Hydrocarbon Processing - December 2021 - 58

Environment and Safety
mining operations across a wide array of industries could reasonably
reduce energy consumption by 20%-25% by implementing
state-of-the-art best practices. To put the opportunity
in perspective, industrial plants consume about 30% of the
total energy budget in the U.S., and reclaiming this wasted energy
could reduce the country's national energy consumption
and associated GHG emissions by 6%-7.5%. This article will
include a non-exhaustive checklist of some reliability engineering
best practices to reclaim some of this lost energy.
The following are ways to employ proactive mechanical best
practices:
* Minimize precision mechanical fastening practices
* Follow precision mechanical balancing practices
according to ISO 21940 G1.0 for critical assets
and G2.5 for the balancing of plant assets
* Precisely align mechanical drive systems:
° Ensure shaft alignment to 0.3 mm/in. of angularity
and 1 mm of offset for 3,600-rpm applications
° Laser align pulleys, sheaves and sprockets
° Precisely align conveyor belts
° Minimize pipe strain
° Always consider thermal growth in alignment
calculations
* Minimize V-belt slip to less than 2%, and use a
strobe light to determine slip percentage
* Select the correct lubricant type and quantity:
° Determine sufficient viscosity and lubricity
to minimize boundary contact friction
° Avoid excessive viscosity, which can produce fluid
friction and churning losses
° Consider the operating temperature and the
temperature range, and select lubricants
TABLE 1. Energy and environmental impact comparison
of an IE4 motor vs. an IE1 motor
Motor kW rating
Assumed load, %
Operating, hr/yr
Efficiency, %
kWh/yr
Energy cost/yr
at 0.06/kWh
CO2 emissions/yr, kg
Social cost of carbon/yr
IE1, 2 pole
75
80
8,000
92.7
517,799
$31,068
366,084
$18,304
IE4, 2 pole
75
80
8,000
95.8
501,044
$30,063
354,238
$17,712
Differential
3.1
-16,756
-$1,005
-11,846
-$592
Details
TABLE 2. Injury rate reduction through precision maintenance
Original Improved Differential
Mean time between repairs, mos
Corrective maintenance task, FTE
Corrective maintenance task, hr
Corrective maintenance task,
worker hr/yr
Estimated annual injuries,
4.2/100 FTE
Estimated annual cost, $100/hr
12
4
8
32
0.0014
3,200
58 DECEMBER 2021 | HydrocarbonProcessing.com
96
4
8
4
0.0002
1,000
+700%
-
-
-88%
-86%
-69%
Safety benefits of reliability engineering. Many reliability
engineers have little to no interaction with the well-regulated
with an appropriate viscosity index
* Keep the in-service lubricant healthy and free of
particles, water, air and other contaminants
* Properly size pumps based upon the application
* Operate pumps at peak curve efficiency
* Ensure a sufficient suction-side head to avoid cavitation
* Properly size piping/hosing (diameter and length) and
minimize bottlenecks for all fluid conveyance systems,
with minimal turns and curves, to minimize fluid friction
and churning losses.
The following are ways to employ proactive electrical best
practices:
* Use high-efficiency motors-IEC IE4 class motors are
about 3% more energy efficient than IE1 class motors
(e.g., for a 75-kW electric motor, an IE4 can reduce
lifetime energy costs by more than $10,000 vs. an IE1
motor in the same application, as shown in TABLE 1;
applied to a fleet of 1,000 motors on a typical site, this
can result in a staggering $10 MM lifecycle benefit)
* Deploy variable frequency/speed drives where appropriate
* Minimize phase-to-phase electrical unbalance
(such as voltage and current), and keep the voltage
imbalance to less than 2% (less is best)
* Properly size, install and maintain electrical circuits
to reduce heat
* Ensure proper electrical connections in all applications
* Minimize harmonic distortion to less than 3% for
any single harmonic and less than 5% total harmonic
distortion for systems under 69 kilovolts (kV)
* Minimize reactive power, and make power corrections
through synchronous motor control.
Managing fugitive emissions. Fugitive emissions waste
energy, and these emissions can cause the unintended release
of polluting and hazardous effluent. Compressed air systems
represent a great opportunity to reduce energy consumption.
Approximately 10% of a typical energy budget is spent compressing
air. It is not uncommon for compressed air systems to
suffer a 20%-30% leakage rate. This means that a site can leak
as much as 2%-3% of its total energy expenditure into the atmosphere.
Leaking in other compressed/pressurized fluid systems
(such as natural gas; water; and lubrication, hydraulic and
steam systems) wastes a great deal of energy. In addition, in the
hydrocarbon-intensive industries, flare-minimization strategies
have been shown to dramatically reduce waste of methane and
other hydrocarbons, and to reduce sulfur dioxide emissions.
In addition to energy conservation, some fugitive emissions
have a direct and adverse effect on the environment and on
people. For example, during its first 20 yr in the atmosphere,
methane is about 80 times more powerful than CO2
as a GHG
before settling down to 25 times more powerful after 100 yr
in the atmosphere. Liquid and solid effluents can contaminate
watersheds and adversely affect the quality of drinking water.
Studies have shown that people living near refineries and other
petrochemical facilities suffer rates of cancer that are much
higher than normal rates.
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