Closed hopper exhaust gas
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In UOP’s third-generation continuous reforming process, the exhaust gas from the catalyst regeneration lockhopper is designed to be discharged before the reformate air cooler; some have suggested moving it to behind the air cooler, as this could help reduce pressure fluctuations in the reforming reaction section. How should this issue be understood? ? I would appreciate some guidance from an expert.
The temperature for venting air during shutdown is around 150 degrees, with a volume of approximately 1000 Nm3； Logically, it should be cooled to room temperature again before air cooling. The values remain the same before and after air cooling; therefore, there should be no difference in the impact on the pressure of the reforming reaction, in my opinion
Indeed, an exhaust volume of around 100 liters is very small compared to the oil and gas after the reaction; cooling it through air cooling has no impact on the pressure in the high-pressure tank.
The advantage of switching to air cooling is that the pressure during regeneration is low, which facilitates regeneration and allows for a reduction in the severity of the reaction conditions.
The regenerative charring pressure is a factor that takes various aspects into consideration； High pressure helps to increase the coking rate, but is not conducive to catalyst drying; the opposite is true for low pressure. Additionally, the pressure difference before and after air cooling is at most 0.3 kg, and the difference between 0.27 Ma and 0.25 MPa in the pressure of the regenerator has a very minor impact.
By this impact, he means that the closed hopper intermittently releases gas in front of the air cooler (gas is released only during charging)； But I agree with you; this volume has no impact on the reaction pressure, only a very minor one ； It is not recommended to move it after the air cooling stage; this gas is at 140–155°C, and according to the design principles it should be cooled before the air cooling process. Placing it after air cooling will instead cause temperature fluctuations (although the impact is minimal, as can be seen by considering the flow rate)
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The gas volume discharged from the closed hopper is very small compared to the amount of circulating hydrogen, so its impact on pressure is minimal； However, a high discharge temperature is a reasonable design before discharging it into air cooling.