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Oil Extraction

Oil Extraction

  • Categories:Company News
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  • Time of issue:2021-12-24 16:26
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(Summary description)With the development of leaching method oil, the proportion of pressing method oil is decreasing day by day. But the oil production by pressing still plays an irreplaceable role and occupies an important position in my country's oil industry. At present, the oil presses used by large and medium-sized oil factories in China, including some small oil factories, are mainly ZX·18 oil presses (the original 200 type oil presses) and ZY·24 type pre-presses (the original 202 type oil presses). press). Some small oil mills still use the ZX·10 type oil press (the original 95 type oil press) and the ZQ·35 type hydraulic oil press (the original 90 type oil press). In order to increase the oil yield or improve the permeability of the embryo, most domestic oil plants have adopted the pre-pressing-leaching oil-making process.

Oil Extraction

(Summary description)With the development of leaching method oil, the proportion of pressing method oil is decreasing day by day. But the oil production by pressing still plays an irreplaceable role and occupies an important position in my country's oil industry. At present, the oil presses used by large and medium-sized oil factories in China, including some small oil factories, are mainly ZX·18 oil presses (the original 200 type oil presses) and ZY·24 type pre-presses (the original 202 type oil presses). press). Some small oil mills still use the ZX·10 type oil press (the original 95 type oil press) and the ZQ·35 type hydraulic oil press (the original 90 type oil press). In order to increase the oil yield or improve the permeability of the embryo, most domestic oil plants have adopted the pre-pressing-leaching oil-making process.

  • Categories:Company News
  • Author:
  • Origin:
  • Time of issue:2021-12-24 16:26
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Information

The first section of the basic theory of oil production by pressing

1. Overview of oil production by pressing

With the development of leaching method oil, the proportion of pressing method oil is decreasing day by day. But the oil production by pressing still plays an irreplaceable role and occupies an important position in my country's oil industry. At present, the oil presses used by large and medium-sized oil factories in China, including some small oil factories, are mainly ZX·18 oil presses (the original 200 type oil presses) and ZY·24 type pre-presses (the original 202 type oil presses). press). Some small oil mills still use the ZX·10 type oil press (the original 95 type oil press) and the ZQ·35 type hydraulic oil press (the original 90 type oil press). In order to increase the oil yield or improve the permeability of the embryo, most domestic oil plants have adopted the pre-pressing-leaching oil-making process.

Second, the characteristics of oil production by pressing

(1) Strong adaptability

Oil pressing is suitable for a variety of oil processing and production of different scales. The requirements for power equipment are not high, and electricity or other power can be used, which is flexible and convenient in use. It is especially suitable for areas and rural areas with underdeveloped industries or inconvenient transportation.

(2) The process and operation are simple and easy

Usually, the oil can be pressed after pretreatment. The process flow is short, the technical requirements for operation are low, and the supporting equipment can be combined with local and foreign equipment. The investment is small and the effect is quick. When using a small oil press, you can also directly fry the seeds and press the whole seeds, but the quality of the crude oil obtained is poor.

(3) Production is relatively safe

During the production process, the oil pressing machinery runs smoothly and the spindle speed is slow. As long as the oil production is carried out according to the production operation rules, there will generally be no accidents.

(4) Disadvantages

Oil production by pressing method mainly has the following shortcomings: first, the residual oil rate of the pressed cake is higher than that of the leached meal; second, the labor intensity is high when overhauling and replacing wearing parts; third, the product quality is poor when the production conditions of small factories are simple.

Since there are still some limitations in the production of oil by pressing method, especially the residual oil rate of the pressed cake is relatively high, generally reaching 5%-8%. oil, thereby reducing production costs and improving enterprise efficiency.

3. The change of the embryo during the pressing process

After the pretreatment, the blank must have suitable plasticity and pressure resistance. This characteristic of the blank is a necessary condition for establishing sufficient pressure in the press chamber, and it is necessary for the power screw oil press to produce sharp friction between the particles and the mechanical structure of the press chamber when pressing the blank. The condition is also an indispensable condition for all oil presses to form cakes during the pressing process.

During the pressing process of the material, the changes that occur are mainly physical changes. The specific performance is that the volume of the pressed material is gradually reduced; a large amount of oil is discharged; the trace water in the material embryo is gradually evaporated; the viscosity of the oil is continuously reduced; the amount of colored substances, solid substances and colloidal substances in the oil is also gradually increased; .

During the pressing process, the pressing material undergoes a series of chemical changes at the same time as physical changes. The performance is that the colloidal structure continues to be destroyed; the protein is deeply denatured and combined with other substances; there is also the occurrence of "dissociation", such as the protein and phospholipids, free fatty acids and gossypol. This results in an increase in oil-soluble impurities; carbohydrates will also be partially carbonized due to increased temperature, and so on.

It can be seen that the changes in the pressing material during the pressing process are not only beneficial to oil production, but also detrimental to the quality of oil products. Of course the former predominates.

4. Oil discharge power and oil discharge depth during the pressing process

(1) Oil discharge power during the pressing process

The essence of studying the power of oil discharge during the pressing process is to study the rate at which the oil is discharged from the inside of the cells of the pressed material during the pressing process. We know that the process rate is proportional to the driving force and inversely proportional to the resistance. Pressure is the driving force of the pressing process, and viscosity is the resistance of the pressing process.

After the oil has undergone the pretreatment process, although necessary and sufficient conditions have been created for the oil to be separated from the cooked embryo, the oil will not flow out automatically after all. For oil by pressing, it is also necessary to rely on machinery to exert enough pressure; in order to free the oil from the shackles of solid matter in the embryo. Therefore, a strong pressure needs to be established in the pressing chamber of the press so that the oil can be smoothly discharged from the oil.

However, in the pressing process, only enough pressure is established without higher temperature coordination, and the oil output effect will not be good. Because there is not a high enough temperature, the viscosity of the oil cannot be reduced much, that is, the resistance of the oil to be discharged is large, and the oil is not discharged smoothly during the pressing process.

It can be seen that in the pressing process, the oil discharge rate mainly depends on "pressure and temperature". Pressure is a necessary prerequisite for oil to be discharged from the pressed material, while temperature is a necessary condition for reducing oil discharge resistance.

(2) Oil discharge depth during pressing

The essence of studying the depth of oil discharge in the pressing process is to study the degree of oil discharge in the pressing process. We know that the driving force of oil discharge in the pressing process is pressure and temperature (or viscosity). Then, can we imagine that during the pressing process, the pressure and temperature should be increased as much as possible to reduce the viscosity of the oil to 0 and squeeze out all the oil in the embryo?

In fact, in the process of oil extraction, the pressure of the pressing chamber cannot be increased indefinitely, and the temperature of the material embryo cannot be increased indefinitely. Since the gravitational force between oil molecules in the blank cannot be reduced to 0, the viscosity of the oil cannot be reduced to 0. Therefore, a certain amount of extremely thin oil film (existing on the inner and outer surfaces of the cake, generally invisible to the naked eye) will always remain in the cake finally formed during the pressing process. Therefore, it can be concluded that during the pressing process, even under the most suitable pressure and temperature and other conditions, it is impossible for the oil to be completely squeezed out of the embryo.

In addition, during the pretreatment process of the oil, the cell structure (mainly the cell membrane) has been damaged to a great extent under the action of strong mechanical shearing force and pressure during the crushing and rolling process; The colloidal structure of cells was further damaged. But none of the above destruction will and cannot be completely complete. Therefore, the oil cannot be completely squeezed out.

In addition, during the intense pressing process of the material embryo, the oil discharge gap has become very small, and the oil film in it has been extremely thin, which has caused it to lose the general hydrodynamic characteristics, and it is close to the properties of plastic solids. The molecular attraction of solid matter and the attraction between oil molecules will always retain a thin oil film, so the residual oil rate in the cake will not be too low.

It can be seen that, during the pressing process, it is impossible to squeeze out the oil in the embryo, and it is impossible to reduce the residual oil rate in the cake to a very low level.

Five, the formation of cake

During the pressing process, with the large amount of oil discharged, the trace water evaporates, the volume of the pressed material is continuously reduced, and the pressed material of the granular body finally forms a porous plastic body - cake.

The formation process of the cake is accompanied by several changes, such as the process of oil and fat from more discharge to less discharge, the rising process of pressure from low to high, and the process of pressing material from discontinuous phase to continuous phase.

The necessary condition for the pressed material to form cakes is that the pressed material must have suitable plasticity and can withstand pressure. Without plastic pressing, it is difficult to form cakes even if the pressure is high. The factors that affect the plasticity of the embryo are the moisture and temperature of the pressed embryo.

Section 2 The working principle and basic concepts of the screw oil press

1. Working principle

The working principle of the screw oil press, in a nutshell, is due to the propelling action of the rotating screw shaft in the pressing chamber, so that the pressing material continuously advances forward. In this process, due to the gradual reduction of the screw pitch of the screw, the width of the screw thread gradually increases, and the diameter of the root circle of the screw gradually increases, so that the space of the pressing chamber gradually becomes smaller, and the pressing material is compressed in the pressing chamber to produce a strong squeeze. pressure. In this way, the grease flows out from the gap of the squeezing cage, and the solid material is pressed into cakes and continuously discharged from the end of the screw shaft.

During the pressing process, the extrusion force is derived from the compression force, cake output resistance and friction resistance.

1. Compression force

After the embryo enters the press, it is firstly pressed into the pressing chamber by the vertical downward pressure of the feeding screw. The material is pushed forward by the rotating screw in the press chamber. In the process of propulsion, the fundamental reason for the compression of the material lies in the following two aspects:

(1) Squeeze snails. The screw pitch gradually decreases along the pushing direction, the thread width gradually increases, and the root circle diameter gradually increases.

(2) Squeeze the chamber. The inner diameter of the pressing chamber becomes smaller along the pushing direction (ZX·10 oil press does not have this structural feature).

The compression process experienced by the pressing material in the pressing chamber of several domestic screw oil presses is usually realized by two-stage pressing.

In the first stage of pressing, after the pressing material enters the pressing chamber, it is compressed due to the gradual shrinking of the pressing chamber space, and most of the oil is discharged. At this time, the structure of the pressing material is relatively tight, and with the push of the pressing screw, it enters the second stage of pressing.

In the second stage of pressing, when the pressing material just enters this stage of pressing, due to the sudden increase of the pressing chamber space, the original tight pressing material has a chance of loosening, the structure is adjusted, and the oil circuit is dredged. Then, the pressing material continues to be pushed along with the pressing screw. During the advancement, the space of the pressing chamber is smaller than that of the first-stage pressing, so that the pressing material is subjected to more intense pressing to squeeze out as much oil as possible. Finally, the pressed material is extruded from the annular cake gap to become cake blocks, thereby completing the second stage of pressing.

2. Cake out resistance

The annular cake gap at the end of the cake is formed by the cake ring (ZX·10 type oil press) or short sleeve (ZX·18 type oil press) on the screw shaft and the cake outlet fitted on the frame. Constructed of loops. The size of the gap can be adjusted, so as to control the discharged cake to reach the required thickness. The thickness of the cake directly affects the resistance of the embryo in the pressing chamber. When the gap of the cake outlet is increased, the thickness of the cake is large, the displacement is large, and it is easy to discharge. At this time, the resistance of the pressed material in the pressing chamber will be smaller; when the gap of the cake outlet is adjusted to be small, the thickness of the cake is thin and the displacement is small. , at this time, the resistance of the pressing material will be larger. Therefore, in the pressing process, in order to achieve a good process effect, the pressing material should be kept under a certain pressure in the pressing chamber to ensure that the oil in the material embryo is squeezed out as much as possible, which requires mastering and controlling the thickness of the cake. .

3. Frictional resistance

The movement of the blank in the press chamber includes axial movement and radial movement, and these movements are all irregular movements. These irregular movements will produce a variety of frictional resistances, including the frictional resistance between the material embryo and the pressed bar, the pressing ring, the material embryo and the screw press, and the material embryo and the material embryo. Among these frictional resistances, the former frictional resistance is the largest, because the press bar has edges and corners, and the inner cavity of the press ring has radial tooth grooves. The second is the second frictional resistance. Although the screw thread is smooth, it pushes the material during rotation, so its frictional resistance is not small. The latter is the frictional resistance between the blanks, which is caused by the irregularity of the movement of the blanks themselves. The biggest effect of the above frictional resistances is to establish sufficient pressure in the press chamber, and at the same time, it has certain benefits for continuously opening the oil passage between the blanks. In addition, due to frictional heat generation, the temperature of the pressing material is further increased, which further promotes the protein denaturation in the material embryo, the cell structure is destroyed, the plasticity is increased, and the viscosity of the oil is reduced, which is also conducive to the pressing of oil.

Regarding the pressure in the press chamber, according to the actual measurement and calculation data of the relevant models, the ZX·10 oil press reaches 24.5-43.8MPa in one press, the ZX·18 oil press reaches 24.0MPa in one press, and the ZY·24 19.1MPa during pre-pressing of type pre-press.

2. Basic Concepts

1. The compression curve of the press chamber

In the pressing chamber of the screw oil press, after the pressing material enters the feeding section, the screw thread width increases section by section, the pitch decreases, and the root circle diameter increases. compressed. In the press chamber, the degree of compression changes with the advancement of the material. The change of the compression degree in the process of pushing the material in the press chamber is depicted as an image, which is called the compression curve of the press chamber.

The compression process of the pressed material is divided into three stages, and the analysis is as follows:

(1) Feeding section. The pressed material is squeezed tightly in the feeding section, air and moisture are discharged, plastic deformation occurs, and oil starts to come out. Therefore, a small amount of oil droplets and air bubbles can be seen in the front section of the squeezing cage.

(2) Pressing section. The pressing chamber space of the pressing section shrinks rapidly and regularly, the pressing material is strongly pressed, and the grains of the material begin to combine to form a continuous porous material and discharge a large amount of oil. During this process, the material is also subjected to various frictions while being compressed. Specifically, due to the interruption of the screw screw, the shearing action of the pressing chamber and the edge of the pressing strip, the displacement of the material level, the fracture and mixing, etc., the oil circuit is continuously opened, so the grease can be quickly and fully discharged.

(3) into a cake segment. The pressed material has formed a block-shaped cake in the cake-forming section, which is almost integrally advanced, so it also has a large axial compression resistance. At this time, the compressibility of the tile cake is not large, but it is necessary to maintain a high pressure to drain the oil, and the process should be extended for an appropriate time, and the axial resistance should be reduced (the geometric size of the pressing screw here has been Has not changed much). If you think that the oil has been pressed clean at this time, so as to relax the pressure, then the hot cake will expand and loose but absorb oil, which is not good for pressing. The last discharged cake will generally expand due to elasticity or expansion.

2. Compression ratio and total compression ratio

(1) The free volume of squeezing snails. The free volume of the squeezing screw refers to the volume of space contained by each lead (pitch) squeezing screw in the squeezing chamber.

(2) Compression ratio. The compression ratio refers to the ratio of the corresponding free volume before and after the adjacent two-lead screw presses.

(3) Overall compression ratio. The ratio of the free volume of the first lead of the feed to the last lead of the cake outlet is the total compression ratio.

The compression ratio of the first stage of the ZX·10 oil press is 5.98, and the total compression ratio is 16.90; the total compression ratio of the ZX·18 oil press is 12.10; the ZY·24 pre-press is generally designed with two The total compression ratio is 9.60 for the set-pressed snails used for pre-pressing oil with medium oil content; the total compression ratio is 11.50 when used for pre-pressing oil with high oil content.

The significance of the compression ratio is to indicate the geometric characteristics of the cavity space. It has a great relationship with the pressing process of different oils. Usually, for the oil with different oil content, the pressing screw with the appropriate compression ratio should be selected during pressing.

For embryos with high oil content, it is better to have a larger compression ratio before pressing. If the compression ratio of this section is too small and the pressure is insufficient, the oil outlet position will be pushed back and the draining section will be reduced; for the material with low oil content, the compression ratio of the pre-pressing section should be smaller. If the compression ratio of this section is too large, the cake will be formed prematurely, and a part of the oil will be enclosed in the cake, so that it cannot be discharged smoothly. In short, different compression ratios should be selected according to different oil materials, so as to have a good pressing effect and prevent the residual oil rate of the cake from being too high.

It can be seen that each oil plant should be pressed with a set of screw presses that meet the compression ratio requirements, but the existing oil presses are generally only equipped with one set of screw presses. In view of this, in practice, both new and old snails can be used.

The actual compression ratio of the pressed material is smaller than the theoretical compression ratio (because the pressed material has elastic deformation, "returning material" and other factors). Generally, the ratio of theoretical compression ratio to actual compression ratio is 1.5-4.5, the actual compression ratio of ZX·18 oil press is 3.11-4.00, and the actual compression ratio of ZY·24 pre-press is 2.18-2.96.

3. Factors affecting oil extraction by screw oil press

There are many factors that affect the oil pressing effect of the screw oil press. To sum up, they mainly include the pretreatment quality of the embryo and the pressing process conditions:

For the pretreatment of the blank, the previous steps have been described in detail. The raw embryo is obtained after pretreatment, and its structure and physical and chemical properties must meet the requirements of pressing, and make it have suitable plasticity and pressure resistance, so as to meet the quality requirements of the raw embryo during pressing. The main factors affecting the quality of blank pretreatment are the moisture and temperature of blank. The effects of temperature and moisture on the quality of the embryos have been introduced in detail in the chapter on steaming and frying, and will not be repeated here.

The pressing process conditions include the pressure of the pressing chamber, the thickness of the cake, the compression ratio of the press, the pressing time, the temperature of the pressing chamber, and the change of the properties of the pressing material during the pressing process.

A point-by-point discussion follows:

(1) Influence of pressing chamber pressure on oil yield

The factors that affect the pressure of the press chamber are: the mechanical structure of the press chamber, the thickness of the cake, the speed of the screw shaft, the oil flow gap, the degree of use of the oil press, the pretreatment quality of the pressed material embryo, and the amount of feed. Wait. When the same oil press presses the same oil, and the feed amount is the same, the pressure of the pressing chamber is mainly related to the thickness of the cake and the speed of the screw shaft.

Under normal circumstances, the pressure of the pressing chamber of the oil press is inversely proportional to the thickness of the cake; the current intensity (reflecting the chamber pressure) is approximately proportional to the rotational speed of the screw shaft. Generally speaking, the higher the pressing chamber pressure, the higher the oil yield.

The pressure of the pressing chamber of the oil press is reflected by the reading of the ammeter. When the reading is large, the pressure is large; when the reading is small, the clear force is small; when the current fluctuates, the pressure is unstable. When the current intensity is stable, the press works normally, and the oil output is generally good at this time. The current intensity of the ZX·10 oil press during normal operation is 10-12A. The current intensity of ZX·18 oil press during normal operation is 25-28A, the minimum is >20A, and the maximum is <30A. The ZY·24 pre-press is about 55A.

(2) Influence of cake thickness on oil yield

The smaller the cake thickness, the higher the oil yield.

(3) Influence of compression ratio on oil yield

We know that the compression ratio and the total compression ratio are concepts that reflect the geometric characteristics of the press chamber. The compression ratio of the first stage of ZX·l0 oil press is 5.98, and the total compression ratio is 16.90. The total compression ratio of ZX·18 oil press is 12.10. The total compression ratios of the two sets of pressing screws of the ZY·24 pre-press are 9.60 and 11.50 respectively. The actual compression ratio of the pressed material cannot be directly measured so far, and can only be obtained by approximate calculation methods. Generally speaking, the larger the compression ratio of the press, the higher the oil yield. After the screw is worn to a certain extent, its compression ratio will decrease, so it needs to be replaced in time.

 (4) Influence of pressing time on oil yield

There is a certain relationship between pressing time and oil yield. Usually, the oil flow is relatively clean and the oil yield is high when the pressing time is long. However, the pressing time should not be too long, otherwise, the heat loss will be too much, and the oil yield will not increase significantly, on the contrary, it will affect the processing capacity of the equipment. Therefore, to determine the length of the pressing time, factors such as the properties of the pressed material, the pressure, the thickness of the cake, the oil content and the equipment structure must be comprehensively considered, and the pressing time should be shortened as much as possible on the premise of satisfying the oil production efficiency and beneficial to the quality of the oil product. This not only helps to increase the processing capacity of the equipment, but also reduces unnecessary production consumption.

For a screw oil press, the length of the pressing time is related to the speed of the screw shaft and the thickness of the cake. The pressing time of the commonly used oil presses is relatively short, the shortest is only tens of seconds, and the longest is only 2-3 minutes. Of course, in practice, the speed of the screw shaft and the thickness of the cake can be adjusted according to the needs, and the pressing time will also be changed accordingly.

When the thickness of the cake is fixed, the faster the speed of the screw shaft is, the shorter the pressing time is. On the contrary, when the speed of the screw shaft is constant, the pressing time is short when the cake is thick, and the pressing time is long when the cake is thin.

In addition, the length of the pressing time also varies according to the age of the pressed snails. The newly assembled screw thread has complete edges and corners, the propelling material is strong, and the embryo recovery is less, and the pressing time will be shorter; while the old screw screw is severely worn, the propulsion force is weak, the embryo recovery is increased, and the pressing time will be longer.

(5) Influence of pressing chamber temperature on oil yield

During the pressing process, due to the deformation, movement and friction of the pressing material particles in the pressing chamber, heating will occur, which will increase the temperature of the pressing chamber. The more thoroughly the oil is extracted during pressing, the more heat is generated, and the stronger the heating effect on the pressing material and the oil press.

Since the temperature of the pressing chamber directly affects the residual oil rate of the pressed cake (the temperature determines the depth of oil discharge), the "high temperature and low moisture" process is always adopted in the oil-pressing process of the screw press.

However, the temperature of the pressed material embryo has a certain limit, which cannot be higher than 130oC, which can be confirmed from the graph of the relationship between the oil yield and the temperature of the pressing chamber.

When the chamber temperature is higher than 130oC, the oil yield drops sharply, which is not good for production.

Although the heating effect in the pressing process is beneficial to the destruction and inhibition of enzymes in the pressed material (such as lipase in rice bran and vasinase in soybean), and some oil crops (such as rice bran, sesame, etc.) are pressed to obtain pressed cakes The storage and utilization of the pressed material is also beneficial, but the overheating of the pressed material will also have the following adverse effects on the pressing process: one is to cause the rapid evaporation of water, which destroys the normal plasticity of the pressed material during the pressing process; the second is to deepen the color of the pressed cake. , and even cause coking; the third is the protein-assisted denaturation effect (requires that the protein denaturation process is mainly completed in the steaming and frying process), which further reduces the soluble protein content and limits the comprehensive utilization of pressed cakes (however, some toxic protein denaturation is not effective. It is beneficial, such as castor protein chips); the fourth is to make some unfavorable changes in the chemical composition of the pressed material, such as the natural special aroma substances in the oil are volatilized or destroyed, and the vitamins are destroyed; the fifth is to crack the oil, resulting in an increase in the acid value of the oil. The sixth is to oxidize phospholipids and free fatty acids; the seventh is to promote the dissolution of pigments, waxes, unsaponifiables, phospholipids and other substances in the crude oil, making the quality worse, and so on.

It can be seen that in order to improve the pressing efficiency, it is necessary to control the increase of the temperature of the pressing chamber, and conduct appropriate cooling and cooling treatment on the pressing chamber.

Section 3 ZX·10 Oil Press

The original name of the ZX·10 type oil press is the 95 type oil press. It is a small oil pressing equipment produced in China with a history of nearly 40 years. This machine is suitable for pressing a variety of oil crops, such as soybean, cottonseed, rapeseed, corn germ and so on. It has the following characteristics: continuous production, simple supporting equipment, short body, convenient operation, suitable for small-scale production. It is especially suitable for rural township enterprises and individual processing factories.

1. Structure of ZX·10 Oil Press

ZX·l0 oil press is composed of feeding device, screw shaft, pressing cage, frame, machine base and transmission mechanism.

 (1) Feeding device

The feeding device mainly includes parts such as storage hopper, feeding hopper and feeding rod.

The storage hopper is made of a cylinder made of iron coil and a casting cone connected by screws. There is an observation hole on the cone, and a plug-in plate is installed at the feeding port to adjust the size of the feeding amount.

The casting feeding hopper is located at the lower part of the storage hopper, and is equipped with a transmission device that drives the feeding rod. The blanking port is also equipped with a control board to control the blanking amount.

The feeding rod is made of round steel and has 4 feeding fins welded. The lower part is also equipped with a pressing screw, which is firmly connected to the dialing rod with a flat key.

(2) Spiral shaft

The screw shaft, also known as the screw shaft, is one of the main components of the screw oil press. It is composed of pressing shaft, pressing screw, locking nut, retaining ring, adjusting bolt and tightening nut and other parts.

1. Press shaft

The pressing shaft, also known as the mandrel, is a high-strength part for assembling the pressing screw, and its surface hardness is HRC24-28o.

There is a keyway on the left end of the press shaft to assemble the large gear. And the shaft can move horizontally and axially in the center of the large gear wheel to adjust the thickness of the cake.

There is a long keyway in the middle of the pressing shaft, and there are retaining rings and 7 pressing screws in sequence from left to right. To the right, there is a left-handed thread with a length of 80 mm on the press shaft, the specification is M48×3, which is used to cover the lock nut and fix the press screw so that it does not move axially.

The journal at the right end of the press shaft is matched with the two shaft sleeves at both ends of the adjusting bolt and supports its rotation. At the same time, there is also a rolling bearing, model 8307, to bear the axial thrust.

The function of the adjusting bolt is to adjust the axial position of the screw shaft, so as to adjust the width of the annular gap between the cake ring and the cake outlet, and to control the thickness of the cake.

2. Squeeze the snails

The screw of ZX·10 oil press is a hollow cylindrical part made of high-quality carbon structural steel and wound with a threaded rib.

ZX·10 type oil press has 7 sections of screw press.

The characteristics of ZX·10 oil press for screw pressing: along the sequence of screw pressing section 1 to section 7, the diameter of the screw bottom gradually increases, the width of the thread is gradually widened, the pitch of the screw becomes smaller, and the height of the screw thread decreases. The fourth section has no thread, its length is 50 mm, the front section of the outer peak is 35 mm long, and its outer diameter gradually increases from 90.5 mm to 94.5 mm. The rear section of the peripheral peak is 15 mm long, and its peripheral diameter is gradually reduced from 94.5 mm to 80 mm. There is an ups and downs in the middle, mainly causing secondary pressing. The seventh section of the screw press is the cake ring, which has no thread, and its diameter gradually increases from 94.5mm to 106mm. There is a bushing in the cake ring, which is matched with it by a flat key. And the bushing is matched with the pressing shaft by the flat key. The length of each section of the screw press is gradually shortened in sequence, and each section of the screw press is closely matched with the pressing shaft with a flat key.

3. Lock nut and retaining ring

The locking nut and the retaining ring are used to fix the pressing screw, so that the pressing screw does not move axially, and each section of the pressing screw is closely matched.

The lock nut is a gray iron casting, and the inner hole is matched with the press shaft through a left-hand thread. It has four sockets evenly distributed on its outer circumference for tightening the lock nut. When 4 sticks are installed, it can also be used for breaking cakes.

The outer diameter of the retaining ring is 85 mm, the inner diameter is 48 mm, and the thickness is 20 mm. In addition to the fixing function of the screw, it can also act as a barrier between the material entering the pressing chamber and the gear box.

4. Adjusting bolt and set nut

The adjusting bolt is a gray iron casting, and its function is to adjust the thickness of the cake. The outer edge has a left-handed trapezoidal thread with a length of 154 mm, and the thickness of the cake can be adjusted by 0.4 mm for each rotation. There are 4 toggle handles installed on the adjustment bolt, and there is an oil cup at the bearing bush.

The function of the set nut is to fix the adjusting bolt that adjusts the axial position of the screw shaft on the frame; to prevent the uranium from being displaced by itself during the operation, so that the thickness of the cake can be kept as required by the process. Set nuts are made of 45-gauge steel or ductile iron.

(3) squeeze cage

The squeezing cage is also one of the main components of the screw oil press. The press cage of ZX·10 oil press includes the following parts: press cage shell, press ring, press bar, cake ring, compression screw, oil receiving tray and cover, etc.

1. Squeeze the cage

The cage shell is made of ductile iron, divided into upper and lower halves, and the two halves are fixed together with 10 bolts. Generally, only the upper half can be removed for maintenance. One end of the lower squeeze cage is connected with the frame, and the other end is connected with the gear box. There is a keyway in the middle of the inner circle of the lower pressing cage, and a flat key is fixed with a countersunk head screw to fix the pressing ring and the pressing ring.

2. Pressed strips and pressed strips

The pressed bar is made of No. 20 high-quality carbon structural steel, which is carburized and quenched.

The pressed bars are installed in the pressed bar ring, a total of 16, and are packed in a circle. In addition, there is a locking press rod inserted in between, so that the press rod is tightly combined.

The press ring is made of HT20-40 gray moon iron. The end face in contact with the pressing ring has 220 radial oil grooves, the depth of which is 0.4-0.7 mm. The outer surface of the press ring is provided with a longitudinal keyway, which is matched with the press cage shell through a flat key.

3. Press ring

The press ring is made of No. 20 high-quality carbon structural steel, and is quenched by the infiltration team. The inner ring of the pressing ring is processed into ten curved saw teeth, and one end face has an oil groove.

The function of the ten curved saw teeth in the pressing ring of the ZX·10 type oil press is to form an unsmooth curved surface in the pressing chamber, so as to increase the frictional resistance and turning ability of the material embryo in the pressing chamber. In addition, there is also a part of the conical surface (that is, the chamfer) at the end of the inner curved surface of the pressing ring, which plays the role of buffer transition of the material. The position of the cone surface of each pressing ring is different, there are left and right sides. Only the No. 7 press ring has no curved serrations.

The ZX·10 oil press has a total of 14 pressing rings, and all the pressing rings are provided with key grooves on the outside to match the flat keys in the middle of the lower pressing cage, so that they do not rotate with the screw shaft. After all the press rings are assembled, the serrations on the inner surface of the ring are superimposed on each other.

4. Take out the cake ring and press the screw

The cake ring is a steel ring made of No. 20 high-quality carbon structural steel, which has been carburized and quenched, and has a length of 55 mm. Its outer circle is finished after finishing, embedded in the compression screw, and cooperates with the cake ring to form a cake gap.

The function of the compression screw is to compress the press ring and the press ring, so that they do not move axially. One end of the inner ring is matched with the cake outlet ring, and the outer circumference is a thread with a length of 45 mm, which is screwed into the thread of the cake outlet end of the squeezing cage to play a pressing role. The other end of the outer ring is drilled with 6 uniform holes with a hole diameter of 25.5, which are used for insertion during assembly and disassembly.

In addition, there is a cover on the periphery of the squeezing cage to prevent the oil residue from splashing due to the high pressure of the squeezing chamber. There is also an oil receiving tray under the squeezing cage shell, which is used to collect the oil squeezed out of the squeezing chamber.

(4) Rack and base

As can be seen from the previous assembly drawing, the upper outer side of the frame is the wire sleeve of the adjusting bolt, and the inner side is connected with the cage shell. The frame is cast with HT20-40. The base is made of HTl5-33, one end of which is combined with the frame, and the other end is combined with the gear box.

(5) Transmission mechanism

Transmission system of ZX·10 oil press.

3. Operation of ZX·10 Oil Press

(1) Preparations before driving

(1) After the new press has been transported and stored, it should be cleaned before use, wipe off the anti-rust paint everywhere, pull out the screw shaft, remove the upper press shell, and polish the outer surface of the press screw and the inner surface of the press ring with emery cloth Glossy.

(2) Check the level of lubricating oil in the gearbox. If it is insufficient, add oil or gear oil, and check all other lubricating parts in detail and add lubricating oil.

(3) Check whether there are foreign objects such as iron blocks in the press chamber, and turn the V-belt pulley by hand to make the press shaft rotate more than eight times to check whether there is jamming, and pay attention to whether the gear meshing in the gearbox is normal.

(4) Check and adjust the tension of the belt. If the belt is too loose, the belt will slip, reduce the transmission efficiency, and affect the service life of the belt. If it is too tight, the radial tension of the motor shaft will be increased, and the bearing will be prone to heat and burn out.

(5) Check whether the cake outlet is loosened. If it is too tight, sudden blanking will cause blockage of the material embryo, and even equipment accidents will occur due to excessive load.

(2) Driving

1. Start the motor, generally run empty for 15 minutes to observe whether the no-load current is normal (about 3A), the current is too high

Stop and check before driving. When idling, pay attention to whether the sound in the gearbox is normal, and whether the bearing parts and the motor are hot.

2. After everything is normal, the pretreated embryo can be put into the pressing chamber. At the beginning of pressing, the temperature of the embryo entering the pressing can be appropriately lower, and the moisture content can be higher. The cutting amount should not be too strong, otherwise the pressing chamber will be easily blocked, and even no oil will be produced.

3. As the temperature of the pressing chamber increases, the pressing material embryo can gradually increase, the moisture of the material embryo can also gradually decrease, and the pressing temperature gradually increases.

4. Rotate the adjustment screw to gradually reduce the thickness of the cake. After the oil is normal, tighten the set nut, and the press enters the normal operation stage, and then gradually squeeze out the more oily broken cake. Evenly mix into the embryo, steam, fry and press.

5. After normal operation, the feeding must be kept uniform, and not too much or too little, otherwise it will affect the oil yield and the life of the oil press. Generally, the thickness of the cake is controlled at 4-5mm, the pressing temperature is 110-120 ℃ (for rapeseed), and the pressing moisture is about 2-3.5% (for rapeseed), which can be adjusted according to different oil varieties.

6. Pay attention to the reading of the ammeter. Generally, the current is 14-16A during normal operation. When it exceeds, it means that the pressure increases and the load increases; if it suddenly increases, it means that the press chamber is blocked, and the feeding should be stopped immediately. When the feeding is resumed, it cannot be lowered all of a sudden, so stop the machine immediately; if the amperage is found to be too low, it means that the feeding is insufficient and the pressure is not enough.

7. Pay attention to the situation of the cake. Normally, the cake is tile-shaped, one side is smooth, and the other side has many small cracks, which quickly becomes hard when it falls. If the pressed water is too high, the cake will be soft and weak; if the pressed water is too low, the cake will not be formed, and there will be more powder, darker color, and a burnt smell.

8. Observe the oil output. During normal operation, most of the oil output position is concentrated in the press ring (except rice bran), and a small amount of oil flows out of several press rings near the press ring, and the oil is very clear. If the moisture of the pressed material embryo is too high or too low, the oil outlet position will move backward in the direction of the cake outlet, and the foam in the oil will increase or the oil will be turbid, and the residual oil in the cake will also increase.

9. Observe the slag situation. During normal operation, there is generally little slag between the pressing rings. If the moisture content of the pressed material embryo is too high, flaky slag will flow out near the pressing bar; There is powdery or filamentous slag flowing out from each pressing ring.

(3) Parking

1. Before stopping the machine normally, stop feeding, loosen the cake outlet, then feed a small amount of oil cake or raw material embryo, and push out the clinker embryo in the pressing chamber before stopping, which can prevent the clinker embryo from pressing in the pressing chamber. The inner knot is hard to avoid major accidents such as twisting and breaking of the pressing shaft and bursting of the pressing cage.

2. In case of emergency stop due to sudden power failure and other situations, the power supply should be cut off first, and then the vehicle should be cranked manually. After all the blanks in the press chamber are coiled out, the vehicle can be restarted, otherwise the vehicle must be dismantled after a long time.

Four, maintenance points

1. Always pay attention to whether the moving parts are abnormal, check whether the fasteners are firm, and whether the oil supply of each lubricating part is sufficient.

2. Replace the abrasive parts in time.

3. Wipe the press frequently to keep the whole machine clean.

4. Regular maintenance, generally a small maintenance once a month, once in half a year, and a major maintenance once a year. During maintenance, the lubricating oil in the gearbox should be replaced in time.

Section 4 ZX·18 and ZY·24 Oil Presses

1. ZX·18 oil press

The ZX·18 oil press (or the original 200 oil press) is a kind of oil pressing equipment with relatively good domestic performance. It has a wide range of uses, and is widely used for oilseeds such as rapeseed, peanut, soybean, cottonseed, sunflower seed, and saffron. In the south, it can also be used to press copra, rice bran and other oils.

The advantages of ZX·18 oil press are compact structure, good performance, convenient operation and small occupation of working surface. The disadvantage is that it consumes a lot of power and needs a motor with a capacity of 17-2Okw. If the machine is overloaded during operation, there is no automatic control mechanism. It is labor-intensive and difficult to disassemble and assemble vulnerable parts such as screw presses and press bars. When the screw press assembly is not tight, there will be oil leakage from the mandrel during the pressing process. Sometimes the feeding mechanism will also appear the phenomenon of bypassing and not feeding.

ZX·18 oil press consists of feeding mechanism, screw shaft, squeezing cage, school cake mechanism, adjusting frying pan and transmission mechanism.

(1) Feeding mechanism

The feeding mechanism consists of upper and lower feeding hoppers. Its functions are: the upper feeding hopper is used to accept and adjust the cooked embryos discharged from the frying pan, and its flow rate is controlled by moving the handle to turn the movable material gate; the lower feeding hopper is used to observe the feeding situation. "Can be cleared in time. The feeding mechanism is equipped with a feeding shaft, and the lower end of the feeding shaft is equipped with a feeding screw to forcibly press the material embryo into the pressing chamber.

(2) Screw shaft The screw shaft is the main working part of the ZX·18 oil press. The length of its mandrel is 1960 mm, and there are 7 press screws and 6 bushings on it, all of which are matched with flat keys to form a left-handed screw shaft. The first section of the screw press has a double-ended thread to accelerate the advancement of the material embryo; the second section of the screw press is tapered at the bottom end of the screw, thus forming the first stage of pressing. This is followed by the second stage of pressing. There is a lining ring on the screw sleeve between the pressing screw and the pressing screw, which plays two roles, one is the transition between different screw root diameters; the other is the scraper installed in the inner cavity of the pressing cage corresponding to the bushing Cooperate, start the turning function of the embryo. At the right end of the first section of the screw, the mandrel is covered with a cast iron inlaid copper sleeve sliding shaft and is locked with a special left-handed nut and a left-handed stop nut. The left end of the screw shaft is connected to the output shaft of the reduction box through a coupling. During normal operation, looking at the feed end of the oil press, the screw shaft rotates clockwise.

Both the squeeze screw and the lining ring are made of 20# steel, and the hardness after quenching is HRC55-62o. The material of the mandrel is 4OCr steel, the hardness reaches HRC24o-30o.

(3) squeeze cage

The squeeze cage is composed of cage plate, generous iron, special bolts, squeeze bars and other parts. It is divided into upper and lower halves, each with 12 cage plates with a thickness of 25 mm and a spacing of 65 mm. The two halves of the cage are combined into a whole with special bolts and square iron. The built-in press bar is divided into 4 sections, the first section has 44 pieces, the size is 178×19×10 mm, and the inner cavity diameter is φ80 mm. The second, third and fourth sections are equipped with a total of 114 press bars, the size is 276×19×10 mm, and the inner cavity diameter is φ152 mm. In addition, each section is equipped with two convex press bars, which are locking press bars, and the function of the pressing plate is to press the press bars. Due to the different diameters of the inner cavities assembled into the first and second stage press rods, two conical split rings with inner cavities are used for fitting and transition. In addition, there is also a press chamber resistance on the wall of the press chamber, and its position just corresponds to the lining ring on the screw shaft.

When installing the press bar, make the edges and corners of the press bar follow the rotation direction of the screw shaft, so as not to cause the cake crumbs to be pressed into the oil discharge gap too much. There are two ways to install the press bar. One is to install it from both sides first, and then lock it with a convex press bar when it is gathered in the middle; the other is to install it from one side first, and then install it on the other side. The pressure plate is fixed.

The oil gap between the press bars is caused by the use of gaskets to spread the press bars. Gaskets are made of 45NiMn steel. The pressed bar is made of low-carbon steel, carburized on the surface, and the hardness reaches HRC62o.

 (4) School cake organization

The cake calibration device of the ZX·18 oil press is set on the cake outlet end of the screw shaft with a cake abutting head that can move in the axial direction. When the cake calibration device is working, the cake outlet ring and the screw shaft do not need to move axially. , the gap between the cake abutting head and the cake outlet ring is changed only by the axial movement of the cake bearing head sleeved on the screw shaft, thereby changing the thickness of the cake outlet. This kind of cake calibration device makes the pressing shaft in good condition, but it is not easy to adjust the cake thickness during operation, and it is easy to cause the phenomenon of slag leakage and deadlock.

Both the school cake head and the cake ring fixed on the body wall are tapered, so the thickness of the cake can be controlled by adjusting the gap between them. The school cake head is connected with the back section of the school cake head by threads. There are also three sticks in the back section of the school cake head. They are evenly distributed along the circumference. They have two functions. The second is to connect the rear section of the school cake head with the gasket. The groove of the washer is embedded with the protruding part of the inner ring of the split ring, and the split ring is connected to the school pan with 6 bolts. The cake pan is connected with the trapezoidal threaded round nut with a flat key, and the trapezoidal threaded round nut is matched with the trapezoidal threaded bushing, and the bushing is connected with the pressing shaft with a flat key, so that they can both move in the axial direction. , can also rotate with the shaft. In addition, the shaft sleeve is also connected with the washer by a flat key, and the flat key has two screw holes, and the washer is fastened with the countersunk head screw, so as to ensure that the washer and the flat key are on the outer edge of the shaft sleeve together slide in the keyway. When the cake calibration device is working, the cake ring and the pressing shaft do not need to be moved axially, and the cake calibration head can be moved axially on the shaft only by pulling the cake calibration plate. the gap to change the thickness of the cake.

(5) Adjust the wok and the base

The structure of the adjustment frying pan of the ZX·I8 oil press is similar to that of the steaming frying pan, generally with 3 layers. Its outer diameter is 1240 mm, inner diameter is 1220 mm, the total height of 3 layers is 1318 mm, the total volume is 1.2 m3, the effective volume is 0.72 m3, the heating area is 4.5 m2, and the stirring shaft speed is 35 rpm. But the bottom frying pan has no edge steam jacket, only the bottom steam jacket.

The cross-section of the base of the ZX·18 oil press is "M"-shaped, and there is a screw conveyor in the middle. The screw conveyor is used to transport the oil and cake residue discharged from the squeezing cage, and then the conveying machinery will send it into the oil tank and other equipment for oil residue separation.

(6) Transmission mechanism

The transmission system of ZX·18 oil press is divided into 4 parts.

1. Transmission of the screw shaft

The small V-belt pulley (1) on the motor drives the large V-belt pulley (2) on the gear box through the V-belt to realize one deceleration. The small bevel gear (3) coaxial with the large V-belt pulley drives the large bevel gear (4) to realize secondary deceleration and 90o reversal. The small cylindrical helical gear (5) coaxial with the large bevel gear (4) drives the helical shaft of the large cylindrical helical gear (6) meshing with it, that is, the helical shaft of the large cylindrical helical gear is connected with the shaft of the large cylindrical helical gear through a coupling to realize three reductions. , its speed is 8.08 rpm.

2. Adjust the drive of the stirring shaft of the wok

The small flat belt pulley (9) coaxial with the large triangle belt pulley (2) on the gear box is driven by the flat belt to adjust the large flat belt pulley (10) on the frying pan to realize one deceleration. The small bevel gear (11) coaxial with the large flat pulley (10) on the adjusting frying pan meshes with the large bevel gear (12) to make it decelerate twice and reverse the direction by 90°. The shaft of this large bevel gear is to adjust the stirring in the wok.

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Time of issue:2021-12-24 13:33:23

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Address

No. 88 Dongan Road Economic Development Zone in Suzhou, Taicang City Regal(PC:215415)

 

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Time of issue:2021-12-24 13:57:34

Copyright:Taicang Baoma Oils & Fats Equipment Co.,Ltd.

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Time of issue:2021-12-24 14:02:17