Business: Industrial
Setting up an Energy Management Program
1.2.2 Preparing the audit
Timing of the audit
Foundry management must be consulted on this important consideration. You will
want the audit to reflect optimum operating conditions at or near production
capacity level. This is to ensure that the data collected over the audit period
will give you a true picture of the energy efficiency usage of the foundry
when it is operating at its peak. Lower production levels will result in wasting
energy.
A period of one to three weeks, when the foundry is operating smoothly,
should be selected. This should result in good averages of energy data
collected, ideally free of distortions caused by abnormal operating conditions
in various
foundry departments.
the energy audit with
the intent to determine energy inefficiencies in the foundry process as
well as energy losses in the “waste” streams.
Often, when longer data collection periods are chosen,
process abnormalities, interruptions, etc., are bound to happen, which would
result in proportionately
greater data distortions and higher specific energy consumption.
Determine
the production baseline
Among other things, you will want to use the audit results to establish
energy consumption levels based on average production. Normally, foundries
do not
have this information available. Such information would, however, facilitate
future energy management, including setting energy consumption targets,
quantifying eventual energy savings, budgeting, planning capital expenditures
and helping
to set true current costs per production unit, to cite a few examples.
over the highest production period. It is likely that the foundry will
not operate at this rate all year long but at some average level below
that. The average production rate divided by the maximum production capacity
will produce the nominal production efficiency, expressed in percent.
It is useful to relate the energy consumption to that basis.
Gathering
available information
Historical statistics, such as cost of fuels and electricity
(annually and monthly), purchase of raw materials, supplies (sand, binders,
shot,
refractories,
etc.), waste disposal data (volumes, tonnage, costs and revenue),
production data (good castings, scrap, rework, material losses) and labour
data
should be relatively easy to get in most foundry operations. The
material inventories
should be established before and at the close of the audit. You will
need this information when verifying or calculating the material
and energy
balances.
Getting the tools
It is agreed that the collected data should be accurate to the maximum
extent possible. The main meters on incoming natural gas lines,
electric power supplies
and water mains are usually maintained and calibrated by the respective
utilities and are expected to produce accurate readings. Likewise,
important measurements,
e.g., MCC (motor control centre) power meters or demand meters,
are usually accurate and can be accepted as such, at least initially.
Beyond that,
the accuracy of other foundry data is usually questionable and
not easy to assess.
Current experience shows that there are too few meters
used in other locations in the typical foundry in Canada. If there are
additional
monitoring and
measuring instruments available, the first thing to do is to
identify and check them.
This involves checking the calibration and maintenance logs,
how their specifications are matching the applications, the temperature
and pressure
compensations
and their proper installation. When there is insufficient time
to accomplish all
these things before the audit, the identified deficiencies should
be noted for action later on.
the existing information to identify and focus on the major end users of
energy.
It is also helpful to obtain the
facility layout diagram, process flowchart, and power, water and natural
gas distribution diagrams.
Other audit
tools that may be employed to prepare and analyse data range
from hand calculations
used
for simple cross-checks, spreadsheets used for data analysis,
to simulation programs. Software packages to evaluate the audit
data,
perform simulations
and find optimum solutions are on the market; to get them,
a utility and a number of other sources may be accessed.
Electric power consumed
by major equipment needs to be measured. A foundry may consider it useful
to purchase an energy analyser
for its
ongoing
energy program (complemented by a phase analyser, which is
necessary in order
to properly see the sine wave). This would require an investment
of about $4,500.
The analysers
can also be rented or borrowed from an electrical utility.
A consultant may have his or her own set.