The authors proposes an innovative technology “Molten Salt Redox Combustion Energy System”, that includes the flameless combustion in molten salt. This system generates a high temperature without dis-charging pollutants coming from combustion of fuels. At the same time, it is possible to recover the pure carbon dioxide. This system characterized by coupling two redox reactions occurring at different places, separately. At one place, the oxidation of the redox couple by air proceeds, while at the other, the reduction reaction with fuels does. This system is ready for giving the following advantages. ·Pure carbon dioxide from the combustion of fuels can be recovered. ·Thermal NOx is not generated, because of relatively low temperature reactions. ·Sulfur, nitrogen and chlorine compounds in fuels are caught in molten salt as sulfates, nitrates and chlorides of alkali metals. ·The mix fuels of a variety of compositions can be applied. ·A few kinds of oxidation-reduction couples can provide the chemical heat pump effect. As the first step of developing this combustion system, the authors describe the theoretical concept and discusses it feasibility based on the chemical thermodynamics. The promising redox couples were found successfully.
A method for predicting the yields of products and the elemental composition of char during pyrolysis of biomass was presented. 10 kinds of biomass feedstocks with a focus on wood biomass were pyrolyzed at various temperatures using a Curie-Point Pyrolyzer attached to a gas chromatograph. At moderate tempera-ture not lower than 485°C, the yields of total volatiles linearly increased with the atomic ratio H/C which was also correlated with the lignin content in feedstock. Furthermore, it was clarified that the average elemental composition of total volatiles produced at these temperatures was equal to that of cellulose and that the tar fraction among volatiles consisted of glucosan or cellobiosan, the molecular weight of which was about 300. By combining these results, we developed a new chart for predicting the elemental composition of char pyrolyzed at moderate temperature only from the elemental analysis of feedstock. The presented method is expected to provide a useful guideline for the decision on pyrolysis condition or subsequent conversion such as gasification and combustion.
It is an environmental problem in the stadium where the sports event is held that a large amount of the paper cup is wasted along with sales of beverage such as beer and soft drinks. The returnable cup system has been carried out in Oita Big Eye for the reduction of waste and the effective use of resource. In this study, life cycle inventory of the returnable cup system in the stadium was analyzed, and the reduction effects of energy consumption and solid waste were investigated by comparing with the conventional bev-erage service using the paper cup. As a result, it was shown that the amount of environmental loads became smaller in the beverage service by the server. In addition, it was confirmed to be able to decrease the amount of environmental loads in the beverage service with the returnable cup by increasing the number of reuse. Changing to the bever-age service with the returnable cup from the paper cup could largely reduce several environmental loads in Oita Big Eye. It was suggested that the reduction rate of environmental loads in one game was larger by changing from the beverage service by the aluminum can or the PET bottle to the server.
The present study has been carried out to evaluate the performance of natural gas (13A) fired water heater with titanium heat exchanger for latent heat recovery. The latent heat recovery with condensation is very useful method to enhance the thermal efficiency of the water heater. However, it is usually accompa-nied with corrosion problem of heat exchanger caused by strong acid condensate that is formed due to the hazardous gases such as SOx or NOx. In this study, titanium heat exchanger was adopted as secondary heat exchanger because they have excellent corrosion resistance. The experiments were conducted for mass flow rate and inlet temperature of supplied water and setting temperature of hot water as parameters, respectively. Tube arrangements of heat exchanger including inline and staggered configurations were investigated. In the terms of thermal efficiency, the performance of the water heater was evaluated based on the net calorific value at maximum rated output. As a result, the thermal efficiency of gas fired water heater with latent heat recovery heat exchanger was approximately 10% higher than that of the conventional instantaneous water heater. In addition, it was found that the overall heat conductance of the heat ex-changer with staggered tube rows is more efficient than that of the inline tube rows.
“Methane hydrate/LNG hybrid-type power generation project” as a strategy for promoting methane hydrate development is proposed in this study. This project has the following advantages.(1) It will be profitable under the current electric power price (19yen/kWh) by expansion of power output and extension of operating life.(2) The risk from methane hydrate development can be reduced.(3) It enables to reduce the CO2 emission and production cost of the hot water injection method by using waste heat in the power plant. However, under the CO2 emission trading system, unit price of the dealings which enables this project to be more profitable than the coal-fired power plant is considerably high: 10, 000 yen/ton-CO2. In order to introduce this project to the electricity market, the other incentives such as preferential tax treatment for domestic energy resource development are also required.