Hammermills and Flour Conveyance: Two hammermills were replaced with new mills that have a higher capacity. In addition, flour conveyors were added to improve conveyance reliability.
Liquefaction and Beer Feed Pumps: The mash flow rate presented a bottleneck in the plant due to the pump size and pressure drop across the beer and mash exchangers and beer preheaters. Space within the process building was limited, so larger beer and mash exchangers were not feasible. To achieve a higher mash rate, the liquefaction and beer pumps and associated piping were upsized, and booster pumps were installed following the mash exchangers.
Beer De-Gas: A centralized beer de-gassing system was added to improve distillation performance. Beer is sent to a new vacuum flash tank from the beerwell, and the CO2 vapors are sent to the CO2 scrubber. The system was designed to fit within the existing distillation footprint. Following the start-up of the de-gas system, distillation pressure dropped by 1-2 psi due to the reduced flow of non-condensables.
Syrup Mixer Addition: A two-step syrup mixing system was implemented in the plant’s side two dryer system. The new mixers help homogenize the wet cake and syrup, creating a friable dryer feed and reducing the risk of dough-balling. Additionally, the mixers enable the plant to increase the rate of syrup addition to the wet cake feed, decreasing the volume of syrup loaded out by truck.
Ethanol Storage Tank and Loadout Upgrades: A new 1-million-gallon ethanol storage tank was added to the existing tank farm to increase storage capacity. The new tank was equipped with an advanced tank monitoring system to improve inventory management. An ethanol loadout pump was added, and the loadout piping was replaced to increase loadout rate to 3,000 gallons per minute (GPM) with the ability to increase to 3,500 GPM in the future. A second truck loadout was also added with the ability to load out 200-proof ethanol and blends up to E-85.
Distillation Improvements: Golden Grain Energy was planning to debottleneck their distillation and dehydration systems. The molecular sieves were running at capacity, and the plant was steam limited. The existing distillation area did not have enough open space for additional equipment.
KFI conducted a study to evaluate the efficacy of a membrane style ethanol-water separation system. This system can take regeneration streams from the molecular sieves and 190-proof ethanol and dehydrate them to 200-proof ethanol in an area separate from distillation. A new motor control center room was added to accommodate this system and make space for future equipment. KFI supported the preliminary and detailed design, construction, start-up, and commissioning.
The system was commissioned and then expanded the following year, bringing the system capacity to 123,000 gallons per day and improving efficiency throughout the distillation, dehydration and evaporator system.
Heat Recovery Steam Generator Replacements: KFI provided process, mechanical, and structural engineering services to replace two heat recovery steam generators (HRSGs) and economizers that had reached the end of their life. Each HRSG is driven by waste heat from a thermal oxidizer. The economizers utilize additional waste heat to warm various process streams. As an added benefit, the improved efficiency of the new HRSGs and economizers reduced the plant’s natural gas consumption. Each HRSG and economizer was installed in alignment with the existing thermal oxidizer, exhaust stack, and induced draft fan. KFI collaborated closely with the HRSG manufacturer and the contractor to ensure both projects would be successful and completed within the plant’s annual outage.
Corn Storage and Receiving Expansion: KFI provided process, mechanical, and electrical engineering services for the addition of two 2.2-million-bushel grain bins. This project was completed in two stages. The first stage included a new corn receiving building, a new motor control center room, and the first bin, while the second stage included the construction of the second bin. Each corn bin is 165 feet in diameter and 155 feet tall, extending the plant’s corn storage capacity by months and providing the plant and local farmers with more flexibility. When the first 2.2-million-bushel bin was constructed, future considerations for a second bin were included, allowing for its completion in under nine months.
