Often, ethanol plants are challenged with mineral deposits ― and the loss of heat transfer efficiency in distillation that accompanies these deposits. Deposit control technology from U.S. Water Services, St. Michael, Minn., can help plants reduce mineral deposits that cause fouling issues in evaporator systems and beer mash exchangers, eliminating sulfuric acid as a mineral deposit control aid.

An ethanol plant in the Midwest had been using an average of 522 lb of sulfuric acid per day to keep the evaporator system running at optimal production. The evaporator system was becoming less efficient due to mineral deposit scale. Sulfuric acid was used twice daily to maintain steam usage. The high usage rate of sulfuric acid was driving input costs higher and was leaving residual sulfur in the co-product.

U.S. Water’s mineral control product was trialed in the plant to determine its ability to control mineral deposit scaling and help reduce the amount of sulfuric acid that was being used on a daily basis. After determining an optimal dosage rate, the acid-to-evaporation was reduced in a step-wise fashion and then eliminated completely. The deposit-control technology also helped the plant reduce the amount of steam that was used in the evaporation system by 5,300 lb/hr.

Once online, the plant was able to see added benefits in beer feed temperature control. Prior to the introduction of mineral deposits control product, workers typically switched and cleaned the mash trains every six to eight hours. Upon the start of the trial, the plant was able to reduce the clean-in-process routine to every 16 hours. The average beer feed temperature before the use of the product was 140°F (60°C). The beer feed temperature now averages 146°F (63°C), a significant improvement in heat transfer efficiency.