Researchers from Iowa State University are working with Frontline BioEnergy to optimize a gasification process for the production of producer gas from biomass to replace the use of natural gas in ethanol plants.
Many ethanol plants use natural gas to produce the heat required to create the steam to liquefy corn starch, to distill alcohol, and to dry the leftover distillers grains.
Natural gas is thus the second largest expense at these plants, trailing only the cost of the corn used for ethanol production. One estimate says Iowa’s annual production of more than one billion gallons of ethanol accounts for about 16% of the state’s demand for natural gas.
Producer gas is made by injecting biomass—corn stalks, distillers grains, waste wood or other biorenewables—into a fluidized bed gasifier, a thermal system that pumps air up through a bed of hot sand, creating bubbles and a sand-air pseudo-fluid. A reaction between the biomass and the hot sand-air mixture produces flammable gases. The process also generates its own heat to sustain the reaction.
Producer gas is a mixture of hydrogen, carbon monoxide, methane and other flammable gases that can also be upgraded to syngas for further conversion to fuels or other chemicals.
The goal is to design a gasifier large enough to produce energy for an ethanol plant. The project is partially supported by a $132,274 grant from the Grow Iowa Values Fund, a state economic development program.
Iowa State will use X-ray radiography, X-ray computed tomography and X-ray stereography images of the flows within a 6-inch reactor to measure local conditions.
Researchers will then simulate the results of the X-ray tests using computational fluid dynamics and then run simulations and compare the results with data from the fluidized bed experiments. Ultimately the goal is to validate a computer model to enable appropriate design changes to optimize the delivery of the producer gas.