Performance Assessment of an Allothermal Auger Gasification System for On-Farm Grain Drying

Abstract

Biomass gasification is a well-developed technology with the potential to convert agricultural residues to value-added products. The availability of on-farm gasifiers that can handle low-density agricultural wastes such as soybean residue, an underutilized feedstock, is limited. Therefore, the goal of this research was to install and assess an allothermal, externally heated, auger gasifier capable of converting agricultural wastes to combustible gas for on-farm grain drying. The system was used to convert soybean residues under different reactor temperature, i.e., 700˚C, 750˚C, 800˚C, and 850˚C. The results showed that increasing the reactor temperature from 700˚C to 850˚C increased the producer gas molar fractions of H2, CO, and CH 4 , from 1.1% to 1.5%, from 15.0% to 23.8%, and from 5.1% to 7.7%, respectively. The higher heating value of the producer gas reached 6.3 MJ/m 3 at reactor temperature of 850˚C. Specific gas yield increased from 0.32 to 0.58 m 3 /kg biomass while char and particulate yield decreased from 41.7% to 33.6% by increasing the reactor temperature from 700˚C to 850˚C. Maximum carbon sequestration achieved, in the form of biochar-carbon, was 32% of the raw feedstock carbon. Gasification of collectable soybean residues from 1 acre would be sufficient to dry 1132 kg of soybean seeds (the average yield from one acre) from moisture content of 20% to 13% (wet, weight basis). Furthermore, about 300 kg of biochar, a value-added soil conditioner, could be produced and applied to the soybean land as a bio-fertilizer.

Gasification of Phycoremediation Algal Biomass

“…By contrast, countercurrent (updraft) gasifiers have been reported to yield condensables in amounts ranging from 12.7% to 37.2% of fed biomass; these numbers varied according to the type of feedstock and the operational parameters (Di Blasi et al 1999). Earlier studies (Sadaka 2013;Sadaka et al 2014), which utilized the auger gasification platform used in the current study, reported yields of condensables that varied from 18% to 34%. The auger gasifier, therefore, could be considered an intermediate platform between downdraft (concurrent) and updraft (countercurrent) gasifiers in terms of the yield of condensables.…”