May 11, 2010 at 11:35 pm #2678
Do you’ll have a feed surge tank or drum before the feed enters the Frac bottoms or heaters?
My tank level gauge failed and I am planning on installing a new radar level by opening and changing out a 5X6 ft man-way on top of the tank. Have you heard of anyone opening or changing out a live nitrogen purge 450 deg pitch tank top man-way? the tank operates at 420-460 deg at approximately 3-6 inches of water column.
May 12, 2010 at 11:50 am #5634
I would strongly recommend not installing the radar gauge on the tank manway containing hot resid and in the presence of nitrogen. The risks are high due to the possiblity of resid ignition on loss of nitrogen flow or intrusion of air. In addition, the nitrogen poses a suffocation risk to workers.
A more prudent path would be to consider installing a gamma level detection device, which can be done without shutting down the feed surge tank or opening it while in service.
Best regards – Mitch Moloney
May 13, 2010 at 5:59 pm #5627
Thanks for the information; the device is a Rosemount 5600 series
The Rosemount 5600 uses state-of-the art microwave technology to get highest reliability and precision. It measures the level of liquids, slurries, and solids. The transmitter operates in a wide range of temperatures, pressures, vapor gas mixtures, and various process conditions. (We are already using the series in the tank field and it has been very reliable so far).
The plan is to perform the job under Fresh Air (full face supplied air w/ escape pack-protection for vapors), bunker gear (jacket, overalls, boots) protection from heat, Full body harness and tie off – protection from falling. I plan on using 2 cranes, (1) to station the new manway with device and all gaskets ready to install approximately 10ft from the workers and (1) crane to lift the old manway off the tank.
The N2 supply is on pressure control to the tank and an additional amount of N2 will be added to maintain a positive pressure and prevent air from entering the manway. I am working with the Safety & Fire dept to address any concerns.
Please advice on any Safety concerns or potential hazards.
May 19, 2010 at 1:03 pm #5617
I agree with Mr. Mitch, the risks are too high.
In the DCU I worked some years ago, we had a surge tank that was damaged in a fire.
While the tank was being repaired we were able to run the coker without it. Our fractionator had a larger diameter at the bottom, which helped, along with a closer control on the level in the vacuum and fractionator bottoms.)
After the tank was repaired, it was not used again as a surge tank.
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