Design of a decoupler controller for forced circulation evaporator used in a radioactive treatment plant

Evaporation is a proven method for a treatment of liquid radioactive wastes providingboth good decontamination and high concentration. In a radioactive waste treatment plant, anevaporator is used to reduce the volume of medium radioactive liquid waste arising fromdifferent applications of nuclear industries. The control system objective is to limit thecomposition of the liquid waste at a prescribed value. For the safe operation, without damagingthe installed equipment, a good control for the evaporator operating pressure and the level ofliquid waste inside the separator part has been required.Evaporator equipment is a complex process, which is a multivariable, nonlinear and hasmany disturbances. Therefore, design a control strategy for the evaporator is bit difficult. Thesolution method is based on system decoupling eliminating the parasite interactions betweeninput-output pairing variables and converting Multi-Inputs Multi-Outputs (MIMO) system toseveral Single-Inputs Single-Outputs (SISO) systems.The main objectives of this thesis are: Firstly, to control the separator level. Secondly, todevelop a design of 2x2 decoupler controller for forced circulation evaporator used in aradioactive waste treatment plant. Within this context, a mathematical model of forced circulationevaporator is defined. This non linear model is represented using three different simulink models.Then, the linearized evaporator model has been developed. The separator level is controlled byusing three different controllers. Finally, the design of the decoupling controller for the developedIinearized model is introduced.Computer Results demonstrate that:The Deadbeat response has been succesfully obtained from the proposed separatorcontrol system .The designed decoupling controller shows better performance for set-point and loadchanges. Moreover, the robustness of this suggested control system is proven.