Method for recovering residual oil in adsorbent for linseed oil production

Abstract

The invention provides a method for recovering residual oil in an adsorbent for linseed oil production, and relates to the technical field of residual oil recovery, and the method comprises the following steps: step 1, crushing an oil-containing adsorbent by using a wall breaking machine to destroy a porous structure of the oil-containing adsorbent and release free oil wrapped by micropores and mesopores; step 2, carrying out centrifugal separation on the crushed adsorbent by using a high-speed centrifugal machine so as to preliminarily separate grease in the adsorbent; step 3, carrying out enzymolysis impregnation on the oil-containing adsorbent material bag after centrifugal separation by utilizing a demulsifying enzyme preparation so as to destroy a physical and chemical adsorption interface between grease and the adsorbent and promote release of non-polar grease; step 4, squeezing the oil-containing adsorbent subjected to enzymolysis impregnation based on multi-section gradient pressure so as to deeply degrease the oil-containing adsorbent; in the squeezing process, temperature rise control is matched, so that the grease viscosity is reduced, and grease outflow is promoted. According to the scheme, the residual oil rate in the adsorbent can be reduced, and the yield of the linseed oil is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of residual oil recovery, in particular to a method for recovering residual oil in adsorbent for flaxseed oil production. BACKGROUND

[0002] Flaxseed oil is a high-nutrition edible oil extracted from flaxseed, and its core advantage is that it is rich in alpha-linolenic acid, which is an essential omega-3 polyunsaturated fatty acid in the human body, and the content is usually ≥ 50%, much higher than common vegetable oils such as soybean oil and rapeseed oil. Alpha-linolenic acid can be converted into EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) in the human body, has physiological functions such as regulating blood lipids, protecting the cardiovascular system, and promoting brain development, and is widely used in the fields of health food and dietary supplements, and the market demand continues to grow. The quality requirements of flaxseed oil are extremely strict, not only the retention rate of active ingredients such as alpha-linolenic acid needs to be guaranteed, but also the indicators such as clear color, no odor, and low-temperature non-coagulation need to be met, which puts high requirements on the production process.

[0003] At present, the main processes in the production of flaxseed oil are raw material pretreatment, oil extraction by pressing, and refining and purification. Among them, the refining and purification mainly goes through three key steps of decolorization, deodorization and dewaxing, and the adsorbent (activated carbon, activated clay, diatomite) is the core auxiliary material for improving the quality in the process of refining and purification, which can solve the problems of pigment residue, odor residue and low-temperature coagulation. However, the adsorbent has a rich microporous / mesoporous structure, and these voids are the core areas for adsorbing pigments, odors and wax esters. Although such structure effectively solves the quality problem of flaxseed oil, it also becomes a container for oil retention, resulting in a high residual oil rate of the adsorbent. Moreover, due to the existence of hydroxyl, carboxyl, carbonyl and other oxygen-containing functional groups on the surface of activated carbon, these functional groups will chemically react with polar components such as phospholipids and free fatty acids in oil and fat, forming hydrogen bonds or coordination bonds, which further enhances the binding force between oil and fat and the adsorbent, and also makes it more difficult to separate the residual oil. In actual flaxseed oil production, the high residual oil rate and the difficulty in separating the residual oil in the adsorbent greatly affect the yield of flaxseed oil. SUMMARY

[0004] Therefore, in view of the above problems, it is necessary to provide a method for recovering residual oil in adsorbent for flaxseed oil production to reduce the residual oil rate of the adsorbent and improve the yield of flaxseed oil.

[0005] The present application provides a method for recovering residual oil in adsorbent for flaxseed oil production, which comprises the following steps: Step 1: crushing the oil-containing adsorbent by using a cell disruptor to destroy the porous structure of the oil-containing adsorbent and release the free oil and fat wrapped by micropores and mesopores; Step 2: centrifugal separation of the broken adsorbent by using a high-speed centrifuge to preliminarily separate the oil in the adsorbent; Step 3: enzyme hydrolysis and impregnation of the oil-containing adsorbent package after centrifugal separation by using a demulsification enzyme preparation to destroy the physical and chemical adsorption interface between the oil and the adsorbent and promote the release of non-polar oil; wherein the demulsification enzyme preparation comprises lipase, phospholipase, polyglycerol ester, and enzyme stabilizer; Step 4: pressing of the oil-containing adsorbent after enzyme hydrolysis and impregnation based on multi-stage gradient pressure to deeply defat the oil-containing adsorbent; wherein temperature control is provided during the pressing process to reduce the viscosity of the oil and promote the outflow of the oil.

[0006] Preferably, in step 1, the blender uses a titanium alloy cutter assembly with a surface hardness not less than HRC60, the rotational speed of the blender is 18000-22000 rpm, the blade linear speed is not less than 150 m / s, and the breaking treatment time is such that the particle size of the broken adsorbent is not greater than 30 μm.

[0007] Preferably, the temperature of the oil-containing adsorbent is monitored in real time during the breaking treatment, so that the breaking treatment is stopped when the temperature is greater than a first preset temperature threshold, and the oil-containing adsorbent is cooled to room temperature before the breaking treatment is performed again, so as to avoid the expansion of the air entrained due to the temperature rise, affecting the progress of the breaking process.

[0008] Preferably, step 2 specifically comprises: S21: loading the broken oil-containing adsorbent into a nylon cloth pocket and compacting it by using a mechanical compactor to ensure that the thickness of each package meets a preset thickness; S22: placing the packages symmetrically in the 4 sectors of the centrifuge drum, and the weight deviation of the packages loaded in each sector is not greater than 0.5%; S23: controlling the high-speed centrifuge to work according to preset process parameters to preliminarily separate the oil in the packages.

[0009] Preferably, the mesh number of the nylon cloth pocket in step S21 is 500-800 mesh, and the nylon cloth pocket is soaked in deionized water at 40-60℃ for 10-20 minutes before loading the oil-containing adsorbent to reduce the adsorbability of the nylon cloth pocket to oil; the preset thickness is 100-120 mm.

[0010] Preferably, the preset process parameters in step S23 are: under normal temperature conditions, the rotational speed of the high-speed centrifuge is 8000-10000 rpm, and the treatment time is 5-10 min; under low temperature conditions, the temperature of the packages is raised to 25-35℃ by starting the electric heating jacket of the high-speed centrifuge, the rotational speed of the high-speed centrifuge is 8000-10000 rpm, and the treatment time is 4-8 min.

[0011] Preferably, the step 3 specifically comprises: S31: Put the oil-containing adsorbent bale after centrifugal separation into the enzymatic impregnation tank containing 50-60℃ deionized water; S32: Add demulsifying enzyme preparation to the enzymatic impregnation tank; wherein the demulsifying enzyme preparation comprises: 45-55% lipase, 25-35% phospholipase, 15-20% polyglycerol ester with HLB value of 12-14 and 5-10% enzyme stabilizer; S33: Stir the solid-liquid mixture in the enzymatic impregnation tank using a staged stirring strategy to promote the destruction of the oil-adsorbent interface and release non-polar oil.

[0012] Preferably, the staged stirring strategy comprises: in the first stage, stirring at a speed of 40-50 rpm for 10-14 hours to promote the contact between the demulsifying enzyme preparation and the oil-containing adsorbent; in the second stage, stirring at a speed of 20-30 rpm for 22-26 hours to avoid excessive stirring leading to the failure of the demulsifying enzyme preparation; in the third stage, stirring at a speed of 40-50 rpm for 10-14 hours to disperse the enzymatic products.

[0013] Preferably, the step 4 specifically comprises: First stage: control the press to slowly rise from 0 to 20 MPa in 1-2 hours to press the oil-containing adsorbent after enzymatic impregnation, and at the same time, control the oil-containing adsorbent to slowly rise to 40±1℃ by the temperature control device in the first stage; Second stage: control the press to slowly rise from 20 MPa to 40 MPa in 7-8 hours to press the oil-containing adsorbent after enzymatic impregnation, and at the same time, control the oil-containing adsorbent to slowly rise to 50±1℃ by the temperature control device in the second stage; Third stage: control the press to slowly rise from 40 MPa to 60 MPa in 7-10 hours to press the oil-containing adsorbent after enzymatic impregnation, and at the same time, control the oil-containing adsorbent to slowly rise to 60±1℃ by the temperature control device in the third stage; Fourth stage: control the press to slowly release from 60 MPa to 0 in 1-2 hours, and at the same time, stop the temperature control device in the fourth stage to naturally cool the oil-containing adsorbent.

[0014] Preferably, the surface of the rollers of the press is treated with nano-level polishing and sprayed with a polytetrafluoroethylene coating to reduce the adhesion of adsorbent particles.

[0015] From the above technical scheme can be known, the method for recovering residual oil in adsorbent for flaxseed oil production provided by the application, first, the oil-containing adsorbent is broken by a wall breaking machine to destroy the porous structure of the oil-containing adsorbent, so that the free oil wrapped by micropores and mesopores is released. Then, the broken adsorbent is centrifuged by a high-speed centrifuge to preliminarily separate the oil in the adsorbent. Further, the oil-containing adsorbent after centrifugal separation is subjected to enzymatic impregnation by a demulsifying enzyme preparation to destroy the physical and chemical adsorption interface between the oil and the adsorbent, so as to promote the release of nonpolar oil. Finally, the oil-containing adsorbent after enzymatic impregnation is pressed based on multi-stage gradient pressure to deeply defat the oil-containing adsorbent, and at the same time, the oil viscosity is reduced by temperature control, thereby promoting the oil to flow out. As can be seen, first, the broken treatment by the high-speed wall breaking machine can completely open the voids, and the gradual compression by the multi-stage gradient pressing can make the oil be released, thereby reducing the residual oil retention from the structural root. Second, the demulsifying enzyme preparation destroys the physical and chemical adsorption interface between the oil and the adsorbent, so that the binding force between the oil and the adsorbent is weakened, thereby facilitating the separation of the oil during pressing. In this way, the residual oil content in the adsorbent can be effectively reduced by the four-step cooperative treatment of wall breaking, centrifugation, enzymolysis and pressing, thereby greatly improving the yield of flaxseed oil. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A flow chart of the method for recovering residual oil in adsorbent for flaxseed oil production provided by the embodiment of the application is shown. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0018] As shown in Figure 1 , the embodiment of the application provides a method for recovering residual oil in adsorbent for flaxseed oil production, which comprises the following steps: Step 1: breaking the oil-containing adsorbent by a wall breaking machine to destroy the porous structure of the oil-containing adsorbent, so that the free oil wrapped by micropores and mesopores is released; Step 2: centrifuging the broken adsorbent by a high-speed centrifuge to preliminarily separate the oil in the adsorbent; Step 3: enzymatic impregnation of the centrifuged oil-containing adsorbent material package with a demulsification enzyme preparation to destroy the physical and chemical adsorption interface between the oil and the adsorbent and facilitate the release of non-polar oil; wherein the demulsification enzyme preparation comprises lipase, phospholipase, polyglycerol ester, and enzyme stabilizer; Step 4: pressing of the enzymatically impregnated oil-containing adsorbent based on multi-stage gradient pressure to achieve deep degreasing of the oil-containing adsorbent; wherein temperature control is provided during the pressing process to reduce the viscosity of the oil and facilitate the outflow of the oil.

[0019] In this embodiment, the high-speed cell disruptor is used for crushing treatment, which can completely open the voids, and the multi-stage gradient pressing can gradually compress the oil, thereby reducing the residual oil retention from the root cause. Secondly, the demulsification enzyme preparation is used to destroy the physical and chemical adsorption interface between the oil and the adsorbent, so that the binding force between the oil and the adsorbent is weakened, thereby facilitating the separation of the oil during pressing. In this way, the four-step cooperative treatment of cell disruption, centrifugation, enzymatic treatment, and pressing can effectively reduce the residual oil content in the adsorbent, thereby greatly improving the yield of flaxseed oil.

[0020] For Step 1, a cell disruptor is used to crush the oil-containing adsorbent to destroy the porous structure of the oil-containing adsorbent and release the free oil wrapped by micropores and mesopores.

[0021] In this step, the purpose is to destroy the porous structure of activated carbon, activated clay, diatomite, etc. in the oil-containing adsorbent through ultra-high-speed mechanical crushing, release the free oil wrapped by micropores and mesopores, lay a foundation for the subsequent separation process, and achieve effective release of free oil. Specifically, the cell disruptor uses a titanium alloy cutterhead assembly with a surface hardness not less than HRC60, the rotational speed of the cell disruptor is 18000-22000 rpm, the blade linear speed is not less than 150 m / s, and the crushing treatment time is such that the particle size of the crushed adsorbent is not greater than 30 μm, for example, the general treatment time is 4-12 minutes.

[0022] Due to the high-speed operation of the crusher, air from the outside will be drawn in. During the high-speed operation of the crusher, the temperature of the oil-containing adsorbent material will gradually rise due to constant friction with the material. When the temperature rises, the drawn-in air will expand, which will affect the crushing process and even damage the equipment. Therefore, in one embodiment, the temperature of the oil-containing adsorbent is monitored in real time during the crushing process, and the crushing process is stopped when the temperature exceeds a first preset temperature threshold, and the oil-containing adsorbent is cooled to room temperature before the crushing process is resumed, so as to avoid the expansion of the drawn-in air due to the rise in temperature, which affects the crushing process.

[0023] In this step, the high-speed shearing force destroys the porous structure of the adsorbent, causing the free oil to be released from the pores, forming an oil-adsorbent suspension. Further, the density difference between the oil and the solid particles can be used to achieve the preliminary separation of the oil and the adsorbent. In practice, the density of the oil is generally 0.91-0.93 g / cm³, and the density of the adsorbent is generally 1.2-1.8 g / cm³. Specifically, after the wall breaking is completed, the stirrer can be turned on to maintain the suspension state to prevent the solid particles from settling and caking. Then, the bottom valve is opened, and the suspension passes through the screen to filter out the solid particles, which are retained in the separation chamber, and the free oil passes through the filter into the collection tank. A liquid level sensor is installed in the collection tank, and when the oil quantity reaches 40 L, the gear pump is automatically started to transport the oil to the temporary storage tank, which is equipped with a stirring device to prevent the oil from stratifying.

[0024] In this step, a titanium alloy cutter is used to achieve a particle size of the adsorbent of ≤30 μm at a high speed. Compared with the traditional crushing process (particle size ≤50 μm), the porous structure of the adsorbent is more completely destroyed, the mesopore (2-50 nm) of the activated carbon and the micropore (1-3 nm) of the white clay have a significantly improved pore opening rate, and the release channel of the free oil originally wrapped by the pores is completely opened, laying a core foundation for the subsequent separation process. At the same time, the conical separation chamber at the bottom of the wall breaking machine is combined with multiple layers of screens to recover most of the free oil in advance, significantly reducing the oil content of the oil-adsorbent mixture entering the centrifugal process, reducing the processing pressure of the centrifugal equipment, and improving the defatting efficiency of the subsequent process.

[0025] For step 2, a high-speed centrifuge is used to separate the adsorbent after the crushing process to preliminarily separate the oil in the adsorbent.

[0026] In this step, the oil-adsorbent mixture after the wall breaking is separated by high-speed centrifugal force to achieve preliminary defatting, significantly reducing the oil holding capacity of the adsorbent, thereby reducing the processing load of the subsequent enzymolysis process. Specifically, the main equipment can use a horizontal centrifuge, which has a maximum speed of 12000 rpm, a drum diameter of 500 mm, an effective volume of 20 L, and is equipped with 4 fan-shaped material pockets. The 4 fan-shaped material pockets are symmetrically distributed with an included angle of 90°, and the drum is made of 316L stainless steel. The filter assembly can be customized with 500-800 mesh nylon cloth pockets. Before loading the oil-containing adsorbent, the nylon cloth pockets are soaked in 40~60℃ deionized water for 10~20 minutes to reduce the adsorption of oil by the nylon cloth pockets. In addition, a weight sensor can be installed at the bottom of each material pocket, connected to an automatic feeding device to ensure that the weight difference between the sectors is ≤0.5%. Step 2 can be implemented through the following process: S21: Load the crushed oil-containing adsorbent into the nylon cloth pocket and use a mechanical compactor to compact it to ensure that the thickness of each material pocket meets the preset thickness; In this step, the oil-agent mixture after breaking the wall is specifically filled into a nylon cloth pocket, and a mechanical compactor is used for compaction, the pressure of the mechanical compactor is 5 MPa, the pressure is maintained for 30 seconds, the thickness of the material pocket is controlled to be 100-120 mm, and local material loosening during centrifugation is avoided.

[0027] S22: The material pockets are symmetrically placed in the four sectors of the centrifuge drum, and the weight deviation of the material pockets filled in each sector is not greater than 0.5%.

[0028] In this step, considering that the material pockets are placed in the four sectors of the centrifuge group, the weight sensor detects the weight of each material pocket in real time, if the weight difference is greater than 0.3%, manual supplement or automatic start of the micro screw conveyor is performed until the weight difference between the sectors is less than or equal to 0.5%.

[0029] S23: Control the high-speed centrifuge to work according to the preset process parameters to preliminarily separate the oil in the material pocket.

[0030] In this step, the preset process parameters are: under normal temperature conditions, the speed of the high-speed centrifuge is 8000-10000 rpm, and the processing time is 5-10 minutes; under low temperature conditions, the temperature of the material pocket is raised to 25-35°C by starting the electric heating jacket of the high-speed centrifuge, the speed of the high-speed centrifuge is 8000-10000 rpm, and the processing time is 4-8 minutes. For example, under normal temperature conditions (generally 25-30°C), the speed is set to 9000 rpm and the processing time is 7 minutes; under low temperature conditions (generally <10°C), the temperature of the material pocket is raised to 35-40°C by starting the electric heating jacket of the centrifuge, the speed is kept at 9000 rpm, and the processing time is shortened to 5 minutes to reduce the viscosity of the oil by raising the temperature. After separation, the oil outside the nylon cloth pocket is collected for refining, and the oil-adsorbent material pocket is taken out for subsequent enzymatic hydrolysis.

[0031] In step 2, during centrifugal separation, the centrifugal force generated by high-speed centrifugation makes the oil overcome the surface tension of the adsorbent and be thrown out of the cloth pores to form an oil film on the inner wall of the drum and gather into a flow. Specifically, the inner wall of the horizontal centrifuge drum is provided with a spiral oil guide groove, the end of the oil guide groove is connected with a polytetrafluoroethylene oil guide pipe, and the outlet of the oil guide pipe is connected with a vacuum dewatering device. During centrifugation, the thrown-out oil flows along the oil guide groove, enters the vacuum dewatering device through the oil guide pipe, and removes water in a negative pressure environment to avoid interference of water in subsequent enzymatic hydrolysis. The dewatered oil flows into a refining pre-storage tank through a pipeline; after centrifugation, compressed air is used to blow the inner wall of the drum to blow the residual oil into the oil guide groove, thereby improving the recovery rate.

[0032] Therefore, the weight difference of the four fan-shaped material packs in step 2 is less than or equal to 0.5%, and the dynamic balance compensation mechanism is used to effectively reduce the vibration of the centrifuge when it operates at a high speed of 8000-10000 rpm, the service life of the equipment is longer than that of the traditional centrifugal method, and the uneven separation of oil caused by vibration is avoided. Moreover, for low-temperature conditions (<10℃), the centrifugal environment temperature is increased to 25-35℃ by an electric heating jacket, the oil viscosity is significantly reduced, the fluidity is significantly improved, the centrifugation time is effectively reduced, and the oil holding capacity of the adsorbent after primary degreasing is also significantly reduced, and the degreasing efficiency is improved compared with the traditional centrifugal method.

[0033] For step 3, the oil-containing adsorbent material pack after centrifugal separation is subjected to enzymatic impregnation with a demulsification enzyme preparation to destroy the physical-chemical adsorption interface between the oil and the adsorbent and promote the release of non-polar oil; wherein the demulsification enzyme preparation comprises lipase, phospholipase, polyglycerol ester and enzyme stabilizer.

[0034] In this step, the biological degradation of the composite demulsification enzyme preparation is used to destroy the physical-chemical adsorption interface between the oil and the adsorbent, reduce the binding energy, promote the release of non-polar oil, and improve the degreasing efficiency of subsequent pressing. Specifically, step 3 can be realized by the following ways: S31: The oil-containing adsorbent material pack after centrifugal separation is put into an enzymatic impregnation tank containing 50-60℃ deionized water; S32: Adding a demulsification enzyme preparation to the enzymatic impregnation tank; wherein the demulsification enzyme preparation comprises: lipase 45-55%, phospholipase 25-35%, polyglycerol ester with HLB value of 12-14 15-20% and enzyme stabilizer (trehalose) 5-10%; S33: The solid-liquid mixture in the enzymatic impregnation tank is stirred by using a segmented stirring strategy to promote the destruction of the oil-adsorbent interface and release non-polar oil.

[0035] In this step, the segmented stirring can be divided into two stages. In the first stage, the stirring speed is 40-50 rpm for 10-14 hours to promote the contact between the demulsification enzyme preparation and the oil-containing adsorbent; in the second stage, the stirring speed is 20-30 rpm for 22-26 hours to avoid excessive stirring leading to the failure of the demulsification enzyme preparation; in the third stage, the stirring speed is 40-50 rpm for 10-14 hours to disperse the enzymatic products.

[0036] The principle of recovering oil and fat in step 3 is that after the enzyme hydrolysis reaction destroys the oil-adsorbent interface, the oil and fat is released from the surface of the adsorbent into the immersion liquid to form an oil-in-water emulsion, and the oil and fat is recovered by demulsification and solid-liquid separation. Specifically, after the enzyme hydrolysis is completed, the adsorbent-emulsion mixture can be pumped into an electric demulsification device, and under the action of a high-voltage electric field, the oil droplets in the emulsion coalesce. The mixed liquid after demulsification enters a disc separator, and under the action of centrifugal force, it is divided into three layers: the upper layer of oil and fat, the middle layer of aqueous phase, and the lower layer of adsorbent particles. The upper layer of oil and fat enters the oil and fat collection tank through the overflow port, and the middle layer of aqueous phase containing enzyme preparation is pumped back to the enzyme hydrolysis tank for recycling. The wet adsorbent discharged from the separator is sent to a plate and frame filter to further filter out residual oil and fat.

[0037] In this step, the composite demulsification enzyme preparation can reduce the oil-adsorbent interfacial tension, and the synergistic effect of each component can significantly reduce the oil-adsorbent binding energy, thereby improving the release rate of non-polar oil and fat, and significantly enhancing the degreasing efficiency. Moreover, in this scheme, high-speed stirring for the first 12 hours promotes enzyme-substrate contact, low-speed stirring for the next 24 hours prevents enzyme deactivation, and the last 12 hours of high-speed stirring disperses the product. Combined with trehalose as an enzyme stabilizer, the enzyme activity retention rate can be significantly improved, which helps to shorten the enzyme hydrolysis time and improve the production efficiency.

[0038] Step 4: The oil-containing adsorbent after enzyme hydrolysis immersion is pressed based on multi-stage gradient pressure to deeply degrease the oil-containing adsorbent; wherein temperature control is provided during the pressing process to reduce the viscosity of the oil and fat and promote the flow of the oil and fat.

[0039] In this step, the purpose is to deeply degrease the oil-containing adsorbent after enzyme hydrolysis by multi-stage gradient pressure pressing with temperature control, to effectively reduce the residual oil rate in the adsorbent. Specifically, step 4 can be divided into four stages for pressing operation, including: First stage: control the press to slowly rise from 0 to 20 MPa within 1-2 hours to press the oil-containing adsorbent after enzyme hydrolysis immersion, and at the same time, control the oil-containing adsorbent to slowly rise to 40±1℃ by the temperature control device in the first stage; Second stage: control the press to slowly rise from 20 MPa to 40 MPa within 7-8 hours to press the oil-containing adsorbent after enzyme hydrolysis immersion, and at the same time, control the oil-containing adsorbent to slowly rise to 50±1℃ by the temperature control device in the second stage; Third stage: control the press to slowly rise from 40 MPa to 60 MPa within 7-10 hours to press the oil-containing adsorbent after enzyme hydrolysis immersion, and at the same time, control the oil-containing adsorbent to slowly rise to 60±1℃ by the temperature control device in the third stage; Fourth stage: control the press to slowly release from 60 MPa to 0 within 1-2 hours, and at the same time, stop the temperature control device in the fourth stage to allow the oil-containing adsorbent to cool naturally.

[0040] In this embodiment, the surfaces of the opposing rollers of the press are treated with nano-level polishing and sprayed with a polytetrafluoroethylene coating to reduce the adhesion of adsorbent particles.

[0041] In step 4, the adsorbent pores are gradually contracted by gradient pressure extrusion, and the oil is squeezed out and forms an oil film on the surface of the opposing rollers, which is collected by the oil scraping device. Specifically, during the pressing process, the oil on the surface of the opposing rollers is continuously scraped off by the oil scraping plate and flows into the oil collection tank, converges along the inclined tank bottom to the end pipeline. The oil enters the heated settling tank through the pipeline, and a small amount of solid impurities is settled to the bottom of the tank by using the density difference, and the drain valve is opened regularly to discharge the impurities. The settled oil is filtered through a precision filter to remove trace amounts of suspended particles, and finally sent to the refining process storage tank.

[0042] In this step, the adsorbent voids are gradually compressed by controlling the gradient pressure, which can avoid the collapse of the voids caused by sudden pressure rise compared to the traditional pressing method, and reduce the oil retention. Moreover, by coating the surface of the rollers with ceramic and polytetrafluoroethylene, the adhesion of the adsorbent is significantly reduced, reducing the loss of oil with the adsorbent.

[0043] Of course, in some embodiments, step 4 can also be divided into more stages for pressing control, further refining the pressure change range of each stage, such as using 60MPa as the maximum pressure limit, and increasing the pressure by 5MPa gradient change value, which can further reduce the residual oil content in the adsorbent.

[0044] In addition, for the temperature control equipment, the press can be equipped with a closed heating and insulation device made of canvas with a metal skeleton, such as a heating blanket, which can surround the main body of the press. Through the built-in heating components and insulation measures, it can ensure that the pressed adsorbent is at the target working temperature. For the heating and insulation device, it can be integrated with a coiled heating wire and a steam pipe inside. When there is excess steam, steam is introduced through the pipe to achieve heating; when there is no excess steam, the heating wire can be switched on to heat. The two methods can be flexibly combined to ensure heat supply. For the heating device, considering the natural loss in the process of heat conduction, the final temperature transmitted to the adsorbent can reach 60℃, so the rated heating temperature should be at least 70℃ to meet the process requirements and make rational use of the temperature conduction law. Further, the outside of the heating device can be wrapped with insulation cotton to effectively reduce heat loss to the outside world, maintain stable internal temperature, and reduce energy consumption. At the same time, temperature measuring modules should be installed inside the device to monitor the temperature of the heating area in real time, provide data basis for heat source switching and temperature adjustment, and ensure temperature control accuracy. Of course, in the cold season in the north, actual temperature control should also effectively combine the heating capacity of indoor heating to control the temperature. For example, the target temperature can be achieved by increasing the heating temperature or reducing the heating temperature in combination with the heating device.

[0045] In order to facilitate the operator to check, maintain and take and place materials in the inside of the press, the enclosed heating and temperature maintaining device should be provided with a small door which can be opened and closed, so that the temperature maintaining effect can be ensured and the operation convenience is considered.

[0046] Of course, quality control and monitoring should also be carried out during the generation process. For example, 3-5 samples are randomly taken from each batch, and the residual oil rate is detected. If the residual oil rate is greater than 8%, the process parameters are adjusted. Regularly check the key parts of the equipment, such as the wear of the wall breaking machine cutter, the pressure deviation of the press roller, and replace them in time. For demulsification enzyme preparation, the content of each batch is detected to ensure that the lipase and other components are within the specified range.

[0047] The modules or units in the device of the embodiments of the application can be combined, divided, and deleted according to actual needs. The above disclosed is only the preferred embodiments of the application, and of course cannot limit the scope of the rights of the application. Those skilled in the art can understand that all or part of the processes of the above embodiments are implemented, and equivalent changes made according to the claims of the application still belong to the scope covered by the application.

Claims

1. A method for recovering residual oil from an adsorbent used in flaxseed oil production, characterized in that, Includes the following steps: Step 1: Use a high-speed blender to break down the oil-containing adsorbent, thereby destroying its porous structure and releasing the free oil encapsulated in the micropores and mesopores. Step 2: Use a high-speed centrifuge to centrifuge the crushed adsorbent to initially separate the oils from the adsorbent; Step 3: The oil-containing adsorbent package after centrifugation is enzymatically impregnated with a demulsifying enzyme preparation to disrupt the physicochemical adsorption interface between the oil and the adsorbent and promote the release of non-polar oil; wherein the demulsifying enzyme preparation contains lipase, phospholipase, polyglycerol ester and enzyme stabilizer. Step 4: Press the enzymatically hydrolyzed oil-containing adsorbent using multi-stage gradient pressure to deeply degrease it; during the pressing process, temperature control is used to reduce oil viscosity and promote oil outflow.

2. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 1, characterized in that, In step 1, the blender uses a titanium alloy blade assembly with a surface hardness of not less than HRC60, the blender speed is 18000~22000rpm, the blade linear speed is not less than 150m / s, and the breakage treatment time meets the requirement that the adsorbent particles after the breakage treatment are not larger than 30μm.

3. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 1, characterized in that, The temperature of the oil-containing adsorbent is monitored in real time during the crushing process. The crushing process is stopped when the temperature exceeds the first preset temperature threshold. The oil-containing adsorbent is then cooled to room temperature before the crushing process is repeated to avoid the expansion of the entrained air due to the temperature rise, which would affect the crushing process.

4. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 1, characterized in that, Step 2 specifically includes: S21: The crushed oil-containing absorbent is packed into nylon-lined bags and compacted using a mechanical compactor to ensure that the thickness of each bag meets the preset thickness. S22: The material bags are placed symmetrically in the four sectors of the centrifuge drum, and the weight deviation of the material bags in each sector is no more than 0.5%; S23: Control the high-speed centrifuge to operate according to the preset process parameters in order to initially separate the grease in the material package.

5. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 4, characterized in that, In step S21, the nylon cloth bag has a mesh size of 500-800. Before filling the nylon cloth bag with the oil absorbent, it is soaked in deionized water at 40-60°C for 10-20 minutes to reduce the nylon cloth bag's adsorption of oil. The preset thickness is 100-120mm.

6. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 4, characterized in that, The preset process parameters in step S23 are as follows: under normal temperature conditions, the speed of the high-speed centrifuge is 8000~10000 rpm, and the processing time is 5~10 min; under low temperature conditions, the electric heating jacket of the high-speed centrifuge is started to raise the temperature of the material bag to 25~35℃, the speed of the high-speed centrifuge is 8000~10000 rpm, and the processing time is 4~8 min.

7. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 1, characterized in that, Step 3 specifically includes: S31: The oil-containing adsorbent package after centrifugation is put into an enzymatic hydrolysis impregnation tank containing deionized water at 50~60℃; S32: Add a demulsifying enzyme preparation to the enzymatic hydrolysis impregnation tank; wherein the demulsifying enzyme preparation comprises: 45-55% lipase, 25-35% phospholipase, 15-20% polyglycerol ester with an HLB value of 12-14, and 5-10% enzyme stabilizer; S33: A segmented stirring strategy is adopted to stir the solid-liquid mixture in the enzymatic hydrolysis impregnation tank to promote the destruction of the oil-agent interface and release non-polar oils.

8. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 7, characterized in that, The staged stirring strategy includes: in the first stage, stirring at 40-50 rpm for 10-14 hours to promote contact between the demulsifying enzyme preparation and the oil-containing adsorbent; in the second stage, stirring at 20-30 rpm for 22-26 hours to avoid over-stirring and causing the demulsifying enzyme preparation to become ineffective; and in the third stage, stirring at 40-50 rpm for 10-14 hours to disperse the enzymatic hydrolysis products.

9. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 1, characterized in that, Step 4 specifically includes: First stage: Control the press to slowly increase from 0 to 20MPa in 1-2 hours to press the oil-containing adsorbent after enzymatic hydrolysis and impregnation. At the same time, the temperature control equipment controls the oil-containing adsorbent to slowly increase the temperature to 40±1℃ in the first stage. Second stage: Control the press to slowly increase from 20MPa to 40MPa over 7-8 hours to press the oil-containing adsorbent after enzymatic hydrolysis and impregnation. At the same time, the temperature control equipment controls the oil-containing adsorbent to slowly increase the temperature to 50±1℃ during the second stage. The third stage: The press is controlled to slowly increase from 40MPa to 60MPa over 7-10 hours to press the oil-containing adsorbent after enzymatic hydrolysis and impregnation. At the same time, the temperature of the oil-containing adsorbent is slowly increased to 60±1℃ by temperature control equipment during the third stage. Fourth stage: Control the press to slowly depressurize from 60MPa to 0 within 1-2 hours. At the same time, stop the temperature control equipment in the fourth stage to allow the oil adsorbent to cool naturally.

10. The method for recovering residual oil from the adsorbent used in flaxseed oil production according to claim 9, characterized in that, The surfaces of the rollers of the press are polished at the nanoscale and coated with a polytetrafluoroethylene coating to reduce the adhesion of adsorbent particles.

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