FCC沉降器结焦问题的研究进展

沉降器是催化裂化中油气与催化剂分离过程的重要设备。沉降器的结焦问题易导致非计划停工，严重影响催化裂化装置的长周期运行，因此抑制或减缓沉降器结焦成为该领域的研究热点之一。综述了国内外有关沉降器结焦问题的研究进展，以期为沉降器的优化操作提供参考。首先对沉降器结焦的部位及原因进行了分析，从化学反应角度分析了结焦的内因是反应油气中液相重组分的存在；从流场分布、压力分布、催化剂含量分布和温度分布解析结焦的外因。进而阐述了结焦物的基本特性，按照不同方法对结焦物进行了分类和特性的比较。其次，从化学反应过程和油剂流动、焦体沉积与增长过程两方面总结了结焦的机理，并总结了操作条件(原料性质、催化剂含量、反应温度、再生剂温度和油/剂比)和沉降器结构(粗旋与顶旋连接结构、快分系统)对结焦的影响规律。最后根据结焦机理和影响因素，从优选反应物和优化操作条件、优化沉降器结构2个方面提出了抑制或减缓结焦问题的具体措施。提高沉降器温度和降低油气分压可从操作条件方面降低结焦的可能性，优化粗旋与顶旋连接结构、优化快分系统、优化分离器入口结构和顶旋升气管结构等措施可以改善沉降器内流场分布，进而抑制结焦。

Research Progress on Coking in FCC Disengager

Disengager is known as a vital device for separating oil and gas from catalyst in fluid catalytic cracking (FCC) progress. However, the coking in FCC disengager leads to unplanned shutdown, thus seriously affecting the long period operation of the FCC unit. Therefore, inhibiting or slowing down the coking in FCC disengager has become one of the research hotspots in this field. This paper summarizes the research progress on the coking problem of FCC disengager at home and abroad, hoping to provide a reference for the optimized operation of FCC disengager. Firstly, this paper analyzes the coking parts and relevant causes of the disengager. Based on the analysis from the perspective of chemical reaction, it is found that the internal cause of coking lies in the existence of liquid-phase heavy components in reaction oil and gas; the external cause of coking has been analyzed in terms of flow field distribution, pressure distribution, catalyst content distribution and temperature distribution. Next, this paper puts forward the basic characteristics of the coking materials, then clarifies the coking materials and performs a comparison of the characteristics using different methods. Secondly, the coking mechanism has been summarized in terms of chemical reaction process and oil flow, as well as coke deposition and growth process; the influence rule of the operating conditions (raw material properties, catalyst content, reaction temperature, regenerant temperature and oil/catalyst ratio) and the disengager structure on coking has also been summarized. Finally, according to the coking mechanism and influencing factors, specific measures to inhibit or slow down coking have been proposed from two aspects, i.e. , selecting the preferred reactant and optimizing the operating conditions and disengager structure. In conclusion, the possibility of coking can be reduced by changing operating conditions, i.e. , raising disengager temperature and lowering oil-gas partial pressure; the flow field distribution in the disengager can be improved by optimizing the connected structure of rough turning and top turning, the quick separation system, the inlet structure of separator and the standpipe structure of top turning, thus inhibiting the coking process.