The Design of the Discharging Mode and the Bottom Structure of the Rice Husk Steel Silo

Rice husk is the main auxiliary material of brewing liquor and a kind of excellent filler. The quality of rice husk has a great impact on the liquor quality. With the continuous size expansion of the liquor plant and the rapid development of mechanized liquor brewing process, the demand for rice husk also increases greatly. And in the aspects of relevant transportation, cleaning and storage, how to adapt to the requirements of mechanized liquor brewing process is an urgent problem to be solved.
In the liquor plant, taking into account the characteristics of the arch phenomenon of rice husk, the storage for rice husk follows the forms of traditional packaging or bulk in flat warehouse so far, which has brought great difficulties to the mechanized production. The use of steel silo in storage and the multi-holes discharging bottom structure, supplemented by appropriate manual helps, people can solve the arch problem and provide better conditions for the cleaning, transportation and storage automation operations of rice husk.

I. The selection of the discharging mode

It is seldom to use steel silo to store rice husk in the liquor industry nowadays. The main reason is about the discharging difficulty. People have adopted a number of methods in the rice husk processing industry in the actual design, including  Dia.16m underpants-type double outlet design, Dia. 13m quadruple cone design, Dia. 11m cross segment bottom quadruple cone design, Dia. 6m V-groove multi-holes discharging design, etc. People have gotten a certain experience. Although these methods cannot completely solve the problem, people can restore normal use of the silo with manual breaking the arch.
Among them, the V-groove multi-holes discharging design is the best one in effect. The cross segment bottom quadruple cone design follows, and the underpants-type double outlet design is the worst. Taking into account of the higher base size of the V-groove multi-holes discharging design and underpants-type double outlet design, especially for more than 15m large steel silo, the base size will be higher, the cross segment bottom quadruple cone design is at the first place of selection.  
From the viewpoint of the stress analysis of the arch phenomenon, people often think that because the frictional resistance among the rice husks is very large, it is difficult to form the whole flow for the large steel silo. In the view of the mentioned situation above, adopting the multi-holes design and discharging from different holes in sequence in different times can break the balanced support of rice husk in the silo and lead to the overall flowing improvement of the rice husk and be conducive to prevent the arch phenomenon.
 

II. The configuration of silo type and structural design

Rice husks are generally stored in spiral steel silos. The spiral steel silo has the characteristics of good overall performance, long service life, good airtight performance, short construction period, low cost, small occupation, easy management and high strength. The silo base adopts a fully enclosed steel-concrete structure, and the silo bottom adopts the multi-holes discharging cone design so as to avoid the possibility of the arch phenomenon of rice husk.

 
III. The cone structure design of the silo bottom

The multi-square bucket design is most commonly used, but it will leave a number of bow platforms around and need to make the treatment of filling the slope that not only wastes silo capacity, but also increases additional costs and silo weight. So how to minimize the volume of filling the slope?
 
People have had the simulation and calculation. Taking seven-hole discharging cone, thirteen-hole discharging square bucket, seven-hole discharging honeycomb cone for examples, the results show that the seven-hole discharging honeycomb cone can fill the smallest volume. Meanwhile, the arrangement of discharging holes shall be conducive to the layout of the delivering equipments of the material. The three methods above are required to arrange three discharging equipments. But unlike the other two methods, the numbers of the thirteen-hole discharging square bucket is more than six, making the number of material delivering equipments also increase. Accordingly, the discharging gates and negative pressure feeding device shall be also increased.
On the other hand, in the case of the same slope angle, the number of cone will affect the height of the base bottom, and thus affect the silo height. This is conducive to the stability of the silo. In addition, for the multi-cone design, the cone bearing load is also considered with the same problem. Obviously, neatly arranged square bucket design is conducive to arrange the load beam and civil construction.
The internal friction angle of rice husk is 42°-45°. It is tested that the outer friction angle of rice husk and steel coil is about 37°. The maximum design slope is 60°, which can ensure that the slope of cross line of each side is greater than that of friction angle. In the cone production, people need to consider conserving materials, reducing the cone weight to ensure  the stiffness needs of the cone sides be sufficient.
 

IV. The arch breaking problem

When the storage time of rice husk is too long or the water content is too high, the arch phenomenon will happen, which could form the cone flow so that the rice husk cannot be discharged from the gravity. To solve this, we can open a number of holes as quick-opening doors on the side wall of the cone, once the arch phenomenon happens, people can use a long thin stick to insert into the hole to break the arch.
 
In addition, it is necessary to give the drying treatment on rice husk in the silo. For the longer-term storage of rice husk, we need to do heat and water insulation treatment, which can significantly reduce the arch phenomenon. 
 
FLYER Company has rich experience in design and construction of modern large spiral steel silo. We can effectively solve complex problems. If you have any problems or other requirements, please contact with us freely. We will provide you with relevant specified information. We expect to build a long term partnership with you!