ROBUST CONCENTRATION CONTROL OF TARGET PRODUCT IN CHEMICAL REACTOR

Abstract

A liquid-phase continuous stirred tank reactor equipped with a mechanical stirrer and cooling jacket is considered as a control object. The reactor operates in the polytropic mode. The multistep series-parallel exothermic process is carried out in the reactor. The objective of chemical reactor operation is to obtain the key product of specified concentration. The paper deals with analytical synthesis of automatic concentration control system of target product which provides invariance, covariance to the given actions, asymptotic stability and robustness under the action of uncontrollable parametric and signal disturbances. The astatic control law obtained using the synergetic control theory is proposed. Using the method of analytical design of aggregated regulators (ADAR) for a given invariant manifold, a non-linear control algorithm with an integral part was synthesized which solves the problem of stabilization of the concentration of target component on the exit of the reactor at the given value under the action of disturbances on the object. Algorithmic synthesis of the control law is carried out using a non-linear mathematical model of the object without the use of the linearization procedure. As a result of simulation it was found that the closed-loop control system has no static control error under the action of uncontrollable parametric and signal disturbances on the object, changes in the set points and initial deviation of the state variables from the static values. Consequently, the proposed non-linear concentration control algorithm has the property of robustness. The obtained results indicate the effectiveness of the ADAR method and the prospects of the synergetic control theory for solving problems of algorithmic synthesis of control systems of non-linear, multi-dimensional and multi-connected technological objects. The integration of the synthesized control law of chemical reactor at the design stage will allow implementing flexible cybernetically organized chemical-technological systems.