Gravity Separator Fundamentals and Design
Author: Todd Jekel, PhD, Douglas Reindl, PhD, P.E. and J. Michael Fisher
The objective of this paper is to review the literature on the principles governing gravitydriven separation of liquid-vapor mixtures, review design methods for separators, and develop a model that predicts separator performance given operating requirements (i.e. size or velocity, and design droplet size) subject to design constraints. The model presented can serve as a basis to establish a fundamentals-based new design method for gravity separators. It is not the purpose of this paper to develop or recommend design guidelines; rather it is a literature search and analysis to parallel existing design guidelines to ammonia. The paper summarizes landmark literature in the history of gravity separation and reviews the assumptions made in both the literature and the techniques developed in the paper. Equations of motion that define the droplet trajectories in both vertical and horizontal vessels are presented and implemented in a computer model. Results of in-depth analysis aimed at characterizing liquid vapor separation in both vertical and horizontal vessels are presented. ASHRAE recommendations for vessel sizing are quantified using the techniques developed in this paper. Other author’s recommendations for vertical vessel sizing are also analyzed and compared to the ASHRAE recommendations. A design example is presented for both vertical and horizontal vessels.