Cleaning a chemical tank
Cleaning a chemical tank
(OP)
I have a tough cleaning job. The storage tank is filthy with food grade oil; the flash point is extremely high. The new product must contain no more than 40 ppm water. The storage tanks are thin-walled tanks originally used in a dairy. Steam cleaning is out because of the water and also because oils with a FP of 46 C won't be very impressed by steam. Then again, I heard of our tanks described as pop cans so vacuum failure is a major concern.
Originally, I suggested using the product and pumping it through the tanks after reaction to form product and filtration but this was rejected.
Now, an engineer is suggesting having a guy climb in the tank with soap and water to mechanically clean the tank.
Any ideas?
Originally, I suggested using the product and pumping it through the tanks after reaction to form product and filtration but this was rejected.
Now, an engineer is suggesting having a guy climb in the tank with soap and water to mechanically clean the tank.
Any ideas?





RE: Cleaning a chemical tank
What about a caustic/detergent wash/soak to degrease, then drain the tank and water flush (use a pressure washer) to remove the caustic.
To dry, put someone inside the tank to rag it out to remove the bulk of the water and then use nitrogen/dry air purging to remove the moisture content. Pressure cycles would be good, but it sounds like your tanks aren't up to much.
You can get a dew point meter to test the vented gas for moisture content and therefore determine when the tank is sufficiently dried
To speed up the drying, you could have the tank wrapped in heat blankets (the type used for weld stress relief) in conjunction with the purging, or you could hire a heater for the nitrogen/air depending on how much you are prepared to spend.
RE: Cleaning a chemical tank
RE: Cleaning a chemical tank
Contact some people like AIMM who have the equipment to tackle the job from several angles.
You can rent the tank cleaning nozzles.
You can use a foaming system instead of pure liquid.
If the flash point of the oil is 46°C it is going to be had to get the cleared for vessel entry without a lot of work and special gear.
If draining is problem add 5" of water and make 3" hot tap for a draw off nozzle.
http://aimmtechnologies.com/services.html
RE: Cleaning a chemical tank
RE: Cleaning a chemical tank
So long as there is no safety concern with entering, this method is 100% certain to get it as clean as you desire.
best wishes,
Sean
RE: Cleaning a chemical tank
The next tank may be more challenging since the oil is pyrophoric and may burn when exposed to air.
RE: Cleaning a chemical tank
<a href="http://www.cpel.com"]FRP Large Tanks</a>
RE: Cleaning a chemical tank
1. Try a solvent with a high vapor pressure like EtOH that you could circulate through the tank through a cleaning nozzle. When the thick oil is removed you can then steam out the solvent. Of course this option presents you some new challenges to deal with such as handling the solvent and disposal/recovery.
2. Flush tank with new oil until it meets specs. Then you just have to find outlet for the contaminated oil.