World Grain - August 2007 - 65

TECHNICAL PROFILE: ENERGY MANAGEMENT IN FLOUR MILLS

rent situation. For this purpose, a plant
will ideally be divided into plant sections or sub-processes that are detailed
as accurately as possible. The energy
requirements of these sub-processes
can then be accurately determined by
integral power measurements. This will
provide an overview as a function of
time over the energy used by the individual sub-processes at any given point
in time.
By dividing the contract with the energy utility into different time frames,
it may be possible to move energy-intensive processes to periods with lower
rates. In flour mills this will only be possible for a small number of sub-processes. These include grinding of the byproducts from grain cleaning, bran pelleting,
raw wheat transfer from the storage bins
to the blending bins, etc. Another possibility is to analyze plant sections that
operate simultaneously. As power rates
often depend on peak power consump-

tion, this may allow fine-tuning of power
usage.
Power measurements are also a suitable instrument for pinpointing process
operations with high power consumption. This means that any investments
made should focus on sections where
a fast return on the investment is
ensured.
POWER DISTRIBUTION/
INFRASTRUCTURE
Whenever possible, transformers
should be installed as near as possible to
the equipment that uses the power. The
longer the cable routes, the higher the
power losses. This is especially important today, since the current high copper
prices will generate high costs if cable
cross-sections are oversized.
Another important factor is the selection of the electric motors. In the recent
past, most manufacturers of induction
(asynchronous) motors have substan-

rationel kornservice

1PFEUFFER
und Pru fqer äLc

Sample Cleaner

SLN 3 & SLN 4
for cleaning and grading by size as means of
selecting grain for seed, malting, feed etc.
results in accordance
with process cleaning
machine (3 or 4 sieves)
aspiration and deawner
for all types of grains
(oil seeds, cereals, corn,
grain legumes, seeds etc.)
self cleaning sorting sieve
by ball cleaning system
sieve changes can be
made easily in seconds
maintenance free, vibration
free & low noise operation
www.pfeuffer.com
Pfeuffer GmbH
Flugplatzstr. 70
D-97318 Kitzingen
I.

Tel. +49 93 21 93 69-0
Fax +49 93 21 93 69-50
info@pfeuffer.com

Heat recovery systems
Direct heat
(air/air heat exchange)

exh

aus

t ai

fres

ir
fres

er
ang

exh

t ex

hea

aus

t ai

Heat shifting circuit
(liquid/air heat exchange)
exh

aus

t ai

fres

nge

cha

ex
eat

exp

ans
ion
tan
circ
k
u
for latin
s
g
h
circ ifti pu
uit ng mp

tially improved the efficiency of their
products. As a rule of thumb, the cost
value of new motors should never be
below 0.9.
The quality of the motors as well as
their starting characteristics must be
considered in the context of energy consumption reduction. Depending on the
service hours, specific functions and
power consumption of drive motors, their
circuitry may have an appreciable impact
on power usage. It is therefore important
in each application to determine whether
it is worth the cost to buy a somewhat
higher-priced system in order to conserve
energy over a certain amount of time.
The reliability of frequency converters has improved in recent years while
their prices have dropped. Therefore, it
also may be worth contemplating their
use in applications where their cost was
considered too high until recently. Besides optimizing the starting characteristics of motors, frequency converters
also improve motor efficiency by almost
1.0 because they prevent phase shifts in
the motor windings. Improved power ef-

For more information, see Page 74.

August 2007 / World Grain / www.World-Grain.com

http://www.pfeuffer.com http://www.World-Grain.com

World Grain - August 2007

Table of Contents for the Digital Edition of World Grain - August 2007