SIMULATION AND OPTIMIZATION OF A SET OF CATALYTIC REACTORS USED FOR DEHYDROGENATION OF BUTENE INTO BUTADIENE

The simulation and optimization of a set of industrial fixed bed catal ytic reactors is presented. The reactors are operating in deactivation -regeneration cycles. Dynamic mathematical models for the four stages of the process are included, i.e. dehydrogenation (deactivation by cok ing), steam purge, oxidative regeneration and evacuation. An iterative method was used to simulate an autothermal process, which is common i n the industrial practice. To prevent the permanent loss of the cataly st activity by sintering, an upper limit of temperature has been impos ed. The cycle time, temperature and composition of the feed during the regeneration stage are selected as optimization variables. Under auto thermal conditions, the four stages of the cycle start with markedly n on-uniform thermal profiles in the catalytic bed, which have considera ble influence on the maximum temperature of the cycle. In this way, th e production rate of butadiene has been substantially improved as both the maximum allowable temperature and the inert-catalyst ratio increa se, The higher the oxygen molar fraction at the regeneration stage, th e shorter is the optimal duration of the cycle.