The operation of a 1 t-wet/d supercritical water gasification plant was evaluated for the gasification of barley shochu residues with activated carbon charges ranging from 0 to 0.05 kg/kg-slurry. Activated carbon concentrations greater than 0.025 kg/kg-slurry were found to prevent plugging by tarry residues. The pressure loss for the effluent that flowed in the annulus of the double-tube heat exchanger did not exceed 0.2 MPa. Long continuous operation times of 17 h 48 min were possible with an activated carbon charge of 0.025 kg/kg-slurry. Activated carbon is not only effective for prevention of plugging, but also effective for reduction in total organic carbon and enhancement of carbon gasification efficiency. An economic evaluation showed that the process can be viable when operated for more than 200 d per year.
A novel gasification process of waste plastics (WP) was investigated. The present paper shows principle of the gasification, especially role of a gasifying agent, experimental verification of effectiveness of the agent, and reaction scheme of the gasification. The gasifying agent of WP, that is most characteristic feature of this process, is a mixed gas mainly composed of CO2, H2, and H2O and easily produced by the water gas shift reaction of a by-product gas generated in steelmaking process. By fluidized-bed micro reactor experiments, lower heating value (LHV) of the gas produced by the gasification of low-density polyethylene (LDPE) and WP was 22.5 MJ/Nm3 and 19.3 MJ/Nm3, respectively, with 66% of gas yield for LDPE and 56% for WP at atmospheric pressure and 873K with a nickel powder catalyst diluted by silica sand. It was concluded that not only polyolefins but also other various polymers such as polyesters and elastomers were gasified based on polymer components included in WP and the gas yield of WP. The gasification reaction scheme was also discussed.
The purpose of this research is to design an optimum automotive bioethanol supply chain in Japan. In this research, a mixed integer linear programming (MILP) model provides the optimal design of bioethanol supply chain with the objective of minimizing the cost of supply chain. Furthermore, the model can optimize biomass species, cultivation and traffic volume of biomass, locations and scales of the bioethanol production plants and traffic volume of bioethanol. The transportation cost of feedstock and bioethanol are optimized using Geographic Information System (GIS). Optimized supply chain is evaluated bioethanol production cost, energy profit ratio (EPR) and CO2 reduction. Tohoku area was selected as a case study. The bioethanol production cost, which uses first generation bioethanol plant is 203 JPY/L, where first and second generation bioethanol plants are installed is 168 JPY/l, where first and second generation bioethanol plants are installed and technological development was considered is 92 JPY/L. EPR of each case are 1.66, 2.49 and 3.40, and CO2 reduction are 277 kt-C, 288 kt-C and 305 kt-C, respectively. It is necessary to decrease cultivation cost of energy crops and increase bulk density of crop residue to reduce the bioethanol production cost, increase EPR and CO2 reduction.
Beating or refining has been recently taken notice as a promising pretreatment method for enzymatic saccharification of wood pulp. Softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP) with varieties of freeness were prepared using Niagara beater to evaluate effectiveness and limitation of beating. The initial glucose yields by enzymatic hydrolysis of beaten pulps were compared. Beating promoted enzymatic saccharification. However, excess beating did not improve the glucose yield, indicating that it did not change the specific surface area accessible to cellulase. The pulp with smaller freeness suffered from dramatic decrease of glucose yield with higher pulp concentration. The result suggested that external fibrillation enhances fiber aggregation, which could limit cellulase accessibility. The glucose yields were different between NBKP and LBKP even with the same freeness. Enzymatic saccharification is also dependent on the type of plant fiber.