Control of a Chaotic Autocatalytic Reaction in a Continuous Stirred Tank Reactor

Systematic methods and tools for managing the complexity

Process Control (T4-8)

Mr Ankur Muherjee
Newcastle University
School of Chemical Engineering & Advanced Materials
Room M601, Merz Court
Claremont Road
Newcastle upon Tyne, NE1 7RU
United Kingdom (Great Britain)

Dr Dominic Searson
Newcastle University
Chemical Engineering & Advanced Materials
School of Chemical Engineering & Advanced Materials, Merz Court, Newcastle University, Newcastle upon Tyne, NE1 7RU
United Kingdom (Great Britain)

Dr Mark Willis
University of Newcastle
Chemical Engineering and Advanced Materials
CEAM,
Merz Court,
University of Newcastle,
Claremont Road,
Newcastle upon Tyne
United Kingdom (Great Britain)

Prof Allen Wright
University of Newcastle
Chemical Engineering and Advanced Materials
CEAM,
Merz Court,
University of Newcastle,
Claremont Road,
Newcastle upon Tyne
NE1 7RU
United Kingdom (Great Britain)

Keywords: chaos, feedback control, heat evolution data, CSTR

Control of chaos in chemical reaction systems is crucial considering the necessity to mitigate long term unpredictability and non-uniform system performance, e.g. irregular product concentration/selectivity at any given time. Chaos in chemical systems may be controlled by stabilising unstable periodic orbits using temporal perturbations to an accessible process parameter. This paper investigates if product selectivity (the ratio of the quantity of desired product to the total quantity of products) of a chaotic autocatalytic reaction may be improved by feedback control of a single observed state variable. The reaction is simulated in a continuous stirred tank reactor. In this system, two products are produced by a reaction scheme that exhibits non-linear feedback characteristics and properties of multi-stability, oscillations and chaos. The state variable used for the chaos control algorithm is derived from the time series of the rate of heat evolution data obtained from the reactor. The aim of this work is to demonstrate a novel design technique for the control of chaos in a generic chaotic chemical reaction system in which the system equations are unknown and only a single state variable is available for measurement and control. The Simple Proportional Feedback control algorithm (Davies and Scott, 2001) is implemented on this system. The objective of this paper is to compare the product selectivity of the reaction system when it is stabilised to different desired unstable periodic orbits. The performance of the control algorithm is evaluated when noisy heat evolution data are sampled for the feedback law. Also, disturbance rejection properties of the controller are investigated when reactant inlet feed disturbances are applied to the system.

Reference
Davies, M.L. and Scott, S.K. (2001) Control of product selectivity for a model with mutating autocatalysis, Chemical Engineering Science, 56, 15, 4587-4595.

Presented Tuesday 18, 15:40 to 16:00, in session Process Control (T4-8).