Advanced treatment system and method for swill oil subjected to low-temperature hydrothermal treatment
Through system optimization of multi-stage filtration, low-temperature hydrothermal treatment, and transesterification reaction, combined with UASB anaerobic reactor and double-effect MVR evaporator, the problems of low impurity removal rate, high energy consumption, and low conversion rate in swill oil treatment have been solved, achieving efficient resource utilization and wastewater treatment.
Patent Information
- Application Number
- CN202511347552.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-19
- Publication Date
- 2025-12-02
AI Technical Summary
Existing technologies for treating swill oil suffer from problems such as low impurity removal rate, high energy consumption, unsatisfactory dehydration effect, excessive VOC emissions, low ester exchange conversion rate, insufficient methanol recovery rate, and substandard wastewater treatment, resulting in low resource utilization efficiency.
The entire process of resource utilization is achieved by using a coupled treatment of multi-stage filtration, low-temperature hydrothermal treatment, alkaline catalysis and ultrasound-assisted transesterification reaction, methanol flash evaporation, UASB anaerobic reactor and double-effect MVR evaporator.
It improves the resource utilization rate of swill oil, reduces energy consumption and treatment costs, increases the transesterification conversion rate, reduces VOC emissions, and achieves harmless treatment of wastewater.
Smart Images
Figure CN121046147A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of resource utilization technology of kitchen waste, specifically to a deep treatment system and method for swill oil after low-temperature hydrothermal treatment. Background Technology
[0002] With the booming development of the catering industry, the problem of waste cooking oil (commonly known as swill oil) is becoming increasingly prominent. Currently, the processing technologies commonly used in the industry have many technical bottlenecks, which seriously restrict the resource utilization efficiency of swill oil.
[0003] In the pretreatment stage, existing technologies face three main challenges: First, traditional filtration processes often employ a single-screen filtration method, achieving an impurity removal rate of less than 80% and failing to effectively separate colloidal components; second, dehydration processes consume high energy, generally exceeding 120 kWh / ton of oil, yet the dehydration effect is unsatisfactory, with residual moisture still exceeding 2% after treatment; third, existing technologies lack effective deodorization measures, resulting in severe VOC emissions exceeding standards during treatment, with measured concentrations generally exceeding 50 mg / m³. 3 .
[0004] In the conversion stage, existing transesterification processes have significant technical shortcomings. Currently, the mainstream single-stage reaction systems have low conversion efficiency, achieving only 82%-85%. To improve reaction efficiency, excessive catalyst usage (NaOH dosage > 1.5%) is often required, which not only increases processing costs but also introduces challenges for subsequent treatment. More importantly, existing processes generally have reaction times exceeding 4 hours, and methanol recovery rates are less than 90%, resulting in severe resource waste and poor economic returns.
[0005] The problems in wastewater treatment are particularly prominent. The high-concentration organic wastewater (COD > 8000 mg / L) generated from swill and oil treatment poses a significant challenge to traditional biological treatment processes. When using conventional A / O processes, the COD removal rate fluctuates greatly, only reaching 60%-70%, far below current emission standards. If evaporation processes are used, the steam consumption is as high as 0.8 tons per ton of water, making the operating costs prohibitively high.
[0006] From the perspective of resource utilization, existing technologies have significant shortcomings. First, the purity of the byproduct glycerol is generally below 90%, making it difficult to use directly as a chemical raw material. Second, the process water reuse rate is less than 30%, resulting in a serious waste of water resources. Furthermore, existing technical solutions often focus only on optimizing a single step, lacking a systematic, end-to-end design. Although traditional processes employ improved two-stage ester exchange processes, they still fail to solve key problems such as easy clogging of the filtration system (requiring shutdown for cleaning every 8 hours) and substandard wastewater treatment. Summary of the Invention
[0007] To address existing problems, this invention aims to provide a deep treatment system and method for swill oil after low-temperature hydrothermal treatment. Through an integrated, efficient pretreatment, deep conversion, and wastewater reuse technology, it reduces consumption and increases efficiency, improves the conversion rate of the transesterification process, and achieves system optimization of material flow and energy utilization at low cost.
[0008] To achieve the above objectives, the present invention provides the following technical solution.
[0009] This invention provides a deep treatment system for swill oil after low-temperature hydrothermal treatment, comprising a pretreatment unit, a transesterification reaction unit, a methanol recovery unit, a product separation unit, and a wastewater treatment unit. The pretreatment unit contains swill and is used for multi-stage filtration of swill. The inlet of the transesterification reaction unit is connected to the outlet of the pretreatment unit. The inlet of the methanol recovery unit is connected to the outlet of the transesterification reaction unit. The product separation unit is connected to the transesterification reaction unit. The wastewater treatment unit is connected to the pretreatment unit. The wastewater treatment unit includes a UASB upflow anaerobic reactor, a regulating water tank, a liquid fertilizer storage tank, a double-effect MVR evaporator, and a water storage tank. The double-effect MVR evaporator is connected to the UASB upflow anaerobic reactor through the liquid fertilizer storage tank.
[0010] As a further improvement of the present invention, the pretreatment unit includes a swill oil storage tank, an evaporator, a vibrating screen coarse filter device, a vibrating screen fine filter device, and a multi-stage fine filter device connected in sequence; the screen aperture of the vibrating screen coarse filter device is 100 mesh, the screen aperture of the vibrating screen fine filter device is 200 mesh, and the filtration accuracy of the multi-stage fine filter device is 0.1-1.0 μm.
[0011] As a further improvement of the present invention, the evaporator includes a vacuum dehydration device; the working pressure of the vacuum tube dehydration device is -0.06 to -0.1 MPa, and its working dehydration temperature is 80-95°C.
[0012] As a further improvement of the present invention, the transesterification reaction unit includes a primary reactor, a separator, a secondary reactor, and a separator. The primary reactor and the secondary reactor are used for alkaline-catalyzed and ultrasonically assisted transesterification reactions, respectively. The catalyst used in the primary reactor is NaOH or KOH, and the amount used is 0.5-1.5% of the mass of swill.
[0013] As a further improvement of the present invention, the secondary reactor is equipped with an ultrasonic generator with an ultrasonic frequency of 20-60kHz and a power density of 30-80W / L.
[0014] As a further improvement of the present invention, the methanol recovery unit includes a methanol flash tank and a methanol collection tank.
[0015] As a further improvement of the present invention, the operating pressure of the methanol flash tank is 0.1-0.5 MPa and the operating temperature is 60-90℃.
[0016] As a further improvement of the present invention, the upflow velocity of the UASB upflow anaerobic reactor is 0.5-1.5 m / h, and the reaction temperature is 30-40℃.
[0017] As a further improvement of the present invention, the double-effect MVR evaporator includes a first-effect evaporator and a second-effect evaporator; the operating pressure of the first-effect evaporator is 0.4-0.8 MPa and the operating temperature is 80-100℃; the operating pressure of the second-effect evaporator is 0.2-0.5 MPa and the operating temperature is 60-80℃.
[0018] This invention also provides a method for deep treatment of swill oil after low-temperature hydrothermal treatment. The swill is vacuum dehydrated, and the dehydrated water is coupled through a double-effect MVR generator and a UASB upflow anaerobic reactor. The residue after swill dehydration is filtered in multiple stages. The dehydrated and filtered products are subjected to transesterification under alkaline catalysis and ultrasonic assistance. The transesterified products are then subjected to methanol flash evaporation, and the heat released by flash evaporation can be used to preheat the vacuum dehydration or transesterification reaction.
[0019] The present invention has the following beneficial effects: This system integrates the entire process of swill oil recycling. Through the synergy of unit pretreatment, ester exchange, methanol recovery, product separation and wastewater treatment units, it realizes the resource utilization of swill oil and the harmless treatment of wastewater, improving the overall efficiency of the system. The wastewater treatment unit, through the coupling of UASB anaerobic reactor and double-effect MVR evaporator, converts wastewater into biogas and concentrate, reducing secondary pollution.
[0020] Preferably, the pretreatment unit employs a three-stage filtration method using 100-mesh and 200-mesh vibrating screens and 0.1-1.0μm fine filter screens to remove large particulate impurities, fibers, and suspended solids from the swill step by step, ensuring the purity of the raw materials for subsequent reactions; at the same time, multi-stage filtration can prevent clogging of subsequent equipment.
[0021] Preferably, the dehydration is carried out under a pressure of -0.06 to -0.1 MPa and at 80-95°C to avoid high-temperature decomposition of oils and improve oil yield; at the same time, low temperature and reduced pressure are maintained to reduce the degradation of heat-sensitive components and reduce energy consumption.
[0022] Preferably, the primary reactor uses NaOH / KOH at a concentration of 0.5-1.5% for catalysis, which can promote the hydrolysis of triglycerides.
[0023] Preferably, the secondary reactor uses ultrasound, which can enhance mass transfer and interfacial activity, and accelerate the methyl esterification reaction; at the same time, ultrasound assistance shortens the reaction time and reduces the amount of catalyst used.
[0024] Preferably, the methanol flash tank separates unreacted methanol through pressure difference, thereby improving the methanol recovery rate and reducing raw material costs.
[0025] Prior to this, methanol flash tanks using 0.1-0.5 MPa and 60-90℃ can achieve a methanol recovery rate of over 95% and significantly reduce raw material costs.
[0026] Preferably, the operating parameters of the UASB are set as follows: upflow velocity 0.5-1.5 m / h, 30-40℃, and COD volumetric loading 5-15 kg / (m³). 3 ·d) enables the UASB to process the water removed from the swill at a high load, thereby achieving efficient degradation of organic matter and reducing the proportion of fertilizer water; at the same time, the biogas produced can be reused as a heat source for the system, reducing dependence on purchased energy.
[0027] Preferably, the single-effect MVR evaporator achieves high-pressure steam-driven evaporation, and the condensate is refluxed to preheat the feed. The second effect utilizes the secondary steam from the first effect to reduce energy consumption. Compared with the single-effect MVR evaporator, the double-effect MVR evaporator saves more than 50% of steam. The concentrated liquid after evaporation contains nitrogen and phosphorus and can be stored as liquid fertilizer.
[0028] The deep processing method of this invention dehydrates under mild conditions of 80-95℃, protecting the structure of the oil and avoiding quality degradation caused by high-temperature cracking; the dual-stage reaction of alkali catalysis and ultrasound balances reaction rate and selectivity, improving the purity of the biodiesel product; simultaneous treatment of wastewater and solid waste is beneficial for system thermal integration and reduces total energy consumption. Attached Figure Description
[0029] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and are not intended to specifically limit the shapes and proportions of the components. In the drawings: Figure 1 This is a schematic diagram of a deep treatment system for swill oil after low-temperature hydrothermal treatment in Example 1; Figure 2 This is a step diagram of a deep treatment method for swill oil after low-temperature hydrothermal treatment in Example 1.
[0030] The components include: 1. Swill oil storage tank; 2. First pretreatment transfer pump; 3. Evaporator; 4. Oil storage tank; 5. Second pretreatment transfer pump; 6. Vibrating screen coarse filtration device; 7. Third pretreatment transfer pump; 8. Vibrating screen fine filtration device; 9. Fourth pretreatment transfer pump; 10. Multi-stage fine screen filtration device; 11. Ester exchange transfer pump; 12. Primary reactor; 13. Primary separator; 14. Secondary reactor; 15. Secondary separator; 16. Methanol flash tank; 17. Methanol collection tank; 18. Finished diesel tank; 19. Glycerin storage tank; 20. UASB upflow anaerobic reactor; 21. Second wastewater treatment transfer pump; 22. Adjustment water tank; 23. Liquid fertilizer storage tank; 24. Dual-effect MVR generator; 25. First wastewater treatment transfer pump; 26. Water storage tank. Detailed Implementation
[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.
[0032] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0034] Example 1 like Figure 1As shown, this embodiment provides a deep treatment system for swill oil after low-temperature hydrothermal treatment, including a pretreatment unit, a transesterification reaction unit, a methanol recovery unit, a product separation unit, and a wastewater treatment unit; the pretreatment unit contains swill and is used for multi-stage filtration of swill; the inlet of the transesterification reaction unit is connected to the outlet of the pretreatment unit; the inlet of the methanol recovery unit is connected to the outlet of the transesterification reaction unit; the product separation unit is connected to the transesterification reaction unit; and the wastewater treatment unit is connected to the pretreatment unit.
[0035] The wastewater treatment unit includes a UASB upflow anaerobic reactor 20, a regulating water tank 22, a liquid fertilizer storage tank 23, a double-effect MVR evaporator 3, and a water storage tank 26; the double-effect MVR evaporator 3 is connected to the UASB upflow anaerobic reactor unit through the liquid fertilizer storage tank 23.
[0036] Specifically, such as Figure 1 As shown, the inlet of the water storage tank 26 collects the evaporation products from the evaporator 3, and the outlet of the water storage tank 26 is connected to the inlet of the first wastewater treatment transfer pump 25. The outlet of the first wastewater treatment transfer pump 25 is connected to the inlet of the double-effect MVR generator 24. The outlet of the double-effect MVR generator 24 is connected to the inlet of the liquid fertilizer storage tank 23 and the inlet of the regulating water tank 22, respectively. The outlet of the regulating water tank 22 is connected to the inlet of the second wastewater treatment transfer pump 21. The outlet of the second wastewater treatment transfer pump 21 is connected to the UASB upflow anaerobic reactor 20. The double-effect MVR generator 24 uses mechanical vapor recompression technology to compress and heat secondary steam and then recycle it as a heat source, significantly reducing dependence on external steam. The outlet of the dual-effect MVR generator 24 is diverted to the liquid fertilizer storage tank 23, which can concentrate and recover inorganic salts and organic matter in high-salt wastewater and convert them into usable resources such as liquid fertilizer, realizing waste resource utilization and reducing treatment costs; at the same time, the system removes complex wastewater with high salt and high COD, which can extend the equipment life and reduce downtime maintenance.
[0037] The pretreatment unit includes a swill oil storage tank 1, an evaporator 3, a vibrating screen coarse filter device 6, a vibrating screen fine filter device 8, and a multi-stage fine filter device 10 connected in sequence; the vibrating screen coarse filter device 6 has a screen aperture of 100 mesh, the vibrating screen fine filter device 8 has a screen aperture of 200 mesh, and the multi-stage fine filter device 10 has a filtration accuracy of 0.1 μm.
[0038] Specifically, such as Figure 1As shown, the swill oil storage tank 1 is connected to the inlet of the evaporator 3 via the first pretreatment conveying pump 2, and the outlet of the evaporator 3 is connected to the oil storage tank 4; the outlet of the oil storage tank 4 is connected to the inlet of the vibrating screen coarse filter device 6 via the second pretreatment conveying pump 5, and the outlet of the vibrating screen coarse filter device 6 is connected to the inlet of the vibrating screen fine filter device 8 via the third pretreatment conveying pump 7; the outlet of the vibrating screen fine filter device 8 is connected to the inlet of the multi-stage fine filter device 10 via the fourth pretreatment conveying pump 9.
[0039] The evaporator 3 includes a vacuum dehydration device; the working pressure of the vacuum tube dehydration device is -0.06 MPa, and its working dehydration temperature is 80°C. Gentle dehydration at 80°C avoids high-temperature decomposition of oils and increases oil yield; simultaneously, maintaining low temperature and reduced pressure reduces the degradation of heat-sensitive components and lowers energy consumption.
[0040] The transesterification reaction unit includes a primary reactor 12, a primary separator 13, a secondary reactor 14, and a secondary separator 15. The primary reactor 12 and the secondary reactor 14 are used for alkaline-catalyzed and ultrasonically assisted transesterification reactions, respectively. The catalyst used in the primary reactor 12 is NaOH, and the amount used is 0.5% of the mass of the swill.
[0041] Specifically, such as Figure 1 As shown, the inlet of the primary reactor 12 is connected to the ester exchange transfer pump 11, which is also connected to the outlet of the multi-stage fine screen filter device 10. The outlet of the primary reactor 12 is connected to the inlet of the primary separator 13, the outlet of the primary separator 13 is connected to the inlet of the secondary reactor 14, and the outlet of the secondary reactor 14 is connected to the inlet of the secondary separator 15. The primary separator 13 and the secondary separator 15 are both connected to the glycerol storage tank 19.
[0042] The secondary reactor 14 is equipped with an ultrasonic generator with an ultrasonic frequency of 20 kHz and a power density of 30 W / L. The use of ultrasound in the secondary reactor 14 enhances mass transfer and interfacial activity, accelerating the methyl esterification reaction; simultaneously, ultrasound-assisted reaction shortens the reaction time and reduces the amount of catalyst required.
[0043] The methanol recovery unit includes a methanol flash tank 16 and a methanol collection tank 17. The methanol flash tank 16 separates unreacted methanol through pressure difference, thereby improving the methanol recovery rate and reducing raw material costs.
[0044] The methanol flash evaporator 16 operates at a pressure of 0.1 MPa and a temperature of 60°C.
[0045] Specifically, such as Figure 1As shown, the inlet of the methanol flash tank 16 is connected to the outlet of the secondary separator 15, and the steam port of the methanol flash tank 16 is connected to the methanol collection tank 17. The outlet of the methanol flash tank 16 is connected to the inlet of the finished diesel fuel tank 18.
[0046] The upflow velocity of the UASB upflow anaerobic reactor 20 is 0.5 m / h, and the reaction temperature is 30℃.
[0047] The dual-effect MVR evaporator 3 includes a first-effect evaporator and a second-effect evaporator; the first-effect evaporator operates at a pressure of 0.4 MPa and a temperature of 80°C; the second-effect evaporator operates at a pressure of 0.2 MPa and a temperature of 60°C.
[0048] This embodiment also discloses a method for deep treatment of swill oil after low-temperature hydrothermal treatment, including the following steps: The swill is vacuum dewatered, and the dewatered water is then coupled through a double-effect MVR generator 24 and a UASB upflow anaerobic reactor 20 for further processing. The residue after dewatering the swill undergoes multi-stage filtration; The dehydrated and filtered product was subjected to transesterification under alkaline catalysis and ultrasonic assistance conditions. The transesterified product was then subjected to methanol flash evaporation, and the heat released by the flash evaporation could be used to preheat the vacuum dehydration or transesterification reaction.
[0049] The deep processing method in this embodiment protects the structure of the oil and avoids quality degradation caused by high-temperature cracking; the two-stage reaction of alkali catalysis and ultrasound takes into account both reaction rate and selectivity, improving the purity of the biodiesel product; the simultaneous treatment of wastewater and solid waste is conducive to system thermal integration and reduces total energy consumption.
[0050] Example 2 This embodiment provides a deep treatment system for swill oil after low-temperature hydrothermal treatment, including a pretreatment unit, a transesterification reaction unit, a methanol recovery unit, a product separation unit, and a wastewater treatment unit. The pretreatment unit contains swill and is used for multi-stage filtration of swill. The inlet of the transesterification reaction unit is connected to the outlet of the pretreatment unit. The inlet of the methanol recovery unit is connected to the outlet of the transesterification reaction unit. The product separation unit is connected to the transesterification reaction unit. The wastewater treatment unit is connected to the pretreatment unit. The wastewater treatment unit includes a UASB upflow anaerobic reactor 20, a regulating water tank 22, a liquid fertilizer storage tank 23, a double-effect MVR evaporator 3, and a water storage tank 26. The double-effect MVR evaporator 3 is connected to the UASB upflow anaerobic reactor unit through the liquid fertilizer storage tank 23.
[0051] The pretreatment unit comprises a swill oil storage tank 1, an evaporator 3, a vibrating screen coarse filter 6, a vibrating screen fine filter 8, and a multi-stage fine filter 10 connected in sequence. The vibrating screen coarse filter 6 has a screen aperture of 100 mesh, the vibrating screen fine filter 8 has a screen aperture of 200 mesh, and the multi-stage fine filter 10 has a filtration accuracy of 1.0 μm. Multi-stage filtration is used to separate the solid and liquid components of the swill, combined with an acidification and settling separation process (the upper oil layer needs to be acid-cooked and carbonized to remove impurities after extraction), providing high-purity raw materials for subsequent reactions.
[0052] The evaporator 3 includes a vacuum dehydration device; the working pressure of the vacuum tube dehydration device is -0.1MPa, and its working dehydration temperature is 95℃.
[0053] The transesterification reaction unit includes a primary reactor 12, a primary separator 13, a secondary reactor 14, and a secondary separator 15. The primary reactor 12 and the secondary reactor 14 are used for alkaline-catalyzed and ultrasound-assisted transesterification reactions, respectively. The catalyst used in the primary reactor 12 is KOH, at a dosage of 1.5% of the swill mass. The transesterification reaction unit converts pretreated oils into biodiesel, optimizing reaction efficiency compared to existing processes using enzyme-catalyzed transesterification or mesoporous molecular sieve immobilized enzyme technology.
[0054] The secondary reactor 14 is equipped with an ultrasonic generator with an ultrasonic frequency of 60 kHz and a power density of 80 W / L.
[0055] The methanol recovery unit includes a methanol flash tank 16 and a methanol collection tank 17. The methanol collection tank 17 is connected to the primary reactor 12 and the secondary reactor 14 via two methanol tank evaporation circuits. These circuits return the volatile products from the methanol collection tank 17 to the primary reactor 12 and the secondary reactor 14 for recycling and separation, thereby improving the purity of the products in the methanol collection tank 17. The methanol recovery unit achieves solvent recycling, reducing production costs.
[0056] The methanol flash evaporator 16 operates at a pressure of 0.5 MPa and a temperature of 90°C.
[0057] The upflow velocity of the UASB upflow anaerobic reactor 20 is 1.5 m / h, and the reaction temperature is 40℃. The UASB anaerobic reactor utilizes microorganisms to degrade organic matter. The 1.5 m / h velocity and 40℃ allow the UASB to process the water removed from the swill at a high load, achieving efficient degradation of organic matter and reducing the proportion of fertilizer in the swill. Simultaneously, the biogas produced can be reused as a system heat source, reducing reliance on purchased energy.
[0058] The double-effect MVR evaporator 3 includes a first-effect evaporator and a second-effect evaporator; the first-effect evaporator operates at a pressure of 0.8 MPa and a temperature of 100°C; the second-effect evaporator operates at a pressure of 0.5 MPa and a temperature of 80°C. The double-effect MVR evaporator 3 achieves high energy-to-weight ratio concentration through mechanical vapor recompression.
[0059] Example 3 This embodiment provides a deep treatment system for swill oil after low-temperature hydrothermal treatment, including a pretreatment unit, a transesterification reaction unit, a methanol recovery unit, a product separation unit, and a wastewater treatment unit. The pretreatment unit contains swill and is used for multi-stage filtration of swill. The inlet of the transesterification reaction unit is connected to the outlet of the pretreatment unit. The inlet of the methanol recovery unit is connected to the outlet of the transesterification reaction unit. The product separation unit is connected to the transesterification reaction unit. The wastewater treatment unit is connected to the pretreatment unit. The wastewater treatment unit includes a UASB upflow anaerobic reactor 20, a regulating water tank 22, a liquid fertilizer storage tank 23, a double-effect MVR evaporator 3, and a water storage tank 26. The double-effect MVR evaporator 3 is connected to the UASB upflow anaerobic reactor unit through the liquid fertilizer storage tank 23.
[0060] The pretreatment unit comprises a swill oil storage tank 1, an evaporator 3, a vibrating screen coarse filter 6, a vibrating screen fine filter 8, and a multi-stage fine filter 10 connected in sequence. The vibrating screen coarse filter 6 has a screen aperture of 100 mesh, the vibrating screen fine filter 8 has a screen aperture of 200 mesh, and the multi-stage fine filter 10 has a filtration accuracy of 0.5 μm. Multi-stage filtration is used to separate the solid and liquid components of the swill, combined with an acidification and settling separation process (the upper oil layer needs to be acid-cooked and carbonized to remove impurities after extraction), providing high-purity raw materials for subsequent reactions.
[0061] The evaporator 3 includes a vacuum dehydration device; the working pressure of the vacuum tube dehydration device is -0.08MPa, and its working dehydration temperature is 90℃.
[0062] The transesterification reaction unit includes a primary reactor 12, a primary separator 13, a secondary reactor 14, and a secondary separator 15. The primary reactor 12 and the secondary reactor 14 are used for alkali-catalyzed and ultrasound-assisted transesterification reactions, respectively. The catalyst used in the primary reactor 12 is a magnetic solid alkali, such as CaO@Fe3O4. The transesterification reaction unit converts pretreated oils into biodiesel, optimizing reaction efficiency compared to existing processes involving enzyme-catalyzed transesterification or mesoporous molecular sieve-immobilized enzyme technology.
[0063] The secondary reactor 14 is equipped with an ultrasonic generator with an ultrasonic frequency of 40kHz and a power density of 50W / L.
[0064] The methanol recovery unit includes a methanol flash tank 16 and a methanol collection tank 17. The methanol collection tank 17 is connected to the primary reactor 12 and the secondary reactor 14 via two methanol tank evaporation circuits. These circuits return the volatile products from the methanol collection tank 17 to the primary reactor 12 and the secondary reactor 14 for recycling and separation, thereby improving the purity of the products in the methanol collection tank 17. The methanol recovery unit achieves solvent recycling, reducing production costs.
[0065] The methanol flash evaporator 16 operates at a pressure of 0.3 MPa and a temperature of 80°C.
[0066] The upflow velocity of the UASB upflow anaerobic reactor 20 is 1.0 m / h, and the reaction temperature is 35℃. The UASB anaerobic reactor is used to degrade organic matter through microorganisms.
[0067] The double-effect MVR evaporator 3 includes a first-effect evaporator and a second-effect evaporator; the first-effect evaporator operates at a pressure of 0.6 MPa and a temperature of 90°C; the second-effect evaporator operates at a pressure of 0.3 MPa and a temperature of 70°C. The double-effect MVR evaporator 3 achieves high energy-to-weight ratio concentration through mechanical vapor recompression.
[0068] like Figure 2 As shown in the figure, this embodiment also discloses a method for deep treatment of swill oil after low-temperature hydrothermal treatment, including the following steps: The swill is vacuum dewatered, and the dewatered water is then coupled through a double-effect MVR generator 24 and a UASB upflow anaerobic reactor 20 for further processing. The residue after dewatering the swill undergoes multi-stage filtration; The dehydrated and filtered product was subjected to transesterification under alkaline catalysis and ultrasonic assistance conditions; the transesterified product was then subjected to methanol flash distillation.
[0069] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.
Claims
1. A deep treatment system for swill oil after low-temperature hydrothermal treatment, characterized in that, The system includes a pretreatment unit, a transesterification reaction unit, a methanol recovery unit, a product separation unit, and a wastewater treatment unit. The pretreatment unit contains swill and is used for multi-stage swill filtration. The inlet of the transesterification reaction unit is connected to the outlet of the pretreatment unit. The inlet of the methanol recovery unit is connected to the outlet of the transesterification reaction unit. The product separation unit is connected to the transesterification reaction unit. The wastewater treatment unit is connected to the pretreatment unit. The wastewater treatment unit includes a UASB upflow anaerobic reactor, a regulating water tank, a liquid fertilizer storage tank, a double-effect MVR evaporator, and a water storage tank. The double-effect MVR evaporator is connected to the UASB upflow anaerobic reactor through the liquid fertilizer storage tank.
2. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 1, characterized in that, The pretreatment unit includes a swill oil storage tank, an evaporator, a vibrating screen coarse filter, a vibrating screen fine filter, and a multi-stage fine filter connected in sequence; the vibrating screen coarse filter has a screen aperture of 100 mesh, the vibrating screen fine filter has a screen aperture of 200 mesh, and the multi-stage fine filter has a filtration accuracy of 0.1-1.0 μm.
3. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 2, characterized in that, The evaporator includes a vacuum dehydration device; the working pressure of the vacuum tube dehydration device is -0.06 to -0.1 MPa, and its working dehydration temperature is 80-95℃.
4. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 1, characterized in that, The transesterification reaction unit includes a primary reactor, a primary separator, a secondary reactor, and a secondary separator. The primary reactor and the secondary reactor are used for alkaline-catalyzed and ultrasonically assisted transesterification reactions, respectively. The catalyst used in the primary reactor is NaOH or KOH, and the amount used is 0.5-1.5% of the swill mass.
5. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 4, characterized in that, The secondary reactor is equipped with an ultrasonic generator with an ultrasonic frequency of 20-60kHz and a power density of 30-80W / L.
6. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 1, characterized in that, The methanol recovery unit includes a methanol flash tank and a methanol collection tank.
7. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 6, characterized in that, The methanol flash evaporator operates at a pressure of 0.1-0.5 MPa and a temperature of 60-90℃.
8. The deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 1, characterized in that, The upflow velocity of the UASB upflow anaerobic reactor is 0.5-1.5 m / h, and the reaction temperature is 30-40℃.
9. A deep treatment system for swill oil after low-temperature hydrothermal treatment according to claim 1, characterized in that, The dual-effect MVR evaporator includes a first-effect evaporator and a second-effect evaporator; the operating pressure of the first-effect evaporator is 0.4-0.8 MPa and the operating temperature is 80-100℃; the operating pressure of the second-effect evaporator is 0.2-0.5 MPa and the operating temperature is 60-80℃.
10. A method for deep treatment of swill oil after low-temperature hydrothermal treatment as described in any one of claims 1-9, characterized in that, Includes the following steps: The swill is vacuum dewatered, and the dewatered water is then coupled through a double-effect MVR generator and a UASB upflow anaerobic reactor for further processing. The residue after dewatering the swill undergoes multi-stage filtration; The dehydrated and filtered product was subjected to transesterification under alkaline catalysis and ultrasonic assistance conditions. The transesterified product was then subjected to methanol flash evaporation, and the heat released by the flash evaporation could be used to preheat the vacuum dehydration or transesterification reaction.