Melt frozen product in railcar (failed coils)

[tgschaef]

We have a 24,000 gal frame type tank car ~¾ full of product and the steam coils have failed. What are our options to melting the material and clearing the railcar recovering the product? The product melts at 250°F.

The car owner won't let us cut a head off and shovel it out. Reacting or dissolving the material is not desireable for various reasons. The "easiest" answer seems to be rolling it into an "oven". Is anyone aware of a railcar "hotbox" that we could ship the car to and melt the product and then do a transfer to trucks or other railcar? The car is currently in the SE US.

TIA

Tim

 

[GregLocock]

You /might/ be able to find an autoclave that size, used for making composite aircraft parts. 250 is a little higher than the epoxies I'm used to, but would make sense for aerospace.

Otherwise, build an insulated wooden box around it and blast steam in for a few hours/days. We built a vehicle sized one that got to 190 in a couple of days, using a propane gas heater or two.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[kcj]

what do you mean by steam coils have 'failed'? You probably already know this, but there may be multiple sets of coils.
Cars we were using had two or three sets of steam coils, coming out to two or three sets of pipe stubs. Those were older cars though.

You might have reduced capacity but might be able to somehow use the remaining loops, depending on where the damage was.

Probably along shot, but I thought I would toss it up here.

Are they external coils, you might cut through the jacketing and insulation and modify them externally. If internal coils, there are not many options ohter then your oven plan.

k

 

[debodine]

Your situation is way outside my area of expertise, but I had read the report at this link some time back and thought it might be informative.

http://www.ntsb.gov/Recs/letters/2004/R04_10.pdf

best regards,

debodine

 

[tgschaef]

The car is insulated and the more I think of it, heating from the outside would probably be a long, expensive process. My current line of thinking is getting ~100+ ft flexible stainless (compatibility reasons) hose and snaking it from the manway to one end to the other end and back out the top. This hose would be connected to a fabricated new manway lid with pipe connections. Then put some 245# steam on it and trap it out on the other end.

My rough calculations show this should be able to provide enough heat input, especially after it melts some and hopefully sinks into the material.

kcj, you're right there are two sets of coils. They said the product started coming out of the steam connections after filling the tank (they also claimed to pressure checking the bundle first, but whatever...) I didn't specifically ask if they tried both sets, but we've had this for over a year and I heard stories of leaving steam on for a month and getting no where as well as dropping a U-tube exchanger bundle down the manway. I assume (always dangerous) that both sets were tried in all of this before they asked me. As for the U-tube, that melted right around the bundle but I believe with the limited surface area and heat losses through the unsealed manway's heat losses that's as far as it got.

debodine, thanks for the warning. Thankfully this product is stable, and doesn't readily decompose, but point taken.

Thanks,

Tim

 

[hydrae]

After thinking about this,
Take a new manway lid (or a piece of plate the same size) and drill holes for the u-tube steam coil inlet and outlet allow the u-tube to slide down as the product melts, also drill a hole for a pumping device could be a simple as a stainless paddle wheel on shaft like what is used to mix paint through a bearing sleeve that is welded it to the manway lid. After melting the product in the area of the u-tube, run the mixer to expand the melted area.

If the viscosity is too high for the paint mixer to work use a pump instead, could be a submersible sump pump with just the cord going through the lid or a pump on a line shaft so the motor is outside, on the pump outlet install a elbow to direct the product to the far end of the tanker.

You may have to add insulation to the outside of the tanker to keep the heat losses less than the capacity of the u-tube heat source

A second method:
Do you have more of the same product?
If so can you pump hot product into one end of the tank and draw it out of the other side? set up a flow of warm product to melt the rest.
This method not so easy if all of your pumps are air padding as a method of material transfer.

Hydrae