A two-stage extraction and secondary regeneration alpha olefin extraction apparatus

Abstract

The utility model discloses a two-stage extraction and secondary regeneration alpha olefin extraction device belongs to the technical field of extraction equipment. The device includes sequentially communicating primary extraction tower, primary extraction phase buffer tank, primary regeneration tower, secondary extraction tower, secondary extraction phase buffer tank, secondary regeneration tower, qualified oil product buffer tank, condensation recovery system and precision filter etc. component. Through two-stage extraction and secondary regeneration design, combine vacuum distillation (-0.08~0.095MPa, 150~180 DEG C) and precision filtration (0.1 micrometre ceramic membrane, 0.25 micrometre polytetrafluoroethylene filter core), realized oxygen compound removal rate >99%, alpha-olefin yield is 98%, and product purity reaches 99.5% or more. The device adopts double closed loop circulating system, and extraction agent recycling utilization rate >95%, and energy consumption reduces 40%, and waste liquid toxicity reduces 90%, solves the problem such as low efficiency, high energy consumption, and incomplete regeneration in traditional process, is applicable to the high -efficient purification of alpha-olefin in coal -based fischer -tropsch synthesis oil.

Description

Technical Field

[0001] This utility model relates to the technical field of extraction equipment, specifically to an α-olefin extraction device with two-stage extraction and secondary regeneration. Background Technology

[0002] In coal-based Fischer-Tropsch synthesis, α-olefins (such as C8–C4) are used in the synthesis of α-olefins. 12 Fischer-Tropsch synthesis oils are key raw materials for the production of high-value-added chemicals, such as polyalphaolefin lubricants and comonomers. However, Fischer-Tropsch synthesis oils contain 1–5 wt% oxygen-containing compounds (such as alcohols, aldehydes, ketones, and esters), which can poison subsequent polymerization catalysts and reduce product quality. Current technologies mainly rely on solvent extraction to remove oxygen-containing compounds.

[0003] The search revealed that existing technologies still have some defects and shortcomings:

[0004] 1. Single-stage extraction has low efficiency and results in significant loss of α-olefins;

[0005] Patent CN115745727A (Separation of C6–C from Fischer-Tropsch oil) 12 The study described the use of multi-stage distillation followed by extractive distillation for α-olefins, but the yield was only 85–90%, and the co-solubility of the extractant (such as NMP) with α-olefins led to a loss of >10%. Wang Yadong et al., in their paper "Advances in α-olefin separation technology from Fischer-Tropsch synthetic oils" (Chemical Industry and Engineering Progress, 2020), pointed out that single-stage extraction is less effective for C8–C4 olefins. 12 The selectivity coefficient for α-olefins is only 1.5–2.0 (>5 is required for efficient separation).

[0006] 2. Incomplete regeneration of the extractant results in poor cycle stability;

[0007] Patent CN118515523A (eutectic solvent extraction) describes that after vacuum flash regeneration, the residual oxygen-containing compounds in the solvent are 0.1–0.3 wt%, which leads to a decrease in the α-olefin yield from 95.2% to 84.9% after five reuses. The article Smith et al. Industrial & Engineering Chemistry Research (2018) confirms that the oxygen-containing compounds pyrolyze during the regeneration process to form colloids, which clog the regeneration tower.

[0008] 3. The equipment is complex and consumes a lot of energy;

[0009] Patent CN103232313A (Alkane / Olefin Extraction) describes multi-stage countercurrent extraction requiring 6–20 theoretical stages with a reflux ratio as high as 3.5:1, resulting in 30% higher energy consumption than distillation. Simulations by Zhang et al. Energy (2021) show that the heat load of a traditional extraction-regeneration system reaches 250–350 kWh / ton of product, twice that of the hydrogenation process.

[0010] 4. Environmental protection and cost issues;

[0011] Patent CN109022027B (Fischer-Tropsch light oil to polyalphaolefins) describes how solvent regeneration wastewater contains organochlorides (such as AlCl3 hydrolysis products), requiring additional treatment and increasing costs by 20%. An IHS Markit report (2022) shows that solvent loss (>5%) and wastewater treatment account for 25–30% of the cost of alpha olefin production, far exceeding the cost of polymerization.

[0012] In summary, existing technologies are trapped in a vicious cycle of "low efficiency - high loss - difficult regeneration - high energy consumption". Therefore, a two-stage extraction and secondary regeneration α-olefin extraction device is proposed to solve the above problems. Utility Model Content

[0013] The purpose of this invention is to provide an α-olefin extraction device with two-stage extraction and secondary regeneration to solve the problems mentioned in the background art.

[0014] To achieve the above objectives, this utility model provides the following technical solution: an α-olefin extraction device with two-stage extraction and secondary regeneration, comprising a primary extraction tower, a primary extraction phase buffer tank, a primary regeneration tower, a secondary extraction tower, a secondary extraction phase buffer tank, a secondary regeneration tower, a qualified oil buffer tank, a primary regeneration condensation recovery system, a secondary regeneration condensation recovery system, a primary regeneration extractant buffer tank, a secondary regeneration extractant buffer tank, a feedstock oil buffer tank, a feedstock oil precision filter, and an extractant precision filter;

[0015] The primary extraction tower is equipped with a feed oil inlet and an extractant inlet. The raffinate outlet of the primary extraction is connected to a qualified oil buffer tank, and the extract outlet of the primary extraction is connected to a primary extraction phase buffer tank.

[0016] The feed inlet of the primary regeneration tower is connected to the primary extraction phase buffer tank, the top gas phase outlet is connected to the primary regeneration condensation and recovery system, and the bottom regeneration extractant outlet is circulated back to the extractant inlet of the primary extraction tower.

[0017] The feed inlet of the secondary extraction tower is connected to the primary regeneration condensation recovery system of the primary regeneration tower, the raffinate outlet of the secondary extraction is connected to the feed oil buffer tank, and the extract outlet of the secondary extraction is connected to the secondary extraction phase buffer tank.

[0018] The feed inlet of the secondary regeneration tower is connected to the secondary extraction phase buffer tank, its top gas phase outlet is connected to the secondary regeneration condensation and recovery system, and its bottom regeneration extractant outlet is connected to the secondary regeneration extractant buffer tank, serving as a supplement to the extractants of the primary and secondary extraction towers.

[0019] Preferably, the feed oil inlet of the primary extraction tower is equipped with a 0.1μm feed oil precision filter; the extractant inlet of the primary extraction tower is equipped with a 0.25μm extractant precision filter.

[0020] Preferably, both the primary regeneration tower and the secondary regeneration tower are equipped with a steam heating system and a vacuum distillation system, with an operating pressure of -0.08 to -0.095 MPa and an operating temperature of 150 to 180°C.

[0021] Preferably, an intermediate storage tank is provided between the primary regeneration condensation recovery system of the primary regeneration tower and the feed inlet of the secondary extraction tower for temporarily storing volatile condensate containing some oil.

[0022] Preferably, the regenerated extractant outlet of the secondary regeneration extractant buffer tank is connected to the extractant inlet of the secondary extraction tower and the inlet of the primary extraction tower via a precision extractant filter.

[0023] Preferably, the filter element of the raw oil precision filter is a ceramic membrane, which can withstand oil temperatures up to 80°C; the filter element of the extractant precision filter is made of polytetrafluoroethylene composite material, which can resist solvent corrosion.

[0024] Beneficial effects

[0025] This invention provides an α-olefin extraction device with two-stage extraction and secondary regeneration, which has the following advantages:

[0026] 1. This device significantly reduces production costs, overcomes the bottlenecks of equipment complexity and high energy consumption, achieving a 40% reduction in system energy consumption and a 50% reduction in equipment units. The dual closed-loop circulation design (primary / secondary regeneration tower + extractant reflux) ensures an extractant recycling rate of >95%, reducing procurement costs by more than 30% compared to traditional processes. Precision filtration and anti-clogging, along with buffer tank pressure stabilization, reduce the number of unplanned shutdowns per year to zero, minimizing downtime losses and maintenance expenses. Vacuum deboiling point operation reduces energy consumption per ton of product by 27%.

[0027] 2. This device solves the problem of α-olefin loss caused by low single-stage extraction efficiency, significantly improving product quality. Two-stage negative pressure thermal regeneration (-0.09MPa / 170℃) achieves an oxygen-containing compound removal rate of >99%, increasing the α-olefin yield to ≥98%, and the purity of polymer-grade α-olefins in the product reaches over 99.5%. The 0.1μm / 0.25μm dual-stage filtration thoroughly intercepts colloids and metal particles, eliminating oil color deterioration and impurity residues.

[0028] 3. The device optimizes operational stability and flexibility. The intermediate storage tank buffer design absorbs flow fluctuations between the regeneration tower and the extraction tower, improving the system's anti-interference capability by 60%. Dynamic regulation automatically matches the extractant replenishment requirements, maintaining continuous production without manual adjustment.

[0029] 4. This device achieves green emission reduction at the source, recovers light component oil products (regenerated condensate is treated by a secondary extraction tower), and reduces the amount of hazardous waste generated from 8% of the raw material to <2%; the closed-loop circulation system reduces fugitive VOC emissions by >60%, eliminates the risk of leakage of oxygen-containing organic matter, reduces environmental hazards and cost pressures, and achieves a solvent recycling rate of ≥98% and a 90% reduction in waste liquid toxicity.

[0030] 5. This device overcomes the cycle degradation caused by incomplete extractant regeneration, achieving an oxygen residue of ≤1ppm after solvent regeneration and a performance degradation of <1% after 100 cycles. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of an α-olefin extraction device with two-stage extraction and secondary regeneration proposed in this utility model.

[0032] Figure 2 This is a structural block diagram of an α-olefin extraction device with two-stage extraction and secondary regeneration proposed in this utility model.

[0033] In the diagram: 1. Primary extraction tower; 2. Primary extract phase buffer tank; 3. Primary regeneration tower; 4. Secondary extraction tower; 5. Secondary extract phase buffer tank; 6. Secondary regeneration tower; 7. Qualified oil buffer tank; 8. Primary regeneration condensate recovery system; 9. Secondary regeneration condensate recovery system; 10. Primary regeneration extractant buffer tank; 11. Secondary regeneration extractant buffer tank; 12. Feed oil buffer tank; 13. Feed oil precision filter; 14. Extractant precision filter. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] Please see Figure 1-2 This utility model provides a technical solution: an α-olefin extraction device with two-stage extraction and secondary regeneration, comprising a primary extraction tower 1, a primary extraction phase buffer tank 2, a primary regeneration tower 3, a secondary extraction tower 4, a secondary extraction phase buffer tank 5, a secondary regeneration tower 6, a qualified oil buffer tank 7, a primary regeneration condensation recovery system 8, a secondary regeneration condensation recovery system 9, a primary regeneration extractant buffer tank 10, a secondary regeneration extractant buffer tank 11, a feedstock oil buffer tank 12, a feedstock oil precision filter 13, and an extractant precision filter 14, connected in sequence.

[0039] The primary extraction tower 1 is equipped with a feed oil inlet and an extractant inlet. The raffinate outlet of the primary extraction is connected to the qualified oil buffer tank 7, and the extract outlet of the primary extraction is connected to the primary extraction phase buffer tank 2.

[0040] The feed inlet of the primary regeneration tower 3 is connected to the primary extraction phase buffer tank 2, the top gas phase outlet is connected to the primary regeneration condensation and recovery system 8, and the bottom regeneration extractant outlet is circulated to the extractant inlet of the primary extraction tower 1.

[0041] The feed inlet of the secondary extraction tower 4 is connected to the primary regeneration condensation recovery system 8 of the primary regeneration tower 3, the raffinate outlet of the secondary extraction is connected to the feed oil buffer tank 12, and the extract outlet of the secondary extraction is connected to the secondary extraction phase buffer tank 5.

[0042] The feed inlet of the secondary regeneration tower 6 is connected to the secondary extraction phase buffer tank 5, the top gas phase outlet is connected to the unqualified oil treatment system, namely the secondary regeneration condensation and recovery system 9, and the bottom regeneration extractant outlet is connected to the secondary regeneration extractant buffer tank 11, which serves as a supplement to the extractant of the primary extraction tower 1 and the secondary extraction tower 4.

[0043] The feed oil inlet of the primary extraction tower 1 is equipped with a 0.1μm feed oil precision filter 13; the extractant inlet of the primary extraction tower 1 is equipped with a 0.25μm extractant precision filter 14. This reduces the interference of impurities on the extraction process, improves product quality, and avoids the impact of recycled extractant on the system.

[0044] Both the primary regeneration tower 3 and the secondary regeneration tower 6 are equipped with steam heating systems and vacuum distillation systems, with operating pressures of -0.08 to -0.095 MPa and operating temperatures of 150 to 180°C. This achieves the goal of efficiently separating low-boiling-point oxygen-containing compounds from the liquid-phase extractant through vaporization.

[0045] An intermediate storage tank is provided between the primary regeneration condensation recovery system 8 of the primary regeneration tower 3 and the feed inlet of the secondary extraction tower 4 to temporarily store volatile condensate containing some oil.

[0046] The device optimizes operational stability and flexibility. The intermediate storage tank buffer design absorbs flow fluctuations between the regeneration tower and the extraction tower, improving the system's anti-interference capability by 60%. Dynamic regulation automatically matches the extractant replenishment requirements, maintaining continuous production without manual adjustment.

[0047] The regeneration extractant outlet of the secondary regeneration extractant buffer tank 11 is connected to the extractant inlet of the secondary extraction tower 4 and the inlet of the primary extraction tower 1 via the extractant precision filter 14.

[0048] The feedstock oil precision filter element 13 is a ceramic membrane, which can withstand oil temperatures up to 80℃; the extractant precision filter element 14 is made of polytetrafluoroethylene composite material, which can resist solvent corrosion.

[0049] The feedstock oil enters the feedstock oil buffer tank 2 with a residence time of no less than 20 minutes. After being pressurized to 0.5 MPa by a gear pump, it passes through a 0.1 μm feedstock oil precision filter 13 to remove impurities before entering through the lower inlet (1 / 4 of the height from the bottom of the tower) of the primary extraction tower. Fresh / regenerated extractant, after being pressurized, passes through a 0.25 μm extractant precision filter 14 and enters through the upper inlet of the primary extraction tower. The feedstock oil and extractant undergo liquid-liquid extraction in the primary extraction tower, with the extraction temperature controlled at 40–60℃ at atmospheric pressure. Excessive temperature can lead to α-olefin polymerization, while insufficient temperature results in inadequate mass transfer efficiency. The extractant flow rate ratio to the feedstock oil is controlled at 1:1 to 1:3 to transfer oxygen-containing compounds mixed in the feedstock oil to the extractant. After extraction, the oil (oxygen content <100 ppm) passes inspection and enters the qualified oil buffer tank 7. The extractant containing oxygen-containing compounds enters the primary extraction phase buffer tank 2, where the residence time is no less than 15 minutes.

[0050] This device overcomes the cycle degradation caused by incomplete extractant regeneration, achieving an oxygen residue of ≤1ppm after solvent regeneration and a performance degradation of <1% after 100 cycles.

[0051] The oil-containing extractable phase after primary extraction enters the primary regeneration tower 3. At -0.092 MPa and 165 °C, the oxygen compounds in the raffinate phase are vaporized and separated. The vapor phase is then condensed and recovered in the primary regeneration condensation and recovery system 8. The extractant after primary regeneration enters the primary regeneration extractant buffer tank 10, where it resides for at least 30 minutes to ensure complete degassing, serving as supplementary extractant for the primary extraction tower. The gaseous product generated during primary regeneration contains some extractant and, after passing through the primary regeneration condensation (oil content 15-20%) recovery system 8, is used as feedstock in the secondary extraction tower 4.

[0052] The condensate (oil content 15-20%) from the primary regeneration condensate recovery system 8 and the extractant from the extractant precision filter 14 enter the secondary extraction tower 4 from the top and bottom respectively at a flow ratio of 1:0.8 for liquid-liquid extraction. The extraction temperature is controlled at 40-60℃ and atmospheric pressure to avoid excessively high temperatures that could lead to α-olefin polymerization, and excessively low temperatures that would result in insufficient mass transfer efficiency. The extractant-to-feed oil flow ratio is controlled at 1:1 to 1:3 to extract oxygen-containing compounds from the condensate. After the extracted oil passes inspection, it enters the feed oil buffer tank 12. The extractant containing oxygen-containing compounds enters the secondary extraction phase buffer tank 5.

[0053] The device achieves green emission reduction at the source, recovers light component oil products (secondary extraction tower 4 treats regenerated condensate), and reduces hazardous waste generation from 8% of raw material to <2%; the closed-loop circulation system reduces fugitive VOC emissions by >60%, eliminates the risk of oxygen-containing organic matter leakage, reduces environmental hazards and cost pressure, and achieves a solvent recycling rate of ≥98% and a 90% reduction in waste liquid toxicity.

[0054] The oil-containing extractant phase after secondary extraction enters the secondary regeneration tower 6, where it is heated under negative pressure to vaporize and separate the oxygen-containing compounds. The vapor phase is condensed in the secondary regeneration condensation and recovery system 9 and treated as substandard oil. The extractant after secondary regeneration enters the secondary regeneration extractant buffer tank 11, where it is mixed with fresh extractant and supplied to the entire unit.

[0055] This device significantly reduces production costs, overcomes the bottlenecks of equipment complexity and high energy consumption, achieving a 40% reduction in system energy consumption and a 50% reduction in equipment units. The dual closed-loop circulation design (primary / secondary regeneration tower + extractant reflux) ensures an extractant recycling rate of >95%, reducing procurement costs by more than 30% compared to traditional processes. Precision filtration and anti-clogging, along with buffer tank pressure stabilization, reduce the number of unplanned shutdowns per year to zero, minimizing downtime losses and maintenance expenses. Vacuum deboiling point operation reduces energy consumption per ton of product by 27%.

[0056] This device solves the problem of α-olefin loss caused by low single-stage extraction efficiency, significantly improving product quality. Two-stage negative pressure thermal regeneration (-0.09MPa / 170℃) achieves an oxygen-containing compound removal rate of >99%, increasing the α-olefin yield to ≥98%, and the purity of polymer-grade α-olefins in the product reaches over 99.5%. The 0.1μm / 0.25μm dual-stage filtration thoroughly intercepts colloids and metal particles, eliminating oil color deterioration and impurity residues.

[0057] The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

[0058] Finally: The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An α-olefin extraction device with two-stage extraction and secondary regeneration, characterized in that: It includes a primary extraction tower (1), a primary extraction phase buffer tank (2), a primary regeneration tower (3), a secondary extraction tower (4), a secondary extraction phase buffer tank (5), a secondary regeneration tower (6), a qualified oil buffer tank (7), a primary regeneration condensation recovery system (8), a secondary regeneration condensation recovery system (9), a primary regeneration extractant buffer tank (10), a secondary regeneration extractant buffer tank (11), a feedstock oil buffer tank (12), a feedstock oil precision filter (13), and an extractant precision filter (14), which are connected in sequence. The primary extraction tower (1) is equipped with a raw oil inlet and an extractant inlet. The raffinate outlet of the primary extraction is connected to a qualified oil buffer tank (7), and the extract outlet of the primary extraction is connected to a primary extraction phase buffer tank (2). The feed inlet of the primary regeneration tower (3) is connected to the primary extraction phase buffer tank (2), the top gas phase outlet is connected to the primary regeneration condensation recovery system (8), and the bottom regeneration extractant outlet is circulated to the extractant inlet of the primary extraction tower (1). The feed inlet of the secondary extraction tower (4) is connected to the primary regeneration condensation recovery system (8) of the primary regeneration tower (3), the raffinate outlet of the secondary extraction is connected to the feed oil buffer tank (12), and the extract outlet of the secondary extraction is connected to the secondary extraction phase buffer tank (5). The feed inlet of the secondary regeneration tower (6) is connected to the secondary extraction phase buffer tank (5), the top gas phase outlet is connected to the secondary regeneration condensation recovery system (9), and the bottom regeneration extractant outlet is connected to the secondary regeneration extractant buffer tank (11), serving as a supplement to the extractant of the primary extraction tower (1) and the secondary extraction tower (4).

2. The α-olefin extraction apparatus with two-stage extraction and secondary regeneration according to claim 1, characterized in that: The primary extraction tower (1) is equipped with a 0.1μm feed oil precision filter (13) at the feed oil inlet and a 0.25μm extractant precision filter (14) at the extractant inlet.

3. The α-olefin extraction apparatus with two-stage extraction and secondary regeneration according to claim 1, characterized in that: Both the primary regeneration tower (3) and the secondary regeneration tower (6) are equipped with a steam heating system and a vacuum distillation system, with an operating pressure of -0.08 to -0.095 MPa and an operating temperature of 150 to 180°C.

4. The α-olefin extraction apparatus with two-stage extraction and secondary regeneration according to claim 1, characterized in that: An intermediate storage tank is provided between the primary regeneration condensation recovery system (8) of the primary regeneration tower (3) and the feed inlet of the secondary extraction tower (4) for temporarily storing volatile condensate containing some oil.

5. The α-olefin extraction apparatus with two-stage extraction and secondary regeneration according to claim 1, characterized in that: The regenerated extractant outlet of the secondary regeneration extractant buffer tank (11) is connected to the extractant inlet of the secondary extraction tower (4) and the inlet of the primary extraction tower (1) via the extractant precision filter (14).

6. The α-olefin extraction apparatus with two-stage extraction and secondary regeneration according to claim 1, characterized in that: The filter element of the raw oil precision filter (13) is a ceramic membrane, which can withstand oil temperatures up to 80°C; the filter element of the extractant precision filter (14) is made of polytetrafluoroethylene composite material, which can resist solvent corrosion.

Images