Funny vessel design with level gauge! 1

[takiyasamsama]

This sounds funny to me but is there any such thing where the level gauge is connected between bottom head (top of bottom) to the shell. In fact what sounds funnier to me is that the bottom nozzle also serve as an outlet connection. Have a look at this picture:

Is there any vessel design like this? The reason the level gauge is at the bottom is that the requirement by client is to make sure the vessel is fully empty and they dont want a deadstock left inside the tank, it means complete drain and is indicated by the level gauge.

 

[enderlord]

What is the purpose of this vessel?

 

[LittleInch]

What is N3?

If this is a drain then I can see why they would want / need this so that the lower part of the level guage is not always full to the level of the bottom of the tank or just above.

It is not usual to connect the bottom part to a normally flowing nozzle as this distorts the level reading, but as a drain to drain off the level guage and then isolate it again so that any liquid in the tank is measured seems Ok to me.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EmmanuelTop]

This arrangement is not uncommon - please note that a dedicated instrument nozzle must be provided on the vessel instead of using process outlet piping connection. This is particularly important in your case where you have a 2" branch installed on the 3" main line (which is just one nominal size larger), so level-flow interference is almost certain. The higher the flowing velocity, the more erroneous/erratic measurement will be.

Dejan IVANOVIC
Process Engineer, MSChE

 

[EmmanuelTop]

I could not find any relevant standard that allows instrument taps in the vessel outlet piping. Here are some online resources:

http://igs.nigc.ir/STANDS/IPS/c-in-140.PDF

http://igs.nigc.ir/STANDS/IPS/e-in-140.PDF

http://www.red-bag.com/specificatio...design-specification-for-instrumentation.html

http://www.omega.com/literature/transactions/Transactions_Vol_IV.pdf

http://www.pacontrol.com/download/BASIC-INSTRUMENTATION-MEASURING-DEVICES-AND-BASIC-PID-CONTROL.pdf

http://piyushpanchal2007.mynetworksolutions.com/images/2._LEVEL.pdf

http://www.driedger.ca/ce6_v&t/Ce6_v&t.pdf

Dejan IVANOVIC
Process Engineer, MSChE

 

[takiyasamsama]

It is a simple vessel for a pre-coat purpose. basic operation as required is that the vessel will start mixing the ingredient and transfer to the filter press machine then recirculated back into this vessel and keeps recycling up to a certain period of time. After the cycle has completed, the vessel is intended to be empty out through (N3) nozzle as in the diagram.

I questioned my process team, as this design was proposed by the process team. However my proposed design was to connect the level gauge between the nozzle as normal vessel did because whatever is left inside the tank will be drained out completely so I dont think it should be monitored. Again that's just my opinion.

 

[takiyasamsama]

Dear EmmanualTop,

From your explanation I understand that an instrument connection shall not be interfere with a process connection, correct?

 

[georgeverghese]

Not usually done, but this is sometimes done for operational reasons. However, if there are solids in this tank, the drain line could get blocked and the LG reading may be in error - if so, try using a top mounted ultrasonic level transmitter as a backup indication if this is critical.

 

[takiyasamsama]

georgeverghese, I've been thinking the same as well. With all the draining purpose, the line could get blocked by the mixture inside the vessel.