Mass Integration as a Design Heuristic: Improvements in the HDA Process

This paper explores mass exchanging the Outlet and inlet streams of a. reactor, as design heuristic within the hierarchical process design procedure by Douglas [AIChE. J. 1985, 31(3), 353-361 and Conceptual Design of Chemical Processes; McGraw-Hill 1988], who worked on the HDA process to test the proposal:The heuristic is used at an early stage of the hierarchy, when deciding the recycle and separation system structure of the process. If the reaction requires operating conditions with reactants in excess or that catalyze the reaction, which must be removed after the reaction; there is a concentration gradient between the inlet and outlet streams that may be used as the driving force in a mass exchanger (if such a device is available for the particular case). When applied to the HDA process, this methodology generated alternatives different from the previously proposed by other authors by resorting to a ceramic membrane gas permeation unit to perform the mass exchange of hydrogen. The performance of applying the heuristic was tested comparing the flow sheets proposed by several authors with and without this mass exchanger. The success of implementing this Mass exchange networks synthesis concept was dependent on the concentration of the component to be transferred in the rich stream (i.e., it works if there is in appropriate driving force).