Process for preparing crude fuel oil by hydrogenation of all fractions of ethylene tar

Abstract

The invention relates to a process for preparing crude fuel oil by hydrogenation of all fractions of ethylene tar. The method comprises the following steps: (1) adding a reaction improvement emulsifying additive into ethylene tar, fully stirring to reduce the viscosity of raw oil, mixing with hydrogen, feeding into a hydrogenation reactor, and carrying out hydrotreatment under the action of a hydrogenation catalyst to obtain an oil-gas mixture of a hydrogenation reaction effluent; (2) feeding an oil-gas mixture of a hydrogenation reaction effluent into a high-pressure separator, and separating to obtain gas and mixed product oil; and (3) distilling and cutting the mixed product oil to obtain a crude aromatic gasoline component and a crude diesel oil component. The method has the characteristics that the hydrogenation process is simple, the reaction conditions are mild, and the catalyst is not easy to coke and inactivate.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogenation of inferior oil products, and particularly relates to a process for preparing crude fuel oil by hydrogenating a full fraction of ethylene tar. Background Art

[0002] Steam cracking of naphtha and diesel fuels is a common process for producing ethylene in the petrochemical industry. During ethylene production, a certain amount of ethylene tar is produced. This product, formed by the high-temperature condensation of the raw materials and products during the steam cracking process, accounts for approximately 15-20% (by weight) of the ethylene output. Ethylene tar primarily consists of C9-C90 fractions, with aromatics accounting for over 60% by weight. These aromatics are primarily a mixture of condensed aromatic hydrocarbons with two or more rings. These components, such as indene, methylnaphthalene, ethylnaphthalene, dimethylnaphthalene, anthracene, acenaphthene, and phenanthrene, are present at high levels. The product is low in ash and heavy metals, and generally appears as a viscous liquid with poor fluidity. Its composition varies depending on the cracking feedstock and cracking conditions. Ethylene tar is generally characterized by a complex composition and high levels of aromatics, olefins, and asphaltenes. Most refineries lack the processing technology for ethylene tar, impacting the economic viability of the entire plant.

[0003] Most international research on ethylene tar has focused on using it to produce mesophase pitch, asphalt resin, extract naphthalene, and prepare carbonaceous precursors. Some researchers have also used ethylene tar as an additive in the viscosity reduction process for vacuum residue or as a precursor for preparing mesoporous carbon-based solid acid catalysts. These advanced processing techniques can increase the added value of ethylene tar and improve the economic efficiency of the entire steam cracking unit. Furthermore, ethylene tar can be subjected to a two-stage catalytic hydrogenation process to produce fuel oil with a sulfur content of less than 10 ppm and a nitrogen content of less than 2 ppm. Because ethylene tar has a relatively complex composition, conventional hydrogenation processes require it to be distilled and cut, with the lighter fractions selected for hydrorefining to produce fuel oil. The heavier deasphalted oil and deoiled asphalt are then used as raw materials for the subsequent production and processing of carbonaceous materials such as carbon fiber pitch and coated asphalt. While this process can achieve good hydrogenation reaction results, it is still relatively complex, resulting in high costs for the pre-treatment of ethylene tar, which affects the economic efficiency of the entire process.

[0004] From the current research status of the existing technology, there is no report on hydrogenating the whole fraction of ethylene tar to produce crude fuel oil. Summary of the Invention

[0005] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a process for hydrogenating the whole fraction of ethylene tar to produce crude fuel oil, which has the characteristics of simple hydrogenation process, relatively mild reaction conditions, and catalyst not easily coked and deactivated.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar comprises the following steps:

[0008] Step (1): Add reaction-improving emulsifying additives:

[0009] A reaction-improving emulsifying additive is added to ethylene tar, and after sufficient stirring, the viscosity of the raw oil is reduced. The raw oil is then mixed with hydrogen and fed into a hydrogenation reactor for hydrogenation treatment under the action of a hydrogenation catalyst to obtain an oil-gas mixture as the effluent of the hydrogenation reaction.

[0010] Step (2): High-pressure separation:

[0011] The oil-gas mixture of the hydrogenation reaction effluent enters the high-pressure separator, and after separation, gas and mixed product oil are obtained;

[0012] Step (3): distilling and cutting the mixed product oil to obtain a crude aromatic gasoline component and a crude diesel component.

[0013] The reaction-improving emulsifying additive in step (1) is sorbitan fatty acid ester (trade name: Span-80).

[0014] The reaction improving emulsifying additive in step (1) accounts for 300 to 600 μg / g of the mass fraction of ethylene tar. Within this temperature, pressure, space velocity, and hydrogen-to-oil ratio range, the hydrogenation effect of ethylene tar is better.

[0015] In the step (1), the temperature range of the hydrogenation reaction is 320-380°C, the reaction pressure is 5.0-7.0 MPa, and the ethylene tar volume space velocity is 0.5-1.0 h -1 , the volume ratio of hydrogen to oil is 500-800:1.

[0016] In step (2), the high-pressure separator is operated at a temperature of 310-370°C and a pressure of 4.9-6.9 MPa. The addition of an emulsifier in an amount of 300-600 μg / g can enhance the fluidity of the ethylene tar while preventing the introduction of excessive foreign matter into the tar, thereby altering the basic properties of the feedstock oil.

[0017] In the step (3), the distillation cut-off temperature of the mixed product oil is 205° C., the component below 205° C. is the crude aromatic gasoline fraction, and the component above 205° C. is the crude diesel fraction.

[0018] Asphaltenes contained in ethylene tar are thick condensation polymers that undergo free radical polymerization during hydrogenation, particularly at high temperatures. This self-association reaction increases the molecular weight of the asphaltenes, forming self-aggregate particles resembling layered carbon. These particles have high viscosity and density, leading to coking and deactivation of hydrogenation reactors, pipelines, and catalysts.

[0019] The present invention mixes a reaction-improving emulsifying additive with ethylene tar before the hydrogenation reaction. The additive can break up the network structure formed by the aggregation of asphaltene and asphalt gum or colloid, thereby reducing the viscosity of ethylene tar, enhancing the compatibility of asphaltene in feed oil, reducing the coking precipitation rate in the reactor and pipeline, and delaying the rate of catalyst coking deactivation, thereby improving the conditions for the hydrogenation reaction of the full fraction of ethylene tar and facilitating the hydrogenation reaction.

[0020] The hydrogenation reaction uses a fixed-bed hydrogenation reactor, and the hydrogenation catalyst is a commercial hydrogenation catalyst commonly used in the residual oil or diesel hydrogenation process, among which hydrocracking or hydrorefining catalysts have the best performance.

[0021] Beneficial effects of the present invention:

[0022] (1) The ethylene tar full fraction hydrotreating process of the present invention overcomes the limitations of the existing ethylene tar fixed bed hydrotreating technology on feedstock oil indicators and has the characteristics of simple process steps, mild reaction conditions and low investment.

[0023] (2) The present invention uses a reaction-improving emulsifying additive mixed with ethylene tar. The addition of the additive can dismantle the network structure formed by the aggregation of components such as asphaltene and colloid, and can dismantle the macromolecules such as asphaltene and colloid in the ethylene tar, preventing their polycondensation, thereby increasing fluidity and shortening the catalyst coking time. This reduces the viscosity of the feedstock oil, slows the rate of coking sedimentation in the pipeline and reactor, and delays the rate of catalyst coking deactivation, thereby enhancing the hydrogenation conversion performance of ethylene tar. DETAILED DESCRIPTION

[0024] The preparation method of the present invention is described in detail below through specific examples, but the protection scope of the present invention is not limited to these examples.

[0025] The raw oil used in the examples is the by-product tar from a domestic ethylene plant. The properties of the raw oil are shown in Table 1 below.

[0026] The catalyst used in the examples is the diesel hydrogenation catalyst FHUDS-8 developed by the Dalian Research Institute of Petrochemicals of Sinopec; the reaction-improving emulsifying additive used is sorbitan fatty acid ester (trade name Span-80).

[0027] Table 1. Analysis of properties of ethylene tar feedstock oil

[0028] project Analyze the values <![CDATA[Kinematic viscosity (50 °C) / mm 2 .s -1 > <![CDATA[Density (15 °C) / Kg.m -3 > Sulfur content / wt% Asphaltene / wt% Distillation range / ℃ / Initial distillation point 10％ 30％ 50％ 84％ Do something Cleanliness

[0029] Example 1

[0030] The ethylene tar listed in Table 1 was mixed with a reaction-improving emulsifying additive, sorbitan anhydride fatty acid ester, at a rate of 300 μg / g of the feedstock. After the addition of the additive, the mixture was thoroughly stirred and then placed in a fixed-bed hydrogenation reactor for hydrogenation in the presence of a hydrogenation catalyst. The hydrogenation reaction conditions were: a reaction temperature of 380°C, a reaction pressure of 5.0 MPa, an ethylene tar volumetric space velocity of 0.5 h⁻¹, a hydrogen-to-oil volume ratio of 600:1, and a FHUDS-8 catalyst. The high-pressure separator was maintained at a temperature of 370°C and a pressure of 4.9 MPa to yield gas and a hydrogenation reaction oil. The hydrogenation reaction oil was then distilled at a cutoff temperature of 205°C. Temperatures below 205°C yielded crude aromatic gasoline, while those above 205°C yielded crude diesel. The cutoff product oil was weighed, and the yields of the corresponding distillates were calculated.

[0031] Example 2

[0032] The ethylene tar listed in Table 1 was mixed with the reaction-improving emulsifying additive, sorbitan anhydride fatty acid ester, at a rate of 600 μg / g of the raw oil. After the addition of the additive, the mixture was thoroughly stirred and set aside for further use. The ethylene tar with the emulsifying additive was mixed with hydrogen and then introduced into a fixed-bed hydrogenation reactor for hydrogenation in the presence of a hydrogenation catalyst. The hydrogenation reaction conditions were: a reaction temperature of 350°C, a reaction pressure of 6.0 MPa, and an ethylene tar volumetric space velocity of 1.0 h / min. -1 The hydrogen-to-oil volume ratio is 500:1, and the hydrogenation catalyst is FHUDS-8. The high-pressure separator temperature is 340°C and the pressure is 5.9 MPa. After separation, the gas and hydrogenation reaction oil are obtained. The hydrogenation reaction oil is then distilled at a cutoff temperature of 205°C. Below 205°C, the crude aromatic gasoline component is obtained, while above 205°C, the crude diesel component is obtained. The product oil after the cutoff is weighed, and the yield of the corresponding distillate is calculated.

[0033] Example 3

[0034] The ethylene tar listed in Table 1 was mixed with the reaction-improving emulsifying additive, sorbitan anhydride fatty acid ester, at a rate of 450 μg / g of the feedstock. After the addition of the additive, the mixture was thoroughly stirred and then placed in a fixed-bed hydrogenation reactor for hydrogenation in the presence of a hydrogenation catalyst. The hydrogenation reaction conditions were: a reaction temperature of 320°C, a reaction pressure of 7.0 MPa, an ethylene tar volumetric space velocity of 0.6 h⁻¹, a hydrogen-to-oil volume ratio of 800:1, and a FHUDS-8 catalyst. The high-pressure separator was maintained at a temperature of 310°C and a pressure of 6.9 MPa. Gas and hydrogenation reaction oil were separated. The hydrogenation reaction oil was then distilled at a cutoff temperature of 205°C. Temperatures below 205°C were classified as crude aromatic gasoline, while temperatures above 205°C were classified as crude diesel. The cutoff product oil was weighed, and the yields of the corresponding distillates were calculated.

[0035] Comparative Example

[0036] Using the ethylene tar listed in Table 1 as the starting material, without the addition of the reaction-improving emulsifying additive, sorbitan anhydride fatty acid ester, a full-fraction hydrogenation reaction was conducted using the same procedures as described in Example 1. The results showed that the catalyst rapidly deactivated due to coking, and after 12 hours of reaction, the fixed-bed reactor showed significant blockage and coking, leading to the termination of the reaction.

[0037] Table 2. Ethylene tar hydrogenation reaction conditions and the yields of gasoline and diesel components after distillation and cutting of the product oil.

[0038]

[0039]

[0040] As shown in Table 2, compared to the comparative example of the ethylene tar hydrogenation experiment without any reaction-improving emulsifying additive, the ethylene tar in each embodiment, after undergoing fixed-bed hydrogenation, after adding a certain amount of sorbitan anhydride fatty acid ester (Span-80), exhibited significantly lower kinematic viscosity and higher desulfurization rates. The product oils were distilled and cut to yield a crude gasoline fraction below 205°C and a crude diesel fraction above 205°C. This demonstrates that the reaction-improving emulsifying additive can break up the network structure formed by the aggregation of components such as asphaltenes and colloids in the tar, thereby reducing the viscosity of the feedstock, enhancing the compatibility of asphaltenes and colloids in the feedstock, reducing the flow resistance of the ethylene tar, lowering the rate of coking and precipitation in the reactor and pipelines, and delaying the coking and deactivation of the hydrogenation catalyst, thereby improving the conditions for the ethylene tar hydrogenation reaction and facilitating the reaction.

Claims

1. A process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar, characterized in that: The following steps are included: Step (1): adding a reaction-improving emulsifying additive to ethylene tar, stirring the tar sufficiently to reduce the viscosity of the crude oil, mixing the crude oil with hydrogen, and then entering a hydrogenation reactor to undergo hydrogenation treatment under the action of a hydrogenation catalyst to obtain an oil-gas mixture as a hydrogenation reaction effluent; Step (2): the oil-gas mixture of the hydrogenation reaction effluent enters a high-pressure separator to obtain gas and mixed product oil after separation; Step (3): distilling and cutting the mixed product oil to obtain a crude aromatic gasoline component and a crude diesel component.

2. The process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar according to claim 1, characterized in that: The reaction-improving emulsifying additive in step (1) is sorbitan fatty acid ester.

3. The process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar according to claim 1, characterized in that: The reaction improving emulsifying additive in the step (1) accounts for 300 to 600 μg / g of the mass fraction of the ethylene tar.

4. The process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar according to claim 1, characterized in that: In the step (1), the temperature range of the hydrogenation reaction is 320-380°C, the reaction pressure is 5.0-7.0 MPa, and the ethylene tar volume space velocity is 0.5-1.0 h -1 , the volume ratio of hydrogen to oil is 500-800:

1.

5. The process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar according to claim 1, characterized in that: In the step (2), the operating conditions of the high-pressure separator are a temperature of 310 to 370° C. and a pressure of 4.9 to 6.9 MPa.

6. The process for preparing crude fuel oil by hydrogenating the whole fraction of ethylene tar according to claim 1, characterized in that: In the step (3), the distillation cut-off temperature of the mixed product oil is 205° C., the component below 205° C. is the crude aromatic gasoline fraction, and the component above 205° C. is the crude diesel fraction.

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