硫酸分解反应器作为热化学硫碘制氢系统中的重要设备,其换热需要匹配系统的产氢量换热需求。为研究硫酸分解反应器不同结构对换热的影响,使反应器的换热满足系统需求,同时满足制造工艺的限制。通过试验对硫酸分解反应进行反应动力学参数标定并建立反应动力学模型,用gPROMS软件对反应器进行仿真,得到反应器内的压力、温度、流量和各组分浓度等参数。结果表明:反应器总长度不变,调整预热段和反应段长度比或提高填充颗粒热导率无法提升总转化率。反应器增加预热段长度可显著增加总转化率,关键原因是预热段长度决定了反应器内温度能否达到SO3分解反应所需最佳温度850℃。减小反应器直径并不能增加总转化率,虽然反应器的直径减小有利于传热,但由于整体入口流量不变,流体流速显著提高,减少了反应物的停留时间,同时还会显著增加反应器流阻。采用套筒环腔内、外加热结构作为反应器预热段可有效提高总转化率。采用内外同时加热时,增加了换热面积,有利于缩短预热段长度,预热段长度仅需900mm左右反应器出口温度即可达到850℃,得到了符合要求的反应器结构设计。

The sulfuric acid decomposition reactor is an important equipment in the thermochemical sulfur iodine hydrogen production system, its heat transfer needs to match the hydrogen production capacity of the system. In order to study the effect of different structures ofsulfuric acid decomposition reactors on heat transfer, and to ensure that the heat transfer of the reactor meets the system requirements whilealso meeting the limitations of manufacturing processes. Through experiment, the reaction kinetics parameters of sulfuric acid decomposition reaction were calibrated and a reaction kinetics model was established. The reactor was simulated by gPROMS to obtain parameterssuch as pressure, temperature, flow rate, and component concentrations within the reactor. Results show that the total conversion rate cannot be improved by adjusting the length ratio of the preheating section and the reaction section or increasing the thermal conductivity of thepacked particles, while the total length of the reactor remains unchanged. Increasing the length of the preheating section in the reactor cansignificantly increase the total conversion rate. The key reason is that the length of the preheating section determines whether the temperature inside the reactor can reach the optimal temperature of 850 ℃ required for the SO3 decomposition reaction. Reducing the reactor diameter does not increase the total conversion rate, although reducing the diameter of the reactor is beneficial for heat transfer, due to the unchanged inlet flow rate, the fluid flow rate increases significantly, reducing the residence time of the reactants and significantly increasingthe reactor flow resistance. Using a sleeve annulus internal and external heating structure as the preheating section of the reactor can effectively improve the total conversion rate. When both internal and external heating are used, increasing the heat transfer area is beneficial forshortening the length of the preheating section. The length of the preheating section requires about 900 mm to achieve a reactor outlet temperature of 850 ℃ . A reactor structure design that meets the requirements has been found.

0 引言

1 热化学硫碘制氢原理和系统流程

   1.1 原理

   1.2 系统流程

2 仿真模型及控制方程

   2.1 固定床压降

   2.2 床层-壁面换热系数

   2.3 流-固换热系数

3 反应动力学试验

   3.1 试验装置

   3.2 反应动力学模型

4 硫酸分解反应仿真结果

   4.1 不同预热段/催化段比例及催化剂颗粒导热系数对反应器性能的影响

   4.2 不同预热段长度及反应器直径对反应器性能的影响

   4.3 不同预热段形式对反应器性能的影响

5 结论