Thursday, March 15, 2018

Regenerative Turbine Chemical Pumps

regenerative pump for chemical applications
Regenerative turbine pump for chemical applications
Image courtesy Roth Pump Company
A regenerative turbine pump is significantly different from a centrifugal pump in the way in which liquid moves through the impeller section, making the turbine pump a better performer in a number of industrial applications.

A centrifugal impeller basically traps some liquid at the inlet and rapidly slings through the discharge port. The liquid velocity is increased by the impeller and manifests as outlet pressure. A key distinction between centrifugal and regenerative turbine pumps is that the liquid enters and exits the impeller only one time in a centrifugal pump. A regenerative turbine pump has an impeller with a larger number of smaller, specially shaped vanes. The shape imparts a circulatory movement of the liquid from the vanes to the casing, and back to the vanes. Each return to the vane section increases fluid velocity, resulting in increased pressure. As the impeller rotates, liquid enters, leaves, then re-enters the vane section many times. This process is called regeneration. The impact of this design is a pump that can deliver substantially greater pressure than a centrifugal pump with the same impeller diameter and rotational speed.

A regenerative turbine pump is capable of pumping fluids with up to forty percent entrained gases without damage from cavitation or any performance loss. Fluid conditions with even low levels of entrained gases are generally not recommended for centrifugal pumps because of the degradation in performance, evidenced as fluctuating discharge pressure and excessive wear and vibration. Where cavitation is a concern, the regenerative turbine pump holds the advantage over centrifugal. Applications with low flow and high head requirements will also be better serviced by a regenerative turbine pump.

For chemical applications, assuring compatibility between the casing, turbine, and seal materials is an important step. Performance curves for the various pump models can be used to match a pump and motor combination to the application. Share your fluid transfer requirements and challenges with experts, and leverage your own knowledge and experience with their product application expertise to develop an effective solution.