HFA Settler Interface Level Measurement

[GGMurphy]

I want to measure the interface levels in a Hydrofluoric acid settler. Due to the nature of HFA a non-contact measurement device is strongly preffered. So far the only non-contact solution that appears to be capable of measuring the various interface levels is a Vega nucleonic density measurement device. It produces a density profile of the vessel from which the interface between the HFA - Emulsion Layer - Hydrocarbons can clearly be seen. The trouble with this method is the obvious risk surrounding radioactive material and the high cost (£60k).

Can anyone suggest a alternative method or a nucleonic device that might be less expensive?

 

[ProjEngr]

We are in the process of installing an Ohmart source and detector on an HF column in our unit. The total installed cost looks to be about $20,000. The source and detector only cost around $7,000.

 

[GGMurphy]

Which model are you using? Vega is the UK name of Ohmart so I have access to their models. Is this for an interface level application?

 

[ProjEngr]

Source: SH-F1-20-A45-M3-S00-L0-P0
Detector: LJTH-36-V1-H0-M0-S00-P0

We are using this to detect the level in the HF regenerator column, so this is not an interface. We have tried using the internal radioactive type densometers in our settlers, but they were very problematic. These were older models that had cables to bring the source up and down inside the vessel.

Currently in our (2) acid settlers we are using the Fisher DLC3000 level indicator with a float column to give the interface between HF and HC. Looking at the maintenance record, the only thing we do to them are recalibration (every few months.) This could be another option for you.

 

[GGMurphy]

Are there not any serious safety implications on using the Fisher device with it being in contact with the process? Is there a risk involved when calibrating it also?

Our current device is a Berthold radioactive density measurement device that like yours send the source and detector up and down dry wells via an Enraf servo motor. It has worked well for 15 years but now its reliability has come it to question as it has become problematic.

Cheers for your assistance.

 

[ProjEngr]

The level bridal has connections to flare, nitrogen, and isobutane flush. Also, our unit safety requirements state that a full acid suit (PPE) must be worn in this area. So calibration is a pretty safe operation.

The Fisher DLC3000 has a seal on it that segregates the electronics from the process. All wetted parts are monel. We have had this instrument in service for over 5 years now. Originally, it was a 249B caged displacer with a pneumatic transmitter on it. We have since converted over to Honeywell TDC3000 DCS control, and that's when we put the DLC3000 on the existing gauge chamber (about 1.5 yrs ago). Good luck.

http://www.emersonprocess.com/fisher//products/tour/fmi.html