A production method, system and device for enriching polyunsaturated fatty acids

Abstract

The present invention relates to the technical field of oil processing, in particular to a production method, system and device for enriching polyunsaturated fatty acids, comprising: adding oil and auxiliary materials to a crystallization tank, cooling and stirring to form crystals through gradient, and obtaining a suspension; performing membrane filtration on the obtained suspension to obtain a concentrate and a filtrate; further cooling, stirring and filtering the obtained filtrate to obtain the expected product enriched in polyunsaturated fatty acids. The present invention provides a cold zone jacket for the membrane filtration equipment without setting up a cold storage, and the crystallization freezing liquid circulates through the jacket to ensure that the crystallization temperature is consistent with the cooling temperature, thereby saving the investment cost of building a cold storage. In actual operation, the filtration environment temperature is only limited to the inside of the membrane filter pipeline, which saves energy and reduces consumption, and has precise temperature control and saves operating costs. Personnel operation does not need to enter the cold storage, which optimizes the working environment. The membrane filtration equipment occupies a small area, has a large space utilization rate, and has low later maintenance and replacement costs.

Description

Technical Field

[0001] The invention relates to the technical field of oil processing, in particular to a production method, system and device for enriching polyunsaturated fatty acids. Background Art

[0002] Polyunsaturated fatty acids such as DHA and EPA have good therapeutic effects in preventing and treating cardiovascular and cerebrovascular diseases, inflammation, inhibiting tumors, and preventing Alzheimer's disease. Many methods have been reported to enrich polyunsaturated fatty acids, mainly including the following: urea inclusion method, low-temperature freezing method, metal salt precipitation method, vacuum distillation method, supercritical extraction method, high-performance liquid chromatography and chromatography method. Among them, low-temperature crystallization fractionation technology has a long history of development. The traditional freezing crystallization fractionation technology aims to strictly control the cooling rate, stirring rate, crystallization and crystal growth time under low-temperature environment, so as to make the crystals large and strong, easy to filter and separate later. However, due to the large number of oil components and complex structure, it is easy to form heterogeneous nucleation and secondary nucleation during the production process, resulting in uneven crystal size and various shapes. The crystals are wrapped with a lot of liquid oil. During the stirring process, due to the continuous increase in viscosity, the system's degree of freedom is weakened, and it is easy to form crystal scale on the wall and other parts, resulting in uneven heat transfer and the formation of undesirable substances such as crystal bundles, which affects the final result of fractionation. In particular, the viscosity of oils and fats increases linearly in a low-temperature environment, resulting in the inability to dissipate the heat of crystallization and uneven supersaturation of the system. Increasing the stirring intensity will cause crystal breakage and secondary nucleation. The crystals have different shapes and sizes, and the particle size range is too wide, which ultimately leads to separation difficulties.

[0003] At present, the main methods for separating crystals are rotary vacuum filters, high-pressure mode filters, plate and frame filter presses, etc. However, these filtering methods have high requirements on the size, shape, and uniformity of crystals on the one hand. On the other hand, the ambient temperature must be consistent with the filtrate temperature during filtration, which places high demands on hardware facilities. Usually, a cold storage is established to meet the temperature requirements. However, for fractionation operations, multi-stage fractionation requires different temperatures, and multiple cold storages with different temperatures need to be established. The investment cost and operating cost are very high. In addition, personnel need to enter the cold storage to replace the filter membrane and repair the machine. For ultra-low temperature fractionation, it is not friendly to operators, and low temperatures have high requirements for equipment materials, electronic components, and instruments. The construction cost and operating cost are very high. The traditional fractionation process is basically intermittent or semi-continuous operation, which requires slow cooling and slow stirring of crystallization and crystal cultivation, and filtering and separation when the crystal grows to a certain extent.

[0004] At present, oil fractionation technology is mainly used in palm oil fractionation, oil dewaxing and winterization, and other primary fractionation of oils at room temperature or slightly low temperature. It is rarely used for the enrichment of polyunsaturated fatty acids at ultra-low temperature. For example, it is rare to enrich polyunsaturated fatty acids in fish oil under ultra-low temperature conditions. At present, the industry lacks process technology for enriching polyunsaturated fatty acids in oils based on ultra-low temperature fractionation technology. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems existing in the prior art, the present invention is proposed.

[0007] Therefore, one of the objects of the present invention is to provide a production method enriched with polyunsaturated fatty acids.

[0008] In order to solve the technical problem, the present invention provides the following technical solution: a production method for enriching polyunsaturated fatty acids, comprising:

[0009] Add oil and auxiliary materials into a crystallization tank, cool gradually and stir to form crystals to obtain a suspension;

[0010] The obtained suspension is subjected to membrane filtration to obtain a concentrate and a filtrate;

[0011] The obtained filtrate is further cooled, stirred and filtered to obtain the expected product enriched in polyunsaturated fatty acids.

[0012] As a preferred embodiment of the production method for enriching polyunsaturated fatty acids of the present invention, the oil comprises one or more of triglycerides, fatty acid methyl esters, fatty acid ethyl esters, monoglycerides, diglycerides, fatty acids and fatty acid salts.

[0013] As a preferred embodiment of the production method for enriching polyunsaturated fatty acids of the present invention, the auxiliary materials include an organic solvent and a surfactant;

[0014] The organic solvent includes one or more of n-hexane, benzene, methanol, carbon tetrachloride, ethyl acetate, ethanol, tert-butanol, acetone, acetonitrile, dichloromethane and methanol.

[0015] The surfactant includes one or more of sodium dodecyl sulfate, mono- and di-glycerides, phospholipids, hydroxyglycerides, sorbitan fatty acid esters, and polyglycerol fatty acid esters.

[0016] As a preferred embodiment of the production method for enriching polyunsaturated fatty acids of the present invention, the membrane filtration adopts a pipeline membrane form, and the suspension is pressurized and flows through the pipeline membrane in a directional manner.

[0017] As a preferred embodiment of the production method for enriching polyunsaturated fatty acids of the present invention, the membrane material of the membrane filtration includes one or more of organic nylon, polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, glass fiber, water-based fiber, acetate fiber and ceramic.

[0018] As a preferred embodiment of the production method for enriching polyunsaturated fatty acids of the present invention, the pore size of the filtration membrane in the membrane filtration is in the range of 30 μm-40 μm.

[0019] As a preferred embodiment of the production method for enriching polyunsaturated fatty acids of the present invention, the filtration pressure of the suspension in the pipeline membrane is set in the range of 10 bar to 12.5 bar.

[0020] One of the beneficial effects of the present invention is that the traditional fractionation process is basically intermittent or semi-continuous operation, which requires slow cooling and slow stirring for crystallization, and filtering and separation when the crystals grow to a certain extent. On the one hand, this type of filtration method for separating crystals has very high requirements on the size, shape, uniformity, etc. of the crystals. The present invention can fully realize fully automatic continuous operation through the filtration equipment in the form of a pipeline membrane, which reduces the crystal particle size requirements to a certain extent and greatly improves the work efficiency.

[0021] Another object of the present invention is to provide a production system enriched with polyunsaturated fatty acids.

[0022] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0023] The mixing unit includes a crystallization tank, which is used to mix and stir the oil and auxiliary materials to obtain a reaction stock solution;

[0024] A cooling unit is used to cool the reaction solution in the crystallization tank to precipitate crystals and obtain a suspension;

[0025] A filtration unit, used to filter out the crystals in the suspension to obtain a concentrate and a filtrate; and

[0026] The fractionation unit is used to further cool, stir and filter the obtained filtrate.

[0027] As a preferred solution of the production system for enriching polyunsaturated fatty acids of the present invention, the filtration unit comprises a membrane filter connected to a crystallization tank, and a diaphragm pump arranged on one side of the membrane filter;

[0028] The temperature reduction unit includes a cold zone jacket connected to the membrane filter.

[0029] As a preferred solution of the polyunsaturated fatty acid enrichment production system of the present invention, wherein: the membrane filters are provided in no less than two groups;

[0030] The filtration unit also includes an infrared heating device and a nitrogen purge device adapted to the membrane filter.

[0031] Another beneficial effect of the present invention is that, without setting up a cold storage, the present invention sets a cold zone jacket on the membrane filtration equipment, and the crystallization freezing liquid circulates through the jacket to ensure that the crystallization temperature is consistent with the cooling temperature, which greatly saves the investment cost of building a cold storage. In addition, in actual operation, the filtration environment temperature is only limited to the inside of the membrane filter pipeline, which saves energy and reduces consumption, has precise temperature control, and saves operating costs. Personnel operation does not need to enter the cold storage, which optimizes the working environment. The membrane filtration equipment occupies a small area, has a large space utilization rate, and has a low cost for later maintenance and replacement. The membrane filter designed by the present invention is equipped with an infrared heating device and a nitrogen purge device, and can be equipped with an automatic control program to achieve maintenance-free and automatic cleaning effects.

[0032] Another object of the present invention is to provide a material injection device.

[0033] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0034] A material injection device, comprising a top feed pipe arranged above the crystallizer, and a side feed pipe arranged on the side of the crystallizer, wherein the side feed pipe is located inside the crystallizer and connected with a material distribution mechanism, and a staggered distribution mechanism is arranged between the material distribution mechanism and a stirring shaft in the crystallizer;

[0035] The material distribution mechanism includes a mixing box arranged inside the crystallization tank, a guide plate arranged on the top of the mixing box, a guide strip arranged on the guide plate, an extrusion hole arranged at the bottom of the mixing box, a mounting hole arranged on one side of the inner part of the mixing box, a rotating plate rotatably arranged on the mounting hole, a plurality of extrusion plates fixedly connected to the outer wall of the rotating plate, and a separation arc knife corresponding to the lateral feeding pipe is arranged on the extrusion plate.

[0036] As a preferred embodiment of the injection device of the present invention, the staggered mechanism comprises a connecting sleeve arranged on the stirring shaft in the crystallization tank, a connecting cylinder arranged on the peripheral side of the connecting sleeve, a cut-off groove arranged inside the connecting cylinder, a cut-off block is arranged inside the cut-off groove, a resistance rod is connected to the cut-off block, a return spring is arranged between the resistance rod and the connecting cylinder, a counterweight block is fixedly connected to one end of the resistance rod away from the return spring, a staggered groove is arranged between the counterweight block and the resistance rod, a plurality of driving rods are arranged at the bottom of the rotating plate, and a plurality of cutters are arranged at the peripheral side of the bottom of the rotating plate;

[0037] The staggered mechanism also includes a plurality of edge arc surfaces arranged on the counterweight block corresponding to the driving rod, and the side wall of the counterweight block is in contact with the outer wall of the driving rod.

[0038] As a preferred solution of the injection device of the present invention, wherein: the inner wall of the rotating plate is provided with a resistance groove corresponding to the mounting hole, the outer wall of the rotating plate is provided with a sealing groove corresponding to the mounting hole, and the top of the rotating plate is provided with an inclined surface.

[0039] Another beneficial effect of the present invention is that the setting of the material dividing mechanism can mix the reactants in the initial stage, which is convenient for the subsequent reaction in the crystallization tank. The setting of the staggered mechanism can effectively cooperate with the movement of the injection device when the stirring is rotating at a low speed. When rotating at a high speed, the injection device is separated from the stirring rod, so that the injection and stirring work are separated, achieving the purpose of one shaft serving two purposes, feeding when rotating at a low speed, and mixing the materials inside the crystallization tank when rotating at a high speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0041] Figure 1 It is a process flow chart of the present invention.

[0042] Figure 2 for Figure 1 A magnified schematic diagram of center A.

[0043] Figure 3 This is a polarized light microscope picture of the crystal in Example 2 of the present invention.

[0044] Figure 4 This is a polarized light microscope picture of the crystal in Example 3 of the present invention.

[0045] Figure 5 This is a polarized light microscope picture of the crystal in Example 4 of the present invention.

[0046] Figure 6 This is a polarized light microscope picture of the crystal in Example 5 of the present invention.

[0047] Figure 7 This is a schematic diagram of the structure of the injection device in Example 7 of the present invention.

[0048] Figure 8 This is a schematic diagram of the internal structure of the injection device in Example 7 of the present invention.

[0049] Fig. 9 It is a schematic diagram of the structure of the material dividing mechanism and the staggered dividing mechanism in Example 7 of the present invention.

[0050] Fig.10 This is a schematic diagram of the mixing box structure in Example 7 of the present invention.

[0051] Fig.11 This is a schematic diagram of the internal structure of the mixing box in Example 7 of the present invention.

[0052] Fig.12 This is a schematic diagram of the structure of the rotating plate in Example 7 of the present invention.

[0053] Fig.13 This is a cross-sectional view of a mixing box in Example 7 of the present invention.

[0054] Fig.14 for Fig.13 Enlarged view of point A in the middle.

[0055] Fig.15 This is a cross-sectional view of the connecting tube in Example 7 of the present invention. DETAILED DESCRIPTION

[0056] In order to make the objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0057] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0058] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0059] The present invention selects the various components of fats and oils as shown in the following table:

[0060] Table 1 Fatty acid composition of fish oil

[0061]

[0062]

[0063] Example 1

[0064] Reference Figure 1-2 The present embodiment provides a production system for enriching polyunsaturated fatty acids, including a mixing unit 100, a cooling unit 200, a filtering unit 300 and a fractionation unit 400. For ease of understanding, in the figure, Y represents filtered oil, NY represents concentrated oil, LM represents refrigerant, SQ represents steam, NQ represents nitrogen, and ZK represents vacuum.

[0065] Specifically, the mixing unit 100 is composed of a crystallization tank 101 for storage and a stirring device, which is used to mix and stir the oil and auxiliary materials to obtain a reaction stock solution; the cooling unit 200 includes a cold zone jacket 201 arranged on the outside of the membrane filter 301, which is used to cool the reaction stock solution to precipitate crystals to obtain a suspension; the filtering unit 300 includes a membrane filter 301 connected to the mixing unit 100, and a diaphragm pump 302 arranged on one side of the membrane filter 301, which is used to filter out the crystals in the suspension to obtain a concentrated solution and a filtrate; the extraction unit 400 is used to further cool, stir and filter the obtained filtrate; the cold zone jacket 201 is arranged on the outside of the pipe-shaped membrane filter 301, and the pipe-shaped membrane filter 301 can be connected and arranged for circulation, and the suspension is cooled by the cold zone jacket 201. After reaching a suitable temperature, filtration is started, and the cold zone jacket 201 replaces the cold storage with a large area in the prior art, which can greatly save floor space.

[0066] First, the oil is heated to 40°C by dry fractionation to eliminate all crystals. At a stirring rate of 5 to 90 r / min, the first fraction is cooled to 0°C at a cooling rate of 2 to 8°C / h, crystallized at a constant temperature for 12 to 48 hours, and high-melting-point esters are removed by membrane separation to obtain liquid oil; the liquid oil enters the second fraction, cooled to -30°C at a cooling rate of 2 to 8°C / h, crystallized at a constant temperature for 12 to 48 hours, and high-melting-point esters are removed by membrane separation to obtain liquid oil; the liquid oil enters the third fraction, cooled to -60°C at a cooling rate of 2 to 8°C / h, crystallized at a constant temperature for 12 to 48 hours, and high-melting-point esters are removed by membrane separation to achieve the purpose of enriching polyunsaturated fatty acids;

[0067] Furthermore, the membrane filter 301 is provided with no less than two groups, and the filtering unit 300 also includes an infrared heating device and a nitrogen purge device adapted to the membrane filter 301; in this embodiment, the membrane filter 301 is a disc-type pipeline structure, and the reaction suspension flows through the pipeline under a certain pressure and will be filtered through the pipeline membrane; compared with the direct barrier filtration commonly used in the prior art, the main flow direction of the fluid is parallel to the direction of the filter hole, which is easy to form blockage; in this embodiment, since the main flow direction of the fluid is along the inner wall of the pipeline, it is perpendicular to the direction of the filter hole, which will provide a certain flushing force on the inner wall, flush the adhesive on the inner wall, thereby delaying the blockage of the membrane hole.

[0068] Since the membrane filter 301 adopts a pipeline structure, the internal suspension can be circulated to improve the filtering effect. In this embodiment, two identical membrane filters 301 are set in the middle of each fractionation and used alternately. When the pressure in one of the membrane filters 301 is detected to be continuously increased to reach the set value, it means that the filter membrane is becoming more and more seriously blocked and the filtering efficiency is also reduced. When the filter membrane needs to be cleaned, the internal liquid is switched to another membrane filter 301 to continue continuous filtering. The infrared heating device of the membrane filter 301 that needs to be cleaned is turned on to 60-80°C and maintained for 30-60 minutes, and the nitrogen purge device is turned on to restore the membrane flux. The infrared heating device and the nitrogen purge device are conventional means of the prior art, and can be adaptively arranged in combination with the pipeline-shaped membrane filter 301 of this embodiment. The improvement of the present invention over the prior art is that the filter membrane is cleaned alternately by two groups of identical membrane filters 301 without affecting the progress of the entire process, and the entire process is repeated in this way to achieve continuous progress.

[0069] Example 2

[0070] Reference Figure 3 , This embodiment adopts dry fractionation, that is, after obtaining the first-level or second-level fraction liquid, solvent selective fractionation is performed to achieve the purpose of enriching polyunsaturated fatty acids, and the pore size of the membrane filter 301 is 30um, specifically: the fish oil ethyl ester with the fatty acid content in Table 1 is heated to 40°C through a heat exchanger to eliminate all crystals, enters the 1# crystallization tank 101, the stirring rate is 10r / min, and the temperature is reduced to 0°C at a cooling rate of 2°C / h. The crystal is grown for 24h, and the discharge valve and the corresponding diaphragm pump under the 1# crystallization tank 101 are opened, and the 1# membrane separation equipment of the filtration unit 300 is pumped into the membrane material. The membrane material is polytetrafluoroethylene with a pore size of 30um. At this time, the temperature inside the membrane filter 301 is 0±2°C, and the concentrated liquid is circulated back to the 1# crystallization tank 101 through the explosion-proof diaphragm pump, and the liquid oil enters the 2# crystallization tank 101 through the diaphragm pump, and the final concentrated liquid enters the 1# concentrated oil tank;

[0071] Add the cooled n-hexane solvent to the 2# crystallizer 101, the ratio of oil to auxiliary solvent is 1:5, start the second-stage fractionation, cool down to -20°C at a cooling rate of 3°C / h, stir at a rate of 10r / min, grow crystals for 24h, open the discharge valve and corresponding diaphragm pump under the 2# crystallizer 101, pump into the 2# membrane separation equipment, the membrane material is polytetrafluoroethylene, the pore size is 30um, at this time the temperature inside the membrane filter 301 is -20±2°C, the concentrate is circulated back to the 2# crystallizer 101 through the diaphragm pump, the liquid oil enters the 3# crystallizer 101 through the diaphragm pump, and the final concentrate enters the 2# concentrated oil tank;

[0072] The third stage fractionation starts from the 3# crystallization tank 101, and the temperature is reduced to -60°C at a cooling rate of 2°C / h, the stirring rate is 10r / min, and the crystallization is carried out at a constant temperature for 24h. The discharge valve and the corresponding diaphragm pump under the 3# crystallization tank 101 are opened, and the 3# membrane separation equipment is pumped in. The membrane material is polytetrafluoroethylene with a pore size of 30um. At this time, the temperature inside the membrane filter 301 is -60±2°C. The concentrated liquid is circulated back to the 3# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the finished oil tank through the diaphragm pump. The final concentrated liquid enters the 3# concentrated oil tank. The 1#, 2#, and 3# concentrated oils can form different series of by-products according to the different fatty acid compositions, such as pet feed oil ingredients.

[0073] Example 3

[0074] Reference Figure 4 , this embodiment is different from embodiment 2 in that solvent selective fractionation is directly adopted, and a faster stirring rate and cooling rate are provided, specifically: the fish oil ethyl ester with fatty acid content in Table 1 is heated to 40°C through a heat exchanger to eliminate all crystals, enters the 1# crystallization tank 101, adds n-ethane solution, the ratio of oil to auxiliary material solution is 1:5, the stirring rate is 15r / min, and the temperature is reduced to -10°C at a cooling rate of 4°C / h, and the crystal is grown for 30h. The discharge valve under the 1# crystallization tank 101 and the corresponding explosion-proof diaphragm pump are opened, and the 1# membrane separation equipment of the filtration unit 300 is pumped into the membrane material. The membrane material is polytetrafluoroethylene with a pore size of 30um. At this time, the temperature inside the membrane filter 301 is -10±2°C, and the concentrated liquid is circulated back to the 1# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the 2# crystallization tank 101 through the diaphragm pump, and the final concentrated liquid enters the 1# concentrated oil tank;

[0075] The second fractionation of the 2# crystallizer 101 is started, the temperature is reduced to -30°C at a cooling rate of 4°C / h, the stirring rate is 15r / min, and the crystallization is carried out at a constant temperature for 30h. The discharge valve and the corresponding explosion-proof diaphragm pump under the 2# crystallizer 101 are opened, and the 2# membrane separation equipment is pumped in. The membrane material is polytetrafluoroethylene, and the pore size is 30um. At this time, the temperature inside the membrane filter 301 is -30±2°C, and the concentrated liquid is circulated back to the 2# crystallizer 101 through the diaphragm pump, and the liquid oil enters the 3# crystallizer 101 through the diaphragm pump, and the final concentrated liquid enters the 2# concentrated oil tank;

[0076] The third stage fractionation is started in the 3# crystallization tank 101, with the temperature dropping to -60°C at a cooling rate of 3°C / h, the stirring rate of 15r / min, and the crystallization is carried out at a constant temperature for 30h. The discharge valve and the corresponding diaphragm pump under the 3# crystallization tank 101 are opened, and the 3# membrane separation equipment is pumped in. The membrane material is polytetrafluoroethylene with a pore size of 30um. At this time, the temperature inside the membrane filter 301 is -60±2°C. The concentrated liquid is circulated back to the 3# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the finished oil tank through the explosion-proof diaphragm pump. The final concentrated liquid enters the 3# concentrated oil tank.

[0077] Example 4

[0078] Reference Figure 5 , this embodiment also adopts dry fractionation, but different from embodiment 2, this embodiment provides faster stirring rate and cooling speed, and the pore size of membrane filter 301 is 10um, specifically: the fish oil ethyl ester with fatty acid content in Table 1 is heated to 40°C through a heat exchanger to eliminate all crystals, enters 1# crystallization tank 101, the stirring rate is 30r / min, and the temperature is reduced to 0°C at a cooling rate of 4°C / h, and the crystal is grown for 12h, the discharge valve under 1# crystallization tank 101 and the corresponding diaphragm pump are opened, and the 1# membrane separation equipment of the filtration unit 300 is pumped into the membrane material. The membrane material is polytetrafluoroethylene with a pore size of 10um. At this time, the temperature inside the membrane filter 301 is 0±2°C, and the concentrated liquid is circulated back to 1# crystallization tank 101 through the diaphragm pump, and the liquid oil enters 2# crystallization tank 101 through the diaphragm pump, and the final concentrated liquid enters 1# concentrated oil tank;

[0079] Add the cooled n-hexane solvent to the 2# crystallizer 101, the ratio of oil to auxiliary solvent is 1:5, start the second fractionation, cool down to -20°C at a cooling rate of 4°C / h, stir at 30r / min, grow crystals for 12h, open the discharge valve and corresponding diaphragm pump under the 2# crystallizer 101, pump into the 2# membrane separation equipment, the membrane material is polytetrafluoroethylene, the pore size is 10um, at this time the temperature inside the membrane filter 301 is -20±2°C, the concentrate is circulated back to the 2# crystallizer 101 through the diaphragm pump, the liquid oil enters the 3# crystallizer 101 through the diaphragm pump, and the final concentrate enters the 2# concentrated oil tank;

[0080] The third stage fractionation starts in the 3# crystallization tank 101, the cooling rate drops to -60°C at 3°C / h, the stirring rate is 30r / min, and the crystallization is carried out at a constant temperature for 12h. The discharge valve and the corresponding diaphragm pump under the 3# crystallization tank 101 are opened, and the 3# membrane separation equipment is pumped in. The membrane material is polytetrafluoroethylene with a pore size of 10um. At this time, the temperature inside the membrane filter 301 is -60±2°C. The concentrated liquid is circulated back to the 3# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the finished oil tank through the diaphragm pump, and the final concentrated liquid enters the 3# concentrated oil tank.

[0081] Example 5

[0082] Reference Figure 6 , this embodiment directly adopts solvent selective fractionation, which is different from Example 3 in that the stirring rate and the cooling rate are further improved, and the pore size of the membrane filter 301 is 30um, specifically: the fish oil ethyl ester with fatty acid content in Table 1 is heated to 40°C through a heat exchanger to eliminate all crystals, enters the 1# crystallization tank 101, adds n-ethane solution, the ratio of oil and auxiliary material solution is 1:5, the stirring rate is 40r / min, and the temperature is reduced to -10°C at a cooling rate of 6°C / h, and the crystal is grown for 12h, and the discharge valve and the corresponding explosion-proof diaphragm pump under the 1# crystallization tank 101 are opened, and the 1# membrane separation equipment of the filtration unit 300 is pumped into the membrane material. The membrane material is polytetrafluoroethylene with a pore size of 10um. At this time, the temperature inside the membrane filter 301 is -10±2°C, and the concentrated liquid is circulated back to the 1# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the 2# crystallization tank 101 through the diaphragm pump, and the final concentrated liquid enters the 1# concentrated oil tank;

[0083] The second fractionation is started in the 2# crystallization tank 101, and the temperature is lowered to -30°C at a cooling rate of 6°C / h, the stirring rate is 40r / min, and the crystallization is carried out at a constant temperature for 12h. The discharge valve and the corresponding explosion-proof diaphragm pump under the 2# crystallization tank 101 are opened, and the 2# membrane separation equipment is pumped in. The membrane material is polytetrafluoroethylene, and the pore size is 10um. At this time, the temperature inside the membrane filter 301 is -30±2°C, and the concentrated liquid is circulated back to the 2# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the 3# crystallization tank 101 through the diaphragm pump, and the final concentrated liquid enters the 2# concentrated oil tank;

[0084] The third stage fractionation is started in the 3# crystallization tank 101, and the temperature is reduced to -60°C at a cooling rate of 3°C / h, the stirring rate is 40r / min, and the crystallization is carried out at a constant temperature for 12h. The discharge valve and the corresponding diaphragm pump under the 3# crystallization tank 101 are opened, and the 3# membrane separation equipment is pumped in. The membrane material is polytetrafluoroethylene with a pore size of 10um. At this time, the temperature inside the membrane filter 301 is -60±2°C. The concentrated liquid is circulated back to the 3# crystallization tank 101 through the diaphragm pump, and the liquid oil enters the finished oil tank through the explosion-proof diaphragm pump. The final concentrated liquid enters the 3# concentrated oil tank.

[0085] Comparative Example 1

[0086] The fish oil ethyl ester with fatty acid content in Table 1 is heated to 40°C through a heat exchanger to eliminate all crystals, and enters the 1# crystallization tank 101, and n-ethane solution is added, the volume ratio of fish oil to n-ethane is 1:5, the stirring rate is 10r / min, and the temperature is reduced to -10°C at a cooling rate of 2°C / h. The crystal is grown for 48h, and the discharge valve under the 1# crystallization tank 101 is opened and pumped into the vacuum filter in the 1# cold storage. The temperature inside the cold storage is -10°C. The mixed liquid is pumped into the 2# crystallization tank 101 with an explosion-proof pump or compressed gas, and the filter residue is desolventized and recovered.

[0087] The second fractionation is started in the 2# crystallization tank 101, and the temperature is lowered to -30°C at a cooling rate of 2°C / h, the stirring rate is 10r / min, and the crystallization is carried out at a constant temperature for 48h. The discharge valve and the corresponding explosion-proof diaphragm pump under the 2# crystallization tank 101 are opened, and the mixture is pumped into the vacuum filter in the 2# cold storage. The ambient temperature inside the 2# cold storage is -30°C. The mixed liquid is pumped into the 3# crystallization tank 101 by an explosion-proof pump or compressed gas, and the residue is desolventized and recovered;

[0088] The third stage fractionation was started in 3# crystallization tank 101, with the temperature dropping to -60°C at a cooling rate of 2°C / h and a stirring rate of 10r / min. The crystallization was carried out at a constant temperature for 48h. The discharge valve and the corresponding diaphragm pump under 3# crystallization tank 101 were opened, and the vacuum filter in 3# cold storage was pumped. The ambient temperature inside 3# cold storage was -60°C. The final filtrate was desolventized and then entered into the finished oil tank, and the filter residue was desolventized and recovered.

[0089] By comparing the results of Examples 2-5 with Comparative Example 1, the effects of different fractionation methods, crystallization conditions, and membrane pore sizes on the products were obtained, as shown in Table 2:

[0090] Table 2 Effects of different experimental factors and environments on polyunsaturated fatty acid production

[0091] Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Crystal size distribution μm 150-180 100-130 90-110 40-60 200-280 Process time hours 122 115 61 53.3 204 HUFA content% 73.6 74.8 71.2 69.8 75.3

[0092] Result analysis:

[0093] Crystallization conditions: The stirring rates of Example 2 to Example 5 are 10 r / min, 15 r / min, 30 r / min and 40 r / min, respectively; the cooling rates are 2°C / h, 4°C / h, 4°C / h and 6°C / h, respectively; the crystal growing times are 24 h, 30 h, 12 h and 12 h, respectively. It can be seen from Table 2 that the faster the cooling rate, the faster the stirring rate, the shorter the crystal growing time, the smaller the crystal particles, and vice versa.

[0094] Extraction method: Example 2 and Example 4 use dry-solvent mixed extraction, and Example 3 and Example 5 use solvent extraction. During the experiment, it was found that the viscosity of dry extraction was very high at low temperature, filtration separation was difficult, and the yield was low, so it was generally only used in the first-stage extraction. Solvent extraction increases the solubility of crystals, which reduces the crystallization temperature, but has a low filtration viscosity, good crystal size uniformity, and is easy to filter and separate. As can be seen from Table 2, compared with Comparative Example 1, the various embodiments of the present invention have little difference in the HUFA content of the product, but save process time, have high production efficiency, and have great advantages. Example 5 is preferred.

[0095] Example 6

[0096] The other conditions of this embodiment are the same as those of embodiment 3. The difference is that the pore sizes of the membrane filter 301 of different sizes and the filtering pressures of different sizes applied by the diaphragm pump to the inner wall of the pipeline membrane are set. A further comparative experiment is conducted, and the test data results are recorded as follows:

[0097] Table 3 Effects of different membrane pore sizes and filtration pressures on the results

[0098]

[0099] Result analysis:

[0100] As the filtration pressure increases, the total production time decreases and the HUFA content increases; smaller membrane pore size may lead to an increase in the total production time but can increase the HUFA content.

[0101] When the filtration pressure increased from 10 bar to 15 bar, the total production time was significantly reduced and the HUFA content of polyunsaturated fatty acids increased; when the membrane pore size increased from 20 μm to 50 μm, the total production time was reduced, but the HUFA content of polyunsaturated fatty acids also increased.

[0102] In order to find the best range, we need to find a balance between production efficiency and product quality. From the data, we can see that when the filtration pressure is between 10 bar and 12.5 bar and the membrane pore size is between 30 μm and 40 μm, the total production time and the polyunsaturated fatty acid HUFA content are well balanced.

[0103] Example 7

[0104] Reference Figure 7-15 A material injection device includes a top feed pipe 500 arranged above a crystallization tank 101, and a side feed pipe 600 arranged on the side of the crystallization tank 101, the side feed pipe 600 is located inside the crystallization tank 101 and is connected with a distribution mechanism 601, and a staggered distribution mechanism 602 is provided between the distribution mechanism 601 and the stirring shaft in the crystallization tank 101.

[0105] Furthermore, the top feed pipe 500 is provided to introduce non-fluid materials. The crystallizer 101 will generate gases during operation, and these gases need to be discharged in time. The top feed pipe 500 also has an exhaust function to avoid excessive air pressure inside the crystallizer 101. The distribution mechanism 601 is provided to mix the reactants in the initial stage to facilitate the subsequent reaction in the crystallizer 101. The staggered mechanism 602 is provided to effectively cooperate with the movement of the injection device when the stirring is rotated at a low speed. When rotating at a high speed, the injection device is separated from the stirring rod, so that the injection and stirring work are separated, achieving the purpose of dual use of one axis, feeding when rotating at a low speed, and mixing the materials inside the crystallizer 101 when rotating at a high speed.

[0106] The material distribution mechanism 601 includes a mixing box 601a disposed inside the crystallization tank 101, a guide plate 601b disposed on the top of the mixing box 601a, and a guide strip 601c disposed on the guide plate 601b.

[0107] Furthermore, the cross-section of the mixing box 601a is annular. The setting of the mixing box 601a can effectively perform preliminary mixing of the fluid raw materials, which is convenient for the subsequent mixing inside the crystallization tank 101. The setting of the guide plate 601b can effectively guide the material in the top feed pipe 500 to enter the middle position of the crystallization tank 101. The setting of the guide strip 601c can effectively guide the material located on the guide plate 601b, so that the material passing through the guide plate 601b can be guided to the central area of ​​the crystallization tank 101.

[0108] An extrusion hole 601d is arranged at the bottom of the mixing box 601a, a mounting hole 601e is arranged on one side of the inner part of the mixing box 601a, a rotating plate 601f is rotatably arranged on the mounting hole 601e, an interference groove 601i is arranged on the inner wall of the rotating plate 601f corresponding to the mounting hole 601e, a sealing groove 601j is arranged on the outer wall of the rotating plate 601f corresponding to the mounting hole 601e, an inclined surface 601k is arranged on the top of the rotating plate 601f, a plurality of extrusion plates 601g are fixedly connected to the outer wall of the rotating plate 601f, and a separation arc knife 601h corresponding to the side feeding pipe 600 is arranged on the extrusion plate 601g.

[0109] Preferably, the cross section of the extrusion hole 601d is circular, the number of the extrusion holes 601d is multiple, and the multiple extrusion holes 601d are distributed in a circular array at the bottom of the mixing box 601a. ​​The mounting hole 601e is located at the edge of the inner wall of the mixing box 601a. ​​The setting of the abutment groove 601i and the sealing groove 601j can effectively increase the sealing between the rotating plate 601f and the mixing box 601a, so that the rotating plate 601f is always located on the mixing box 601a, and the rotating plate 601f is rotatably connected to the mixing box 601a. ​​The setting of the inclined surface 601k avoids The materials are piled on top of it, and the extrusion plate 601g cooperates with the bottom of the mixing box 601a and the extrusion hole 601d to mix large pieces of fluid materials. After mixing, they are divided into small portions to facilitate the subsequent mixing and stirring. At the same time, the small particles are located on the side of the crystallization tank 101 close to the inner wall. During stirring, they can directly contact the stirring fan blades. Driven by the stirring fan, they can be better mixed with the materials introduced from the top inlet pipe. The setting of the separation arc knife 601h is convenient for dividing the materials introduced from the side inlet pipe, which is convenient for the subsequent separation into small portions.

[0110] The staggered mechanism 602 includes a connecting sleeve 602a disposed on the stirring shaft in the crystallization tank 101, a connecting cylinder 602b disposed on the peripheral side of the connecting sleeve 602a, a cut-off groove 602c disposed inside the connecting cylinder 602b, a cut-off block 602d disposed inside the cut-off groove 602c, a resisting rod 602e connected to the cut-off block 602d, a return spring 602f disposed between the resisting rod 602e and the connecting cylinder 602b, and the resisting rod 602e is away from the return spring 602f. A counterweight block 602g is fixedly connected to one end of 602f, and a staggered groove 602h is provided between the counterweight block 602g and the resistance rod 602e. A plurality of driving rods 602i are provided at the bottom of the rotating plate 601f, and a plurality of cutting knives 602j are provided on the peripheral side of the bottom of the rotating plate 601f. The staggered mechanism 602 also includes a plurality of edge arc surfaces 602k arranged on the counterweight block 602g corresponding to the driving rod 602i, and the side wall of the counterweight block 602g is in contact with the outer wall of the driving rod 602i.

[0111] Among them, the setting of the connecting sleeve 602a can effectively transfer the driving force on the stirring shaft to the connecting sleeve 602b. When the stirring shaft rotates during use, the connecting sleeve 602b rotates. The setting of the cut-off groove 602c and the cut-off block 602d can effectively limit the interference rod 602e. During use, the stirring shaft rotates, and the counterweight block 602g moves under the action of centrifugal force. The moving distance of the counterweight block 602g is related to the rotation speed of the stirring shaft. When the stirring shaft rotates slowly, the counterweight block 602g contacts the driving rod 602i, and the driving rod 602i rotates under the interference of the counterweight block. When the driving rod 602i rotates, the rotating plate 601f rotates. When the rotation speed of the stirring shaft increases, the counterweight block 602g will move in the direction away from the driving shaft until it is out of contact with the driving rod 602i. At this time, the contact rod 602e is still rotating, and the misaligned groove 602h between the contact rod 602e and the counterweight block 602g is adapted to the driving rod 602i. The driving rod 602i cannot obtain the driving force. At the same time, the driving force of the stirring shaft reduces the obstruction, which can better stir the material. The setting of multiple cutters 602j can effectively cut off the material extruded by the extrusion hole 601d, which is convenient for dividing the material into small portions. The setting of the edge arc surface 602k plays a protective role when the counterweight block 602g is about to separate from the driving rod 602i, avoiding direct impact on the driving rod 602i, which will cause damage to the driving rod 602i and the counterweight block 602g.

[0112] When feeding, the material is introduced into the crystallization tank 101;

[0113] Part of the material is introduced into the crystallizer 101 through the top feed pipe 500, and the grease and additives to be mixed are introduced through the side feed pipe 600. At this time, the stirring motor in the crystallizer 101 is started. When the stirring motor is started, the stirring shaft thereof rotates, and the connecting sleeve 602a is driven to rotate. The connecting sleeve 602a rotates, and the resistance rod 602e and the counterweight block 602g are driven to rotate. The counterweight block 602g rotates, and the driving rod 602i is driven to rotate. The driving rod 602i rotates, and the rotating plate 601f is driven to rotate. The rotating plate 601f rotates, and the separation arc knife 601h and the extrusion plate 601g are driven to rotate. The separation arc knife 601h separates the material introduced from the side feed pipe 600. The separated material is extruded by the extrusion plate 601g and the mixing box 601a, so that the grease mixture is discharged through the extrusion hole 601d.

[0114] At the same time, the rotating plate 601f drives the cutter 602j to rotate, thereby cutting the extruded grease mixture.

[0115] When performing mixing work;

[0116] As the rotation speed of the stirring shaft increases, the counterweight 602g will move away from the drive shaft under the action of centrifugal force until it is out of contact with the drive rod 602i. At this time, the resistance rod 602e is still rotating, and the staggered groove 602h is adapted to the drive rod 602i. The drive rod 602i cannot obtain the driving force, and at the same time, the driving force of the stirring shaft is reduced, so that the stirring shaft can perform normal stirring work.

[0117] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0118] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0119] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0120] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A production system for enriching polyunsaturated fatty acids, characterized in that: The mixing unit (100) comprises a crystallization tank (101) for mixing and stirring the oil and auxiliary materials to obtain a reaction stock solution; A cooling unit (200) is used to cool the reaction stock solution in the crystallization tank (101) to precipitate crystals and obtain a suspension; A filtration unit (300) is used to filter out crystals in the suspension to obtain a concentrated solution and a filtrate; A fractionation unit (400) for further cooling, stirring and filtering the obtained filtrate; and an injection device (M); The filtration unit (300) comprises a membrane filter (301) connected to the crystallization tank (101), and a diaphragm pump (302) arranged on one side of the membrane filter (301); The temperature reduction unit (200) comprises a cold zone jacket (201) connected to a membrane filter (301); The membrane filters (301) are provided in no less than two groups; The filtering unit (300) further comprises an infrared heating device and a nitrogen purge device adapted to the membrane filter (301); The injection device (M) comprises a top feed pipe (500) arranged above the crystallization tank (101), and a side feed pipe (600) arranged on the side of the crystallization tank (101), wherein the side feed pipe (600) is located inside the crystallization tank (101) and is connected to a material distribution mechanism (601), and a staggered distribution mechanism (602) is provided between the material distribution mechanism (601) and a stirring shaft in the crystallization tank (101); The material distribution mechanism (601) comprises a mixing box (601a) arranged inside the crystallization tank (101), a guide plate (601b) arranged on the top of the mixing box (601a), a guide strip (601c) arranged on the guide plate (601b), an extrusion hole (601d) arranged at the bottom of the mixing box (601a), a mounting hole (601e) arranged on one side of the inner part of the mixing box, and a rotating plate (601f) rotatably arranged on the mounting hole (601e), a plurality of extrusion plates (601g) being fixedly connected to the outer wall of the rotating plate (601f), and a separation arc knife (601h) corresponding to the lateral feeding pipe (600) is arranged on the extrusion plate (601g); The staggered mechanism (602) comprises a connecting sleeve (602a) arranged on the stirring shaft in the crystallization tank (101), a connecting sleeve (602b) arranged on the peripheral side of the connecting sleeve (602a), a cut-off groove (602c) arranged inside the connecting sleeve (602b), a cut-off block (602d) being arranged inside the cut-off groove (602c), a resisting rod (602e) being connected to the cut-off block (602d), and the resisting rod (602e) being connected to the cut-off block (602d). e) and the connecting tube (602b), a return spring (602f) is provided between the end of the abutment rod (602e) away from the return spring (602f), a counterweight block (602g) is fixedly connected, a staggered groove (602h) is provided between the counterweight block (602g) and the abutment rod (602e), a plurality of driving rods (602i) are provided at the bottom of the rotating plate (601f), and a plurality of cutting knives (602j) are provided on the peripheral side of the bottom of the rotating plate (601f); The staggered mechanism (602) further comprises a plurality of edge arc surfaces (602k) arranged on the counterweight block (602g) corresponding to the driving rod (602i), and the side wall of the counterweight block (602g) is in contact with the outer wall of the driving rod (602i); An inner wall of the rotating plate (601f) corresponding to the mounting hole (601e) is provided with a resistance groove (601i), an outer wall of the rotating plate (601f) corresponding to the mounting hole (601e) is provided with a sealing groove (601j), and an inclined surface (601k) is provided on the top of the rotating plate (601f).

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