2. Improve the processing capacity of the equipment
All kinds of oil production equipment have their rated processing capacity. Since the husk occupies a certain volume and weight, the oil production with the shell can improve the processing capacity of the oil production equipment after peeling the oil. For example, when the husk content in sunflower kernels is reduced from 8% to 3%, the processing capacity of the pre-pressing leaching equipment will increase by about 10%.
3. Reduce wear and tear on equipment
Some oil husks are very hard. If the peeling effect is not good or the kernel contains a lot of husks, it will cause strong wear and tear on the oil making equipment and cause various parts to wear quickly. For example, the wear caused by the rollers of the flaking machine, the blades of the conveying auger, especially the pressing screw, pressing bar and pressing ring of the oil press. The shelling efficiency is high, and the kernel contains less husks, which can reduce the wear and tear of the equipment, which is beneficial to production and prolongs the service life of the equipment.
4. Improve the quality of crude oil and cake
The husks of oil plants have some pigments and waxes to varying degrees. If the kernel contains a lot of shells, it will affect the appearance, taste, smell, color and transparency of the oil. For example, in addition to gossypol, cottonseed will deepen the color of wool cotton oil, and the cotton kernel contains a lot of cotton husks, and the brown pigment in the cotton husk will also deepen the color of wool cotton oil. Sunflower seed shells contain wax. When the shell content in sunflower kernels is 6-8%, the wax content in pre-pressed crude oil is 0.05-0.10%, while the wax content in leached sunflower oil is 0.10-0.35%. . The higher the shell content in the kernel, the lower the use value of the meal. Therefore, the efficiency of shelling is improved, the content of shell in the kernel is less, and the quality of the obtained crude oil and cake is correspondingly high.
5. Conducive to rolling
When the shelled oil or the kernel with high shell content in the embryo is rolled into the embryo, it is often difficult to roll into a thinner embryo. Therefore, the less shell in the kernel has good plasticity, which is conducive to embryo rolling, so that the rolled embryo can be rolled out. The thickness of the sheet is uniform and has certain elasticity and strength.
6. The leather shell can be used comprehensively
The husk mixed in the oil is not good for oil production, and the husk after peeling is separated from the kernel and can be used comprehensively. For example, cottonseed husks can be hydrolyzed to produce furfural, cottonseed husks, coconut husks and tung seed husks can be used to produce activated carbon, and sunflower seed husks can be used to make fiberboard.
(2) Shelling requirements
1. General requirements
(1) The shell breaking rate is high. Oil peeling mainly uses various peeling equipment to first break the shell of the oil with shell, and then separate the kernel and the shell. Therefore, it is required that the shell breaking rate of oilseeds should be high when peeling, so as to reduce the kernel content in the shell and reduce the leakage of seeds.
(2) There should be less leakage of seeds. Due to the different sizes of oilseeds, it is easy to cause small particles of oil to leak out without being broken during shelling, and to be mixed with the husk after the kernel husk is separated, which will increase the total loss of oil. Therefore, when the oil is peeled, the leakage of seeds should be minimized. If conditions permit, it is best to classify the oil first and then peel it off.
(3) The powder degree should be small. The powder caused by oil peeling is easy to adhere to the shell to increase the total loss of oil content, and at the same time, the high degree of powder is also unfavorable for oil production.
2. Specific requirements
(1) Shelling efficiency. The efficiency of shelling depends on two aspects: the performance of the shelling equipment and the operation process of the shelling. The combination of the two is appropriate, and the shelling efficiency is high.
Shelling rate of disc shelling machine (for cottonseed, tung oilseed, camellia oilseed): not less than 80%;
Shelling rate of blade peeler (when used for cottonseed): not less than 90%;
Shelling rate of hammer or tooth stick shelling machine (for peanuts): not less than 90%;
The peeling rate of sunflower seeds by vertical centrifugal peeling machine: up to 90%.
(2) The percentage of kernels in the shell. The kernel content in the separated shell is required to be as low as possible, and at the same time, the degree of pulverization is required to be small when peeling the shell. Otherwise, the kernel chips produced are too fine, and the oil will be easily squeezed out, so that there is grease on the shell and kernel chips are mixed into the shell. oil yield. In addition, the separation effect is also related to the equipment and operation process. The proper combination of the two can achieve less kernel content in the shell. The specific requirements for the kernel content in the shell are:
Cottonseed hulls: below 0.5% (including kernels in whole kernels in hulls);
Peanut shell: below 0.5%;
Sunflower seed husk: below 0.5%;
Tung seed husk: below 0.5%.
(3) The shell content in the kernel. For cottonseed, the husk content in the kernel of the oil extracted by the screw oil press is generally required not to exceed 6%; the husk content in the kernel of the hydraulic oil press should not exceed 10%. When other oils are pressed to make oil, the shell content in the kernel should be reduced as much as possible, and the general requirement is below 5. The hull content in the kernels of sunflower seeds after peeling and separation generally does not exceed 2%.
When the meal is used as the raw material for edible protein, the requirements for the content of shell in the kernel are more stringent, and the number of shells in the kernel should be reduced as much as possible, and the content of cellulose should be reduced to increase the edible value of the meal.
Whether the above requirements can be achieved depends on the quality of the oil, whether the operation process is correct, and whether the peeling and separation equipment is reasonable. When the oil moisture is too low, the shell is brittle and easy to break when peeling, the shell kernel is highly pulverized, and it is difficult to separate the kernel and shell; when the equipment is used unreasonably, it will cause leakage of seeds or large pulverization of kernel and shell, which will also affect the peeling effect. .
2. Shelling equipment
(1) Knife board peeling machine
The blade sheller is a special equipment for cottonseed shelling, and it is an ideal equipment commonly used in large and medium-sized oil plants. It is characterized by high rate of whole kernels, small powder degree, easy separation of kernel shells, but easy seed leakage and low shelling efficiency, so it is often used in conjunction with a vibrating screen, so that the whole seeds can be returned and peeled again.
The cutter plate shelling machine is composed of a feeding hopper, a feeder, a regulator, an iron removing device, a rotating drum, a cutter plate, a cutter plate seat and other components.
(1) Feeding mechanism. The feeding mechanism consists of a feeding hopper, a feeding roller and a regulator on the side of the feeding hopper, which is used to control the feeding flow and ensure uniform feeding. The outer circle of the feeding roller is toothed, and a clutch is installed at the shaft end. In order to control the feed roller to run or stop. The inclined flow plate under the feeding roller is equipped with magnetic steel to remove the magnetic metal impurities in the cottonseed.
(2) Shelling mechanism.
①Rotating drum. The drum is an inner hollow cylinder made of ductile iron, and the rotating shaft passes through the center of the drum and is fixed with keys. There are knife grooves with equal spacing on the surface of the drum, and the knife plate is fastened in the knife groove with a pressure plate and bolts. The number of blades depends on the diameter of the drum. For example, the drum is φ450×1220 mm, and 14 blades are installed on it. When working, the rotating speed of the drum is high, about 1000 rpm, which will generate peeling shear force. Therefore, the drum should have sufficient mechanical strength and wear resistance.
② knife board. The blade is the main working part that generates shearing force, impact force and friction during shelling. The blade is made of 20Cr steel after heat treatment. The carburizing thickness of the main working face blade surface is 3 mm, and the surface hardness is HRC60-63°. The pressing plate is also made of the same material, the surface carburizing thickness is 0.8-1.0 mm; the surface hardness is HRC60-63°.
③ Blade seat. The blade seat is also made of ductile iron. There are 5-8 blade grooves on the seat, and the blade is fixed by a pressure plate in the groove. The working surface of the blade holder is a circular arc concave surface, which cooperates with the drum, and there is a certain distance between the two. The size of this distance can be adjusted by the eccentric shaft on the blade holder, generally 3-4 mm.
④Fix the blade holder. It is used to fix the blade holder. It consists of two wall panels and positioning braces. The lower end of the wall panel is connected with the frame by a fixed shaft, and the upper end relies on positioning strips and positioning stems to fix the position of the blade frame to maintain a certain distance between the blade base and the drum.
2. Working principle
Figure 2-2 shows the situation of cottonseed being sheared and hulled between the blades. The cottonseed entering the cutter plate sheller flows evenly between the drum (1) and the cutter plate seat (2) through the feeding mechanism. Shell.
3. Factors affecting the shelling efficiency of the blade shelling machine
(1) The moisture content of cottonseed. When the moisture is low, the shell is brittle, and the shelling efficiency is high, but the degree of pulverization is large; when the moisture is high, the whole kernel rate of the extruded product is high, and the pulverization rate is low, but the shelling efficiency is also low.
(2) Drum speed. When the rotation speed is high, the number of times the cottonseed is sheared by the blade increases, the hulling rate is high, and the corresponding whole kernel rate is low.
(3) Feeding amount. In the case of the same rotating speed of the drum, the feeding amount is large, the whole kernel rate of the exfoliated material is high, and the processing capacity is increased, but the leakage of seeds is more, and the re-peeling rate is also large.
(4) Blade clearance. The size of the gap between the blades of the blade shelling machine has an impact on the processing capacity, the shelling rate and the whole kernel rate. When the gap between the blades increases, the leakage of seeds increases, and the peeling rate and processing capacity are greatly reduced, but the degree of pulverization decreases, and the whole kernel rate increases accordingly.
(2) Disc shelling machine
Disc shelling machine, also known as tooth plate shelling machine, is a shelling equipment that uses the grinding action of the tooth pattern on the surface of a pair of grinding discs to break the oil shell. It is mainly used for shelling cottonseed, and can also be used for peanut fruit , tung seeds and other shelled oilseeds. In addition, it can also be used for crushing various oils and coarsely crushed oil cakes. It is characterized by relatively simple structure, convenient adjustment and use, and wide application range. However, when the disc sheller peels the oil, the degree of comminution is large, and more broken kernels are formed, which makes the separation of kernels difficult and leads to oil loss.
The structure of the disc sheller is shown in Figure 2-3. It is mainly composed of feeder, grinding disc, regulator, transmission mechanism and machine base.
(1) Feeder. The feeder consists of feeding wings, feeding shafts and adjusting plates. The feeding wings (1) are installed on the feeding shaft, and there are two pairs of cross-arrangement. A rack is fixed on the bottom surface of the adjusting plate (2), and a gear is engaged with it. When the gear is turned, the rack drives the adjusting plate to move back and forth, thereby reducing or increasing the amount of feed.
(2) Grinding disc. The grinding disc is made of several fan-shaped grinding discs fixed on the chassis, and is one of the main components of the disc shelling machine. The disc shelling machine has two grinding discs, one is fixed (commonly known as "dead disc"), which is fixed; the other is rotating (commonly known as "live disc"), which is connected with the drive shaft and rotates with the shaft. There are four knives on the movable grinding disc. The main function of the knives is to throw the oil between the grinding discs for shelling.
The grinding discs on the grinding disc are made of white iron and are fan-shaped. Each grinding disc is equipped with 4-6 grinding discs to form a circular ring. There are two types of grinding discs: fine oblique grooves and square grooves. Diagonal fluted discs are often used for cottonseed shelling, and square fluted discs are used for crushing. There are 3 holes in each disc for fixing to the chassis with countersunk screws.
(3) Regulator. The adjuster is installed on the right end of the transmission shaft, and the left end of the transmission uranium is fixed with the rotating grinding disc.
The adjuster is to move the drive shaft back and forth to achieve the purpose of adjusting the distance between the grinding discs and automatically removing hard foreign objects such as iron blocks and stones mixed between the grinding discs.
The adjuster is composed of two springs, push plate, ejector rod, cam, handle and segment handwheel. Pulling the handle can make the rotating grinding disc move back and forth by 13mm, which is used for turning on and off the machine and large adjustment in case of failure; rotating the adjusting handwheel can be used to fine-tune the grinding disc spacing. When hard impurities, such as iron blocks, enter between the grinding discs, the movable grinding disc will move outwards, and it will automatically recover after the hard impurities fall, so as to automatically remove the hard impurities and protect the grinding discs from damage.
(4) Transmission mechanism. The transmission mechanism of the disc sheller includes the main drive and the feeding shaft. The main drive is driven by a motor through a pair of V-belt pulleys, while the feeding shaft is driven by the main shaft through a pair of gears and a pair of flat pulleys.
2. Working process
When working, the oil feeds into the machine evenly by the non-stop rotation of the feeding wing, and its flow is controlled by the regulating plate. Since the movable disc is equipped with four knives, the oil is evenly driven between the two grinding discs during rapid rotation, so that the oil is subjected to the grinding action of the grinding discs, and the shell is broken to form a kernel-shell mixture, which is discharged through the bottom of the sheller. mouth discharge. The working distance between the grinding discs is adjusted by the predator.
3. Operation of Disc Sheller
(1) Before driving, carefully check whether the screws are tightened (especially the screws on the grinding disc) and whether there is enough lubricant for each rotating part. The incoming materials should be cleaned of hard impurities.
(2) Before starting the car, first manually turn the main shaft, push the handle on the regulator, and require that the two grinding discs do not touch during operation (the sound of grinding disc friction is not heard), and then push the handle back to the original s position.
(3) After driving, wait for the main shaft to run to the normal state, push the handle, adjust the hand wheel, make the two grinding discs touch slightly (you hear a little sound), then open the feeding hopper to check the granularity of the cutting material, if you still feel If it does not meet the requirements, adjust the handwheel until the qualified particle size is obtained, and then fix it with a lock nut.
(4) During normal operation, always pay attention to whether there are hard impurities (such as iron blocks, etc.) in the grinding disc. Once abnormal noise is found, you should immediately pull the handle of the adjuster and pull the movable disc away to avoid the grinding disc. crushed. When the disc is released, the untreated oil should be collected and reprocessed.
(5) Always pay attention to the dynamic load during operation. When the load increases, the supply should be reduced in time; when the power load suddenly increases, the sheller should be checked for blockage, and if so, the shell should be shut down to remove the shell for cleaning.
(6) Before parking, close the feeding hopper, and then pull the handle back, so that the grinding discs are separated from each other.
(3) Knife cage shelling machine
Knife cage shelling machine, also known as hammer shelling machine, is used for shelling peanuts. It uses a knife cage with a hammering head to rotate in a semi-circular cage, hammering and squeezing the peanuts entering the cage to break them, and then through air selection and screening to pass through the cage. The kernel is separated from the shell. The equipment is characterized by simple structure, convenient operation, high shelling efficiency, and separation of kernel shells. It is a combined equipment for shelling and kernel shell separation.
The structure of the knife cage sheller is mainly composed of feeding mechanism, shelling mechanism, kernel shell separation mechanism and transmission mechanism. When working, the peanut fruit from the feeding hopper controls the flow through the regulator and the feeding roller, and forms a thin material flow to fall evenly. In the process of falling peanuts, the airflow from the air duct blows away the impurities, and falls into the cage behind the air deflector. The heavy impurities in the peanuts fall vertically into the chute and are discharged out of the machine. There is a regulating valve on the upper part of the chute to control to prevent the peanuts from falling into it. As for the peanuts, they flow into the cage from the left under the action of the airflow. The knife cage is in the middle of the cage. There is a hammering head on the knife cage. The knife cage rotates at a speed of 100 rpm. It is broken under the action of squeezing and falls through the gap of the lower semicircular cage. The unbroken peanuts continue to stay in the cage until they are broken and pass through the gap. The peanut shells and peanut kernels falling from the gaps of the cages meet the air flow adjusted by the adjustable damper blown by the fan, and blow the broken shells to the shell collecting pipe, and the nut shells are discharged from the outlet at the lower part of the shell collecting pipe, and the crumbs, etc. Light impurities are discharged from the shell chip outlet in the middle of the shell tube and collected separately.
The peanut kernels and a small amount of small peanuts falling from the cage grid enter the vibrating screen for re-separation. The vibrating screen has 3 layers of sieve surface. The first layer separates peanuts and peanut kernels, and the peanuts above the sieve need to be returned and shelled again; the second layer is to separate peanut kernels with different particle sizes; the third layer is used to screen out fine impurities. Because the particle size of peanut fruit is quite different, in order to improve the shelling effect, large oil plants should first classify the peanut fruit before shelling, and then peel it separately.
(4) Centrifugal Sheller
Centrifugal sheller is a kind of equipment in which under the action of centrifugal force, oil with shells enters the equipment and violently hits the wall of the equipment, and its shell is broken. There are vertical centrifugal shellers and horizontal centrifugal shellers, among which vertical Centrifugal shellers are the most common.
Vertical centrifugal sheller, also known as turbine sheller, is a special equipment for sunflower seed shelling. It consists of a feeding hopper, a rotating drum (turntable), a transmission mechanism and a casing. When working, after the sunflower seeds enter the feeding hopper, they fall to the rapidly rotating turntable through the adjusting gate, and the sunflower seeds are thrown into chaos at high speed. First, they are impacted by the beating plate on the turntable; The sunflower seeds that have not been cracked hit the baffle at a high speed to further break them, so as to achieve the purpose of fully shelling. The kernels falling from the baffle will flow into the discharge port together with the shell and be discharged out of the machine, and then be separated separately.
The advantages of vertical centrifugal shelling machine are large processing capacity; high shelling efficiency, up to 9% 0; whole kernel rate of 70-80%, small degree of crushing; high utilization rate of plate, and compact structure, saving power. The disadvantage is that the structure of the equipment is more complicated, and the adjustment at the beginning of operation is more troublesome.
(5) Toothed roller shelling machine
The toothed roller sheller is a new type of cottonseed shelling equipment, which can also be used for crushing large-grained oil such as soybeans and peanuts. The toothed roller sheller mainly realizes the peeling of cottonseed and the crushing of oil through the shearing and squeezing action of two toothed rollers with speed difference on the oil. The gap between the toothed rollers can be adjusted by the adjusting device according to the size of the shelled oilseed particles. The machine has high peeling rate, the powder degree of the mixture of shell and kernel after peeling is small, the rate of whole kernel is high, and the kernel and shell are easy to separate.
3. Factors affecting the peeling effect
1. The nature of the oil
The main oil properties that affect the peeling effect are the mechanical properties of the oilseed shell and the adhesion between the shell and kernel. Different types of oil, maturity and water content, the mechanical properties of the oilseed shell and the adhesion between the shell and kernel are also different, and the degree of difficulty of shelling is also different. For example, the shell of sunflower seeds has a fibrous structure and is very brittle, and it is easy to open the shell along the fibers; while the shell of cottonseed is tough and elastic, and the surface is fluffy, which is not easy to peel. The maturity of the grain is good, the grain is full, and the thousands of grains are heavy, so it is easy to peel the shell, otherwise, it is not easy to peel the shell. Oilseed moisture content has a direct effect on the strength, elasticity, and plasticity of the hull, as well as on the degree of comminution of the kernel. Taking sunflower seeds as an example, when the moisture content is 6%-9%, the shell strength is the largest, and the shell strength will decrease when the moisture content is above or below this range. In general, the lower the water content of the oilseed, the more brittle the shell is, and the shell is easy to break when peeling, but the powder degree of the mixture increases after peeling. On the contrary, the toughness of the shell is good, the shell breaking rate is low when peeling, but the whole kernel rate after peeling is improved. When peeling oilseeds, the most appropriate moisture content of the oilseed should be maintained, so that the shell and the kernel have the greatest difference in elastic deformation and plastic deformation. On the other hand, the powder degree of the kernel will not be too large under the action of mechanical external force. Therefore, it is very important to control the optimal moisture content of the oil when peeling the oil to improve the peeling efficiency and reduce the powder degree. When the moisture content of the shelled oilseeds is not suitable, the moisture content of the oilseeds can be adjusted before shelling. In addition, the shell strength of oilseeds also has a certain relationship with temperature. When the oilseed is heated, its shell strength decreases. The gap between the oilseed kernel and the shell is large, the combination of the kernel and the shell is loose, and it is easy to peel and separate, otherwise, it is difficult to peel and separate.
The particle size composition of oilseeds also affected the hulling effect. The particle size of oilseeds is uneven, and it is difficult to determine the optimal operating conditions of the shelling equipment, so that the shelling efficiency and powder degree cannot reach the best balance, and the shelling effect is reduced. In order to improve the peeling effect, the process of cyclic peeling and secondary peeling can be adopted. When the particle size difference is too large, it is best to use graded peeling to achieve a good process effect.
The surface state of oilseeds also affects the hulling effect. For example, under the same conditions, the hulling rates of fluffed cottonseed and delinted cottonseed are different, and the fluffed cottonseed is difficult to break, so the hulling rate is low and the degree of comminution is small. The power consumption of the shelling equipment is relatively large.
2. Selection of shelling methods and equipment
Different oilseeds have different husk properties, adhesion between kernel shells, and oilseed shapes and sizes. According to their characteristics, especially the mechanical properties of the shell—strength, elasticity and plasticity, different methods and equipment should be used for peeling. shell. The peeling method and the selection of equipment are different, and the peeling effect shows a great difference. For example, the brittle shell of sunflower seeds should be shelled by impact method, and the tough shell of cottonseed should be shelled by shearing or grinding methods. When the disc sheller is used to grind and peel the cottonseed, the cottonseed is broken and peeled by the continuous grinding action of the grinding disc, and the peeling rate is very high, but the pulverization of the mixture after peeling increases, which affects the kernel Shell separation effect, and a large number of oil-containing kernel chips are privately attached to the shell, which increases the oil content of the shell and causes oil loss. In the blade shelling machine that uses the shearing method for shelling, although the cottonseed is subjected to multiple actions by the movable blade and the fixed blade, its effect is not continuous but periodic, only when the movable blade and the fixed blade are affected. The fixed blade is sheared at the moment of contact. Therefore, the degree of pulverization of the oilseed after peeling is very small, and the kernel is relatively complete, which is conducive to the complete separation of the kernel and the shell, but the leakage of the oilseed is easy to occur. The hulling rate is low, and the hulling mixture must be separated from the husks, and the leaking seeds must be re-peeled.
3. Working conditions of shelling equipment
The working conditions of the shelling equipment, such as the selection of the rotating speed of the shelling equipment, the uniformity of the oil flow, and the wear of the shelling working surface, will affect the shelling effect, and should be used reasonably according to different oil and shelling requirements.
For example, when the centrifugal sheller using the impact method works, the force of the sheller on the oilseed mainly depends on the centrifugal force generated by the turntable or the impact force of the plate, and its size is related to the rotation speed of the turntable or the impact force of the plate. The speed is proportional to the mass of the particle. Therefore, the shelling efficiency and shelling quality of the shelling machine have a great relationship with the rotating speed of the shelling machine, the structure of the rotary table, the number of plates, the quality of the grains (thousand-grain weight), the uniformity, and the amount of blanking. . Table 2-8 lists the relationship between the rotation speed and the peeling rate of the vertical centrifugal sheller when peeling sunflower seeds. It can be seen from the table that when the moisture content of the raw material is the same, the rotation speed is high, the shelling rate is also high, but the broken kernel rate also increases accordingly. Table 2-9 lists the effect of grain quality on the shelling rate. It can be seen from the table that the grains are full and the thousand grains are heavy, and the shelling rate is higher. When the disc sheller using the grinding method is used, the speed of the grinding disc, the size of the working gap between the grinding discs, the shape of the grooves on the grinding disc and the uniformity of the grains all affect the peeling efficiency and the shelling efficiency. quality.
When the shelling machine using the shearing method is working, the rotating speed of the drum increases, the shelling rate increases, but the corresponding whole kernel rate is low. The size of the gap between the blades has an impact on the oil handling capacity, the peeling rate and the whole kernel rate. When the gap increases, the phenomenon of seed leakage increases, the peeling rate and the processing capacity decrease, but the pulverization degree decreases, and the whole kernel rate increases.
When the roller shelling machine using the extrusion method is working, the rotating speed of the rolls, the difference in the rotating speed of the two rolls, the rolling distance between the rolls, and the shape of the grooves on the rolls have a direct impact on the shelling effect. The higher the rotational speed of the roll, the higher the peeling rate and the larger the processing capacity. The greater the difference in rotation speed between the two rollers, the higher the peeling rate, but the greater the degree of pulverization of the peeled material. The smaller the rolling distance between the rolls, the higher the peeling rate, the greater the pulverization degree, the greater the processing capacity and the greater the power consumption.
4. Separation of kernel shell
After the oil is peeled and peeled, a mixed material is obtained, which includes whole kernels, kernel chips, shells, shell chips, and unbroken intact oil. In production, it is required to separate this mixed material, the separated kernels and kernel chips are sent to the next process, the shells and shell chips are sent to the warehouse, and the complete oil is re-shelled. Kernel shell separation is a relatively complicated process, and the effect of separation is directly related to the level of oil yield and the quality of oil cakes.
(1) Separation equipment
In production, screening method and air separation method are often used to separate the mixture of kernel, shell and whole grain oil. Some shelling equipment itself has a screening or winnowing system to form a combined equipment, which completes shelling and separation of kernels and shells at the same time.
1. Screening equipment
The screening equipment separates kernels and shells, generally using equipment such as vibrating screens and rotary screens. The special equipment for the separation of sunflower seed shells and kernels includes sunflower seed shells, kernel separation sieves, etc.
When the screening equipment is used for kernel shell separation, its structure and principle are the same as those used for cleaning, only the sieve plate and sieve hole specifications are different, which should be selected according to the requirements of peeling and kernel shell separation.
(1) Vibrating screen. The vibrating screen used for cottonseed shelling, kernel and shell separation, the sieve plate is made into corrugated shape, so that the material can be better turned on the screen surface, which is conducive to the separation of kernel and shell. Since the material just dropped from the sheller is relatively loose on the screen surface, and the shells and kernels gather together during vibration, the fluidity is poor, so the sieve holes in the discharge section are slightly enlarged to facilitate the separation of kernels.
(2) Cylinder sieving. Cylindrical sieving has better separation effect for cottonseed kernel husks. The arrangement of the sieve holes on the sieve cylinder is from large to small, because the material entering the front section of the cylinder screen is poorly scattered. After the beater is continuously beaten and flipped, the material is gradually loosened, and the screen holes in the rear section can be appropriately made smaller to minimize the number of shells. The crumbs are mixed into the kernels through the mesh of the sieve.
(3) Separation sieve for sunflower seed shells and kernels. The kernel shells of sunflower seeds after peeling are not much different in size and weight, and it is difficult to separate them. This equipment is a special equipment for the separation of sunflower seed shells and kernels. It is basically the same as the vibrating screen. It consists of a feeding mechanism, a kernel screen, a shell screen, a fan and a transmission mechanism.
The working principle is the same as the specific gravity stoner. When working, sunflower seeds, kernels and shells fall into the middle of the kernel sieve evenly from the feeding hopper, and the sieve surface is first suspended by the air flow blown from the bottom of the fish scale-shaped sieve holes. Since the suspension speed of seeds and shells is smaller than that of kernels, seeds and shells are suspended on the upper layer of the kernels, and the vibration of the sieve body will increase the automatic classification of the whole seeds, kernels and shells, and the kernels will be deposited on the screen surface. Due to the inertial force, the thrust of the raised screen holes and the blowing wind, the kernels gradually move on the screen surface and finally discharge from the outlet. The seeds and shells slide along the inclined direction of the screen surface under the action of their own gravity and inertial force, and finally enter the middle of the shell screen from the seed and shell outlets at the lower end of the screen surface along the sliding plate. Like the kernel sieve, the seeds and shells are separated here, the whole seeds are discharged from the upper end of the sieve surface by moving upward, and the shells are discharged from the lower end of the sieve surface. After separation, the shell content in the kernel is less than 2%.
2. Wind selection equipment
After the cottonseed and other oilseeds are hulled, the broken shells and kernels or whole kernels sometimes have a small difference in size, and there is no obvious difference in shape and size between the kernels and husks. Chips, whole grains and broken shells are separated. Usually, the difference in suspension speed between these oils can be used to separate such materials by means of wind separation, such as special wind separation equipment, seed husk separator or other types of suction tooth separators. For different materials, the appropriate suspension speed should be selected according to the process requirements to determine the type and size of the wind separation equipment. Now the seed husk separator is introduced as follows.
The seed husk separator is generally used in two-stage cottonseed hulling process to separate the whole cottonseed in the shell. It is a device that uses wind to separate the whole cottonseed from the husk.
When working, the material enters from the feeding hopper and is uniformly discharged under the action of the feeding roller. Then, it falls between the arc groove plate and the knife roller through the drip plate, so that the material is divided into uniform thin layers, which is convenient for the wind to absorb the cottonseed husks. The whole cottonseed falls directly into the lower screw conveyor due to its large specific gravity and is discharged out of the machine, while the cotton hull is discharged out of the machine through the upper suction pipe through the tuyere ring under the action of wind due to its light specific gravity. to the collector. The damper, the guide plate and the tuyere ring are used to adjust the air volume and speed so that the seed shells can be effectively separated. Usually the wind speed at the suction duct of the wind chamber is 4.5-5.0 m/s.
The main points of operation of the seed husk separator are:
(1) Before feeding, check the separator for air leakage. When the air leakage is serious, the cause must be found out, and the feeding can be started after sealing.
(2) When feeding, the material flow should be controlled, and the air volume and air speed should be adjusted so that the discharged grains basically do not contain husks, or there are basically no grains in the husks.
(3) When parking, first stop the feeding, and then shut down the fan and the discharging cage.
(2) The technological process of several kinds of oil peeling and kernel shell separation
1. Process flow of cottonseed hulling and kernel husk separation
At present, some domestic cottonseed oil plants have small production scales, while others have large production scales. Small and medium-sized oil plants, due to the variety of oil plants, produce different oil plants in different seasons, the equipment for cleaning and peeling requires one machine to be multi-purpose, and the equipment selected should be considered suitable for a variety of oil plants. In this way, for the production of different oils, it is necessary to properly adjust some equipment and technological processes to adapt to the production of various oils. For example, a disc sheller can be used for cottonseed shelling, because it is suitable for shelling and crushing of oil plants, and the process and equipment are relatively simple, but the disadvantage is that the oil yield is low.
Large-scale oil plants can use special equipment for cottonseed husking, which has a complete process flow, better hulling effect and higher oil yield. The disadvantage is that the cost of shelling is higher due to the selection of more equipment, but this part of the cost can be compensated by increasing the oil yield.
2. Peanut shelling and kernel shell separation process
Peanut husks are loose, and there are certain gaps between the kernel shells, which are broken after being hammered and squeezed by a hammer shelling machine. The process flow is shown in Figure 2-11.
3. Process flow of sunflower seed peeling and kernel shell separation
Sunflower seed shells are thin and brittle, and the shelling process is relatively simple. Usually, a vertical centrifugal shelling machine is used to break the shells, and then separate the kernels and shells. The process flow is shown in Figure 2-12.
(3) Factors affecting the separation effect of kernels and shells
1. Properties of the peeling mixture
During the shelling process, the oilseed shell is broken by external force, but the degree of difficulty of separating the kernel from the shell varies with the variety of oilseeds. For example, the combination of peanut kernel and shell is very loose, the kernel is easy to fall off from the shell after the peanut shell is broken, and the separation of the kernel shell is relatively easy. However, the adhesion between the cotton kernel and the shell is relatively tight. After the cotton shell is peeled off, there are still some cotton kernels in the broken shell that cannot fall off, and due to the poor scatterability of the cotton shell, some of the cotton kernels will be wrapped in the broken shell. In cotton husk, kernel husk is more difficult to separate.
The degree of pulverization of the mixture after peeling has a great influence on the separation effect. The greater the degree of pulverization of the mixture after peeling, the more difficult it is to separate the kernel shells. Because the separation of kernel chips and shell chips is much more difficult than the separation of whole kernel and shell. When the pulverization degree of the peeling mixture is very large, it is difficult to achieve the ideal separation effect even if a lot of separation equipment is added.
2. Separation process of shelling and kernel shell
The choice of peeling and kernel husk separation process has an important influence on the separation effect of kernel husk. Only by selecting a reasonable and perfect peeling and kernel shell separation process can a good kernel shell separation effect be achieved. The separation process of kernel husk should be selected according to the variety of oilseeds, the type of hulling equipment, the nature of the hulling mixture, the production scale of the oil plant, equipment investment, power consumption and other factors. Different oilseed varieties have different scatterability of the mixture after peeling and different adhesion between kernel shells, and the separation process also has its own characteristics. As mentioned above, the separation of peanut kernel shells is easier than that of cottonseed kernels. Therefore, the separation process of peanut shelling and kernel shell separation is relatively simple, while the separation process of kernel shells after cottonseed shelling is relatively simple.
for complex. The choice of separation process also considers the type of shelling equipment. Different types of shelling equipment have different particle size composition and pulverization degree of the mixture after shelling, and the separation process is also different. If a disc sheller is used to peel the cottonseed, the pulverization of the mixture after shelling is high, but the shelling rate is high and the seed leakage is very small. The separation process should mainly consider strengthening the separation of broken kernels and broken shells. If the cottonseed is hulled by a knife-board husker, the whole kernel rate after hulling is high, the pulverization degree of the mixture is small, but the seeds are leaked more. Therefore, the separation process must consider the separation of the unpeeled whole seeds in the shell. The unpeeled whole seeds are recovered and peeled again. Small oil plants often use a relatively simple peeling and separation process, while large oil plants should use a relatively complete peeling and separation process. Taking cottonseed as an example, the simpler one is the one-time hulling and separation process, and the more perfect is the two-time husking separation process.
The first peeling and separation process is to peel the cleaned cottonseed by a disc peeler or a toothed roller peeler, and then first use a flat screen to separate the shell and the whole kernel, and then use a round screen to attach to the shell or wrap it in the shell. The broken kernels are separated out, and at the same time, the broken shells are separated from the kernels by the method of wind selection. The separation of kernel shells can also be carried out directly by using spiral sieves. The separation process of one-time shelling is simple, and the equipment is used less, but in order to obtain a higher shelling rate, the pulverization degree of the shelling mixture is usually large, and it is difficult to achieve a perfect separation of kernel shells. The rate is high, resulting in the loss of oil in the production process.
The two peeling and separation process is to peel the cleaned cottonseed by the peeling equipment, and then use the kernel husk separation and sub-husk separation equipment to complete the separation of the kernel, the shell and the unpeeled whole seeds, and the separated whole seeds are returned to the shelling. Re-peeling in the machine cycle, or enter the next shelling machine for secondary peeling. The double peeling process reduces the degree of pulverization when the oilseed is peeled, and the whole kernel rate in the peeling mixture is high, which is conducive to the perfect separation of the kernel shell, thus reducing the husk content in the kernel, especially the kernel content in the shell, effectively. Reduced oil loss during production. However, the two peeling and separation processes are more complicated, and more equipment is used. When the disc sheller is used for secondary shelling, the distance between the grinding discs of the first-pass sheller is selected to be larger, so that the cottonseeds of general particle size can be peeled without being too broken, while the smaller particle size and the deflated seeds cannot be Peeling, the shelling mixture is separated by the seed husk separator to separate the small seeds that are not peeled, and then enters the second shelling machine with a small distance between the grinding discs for shelling. The mixture after peeling is relatively loose, and it is best to directly enter the separation equipment to separate the kernel and shell.
3. Equipment and process conditions
The structure and process conditions of the kernel-shell separation equipment are also factors that affect the separation effect. For example, the selection of screen surface during screening and separation, the reasonable selection of air volume and wind speed during air separation and separation, and the uniformity of wind when materials pass through the air duct.
Section 3 Oil peeling
First, the purpose, requirements and methods of peeling
The purpose of oilseed peeling is to increase the protein content of the cake and reduce the cellulose content, and to improve the utilization value of the cake. At the same time, the color and wax content of the leached crude oil are reduced, and the quality of the leached crude oil is improved. Oil peeling can also increase the processing capacity of oil production equipment, reduce the residual oil content of the cake, and reduce the energy consumption in the production process. At present, oil production enterprises mainly dehull soybeans to produce low-temperature soybean meal and high-protein feed soybean meal. In addition, according to market demand, the soybean hulls can be pulverized and added to soybean meal in different proportions to produce soybean meal with different protein contents. Peanuts, rapeseeds, sesame seeds, etc. are sometimes peeled to meet the requirements of different production processes.
Dehulling method: The seed coat of most oilseeds is thin, and the bonding adhesion with the seed kernel is also strong, especially when the oilseed water content is high, the seed coat toughness increases, making it difficult to peel, even if the seed kernel is After being broken by external force, the seed coat may still be attached to the broken kernel. Therefore, the moisture content of oilseeds is a very critical factor in the peeling process. In production, the moisture of the oilseed is usually adjusted first, and then the oilseed is broken into several pieces by means of grinding, squeezing, shearing and impacting, and the seed coat outside the seed kernel is also broken and removed from the seed kernel at the same time. The kernels and skins are separated by wind-selection or screening.
Peeling requirements: high peeling rate, small powder degree of oil when peeling and crushing, better separation of peel and kernel, minimal loss of oil content, peeling and peeling and kernel separation process should be as short as possible, equipment investment and energy consumption of peeling process Small wait.
2. Peeling process and equipment
1. Peeling of soybeans
There are two kinds of soybean peeling process: cold peeling and hot peeling. The traditional soybean peeling process is the cold peeling process. The soybean cold peeling process is about to clean the soybeans in the drying tower by hot air heating and drying to about 10% water content, drying temperature is 70 ℃ - 80 ℃, and then stay in the storage bin for 24-72 hours, and then enter the tooth at ambient temperature. Roll crusher, is crushed into 4-6 petals. The broken soybeans are air-selected and screened to separate the husks and kernels, the separated bean kernels are softened and then rolled, and the bean hulls are collected separately. The characteristics of this process are: the dried and cooled bean skin is relatively crisp, and the bean skin is easy to fall off and separate from the bean kernel after the soybean is broken, but the powder degree of the broken beans is large, and the broken bean skin and the broken bean kernel are not easily separated. Moreover, the peeled cold bean kernels need to be reheated and softened, which increases the steam consumption.
At present, soybean thermal dehulling process is used more. According to the required peeling rate, the hot peeling process can be divided into two types: semi-peeling and full peeling. The peeling rate of the semi-peeling process is generally 60% to 70%, the peeling rate of the full peeling process is more than 90%, and the kernel content in the skin is less than 1.5% according to the oil content in the skin.
Figure 2-12 shows a form of semi-hulling process in soybean thermal dehulling. The cleaned soybeans are heated and dried by hot air in the drying tower to about 10% water content, the heating time is 20-30 minutes, and the temperature is 60°C to 65°C. Falling into the impact suction separator uses the impact to loosen the bean husks from the kernels, and separate most of the bean kernels and the bean husks through suction separation. The separated bean kernels are rolled into billets, and the separated bean skins are then divided into three components: skin, broken kernels, broken skins and fine kernels through a vibrating screen. The separated fine kernels are rolled into billets, and the broken kernels and broken skins are separated by a suction separator. The separated broken bean kernels are sent to rolling, and the separated broken bean hulls and the bean hulls separated by the vibrating screen are crushed together and then packaged separately or mixed with soybean meal in a certain proportion to produce soybean meal with different protein contents. Compared with the cold peeling process, the production cycle is shortened, and the powder degree of hot soybeans after crushing is reduced, which is beneficial to the separation of skin and kernel. The hot air circulation system is adopted in the hot peeling process, so that the drying, crushing, peeling and peeling of soybeans after drying are maintained at a certain temperature, so the peeled hot beans can be directly Rolling, which not only greatly saves the steam consumption of the softening process, but also saves the investment and energy consumption of the softening equipment. However, in the thermal peeling process, the soybeans are hot when crushed. After crushing, the hulls and the kernels are easily attached together, and the husks are not easily separated from the bean kernels. Usually, the bean hulls need to be loosened and separated from the bean kernels under the action of external force. . Therefore, in the thermal dehulling process, the crushed bean kernels must pass through a dehulling machine with an impact force to help the bean husks fall off the bean kernels, and then go through wind selection and screening to separate the husks and kernels.
Figure 2-13 shows a form of the full dehulling process in soybean thermal dehulling. The cleaned soybeans are first slowly dried in a drying tower to about 10% water content, and then quickly dried in a fluidized bed dryer to further reduce the water content of the soybean skins. The dried soybeans are crushed to 2-3 petals by the first-stage toothed roller crusher, and then separated by the pine bark machine and the bark and kernel suction separator. The separated watercress is then crushed to 4-6 pieces by the second-stage toothed roller crusher, and then separated by the pine bark machine and the bark suction separator. The bean kernels separated twice are sent to the rolling mill for rolling, and the separated bean skins are further separated from the fine kernels in the skins by a vibrating screen and a suction separator. This peeling process has a long process and many equipment, but the peeling rate is high and the kernel content in the peel is low, and the protein content of the obtained soybean meal can reach more than 49% (of course, the protein content of soybean meal also depends on the protein content of soybean raw materials).
The by-product of soybean peeling is soybean hull, which can be sold directly as a by-product, or added to soybean meal in a certain proportion to produce grades of soybean meal with different protein contents. Soybean hulls are high in plant fiber but low in lignin. Therefore, it can be highly digested by animals. In fact, the metabolic energy of soybean hulls is close to that of grains for anti-dang animals. Therefore, from an economical point of view, soybean hulls can be used to replace grains in forages, and it has auxiliary functional characteristics. For growing cattle and sheep, soybean hulls instead of grains can eliminate and reduce the risk of acidification. Negative effects of starch on digesting fiber. For lactating cows and ewes, soybean hulls can replace a significant grain ratio in grain-forage feeds without reducing milk fat content or milk production. The use of soybean hulls as a source of dietary fiber is increasing in human food.
Soybean peeling can also use rubber roller husker. When working, the dried soybean particles enter between the rubber rollers, and the two sides of the soybean particles are subjected to the friction and tearing force of the two rubber roller surfaces in different directions, and the pressure produces elastic and plastic deformation. The skin begins to separate from the kernel under the action of squeezing and rolling, and the kernel is divided into two or more petals under the action of strong rolling and squeezing, and leaves the working area of the rubber roller together with the seed coat, and then adopts air selection and screening. method for the separation of skin and kernel.
2. Rapeseed peeling
Rapeseed contains 14%-20% of the seed coat, the average skin content of cabbage type black seed rape is 18%, the seed coat contains more than 30% of crude fiber, most of the sinapine, pigment, phytic acid, Antinutrients such as tannins are also mainly present in the seed coat. Therefore, the seed coat is the main factor affecting the protein feeding of rapeseed meal, and it is also the key to restrict the development of rapeseed edible protein. Dehulling treatment can effectively remove anti-nutritional factors, the average protein content of cakes can be increased by about 14%, and the quality of cakes is also greatly improved. Dehulling is not carried out in normal rapeseed oil production, but rapeseed dehulling is more meaningful in canola seed processing, because canola seeds have higher fiber content than general rapeseed, and their meal is a non-reactive The application of animal feed is limited.
At present, the research on rapeseed peeling technology is still in its infancy. According to domestic reports, the moisture content of rapeseed is adjusted to 7%-8%, the rapeseed is broken and peeled by centrifugal impact, and then the skin and kernel are separated by screening and wind selection. It has been reported abroad that the rapeseed skin is broken by the elastic deformation of the rapeseed in the gap between the crushing rollers, and then the skin and the kernel meat are separated by screening and electromagnetic field action. In actual production, rapeseed crushing and dehulling is carried out in two steps. The first crushed mixture is divided into three components by the plane rotary sieve. The kernels under the sieve are directly pressed, and the incompletely crushed rapeseed on the sieve is subjected to secondary crushing. separation in. After the skin and kernel mixture enters the high electric field skin and kernel separator, it falls onto a rotating roller after being vibrated evenly and is thrown into a strong electric field at a certain linear speed. The electromagnetic field force they are subjected to in the electric field will also be different, and the distance they can reach in the electric field will be different. By adjusting the angle of the lower baffle of the separator, the rapeseed skin can be well separated.
The color, flavor and quality of the oil obtained by pressing the dehulled rapeseed kernels were obviously improved, and the utilization value of the meal after dehulling was improved. But the disadvantage of oil loss during peeling operations should also be considered.
3. Peel the sesame seeds
Sesame seeds do not peel in general oil production. However, due to the high fiber and oxalate content (2% to 3% calcium oxalate chelate) in the seed coat or cuticle of sesame, the color of the oil and meal is deepened, and the cake is bitter, and such cake cannot be As a protein resource for humans or other monogastric animals, it can only be used as feed or fertilizer for cattle. Therefore, when sesame is used as food or sesame meal is used as human protein resource, peeling is usually required. The traditional method of sesame peeling is to soak the seeds in water to make the seed coat burst, and then separate the skin from the seed by buoyancy sorting. In the flotation separation of seeds and skins, the density of water can be adjusted with brine to promote better separation. Experiments have found that hot dilute alkaline solutions such as sodium hydroxide, sodium borate, and sodium hypochlorite can be used to loosen or rupture the seed coat. Another traditional method is to rub and rub the soaked sesame seeds on a wooden board or slate, and then the mixture is separated by flotation with brine. In addition, there are also reports of using mechanical methods to peel sesame seeds, that is, the soaked sesame seeds pass through two vertically installed disks with hard surfaces, one disk is fixed, the other disk rotates, the wet seeds are rubbed, and the skin is removed from the kernel. Then, the mixture is washed by water flow or water spray, and the skin is sieved from the mixture with a wire mesh.