气体流速对SiO2／S涂层中试制备的影响

Impacts of Gas Flow Rate on Growth of Coke-Inhabiting SiO_2/S Films Inside Cracking Tubes of Pilot Ethylene Facility

为了抑制乙烯裂解炉管内表面结焦，在实验室小试的基础上，对SiO/S涂层进行了中试制备研究。并分析了不同气体流速对涂层形貌和结构的影响，优化了涂层中试制备工艺。采用扫描电子显微镜和Raman光谱对涂层形貌、成分和结构进行了表征。对优化后涂层的热冲击性能进行了考核。结果表明：随着气体流速的增加，炉管出VI涂层粒子逐渐变小，结合也更加致密。同时，涂层厚度及Si—O—S结构逐渐增加。当气体流速为30～40m／s时，炉管出口涂层厚度为8～10μm，粒子结合致密。涂层经过16次热冲击试验后仍未剥落，可以满足抑制炉管结焦使用要求。

The coke-inhabiting SiO2/S coatings were deposited by ambient pressure chemical vapor deposition on the inner walls of the cracking tubes in the pilot facility for ethylene production. The influence of the SiO2/S coating condi- tions, such as the steam flow rate, steam temperature, and chemical concentrations, on the mechanical properties of the SiO2/S coating was studied. The micmstructures and mechanical properties of the coating were characterized with scanning electron microscopy and Raman spectroscopy. The results show that the steam flow rate significant affects the mechanical prop＆ties of the SiO2/S coatings. For instance, as the steam flow rate increases, the coating, sampled at the tube coil outlet, was found to be more compact, with increasing smaller grains and stronger interracial adhesion. At a flow rate of 30 - 40m/s, the coating with thickness of 8 - 10μm was obtained, and no peeling off was observed after 16 cycles of water quenching.