Soybean oil extraction production line
Soybean oil extraction production lines generally use various methods such as pressing and extraction to obtain crude oil with more impurities, and then refined to obtain edible refined oil.
The squeezing method of soybean oil extraction production line is divided into two kinds of ordinary squeezing method and screw squeezing method. Ordinary pressing is a method of applying pressure on soybeans. This method has not been used much, especially in industrialized large-scale production. In the screw press method, a screw shaft is installed in the cylinder of the horizontal device. After the pretreated soybean enters the screw press, the oil is squeezed out while advancing. This method can be produced continuously, but in the process of oil extraction, the protein changes to a large extent due to friction and heat.
Soybean oil extraction production line Soybean oil extraction production lines generally use various methods such as pressing and extraction to obtain crude oil with more impurities, and then refined to obtain edible refined oil. The squeezing method of soybean oil extraction production line is divided into two kinds of ordinary squeezing method and screw squeezing method. Ordinary pressing is a method of applying pressure on soybeans. This method has not been used much, especially in industrialized large-scale production. In the screw press method, a screw shaft is installed in the cylinder of the horizontal device. After the pretreated soybean enters the screw press, the oil is squeezed out while advancing. This method can be produced continuously, but in the process of oil extraction, the protein changes to a large extent due to friction and heat. The extraction method of soybean oil extraction production line uses a solvent that can dissolve oil to extract the oil from the preform through the effects of wetting and penetration, molecular diffusion and convection diffusion. Then, the mixed oil composed of solvent and fat is separated, and the solvent is recovered to obtain crude oil. The most common application in the actual production of my country's oil industry is the extraction method. The solvents include several aliphatic hydrocarbons such as n-hexane or light gasoline. Among them, light gasoline is the most widely used solvent, but the biggest disadvantage is that it is flammable and explosive, the composition is complex, and the boiling point range is wide. The extraction rate of oil is as high as 99% Soybean oil extraction production line method difference The processing technology of soybean oil extraction production line is different The processing technology of squeezed oil is "physical squeezing method", and the processing technology of extracting oil is "chemical extraction method". The production process of the physical pressing method requires that the raw materials must be selected. The oil is crushed, steamed, and squeezed after removing impurities and stones to separate the oil from the oil. The fried seeds are added during the squeezing process, and they are pressed by the press , Made with high-tech natural filtration and purification technology. It maintains the original taste of soybeans, has a mellow fragrance, is rich in vitamin E, has a long shelf life, and does not contain any additives, does not contain solvent residues and soap content. It is a pure natural green food produced by combining modern technology with traditional technology . The extraction method adopts the organic solvent extraction method. The oil is fully combined with organic solvents such as "No. 6 light gasoline" (commonly known as "No. 6 solvent oil") and then extracted. Therefore, organic substances such as n-ethane, which are toxic to the human body, are extracted. It is difficult to completely remove. Only after the scouring meets very strict standards, can you eat with confidence, otherwise, it is easy to have a harmful effect on the human body; but in the high temperature scouring, it is inevitable that some vitamins will be lost. In China, except that some soybean oil is produced through the pressing process, due to the high oil yield of the extraction method, most corn oil, soybean oil, cottonseed oil, etc. are basically processed and manufactured by the "No. 6 light gasoline" extraction method. Soybean oil extraction production line has different nutrients Squeezed soybean oil has complete color, aroma and taste, and retains the characteristics of various nutrients. The extracted oil is colorless and tasteless, most of the nutrients are destroyed after processing. The edible oil standard drafted by the National Grain Administration of China has been promulgated and implemented, and the old standard used in my country has been cancelled. The new standard stipulates that the words "squeezed" and "extracted" should be marked on the product label for pressed soybean oil and extracted soybean oil. With the advancement of society and the improvement of people’s living standards, dietary emphasis on nutrition and health has become people’s pursuit. The transparency of the soybean oil production process is to let consumers understand the soybean oil production process and give consumers the right to know. Give the choice to consumers. The raw material requirements of the soybean oil extraction production line are different "Squeezed soybean oil" adopts pure physical pressing method, which retains the original flavor of soybeans, so the requirements for soybean raw materials are very strict, the raw materials are required to be fresh, the acid value and peroxide value are low, so the price is relatively high; at the same time, because Only by pressing, the residual oil in the soybean cake is high, and the output rate of the pressed oil is relatively low. So the price of squeezed soybean oil is relatively high. Process flow of soybean oil extraction production line Soybean oilseed cleaning→screening→wind separation→specific gravity de-stone→magnetic separation→side-by-side mud cleaning→dust removal→soybean moisture adjustment→crushing→softening→rolling→squeezing and puffing of soybeans→soybean oil leaching→mixed oil treatment →Purification and preheating of mixed oil→Evaporation of mixed oil→Stripping of mixed oil→Soy crude oil (crude oil)→Filtration→Hydration and degumming→Alkali refining and deacidification→Decolorization→Deodorization→Product oil If the technological process requires the extraction of phospholipids, the crude oil needs to be cleaned and dried before the rehydration and degumming. dry. Raw material cleaning of soybean oil extraction production line Purpose and requirements: Some impurities will be mixed into oil during harvesting, transportation and storage. Although the oil is usually cleaned before storage, the oil will still carry a small amount of impurities after the preliminary cleaning, which cannot meet the requirements of oil production. Therefore, after the oil enters the production workshop, it must be further cleaned to reduce its impurity content to the process Within the required range, to ensure the effect of the oil production process and product quality. Cleaning method:
Screening uses the difference in particle size between oil and impurities, and with the help of the relative movement of the oil-containing material and the screen surface, the impurities larger or smaller than the oil are removed through the screen holes. The commonly used screening equipment for soybean oil extraction production line includes vibrating screen, plane rotary screen, rotary screen and so on. Many screening equipment have an important working component, namely the screen surface. The size and shape of the sieve should be selected according to the actual size of the soybean particles. ②Wind selection: According to the difference in specific gravity and aerodynamic properties of oilseed soybeans and impurities, the method of separating impurities in oil by wind is called winnowing. Air separation can be used to remove light impurities and dust in oil, and it can also be used to remove heavy impurities such as metals and stones. Generally, the air separation equipment selected by oil plants is mostly used in combination with screening equipment, such as suction flat screen, vibration cleaning The sieve, plane rotary drying, etc. are equipped with a winnowing device.
Removing stone by specific gravity method:
This method is based on the difference in the specific gravity and suspension speed of oilseed soybeans and stones, and uses the combined action of an inclined screen surface with certain movement characteristics and the airflow passing through the screen surface to achieve the purpose of grading and removing stones. Soybean oil extraction production line commonly used suction specific gravity stone remover, which is characterized by negative pressure inside the stone remover when working, which can effectively prevent dust from spreading, and the single machine has a large output, but a separate suction dust removal system is required. The blower specific gravity stone remover is equipped with a fan and has a simple structure, but the working conditions are poor and the output is small. It is only used in small oil processing plants. ④Magnetic separation: Magnetic separation is a method of using magnetic force to remove magnetic metal impurities in soybeans. The application of magnetic separation is to use the magnetic difference of various ores or materials to carry out the separation process under the action of magnetic force and other forces. The equipment generally used for magnetic separation includes permanent magnetic drum magnetic separator, cylindrical magnetic separator, drum type iron suction machine, and charged electromagnetic iron suction machine. ⑤ Cleaning of mud side by side: Mud that has a shape and size similar to or equal to that of soybeans, and a specific gravity similar to that of soybeans, is called side-by-side mud. Rapeseed, soybean, and sesame have more side-by-side mud. When cleaning the side-by-side mud, the mechanical properties of the mud block are different. The oilseeds containing side-by-side mud are firstly milled or beaten to crush the side-by-side mud, that is, to grind the mud, and then the mud ash is screened or winnowed. The equipment used in soybean oil extraction production line grinding mud mainly includes rubber roller grinder, vertical circular beating sieve and so on. ⑥Dust removal: The dust contained in the oil not only affects the quality of the oil and meal, but also flies up during the cleaning and transportation of the oil. The dust that flies up pollutes the air and affects the environmental sanitation of the workshop, so it must be removed. The method of dust removal is to seal the dust source first, reduce the scope of influence of dust, and then set up a dust removal air net to collect the dust-laden air and remove the dust from it. The dust collectors commonly used in soybean oil extraction production lines include centrifugal dust collectors and bag dust collectors. Consider the cost and other factors here, and use a centrifugal dust collector. Soybean oil extraction production line soybean moisture adjustment Oil moisture has an impact on the physical properties of the oil, such as elasticity, plasticity, mechanical strength, thermal conductivity, and organizational structure, and these physical properties of the oil directly affect the effect of oil processing. Oil moisture will also affect the activity of various enzymes in the oil, and the action of enzymes can change the properties of certain components in the oil, thereby affecting the quality and yield of products and by-products. If the oil humidity is too high, it must be dried. Generally, convection drying and conduction drying are used. If the oil humidity is too low, humidify it. Generally, saturated steam and water are mixed and sprayed onto the conveying oil, which can achieve a better wetting effect and the time for the moisture to be uniform is also short. Crushing of soybean oil extraction production line Before the soybeans are rolled, the large-grain soybeans must be crushed. The purpose is to make the soybeans have a certain particle size by crushing to meet the rolling conditions. The surface area of the soybeans after crushing is increased, which is beneficial to the transfer of temperature and moisture during softening, and the softening effect is improved. The soybeans are required to have uniform particle size after crushing, no oil, no agglomeration, less powder, and the particle size meets the requirements. Soybean crushing particle size is 4~6 petals, and the powder degree of crushed beans is controlled to not exceed 10% through 20 mesh/inch sieve. The maximum diagonal length of the pre-pressed cake after crushing is 6~10mm. In order to meet the requirements of crushing, the moisture content of the oil must be controlled during crushing. If the moisture content is too high, the oil is not easy to be broken, and it is easy to be squashed. Out of oil. It will also cause the crushing equipment to be unsuitable for eating, reducing the output, etc.; if the water content is too low, the powder degree of the crushed oil will increase, and the oily powder will easily stick together to form a mass. In addition, the temperature of the oil The crushing effect has an impact. Hot oilseeds have a small powder degree after crushing, while cold oilseeds have a large powder degree after crushing. Generally, soybeans are suitable for crushing with a moisture content of 10% to 15%. There are several methods for crushing oil, such as impact, shearing, squeezing and milling. Commonly used crushing equipment for soybean oil extraction production line includes toothed roller crusher, hammer crusher, and disc sheller. Softening of soybean oil extraction production line Softening is to improve the elastoplasticity of the oil by adjusting the moisture and temperature of the oil, so that it has the best conditions for rolling, reducing the powder and sticking phenomenon during rolling, and ensuring the quality of the blank. Softening is mainly used for oils with low oil content, low water content and high shell content with poor plasticity and hard texture. Soybeans have low oil content and poor plasticity, so they are generally softened before rolling. The rolling temperature should depend on the moisture content of soybeans. When soybean moisture is 13%~15%, the softening temperature is usually controlled at 70~80 degrees, and the softening time is 15~30 minutes. The softening equipment commonly used in soybean oil extraction production line includes layered softening pot and drum softening pot. Rolling stock of soybean oil extraction production line The rolling stock of the soybean oil extraction production line is a process in which the oil is pressed from granular to flake by the action of machinery. The purpose of the rolling stock is to destroy the cell tissue of the oil, increase the surface area of the oil, and shorten the distance of the oil outflow, which is beneficial to the extraction of the oil and also helps to improve the evaporation effect. Rolling stock is the key to pretreatment, which is related to the output and quality of grease. The key to the billet is the operation of the billet mill. In order to ensure the quality of the rolled slab, the moisture and temperature of the material before the rolled slab must be strictly controlled. It is better to install a softening box on the rolling mill to avoid excessive water content and temperature loss after softening. Before driving, check the working condition of the rolling mill carefully. If you find that the thickness of the billet at both ends is uneven, or the unrolled oil is mixed into the billet, you should stop the machine for inspection and adjust the rolling distance (should be balanced on both sides and avoid adjustment. Too tight). Check whether the scraper is close to the surface of the roll to prevent sticking to the roll. Pay attention to the uniformity of the flow to prevent no-load operation. Generally, the thinner the oil is rolled, the more cell tissues will be destroyed, and the better the oil extraction effect will be. The requirements for the rolled billet are that the billet is thin and uniform, with low powder density and no oil leakage. Regardless of whether the squeezing method or the leaching method extracts oil, the thickness of the blank has a great influence on the oil yield. The influence of soybean green thickness on the oil yield Generally, the thickness of soy slab should be less than 0.3mm. Rolling equipment can be divided into two types of in-line rolling mills and parallel rolling mills. There are two types of in-line billet rolling mills: three-roll billet mill and five-roll billet mill. Parallel billet mills include single-roll billet mills and double-roll billet mills. Extrusion of soybean oil extraction production line Grease extrusion is the process of using extrusion equipment to transform the crushed, rolled or whole grain oil into porous expanded pellets. Extrusion is a high-temperature, short-term process. Commonly used extruders are single-screw and twin-screw. According to the water content during extrusion, they can be divided into wet and dry extrusion methods. The extrusion and expansion pretreatment of oil is mainly treated by a low-moisture wet method with a single screw extruder, that is: the oil is cleaned and rolled into the extruder, and then extruded by heating, pressurizing, gluing and decompression. forming. Generally speaking, in the extrusion process, the extrusion temperature can reach about 110-200°C, and the residence time in the extruder is 1 to 3 minutes, which is only 5 to 105. After the oil is extruded under high temperature, humidity and heat, the following purposes can be achieved: (1) Gelatinization of starch and denaturation of protein. Due to expansion, it can quickly and completely destroy the cell structure, and the oil can evenly diffuse out and is easy to extract. (2) It can inactivate various enzymes, especially lipohydrolase, oxidase, etc. After extrusion, the inactivation rate is more than 95%. (3) It can increase the oil yield, increase the output, and reduce the solvent loss. Oil extrusion and puffing equipment: There are two main types of oil extrusion and puffing equipment. One is an extruder used for low oil content green bodies, the so-called closed-wall extruder, and the other is used for high oil content. The green body extruder is the so-called slotted wall extrusion extruder. The extrusion section is suitable for the extraction process of soybean meal as fish feed, which can relatively increase the bulk density and increase the processing volume. But it is not suitable for the extraction process of soy protein in the later stage. In the later stage, if soy protein isolate or soy protein concentrate is extracted. The soybean flakes dried after embossing can be leached directly at low temperature. Soybean oil extraction production line oil leaching 1; Basic principles and elements of oil production by leaching method Soybean oil extraction production line leaching method oil production is to use a solvent that can dissolve oil, through wetting and penetration, molecular diffusion and convection diffusion to extract the oil from the embryo, and then separate the mixed oil composed of the solvent and the fat, and then recover it. To obtain crude oil from the solvent, the solvent in the soybean meal must also be recovered to obtain the leached meal. In this process, the basic elements are the solvent and raw material, as well as the leaching method and process parameters that determine the leaching effect. 1, 1, the choice of solvent The ideal leaching solvent should meet the following basic requirements: ①It can dissolve grease in any proportion at room temperature or low temperature; ②The selectivity of the solvent is better, that is, it does not dissolve other ingredients except grease. ③Stable chemical properties, stable to light and water, and can't change chemically after heating, evaporating and cooling. ④ The solvent is required to have a low boiling point, low specific heat and low latent heat of vaporization, and is easy to separate and recover from meal and oil. ⑤ The solvent itself is non-toxic, neutral, has no peculiar smell, and does not pollute. ⑥The solvent does not react chemically with oil, meal or equipment materials. Several aliphatic hydrocarbons such as industrial hexane or light gasoline are the most commonly used leaching solvents in the actual production of China's oil industry. Among them, light gasoline is one of the most widely used solvents in China. It is a low boiling point fractionation product of petroleum raw materials and meets the above-mentioned basic requirements of solvents. But the biggest disadvantage is that it is flammable and explosive. When the air content reaches 1.25 to 4.9%, there is a danger of explosion. At the same time, light gasoline has a complex composition and a wide boiling point range. In addition, acetone, methyl ethyl ketone, isopropanol, butane and some compound solvents can be used for oil extraction, and some are being studied and tried. 1, 2, the requirements for the blank Soybean raw materials are pretreated, so that the structure and properties of the raw material should meet the requirements of the extraction process to obtain a good extraction effect. ① The more thorough the cell destruction, the better. ②The material embryo is thin and strong, and the powder degree is small. In this way, the extraction distance is short and the contact area between the solvent and the embryo is large, which is beneficial to improve the leaching efficiency. The soybean direct extraction method requires the thickness of the raw material to be 0.2～0.3mm. ③The water content is appropriate, and the leaching solvent is insoluble in water. If the water content in the raw material is high and the internal voids are full of water, it will affect the penetration of the solvent and the dissolution of grease. Therefore, the moisture content of the material embryo should be low. (<13%, 5～7%) ④ Proper temperature, high raw material temperature, low oil viscosity, easy flow, good leaching effect, but it should be noted that the raw material temperature should not exceed the boiling point of the solvent to avoid vaporization of the solvent. Therefore, the temperature of the blank is generally controlled at 45～55℃, and should not exceed 60℃. 2; extraction process Solvent extraction of soybean oil extraction production line is the main process of extracting oil. In the leaching process, a specific extraction device is used to achieve full contact between the solvent and the raw material in a reasonable extraction method, so as to achieve the purpose of fully dissolving the oil and extracting the oil. The good extraction effect is ensured by the correct extraction method and suitable leaching process conditions. (1) The extraction method refers to the contact method between the solvent and the embryo during the oil extraction process. There are three types: ① Immersion type: The material embryo is always immersed in the solvent (or dilute mixed oil) to complete the leaching process. This method has a short leaching time and a large amount of mixed oil, but the concentration is relatively thin, that is, the amount of grease in the mixed oil is less, and the mixed oil contains more slag. ② Percolation type: The contact process between the solvent and the raw material is always spray-permeable. After leaching, a thick mixed oil with a lot of grease can be obtained, and the amount of residue in the mixed oil is also small. But the leaching time is longer. ③Soaking and spraying mixed type: soak the raw material first, and then spray and infiltrate, which improves the leaching rate and oil output efficiency, and reduces the leaching time. According to the type of extractor, the leaching method is divided into batch type and continuous type. The leaching method of soaking kettle is batch type. Other commonly used extractors are continuous. However, no matter which leaching method, the countercurrent leaching process is basically adopted. During the solvent leaching process, the oil in the embryo is continuously extracted by solvents of different concentrations, so that the residual oil in the meal is gradually reduced to the specified index, and the concentration of oil in the solvent is gradually increased in the reverse direction and finally discharged and recovered. (2) Extraction process conditions of soybean oil extraction production line ① The extraction temperature and extraction time, and the requirements of extraction temperature are consistent with the temperature of the raw material, and the solvent should be preheated first. Theoretically speaking, the longer the extraction time, the better the effect and the lower the residual oil rate in the meal. In actual production, the oil extraction process can be divided into two stages. The first stage is mainly to dissolve the oil in the damaged cells by a solvent. The extraction volume is large and the time is short. Generally, the total oil content can be extracted only in 15-30 minutes. 85 to 90% of the cytotoxicity; in the second stage, the solvent needs to penetrate into the undamaged cells, which takes a long time and is low in efficiency. The best "economic time" should be considered according to the actual situation. ②The penetration rate of the solvent is the amount of solvent that passes through a unit area in a unit time, that is, the penetration rate. It is generally believed that the penetration rate for the soybean extraction process is 360 liters/decimeter 2·hour. ③The ratio of solvent consumption to solvent. Solvent consumption is usually measured by "solvent ratio". The definition of solvent ratio is the ratio of the weight of the solvent used to the weight of the material to be immersed in a unit time. The size of the solvent ratio directly affects the concentration of the mixed oil after extraction, the concentration difference between the inside and outside of the embryo during extraction, the leaching rate, and the residual oil rate. Generally, the solvent ratio of multi-stage mixed leaching is (solvent: material) Within the range of 0.3～0.6:1. ④Draining time and soluble content of wet meal. After the extraction process, it is always hoped that the residual solvent in the meal should be as little as possible to reduce the equipment load of the soybean meal desolventization. Therefore, the draining time should be prolonged appropriately. The limit of the soluble content of the wet meal of the soybean embryo once soaked is 25-30%, and the draining time is about 20 minutes. (3) Type of extractor of soybean oil extraction production line It is broadly divided into continuous type and batch type. According to the extraction method, it is divided into immersion type, osmotic type and mixed type. The equipment for each extraction method is divided into many structural types. Among them, the single-kettle and multi-kettle combined type have been gradually eliminated due to intermittent production and high labor intensity. The flat-rotation type and ring type drag chain type have high extraction efficiency and advanced technology, which have been widely used, but the cost is relatively high.
3; Desolubilization of wet meal The "wet meal" from the extractor usually contains 21-40% solvent. It must be desolventized and dried to recover the solvent and reduce the moisture in the meal, so that it can reach the specified residual solvent quantity index (500-1000ppm) and Store moisture safely. The process of recovering the solvent is called desolventization, and the process of drying to remove water is called roasted meal. 3, 1. The basic process of desolventizing roasted meal in soybean oil extraction production line The desolubilization stage mainly uses direct steam to pass through the material layer. After the two contact heat transfer, the solvent boils and volatilizes. Direct steam is used as a heat source for heating the solvent, and it is also steamed out with the solvent under pressure. But at the same time, the water vapor will partially condense into water droplets and remain in the meal while heating the solvent, increasing the moisture of the soybean meal; therefore, it needs to be treated with the roasted meal to remove the moisture. The roasted meal is generally heated by indirect steam to remove the moisture. ,3, 2. The basic method of desolventizing roasted meal in soybean oil extraction production line
The high-temperature desolventization method uses direct steam with a gauge pressure of 0.5kg/cm2 to pass through a layer of about 1.5m thick, steaming for 30-40 minutes, and then drying with indirect steam at a gauge pressure of 4-5kg/cm2 to remove water. In order to meet the specified water content requirements. The meal temperature is above 105℃. The denaturation of meal protein is seriously unfavorable for further processing and utilization of protein. Generally sold directly as a feed bucket.
②Flash pre-desolventization (low-temperature desolventization) method, using high-speed flowing superheated solvent vapor to blow the wet meal to the cyclone separator to remove the solvent in a very short time. The desolventized meal enters the feeder by its own weight, and evenly enters the steaming and drying cooler. The steam-drying cooler maintains a vacuum degree of 200-400mmHg, the upper part is depleted with a small amount of direct steam, and the lower layer is blown into dry cold air to remove moisture. In this way, the heating time of soybean meal is short, the steaming temperature is low, and anhydrous steam acts directly, and the meal output temperature does not exceed 70-80°C, so the protein denaturation rate is low, only 1 to 2%, which is beneficial to the further development and utilization of protein. It is suitable for reprocessing and extracting soy protein.
Mechanical pre-demelting method, in order to save steam, sometimes a mechanical extrusion method is used to first extrude part of the solvent, and then perform thermal demelting and roasting. Desolubilized roasted meal equipment mainly includes multi-stage horizontal dryers, high-layer drying and steam-drying coolers.
4; Evaporation of mixed oil in soybean oil extraction production line The oil content of the concentrated mixed oil obtained from the leaching process is generally 10-30%. To obtain crude oil, the solvent must be steamed off from the mixed oil. The leaching method stipulates that the residual solvent index in crude oil is 50-500ppm. The solvent is removed from the mixed oil by using the characteristic that the boiling point of the solvent is lower than the boiling point of the grease, and heating is used to make the mixed oil boil, so that the solvent is vaporized and the grease is retained. However, because the solvent and grease are homogeneous mutual solutions, under certain pressure or vacuum conditions, the boiling point of the solvent tends to increase as the concentration of the mixed oil increases. It can be seen that only heating and evaporation can not remove the solvent in the mixed oil, so the method of steam stripping must also be used. The conventional mixed oil separation can be divided into two steps: ① The mixed oil evaporates, that is, it is heated by indirect steam to remove the solvent by evaporation. ② Stripping. At a temperature of 110-115°C, direct steam with a pressure of 0.2-0.5kg/cm2 is introduced, so that a small amount of solvent in the mixed oil is taken away with the steam to remove the residual solvent. Evaporation equipment often uses long tubes or evaporators, and stripping equipment includes rising film, tubular, and stripping towers. Soybean oil extraction production line evaporates under negative pressure, and the secondary steam in the evaporator is led to the first evaporator to heat the mixed oil under negative pressure, so that the soybean oil can save energy and reduce the color of crude oil. 5; solvent recovery The exhaust gas is recovered through desolventizing roasted meal and mixed oil evaporation and stripping process. The equipment includes: condenser, water separator, distilled water tank and tail gas recovery device, etc. Exhaust gas recovery devices include water absorption tower, refrigeration recovery device, mineral oil recovery device, etc. The conventional mixed oil separation can be divided into two steps: ① The mixed oil evaporates, that is, it is heated by indirect steam to remove the solvent by evaporation. ② Stripping. At a temperature of 110-115°C, direct steam with a pressure of 0.2-0.5kg/cm2 is introduced, so that a small amount of solvent in the mixed oil is taken away with the steam to remove the residual solvent. Evaporation equipment often uses long tubes or evaporators, and stripping equipment includes rising film, tubular, and stripping towers. Refining of soybean oil 1; Grease degumming Crude oil is a colloidal system, in which phospholipids, proteins, mucilage and glycosyl diglycerides, etc., are named as peptic impurities of grease due to the formation of a sol system with triglycerides. The presence of peptizing impurities not only affects the stability of the oil, but also affects the technological effects of oil refining and deep processing. For example, oil is easy to emulsify in the process of alkali refining, which increases the difficulty of operation, increases the loss of oil refining and the consumption of auxiliary materials, and reduces the quality of soapstock; in the decolorization process, it will increase the consumption of adsorbent It can reduce the decolorization effect; the undegummed oil cannot be subjected to physical refining and deodorization operations, nor can it be further processed. Therefore, the refining of crude oil must first remove peptic impurities. The process of applying physical, chemical or physical chemical methods to remove desoluble impurities in crude oil is called degumming. Degumming methods include hydration degumming, acid refining degumming, adsorption degumming, thermal polymerization degumming and chemical reagent degumming, etc. The most common applications in the oil industry are hydration degumming and acid refining degumming. The refining of edible fats and oils mostly uses hydration degumming, and strong acid refining degumming is used for the refining of industrial oils. Generally, the operation of hydration and degumming is adopted for grease. Hydration and degumming is the use of the hydrophilicity of peptic impurities such as phospholipids. A certain amount of hot water or dilute alkali, salt, phosphoric acid and other electrolyte solutions are added to the hot crude oil under stirring to make the peptic impurities absorb water and agglomerate. , And then a method of degumming oil by sedimentation and separation. In the process of hydration and degumming, the main substances that can be aggregated and settled are phospholipids, as well as proteins combined with phospholipids, glycosyl diglycerides, mucus and trace metal ions. The main equipment of hydration and degumming can be divided into hydrator, separator, dryer and desolvator according to the process function, and can be divided into batch type and continuous type according to the continuity of production. 2; Alkali refining and deacidification Crude oil contains a certain amount of free fatty acids. The process of removing these fatty acids is called deacidification. Commonly used methods for deacidification are alkali refining, chemical refining, and steam distillation, physical refining. Alkali refining and deacidification method is to achieve the purpose of deacidification by adding alkaline aqueous solution to the oil, crude oil or hydrated degummed oil, and neutralizing chemical reaction. The chemical neutralizer commonly used in the alkali refining and deacidification process is caustic soda. The addition amount of NaOH depends on the quality of the raw oil. The total alkali consumption is detailed in the following steps. It includes three parts. One is the alkali used to neutralize free fatty acids. It is the theoretical base, the second is the phosphoric acid added in the process of neutralizing the acid reaction, and the other part is the extra base added to meet the process requirements, which is called the excess base. The concentration of lye is generally 12~240Be. The excess alkali is selected according to the process. Generally, it is 0.10.25% of the oil volume. The continuous production line is calculated at 25% of the theoretical alkali. The neutralization chemical reaction is completed in the mixing device, stagnant reaction tank and related pipelines. The soapstock is separated with the aid of a centrifugal separator. It is commonly known as desoaping. The residual soap in the desoaping oil is washed by light lye and re-refined. Hot water washing, water washing, and then separating the net oil with the aid of a centrifugal separator, and then removing the residual water and residual solvent through a vacuum drying desolvator to obtain the national standard third and fourth grade refined oil. Or enter the decolorization, deodorization, and degreasing process to be refined and processed into national standard first or second grade product oil. 3; Decolorization All kinds of fats have different colors because they contain different pigments. For example, chlorophyll makes oils dark green; carotene makes oils yellow; during storage, sugars and proteins decompose to make oils brown; gossypol makes cottonseed oil dark brown. In the aforementioned refining method, although part of the pigment in the fat can be removed at the same time, it cannot reach a satisfactory level. Therefore, for the production of high-grade oils-salad oil, cosmetic oil, light-colored paint, light-colored soap and margarine, the color should be light. Only the refining method mentioned above cannot meet the requirements and must be decolorized. The processing can only do so. The methods of decolorization of grease include sunlight decolorization method (also known as oxidation method), chemical decolorization method, heating method and adsorption method. The most widely used method is the adsorption method, which is to add certain substances with strong adsorption capacity (acid activated clay, bleaching earth, activated carbon, etc.) to grease, and absorb and remove pigments and other impurities (proteins, mucus, resins, etc.) in the oil under heating. Class and soap etc.). Process flow: intermittent decolorization is a process in which grease and adsorbents complete the decolorization process through a one-time adsorption balance under intermittent conditions. The decolorized oil is transferred to the decolorization tank through the storage tank, and after heating and drying under vacuum, it fully contacts with the adsorbent sucked in from the adsorbent tank under stirring to complete the adsorption balance, and then is cooled by the oil pump and pumped into the filter press to separate the adsorbent. After filtering, the decolorized oil is collected into the storage tank, and transferred to the deodorization process by vacuum suction or oil transfer pump, and the adsorbent filter cake in the filter press is transferred to the treatment tank to recover the residual oil. 4; Deodorization Pure fatty acid triglycerides are colorless and odorless, but natural oils and fats have their own special odor (also called odor). Odor is an oxidation product, which is further oxidized to generate peroxy compounds, which are decomposed into aldehydes, thus making the oil taste. In addition, odors such as solvent, soap, and earthy odors are also produced during the oil production process. The process of removing the peculiar smell (flavoring substances) of fats and oils is called "deodorization" of fats and oils. The deodorization of the leached oil (called "desolvation" when the process parameters fail to meet the deodorization requirements) is very important. Before deodorization, hydration, alkali refining and decolorization must be carried out to create good deodorization conditions, which is conducive to residual solvents in the oil and Removal of other odors. Deodorization methods There are many deodorization methods, including vacuum steam deodorization, gas blowing, hydrogenation, and polymerization. The vacuum steam deodorization method is the most widely used and the best effect at home and abroad. Vacuum steam deodorization is a process in which superheated steam (under vacuum) is used in the deodorization pot to remove odorous substances in the oil. The principle of vacuum steam deodorization is that water vapor passes through the oil containing odorous components, vapor-liquid contact, the water vapor is saturated with the odorous components that volatilize, and is selected and removed according to the partial pressure ratio. Refined oil After the above-mentioned operation process, the oil produced is the finished oil.
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