Abstract:

During the strong exothermic reaction in the fixed-bed reactor, the hot spot temperature of the reactor is sensitive to the change of operating parameters, which can easily cause flying temperature, resulting in a decrease in conversion rate and affecting catalyst life. In order to enhance the synergy of heat and mass transfer and chemical reaction in a fixed-bed reactor for carbonylation, a one-dimensional pseudo-homogeneous heat transfer model was established to investigate the effects of operating parameters on bed hot spot temperature, reaction conversion and bed temperature rise. The presented method not only reflects the synergistic effect of heat and mass transfer and reaction, but also has clear interrelation and convenient algorithm. Under the experimental application conditions, the catalyst particle diameter is less than or equal to 1.5 mm. The reactor inlet temperature / coolant oil temperature should not only meet the requirements of thermal stability of the bed, but also make the reaction conversion and bed temperature rise within a reasonable range. The simulation results show that with the increase of bed inlet temperature, good conversion rate and small bed temperature rise can be obtained by reducing the coolant oil temperature. On this basis, the effect of ethylene oxide inlet concentration on the conversion and bed temperature rise was investigated. This study can provide a basis for the selection of operating parameters such as catalyst particle diameter, bed inlet temperature, coolant oil temperature and bed inlet concentration for the fixed-bed reactor to meet the conversion requirements and reasonable bed temperature rise.

Key words: fixed-bed reactor, pseudo-homogeneous model, hot spot, interior diffusion, reaction conversion, bed temperature rise

摘要：

固定床反应器中进行强放热反应时， 反应器的热点温度对操作参数变化敏感，容易引起飞温，导致转化率下降，影响催化剂寿命。为强化羰基化固定床反应器内热质传递与化学反应的协同性，建立考虑颗粒内扩散影响的羰基化固定床反应器拟均相一维传热模型，考察操作参数对床层热点温度、反应转化率、床层温升的影响。不仅体现传热传质和反应的协同作用，而且影响关系明晰、求解方便。为保证反应转化率，本实验条件下确定催化剂颗粒直径小于等于1.5 mm。反应器入口温度/冷却剂油温既要满足床层热稳定性需求，又要使反应转化率和床层温升都在合理范围内。模拟结果表明在床层入口温度升高的同时，可通过降低冷却剂油温获得良好的反应转化率和较小的床层温升。在此基础上，考察入口环氧乙烷浓度对反应转化率和床层温升的影响。本研究可为固定床反应器满足转化率要求、床层合理温升而选择催化剂颗粒直径、床层入口温度、冷却剂油温和床层入口浓度等操作参数提供计算依据。

关键词: 固定床反应器, 拟均相模型, 热点, 内扩散, 转化率, 床层温升