Acetone road tanker off-loading velocities 1

[Alfsterino]

Well, finally a question that has not been asked on the site that I need answering so here's my first post!

I am designing a small acetone storage tank (5m3 volume) which needs to be filled from a road tanker. I am having problems working out a maximum pumping velocity as some literature say static shuld be avoided by keeping velocities to 1m/s to 7m/s but other documentation says that due acetone being miscible with water it will not hold a static charge(NFPA Code77 8.3.3.2 (2007)) .

The client would prefer we pump as quickly as we can along with the transfer of acetone to the process which would be 12m/s along a 25mm diameter line.

Should I treat acetone as a non-conducting solvent or a conducting one?

Many thanks for any help.

 

[HamishMcTavish]

This link recommends grounding and bonding is applied for transfers of acetone - surely if you do that you could pump as fast as you want?

A fire / explosion surely requires a flammable mixture with air (in the right proportions) and a source of ignition.

http://www.sunocochemicals.com/HES/tech_manuals_acetone.htm

Regards, HM

No more things should be presumed to exist than are absolutely necessary - William of Occam

 

[Alfsterino]

HM,

Thanks for the reply.

Even if a system is fully bonded and you are using a non-conducting solvent one still needs to keep the velocity low otherwise a charge will build up in the fluid itself.

Based on the NFPA information, I am assuming acetone will not build a static charge and I will be able to pump at higher speeds. Though based on pipe sizes this will be a maximum of 4m/s for tanker unloading so not too high at all.

The 12m/s flow is a small volume as well: ~20litres.

 

[HamishMcTavish]

I found the following:

http://www.caledonlabs.com/upload/msds/1200-1e.pdf

which is Canadian, however that shouldn't affect the data bits. It states under the fire and explosion section that the liquid will not accumulate a static charge

hope this helps, HM

No more things should be presumed to exist than are absolutely necessary - William of Occam

 

[Alfsterino]

Brilliant. Well, that sorts it out then.

Many thanks.

 

[MJCronin]

Alf...

I have a problem with the liquid velocity and the selected pipe size.

In English units, a velocity of 12 m/s and 25 mm pipe equates to about 40 ft/second velocity in a 1" NPS pipe ???

Isn't this a bit high ?

Any fill pipe that I have designed for a tank farm has always been 2"NPS or larger and velocities were under 12 FT/sec.

The same client that will complain bitterly about long tanker offload time will complain bitterly about piping vibration and erosion.

My opinion only

-MJC

 

[ash9144]

Good point from MJC. That high velocity will also result in a lot of flashing of acetone when it exits the pipe.

When I worked around acetone we treated it as a nonpolar solvent and had adequate dip pipes and bonding. Why take the chance?

 

[MJCronin]

ash....

I agree with your dip pipe and bonding remark.

Considering all of the eventual system changes in a plant, it is well worth a few dollars more to bond everything and include dip tubes in all tanks.

Why take a chance and....prepare for the future !!

-MJC

 

[StoneCold]

We do alot of tanker truck unloading of solvents to I will put my two cents in as well. We would do the bonding and dip pipe for loading. We set our velocities up a round 10 ft/sec. I would definately look at using 2" pipe. It is just easier to get the truck unloaded. We shoot for a 2hr unload time becaue more than four hours they charge demurge (sp?). We also put low pressure nitrogen on the tops of the trucks and then open the vapor balance line to the tank which also has an almost pure nitrogen pad on top of it.
Obviously no smoking, no cell phones, truck turned off, grounded and bonded to the rest of the system. Our unloading hoses are stainless so they conduct any charge back to the pump and the rest of the carbon steel piping.


Regards
StoneCold

 

[hacksaw]

any fluid velocity exceeding 10 ft/s (3 m/s) with a flammable liquid is more than a bit risky, charge buildup or no.

 

[786392]

In my humble opinion there has to be initially lower velocity around 1m(or 3ft) per second till the pipe's exitiing end gets dipped after this the velocity may be inreased to 3m(10ft) per second.

This is helful for highly volatile flammables handling safety.

Best Regards
Qalander(Chem)

 

[Alfsterino]

Thanks for the replies.

The 12m/s will 'only' be transferring about 20litres of fluid. It will also be via a system where the velocity can be reduced as well hence from a process design point of view it will not be an issue. The client will have to make their basis of safety for those transfer speeds.

The bulk will be along 2" line with the information given above the set-up I have designed will not give high velocities.

Regards,

Alf

 

[BigInch]

Sorry but you're gonna' get my warning too. 12 m/s? In a transfer application? Get serious.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[25362]

I fully agree with BigInch. Although the "static" relaxation time for pure acetone (a polar liquid) at 20[sup]o[/sup]C is in the order of 10[sup]-4[/sup] s, the high flow velocity may result in an accumulated energy level beyond 0.1 mJ, considered a reasonable limit to avoid a spark igniting flammable acetone vapors.

I suggest reading chapter 7 of Crowl and Louvar's Chemical Process Safety: Fundamentals with Applications, Prentice Hall, in particular, example 7.4.

 

[BigInch]

My comment was purely from the hammer and spill safety perspective. First, I wouldn't want to get hit with that 20 liter bullet, second, won't that spray everything within 75 feet. Glad its not explosive.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[25362]

BigInch, thanks for the clarification. Anyway, I still surmise that static charge buildup at these high velocities is a subject to be taken into consideration.

 

[BigInch]

Oh yes... just indicating that I was not thinking about that. The knockdown effect alone, if the loading connection was opened a split second too soon, was bad enough for me.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Alfsterino]

All pipe velocities now at sensible low single figures!

Many thanks for all the help and advice.