the need for special sealing pockets dust
Without touching until the volume removed by aspiration of air, we note the need for special sealing pockets in the dust of toxic dust. Closed vehicles - elevators, bacon, etc. - should have a maximum sealed casings, tightly connected to the chutes.
Pouring of any pipelines, if any, must necessarily be provided with shelter from the side chambers of type SIOT. In the places of the material from the crusher, in addition to installing shelters SIOT recommended further kapsyulirovat heat, cover and part of the conveyor through the creation of the chamber under the crusher, from which an additional air suction is performed. Such secondary kapsyulyatsiya shown in Fig. 9.
Transport of dusty materials with toxic dusts is best done by pneumatic.
Ducts aspiration systems that remove toxic dust should be laid vertically or with a maximum slope, velocity in ducts made possible the greatest. What is less need to clean the air ducts (for toxic dusts it difficult operation), the better.
Of toxic dusts in all possible cases should be applied hydro - dedusting in parallel with the aspiration.
For dust control devices having solid covers without openings (mixers, elevators, augers n, etc.), it is necessary to create in them a considerable vacuum. Only in this case will be achieved not knocking the dust through the cracks, which is especially important when toxic dusts.
Taking the rate of air through the drain is not the density of housing, 4 m / sec for a relatively innocuous dusts and up to 8 m / s for toxic dusts and estimating the coefficient of local resistance compacted gap value s = 3, we obtain the necessary vacuum in the enclosure in the range from 3 to 12 kg/m2.
In the calculation of aspiration systems should consider the vacuum aspiriruemoy equipment in an amount not less than 5 kg/m2 for normal dust and October 15 kg/m2 - for toxic dusts.
Air speed in duct aspiration and suction plants is usually prescribed in accordance with the SI 7-57. However, the practice of recent years has shown that these speeds are too low. Calculated from these data suction system clogged with dust deposited in them. Recommended in the design aspiration to take the air velocity, given in the Table. 17.
The question of what material to perform suction ducts, to date, is controversial. In most cases, these ducts are made of circular cross section of sheet steel. However, there are no contraindications to their implementation of plastics, such as vinyl plastic.
The most rational suction ducts are made of steel with thickness 0.7 mm for diameters up to 200 mm and 1 mm in diameter is over. Only a very abrasive dust to do the knee of the thicker steel 1,5 - 2 mm. Considered unnecessary to install any shut-off and regulating bodies for aspirating air ducts, since they only stimulate the formation of gaps. On the other hand, it must install on the aspiration duct hatches for cleaning.