| Abstract
| - Previous studies of tubular reactor systems have explored flowsheets with either a gas recycleor a liquid recycle. In this paper, we extend this work to consider a flowsheet with two recyclestreams: a large gas recycle from a separator drum and a small liquid recycle from a distillationcolumn. Both the steady-state economics and the dynamic controllability of this dual-recyclesystem are compared with those of single-recycle processes. Three kinetic cases are considered: an irreversible reaction with moderate activation energy, an irreversible reaction with highactivation energy, and a reversible reaction. Results demonstrate that the dual-recycle flowsheetis less expensive than the liquid-recycle system for the irreversible reaction case, particularlyfor the high activation energy where the total annual cost is 50% less. In the reversible reactioncase, the liquid-recycle system is less expensive, because of the need for a high-purity recycle.Control structures are developed for all three flowsheets that provide effective regulatory controlfor large disturbances.
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