Steady State Operability Characteristics of an Adiabatic Fixed-Bed Reactor for Methanol Dehydration

Document Type : Research Note


Faculty of Chemical and Petroleum Engineering, Shiraz University,Shiraz, I.R. IRAN


Operability analysis as one of the most important bridges between process design and process control helps the process designer to investigate the control issues quite early in the design stage. Recently, Vinson and Georgakis suggested a steady state geometrical operability index as a quantitative measure for assessment of process operability. In this paper, DME fixed-bed reactor is heterogeneously modeled based on mass and energy conservation law at steady state condition. To verify the accuracy of the model, simulation results of the conventional reactor is compared with the available industrial plant data. It is observed that there is a good agreement between the simulation result and the plant data. Then, the steady state operability characteristics of DME reactor have been analyzed by using the ramework of Vinson and Georgakis. This paper demonstrates the utility of the approach to industrial chemical reactors. By measuring the operability characteristics of the reactor, the input and output operability index of the process is calculated equal to 43.31% and 57.58% respectively. The results showed the low process ability for creation of desired output by available input.


Main Subjects

[1] Skogestad S.,PostlethwaiteI., "Multivariable Feedback Control", Second ed., John Wiley & Sons,United Kingdom(2005).
[2] Rojas O., Bao J., Lee P., A Dynamic Operability Analysis Approach for Nonlinear Processes, Journal of Process Control, 17, p. 157 (2007).
[3] Helbig A., Marquardt W., Allgower F., Nonlinearity Measures: Definition, Computation and Applications, Journal of Process Control, 10, p. 113 (2000).
[4] Ziegler J.G., Nichols N.B., Process Lags in Automatic Control Circuits, Transactions of ASME, 65, p. 433 (1943).
[5] Swaney R.E., Grossmann I.E., An Index for Operational Flexibility in Chemical Process Design, Part I: Formulation and Theory, A.I.Ch.E. Journal, 31, p. 620 (1985)
[6] Russo L.P., Bequette B.W., Impact of Process Design on the Multiplicity Behavior of a Jacketed Exothermic CSTR, A.I.Ch.E. Journal, 41, p. 135 (1995).
[7] Lyman P.R., Luyben W.L., Tyreus B.D., Method for Assessing the Effect of Design Parameters on Controllability, Industrial and Engineering Chemistry Research, 35, p. 3484 (1996).
[8] Georgakis C., Uzturk D., Subramanian S., Vinson D., On the Operability of Continuous Processes, Control Engineering Practice, 11, p. 859 (2003).
[9] Vinson D.R., Georgakis C., A new Measure of Process Output Controllability, "IFAC Symposium on Dynamics and Control of Pprocess Systems", p. 700 (1998).
[10] Vinson D., Georgakis C., A New Measure of Process Output Operability, Journal of Process Control, 10, p. 185 (2000).
[11] Uzturk D., Georgakis C., Assessment and Enhancement of the Inherent Dynamic Operability of Pprocesses, A.I.Ch.E. Annual meeting", paper 244, (2000).
[12] Uzturk D., Georgakis C., Inherent Dynamic Operability of Processes I: Defnitions and Analysis in the SISO Case, Industrial and Engineering Chemistry Research, 41, p. 421 (2002).
[13] Lu W.Z., Teng L.H., Xiao W.D., Simulation and Experiment Study of Dimethyl Ether Synthesis from Syngas in a Fluidized-bed Reactor, Chemical Engineering Science, 59, p. 5455 (2004).
[14] Berčič G., Levec J., Intrinsic and Global Reaction Rate of Methanol Dehydration over γ-Al2O3 Pellets, Industrial and Engineering Chemistry Research, 31, p. 1035 (1992).
[15] Froment G.F., Bischoff K.B., "Chemical Reactor Analysis and Design", John Wiley & Sons,New York (1990).
[16] Cussler E.L., "Diffusion, Mass Transfer in fluid System", Cambridge University Press,United Kingdom (1984).
[17] Smith J.M., "Chemical Engineering Kinetics",McGraw Hill,New York, (1980).