Calorific value change of slash as logging residues after biological-drying under humid weather conditions in Japan

为了确定湿地生物干燥的可行性，通过田间干燥试验，估算湿地生物干燥后的热值，并分析湿地生物干燥过程，将杉树枝装入金属丝网袋中，制成湿地袋（15 ~ 25条枝条，6000.0 ~ 11173.2g），田间连续称重。我们还把3个袋子堆在地上，建立了3个桩。2004年7月31日至2004年10月4日期间进行了实地试验，包括每天两次（早晚）称量每个袋子的重量，并测量堆内的温度。在日本鹿儿岛大学森林，年降雨量在3, 000 mm以上，一般情况下，采伐迹地的含水量都能达到平衡含水量（EMC），平衡含水量对应于采伐迹地的各个相对湿度。 ...更多信息 相对湿度在30摄氏度下，对于50%湿度，EMC将为约15%，对于80%湿度，EMC将为24%。由于在我们的实验中，我们的领域的平均相对湿度为85%，EMC可以估计为25%至30%。尽管经历了三次台风袭击，降雨量较大，但上层桩的电磁兼容性仍为18%~ 32%，中层桩的电磁兼容性为15%~ 63%。通过生物干燥，有可能使炉渣的含水率降低到EMC。含水率低的采伐迹地热值高，运输成本低。超过2000千卡/千克的燃料可以在没有任何额外燃料的情况下自燃。因此，通过60 d的干燥，可以使剩余物的含水率降低到原来的1/5左右，热值提高到原来的2倍。从所获得的结果，它可能是可能的，以估计在该领域的相对湿度的剩余物的EMC。然而，干燥本质上是一个扩散过程，必须模拟水分扩散过程，生物干燥（自然干燥）是提高燃料质量的合理途径。在实际应用中，坡脚桩顶部覆盖防水层可有效防止降雨和结露的影响。少

Objectives of this study were to estimate the net calorific value that slash would contain after biological-drying, and to analyze the drying process of slash through drying experiments in a field.To identify the biological drying process in the field, we established slash bags those filled Sugi branches into a wire net bag (15 to 25 branches, 6000.0g to 11173.2g) and continuously scaled weights in the field. Also we piled 3 bags on a ground and established 3 piles. Field experiments, which included weighing each bag twice a day (morning and evening) and measuring temperature inside a pile, were carried out during 31 July 2004 to 4 October 2004. Weather conditions (air temp and humidity, wind velocity, precipitation, solar radiation) are also measured near the field site.Our study site was Kagoshima University Forest in JAPAN with more than 3,000mm annual rain fall.In general a moisture content of slash would reach to the equilibrium moisture content (EMC) which corresponds to each rel … More ative humidity. At 30 degree C, the EMC would be about 15% for 50% humidity and 24% EMC for 80% humidity. Since the average relative humidity in our field was 85% during our experiment, EMC could be estimated 25% to 30%. The EMCs of slash piles were observed 18 to 32% for upper layer pile and 15 to 63% for middle pile in spite of three times typhoon attacks with much rain fall. Through biological drying, it might be possible to decrease the moisture content of slashes reaching to EMC. The slash with lower moisture shows higher calorific heat value and needs lower transporting cost. Fuels with more than 2000kcal/kg could burn spontaneously without any additional fuels. Therefore, slash drying means improving fuel quality both in thermal and economic efficiency.Through 60-days drying, the moisture contents of slash became about one fifth and the calorific heat values increased to twice of initial value. From the results obtained, it might be possible to estimate the EMC of slash in the field from relative humidity. However, drying is essentially expressed as the diffusion process and we would have to model water contents diffusion process.Biological drying (natural drying) of slash would be a reasonable way to improve fuel quality. For a practical application, waterproof top mulching of slash piles might be useful for prevent from rain fall and dewing influence. Less