| 查看: 142 | 回复: 1 | ||
| 当前主题已经存档。 | ||
风雨182木虫 (正式写手)
|
[交流]
【求助】请教高手
|
|
| 在声场高温流化床中，声波的传播过程依靠流化介质中各质点间的动量传递进行。当表观速度较低时，床层仍处于固定床阶段，声能经过床层颗粒时受到削弱，声波无法传播到床层顶部，因此对颗粒流化质量影响很小；随着表观速度增大，床层进入散式流态化，床层均匀膨胀，孔隙率变大，声波可以传播到床层顶部，使颗粒在较低速度下实现流化；当速度进一步提高时，床层开始膨胀，床层进入鼓泡流态化，声波的存在降低了床层最小鼓泡速度，减小了气泡尺寸和压力波动幅度，抑制了气泡的上升速度，增加了气固两相接触效率，有利于颗粒的传质和传热，导致颗粒的最小流化速度急剧降低。 |
回复此楼
monitor2885
至尊木虫 (职业作家)
队长
- 翻译EPI: 15
- 应助: 6 (幼儿园)
- 贵宾: 0.339
- 金币: 39310.5
- 散金: 147
- 红花: 22
- 帖子: 4976
- 在线: 2169.7小时
- 虫号: 701577
- 注册: 2009-02-15
- 性别: GG
- 专业: 生态系统生态学
★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
风雨182(金币+20,VIP+0):谢拉 9-2 10:07
风雨182(金币+20,VIP+0):谢拉 9-2 10:07
|
在声场高温流化床中，声波的传播过程依靠流化介质中各质点间的动量传递进行。当表观速度较低时，床层仍处于固定床阶段，声能经过床层颗粒时受到削弱，声波无法传播到床层顶部，因此对颗粒流化质量影响很小；随着表观速度增大，床层进入散式流态化，床层均匀膨胀，孔隙率变大，声波可以传播到床层顶部，使颗粒在较低速度下实现流化；当速度进一步提高时，床层开始膨胀，床层进入鼓泡流态化，声波的存在降低了床层最小鼓泡速度，减小了气泡尺寸和压力波动幅度，抑制了气泡的上升速度，增加了气固两相接触效率，有利于颗粒的传质和传热，导致颗粒的最小流化速度急剧降低。 Under circumstances of sound field in the high-temperature fluidized bed，spread process of acoustic relies on each of momentum transfer between particles in streaming media. When superficial velocity is low, the bed still performs be in fixed-bed stage. The sound energy through the particle bed is weakened, so that sound cannot be spread to the top of bed. So there is a little impact on the quality of particle flow. As apparent velocity increases fluidization bed is done, bed will uniformly expand, with bigger porosity, so that sound can be transmitted to the top of bed. Particle at a lower speed achieves fluidization. When the speed further increases, the bed starts to expand into the bubbling fluidized bed. The presence of sound wave will reduce the velocity of minimum bubbling bed, as well as reduction in bubble size and pressure fluctuation to inhibit bubble rising velocity and increase the efficiency of gas-solid contact. It is favorable for particle to complete mass and heat transfer, resulting in the minimum fluidization velocity of particles to decrease dramatically. |
2楼2009-09-01 19:33:12
