Process optimization of a closed-chamber distillation system for the recovery of FLiNaK molten salt

Low-pressure distillation has been proposed as a suitable technique for the recovery of carrier salt from molten salt reactor spent fuel.A closed-chamber distillation system,in which the pump is stopped and pressureinduced salt distillation is performed,was arranged for fluoride salt treatment.A stair-step optimization process was demonstrated to improve the recovery efficiency by up to 99%.The pressure change curve was feasible for estimating the distillation process,and a method for displaying the pressure value online in order to determine the endpoint was also developed.The decontamination factor of Nd in the condensate salt was deduced to be greater than 100 with 1 wt%NdF3–FLiNaK distillation.The optimal conditions developed in this study showed a high recovery ratio for the fluoride carrier salt and a high separation efficiency for rare earth products.

Effects of Heating Temperature and Moisture on Indirect Gasification of Rubber Wood in Closed Gasifier Chamber

Rural area in Indonesia of which electrification ratio is still low has a strong demand for off-grid electric power supply. On the other hand, Indonesia is a leading natural rubber production country and these rubber wood trees are cultivated in vast plantation farms. A rubber wood tree is woody biomass resource which can be stably supplied because a lot of trees aged more than 25 years are logged and nursery trees are planted constantly. Woody biomass is burned directly as solid fuel and the generated thermal energy can be applied only for room heating or cooking. Otherwise, direct conversion of biomass to electric energy requires a large scale equipment such as a boiler and a steam turbine, whereas gasified woody biomass can be easily handled and can have wide application. A closed gasifier chamber which was kept vacuum and fulfilled with gas yield during gasification was recently developed by the authors for indirect gasification. It was confirmed that generated gas by the gasifier is clean and can be directly used to drive an engine generator to supply electricity. In this study, planer dust of rubber wood is used as gasification feedstock for indirect gasifying in the closed gasifier chamber, and effects of heating temperature and moisture content on gasification performance are discussed to examine characteristics of the closed gasifier chamber in details.

Effect of linear alkyl benzene sulfonates (LAS)on the fate of phenanthrene in a model ecosystem (water-lava-plant-air)

Advanced closed chamber system was used to study the fate of phenanthrene (3 rings PAHs) in the presence of linear alkylbenzene sulphonates(LAS). The results showed mineralization and metabolism of phenanthrene are fast in the “culture solution lava plant air' model ecological system. The distribution proportions of applied 14 C activity in this simulative ecological system were 41%—45%, 14% to 10% and 1% in plant, lava and culture solution respectively, and 18% to 29%, 11% to 8% recovered in the forms of VOCs and CO 2. Main parts of the applied 14 C activity exist in two forms, one is polar metabolites(25%) which mainly distribute in the root(23%), the other is unextractable part(23%) which have been constructed into plant root(8 98%), shoot(0 53%) or bonded to lava(13 2%). The main metabolites of phenanthrene were polar compounds(25% of applied 14 C activity), and small portion of 14 C activity was identified as non polar metabolites(6% of applied 14 C activity) and apparent phenanthrene(1 91% of applied 14 C activity). Phenanthrene and its metabolites can be taken up through plant roots and translocated to plant shoots. The presence of LAS significantly increased the the concentration of 14 C activity in the plant and production of VOCs, at the same time it decreased the phenanthrene level in the plant and the production of CO 2 at the concentration of 200 mg/L.

Carbon isotope fractionation during CH_4 transport in paddy fields

In this study,to further promote the application of the stable carbon isotope natural abundance(SCINA)method to the study of CH4in paddy fields in China,field experiments were carried out to investigate carbon isotope fractionation during CH4transport in both rice-and non-rice-growing seasons.More importantly,two new methods for the measurement of the CH4transport fractionation factor(εtransport)in paddy fields were introduced.The results indicated that the closed chamber+syringe method was much better for the determination ofεtransport during the non-rice-growing season.Presently,εtransport was calculated using theδ13C value of the CH4emitted from a rice field minus that of the CH4in the floodwater(–6.7‰to–3.0‰).In addition,there were three methods available for estimatingεtransport during the rice-growing season:deduction of theδ13C value of the CH4in the floodwater from that of the CH4emitted from the field(–16.6‰to–15.2‰);deduction of theδ13C value of the CH4in the soil pore water from that of the CH4emitted from the field(–13.2‰to–1.1‰);and deduction of theδ13C value of the CH4in the aerenchyma of plants from that of the CH4emitted from plants(–16.3‰to–10.9‰).Unfortunately,the first two methods showed relatively large uncertainties.Only the last one,the dividing+cutting method,was not only scientific and reliable but also provided accurate measurements.