Chunxi Lu

A Historic Review on R&D of China’s FCC Riser Termination Device Technologies

Abstract Fluid catalytic cracking (FCC) is a dominant refining conversion process in China’s most refineries. After decades of development, China has already become one of the major FCC technology licensors in the world. In this review, the research and development (R&D) activities on FCC riser termination device (RTD) technologies in China are reviewed and discussed. Emphasis is put on the R&D of a series of advanced RTD technologies led by China University of Petroleum, Beijing, which initiated in the early 1990s when more and more China’s FCC units chose to process more residue feedstock. Followed by the guideline of three “quick”s and two “high”s, two early types of RTD systems with coupled zones for gas–solids centrifugal separation and pre-stripping were developed and applied successfully in commercial units. Significantly reduced yields of coke and dry gas due to restrained post-riser reactions and satisfactory particle recovery efficiency were achieved. These were the fender-stripper cyclone and vortex quick separator systems designed for external- and internal-riser FCC units, respectively. Later, further improvement efforts led to the development of another two RTD systems, i.e. the circulating-stripper cyclone system for external-riser units and super vortex quick separator system for internal-riser units. By now, nearly 50 applications were commissioned with a sum FCC capacity of 40.0 Mton/a, nearly one-third of China’s total FCC processing capacity. Besides, other research efforts, such as the geometry optimization efforts on LD2 type separator, the studies on RTD for down-flow riser FCC units, and the idea of non-disengager FCC unit are also discussed in this review. To accommodate to degraded feedstock, more stringent environmental regulations and new FCC process technologies, future R&D efforts on RTD technologies should be put on improvements to further satisfy the three-“quick”s and two-“high”s requirements with changing FCC operating conditions and different process requirements.

A novel gas-solids separator scheme of coupling cyclone with circulating granular bed filter (C-CGBF)

A novel gas-solids separator scheme of coupling cyclone with circulating granular bed filter (C-CGBF) was proposed. The influences of the operating regimes, the inlet dust concentrations and the inlet gas flow rates on the scheme were investigated in a pilot-scale cold-model experimental apparatus. The pressure drop and the collection efficiency were measured and analyzed. It was shown that, differing from that under the fixed bed (FB) operating regime, the pressure drop tended to assume a steady state after an increasing period under the moving bed (MB). Experiments under the MB revealed that stable/high collection efficiency, typically exceeding 95%, was achieved with considerably low pressure drop. The dust hold-up in the built-in granular bed and the filter cake formed on the outer screen wall contributed to high collection efficiency, as well as increased the pressure drop. Furthermore, the individual contribution of the cyclone shell and the built-in granular bed to the total collection efficiency under the MB were investigated. The size distributions of the captured particles were also analyzed. The contribution ratios of the cyclone shell were around 80%, while the majority of the particles captured by it were larger than 10 μm.

Heat Coupling of Gasoline Upgrading and Fluid Catalytic Cracking Processes

Heat supplement is necessary for FCC gasoline upgrading processes to keep the heat balance of reaction-regeneration system, while excess heat would be removed in FCC process due to the processing of heavy feedstock. Combining gasoline upgrading processes with FCC process can realize the heat coupling so as to achieve the maximum energy utilization. In this paper, the heat balance calculations of a commercial FCC unit and a FCC gasoline aromatization process were carried out, and the feasibility as well as the way to accomplish the heat coupling for the two processes was investigated. The results showed that the coked aromatization catalysts could be heated to the desired temperature by the direct contact with the hot regenerated FCC catalysts. The pilot experiment and CFD simulation was carried out to investigate the flow behavior and heat transfer of the direct coupling system of FCC process and FCC gasoline aromatization process. The results indicated that the well-mixing and efficient heat transfer between FCC catalysts and aromatization catalysts, as well as the sufficient regeneration of aromatization catalysts, could be achieved at appropriate operating conditions.