In a vacuum distillation unit, why is it necessary to have multiple side streams taken from the vacuum tower?
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Isn’t the side-stream product from the vacuum tower fed as feedstock to the FCC unit? Why not extract it all at once? Why is multi-line extraction necessary?
It’s mainly because of the heat level, right! That’s what I think
Not all side-stream products go through catalytic cracking; for example, those from the first stage undergo hydrodesulfurization, those from the second stage go through catalytic cracking, while those from the third and fourth stages are sent to the cold wax extraction unit.
It is still necessary to remove the excess heat; this is the key to energy savings in atmospheric and vacuum distillation.
Multi-line extraction takes into account the thermal balance of your tower. Do you know the three types of balance?
Material balance, phase balance, thermal balance?
That’s right; the purpose of extraction and reflux is to maintain the three balances within the tower
Wax oil usually accounts for 30%, with the rest being vacuum residue
Not all side-stream products go through catalytic cracking; for example, those from the first stage undergo hydrodesulfurization, those from the second stage go through catalytic cracking, while those from the third and fourth stages are sent to the cold wax extraction unit.
Increasing the wax oil recovery rate means that the fraction at 500°C is completely removed; this is related to cost calculations