Abengoa - Rotterdam, NL

Project Background

HPD's stillage evaporation system from Abengoa's Rotterdam, Netherlands production facility features the EHSC, high-solids concentration technology

Stillage Concentration | Feedstock Flexibility

Prior to construction, Abengoa planned to produce 360,000 tons annually of Distillers Dry Grains with Solubles (DDGS) from this facility that could be sold as animal feed. Wheat would be the primary feedstock, but the facility desired to have the flexibility to use corn depending on market conditions and availability.

Corn, and especially wheat, present a challenge for conventional methods of water removal from thin stillage to produce DDGS. The viscosity of the stillage dramatically increases as the concentration factor becomes higher. Falling film evaporators, normally used for initial concentration of the stillage prior to final drying, experience issues when reaching 20-30% total solids (TS). This results in fouling of the heat transfer surfaces with subsequent plugging, frequent cleanings, and system down time.

Abengoa contacted HPD to discuss alternative process designs that would be a reliable solution to the issues associated with water removal from thin stillage. HPD has several successful evaporator installations in biofuels production facilities in North America and Europe.

HPD Stillage Concentration Technology

The EHSC System allows higher concentrations of stillage with reduced power consumption and scaling

Though falling film evaporators are an efficient method to remove water, they experience difficulties when they approach higher concentrations due to the viscosity of the syrup, especially with wheat feedstock. In order to overcome this issue, HPD designed the process to operate the falling-film evaporators at a much lower concentration to prevent fouling.

HPD proposed the use of proprietary Enhanced High Solids Concentration (EHSC) evaporation technology following the falling film evaporators in order to manage the viscosity and reduce potential fouling of heat transfer surfaces. This would not only provide stable system operation and availability, but also achieve a higher than normal concentration of 35% TS of the syrup that was desired by Abengoa.

The EHSC system design promotes turbulence of the concentrated syrup to minimize scaling of the heat transfer surfaces and consume much less power than standard, forced circulation evaporators. This technology is a proven method of processing highly viscous process streams and has been successfully operated in several biofuel plants in the United States and Europe that use both wheat and corn as feedstock.

Pilot Testing to Confirm Process Design

EHSC evaporator pilot unit

In order to confirm the design parameters for Abengoa's Rotterdam facility, HPD conducted a series of tests that included both analytical data and on-site pilot testing using worst-case conditions. The feedstock of corn and sorghum stillage was provided from Abengoa's facility in Galicia, Spain. These results would then be compared to previous tests using wheat stillage.

Pilot testing over several days on both corn and sorghum revealed that HPD's EHSC technology could consistently process the stillage up to 45% TS with stable operation with no fouling or scaling of tube surfaces.

Based on this data, it was concluded that the system would have no problems with the specified concentration of 35% TS that would be normal operating conditions for both wheat and corn feedstock.

Website: www.hpdsystems.com