Trace metals are usually inevitably contained in wastes, coals and so forth. When the wastes and/or coals are burnt, pollutants like NOx, SOx, soot, particulates, dioxins and heavy metal compounds are emitted from the furnaces. Some of the heavy trace metal compounds condense on the particle surface and/or form fine particulates during the combustion/incineration processes. Owing to the difficulties in capturing those fine particulates by means of conventional dust collection systems, those particulates tend to be exhausted into the atmosphere. In this study, fundamental behavior of the vaporization of Pb, Cd and Cr compounds was studied at relatively low temperature. In this experiment the effects of temperature and reaction atmosphere on the vaporization behavior of Pb, Cd and Cr compounds were studied using a thermobalance. The chemical thermoequilibrium calculation for each compound was also carried out in order to validate the experimental results obtained. As a result, the vaporization behavior of the metal compounds appears dependent on their respective melting points. Most of chlorides were easily vaporized at relatively low temperatures. This suggests that the presence of HCl enhances the vaporization of metal compounds, while coexistence of SO2 shows inhibition of the vaporization tendencies of Pb and Cd compounds. All of the Cd compounds vaporized in the reducing conditions. The results of chemical thermoequilibrium calculation agreed closely with the experimental results obtained.
In this paper, we designed biomass gasification cogeneration plant in a sawmill. The sawmill in K town in Ehime prefecture was selected as the model plant. The biomass material used as the fuel is cedar (scrap wood). The plant consists of a fluidized-bed gasifier and a gas engine. These components produce steam, hot water and electricity. The net electricity and steam power from the plant are 2, 000kW and 7, 492 MJ/h respectively. The fuel of gas engine is mixture of low calorific biogas and LPG. The condition of steam by recovering from a heat recovery boiler and a exhaust boiler is 0.9MPa and 175°C. The net efficiency of this system was 41.6%-LHV. In addition, the basic data on the performance of the gasifier were obtained from the two experiments concerning the pyrolysis of wood and the gasification of Char. Using the basic data of both experiments, the efficiency of the gasification was calculated. From the results of energy demand, especially electricity and heat, the biomass of 10, 512 t/year and LPG of 593t/year are consumed. Furthermore, the CO2 emission of 3, 468 t-CO2/year and the weight of final disposal of 8, 857 t/year are reduced compared with conventional case (non-biomass energy system).
In order to evaluate metal materials for a methanol-mediated extraction process, an electrochemical corrosion tests and an immersion corrosion tests of carbon steel (SS400) and stainless steels (SUS304 and SUS316L) were performed using a phenol-containing methanol-water solution recovered from a methanol-mediated extraction of naphtha fraction of Tanito Harum coal liquid. In Both tests, the corrosion rates were 0.1-0.5mm/y on SS400, and less than 0.01mm/y on both SUS304 and SUS316L. From those results, it could be concluded that SUS304 and SUS316L are available for the plant materials, except SS400.