Ash Hopper / Screw Feeder Displaced Air

Posted in: , on 15. Dec. 2013 - 16:26

Hi,

Hope someone can help me with this problem or give me some guidance. Im fairly new in the materials handling game but eager to learn.

I have a fully enclosed hopper with screw feeder fixed to the outlet. This hopper will be fed Ash (1200Kg/m3) up to a max rate of up to 40 tons per hour. This will not be a constant flow it will come in one slug or slugs of Ash i.e. 40 tons could come in a small period but overall the max will be 40 tons per hour.

The hopper which is a pyramid design has a volume of 75m3.

Ash Bulk Density = 1200kg/m3

Fill rate up to 40 Tons/Hour

My question is to with the displaced air.

What exhaust air flow rate is needed to get rid of the displaced air so an over pressurization is not caused.

We are going to put a spigot on the hopper from which to extract the displaced air. I just need to size this according in order to extract the correct amount of air.

Thanks Shaun

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Re: Ash Hopper / Screw Feeder Displaced Air

Erstellt am 16. Dec. 2013 - 01:27

Assuming hopper is fed by a pneumatic conveyor the Filter needs to be sized on the amount of conveying air coming into the hopper. The air displaced by material will be negligible as compared to the conveying air.

Mantoo

Re: Ash Hopper / Screw Feeder Displaced Air

Erstellt am 16. Dec. 2013 - 04:23
Quote Originally Posted by MantooView Post
Assuming hopper is fed by a pneumatic conveyor the Filter needs to be sized on the amount of conveying air coming into the hopper. The air displaced by material will be negligible as compared to the conveying air.

Itis not pneumatic its is a fully skirted and covered trough belt conveyor.

Re: Ash Hopper / Screw Feeder Displaced Air

Erstellt am 18. Dec. 2013 - 08:26

If it is ash on belt conveyor then we again has to assume it is wet.

Dry ash on belt conveyors is not a good solution in my opinion.

If it is wet then you can assume it is non dusty product and you

will not need a slight vacuum in the hopper to keep the dust inside.

The displaced volume of air will be equal to the volume of material into

silo which is 33.33 m3/hr based on density of 1200kg/m3. This vol of air

will easily decipate through the belt conveyor interface and it is very unlikely

that it will cause over pressurization. But if you are worried then you can put

a PRV / VRVon the hopper. They are cheap and cheerful.

If it is dry ash then you will need a fan assisted filter to keep the dust in. The fan

size will depend on the hopper volume. If putting a fan then you will require a PRV / VRV

as then you will have a real chance of vacuum build up.

Mantoo