重油催化抑制结焦沉降器油气停留时间的数值模拟

 采用标量输运方程数值模拟了一重油催化防结焦改造后沉降器内油气停留时间的分布。结果表明，沉降空间油气停留时间分布曲线呈单峰形式；在忽略油气质量流率极小量，即油气质量流率小于10-3kg/s时认为不存在油气的情况下，由汽提段进入的油气主流停留时间大致为13s，最短约7.5s，最长也不超过60s；由粗旋料腿入口进入的油气主流停留时间约15s，最短不足6s，且几乎所有油气的停留时间都小于70s。油气在沉降器内总体平均停留时间约26s。对比尺寸近似的常规沉降器和FSC沉降器内油气停留时间分布发现，抑制结焦沉降器的平均停留时间较短，比常规沉降器缩短79.8%，比FSC缩短81.9%；预计防结焦改造后沉降器沉降空间结焦情况大为减轻。

NUMERICAL SIMULATION OF OIL GAS RESIDENCE TIME DISTRIBUTION IN A RFCC DISENGAGER AFTER ANTI-COKE DEPOSITION RETROFITTING

The residence time distribution of oil gas in the disengager of a innovated FCC unit was calculated mainly by numerical simulation with scalar transport equation. Totally, the residence time distribution curve of oil gas had one wave crest and the average residence time of oil gas was about 26 s. Under the suppose that the teeny mass flow rate less than 10-3 kg/s of oil gas was zero, the main flow residence time, minimal residence time and maximal residence time of the oil gas from the stream stripper were about 13 s, 7.5 s and shorter than 60 s, respectively. The main flow residence time, minimal residence time and maximal residence time of the oil gas from the dip leg of rough cut cyclone were 15 s, less than 6 s and shorter than 70 s, respectively. Comparatively, average residence time of this retrofitted disengager was 79.8 % and 81.9 % shorter than those of usual disengager and FSC disengager, respectively. The coke condition of the innovated FCC unit will be improved.