Properly designed liquid-liquid coalescing systems efficiently separate the emulsifed or dispersed liquid from the continuous phase of the process stream so that downstream contamination is avoided. Simplifying the system, an emulsion enters a coalescing unit, the fluid mixture passes through the separation medium in an inside-to-outside flow pattern and the small dispersed liquid droplets form larger droplets, or coalesce, and subsequently separate from the continuous phase. The continuous phase exits through its designated outlet and the discontinuous phase is drained from a sump. However, the process isn’t quite so simple; it is actually a complex process with many factors to consider. Creating a system for efficient separation requires technical expertise acquired from years of experience and an expert understanding of the science and parameters affecting the process. Fluid compatibility, viscosity, interfacial tension, specific gravity, and flow rate are all important parameters in sizing an efficient system. In addition, coalescer protection, element design and vessel design are very critical.
Protecting the Coalescers: To operate at their highest efficiency, coalescers must be free from solid contaminants. Installing the correct pre-filtration system upstream of the coalescing unit is critical for proper functioning and operating efficiency. Solid contaminants can plug coalescer media which can lead to more frequent changeouts and less efficient performance. FTC offers a full line of liquid/solid filters and vessels to protect our Strata separation technology.
Coalescer Element Design: The actual coalescence of the dispersed droplets occurs inside the coalescing elements through a 3-step process. First, the process is initiated with the interception of the dispersed liquid droplets in the stream by the microfiber matrix. Next, after the interception phase, the small droplets effectively coalesce within the fiber matrix to form larger droplets. Finally, in the drainage phase, the large liquid droplets are released from the coalescing element. FTC’s engineers understand the science behind this complex three stage process and carefully select the proper element style, media type and layering for each application.
Vessel Design: The separation process is not completed when the droplets leave the coalescing element. The larger droplets exiting the coalescer elements enter the disengagement phase where they separate from the continuous phase more rapidly due to droplet size and gravitational forces. Vessel design is critical in order to provide efficient separation of the discontinuous phase from the continuous phase. Improper vessel design will compromise the separation efficiency and allow the liquid contaminant to exit the vessel with the continuous phase causing contaminant carry over. FTC engineers evaluate the critical parameters of each application such as exit velocities, droplet rise or fall rates, and nozzle locations to ensure proper removal of the discontinuous phase.