共查询到19条相似文献,搜索用时 468 毫秒
1.
2.
3.
4.
5.
(气)-液-固循环流化床的研究进展 总被引:1,自引:0,他引:1
液-固(L-s)和气-液-固(G-L-s)循环流化床与传统流化床相比具有许多优点。但对L-S和G-L-S循环流化床的研究报道与气一固循环流化床相比较少。由于新加工过程和生物技术的兴起.拓宽了L-S和G-L-S循环流化床的应用新领域。为了理解和掌握这两种液相循环流化床的流动特性,对其近期的研究进展进行了回顾,并对其在生物化工中的应用前景进行了展望。 相似文献
6.
7.
在耦合流化床反应器大型冷模实验装置上,考察了不同表观气速下FCC颗粒在耦合流化床内截面平均密度的轴向分布. 结果表明,反应器轴向固含率可分为底部流化床区域和上部提升管区域. 前者的密相区平均固含率随表观气速增大而减小;后者的平均固含率随表观气速Ug增大而增大,Ug<0.58 m/s时固含率分布均匀,Ug=0.70~1.04 m/s时提升管出口出现约束返混区(>8.62 m),Ug>1.16 m/s时提升管底部出现密度重整区(3.82~4.57 m)、加速平稳区(4.57~8.62 m)和出口返混区(>8.62 m). 确定了耦合反应器内提升管区域截面平均固含率的影响参数,并利用实验数据回归了平均固含率的轴向分布经验模型,计算值与实验值吻合较好. 相似文献
8.
9.
实验的三相循环流化床以玻璃珠 (dp = 0.48 mm, ρs = 2460 kg(m(3) 和苯乙烯颗粒 (dp = 1.45mm, ρs = 1264 kg(m(3)为固相,空气为气相,水、0.05%、0.20% (mass) CMCS (羧甲基纤维素钠)水溶液为液相.实验研究了液体粘度、表观液体速度、表观气体速度、辅助液体速度及颗粒密度对颗粒循环速度的影响.随着液体粘度的增加,颗粒循环速度增加;随着表观液体速度和辅助液体速度增加,颗粒循环速度都增加;随着表观气体速度的增加,颗粒循环速度减小.低密度颗粒系统同高密度颗粒系统相比,低密度颗粒系统能提前从三相传统流型进入三相循环流型.实验还研究了液体粘度对低密度颗粒的起始液体速度和过渡液体速度的影响,为得到三相循环流化床的流型图提供了可靠的依据. 相似文献
10.
11.
Kyong-Bin Choi Sang-Il Park Yeong-Seong Park Su-Whan Sung Dong-Hyun Lee 《Korean Journal of Chemical Engineering》2002,19(6):1106-1111
The effects of gas velocity, inlet gas temperature and the solid feed rate on the drying efficiency, the outlet solid moisture
content, bed temperature in each stage, the outlet gas humidity and temperature in a rectangular acryl multistage fluidized
bed (0.172 m×0.192 m×1.5 m-high) with a downcomer (0.04 m-I.D.) were investigated. The experiments were performed by using
1.9 mm millet particles. The final moisture contents of the solids increased with increasing the solid feed rate. The drying
efficiency increased with increasing the wetted solid feed rate but decreased with increasing the inlet gas temperature. The
drying performance of the multistage fluidized bed was compared with the single-stage fluidized bed and found to be superior
under identical operation conditions. The model predicted values were well matched with the experimental data in the multistage
fluidized bed dryer.
This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University. 相似文献
12.
Somchart Soponronnarit Anan Pongtornkulpanich Somkiat Prachayawarakorn 《Drying Technology》1997,15(5):1603-1615
A batch fluidized bed dryer was carried out for corn drying. Drying characteristics of corn were investigated The experimental results indicated that moisture transfer inside a corn kernel was controlled by internal diffusion by the following conditions : inlet hot air temperatures of 120 - 200 °C, superficial air velocities of 2.2- 4 m/s, bed depths of 4 - 12 cm, fraction of air recycled of 0.5 -0.9 and initial moisture content of corn of 43 % dry-basis. The Wang and Sing equation could describe in accordance with the results. Inlet hot air temperature and specific air flow rate were independent variables for drying constant model in the Wang and Singh equation. 相似文献
13.
Somchart Soponronnarit Anan Pongtornkulpanich Somkiat Prachayawarakorn 《Drying Technology》2013,31(5):1603-1615
ABSTRACT A batch fluidized bed dryer was carried out for corn drying. Drying characteristics of corn were investigated The experimental results indicated that moisture transfer inside a corn kernel was controlled by internal diffusion by the following conditions : inlet hot air temperatures of 120 - 200 °C, superficial air velocities of 2.2- 4 m/s, bed depths of 4 - 12 cm, fraction of air recycled of 0.5 -0.9 and initial moisture content of corn of 43 % dry-basis. The Wang and Sing equation could describe in accordance with the results. Inlet hot air temperature and specific air flow rate were independent variables for drying constant model in the Wang and Singh equation. 相似文献
14.
The effects of gas velocity (0.32 to 0.67 m/s), inlet gas temperature (25 to 100 °C) and the mass ratio of starch to inert particles (0.1 to 0.4) on the drying rate of starch in a 0.083 m-ID × 0.80 m-high inert medium fluidized bed were investigated. The drying mechanism in an inert medium fluidized bed can be classified into adhesion-dispersion, evaporation and disintegration steps. The drying rate increases with the increasing inlet gas temperature and velocity; the rates being about 10 times those reported for an agitated pan dryer. However, the drying rate decreases slightly as the mass ratio of starch to inert particles increases. Also, the drying rate exhibits a maximum at an optimum bed porosity. The drying rate data obtained in an inert medium fluidized bed have been correlated with the relevant dimensionless groups, i.e. Stefan and particle Reynolds numbers based on the theory of isotropic turbulence. 相似文献
15.
An experimental study of the residence tine distribution and drying characteristics of a continous pilot-plant vibrated fluidized bed dryer(the air distributor plate is 1.50 m in length and 0.24 m in width) is presented and discussed. Operating variables in the study included: vibration intensity, mass flow rate of air, granules feed rate, inlet air temperature and particle size. It was inferred from the experimental results that the flow of particles in the continous VFB could be considered as plug flow. Among the variables considered, vibration intensity was identified as the most significant factor to affect particle mean residence time, particle diffusivity and constant drying rate for the bed of wheat particulates and instant pharmaceutical BYN granules. 相似文献
16.
17.
A fluidized bed dryer (FBD) and a combined microwave/fluidized bed dryer (CMFD) are used to dry the fresh ripe peppercorns. The average moisture content vs. elapsed drying time, and drying rate vs. average moisture content are experimentally investigated. It is found that the microwave field from the CMFD can increase the potential of the conventional fluidized bed drying. The drying rates of both dryers are dependent on the inlet air temperature and velocity. For the CMFD, the effects of the air velocity on the drying rate are found to be opposite to our previous results tested with white pepper seeds i.e., the drying rates of the fresh ripe peppercorns decreased with increasing air velocity. By using a CMFD, the drying time required to reach the desired moisture content can be reduced to 80-90% of the drying time required for a FBD at the same drying air temperature and velocity. The color of the product dried by a CMFD is also attractive: it becomes flaming yellow, instead of black as obtained from a FBD. The physical structure of the peppercorn, before and after the drying process is also investigated by a metallurgical macroscope and an image analyzer. Different from drying by a FBD, the external form and matter of the white pepper seed are still maintained, even after passing through the drying process. 相似文献
18.
F.C. Godoi N.R. PereiraS.C.S. Rocha 《Chemical Engineering and Processing: Process Intensification》2011,50(7):623-629
A rotating-pulsed fluidized bed (RPFB) dryer was employed to conduct the drying of poly-hydroxybutyrate (PHB) cohesive granules. Along the experiments, it was possible to identify, visually, 3 different dynamic regimes that were related with the temperature profile, the drying kinetics and the fluid dynamic behavior. The drying kinetics of PHB showed a short constant drying rate period followed by a decreasing drying rate period. The constant drying rate (Nc) and final moisture content (dry basis) were related to the rotation frequency (responsible for the pulsation effect), temperature and velocity of the inlet air. Furthermore, measurements of molecular mass (gel permeation chromatography analysis) and Carr Index (flowability test) on PHB samples were done before and after the drying. The RPFB dryer showed to be appropriate to dry the PHB granules, resulting in an excellent fluid dynamic behavior that provided uniform drying of the solid. The best conditions of drying were identified at 7 Hz of rotation frequency, 90 °C and 0.55 m/s of inlet air temperature and velocity. At these conditions the dried PHB reached final moisture content of 0.56% (wet basis) after 2 h of drying. 相似文献
19.
《Drying Technology》2013,31(4):779-794
Abstract A fluidized bed dryer (FBD) and a combined microwave/fluidized bed dryer (CMFD) are used to dry the fresh ripe peppercorns. The average moisture content vs. elapsed drying time, and drying rate vs. average moisture content are experimentally investigated. It is found that the microwave field from the CMFD can increase the potential of the conventional fluidized bed drying. The drying rates of both dryers are dependent on the inlet air temperature and velocity. For the CMFD, the effects of the air velocity on the drying rate are found to be opposite to our previous results tested with white pepper seeds i.e., the drying rates of the fresh ripe peppercorns decreased with increasing air velocity. By using a CMFD, the drying time required to reach the desired moisture content can be reduced to 80–90% of the drying time required for a FBD at the same drying air temperature and velocity. The color of the product dried by a CMFD is also attractive: it becomes flaming yellow, instead of black as obtained from a FBD. The physical structure of the peppercorn, before and after the drying process is also investigated by a metallurgical macroscope and an image analyzer. Different from drying by a FBD, the external form and matter of the white pepper seed are still maintained, even after passing through the drying process. 相似文献