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Simulation and Control of Fixed Bed OCM Reactor

Valadkhani, Ali | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42741 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shahrokhi, Mohammad; Pishvaei, Mahmoud Reza; Zarrinpashneh, Saeed
  7. Abstract:
  8. Oxidative coupling of methane (OCM) in a fixed bed tubular reactor over Mn-Na2WO4/SiO2 catalyst has been studied. Four kinetic models have been considered for OCM reactions. Based on an objective function and using genetic algorithm, kinetic parameters have been estimated. A reactor tube with 20 mm diameter and 400 mm length surrounded by molten salt for removing heat of reaction has been used for experimental study. Effects of different factors such as CH4/O2 ratio, nitrogen content in feed and contact time are investigated experimentally and by simulation. A good agreement has been observed between simulation and experimental data. Oxidative coupling of methane (OCM) in an industrial fixed bed multi-tubular reactor over the Mn-Na2WO4/SiO2 catalyst has been studied. A reactor system containing 15000 tubes has been used for simulation study. In order to control the reactor temperature, different control loops have been studied and the best one is selected. Except reactor temperature, several other variables like feed temperature, natural gas, oxygen and nitrogen flow rates should be also controlled. An artificial neural network has been designed for new set-points calculations and keeping the reactor yield at its maximum value during changes in feed composition and conditions. The performance of the block oriented Hammerstein nonlinear model predictive controller (HNMPC) for controlling the reactor temperature has been tested and compared with that of PID controller through dynamic simulation. Simulation results for load rejection, set-point tracking and also model mismatch scenarios show that the HNMPC method has a better performance compared to PID controller
  9. Keywords:
  10. Kinetic Model ; System Identification ; Neural Network ; Block Oriented Hammerstein Model ; Fixed Bed Reactor ; Oxidative Coupling ; Model Predictive Control

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