Pre-distillation column pressure difference issue
Thread Content
One of the reasons for corrosion in the pre-distillation tower is an excessive pressure difference in the medium-pressure system; a factory reduced this pressure difference from 0.2 MPa to 0.06 MPa, which led to a reduction in corrosion. What pressure difference does 0.06 MPa refer to? Can increasing the secondary air pressure achieve the same effect?
The cause of corrosion in the pre-distillation tower shouldn’t be related to the pressure difference in the medium-pressure system, right? But it is related to the pressure difference of the pre-distillation tower. If the pressure difference is high, it indicates a large gas flow rate and high resistance, which can lead to erosion corrosion. The medium-pressure system has many devices, and there are numerous factors that can affect the pressure difference; it is necessary to calculate the flow area for each section in order to determine where the bottleneck lies Then, corresponding modifications must be made to eliminate the problem of high pressure difference. Simply increasing the secondary air pressure will not be effective.
It is stated that the corrosion of the packing in the upper part of the pre-distillation tower is a result of oxygen-deficient corrosion, due to the high pressure in that upper area (around 19 kilograms), with the secondary air not reaching that section but going straight to the secondary separator.
During normal operation, as long as the first column always has a liquid level and there is no air leakage, the vast majority of the air will not leak into the second column. In the case of oxygen-deficient corrosion, it is not just the upper filler that gets corroded; rather, all areas will be corroded. Therefore, it is recommended to look for other causes for the corrosion issue of the upper packing.