In order to develop a small-scale gasifier in which biomass can be converted to energy with high efficiency, we planed a gasification process that consists of two parts: pyrolysis part (rotary kiln) and gasification part (downdraft gasifier). We performed fundamental experiments on gasification part and discussed the apropriate conditions such as air supply location, air ratio, air temperature and hearth load. The following results was found: 1) the air supply into the char bed is more effective than that into the gas phase, 2) we can have the maximum cold gas efficiency of 80% on the following conditions: air supply location: char layer, air temperature: 20°C, air ratio: 0.2. 3) As air temperature is higher, the cold gas efficiency is larger. As for the hearth load, the cold gas efficiency becomes higher and reaches the constant level. It is expected from the results that high temperature in the char layer is effective on the char gasification.
From a viewpoint of environmental preservation and resource protection, the recycling of wastes has been promoting. Expectations to new energy resource are growing by decrease of fossil fuel. Biomass is one of new energies for prevent global warning. This study is an attempt to burn biomass lamps made from residues in order to thermally recycle waste products of drink industries. The pyrolytic properties of shochu dregs and used tea leaves were observed by thermo-gravimertic analysis (TG) to obtained fundamental data of drink waste pyrolysis. It observed that shochu dregs pyrolyze under lower temperature than used tea leaves. These wastes were compressed by hot press apparatus in the temperature range from 140 to 180 °C for use as Bio-fuel (BF). The combustion behavior of BF was observed in fall-type electric furnace, where video-recording was carried out at sequential steps, such as ignition, visible envelope flame combustion and char combustion to obtain combustion characteristics such as ignition delay, visible flame combustion time and char combustion time.
A new type of sewage sludge incinerator, which combines a pressurized fluidized bed combustor and a turbocharger driven by flue gas, was proposed. We constructed a demonstration plant (4.32 t/d scale) at a sewage works in Oshamanbe Cho in Hokkaido. The objectives of this study were combustion characteristics of de-watered sludge in this plant. Additionally, the characteristics between our new plant and a conventional one were compared using the experimental results. As the results, CO NOx, and N2O emissions were SUBstantially reduced by the pressurization. N2O emission could be controlled by the freeboard temperature in spite of the high nitrogen content of the fuel and the pressurized conditions. In particular, N2O emission of the new plant was less half of that of the conventional plant. It is thought that N2O was decomposed at a local high temperature place in the freeboard. This phenomenon was verified qualitatively by investigating the chemical reaction rates. Therefore, our new fluidized bed incinerator with the turbocharger had a low environmental impact.
Recently, development of energy transfer technology based on woody biomass remarkably has been forwarding accompanied biomass boom for gasification and liquefaction. To elevate on yield of energy into biomass for transportation and exergy is extremely important for essential utilization and production of bio-fuels. Because, conversion to bio-fuel must be discussion in detail thermo-decomposition characteristics for biomass main composition formed on cellulose and hemicelluloses, lignin. In this research, we analyze thermo-decomposition characteristics of each biomass main composition on both active (air) and passive (N2) atmosphere. Especially, we suggest predict model of gasification based on change of atomic carbon ratio with thermo-decomposition. 1) Even if it heat-treats cedar chip by 473K, loss of energy hardly produces it. From this, it acquired that the substance contributed to weight reduction was a low ingredient of energy value. 2) If cedar chip is heated in the 473K around, it can be predicted that the substance with a low energy value like water or acetic acid has arisen by thermal decomposition. It suggested that the transportation performance of the biomass improved by choosing and eliminating these. 3) Each ingredient of hydrogen, nitrogen, and oxygen which dissipated in the gasification process acquired that it was direct proportion to the carbonaceous dissipation rate. 4) The action at the time of thermo-decomposition of (the carbon, hydrogen, nitrogen, oxygen which are) the main constituent factors of the biomass suggested a possibility of being predicted by a statistical method.
Global environment problems have become more and more serious in recent years, and reduction of greenhouse gas emission based on Kyoto Protocol adopted at the 3rd conference of the parties of the United nations Framework Convention on Climate Change (COP3); securement of primary energy source and development of clean and renewable energy sources have been pressingly needed in consideration of the predicted depletion of fossil fuel in the future. In this study, we explore the use of a solidified biomass-derived fuel, having the maximum compressive strength of 100MPa and calorific value of 21MJ/kg, in iron-casting or iron-making processes as an alternative fuel to be mixed with coal coke. This study, carried out for internal observation using a quick-freeze technique, observed an actual working cupola furnace under the 20% alternative coal coke operation condition. After quick freeze of the cupola furnace, the solidified biomass fuel was found to inhabit near the iron-melting zone. Especially, this solidified biomass fuel smoothly changes carbonized fuel through high-density state during the operating process. On the other hand, this study tried to simulate gasification combustion under a high temperature environment instead of actual internal combustion of solidified biomass fuel. These combustion mechanisms were confirmed to be similar to diffusion-flame phenomena in general.
Bio-cokes, developed by Kinki University (domestic patent No. 4089933), can utilize unused biomass and be used as a coalcoke substitute in large-scale industrial processes such as foundry cupola furnaces. Bio-cokes are expected to serve as a technology corresponding to (1) reduction in the amount of the CO2 generation for the global warming prevention; and (2) rise of the price of coal coke. In preliminary tests conducted at Kinki University, it was confirmed that Bio-cokes could be manufactured from various raw materials such as used tea leaves, wood waste, etc. This paper reports our current effort to optimize manufacturing conditions of a mass-production facility of Bio-cokes. This study confirms the pressured solidification characteristics of biomass (using tea scum as the raw material) with varied parameters such as heat process temperature, smashed size, pressure, and initial water content. Thermal analysis of the material explains why the manufacturing process does not change material weight when setting the heat process temperature at 180°C . The optimum pressure for effectively obtaining a high specific gravity is constantly around 20MPa in spite of different smashed material sizes. There is the optimum initial water content to achieve the highest specific gravity, which is very close to the value based on the true-densiy.