Sun Mountain Lumber, air compressor upgrade, Deer Lodge, MT

casestudy
project
cost/savings•••
Sun Mountain Lumber
Compressed Air System
Deer Lodge, Montana
Total Cost: $342,287
History
NWE Incentive: $200,000
Located in Deer Lodge,
Montana, Sun Mountain
Lumber was formed in
2004 with the purchase
of the stud mill and finger
jointer facilities formerly
owned by Louisiana Pacific
Corporation. The facility is
owned by long-time Deer
Lodge residents, Sherm
and Bonnie Anderson.
Completion Date: June
2007
Customer Cost: $142,287
Calculated Annual Savings (kWh):
1,233,000 kWh
Measured Annual Savings (kWh):
1,900,000 kWh
Simple Payback with Energy Savings for
the Customer: 1.1 Years
Measured Annual Energy Cost Savings:
$133,000/year
project
features•••
• Two new 150 hp oil-flooded
rotary screw air compressors
with VFDs
• New compressed air dryer with
dew-point controls
• New 1,000 gallon receiver
• Sequence based, microprocessor control
• Combination of new and
repaired distribution piping to major
mill processing areas
• Actuated valves to shut off air
to inactive areas of the facility
• Benefits that extend beyond
energy savings and include
enhanced compressor life, more
reliability, and stabilized system
pressure
Sun Mountain Lumber is the largest private employer in the Deer Lodge
valley. The plant is a critical part of the Montana timber products
industry, purchasing raw materials throughout the State. It is also crucial
to the housing market because it produces two-by-four and two-by- six
studs used in the building industry.
Lumber manufacturing facilities use considerable amounts of electrical
energy. Prior to the modifications at Sun Mountain Lumber, the baseline
energy consumption for the compressed air system was approximately
three million kWh per year, with an average measured demand of 352
kW. The energy cost to operate the compressors was approximately
$215,000 per year.
Pre-Modification
As a first step in determining compressor energy reduction strategies,
base-case energy end-use data were collected and analyzed for the
four compressor systems in each of the plantʼs operation areas
(Debarker/Saw/Resaw, Finger Jointer, Planer Building, Dry Kilns).
The metering study verified that approximately one-half of the compressed air costs at the facility were due to leaks in the piping system
valves, hoses, actuators and associated equipment. The energy cost
associated with serving the leaks was calculated at $100,000 per year.
The study projected that a leak reduction program would reduce the
leak load by 50% (750,000 kWh per year). Metering data collected after
the project was complete showed that Sun Mountain reduced their leak
load by almost 80%.
In addition to leak reduction, the study recommended the integration of
the piping system and the installation of two new air compressors with a
computer based, sequencer control system. The new system integrates
all of the compressors into a common distribution system and reduces
“trim” or throttling losses common with multiple, small systems.The new
compressors also have a higher mechanical efficiency when compared
with the older compressors that were decommissioned.
As a baseline metric regarding existing compressor efficiency, the
average flow (SCFM) divided by the average recorded power was measured
for each compressor. The study provides the compressed air supply
efficiency (CASE):
Sullair Compressors for Debarker/Saw: 4.7 scfm/kW
QNW Compressors for Debarker/Saw – 3.0 scfm/kW
QNW Compressor for Finger Jointer – 5.4 scfm/kW
QNW Compressor for Planer Building – 3.6 scfm/kW
QNW Compressor for Dry Kiln – 2.3 scfm/kW
By comparison, a new oil-flooded, rotary screw compressor at 100 psi, at full
capacity (no throttle) produces approximately 6.0 scfm/kW.
Efficiency Improvements
To reduce air leaks and pressure drops due to friction losses, a new compressed air distribution system consisting primarily of four inch steel pipe,
was installed in a number of areas.
In addition, existing piping not
scheduled for replacement had
extensive leak repair completed on
it. The distribution system also was
fitted with no-air loss drain valves
and actuated valves to shut off air
to periodic operating processes
within the system. This includes the
Finger Jointer and Planer plants,
which are operated approximately
50 hours per week.
The project also included the
installation of two new 150 hp
oil-flooded rotary screw
compressors equipped with VFDs.
One compressor was installed
in the existing Debarker/Saw compressor room and the other was placed
near the Finger Jointer Plant. A 1,000 gallon receiver was also added to the
system, along with a new compressed air dryer and upgrades of the existing
dryer control system - which was retrofitted with dew-point controls.
The facilityʼs compressed air system is now sequenced using a computerized
control system. One of the new compressors runs continuously anytime the
air system is pressurized. The other new compressor runs only when the
Finger Jointer Plant is operational. The old compressors are designed to
operate as load/unload units,
except for one of the existing
QNW compressors in the
Debarker/Saw operation. It has
been designated for standby
use only.
And, as a final step, the entire
compressed air system was
re-checked for leaks using
ultrasonic leak detection
equipment.
other potential
applications•••
Compressed air systems and the
industries they serve are diverse
- therefore there is little statistical
data available to benchmark usage.
However, the USDOE estimates that
close to five billion dollars per year is
spent on compressor electricity.
Any operation that uses compressed
air can benefit from both evaluating
the total demand of their system, as
well as the compressed air supply
efficiency (CASE). CASE is a measure
of scfm per kWh.
Nearly 85% of compressor electrical
energy is lost in wasted heat energy.
Therefore, the remaining 15% of
energy should be used as efficiently
as possible.
Many potential improvements exist,
including those implemented at Sun
Mountain Lumber. Others include
heat recovery and alternative
strategies for low-pressure end use.
project contacts
and resources •••
Building Owner:
Sun Mountain Lumber, Sherm Anderson
(406) 466-2927
Contractors:
Rogers Machinery
Hawe Steel Design
S&J Datatech
NorthWestern Energy:
Dave Bausch, P.E.
(406) 497-2322