Method for preparing clean fuel component through efficient conversion of ethylene tar
By adding composite chemical modifiers to ethylene tar and subjecting it to high-temperature and high-shear treatment, combined with precision fractionation and dehydration, ethylene tar was successfully converted into a high-yield, high-quality clean fuel, solving its instability and coking problems and improving its utilization rate and combustion performance.
Patent Information
- Application Number
- CN202511003498.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-12-09
AI Technical Summary
Ethylene tar has low utilization rate due to its instability and complex composition, easily causes equipment coking and blockage, and has poor combustion performance, polluting the environment.
By using composite chemical modifiers to break down the colloidal system of ethylene tar under high temperature and high shear conditions, combined with precision fractionation and dehydration, clean fuel components are separated.
This technology enables the efficient conversion of ethylene tar into high-value clean fuel oil, solves the coking problem, and improves utilization and combustion performance.
Smart Images
Figure CN121086809A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for the resource utilization of petrochemical byproducts, specifically a method for the efficient conversion of ethylene tar to prepare clean fuel components, belonging to the fields of petrochemical and clean energy technology. Background Technology
[0002] Ethylene tar is a heavy liquid byproduct generated during the high-temperature cracking of hydrocarbon feedstocks such as naphtha and light diesel oil in ethylene cracking units, resulting in side reactions such as condensation and cyclization. The production of ethylene tar is substantial, accounting for approximately 12%-15% of the total feedstock of ethylene plants. Figure 1 As shown, ethylene tar contains up to 52.24% aromatic hydrocarbons and 16.27% saturated hydrocarbons, all of which are potentially high-value fuel or chemical components. However, it also contains up to 10.71% gum and 20.78% asphaltenes, as well as a large amount of unsaturated components such as olefins and alkynes. This complex composition leads to technical challenges in utilizing ethylene tar, including poor compatibility, poor stability, and poor thermal stability. The chemical composition and molecular structure of ethylene tar differ greatly from conventional heavy oil products. According to the principle of "like dissolves like," the two are difficult to mix and easily separate after mixing, seriously affecting their usability as a blending component for fuel oil. The abundant olefins and alkynes, which are chemically active, are prone to self-polymerization and condensation reactions during storage or heating, generating new gums and asphaltenes, leading to increased oil viscosity, quality deterioration, and even equipment blockage. During the heat exchange and heating process, the complex colloidal system of ethylene tar, composed of gums and asphaltenes, becomes unstable, leading to the aggregation and coking of primary and secondary asphaltenes, which adhere to the heat exchange tubes and tower walls. In severe cases, this can cause furnace tube burn-through or fractionation tower blockage, resulting in safety accidents. For these reasons, the utilization rate of ethylene tar is currently generally low, with most being burned directly as low-quality fuel. This not only has low economic value but also pollutes the environment due to its poor combustibility, low calorific value, and tendency to produce black smoke.
[0003] Therefore, how to utilize ethylene tar as a resource through an economical, efficient, and environmentally friendly technology is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0004] Based on the above background, the purpose of this invention is to provide a method for efficiently converting ethylene tar into clean fuel components, which can disrupt the unstable system of ethylene tar and efficiently separate clean fuel components.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] A method for efficiently converting ethylene tar into clean fuel components, the method comprising the following steps:
[0007] S1. The ethylene tar feedstock is reacted with a composite chemical modifier consisting of a coupling agent and a dispersant in a reactor at a temperature of 80-110℃ and a high shear rate for 1.5-2.5 hours to destroy the original aromatic hydrocarbon-colloidal-asphaltene colloidal system in the ethylene tar and to selectively pre-precipitate the heavy components in the form of particles, thereby obtaining a modified ethylene tar mixture.
[0008] S2. The modified ethylene tar mixture is first fed into a sedimentation separation device to separate and remove the heavy phase rich in colloidal coke powder at the bottom. Then the upper liquid phase is sent into a dehydration tower for dehydration treatment to obtain dehydrated modified tar.
[0009] S3. The dehydrated modified tar is fed into a multi-stage vacuum distillation column system with at least one side-stream extraction point. Precision fractionation is carried out under the conditions of column bottom temperature of 340-370℃ and column top absolute pressure of 1-10 KPa. Light fuel oil components with a boiling range of less than 200℃ are extracted from the column top, medium fuel oil components with a boiling range of 200-350℃ are extracted from the side-stream extraction point, and heavy fuel oil components are extracted from the column bottom.
[0010] By actively breaking down the unstable colloidal system of ethylene tar feedstock using chemical methods, the gums and asphaltenes are pre-precipitated, thus creating excellent conditions for subsequent physical separation and fractionation, and solving the problems of coking and clogging.
[0011] Preferably, in step S1, the coupling agent is at least one nonionic surfactant selected from long-chain fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether; the dispersant is at least one ashless dispersant selected from polyisobutylene succinimide and high molecular weight PIBSA-PAM.
[0012] The lipophilic and hydrophilic groups of the coupling agent can effectively intervene and disrupt the colloidal structure, while the long-chain dispersant can encapsulate the precipitated heavy particles, preventing them from re-aggregating, thus ensuring the modification effect on ethylene tar feedstock.
[0013] Preferably, in step S1, the total amount of the composite chemical modifier added is 1.0-3.0% relative to the mass of the ethylene tar feedstock, wherein the mass ratio of the coupling agent to the dispersant is 1-2:1-2.
[0014] Preferably, in step S2, the dehydration tower is operated under normal pressure or slightly negative pressure, the top temperature of the dehydration tower is controlled at 100-150℃, and the bottom temperature of the dehydration tower is controlled at 160-190℃.
[0015] The dehydration step aims to efficiently remove free water and emulsified water entrained in the feedstock, while precise temperature control prevents valuable light fuel oil components from being carried away with water vapor.
[0016] Preferably, in step S2, the upper liquid phase separated from the sedimentation separation device is first cooled to 40-60°C by a heat exchanger before being sent to the dehydration tower, and then sent to an intermediate buffer tank for secondary sedimentation for at least 30 minutes.
[0017] By taking advantage of the fact that some heavy colloids have lower solubility at low temperatures, they are induced to precipitate further through active cooling, thereby removing more potential coking precursors before entering the distillation column.
[0018] Preferably, in step S3, the top reflux ratio of the multi-stage vacuum distillation column system is 0.5-2.0.
[0019] By controlling the reflux ratio within the aforementioned specific range, an optimal balance between separation accuracy and energy consumption can be achieved.
[0020] Preferably, in step S3, a portion of the heavy fuel oil component extracted from the bottom of the tower is cooled and returned to the reactor as a diluent, where it participates in the reaction together with the ethylene tar feedstock and the composite chemical modifier.
[0021] The returned heavy oil is a relatively stable component. As a diluent, it can effectively reduce the viscosity of the feed and improve the mixing and heat transfer effects. At the same time, as a solvent, it helps to better disperse the composite chemical modifier and improve the reaction efficiency.
[0022] Preferably, the mass of the heavy fuel oil component returned to the reactor as a diluent is 10-30% of the mass of the ethylene tar feedstock.
[0023] Preferably, in step S3, the heavy fuel oil component with a temperature of 340-370°C extracted from the bottom of the tower is preheated to 60-80°C by exchanging heat with the ethylene tar feedstock before entering the reactor through a feedstock preheating heat exchanger before being sent to the storage tank or for further processing.
[0024] High-temperature waste heat at the end of the process is used to preheat low-temperature raw materials at the beginning of the process, realizing the cascade utilization of energy and significantly reducing the total energy consumption of the system.
[0025] Preferably, before step S1, the method further includes the following steps:
[0026] The ethylene tar feedstock is preheated to 60-80°C and premixed with the composite chemical modifier in a static mixer.
[0027] Preheating reduces the viscosity of the raw materials, while the static mixer achieves the initial uniform dispersion of additives with extremely low energy consumption.
[0028] Compared with the prior art, the present invention has the following advantages:
[0029] This invention discloses a method for the efficient conversion of ethylene tar into clean fuel components. By pre-separating unstable components from the ethylene tar feedstock through chemical modification, the risk of coking during subsequent heat treatment is completely eliminated, ensuring long-term safe and stable operation of the equipment. Through precise temperature control and the recycling of energy and materials, this method maximizes the conversion of ethylene tar into high-value clean fuel oil, achieving a high product yield. This method significantly improves the utilization value of ethylene tar, efficiently producing light and medium-quality fuel oil components with high cleanliness, good combustion performance, and better compatibility with conventional fuel oils. These components can be used as high-quality fuel oil blending components or further as high-quality raw materials for the production of fine chemicals such as rubber fillers, carbon black anode materials, high-end adhesives, coated asphalt raw materials, and green energy fuel oils. Attached Figure Description
[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0031] Figure 1 This is a diagram illustrating the basic properties of the ethylene tar feedstock used in this invention.
[0032] Figure 2 This is a process flow diagram of a method for efficiently converting ethylene tar to prepare clean fuel components according to the present invention;
[0033] Figure 3 This is a comparison diagram of the ethylene tar feedstock before and after the destabilization and upgrading reaction in this invention. Detailed Implementation
[0034] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.
[0035] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art. Unless otherwise specified, the components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.
[0036] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this detailed description, numerous specific details are set forth to facilitate explanation and provide a thorough understanding of the embodiments of the present invention. However, one or more embodiments may be practiced by those skilled in the art without these specific details.
[0037] The present invention discloses a method for the efficient conversion of ethylene tar to prepare clean fuel components, the method comprising the following steps:
[0038] S1. The ethylene tar feedstock is reacted with a composite chemical modifier consisting of a coupling agent and a dispersant in a reactor at a temperature of 80-110℃ and a high shear rate for 1.5-2.5 hours to destroy the original aromatic hydrocarbon-colloidal-asphaltene colloidal system in the ethylene tar and to selectively pre-precipitate the heavy components in the form of particles, thereby obtaining a modified ethylene tar mixture.
[0039] S2. The modified ethylene tar mixture is first sent to a settling separation device to separate and remove the heavy phase rich in colloidal coke powder at the bottom. Then the upper liquid phase is sent to a dehydration tower for dehydration treatment to obtain dehydrated modified tar.
[0040] S3. The dehydrated modified tar is fed into a multi-stage vacuum distillation column system with at least one side-stream extraction point. Precision fractionation is carried out under the conditions of column bottom temperature of 340-370℃ and column top absolute pressure of 1-10 KPa. Light fuel oil components with boiling range below 200℃ are extracted from the column top, medium fuel oil components with boiling range of 200-350℃ are extracted from the side-stream extraction point, and heavy fuel oil components are extracted from the column bottom.
[0041] The following describes in detail the entire process of treating ethylene tar, a byproduct of an ethylene plant, using the method of this invention. The basic properties of the raw material, ethylene tar, are as follows: Figure 1 As shown, its density (20℃) is 1.0798 g / cm³, its resin content is 10.71%, and its asphaltene content is 20.78%. The process flow for the efficient conversion of ethylene tar into clean fuel components is as follows: Figure 2 As shown.
[0042] Step S1: Raw material pretreatment and destabilization and upgrading reaction.
[0043] S11. Heat Integration and Preheating: First, the ambient temperature ethylene tar feedstock is pumped to the feedstock preheating heat exchanger. Simultaneously, a high-temperature heavy fuel oil component (approximately 350°C) collected from the bottom of the subsequent vacuum distillation column is also introduced into the same heat exchanger. The two components exchange heat, preheating the ethylene tar feedstock to 75°C. This process recovers the waste heat from the high-temperature product, saving a significant amount of energy.
[0044] S12. Premixing: The preheated ethylene tar feedstock, together with the composite chemical modifier, is fed into a static mixer. In this embodiment, the total amount of the composite chemical modifier added is 1.8% of the ethylene tar mass. This modifier is composed of alkylphenol polyoxyethylene ether as a coupling agent and polyisobutylene succinimide as a dispersant, mixed at a mass ratio of 1:1.5. In the static mixer, the ethylene tar feedstock and the composite chemical modifier achieve preliminary macroscopic uniform mixing.
[0045] S13, High-shear reaction: The premixed materials are fed into the reactor. The reactor is equipped with a high-shear dispersing emulsifier and is jacketed for heating. The temperature inside the reactor is controlled at 95℃, and the reaction is continued for 2 hours under high-shear conditions.
[0046] The optimal reaction temperature range is 80-110℃. Below 80℃, reaction kinetics are insufficient, viscosity is high, and the effect is poor; above 110℃, there is a risk of initiating the thermal polymerization of the raw materials themselves. A reaction time of 1.5-2.5 hours ensures that the coupling agent has sufficient time to penetrate and disrupt the colloidal structure, and the dispersant has sufficient time to coat the precipitated particles. High shear force provides strong mechanical energy, breaking the modifier into micron-sized droplets, greatly increasing the interphase contact area, thereby achieving efficient destabilization and modification.
[0047] Step S2: Physical separation.
[0048] S21. Primary Settling: The modified mixture obtained in the reactor is sent to a settling separator. It remains there for approximately 2 hours, where gravity separation is used. During this process, the denser colloidal powdery substance precipitated after the colloidal system is disrupted settles to the bottom and is discharged as the heavier phase. Figure 3 As shown, it can be clearly observed that black ethylene tar ( Figure 3 After modification, the mixture (on the left) clearly separated into an upper oil phase, a lower aqueous phase, and a bottom precipitate of colloidal coke powder. Figure 3 (Right side).
[0049] S22. Secondary Sedimentation: The upper liquid phase from the sedimentation separation unit is pumped out and cooled from approximately 90°C to 50°C via an intermediate heat exchanger. It is then transferred to an intermediate buffer tank for secondary sedimentation, with a residence time of 45 minutes. The purpose of cooling is to induce precipitation by utilizing the principle that some critical heavy components, which are still soluble at high temperatures, have reduced solubility at low temperatures. 40-60°C is the optimal range that balances precipitation efficiency and energy consumption. This process removes more impurities, ensuring the safe operation of subsequent distillation units.
[0050] S23. Dehydration Treatment: The supernatant after secondary sedimentation is fed into a dehydration tower. The tower top temperature is controlled at 120℃ and the tower bottom temperature at 180℃, operating under atmospheric pressure. Water vapor is discharged from the top of the tower, and the dehydrated modified tar is collected from the tower bottom. The tower top temperature of 100-150℃ is sufficient to completely vaporize the water, while the tower bottom temperature of 160-190℃ ensures that the oil has good fluidity, facilitating pumping, while preventing the light oil components with boiling points close to 200℃ from vaporizing in large quantities, thus avoiding product loss.
[0051] Step S3: Precision vacuum fractionation.
[0052] S31. Distillation Operation: The dehydrated modified tar is fed into a vacuum distillation column. The absolute pressure at the top of the column is controlled at 5 kPa, the bottom temperature at 350°C, and the reflux ratio at the top of the column is set to 1.2.
[0053] Ethylene tar contains a large number of high-boiling-point components, and excessively high separation temperatures under normal pressure can lead to cracking and coking. Using reduced pressure significantly lowers the actual boiling point of the material, enabling effective separation at a relatively safe temperature of 350°C. A reflux ratio at the top of the column is set to 1.2 to ensure product separation accuracy while controlling energy consumption.
[0054] S32. Product Collection and Material Circulation: Light fuel oil components with a boiling range below 200℃ are collected from the top of the tower; medium fuel oil components with a boiling range of 200-350℃ are collected from the side collection point in the middle of the tower; and heavy fuel oil components with a boiling range above 350℃ are collected from the bottom of the tower. The heavy fuel oil components collected from the bottom of the tower are diverted. Approximately 20% of the heavy fuel oil components entering the reactor are cooled by heat exchange and then pumped into the reactor as a diluent to mix with the fresh feedstock.
[0055] The final fractionated products obtained using the above method were analyzed, and the light fuel oil component yielded 11%, with a density of 0.811 and a distillation range of HK-200℃; the medium fuel oil component yielded 67%, with a density of 0.936 and a distillation range of 200-350℃. The residual heavy fuel oil component, after deducting the recycled amount, yielded 22%.
[0056] This method successfully and efficiently converts low-value, unstable ethylene tar into high-yield, high-quality clean fuel oil components. The entire process is stable, controllable, and free from coking.
[0057] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A method for efficiently converting ethylene tar into clean fuel components, characterized in that: The method includes the following steps: S1. The ethylene tar feedstock is reacted with a composite chemical modifier consisting of a coupling agent and a dispersant in a reactor at a temperature of 80-110℃ and a high shear rate for 1.5-2.5 hours to destroy the original aromatic hydrocarbon-colloidal-asphaltene colloidal system in the ethylene tar and to selectively pre-precipitate the heavy components in the form of particles, thereby obtaining a modified ethylene tar mixture. S2. The modified ethylene tar mixture is first fed into a sedimentation separation device to separate and remove the heavy phase rich in colloidal coke powder at the bottom. Then the upper liquid phase is sent into a dehydration tower for dehydration treatment to obtain dehydrated modified tar. S3. The dehydrated modified tar is fed into a multi-stage vacuum distillation column system with at least one side-stream extraction point. Precision fractionation is carried out under the conditions of column bottom temperature of 340-370℃ and column top absolute pressure of 1-10 KPa. Light fuel oil components with a boiling range of less than 200℃ are extracted from the column top, medium fuel oil components with a boiling range of 200-350℃ are extracted from the side-stream extraction point, and heavy fuel oil components are extracted from the column bottom.
2. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S1, the coupling agent is at least one nonionic surfactant selected from long-chain fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether; the dispersant is at least one ashless dispersant selected from polyisobutylene succinimide and high molecular weight PIBSA-PAM.
3. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S1, the total amount of the composite chemical modifier added is 1.0-3.0% relative to the mass of the ethylene tar feedstock, wherein the mass ratio of the coupling agent to the dispersant is 1-2:1-2.
4. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S2, the dehydration tower operates under normal pressure or slightly negative pressure, the temperature at the top of the dehydration tower is controlled at 100-150℃, and the temperature at the bottom of the dehydration tower is controlled at 160-190℃.
5. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S2, the upper liquid phase separated from the sedimentation separation device is first cooled to 40-60°C by a heat exchanger before being sent to the dehydration tower, and then sent to an intermediate buffer tank for secondary sedimentation for at least 30 minutes.
6. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S3, the top reflux ratio of the multi-stage vacuum distillation column system is 0.5-2.
0.
7. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S3, a portion of the heavy fuel oil component extracted from the bottom of the tower is cooled and returned to the reactor as a diluent, where it participates in the reaction together with the ethylene tar feedstock and the composite chemical modifier.
8. The method for efficiently converting ethylene tar into clean fuel components according to claim 7, characterized in that: The mass of the heavy fuel oil component returned to the reactor as a diluent is 10-30% of the mass of the ethylene tar feedstock.
9. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: In step S3, the heavy fuel oil component with a temperature of 340-370°C extracted from the bottom of the tower is preheated to 60-80°C by exchanging heat with the ethylene tar feedstock before entering the reactor through a feedstock preheating heat exchanger before being sent to the storage tank or for further processing.
10. The method for efficiently converting ethylene tar to prepare clean fuel components according to claim 1, characterized in that: Prior to step S1, the method further includes the following steps: The ethylene tar feedstock is preheated to 60-80°C and premixed with the composite chemical modifier in a static mixer.