The KLS Operates Over a Large Range of Operating Variables

The KLS is able to operate over a large range of operating variables

Turndown is not an issue for the Mueller KLS Helical Coil Separator. The patented helical coil geometry generates a high g swirl that works to remove contaminates from the gas stream. For contaminates to remain in the gas stream, the buoyancy and drag forces must overcome the inertial force created by the high g swirling action. Through CFD analysis, Mueller has found that even at minimum gas mass flows (1.5 lb/min) the helical coil produces nearly 200 g’s.

The high g centrifugal force acting on the contaminate particles is greater than the combined buoyancy and drag forces even at low gas flows. In addition to generating a high g swirl, the KLS geometry forces the gas to turn inward toward the center axis as it exits the gas channel outlet.

The transition from the outlet of the helical gas channels to the inlet of the clean gas outlet tube does two things: it makes following the gas path difficult because the gas is moving inward while the high g swirl is forcing the contaminate outward, and the radius of the swirling flow decreases due to the clean gas outlet tube geometry causing the inertial forces to increase. Combined, these attributes allow the KLS to operate across a wide range of operating variables without affecting the separation performance.




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Defoaming Capabilities of the Mueller KLS Helical Coil Separator

Swirling flow plays a central role in process intensification and is the basis for the operation of foam-breaking or “defoaming”. Foam breaking occurs in three stages: draining of the cellular liquid that makes up the walls, breakage of the foam walls, and diffusion of the gas out of the foam cells.

Defoaming chemicals are widely used in industrial applications but requires the user to install and maintain a special chemical injection system and the ongoing purchase of chemicals which can be expensive. It has been found that one of the most effective ways of breaking many types of foams is by using centrifugal force. Foam breaking through centrifugal force can often significantly reduce, if not eliminate, the dependency of such chemicals (Hoffmann, et al., 2007).


Generally speaking, when a fluid mixture enters into the helical coil separator, the light phase (gas) is displaced inward toward the axis due to the heavy phase (liquid, solids, or both) being pushed to the outer wall by the centrifugal force. If the fluid mixture contains foam, the gas bubbles will tend to migrate toward the central axis of the KLS. As the foam concentrates toward the axis, the shear stresses within the KLS will distort the cellular structure of the foam.

The combination of the centrifugal force and the shear separates the incoming foam into its component vapor and liquid phases so that only the gas remains at the center and the liquid is pushed to the wall (Hoffmann, et al., 2007).
As one can imagine, the defoaming benefits of mechanical separators is proportional to the centrifugal force that they create. In the case of the KLS, the helical coil element is designed in such a way that it creates a high G swirl region between the helical element and the clean gas tube. This region has been shown to generate over 10,000 Gs at high gas flows (10.967 lb/min) and just over 200 Gs at low gas flows (1.567 lb/min).

Another advantage of the KLS is the high tangential flow region just outside of the vortex core. The motion in this region is almost purely tangential further aiding in the removal of the liquid after the foam structure has broken. Further analysis by Hoffman et al indicates that the low pressure core of the vortex allows the dissolved gas to be liberated from the foam structure. The gas bubbles that have been liberated can then be separated from the liquid phase.

Works Cited
Hoffmann, A.C. and Stein, L.E. 2007. Gas Cyclones and Swirl Tubes. New York : Springer-Verlag, 2007.


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Mueller KLS Helical Coil Separator - An Introduction

Mueller Environmental Designs, Inc. has developed and patented a breakthrough in separation technology. The Mueller KLS Helical Coil Separator utilizes impingement and coalescing techniques along with strong inertial forces to separate liquid and solid contaminants from the natural gas stream.

The Mueller KLS Helical Coil Separator has been in service for over 10 years (5 different helical element iterations) with the first unit going into service in 2000. Since that time, Mueller Environmental Designs, Inc. has sold over 100 units in varying applications throughout the natural gas industry.

The separation capabilities of the Mueller KLS Helical Coil Separator are made possible by the helical coil element geometry. The helical element has been engineered to maximize the separation efficiency. The helical coil element uses liquid impingement and inertial forces to maximize the collection of sub-micron aerosols.

The Mueller KLS Helical Coil Separator has been engineered to maximize the separation methods associated with the helical coil technology. CFD analysis shows that the velocity patterns throughout the Mueller KLS Helical Coil Separator are unchanged due to the flow rate. This means that the inertial fields and the separation mechanism exist independently of the gas flow rate.

For more information on the Mueller KLS Helical Coil Separator, visit us at:

Mueller Environmental Designs