Preparation method of light fuel oil in heavy oil delayed coking product

Abstract

The invention provides a preparation method of light fuel oil in a heavy oil delayed coking product, and belongs to the technical field of heavy oil delayed coking. The method comprises the following steps: adding coal tar and a surfactant into heavy oil according to a preset mass ratio, stirring and mixing, and reacting at a first preset temperature to prepare an intermediate product; and in a carbon dioxide atmosphere, heating the intermediate product to a second preset temperature for reaction to obtain the light fuel oil.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of heavy oil delayed coking, and more particularly, to a method for preparing light fuel oil in a heavy oil delayed coking product. BACKGROUND

[0002] In recent years, with the growth of demand for light fuel and the shortage of crude oil reserves and the contraction of conventional oil, it is of great significance to use heavy oil, such as unconventional resources, to produce light oil to ensure national defense security and national interests. The global recoverable reserves of heavy oil in 2024 are 36.1 billion tons, and heavy oil generally accounts for 40% to 50% in the process of crude oil processing, and contains more sulfur, nitrogen, metals, macromolecular asphaltene and residual carbon. The processes for producing light fuel oil from heavy oil mainly include delayed coking, catalytic cracking and hydrocracking. Catalytic cracking and hydrocracking are often accompanied by serious catalyst coking and deactivation problems in the process of heavy oil hydrogenation, which greatly affects the lightening effect of heavy oil. Delayed coking does not involve catalyst deactivation problems, and the process is simpler, so it has become the mainstream way of lightening heavy oil. However, a large amount of coke is also generated in the delayed coking of heavy oil, which seriously affects the yield of light fuel oil. Therefore, how to inhibit the generation of coke in delayed coking has become the key to the high value-added utilization of heavy oil resources, and is also of great significance to national energy security. SUMMARY

[0003] Therefore, the present disclosure provides a method for preparing light fuel oil in a heavy oil delayed coking product, which can at least partially solve the above technical problems.

[0004] The present disclosure provides a method for preparing light fuel oil in a heavy oil delayed coking product, comprising: adding a preset mass ratio of coal tar and a surfactant to heavy oil, stirring and mixing, and then reacting at a first preset temperature to prepare an intermediate product; and heating the intermediate product to a second preset temperature under a carbon dioxide atmosphere to obtain the light fuel oil.

[0005] According to an embodiment of the present disclosure, the preset mass ratio of the coal tar and the surfactant is 1:(0.002-0.01).

[0006] According to an embodiment of the present disclosure, the heating of the intermediate product to the second preset temperature under the carbon dioxide atmosphere comprises: filling the intermediate product with carbon dioxide to make the pressure of the container in which the intermediate product is located a preset pressure; and heating the container with the preset pressure to the second preset temperature under stirring to react.

[0007] According to an embodiment of the present disclosure, before the intermediate product is filled with carbon dioxide to make the pressure of the container in which the intermediate product is located a preset pressure, the method further comprises: purging the intermediate product with carbon dioxide.

[0008] According to an embodiment of the present disclosure, before the intermediate product is heated to the second preset temperature for reaction under the carbon dioxide atmosphere, the method further comprises: cooling the intermediate product to a third preset temperature by air cooling.

[0009] According to an embodiment of the present disclosure, the first preset temperature is 180-300℃, and the reaction time at the first preset temperature is 1-6h.

[0010] According to an embodiment of the present disclosure, the second preset temperature is 450-550℃, and the reaction time at the second preset temperature is 2-6h.

[0011] According to an embodiment of the present disclosure, the preset pressure is 0.1-3Mpa.

[0012] According to an embodiment of the present disclosure, the heating rate of the container with the preset pressure to the second preset temperature is 2-20℃ / min.

[0013] According to an embodiment of the present disclosure, the coal tar comprises one of high-temperature coal tar, medium-temperature coal tar and low-temperature coal tar; and the surfactant comprises one of dodecyl trimethyl ammonium bromide, sodium dodecyl sulfate and cetyl trimethyl ammonium chloride.

[0014] The method for preparing light fuel oil in heavy oil delayed coking products according to the embodiment of the present disclosure has at least the following beneficial effects:

[0015] By incorporating coal tar and surfactant into the heavy oil system to improve the stability of the heavy oil colloid, and placing the reaction system in a carbon dioxide atmosphere, the generation of coke in delayed coking is inhibited and the yield of light fuel oil is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 A flow chart of the method for preparing light fuel oil in heavy oil delayed coking products according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that the description which follows is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it would be apparent to one skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known structures and techniques have not been described in detail in order to avoid obscuring aspects of the present disclosure.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the terms "comprises", "comprising", "includes", "including" and the like are specifically intended to be open-ended and to mean that other features, steps, operations, and / or components can be added.

[0020] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein are to be interpreted as having a meaning that is consistent with the understanding of a person of ordinary skill in the art, and should not be interpreted in an idealized or overly formal manner.

[0021] Figure 1 A flow chart of a method for preparing light fuel oil from a heavy oil delayed coking product according to an embodiment of the present disclosure is schematically shown.

[0022] As shown in Figure 1 The method for preparing light fuel oil from a heavy oil delayed coking product according to the embodiment includes:

[0023] In operation S110, a preset mass ratio of coal tar and surfactant is added to the heavy oil, and after stirring and mixing, a reaction is performed at a first preset temperature to prepare an intermediate product.

[0024] In operation S120, the intermediate product is heated to a second preset temperature under a carbon dioxide atmosphere to perform a reaction to obtain light fuel oil.

[0025] In the embodiment of the present disclosure, heavy oil is a complex mixture of hydrocarbons, mainly composed of macromolecular compounds with irregular structures, and its chemical structure contains alkanes, cycloalkanes, and polycyclic aromatic hydrocarbons, etc. According to industry standards, heavy oil can be divided into four components by polar separation method: saturated fraction, aromatic fraction, resin, and asphaltene.

[0026] Among them, asphaltene is the most polar, largest molecular weight and most complex structure component in heavy oil, usually accounting for 8%~15% of the total mass of heavy oil. As the core unstable factor of heavy oil colloidal system, the structural characteristics of asphaltene have a decisive influence on the stability of the whole system. About the molecular structure of asphaltene, two typical models have been proposed by the academic community: “continental model” and “archipelago model”. The former believes that asphaltene is composed of a highly condensed large aromatic nucleus, with multiple alkyl side chains connected to the periphery; the latter describes it as a cluster structure formed by multiple smaller aromatic nuclei connected to each other by bridges (such as methylene, sulfide bonds, etc.). In recent years, with the development of modern analysis technology, especially the research results based on Yen-Mullins model show that the asphaltene in most natural heavy oil tends to adopt the “continental type” structure, that is, a single core aromatic nucleus containing about seven fused aromatic rings as the main body, surrounded by several outwardly extending alkyl side chains. This molecular structure has a clear polar head (aromatic nucleus) and non-polar tail (side chain), with a molecular weight range of 500 Da~1000 Da, an average of about 750 Da.

[0027] In the original heavy oil system, asphaltene is uniformly dispersed in the continuous oil phase composed of saturates and aromatics in a colloidal state by the solvation of resin and aromatic components, forming a relatively stable thermodynamic metastable system. However, during thermal processing, temperature becomes the key factor driving chemical reactions, not only promoting the breaking of C-C and C-heteroatom bonds, but also significantly affecting the dissociation and recombination behavior of asphaltene aggregates.

[0028] With the increase of temperature, the alkyl side chains on the periphery of asphaltene gradually undergo cracking (dealkylation reaction), leading to a decrease in solubility and an increase in aromaticity. The intermolecular π-π interaction of the converted asphaltene increases, the affinity increases, and the compatibility with other components of the oil phase gradually decreases, making it prone to self-aggregation and forming nanoscale aggregates. When the residue conversion rate is low, these aggregates can still maintain dynamic balance and partially dissociate; but as the conversion depth increases, the dealkylation reaction continues, the aromaticity of the asphaltene core further increases, and the colloidal stability rapidly decreases, eventually forming highly aromatic solid precipitates—coke through polycondensation reaction.

[0029] Therefore, in the heavy oil delayed coking process, the formation of coke is essentially due to the excessive dealkylation of asphaltene at high temperature, the polycondensation of aromatic nuclei, and the resulting colloidal instability and phase separation. However, in the existing delayed coking of heavy oil, only process conditions such as reaction temperature can be adjusted, making it difficult to effectively adjust the colloidal stability of heavy oil and the reaction path of asphaltene, which not only reduces the yield of light fuel oil but also affects the long-term stable operation of the device.

[0030] Based on this, the embodiment improves the colloidal stability of heavy oil by mixing coal tar and surfactant into the heavy oil system, and places the reaction system in a carbon dioxide atmosphere, thereby inhibiting the formation of coke in delayed coking and improving the yield of light fuel oil.

[0031] Specifically, the asphaltene content in coal tar is low, and it has high colloidal stability. Mixing it into the heavy oil system can effectively improve the compatibility of the overall components and enhance the solvation of asphaltene. At the same time, with the addition of surfactant, it can reduce the interfacial tension by adsorbing on the oil-oil interface or the surface of asphaltene particles, exerting steric hindrance and electrostatic stabilization effect, further promoting the uniform dispersion of components in heavy oil, and significantly improving the colloidal stability of the system, thereby inhibiting the aggregation and phase separation of asphaltene and reducing the tendency of coke formation. In addition, coal tar is rich in phenolic compounds, alcohols and other oxygen-containing organic compounds, which can release active free radicals during pyrolysis, combined with the introduction of atmosphere, jointly regulate the free radical reaction path: on the one hand, promote the generation of unsaturated hydrocarbons and organic oxygen-containing compounds, on the other hand, inhibit excessive dehydrogenation and excessive breakage of alkyl side chains, reduce the generation of inorganic oxygen (such as CO, ), effectively block the transformation of asphaltene to highly condensed coke structure. At the same time, the sulfides, micron-sized carbon particles and inorganic mineral components contained in coal tar can act as dispersed condensation nuclei or growth nuclei during the reaction process, adsorb heavy oil macromolecular radicals, promote the formation of well-dispersed spherical coke precursors, and inhibit their further coalescence and growth, thereby reducing the overall coke yield.

[0032] On the basis of the above embodiment, the preset mass ratio of coal tar and surfactant is 1:(0.002~0.01).

[0033] In the embodiment of the present disclosure, within the mass ratio range, the addition amount of surfactant is sufficient to adsorb on the mixing interface of coal tar and heavy oil, effectively reduce the interfacial tension between the two phases, promote the uniform mixing and emulsification of coal tar and heavy oil, and form a stable microemulsion structure or micellar system. This helps to improve the dispersion state of asphaltene in the oil phase, prevent local enrichment or phase separation due to polarity difference, and thus significantly enhance the overall colloidal stability of the system.

[0034] On the basis of the above embodiment, under the carbon dioxide atmosphere, the intermediate product is heated to a second preset temperature for reaction, including: charging carbon dioxide into the intermediate product, so that the pressure of the container where the intermediate product is located is a preset pressure. Under stirring conditions, the container with the preset pressure is heated to a second preset temperature for reaction.

[0035] Based on the above embodiments, before introducing carbon dioxide into the intermediate product to make the pressure of the container containing the intermediate product reach a preset pressure, the method further includes: purging the intermediate product with carbon dioxide.

[0036] Furthermore, the number of purging cycles can be up to three, but is not limited to this.

[0037] In the embodiments of this disclosure, the presence of oxygen readily leads to uncontrolled condensation reactions of asphaltenes and resins, generating a large amount of precursor coke. Utilizing... Purging the reaction vessel and intermediate products thoroughly replaces the air (especially oxygen) in the system, completely eliminating the risk of free radical oxidation and localized overheating and coking caused by residual oxygen molecules at high temperatures. After purging, the system is then charged with... By establishing preset pressure, not only was an inert protective atmosphere maintained, but the pressure was also enhanced. Solubility and penetration in the oil phase.

[0038] According to embodiments of this disclosure, before heating the intermediate product to a second preset temperature for reaction in a carbon dioxide atmosphere, the method further includes: cooling the intermediate product to a third preset temperature using air cooling.

[0039] Furthermore, the third preset temperature can be room temperature.

[0040] In the embodiments of this disclosure, rapidly cooling the intermediate product to room temperature via air cooling effectively terminates the thermal reaction process in the pretreatment stage. During the initial mixing and activation process, partial weak dissociation or reorganization of the associated structures may occur between heavy oil, coal tar, and surfactants. Timely cooling can "lock in" the formed uniform dispersion system and stable colloidal structure, preventing premature aggregation of asphaltenes or uncontrollable condensation reactions due to the continued effect of residual heat. Simultaneously, the solid-liquid-gas interface is more stable at room temperature, which is beneficial for… Gradual dissolution and uniform distribution in the oil phase.

[0041] Based on the above embodiments, the first preset temperature is 180℃~300℃, and the reaction time at the first preset temperature is 1h~6h.

[0042] The second preset temperature is 450℃~550℃, and the reaction time at the second preset temperature is 2h~6h.

[0043] The preset pressure is 0.1 MPa to 3 MPa.

[0044] The heating rate for raising the container at the preset pressure to the second preset temperature is 2℃ / min to 20℃ / min.

[0045] According to embodiments of this disclosure, the coal tar includes one of high-temperature coal tar, medium-temperature coal tar, and low-temperature coal tar. The surfactant includes one of dodecyltrimethylammonium bromide, sodium dodecyl sulfate, and hexadecyltrimethylammonium chloride.

[0046] Furthermore, high-temperature coal tar is produced during the high-temperature dry distillation of coal at 900℃~1100℃.

[0047] Medium-temperature coal tar is produced by the pyrolysis of coal in the range of 600℃ to 800℃.

[0048] Low-temperature coal tar is produced by the pyrolysis of coal at a relatively low temperature of 450℃ to 600℃.

[0049] The present disclosure will be further described below through specific implementation methods.

[0050] Example 1

[0051] (1) Add 25g of heavy oil, 5g of medium-low temperature coal tar and 0.05g of dodecyltrimethylammonium bromide to the reactor and stir at 180°C for 1 hour to fully mix the heavy oil, low temperature coal tar and surfactant to form a uniform and stable intermediate product.

[0052] (2) After the reaction is complete, stop heating and stirring, and use air cooling to quickly reduce the temperature inside the reactor to room temperature.

[0053] (3) Subsequently, carbon dioxide gas is introduced into the reactor for purging, repeated three times, to completely remove residual air from the reactor and prevent oxygen from triggering an oxidation-condensation reaction at high temperatures, which could lead to coking. After purging, carbon dioxide is continuously introduced into the reactor. This raises the system pressure to 0.1 MPa, establishing a stable inert reaction atmosphere.

[0054] (4) Under the condition of stirring rate of 400 r / min, the reaction system was heated from room temperature to 450℃ at a heating rate of 2℃ / min, and the reaction was kept at this temperature for 2 hours to achieve deep pyrolysis conversion of heavy oil. After the reaction was completed, the reactor was rapidly cooled to room temperature again by air cooling to terminate the reaction and obtain the final product.

[0055] Tests showed that, compared to the traditional delayed coking process without the addition of coal tar and surfactants and carried out under a nitrogen atmosphere, the coke production in this embodiment was reduced by 99%, and the yield of light gasoline and diesel was increased by 60%.

[0056] Example 2

[0057] (1) Add 27g of heavy oil, 3g of high-temperature coal tar and 0.02g of sodium dodecyl sulfate to the reactor and stir at 200°C for 3 hours to fully mix the heavy oil, low-temperature coal tar and surfactant to form a uniform and stable intermediate product.

[0058] (2) After the reaction is complete, stop heating and stirring, and use air cooling to quickly reduce the temperature inside the reactor to room temperature.

[0059] (3) Subsequently, carbon dioxide gas is introduced into the reactor for purging, repeated three times, to completely remove residual air from the reactor and prevent oxygen from triggering an oxidation-condensation reaction at high temperatures, which could lead to coking. After purging, carbon dioxide is continuously introduced into the reactor. This raises the system pressure to 1 MPa, establishing a stable inert reaction atmosphere.

[0060] (4) Under the condition of stirring rate of 400 r / min, the reaction system was heated from room temperature to 500℃ at a heating rate of 10℃ / min, and the reaction was kept at this temperature for 3 hours to achieve deep pyrolysis conversion of heavy oil. After the reaction was completed, the reactor was rapidly cooled to room temperature by air cooling to terminate the reaction and obtain the final product.

[0061] Tests showed that, compared to the traditional delayed coking process without the addition of coal tar and surfactants and carried out under a nitrogen atmosphere, the coke production in this embodiment was reduced by 96%, and the yield of light gasoline and diesel was increased by 50%.

[0062] Example 3

[0063] (1) Add 25g of heavy oil, 5g of medium-temperature coal tar and 0.04g of hexadecyltrimethylammonium chloride to the reactor and stir at 300°C for 1 hour to fully mix the heavy oil, low-temperature coal tar and surfactant to form a uniform and stable intermediate product.

[0064] (2) After the reaction is complete, stop heating and stirring, and use air cooling to quickly reduce the temperature inside the reactor to room temperature.

[0065] (3) Subsequently, carbon dioxide gas is introduced into the reactor for purging, repeated three times, to completely remove residual air from the reactor and prevent oxygen from triggering an oxidation-condensation reaction at high temperatures, which could lead to coking. After purging, carbon dioxide is continuously introduced into the reactor. This raises the system pressure to 2 MPa, establishing a stable inert reaction atmosphere.

[0066] (4) Under the condition of stirring rate of 400 r / min, the reaction system was heated from room temperature to 550℃ at a heating rate of 5℃ / min, and the reaction was kept at this temperature for 6 hours to achieve deep pyrolysis conversion of heavy oil. After the reaction was completed, the reactor was rapidly cooled to room temperature by air cooling to terminate the reaction and obtain the final product.

[0067] Tests showed that, compared to the traditional delayed coking process without the addition of coal tar and surfactants and carried out under a nitrogen atmosphere, the coke production in this embodiment was reduced by 92%, and the yield of light gasoline and diesel was increased by 45%.

[0068] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A process for the production of light fuel oil from a heavy oil delayed coking product, characterized by, The application relates to a method for preparing light fuel oil from heavy oil. The method comprises the following steps: adding coal tar and a surfactant into heavy oil in a preset mass ratio, mixing, and then reacting at a first preset temperature to prepare an intermediate product; 2. The method of claim 1, wherein, under a carbon dioxide atmosphere, heating the intermediate product to a second preset temperature to react and obtain light fuel oil.

3. The method of claim 1, wherein, The preset mass ratio of the coal tar and the surfactant is 1:(0.002-0.01). The step of heating the intermediate product to the second preset temperature to react under the carbon dioxide atmosphere comprises the following steps: filling the intermediate product with carbon dioxide to make the pressure of a container containing the intermediate product reach a preset pressure; 4. The method of claim 3, wherein, under stirring, heating the container with the preset pressure to the second preset temperature to react. Before the step of filling the intermediate product with carbon dioxide to make the pressure of the container containing the intermediate product reach the preset pressure, the method further comprises the following step:

5. The method of claim 1, wherein, blowing the intermediate product with carbon dioxide. Before the step of heating the intermediate product to the second preset temperature to react under the carbon dioxide atmosphere, the method further comprises the following step:

6. The method of claim 1, wherein, cooling the intermediate product to a third preset temperature by air cooling.

7. The method of claim 1, wherein, The first preset temperature is 180-300 DEG C, and the reaction time at the first preset temperature is 1-6 hours.

8. The method of claim 3, wherein, The second preset temperature is 450-550 DEG C, and the reaction time at the second preset temperature is 2-6 hours.

9. The method of claim 3, wherein, The preset pressure is 0.1-3 MPa.

10. The method of claim 1, wherein, The heating rate of the container with the preset pressure to the second preset temperature is 2-20 DEG C / min. The coal tar comprises one of high-temperature coal tar, medium-temperature coal tar and low-temperature coal tar. The surfactant comprises one of dodecyl trimethyl ammonium bromide, sodium dodecyl sulfate and cetyl trimethyl ammonium chloride.

Images