Buna Sow Leuna Finds Flashing Fluid Fix!

When the valves installed at DOW Germany’s Buna Sow Leuna plant were experiencing damage due to flashing fluids, they relied on CCI to replace the troublesome valves with DRAG® water drain and level control valves to eliminate the costly problems in maintenance and production output. The water drain valves and level control valves provided by CCI are designed for the liquids flowing at high velocities that over time can erode the trim, and hence, make it difficult to control liquid level. By incorporating advanced velocity control technology, the cause of these high-maintenance requirements is addressed and thereby eliminated.

In Depth: Calculating Complex Flashing Liquids

— Excerpted from “Control Valve Sizing for Complex Liquids” by J. Gary MacKinnon.

The Instrument Society of America publishes standard S75.01 entitled “Control Valve Sizing Equations.” This standard outlines the method of sizing control valves for flashing liquids, non-flashing liquids and gases which account for the vast majority of fluids encountered in industrial applications. Occasionally, valve sizing is required for fluids that differ from those covered by the standard such as a gas liquid mixture and multi-constituent liquids whose constituents flash at various pressures. The Standard is not applicable to these fluids because the behavior of the fluid density as the pressure drops through the valve does not fit the fluid models which form the basis of the standard. In addition, the problem is complicated by slip between the phases and thermal non-equilibrium. Although a general solution has not been found, CCI utilizes a method of sizing control valves that handle complex fluids by using a set of apparently overly restrictive assumptions. Yet when the results are compared to the present ISA equations where these assumptions are not present, good agreement is found.

Published in SOLUTIONS Winter 2001