# Thread: Weight of Conical Bottom Silo

1. ## Weight of Conical Bottom Silo

I want to know how we calculate the weight of Conical Bottom Silo.

Material Stored - Fly Ash
Opening Dia - 4.5 m
Straight Portion Height - 5 m
Conical Portion Vertical Height - 4 m
Thickness for Straight Portion - 8mm Thk MS
Thickness for Inclined Portion - 10 mm Thk MS
Conical Bottom Dia - 0.45 m

2. Hello,

The silo will have vertical cylindrical portion, and frustum of cone as a lower portion. Find the surface area of both these portions. Then calculate the weight of the plate according to plate thickness. Add for the stiffeners and supporting frame. Decision about these features (plate thickness, stiffeners sizes, supporting frame) is structural design issue.

Surface area vertical = (Pi) x (Diameter) x (Vertical height)

Surface conical area of frustum of cone = (Pi) x (R1 + R2) x L,
where R1 is outlet radius, R2 is upper end radius, and L is sloping portion length.

Cross check with the available mathematical book, and then use the above information.

Ishwar G. Mulani
Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.
Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India. Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com

3. ## Not Bin There Yet.

If you have to ask about bin geometry I suggest you postpone this bin design until you begin to understand the principles involved.
Is the surcharge within the bin?
Will the shell withstand the transition pressure? If the surcharge is within the bin the required thickness not going to be the same as the thickness required to withstand the pressure at the transition where you will probably need ring reinforcement. Without a lid, which should answer the surcharge containment issue, you will need a wind girder. Ash will abrade the platework and the severity is related to the discharge method and the life expectancy of the bin.
You need to do some homework before you order and roll any shell plates.
What is the plate material?

4. ## Hopper design

A section on the web site www.ajax.co.uk will calculate the weights and capacities of conical hoppers. The hopper design chart will also advise a design procedure. The sizes described indicate a wall inclination of about 60 degrees to the horizontal; a common choice that is neither one thing or the other for a reliable flow regime. Hopefully, the design is in the hands of one experienced in the handling of fly ash.

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