Tank farm - Liquid levels

I am working on a project where there will be 160 tanks with upto 16,000 gallons of liquid in them. I am planning on trying to measure the level with a pressure transmitter or transducer.

• Sensor Recommendations
• Detect which tanks have been manually opened and compare to the operator selected by sensing the change in level.
• Separate circuit for High High Level pump shut down (PLC based?)
• Lot number history. (record of events for each "delivery" of product. IE lot 12345678 Offload date 1/2/07 JFG, tank: 1234 16000 Gallons at: 22:10, tfr: 1/2/07 @09:00 to Mixer: 2 by: BDH 10,000 gallons, tfr: 1/2/07 @11:00 to Mixer 1 by JFG 6,000 gallons. etc.
• I would like to be able to recite the history of what was put into each tank.
• Each gallon of product would have a lot number that told it's history of where it has been how it got there, who put it there, what time/date, and any other process variable that was available.
• The system would be connected to a PC where the history could be stored or a dedicated hard drive.
• PC based HMI control by thr operator.
• 25 to 30% of the tanks are located in explosion proof rated areas. So the sensors there need to be barrier or exp rated.

Oh, and start up is expected in March for line 1 of 3.

BrianAth said:

measure the level with a pressure transmitter or transducer.
Sensor Recommendations

Click to expand...

Level:
Do you have bottom access for pressure transmitters? What's the connection? spud flange? NPT threaded?

Are the low access points different than the tank's outlet?

Do you have top access for running a line to the low side of a DP for those tanks that are not vented directly to atmosphere?

A tank farm that size and number, probably the tanks on pads, not legs.

How are the tanks vented? directly to atmosphere?

Depending on what's in them, many tanks have a weigthed vent that holds up to about ±0.4 psig before it releases. That build up in pressure will distort all your readings, all the more so on tanks with chemicals with high vapor pressures. Tank fills will appear to overshoot (possibly tripping the high limit: Unloading a tank will undershoot. A sense line from the top of the tank sensing vapor/blanket pressure is needed.

I happen to use Siemens DS III (DS 3) for head pressure - built-in keypad, display, so a HART communicator is not essential. But on a project this size, I'd go HART in a heart beat. I/S.
http://pia.khe.siemens.com/index.asp?Nr=2114

There's a debate about 3 valve manifolds on DPs for tank farms, I like a manifold for start-up, zeroing, bleeding the lines, and for isolating the transmitter if necessary, but some owners find that the equalizing valve mysteriously gets opened (no DP = zero level and the low legs fills with liquid and needs to be drained) or one of the sense legs gets shut off. Gremlins in the tank farm.

High level:
Float switch for clean stuff an I/S barrier.

Or capacitive is a favorite. I use the Siemens CLS-200 because it works on about 97% of all the hydrocarbons I've run into.
http://pia.khe.siemens.com/index.asp?Nr=4924

BrianAth said:

Detect which tanks have been manually opened

Click to expand...

What kind of manual valve?
Quarter turn where a microswitch could be installed? Even a quarter turn valve can be opened partially, though, without tripping a limit switch.
A flow switch in the outlet line?

No problem. What is the operations budget? Any OT?

I am currently looking at doing a project for our tankfarm, but it's not quite on your level. I only have around 50 tanks to monitor the levels. Instead of using pressure transmitters, I was planning on using radar transmitters from K-Tek. I haven't made it to seeing how much they are going to cost, but I've been really happy with K-Tek products throughout the plant.

I had a couple salespersons stop by a couple weeks ago and show me honeywell's new line of wireless data acquisition and monitoring equipment. I was considering the XYR5000 series due to the fact that it is getting a lot more expensive running wires throughout the plant. Especially when a tank farm covers a lot wider area.

Just some food for thought.

If you need high accuracy then radar level transmitters would be the best devices.

If you will be monitoring and controling the output from the tanks this will be a major project. Maybe a system integrator maybe necessary. There will be a lot of design and progeramming for a system of this size.