Method and apparatus for separating silicone from waste oil

Abstract

The application discloses a separation method and a separation device for organic silicon in waste oil. The separation method for organic silicon in waste oil comprises the following steps: mixing waste oil containing organic silicon, a surfactant and water, stirring and emulsifying to obtain an emulsified mixed solution; and carrying out demulsification on the emulsified mixed solution to make the mixed solution carry out phase separation, so as to obtain an upper purified oil layer, a middle layer of an oil-water interface layer containing organic silicon and a lower water layer, that is, the separation of organic silicon in waste oil is realized. The separation method in the application is different from traditional processes such as a solvent extraction method, an oxidative decomposition method, an alkali washing and washing method, a hydrogenation removal method and an adsorption removal method. The method does not generate solid hazardous waste and reduces energy consumption, and effectively realizes the resource utilization of waste oil.

Description

Technical Field

[0001] This invention belongs to the field of waste oil treatment technology, specifically relating to a method and apparatus for separating organosilicon from waste oil. Background Technology

[0002] Waste oil resource utilization has become an important direction in the fields of environmental protection and energy. Organosilicon in waste oil mainly originates from defoamers and additives, and mostly exists in the form of siloxanes, exhibiting extremely strong thermal and chemical stability, making it difficult to remove using conventional refining processes. Organosilicon in waste oil not only causes irreversible poisoning of hydrogenation catalysts and shortens the operating cycle of the equipment, but also affects the quality of recycled oil, becoming a core bottleneck restricting the high-value utilization of waste oil. Developing efficient desiliconization technology is crucial to improving the comprehensive utilization rate of waste oil.

[0003] Currently, the main methods for removing organosilicon from waste oil include adsorption, hydrodesiliconization, catalytic conversion, chemical treatment, and pyrolysis. Adsorption is the most widely used desiliconization pretreatment technology. Its core principle is to achieve selective separation by relying on the active sites on the adsorbent surface to form van der Waals forces, hydrogen bonds, or coordination interactions with organosilicon molecules. Hydrodesiliconization is the mainstream technology for deep desiliconization of waste oil, often used in the production of high-value-added recycled base oils. Its principle is to break the Si-C bonds in organosilicon molecules under a hydrogen atmosphere and catalyst, causing silicon to be converted into SiO2 deposition or removed as volatile silicon compounds. Catalytic conversion leverages non-hydrogen-exposed conditions, using catalysts to promote the decomposition and isomerization of organosilicon into easily separable solid forms, suitable for treating high-silicon-content waste plastic oil and heavy waste oil. Chemical treatment, with its simple equipment and mild reaction conditions, is often used for small-scale waste oil pretreatment or auxiliary desiliconization, mainly including alkaline washing, oxidative decomposition, and solvent extraction. The pyrolysis treatment method is mainly used in waste plastic pyrolysis oil. Its principle is to add silicon precipitators, such as granular alumina, during the pyrolysis of waste plastics, so that organosilicon is directly converted into solid silicon compounds during pyrolysis, avoiding entering the pyrolysis oil, and the silicon content in the pyrolysis oil can be reduced to < 5μg / g.

[0004] Although the above methods can remove organosilicon impurities from waste oil, they suffer from high energy consumption, low economic efficiency, and low environmental friendliness, and require further improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for separating organosilicon from waste oil. This method features low processing cost, environmental friendliness, and energy saving. It is suitable for separating organosilicon from waste oils such as waste engine oil, white oil, hydraulic oil, fuel oil, and transformer oil. This method is a front-end treatment process for waste oil regeneration. It can not only effectively reduce the cost of removing silicon in waste oil regeneration, but also ensure the stable operation of subsequent processes in waste oil regeneration, extend the service life of downstream equipment, improve oil quality, and broaden the application range of oil.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A method for separating organosilicon from waste oil, the method comprising the following steps:

[0008] Waste oil containing organosilicon, surfactant, and water are mixed and emulsified by stirring to obtain an emulsified mixture.

[0009] The emulsified mixture is demulsified to separate the phases, resulting in an upper purified oil layer, a middle oil-water interface layer containing organosilicon, and a lower water layer, thus achieving the separation of organosilicon from waste oil.

[0010] In one or more embodiments of the present invention, the amount of water used is 3%-32% of the mass of waste oil.

[0011] In one or more embodiments of the present invention, the amount of surfactant used is 0.1%-20% of the total mass of water and waste oil, or the amount of surfactant used is 0.5-60 times the mass of silicon in the waste oil.

[0012] In one or more embodiments of the present invention, the surfactant is at least one of anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, natural emulsifiers, and polymeric emulsifiers;

[0013] The anionic surfactant is at least one of fatty acid salt surfactants, sulfonate surfactants, sulfate surfactants, and phosphate ester surfactants.

[0014] The cationic surfactant is at least one of alkyl quaternary ammonium salt surfactant and benzyl quaternary ammonium salt surfactant;

[0015] The nonionic surfactant is at least one of polyol fatty acid esters, fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, and block polyethers.

[0016] The zwitterionic surfactant is at least one of betaine surfactants, imidazoline surfactants, and amino acid surfactants;

[0017] The natural emulsifier is at least one of phospholipid emulsifiers, polysaccharide emulsifiers, protein emulsifiers, and sugar derivative emulsifiers;

[0018] The polymeric emulsifier is at least one of polyacrylate emulsifiers and polyurethane emulsifiers.

[0019] In one or more embodiments of the present invention, the stirring speed of the emulsification is 200 r / min-1200 r / min, and the stirring time is 15 min-120 min.

[0020] In one or more embodiments of the present invention, the demulsification operation employs at least one of centrifugal demulsification, demulsification with a demulsifying agent, and demulsification by fabric filtration.

[0021] The centrifugal demulsification operation is carried out using a continuous centrifuge with a centrifugation time of 10s-120s and a separation factor of 1000-30000; or, an intermittent centrifuge with a centrifugation time of 2min-30min and a separation factor of 800-20000.

[0022] Demulsification was performed using a fabric filter to filter the emulsified mixture at a pressure of 0.1 MPa-0.5 MPa and a surface flow velocity of 0.5 m / s. 3 / (m 2 ·h)-5m 3 / (m 2 ·h);

[0023] Demulsification is performed by mixing the demulsifier with the emulsified mixture, with the amount of demulsifier added being 0.01%-2% of the mass of the mixture.

[0024] In one or more embodiments of the present invention, the upper purified oil layer, surfactant and water are mixed, and then emulsification, demulsification and phase separation are repeated.

[0025] In one or more embodiments of the present invention, the upper purified oil layer obtained after repeated emulsification, demulsification, and phase separation is subjected to alkaline washing, adsorption, filtration, and distillation.

[0026] In one or more embodiments of the present invention, an intermediate oil-water interface layer containing organosilicon, a surfactant, and water are mixed, and then emulsification, demulsification, and phase separation are repeated.

[0027] In one or more embodiments of the present invention, the waste oil containing organosilicon is first subjected to primary centrifugation to remove the lower layer liquid, the upper layer liquid is collected, and then the upper layer liquid, surfactant and water are mixed and stirred to emulsify.

[0028] The silicon content in the waste oil is x%, and the amount of the removed lower liquid is 1.25 to 25 times (total mass of waste oil × x%).

[0029] Another specific embodiment of the present invention provides the following technical solution:

[0030] An apparatus for separating organosilicon from waste oil, applied to a method for separating organosilicon from waste oil, comprising:

[0031] The emulsification unit includes a mechanically stirred tank for mixing and emulsifying waste oil containing organosilicon, surfactants, and water;

[0032] The demulsification unit, connected to the mechanically stirred tank, is used to receive the emulsion and demulsify and separate the emulsion.

[0033] In one or more embodiments of the present invention, the demulsification unit includes a centrifuge connected to a mechanically stirred tank; or,

[0034] The demulsification unit includes a phase separator, which is connected to a mechanically stirred tank; or,

[0035] The demulsification unit includes a filter, which is connected to a mechanically stirred tank.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. A revolutionary innovation in process route, achieving low-temperature, low-pressure, and low-energy operation. Traditional adsorption, hydrogenation, and catalytic conversion technologies all require high temperatures (up to 550°C), high pressures (3-8 MPa for hydrogenation), or strong acid / alkali conditions, resulting in extremely high energy consumption and equipment requirements. This invention innovatively adopts a physical separation path under normal temperature and pressure, achieving efficient separation through only a gentle step of emulsification-demulsification-phase separation, utilizing the selective enrichment effect of organosilicon at the oil-water interface. This process requires no harsh external energy input; the core energy consumption comes only from stirring and centrifugation, fundamentally overturning the high-energy-consumption desiliconization technology and significantly reducing process operating costs and equipment investment thresholds.

[0038] 2. Excellent environmental friendliness, eliminating hazardous waste and secondary pollution at the source. Existing technologies have significant environmental shortcomings: adsorption methods produce waste adsorbents, hydrogenation methods rely on high-pressure hydrogen and the catalyst is easily deactivated, and chemical methods produce silicon-containing wastewater and waste residue. This invention uses water and surfactants as the main media, without introducing strong acids, strong alkalis, oxidants, or organic solvents, and the reaction conditions are mild. After separation, the silicon-rich interface layer can be centrally treated, and the lower aqueous phase can be recycled or discharged in compliance with standards after simple treatment, without generating difficult-to-dispose-of solid hazardous waste. This avoids the secondary pollution problems of heavy metal catalysts, silicon-containing hazardous waste, and toxic solvents caused by traditional methods at the source, achieving clean production.

[0039] 3. The process is highly adaptable and flexible, enabling customized deep desilication. Traditional methods each have limitations: adsorption methods are ineffective for heavy oils, hydrogenation methods have high equipment requirements, and chemical methods are difficult to remove silicon at a deep level. This invention, by adjusting parameters such as surfactant type, water-oil ratio, and demulsification method (centrifugation, chemical, or fabric filtration), can flexibly adapt to various oil types, from waste engine oil to fuel oil, and various organosilicon impurities, from silanes to polysiloxanes. The unique interface layer collection design allows for the recycling and reprocessing of the "silicon-rich oil layer." Through multi-stage series processes, the desilication rate can be easily increased to over 95%, meeting the stringent silicon content requirements of different quality recycled oils, combining process flexibility with processing depth. Attached Figure Description

[0040] 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 some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic flowchart of a method for separating organosilicon from waste oil according to an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of a process for separating organosilicon from waste oil in one embodiment of the present invention, which involves multiple high-speed centrifugal demulsifiers connected in series.

[0043] Figure 3 This is a schematic diagram of a process for separating organosilicon from waste oil in one embodiment of the present invention, which involves multiple high-speed centrifuges connected in series to demulsify and perform alkaline washing, adsorption, filtration, distillation, and flash evaporation.

[0044] Explanation of key figure labels:

[0045] 111. Storage tank; 221. Primary centrifuge; 222. Primary phase separator; 331. First-stage mechanically stirred tank; 441. First-stage centrifuge; 442. First-stage phase separator; 551. Second-stage mechanically stirred tank; 661. Second-stage centrifuge; 662. Second-stage phase separator; 771. Tertiary mechanically stirred tank; 881. Tertiary centrifuge; 882. Tertiary phase separator; 991. Alkali washing reactor; 992. Adsorption sedimentation tank; 993. Filter; 994. Flash tank; 995. Oil-water phase separator; 996. Storage tank; 1. Waste oil containing organosilicon; 2. Light waste oil; 3. Waste oil after primary emulsification; 4. Light oil with reduced silicon content after primary centrifugal phase separation; 5. Waste oil after secondary emulsification; 6. Secondary... 7. Light oil with reduced silicon content after primary centrifugal phase separation; 8. Waste oil after tertiary emulsification; 9. Light oil with reduced silicon content after tertiary centrifugal phase separation; 10. Light oil separated after alkaline washing; 11. Light oil after adsorption and precipitation treatment; 12. Filtered light oil; 13. Finished oil after flash evaporation; 14. Middle oil-water interface layer after tertiary centrifugal phase separation; 15. Middle oil-water interface layer after secondary centrifugal phase separation; 16. Middle oil-water interface layer after primary centrifugal phase separation; 17. Light oil separated by static phase separation at the water interface layer; 18. Other waste liquids in the oil-water phase separator; 19. Waste liquid generated by phase separation in the primary phase separator; 20. Waste liquid generated by phase separation in the secondary phase separator; 11. Waste liquid generated by phase separation in the tertiary phase separator. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0047] Existing methods for removing organosilicon from waste oil, such as adsorption, commonly use adsorbents including modified alumina-silicon composite adsorbents, activated alumina, and activated carbon. A relevant patent, such as CN101157506B, describes an integrated treatment method for removing silicon, purifying water, and softening oilfield wastewater. This method uses Al... n+1 (SiO2)Cl 3(n+1)Adsorbents of xH2O (0 < n ≤ 10, x is 5 or 9) are used to treat oilfield sewage through a process of adding adsorbents, compounding stabilizers, adding flocculant improvers, horizontal flow sedimentation, and pressure filtration. After treatment, the silica in the sewage is reduced to below 50 mg / L, the hardness is reduced to 10 - 30 mg / L, the suspended solids are ≤ 10 mg / L, significantly reducing the subsequent resin softening load, solving the problems of filter media caking and equipment scaling, and the pH adaptation range is 7.5 - 8.5, with low treatment costs. However, its application scenario is single, only suitable for oilfield sewage, and has no treatment effect on other types of wastewater; and this process still needs to strictly control the water body pH within the range of 7.5 - 8.5, and water quality fluctuations are likely to affect the treatment effect, requiring additional adjustment processes. The core adsorbent for silicon removal by the adsorption method is for single use, with high regeneration costs, and the solid waste treatment cost is high for large-scale applications; secondly, the process has many links, takes a long time, requires high professionalism of equipment and operators, and has a large upfront investment.

[0048] In the hydrodesiliconization method, related patents such as CN116159569B, CN119432430A, and US2023416636A1. This method is divided into three categories: pre-hydrogenation, slurry bed hydrogenation, and two-stage hydrogenation. Commonly used Ni-Mo-P / aluminum oxide support catalysts can achieve a desiliconization rate of 95% - 99.9% under the conditions of 280 - 380 °C and a pressure of 3 - 8 MPa, effectively protecting the subsequent hydrogenation catalysts. However, this technology has strict requirements for equipment and working conditions: it needs to be equipped with a high-pressure hydrogenation device, with huge initial equipment investment, which is difficult for small and medium-sized enterprises to bear; the hydrogen consumption is large, and the purity needs to meet the standard, further pushing up the operating costs; the catalyst is easily deactivated due to silicon deposition and carbon deposition, and the regeneration is difficult. Some catalysts need to be discarded, which not only increases costs but also causes resource waste; the operation process is complex, with extremely high precision requirements for parameters such as temperature, pressure, and space velocity, and it is easy to have problems of incomplete reaction or overreaction, affecting the yield and quality of the regenerated oil.

[0049] The mainstream processes of the catalytic conversion method include catalytic cracking, fluidized bed catalytic desiliconization, and integrated dechlorination and silicon capture. Using ZSM-5 molecular sieve and Al2O3-MgO-CaO composite catalysts, under the condition of 280 - 550 °C, silicon is converted into SiO2 or silicate and adheres to the catalyst, and the desiliconization rate can reach 90% - 99%. Chlorine, metals and other impurities can also be removed synchronously. Related patents such as CN116083117B and CN119278247A. However, this technology has many limitations: the catalyst life is short, the phenomena of silicon deposition and carbon deposition are prominent, and it needs to be regenerated frequently. The regeneration process requires high-temperature roasting, with high energy consumption and easy to cause damage to the catalyst structure; by-products such as coke are easily generated during the reaction process, reducing the yield of the regenerated oil, and the treatment of by-products requires additional processes, increasing the environmental protection pressure; the operation stability of the fluidized bed process is poor, the catalyst is severely worn, and equipment blockage problems are easy to occur; it is highly sensitive to the composition of the feed oil. When the impurities in the waste oil are complex, the catalytic efficiency drops significantly, and the desiliconization effect is unstable.

[0050] Chemical treatment methods mainly include three categories: alkaline washing, oxidative decomposition, and solvent extraction, with relevant patents such as CN103328614B, CN118339255A, and US20020011448A1. Alkaline washing uses a 5-10% NaOH solution at room temperature to convert organosilicon into silicates, which then enter the aqueous phase. Oxidative decomposition uses oxidants such as hydrogen peroxide to break Si-C bonds at 180-250℃. Solvent extraction uses polar solvents such as NMP and DMSO to selectively extract organosilicon, achieving a desilication rate between 60% and 90%. The core drawbacks of this technology are secondary pollution and treatment limitations: alkaline washing and oxidation processes generate large amounts of silicon-containing wastewater and sludge. This type of wastewater has poor biodegradability and high toxicity, requiring additional investment in treatment; otherwise, it can easily cause water and soil pollution. Solvent extraction has poor selectivity, easily extracting effective components from waste oil, affecting the quality of recycled oil, and solvent recovery is difficult, easily causing solvent loss and volatile pollution. The overall desiliconization efficiency is limited, making it difficult to achieve deep desiliconization requirements, and it needs to be used in conjunction with other processes. It has poor adaptability to heavy waste oil, as organosilicon has low solubility in heavy oil, resulting in insufficient reaction or extraction and a significant reduction in treatment effect, making it unsuitable for high-requirement recycled oil production scenarios.

[0051] Patents related to pyrolysis treatment methods, such as CN119278247A, also have obvious drawbacks. The energy consumption cost of this method is second only to hydrogenation, and it also generates a lot of solid hazardous waste that requires post-treatment. It does not meet the public welfare requirements of economic efficiency, energy conservation, and environmental protection.

[0052] Traditional methods for separating organosilicon from waste oil rely on a combination of processes, including adsorption, deep hydrogenation, catalytic conversion, and oxidative pyrolysis, to recover both the organosilicon and the waste oil. However, these methods require multiple processes, resulting in enormous energy consumption and excessive amounts of hazardous solid waste.

[0053] Based on this, the present invention utilizes the density difference between organosilicon materials and waste oil, as well as the synergistic principle of oil-water interface enrichment effect and surfactant adsorption, to combine centrifugal separation, water washing emulsification with surfactant addition, mechanical or chemical demulsification, and phase separation. This achieves the separation of organosilicon elements from waste oil, significantly reduces energy consumption and hazardous waste generation during organosilicon separation, and solves the problems of excessive cost and energy consumption in the organosilicon separation process from waste oil.

[0054] A specific embodiment of the present invention discloses a method for separating organosilicon from waste oil, such as... Figure 1 As shown, it includes the following steps:

[0055] Step 1: First, perform primary centrifugation on the waste oil containing organosilicon to remove the lower layer of liquid and collect the upper layer of liquid.

[0056] Specifically, waste oils containing organosilicon include: lubricating oils, such as waste engine oil from internal combustion engines in automobiles, ships, and construction machinery; industrial lubricating oils such as hydraulic oil, gear oil, compressor oil, guide rail oil, and vacuum pump oil; metalworking oils such as cutting oil, rolling oil, quenching oil, and drawing oil; and insulating oils used in ionization equipment; process oils, such as rust-preventive oils and cleaning oils used for surface treatment; mold release oils used in the plastics and rubber industries; and lubricants used in chemical fiber production, such as white oil; and fuel oils, such as contaminated waste diesel and waste kerosene.

[0057] The types of organosilicones in waste oil include: silanes, such as methyltrimethoxysilane, vinyltriethoxysilane, and γ-aminopropyltriethoxysilane; siloxanes, such as polydimethylsiloxane, hexamethylcyclotrisiloxane (D3), and octamethylcyclotetrasiloxane (D4); silicone resins, such as methyl silicone resin and phenylmethyl silicone resin; and polysilazanes, such as perhydropolysilazane and organopolysilazane.

[0058] Waste oil containing organosilicon can be waste oil that has undergone primary separation such as flash evaporation or mechanical impurity removal, or it can be raw waste oil without primary separation.

[0059] Primary centrifugation can be performed using either intermittent or continuous centrifugation. If using a continuous centrifuge, the residence time (centrifugation time) is 10-120 seconds, and the separation factor is 1000-30000. If using an intermittent centrifuge, the residence time (centrifugation time) is 2-30 minutes, and the separation factor is 800-20000.

[0060] In this step, since the primary centrifugation separation mainly involves metastable homogeneous oil without a clear interface layer, it is necessary to test the total organosilicon content in the waste oil to determine the material removal of the lower liquid. If the silicon content in the waste oil is x% by mass, then the amount of material to be discharged from the lower layer should be 1.25 to 25 times (total mass of waste oil × x%).

[0061] Step 2: Mix waste oil containing organosilicon, surfactant and water, stir and emulsify to obtain an emulsified mixture.

[0062] Specifically, the waste oil containing organosilicon in this step is the upper liquid obtained in step 1.

[0063] Furthermore, the surfactant is at least one of anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, natural emulsifiers, and polymeric emulsifiers.

[0064] Specifically, the anionic surfactant is at least one of fatty acid salt surfactants, sulfonate surfactants, sulfate surfactants, and phosphate ester surfactants.

[0065] The cationic surfactant is at least one of alkyl quaternary ammonium salt surfactants and benzyl quaternary ammonium salt surfactants.

[0066] The nonionic surfactant is at least one of the following: polyol fatty acid esters (such as sorbitan fatty acid esters (Span series), polyoxyethylene sorbitan fatty acid esters such as Tween series), fatty alcohol polyoxyethylene ethers (AEO series), alkylphenol polyoxyethylene ethers (OP / TX series), and block polyethers (Poloxamer).

[0067] The zwitterionic surfactant is at least one of the following: betaine surfactants (such as dodecyl dimethyl betaine (BS-12), cocamidopropyl betaine (CAB)), imidazoline surfactants, and amino acid surfactants.

[0068] Natural emulsifiers are at least one of phospholipid emulsifiers, polysaccharide emulsifiers, protein emulsifiers, and sugar derivative emulsifiers.

[0069] The polymeric emulsifier is at least one of polyacrylate emulsifiers and polyurethane emulsifiers.

[0070] Furthermore, the amount of water added during the emulsification process is 3%-32% of the mass of waste oil, and the amount of surfactant added is 0.1%-20% of the total mass of water and waste oil, or 0.5-60 times the mass of the measured organosilicon content in the waste oil.

[0071] Furthermore, the emulsification stirring speed is 200 r / min-1200 r / min, and the time is 15 min-120 min. During the stirring and emulsification process, auxiliary heating can be added as needed, with a temperature range of 15℃-85℃.

[0072] Step 3: Demulsify the emulsified mixture to separate the phases and obtain an upper purified oil layer, a middle oil-water interface layer containing organosilicon, and a lower water layer, thus achieving the separation of organosilicon from waste oil.

[0073] Specifically, the demulsification operation employs at least one of the following methods: centrifugal demulsification, demulsification using demulsifiers, or demulsification via fabric filtration. If a continuous centrifuge is used, the residence time (centrifugation time) is 10-120 seconds, and the separation factor is 1000-30000. If a batch centrifuge is used, the residence time (centrifugation time) is 2-30 minutes, and the separation factor is 800-20000.

[0074] In demulsification, the demulsifier is first mixed with the emulsion, and then injected into a phase separator for oil-water separation. During oil-water separation, the liquid at the oil-water interface is collected as the aqueous phase. The specific type of demulsifier can be selected according to actual needs, such as polyether or cationic types. The amount of demulsifier added is 0.01%-2% of the total mass of the emulsion. Alternatively, centrifugal demulsification can be combined with demulsification using a demulsifier to achieve demulsification. This combination can improve oil-water demulsification efficiency, enhance organosilicon separation capabilities, and simultaneously reduce the water content of the collected oil phase.

[0075] In the fabric filtration emulsification process, the filtration pressure is controlled at 0.1MPa-0.5MPa, and the surface flow velocity is controlled at 0.5m / s. 3 / (m 2 ·h)-5m 3 / (m 2 •h), the types of fabrics used can be natural fiber fabrics, synthetic fiber fabrics, inorganic fiber fabrics, composite fiber fabrics, nanofiber fabrics, or hydrophilic modified fabrics, such as APTES-TiO2 coated fabrics, polydopamine (PDA) modified fabrics, and hydroxylated / carboxylated polyester fabrics.

[0076] In this step, the phase separation stage divides the mixture into three parts: an upper purified oil layer, a middle oil-water interface layer containing organosilicon, and a lower water layer. The upper purified oil layer is the finished product, the middle oil-water interface layer containing organosilicon can be collected in a storage tank for further accumulation before phase separation, and the lower water layer enters the wastewater regeneration system.

[0077] Depending on the demulsification method, if an intermittent centrifuge or a continuous centrifuge is used for demulsification, the phase separator is integrated into the centrifuge, and the phase separation operation can be achieved inside the centrifuge without the need for a subsequent phase separation process or additional phase separation equipment; if a demulsifier is used for demulsification, then a special phase separation equipment is required to achieve phase separation of the mixture.

[0078] In addition, centrifugal demulsification integrates phase separation, allowing the use of continuous or intermittent centrifuges during the centrifugal demulsification process to be combined as needed and based on energy consumption indicators, or to add multiple emulsification centrifugal demulsification processes to achieve the removal of organosilicon and water from waste oil to meet standards.

[0079] Furthermore, the obtained upper purified oil layer can be tested. If a higher level of organosilicon content is required, the upper purified oil layer, surfactant, and water can be mixed and then emulsified, demulsified, and phase separated repeatedly until the organosilicon content reaches the required standard value.

[0080] Alternatively, if there are no higher requirements for the organosilicon content, the upper purified oil layer can undergo fewer emulsification, demulsification, and phase separation operations before entering the post-processing process, such as alkaline washing, adsorption precipitation, filtration, and distillation flash evaporation.

[0081] Furthermore, the resulting intermediate oil-water interface layer containing organosilicon contains a high content of waste oil and organosilicon. The intermediate oil-water interface layer can be collected for subsequent processing or returned to the previous emulsification operation. That is, the intermediate oil-water interface layer, surfactant, and water can be mixed and then emulsified, demulsified, and phase separated repeatedly; or the intermediate oil-water interface layer, organosilicon-containing waste oil, surfactant, and water can be mixed and then emulsified, demulsified, and phase separated.

[0082] Furthermore, the lower water layer contains various impurities, including organosilicon, which can be sent into the sewage system for sewage treatment.

[0083] In summary, this invention achieves efficient separation of organosilicon through centrifugation, emulsification, demulsification, and phase separation processes. Its core principle is based on the density difference between organosilicon and waste oil, and the synergistic mechanism of oil-water interface enrichment effect and surfactant adsorption: During centrifugation, some organosilicon and recycled waste oil are in a metastable homogeneous state, allowing for partial separation; during emulsification, organosilicon readily aggregates at the oil-water interface, while surfactants enhance this enrichment effect through physical adsorption; after demulsification, phase separation occurs, achieving the separation of organosilicon from the base oil. The method in this invention significantly reduces processing energy consumption and operating costs, while effectively reducing secondary pollution, providing a feasible path for the resource utilization of waste oil. It is particularly suitable for high-quality fuel oil applications with stringent silicon content requirements (such as engine oils), promoting the conversion of waste oil into high-value-added fuel oils, and yielding significant economic and environmental benefits.

[0084] Another specific embodiment of the present invention provides a device for separating organosilicon from waste oil, which is applied to a method for separating organosilicon from waste oil, specifically including:

[0085] The emulsification unit includes a mechanically stirred tank for mixing and emulsifying waste oil containing organosilicon, surfactants, and water;

[0086] The demulsification unit, connected to the mechanically stirred tank, is used to receive the emulsion and demulsify and separate the phases of the emulsion.

[0087] Specifically, depending on the demulsification method, the demulsification unit includes a centrifuge connected to a mechanically stirred tank. The centrifuge can be a continuous centrifuge or an intermittent centrifuge, and this setup is suitable for centrifugal demulsification. Alternatively, the demulsification unit includes a phase separator connected to a mechanically stirred tank, and this setup is suitable for demulsification using demulsifiers. Demulsification is performed by adding demulsifiers to the mechanically stirred tank, and then the liquid is conveyed to the phase separator for phase separation. Alternatively, the demulsification unit includes a filter connected to a mechanically stirred tank, and this setup is suitable for demulsification using fabric filtration.

[0088] To further describe in detail the method for separating organosilicon from waste oil in this invention, the specific process is as follows:

[0089] S1, Primary Centrifuge Unit Operation

[0090] Waste oil containing organosilicon is transported from a storage tank to a centrifuge (intermittent or continuous) for centrifugation, and the upper layer of the metastable homogeneous liquid is collected. If an industrial continuous centrifuge, such as a disc centrifuge, is used, the waste oil is pumped into the centrifuge at a certain feed rate. Under a high centrifugal force field with a separation factor of 1000-30000, rapid phase separation can be achieved within 10-120 seconds in the centrifuge. The metastable homogeneous upper and lower layers are directly separated and exported without subsequent settling. The amount of lower liquid removed by centrifugation is 1.25-25 times (total waste oil mass × x%), where x% represents the mass percentage of silicon in the waste oil.

[0091] If using an intermittent centrifuge, a separation factor of 800-20000 and a centrifugation time of 2-30 minutes will result in a metastable homogeneous liquid layer. The lower layer liquid to be removed is 1.25-25 times (total waste oil mass × x%), where x% is the mass percentage of silicon in the waste oil. The lower layer liquid, containing a large amount of organosilicon, can be returned to the storage tank or stored in other containers for further centrifugation.

[0092] S2, Emulsification Unit Operation

[0093] The waste oil, still containing organosilicon, obtained from the initial centrifugation, is injected into a mechanically stirred tank equipped with a heating jacket. The system temperature is controlled between 15℃ and 85℃, depending on the oil's viscosity and silicon content. 3%-32% (by weight of the waste oil) of pure water and 0.1-20% (by weight of the total water and oil mass, or 0.5-60 times the measured organosilicon mass) of surfactant are added to the stirred tank. Then, thorough emulsification is carried out at a stirring speed of 200-1200 rpm for 15-120 minutes to form a stable water-in-oil or oil-in-water emulsion.

[0094] S3, Demulsification Unit Operation

[0095] The emulsified mixture is then transferred to the demulsification process. If an industrial continuous centrifuge, such as a disc centrifuge, is used, the waste oil is pumped into the centrifuge at a certain feed rate. Under a high centrifugal force field with a separation factor of 1000-30000, the waste oil can achieve rapid phase separation within 10-120 seconds in the centrifuge. The oil phase (upper purified oil layer), the silica-rich interface layer (middle oil-water interface layer containing organosilicon), and the aqueous phase (lower water layer) are directly separated and exported without the need for subsequent settling separation.

[0096] If an intermittent centrifuge is used, with a separation factor of 800-20000 and a centrifugation time of 2-30 minutes, the material will separate into phases within the centrifuge. It is necessary to accurately monitor and collect the interface layer (silicone-rich oil layer) between the oil and water. This interface layer is rich in aggregated organosilicon compounds and a small amount of emulsion. It should be classified as the aqueous phase or collected separately and sent to a subsequent centralized treatment system to prevent silicon impurities from returning to the oil phase.

[0097] If a demulsifier is used for demulsification, the demulsifier is mixed with the emulsion and then transported to a phase separator for stratification. The stratified liquid is divided into an upper purified oil layer, a middle oil-water interface layer containing organosilicon, and a lower water layer in the phase separator.

[0098] S4, Subsequent Processing Unit

[0099] For cases that are difficult to process, have high silicon content, or require extremely high silicon trace levels, a combination of "emulsification + demulsification + phase separation" and "post-processing" can be used. That is, first perform the emulsification-demulsification-phase separation unit operation, and then combine multiple emulsification-demulsification-phase separation operations to further reduce the silicon content.

[0100] If the process requires extremely low moisture content in the finished product, multiple "high-speed centrifugal demulsification" or multiple "demulsifier demulsification" operations can be connected in series. For example... Figure 2 As shown, the waste oil in storage tank 111 is transported to primary centrifuge 221 for primary centrifugation to remove the lower layer liquid. The upper layer liquid is then transported to primary mechanical stirring tank 331 for primary emulsification, and then to primary centrifuge 441 for demulsification. The upper purified oil layer in primary centrifuge 441 is transported to secondary mechanical stirring tank 551 for secondary emulsification, and then to secondary centrifuge 661 for demulsification. The upper purified oil layer in secondary centrifuge 661 is transported to tertiary mechanical stirring tank 771 for tertiary emulsification, and then to tertiary centrifuge 881 for demulsification. The upper purified oil layer collected in tertiary centrifuge 881 is the finished product.

[0101] If the process requires not only reducing water content but also improving oil color and removing certain gums or polycyclic aromatic hydrocarbons, then an "alkali washing + adsorption + filtration + distillation flash evaporation" operation can be performed. For example... Figure 3As shown, the waste oil 1 containing organosilicon in storage tank 111 is sent to primary centrifuge 221 for primary centrifugation. After the lower layer liquid is removed by primary phase separator 222 (if an industrial centrifuge is selected, the primary phase separator 222 is integrated into the primary centrifuge 221 and does not need to be set up separately), the upper layer liquid, namely light waste oil 2, is sent to primary mechanical stirring tank 331 for primary emulsification. The waste oil 3 after primary emulsification is sent to primary centrifuge 441 for demulsification, and then undergoes phase separation by primary phase separator 442 (if an industrial centrifuge is selected, the primary phase separator 442 is integrated into the primary centrifuge 441 and does not need to be set up separately).

[0102] The upper purified oil layer, namely the light oil 4 with reduced silicon content after primary centrifugal phase separation, is transported to the secondary mechanical stirring tank 551 for secondary emulsification. The waste oil 5 after secondary emulsification is transported to the secondary centrifuge 661 for demulsification, and then undergoes phase separation through the secondary phase separator 662 (if an industrial centrifuge is selected, the secondary phase separator 662 is integrated into the secondary centrifuge 661 and does not need to be set up separately).

[0103] The upper purified oil layer, i.e., the light oil 6 with reduced silicon content after secondary centrifugal phase separation, is transported to the tertiary mechanical stirring tank 771 for tertiary emulsification. The waste oil 7 after tertiary emulsification is transported to the tertiary centrifuge 881 for demulsification, and then undergoes phase separation through the tertiary phase separator 882 (if an industrial centrifuge is selected, the tertiary phase separator 882 is integrated into the tertiary centrifuge 881 and does not need to be set up separately).

[0104] The upper purified oil layer, namely the light oil 8 with reduced silicon content after three-stage centrifugal phase separation, is transported to the alkaline washing reactor 991 for alkaline washing. The light oil 9 separated after alkaline washing is transported to the adsorption sedimentation tank 992 for adsorption sedimentation. The light oil 10 after adsorption sedimentation is transported to the filter 993 for filtration. The filtered light oil 11 is transported to the flash evaporator 994 for distillation and flash evaporation. The finished oil 12 after flash evaporation is collected.

[0105] The intermediate oil-water interface layer 13 after the third-stage centrifugal phase separation can be returned to the second-stage mechanically stirred tank 551 for further processing. The intermediate oil-water interface layer 14 after the second-stage centrifugal phase separation can be returned to the first-stage mechanically stirred tank 331 for further processing. The intermediate oil-water interface layer 15 after the first-stage centrifugal phase separation can be transported to the oil-water phase separator 995 for standing and phase separation.

[0106] The light phase 16 of the oil-water interface layer in the oil-water phase separator 995 can be returned to the storage tank A for further processing. Other waste liquids 17, 18, 19, 20, and 20 of the oil-water phase separator 995, the waste liquid 18, 19, 20, and 20 of the phase separation of the primary phase separator 442, the secondary phase separator 662, and the tertiary phase separator 882 can be transported to the storage tank 996 for further processing.

[0107] In summary, to ensure that the product meets high-quality oil standards, a follow-up process that allows for real-time processing can be added as needed after the desiliconization process to dynamically optimize the overall process.

[0108] The present invention will be further described in detail below with reference to specific embodiments.

[0109] Example 1

[0110] The method for separating organosilicon from waste oil in this embodiment is as follows:

[0111] Organosilicon was removed from the recovered waste white oil by emulsification and centrifugal demulsification. The initial silicon content in the waste white oil was 5968 ppm (tested according to ASTM D5185-18).

[0112] First, the waste white oil was centrifuged at 4000 rad / min for 15 minutes using an intermittent centrifugation method. After removing 5% of the total mass of the bottom layer of waste white oil, the upper layer of liquid was collected into a storage tank.

[0113] Subsequently, according to the weight, 4 parts of waste white oil and 1 part of water from the storage tank were added to the mechanical mixing tank, and then 0.6% of the waste white oil mass of surfactant alkylphenol polyoxyethylene ether OP10 was added. The mixture was thoroughly stirred and emulsified after 15 minutes.

[0114] After emulsification, the mixture was subjected to intermittent centrifugation at 4000 rad / min for 15 minutes, and the supernatant purified oil was collected.

[0115] According to ASTM D5185-18, the silicon content in the obtained upper purified oil was reduced to 413 ppm, with a removal rate of up to 93%.

[0116] Example 2

[0117] The method for separating organosilicon from waste oil in this embodiment is as follows:

[0118] Organosilicon was removed from the recovered waste white oil by emulsification and centrifugal demulsification. The initial silicon content in the waste white oil was 5968 ppm (tested according to ASTM D5185-18).

[0119] First, the waste white oil was centrifuged at 4000 rad / min for 15 minutes using an intermittent centrifugation method. After removing 5% of the total mass of the bottom layer of waste white oil, the upper layer of liquid was collected into a storage tank.

[0120] Subsequently, according to the weight, 5 parts of waste white oil and 1 part of water from the storage tank were added to the mechanical mixing tank, and then 0.4% of the waste white oil mass of surfactant Span80 was added. The mixture was thoroughly mixed and stirred, and fully emulsified after 15 minutes.

[0121] After emulsification, the mixture was subjected to intermittent centrifugation at 4000 rad / min for 15 minutes, and the supernatant purified oil was collected.

[0122] The obtained upper purified oil was washed with 1 mol / L sodium hydroxide. After washing, the upper purified oil was collected and mixed with 2 wt% clay for adsorption for 20 min at a controlled temperature of 50℃. After adsorption, the mixture was filtered, and the white oil liquid was collected. The white oil liquid was then subjected to vacuum distillation with gradually increasing temperature at 3 kPa, and finally raised to 295℃, with a distillation yield of 96%.

[0123] According to ASTM D5185-18, the silica content of the distilled white oil liquid was reduced to 334 ppm, and the organosilicon removal rate reached 94.4%.

[0124] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0125] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for separating organosilicon from waste oil, characterized in that, The method for separating organosilicon from waste oil includes the following steps: Waste oil containing organosilicon is first subjected to primary centrifugation to remove the lower layer liquid and collect the upper layer liquid; wherein the removed lower layer liquid is 1.25 to 25 times the mass of silicon in the waste oil. The upper liquid collected in the previous step, surfactant, and water are mixed and stirred to emulsify, resulting in an emulsified mixture. The emulsified mixture is demulsified to separate the phases, resulting in an upper purified oil layer, a middle oil-water interface layer containing organosilicon, and a lower water layer, thus achieving the separation of organosilicon from waste oil. The demulsification is performed using at least one of centrifugal demulsification, demulsification agent demulsification, and fabric filtration demulsification. When centrifugal demulsification is used, a continuous centrifuge is used for demulsification, with a centrifugation time of 10s-120s and a separation factor of 1000-30000; or, an intermittent centrifuge is used for demulsification, with a centrifugation time of 2min-30min and a separation factor of 800-20000. When using fabric filtration to demulsify the emulsion mixture, the filtration pressure is 0.1 MPa-0.5 MPa, and the surface flow velocity is 0.5 m / s. 3 / (m 2 ·h)-5m 3 / (m 2 ·h); When demulsifying by mixing the demulsifier with the emulsified mixture, the amount of demulsifier added is 0.01%-2% of the mass of the mixture.

2. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The amount of water used is 3%-32% of the mass of the waste oil.

3. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The amount of surfactant used is 0.1%-20% of the total mass of water and waste oil, or the amount of surfactant used is 0.5-60 times the mass of silicon in the waste oil.

4. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The surfactant is at least one of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants; The anionic surfactant is at least one of fatty acid salt surfactants, sulfonate surfactants, sulfate surfactants, and phosphate ester surfactants. The cationic surfactant is at least one of alkyl quaternary ammonium salt surfactant and benzyl quaternary ammonium salt surfactant; The nonionic surfactant is at least one of polyol fatty acid esters, fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, and block polyethers. The zwitterionic surfactant is at least one of betaine surfactants, imidazoline surfactants, and amino acid surfactants.

5. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The emulsification stirring speed is 200r / min-1200r / min, and the stirring time is 15min-120min.

6. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The upper purified oil layer, surfactant, and water are mixed, and then emulsification, demulsification, and phase separation are repeated.

7. The method for separating organosilicon from waste oil according to claim 6, characterized in that, The upper purified oil layer obtained after repeated emulsification, demulsification, and phase separation is subjected to alkaline washing, adsorption, filtration, and distillation.

8. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The intermediate oil-water interface layer containing organosilicon, surfactant, and water are mixed, and then emulsification, demulsification, and phase separation are repeated.

9. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The surfactant is a natural emulsifier, which is at least one of phospholipid emulsifiers, polysaccharide emulsifiers, protein emulsifiers, and sugar derivative emulsifiers.

10. The method for separating organosilicon from waste oil according to claim 1, characterized in that, The surfactant is a polymeric emulsifier, which is at least one of polyacrylate emulsifiers and polyurethane emulsifiers.

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