You haven't given the feed rate into the bin.

However it may be worth considering feeding the lime into a receiver at one end of the bin which discharges into a mechanical conveyor like an en-masse chain conveyor or screw conveyor having an “open bottom”. The lime discharged would then fill the bin to the underside of the conveyor and so form a false bottom. Further material would then be progressively conveyed along the length of the bin so maximising the filling. (The method sometimes referred to as "spill and fill")

This is a well known method of filling long bins or open piles. ■

[QUOTE]Originally posted by vlad1979

[B]Hi everybody,

I will get right to the point. Due to limited space we will have to design a rectangular shape silo. It will be like 10 meters long x 2.5 meters wide x 7 meters high. The capacity will be like 170 cubic meters. This will vary depending on the lime will put in.

The lime will be coming thru a pipe on the top with compressed air, and on the bottom of the silo will be a screw conveyor that will collect the lime.

Our main problem right now is to find a solution on how to fill the silo as much as posible and evenly, not having those mountain shapes inside, like the picture suggest (please see the attached picture). Are there some solutions to this problem? We were thinking on having the main pipe then thru a series of diverter gates to have 2-3 pipes in different positions on the silo to fill it. The problem is these diverter gates cost quite much so will want to avoid them as much as possible. Or having some sort of vibrators...

Anyone has some insight on these rectangular silo?

Any other suggestions or comments on the design so far are welcomed.

Another option is to purchase a material thrower/ship trimmer commonly used to fill ship holds and railroad box cars with a material, the material is conveyed however and it reaches the end point and drops onto the spinner and it thrown wherever to fill the space

Everything would be thrown against all four walls and it would fill completely as the material would sink to the bottom of the inverted cone of sorts and the silo would be filled evenly.

The folks that sell them advertise here on the web site so they are easy to find.

Oh and by the way you will always have mountains of product-any product for that matter until drawdown of the material is started with a system such as yours. ■

Designers solution is the best you'll get. If you can take it out with a screw then you can put it in with a screw.

The surcharge ridge will remain ( your mountain bit) because that is the way particulates fall into place.

With 7m head of lime you might have an arching/consolidation problem with the take out screw depending on the residence period. ■

"..a material thrower/ship trimmer commonly used to fill ship holds and railroad box cars with a material, the material is conveyed however and it reaches the end point and drops onto the spinner ..."

I always thought ship trimmers were like this ??

http://www.metsominerals.com/inetMin...25-2256F-6FB29

I've used spinning discs to maximise the fill of a bin (inspired by road gritting lorries), but don't think I'd recommend it's use on a bin with a plan aspect ratio of 4:1 as it will fill widthwise long before filling lengthwise. Also how well would the lime be thrown?

Maybe you could blow the lime in at the end of the bin. This used to be standard with small rectangular flour bins, but would it blow 10m? ■

Most grades of lime are easily fluidisable and when discharged in it is aerated state and the angle of repose is very low (almost flat). I have seen a number of rectangle squat silos with side inlets for lime in water industry which work fine and also bulk tanker filling is the best example for you situation.

I would suggest that you do an angle of repose test on the lime and do the sums from their. In Lime silos, angle of repose is not a problem air retention is. Level of lime falls substantially with in 5 -15 min due to deaeration. Again this can be measured by measuring the aerated, poured and tamped density of lime.

If you are really unlucky and still get a mountain then the alternative is to aeration pads, they work wonders on lime as long as it is good quality dry air but then you will loose capacity on gravometric bases. !!!Catch 22!!! ■

Dear Vlad,

In your drawing, I do not see a filter assembly, to clean the convey air before exhausting to the atmosphere.

A possible solution to replace the diverter valve , could be a pipe with openings at the bottom side with a small vertical pipe down at each opening.

As soon as an opening gets blocked, another opening takes over, until all openings are blocked.

Level testers must prevent over filling.

I have seen a cement installation, using this principle in a flat storage system.

I do not know whether this system was working for the intended accuracy, but it never created problems.

The cement was always found back

The actual lay out of your system should be very carefully designed.

No guarantee.

success ■

My first point is that to secure the volume given at the dimensions stated requires that the container is virtually rectangular, so it would be ineresting to see how the screw will extract from a flat bottom. and the container be filled into all the top corners. Secondly, a discharge screw 10 metres long is not good practice. Apart from deflection, intermediate bearing in flooded conditions is inviting problems, the live extraction characterists will be limited to a short section leaving most of the contents static and subject to prolonged residence if the 'hopper' is refilled before empty.

Bringing in a pneumatic delivery pipe at the top of one en and extending it into the container some distance past and extracting filter, may allow the filling to blow across most of the length but I feel the constraints are too severe for the unit to be a practical proposition. Don't go back to the drawing board, go back to question the design criteria. ■

It would be quite practical to use a chain conveyor to extract from this 10m long bin. There are many working examples. ■

This does appear to be a catch 22 situation. I tend to go with Mattoo's comments although other comments can also be valid depending upon the lime's charictoristics.

I would throw a word of caution on both screw and chain conveyors in this instance. If the Lime is Fluidised then there is a good chance that it will flow past the screw/chain flights and empty the hopper on the first fill. This will stop when the lime has de-areated. ■

Certainly there have been many flour bins pneumatically fed where no such problem have been encountered. ■

Quite true.... However I look at Vlad 1979's reference to limited space which would also suggest a short distance to the conveyor discharge. This coupled with potential uneven emptying of this unusual shaped hopper and subsequent loss of head does make it vunerable to such a case. Especially if the lime is hot for any reason.

The case should therefore be considered any problem engineered out. ■