There is a considerable scope for improving the temperature control of
exothermic processes. In this thesis, a sub-optimal control strategy
is developed through utilizing the dynamic, simulation tool. This
scheme is built around easily obtained knowledge of the system and
still retains flexibility. It can be applied to both exothermic batch
and fed-batch processes. It consists of servo and regulatory modes,
where a Generalized Predictive Controller (GPC) was used to provide
self-tuning facilities.
The methods outlined allow for limited thermal runaway whilst keeping
some spare cooling capacity to ensure that operation at constraints
are not violated. A special feature of the method proposed is that
switching temperatures and temperature profiles can be readily found
from plant trials whilst the addition rate profile Is capable of
fairly straightforward computation. The work shows that It is
unnecessary to demand stability for the whole of the exothermic
reaction cycle, permitting a small runaway has resulted in a fast
temperature response within the given safety margin.
The Idea was employed for an exothermic single Irreversible reaction
and also to a set of complex reactions. Both are carried out in a
vessel with a heating/cooling coil. Two constraints are Imposed; (1)
limited heat transfer area, and (11) a maximum allowable reaction
temperature Tmax.
The non-minimum phase problem can be considered as one of the
difficulties in managing exothermic fed-batch process when cold
reactant Is added to vessel at the maximum operating temperature. The
control system coped with this within limits, a not unexpected result.
In all cases, the new strategy out-performed the conventional
controller and produced smoother variations in the manipulated
variable. The simulation results showed that batch to batch variations
and disturbances In cooling were successfully handled. GPC worked well
but can be susceptible to measurement noise. / Higher Education Ministry and Scientific Research
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/4217 |
| Date | January 1989 |
| Creators | Kaymaz, I. Ali |
| Contributors | Henry, R.M. |
| Publisher | University of Bradford, School of Control Engineering |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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