Volume BSH 10:
Part 1 Survey of
Storage Options for Bulk Solids
This part discusses
the design of hoppers, bins, silos or bunkers for wet, granular
solids. Such material will generally be unsaturated, i.e.,
the material will be a three-phase mixture of granular solids,
water (or other liquid) and occluded air (or other gas).
Volume BSH 10: Part
2 Design Guide for Storage of Wet Bulk Solids in Hoppers, Silos,
Bins and Bunkers
This part is
a design guide intended to be used as a reference work for
the design of hoppers, silos, bins and bunkers for the storage
and discharge of wet bulk solids. The majority of the part
refers to the design of the discharging section of the storage
vessel, since it is this that is the key to proper function
of a vessel. In practice, this means principally the selection
of the hopper angle to obtain the correct flow pattern, and
the outlet to ensure that the material will not arch over
it. It also includes the correct selection of the wall material
for the converging section, together with selection and interfacing
of the feeder to draw material out of the bottom of the hopper.
The part concentrates
on practical considerations and the methods of design, and
how to avoid practical pitfalls, rather than fundamental analysis
and theory. However, some explanation of fundamental concepts
has been included to enable a practical engineer to obtain
an outline understanding of the reasons behind the steps laid
down. References are included for the use of those seeking
a more rigorous fundamental understanding. Case studies are
included to illustrate the design techniques described.
The part includes
"digests" of the approaches to be used when designing
and troubleshooting bins for wet materials. The reader is
particularly encouraged to use and refer to these when trying
to use the part, as they lay out a structured approach to
the processes of design and troubleshooting. Finally the part
incorporates a section describing the processes of "caking"
in wet materials and how this can be avoided.
The part has been written to be particularly relevant
to bulk solids which include sufficient liquid (of any type) to modify
significantly their flow characteristics from those of dry materials,
but are not so wet as to be better characterised by rheological techniques.
Essentially this means that compared with dry materials, they have significant
cohesive strengths, ie., they are not "free-flowing", and significant
time consolidation characteristics, ie., if left in a hopper they gain
strength markedly and become more difficult to discharge. Some dry materials
exhibit these characteristics, and the guidance in this work is equally
relevant to the design of hoppers for those materials. Note that materials
which have moisture contents well above the level at which draining begins,
should be treated as non-Newtonian liquids, using rheological techniques.
Such materials are beyond the scope of this part (see the Slurry
Handling Knowledge Base).
