垂直立管中料层平衡高度的控制与操作

对催化裂化装置中,垂直立管中催化剂料层高度的变化对立管中催化剂的输送操作及料封的影响进行了考察。研究发现,催化剂在垂直立管中的流动可分为"脱气"和"持气"两种状态。实验结果表明,催化剂在立管中稀相流动时,压降降低,轴向压力分布有较好的线性关系,利于稳定操作和提高催化剂的循环速度。当立管中催化剂料层平衡高度较小时,"脱气段"较短,因而有利于催化剂在立管中的循环下移。因此,催化剂在立管中的输送宜采取控制一定料面高度的半充满操作方式,使催化剂在立管中形成空管或稀相流化与临界移动床下输共存的流动形式,使之既可保证立管下端良好的料封,又能满足整个装置系统稳定运行所要求的催化剂的输送循环。

Control and Operation of Balance Bed Height of Catalyst in the Stand Pipe

Experiments were conducted aiming at controlling balance bed height of catalyst and at studying characteristics of catalyst transportation in the stand pipe. The flow characteristics of catalyst particles in stand pipe involved both status of "gas holding" and "gas stripping". When catalyst particles flew in dilute phase the pressure drop in stand pipe decreased and axial pressure profile appeared linear. Lower bed height in the stand pipe made "gas stripping section" shorter. All of these operations enhanced solid circulating rate and maintained a steady moving-down of catalyst particles. Therefore conventional operation mode of stand pipe with catalysts full -filled should be improved. The better operation was to allow the stand pipe to operate with catalyst semi -packed,so as to form a flow status of either "empty pipe " or dilute fluidization coexisting with critical down transporting of moving-bed in stand pipe. It will make the operation of the stand pipe to have the advantages of steadiness, lower pressure drop, linear distribution of axial pressure, increasing solid circulating rate and maintaining promising sealing off by solid at the bottom of stand pipe.