OP-II-3

PP-II-15of 1–2.5 lead to a decreasing rate constant of oxychlorination at 220°C by a factor of3–5. The complete conversion of hydrogen chloride can be achieved, in this case, byan increase in temperature to 245–255°C. The process selectivity remains 98–98.5%because the rate of ethylene oxidation or dichloroethane oxidation to form COxusually changes in a like manner together with a change in the rate of the mainreaction of oxychlorination.When the oxychlorination of ethylene is carried out in the fluidized bed of the catalyst,one of the major conditions is to maintain high quality fluidization. Specifically, conditionsfavorable for the agglomeration of catalyst particles should be excluded.An increase in the productivity of the reactor assumes an increase in the flowrates of initial reactants, which, in turn, affects the hydrodynamics of the fluidizedbed. The flow rate of gases is limited by the minimum fluidization rate. For number ofquantity of industrial catalysts of the fluidized bed, 20–100 μm particles and a bulkdensity of 1.00–1.10 g/cm 3 are typical. The minimum fluidization velocity is3.5–5.0 mm/s depending on the nature of the fluidizing agent.Proceeding from the threshold value of the fluidization number which is 77.7 forthe laminar flow, the maximum value of the working gas flow rate in the industrialreactor is 0.27–0.39 m/s.Industrial processes in which concentrated oxygen is used as an oxidant aremore flexible compared to the process in which air is used, because an increase inthe consumption of initial reactants is possible with a simultaneous decrease in theflow rate of the recycled gas, which is both a fluidizing agent and a diluent thatprovides explosion safe conditions of the process. Also the air based process can beintensified by enriching the air with oxygen to a concentration of 23–24%.One of the conditions for an increase in the productivity is the use of catalystswith a higher value of the equivalent diameter of particles. So, an increase in theeffective diameter of particles from 50 to 100 μm leads to an increase in the minimumfluidization velocity from 3.5 to 13.0 mm/s. In this case, the working linear velocity ofthe gas flow can be increased up to 0.7–0.8 m/s with rise of the productivity.If we consider a reactor and a catalyst as a mutually related system, the ways forincreasing the productivity can be associated only with technological parameters ofthe process (flow rates of initial reactants and their concentrations, temperature,pressure and others).359