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Pressure Relief of Non-Ideal Mixtures: Composition Trajectories & Residue Curve Maps
  • Paul Dillon
Paul Dillon
PM Group Ltd.
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Abstract

During the course of a pressure relief discharge from a vessel containing a multicomponent liquid mixture, composition changes occur that affect the properties vessel contents. In this work, a model of the dynamic relief process for ternary, non-ideal, homogeneous mixtures is developed, under the assumption of vapour-only venting. Opening/re-closing of the relief valve introduces state-events which require re-initialization of the model at each state transition. The relationship between the pressure relief model and the concept of residue curves, which describe simple-distillation processes, is demonstrated. It is known that the presence of azeotropes and distillation boundaries in mixtures restricts the composition trajectories of simple-distillation processes, as well as continuous distillation columns at total reflux. In this work, the residue-curve analogy is extended to vapour-only pressure-relief, where vapour composition changes directly affect the operation of the pressure-relief device. Examples of dynamic relief processes are developed for ternary mixtures with varying non-ideality.

Peer review status:ACCEPTED

28 Apr 2020Submitted to AIChE Journal
02 May 2020Submission Checks Completed
02 May 2020Assigned to Editor
11 May 2020Reviewer(s) Assigned
22 Jul 2020Editorial Decision: Revise Minor
13 Aug 20201st Revision Received
08 Sep 2020Submission Checks Completed
08 Sep 2020Assigned to Editor
16 Sep 2020Editorial Decision: Accept