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

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 CH4, 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/m3 at reactor temperature of 850°C. Specific gas yield increased from 0.32 to 0.58 m3/kgbiomass 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)

Experimental Investigation of Solid Fuel Combustion Process in a Hybrid Porous Reactor

One of the most significant human-made methane emission sources is the MSW （municipal solid waste）, deposited on sanitary landfills and open dumps. Within this work, an alternative MSW treatment concept is presented, which could provide a relatively clean waste/biomass-to-energy transformation. The proposed procedure comprises of a combustion and a gasification （or pyrolysis） step, which are consecutively taking place in a two-stage hybrid porous reactor system. The core of the system is two packed bed reactors, in which solid fuel （waste or biomass） is mixed with inert ceramic particles of similar size. This paper overviews the initial experimental investigation of the combustion step of a hybrid mixture, composed of wood pellets （fuel） and alumina balls （inert ceramic particles） in a 250 ram-high batch reactor. The temperature profile along the reactor, the concentration of CO and the flame front propagation velocity were measured as a function of the ceramic particle size （11 and 20 mrn）, the inert-to-fuel mass ratio （0：1, 2：1, 3：1） and the airflow rate （30, 42, 60 1/min）. Experiments indicate that an increase of the mass ratio of inert-to-fuel material and a decrease of the inert ceramic particles size lead to a decrease of the maximum temperature of the packed hybrid bed. Measured CO concentrations showed strong dependence on the inert ceramic particle size, i.e. the particle size reduction from 20 to 11 mm resulted in a significant reduction of CO-emission peaks. The maximum flame front propagation velocity of 0.2 mm/sec was detected for the airflow of 42 1/min, the particle size of 20 mm and the mass ratio of 3：1.