摘要
本文在 A— S方程的基础上推导出气体流经固定床时的压降表达式。该式表明固定床中的压降与床层内的压力水平成反比 ;在一般情况下 ,必须通过数值积分才能得到总的床层压降 ,只有在等温条件下床层压降才有解析解。实验数据表明 ,本文给出的公式能很准确地统一不同压力水平下的流量—压降之间的定性关系 ,但是当催化剂颗粒形状不同时 ,流量—压降之间的定量关系不同 ;通过对数据的分析证实流量—压降关系中的两个系数反映了颗粒形状 (包括粗糙度 )对压降的影响。本文所选用的三种异形催化剂的颗粒形状可使粘性力引起的床层压降相差约 2 .0 3倍 ,使惯性力引起的床层压降相差约 2 .7倍。这些结论说明应用Ergun方程计算压降会给计算结果带来很大的误差。
Based on A S equation, a new expression was derived for pressure drop in fixed bed with gaseous flow. It was indicated by using the proposed expression that the pressure drop is inversely proportional to the pressure level in the bed, and that the overall pressure drop should be obtained by numerical integration. In the case of isothermal gas flow, however, the overall pressure drop can be expressed in an analytical way similar to Ergun equation. Experimental data demonstrated excellent generality of the presented expression for describing the flow rate pressure drop relation under different pressure levels, while the two coefficients in the expression significantly differ for beds with different shaped catalyst particles. It was also revealed from the analysis to experimental data that the two coefficients (defined as particle shape coefficients in this paper) reflect the effect of catalyst particle shape (including surface roughness) on pressure drop. For the three kinds of abnormal shaped catalyst particles used, i.e., ring, wheel shape and honeycomb shape, difference of 2.03 times was found in the pressure drop due to viscous resistance and form drag, and up to 2.7 times due to inertial resistance. It was demonstrated that the Ergun equation will lead to a considerably wrong prediction of pressure drop in industrial fixed bed reactors with abnormal shaped catalyst particles operating under high pressures and high temperatures. [WT5HZ]
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2000年第1期1-6,共6页
Chemical Reaction Engineering and Technology
基金
西南化工研究院资助
关键词
固定床
压降
模型
温度
压力
颗粒形状
气体
fixed bed
pressure drop
pressure drop model
pressure and temperature effect
particle shape effect
abnormal shaped catalyst particles
