Level measurement of Sulphuric acid tank 3

[operationsengineer]

We a operating a 400 ton/day Urea manufacturing facility. At our water treatment section we are experiecing difficulity in maintaing level glasses and level switches of sulphuric acid(98%) tanks.
There sensing lines get chocked by sluge and we have to mesure the level by dipstick. One of our tanks overflowed due to overfilling caused by wrong level.
We would appreciate help on maintaing sulphuric acid tankks, Altrnates for reliable level measurements & standard arrangement for level measurement / tank protection.
Zaheer Anwar(unit manager utilities)
FAUJI FERTILIZER COMPANY> PAKISTAN

 

[butelja]

How about a bubbler differential pressure level transmitter?

 

[MJCronin]

ops guy,

An excellent guidleine for the delivery, storage and transfer of Sulfuric acid is on the internet. It was developed by "General Chemical":

See this link:

http://www.genchemcorp.com/pdf/tsr5078.pdf

Generally speaking, either a manometer (bubbler) system, or a "weigh cell" system or an top of the tank mounted "ultrasonic" device are most often used. ( I recall that the company "Milltronics" has such devices.

You did not tell us about the concentration of acid and the tank material. Please post a response...

Your sludge may be from the acid consuming the tank walls ?!! ( a small amount of sludge is OK in a new tank)

Do you have a tank maintenance program and have you measured the wall thickness at the shell midpoint ??!!
Other sulfuric acid tanks have collapsed without warning....
Is your engineering field office downhill from the tank !!

Do you have a dessicant vent dryer installed ? These are highly recomended in order to prevent water ingress.

More details ....please

Good Luck..........



MJC

 

[saxon]

openg.,Have you thought of using a radar level sensor tied to a Level recorder/controller with high/high, low/low level alarms/auto shutdown with high/low automatic fill.

saxon

 

[C4Reactor]

Hi Zaheer,
Try radar level sensor. We are using it for corrosive service. Great stuff.

 

[Shy]

Try looking fo Ultrasonics measurement systems. These fit on top of the tanks and can be fitted without disruption on manholes/ flanges etc. There are a lot of Ultrasonic level and alarm measurement providers worldwide and suitable acid resistant hardware may also be specified. Try searching the

http://WWW for

nearest dealers of Ultrasonic measurement suppliers.
Hope this is helpful.

 

[ihg]

98% sulfuric is not particularly corrosive to steel, as it builds an insoluble ferrous sulfate layer. BUT if the tank breathes, and you dont have a dessicant dryer (or a dry gas makeup) you get a layer of dilute acid at the surface which is really corrosive. Suggest that an ultrasonic level transmitter will be a good solution. A dry nitrogen bubbler would also work if you have a cryo separation unit. Instrument air may not be dry enough to avoid corrosion.

 

[ElderX]

I recommend when you do the ultrasonic thickness test, that you perform a continuous scan at right angles to the phase lines ( around a horiz tank or up and down a vertical) as opposed to spot readings. This will assure that you don't miss localized zones of corrosion which is likely using the "hunt and peck" spot testing technique.