You will need to understand the flow properties of your coal and how they interact with the geometry of the converging section of your silo that feeds into your gravimetric feeder. You should also understand the characteristics of your feeder and how material is extracted from the silo outlet. ■

You propose to change the 2.4m^2 slot opening to a 1m^2 square outlet. (It will be a truncated pyramid, not a cone frustrum)

That is a tall order!

Your material flow regime will go out of the window because the valley angles will be dramatically reduced. Your bin will be approaching flat bottomed proportions. If the opening width increases so much then shouldn't the receiving conveyor etc. grow in sympathy; regardless of any flow change, or not?

Without a serious explanation of the intent of the modification I would advise aghast it. ■

John appears to have got his dimensions mixed up but the comments are valid that to 'loose' 3 metres in outlet length is a big challange. In any case, the information available is not adequate to assess the situation, either in geometry or as an understanding of the options. The first step is to know the underlying reason for the change. Presumably there is a wish to secure measured discharge, but are there any other reasons that the present discharge arrangement is unreliably or unsatisfactory?

The application appear to need a thorough evaluation based on full details and dimensions of the existing equipment, operating history and current objectives. Much can be done to alter flow regimes by way of inserts and innovative technology but, as pointed out by designer, data is also needed on the flow proprerties of the coal and I would caution that special geometries is a topic for specialists. ■

Check out the General Kinematics Un-Coaler Activator/Feeder. It can be custom designed to your process.

http://www.generalkinematics.com/pro...r/uncoaler.cfm ■

Although the design of hoppers and outlets are very important, they seldom take into account other key factors such as variations in particle, climatic conditions etc. We havea lot of experience in ensuring that many types of material flow at maximum, even rates, irrespective of the design or condition of the hopper or it's outlet.

By installing the correct model of Acoustic Cleaner just above the hopper outlet and 'sounding' it for a few seconds at periodic intervals during coal discharge, then these sound waves will ;excite' the coal particles and prevent bridging over the outlet. In all cases this is a very effective and certainly much cheaper option than redesign of hopper outlet.

If you care to look at the following link you will find further details and photograph. - http://www.primasonics.com/hopperapplications.htm

Regards

Donald ■