PROBLEM
110 MGPY ethanol plant had been in operation for more than ten years. Over that period, the competitiveness among plants changed. Plants were bought out by “oil giants” and others formed buying co-operatives. This plant looked for a way to reduce operating costs. A large percentage of the natural gas was used to dry the “wet cake” into either modified DDGS or finished DDGS. The “wet cake” originates from a series of decanter centrifuges, many of which are designed using gear-driven back drives that are difficult to adjust for solids content variations. The limited control of a gear-driven centrifuge led to challenges in producing the desired levels of dryness for the final product going to the dryer.
The ethanol plant operation and maintenance team approached Centrisys/CNP, known for their expertise in decanter technology, to produce dryer solids, to improve process control and decrease the natural gas consumption for the dryers.
SOLUTION
Centrisys/CNP introduced the ROTODIFF® hydraulic backdrive as a more precise alternative to the traditional gear-driven decanter. Retrofitting one decanter to start produced promising results: a 1% increase in cake dryness, improved process control, a decrease in maintenance costs as compared to traditional methods and an overall reduction in natural gas usage at the plant. Based on the energy savings alone, a ROI of 9-12 months was estimated. Encouraged by these positive outcomes, the plant proceeded to retrofit all the remaining decanters with ROTODIFF hydraulic backdrive technology.