A large distillery in Kentucky had been working with Kurita America for approximately eight months and was producing about 8.7 million proof gallons of distilled spirits annually.
Fouling is expected in a distillery due to the high mineral content of a plant’s water supply. This particular distillery was facing fouling in its evaporators because of high concentrated mash solids and high temperatures in the evaporators, which caused the dry house to shut down every seven to 10 days to for clean-in-place (CIP) to take place.
A dry house is a distillery’s name for the building that contains centrifuges, evaporators, dryers and the dried distillers grains (DDGS) loadout system. The plant would have to increase steam load and decrease rates in order to maintain efficiency, which is done to keep the syrup solids at a high enough level to efficiently run the dryers. This is common if evaporators are fouled. Shutting down the dry house over this extended CIP period of 12 to 18 hours would require slowing/shutting down the cook and distillation areas, where the mash and yeast are mixed to create the alcohol mixture and then where the alcohol is separated from the mash. This creates a significant loss in overall plant production. The inefficiency of the CIP and shutting down the distillation areas could be up to a loss of 19,400 proof gallons per day during a CIP event.
Discussions with plant personnel about industry- and facility-specific distributed control systems (DCS) trend reviews and visual inspections of evaporators during downtime confirmed that 10 to 20 percent more steam was needed to maintain heat transfer efficiency even as plant load through the evaporators was reduced. Visual inspection of the four evaporators showed some organic fouling due to higher steam loads in evaporators one through three and a layer of egg-shell thickness calcium oxalate fouling in the fourth evaporator. Calcium oxalate prevents the effective heat transfer between products in the evaporators, which causes excess steam usage, loss in syrup solids and more energy consumption.
Additionally, once calcium oxalate hardens, it is difficult to remove. Kurita America sampled the material from the evaporators, specifically the tube walls and evaporator flash chamber, and completed the testing of loss on ignition (LOI), which showcases how much material is organic; X-ray diffraction (XRD), which identifies the major crystalline phase — the calcium oxalate in the distillery case; and X-ray fluorescence (XRF), which identifies individual elements. Testing determined that approximately 35 percent of the material in the final evaporator was organic, and the remaining material was identified as calcium oxalate. Higher organic fouling is easier to clean than mineral fouling, thus higher mineral fouling uses more energy to maintain operating targets. The latter will be less efficient with CIP time.
Due to a very thick layer of calcium oxalate that added 10 to 20 percent to energy costs, Kurita America recommended that the evaporator should be hydro blasted prior to using any other form of treatment for cleaning and inhibition. Kurita America also recommended that all future CIPs utilize Kurita America’s ProClean 815 scale and deposit cleaner with caustic CIPs. The distillery was unable to use acid-based cleaning as ProClean 815 effectively softens and remove mineral scale deposits. ProClean 815 has been used since May of 2019, and the facility has extended its time between CIP events while maintaining evaporator efficiency.
The plant is seeing significant improvement in evaporator cleanliness and steam load and efficiency from five to 10 percent with the usage of ProClean 815.The plant has currently been able to extend time between CIP events from seven to ten days to three weeks by utilizing Kurita’s CIP program.
Kurita America’s CIP program contains a routine schedule that utilizes ProClean 815 at recommended doses and visual inspections after each CIP and verified with a borescope. This has helped the distillery to produce an extra 500,000 proof gallons per year due to the reduction in CIP days.
The facility has been able to maintain steam valve position and expected flow rates through evaporators during the three-week period. Additionally, the distillery reduced their water use for CIP events by 25 percent, which will save both steam costs and reduce required chemicals by 25 percent. Kurita America is working with the plant to identify automation improvements to reduce physical handling of chemicals during the CIP process and improve safety for employees.
Kurita America continues to work with the Kentucky distillery to extend runtimes between CIP events with a scale inhibitor trial and the monitoring of the plant’s trend reviews and physical inspections to verify the prolonged runtimes. Together, the plant and Kurita America are working toward a clean facility with improved safety, water usage, energy efficiency and cleanliness.
Jason Waddell is a field technical manager at Kurita America. He has nearly 10 years of experience as an operations manager for a Midwest ethanol producer. Jason has also worked as a supervisor and trainer for a Midwest ethanol plant and is a proud US Navy veteran. He is focused in Midwest in the United States with experience in the biofuels and food and beverage industries.