1. Rice processing process
In view of the whitening polishing effect of various rice mills and polishing machines commonly used in the country, and processing standard one and standard two ordinary precision rice, only one or two rollers can be used to grind white; if processing clean rice (also The high-precision grades such as rice, pearl rice, crystal rice, etc., must be milled with three or even four rollers, and then polished by multiple rollers before they can be obtained. Although many rice processing companies are currently restricted by production sites and plant buildings, their rice processing equipment usually adopts floor layout or platform layout, but their rice processing processes are basically similar.
(1) The processing of rice with ordinary accuracy grade rice → cleaning → go stone → glutinous rice → grain rough separation → whitening → white rice classification → packaging → storage.
(2) Processing of high-precision grade rice rice → early clearing → cleaning → removing stone → wolfberry → coarse grain separation → selection of brown rice (thickness grading) → multi-level light milling → white rice classification → multi-level polishing → white rice classification → from rice Selection (length classification) → color selection purification → packaging → storage.
2. Reasons for increase in the processing of rice
The actual production experience shows that there are many reasons for the fragmentation in the processing of rice, and they are summarized in three aspects. The first is the quality of rice itself; the second is the various treatments that rice is subjected to before it is processed, such as the state of rice when it is harvested, the mechanical shocks that rice undergoes during threshing, sun drying, loading and unloading, and transport, and pests and moisture during storage and storage. , Mildew, etc.; The third is the rice processing machinery and equipment, process performance and operational management. The quality of rice and the various treatments it undergoes before it is processed are usually congenital, and rice processing companies can only adapt to it without changing it. Therefore, the technological performance and operation and management level of rice processing machinery and equipment are the main reasons for the increase in crushing in rice processing, and are reflected in the following aspects.
1 rice processing process
Good quality rice can be processed into high-precision rice, but also can be processed into normal-precision rice. However, poor-quality rice can only be processed into normal-precision rice. If it is hard to process poor-quality rice into high-precision rice It will inevitably produce a lot of broken rice. Therefore, first of all, rice should be processed according to the quality of rice by selecting a suitable rice processing process.
2 rice processing management
Extra large grain rice and special grain rice are first separated and classified and processed to ensure that the raw grains entering the equipment such as the rakes, rice mills, and polishers tend to be uniform in grain size, thereby increasing the shelling rate of the husker and preventing During grinding and polishing, there was an insufficient polishing and/or non-uniform whitening of the white grain of the raw grain, and the phenomenon that the large grain grain was over-ground and had a large amount of broken rice. Therefore, processing should be based on the classification of rice types, varieties, quality, moisture content, freshness, and aging, and must not be mixed and processed.
3. Rice processing machinery and equipment
The production experience shows that the rice processing machinery and equipment that cause the crushing of the rice processing process are mainly rakes, grain separators, rice mills, polishers and bucket elevators.
(1) Rucking machine, grain separator
When rice enters two opposite directions and rotates the two rollers, the paddy is squeezed by the rubber roller, rubbed and teared, and the rice husk is forced to peel off and separate from the brown rice. Because the rubber has excellent elastic deformation ability, it is not easy to damage the brown rice grain, so at present domestic rice processing enterprises almost all use the roller roller husk machine to remove the rice husk. When the pressure between two rubber rollers of the roller roller husker increases, the pressure and friction force of the rubber roller on the rice grain increases, the tearing effect of the roller increases, and the shelling rate also increases. However, the waist rate and the crushing rate of the brown rice also increase. Therefore, according to the variety, quality, moisture content, and grain shape of the raw grains, the appropriate roll-to-roll pressure, the line speed of the two rubber rollers, and the difference in line speed should be selected to ensure a higher shelling rate, a smaller bursting rate, and a lower level. Crushed rate.
If the hull and grain separation process is not effective, then the grain content in the back sorghum valley increases, causing excessive brown rice and chaff to enter the working area of ​​the squeezing machine. This may result in two consequences: On the one hand, it will reduce the opportunity for rice to enter the working area of ​​the rubber rollers in the rake, resulting in a decrease in the output of the rake; on the other hand, the brown rice will be squeezed again in the working area of ​​the squeezing machine. Crushed rate. Thus, it can be seen that increasing the purity of the back sorghum grain, reducing the grain size of the back sorghum, and the amount of rice hull contained in the grain are the preconditions for increasing the shelling rate and reducing the crushed grain rate of the husker.
(2) Milling machine
Although rice mills can be divided into horizontal rice mills and vertical rice mills according to their working methods, they can be divided into sand roller rice mills and iron roller rice mills according to the material of the roller. Similar, that is, the unit production of white rolling area, white room clearance, roll roller shape, pressure screen strips, rice screen, sieve bracket, pressure and pressure of the exhaust fan and air pressure.
1 unit yield whitening exercise area. Milling rice is to force the movement of the rice grain fluid by rotating the roller at a suitable rotational speed, so that collision and friction occur between the moving state of the rice fluid and the components of the whitening chamber and the rice grains. The rice grains are subjected to rolling, grinding, rubbing and rubbing away and the like. Mipi removed. If the unit production yield is too large, the movement of the rice grains such as tumbling, grinding, and friction rubbing will become very severe, and whitening and other phenomena will easily occur. Although the accuracy level of rice obtained was improved, the amount of broken rice was also significantly increased.
2 white room clearance. If the gap between the whitening chamber (commonly referred to as "storage gas") is too large, or the gap between the whitening chamber is increased due to the abrasion of the grind roller, the pressure screen strip, the rice screen and the dial roller, etc., the rice grains will produce a large amount when the rice mill is operated. Harmful return movements, resulting in a decline in the output of rice mills, increased electricity consumption per unit of output, and increased broken rice. If the gap between the whitening chambers is too small, the rice grains are greatly affected by tumbling, grinding, rubbing, rubbing, etc., resulting in broken rice. At the same time, the rice grains are easily broken to produce broken rice. Therefore, the gap should be selected suitable for white room, usually slightly longer than a grain of rice is appropriate.
3 roll roller shape. The roller can be divided into sand roller and iron roller, sand roller is used for sand roller rice machine, and iron roller is used for iron roller rice machine. The roller can be divided into smooth cylindrical roller (abbreviated as smooth roller) and spiral grooved cylindrical roller (simply referred to as spiral groove roller) according to the structural form. Because the spiral groove roller impacts, rolls, and grinds the grain of rice. Rubbing and rubbing away from the effect is relatively soft, rice milling process effect is good; and smooth sand roller has a greater effect on the rice, easy to cause broken rice, has now been gradually replaced by spiral groove roller. Iron rollers are generally divided into two-bar steel iron rollers and three-bar steel iron rollers. The three-bar steel iron rollers have a relatively gentle effect on the collision, rolling, grinding, and friction rubbing of rice grains. The rice milling process has a good effect; Two-bar steel iron rollers have a relatively large impact on rice grains such as impact, rolling, grinding, and friction rubbing, which can easily cause broken rice. In addition, the relative positions of the iron roller press ribs and the iron roller rotation axis can be further divided into straight rib iron rollers and diagonal rib steel bars. The inclined iron roller has a relatively gentle effect on the collision, rolling, grinding and rubbing away from the rice grains, and the rice milling process has a better effect. The straight iron roller has a greater effect on the rice grains and can easily cause broken rice.
4 pressure screen strips. Pressure bar (sometimes also called rice knife) can aggravate rice impact, rolling, grinding and rubbing away from the role, is conducive to uniform white rice. If the filter bar is too thin, it will have less impact on the impact, rolling, grinding and rubbing away from the rice. The precision of grinding the rice is lower; if the bar is too thick, then the white room gap Too much reduction, it has a very severe effect on the collision, rolling, grinding and rubbing away from the rice, and it can easily cause broken rice.
5 meters sieve. Rice mill rice sieve according to the shape can be divided into arc-shaped rice sieve and regular polygon rice sieve, which arc-shaped rice sieve is usually used for sand roller rice machine, regular polygon rice sieve is usually used for iron roller rice machine. According to whether the surface of rice sieve has any round bumps, it can be divided into non-bump rice sieves and convex rice sieves. The bump rice sieve (usually used only for iron rice rolls) collides, rolls, mills and rubs against rice grains. Efforts such as rubbing are very severe and can easily cause broken rice. The rice sieve mesh is usually a rectangular hole. If the size of the mesh is too large, although the row is clean, the rice is easily broken into the sieve and broken, resulting in broken rice; if the size of the sieve is too small, the row is not smooth, especially When processing high-moisture raw grains, it is very easy to plug the sieve holes. If the processing is not stopped in time, broken rice will also be produced. If the angle between the rectangular hole of the meter screen and the rotation direction of the roller is an acute angle, then the rice screen will have a gentle effect on the collision, rolling, milling, and frictional rubbing of the rice grains, which is beneficial to the uniform whitening of the rice grains. Larger internal pressure usually adopts this form). If the angle between the oblong screen and the rotation direction of the roller is obtuse, then the screen will have a very severe effect on the rice and it will easily cause broken rice (usually this form is not used in actual production). If the rectangular screen of the rice screen is in the same direction as the rotation of the roller, then the impact, tumbling, grinding, and frictional rubbing of the rice screen on the rice are between the above two. In general, the meter is still softer and is beneficial to the grain of rice. Uniform whitening (Sand roller rice machine usually adopts this form because of the small internal pressure). Therefore, according to the variety of raw grains, size and size of the water content, sieve mesh sieves of suitable size and structure should be selected.
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