【摘要】 针对流化床内颗粒受热产生黏性及由此引发的团聚、失流化现象,利用低温模拟物聚乙烯颗粒在二维内循环流化床实验台内对床内颗粒受热团聚过程进行实验模拟,找了颗粒团聚成长规律。通过分析不同工况下的团聚物质量占物料总质量的比例,找出影响颗粒团聚的因素。实验表明,流化床内颗粒团聚过程分为两个主要阶段:成核阶段及黏性核快速长大并破碎阶段。流化床运行温度存在一高一低两个临界点,当温度低于较低临界点时,床内颗粒平稳流化,无团聚现象出现;当温度高于低临界点低于高临界点时,床内颗粒出现部分团聚;当温度高于高临界点时,床内颗粒迅速出现大范围团聚,因此将低临界点定义为第一临界温度,高临界点定义为第二临界温度。较低床温、合理流化风速配比、高非黏颗粒比例都对颗粒团聚有显著抑制作用。更多还原

【Abstract】 To study the defluidization phenomenon in fluidized beds,polyethylene particles were used to simulate the process of particle agglomeration in a two-dimensional internally circulating fluidized-bed. By sampling, the agglomerate growth was investigated.Experimental results showed that the process could be divided into two stages:the nucleation stage and the accelerated growth stage.There were two critical temperatures which were defined as the first critical temperature and the second critical temperature.When the bed temperature was below the first critical temperature,particle agglomeration did not happen.When the bed temperature was between the first and the second critical temperature,the agglomeration occured. When the bed temperature was higher than the second critical temperature,the agglomeration grew quickly.Low bed temperature,reasonable fluidizing air distribution and high noncohesive particle content were all beneficial to restrain agglomeration.更多还原