The double-flange level gauge experiences large fluctuations
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The double-flange level gauge installed at the bottom of the re-refining tank in catalytic cracking units experiences large fluctuations when the ambient temperature is low, with the level changing by 5–13 units within a few seconds; the normal level range is between 40 and 80. There is basically no problem when the lowest temperature is above minus eight degrees. If the ambient temperature remains low, especially below seven or eight degrees below zero, this problem will occur. First, it should be noted that the process conditions remain unchanged and there are no external disturbances. The upper and lower pressure measurement points are at around 10 meters apart, but the silicone oil capillary is relatively long and has several coils stacked together; the heating at the base of the double flanges is in good condition, while the capillary itself does not have any heating. Other double-flange level gauges do not have this problem. The last time it was taken apart for inspection, no blockage was found; it worked fine after being reassembled. Now, with the low temperatures, it’s happening again
This is really hard to solve; let’s change the table.
I think it’s still a heat tracing issue; check it carefully. If that doesn’t work, try replacing the transmitter.
Provide heat tracing for the capillary; electric heat tracing will also work, and it will definitely solve the problem. Please reply to me once it’s solved
Conditionally, switch to a new gauge first and give it a try.
Installing a heating tape around the capillary should be able to solve this problem
The regular double-flange type is not made of low-temperature silicone oil; the order was placed incorrectly. If the gauge is not replaced, the only option is to provide light heating for the capillary, and even that heating should be mild.
I’m facing the same problem; I attribute it to silicone oil. Although the temperature doesn’t reach the melting or boiling point of silicone oil, over time all the silicone oil I have started to thin out.
We have encountered situations similar to those described by the original poster before; one issue is related to insulation or electric heating, and another situation arises when double flanges are in use for too long in harsh working conditions, which causes the diaphragm of these flanges to harden and lose its elasticity :-(
Check your double-flange model; whether it’s an EJA or a 3051C, type C silicone oil cannot be used below 0 degrees.