الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Urea synthesis is one of the most important industries in agriculture as a fertilizer. Urea is generally used as a crude material in producing many chemical compounds including chemical solutions, plastics, adhesives and medical drugs and the study of the reaction kinetics is of great interest to the industry. This thesis introduces the mathematical model of ammonia and urea reactors and suggested five methods to overcome the parameter variation and external disturbances that affect the ammonia-urea reactors, reducing the pollution effect, increasing urea production, and improving stability.
The first proposed method is PID controller and the second is sliding mode controller (SMC). These controllers are applied for a multivariable nonlinear system as a Urea Reactor system. The main target of the designed two controllers is to reduce the disturbance of 〖NH〗_3 pump and 〖CO〗_2 compressor in order to reduce the pollution effect in such chemical plant. Simulation results of the suggested PID controller are compared with that of the SMC controller. Comparative analysis proves the effectiveness of the suggested SMC controller than the PID controller according to disturbance minimization as well as dynamic response. Also, the thesis presents the results of applying SMC, while maximizing the production of the urea by maximizing the 〖NH〗_3 flow rate. This controller kept the reactor temperature, the reactor pressure, and 〖NH〗_3/〖CO〗_2 ratio in the suitable operating range. Moreover, the suggested SMC when compared with other controllers in the literature shows great success in maximizing the production of urea. The third proposed method is Adaptive model predictive controller, the fourth is Adaptive Neural Network Model Predictive Control, and the fifth is Adaptive neuro-fuzzy sliding mode controller. These methods are applied to a multivariable nonlinear system as Ammonia-Urea reactors system. The main target of these controller is to achieve stabilization of the outlet concentration of ammonia and urea, stable reactions rate, increase the conversion of carbon monoxide (CO) into carbon dioxide (carbon dioxide (〖CO〗_2) to reduce the pollution effect, increasing the ammonia and urea productions, keeping the 〖NH〗_3/〖CO〗_2 ratio equal to 3 to reduce the unreacted 〖CO〗_2 and 〖NH〗_3, and the two reactors temperature in the suitable operating ranges due to the change in reactors parameters or external disturbance. Simulation results of the three controllers are compared. Comparative analysis proves the effectiveness of the suggested Adaptive neuro-fuzzy sliding mode controller than the other controllers according to external disturbance and the change of parameters. Moreover, the suggested methods when compared with other controllers in the literature show great success in overcoming the external disturbance, the change of parameters, and reducing the pollution effect. The validity of the proposed methods is confirmed by simulation results. The five approaches are explained in clear details, which are designed using MATLAB/2015 software package.