Operation of Static Mixer® Units

By:

Kenics Corporation

This technical report details the installation, alignment, and operational requirements for Kenics static mixer units designed to blend fluids, gases, and solids through helical flow division. It provides specific engineering guidelines for module orientation and injection techniques, including calculated velocity ratios and nozzle placements based on the viscosity and flow rates of the materials involved. Additionally, the document emphasizes the necessity of precise metering control and explains the design of injection headers to ensure uniform distribution across the mixing elements.

Key Learnings

• Mixing Mechanism: Static mixers utilize unique helical elements to achieve intimate mixing through a combination of flow division and radial mixing, which remains effective regardless of changes in system throughput.
• Module Alignment: Proper installation requires matching "R" (right-hand) and "L" (left-hand) marks at module junctions to ensure the continuous alternating rotation of elements necessary for process efficiency.
• Injection Proximity: For optimal dispersion, components should be injected as close to the first mixing element as possible, typically within one to two pipe diameters.
• Velocity Ratios: Effective mixing is highly dependent on the velocity of the sidestream relative to the mainstream, with specific ratios (ranging from 1.4 X to 2.5 X) assigned based on the viscosity and flow rate proportions of the materials.
• Metering and Flow Control: Because these units operate as plug flow devices with almost no back-mixing, precise manual or automatic metering is essential to prevent product non-uniformity caused by surging or pulsations.
• Injection Header Design: When using multi-point injection, the inclusion of orifice plates is necessary to create a controlled pressure drop, ensuring an even distribution of the minor component across all ports.