Energy Conservation strategies
industry via Case studies
through
improved
maintenance
practices
in
Rajesh M Holmukbe
Asst. prof.in Electrical Engineeering,
College of Engineering,
Bharati Vidyapeeth University,
Pune-43,
Maharashtra.
Email: [email protected]
Abstract:
Energy Reduction Strategies through
Improved Maintenance practices is
composed of nine distinct areas in
which
ineffective
maintenance
practice
adversely
affect
energy
consumption. These areas address in
house maintenance
concerns that
result
in
excessive
energy
consumption. This paper describes
theory behind how and why the
proposed energy reduction strategy or
solution works.
This paper also
provides estimates of potential and
typical
electrical
energy
saving
available when improved maintenance
practices are used. A variety of case
studies are included. Handy tips for
energy
saving
which
can
be
implemented for little cost are also
discussed here.
httroduction:
Currently
industries
have
finally
recognized maintenance as an integral
part of the production process Friction
can be classified as the maintenance
department's
single
largest
enemy.
Friction causes heat which in turn causes
wear, which directly impacts energy
consumption
levels. The more that
friction is present in a piece of
machinery,
the greater the energy
requirement to operate the machine.
Understanding
the
direct
relationship between maintenance and
energy effectiveness is essential when
establishing energy reduction initiatives.
The following sections provide the
insight into how effective maintenance
practices can conserve energy.
Maintenance Practices and Energy
Consumption
The majority of equipment consumes a
basic level of energy, regardless of its
outputs; this means that
specific consumption is a function of
load. High efficiency
is achieved
through three key elements:
1) good energy efficient design
2) effective maintenance, and
3) good load factor (i.e., optimum use of
machinery
in energy
management
terms).
Machinery that consumes energy
independent of load condition (e.g. when
idling) requires the production planning
department
to address
idle time
reduction either through streamlined
planning or automated controls. Studies
performed by the Researchers.cencluded
that over 30% of total energy consumed
by machine tools in a single shift was
due to idling operation break times and
non-productive times.
Mechanical and electrical equipment
require sustained energy in order to
produce
work. Following
equation
shows a simple calculation that relates to
all moving equipment.
EI
Energy In
=
wo
WorkOut
+
EL
Energy Losses
Reduction of energy losses
dictates the validity and importance of
the maintenance function.
There are many areas which
affect the industrial energy bill. By
focusing on conserving energy in these
key areas, maintenance is able focusing
on conserving energy in these key areas.
Maintenance is able to influence a
positive change on the industry electrical
energy consumption bill. The following
nine areas have specifically chosen
because of their daily link to the
maintenance function:
I. Lubrication
2. Compressed air systems
3. Electrical Connectivity
4. Mechanical drive system
5.
astebeat and cooling reco ery
6. Housekeeping
7. P.M. Practices
8. Lighting
9. Steam systems
1. Lubrication:
Effective lubrication uses the correct
lubricant delivered at the correct time to
effectively reduce energy consumption.
Successful lubrication can save up to
20010of energy.
Case Study:
ASOO-Ton straight side punch press
employs an automatic recirculative oil
lubrication delivery system delivering a
standard chemical wear EP 150 type oil
lubricant to both rotating and sliding
wear surface. Energy is provided by an
electrical variable speed drive and the
press is used in a continual stroking
operation. The company monitored the
press energy use for fixed period
The
standard
lubricant
is
replaced with a premium plastic
deforming type lubricant (mineral based)
ISO 150 and the press is restarted.
Stamping the same parts as in the first
energy test, the company once again
deteonined the press's energy usage 0 er
the same period of time.
The original average kW usage
prior to change is listed as 25.17kW; in
the post lube change out, the kW usage
drnmatically
drops
to
20.55kW,
representing a reduction in energy
consumption of 17.92%!
Strategies for energy saving:
I)Perform a lubrication effectiveness
review by a consultant
II) Replace grease nipples practically.
DI)Change out lubricants based on
actual usage patterns
IV)Investigate the use of premium
Lubricants for optimum cost
V)Perform an energy use analysis
2.Compressed air systems
Energy savings through maintenance
Functions:
As shown in table, significant
potential energy savings of over 25%
can
is
achieved
by
improving
maintenance practices for compressed
arr.
COMPRESSED
AIR SAVINGS
DUE TO THE MAINTENANCE
FUNCTION
Potential Savings
Chuk & Repair Action
9.JO/e
System air leaks
23%
System over pressure
02'/e
Filter- maintenance
4.SO/e
Correct lubrication
air
Reduced
5J)%
.
.
.
.Figwre:Typic:aIC..pressed
Air SaYl~
Attributed to the Maintenance Function
"
"
"
""
Case Study:
A
metal
stamping/fabricating
company operates a plant with a
compressed air capacity of 1033 hp,
using a system of five air
compressors. An energy efficiency
study of their plant indicates the
following energy losses in their
system:
• System leaks amounting to 34%
of total capacity.
• Air blower valves tied open
results
in
an
unnecessary
continuous loss of air from the
delivery system.
• Bent copper tubing used in place
of engineering nozzles for air
blow off stations.
• Compressor air intake situated
inside the building, instead of
outside. In a compressed air
system, the colder the Intake air,
the more efficient the system.
The company decided to only tackle
system air leaks: leak maintenance
reduced air leakage b 500/0 which
resulted in a 350 hp compressor
being shut off and used onl as a
standb
unit when maintenance
activities require a compressor to be
shut down.. This reduced
the
electrical load by an estimated 270
k
or approximatel
2.1 milion
kWh annuall.
This reduction of
energy consumption corresponds to
an annual savings.
Strategies for energy saving:
I) Perform a compressed air audit.
II) Perform air leak checks
DI) Where er practical, use electric
motors rather than air motors, electrical
control rather than pneumatic control,
electrical tools rather than air tools.
Compressed air devices use four times
the electricity of electrical devices.
IV) Limit the use of air blo off devices.
If the must be used, use an engineered
nozzle which will realize 40.90%
savings Use a timer device to control
blow off air.
3.Electrical
connectivity:
Performing
electrical
connectivity
testing is a large part of any electrical
maintenance management strategy.
A non-intrusive and effective
maintenance approach to checking for
loose connections involves the use of a
predictive maintenance
infrared (IR)
non-contact measurement device an infra
red
thermo
graphic
camera
or
thermometer
to scan all of the
connections so that only those that are
out of specification can be identified
ote : IR connectivity scanning is only
effective on live electrical connections: •
access to high voltage areas may not be
feasible.
Ana
Electrical Connections
Lil!btinl!.
Motors
Power Transmission
Transfo£lllClS
FIIJ:- •••••••••••.••••
••••••••••
Unbalanced Phases. loose
(ground
ooonections
fault), poor insulatioo,
fuses, ";0111
degenaaIed
brushes. broIreo or loose
S\\'ikh e.ear
Ballast ooend:ions.
brushes.
Overloading,
bearinz failures
Poor connecdoas, broIreo
insulators
Housine...Wmdinre;
~
••••••
s
for Reducing Electrical Consumption
Poor electrical connectivity results in
inefficient energy use. Inefficient use of
maintenance resources, and potential
safety hazards.
Case Study
A food processing industry performs an
IR thermo graphic electrical connectivi
study throughout its facility. On one 400
hp drive arrangement, a loose motor
connection was found (see Figure for a
similar fault) and clearly showed the left
hand connection as suspect. During the
investigation. It is determined that the
loose connection is responsible for a 0.1
Ohm resistance to ground.
Calculation of losses:
Hot Spot = 0.1 ohm resistance to
ground
• Motor = 400 hp, 480v, SOOamp
• (amp/hp for 480v-3ph=1.2S)
• Power Cost =RsO.OS.S/kW
• Power lost to ground
_
2·
- amperage x resistance
=(500ampixo.lOhm
=25kW
Cost of Power
• =hours of operation x number of
days operating x power consumed x
costperkW
• =24hr x 260 da s x 25kW x RsO.05.5
• =Rs9,630 per annum
•
B re-tightening the loose connection, a
potential fire hazard was averted and the
company
saved
over Rs9,OOO m
unnecessary annual energy costs.
If this type -of situation is allowed to
deteriorate further, arcing at the contact
could eventually lead to an electrical fire
which could have resulted in the loss of
vital
production
equipment
and
thousands of downtime and maintenance
dollars.
Strategies for energy saving:
I) Using infra red technology .
II) Check electrical insulation visually.
DI) Check for looseness or mechanical
wear on electrical contractors ..
IV) Check for even and full contact on
fuses and knife-gate contacts.
V) Check for rela chattering
VI) Check for unusual noises and smells.
4. Mechanical drive systems:
Laser
alignment
equipment
manufactures
claim
that
improved
alignment
of shaft-coupled
rotating
equipment
has been measured
to
produce electrical energy saving of up to
11% while increasing
Case Study-Alignment
A wheel manufacturing plant performed
laser alignment on a series of metal
spinning machines. Each metal spinning
machine required two alignments, one
between the spinning head to the
gearbox and the other between the
gearbox and a 200 hp d,c, motor. Each
alignment took an average of two hours
to perform,
Electrical metering is performed under
identical load conditions, both before
and after alignments take place. The
alignments resulted in energy reduction
savings ranging from 6-15% reduction
averging at 100/0energy savings.
100/0Savings=5.8kW
Strategies for energy saving:
I) Ensure belts are tensioned properly.
II)Investigate
automatic
tensioning
adjusters
S.Waste heat and cooling recovery:
Up to 94% of the
equivalent of total electrical input can be
recovered through an enclosed oilcooled sere
compressor arrangement
(see Figure ). Figure shows the Btu/hr
heating
potential
available
by
horsepower rating of an air-cooled sere
compressor.
Heat Recovery Source
Compn::ssor oil cooling
(oil cooler)
Compressed air cooling
(aftcn:ooler)
Drive motor beat
Dissipated beat
A total of 94% of
RXOverable
Potential Recovery
n%
13%
9%
2%
COIIIpICSSOI'"
beat is potmtiaUy
Strategies for energy saving:
J)Use an infra red detector to check for
correct operation and effectiveness of
heat exchanger devices.
II)U se infra red thermal imaging to
check for insulation and refractory
degradation.
6.House keeping:
Good
housekeeping
or
dirt/contamination
control is crucial
when the goal is to optimize the energy
cost reduction
Housekeeping
IS
a
key
component
of
any
maintenance
philosophy, e.g. Reliability Centered
Maintenance (RCM) or Total Productive
maintenance (TPM).
incn:ased
HeJUSiCkeepiog Savings
Good
Reduces:
Extended
Wear Contaminants
oompooeot
lib; extended lubricant
redua:d
Iifu"
energy
with
associated
losses
wear.
Higher- quality control.
Product Contamination
and
reduced
enagy
costs,
resources
associated with product
reworkioa.
Identification
of bidden
Component Failures
defects
En~Cooswnption
contact
Improved
sur1aces, beat n:duc:tion.
bigber efficiency cooling,
drops
reduced ~
througb filtration media
.
.
FIgure Savmgs Recovered Througb Improved
Housekeeping
Strategies for energy saving:
I)Introduce equipment cleaning as a
regular part of maintenance inspections.
II) Whenever possible, place air filtration
media on outside of equipment so that
the condition can be easily seen and
changed as required.
7.PM practices:
An over tightened motor connection
results in a broken motor connection.
The 400hp, 460v ,441 amp motor is run
24 hours a day for 265 days a year. The
annual energy loss is calculated as
follows:
• Assume hot spot
0.10 hm
resistance to ground
• electricity = RsO.055/kW
• (441 amp) 2 x 0.10 hr = 19.44 kW
•
24hr x 265 days/year x 1O.448kW x
RsO.055
• RS6,800 per annum.
A simple broken connection not
only represents a potential safety hazard
and in this case, also a potential energy
savings of almost Rs7,000.
Strategies for energy saving:
I)Check present P.M. instruction sets for
ambiguity
II)Ensure task definitions are concise,
descriptive and relevant.
llI)Whenever possible, number the steps
involved, giving "if" and "then" options
to facilitate the process.
IV)Always produce feedback reports.
For example, how well equipment
performed as a result of the P.M. energy
usage prior to and post P.M.
a.Industrial Lighting:
The type of lighting used depends upon
the task or activity performed within the
specific workplace area In the industrial
work place there are three types of
lighting
presently
in use
1)
incandescent, 2) fluorescent, and 3) high
intensity
discharge
(sodium,
metal
halide, mercury vapor).
Case Study
A building has 600 fluorescent light
fixtures, each containing our 40W lamps
which burn for approximately 4000
hours per year. Management decides to
retrofit the lights with a new reflector
and better quality lamp, thus allowing
for the removal of two lamps and one
ballast from each fixture. A standard
F40 fluorescent lamp magnetic ballast
consumes 96w of electrical energy per
hour.
Initial system consumes 192w x 600 x
4000 divided by 1000 (for total kW
usage) x RsO.05kW energy cost = Rs
25,344 energy use.
The new system eliminates a 96W
ballast from 600 fixtures which reduces
energy requirements by 50%. Therefore
energy savings = 0.5 X Rs25,344 =
Rs12~672
Additional savings of a further 25% can
be gained by changing to an electronics
ballast..
Strategies for energy saving:
!)Clean light reflectors and lamp on a
regular basis
II)Perfonn a lighting management study
of determine exact lighting requirement
and
potential
energy
saving
opportunities
III)Replace incandescent lamps with
compact fluorescent lamps as lamps
bum out energy use is 800/0 less and the
lamp lasts four times as long with only a
one year payback
/'
9. Steam system:
Steams are a utility used to provide
power cleaning heating and process
manufacturing,
steam
system
efficiency is realized when the .system is
well designed and maintained. The
maintenance department can influence
steam system energy savings within
three major areas,
I) leak detection and elimination.
2) Pipe insulation checks, and
3) Water treatment.
Steam leaks can be effectively checked
b using an infra red thermal imaging
system or an ultrasonic leak detector
device.
Case Study:
A food processing
company produces 125 psig steam
for its hot water, sterilization,
cleaning and heating needs on a 24
hour, 300 day per year basis. An
annual infra red leak study of the
steam system found the following:
Evidence of three leaking steam
traps; further investigation concluded
that the leaks were equivalent to two
x 1132 orifice leak and a 1116 leak.
•
Leaking insulation at a flange area;
investigation concluded the leak was
substantial and was the equivalent of
a 1/8 orifice leak.
After replacing the traps and tightening a
re insulating the flange steam savings
based on Rs 6.00 per 1000 pounds steam
were calculated as follows:
•
1132 flow
•
1116 flo
•
118flow
A total steam loss of 72.7ib/hr was lost
Results:
24 hr x 300 days x 72.7 iblhr x Rs 6
divided by 1000 = Rs 3140.00 annual
savings
Conclusion:The
case studies and
examples cited in this paper diligent
management practices in plant operation,
careful
use of lighting
and air
conditioning, and other similar measures
to eliminate outright waste of energy.
The measures were said not to interfere
with production, not to reduce worker
safety or performance, and not to entail
unjustifiable cost; in fact, in many
instances,
the
fuel
conservation
measures were said to be accompanied
by significant cost savings.
Biblography:
Industrial Training through MERC,Mumbai
in following companies:
I. Crompton greaves Ltd ,Mumbai
& DTE,Mumbai
2. Seimens Ltd ,Aurangabad
3. Legrand Ltd ,Jalgoan
(