Process for decolorizing fats and oils

Abstract

The application discloses a grease decoloring process, which comprises the following steps: oil to be decolored is mixed with white clay, and then is filtered by a filter and a precision filter, and finally is stored in an oil tank, wherein the first and second white clay mixers are connected with the decoloring tower respectively, the second white clay mixer is also connected with the filter, and a closed loop is formed during the decoloring to form a filter cake layer on the filter screen of the filter, then the second white clay mixer is connected with the decoloring tower, the oil and clay mixture of the decoloring tower is filtered in the filter in which the filter cake layer has been formed, and then flows into the oil tank through the precision filter. In one aspect, the oil and clay mixture discharged from the decoloring tower is directly filtered by the filter screen and the filter cake layer to obtain high-quality grease, thereby greatly shortening the time of the grease decoloring treatment and improving the decoloring efficiency and processing capacity of the decoloring system. In another aspect, the residual liquid in the filter cake is blown dry by gas, and then the filter cake is shaken off by the vibrating filter screen to clean the filter screen.

Description

[0001] This application is a divisional application of application number 201910253480.5, filed on March 29, 2019, entitled "An Oil Decolorization System and Process Containing a Vertical Blade Filter". Technical Field

[0002] This invention belongs to the field of oil decolorization technology, and specifically relates to an oil decolorization process. Background Technology

[0003] Currently, vertical blade filters, as a new type of filter, are widely used in the filtration processes of the food and oil industries. They are important equipment for solid-liquid separation and are gradually replacing plate and frame filters, which are slow to filter, labor-intensive, and have high oil loss.

[0004] In food or oil processing, the separation of components with different compositions and forms is frequently encountered. The purpose is to remove harmful or useless components, retain the effective components for processing and utilization, or to separate components with different properties for separate processing and utilization. Solid-liquid separation is one of the common unit operations, and filtration is a traditional chemical unit operation. Its principle is that when a liquid feed passes through a solid filter medium, the suspended solids are separated from the solution.

[0005] In oil extraction and processing, filtration is essential in processes such as crude oil purification, oil decolorization, winterization degreasing, and dewaxing. Various filtration equipment is frequently used, including plate and frame filters, box filters, centrifugal filters, and bag filters. Plate and frame filters are a traditional type of filtration equipment. The filter plates and frames are typically square, but round ones are also used (mostly in small-scale equipment). The characteristic of round plate and frame filter presses is that, for the same filtration area, the sealing perimeter is the shortest, thus requiring the least clamping force. However, for the same filtration area, their overall dimensions are larger. Plate and frame filters are divided into two types: open flow and closed flow. Open flow filters allow the filtrate to flow directly from the outlet of each filter plate; closed flow filters allow the filtrate to flow out from the outlet of a fixed end plate. For example, plate and frame filters are used in the winterization and dewaxing process of oil processing, while oil filtration often uses oil clarifying tanks. The advantages of these filtration machines are low investment and suitability for small-batch production. The main disadvantages are: the separation process cannot be carried out continuously, the filtration efficiency is low, the residual oil content in the filter cake is high, resulting in large losses, high labor intensity, small production capacity of a single unit, and the use of multiple units will occupy a large factory area, which is not conducive to management.

[0006] With continuous improvements in filter performance, manufacturers now widely choose vertical leaf filters for filtration. Vertical leaf filters combine the stable performance of plate and frame filters with the advantages of closed-loop continuous production, offering high throughput and good economic benefits. Compared to plate and frame filters, vertical leaf filters have a compact structure, smaller footprint, mechanized automatic slag discharge, are clean and hygienic with low pollution, and fully automatic operation. Two units can be used in parallel or alternately to achieve continuous closed-loop production, significantly reducing labor intensity and optimizing on-site management.

[0007] The operation of vertical blade filters is generally controlled automatically by a computer, and each cycle includes the following stages:

[0008] (1) During the feeding stage, the solid-liquid mixture is fed into the filter body. When liquid flows through the overflow port, it indicates that the filter body of the vertical blade filter is full of the liquid to be filtered. Then the overflow port can be closed and the filter cake stage can begin.

[0009] (2) Cake-forming stage: At this stage, filtrate begins to pass through the filter screen. The filtrate passing through the filter screen at this time is turbid and should be returned to the filtrate to be filtered. When the turbid liquid becomes clear, close the reflux channel and enter the normal filtration stage. This stage usually takes about 30 minutes.

[0010] (3) Filtration stage: The normal filtration stage usually lasts about 2 to 4 hours. When the tank pressure reaches the specified limit value, filtration should be stopped. At this time, the thickness of the filter cake on the filter screen has reached the limit value and filtration can no longer be performed.

[0011] (4) Slag discharge stage: This stage involves many valve operations and is considered an auxiliary working time. The filter tank is emptied, the filter cake is dried, and the filter cake is removed. After discharge, the valve is closed to prepare for the next filtration.

[0012] The grease decolorization process using a vertical blade filter, such as... Figure 1 As shown, after passing through the clay mixer, the decolorized oil enters the decolorization tower for decolorization treatment. After the decolorization treatment is completed, the oil-clay mixture is pumped into the filter for filtration, and then into the storage tank after fine filtration.

[0013] However, the main component of oils is triglycerides. Pure triglycerides are colorless in liquid and white in solid. However, various common oils have different colors due to the varying amounts and types of pigments they contain. Most pigments are non-toxic but affect the appearance of the oils. Therefore, to produce higher-grade oil products, such as national standard grade 1 oil, the raw material for margarine, and certain cosmetic raw materials, decolorization is necessary. There are many methods for oil decolorization, with adsorption decolorization being the most widely used in industrial production. While this method generally works well for filtering crude oil, it is problematic when decolorizing oils by filtering bleaching clay. Due to the characteristics of bleaching clay itself—such as its small particle size and high viscosity when containing oil—problems easily arise during operation. The most obvious drawback is the excessively long cake-forming time, which increases the intensity and difficulty of equipment operation. Furthermore, as the filtration time increases, the filter cake on the filter screen becomes denser, and the filtration channels become narrower, reducing the normal filtration time. Therefore, the decolorization efficiency of the oils is very low. Summary of the Invention

[0014] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide an improved oil decolorization process. This process allows a filter cake layer to form on the filter screen of a vertical blade filter while the decolorization tower is in operation. In this way, the oil-soil mixture discharged from the decolorization tower is directly filtered for high-quality oil through the cooperation of the filter cake layer and the filter screen, thereby significantly shortening the oil decolorization time and improving the decolorization efficiency and processing capacity of the decolorization system.

[0015] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0016] An oil decolorization process includes: oil to be decolorized → clay mixing → decolorization tower → filter → fine filter → oil storage tank. The clay mixing process utilizes a first clay mixer and a second clay mixer, both connected to the decolorization tower. The second clay mixer is also connected to the filter. Simultaneously with decolorization in the decolorization tower, a closed-loop circulation of oil-clay mixture is formed between the second clay mixer and the filter, resulting in a filter cake layer on the filter screen. Once the decolorization requirements are met, the closed-loop circulation is closed, and the second clay mixer is reconnected to the decolorization tower. The oil and clay mixture is then discharged through the decolorization tower's drain channel. The mixture enters a filter press where a filter cake layer has already formed for filtration. After cooling, the filtered oil is further filtered by a fine filter press to form decolorized oil that flows into the oil storage tank. When the filter cake layer accumulated on the filter screen gradually thickens and the oil output speed of the filter press slows down, filtration is stopped. First, compressed air is used to discharge the liquid to be filtered from the filter press. Then, steam or compressed air is used to dry the residual liquid in the filter cake layer. The slag discharge port is opened, and the filter cake layer is shaken off from the slag discharge port of the filter press by vibrating the filter screen to complete the filter screen cleaning. Then, the oil-clay mixture is circulated again to form a filter cake layer on the filter screen in preparation for the next filtration.

[0017] Preferably, the filter is a vertical blade filter, which includes a vertically arranged tank with an inlet, an outlet and a slag discharge port; and filter blades vertically arranged in the tank. The tank includes a body, a cover and a bottom, and the filter blades are detachably mounted on the side walls of the tank from both sides.

[0018] Furthermore, there are multiple sets of filter blades, each set of filter blades including a rectangular filter frame and filter screens located on opposite sides of the filter frame, wherein the filter screens and filter frame form a filter cavity.

[0019] According to a specific embodiment and preferred aspect of the present invention, the vertical blade filter further includes an oil collecting pipeline for communicating the plurality of filter chambers from the filter frame to each other, an oil discharging pipeline for connecting the oil collecting pipeline to the discharge port, and an oil storage tank.

[0020] Preferably, the filter frame is a hollow pipe, and a connecting pipe is provided between the multiple hollow pipes to connect the inner cavities of the multiple hollow pipes.

[0021] Furthermore, through holes are formed on the inner wall of each hollow pipe forming the filter chamber, allowing the filtered oil to flow through these through holes within the hollow pipe and towards the oil collection pipe. This significantly improves filtration efficiency.

[0022] In some specific embodiments, the horizontal cross-section of the tank body is circular, and multiple sets of filter blades are distributed evenly at intervals along the extension direction of the same diameter of the circle inside the circle; and / or, the filter frames of multiple sets of filter blades are of equal height and are evenly distributed at intervals.

[0023] According to another specific embodiment and preferred aspect of the present invention, the vertical blade filter further includes a support detachably disposed inside the tank body and a vibrator disposed outside the support, wherein the filter blades are detachably connected to the support from the upper and lower ends, and the output end of the vibrator is in communication with the support. When cleaning, the vibration of the vibrator is transmitted to the support, and the filter blades vibrate accordingly to cause the cake to fall off.

[0024] In some specific embodiments, the slag discharge port is located at the bottom of the tank bottom, and the feed inlet is located on the side of the tank bottom, and there are two of them; the feed inlet is located on the side of the tank body, and an overflow port is also provided above the feed inlet on the side of the tank body.

[0025] In addition, the first and second clay mixers share a single clay additive.

[0026] Preferably, after the vertical blade filter forms a cake, the second bleaching clay mixer can be connected to the decolorization tower, allowing the oil-clay mixture to undergo further decolorization treatment in the decolorization tower. This significantly improves the efficiency of oil decolorization.

[0027] In short, the working process of a vertical blade filter is as follows: the oil-soil mixture is pumped into the tank. Under pressure, the filtrate passes through the filter surfaces on both sides of the blades and enters the blade filter chamber. Initially, some small particles smaller than the filter mesh will pass through the filter and enter the filtrate. This unsuitable filtrate must be returned to the liquid to be filtered, thus forming a closed-loop cycle. Solid impurities in the liquid to be filtered are gradually trapped on the filter screen to form a filter cake. Only after a stable and effective filter cake is established on the filter screen can clear and qualified filtrate be obtained at the outlet. At this point, the vertical blade filter... After the machine completes the pre-treatment filtration, the oil-soil mixture discharged from the decolorization tower is pumped into the tank. Under the action of the filter cake and filter screen, the decolorized oil flows to the storage tank. At this point, the vertical blade filter enters the effective filtration stage. However, as the filtration time increases, the amount of filter cake accumulated on the filter screen gradually increases. Once a certain amount is reached, the effective filtration stage should end. Compressed air is used to discharge the liquid to be filtered from the filter tank. After the residual liquid in the filter cake is dried with steam (or compressed air), the butterfly valve at the bottom of the tank is opened, and the vibrator is started to vibrate the filter screen, causing the filter cake to fall off and be discharged from the tank. After the filter cake is discharged, the butterfly valve is closed to prepare for the next filtration.

[0028] In addition, regarding the above-mentioned "until the decolorization requirements are met", under normal circumstances, it is sufficient to observe whether the filtered oil is clear. Of course, the quality of the filtered oil can also be judged by analyzing the soil content of the oil through automatic sampling. Commonly used equipment for oil quality monitoring can be purchased directly from outside.

[0029] Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0030] In existing oil decolorization processes, due to the inherent characteristics of bleaching clay, such as its small particle size and high viscosity of oily bleaching clay, several problems easily arise during operation. The most obvious drawback is the excessively long cake-hanging time, which increases the intensity and difficulty of equipment operation. At the same time, as the filtration time increases, the filter cake on the filter screen becomes dense, and the filtration channels become narrow, reducing the normal filtration time. Therefore, the decolorization efficiency of oil is very low. This invention cleverly solves the various shortcomings of existing oil decolorization processes through a holistic design of the oil decolorization process. After adopting this oil decolorization process, the decolorized oil, after being heated by a heater, is pumped into the first clay mixer, where it mixes with clay added by the clay additive device. Once fully mixed, the oil-clay mixture is pumped into the decolorization tower. Inside the tower, under stirring, the clay adsorbs pigments and other substances from the oil. Simultaneously, another portion of the heated oil to be decolorized is pumped into the second clay mixer, where it mixes with clay added by the clay additive device. In the second clay mixer, the clay concentration in the resulting oil-clay mixture is significantly increased compared to the oil-clay mixture in the decolorization tower. This highly concentrated oil-clay mixture, fully mixed in the second clay mixer, is then pumped into a filter, completing the filter's feeding and cake-forming stages. The reflux from the cake-forming stage is returned to the second clay mixer. In the bleaching clay mixer, once the cake has formed and a stable filter layer has been created on the filter screen, the normal filtration stage can begin. At this point, the oil inlet channel from the second bleaching clay mixer to the filter is closed, while the oil inlet channel from the decolorizing tower to the filter is opened. The decolorized mixture is then filtered. After cooling, the filtered oil is further filtered by a safety filter (fine filter), resulting in decolorized oil. Therefore, this invention achieves two advantages: First, it allows the formation of a filter cake layer on the filter screen of the filter while the decolorizing tower is decolorizing. This allows the oil-clay mixture discharged from the decolorizing tower to directly filter high-quality oil through the combined action of the filter cake layer and the filter screen, significantly shortening the oil decolorization time and improving the decolorization efficiency and processing capacity of the decolorization system. Second, by blowing away the residual liquid in the filter cake with gas and then using a vibrating filter screen to shake the filter cake off, the filter screen is quickly cleaned, making the operation convenient and efficient. Attached Figure Description

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1 This is a schematic diagram of the oil decolorization process in the existing technology;

[0033] Figure 2 This is a schematic diagram of the structure of the oil decolorization system of the present invention;

[0034] Figure 3 This is a partial structural front view of the vertical blade filter of the present invention;

[0035] Figure 4 for Figure 3 A magnified cross-sectional view of one of the filter blades;

[0036] Figure 5 This is a schematic diagram of the oil decolorization process of the present invention;

[0037] The components are as follows: 1. Bleaching clay mixing unit; 10. First bleaching clay mixer; 11. Bleaching clay adding device; 2. Decolorization tower; 3. Vertical blade filter; 30. Tank body; 30a. Tank body; 30b. Tank cover; 30c. Tank bottom; a. Inlet; b. Outlet; c. Slag outlet; d. Overflow outlet; 31. Filter blades; 310. Filter frame; 311. Filter screen; q. Through hole; 32. Oil collection pipeline; 33. Support; 34. Vibrator; 35. Oil storage tank; 4. Pretreatment unit; 40. Second bleaching clay mixer; 41. Circulation component; 42. Detection device; B. Filter cake layer (cake); X. Oil to be decolorized. Detailed Implementation

[0038] See Figure 2 As shown, the grease decolorization system containing a vertical blade filter according to this embodiment includes a clay mixing unit 1, a decolorization tower 2, a vertical blade filter 3, and a pretreatment unit 4 for pretreating the vertical blade filter 3 to form a cake (or filter cake layer).

[0039] Specifically, the bleaching clay mixing unit 1 includes a first bleaching clay mixer 10 and a bleaching clay adding device 11 connected to the pipeline of the oil to be decolorized X. The first bleaching clay mixer 10 is connected to the decolorization tower 2, and the decolorization tower 2 is connected to the vertical blade filter 3.

[0040] Vertical blade filter 3 is used for solid-liquid separation of oil-soil mixtures.

[0041] The pretreatment unit 4 includes a second clay mixer 40 connected to the vertical blade filter 3, a circulation component 41 that circulates the pre-filtered oil from the vertical blade filter 3 to the second clay mixer 40, and a detection device 42 installed on the oil outlet pipeline of the vertical blade filter 3 to detect the color and / or clay content of the oil online. When the result measured by the detection device 42 meets the decolorization requirements, a cake (filter cake layer) B is formed on the filter screen of the vertical blade filter 3, the circulation component 41 stops working, and the oil-clay mixture in the decolorization tower 2 enters the vertical blade filter 3 with the cake formed for filtration, that is, the cake formation process is completed.

[0042] As for the testing device 42, generally, it is sufficient to observe whether the filtered oil is clear. Of course, analyzing the soil content of the oil through automatic sampling can also determine the quality of the filtered oil. Furthermore, the testing device 42 is a commonly used device for oil quality monitoring and can be purchased directly; therefore, it will not be described in detail here.

[0043] The circulation component 41 mainly includes a circulation pump and circulation pipelines.

[0044] Meanwhile, the second bleaching clay mixer 40 is also connected to the decolorization tower 2. That is, after the vertical blade filter 3 forms a cake, the second bleaching clay mixer 40 can be connected to the decolorization tower, allowing the oil-clay mixture to undergo further decolorization treatment in the decolorization tower 2. This significantly improves the efficiency of oil decolorization.

[0045] Combination Figure 3 As shown, the vertical blade filter 3 includes a vertically arranged tank 30 with an inlet a, an outlet b and a slag discharge outlet c; and filter blades 31 vertically arranged inside the tank 30. The tank 30 includes a tank body 30a, a tank cover 30b and a tank bottom 30c, and the filter blades 31 are detachably arranged on the side walls of the tank body 30a from both sides.

[0046] In this example, the can body 30a is cylindrical, the can bottom 30c is a frustum-shaped cone with an outer diameter that gradually decreases from top to bottom, and the can lid 30b is detachably installed at the opening of the can body 30a.

[0047] Specifically, the horizontal cross-section of the tank body 30a is circular, and there are multiple sets of filter blades 31, which are distributed sequentially and at intervals inside the circle along the same diameter.

[0048] Combination Figure 4 As shown, each set of filter blades 31 includes a rectangular filter frame 310 and filter screens 311 located on opposite sides of the filter frame 310. The filter screens 311 and the filter frame 310 form a filter cavity. The vertical blade filter also includes an oil collection pipe 32 for connecting multiple filter cavities from the filter frame 310, an oil outlet pipe (not shown in the figure, but easy to imagine) for connecting the oil collection pipe 32 to the discharge port b, and an oil storage tank 35.

[0049] In this example, the filter frame 310 is a hollow pipe, and a connecting pipe is provided between multiple hollow pipes to connect their inner cavities. Each hollow pipe forming a filter cavity has a through hole q on its inner wall, allowing the filtered oil to flow through the through hole q within the hollow pipe and towards the oil collection pipe 32. This significantly improves filtration efficiency.

[0050] In this example, the filter frames of multiple sets of filter blades 31 have the same height and are evenly spaced.

[0051] The vertical blade filter 3 also includes a support 33 detachably installed inside the tank body 30a and a vibrator 34 installed outside the support 33. The filter blades 31 are detachably connected to the support 33 from the upper and lower ends. The output end of the vibrator 34 is connected to the support 33. When cleaning, the vibration of the vibrator 34 is transmitted to the support 33, and the filter blades 31 vibrate accordingly to cause the cake to fall off.

[0052] In addition, the slag discharge port c is located at the bottom of the tank bottom 30c, and the feed port a is located on the side of the tank bottom 30c, and there are two of them; the feed port a is located on the side of the tank body 30a, and an overflow port d is also provided above the feed port on the side of the tank body 30a. The overflow port d is provided so that when liquid flows through the overflow port d during the feeding stage of the vertical blade filter 3, it means that the vertical blade filter 3 is full of liquid to be filtered, and the overflow port can be closed to enter the filter cake hanging stage.

[0053] In this example, the working process of the vertical blade filter is as follows: the oil-soil mixture is pumped into the tank. Under pressure, the filtrate passes through the filter surfaces on both sides of the blades and enters the blade filter chamber. Initially, some small particles smaller than the filter mesh will pass through the filter and enter the filtrate. At this point, the unsuitable filtrate must be returned to the liquid to be filtered, thus forming a closed-loop cycle. Solid impurities in the liquid to be filtered are gradually trapped on the filter screen, forming a filter cake layer. Only after a stable and effective filter cake is established on the filter screen can clear and qualified filtrate be obtained at the outlet. At this point, the vertical blade filter... After the machine completes the pre-treatment filtration, the oil-soil mixture discharged from the decolorization tower is pumped into the tank. Under the action of the filter cake and filter screen, the decolorized oil flows to the storage tank. At this point, the vertical blade filter enters the effective filtration stage. However, as the filtration time increases, the amount of filter cake accumulated on the filter screen gradually increases. Once a certain amount is reached, the effective filtration stage should end. Compressed air is used to discharge the liquid to be filtered from the filter tank. After the residual liquid in the filter cake is dried with steam (or compressed air), the butterfly valve at the bottom of the tank is opened, and the vibrator is started to vibrate the filter screen, causing the filter cake to fall off and be discharged from the tank. After the filter cake is discharged, the butterfly valve is closed to prepare for the next filtration.

[0054] In addition, to further ensure the filtration effect, a fine filter can be installed between the vertical blade filter and the oil storage tank.

[0055] The decolorization process of this application (see [link]). Figure 5 As shown):

[0056] After being heated by the heater, the decolorized oil is pumped into the clay mixer 1, where it mixes with the clay added by the clay additive device (clay additive). Once fully mixed, the oil-clay mixture is pumped into the decolorization tower. Inside the tower, under stirring, the clay adsorbs pigments and other substances from the oil. Simultaneously, another portion of the heated oil is pumped into the clay mixer 2, where it mixes with the clay added by the clay additive device (clay additive). In the oil-clay mixture formed in the clay mixer 2, the clay concentration is significantly increased, compared to the concentration in the decolorization tower. The high-concentration oil-clay mixture, thoroughly mixed in the clay mixer 2, is pumped into the vertical blade filter to complete the feeding and cake-forming stages of the vertical blade filter. The reflux from the cake-forming stage returns to the clay mixer 2. Once the cake-forming is complete, a stable filter layer is formed on the filter screen, and the normal filtration stage can begin. At this point, the oil inlet channel from the clay mixer 2 to the vertical blade filter is closed, and the oil inlet channel from the decolorization tower to the vertical blade filter is opened. The decolorized mixture is then filtered, and the filtered oil is cooled and further filtered by a safety filter (fine filter) to become decolorized oil.

[0057] In this process, similar to the original decolorization process, the vertical blade filter undergoes a four-stage cyclical operation. The feeding, filtering, and slag discharge stages remain largely unchanged. The most significant change is in the cake-forming stage. Previously, the oil-bright clay mixture from the decolorization tower was fed into the vertical blade filter for cake formation, resulting in low clay concentration and a long cake-forming time. Now, a dedicated device supplies the vertical blade filter with a high-concentration oil-bright clay mixture for circulation, significantly accelerating the cake-forming speed and reducing the cake-forming time by more than half. The significantly shortened cake-hanging time makes the oil flow channels in the filter cake layer on the filter screen looser and more unobstructed, allowing oil to pass through more easily. However, the bleaching clay is blocked by the filter cake layer, thus prolonging the normal filtration time. Therefore, the filter screen needs to be cleaned. Specifically, use compressed air to drain the liquid to be filtered from the filter tank, and use steam (or compressed air) to dry the residual liquid in the filter cake. Then, open the butterfly valve at the bottom of the tank, start the vibrator to drive the filter screen to vibrate and shake off the filter cake, which is then discharged from the tank. After the filter cake is discharged, close the butterfly valve to prepare for the next filtration.

[0058] Therefore, the reduced cake hanging time lowers the operational intensity and difficulty of the equipment. At the same time, since the decolorization of the decolorization tower and the feeding and cake hanging of the vertical blade filter are carried out simultaneously, the original process was to decolorize first and then feed and hang cake. By adopting the system of this application, the process time is significantly shortened, which is equivalent to improving the processing capacity of the equipment.

[0059] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. Furthermore, the invention is not limited to the embodiments described above. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be covered within the scope of protection of the invention.

Claims

1. A process for decolorizing oil, comprising: oil to be decolorized → mixing with bleaching clay → decolorization tower → filter → fine filter → oil storage tank, characterized in that: In the bleaching clay mixing process, a first bleaching clay mixer and a second bleaching clay mixer are connected to the decolorization tower, respectively. The second bleaching clay mixer is also connected to a filter. While the decolorization tower is performing decolorization, a closed-loop circulation of oil-bearing clay mixture is formed between the second bleaching clay mixer and the filter, resulting in a filter cake layer forming on the filter screen. Once the decolorization requirements are met, the closed-loop circulation is closed, and the second bleaching clay mixer is connected to the decolorization tower. Then, the oil discharge channel of the decolorization tower is opened, and the oil-bearing clay mixture enters the filter with the formed filter cake layer for filtration. After filtration, the oil is cooled and then further filtered by a fine filter to form decolorized oil that flows into the storage tank. When the filter cake layer accumulated on the filter screen gradually thickens and the oil output speed of the filter screen slows down, filtration is stopped. First, compressed air is used to discharge the liquid to be filtered from the filter screen. Then, steam or compressed air is used to dry the residual liquid in the filter cake layer. The slag discharge port is opened, and the filter cake layer is shaken off from the slag discharge port of the filter screen by vibrating the filter screen to complete the filter screen cleaning. Then, the oil-clay mixture is circulated to form a filter cake layer on the filter screen in preparation for the next filtration. The filter is a vertical blade filter, which includes a vertically arranged tank with an inlet, an outlet and a slag discharge port; and filter blades vertically arranged in the tank. The tank includes a tank body, a tank cover and a tank bottom, and the filter blades are detachably mounted on the side walls of the tank body from both sides. The vertical blade filter also includes a support detachably installed inside the tank and a vibrator installed outside the support. The filter blades are detachably connected to the support from the upper and lower ends. The output end of the vibrator is connected to the support. When cleaning, the vibration of the vibrator is transmitted to the support, and the filter blades vibrate accordingly to cause the filter cake layer to fall off.

2. The oil decolorization process according to claim 1, characterized in that: The filter blades are in multiple sets, and each set of filter blades includes a rectangular filter frame and filter screens located on opposite sides of the filter frame, wherein the filter screens and filter frame form a filter cavity.

3. The oil decolorization process according to claim 2, characterized in that: The vertical blade filter also includes an oil collection pipeline for connecting the multiple filter chambers to each other from the filter frame, an oil outlet pipeline for connecting the oil collection pipeline to the discharge port, and an oil storage tank.

4. The oil decolorization process according to claim 3, characterized in that: The filter frame is a hollow pipe, and a connecting pipe is provided between multiple hollow pipes to connect the inner cavities of the multiple hollow pipes.

5. The oil decolorization process according to claim 4, characterized in that: A through hole is formed on the inner wall of each hollow pipe forming the filter cavity, and the filtered oil can flow through the through hole in the hollow pipe and flow to the oil collection pipeline.

6. The oil decolorization process according to claim 2, characterized in that: The horizontal cross-section of the tank body is circular, and multiple sets of filter blades are evenly distributed inside the circle along the same diameter.

7. The oil decolorization process according to claim 2, characterized in that: The filter frames of multiple sets of filter blades are of equal height and are evenly spaced.

8. The oil decolorization process according to claim 1, characterized in that: The slag discharge port is located at the bottom of the tank, and the feed inlet is located on the side of the tank bottom, and there are two inlets.

9. The oil decolorization process according to claim 1, characterized in that: The feed inlet is located on the side of the tank body, and an overflow outlet is also provided above the feed inlet on the side of the tank body.

10. The oil decolorization process according to claim 1, characterized in that: The can lid is detachably mounted at the opening of the can body, and the bottom of the can is a cone shape with an outer diameter that gradually decreases from top to bottom.

11. The oil decolorization process according to claim 1, characterized in that: The first and second clay mixers share a single clay additive.

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