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Audited benefits of $958K per year from the online system |
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Benefits of over $110K per year identified using the offline optimization tool |
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Identified losses from degradation in the performance of the mills |
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Unified approach to plant operation across all powerhouses on the site |
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Received energy efficiency award by American Chemistry Council |
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Challenge
The utilities plant at Eastman supplies steam and power to the
process plants and offices on the 1,046 acre site, producing on
average 3.6M lb/hr of steam and 176MW of electricity. In view of the
rising increase in power and fuel costs, the utilities plant was the
focus area in Eastman's initiative to reduce energy costs. An
optimization system was identified as a key factor in achieving this
goal.The utilities plant is located in 4 powerhouses and consists
of 17 boilers and 19 steam turbine generators. Coal is the main fuel
burnt (except in the 3 gas-fired backup boilers). The boilers also
serve to dispose of waste material including biosludge, waste gas
and waste liquid. Steam is generated in the powerhouses and
distributed to the site at 3 pressure levels. The powerhouses
operate a complex steam system where steam can be let down from one
level to another via steam turbine generators, pressure reducing
stations and equipment turbine drives whose exhausts can be switched
between headers. Regulatory limits are also set for NOx emissions in
the powerhouses during the ozone season. If the total NOx emission
is below the permitted amount at the end of the NOx season, the
balance may be traded on the market.
Solution
Eastman selected AMS Optimizer as the key
technology to achieve the energy savings goal because of its proven
track record in delivering significant benefit from online
optimization.Using AMS Optimizer, a robust and reliable process
model of the utilities infrastructure and electrical distribution
network was developed, covering the full range of possible operating
modes on the plant. The model is automatically tuned to reflect
changes in equipment performance. It also forms the basis of the real-time optimizer. AMS
Optimizer obtains and conditions its input data from the site data
historian. Running every 5 minutes it generates the optimum loading
on each boiler based on the current demands and redistributes steam
to the most efficient power generating units. In the ozone season, the AMS Optimizer predicts the NOx emission
rates, ensures that emission limits are not violated and that the
NOx savings are recognized when generating the optimum boiler
loading.
The results are displayed in an easy-to-use, purpose-built user
interface, for implementation by the plant operators. The user
interface provides a consistent view to operators in all the
powerhouses and also to the engineers and managers across the site.
Prior to commissioning each powerhouse operated with different
philosophies, but AMS Optimizer has provided a unified approach to
plant operation across the powerhouses. The total benefits of the
optimization system to Eastman was audited and found to be
in excess of $1M per year.
The American Chemistry Council awarded Eastman an 'Exceptional
Merit' distinction for 'Significant Improvements in Manufacturing at
a Plant Site' for this utilities optimization system.
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