(8) to avoid (flat bottom bin) junction tube under extreme conditions: when FIG. 9, when δ '= 46 °, δ = 66 °, the flow factor ƒ ƒ = 8.6 plotted in Figure 11c on the line ƒ ƒ =. 3.6, extrapolation can be obtained ƒ cc = 25kPa and γ = 2500kg / m 3 .
(9) When δ' = 46°, Figure 12 shows K = 1.1.
(10) Avoid the minimum discharge opening diameter of the (flat bottom) tube is calculated according to Equation 8:
(It can be seen that in this case, the flat bottom bin or the bottom of the bottom of the warehouse should be selected with a small angle between the horizontal and the horizontal.)
{Example 2} When the discharge opening of the tapered steel hopper is 50 m 3 /min and the discharge opening width is 50 cm, the length of the discharge opening is obtained.
Solution: From Example 1, we can see that ƒ ƒ = 1.06, ƒ cc = 8.5 kPa, σ 1 = 9 kPa, γ = 2120 kg / m 3 . The consolidation pressure of the silo discharge port is calculated according to formula (12):
σ 1 = 2120 × 0.5 × 9.8 × 1.06 = 11000Pa = 11.3kPa
When the consolidation pressure σ = 11 kPa, γ = 2180 kg / m 3 (Fig. 11b). Correct the consolidation pressure of the discharge port:
σ 1 = 2180 × 0.5 × 9.8 × 1.06 = 13000Pa = 11.3kPa
Correspondingly, the stress σ y = 9.5 kPa acting on the blockage of the discharge port (ie, the critical open yield strength ƒ cc = 9.5 kPa on the blockage of the discharge opening). Then, the actual flow factor should be calculated according to the formula:
After solving, L = 1.3m.
It can be seen from the above calculation that in order to avoid the arching and knotting of the silo, the fluidity of the material should be tested and determined. In the design, increase the size of the discharge port as much as possible, increase the number of discharge ports; at the same time, to correctly select the angle of the bucket, it is best not to use a flat bottom. [next]
(three) warehouse
The shape of the bucket's bucket, the most common is the symmetrical cone, because it is easier to build. If the inclination of the bucket is not enough, the material flow of the flat bottom bin will occur.
Round, square and rectangular buckets can be designed to be eccentric when storing difficult to flow materials. Since the side wall of the bin is vertical, a stable arch does not occur. In order to avoid the knot phenomenon, a strip discharge port may be used, and the length may be almost equal to the diameter of the cartridge body.
The inclined wall of the bucket has a significant impact on the fluidity of the material. Theoretically, the minimum inclination of the wall of the bucket (if it is a pyramid, it should be the slope of the intersection of the two inclined walls) should be equal to or greater than the friction angle of the material to the wall. However, it has been proved that the inclination angle of the wall of the bucket should be equal to the collapse angle of the material due to changes in the mud, water, and storage compaction time of the material.
The formula for calculating the inclination of the intersection of the two inclined walls of the pyramidal bucket (Fig. 13) is:
It is worth noting that a section of the cone from the lower part of the bucket to the discharge opening is preferably made of steel and has a height of not less than 1.5 m to increase the discharge opening of the upper reinforced concrete silo of the bucket and to add a vibrator for the future. The vibrating bucket brings convenience.
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