助熔剂对生物质灰熔点和半焦气化的影响分析

为了满足生物质气流床气化液态排渣的要求,研究了CaO与Fe2O3作为助熔剂对高灰熔点生物质的助熔效果,并考察了其对生物质半焦气化的影响.结果表明:当助熔剂CaO质量分数介于0.3～0.4之间时,稻壳灰熔点有明显的降低;当助熔剂Fe2O3质量分数在0～0.5之间并逐渐增大时.稻壳灰熔点急剧下降.CaO与Fe2O3在质量分数较低时对半焦气化都有一定的催化作用,能够提高碳转化速率,但是随着质量分数的增加,助熔剂附着在多孔半焦的表面,阻碍气化介质与半焦的接触,使气化效果下降.     

Application of char products improves urban soil quality

Urban soils are a key component of the urban ecosystem but little research has considered their quality and management. The use of char or partially combusted char products as a soil amendment is becoming popular worldwide because of perceived benefits to fertility and the potential for increasing carbon sequestration. In this study, we assessed the effect of applying coarse and fine char material on the quality of four different types of soil‐based root‐zone mixes typically used for turfgrass and general landscaping in Singapore: clay loam soil, approved soil mix (ASM, 3 soil:2 compost:1 sand), 50:50 (sand/soil) and 75:25 (sand/soil). Char briquettes made from sawdust were mixed thoroughly at rates of 25, 50 and 75% by volume with the soil mixes. Results showed that addition of char (both coarse and fine) significantly enhanced the carbon content of the mixes, with the largest increase being associated with the 50% and 75% additions. Soil nutrients (total N, extractable P, K, Ca and Mg) and mean weight diameter of aggregates were also significantly increased following the application of char. The clay loam and the 50:50 and 75:25 soil mixes were more responsive to the addition of char than was ASM.     

Improvement of fire retardancy of plywood by incorporating boron or phosphate compounds in the glue

A practical approach to enhancing the fire retardancy of wood-based materials by adding fire-retardant chemicals to the glue was developed. Plywoods were manufactured using urea melamine formaldehyde resin mixed with ammonium pentaborate or dihydrogen phosphate. Treated plywoods had better incombustibility than untreated ones. X-ray photoelectron spectroscopy (XPS) analysis clearly demonstrated the distribution of boron and phosphorus, which had migrated from the glue to the wood, contributing to better fire retardant properties. The cross-sectional micrographs from scanning electron microscopy showed that untreated specimens exhibited a foamy structure near the interface in the glue layer and the deformed structure of wood cells. The cell structure and cell wall thickness retained intact in the specimens treated with urea melamine formaldehyde resin mixed with ammonium pentaborate or dihydrogen phosphate. When observing the effect of the thickness of overlay veneers on incombustibility, a shorter glowing time was obtained from the specimens with a thicker surface layer when the fire retardant chemical was added at 2%, but the differences were smaller at the higher chemical retention of 4%. A similar tendency was observed for the char length.Part of this paper was presented at the International Tropical Wood Conference in Kuala Lumpur, Malaysia, June 1997     

Biochar differentially affects the cycling and partitioning of low molecular weight carbon in contrasting soils

Biochar application to soils has received much attention due to the potential for dual benefits of improved fertility and carbon (C) sequestration. Whilst its effect on C and nitrogen (N) cycling in soils has been investigated previously, this has usually either focussed on the bulk soil organic matter, or a single compound such as glucose. Five low molecular weight dissolved organic C (LMWDOC) substrates (three sugars, one amino acid, one organic acid) were selected for a ¹⁴C-CLPP experiment from which turnover rate (t_1/2) and immediate carbon use efficiency (CUE) of the substrate were estimated. We demonstrated that whilst soil type had the greatest effect on soil microbial function, the addition of biochar also influenced microbial turnover and CUE of the substrates, most notably in the lowest fertility soil. We also identified that the relationship between turnover and CUE of the five substrates differed substantially, and the effect of biochar and soil type was more pronounced in the amino acid than the organic acid. This effect tended to be greatest in biochars produced at 450 °C, and less pronounced with the addition of biochars produced at 550 °C, though these trends were not consistent for all compounds in all soils tested. We conclude biochars and soils interact to manifest non-systematic differences in turnover rates of LMWDOCs, and thus a variety of mechanisms are likely responsible for this observation. As these compounds are most commonly found in the rhizosphere and can contribute a significant portion of photosynthetically-fixed C, and plant roots have been observed to grow preferentially around biochar particles, it is apparent that biochar may significantly affect the flow of LMWDOC through the microbial community in soils.