What is the difference in the bottom structure between a coking fractionation tower and a catalytic fractionation tower?
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What is the difference in the bottom structure between a coking fractionation tower and a catalytic fractionation tower?
The temperature inside the coking fractionation tower is lower; there is no catalyst. At the bottom of the tower, direct heat exchange occurs between the feedstock and the oil. The bottom section of the catalytic fractionation unit includes a superheating removal section and an oil slurry circulation system.
The bottom of the catalytic distillation tower is equipped with chevron baffles for washing the catalyst, while the coking distillation tower is connected directly to the feedstock
The bottom of the catalytic fractionation tower contains mainly slurry with solid particles; the liquid phase temperature is generally kept below 350°C to prevent coking. A herringbone baffle is usually installed at the bottom of the tower, allowing the slurry to flow back upward and downward as well as be discharged externally. The purpose of this reflux is to wash the catalyst out of the gas-oil mixture； The bottom of the coking distillation tower contains coke powder; there are also wedge-shaped baffles, and reflux occurs at the tower bottom. In one case, residue oil is fed to the bottom of the tower, while in another case, wax oil is used; it is also necessary to control the temperature at the tower bottom.