Optimum operating cycle for systems with deactivating catalyst and the reaction of solid particles

Graduation date: 1977This thesis consists of two parts. Part I (Chapters 1,\ud 2, 3) of this thesis concerns finding the best way of\ud running a reactor whose catalyst decays with use, and must\ud consequently be replaced or regenerated at regular\ud intervals. Chapter 1 introduces the problem, and Chapter 2\ud develops a one variable search method which avoids the\ud previously proposed multidimensional search procedures.\ud Chapter 3 then applies this method to catalytic reactors\ud for various fluid-solids contacting patterns. Optimal\ud operation and regeneration policies are discussed for\ud reasonable kinetic expressions, and for reasonable economic\ud objectives. For independent and series deactivations rising\ud or maximum temperature policy is always optimal; for\ud parallel deactivations, however, the optimal policy\ud follows one of three patterns depending on reaction and\ud deactivation kinetic constants, and on economic parameters.\ud Optimal regeneration pattern is mainly dependent on\ud regeneration kinetics. A numerical example illustrates the\ud procedure for optimum scheduling, how to best operate and\ud at what point to regenerate.\ud Part II (Chapter 4) of this thesis proposes a model to\ud represent the reaction of initially dense solid particles\ud with gas. It views that cracks first form at the pellet\ud surface and then penetrate into the interior. As a result\ud the virgin core shrinks leaving behind a grainy structure\ud which then reacts away according to the shrinking core\ud model. Simple conversion-time expressions are obtained,\ud methods of comparison with experiment are suggested, and a\ud good fit is shown to reported iron ore reduction data