carbon dioxide transport 4

[RE]

We have to transport 250000 std m3/day of CO2 (@ atmospheric pressure and 50 °C) fron one site to other, 90 km apart. There are two option: 1) compress de gas and send it in a pipeline, 2)condense the CO2 and send it as liquid in a smaller pipeline or by truck; and vaporize at the other end. Does anybody have experience in this field? Which is the best alternative? It is possible to send liquid CO2 through 90 km pipeline? Thank you!!!

 

[Montemayor]

RE:

First, we've got to get some basics understood:
1) You say you have to transport 250M std. M3/day (approx. 6,130 std M3/min); you further define a temp. & pressure of 50 oC and atmospheric pressure, without stating if these are your "std." conditions. I doubt it, but you leave it up in the air.

2) Presumably, the CO2 exists at 50 oC and 1.0 atmA; and the "standard" conditions are undefined. If you are to give us basic data, you should state your "std" conditions - this is normal, std. engineering practice if you want to deal with specifics - as in your case.

3) Your first option is a 90 km gas pipeline (note: you don't say supercritical);

4) Your second option is ship it via a tank truck as a liquid; this is routinely done in industry at 250 psig and -8 oF. The conventional tank truck has a max. capacity of 20 tons (net), and the 250M M3/day is equivalent to approx. 460 tons/day (if 20 oC is taken as your "std" condition - see what I mean about stating your base standard?). This means you would require at least 23 tank truck transfers per day - one an hour. This isn't close to being a practical solution.

You could save on the liquid investment by sub-contracting out the hauling of the LCO2; however, you're going to have to face up to an investment in compression and liquefaction (Ammonia; 2-stage) as well as a very healthy storage capacity at the reception end, plus vaporization equipment. On the surface,with the scarce basic data you've supplied, the LCO2 doesn't make economic nor practical sense. Here, I'm stating this with over 15 years of designing, operating and managing LCO2 facilities.

The gas P/L, then, is what is left over as your option. You haven't mentioned going supercritical, but then that P/L version is merely a variance on the gas P/L option. I presume you would compress the 50 oC gas (after cooling it!) up to the pressure to overcome the P/L pressure drop in an optimization case. This all is predicated on what you need at the reception terminal and what it is worth to you. This should be a very nice and educational optimization exercise on P/L size, compressor pressure and energy consumption.

You ask if it is possible to send LCO2 through a P/L. Of course it is - in both the saturated state as well as in the supercritical state. I wouldn't do it in the saturated state because of the critical properties of CO2. I'll let you use the thermodynamic values at:

http://webbook.nist.gov/chemistry/fluid/

there, you will see that it takes less than 88 oF to keep the CO2 liquified - the less the temperature, the less the pressure. However, when you get to a temperature less than your U/G pipeline, you're going to require insulation - and this is probably not practical for a buried pipeline that long.

Which is the best alternative? That is entirely up to you to determine since you own and control all the basic data and economic guidelines and incentives. As you enter the supercritical state, the fluid starts to behave is such a manner that the required pressure drop is normally less than that of the superheated gas. This is where optimization enters the picture in a serious way if your energy prices are high.

I hope this has helped and that I've succeeded in explaining the critical features of this application and its options.

Art Montemayor
Spring, TX

 

[katmar]

Art Montemayor has described the alternatives very well, and I have nothing to add from a technical view point. However, having installed a CO2 gas pipeline (less than 1 km) recently, I would like to also bring the safety aspects to your attention.

CO2 is non-flammable and non-toxic, but it is an asphixiant in that it displaces the oxygen. It is colorless and, depending on the process that generated it, close to odourless as well. It is very easy for CO2 to collect in underpasses, tunnels, culverts etc in case of a leak and any repair team that went in could be dead before they knew what had hit them. I have seen a few near misses with CO2 and unfortunately one fatality.

If you decide to use a liquified pipeline system, the low temperatures introduce a whole new set of safety questions.

Without doing any calculations, my immediate response would be to truck it, although as Art has pointed out this will probably mean a dedicated fleet of 5 or 6 trucks running 24 hours per day.

It would be interesting to see your relative economics once you have done the sums.

regards
Katmar

 

[25362]

One is sometimes compelled to think that when large amounts of carbon dioxide are needed, and by its being a by-product of so many commercial processes, it could be separated, recovered and prepared for commercial uses by simply installing one "generating process" at the planned point of delivery and application, or vice versa.

 

[Montemayor]

25362:

What you bring up makes common sense. However, the marketable and exploitable sources of by-product CO2 are constantly monitored and contracted-for by the major CO2 distributors like Praxair, Liquid Air, BOC, etc. There are no really independent, CO2 producers left today. The process of eliminating CO2 generation (usually by combustion) started in the late 1950's by such companies as Liquid Carbonic (now Praxair) in an effort to buy up by-product sources (such as those existing Ammonia plants, fermentation plants, etc.) in order to eliminate their production costs and simply convert themselves into distributors rather than producers. What you have now is a market that is controlled by those distributors controlling the by-product sources. The real massive production rates of CO2 come from what were intended to be oil wells and, through Nature's whims, turned out to be really CO2 wells. This source is sometimes remarkably pure - although most is "tainted" with hydrocarbons and noxious sulfur compounds.

The CO2 wells are usually dedicated for secondary recovery in developing oil fields. I suspect that the CO2 source in this thread originates from a natural well - there are some rather large CO2 wells out in Colorado, Wyoming, and New Mexico. In today's CO2 marketing world the name of the game is: "control the distribution costs" and you control your profit margin.

The majority of the Process market for CO2 in the USA is centered on the consumption of very high purity CO2 (>99.8% vol). The means to get to that level starts to get expensive on a unit basis when the quantities are relatively low. And dealing with dilute sources (such as flue gas @ 14%vol) is very un-economical and non-competitive. The answer to obtaining a CO2 commodity is to find a by-product source and establish a take-or-pay contract based on added cost due to processing. The profit margin is usually very low based on a unit base, so the contract quantity has to be inherently rather large.

The thermo properties of CO2, as I explained above, make it rather cumbersome to transport in tonnage quantities. Most of the large secondary applications done out in the oil patch utilize supercritical conditions to pipleline the stuff to its target application. Unless you can pass on the stiff refrigeration and compression cost necessary to liquefy the CO2 (like soft drink bottlers), you really have a dilemma in figuring out how to save the refrigeration rather than just vaporize using the atmosphere as a heat sink (most CO2 in industry is consumed in the gas phase).

It isn't an easy problem and it continues to be worked on.

Art Montemayor
Spring, TX

 

[davefitz]

Here is a thought to ponder: if the existing coal fired plants are converted to IGCC with CO2 extraction for sequestation, we would have more CO2 pipelines to the coast ( for undersea sequestation) then there are interstate natural gas pipelines !

 

[25362]

Art Montemayor: your quick and thoughtful comments deserve a star. Thank you for the message and lesson therein.

 

[rmw]

Art,

Among my clients are (used to be, few are left domestically) ammonia plants that produce CO2 as a by-product of their process. In the last decade or more, they (or their subcontractors) have begun to liquify it and truck it to various markets.

Without even knowing all the in's and out's of the topic, I have recommended that use of their by-product to plant management, and many followed through and did it.

Thanks for such a comprehensive view of the overall subject. You are getting a star from me too. Valuable post.

I happen to have amoung my engineering experience, some (not recommended) trucking industry experience and can add to this thread, that depending upon where the original poster is in the world, in the part I am familiar with, which is all I can refer to, there are trucking companies that do just that, truck things, and do it well, no matter what the commodity is.

CO2 is just one of many such commodities, so the liquifaction, storage, and vaporization is the only issue that the poster really has to worry about if he has that available to him/her, and you have given him plenty of food for thought for that part of it.

rmw

 

[RE]

Thank you all very much for the valuable answers!!!
Trying to be synthetic I was very short in giving details. First, I forgot to give the std. condition: 1 atm abs. and 0°C, sorry (Montemayor is right). Second: the whole panorama is as follows: the CO2 is the by product of the conditioning of natural gas well production. At present the CO2 is venting to atmosphere!!. The main goal of the project is to get rid of CO2 at the lowest possible cost, but not venting it any more for pollution problems. At 90 km distance there are a methanol plant that can use de CO2 in gaseous phase. All transport alternatives are open, including supercritical transport. But according to the aswers received it seems to be that the gas pipeline is the most convenient way. Again thank you very much.

 

[jd3020]

Thank you all for the previous conversations. Are any of you aware of the quality of CO2 coming out of ethanol plants? I am hearing of a trend of buyers of CO2 wanting the producers to build the liquid conversion facilities on site with the intent to buy liquid from the source itself. Do you see this?

 

[Montemayor]

jd3020:

I am very aware and familiar with fermentation by-product CO2, having a direct hand in modifying and operating several plants - one in the Caribbean and another in Peru. I also was plant manager for a large dry ice facility in Decatur,IL where the feed LCO2 was purchased "across-the-fence" from Archer-Daniels' ethanol plant from fermentation.

I don't understand your description of "buyers of CO2 wanting the producers to build the liquid conversion facilities on site with the intent to buy liquid from the source itself". Could you please explain this in clearer detail. Do you mean that the LCO2 purchaser would have the ethanol producer locate the fermentation process on the purchaser's property and subject to his (the purchaser's) needs? I hardly think this is practical or makes sense; that's why I need you to make the question a little more clearer and specific.


Art Montemayor
Spring, TX

 

[jd3020]

Sorry for the confusion.
I spoke with a major CO2 marketer (not associated with the ethanol plant). They told me they have normally installed their equipment next to the ethanol plant. They would take the CO2 from the ethanol plant, liquify it, and ship to wherever they needed it. They bear the costs of doing that. They mentioned they are wanting to have the ethanol plant bear the costs of putting the equipment in to liquify it and they now buy it after that process, paying more for it. I hope that is a clearer explanation.

My questions have to do with whether you see this trend, about how much does it cost to install the equipment to do it, and how hard is it to produce food quality CO2?

Thanks for your time.

 

[Montemayor]

jd3020:

Let me try to address what I believe you're asking.

1) A trend to locate a CO2 by-product recovery plant near (or "across-the-fence") from the source has always been there -- since I graduated as a ChE in 1960. So I see nothing "new" or innovative here; who puts up the cash for the investment in the CO2 recovery and liquefaction facilities has a lot to with the need to obtain the CO2 (which depends on factors such as competitors, market demand, market prices, distribution costs, financing available, ROI, etc.). If government is subsidizing the ethanol producers in the overall investment, these same producers may find it attractive to use public money to generate their profit. This is an issue that could politically blow up in someone's face, so I don't know how that could fly.

2) How can anyone guess the size of the capital required for the LCO2 investment when you haven't even stated the capacity or the scope of the project? Your guess is as good as mine.

3) In my opinion, it is very easy to produce "food quality" CO2 from fermentation processes. However, how do you define "food quality"? The main point here is that fermentation CO2 is notoriously STINKY. By this, I mean that it smells horrible unless cleaned and purified. And here lies the problem! Smell doesn't deter it from being perfectly digestible and safe for human consumption; however, no human is going to like drinking a Coke or Pepsi that reeks of fermentation smell. And we're talking of only a fraction of ppms to make a difference. Any process failure to remove absolutely all the bad odor essentially contaminates the process train and the LCO2 storage facilities, making the operation a total failure. Therefore, the risk in allowing the smell to get through the purification train has to be considered. Coca Cola has tried to force expensive, continuous quality monitoring on CO2 production plants and this can become a hard issue. Ensuring that the smell doesn't break through is tough to guarantee without investing in redundent and over-sized purification equipment. The real, fool-proof instrument of choice for the smell test is the human nose and this, unfortunately, is not capable of being on-stream 100% of the time.

The availability of by-product CO2 from fermentation ethanol plants depends on the economics of the ethanol product. Without subsidies this industry is dead in the water. It can't, under common engineering sense, compete with conventional fossil fuels. However, as government subsidies continue and if the public tax payer allows it, the by-product CO2 will be there.

I hope the above addressed your questions.

Art Montemayor
Spring, TX

 

[jd3020]

Thank you. Yes it gives me some background. In terms of the capacity, the ethanol plant will produce 3.15 million gallons of ethanol/month. I have been asked to identify the best markets for the CO2. Naturally, I was asked about food quality CO2. The next step is figuring out pricing of each type of product. Thank you again for your comments. It is fun to learn about this process. Any additional comments would be welcome. Best regards.
JD3020