Cement Silo Dust Collector Purpose & Diagram

Noooo, you DON'T want to remove air from the stored cement. That would cause 'vacuum compaction' ... the cement particles would bond to each other to form a solid mass rather than one of made loose, free-flowing particles.

Vacuum compaction is why the surface of the Moon is hard enough to stand on despite the fact that much of the surface is covered deep with dust. Astronauts that walked on it left tracks, but they (and the lunar landers) didn't sink into it ... which had people at NASA worried until the first Moon mission proved that Moon-dust surfaces were hard enough to walk on.

Cheers! DZ

Dust Collectors or Bag Houses remove the excess air from the silo. Ours typically operate at 3-7 inches of water less than atmospheric pressure. No where near enough to de-aerate the powder.

the air pulses are to keep the filter bags clean &

The bag house is to equalize the pressure, when filling emptying or moving cement in the silo's

thx for the replies

IBGrizzly, the cement silo im having is using screw conveyor at bottom of silo outlet to transfer the cement to a cement weigher...our product is fibre cement board. i think most of u would assume it's a cement or concrete plant...

the cement is pumped into the silo from the cement truck. i think this is done pneumatically so there will be air + cement entering the silo. in other words, dust collector remove excess air to avoid pressure build up in silo which will obstruct any incoming or outgoing process.

i understand that silo inside has to be dry. does reducing air helps significantly? since less air = less atmospheric water.

or is there other system involve to dehumidify the silo?

My comment got stuck, since we had a power outage last night

There is probably a dissicant or other dryer to keep the air inside the silo dry.

the pulse jets for cleaning off the bags, run on compressed air, which probably has a dryer.

the transportation blowers probably don't have dryers, the volumes of air being too large

there may also be air cannons [compressed air] mounted on the cone at the bottom of the silo, to prevent bridging

I don't think you can use vibrators for concrete....

We have 5 silo/bag house in use to handle similar hygroscopic material. We do not use desiccants/dryers in any of the silos. The air used for conveying is either plant air (which does have a dryer unit inline) or the air compressor installed on the delivery trucks (no dryer).

The materials we are dealing with are all fine powders. The materials and associated discharge devices are Lime (CaO)/weigh belt conveyor, Limestone (CaCO3)/screw auger, CKD (cement kiln dust)/screw auger and Zinc Calcine (ZnO)/drag chain, rotary valve and screw conveyor.

The choice to pneumatically move the cement from the truck to the silo was probably done for economic reasons. Most transport trucks used for this type of material are built with sloped bottoms and easily pressurized. The equipment needed to off-load the material is simply a suitable hose and a source of air pressure. Other methods require the recipient to have some sort of conveyor belt, hopper system or screw auger to move the material from the truck to bulk storage.

You are correct that the Bag House separates the air from the cement dust.

As for moisture infiltration, the lower the pressure inside the silo relative to the outside the more moisture is drawn into the silo. The reason this is not an issue is that the hydration of the dust from humidity in the air is relatively slow and if your silo turnover is similar to ours, the majority of the material is turned over in less than a week and the constant movement of the stored material as part of it is withdrawn from the bottom of the silo prevents is from solidifying.

We had one silo, (2,000 MT), with ~ 250 MT of ZnO in it that we did not pull from for about 18 months. The material set up and would not flow out the bottom. We eventually had to go in with Jack-Hammers and dynamite to remove it.

my experience is with storing & moving corn & wheat flour

the wheat flour is especially susceptible to moisture.

since the flour was also transported around the plant pneumatically, with all the air routed through the silos, a rotating desiccant drum that heated the nonactive section to remove the moisture