Through the methanol steam reforming (MSR), the energy of low temperature waste heat (100-150°C) can be recovered into that of hydrogen. However, actual MSR requires over 200°C to enable the high conversion of methanol into hydrogen in terms of reaction kinetics. Thus, in this research, a waste heat recovery system through MSR with absorption heat pump (AHP) was proposed. The role of the AHP is to enhance the temperature level of the waste steam up to 230°C, which is used for the MSR. The endothermic reaction of the MSR decreases the temperature of the MSR reactor. Therefore, high temperature steam should be used not only for the MSR reaction but also for heating the MSR reactor. To evaluate the performances of the system, "enthalpy enhancement factor" was defined. As a result, the recovered enthalpy of the waste heat was almost 4.5 times as much as the required work for the AHP when the waste heat temperature was 150°C and S/C ratio was 4.0.
The biodiesel has attracted attention as an alternative fossil fuel. Generally, the biodiesel is fatty acid methyl esters obtained from triglycerides which are the principal ingredients of oils and fats. The plantation vegetables of biodiesel raw materials are grown in Europe and America. On the other hand, it is necessary to use waste cooking oils in Japan where the cultivated acreage is narrow. The flee fatty acids are included in waste cooking oils decrease the biodiesel yield. Moreover, the long chain saturated compounds of animal fats in waste cooking oils lower the low temperature property of the obtained biodiesel. The pyrolysis of waste cooking oils was examined in order to apply to the manufacturing method of the biodiesel. As the results, it was cleared that the triglyceride generates the fatty acids by the ester bond decomposition at 360-390°C. Next, the fatty acids decompose and the short chain hydrocarbon is generated. Moreover, the hydrocarbon of the light oil fraction is obtained by the decarboxylation of the hydrocarbon at 420°C. At this time, the yield and the selectivity of the light oil fraction can be improved when the activated carbon supported palladium is added as a catalyst. The obtained light oil fractions had a good low temperature property.
The rheological characterisitcs of biomass slurry was determined from the pressure drop under high temperature and high pressure, using chicken manure. The dependence of the pressure drop on the flow rate was used to distinguish laminar and turbulent flow. The n-th order model was employed, and parameters in the model were determined to reproduce the experimental results. Surprisingly, the flow was well expressed with the Newtonian model where n=1, which contradicts with the previous study using the rotating viscometer. The difference in the sheer rate is expected to be the cause of this difference. The apparent viscosity reduced with temperature rise, and agrees with that of water above 300 °C for the slurry employed here. The methodology employed here is simple, and can be employed to determine the rheological characteristics of various slurries.
Initially, NiMo catalyst supported on amorphous silica-alumina (ASA) was used in the hydrocracking of wax, which was produced from biomass using Fischer Tropsch Synthesis (FTS) from biomass. The hydrocracking process was carried out in a 50 cm3 autoclave at 400 °C and 5 MPa (initial hydrogen pressure). The hydrocracking of hexatriacontane (HTC) over NiMo/ASA catalyst produced diesel oil with 59.5 wt % yield, which is higher than the yield obtained from the hydrocracking of biomass FT wax (36.7 wt %). To achieve the highest reactant activity, the ratio of the promoter Ni to the precursor Mo was maintained at 0.3. To determine how the reactant, such as HTC and FT wax, and the pressure condition affect hydrocracking, we carried out the hydrocracking of blending wax and palm oil (PO) using the semi-batch system. However, HTC was not converted through hydrocracking of a mixture of HTC and PO over NiMo/ASA at 5 MPa and 400 °C. HTC was converted when the promoter was changed from Ni to Pt; this proved that HTC can be converted to diesel and gasoline fraction.
In this research, the experiment of converting Japanese municipal solid waste (MSW) into chlorine-free solid fuel using the combination of hydrothermal process and water-washing has been performed. It was shown that after the hydrothermal process, the organic chlorine in the product was reduced and converted into water-soluble inorganic chlorine by the dehydrochlorination effect and the reaction with the alkaline content in MSW. Water-washing experiments were then conducted to identify the influencing parameters of chlorine removal by the washing process to obtain chlorine-free products. The results showed that up to 96 % of inorganic chlorine can be removed only by one-time washing, and the water to product ratio of 1:1 was sufficient to obtain a product with less than 3,000 ppm total chlorine content when the washed water was reused in the washing process. Furthermore, a mass balance calculation of the hydrothermal treatment system and the product characteristics have been performed.
Radioactive species such as 137Cs were discharged from Fukushima Daiichi Nuclear Power Plant which was severely damaged by the enormous earthquake and tsunami. Cropland has been radioactively contaminated by 137Cs etc. and it seems impossible to plant rice due to the non-suitability for food. According to the reports, 137Cs transferred into the rice from soil is less than 1% on the average. Therefore, it is expected that the concentration of 137Cs in bioethanol will be well below the tentative restriction value even if bioethanol could be produced from the rice. It is proposed that the rice field should be filled with water to avoid the flow of runoff contaminated by radioactive cesium compounds because they are insoluble in aqueous phase and that bioethanol should be produced from the rice in order to maintain the multifunction of rice field and to continue the agriculture. If rice farming is halted and neglected, agricultural function of rice field as well as local community will be permanently destroyed.