Crude rice bran oil contains free fatty acids, bran wax, phospholipids, proteins, and pigments. As edible oil, it needs to be further purified and refined to remove these impurities. Rice bran oil is known as one of the most difficult to process fats in the world. It is not only difficult to extract because of its high powder content and high starch content, but also because of its dark color and high acid value, which leads to the yield of refined oil. Low. After research, Jinan Yueheng Machinery has developed a set of advanced technology and equipment suitable for rice bran oil processing. It has applied rice bran preservation, puffing leaching, physical decolorization, physical deacidification and other processes, and can process first-class rice oil that meets national standards. .
The rice bran leaching complete set of equipment specially developed for the characteristics of rice bran adopts an extractor specially designed for rice bran leaching and a rice bran steaming machine, which can achieve the leaching and desolventization of rice bran, and can run continuously for several years without failure. The mixed oil adopts negative pressure evaporation technology. The first steaming, second steaming, and stripping all work under vacuum. Compared with atmospheric evaporation, the evaporation temperature is low, which can reduce the acid value of the bran oil, reduce oxidation, and the color of the leached bran oil is light , Good quality, reduces the burden of the subsequent refining process, and can save a lot of steam consumption and reduce solvent consumption.
Rice bran oil leaching complete equipment
Process flow: rice bran particles → leaching → filtration → evaporation → steam stripping → leaching crude oil
Process description: The rice bran particles in the pretreatment workshop are transported to the leaching workshop, and enter the extractor through the 1# buried scraper conveyor and sealed auger. With the operation of the extractor, the mixed oil with decreasing concentration is sprayed, and finally fresh Solvent, reduce the oil content in the material to less than 1%. The wet rice bran meal is sent to the steaming machine from the 2# buried scraper conveyor and sealed auger, sprayed directly into the steam to remove the solvent, and transported to the meal store for packaging. The mixed oil obtained by solvent leaching grease is filtered, precipitation of mechanical impurities, evaporation, steam stripping and other processes to remove the solvent to obtain leached crude oil.
The mixed oil adopts negative pressure evaporation technology, using the secondary steam of the steam-off machine as the heat source. The first steaming, second steaming and stripping all work under vacuum, which reduces the evaporation temperature, improves the quality of crude oil, and saves steam consumption. .
The solvent vapors from steaming off, first steaming, second steaming, steam stripping, and leaching are recovered through the corresponding condensers. The condensate is concentrated in the liquid collecting tank, and after entering the integrated container for water separation, the solvent is pumped into the extractor and enters the next cycle. , The separated water will be discharged after being boiled in the cooking tank. The free gas of each condenser enters the balance tank, then enters the final condenser, and the tail gas is vented after the solvent is recovered.
Main equipment: extractor, rice bran special steaming machine, meal trap, long tube evaporator, inclined plate stripping tower, condenser, integrated vessel, cooking tank, tail gas absorption tower, etc.
Main features: The equipment is specially designed for rice bran leaching, using negative pressure evaporation process, low residual oil, low dissolution consumption, good quality and light color of leached raw bran oil.
First-class rice bran oil refining complete equipment
The difficulty in refining rice bran oil is that the oil contains more free fatty acids, waxes, bran powder and pigments. The main adverse effect of high free fatty acid content is to reduce the refining yield of rice bran oil; rice bran oil wax is saturated C16-C20 fatty acids and saturated C24 Rice bran varieties with more wax will produce rice bran oil with a wax content of up to 8%, while the wax content of rice bran oil produced by most rice bran varieties is 2-4%. The wax is often emulsion in the refining process. Therefore, the yield is reduced, and it is easy to adhere to the bleaching earth, which requires more bleaching earth to effectively decolorize during processing. The wax will cause the rice bran oil to appear opaque at room temperature, which often limits consumers’ interest in rice bran oil. If the wax content exceeds a certain limit, the rice bran oil cannot be used for frying; the content of bran powder in the rice bran oil can be 0.5%-10% or higher, too high content of bran powder will cause mist and reduce the output of refined rice bran oil. The bran powder can also settle in the oil tank, contaminate the equipment, and cause frequent cleaning of the equipment. The bran powder can also cause premature damage to the seals of transmission equipment such as water pumps, mixers and centrifuges due to friction; rice bran oil usually contains a variety of Vegetable oil pigments, such as chlorophyll, xanthophyll, carotenoids, carotenoids, and brown pigments, among which the chlorophyll value can be as high as 20PPM or more, which brings certain difficulties to decolorization.
The characteristics of rice bran oil determine that the traditional alkali refining process has large alkali refining losses and high refining costs. In order to produce qualified first-level rice bran oil and reduce costs, Zhongtian Jingu has developed a complete set of rice bran oil physical refining processes and equipment. The complete set of equipment adopts physical refining technology, including 12 processes including hydration degumming, water washing, drying, dry degumming, decolorization, filtration, deoxygenation, physical deacidification, delayed decolorization, deodorization, dewaxing, and degreasing. After refining The acid value of the first grade rice bran oil is less than 0.2mgKOH/g, and the color is less than Y20, R2. The freezing test meets the market demand, and the acid value of the mixed fatty acid is 150-190mgKOH/g.
The combined deacidification and deodorization tower and rice bran oil physical refining patented technology developed by Henan Taixing Cereals and Oils Machinery Equipment Co., Ltd. can reduce the consumption of refined caustic soda and activated carbon, and can effectively reduce the peroxide value and prevent the oil from turning back when the oil is deodorized at high temperature. , Acid return, low production cost, high acid value of fatty acids, and good capture effect. After our company’s development and promotion, it has set off a trend in China, and successfully built a number of rice bran oil refining production lines.
Process flow: crude oil→hydration degumming→water washing→drying→dry degumming→decolorization→filtration→deoxygenation→heat exchange→heating→physical deacidification→delay decolorization→heating→deodorization→heat exchange→cooling→dewaxing→ Degreasing → refined oil
Process description: The crude oil is stirred and preheated to a certain temperature. According to the quality of the oil, appropriate concentrated phosphoric acid is added to stir to react, so that the gums in the oil will form oily feet, and then the oily feet will be separated, and then hot brine is added to the oil for washing. Then stand still to separate the soap water, and then enter the drying process after one or two times of the same washing to reduce the moisture content of the degummed oil to less than 0.5%. After drying, the grease is added with phosphoric acid, and the waste clay is used for dry degumming in the leaf filter. The phosphorus content is reduced to less than 10mg/kg, and then it enters the decolorization tower to use activated clay and activated carbon to decolorize. According to the color of the oil, it is necessary It is necessary to recover from time to time. The decolorized oil is then pumped into the gas separator, deoxygenated under vacuum, and then enters the oil—the oil heat exchanger exchanges heat with the deodorized oil, and the oil heated to 180°C enters the heater and is heated to 250°C When left and right, it enters the packed tower at the upper part of the combined deacidification and deodorization tower for deacidification, and then flows into the lower plate tower for delayed decolorization. The deacidified oil from the combined deacidification and deodorization tower is heated and then enters the deodorization tower for deodorization. The oil is in the structured packing. The film formed on the surface flows from top to bottom, and the stripping steam contacts the film-like oil from bottom to top in the tower to conduct mass and heat transfer. Since the filler has a large specific surface area and sufficient vapor-liquid contact, free fatty acids and odorous substances in the oil can be removed to the greatest extent. The deacidification and deodorization operation is carried out under vacuum. The fatty acid mixed steam is discharged from the top of the tower and enters the fatty acid trap to be trapped. The non-condensable gas is pumped out by the vacuum pump, and the trapped fatty acid enters the fatty acid storage tank after cooling. The deodorized oil obtained from the deodorization tower after heat exchange and cooling is pumped into the dewaxing crystallization tank, using the circulation of the coil refrigerant to cool it to the dewaxing crystallization temperature at a certain cooling rate, and then pumped into the filter after a certain period of crystal growth The machine performs solid-liquid separation to obtain dewaxed oil. The dewaxed oil is pumped into the degreasing crystallization tank, cooled to the degreasing crystallization temperature, and after a certain period of crystal growth, pumped into the filter for solid-liquid separation to obtain product oil.
The simple refining process of a small rice bran oil factory is as follows:
Crude rice bran oil → impurity removal → wax removal → hydration → alkali refining → water washing → dehydration → deodorization → refined rice bran oil
①Impurity removal——heat the bran oil to 90℃ and filter it with a filter press.
②Wax removal-the wax content in rice bran oil is generally 3%-5%. The bran wax cannot be absorbed by the human body and has no edible value. It must be removed so as not to affect the quality of the oil.
③Hydration-first heat the crude rice bran oil to 65-70°C, then add hot water at the same temperature equal to 5% of the oil under stirring, stir for 40-60 minutes, and stop heating when the temperature rises to 80°C. Stir for another 25 minutes and let stand for 4-6 hours.
④Alkali refining——The acid value of crude rice bran oil is measured before alkali refining, and the amount of alkali added is calculated according to the following formula:
Solid alkali dosage (kg) = bran oil mass (t) X acid value X 0.713
In the formula, 0.713 is the ratio of the molar mass of sodium hydroxide to potassium hydroxide.
Then make a dilute lye of 18-20oBe, and send the hydrated rice bran oil to the alkali refining tank. When the soap particles appear obviously, the steam is heated up (1℃/min), and the homemade oil and soap particles are clearly separated. Stop heating, the final temperature does not exceed 80 ℃, the stirring speed is reduced to 40r/min, and add hot salt water with a concentration of 3%-5%, when the soap particles are gray-black and have sunk, stop adding salt water and continue stirring for 10 minutes , Let stand until the soap feet sink to the bottom and the oil becomes a thin paste, release the soap feet. In the rice bran oil-sodium refining, there is a data table of the experience of determining the alkali by acid and color, as shown in the following table:
⑤Washing-heat up the rice bran oil after alkali refining to 80~94℃, add boiling water with 10%~15% oil content while stirring, stir for 15 minutes, and let stand for 1~2 hours. If the wastewater is ph When the value is close to 7, it can be discharged; if the wastewater still shows red after the phenolphthalein test, it needs to be washed until the phenolphthalein test result does not show red or the pH meter shows neutral.
⑥Dehydration——heat the oil to 105~110℃, and stir it until there is no foam on the oil surface. The water content of the dehydrated rice bran oil should be less than 0.2%.
⑦ Decolorization——heat the oil to 95~100℃, add dry activated carbon or acid clay while stirring. The added amount is about 2% of the weight of the rice bran oil. After stirring for 0.5 hours, take a sample and observe. If it meets the standard, you can enter the next process. Otherwise, it is necessary to repeat the decolorization several times until the oil is yellow and translucent.
⑧ Deodorization-mainly to remove the oxides in the oil, such as ketones, aldehydes, free acids and sulfur-containing compounds. These substances are present in the oil and make the oil show a special “odor”, so it should be removed. Deodorization usually involves passing superheated steam in a vacuum state (ie 60mmHg) to raise the oil temperature to above 220°C, treating for 4-6 hours, then reducing the oil temperature to 40-60°C, and transferring it to a cooling oil tank. After cooling, refined rice bran oil is obtained.
The quality standard of refined rice bran oil is: the color is orange-yellow and transparent, without rancidity and odor, the moisture content is less than 0.2%, the impurity is less than 0.3%, and the acid value is 5mgKLH/g.