流動接触分解に関する研究 (V)

触媒の再生および最適粒径分布について

抄録

The recent studies on the catalyst regeneration and the optimum distribution of the catalyst are reported in this paper.
One of the difficult operations experienced in the catalyst regeneration is the secondary combustion of carbon monoxide in the regenerator. This reaction, or after-burning as it is generally referred to, is extremely exothermic and the resultant temperature rise is so great in an instant that the regenerator interior is remarkably damaged.
The methods of preventing this after-burning are discussed as follows:
(1) It is recommended to keep the CO₂/CO ratio as low as possible. For example, reduction of CO₂/CO ratio from 1.3 down to 1.2, or reduction by only 0.1, resulted in temperature drop of regenerator by 22°C (or 40°F), in which a considerably safe operation should be expected.
(2) By tracing the location of after-burning, it was found around the outlet of the primary cyclone toward the secondary cyclone, or around the cyclone installed just above the overflow well of regenerated catalyst of low carbon content and the cyclone near by the regenerator shell. Therefore, it is essential, to improve the distribution of combustion air throuth the regenerator grid so as to reduce the locally higher oxygen content.
The optimum distribution of particle-size shall not be precisely determimined neither by the experiences of plant operation nor by laboratory scale experiments. However, it was found that the optimum distribution decided from the standpoint of fluidization was identical with that decided from the standpoint of the catalyst regenration, and most satisfactory results were obtained in the catalyst of the following particle-size distribution:
0-40 microns 5-10wt%
Above 80 microns 10-20wt%