热式气体质量流量计预热特性的研究

针对热式气体质量流量计需要经过一定预热时间才能到达稳定的工作状态的问题,根据JJG897-1995《质量流量计》国家计量检定规程中关于示值误差计量的要求,设计气体质量流量计示值误差曲线与预热时间关系试验;并根据试验结果,提出热式气体质量流量计的合理预热时间。

木材真空-过热蒸汽干燥的预热特性

在真空状态下 ,分别对过热蒸汽和空气为干燥介质时木材干燥预热阶段进行对比试验 ,探讨了木材在真空 -过热蒸汽干燥中预热阶段的工艺特性。结果表明 :过热蒸汽干燥的预热阶段进行得非常迅速 。

烟煤循环流化床预热特性实验

在30 kW预热燃烧实验平台上开展神木烟煤的预热特性实验研究,并采用激光粒度分析仪、全自动比表面积分析仪、场发射电子显微镜和激光拉曼光谱仪对神木烟煤原煤和预热半焦进行粒径、比表面积、表观形貌和碳结构的对比分析。实验结果表明:预热过程对燃料在物理性能方面有较好的改性提质作用,预热燃料相比于原煤表现为粒径变小、比表面积变大、孔隙结构变多;预热过程中碳架结构石墨化程度降低,碳架结构的稳定石墨结构会向无序的活性缺陷结构转变,导致预热燃料中活性缺陷碳结构增多,燃烧反应性增强。

Study on Wood Drying Properties under Vacuum-floating Pressure

Using Masson pine as specimens, when drying mediums are overheated steam and hot-air respectively, preheating characteristics of wood under vacuum-floating pressure drying are discussed by measurement of internal temperature field and variation of moisture content during period of preheating. The relationship between drying medium conditions and drying rate of wood reveals that, firstly, compared with process of air-drying, time needed to be preheated under vacuum-floating decreased dramatically, meanwhile,the magnitude of condensation on the surface is relatively larger. Secondly, drying rate of wood under vacuum-floating pressure increases coupled with temperature of medium, reduction of absolute pressure,and raise of fluctuation rate of pressure. The sequence of factors contribution to drying rate is listed as following: temperature of medium (t) > fluctuation rate of pressure (f)> absolute pressure (p).