Sloped Cylindrical Tank Level 2

[JoeChem]

Greetings,

I am putting together a process design package for a batch plant expansion. We need to install a multipurpose cylindrical 40,000 gallon horizontal storage tank. To minimize holdup we are planning to slope the tank.

We would like to measure the liquid level in the tank so we know if there is insufficient material left for a full batch. We can make partial batches just need to know when we have to. Being a multipurpose facility, there will often be a need to empty the tank and clean in preparation for storing a different raw material.

Struggling with how best to measure the level given the complex relationship between liquid level and volume. Personally, I am leaning towards a simple sight glass but others are considering various types of level instrumentation as they are uncomfortable relying on someone in the field to verify.

Does anyone have any experience with level instrumentation on a sloped horizontal tank? Any pointers, guidance, etc. will be greatly appreciated.

Thanks in advance,

JoeChem

 

[sshep]

Hey Joe,

It wasn't really clear what you were asking because the level measurement has nothing to do with the volume, rather the volume is a function of level: V=f(L)=f(L, cone angle, diameter). To get volume isn't really that complicated of a formula, and all you really need is to measure the level. In my opinion a sight glass is extra work for the operator- if it is important, give him a break and automate the measure.

For the choice of level measurement then it is a simple question: does the SG change? If the SG=constant, then the easiest is a dP cell. If the SG changes then the easiest is some sort of float.

best wishes,
Sean

 

[JoeChem]

Sorry - I did not choose my wording well.

The real question I had is how to relate tank level to volume. If the tank is horizontal the level-volume relationship is not that involved. For a sloped tank the relationship is more complex.

The tank will be multipurpose - so the SG will change with different raw materials.

I suppose we could calibrate the level instrument with data points from known fills and try and curve fit to get a level-volume relationship. Would have to do this for each individual raw material.

I guess it is obvious I am not up on level instrumentation details.

Thanks for the feedback.

JoeChem

 

[Latexman]

Why not a vertical, dished head tank? They drain naturally (no slope), so no jumping through hoops.

Good luck,
Latexman

 

[Mech85]

Hi Joe,

There is an online calculation for and inclided cylinder at the following LMNO Engineering webpage

http://www.lmnoeng.com/Volume/InclinedCyl.htm

There is alos a "Tilted cylindrical tank volume" online calculation at the following webpage.

http://planetcalc.com/1442/

Hope this helps

 

[jamesbanda]

I've never seen a sloped tank as the type you are looking to install. Surely the structural supports and connections will be problematic..

i cannot help but think that you maybe better installing a vertical tank with easier foundation installation etc..

james