measuring salt level in salt saturator??

[cardosocea]

Hello,

I have an application where I need to measure the salt level/volume in a salt saturator.
This is a fairly large tank where we load bulk salt and have a tap on ballcock to keep the water level stable inside the tank.

I've looked around at how to measure the salt level/volume in this tank but there doesn't seem to be any good options for it. Has any of you had a challenge like this to solve that can share some wisdom and experience with me?

 

[JesperMP]

Loadcells ?

 

[drbitboy]

Do you mean the level of undissolved salt at the bottom of the tank?


If yes, and possibly even if not, I think JestperMP is right i.e. loadcells. Even if the formula is a poor model, it should be easy to calibrate.


Does the temperature of the system vary a lot, or is the residence time short? Either of those might affect the mean salt concentration in the brine and therefore the calibration.

 

[Ken Moore]

I have used YO-YO type in the past, not great but okay performance.

https://www.bindicator.com/p/continuous-level-measurement/yo-yo-series-level-indicator/

 

[cardosocea]

Loadcells ?

That would be ideal... and actually used elsewhere on site, but this is already in place and it's a fibre glass flat bottomed tank. Load cells would be an expensive endeavour now.

Do you mean the level of undissolved salt at the bottom of the tank?

Yes. the goal is to measure the undissolved salt despite the water content that is, for the most part, level at the same place.

I have used YO-YO type in the past, not great but okay performance.

https://www.bindicator.com/p/continuous-level-measurement/yo-yo-series-level-indicator/

I'd never seen that... although it's a solution for this.

 

[danw]

Two possibilities.


1. Capacitance
I saw a Siemens CLS100 point level switch detect the difference between water and the resin used for water softening. It was inserted into the side of the tank and switched when the salt level fell below the installed level. It had an analog (pot) sensitivity adjustment.



The LC300 is a top-mounted, continuous level sensor with a contact probe that uses the same sensing technology as the CLS100, so it might work. I suspect it would take a demo to show whether it works or not. But even if it works, you'd have to be aware of not crushing or bending the probe when filling the salt.


2. Guided wave radar (GWR)

GWR might or might not make the salt measurement because it is used for interface level measurements. I'm not sure how the changing dielectric of the water as it saturates would affect the measurement.


Same caveat on not crushing or bending the probe when filling the salt.

 

[drbitboy]

That YO-YO seems like a good option, but it may need proper design (monofilament line? rinsing spray?) to keep the brine out of the head.



A lot of ideas on The Google:


https://www.google.com/search?q=level+measurement+solid+liquid+interface


I like the vibrating rod that tells when the level is above or below a certain point, but maybe an analog solution is required.


Is the brine clear enough that the position of a beam of (laser?) light hitting the brine-salt interface could be detected by a camera?

 

[cidchase]

"Silo Patrol"

Made for you

https://www.monitortech.com/product_c_c_sp.shtml

 

[I_Automation]

Before any were commercially available I designed my own system for this. (Mid 90's)

I had a rod protruding above the tank with a linear encoder to tell how high up it was from zero and the bottom had a plate that would sit on top of the solids in the tank. The plate had a coned top so it wouldn't get stuck if the solids came in while it was down.

I added a small motor to lift the rod to the top and lower it freely, recording the level when the rod stopped moving when it sat on the solids.

Very similar to the Yo-Yo (wonder if they saw mine & stole my idea?) but, as mentioned above, that thin line I would not trust to break in an industrial setting.

 

[Bob O]

Here's another company with most likely a similar product shown above.

https://www.binmaster.com/

 

[Oceansoul]

Hydrostatic level pressure transmitter at the bottom measuring the brine level in the tank. Vibrating fork point level indication (ours are e&h) in the side of the take for hihi hi Lolo bulk salt level.

Usually the tapping points are already part of the tank.


Water treatment works, with many Forbes salt saturators on site.

 

[Tom Jenkins]

In the wastewater world there are interface detection instruments that are used to find the interface between settled sludge blanket and "clear" water. Some work by detecting ultrasonic echoes from the density change between the water and sludge. I don't have any brand-specific recommendations, but a search should locate several.

 

[cardosocea]

Hydrostatic level pressure transmitter at the bottom measuring the brine level in the tank. Vibrating fork point level indication (ours are e&h) in the side of the take for hihi hi Lolo bulk salt level.

Usually the tapping points are already part of the tank.


Water treatment works, with many Forbes salt saturators on site.

How do you know how much is water and how much is salt in the hydrostatic solution? I thought about that one but am not sure what the reading would be since there's always a level of water in the tank.

 

[cidchase]

It's a saturated solution, no??

"Looking in a copy of “CRC Handbook of Chemistry & Physics” 54th edition, Sodium Chloride has listed solubility of 35.7g per 100ml water at 0 Celsius and 39.12 at 100 Celsius."

From the Internet. Take it with a grain of salt...

 

[Saffa]

It's a saturated solution, no??

"Looking in a copy of “CRC Handbook of Chemistry & Physics” 54th edition, Sodium Chloride has listed solubility of 35.7g per 100ml water at 0 Celsius and 39.12 at 100 Celsius."

From the Internet. Take it with a grain of salt...

There will be salt that won't dissolve due to the water being saturated. The idea is that you add more salt into the tank than you need to make one tanks worth of saturated solution. Then as more water is added the bulk salt volume slowly reduces.

OceanSoul's solution is the way to do it. Or go with two conductivity point switches for high and low on the brine solution level instead of the hydrostatic if you don't need analog level.