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PRESS RELEASE

R² Controls Completes major control projects at Sunoco

2nd major project improves yield

Jan2001 -- The recent project involves exothermic reactors, reactor modeling, reactor analysis, and reactor instruments and controls.  This project comes on the heels of a previous reactor control project that used a similar overall methodology.  The reaction is basically heat CHP (Cumene Hydroperoxide) with a little catalyst, and remove the heat as fast as it is formed.  The process is typical for a "Phenol Production Plant" and the process technology is licensed for general use by UOP and Sunoco.  The overall process starts with Cumene reacting with oxygen to form CHP.  The CHP is decomposed to form the products Phenol, Acetone, and AMS.  This project involved the second reaction which is the decomposition of CHP.  A joint Invensys, Sunoco, and R²Controls paper is being written on the most recent project and should be available soon.

The decomposition reactor was modeled with detailed kinetics. The reactor was built as a "User Block" in Aspen plus flowsheet simulator. The model was very useful to compute what the reactor would make for any conceivable reactor operating condition.  If you notice the 2 graphs shown here, you can see some calculations made from the reactor models, including the optimal operating point.  To verify the model, the reactor was tested with a DOE (Design of Experiment) type of test.  This is a hard thing to do on an operating unit, but the results were worth the effort.  Prior to running these tests, certain instrument and regulatory control improvements were made. Test results showed the models were not in complete agreement with the plant tests, but they were close, and the overall conclusions and optimal operating points computed with the models were confirmed.  This information was essential to structure the control system, as we needed to specify which constraints would be involved, and what direction the control system needed to go to drive the operation to the most profitable operating point.  The control system was implemented using DMC+ multivariable control technology.  The controls were relatively simple as multivariable controllers go, involving 3 MV's (Manipulated Variables) and 5 CV's (Controlled Variables).  A dynamic simulation using Cape Software, www.capesoftware.com was used for control system testing and for operator training.  By starting with a detailed understanding of the process, making required instrumentation and regulatory control improvements and finally implementing a relatively simple multivariable controller, the process has never been operated better and is destined for optimal operation in the future.  An audit comparing before and after operation shows a significant increase of yield in the most valuable AMS product and greatly improved stability as evidenced by standard deviations of important controlled variables.

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