatic oils with low gum content, such as catalytic slurry oil, as a raw material.

[0003] CN104449799A discloses a method for producing high-purity petroleum coke from ethylene tar. The method involves mixing ethylene tar with light component oil at a mass ratio of 1:0.05 to 1:0.2 and then feeding the mixture into a delayed coking unit to produce high-purity petroleum coke. The purpose of mixing ethylene tar with light component oil in this method is to mitigate the tendency of ethylene tar to coke in the heating furnace. CN109207186A discloses a method for processing ethylene tar into liquid and / or coke via delayed coking. The method involves mixing the 300-500℃ fraction of ethylene tar with coking feedstock, wherein the coking feedstock is at least one of catalytic slurry oil, vacuum residue, or heavy oil, and the ethylene tar accounts for 15% to 45% of the total mass of the mixed oil. The mixed oil is used as the feedstock for the delayed coking unit.

[0004] CN105623734A discloses a method for preparing needle coke feedstock, which involves mixing catalytic oil slurry with coking feedstock and injecting it into a coking tower for delayed coking reaction, separating oil and gas to obtain wax oil components, then hydrogenating the wax oil components, and separating the hydrogenated products to obtain needle coke feedstock.

[0005] Ethylene tar contains aromatic olefins, which have poor thermal stability and are prone to condensation into coke under high-temperature conditions, affecting the long-term operation of coking units. During the hydrodesulfurization treatment of catalytic slurry, some aromatic rings are saturated into alkyl side chains. These aromatics with a large number of alkyl side chains undergo chain scission or aromatization during coking, acting as hydrogen donors, hindering the polymerization reaction process, and affecting the performance of needle coke products. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a combined production process and system for co-producing needle coke and low-sulfur petroleum coke, which can effectively solve the problem of excessive hydrogen supply in the production of needle coke by hydrogenated oil slurry, as well as the problem of short start-up cycles of delayed coking units due to the poor thermal stability of ethylene tar.

[0007] The first aspect of this invention provides a combined production process for co-producing needle coke and low-sulfur petroleum coke, the combined production process comprising the following:

[0008] (1) The catalytic oil slurry and ethylene tar are mixed and enter the hydrotreating unit. Under the action of hydrogen and hydrotreating catalyst, a hydrotreating reaction occurs. The hydrotreating reaction products are separated to obtain gas, naphtha, hydrotreating wax oil and hydrotreating tail oil.

[0009] (2) The hydrogenated wax oil obtained in step (1) enters the cracking unit and undergoes a cracking reaction under the action of carrier gas. The cracking reaction products are separated to obtain light oil, middle distillate oil and residual oil.

[0010] (3) The intermediate distillate oil obtained in step (2) is used as a raw material for needle coke and enters the needle coke production unit. After reaction, needle coke is obtained.

[0011] (4) The hydrogenated tail oil obtained in step (1) and the residual oil obtained in step (2) are mixed and fed into the low-sulfur petroleum coke production unit, and low-sulfur petroleum coke is obtained after the reaction.

[0012] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the catalytic slurry in step (1) is preferably subjected to desolidification treatment first. The desolidification treatment can be one or a combination of several methods such as filtration, centrifugal sedimentation, flocculation sedimentation, and electrostatic adsorption, with filtration being the preferred method.

[0013] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the ash content of the catalytic oil slurry in step (1) is no more than 0.01wt%, preferably no more than 0.005wt%; the sulfur content is higher than 0.5wt%, or even higher than 0.8wt%.

[0014] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the mass ratio of catalytic oil slurry to ethylene tar in step (1) is 1:2 to 1:0.1, preferably 1:0.7 to 1:0.2.

[0015] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the hydrogenation unit in step (1) includes at least one hydrogenation reactor and a hydrogenation separation system. Furthermore, when there are two or more hydrogenation reactors, there are no particular restrictions on the connection method between the reactors; they are generally connected in series. The reactor can be one or a combination of several of the following: fluidized bed reactor, suspended bed reactor, fixed bed reactor, etc., preferably a fixed bed reactor. Furthermore, the hydrogenation separation system includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, a cold low-pressure separator, and may also include equipment such as a stripping tower and a fractionation tower.

[0016] Furthermore, in the combined production process of needle coke and low-sulfur petroleum coke described above, the hydrogenation catalyst in step (1) can be an existing commercial catalyst, such as the FZC and / or FH series hydrogenation catalysts developed by the Dalian Petrochemical Research Institute, or it can be prepared using existing methods in this field. Generally, the hydrogenation catalyst uses alumina as a support and supports oxides of Group VIB and / or Group VIII metals as active components, such as one or more combinations of oxides of metals such as Mo, W, Co, and Ni.

[0017] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the reaction conditions of the hydrotreating unit in step (1) are as follows: the reaction temperature is 310℃~450℃, preferably 340℃~390℃; the reaction pressure is 2MPa~20MPa, preferably 4MPa~8MPa; the hydrogen-to-oil volume ratio is 100~2500, preferably 800~1800; and the liquid hourly space velocity is 0.1h. -1 ~2.0h -1 Preferably 0.6h -1 ~1.2h -1 .

[0018] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the distillation range of the hydrogenated wax oil in step (1) is 310℃~540℃, preferably 350℃~510℃. The sulfur content of the hydrogenated wax oil is not greater than 0.4wt%, preferably not greater than 0.35wt%.

[0019] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the sulfur content of the hydrotreated tail oil is no more than 0.4 wt%, preferably no more than 0.35 wt%.

[0020] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the cracking unit in step (2) is equipped with at least one reactor. The reactor type can be one or a combination of tubular reactor, tower reactor, and tank reactor, preferably a tower reactor. The reactor includes at least two feed inlets and one discharge outlet, one feed inlet for the first heavy oil and the other feed inlet for the carrier gas.

[0021] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the carrier gas in step (2) can be one or more of water vapor, nitrogen, and inert gas (such as helium, neon, argon, etc.), preferably water vapor.

[0022] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the reaction conditions of the cracking unit in step (2) are as follows: the reaction temperature is 380℃~520℃, preferably 420℃~490℃, the reaction pressure is 0.1MPa~5MPa, preferably 0.2MPa~1.0MPa, the residence time is 0.01h~30h, preferably 0.1h~3h, and the mass ratio of hydrogenated wax oil to steam is 100:0.1~100:20, preferably 100:1~100:8.

[0023] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the light oil in step (2) can be discharged from the device, or enter the hydrotreating unit for processing, or enter the low-sulfur petroleum coke production unit for processing, or part of it enters the hydrotreating unit for processing and part of it enters the low-sulfur petroleum coke production unit for processing; preferably, part of it enters the hydrotreating unit for processing and part of it enters the low-sulfur petroleum coke production unit for processing.

[0024] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the distillation range of the middle distillate oil in step (2) is 320℃~500℃, preferably 350℃~500℃.

[0025] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the needle coke production unit in step (3) includes at least one heating furnace, two coke towers, and one coking distillation tower. The coke towers are always kept in at least one reaction stage and at least one purging and decoking stage. Furthermore, the reaction conditions of the needle coke production unit are as follows: the outlet temperature of the heating furnace is 420℃~560℃, preferably 440℃~530℃, and the heating rate is 0.5℃ / h~30℃ / h, preferably 3℃ / h~7℃ / h; the top pressure of the coke tower is 0.01MPa~2.5MPa, preferably 0.2MPa~1.3MPa, which can be constant pressure operation or variable pressure operation. If variable pressure operation is adopted, the variable pressure rate is 0.1MPa / h~5MPa / h; the reaction cycle is 10h~72h, preferably 32h~54h.

[0026] Furthermore, in the above-mentioned combined production process of needle coke and low-sulfur petroleum coke, the low-sulfur petroleum coke production unit in step (4) includes at least one heating furnace, two coke towers, and one coking fractionation tower. The coke towers are always kept in at least one reaction stage and at least one purging and decoking stage. Furthermore, the reaction conditions of the low-sulfur petroleum coke production unit are as follows: the heating furnace outlet temperature is 480℃~550℃, preferably 490℃~510℃; the coke tower top pressure is 0.01MPa~2.5MPa, preferably 0.1MPa~0.5MPa, and can be operated under constant pressure or variable pressure, preferably constant pressure; the reaction cycle is 10h~48h, preferably 18h~30h.

[0027] A second aspect of the present invention provides a combined production system for the co-production of needle coke and low-sulfur petroleum coke, the combined production system comprising:

[0028] The hydrotreating unit receives catalytic slurry and ethylene tar, and a hydrotreating reaction occurs under the action of hydrogen and a hydrotreating catalyst. The hydrotreating reaction products are separated to obtain gas, naphtha, hydrotreating wax oil and hydrotreating tail oil.

[0029] The cracking unit is used to receive hydrotreating tail oil from the hydrotreating unit and to carry out cracking reaction under the action of carrier gas.

[0030] The separation unit is used to receive the cracking reaction products from the cracking treatment unit and separate them to obtain light oil, middle distillate oil and residual oil.

[0031] The needle coke production unit is used to receive the middle distillate oil from the separation unit and react it to obtain needle coke;

[0032] The low-sulfur petroleum coke production unit receives hydrotreated tail oil from the hydrotreating unit and residual oil from the separation unit, and reacts them to obtain low-sulfur petroleum coke.

[0033] Furthermore, in the aforementioned combined production system for needle coke and low-sulfur petroleum coke, the light oil obtained after separation by the separation unit can be discharged through a pipeline, or processed in a hydrotreating unit, or processed in a low-sulfur petroleum coke production unit, or partially processed in both the hydrotreating and low-sulfur petroleum coke production units; preferably, partially processed in both the hydrotreating and low-sulfur petroleum coke production units.

[0034] Furthermore, the aforementioned combined production system for producing needle coke and low-sulfur petroleum coke includes a desolidification unit for receiving and processing catalytic slurry and desolidifying it. The desolidification unit can employ one or a combination of methods such as filtration, centrifugal sedimentation, flocculation sedimentation, and electrostatic adsorption, with filtration being the preferred method.

[0035] Furthermore, in the aforementioned combined production system for needle coke and low-sulfur petroleum coke, the hydrotreating unit includes at least one hydrotreating reactor and a hydrotreating separation system. Furthermore, when there are two or more hydrotreating reactors, the connection method between the reactors is not particularly limited, and they are generally connected in series. The reactor can be one or a combination of several of the following: fluidized bed reactor, suspended bed reactor, fixed bed reactor, etc., preferably a fixed bed reactor. Furthermore, the hydrotreating separation system includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator, and may also include equipment such as a stripping tower and a fractionation tower. Specifically, in this invention, the hydrotreating reaction effluent enters the hydrotreating separation system for separation to obtain gas, naphtha, hydrotreating wax oil, and hydrotreating tail oil.

[0036] Furthermore, in the aforementioned combined production system for needle coke and low-sulfur petroleum coke, the separation unit can be one or a combination of several of the following: stripping tower, flash tower, and fractionation tower, with fractionation tower being preferred.

[0037] Furthermore, in the aforementioned combined production system for needle coke and low-sulfur petroleum coke, the cracking unit is equipped with at least one reactor. The reactor type can be one or a combination of tubular reactors, tower reactors, and tank reactors, preferably a tower reactor. The reactor includes at least two feed inlets and one discharge outlet, one feed inlet for the first heavy oil and the other feed inlet for the carrier gas.

[0038] Furthermore, in the aforementioned combined production system for needle coke and low-sulfur petroleum coke, the needle coke production unit includes at least one heating furnace, two coke towers, and one coking fractionation tower. The coke towers are always maintained in at least one reaction stage and at least one purging and decoking stage.

[0039] Furthermore, in the aforementioned combined production system for needle coke and low-sulfur petroleum coke, the low-sulfur petroleum coke production unit includes at least one heater, two coke towers, and one coking fractionation tower. The coke towers are always maintained in at least one reaction stage and at least one purging and decoking stage.

[0040] Compared with existing technologies, the combined production process and system for co-producing needle coke and low-sulfur petroleum coke provided by this invention have the following technical advantages:

[0041] (1) In the combined production process of needle coke and low-sulfur petroleum coke provided by the present invention, the components in the catalytic slurry and ethylene tar are effectively enriched and separated, and graded for processing, thereby improving the effective utilization rate of raw materials. First, the mixed raw materials (catalytic slurry and ethylene tar) are hydrogenated, and then the hydrogenation reaction effluent is subjected to a first fractionation to separate the hydrogenation tail oil rich in a large amount of gum components as the raw material for producing low-sulfur petroleum coke. Then, the hydrogenated wax oil fraction is sent to the cracking unit for cracking treatment, and then the cracking reaction effluent is subjected to a second fractionation to separate the fraction rich in tricyclic and tetracyclic aromatic hydrocarbons as the raw material for producing needle coke, thereby preparing high-quality needle coke.

[0042] (2) In the combined production process of needle coke and low-sulfur petroleum coke provided by the present invention, light oil is returned to the hydrotreating unit and / or the low-sulfur petroleum coke production unit. The light oil is rich in bicyclic aromatics. After saturation treatment in the hydrotreating unit, one aromatic ring is converted into a monocyclic aromatic, and the product can be used as an ideal component of high-octane gasoline. When the light oil is directly sent to the low-sulfur petroleum coke production unit to undergo a condensation reaction, deep condensation produces low-sulfur petroleum coke, and shallow condensation produces wax oil fraction (mainly tricyclic and tetracyclic aromatics). The wax oil fraction is a high-quality raw material for the production of low-sulfur petroleum coke.

[0043] (3) In the combined production process of needle coke and low-sulfur petroleum coke provided by the present invention, the catalytic slurry and ethylene tar are simultaneously hydrogenated. The purpose of hydrogenating the catalytic slurry is to reduce the sulfur content of the slurry and to prevent the aromatic double bonds from being saturated. The main purpose of hydrogenating the ethylene tar is to saturate the olefin double bonds and improve the thermal stability of the ethylene tar. The reactions are ordered from easiest to hardest: hydrodesulfurization, olefin double bond saturation, and aromatic double bond saturation. By adding ethylene tar, the olefin double bond saturation of ethylene tar and the aromatic double bond saturation of catalytic slurry compete with each other, reducing the aromatic ring saturation rate of the catalytic slurry and improving the selectivity and yield of the target products (tricyclic and tetracyclic aromatic rings).

[0044] (4) In the combined production process of needle coke and low-sulfur petroleum coke provided by the present invention, the molecular composition of the needle coke feedstock is optimized from the perspective of molecular composition and microstructure. During the hydrodesulfurization of catalytic slurry, some aromatic rings are inevitably saturated. When needle coke is prepared directly from this feedstock, these aromatics with saturated side chains will undergo chain breaking or aromatization reactions. The small molecules generated will escape and disturb the reaction system, hindering the liquid-phase carbonization reaction and resulting in incomplete development of the intermediate phase, which directly affects the microstructure of the needle coke. In addition, the simultaneous occurrence of aromatic side chain breaking reaction and condensation reaction will affect the planarity of the condensed macromolecules, resulting in a loose lamellar structure of the needle coke and a decrease in mechanical properties. The present invention cracks the hydrotreated middle distillate oil to remove the saturated side chains of aromatics in advance, ensuring from the perspective of molecular structure that the aromatics in the cracking products are all aromatics with a small amount of short side chains, which is beneficial for producing high-quality needle coke products. Attached Figure Description

[0045] Figure 1 A schematic diagram of the combined production process and system for co-producing needle coke and low-sulfur petroleum coke provided by the present invention. Detailed Implementation

[0046] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0047] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0048] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (e.g., rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0049] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0050] In this document, all numeric values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numeric value.

[0051] In this paper, the sulfur content was determined by the GB / T 24526 method; the Hastelloy grindability index was determined by the GB / T 2565 method; the tap density sample was prepared according to the requirements of GB / T 1997, and at least 150g of 1mm~2mm particles were screened and determined by the GB / T21354 method; the particle strength was determined by the method in Appendix B of T / ZGTS 002.

[0052] The combined production process of needle coke and low-sulfur petroleum coke provided by this invention is as follows: Figure 1 As shown, in the presence of hydrogen 22, catalytic slurry 1 and ethylene tar 2 enter the hydrogenation reactor 3 of the hydrogenation treatment unit, where they react with the hydrogenation catalyst to undergo a hydrogenation reaction. The hydrogenation reaction product 4 enters the hydrogenation separation system 5 for separation, yielding gas 6, naphtha 7, hydrogenated wax oil 8, and hydrogenated tail oil 9. The separated hydrogenated wax oil 8 enters the cracking treatment unit 10, where it undergoes a cracking reaction under the action of carrier gas 11. The cracking reaction product 12 enters the separation unit 13, where it is separated to obtain light oil 1. 4. Middle distillate oil 16 and residual oil 15; the obtained middle distillate oil 16 is used as a needle coke feedstock and enters the needle coke production unit 17. After reaction, oil gas 18 and needle coke 19 are obtained; the obtained residual oil 15 and hydrotreated tail oil 9 enter the low-sulfur petroleum coke production unit 20. After reaction, low-sulfur petroleum coke product 21 is obtained; the obtained light oil 14 can be discharged from the unit, or enter the hydrotreating unit, or enter the low-sulfur petroleum coke production unit 20, or partly enter the hydrotreating unit and partly enter the low-sulfur petroleum coke production unit.

[0053] The properties of the catalytic slurry and ethylene tar feedstock used in the embodiments and comparative examples of this invention are shown in Table 1. The hydrogenation catalyst used is the FZC-34BT hydrogenation catalyst developed by the Dalian Research Institute of Petrochemical Technology, Sinopec. Steam is used as the carrier gas in the cracking unit.

[0054] Example 1

[0055] Example 1 uses the method provided by this invention. Catalytic oil slurry and ethylene tar are mixed at a mass ratio of 1:0.4 and fed into the hydrotreating unit. Hydrogenation occurs in the presence of hydrogen and the slurry comes into contact with the hydrotreating catalyst. The hydrotreating conditions are: reaction temperature 375°C, reaction pressure 5.3 MPa, hydrogen-to-oil volume ratio 1200, and liquid hourly space velocity 0.90 h⁻¹. -1The hydrotreating reaction products are separated to obtain hydrotreated wax oil and hydrotreated tail oil, with the hydrotreated wax oil having a distillation range of 363℃~505℃. The hydrotreated wax oil and steam are fed into the cracking unit at a mass ratio of 100:4. The cracking reaction conditions are: reaction temperature 471℃, reaction pressure 0.54MPa, and residence time 1.0h. The cracking products are separated to obtain light oil, middle distillate oil, and residual oil. The light oil is returned to the hydrotreating unit, and the middle distillate oil has a distillation range of 368℃~493℃. The middle distillate oil is sent to the needle coke production unit, where the reaction conditions are: furnace outlet temperature 450℃~515℃, heating rate 5℃ / h, coke tower top pressure 0.80MPa, constant pressure operation, and a reaction cycle of 46h. The residual oil and hydrotreated tail oil are mixed and sent to the low-sulfur petroleum coke production unit. The reaction conditions are: furnace outlet temperature of 497℃, coke tower top pressure of 0.18MPa, and reaction cycle of 24h.

[0056] Example 2

[0057] Example 2 uses the method provided by this invention. Catalytic oil slurry and ethylene tar are mixed at a mass ratio of 1:0.5 and fed into the hydrotreating unit. Hydrogenation occurs in the presence of hydrogen and the slurry comes into contact with the hydrotreating catalyst. The hydrotreating conditions are: reaction temperature 371°C, reaction pressure 5.7 MPa, hydrogen-to-oil volume ratio 1200, and liquid hourly space velocity 0.90 h⁻¹. -1 The hydrogenation reaction products are separated to obtain hydrogenated wax oil and hydrogenated tail oil, with the hydrogenated wax oil having a distillation range of 360℃~505℃. The hydrogenated wax oil and steam are fed into the cracking unit at a mass ratio of 100:4. The cracking reaction conditions are: reaction temperature 468℃, reaction pressure 0.48MPa, and residence time 1.6h. The cracking products are separated to obtain light oil, middle distillate oil, and residual oil, with the middle distillate oil having a distillation range of 372℃~495℃. The middle distillate oil is sent to the needle coke production unit, where the reaction conditions are: furnace outlet temperature 450℃~515℃, heating rate 5℃ / h, coke tower top pressure 0.80MPa, constant pressure operation, and a reaction cycle of 46h. Light oil, residual oil, and hydrotreated tail oil are mixed and sent to the low-sulfur petroleum coke production unit. The reaction conditions are: furnace outlet temperature of 497℃, coke tower top pressure of 0.26MPa, and reaction cycle of 24h.

[0058] Comparative Example 1

[0059] Comparative Example 1 uses existing technology to produce needle coke and low-sulfur / ordinary petroleum coke. Catalytic slurry and ethylene tar are mixed at a mass ratio of 1:0.5 and fed into a fractionation tower to separate light oil, middle distillate, and residual oil. The middle distillate has a boiling range of 350℃ to 500℃. The middle distillate then enters a hydrotreating unit, where it undergoes a hydrogenation reaction in the presence of hydrogen and a hydrotreating catalyst. The hydrogenation reaction conditions are: reaction temperature 369℃, reaction pressure 5.6 MPa, hydrogen-to-oil volume ratio 1200, and liquid hourly space velocity (LHSV) 0.90 h⁻¹. -1 The hydrogenation reaction products are separated to obtain gas, naphtha, and hydrogenated tail oil, with the 5% distillation temperature of the hydrogenated tail oil at 378℃. The hydrogenated tail oil enters the needle coke production unit under the following conditions: furnace outlet temperature of 462℃~515℃, heating rate of 5℃ / h, coke tower top pressure of 0.80MPa, constant pressure operation, and a reaction cycle of 46h. Light oil and residual oil are sent to the low-sulfur / ordinary petroleum coke production unit under the following conditions: furnace outlet temperature of 497℃, coke tower top pressure of 0.25MPa, and a reaction cycle of 24h.

[0060] Comparative Example 2

[0061] Comparative Example 2 uses existing technology to produce needle coke and low-sulfur / ordinary petroleum coke. Catalytic slurry enters the hydrotreating unit, where it contacts the hydrotreating catalyst in the presence of hydrogen to undergo a hydrogenation reaction. The hydrogenation reaction conditions are: reaction temperature 367℃, reaction pressure 5.7 MPa, hydrogen-to-oil volume ratio 1200, and liquid hourly space velocity 0.90 h⁻¹. -1 The hydrogenation reaction products and ethylene tar were separated at a mass ratio of 1:0.35 to obtain gas, naphtha, diesel fraction, wax oil fraction, and tail oil. The 5% distillation temperature of the diesel fraction was 191℃, and the boiling range of the wax oil fraction was 377℃~496℃. The wax oil fraction entered the needle coke production unit under the following conditions: furnace outlet temperature of 462℃~515℃, heating rate of 5℃ / h, coke tower top pressure of 0.80MPa, constant pressure operation, and a reaction cycle of 46h. The diesel fraction and tail oil were sent to the low-sulfur / ordinary petroleum coke production unit under the following conditions: furnace outlet temperature of 495℃, coke tower top pressure of 0.24MPa, and a reaction cycle of 24h.

[0062] The needle cokes obtained in the above examples and comparative examples were tested for ash content, sulfur content, volatile matter, and Hastelloy grindability index. After calcination at 1350℃, the needle cokes were calcined to obtain cooked coke, and the true density, tap density, and particle strength of the cooked coke were tested. The results are shown in Table 2.

[0063] The ash and sulfur content of the low-sulfur petroleum coke obtained in the above examples and comparative examples were tested. After calcination at 1350℃, the obtained low-sulfur petroleum coke was obtained as cooked coke, and the true density of the cooked coke was tested. The results are shown in Table 3.

[0064] Table 1 Properties of Crude Oil

[0065]

[0066] Table 2 Properties of needle char

[0067]

[0068] As can be seen from Table 2, the needle coke prepared by the method of the present invention has a low Hastelloy grindability index and high particle strength, indicating that the product has good mechanical properties. Furthermore, the needle coke obtained in Examples 1 and 2 has a low volatile content.

[0069] Table 3 Properties of Low-Sulfur / Ordinary Petroleum Coke

[0070]

[0071] As shown in Table 3, the sulfur content of the ordinary petroleum coke prepared by the method of the present invention is all below 0.5 wt%, which belongs to low-sulfur petroleum coke. The ordinary petroleum coke obtained by Comparative Example 1 has a higher sulfur content and does not belong to low-sulfur petroleum coke; the sulfur content of the ordinary petroleum coke obtained by Comparative Example 2 meets the requirements of low-sulfur petroleum coke, but its true density is slightly lower than that of the examples.

Claims

1. A combined production process for needle coke and low-sulfur petroleum coke, the combined production process comprising the following: (1) The catalytic oil slurry and ethylene tar are mixed and enter the hydrotreating unit. Under the action of hydrogen and hydrotreating catalyst, a hydrotreating reaction occurs. The hydrotreating reaction products are separated to obtain gas, naphtha, hydrotreating wax oil and hydrotreating tail oil. (2) The hydrotreated wax oil obtained in step (1) enters the cracking unit and undergoes a cracking reaction under the action of carrier gas. The cracking reaction products are separated to obtain light oil, middle distillate oil and residual oil. The reaction conditions of the cracking unit are as follows: the reaction temperature is 380℃~520℃, the reaction pressure is 0.1MPa~5MPa, and the residence time is 0.01h~30h. The distillation range of the middle distillate oil is 320℃~500℃. (3) The intermediate distillate oil obtained in step (2) is used as a raw material for needle coke and enters the needle coke production unit. After reaction, needle coke is obtained. (4) The hydrogenated tail oil obtained in step (1) and the residual oil obtained in step (2) are mixed and fed into the low-sulfur petroleum coke production unit, and low-sulfur petroleum coke is obtained after the reaction.

2. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: In step (1), the ash content of the catalytic oil slurry is no more than 0.01 wt%.

3. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The ash content of the catalytic oil slurry in step (1) is no more than 0.005 wt%.

4. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: In step (1), the mass ratio of catalytic oil slurry to ethylene tar is 1:2 to 1:0.

1.

5. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: In step (1), the mass ratio of catalytic oil slurry to ethylene tar is 1:0.7 to 1:0.

2.

6. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions for the hydrogenation unit in step (1) are as follows: reaction temperature 310℃~450℃, reaction pressure 2MPa~20MPa, hydrogen-to-oil volume ratio 100~2500, and liquid hourly space velocity 0.1h. -1 ~2.0h -1 .

7. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions for the hydrogenation unit in step (1) are as follows: reaction temperature 340℃~390℃, reaction pressure 4MPa~8MPa, hydrogen-to-oil volume ratio 800~1800, and liquid hourly space velocity 0.6h. -1 ~1.2h -1 .

8. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: In step (1), the distillation range of the hydrogenated wax oil is 310℃~540℃, and the sulfur content of the hydrogenated wax oil is no more than 0.4wt%.

9. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: In step (1), the distillation range of the hydrogenated wax oil is 350℃~510℃, and the sulfur content of the hydrogenated wax oil is no more than 0.35wt%.

10. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The sulfur content of the hydrotreated tail oil is no more than 0.4 wt%.

11. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The sulfur content of the hydrotreated tail oil is no more than 0.35 wt%.

12. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The carrier gas in step (2) is one or more of water vapor, nitrogen, and inert gas.

13. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The carrier gas in step (2) is water vapor.

14. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions of the cracking unit in step (2) are as follows: reaction temperature is 420℃~490℃, reaction pressure is 0.2MPa~1.0MPa, and residence time is 0.1h~3h.

15. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 12 or 13, characterized in that: The mass ratio of hydrogenated wax oil to water vapor is 100:0.1 to 100:

20.

16. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 12 or 13, characterized in that: The mass ratio of hydrogenated wax oil to water vapor is 100:1 to 100:

8.

17. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The light oil discharged from the device in step (2) may either be processed in the hydrotreating unit or in the low-sulfur petroleum coke production unit, or part of it may be processed in the hydrotreating unit and part of it may be processed in the low-sulfur petroleum coke production unit.

18. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: In step (2), a portion of the light oil is processed in the hydrotreating unit, and a portion is processed in the low-sulfur petroleum coke production unit.

19. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The distillation range of the intermediate distillate oil in step (2) is 350℃~500℃.

20. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions for the needle coke production unit in step (3) are: the outlet temperature of the heating furnace is 420℃~560℃, the pressure at the top of the coke tower is 0.01MPa~2.5MPa, and the reaction cycle is 10h~72h.

21. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions for the needle coke production unit in step (3) are: the outlet temperature of the heating furnace is 440℃~530℃, the pressure at the top of the coke tower is 0.2MPa~1.3MPa, and the reaction cycle is 32h~54h.

22. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions for the low-sulfur petroleum coke production unit in step (4) are: the outlet temperature of the heating furnace is 480℃~550℃, the pressure at the top of the coke tower is 0.01MPa~2.5MPa, and the reaction cycle is 10h~48h.

23. The combined production process for co-producing needle coke and low-sulfur petroleum coke according to claim 1, characterized in that: The reaction conditions for the low-sulfur petroleum coke production unit in step (4) are: the outlet temperature of the heating furnace is 490℃~510℃, the pressure at the top of the coke tower is 0.1MPa~0.5MPa, and the reaction cycle is 18h~30h.

24. A combined production system for co-producing needle coke and low-sulfur petroleum coke, implementing the process of any one of claims 1-23, the combined production system comprising: The hydrotreating unit receives catalytic slurry and ethylene tar, and a hydrotreating reaction occurs under the action of hydrogen and a hydrotreating catalyst. The hydrotreating reaction products are separated to obtain gas, naphtha, hydrotreating wax oil and hydrotreating tail oil. The cracking unit is used to receive hydrotreated wax oil from the hydrotreating unit and to carry out a cracking reaction under the action of a carrier gas. The separation unit is used to receive the cracking reaction products from the cracking treatment unit and separate them to obtain light oil, middle distillate oil and residual oil. The needle coke production unit is used to receive the middle distillate oil from the separation unit and react it to obtain needle coke; The low-sulfur petroleum coke production unit receives hydrotreated tail oil from the hydrotreating unit and residual oil from the separation unit, and reacts them to obtain low-sulfur petroleum coke.

25. The combined production system for co-producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: The light oil obtained after separation in the separation unit is discharged through pipelines, or enters the hydrotreating unit for processing, or enters the low-sulfur petroleum coke production unit for processing, or part of it enters the hydrotreating unit for processing and part of it enters the low-sulfur petroleum coke production unit for processing.

26. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: The light oil obtained after separation in the separation unit is partially processed in the hydrotreating unit and partially processed in the low-sulfur petroleum coke production unit.

27. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: It includes a desolidification unit for receiving and processing catalytic slurry, and for desolidifying the catalytic slurry. The desolidification unit employs one or more of the following methods: filtration, centrifugal sedimentation, flocculation sedimentation, and electrostatic adsorption.

28. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 27, characterized in that: The solidification treatment unit uses a filtration method.

29. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: The hydrogenation treatment unit includes at least one hydrogenation reactor and a hydrogenation separation system. The reactor is one or more of the following: a fluidized bed reactor, a suspended bed reactor, and a fixed bed reactor. The hydrogenation separation system includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, a cold low-pressure separator, and also includes a stripping tower and a fractionation tower.

30. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 29, characterized in that: The reactor is a fixed-bed reactor.

31. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: The separation unit is one or more of the following: stripping tower, flash tower, and fractionation tower.

32. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: The separation unit is a distillation tower.

33. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: The cracking unit is equipped with at least one reactor, which is one or more of the following types: tubular reactor, tower reactor, and tank reactor; the reactor includes at least two feed inlets and one discharge outlet, one feed inlet for hydrotreated wax oil and the other feed inlet for carrier gas.

34. The combined production system for co-producing needle coke and low-sulfur petroleum coke according to claim 33, characterized in that: The reactor type is a tower reactor.

35. The combined production system for co-producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: A needle coke production unit includes at least one heating furnace, two coke towers and one coking distillation tower. The coke towers are always kept in at least one reaction stage and at least one purging and decoking stage.

36. The combined production system for producing needle coke and low-sulfur petroleum coke according to claim 24, characterized in that: A low-sulfur petroleum coke production unit includes at least one heating furnace, two coke towers and one coking distillation tower. The coke towers are always kept in at least one reaction stage and at least one purging and decoking stage.

Images