BM 100 in a refinery

In the High Vacuum unit of a refinery a displacer was used to measure the level of a vessel containing hot wax. Now it is replaced with a BM 100 A
This displacer is mounted in an outside levelchamber. The measuring range is only 300 mm (12") The temperature of the wax is approximately 150°C and there is a slight overpressure. There is some water in the installation. This water collects in the top of the levelchamber as this is the coldest spot in the installation. The waterdroplets fall on the hot wax and the water explodes to steam. This causes that the displacer hammers to the top of the levelchamber. This hammering makes, that the displacer has to be replaced three times a year! Another point is that this displacer has been used to control the level. The controller is in the panel of the controlroom and despite the length of 250 meter pneumatic signal line, you see an enormous bump on the controller (yes this plant is still pneumatic)
A BM 100A was installed with a 50 µ coax sensor without dead zone. This unit works very good. So good that the customer decides to purchase the second BM 100A for the same application within ten days after start-up.
Because of the excellent behaviour of the BM 100A it is possible to control much tighter than before, which means less valvemotion and valvewear. The savings per year for this installation are at about 4000 Euro on maintenance only.
We selected the coaxsensor without dead zone, as this made it possible to swap the displacer by the BM 100A without any modification on the levelchamber. We are not afraid of contamination for this application. As long as the wax is hot it flows like water. The sensorlength is 495 mm. The actual measuring range is 300 mm. In the attached figure you can see the actual signal strength.

Key Words: Level, TDR, wax, displacer, refinery

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