Freezing crude oil with dry ice? Part II

[The Omen]

Hey All,

 

Thanks for your help in the last thread. Here's a new one.

 

Hope you have time and the curiosity to assist with this more detailed request.

 

Basically, I have little to no scientific bent and need help. I am looking to freeze a rectangular block of crude oil (800mm x 800mm x 75mm in depth).

 

So far, getting my hands on crude oil has been quite a task, requiring quite a lot more research than I had anticipated. It seems that prior to any of the oil refineries handing over any crude, I need quite a detailed manual on how I plan to use it. They have issues with regards to “duty of care”.

 

The basic premise thus far, is to create a rectangular wooden crate, with an aluminium tray for the crude.

 

I’ve attached an image on how I plan to freeze it. Have a look.

 

I’ve been told that dry ice may be the go in getting the crude to freeze, however I’m uncertain of quite a few things.

 

So my questions are:

1. Can dry ice do the job?

2. If so, will the whole container need to be completely filled with dry ice to adequately freeze it?

3. Will dry ice stick to the timber and acrylic glass/ aluminium tray if applied?

4. If so, is there some kind of protective agent/ lining I can use to stop it from sticking?

5. Is there any other feasible, affordable option for the freezing?

 

Hope you can help.

 

Thanks,

The Omen

[gonelli]

I'm not 100% sure if dry ice is cold enough to freeze the crude oil. But, I think that using liquid nitrogen would be a better option if you possibly could. Using it removes the problem of things getting stuck to the box, etc. and it will surround the crude oil a lot better and therefore allow faster freezing. Plus the fact that it's at a lower temperature than the dry ice will also make it a better freezing agent.

[The Omen]

Liquid nitrogen has been recommended before.

 

However, do you know if it could be used in a non-laboratory environment? I've never used it. i intuit it's in a high pressure tank and is sprayed into a confined space. If so, how would I use it in this context with the crate mentioned above? Can I buy liquid nitrogen? etc.

[Gilded]

You can buy liquid nitrogen without any sort of special license, but I'd imagine you have to buy quite a bit of it. It doesn't cost that much though. And yes, it can be used in a non-laboratory environment, preferably in some sort of metal container which can withstand the low temperatures well. While nitrogen gas is probably quite pressurized I don't think that's the case with liquid nitrogen, judging by every nitrogen freeze presentation I've seen having a vacuum flask of non-pressurized nitrogen.

[big314mp]

I'm speculating here...but since crude oil is a mix of hydrocarbons, some will freeze in the dry ice, some won't. Looking up a couple of melting points for various alkanes (pentane - some of the octanes) shows that there are quite a few that wouldn't freeze in dry ice.

 

You could freeze it to a slurry, and then try and squeeze out the liquid, leaving behind solid not-quite-so-crude oil.

 

They would all freeze in liquid nitrogen though. Put some sort of plastic liner inside the wood to hold the N2, then make sure the box has a hole punched in the top of it (a drill would work) for pressure to escape. You could even wrap the box in fiberglass insulation to save on the nitrogen use. Then just put in your crude oil container, and pour in some N2. Add more as necessary (b/c it will boil off as the crude oil freezes).

 

Just thought of something...acrylic might crack if you pour liquid N2 on it while it is warm...I don't know how to figure if it will crack or not, but perhaps someone else here does.

[hermanntrude]

liquid nitrogen is sold under pressure and stored in pressurised containers. the reason of course is that if you leave a flask of it at room temperature and pressure, it will boil off in a few hours. But yes, certainly you can pour it into that tray and it will freeze the oil before it boils off

[John Cuthber]

Liquid nitrogen is stored in Dewar vesels with loose fitting lids for several days or even weeks in the lab where I work. We don't keep it under pressure. Large storage Dewars are pressurised, but this is for ease of dispensing rather than to stop it boiling.

 

http://www.cryospeed.co.uk/cryospeed/equipment/dewars_and_accessories/25_litre_dewars_and_accessories/index.asp

 

Anyway, as has been pointed out, dry ice simply isn't cold enough to freeze all the components in crude oil. Also the mixture will have a lower freezing point than the components so I think the best you would get would be a very viscous goo.

With liquid nitrogen you could freeze it, but it would melt as it warmed up so a block of it wouldn't lst long.

What on earth do you want it for anyway?

[The Omen]

Thanks for the response guys. It's overwhelming.

 

I'll tell you all about the reasoning for this, once I actually get the project underway. Till then, it's just a halfbaked idea.

 

So, it seems the unanimous vote is liquid nitrogen. By the sounds of it, it's much cheaper and easier to use in this context.

 

I received an MSDS (material safety data sheet) regards to Crude Oil, and it does emphasise the combustibility of Crude in contained environments. So some more questions:

 

1. would crude contained in this crate combust?

2. does the combo of liquid nitrogen and crude raise any issues for potential combustion?

3. in terms of checking whether the crude is frozen, is there any issue with opening and closing the container to check? does the nitrogen escape? will it blow up in my face? I think that's a silly question...but hey.

4. does the container need to be sealed or not?

5. how do i avoid the crude combusting? what would make it combust?

 

Thanks again,

The Omen

[big314mp]

1. Not unless you set it on fire. It won't spontaneously ignite, although it will probably give off vapors that can easily ignite. Solution? Do the experiment in a well ventilated area away from all (potential for) fire and sparks.

 

2. Nitrogen gas is pretty inert, so the crude won't react with it. On the contrary, the N2 will displace O2, making it virtually impossible to start a fire. With that comes the danger of it displacing the O2 you breathe. Again, a well ventilated area and you'll be fine.

 

3. The N2 will boil, but small droplets hitting you won't be an issue, as they have very little "cold" due to their small size. Keeping it closed (and insulated) will help keep the N2 from boiling away though.

 

4. DO NOT SEAL IT! As the liquid N2 vaporizes, it's volume increases by ~700x (I pulled that number out of thin air, but it's somewhere in that region). Sealing it will make it explode. Think sealed container in a microwave, only larger, and with a bunch of really cold stuff that you wouldn't want to be splashed with.

 

5. Don't set it on fire . In all seriousness, once you add the liquid N2, you'll have better luck setting a brick on fire.

 

And out of curiosity, what program did you use to make the drawing?

[The Omen]

The program is google sketch up (CAD for dummies). It's a fairly decent program, easy to use.

 

This is really great feedback all!

 

More questions?

 

1. What kind of time frame would I be looking at for the liquid nitrogen to freeze the crude? As mentioned the block of crude is roughly 800mm x 800mm x 75mm in depth. The crate will be roughly in the vicinity of 1200mm length x 1200mm width x 575mm height. That's about 200mm surrounding all sides of the crude, top + bottom + sides. (err...don't know how to calculate the mass or volume of the surrounding space any other way) http://www.scienceforums.net/forum/images/smilies/redface.gif

 

2. Do you think the crude in the aluminium tray would stick once frozen, making it difficult to remove the block out of the tray in one piece?

 

3. In terms of lining the crate with plastic, what material would work?

 

4. Is there any issue with the metal/ aluminium tray thrown into the equation? do you have any recommendations if so?

 

5. When you guys mention the boiling point of liquid nitrogen i assume you mean boiling cold, is this right? So, no qualms in it heating the crude up....

 

6. Can the crude be completely sealed as shown above (perhaps with a different lid)?

 

7. If the crude isn't properly sealed with lid, will it end up containing any traces of liquid nitrogen within it, or on the face of it?

 

Thanks again,

The Omen

Edited September 4, 2008 by The Omen
multiple post merged

[big314mp]

You've got a lot of question

 

1. I don't know enough to do the math on this one. Realistically, you would just add liquid N2 until it freezes. I have no idea how much that would be though...perhaps someone else would have a rough idea?

 

2. Well, you can just let it thaw slightly, to melt the layer in contact with the metal. Then you have a thin layer of oil between your metal case and the frozen crude.

 

3. Any plastic sheeting that will provide a good seal (i.e. glue it in place, don't nail/staple it).

 

4. Not really...get yourself some oven mitts, as the tray will be really cold when you try and take it out.

 

5. The boiling point of N2 is -196C, so that would be the temperature of the liquid. Just like boiling water is 100C, boiling N2 is -196C.

 

6. The crude can be sealed, if you so desire. The plastic may crack due to the temperature difference. You may be better off leaving the top off.

 

7. The liquid N2 will vaporize to form gas N2, which will bubble out. I would think that the liquid N2 would be less dense than the crude oil, and so would sit on top (i.e. it wouldn't mix in with the crude at all), but that's just a speculation.

 

The best I could find on the crude/liquid N2 density stuff was that liquid N2 has a density of .707 g/ml, while crude is somewhere between .790 and .973g/ml

 

http://en.wikipedia.org/wiki/Liquid_nitrogen

http://www.engineeringtoolbox.com/liquids-densities-d_743.html

[The Omen]

Hey,

 

So it'd make more sense to make the container out of aluminium sheet metal say, as opposed to wood, given the use of Liquid Nitrogen wouldn't it?

 

Also, would I need to submerge the crude tray in the N2 or would it suffice to just let it sit on top of the N2?

 

if N2 is liquid, isn't it absolutely necessary to cover the crude if it were to be submerged? won't it create a swirling mess of oil and N2 if it isn't?

 

I know, I know...I should just do it and see it, just want to get it right to save on resources.

 

Thanks a bunch.

[big314mp]

What I would do, is have an metal tray (I would have used a cake tin), set it inside your larger liquid N2 box, but set it on small blocks of wood to raise the top edge of the metal tray above the level of the liquid N2. Pour in the N2, and allow to cool.

 

It will take quite a while to freeze, and I'm guessing quite a bit of liquid N2.

[The Omen]

Hi all,

 

So this project was temporarily suspended since I last wrote on it. I have now returned to it with the resources to pull it off, bar one very important component....crude oil. I have been in dialogue with two of four refineries in Australia to access 30 litres and one refinery has declined the request based on 'duty of care'. I fear the others will also follow suit. Whilst it is unfair that they have a monopoly on the resource, I do understand why they are chicken s..ts, particularly in light of all the recurring spillages on their part.

 

Several people have suggested a fake crude made up of what have you, but this is not really an option. I need the real thing, otherwise it is merely theatrics.

 

So two years later, I ask, does anyone know where i can get crude from.

 

Anyone know anyone who knows someone?

 

Auctions on the net perhaps?

 

 

cheers