A purification membrane refining device for edible oil production

Abstract

The present application relates to the technical field of edible oil refining, and particularly relates to a purification membrane refining equipment for edible oil production, which comprises a pretreatment unit, a membrane separation unit, a membrane cleaning unit, a blowdown unit, a finished oil unit, a heat recovery unit and a central control unit. The edible oil is filtered and separated by the purification membrane, the automatic one-stop physical refining of the edible oil is realized, the problem of edible oil production is effectively solved, the whole process is low-temperature physical treatment, the use of chemical reagents is reduced, the nutritional ingredients are retained, the purification membrane is online washed, the central control unit is determined according to the real-time oil flow and the real-time oil temperature, the oil supply pressure is accurately controlled, the continuous and stable operation of the membrane separation unit is ensured, the pressure difference between the two sides of the purification membrane module is determined to start blowdown or cleaning, the purification membrane module can effectively maintain the membrane flux for a long time, and the purification membrane separation and filtering refining of the edible oil with large batch continuous production is realized.

Description

Technical Field

[0001] This invention relates to the field of edible oil refining technology, and in particular to a purification membrane refining device for edible oil production. Background Technology

[0002] Traditional edible oil refining processes typically include steps such as degumming, deacidification, decolorization, and deodorization. These processes are mostly intermittent operations, involving the use of chemical auxiliaries and adsorbents such as phosphoric acid, caustic soda, bleaching clay, and activated carbon, and are carried out under high temperature and high vacuum conditions. Traditional processes have the following inherent disadvantages: 1. High chemical consumption, using large amounts of acids, alkalis, and bleaching clay, leading to high production costs; 2. High oil loss, with neutral oil being lost due to saponification and entrainment during neutralization, adsorption, and subsequent separation processes, resulting in reduced yield; 3. Destruction of nutritional components, as high-temperature treatment destroys the natural active ingredients in the oil, such as vitamin E, sterols, and polyphenols; 4. Environmental pollution, generating large amounts of wastewater, waste bleaching clay, and other solid waste, which are difficult to treat and place a heavy burden on environmental protection; 5. Long process flow, numerous pieces of equipment, complex operation, and high energy consumption.

[0003] Membrane separation technology, as an emerging physical separation method, has been explored for application in the oil and fat industry. It utilizes the selective sieving effect of the membrane pores of the purification membrane to separate different components at the molecular level. It has advantages such as no phase change, low energy consumption, no chemical additives, and mild conditions. Currently, some studies have attempted to use oil purification membranes for degumming. However, directly applying membrane technology to industrial edible oil refining still faces challenges.

[0004] Membrane fouling and flux decline: Crude oil has a complex composition, and substances such as gums, phospholipids, dehazing agents, impurities, and dehydration agents can easily form a gel layer on the membrane surface, leading to a rapid decline in membrane flux and low production efficiency.

[0005] Poor process integration: Most studies only cover a single membrane process, such as degumming, and have failed to form a complete integrated membrane system to replace the traditional multi-step refining process.

[0006] High pretreatment requirements: Direct filtration of crude oil can easily cause membrane clogging, and there is a lack of efficient and reliable pretreatment units.

[0007] System energy efficiency: Although the membrane process is carried out at room temperature, the feed may require a certain temperature to reduce viscosity, and the system lacks effective energy recovery and integrated design.

[0008] Chinese Patent Publication No. CN203513643U discloses a multi-stage continuous membrane separation and purification device for oil products. Its technical point is to set up a series-connected microfiltration membrane treatment unit and an ultrafiltration membrane treatment unit for secondary filtration and purification, and to use solvent assistance to modify the hydrophilic membrane into a hydrophobic membrane to increase the flow rate. However, the crude oil actually contains a lot of impurities and has a high viscosity at low temperatures. Refining the crude oil through the purification membrane can easily cause membrane blockage, resulting in low overall refining efficiency of edible oil and making it unsuitable for large-scale continuous edible oil production. Summary of the Invention

[0009] Therefore, the present invention provides a purification membrane refining device for edible oil production, which overcomes the problems of low efficiency in crude oil refining and inability to achieve large-scale continuous production due to easy clogging of the membrane in the production of edible oil by existing purification membranes.

[0010] To achieve the above objectives, the present invention provides a purification membrane refining device for edible oil production, comprising:

[0011] The pretreatment unit is used to receive and pre-treat crude oil, including pre-filtration and preheating of the crude oil.

[0012] The membrane separation unit includes a circulating oil tank for receiving crude oil, a purification membrane module for membrane filtration of crude oil, and a working sewage pump for conveying crude oil from the circulating oil tank to the purification membrane module.

[0013] A membrane cleaning unit, which is connected to the membrane separation unit, is used to clean the membrane separation unit online;

[0014] The sewage discharge unit is connected to the filtration side of the purification membrane module and is used to discharge the concentrated oil from the filtration membrane module.

[0015] The central control unit is connected to the pretreatment unit, membrane separation unit, membrane cleaning unit and sewage discharge unit respectively. The central control unit can obtain the real-time oil flow rate on the permeate side of the purification membrane module and the real-time oil temperature in the circulating oil tank. When the real-time oil flow rate is lower than the standard oil flow rate range and the real-time oil temperature is lower than the standard oil temperature, the initial heating temperature of the heating layer in the circulating oil tank is adjusted.

[0016] When the real-time oil flow rate is lower than the standard oil flow rate range and the real-time oil temperature is higher than the standard oil temperature, the central control unit obtains the real-time inlet pressure and real-time outlet pressure on both sides of the purification membrane module, calculates the real-time filtration pressure difference, and adjusts the impeller speed of the working sewage pump, or starts the membrane cleaning unit, or starts the sewage discharge unit based on the determination of the real-time filtration pressure difference.

[0017] Furthermore, the central control unit is equipped with a standard oil flow range consisting of a standard oil flow rate and a standard oil flow rate difference. The central control unit calculates the absolute value of the difference between the real-time oil flow rate and the standard oil flow rate as the real-time oil flow rate difference. When the real-time oil flow rate difference is greater than the standard oil flow rate difference, it is determined that the real-time oil flow rate is not within the standard oil flow rate range. Based on the comparison between the real-time oil flow rate and the standard oil flow rate, it is determined whether the real-time oil flow rate is lower or higher than the standard oil flow rate range.

[0018] Furthermore, the central control unit can reduce the impeller speed of the working sewage pump when the real-time oil flow rate is higher than the standard oil flow rate range, Ng1=Ng×[1-(Ls-Lb) / Lb];

[0019] Where Ng is the impeller speed of the working sewage pump before adjustment, Ng1 is the impeller speed of the working sewage pump after adjustment, Ls is the real-time oil flow rate, and Lb is the standard oil flow rate.

[0020] Furthermore, the central control unit can increase the initial heating temperature of the heating layer when the real-time oil flow rate is lower than the standard oil flow rate range and the real-time oil temperature is lower than the standard oil temperature, Tj1=Tj×(Tb / Ts).

[0021] Where Tj is the initial heating temperature of the heating layer, Tj1 is the adjusted heating temperature of the heating layer, Tb is the standard oil temperature, and Ts is the real-time oil temperature.

[0022] Furthermore, the central control unit is also equipped with a first filtration pressure difference. When the real-time oil flow rate is lower than the standard oil flow rate range and the real-time oil temperature is higher than the standard oil temperature, the central control unit obtains the real-time oil inlet pressure and real-time oil outlet pressure on both sides of the purification membrane module, calculates the real-time filtration pressure difference, and controls the increase of the impeller speed of the working sewage pump when the real-time filtration pressure difference is less than the first filtration pressure difference.

[0023] Furthermore, the central control unit is also equipped with a second filtration pressure difference, which is greater than the first filtration pressure difference. When the central control unit determines that the real-time filtration pressure difference is between the first filtration pressure difference and the second filtration pressure difference, it controls the sewage discharge unit to start sewage discharge.

[0024] When the central control unit determines that the real-time filtration pressure difference is greater than the second filtration pressure difference, it controls the membrane cleaning unit to start cleaning.

[0025] Furthermore, the pretreatment unit includes a raw material tank for storing crude oil, which is connected to a pre-filter via a preheating pipe. A feed pump is provided on one side of the pre-filter to transport the pre-filtered crude oil to the circulating tank of the membrane separation unit.

[0026] Furthermore, the purification membrane module includes an ultrafiltration-level purification membrane group and a nanofiltration-level purification membrane group connected in series. Both the ultrafiltration-level purification membrane group and the nanofiltration-level purification membrane group are organic purification membranes, including but not limited to PTFE membranes, PP membranes, PE membranes and PVDF membranes.

[0027] The circulating oil tank is equipped with a heating layer for heating and a temperature sensor for detecting the real-time oil temperature;

[0028] An oil inlet valve is installed on one side of the circulating oil tank, a working sewage pump is installed on one side of the oil inlet valve, and a feed valve is installed on one side of the working sewage pump. The feed valve is connected to the interception side of the ultrafiltration stage purification membrane module.

[0029] The permeation side of the ultrafiltration-grade purification membrane module is connected to the circulation valve and the nanofiltration-grade purification membrane module, respectively. A reflux valve is installed on one side of the circulation valve, and the reflux valve is connected to the circulation oil tank through a pipeline.

[0030] The ultrafiltration-grade purification membrane module is equipped with a first pressure sensor on the retention side and a second pressure sensor on the permeation side, while the nanofiltration-grade purification membrane module is equipped with a third pressure sensor on the permeation side.

[0031] Furthermore, the membrane cleaning unit includes a backwash pump and an external air source. A backwash valve is installed on one side of the backwash pump and is connected to the permeate side of the nanofiltration-grade purification membrane module. An air washing valve is installed on the side of the external air source and is also connected to the permeate side of the nanofiltration-grade purification membrane module.

[0032] The wastewater discharge unit includes a wastewater discharge valve located on the interception side of the ultrafiltration-stage purification membrane module, a working wastewater discharge pump connected to the wastewater discharge valve, a waste oil valve located on one side of the working wastewater discharge pump, and a concentrated oil tank located on one side of the waste oil valve; wherein, the wastewater discharge unit and the membrane separation unit share the working wastewater discharge pump.

[0033] Furthermore, it also includes a refined oil processing unit and a heat recovery unit;

[0034] The finished oil unit includes a finished oil tank, which is connected to the permeate side of the nanofiltration-grade purification membrane module via a pipeline, and the pipeline is equipped with a finished oil flow meter and an oil production valve; a transfer backwash pump is also installed on one side of the finished oil tank, and a transfer valve is installed on the other side of the transfer backwash pump, which is connected to the storage tank; the finished oil unit and the membrane cleaning unit share the transfer backwash pump.

[0035] The heat recovery unit includes a heat exchanger installed on one side of the preheating pipe, a circulation pipe connected to the heat exchanger and the concentrated oil tank respectively, and a heat pump installed on the circulation pipe.

[0036] Compared with existing technologies, the advantages of this invention are as follows: by using a membrane separation unit to filter edible oil through a purification membrane, the edible oil is effectively dehazed, achieving one-stop physical refining of edible oil. This eliminates the generation of waste acid, alkali, and waste bleaching clay from the source. At the same time, the physical separation process avoids the saponification loss of neutral oil, significantly increasing the oil yield. The gentle operating conditions preserve the natural nutrients and flavor of the oil to the greatest extent. By setting up a central control unit to determine parameters such as real-time oil flow and real-time oil temperature, the supply pressure is precisely controlled to ensure a stable output of edible oil separation and refining. By determining the pressure difference on both sides of the purification membrane module, the invention initiates sewage discharge or cleaning, overcoming the problem of unstable membrane flux caused by easy clogging of traditional purification membranes. Through intelligent self-cleaning, the purification membrane module is ensured to maintain membrane flux effectively for a long time, realizing the purification membrane separation and refining of edible oil for large-scale continuous production.

[0037] Furthermore, the preheating pipes and pre-filters effectively remove solid suspended impurities from the crude oil, preventing clogging of the purification membrane module. Simultaneously, the preheating pipes increase the crude oil temperature, and a heating layer within the circulating oil tank ensures stable temperature and improved fluidity, facilitating easier passage through the purification membrane module. By configuring the purification membrane module as a series connection of ultrafiltration and nanofiltration membrane groups, graded filtration of the crude oil is achieved, catering to different oil refining needs. A circulation valve on the permeate side of the ultrafiltration membrane group allows the crude oil passing through it to flow back to the circulating oil tank, enabling multiple circulation filtrations to meet various degumming requirements and enhancing the applicability of the refining equipment. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the system framework of the purification membrane refining equipment used in edible oil production according to this embodiment;

[0039] Figure 2 This is a schematic diagram of the pipeline structure of the purification membrane refining equipment used in edible oil production according to this embodiment;

[0040] Figure 3 This is a logic diagram of the flow and temperature determination of the control unit in this embodiment;

[0041] Figure 4 This is the logic diagram for determining the pressure difference of the control unit in this embodiment.

[0042] Attached Figure Descriptions: 101. Raw material tank; 102. Preheating pipe; 103. Pre-filter; 104. Feed pump; 201. Circulating oil tank; 202. Oil inlet valve; 203. Working sewage pump; 204. Feed valve; 205. Ultrafiltration membrane module; 206. Circulation valve; 207. Nanofiltration membrane module; 208. Return valve; 301. Finished oil flow meter; 302. Oil production valve; 30 3. Finished oil tank; 304. Conveying backwash pump; 305. Conveying valve; 306. Storage oil tank; 401. Backwash valve; 402. Cleaning flow meter; 403. External air source; 404. Float flow meter; 405. Air washing valve; 501. Drain valve; 502. Sewage valve; 503. Waste oil valve; 504. Concentrated oil tank; 601. Heat exchanger; 602. Circulation pipeline; 603. Heat exchange pump. Detailed Implementation

[0043] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0044] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0045] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0046] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] Please see Figure 1 As shown, this is a schematic diagram of the system framework of the purification membrane refining equipment for edible oil production according to this embodiment. This embodiment provides a purification membrane refining equipment for edible oil production, including...

[0048] The pretreatment unit is used to receive and pre-treat crude oil, including pre-filtration and preheating of the crude oil.

[0049] A membrane separation unit, connected to the pretreatment unit, is used to perform membrane filtration on the crude oil that has undergone preliminary treatment.

[0050] The finished oil unit is located on the permeate side of the membrane separation unit and is used to transport or store the finished oil on the permeate side of the membrane separation unit.

[0051] A membrane cleaning unit, which is connected to the membrane separation unit, is used to clean the membrane separation unit online;

[0052] The blowdown unit, which is connected to the membrane separation unit, is used to discharge and store the concentrated oil from the retrieval side of the membrane separation unit;

[0053] The heat recovery unit is connected to the sewage discharge unit and the pretreatment unit respectively, and is used to transport the concentrated sewage oil stored in the sewage discharge unit to the pretreatment unit to preheat the crude oil.

[0054] The central control unit is connected to the pretreatment unit, membrane separation unit, finished oil unit, membrane cleaning unit, sewage discharge unit, and heat recovery unit, respectively, and is used to control the operating status of each unit.

[0055] The purification membrane refining equipment in this embodiment can process crude oil and semi-finished oil of various edible oils, covering common vegetable oils such as peanut oil, sesame oil, and rapeseed oil.

[0056] Please continue reading. Figure 2 As shown, it is a schematic diagram of the pipeline structure of the purification membrane refining equipment used in edible oil production in this embodiment;

[0057] Specifically, the pretreatment unit includes a raw oil tank 101 for storing crude oil. The raw oil tank 101 is connected to a pre-filter 103 via a preheating pipe 102. The crude oil flowing through the preheating pipe 102 is preheated, then pre-filtered by the pre-filter 103, and finally transported to the membrane separation unit by a feed pump 104.

[0058] In this embodiment, the pre-filter 103 can be a bag filter or a cartridge filter, with a precision selection range of 5μm-25μm. After pre-filtration, solid suspended impurities in the crude oil are removed, making it easier to process. At the same time, preheating the crude oil is also to ensure the fluidity of the crude oil, which is convenient for membrane filtration.

[0059] Specifically, the membrane separation unit includes a purification membrane module and a circulating oil tank 201. The purification membrane module includes an ultrafiltration-stage purification membrane group 205 and a nanofiltration-stage purification membrane group 207 connected in series. The circulating oil tank 201 is connected to the feed pump 104. The circulating oil tank 201 is used to receive and store preheated and pre-filtered crude oil. A heating layer is provided inside the circulating oil tank 201 to heat the oil inside. A temperature sensor is also provided inside the circulating oil tank 201 to detect the real-time oil temperature. One side of the circulating oil tank 201 is connected to... The pipeline is connected to the oil inlet valve 202. One side of the oil inlet valve 202 is connected to the working sewage pump 203 through a pipeline. The working sewage pump 203 is connected to the feed valve 204 through a pipeline. The feed valve 204 is connected to the interception side of the ultrafiltration membrane module 205 through a pipeline. When filtering crude oil through the ultrafiltration membrane module 205, the oil inlet valve 202 on the circulating oil tank 201 side and the feed valve 204 on the ultrafiltration membrane module 205 side are opened, and the working sewage pump 203 is started to transport the crude oil in the circulating oil tank 201 to the ultrafiltration membrane module 205 for filtration.

[0060] The permeate side of the ultrafiltration membrane module 205 is connected to the circulation valve 206 and the nanofiltration membrane module 207, respectively. The circulation valve 206 is connected to the return valve 208 through a pipeline, and the return valve 208 is connected to the circulating oil tank 201 through a pipeline. When the circulation valve 206 and the return valve 208 are open, the filtered crude oil discharged from the permeate side of the ultrafiltration membrane module 205 flows back to the circulating oil tank 201 through the circulation valve 206 and the return valve 208, which can realize multiple filtration of crude oil using the ultrafiltration membrane module 205. When multiple filtration of crude oil is not required, both the circulation valve 206 and the return valve 208 are closed, and the filtered crude oil discharged from the permeate side of the ultrafiltration membrane module 205 enters the nanofiltration membrane module 207 for filtration through a pipeline.

[0061] In this embodiment, a first pressure sensor is provided on the retention side of the ultrafiltration-stage purification membrane module 205, a second pressure sensor is provided on the permeation side of the ultrafiltration-stage purification membrane module 205, and a third pressure sensor is provided on the permeation side of the nanofiltration-stage purification membrane module 207. By detecting the pressure conditions on both sides of the ultrafiltration-stage purification membrane module 205 and the nanofiltration-stage purification membrane module 207, the real-time membrane flux status of the ultrafiltration-stage purification membrane module 205 and the nanofiltration-stage purification membrane module 207 can be determined, and the cleaning step can be connected in a timely manner to ensure the long-term continuous production of the purification membrane refining equipment.

[0062] This embodiment uses an ultrafiltration-grade membrane module 205 and a nanofiltration-grade membrane module 207 connected in series to perform secondary filtration of crude oil. Specifically, the ultrafiltration-grade membrane module 205 is equipped with an ultrafiltration-grade oil purification membrane with a molecular weight cutoff of 10,000 Da-50,000 Da. In this embodiment, an MWCO of 20,000 Da is selected, and the operating temperature is 60°C. This membrane is used to remove phospholipids, colloids, and some large molecular weight proteins. The nanofiltration-grade membrane module 207 is equipped with a nanofiltration-grade oil purification membrane with a molecular weight cutoff of 200 Da-1,000 Da. In this embodiment, an MWCO of 400 Da is selected, and the operating temperature is 50°C. This membrane is used to remove free fatty acids (FFA), small molecule pigments, aldehyde and ketone oxides, and residual solvents.

[0063] The ultrafiltration-grade oil purification membrane and nanofiltration-grade oil purification membrane used in this embodiment are both organic purification membranes, including but not limited to PTFE membranes, PP membranes, PE membranes, and PVDF membranes. By using organic purification membranes for filtration, trace amounts of waxy components in edible oil can also be effectively removed. Since waxy components have a high melting point, they will crystallize at low temperatures, affecting the transparency of edible oil and causing it to become hazy. Therefore, filtration through organic purification membranes can effectively remove haze from edible oil.

[0064] Specifically, the finished oil unit includes a finished oil tank 303, which is connected to the permeation side of the nanofiltration-grade purification membrane module 207 via a pipeline. At the same time, a finished oil flow meter 301 and an oil production valve 302 are installed on the pipeline. When the oil production valve 302 is opened, the finished oil discharged from the permeation side of the nanofiltration-grade purification membrane module 207 enters the finished oil tank 303 through the pipeline.

[0065] Meanwhile, a conveying backwash pump 304 is also installed on one side of the finished oil tank 303. The conveying backwash pump 304 is connected to the conveying valve 305 through a pipeline. The conveying valve 305 is connected to the storage oil tank 306 through a pipeline. By opening the conveying valve 305 and starting the conveying backwash pump 304, the finished oil in the finished oil tank 303 can be conveyed to the storage oil tank 306 for storage, thus completing the production and refining of edible oil.

[0066] Specifically, the membrane cleaning unit includes a backwash pump 304, which is connected to a backwash valve 401 via a pipeline. The backwash valve 401 is connected to the permeate side of the nanofiltration-grade membrane module 207 via a pipeline, and a cleaning flow meter 402 is installed on the pipeline. When cleaning the ultrafiltration-grade membrane module 205 and the nanofiltration-grade membrane module 207, the backwash valve 401 is opened, the delivery valve 305 and the circulation valve 206 are kept closed, and the backwash pump 304 is started to deliver the cleaning solution to the permeate side of the nanofiltration-grade membrane module 207 for backwashing.

[0067] The membrane cleaning unit also includes an air washing valve 405 connected to the permeate side of the nanofiltration-grade membrane module 207 via a pipeline. The air washing valve 405 is connected to an external air source 403 via a pipeline, and a float flow meter 404 is installed on the pipeline. By opening the air washing valve 405 and connecting the external air source 403, nitrogen gas is used to perform air washing on the ultrafiltration-grade membrane module 205 and the nanofiltration-grade membrane module 207. In addition, in this embodiment, the working sewage pump 203 on the retention side of the membrane separation unit can also be started, in conjunction with the backwash pump 304, for suction cleaning.

[0068] In this embodiment, the finished oil unit and the membrane cleaning unit share a single backwash pump 304, which not only reduces the use of pumps but also saves pipeline space, enabling the purification membrane refining equipment to achieve a high degree of integration.

[0069] Specifically, the sewage discharge unit includes an air vent valve 501 located at the bottom of the circulating oil tank 201, a sewage discharge valve 502 located at the bottom of the finished oil tank 303 and on the interception side of the ultrafiltration purification membrane module 205, a working sewage discharge pump 203 connected to the air vent valve 501 and the sewage discharge valve 502, the working sewage discharge pump 203 being connected to the waste oil valve 503 via a pipeline, and the waste oil valve 503 being connected to the concentrated oil tank 504 via a pipeline.

[0070] For the concentrated oil discharged from the retrieval side of the ultrafiltration-grade purification membrane module 205, the concentrated oil discharged from the retrieval side of the ultrafiltration-grade purification membrane module 205 is transported to the concentration tank 504 by opening the drain valve 502 and waste oil valve 503 and starting the working drain pump 203.

[0071] In this embodiment, the sewage discharge unit and the membrane separation unit share the same working sewage discharge pump 203, which further reduces the space occupied by the components of the purification membrane refining equipment.

[0072] Specifically, the heat recovery unit includes a heat exchanger 601 installed on one side of the preheating pipe 102; a circulation pipe 602 connected to the heat exchanger 601 and the concentrated oil tank 504 respectively; and a heat exchange pump 603 installed on the circulation pipe 602. The heat exchange pump 603 transports the high-temperature concentrated oil in the concentrated oil tank 504 to the heat exchanger 601 to heat the preheating pipe 102, thereby realizing heat recovery and utilization.

[0073] Please continue reading. Figure 3 As shown, the central control unit is internally configured with a standard oil flow rate Lb and a standard oil flow rate difference ΔLb. When the circulation valve 206 is closed, the central control unit can acquire the real-time oil flow rate Ls detected by the finished oil flow meter 301, and calculate the real-time oil flow rate difference ΔLs based on the real-time oil flow rate Ls and the standard oil flow rate Lb, where ΔLs = |Lb - Ls|. The central control unit then determines the real-time oil flow rate difference ΔLs based on the standard oil flow rate difference ΔLb.

[0074] When ΔLs≤ΔLb, the central control unit determines that the oil output status is normal and does not adjust the operating status of the purification membrane refining equipment;

[0075] When ΔLs > ΔLb, the central control unit will determine the real-time oil flow rate Ls based on the standard oil flow rate Lb in order to determine the adjustment of the purification membrane refining equipment.

[0076] In this embodiment, the standard oil flow rate and the standard oil flow rate difference need to be selected according to the actual situation, and are specifically affected by the membrane flux of the oil purification membrane used, the pump flow rate adopted, and the actual production demand. In this embodiment, the purification membrane refining equipment used for edible oil production has a processing capacity of 10 tons / day, so the standard oil flow rate is set to 15 liters / minute, and the standard oil flow rate difference is set to 0.3 liters / minute to ensure the processing volume in actual production.

[0077] When the real-time oil flow rate Ls is higher than the standard oil flow rate Lb, the central control unit reduces the impeller speed of the working sewage pump 203, Ng1=Ng×[1-(Ls-Lb) / Lb], where Ng is the impeller speed of the working sewage pump 203 before adjustment and Ng1 is the impeller speed of the working sewage pump 203 after adjustment. By reducing the impeller speed of the working sewage pump 203, the oil inlet pressure of the purification membrane module is reduced, thereby controlling the oil flow rate to maintain the stable operation of the overall equipment.

[0078] When the real-time oil flow rate Ls is lower than the standard oil flow rate Lb, the central control unit will acquire the real-time oil temperature Ts in the circulating oil tank 201 and determine the real-time oil temperature Ts based on the set standard oil temperature Tb.

[0079] When the real-time oil temperature Ts is greater than or equal to the standard oil temperature Tb, the central control unit will determine the real-time filtration pressure difference on both sides of the purification membrane module to determine whether to adjust the operating status of the purification membrane refining equipment.

[0080] When the real-time oil temperature Ts < the standard oil temperature Tb, the central control unit will adjust the initial heating temperature of the heating layer in the circulating oil tank 201.

[0081] A heating layer is provided inside the circulating oil tank 201. The heating layer is set with an initial heating temperature Tj. When the central control unit determines that the real-time oil temperature Ts is lower than the standard oil temperature Tb, it adjusts the initial heating temperature Tj of the heating layer to Tj1, where Tj1 = Tj × (Tb / Ts).

[0082] In this embodiment, the crude oil entering the circulating oil tank 201 is preheated, which can shorten the heating time in the circulating oil tank 201. However, the crude oil in the circulating oil tank 201 also circulates, which will cause some heat loss. The standard oil temperature setting depends on the optimal operating temperature of the oil purification membrane. In this embodiment, the optimal operating temperature of the ultrafiltration membrane is 60°C, and the optimal operating temperature of the nanofiltration membrane is 50°C. A small amount of heat is also lost during the process of the oil moving from the ultrafiltration membrane assembly 205 to the nanofiltration membrane assembly 207. Therefore, the optimal oil temperature was selected as 58℃, and the initial heating temperature of the heating layer was set as 65℃. However, in actual production, the actual temperature of the crude oil entering the purification membrane module may be low due to factors such as the low initial temperature of the crude oil in the raw material oil tank 101, the influence of the heat conversion rate of the heat recovery unit on the environment, and insufficient heating time of the crude oil in the circulating oil tank 201. Therefore, the initial heating temperature of the heating layer is adjusted in real time to ensure that the temperature of the crude oil is stable when it enters the purification membrane module, thus ensuring the stable operation of the purification membrane refining equipment.

[0083] Please continue reading. Figure 4 As shown, the central control unit also has a first filtration pressure difference ΔP1 and a second filtration pressure difference ΔP2, where ΔP2 > ΔP1. When the real-time oil temperature Ts ≥ the standard oil temperature Tb, the central control unit will acquire the real-time inlet pressure Pj detected by the first pressure sensor and the real-time outlet pressure Pc detected by the third pressure sensor, and calculate the real-time filtration pressure difference ΔPs, ΔPs = Pj - Pc, and then determine the real-time filtration pressure difference ΔPs.

[0084] When the real-time filtration pressure difference ΔPs < the first filtration pressure difference ΔP1, the central control unit determines that the membrane flux of the purification membrane module is normal and will increase the impeller speed of the working sewage pump 203, Ng2 = Ng × [1 + (Lb - Ls) / Lb], where Ng is the impeller speed of the working sewage pump 203 before adjustment and Ng2 is the impeller speed of the working sewage pump 203 after adjustment; by increasing the impeller speed of the working sewage pump 203, the oil inlet pressure of the purification membrane module is increased, thereby controlling the oil flow rate to maintain the stable operation of the overall equipment.

[0085] When the first filtration pressure difference ΔP1 ≤ real-time filtration pressure difference ΔPs ≤ second filtration pressure difference ΔP2, the central control unit will close the oil inlet valve 202, open the drain valve 502 and waste oil valve 503, and start the working drain pump 203 to discharge the concentrated oil from the interception side of the ultrafiltration purification membrane module 205.

[0086] When the real-time filtration pressure difference ΔPs > the second filtration pressure difference ΔP2, the central control unit will clean the purification membrane module.

[0087] In this embodiment, the first filtration pressure difference ΔP1 is the pressure difference across the purification membrane module during normal operation, and the second filtration pressure difference ΔP2 is the pressure difference across the membrane module when the membrane flux decreases due to blockage. The difference is set according to the actual purified oil and the specific power of the working sewage pump 203. In this embodiment, the first filtration pressure difference is set to 2.1 MPa, and the allowable increase in the blockage pressure of the purification membrane module is 30%, that is, the second filtration pressure difference is 2.73 MPa = 2.1 MPa + 2.1 MPa × 0.3.

[0088] Specifically, when processing crude edible oil that requires multiple filtrations to remove gum, both the circulation valve 206 and the return valve 208 are open. The crude oil is not filtered through the nanofiltration-level purification membrane module 207; instead, it is circulated and filtered only between the ultrafiltration-level purification membrane module 205 and the circulating oil tank 201. At this time, the central control unit determines whether to discharge sewage or whether the gum removal standard has been met by detecting the oil pressure difference between the first pressure sensor and the second pressure sensor. When the gum removal standard is met, the circulation valve 206 is closed, allowing the crude oil that has met the gum removal standard to enter the nanofiltration-level purification membrane module 207. After filtration, the refining of the finished oil is completed.

[0089] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A purification membrane refining device for edible oil production, characterized in that, include, The pretreatment unit is used to receive and pre-treat crude oil, including pre-filtration and preheating of the crude oil. A membrane separation unit includes a circulating oil tank for receiving crude oil, a purification membrane module for membrane filtration of the crude oil, and a working wastewater pump for conveying the crude oil in the circulating oil tank to the purification membrane module. The purification membrane module includes an ultrafiltration-stage purification membrane group and a nanofiltration-stage purification membrane group connected in series. The circulating oil tank is equipped with a heating layer for heating and a temperature sensor for detecting the real-time oil temperature. An oil inlet valve is provided on one side of the circulating oil tank, a working wastewater pump is provided on one side of the oil inlet valve, and a feed valve is provided on one side of the working wastewater pump. The feed valve is connected to the filtration side of the ultrafiltration-stage purification membrane group. The permeation side of the ultrafiltration-stage purification membrane module is connected to the circulation valve and the nanofiltration-stage purification membrane module, respectively. A reflux valve is provided on one side of the circulation valve, and the reflux valve is connected to the circulation oil tank through a pipeline. The ultrafiltration-grade purification membrane module is equipped with a first pressure sensor on the retention side and a second pressure sensor on the permeation side, and the nanofiltration-grade purification membrane module is equipped with a third pressure sensor on the permeation side. A membrane cleaning unit, which is connected to the membrane separation unit, is used to clean the membrane separation unit online; A wastewater discharge unit is connected to the retention side of the purification membrane module to discharge concentrated oil from the retention side of the purification membrane module. The central control unit is connected to the pretreatment unit, the membrane separation unit, the membrane cleaning unit, and the sewage discharge unit respectively. The central control unit is equipped with a standard oil flow range consisting of a standard oil flow rate and a standard oil flow rate difference. The central control unit calculates the absolute value of the difference between the real-time oil flow rate and the standard oil flow rate as the real-time oil flow rate difference. When the real-time oil flow rate difference is greater than the standard oil flow rate difference, it is determined that the real-time oil flow rate is not within the standard oil flow rate range. Based on the comparison between the real-time oil flow rate and the standard oil flow rate, it is determined whether the real-time oil flow rate is lower or higher than the standard oil flow rate range. The central control unit can reduce the impeller speed of the working sewage pump when the real-time oil flow rate is higher than the standard oil flow rate range, Ng1=Ng×[1-(Ls-Lb) / Lb]; The central control unit can increase the initial heating temperature of the heating layer when the real-time oil flow rate is lower than the standard oil flow rate range and the real-time oil temperature is lower than the standard oil temperature, Tj1=Tj×(Tb / Ts). Where Ng is the impeller speed of the working sewage pump before adjustment, Ng1 is the impeller speed of the working sewage pump after adjustment, Ls is the real-time oil flow rate, Lb is the standard oil flow rate, Tj is the initial heating temperature of the heating layer, Tj1 is the heating temperature of the heating layer after adjustment, Tb is the standard oil temperature, and Ts is the real-time oil temperature. The central control unit is also equipped with a first filtration pressure difference. When the real-time oil flow rate is lower than the standard oil flow rate range and the real-time oil temperature is higher than the standard oil temperature, the central control unit obtains the real-time inlet pressure and real-time outlet pressure on both sides of the purification membrane module, calculates the real-time filtration pressure difference, and controls the increase of the impeller speed of the working sewage pump when the real-time filtration pressure difference is less than the first filtration pressure difference. The central control unit is also equipped with a second filtration pressure difference, wherein the second filtration pressure difference is greater than the first filtration pressure difference. When the central control unit determines that the real-time filtration pressure difference is between the first filtration pressure difference and the second filtration pressure difference, it controls the sewage discharge unit to start sewage discharge. When the central control unit determines that the real-time filtration pressure difference is greater than the second filtration pressure difference, it controls the membrane cleaning unit to start cleaning.

2. The purification membrane refining equipment for edible oil production according to claim 1, characterized in that, The pretreatment unit includes a raw oil tank for storing crude oil, which is connected to a pre-filter via a preheating pipe. A feed pump is provided on one side of the pre-filter to transport the pre-filtered crude oil to the circulating oil tank of the membrane separation unit.

3. The purification membrane refining equipment for edible oil production according to claim 1, characterized in that, Both the ultrafiltration-grade purification membrane module and the nanofiltration-grade purification membrane module are organic purification membranes, including but not limited to PTFE membranes, PP membranes, PE membranes, and PVDF membranes.

4. The purification membrane refining equipment for edible oil production according to claim 2, characterized in that, The membrane cleaning unit includes a backwash pump and an external air source. A backwash valve is provided on one side of the backwash pump and is connected to the permeate side of the nanofiltration-grade purification membrane module. An air washing valve is provided on one side of the external air source and is also connected to the permeate side of the nanofiltration-grade purification membrane module. The wastewater discharge unit includes a wastewater discharge valve located on the interception side of the ultrafiltration-stage purification membrane module, a working wastewater discharge pump connected to the wastewater discharge valve, a waste oil valve located on one side of the working wastewater discharge pump, and a concentrated oil tank located on one side of the waste oil valve; wherein, the wastewater discharge unit and the membrane separation unit share the working wastewater discharge pump.

5. The purification membrane refining equipment for edible oil production according to claim 4, characterized in that, It also includes a refined oil processing unit and a heat recovery unit; The finished oil unit includes a finished oil tank, which is connected to the permeate side of the nanofiltration-grade purification membrane module via a pipeline, and the pipeline is equipped with a finished oil flow meter and an oil production valve; a transfer backwash pump is also provided on one side of the finished oil tank, and a transfer valve is provided on one side of the transfer backwash pump, and the transfer valve is connected to a storage oil tank on one side; wherein, the finished oil unit and the membrane cleaning unit share the transfer backwash pump; The heat recovery unit includes a heat exchanger disposed on one side of the preheating pipe, a circulation pipe connected to the heat exchanger and the concentrated oil tank respectively, and a heat exchange pump disposed on the circulation pipe.

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