| Summary: | 碩士 === 長庚大學 === 化學工程研究所 === 88 === Direct-fired furnace as applied to pyrolysis reactions plays an important role in various refining and petrochemical processes. The aim of this work is focused on the optimization of such reactor with ethylene dichloride pyrolysis as an example. This cracking furnace is the key unit in the vinyl chloride monomer process. It turns out the choice of radiative heat flux distribution in the radiant section of the furnace is very critical in that it will strongly affect residence time in the reactor coil, reactor effluent temperature, tube skin temperature, reaction rate, furnace fuel consumption, degree of coking, and tube metal carburization. As a result, it can have a significant impact on the run length and overall process economics.
For this multiobjective optimization problem, a radiative heat transfer model based on the Zoning method has been built for a side-firing furnace and solved simultaneously with a reactor model. Simulation results show that there exist an optimal firing pattern (or fuel allocation policy) and an optimal temperature profile for the reaction coil, under which higher cracking depth can be achieved in the reactor. Alternatively, from the viewpoint of energy saving, the reactor can be operated at reduced heat loads (or fuel consumption) when cracking depth is fixed. The results will aid in better design and operation of the cracking furnace.
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