Combustible Liquid Splash Filling

[MementoMori]

Hello all,

My company is looking at putting in a new atmospheric aboveground storage tank for an organic monomer. The chemical is a Class II Liquid (100 F < FP < 140 F) and will be handled below its flash point.

The company has been receiving the chemical by rail and tanker, unloading with air pressure, and splash filling storage tanks for an extended amount of time. In reading the the relevant codes (NFPA 30, OSHA 1910.106) I have become aware of the potential danger of splash filling regarding static. I am particularly concerned about the potential for misting at the end of the unloading process as the line empties which may be flammable below the FP.

I anticipate pushback in proposing to modify the process. Perhaps with good reason since process changes seldom come without risk. A few concerns I have or that have been raised
-Back flow due to siphoning with a dip pipe or bottom fill connection. For a dip pipe, the antisiphon hole could become obstructed with polymer. Check valves can fail.
-Trapping pressure (from static head) in the fill line and having to disconnect hose connections at trailer. Would require a bleed system that could be prone to error.
-If unloading with air, the line will bubble compressed air through the bottom of the tank. This is still forming a fuel/oxygen mixture (my intuition is this would still be preferable to splash filling the whole time or a mist at the end.

Are my concerns about splash filling warranted in this case? Is anyone aware of accidents caused by splash filling specifically combustibles (not flammables)? I have seen a good bit for diesel but it is often coupled with switch loading from gasoline. It would make selling a change easier. Should the practice always and everywhere to be avoided? The codes do not seem to mandate bottom filling or a fill pipe for combustibles below their FP. Thank you for any input you may have.

 

[pierreick]

Hi,
Why don't you share the name of the monomer, it will save time for everyone?
My 2 cents
Pierre

 

[Latexman]

My guess is butyl acrylate.

Good Luck,
Latexman

 

[MementoMori]

Latexman, good guess but it’s acrylic acid. As an aside, I have read the BAMM manual and looked over their recommendations regarding tank configurations.

 

[pierreick]

Hi,
Read this document and you will get all the information needed for safe handling of AA.

https://www.petrochemistry.eu/sector-group/acrylic-monomers/

Share your design we will comment, I have some experience with GAA material producing Latex in Indonesia.
Note:
How is the exhaust gas treated? With compressed air you will have spills all over the place (severe burns) if sent to atmosphere?
How do you protect your tank in case of overpressure?
where is located your facility?
To me the safe way is to use a pump and to follow the recommendations in the document shared (numerous).
Page 32 of the document shared.
Pierre

 

[georgeverghese]

Is this AA doped with anti polymerisation agent (hydroquinone mono methyl ether)?

 

[MementoMori]

George, yes it is inhibited. Pierre, thank you I will look it over. It is interesting that the EBAM and BAMM safe handling manuals have slight differences. Lots of good information though. Regarding pumping, that is reassuring, I am also gravitating towards switching to pumping to unload. You are correct, the fumes can be rather severe. I have not seen indications of liquid spills from the venting. I imagine it is certainly possible, especially on overfilling. Presently the exhaust gas is vented to a location not exposed to regular foot traffic which is cordoned off during unloading. The tank will have a normally open vent sized for the fire case. There is interest in scrubbing. I would appreciate your feedback on the design but do not think I am permitted to share it.

 

[pierreick]

Hi,
Ok, be cautious and pay attention to what is written in the document shared.
An Hazop study is definitively required.
Pierre

 

[TiCl4]

MementoMori,

Be aware that OSHA may prohibit the transfer of flammable materials via air, depending on your plant's "classification".

To me, the definition is not clear on what types of chemical plants are covered and which are not. Can anyone elucidate?


1910.106(h)

Processing plants —
1910.106(h)(1)

Scope. This paragraph shall apply to those plants or buildings which contain chemical operations such as oxidation, reduction, halogenation, hydrogenation, alkylation, polymerization, and other chemical processes but shall not apply to chemical plants, refineries or distilleries.

...
1910.106(h)(4)(iii)(a)
The transfer of large quantities of flammable liquids shall be through piping by means of pumps or water displacement. Except as required in process equipment, gravity flow shall not be used. The use of compressed air as a transferring medium is prohibited.

I am confused by the (h)(1) section, given the definition of a "chemical plant" is
1910.106(a)(8)
Chemical plant shall mean a large integrated plant or that portion of such a plant other than a refinery or distillery where flammable liquids are produced by chemical reactions or used in chemical reactions.

Things such as polymerization are chemical reactions, so wouldn't they be, by definition, chemical plants?

 

[Latexman]

TiCl4,

OP is not handling a flammable. It is combustible; handled below the flash point.

Definitions are critical to properly analyze the reaction so of a operation.

Good Luck,
Latexman

 

[TiCl4]

Latexman,

I agree, but to OSHA, this IS a flammable liquid.

1910.106(a)(19)

Flammable liquid means any liquid having a flashpoint at or below 199.4 °F (93 °C). Flammable liquids are divided into four categories as follows:

The prohibition later on in the standard applies to ALL "flammable" liquids, regardless of category.

 

[Heaviside1925]

TiCl4,
My reading of this indicates that a chemical plant should be governed by PSM for chemical plants. The quote you provided indicate that if a facility is Not governed by PSM for chemical plants but contain chemical operations such as oxidation, reduction, halogenation, hydrogenation, alkylation, polymerization, and other chemical processes then the following applies.

 

[georgeverghese]

Literature on the net talks about "explosive polymerisation", which presumably means a large exothermic heat of reaction due to polymerisation (dimerisation), which would make this liquid potentially flammable in case of misoperation.

 

[MementoMori]

TiCl4, thank you for the word of caution. Yes, that is a perplexing distinction OSHA is making. On the surface, the difference seems to be a chemical plant uses the flammable liquid in the reaction whereas the "chemical operations" in the processing plant do not use the flammable? Or is differentiator "large integrated plant." I really am not sure. Strangely, the requirements for the chemical plant (1910.106.i) seem less extensive than the requirements for the processing facility (1910.106.e).


1910.106(a)(8)Chemical plant shall mean a large integrated plant or that portion of such a plant other than a refinery or distillery where flammable liquids are produced by chemical reactions or used in chemical reactions.


1910.106(h)
Processing plants —
1910.106(h)(1)
Scope. This paragraph shall apply to those plants or buildings which contain chemical operations such as oxidation, reduction, halogenation, hydrogenation, alkylation, polymerization, and other chemical processes but shall not apply to chemical plants, refineries or distilleries.

 

[pierreick]

Hi,
Please take some time to read the MSDS and the EBAM pamphlet.
Pierre

 

[georgeverghese]

Must say splash filling is one way of aerating this liquid in the presence of air so dimerisation - polymerisation risk is reduced.

 

[TiCl4]

MementoMori,

By the by, what is commonly used elsewhere and would also work here would be an Air/N2 blend to get O2% down to approximately 5-7%. The limiting oxygen concentration of most monomers is in the 7-10%(ish). That is why you see recommendations in monomers that contain MEHQ that O2 is kept at 5% - it keeps the inhibitor active, but stays below the LoC.

If you do that, you don't have to worry about splash filling at all.

 

[georgeverghese]

Perry Chem Engg Handbook discusses LOC ( limiting oxidant concentration ) on page 26-54 of the 7th edn. NFPA 69 has more info on LOC data.

 

[pierreick]

Hi,
Make sure you and others understand the risk associated with the lack (depletion) of O2 during the storage of GAA. Much bigger than other monomers.
I've attached a slide from a PPT presentation made by BASF.
Don't follow recommendation to reduce the O2 content in air mixture, the risk of polymerization and consequences is much higher than fire.
Again, don't reinvent the wheel and follow what is written in the documents shared.
Pierre

 

[shvet]

@pierreick
Can you please share the full version of this file or a link to the resource?