4 replies to this topic

[Cwsrt]

Hi, good day to everyone!

I'm searching for a procedure on how to clean our sulphuric acid storage drum. Our plant's 98% H2SO4 drum is a horizontal drum with a capacity of ~1900 L. It was reported that there is an accumulation of sludge in the ower portions of the drum which prompted the opening and cleaning of the drum. A small amount of acid (around 2 inches high) was retained in the drum along with the sludge.

I was thinking of diluting the Sulfuric acid first before trying to inject any basic chemical into the drum. Will this be a good first step in removing the acid?

What chemical do you recommend in neutralizing the acid drum? NaOH? ammonia?

My main concern is the heat release upon addition of water and/or the alkaline species. Can this issue be addressed with the rate of dilution/neutralization?

Lastly, what parameters can we possibly use as an indication of the "endpoint" of the cleaning process? Will the drum pH suffice?

Thank you in advance for your support!


-CWT

Edited by Cwsrt, 24 October 2012 - 04:34 AM.

[breizh]

CWT,
Consider to use Soda ash or Lime .
Don't forget a full set of PPE .
http://www.google.fr...iw=1110&bih=592
Breizh

Edited by breizh, 24 October 2012 - 07:02 AM.

[S.R.Shah]

CWSRT,

Please do not try to dilute 98% Sulfuric Acid for cleaning
1.Generally 98% Sulfuric Acid is stored in MS Tank.MS shall corrode quickly with Dilute Sulfuric Acid
2. Heat of Neutralization is quite large

Please check Corrosion resistance of tank MOC with any method of cleaning and then apply.You can check with Sulfuric Acid Manufacturer

SRShah

[S.R.Shah]

Dear All;

I came across Sulfuric Acid Dilution or Concentration or Concentrated sulfuric Pumping by Air Pressure but I never came across such situation.


Can this Sluge transfer to other tank or vessel by air pressure or other method from bottom.If such problem occurs frequently,LArge size drain valve to tank should be kept as standard Procedure for desiging Sulfuric Acid Tank.

I have gone through the link given by Breizh particularly thread of Acid Neutralization.

In my view neutralization with alkali also evolves heat of neutralization and Dilution.

Our learned Members can give more precise procedure with required precations.

SRShah

[kkala]

1. I agree with S.R.Shah. In the Phosphoric Fertilizers Plant (~1978) we drained 98% H2SO4 carbon steel pipes and then rinsed them internally with water to prepare them for maintenance. A similar way out for the present case is to remove practically all 98% H2SO4 from the drum without dilution (or even neutralization), then strongly rinse it internally with water to remove any remaining traces of acid. Otherwise we would not be certain that the drum has not been corroded somewhere, which would result in its visual inspection (plus thickness/welds check) to have peace of mind. Even if the vicinity area is not hazardous, it will be so temporarily during water rinsing, due to H2 created by diluted acid reaction with steel.
2. Way to remove sludge and 98% H2SO4 has been proposed by S.R.Shah. Besides, assuming that the drum has a manhole (or manway) near bottom line, you can open it and try to remove 98% H2SO4 / sludge out by a peristaltic pump, careful siphoning, or even mechanical means. Following notes could be useful.
2.1 Add H2SO4 into H2O (slowly and with agitation), not H2O into H2SO4; http://en.wikipedia....i/Sulfuric_acid '> http://en.wikipedia....i/Sulfuric_acid - Chemical Properties.
2.2 98% H2SO4 had accidentally fallen on the floor of empty phosphoric acid CST reactor (1977). We removed as much as possible without damage using brooms; then we threw Na2CO3 for neutralization and later water; the elastomer covering the floor was partially damaged (during reaction for H3PO4 liquid temperature was 80 oC).