Industrial-grade mixed oil produced by utilizing kitchen waste oil and preparation method of industrial-grade mixed oil

Abstract

The invention discloses industrial-grade mixed oil produced by utilizing kitchen waste oil and a preparation method of the industrial-grade mixed oil, and belongs to the technical field of recycling of the kitchen waste oil. The invention relates to industrial-grade mixed oil produced by using kitchen waste oil and a preparation method thereof, and the preparation method comprises the following steps: firstly collecting kitchen waste containing the waste oil, and storing the kitchen waste in a container through special equipment; carrying out screen solid-liquid separation, cleaning grease on the surface of the solid waste, and then carrying out precipitation separation; then carrying out centrifugal separation, chemical cleaning, water washing, acid treatment, dehydration, degumming and metal ion removal on the separated grease and oil-containing liquid; carrying out ultrasonic-assisted multistage ester exchange after enzymolysis optimization, carrying out membrane separation on glycerol and fatty acid methyl ester, and carrying out reduced pressure distillation to obtain a high-purity fraction; carrying out adsorption refining, plasma treatment and supercritical fluid extraction; finally, nano particles are added and blended with additives, efficient recycling of the kitchen waste oil is achieved, and then high-purity industrial-grade mixed oil is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste cooking oil, and more specifically to an industrial-grade mixed oil produced by utilizing waste cooking oil and a preparation method thereof. Background Art

[0002] Waste cooking oil refers to the oil that is no longer suitable for consumption after cooking, frying and other operations during the catering service process. It comes from a wide range of sources, including waste cooking oil from restaurants, canteens, food processing plants and other places. It usually contains food residues, water, free fatty acids, phospholipids and organic pollutants.

[0003] Industrial-grade mixed oil is the product obtained by processing and transforming waste cooking oil through a series of complex and sophisticated treatment processes. It undergoes multiple steps such as collection, separation, purification, ester exchange reaction, separation and purification to remove impurities, odors, and harmful substances in waste cooking oil, so that it meets the standard requirements for industrial application in key indicators such as acid value, peroxide value, color, odor, moisture and volatile matter content. It can be used in industrial fields such as biodiesel production, industrial lubricant base oil formulation, and chemical raw material synthesis. While realizing the resource utilization of waste cooking oil, it also provides a cost-effective and environmentally friendly raw material option for related industries.

[0004] However, the existing industrial-grade mixed oil produced by using waste cooking oil and its preparation method often have the following problems:

[0005] Firstly, the traditional collection and treatment of waste kitchen oil often lacks systematicity and refinement. In many cases, the visible grease is simply separated from the kitchen waste in a rough manner, and there is no effective means to recycle the large amount of grease still attached to the surface of solid waste. For example, in some small-scale treatment facilities, grease and solid waste are separated only by natural standing or simple one-time filtration, which causes a large amount of grease to be discarded along with the solid waste, resulting in serious waste of raw materials. Moreover, due to the lack of deep grease cleaning and multi-step separation treatment of solid waste, the recovered grease is mixed with a large amount of solid impurities, such as food residue particles, fibers, etc., as well as some water-soluble impurities, such as residual salts, sugars, etc. These impurities not only reduce the purity of the raw oil, but also cause a series of problems in the subsequent processing process. For example, solid impurities may be deposited in the reaction equipment, affecting the heat transfer efficiency and normal operation of the equipment, and increasing the cost and frequency of equipment cleaning and maintenance; water-soluble impurities may participate in side reactions in chemical reactions, generate unnecessary products, increase the difficulty of subsequent separation and purification, and reduce the yield and quality of the product, resulting in high costs for the entire production process and difficulty in stably producing high-quality industrial-grade mixed oil;

[0006] Secondly, traditional methods usually have the defects of simple steps and lack of precise control during pretreatment. Some pretreatments may only carry out simple dehydration or a single chemical treatment, while ignoring the presence of multiple impurities at the same time. For example, some processes only carry out general heating and dehydration, without systematic treatment of acidic impurities, phospholipids and metal ions that may be contained in oils and fats. If acidic impurities are not effectively removed, they will accelerate the oxidation and rancidity of oils and fats during subsequent storage and processing, shortening the shelf life of products. If phospholipids remain, foam is easily generated during high-temperature processing, affecting the smooth progress of the reaction, and making the product color darker and less stable. The presence of metal ions may catalyze the oxidation reaction of oils and fats, and in some subsequent reactions, they act as impurities to affect the activity and selectivity of the reaction. Due to the lack of pretreatment processes such as sodium hydroxide chemical cleaning, dilute sulfuric acid treatment, degumming and metal ion removers in this method, which are multi-step coordinated and accurately controlled parameters, it is difficult for traditional methods to reduce various impurities in oils and fats to an ideal level, resulting in low conversion rates of core processes such as subsequent ester exchange reactions, increased side reactions, and product quality such as acid value, peroxide value, color, etc. It is difficult to meet high-standard industrial-grade requirements. The product has poor stability, which limits its application in industrial fields with high quality requirements.

[0007] Thirdly, in the traditional process of preparing industrial-grade mixed oil from waste cooking oil, the separation and refining means are relatively limited. Common separation methods are mostly simple static stratification and rough distillation. The separation of glycerol and fatty acid methyl esters is not accurate enough, which easily causes the two to be entrained with each other, affecting the purity of the product. For example, in the distillation process, due to the lack of a step of accurate separation based on molecular characteristics like the membrane separation technology in the present method, the fatty acid methyl esters in glycerol and the trace glycerol in the fatty acid methyl esters cannot be effectively removed, resulting in a high impurity content in the product. In addition, traditional adsorption refining mostly uses a single adsorbent, such as ordinary activated white clay, which has a limited adsorption effect and cannot deeply remove impurities such as odor, pigments and trace metal ions in the mixed oil, leading to The product's color, smell and other quality indicators are poor. In addition, traditional methods hardly involve advanced in-depth integrated technologies such as plasma treatment, supercritical fluid extraction and refining, and nanoparticle addition. Without plasma treatment, residual harmful organic matter, microorganisms and long-chain polymers cannot be effectively decomposed, and the safety and stability of the product cannot be guaranteed. The lack of supercritical fluid extraction and refining makes it difficult to remove some trace impurities that are difficult to remove by traditional methods, limiting the application of the product in high-end industrial fields. Without the addition of nanoparticles, the lubrication and rheological properties of the mixed oil cannot be improved, and cannot meet the needs of industrial scenarios with strict requirements on oil performance such as high-end mechanical lubrication and special chemical synthesis. The product has low added value and insufficient market competitiveness.

[0008] In view of this, we propose an industrial-grade mixed oil produced using waste cooking oil and a preparation method thereof. Summary of the invention

[0009] 1. Technical issues to be solved

[0010] The object of the present invention is to provide an industrial-grade mixed oil produced by using waste cooking oil and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0011] 2. Technical solution

[0012] An industrial-grade mixed oil produced using waste kitchen oil and a preparation method thereof, the specific steps are as follows: S1: Collection: Collect the waste oil-containing portion from kitchen waste, use a special kitchen waste collection device to collect the waste and grease together into a storage container.

[0013] S2: Solid-liquid separation of garbage: Use screen filtration to separate solid garbage and liquid garbage;

[0014] S3: Cleaning and collection of grease on the garbage surface: After that, the solid garbage is placed in the cleaning pool, and the grease on the garbage surface is washed with clean water. After the washing is completed, the large-volume impurities are intercepted again by sieve filtration. The cleaning water containing grease can be pumped to the sedimentation tank through a water pump to let it settle naturally. Since the density of grease is smaller than that of water, it will gradually float to the liquid surface, while the solid particles will settle to the bottom of the pool. The sedimentation time is 1 to 5 hours to ensure that the solid and grease have enough time to separate;

[0015] S4: Mechanical separation: After the grease in S3 is separated, the grease on the surface of the garbage and the liquid containing grease initially filtered out by S1 can be transported to the centrifuge together. The centrifuge rotates at 1000-3000 rpm for 5-10 minutes, so that the solid particles are precipitated at the bottom and the grease is separated from the upper layer.

[0016] S5: Chemical cleaning: Put the initially separated grease and a small amount of residual solids into a cleaning tank, add 1% to 3% sodium hydroxide solution, stir at 40 to 60°C and 50 to 100 rpm for 10 to 30 minutes to clean the acidic impurities in the grease and the grease attached to the solids;

[0017] S6: Water washing: The grease and solid mixture after washing is then rinsed with clean water, and the water washing is repeated several times until the pH value of the rinsed water is close to 7;

[0018] S7: Acid treatment: add an appropriate amount of 0.5% to 1% dilute sulfuric acid, stir at 50 to 60°C for 10 to 15 minutes, and then filter to remove the decomposition products;

[0019] S8: Dehydration: Remove moisture from the oil at 80-100°C and a reduced vacuum degree of 0.08-0.09MPa to reduce the moisture content to below 0.5%;

[0020] S9: Degumming: Add phosphoric acid to the dehydrated waste oil in an amount of 0.1% to 0.3% of the oil mass, stir at 60 to 70°C for 10 to 20 minutes at a speed of 80 to 100 rpm to precipitate phospholipids and other colloids in the oil, and filter to remove the colloids.

[0021] S10: Metal ion removal: Add 0.1% to 0.2% ethylenediaminetetraacetic acid solution and stir for 10 to 15 minutes to remove metal ions in the waste oil;

[0022] S11: Ultrasonic-assisted transesterification: Put the waste oil after enzymatic hydrolysis optimization into the reactor, add methanol oil and methanol in a molar ratio of 1:6-1:8 and sodium hydroxide in an amount of 0.5%-1% of the oil mass. React at 60-70°C, stir at 120-150 rpm, and during the reaction, ultrasonically treat for 2-3 minutes every 5-10 minutes at an ultrasonic frequency of 20-40kHz;

[0023] S12: Multi-stage transesterification: Multi-stage transesterification is used. After the first-stage reaction, part of the product is separated and the remaining reactants are added with new methanol and catalyst to carry out the next-stage reaction.

[0024] S13: membrane separation: after all reactions are completed, in addition to static stratification, glycerol and fatty acid methyl esters are further separated according to their molecular sizes and properties using a hydrophilic-hydrophobic separation membrane, with the lower layer being glycerol and the upper layer being fatty acid methyl esters;

[0025] S14: vacuum distillation: placing the fatty acid methyl ester in a vacuum distillation apparatus, distilling for 30 to 40 minutes at 160 to 180° C. and a vacuum degree of 0.09 to 0.1 MPa to remove unreacted methanol, residual water and a small amount of light impurities, and obtaining a high-purity fatty acid methyl ester fraction;

[0026] S15: Adsorption refining: using a composite adsorbent of modified activated clay and nano-activated carbon at a mass ratio of 2:1 to 3:1, stirring and adsorbing at 55 to 65°C for 40 to 60 minutes, deeply removing odor, pigments, trace metal ions and remaining impurities in the mixed oil, and improving the color and stability of the oil;

[0027] S16: Plasma treatment: The adsorbed refined mixed oil is introduced into the plasma treatment device. In an argon or helium atmosphere, a low-temperature plasma jet with a power of 200 to 400 watts is used for a treatment time of 15 to 25 minutes to contact the mixed oil. With the help of high-energy active particles, residual harmful organic matter, microorganisms and long-chain polymers are decomposed, the surface of oil molecules is activated, and the compatibility with other additives is enhanced, further improving the quality and safety of the mixed oil.

[0028] S17: Supercritical fluid extraction and refining: After adsorption refining to remove odor, pigments and trace impurities, and plasma treatment to decompose residual harmful organic matter, supercritical fluid extraction and refining are carried out;

[0029] S18: Addition of nanoparticles: a certain amount of nano-titanium dioxide with a particle size of 20 to 50 nm and an addition amount of 0.05% to 0.15% of the oil mass is evenly dispersed in the industrial-grade mixed oil, and treated under ultrasonic conditions with an ultrasonic frequency of 30 to 50 kHz and an ultrasonic time of 20 to 30 minutes to fully disperse the nanoparticles and interact with the oil molecules. Nano-titanium dioxide has good photocatalytic and antioxidant properties, and can inhibit the oxidation and deterioration of the mixed oil during storage and use to a certain extent. At the same time, its nano-size effect can improve the lubrication and rheological properties of the mixed oil, making it more suitable for some industrial fields with high requirements for oil performance, such as high-end mechanical lubrication, special chemical synthesis, etc.

[0030] S19: Post-processing and blending: After extraction and refining, the industrial-grade mixed oil modified with nanomaterials can be mixed with other additives such as antioxidants, lubricants, etc. in a specific proportion to further optimize its performance to meet the needs of different industrial applications. For example, adding an appropriate amount of antioxidants such as vitamin E in an amount of 0.03% to 0.08% of the oil mass can enhance its antioxidant capacity, or adding specific extreme pressure anti-wear agents such as zinc dialkyl dithiophosphate in an amount of 0.1% to 0.3% of the oil mass can improve its lubrication performance.

[0031] Preferably, the industrial-grade mixed oil is prepared by the above method.

[0032] 3. Beneficial effects

[0033] Compared with the prior art, the advantages of the present invention are: starting from the collection of kitchen waste at the source, using special equipment to collect the waste oil-containing part, and fully recovering and preliminarily purifying the grease on the surface of solid waste through multiple steps such as screen filtration, washing in a cleaning pool, and sedimentation. Compared with the traditional method, more waste grease raw materials can be obtained and the raw materials are of higher purity, reducing the cost increase caused by the waste of raw materials and the difficulty of subsequent processing. For example, in the steps of solid-liquid separation of garbage and surface grease cleaning and collection, a large amount of solid impurities and some water-soluble impurities can be effectively removed through multiple screening and sedimentation, laying the foundation for subsequent high-quality oil refining;

[0034] In the pretreatment stage, chemical cleaning, water cleaning, acid treatment, dehydration, degumming, metal ion removal and other steps are closely linked and the parameters are precisely controlled. Sodium hydroxide chemical cleaning can remove acidic impurities and attached grease in a targeted manner. Dilute sulfuric acid treatment further decomposes organic impurities and metal complexes. Dehydration makes the moisture meet the standard. Degumming removes phospholipids. Metal ion removers chelate metal ions. The synergistic effect of each step greatly reduces the types and contents of impurities in the oil, improves the quality of the oil, reduces the adverse effects of impurities on subsequent ester exchange reactions, and improves reaction efficiency and product stability. Traditional methods may have some problems in the pretreatment step. It is relatively simple and cannot achieve such a comprehensive purification effect. On this basis, an enzymatic hydrolysis optimization step is introduced, using specific lipases to accurately act on the waste oil ester structure under suitable conditions, decomposing it into small molecules that are more conducive to the reaction, significantly improving the subsequent transesterification reaction conversion rate and selectivity. Combined with ultrasound-assisted transesterification and multi-stage transesterification technology, the cavitation effect of ultrasound enhances molecular collision and mixing, and multi-stage transesterification further improves the reaction depth and product yield. Compared with traditional transesterification methods, higher purity and more fatty acid methyl ester products can be obtained in a shorter time, reducing production costs and energy consumption;

[0035] Secondly, membrane separation technology accurately separates glycerol and fatty acid methyl esters based on molecular characteristics, and uses vacuum distillation to effectively remove light impurities such as unreacted methanol. Adsorption refining uses a new type of composite adsorbent to deeply remove odors, pigments, etc. at a specific temperature and time, and subsequently increases plasma treatment, supercritical fluid extraction refining and nanoparticle addition steps. Plasma can decompose residual harmful substances and activate oils, supercritical fluid extraction can deeply purify them, and nanoparticles improve oil performance. These steps are progressive, making the mixed oil far superior to the products obtained by traditional preparation methods in quality, stability, safety and applicability, and can meet the stringent requirements of high-end industrial fields for oils, while traditional preparation methods often lack such multi-level and multi-technical deep refining methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The overall manufacturing process diagram of the present invention is as follows: DETAILED DESCRIPTION

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In the description of the present invention, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] Please refer to the figure, the present invention provides a technical solution:

[0041] An industrial-grade mixed oil produced using waste kitchen oil and a preparation method thereof, the specific steps are as follows: S1: Collection: Collect the waste oil-containing portion from kitchen waste, use a special kitchen waste collection device to collect the waste and grease together into a storage container.

[0042] In some embodiments: the food waste collection equipment is a professional food waste collection vehicle or collection box, which has an anti-leakage and preliminary separation structure inside, which can minimize grease leakage during the collection process and initially block larger volumes of solid waste, and transport the collected garbage and grease mixture to a storage container, such as a large stainless steel storage tank, which has a sealing cover and a discharge port so that the material can be easily discharged during subsequent processing.

[0043] S2: Solid-liquid separation of garbage: Use screen filtration to separate solid garbage and liquid garbage;

[0044] In some embodiments: the equipment used for solid-liquid separation of garbage is a multi-layer stainless steel screen with different mesh sizes. For example, a 10-20 mesh screen is first used for preliminary coarse screening to separate larger pieces of solid garbage, and then a 50-100 mesh screen is used for further screening to allow the liquid to pass more smoothly. The solid garbage is intercepted on the screen. The screen is installed on an inclined bracket, and a liquid collection trough and a solid garbage collection box are provided underneath to facilitate the collection of separated liquid and solid.

[0045] S3: Cleaning and collection of grease on the garbage surface: After that, the solid garbage is placed in the cleaning pool, and the grease on the garbage surface is washed with clean water. After the washing is completed, the large-volume impurities are intercepted again by sieve filtration. The cleaning water containing grease can be pumped to the sedimentation tank through a water pump to let it settle naturally. Since the density of grease is smaller than that of water, it will gradually float to the liquid surface, while the solid particles will settle to the bottom of the pool. The sedimentation time is 1 to 5 hours to ensure that the solid and grease have enough time to separate;

[0046] In some embodiments: the cleaning tank is made of stainless steel and is equipped with a nozzle with adjustable water flow direction and intensity to flush the surface of solid waste. A 50-100 mesh filter is used again to intercept and filter large impurities in the cleaned mixture. The water pump is a corrosion-resistant centrifugal pump to transport the cleaning water containing grease to the sedimentation tank. The sedimentation tank is made of concrete or stainless steel and is equipped with a guide plate to guide the water to flow slowly so that the grease can fully float and separate. The sedimentation time is controlled at 1-5 hours by a timer. A mud outlet is set at the bottom of the tank for regular cleaning of precipitated solid particles.

[0047] S4: Mechanical separation: After the grease in S3 is separated, the grease on the surface of the garbage and the liquid containing grease initially filtered out by S1 can be transported to the centrifuge together. The centrifuge rotates at 1000-3000 rpm for 5-10 minutes, so that the solid particles are precipitated at the bottom and the grease is separated from the upper layer.

[0048] In some embodiments: the centrifuge is a high-speed stainless steel centrifuge with a speed adjustment function, which can be accurately set at 1000-3000 rpm. The centrifugation time is controlled at 5-10 minutes by a timer. There are special material feed pipes and solid and liquid discharge ports inside the centrifuge. Solid particles fall into the solid collection container through the discharge port under the action of centrifugal force, and grease flows into the subsequent processing container from another discharge port.

[0049] S5: Chemical cleaning: Put the initially separated grease and a small amount of residual solids into a cleaning tank, add 1% to 3% sodium hydroxide solution, stir at 40 to 60°C and 50 to 100 rpm for 10 to 30 minutes to clean the acidic impurities in the grease and the grease attached to the solids;

[0050] In some embodiments: the cleaning tank is made of stainless steel, with a sealing cover, an agitator and a temperature control system. The agitator is a paddle agitator that can stably operate within a speed range of 50 to 100 rpm, and the temperature control system can accurately control the temperature in the tank at 40 to 60°C. The sodium hydroxide solution is added to the cleaning tank according to a set ratio through a corrosion-resistant metering pump, and a discharge port is provided at the bottom of the cleaning tank to facilitate the discharge of the cleaned material.

[0051] S6: Water washing: The grease and solid mixture after washing is then rinsed with clean water, and the water washing is repeated several times until the pH value of the rinsed water is close to 7;

[0052] In some embodiments: a multi-stage water washing device is used, which consists of multiple stainless steel water washing tanks connected in series, each water washing tank is equipped with a nozzle and a drain, and clean water flows into each water washing tank in turn through pipes and valves. The liquid level difference or a water pump is used to make the water flow between the tanks. The pH value of the flushing water can be monitored in real time by a pH sensor. When the pH value is close to 7, the water flow direction is switched by an automatic valve to transport the treated grease and solid mixture to the next treatment step.

[0053] S7: Acid treatment: add an appropriate amount of 0.5% to 1% dilute sulfuric acid, stir at 50 to 60°C for 10 to 15 minutes, and then filter to remove the decomposition products;

[0054] In some embodiments: the acid treatment tank is made of stainless steel and is equipped with an agitator and a temperature control system. The agitator is similar to the paddle agitator in the chemical cleaning step, and the speed can meet the stirring requirements of 10 to 15 minutes, and the temperature is controlled at 50 to 60°C. Dilute sulfuric acid is added to the acid treatment tank through a corrosion-resistant metering pump, and a filtering device, such as a filter screen or a filter element filter, is provided at the bottom of the acid treatment tank to filter and remove the decomposition products after the stirring is completed, and the filtrate flows into the next step treatment container.

[0055] S8: Dehydration: Remove moisture from the oil at 80-100°C and a reduced vacuum degree of 0.08-0.09MPa to reduce the moisture content to below 0.5%;

[0056] In some embodiments: dehydration is performed using a vacuum distillation device, which is mainly composed of a distillation tower, a condenser, a vacuum pump and a heating system. The distillation tower is made of stainless steel and is provided with fillers or plates inside to increase the gas-liquid contact area and improve the dehydration efficiency. The heating system can be electrically heated or steam heated to control the temperature in the distillation tower at 80-100°C. The vacuum pump maintains the pressure in the tower at a vacuum degree of 0.08-0.09MPa. The water vapor is cooled into liquid water in the condenser and discharged. The dehydrated oil and fat flows into the next processing container from the discharge port at the bottom of the distillation tower.

[0057] S9: Degumming: Add phosphoric acid to the dehydrated waste oil in an amount of 0.1% to 0.3% of the oil mass, stir at 60 to 70°C for 10 to 20 minutes at a speed of 80 to 100 rpm to precipitate phospholipids and other colloids in the oil, and filter to remove the colloids.

[0058] In some embodiments: the degumming tank is made of stainless steel and is equipped with a stirrer and a temperature control system. The stirrer is an anchor stirrer, which can fully mix the phosphoric acid and the grease at a speed of 80 to 100 rpm, and the temperature is controlled at 60 to 70° C. The phosphoric acid is added to the degumming tank through a metering pump, and a filtering device, such as a plate and frame filter press, is provided at the bottom of the degumming tank to filter and remove the precipitated colloid, and the filtrate enters the next metal ion removal step.

[0059] S10: Metal ion removal: Add 0.1% to 0.2% ethylenediaminetetraacetic acid solution and stir for 10 to 15 minutes to remove metal ions in the waste oil;

[0060] In some embodiments: metal ion removal is carried out in a stainless steel reactor with a stirrer, the stirrer is a turbine stirrer, which can fully mix the ethylenediaminetetraacetic acid solution and the oil within 10 to 15 minutes, and the rotation speed is within a suitable range to ensure uniform reaction. The ethylenediaminetetraacetic acid solution is added to the reactor through a metering pump, and after the reaction is completed, the metal ion complex precipitate generated by the reaction is removed through a filtering device such as a precision filter, and the filtrate enters the transesterification reaction step.

[0061] S11: Ultrasonic-assisted transesterification: Put the waste oil after enzymatic hydrolysis optimization into the reactor, add methanol oil and methanol in a molar ratio of 1:6-1:8 and sodium hydroxide in an amount of 0.5%-1% of the oil mass. React at 60-70°C, stir at 120-150 rpm, and during the reaction, ultrasonically treat for 2-3 minutes every 5-10 minutes at an ultrasonic frequency of 20-40kHz;

[0062] In some embodiments: the reactor is made of stainless steel and is equipped with an agitator, a temperature control system and an ultrasonic generator. The agitator is a propeller agitator with a rotation speed of 120 to 150 rpm and a temperature control of 60 to 70°C. The ultrasonic generator can generate an ultrasonic frequency of 20 to 40 kHz, and transmits the ultrasonic wave to the reaction material in the reactor through an ultrasonic transducer. The reactor is provided with a feed port for methanol and a sodium hydroxide solution, and the feed is controlled by a metering pump to achieve a molar ratio of oil to methanol of 1:6 to 1:8 and a sodium hydroxide dosage of 0.5% to 1% of the mass of the oil. After the reaction is completed, the material is transported to the next step through the discharge port.

[0063] S12: Multi-stage transesterification: Multi-stage transesterification is used. After the first-stage reaction, part of the product is separated and the remaining reactants are added with new methanol and catalyst to carry out the next-stage reaction.

[0064] In some embodiments: In addition to the reactor similar to S11, multiple intermediate product storage containers, such as stainless steel storage tanks, are required to store part of the separated products after each stage of transesterification reaction. When the next stage of reaction is carried out, the remaining reactants and new methanol and catalyst are respectively transported from the corresponding storage containers and the feeding device to the reactor by a metering pump, and the stirring, temperature control and ultrasonic auxiliary equipment of the reactor are the same as S11.

[0065] S13: membrane separation: after all reactions are completed, in addition to static stratification, glycerol and fatty acid methyl esters are further separated according to their molecular sizes and properties using a hydrophilic-hydrophobic separation membrane, with the lower layer being glycerol and the upper layer being fatty acid methyl esters;

[0066] In some embodiments: a hydrophilic-hydrophobic separation membrane assembly is used, the outer shell of the membrane assembly is made of stainless steel, and a hydrophilic-hydrophobic separation membrane of a specific pore size and material is installed inside, such as a membrane made of polyvinylidene fluoride (PVDF) or polypropylene (PP). The membrane assembly is equipped with a pressure control system that can adjust the pressure difference on both sides of the membrane to achieve separation based on the molecular size and property differences of glycerol and fatty acid methyl ester. The membrane separation device also includes a feed pump to transport the mixture after the reaction to the membrane assembly. The separated glycerol is collected from a discharge port on one side of the membrane assembly, and the fatty acid methyl ester flows into the next step of the vacuum distillation device from the discharge port on the other side.

[0067] S14: vacuum distillation: placing the fatty acid methyl ester in a vacuum distillation apparatus, distilling for 30 to 40 minutes at 160 to 180° C. and a vacuum degree of 0.09 to 0.1 MPa to remove unreacted methanol, residual water and a small amount of light impurities, and obtaining a high-purity fatty acid methyl ester fraction;

[0068] In some embodiments: the vacuum distillation device is similar to the equipment in S8, and is composed of a distillation tower, a condenser, a vacuum pump, and a heating system. The distillation tower is made of stainless steel, and its internal structure is suitable for the distillation and separation of fatty acid methyl esters. The heating system controls the temperature in the distillation tower at 160-180°C, and the vacuum pump maintains the pressure in the tower at a vacuum degree of 0.09-0.1MPa. Unreacted methanol, residual water, and a small amount of light impurities are separated during the distillation process, and the high-purity fatty acid methyl ester fraction flows into the adsorption refining step from the bottom outlet of the distillation tower.

[0069] S15: Adsorption refining: using a composite adsorbent of modified activated clay and nano-activated carbon at a mass ratio of 2:1 to 3:1, stirring and adsorbing at 55 to 65°C for 40 to 60 minutes, deeply removing odor, pigments, trace metal ions and remaining impurities in the mixed oil, and improving the color and stability of the oil;

[0070] In some embodiments: adsorption refining is carried out in a stainless steel adsorption tank with an agitator. The agitator is a paddle agitator. The rotation speed can make the composite adsorbent and the mixed oil fully contact within 40 to 60 minutes. The temperature is controlled at 55 to 65°C. The composite adsorbent of modified activated clay and nano-activated carbon is added to the adsorption tank through a metering device at a mass ratio of 2:1 to 3:1. A filtering device, such as a precision filter, is provided at the bottom of the adsorption tank to filter and remove the adsorbent and impurities after adsorption. The filtrate enters the plasma treatment step.

[0071] S16: Plasma treatment: The adsorbed refined mixed oil is introduced into the plasma treatment device. In an argon or helium atmosphere, a low-temperature plasma jet with a power of 200 to 400 watts is used for a treatment time of 15 to 25 minutes to contact the mixed oil. With the help of high-energy active particles, residual harmful organic matter, microorganisms and long-chain polymers are decomposed, the surface of oil molecules is activated, and the compatibility with other additives is enhanced, further improving the quality and safety of the mixed oil.

[0072] In some embodiments: the plasma treatment device includes a plasma generator, a reaction chamber and a gas supply system. The reaction chamber is made of stainless steel and is equipped with electrodes and a sample placement rack. The plasma generator can generate a low-temperature plasma jet with a power of 200 to 400 watts. The treatment time is controlled by a timer at 15 to 25 minutes. The gas supply system can provide inert gases such as argon or helium to maintain the atmosphere in the reaction chamber. The treated mixed oil flows from the discharge port of the reaction chamber into the supercritical fluid extraction and refining step.

[0073] In some embodiments: when most conventional impurities have been removed, plasma treatment can utilize its high-energy active particles (such as electrons, ions, free radicals, etc.) to undergo complex physical and chemical reactions with trace amounts of residual organic matter, microorganisms, and possible long-chain polymers in the mixed oil. These reactions can further decompose or modify harmful or unstable substances, such as destroying the molecular structure of harmful substances such as residual pesticides and polycyclic aromatic hydrocarbons, converting them into harmless or easier to separate and remove small molecules, while performing a certain degree of surface activation on the oil molecules to improve their performance in subsequent applications, such as enhancing compatibility with other additives, thereby further improving the quality of the mixed oil.

[0074] S17: Supercritical fluid extraction and refining: After adsorption refining to remove odor, pigments and trace impurities, and plasma treatment to decompose residual harmful organic matter, supercritical fluid extraction and refining are carried out;

[0075] In some embodiments: the supercritical fluid extraction device is mainly composed of an extraction kettle, a separation kettle, a carbon dioxide storage tank, a high-pressure pump and a temperature and pressure control system. The extraction kettle and the separation kettle are made of stainless steel and can withstand a pressure of 8 to 12 MPa. The temperature and pressure control system can accurately control the temperature in the extraction kettle at 35 to 45°C and the pressure at 8 to 12 MPa. The extraction time is controlled by a timer at 30 to 60 minutes. The carbon dioxide storage tank stores liquid carbon dioxide, and the high-pressure pump pressurizes the carbon dioxide to a supercritical state and then transports it to the extraction kettle, where it contacts the mixed oil for extraction. The extracted carbon dioxide and dissolved impurities are separated in the separation kettle by adjusting the pressure and temperature, and the carbon dioxide is recycled to the storage tank for recycling. The refined mixed oil flows out from the discharge port of the separation kettle and enters the nanoparticle addition step.

[0076] In some embodiments: supercritical carbon dioxide has unique physical and chemical properties. In the supercritical state (temperature 35-45°C, pressure 8-12MPa), its density is close to that of liquid, and it has strong solubility. It can dissolve various residual impurities in the mixed oil, such as some residual organic pollutants, trace heavy metal complexes, unreacted small molecular organic matter, etc. At the same time, its viscosity and diffusion coefficient are close to those of gas, which makes it have good mass transfer performance, and it can quickly penetrate into the mixed oil to contact and dissolve the impurities. In addition, supercritical carbon dioxide is selective for the solubility of different substances. It has relatively low solubility for the target oil component in the mixed oil, but high solubility for impurities and harmful substances. When the supercritical carbon dioxide is fully in contact with the mixed oil, the impurities are dissolved and carried out. By adjusting the pressure and temperature, the carbon dioxide is converted into a gaseous state and escaped, thereby realizing the separation of impurities and the mixed oil, significantly reducing the residual harmful substances in the mixed oil, and obtaining a purer and higher quality mixed oil product, so that it can better meet the strict requirements of high-end industrial applications for oil purity and safety.

[0077] S18: Addition of nanoparticles: a certain amount of nano-titanium dioxide with a particle size of 20 to 50 nm and an addition amount of 0.05% to 0.15% of the oil mass is evenly dispersed in the industrial-grade mixed oil, and treated under ultrasonic conditions with an ultrasonic frequency of 30 to 50 kHz and an ultrasonic time of 20 to 30 minutes to fully disperse the nanoparticles and interact with the oil molecules. Nano-titanium dioxide has good photocatalytic and antioxidant properties, and can inhibit the oxidation and deterioration of the mixed oil during storage and use to a certain extent. At the same time, its nano-size effect can improve the lubrication and rheological properties of the mixed oil, making it more suitable for some industrial fields with high requirements for oil performance, such as high-end mechanical lubrication, special chemical synthesis, etc.

[0078] In some embodiments: nanoparticles are added in a stainless steel mixing tank with an ultrasonic device. The ultrasonic device can generate an ultrasonic frequency of 30 to 50 kHz, and the ultrasonic time is controlled by a timer at 20 to 30 minutes. Nano titanium dioxide is added to the mixing tank according to 0.05% to 0.15% of the oil mass through a metering device. The stirrer is a paddle stirrer, so that the nanoparticles are fully dispersed and interact with the oil molecules under the action of ultrasound and stirring, and the mixed oil enters the post-processing and preparation steps.

[0079] S19: Post-processing and blending: After extraction and refining, the industrial-grade mixed oil modified with nanomaterials can be mixed with other additives such as antioxidants, lubricants, etc. in a specific proportion to further optimize its performance to meet the needs of different industrial applications. For example, adding an appropriate amount of antioxidants such as vitamin E in an amount of 0.03% to 0.08% of the oil mass can enhance its antioxidant capacity, or adding specific extreme pressure anti-wear agents such as zinc dialkyl dithiophosphate in an amount of 0.1% to 0.3% of the oil mass can improve its lubrication performance.

[0080] In some embodiments: the process is carried out in a post-processing and blending tank, which is made of stainless steel and equipped with a stirrer. Additives such as antioxidants (such as vitamin E) and lubricants (such as zinc dialkyl dithiophosphate) are added to the blending tank in a specific proportion through a metering pump, and the stirrer is a paddle stirrer to fully stir the additives and the mixed oil. The stirring time is determined according to the properties and addition amount of the additives, and finally an industrial-grade mixed oil product that meets the requirements of different industrial applications is obtained, and the product is transported to a storage container or packaging equipment through a pipeline.

[0081] In some embodiments, according to the needs of different industrial applications, specific proportions of antioxidants, lubricants and other additives can be accurately added, such as vitamin E antioxidants and zinc dialkyl dithiophosphate extreme pressure anti-wear agents, which can optimize the performance of the mixed oil in a targeted manner. Compared with the traditional general formulation method, the product can better adapt to diversified industrial scenarios such as high-end mechanical lubrication and specialty chemical synthesis, thereby improving product added value and market competitiveness.

[0082] Specifically, the industrial-grade mixed oil is prepared by the above method.

[0083] In some embodiments: the power supply designed by the method can be powered by an external conventional power supply, and each link thereof is controlled by a controller.

[0084] In addition, the circuits, electronic components and modules involved in the present invention are all prior art and can be fully implemented by those skilled in the art. Needless to say, the content protected by the present invention does not involve improvements to the internal structure and methods.

[0085] Working principle: First, the kitchen waste containing waste oil is collected into storage containers through special kitchen waste collection equipment to provide raw materials for subsequent processing. The solid-liquid separation of the garbage is carried out by screen filtration. According to the difference in size between solid and liquid particles, large particles of solid waste are intercepted to allow the oil-containing liquid to pass through, and the liquid part containing waste oil is initially separated. Then, the solid waste is cleaned with grease, and the grease on its surface is washed out with clean water and stirring. After filtering large impurities through the screen, the grease-containing cleaning water relies on gravity to settle in the sedimentation tank. Because the density of grease is less than that of water, during the 1-5h sedimentation process, the grease floats up and the solid sinks, achieving further separation of solid and liquid. Subsequently, the grease on the surface of the garbage is separated from the initial grease. The filtered oily liquid is sent to a centrifuge together and rotated at a speed of 1000-3000 rpm for 5-10 minutes. With the help of centrifugal force, the solid particles are precipitated to the bottom and the oil is floated and separated. After that, the separated oil is chemically cleaned, 1%-3% sodium hydroxide solution is added and stirred at 40-60°C and 50-100 rpm for 10-30 minutes in a stirrer. Sodium hydroxide neutralizes the acidic impurities in the oil to generate water-soluble substances, and at the same time destroys the adsorption force between the oil and solid impurities, so that the oil is separated from the solid and dissolved. Then it is washed with water until the pH value of the rinse water is close to 7 to remove the residual sodium hydroxide and water-soluble impurities. An appropriate amount of 0.5%-1% dilute sulfuric acid is added and stirred at 50-60°C for 1 0-15 minutes, so that part of the organic impurities and metal ion complexes in the oil are decomposed and transformed, the decomposition products are filtered out, and the oil is dehydrated in a vacuum dehydrator at 80-100°C and 0.08-0.09MPa vacuum degree, and the water boiling point is reduced by heating and reducing pressure to promote water evaporation, so that the water content is reduced to below 0.5%, and 0.1%-0.3% phosphoric acid by oil mass is added to the waste oil after dehydration, and the oil is stirred in a stirrer at 60-70°C and 80-100 rpm for 10-20 minutes to filter out the colloid precipitation such as phospholipids, and 0.1%-0.2% ethylenediaminetetraacetic acid solution is added and stirred for 10-15 minutes to remove metal ions by chelation. In the ester exchange reaction stage, the treated The waste oil is put into the reactor, methanol and an appropriate amount of sodium hydroxide in a specific molar ratio are added, reacted at 60-70°C and stirred at 120-150 rpm, and ultrasonically treated for 2-3 minutes every 5-10 minutes at a frequency of 20-40kHz. The ultrasonic cavitation effect enhances the collision and mixing of molecules, improves the reaction conversion rate and product purity, and can also be used for multi-stage ester exchange. After the first-stage reaction, part of the product is separated, and the remaining reactants are added with new methanol and a catalyst for the next-stage reaction. After the reaction, the hydrophilic and hydrophobic separation membrane is used to separate glycerol and fatty acid methyl ester according to the molecular size and property differences. The lower layer of glycerol is recovered, and the upper layer of fatty acid methyl ester enters the vacuum distillation, and the reaction temperature is 160-180°C and 0.09-0.Distill for 30 to 40 minutes at a vacuum degree of 1MPa to remove unreacted methanol, residual water and a small amount of light impurities to obtain a high-purity fatty acid methyl ester fraction. A composite adsorbent with a mass ratio of modified activated clay to nano-activated carbon of 2:1 to 3:1 is used for stirring and adsorption at 55 to 65°C for 40 to 60 minutes. The porous structure and surface activity of the adsorbent are used to deeply remove the odor, pigments, trace metal ions and residual impurities of the mixed oil, and improve the color and stability of the oil. The mixed oil after adsorption and refinement is introduced into a plasma treatment device and treated at a power of 200 to 400 watts for 15 to 25 minutes in an argon or helium atmosphere. The high-energy active particles in the low-temperature plasma jet react with the residual harmful organic matter, microorganisms and long-chain polymers in the mixed oil to decompose harmful substances, activate the surface of oil molecules, and enhance the interaction with other additives. Capacitance, followed by supercritical fluid extraction and refining. At a specific temperature and pressure, supercritical carbon dioxide dissolves residual impurities, odor substances and unstable components in the mixed oil, while the solubility of the target oil is low. After extraction, the pressure and temperature are adjusted to allow carbon dioxide to escape, and the mixed oil is further purified. Finally, a certain amount of nano-titanium dioxide is evenly dispersed in the mixed oil and treated at an ultrasonic frequency of 30 to 50 kHz for 20 to 30 minutes. Nano-titanium dioxide uses its photocatalytic and antioxidant properties to inhibit the oxidation and deterioration of the mixed oil, and the nano-size effect improves the lubrication and rheological properties. Then, it is mixed with other additives such as antioxidants such as vitamin E, with an addition amount of 0.03% to 0.08%, and lubricants such as zinc dialkyl dithiophosphate, with an addition amount of 0.1% to 0.3%, according to a specific ratio, to optimize the performance to meet the needs of different industrial applications. .

[0086] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing industrial-grade mixed oil produced by using waste cooking oil, characterized in that: The specific steps are as follows: S1: Collection: Collect the portion containing waste oil from the food waste, use special food waste collection equipment, and collect the waste and grease together into a storage container. S2: Solid-liquid separation of garbage: Use screen filtration to separate solid garbage and liquid garbage; S3: Cleaning and collection of grease on the garbage surface: After that, the solid garbage is placed in the cleaning pool, and the grease on the garbage surface is washed with clean water. After the washing is completed, the large-volume impurities are intercepted again by sieve filtration. The cleaning water containing grease can be pumped to the sedimentation tank through a water pump to let it settle naturally. Since the density of grease is smaller than that of water, it will gradually float to the liquid surface, while the solid particles will settle to the bottom of the pool. The sedimentation time is 1 to 5 hours to ensure that the solid and grease have enough time to separate; S4: Mechanical separation: After the grease in S3 is separated, the grease on the surface of the garbage and the liquid containing grease initially filtered out by S1 can be transported to the centrifuge for mechanical separation; S5: Chemical cleaning: The grease and a small amount of residual solids after preliminary separation are placed in a cleaning tank with an agitator and temperature control, so that the acidic impurities in the grease and the grease attached to the solids can be cleaned off; S6: Water washing: The grease and solid mixture after washing is then rinsed with clean water, and the water washing is repeated several times until the pH value of the rinsed water is close to 7; S7: Acid treatment: The washed solid mixture is then transported to a solution containing an appropriate amount of 0.5% to 1% dilute sulfuric acid, stirred at 50 to 60°C for 10 to 15 minutes, and then filtered to remove the decomposition products; S8: Dehydration: Remove moisture from the oil at 80-100°C and a reduced vacuum degree of 0.08-0.09MPa to reduce the moisture content to below 0.5%; S9: Degumming: Add phosphoric acid to the dehydrated waste oil in an amount of 0.1% to 0.3% of the oil mass, stir at 60 to 70°C for 10 to 20 minutes at a speed of 80 to 100 rpm to precipitate phospholipids and other colloids in the oil, and filter to remove the colloids. S10: Metal ion removal: Add 0.1% to 0.2% ethylenediaminetetraacetic acid solution and stir for 10 to 15 minutes to remove metal ions in the waste oil; S11: Ultrasonic-assisted transesterification: Put the waste oil after enzymatic hydrolysis optimization into the reactor, add methanol oil and methanol in a molar ratio of 1:6-1:8 and sodium hydroxide in an amount of 0.5%-1% of the oil mass. React at 60-70°C, stir at 120-150 rpm, and during the reaction, ultrasonically treat for 2-3 minutes every 5-10 minutes at an ultrasonic frequency of 20-40kHz; S12: Multi-stage transesterification: Multi-stage transesterification is used. After the first-stage reaction, part of the product is separated and the remaining reactants are added with new methanol and catalyst to carry out the next-stage reaction. S13: membrane separation: after all reactions are completed, in addition to static stratification, glycerol and fatty acid methyl esters are further separated according to their molecular sizes and properties using a hydrophilic-hydrophobic separation membrane, with the lower layer being glycerol and the upper layer being fatty acid methyl esters; S14: vacuum distillation: placing the fatty acid methyl ester in a vacuum distillation apparatus to remove unreacted methanol, residual water and a small amount of light impurities to obtain a high-purity fatty acid methyl ester fraction; S15: Adsorption refining: Use a composite adsorbent of modified activated clay and nano-activated carbon to deeply remove odor, pigments, trace metal ions and remaining impurities in the mixed oil, and improve the color and stability of the oil; S16: Plasma treatment: The adsorbed refined mixed oil is introduced into the plasma treatment device. In an argon or helium atmosphere, a low-temperature plasma jet with a power of 200 to 400 watts is used for a treatment time of 15 to 25 minutes to contact the mixed oil. With the help of high-energy active particles, residual harmful organic matter, microorganisms and long-chain polymers are decomposed, the surface of oil molecules is activated, and the compatibility with other additives is enhanced, further improving the quality and safety of the mixed oil. S17: Supercritical fluid extraction and refining: After adsorption refining to remove odor, pigments and trace impurities, and plasma treatment to decompose residual harmful organic matter, supercritical fluid extraction and refining are carried out; S18: Addition of nanoparticles: A certain amount of nano-titanium dioxide with a particle size of 20 to 50 nm and an addition amount of 0.05% to 0.15% of the oil mass is uniformly dispersed in the industrial-grade mixed oil, and treated under ultrasonic conditions with an ultrasonic frequency of 30 to 50 kHz and an ultrasonic time of 20 to 30 minutes to allow the nanoparticles to be fully dispersed and interact with the oil molecules. Nano-titanium dioxide has good photocatalytic and antioxidant properties, and can inhibit the oxidation and deterioration of the mixed oil during storage and use to a certain extent. At the same time, its nano-size effect can improve the lubrication and rheological properties of the mixed oil, making it more suitable for some industrial fields that have high requirements on oil performance, such as high-end mechanical lubrication, special chemical synthesis, etc. S19: Post-processing and blending: After extraction and refining, the industrial-grade mixed oil modified with nanomaterials can be mixed with other additives such as antioxidants, lubricants, etc. in a specific proportion to further optimize its performance to meet the needs of different industrial applications.

2. The industrial-grade mixed oil produced from waste cooking oil according to claim 1, characterized in that: The S4 is passed through a centrifugal separator at 1000-3000 rpm for 5-10 minutes, so that the solid particles are precipitated at the bottom and the grease is separated from the upper layer.

3. The industrial-grade mixed oil produced from waste cooking oil according to claim 1, characterized in that : S5 adds 1% to 3% sodium hydroxide solution to the cleaning tank, and stirs at 40 to 60° C. at a speed of 50 to 100 rpm for 10 to 30 minutes.

4. An industrial grade mixed oil produced from waste cooking oil according to claim 1, characterized in that The S14 is distilled in a reduced pressure distillation apparatus at 160-180° C. and a vacuum degree of 0.09-0.1 MPa for 30-40 min.

5. An industrial grade mixed oil produced from waste cooking oil according to claim 1, characterized in that The mass ratio of the composite adsorbent of S15 modified activated clay and nano activated carbon is 2:1 to 3:1, and the adsorption is stirred at 55 to 65°C for 40 to 60 minutes.

6. The industrial-grade mixed oil produced from waste cooking oil according to claim 1, characterized in that The S19 adds an appropriate amount of antioxidants such as vitamin E in an amount of 0.03% to 0.08% of the oil mass to the industrial-grade mixed oil modified by the nanomaterial to enhance its antioxidant capacity, or adds a specific extreme pressure anti-wear agent such as zinc dialkyl dithiophosphate in an amount of 0.1% to 0.3% of the oil mass to improve its lubrication performance.

7. An industrial-grade mixed oil produced from waste cooking oil, characterized in that: The industrial-grade mixed oil is prepared by the method described in any one of claims 1 to 6.

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