Cryo system design. 2

[danthemeterman]

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

 

[dcasto]

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?

 

[danthemeterman]

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

 

[iainuts]

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.

 

[danthemeterman]

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

 

[dcasto]

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

 

[danthemeterman]

Good point. I'll keep it in mind.

 

[someguy79]

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.

 

[danthemeterman]

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.

 

[dcasto]

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

 

[danthemeterman]

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.

 

[dcasto]

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.

 

[iainuts]

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.

 

[dcasto]

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.

 

[iainuts]

Hi dcasto,

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.

 

[danthemeterman]

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 ?

 

[dcasto]

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.

 

[someguy79]

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.

 

[danthemeterman]

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

 

[danthemeterman]

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.