A performance evaluation was made in a U.S. Midwest dry grind fuel ethanol plant. U.S. Water's Ethanol Process Technologies (EPT) team applied a unique process deposit control technology, pHytOUT, for which three U.S. patents were awarded, including U.S. patent 8,039,244 awarded on October 18, 2011 for which there are no licensees.
Introduction & Identification of Opportunities
U.S. Water was requested to support production efficiency improvements by the plant management team. A number of opportunities for higher efficiencies and better quality were identified. Those identified were:
- Limited plant throughput due to slurry flow restriction
- Plant downtime for equipment cleaning-in-place
- Chemical cost
- Energy cost
- Co-product quality
Solution Identification & Implementation
The plant undertook an extended no-cost trial of the pHytOUT technology – with considerable data collection and review.
Results & Conclusion
Use of the pHytOUT technology enabled an increase in beer feed by 7% and associated >1.5 MM denatured gallons per year increase in production while lowering pressure drop across beer/mash exchanger demonstrated by the control valve position.
Manual cleaning was required to restore slurry flow every four to seven months which required shutting down the front-end for three hours and ten man-hours of effort during each event. Previous increasing trend in First Effect steam pressures arrested and reversed – even with higher rates.
51 days after introduction of pHytOUT technology, piping was opened and inspected. It appeared they have 99.9%+ open versus less than 90% open after previous manual cleaning.
Other results realized include:
- Earlier fermentation finish with less dependence on continued fermentation in beer well
- Sulfuric acid to beer feed discontinued – yet heat exchange improved
- Alleviated wear on mechanical components due to reduction in sulfuric acid use in exchanger train, distillation and evaporators. Maintenance time and potential hazards during repair of these components were reduced
- Sulfuric acid savings of 8,300 gallons per month. Improved safety from reduced acid handling
- Beer feed temp increased 7°F saving 2,600 MM BTU per month
- First Effect steam demand reduced by 2,000 – 2,500 pounds per hour
- Cook water rate increased by 22 gpm and temperature increased 5°F saving 1,970 MM BTU per month at 85% boiler efficiency
- Co-product sulfur (dry matter basis) reduced from ~0.6% to ~0.3%. Decrease of >1.5 million pounds per year in co-product sulfate (>450,000 pounds per year as sulfur)
- Annual technology application costs returned in 100 days