Combustion properties of coal gasification gas with CO2 dilution were investigated for a newly proposed IGCC power generation system with CO2 capture. In this system, the gasification gas is burned under high CO2 concentration atmosphere. In order to clarify the combustion properties of the gasification gas under such atmosphere, the laminar and turbulent burning velocities were investigated for outwardly propagating stoichiometric H2/O2/CO2 flames at the mixture pressures of 0.10 to 0.50MPa, comparing them with those of H2/O2/N2 flames. The unstretched laminar burning velocities of H2/O2/CO2 flames were smaller than those of H2/O2/N2 flames. The ratios of the turbulent burning velocity at the flame radius 30mm, utn(30mm) to the unstretched laminar burning velocity were found to be larger than those of H2/O2/N2 flames at the same turbulence intensity. Increase in the turbulence Karlovitz number and decrease in the Lewis number by the CO2 dilution might cause the increase in the ratio of the turbulent burning velocity to unstretched laminar one of H2/O2/CO2 flames.
In the procedure of the life cycle assessment complying with ISO 14000 series, impact assessment is required. For the integrated assessment of impacts, evaluation with economical values is frequently applied. Evaluating impacts of damages on human health, it is converted to economical value using method of environmental economics. One of the ways to determine the rates of conversion is to presume residents' willingness to pay to avoid the damages. These rates are estimated by analyzing data observed through social survey, but knowledge of the conversion rates in developing countries is not sufficient. We launched a social survey in Shanghai to analyze willingness to pay to decrease risks contracting asthma caused by air pollution. Five hundred subjects were sampled by multistage area sampling. Subjects were sampled from all of the districts of Shanghai. They were asked their willingness to purchase an air purifier to reduce risks to contact asthma with presented prices for the analysis of contingent valuation method, as well as their profiles. The answers were analyzed by fitting log-logistic distributions and factors that influence the willingness were examined.
It is planned to increase plant biomass feedstock to sustain the renewable energy source, bioenergy. In cool regions such as Hokkaido which often offers a short and stressful growth season, less is known about biomass potential (BP) in plants, and generally there is a lack of data regarding a regional suitable harvesting system in feedstock. A constant supply of feedstock per month using several biomass plants would be important for establishing an all year round operating system (AYROS) in biofuel production. Two types of perennial lignocellulosic crops, four C3 grasses which adapt well to cool environments, orchardgrass (OG), reed canarygrass (RC), tall fescue (TF) and timothy (TI), referred to as cool season grasses (CSG) and C4 native grass, Miscanthus sinensis called 'susuki', were evaluated for the BP in Sapporo, Japan. CSG were sown into fertilized land in 2006, whilst M. sinensis was planted in 2007 without fertilization. Three years after planting, in 2009, regional potential across all harvesting of CSG was 9.7 t ha-1 year-1. Different harvestings of CSG revealed high BP from RC and TI rather than OG and TF. RC showed BP peaks twice, in June (11±0.45 t ha-1 year-1) and September (15±1.11 t ha-1 year-1), and a single peak in July (15±1.99 t ha-1 year-1) for TI, indicating that RC is a two peaks type, whilst TI falls into a one peak type. For M. sinensis, the BP increased with the year and varied among accessions. In 2009, regional potential was 1,287±343 g plant-1 year-1. Accessions native to Hokkaido showed maximum BP of 827±353 g plant-1 year-1, mainly from Matsumae (1,622±692 g plant-1 year-1) and Toyoura (2,174±169 g plant-1 year-1). Accessions native to areas other than Hokkaido yielded a potential of 2,206±388 g plant-1 year-1, mainly from Shiozuka (2,531±526 g plant-1 year-1) and Akeno (2,653±635 g plant-1 year-1), substantially higher than the BP of Hokkaido accessions. The BP of M. sinensis over two years of 9 accessions in the present study was about 36.9 t ha-1 year-1, by converting biomass data of plant (921.4 g plant-1 year-1) to land area unit. The BP experiment estimates biomass feedstock is supplied with 10-15 t ha-1 by harvesting TI and RC in June to September and 30 t ha-1 by harvesting M. sinensis in October. This study demonstrated the feasibility and advantage of the combination of CSG and M. sinensis. The BP could be improved using mostly superior genotypes of M. sinensis selected from areas other than Hokkaido. The information from the present study will be available for establishing AYROS in feedstock production for biofuels such as bioethanol in cool regions such as Hokkaido.
Activated carbons were prepared from woody pellets, which were mixed with several percentages of waste bark and wood of typical conifer trees. Specific surface areas of activated carbons from several percentages of waste bark were measured in yields between 9-17%. Specific surface areas of activated carbons of 0wt% bark (100wt% wood) and 100wt% bark (0wt% wood) were 900-1,200m2/g and 740-780m2/g, respectively. Waste bark seemed to be inferior to wood as a precursor of activated carbon. However, specific surface area of 25wt% bark (75wt% wood) was 1,230-1,430m2/g, and it was the largest, even though mixed with bark. X-ray fluorescence of the ashes which were prepared from waste bark were measured, and calcium was detected as a main element, whose content was over 70wt%. Raw materials, char and activated carbons were analyzed by X-ray powder diffraction measurement. Calcium oxalate was detected in raw materials, and calcium carbonate and calcium oxide were detected in char and activated carbons, respectively, which were produced by pyrolysis from precursor during carbonization process and activation process. During activation, calcium carbonate, which was in char, was decomposed to calcium oxide and carbon dioxide, and it seems they participated in development of specific surface area of activated carbons mixed with bark. Adsorption performances of activated carbon of 25wt% bark for toluene, isopropyl alcohol and acetaldehyde were compared with those of the coconut shell based activated carbon, and revealed to be better than them.