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Cryo system design.
2

Cryo system design.

Cryo system design.

(OP)
I am new to cryogenics. I have been singled out to engineer a system to convert methane gas to liquid. Create storage, and transfer the product to new locations. I have lots of experience in Liquid propane, so the concept of cryogenics is not totally foreign, although condensers are.Any help in finding supplies,support and engineering would be very helpful. I plan on trying to attend the classes in Colorado this year, does anyone have any comments on that ? Thank you in advance.
danthemeterman

RE: Cryo system design.

A system to convert methane to liquid?  Its a whole new game than propane systems.  The game is efficency!!!  The process to make LNG is energy intensive and you'll need to pull every tick out of the book to be competative.  Most LNG plants BUY other companies technology and in most cases the patented processes.  So, unless you are looking at system to make less than 100,000 gallons per day, you won't be doing much of the engineering.

I've designed smaller LNG plants and it was great fun.  Finding the physical equipment is tough, loading pumps being among the hardest.  

Is the training at CSM?

RE: Cryo system design.

(OP)
Hi, Thank you, yes I realize it is a new game. I am not so much interested in engineering the equipment as to assemble all the structures and have the tanks built to spec. Most components will be purchased through existing suppliers. I do not want to cross boundaries with Eng-tips so i don't know how much more I can tell you. I like this sight and do not want to be expelled.
danthemeterman  



August 4-7, 2008
27th Annual Cryogenic Engineering Summer Session Short Course
Sponsored by the Cryoco, Inc.
The 27th Annual Cryogenic Engineering Summer Short Course




 

RE: Cryo system design.

Hi dan'
You're asking a pretty broad question.  It sounds like what you're trying to do regards system level design.  For that, such things as ASME B31.3 piping code and ASME BPV for vessels apply.  Since this is a flamable, NFPA codes also apply.  Large structures or buildings need to comply with IBC.  Basically, the same kind of industry standards that apply to any process system will also apply here.  

You might also consider locating equipment suppliers and/or engineering consulting perhaps through ThomasNet.com

If you can be a bit more specific about what you're trying to do it would help.

RE: Cryo system design.

(OP)
I will be employing firms to assist in engineering the project. I just need to get some sort of idea as to how much it will cost to purchase the equipment. Building codes are no t necessary at this time, however I am quite familiar with NFPA 58. I am sorry about being so vague, it is due to privacy legalities. (right to know). I do thank you for your answers, and hope to be a little more forth coming in the future. I will continue to monitor this forum in case of more thoughts.
danthemeterman   

RE: Cryo system design.

OH, in the US LNG plants are subject to DOT 193 rules too.

RE: Cryo system design.

(OP)
Good point. I'll keep it in mind.

RE: Cryo system design.

Here are a few codes to get started with:
NFPA 59A
ASME B31.3
NFPA 70 aka NEC (for classified locations)
ASME BPV Sect VIII Div 1&2

Start researching
gas compressors
heat exchangers
refrigerant schemes like Linde cycle, Joule-Thomson cooling, cascade cycles, mixed refrigerants, and more

Good luck. I just got out of the business of small LNG plants. It's really interesting, but it ain't easy.

RE: Cryo system design.

(OP)
Thank you "someguy".
    The project just hit it's first wall, a major hurdle. There is more startup capitol needed than is currently budgeted. That being said, I was hoping to put together a package form scratch. I called around and found a firm that does turnkey, and the funds are not there. Hoping to use my common sense and previous experience, is also not helping at this time, and I have to believe there may be a considerable  amount of demand for the equipment available.    

RE: Cryo system design.

How big?  I pieced together a small one with used equipment and a technology not normally used in LNG, but easy to impliment.

RE: Cryo system design.

(OP)
Approxiamately 200+ gals/day . Maybe as much as 300. Don't laugh yet. What did/would yours cost, and what was the gas analysis at best ? If I may ask.  

RE: Cryo system design.

Have you ssen this?

http://www.inl.gov/lng/projects/refuelingstation.shtml

I was looking at 50,000 gallons/day at a cost of $10MM US.

The gas had about 3% ethane and less than .5% of Butanes plus.  CO2 was over .5% and water was 7 lbs/MMSCFD.

If you want to use in motor fuels you'll have some problems as the ethane must be under 2%.  Bad rule, but thats the facts.

RE: Cryo system design.

That's really small...  have you considered just putting it through a heat exchanger with liquid nitrogen (LIN)?  You'd need roughly 1.15 to 1.60 gallons of LIN for every gallon of methane (depending on LIN conditions, but it could be made to work at the low end).  The cost for LIN is in the range of 40 to 60 cents per gallon for that much use I'd think, but I'm not in sales so that's a real ballpark number.  If you had a use for the nitrogen, all the better.  

*WARNING - OUT OF THE BOX THINKING AHEAD*
Better yet, make a deal with some company that uses the LIN and stick the system on their site!  They use the gas, you use the refrigeration.   

RE: Cryo system design.

Lin is going to be more expensive than $.50/gallon because it takes as more energy to make LIN than LNG.  Then at 7000 gallons per truck load, thats 12 trucks per day of LIN.

The last LIN I sold was in 2003 and it was $.60/gallon with $3.00 gas.  I'll bet its $1.00/gallon.

Our capital was $.12/gallon, Operating cost $.07/gallon, and energy use $.09/gallon, under $.30/gallon.

I could get it lower but product spec's added to costs.

RE: Cryo system design.

Hi dcasto,

Quote:

Then at 7000 gallons per truck load, thats 12 trucks per day of LIN.
check your numbers again.  200 gallons per day methane times 1.2 gallons LIN per gallon of methane gives just 240 gallons of LIN per day or just over 7000 gallons of LIN per month.  Being this is a roughly 700,000 SCF per month usage rate, I'd guess the deal on LIN could be quite good.  I've seen LIN as low as about $.25 per gallon for large customers, though I don't think this is quite that large.  Still, it's a good sized usage.  

Look at it this way, the cost for a gallon of methane is going to be about 60 cents for the nitrogen plus cost of equipment.  That may or may not be in the ball park of what's needed.  I'll wait to see what Dan says.
 

RE: Cryo system design.

(OP)
dcasto and nuts(sorry, just couldn't resist). I'll start with this. In order for this system, it needs to be on sight, locally of the methane. IE: feet form gas inlet. Sorry for being a bit ignorant and to lazy tonight to Google, but what is LIN (Liquid nitrogen) ? Also, can you simplify mathetically amount of nitrogen needed to produce methane. 1:10, 1:25, 1:100 ? If I were to install LIN storage, would that prohibit the project. dcasto, you said you put a small one together with used equipment. Can you foresee anywhere that we could start with something small until we figure if it would be feasible for packaging multiple units ?

RE: Cryo system design.

iainuts, I was refering to the 50,000 gallon per day project, I can see where I may not have made that clear.

LIN is liquid nitrogen, yes.

I calculate that it takes 1.3 moles of LIN to get 1 Mole of LNG.  I use moles because it makes it clearer than gallons since both the LIN and LNG will be measured by mass then converted to a gallon based on a contract term and not always some published density term.

There is a small packager already in my link.  Also look for this:

http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/9841/view/print

This is out of the box stuff.  There is a working Model in Denver.  I think Cryco sold off the division that has it.

As for doing it your self on a small scale, I'd look at a small LIN plant that you use the LIN to make LNG and sell the O@ to bay most of the bill on the LIN plant.

LIN and LNG storage tanks are very expensive, but available used.  Getting the aluminum heat exchangers will take some work.

RE: Cryo system design.

Dan,
Is your feed gas really a pure methane, or is it a methane rich gas with significant impurity? Remember that some impurities can plug up your system as they freeze out (water, CO2, higher hydrocarbons, etc.) and other gases (N2, He, etc.) will hurt your yield.

RE: Cryo system design.

(OP)
It is only 60% methane. I am working on getting the rest.

RE: Cryo system design.

(OP)
OK guys, this is all I have for now. Do you still have interest ?
55-65% methane, 30-35% carbon dioxide, with some hydrogen, nitrogen and other traces.  

RE: Cryo system design.

the CO2 has to be removed to less than 100 ppm.  All the rest of the components are not a problem.

a combination memebrane and amine would most likele be thge best.  I'd also look at propylene carbonate and amine

RE: Cryo system design.

True, the CO2 is probably your biggest problem to deal with. dcasto probably has a better idea of what's economically good on the 50000 gpd scale. Plants I dealt with were much smaller.

The other stuff might not be a problem in liquefaction of LNG. However, in terms of meeting a product specification might make some of these more problematic. For example, you might have high levels of propane with associated gas. It would not cause any real problems in liquefaction, but your end user might not like it.  

RE: Cryo system design.

(OP)
Ok, now I am at the point where I need to start compiling all your great info, and some from other engineers I found to find out if this is feesible(?)I have looked all through this site to find out how to contact people to know avail. I fully expect this post to be rejected, and hopefully when it is they will contact me for further correspondence.
Thank You.          

RE: Cryo system design.

if you go to a big engineering firm, you'll get big in the box thinking. IMHO.  your task requires small out of the box thinking.

RE: Cryo system design.

(OP)
dcasto! I know, so any suggestions ? Thank you ! Sincerely.

RE: Cryo system design.

I'd agree with dcasto's last comment.  Here's a couple out of the box ideas that add on to my previous suggestion of using LIN.  
1.  If you freeze the CO2 out, you could separate it with a strainer.   

2.  Putting it through a large vessel where velocity is minimal might allow the frozen CO2 to drop out.  

Doing either (or both) of these at an intermediate step of around -80 F means the CO2 will be solidified and the remainder will be gas.  The only concern I'd have is that there would probably need to be some way of getting the solidified CO2 to form large 'chunks', large enough to get stuck in a strainer or fall out at low velocity in the tank.  

This also adds some cost to the economic analysis I provided earlier of course (May 12 @ 19:11).  Take a look at that again and see if the use of LIN is cost effective or not - still curious if the above cost is reasonable for you.  

RE: Cryo system design.

Even with good CO2 removal, some CO2 will build up in the bottom of the LNG stoarge tank and the tank can be warmed up and the CO2 removed periodically.  This happens when the CO2 is under .5% in the feed stream.  Once you get over .5%, CO2 ice will eventually stop up lines and the system will have to be warmed up (derimed).

RE: Cryo system design.

I can't comment on how exactly to do the CO2 freezing heat exchanger, (confidentiality issues) but I can say it has been done. Been there, done that myself.

As dcasto alluded, the CO2 will tend to freeze onto stuff rather than drop out as particulate or something.

Freezing isn't my favorite method for CO2 removal. I've also used vacuum pressure swing adsorption. I've considered using amines and a few other methods too, but they weren't cost effective on the scale I was to produce.

You might give a call to my old company (http://www.prometheus-energy.com/). I don't know if they still have capacity for any new projects, but this sounds more and more like the kind of thing I used to do.

RE: Cryo system design.

Any guies here are in the line of air separation plant

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