Fine Coal Bin Problem
Greetings from the "Easten Wilderness"
It definetely sounds like your coal is rat holeing and bridging over which will creates voids in a stock pile or bin-that is how I lost a close friend 23 years ago.
Your problem is typical and to be expected with regard to coal storage or any bulk product for that matter.
There a many solutions and potential problems with the solution.
The use of air cannons is one solution.
The use of inflatable bags/mass movers mounted permanently to the walls of the vertical bin wall to force coal movement is another.
Changing the method of delivery by utizing an apron feeder with a wider opening in the original bin resulting in a larger more regulated flow of material- regulated by gates and speed of the apron feeder.
Cleaning the bin to eliminate any build up on a regular basis.
Lining the the bin walls with a slippery liner to allow unimpeded movement of material.
changing the bin by installing a bin with a larger bin of rectangular size and a 60 or 70 degree tapered bottom to allow for faster flow.
and The decision to do nothing also is available.
I am sure that Lynn,George or Gary will cover what I have missed.
lzaharis ■
Coal Bridging In Bin
Dear Mr. Ghia,
The problem sounds like bridging and ratholing of product. Are the coal fines wet?
The quick fix is an air cannon or additonal vibrators mounted on the side wall of the bin.
tying them in with a bindicator would allow them to work independently of human operation.
The best way to solve it would be to install air pillows/mass movers on the interior wall of the bin directly oposite ech other to force material out in to the center of the bin.
Installing a slippery liner in the bin is also an option.
If you could post a picture of the bin on the forum that would be good as I am unsure of the bin dimensions.
the other members of the board will probably cover something I missed.
lzaharis ■
Fine Coal Bin
Dear Mr Ghia
have you tried ss liner on bottom cone of silo. This will reduce friction and improve flowablity of hopper.
A R SINGH ■
Fine Coal Bin
Dear Mr Ghia
have you tried ss liner on bottom cone of silo. This will reduce friction and improve flowablity of hopper.
A R SINGH ■
Fine Coal Bin
Dear Mr Ghia
have you tried ss liner on bottom cone of silo. This will reduce friction and improve flowablity of hopper.
A R SINGH ■
Irregular Flow
The description of the bin geometry does not appear to be complete and I cannot square the concept of two, 345mm diameter screws extracting from a 2 M diameter conical outlet. The reference to twin agitators and fluidizing arrangement in an insultated bin also seems quite an elaborate set up. If you would care to send a drawing of the hopper and discharge equipment to lyn@ajax.co.uk with details of the air injection, I would be pleased to review the situation. In general, flow stimulation devices such as air cannons, vibrators, fluidizing pads, agitators, sledge hammers and the like are no substitute for good, gravity flow design for securing steady, reliable flow of bulk material in a consistant, suitable condition of density and flow state.
Superficially, the problem of 'irregular flow' sounds to be more like 'slurping' than 'ratholing', but a more details explanation of the type of flow irregularities should clarify the matter.
I would comment that Ajax has rectified many flow situations, and has just recently successfully modified a 40,000 Te capacity hopper system for fine coal that suffered serious ratholing problems. It now provides reliable flow. ■
Fine Coal Bin
Dear all distinguished members of this forum
We are facing problem of irregular flow during extraction of fine coal ( appx. 15 % R on 90 micron) from the fine coal bin. The phenomena is more pronounced at extraction rate more than 18 TPH. The bin,4 M dia. X 6 M HOS is thermally insulated & has a capacity of 100 M3. The bottom conical outlet dia is 2 M, having wall inclination of 70 deg with the horizontal.
Two agitators are provided at the bottom of the cone along with fluidizing arrangement. The coal is extracted from the bin bottom through variable speed twin screw conveyors of 345 mm dia each, having increasing pitch along the travel direction.
It is suspected that the problem of irregular flow is due to dynamic arching inside the bin. You are requested to suggest solution to above problem. ■