Foaming can hinder gas-liquid separation, therefore, it is desirable to break the foam upstream of separation facilities. There are different methods to breakup foam, including chemical (utilizing defoaming agent), mechanical (such as cyclones), and thermal (by increasing temperature).
Foam stability and breakup are studied in a standalone Churn Flow Coalescer (CFC) and in a Churn Flow Coalescer/Gas-Liquid Cylindrical Cyclone© (CFC/GLCC©) system. The goal is to investigate the possible improvement of the foam breakup efficiency in the GLCC© by installing a CFC upstream of the GLCC©. Testing the standalone CFC, it was found that the CFC generates more, but less stable, foam that can be broken more easily.
Three different CFC’s are tested with diameters of 1″, 2″ and 3″. For the same inlet conditions, the 3″ CFC with tangential inlet was found to be the most efficient for generating less stable foam. The optimal operating conditions for this CFC are at low superficial gas velocities, namely, vsg(CFC) between 0.1 to 0.3 m/s. Higher flow rates generate smaller bubbles and more stable foam. From testing the CFC/GLCC© system, it is found that foam breakup in this system is more efficient than that of the standalone GLCC©, under the same flow conditions.
The operational envelope of the CFC is predicted based on the transition boundary to churn flow developed by Taitel et al. (1980), as a function of the CFC aspect ratio (LE/D). The analysis of transition boundary between slug and churn confirm that less stable foam occurs at the left of churn flow transition boundary.