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4% increase in plant throughput |
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$1M per year savings |
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Project payback of less than 6 months |
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Improved operational performance at current plant rates |
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Improved production management to account for frequently changing prices |
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Case study analysis for process investigation including detailed tailor made models |
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Challenge
This ethylene plant primarily produces ethylene and propylene from a
feedstock comprising of gases (ethane, propane and dry gas) plus
heavier liquids (mainly C4's). Since its commissioned date, the
plant has undergone two major expansions. The plant now has a total
of 9 USC cracking furnaces with 2 feed headers that feed parallel
compressor trains, which supply cracked gas to 2 separation trains.
The most recent expansion resulted in a 60% increase in production
capacity with the plant now having an ethylene throughput of 750,000
tonnes per annum.
Following the installation of Emersons first closed loop optimizer,
the system was able to meet the original objectives:
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Maximize gross margin |
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Match site ethylene demands |
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Respond quickly (within minutes) to changes in feed
availability |
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Provide constraint filling |
Following each subsequent plant modification, the optimizer has been
upgraded. During the latest expansion program, the customer wanted to
maximize the availability of the optimizer. Solution
AMS Optimizer forms the basis of the optimization system.
AMS Optimizer forms part of AMS Suite, an integrated family of applications for predictive maintenance,
performance monitoring and economic optimization.
AMS Optimizer interfaces with the plant control system every 3
minutes generating the optimal operating setpoints based on current
operating conditions. These are sent direct to the DCS controllers.
It provides operators and managers with the ability to open and
close the loop between the optimizer and plant controllers at any
time. Engineers also have the facility to use an open-loop optimizer
that specifies the operating margin assuming that each variable has
moved to its full range of operation.
AMS Optimizer is tuned to work in cooperation with the conventional
advanced controls. The optimizer bases its results on actual
operation and its outputs are restricted based on rate of change.
The optimizer gradually ramps the plant to the optimum position
using the advanced controls to handle the changes, therefore the
plant is never subjected to sudden large change. This closed loop
functionality combined with the intrinsic reliability of AMS Optimizer gives a
robust solution that is easy to use and is well accepted by process
operators. Engineers also have the facility to use an open-loop version of the
optimizer that specifies the operating margin assuming that each
variable has moved to its full range of operation.
* Due to a change in operating company we can no longer disclose
the customer name. The original customer was BP prior to the change
in operating company. The system is still operational.
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