Problem of catalytic thermal demolition of large blind flanges
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It was planned to remove the large blind plate from the unit yesterday, but the vent from the bottom of the distillation tower contained only oil. After checking the liquid levels, it was found that the remote sensor for the feed oil tank indicated 100%, and the same was true for the re-refined oil tank; at that point, both tanks were already feeding oil into the distillation tower via the vapor lift line! Therefore, the oil slurry pump is used to transfer oil to the crude oil tank through emergency discharge, thereby lowering the levels in both the crude oil tank and the reprocessed oil tank. At the same time, oil is discharged from the bottom of the distillation tower into the heavy residue tank; once there is no more oil in the bottom of the distillation tower, air is introduced. I would like to ask if there are any good methods to ensure that crude oil does not enter the distillation tower during the catalytic three-way circulation process ? ? It seems that to ensure accurate liquid level readings in all the important tanks, it is necessary to regularly check whether there is oil in the vent at the bottom of the distillation tower. I would like to ask if there are any other issues related to the three-way circulation process in this facility ? ?
How many platinum- and palladium-containing catalysts does a factory typically replace in a year?
Someone must always be on watch here to prevent oil cross-contamination caused by inaccurate liquid level indications!
1. During the three-way circulation outside the tower, the slurry moves up and down within the tower; in the two-medium flow process, it is best to ensure that both valves are closed, as it is difficult to guarantee that a single valve will not leak or fail to close properly. The original poster mentioned that it’s a newly installed device; although the leakage inside the valve isn’t severe, it’s impossible to be sure whether this is the cause ； 2. Assign someone to monitor the vent at the bottom of the tower; this venting allows one to determine whether there is oil present at the bottom of the tower. It is normal for the vent to contain both water and vapor. In the facility where the poster works, the vent at the bottom of the tower was not used for three or four days, with external circulation systems being used instead – which shows a great deal of trust in the instruments and valves ； 3. Critical instruments should be verified on-site, especially during oil reception; the liquid levels in the reprocessing tank and the feedstock tank have already reached 100%, which is quite concerning. If the tower is filled with oil, it is indeed dangerous.
During the three-way cycle, all the wall valves leading into the distillation tower are closed. The vent at the bottom of the distillation tower remains open and is checked regularly. Also, how does the vapor from your feed oil tanks and reprocessed oil tanks flow directly into the distillation tower? Won’t that prevent oil from being discharged from the vent at the top of the distillation tower? This definitely won’t work; the oil and gas need to be directed to another place
One principle is that without a steam seal for switching between the two units, oil cannot be fed into the fractionation tower. The risk of hot removal of blind plates is that hot air will enter the distillation tower. Installing a valve on the vapor line of the re-refining tank is a good approach; it can be used for a three-way circulation of the feedstock to the stripping distillation column.
The vapor from the top of our crude oil tanks and reprocessed oil tanks returns to the distillation tower, with no valves in between. . .
Currently, the vapor lines at the tops of the crude oil tanks and reprocessed oil tanks here lead directly to the distillation tower, with no valves in between. This is different from some plants where the vapor can be directed either to the distillation tower or to the slurry tank, and valves are present in those systems. Therefore, once these two tanks are full, the vapor goes directly from the vapor lines to the distillation tower
I know that, but can we be sure now that both tanks are full?
It’s confirmed that the tank is full. . . The remotely controlled gauge is inaccurate, and there is also a intermittent gurgling sound coming from the vapor line
It is a good idea to install a valve on the vapor line of the re-refining tank; this could be used for a three-way circulation of the material feeding into the fractional distillation tower. How is this to be used? Could a simple diagram be drawn to illustrate the flow process?