Minimum spouting velocity （Ums） is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology w...Minimum spouting velocity （Ums） is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology was initiated in 1955. In this paper, a new correlation is developed for Ums based on 767 published experimental data covering both high pressure and high temperature conditions. The calculated and the measured results of Ums are in better agreement than other published correlations.展开更多
采用恒温干燥(40,50,60,70℃)和阶段变温干燥(阶段升温和阶段降温)工艺对怀山药进行红外喷动床干燥(IRSBD)处理,研究其对干燥动力学、均匀性及品质特性(质构、复水性能、总酚含量、微观结构和皱缩率)的影响。对怀山药红外喷动床干燥曲...采用恒温干燥(40,50,60,70℃)和阶段变温干燥(阶段升温和阶段降温)工艺对怀山药进行红外喷动床干燥(IRSBD)处理,研究其对干燥动力学、均匀性及品质特性(质构、复水性能、总酚含量、微观结构和皱缩率)的影响。对怀山药红外喷动床干燥曲线的数学模型拟合结果表明,Midilli模型R2最大(0.99989),RMSE和χ2最小(分别为0.00319和1.69872×10-5),最适合描述怀山药IRSBD动力学。对比不同干燥工艺发现,恒温干燥条件下,提高干燥温度有利于缩短干燥时间,降低能耗。阶段升温干燥能耗仅高于70℃恒温干燥,其干燥均匀性最好,样品总酚含量最高为(85.25±7.41)mg GAE/100 g DW,皱缩率及硬度最低,分别为(74.3±3.96)%和(24.95±7.41)N,且有良好的色泽。阶段降温干燥样品具有较高的平衡复水比和脆度,然而在干燥时间、能耗、均匀性及产品硬度、皱缩率和总酚含量方面没有显著优势。结论:阶段升温干燥是怀山药IRSBD更为理想的干燥工艺。研究结果可为IRSBD技术应用于农产品加工提供理论参考。展开更多
Sawdust was subjected to torrefaction in a "semi-batch" slot-rectangular spouted bed (SRSB) reactor at temperatures from 240 to 330℃ and biomass feed rates from 220 to 710g/h.Stable spouting of the sawdust ...Sawdust was subjected to torrefaction in a "semi-batch" slot-rectangular spouted bed (SRSB) reactor at temperatures from 240 to 330℃ and biomass feed rates from 220 to 710g/h.Stable spouting of the sawdust was achieved in the slot-rectangular spouted bed,although the pressure drop across the reactor was observed to oscillate.Compared to the biomass feed rate,the temperature had a greater effect on the biomass weight loss and energy yield.Increases in temperature were found to promote weight loss of the sawdust while decreasing the energy yield.The main solid product was the torrefied sawdust,which remained in the SRSB reactor and was captured by a cyclone.The ratio of the torrefied biomass removed by the cyclone to the total torrefied biomass increased along with both the feed rate and temperature.After undergoing torrefaction,6.7%-39.2% of the original sawdust mass was lost while 67.4%-98.7% of its energy was retained.The torrefied sawdust had a higher carbon content but less oxygen,hydrogen and volatiles,along with a greater higher heating value and increased density compared to the raw sawdust.The size of the sawdust particles also decreased markedly during the torrefaction process.展开更多
基金the National Natural Science Foundation of China through the program ＂Time and Spatial Multi-Scale Interactions in Chemical Engineering and Their Effects＂ （Grant No. 20490201）.
文摘Minimum spouting velocity （Ums） is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology was initiated in 1955. In this paper, a new correlation is developed for Ums based on 767 published experimental data covering both high pressure and high temperature conditions. The calculated and the measured results of Ums are in better agreement than other published correlations.
文摘采用恒温干燥(40,50,60,70℃)和阶段变温干燥(阶段升温和阶段降温)工艺对怀山药进行红外喷动床干燥(IRSBD)处理,研究其对干燥动力学、均匀性及品质特性(质构、复水性能、总酚含量、微观结构和皱缩率)的影响。对怀山药红外喷动床干燥曲线的数学模型拟合结果表明,Midilli模型R2最大(0.99989),RMSE和χ2最小(分别为0.00319和1.69872×10-5),最适合描述怀山药IRSBD动力学。对比不同干燥工艺发现,恒温干燥条件下,提高干燥温度有利于缩短干燥时间,降低能耗。阶段升温干燥能耗仅高于70℃恒温干燥,其干燥均匀性最好,样品总酚含量最高为(85.25±7.41)mg GAE/100 g DW,皱缩率及硬度最低,分别为(74.3±3.96)%和(24.95±7.41)N,且有良好的色泽。阶段降温干燥样品具有较高的平衡复水比和脆度,然而在干燥时间、能耗、均匀性及产品硬度、皱缩率和总酚含量方面没有显著优势。结论:阶段升温干燥是怀山药IRSBD更为理想的干燥工艺。研究结果可为IRSBD技术应用于农产品加工提供理论参考。
文摘Sawdust was subjected to torrefaction in a "semi-batch" slot-rectangular spouted bed (SRSB) reactor at temperatures from 240 to 330℃ and biomass feed rates from 220 to 710g/h.Stable spouting of the sawdust was achieved in the slot-rectangular spouted bed,although the pressure drop across the reactor was observed to oscillate.Compared to the biomass feed rate,the temperature had a greater effect on the biomass weight loss and energy yield.Increases in temperature were found to promote weight loss of the sawdust while decreasing the energy yield.The main solid product was the torrefied sawdust,which remained in the SRSB reactor and was captured by a cyclone.The ratio of the torrefied biomass removed by the cyclone to the total torrefied biomass increased along with both the feed rate and temperature.After undergoing torrefaction,6.7%-39.2% of the original sawdust mass was lost while 67.4%-98.7% of its energy was retained.The torrefied sawdust had a higher carbon content but less oxygen,hydrogen and volatiles,along with a greater higher heating value and increased density compared to the raw sawdust.The size of the sawdust particles also decreased markedly during the torrefaction process.
