Digital Re-print - May | June 2010
Feature title: Flour mill design
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Flour mill design Feature Feature Flour mill design
holes in the floors, in the right places to Other items, such as offices, maintenance Traffic flow and layout
accommodate spouting and pneumatics workshops, staff welfare facilities and labora- Several sites I have worked on over the
and other pieces of plant that require tories will need to be allowed for and apart years have adopted traffic flow as the main
access through the floors. It is easier to from them being near to the mill there is criteria for their premises layout. With one
accommodate changes in steel buildings nothing to be gained by having them in any incoming weighbridge and one outgoing
than in concrete but it is also easier to particular places, suffice to say that the wheat weighbridge, a circular route for vehicles
inadvertently weaken the building structure laboratory may well be close to the intake around the perimeter of the site often
by making too many structural changes in point and the flour laboratory close to the proves to be an economical layout with
a steel building after the building has been packers. minimum supervision of vehicles. Cameras
erected. I am obviously referring to a mill where and traffic notice boards serve to control
A simple layout of a milling facility would bagged flour is the prime product but I real- traffic very well and also provide a good
be to have the intake and wheat silos at ize that there are more and more mills being record of vehicle turn round time and
one end, close to the water and the supply built with bulk facilities and several are also precise data as to when vehicles arrived
vessels followed by the main mill building being built in certain developing countries and departed.
housing the wheat cleaning plant and then with plant bakeries very close by, if they are The mill building itself is usually designed
the mill. not built as an integral part of the whole by the milling engineers and is then checked
Flour and bran will normally be blown facility. over by local structural engineers who may
Flour mill design
into finished product silos at the opposite Certainly this is the case within pasta or may not be retained until the building is
end of the mill building to the wheat silos plants and semolina mills invariably being complete and machinery is installed. Use of
and these will, likely as not feed through built side by side to obtain the greatest contract managers is invaluable if you have
packing machines into the main storage economies overall. nobody on staff who has carried out major
warehouses. All this arrangement will ideally Economies on maintenance, quality con- works before, either civil or mechanical.
by Jonathan Bradshaw be in a straight line to avoid using unneces- trol, staff welfare and general administration
sary power transferring products from one can all be maximized by incorporating as Attention to detail
There can hardly be a more graphic illustration of a mill not being built to match the likely point to another when gravity can do the job many operations as is feasible and practical Electrical controls are usually supplied by
circumstances of an earthquake than the recent events in Haiti where the mill building was reduced far cheaper. on the one site. milling engineers as well but transformers,
to a pile of rubble in literally seconds. I don’t blame anyone for this since the building was originally
built several years ago and those who designed and built it adopted best practice at the time.
Silo Construction & Engineering
T
Grain cooling
he fact that this earthquake ficient depth of water to accommodate our As an aside it is often common practice
GRANIFRIGOR™
was stronger than anything chosen size of vessel. It may be that dredging in concrete buildings to erect the wheat and
felt in the region for some is an economical answer or possible using flour silos from Concrete as well although
time just goes to demonstrate that dolphins far enough from the shore line there is no reason why steel silos cannot be
The most natural way of grain preservation: Modular square bins
there will always be situations that where the water is deeper. used for wheat.
we cannot have foreseen. Students of the old correspondence • Protection against insects and microbes
Concrete or steel? course will know, however, of the advan- more profits
• Without chemical treatment
Having said this there are many other When it comes to the mill building tage and disadvantages of using steel through
• Short amortisation period
factors to take into account when designing itself then we really have just two options, silos for flour in comparison to concrete. smart storage
mill buildings. concrete or steel. Concrete is invariably Temperature changes for one thing are not • Low energy costs
First, we must consider what materials we the favoured option since raw materials transferred as quickly into the finished flour • Independent of ambient weather conditions
shall use to construct the building with. What are almost always available locally and with when concrete is used as compared to steel www.sce.be
are our criteria, how fast do we want to be reasonable supervision local labour can be which allows such temperature change to
in operation, what are the ground conditions, used to build such a mill building. be almost instantly reflected in product
what are the local laws? However, there may well be circum- temperature.
For example, imagine we want to build stances where steel has distinct advantage, Obviously, whatever the circumstances
a mill as a new entrant into the industry in particularly when the site is of poor struc- and whichever is used then adequate ventila-
somewhere like West Africa. ture. Steel is lighter than concrete and can tion is a must. Similarly, mill buildings made of
As a new entrant we obviously need to be fabricated and erected much quicker. steel require adequate ventilation, not only
have dock side facilities for offloading wheat Overall build time to full commissioning to keep the employees and operatives cool
and if we cannot acquire sufficient land with- can be reduced significantly by using a steel – and hopefully productive - but also so the
in a port we may wish to consider a separate building, and it is easy to modify to accom- process is not adversely affected by swings in
SCE
facility for wheat intake and storage and then modate changes as it is being fabricated temperature and humidity.
take into account the need to transfer wheat and erected. SCE is a partner with
to the mill at a later date when the vessel Frequently, piles are used to strengthen Forward planning the international
Tel. +32- 51-72 31 28
has left port. the foundation of a building where it is weak Once the building is erected and the Fr i g o r Te c G m b H • H u m m e l a u 1 • 8 8 2 7 9 A m t ze l l / G e r m a n y Fax +32- 51-72 53 50 feed & food industries •
E-mail info@sce.be consultancy & engineering firms •
We also need to take a good hard look and piling often pays for itself in the long run installation of machinery is commenced it Tel.: +49 7520/91482-0 • Fax: +49 7520/91482-22 • E-Mail: info@frigortec.de machine & plant designers •
at the available draft within the port and because the building steelwork can also be is to be hoped that forward planning has www.frigortec.com
approaches to it to make sure there is suf- reduced in profile. been satisfactory and there are sufficient
12 | may - June 2010 Grain &feed millinG technoloGy Grain &feed millinG technoloGy PREVIOUS PAGE NEXT PAGE may - June 2010 | 13
Flour mill design Feature
very few remote places in North America And finally may I say that there are two
there are strict guideline on emissions and ways to design a mill, or a site, the first being
constant monitoring is now the norm with to obtain a good layout from a practical
equipment being calibrated annually with the point of view and the second one being to
local authority being present at the time. start with the customers specification for
Noise levels are also closely monitored flour and then work backwards through the
and it may prove beneficial to house certain flow sheet requirements and then building
items of plant which generate high noise criteria to house such a mill.
levels separately. This is certainly becom- I generally favour the latter but the
ing the norm and most blower rooms are former can often work well particularly when
positioned on the side of the mill furthest local bakers and traders are the customers
away from housing and almost always these and the mill is producing general all purpose
blower rooms are well insulated. bakers’ flour as its main product.
It is easier and more economical to house In both cases however the plant must
such items separately when they are to be be laid out with plenty of access room to
insulated since this greatly reduces the quantity individual machines because if operatives
of expensive acoustic insulation that is required. cannot work on a piece of equipment easily
without getting knuckles cracked and knees
Maintaining water volumes and rapped they simply will leave it alone, with all
quality the knock on effects that has on flour quality.
generators, field wiring within the mill and All mills require water for damping of wheat Getting involved from day one of con-
laying of high tension cables may be subcon- and whilst we do not have the problems ceiving of the mill design and layout will
tracted with good efficiencies being achieved. nowadays of disposing of the contaminated proves extremely beneficial and as I always
Invariably whoever carries out the electri- water from washers and whizzers we do still advocate regular walk rounds of the mill that
cal installation is the person who will subse- have the problems of maintaining water quality is in operation I can strongly advocate twice
quently maintain the plant and to be in at “the and holding sufficient water in storage to pro- daily tours of the site whilst under construc-
ground floor” will help in their understanding vide adequate pressure for operations. tion. If work is being done to the upper
of the electrical wiring and the protocols Invariably we see the water tanks being floors and for one reason or another your
which have been adopted. Most new mills are placed on the top floor of the mill close to presence is not welcomed then take a pair
highly sophisticated in their electrical controls tempering devices and with separate feeds of binoculars with you and take a good look
and so attention to detail is important. down through the mill to provide adequate from ground level.
With auto roll gap adjustments, extrac- pressure and supply to offices, laboratories, Always hold regular site meetings to
tion monitoring and power recording as the canteens, workshops, toilets and showers. monitor progress and deal with other design
norm, along with possibly on line testing of Sprinkler systems usually have their own issues that may crop up periodically. Always
flour and automatic adjustment of additive supply of water which only need topping up make sure contractors know where they
feeders and wheat blends it requires people whenever sprinkler tests are carried out. stand on an issue, be clear with you instruc-
with advanced knowledge and skill to design, In some instances it is however illegal to tions and listen to the counsel of those wiser
install and maintain the electrical control store water because it is such a scarce com- and more experienced than you are. You will
system in the mills of today. modity. In such circumstances it is usual to sink find that the ‘Old Hands’ take great pride in
Fortunately most engineers have access a bore hole to provide an adequate supply their work and will help you along well so
to electrical contractors with the necessary of potable water although I have seen some long as you look after them in return.
capabilities and some even have a separate rather shallow bore holes which left a lot to
facility with suitably skilled staff within their be desired in terms of water quality, often
own umbrella organization. only rectified by sinking the bore deeper.
Having said this there are some countries Related Companies:
where the client wants the simplest mill he Security Ottevanger Milling Engineers BV
can obtain with no degree of automation Security is another consideration, par- PO Box 3, NL-2750 AA Moerkapelle
whatsoever. In my opinion there is little ticularly where there is a history of forced The Netherlands
sense in taking this approach since even in entry into premises in the area or where Tel: +31 79 5932221
Fax: +31 79 5931147
places where all the operatives are illiterate fraudulent practices are deemed acceptable.
Email: mkp@ottevanger.com
it still pays to carry out tasks automatically Depending on the country arrangements Website: www.ottevanger.com
rather then rely on individuals to remember for security may range from a van com-
when various tasks are to be carried out. ing by the mill premises a few times each TSC BV
night through to armed patrols being on Tweede Broekdijk 7
Noise pollution and dust site at all times with locked gates, machine 7122 LB , Aalten Netherlands
emissions gun platforms and observation points being Tel: +31 543 473979
Some other items which we need to con- the norm. It very much depends upon the Fax: +31 543 474472
sider are noise pollution and dust emissions culture of the country as to what level of Email: info@tsc-silos.com
Website: www.tsc-silos.com
to the atmosphere. In most places except the security is required. The choice is yours.
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