Hi rajendra,

A rotary valve is a fixed volume device. If you have a 200 X 200 mm flange size then it depends on the diameter of the rotary valve, and the rotation speed. Given the bulk density of your fly ash it is possible to calculate tonnage rate.

Talk on the phone to your Rotary Valve Manufacturer for more details. They will be happy to help.

Regards - John.Rz

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Hi rajendra,

As I understand it you have a bin or silo. Under the silo you have a 200 X 200 mm discharge opening controlled by an air-operated slide valve, or pivoted curved slide. You want to know the maximum discharge rate with fly ash with a bulk density of 0.6 t/m3.

There are two discharge rates from a silo or bin, depending on how the product behaves in the bin.

1 - If the product flows from the bottom, then it is a product flow case [mass flow or similar]. The velocity will be equivalent to particles falling from a height of say 600 mm. You can do a laboratory test. Make a plastic sample bucket with a 50 mm discharge nozzle [we fitted it with a full bore ball valve]. Measure the discharge rate. The discharge rate will be roughly proportional to the area of the opening.

2 - If the product forms rat-holes, and flows from the top, then you have a dump flow case. The maximum discharge velocity will be equal to the height of fall. You can estimate it from the normal fluid mechanics formula

---- h = V^2 / (2g)

We measured a dump rate of about 10 ton/sec through a 300 mm diameter outlet, at a bulk density of about 1.2 t/m3.

That would make it about 8.3 m3/sec through 0.07 m2. Through 0.04 m2 that would be about 4.8 m3/s or 2.9 ton/s.

Regards - John.Rz

http://www.cospire.com / Engineering Tips ■

Dear rajendra,

I suppose hat you are referring to a flow control gate with a V notched opening.

When operated by a servo motor or pneumatic cylinder, this opening increase in size in a

non proportionally way, resulting in a more or less proportional dosing function.

As the the flyash is fed to an airslide, the flyash is fluidized already in the silo and the outflow through the regulating gate is also in fluidized mode.

The outflow capacity is then dependent of the rate of fluidization inside the silo (fluidization cloths) and the fluidisation pressure inside the silo. (Pneumatic conveying formulas can be of help here)

see the link

http://www.ibauhamburg.de/components...olgate01.htm

success ■