louis wrote:I'd forgotten about this. It does seem that my original thought, that you could capture CO and oxygen from the atmosphere and have a ready made energy store when humans landed a couple of years later is not so crazy and could work. Whether it's worth going to that trouble compared with just loading 30 tons of methane and oxygen on a Starship is another matter. I guess boil off over two months might be an issue?
If I read this correctly, Louis is suggesting the capture of CO and O2 already in the atmosphere on Mars.
It could be done, but it is no trivial undertaking. The Martian atmosphere is 95% CO2, 2% Argon, 2.8% Nitrogen, 0.174% O2 and 0.0747% CO. For this to work, you must first separate the CO2 from the other gases. The CO2 in the Martian atmosphere is close to its triple point temperature, so relatively little compressor work would be needed to increase its density relative to the other components. The remaining gases would be 40% Argon, 56% N2, 3.48% O2 and 1.49% CO, by volume. The CO would be about 1% by mass. On this basis, the calorific value of the non-CO2 content of the Martian atmosphere is about 100KJ/kg ( CO heat of combustion is 10MJ/kg). At 1bar, the mixture would have volumetric energy density of 150KJ/m3. At 300bar, it would be 45MJ/m3. Because the CO and O2 are present in low concentration, you could probably store the mixture in a single tank, without risk of explosion. To burn it, you would may need to pass it through a heated catalyst bed, as the concentration of fuel and oxidiser is too low to support flaming combustion, even under extreme compression.
In terms of total work output, one needs to compress 19kg of CO2 for every 1kg of stored gas mixture, which would release 100KJ of energy when released. Put another way, the chemical energy content of the Martian atmosphere is 5KJ/kg or 65J per cubic metre at 6.1mbar. This is almost certainly too little for any release of net energy from compressing and combustion of the Martian atmosphere. None the less, it may be interesting to consider this as an energy storage mechanism. The compressed CO2 has its own value as a CAES working fluid. Heating it above 31°C would produce high pressure gas that could drive a compact gas turbine. The stored compressed residual CO containing mixture has chemical energy density 100KJ/kg. Taking the Cv of the gas to be 1KJ/Kg.K, complete combustion would raise the temperature of the gas by 100°C. So along with its internal pressure energy, it could be a useful energy storage mechanism for short range vehicles and compressed air tools. It is worthy of further investigation, I think.
SearchTerm:Parr Instruments reply regarding design of pressure vessel for Mars (or Earth)
SearchTerm:Pressure vessel design
To all ... please suggest additional search terms that would help you find this post in future ...
20210412
-Tom
Good afternoon! Sure thing; you can see how these vessels are opened and closed from the below:
https://www.parrinst.com/support/videos/
There are a number of videos there; the relevant one for understanding the opening and closing is on the left hand column, second one down under “Reactors and Pressure Vessels”. Envision one of these with a boltless split ring closure; an o-ring seal would eliminate the need for tightening bolts. The o-ring must be specified for use with CO2, but this is doable; as you’re probably aware, CO2 destroys o-rings of many flavors but it is a manageable problem. However, kbd512’s concern about abrasive dust may yet slay the o-ring design altogether. A compressed flat gasket will be more resistant to this real-world complication. Or use an already sealed vessel with a simple ball valve on top for solid CO2 loading; the ball valve seat tends to wipe solids away as the valve is closed.
This may well knock Parr out of the running, but I’m not certain that our vessels are competitive at this pressure range of 100-200 psi. A 1-gal vessel from us will cost perhaps $10K USD, as opposed to a welded fabricated vessel for closer to $1K. When you get to pressure vessel manufacturers, there are roughly two types: sheet metal fabricators and milled pressure vessel manufacturers like Parr. The sheet metal fabricators take sheet metal, roll it and weld it, and 200 psi is the typical pressure limit. Milled pressure vessel manufacturers like Parr take solid metal bar and machine the inside out of it and we think 1900 psi is the right pressure limit.
The sheet metal approach can deliver a vessel for under $1K, and at this price point it makes sense to make them by the dozens and put them on the shelf until someone needs it. So if you go that approach you can likely get it immediately, but you’re unlikely to get it customized and it’s tough to get someone who can customize the design very far. The milled metal approach supports businesses who make things on demand, which really just means you’ll have to wait 6-8 weeks for it to be constructed, but it can be highly customized and would include a design phase where you can do things such as evaluate the seal feasibility and compatibility with the robotics available to you. And when you’re done it will weigh a lot; about 80-lbs for a 1-gal, though we can thin the walls down to maybe 50-lbs with some effort.
So for proof of concept you might want to try a less expensive sheet metal vessel. It’s immediate and cost effective. But don’t expect to customize it to vet feasibility of use. For that you’re likely into a milled vessel which will take 4-6 weeks, cost much more, and weigh a lot more.
I hope this helps. Please let me know your thoughts!
Best regards,
Conan
From: tahanson43206
Sent: Saturday, April 3, 2021 1:19 PM
To: Collins, Conan <conan.collins@parrinst.com>;
Subject: 20210403 Fwd: Fw: United States - Custom Systems Google search for clamshell pressure vessel
Dear Mr. Collins,
Thank you for your helpful and encouraging reply to my inquiry!
Please note that I posted a link to an image from your web site to advance discussion.
http://newmars.com/forums/viewtopic.php … 99#p178199
By any chance, do you have (or can you point to) YouTube video (or equivalent) showing how an operator works with the example pressure vessel?
As noted in my post, the pressure we are contemplating is on the order of 100 psi with a high of 200 psi, so 1900 psi is a bit stronger than needed.
Please note that in addition to the Mars application, I am definitely interested in the Earth-side potential of a Dry Ice Pneumatic tool supply system.
A cubic foot (7 gallons) is the size of chamber I am thinking about for an Earth-side demonstration.
<snip>
(th)
]]>I think your point about having pressure greater in the boiler than is needed by the tool makes sense, but I'm pretty sure we don't need to exceed 8 ATM.
The possible exception might be the tool that is used for Brake testing, which needs 10 ATM.
The greater the pressure to be held by the tank the greater the mass of the walls.
For that reason, I recommend trying to avoid going as high as 20 ATM ...
1900 psi is the capability of the precision chamber shown in a post earlier in this topic ...
1900/15 >> 380/3 >> 126 ATM ... we don't need to go anywhere ** near ** that high for this application.
If you visit a show room with Pneumatic tool equipment, you'll get a sense of the scale of equipment in daily use in the United States and probably elsewhere.
The difference with ** this ** application is the need to admit heat into the interior of the boiler, and for that the example of steam boilers would appear to point the way forward.
The challenge for all designs is how to deal with the initial state of the feed stock, which is solid at 1 ATM, or in the case of Mars, a fraction of an ATM.
(th)
]]>https://www.finepowertools.com/air/comp … ct-wrench/
CFM Chart: Impact Wrench Air Consumption
Tool Size Air Consumption Pressure
1/4-inch Impact Wrench 2 CFM 90 PSI
3/8-inch Impact Wrench 3 CFM 90 PSI
1/2-Inch Impact Wrench 5 CFM 90-100 PSI
3/4-inch Impact Wrench 7 CFM 90-100
https://tooltally.com/what-size-air-com … do-i-need/
TOOL REQUIRED PSI REQUIRED CFM @ 90 … SUGGESTED COMPRESSOR SIZE:
Sand Blaster (#4 Nozzle) 60-125 70 Rotary Compressor
Disc Sander 90-100 20 80-Gallon
Dual Action Sander 90 15 80-Gallon
1" Impact Driver 90-100 12 60-Gallon
https://www.redhillsupply.com/air-compr … -info.htm/
AIR TOOL PRESSURE R… PORTABLE TOOLS AIR COMPRESSOR CFM … AIR TOOL PRESSURE R…
70-100 Air Filter Cleaner** 3.0 HAMMERS
70-100 Body Polisher** 20.0 90-100
70-100 Body Sander (Orbital)** 10.0 90-100
70-100 Brake Tester 4.0 125-150
Bravo for thinking ahead to the need for continuous service to tool users! I'm thinking of a factory as the most likely setting for this, but it could just as well be robot avatars working in an excavation deep into a scarf.
The ability to switch boilers into and out of the gang of boilers would help greatly!
While the initial testing will necessarily be limited to a single container, the goal of parallel piping for a gang of boilers is attractive!
***
Regarding your 20 ATM ... The target pressure is 7 ATM.
The maximum pressure needed by any commercial pneumatic tool is (unknown to me at present)
I went to Google and found this:
Most tools are rated at 90 or 100 psi, so using 120 psi regularly ensures you will be replacing expensive air tools in half the time you should have to.
Air Tool Pressure + 5 Reasons To Use The Right PSI For Air Tools ...
www.vmacair.com › blog › air-tool-pressure-5-reasons-use-right-psi-air-tools
About Featured Snippets
120/15 >> 24/3 >> 8 ATM maximum at the tool head.
You **might** want to run the boiler at 9 ATM assuming the regulator is good at dropping the pressure to 8, but in any case, this system is NOT going to be operating at 20 ATM. That said, a partial presence of liquid may help with heat transfer. As a reminder [Dayton Engineer] cautioned heat transfer to dry ice may be a challenge, although we won't know until we (someone/anyone) tries it.
(th)
]]>The regulated pressure out to the tool must have a greater pressure contained in the tank to give the desired flow to the tool.
Starting at the 20 Atm and going accross to the 20' C you will see that its going to transition from solid to liquid then to a gas as you cross the -20' C on the triple point line. The triple point of -56.57' C at 5.11 Atm just means you can have slush in the tank but the pressure is not useable and the outlet temperature is to cold for use.
I was looking for the way to be able to open the boiler so as to fill it to keep the pressure for the tool useable as with the single tank approach the tool stops working to fill it. That means a multiple intermediate tank is used to maintain the outlet pressure in a liquid form and with mars temperatures it would stay that way in this tank as a mixture of co2 gas with it. The final tank holds the co2 gas which still can be warmed to boost the pressure and working temperatures for a human used tool. Each tank has a check valve to keep back flow from occurring as the co2 is feed from the boiler to the next tank and so on until it exits the tool.
The boiler takes the most energy to bring the solid up to pressure to feed it into the liquid storage tank with each step takes a lower storage pressure but the same amount to create pressure to make the tool operate.
]]>Thanks for putting those graphs together ... The ATM one was immediately helpful, because the target pressure is 7 ATM.
It appears (I'm hoping for correction if I misunderstand this) that the triple point may occur as a load of dry ice is warmed to 20 C.
However, I'm wondering if this would actually be beneficial?
In a steam engine on Earth, water is adjacent to the hot fire tubes in a boiler (thanks again to kbd512 for direction on that point), but the end result is gas. What it may be impossible to know is the ratio of water to steam that may be present next to the fire tubes. The same may be true in a dry ice boiler.
Perhaps it doesn't matter ... the desired end result is ** all ** the solid converted to gas, and if some of the CO2 passes through a liquid phase I suspect it won't matter because (as your charts both show) CO2 is a gas at the operating temperature of 20 C.
I'm on the verge of feeling confident enough to call Miura ....
I think a working steam engine boiler manufacturer is a much better match with the problem at hand than any of the alternatives I've seen to date.
The quirk of the Mars Dry Ice challenge is the method of feeding raw material into the boiler. Presumably, the smaller the opening the better, but on the ** other ** hand, (remembering caution from SpaceNut and kbd512 about contamination of the Dry Ice feedstock) it seems advisable to design the boiler so the clinkers can be removed, just as they were for hundreds if not thousands of years for coal/wood fired heating systems.
** None ** of the tanks shown in the bottom graphic in Post #97 appears (to my eye anyway) to be designed to open for cleaning.
(th)
]]>here is that triple point chart in Celsius but pressure is in Mpa not PSi or ATM
This one is in ATM
here is the typical co2 tank that would hold the final pressure for the tools to make use of.
Thanks for continuing to think about the Dry Ice heating situation!
For a point of clarification, the CO2 has to be brought up to a temperature closer to what we humans consider "normal" (ie, 70 degrees Fahrenheit or 20+ C)
The tool needs to be kept cool, so it is good to keep the gas temperature low, but it can't be too low either. In your planning for heating (however you decide to do it) please plan to heat your gas to just below 70 degrees at 90 psi.
If you can get a chance to make some sketches of your idea, it would be interesting to see them.
The example of steam boilers (prompted by encouragement from kbd512) reveals that humans long ago decided to run heating tubes through boilers to more efficiently transfer gas heat to liquid water to produce steam.
A complication (pointed out by [Dayton Engineer], is that dry ice is NOT well suited for heating, since (of course) it is not a liquid, and CO2 will go straight from solid to gas without going through the liquid phase in this situation. (as I understand the process).
The only way forward from here (that I can see) is to run an experiment with dry ice in a pressure cooker for canning. The run will be limited to 15 psi over ambient, but it should serve to confirm heating calculations provided earlier in this topic, and more importantly, it should reveal the physical behavior of molecules of CO2 in this situation. Heat will be applied to the base of the container and it will be conveyed to the interior by conduction through aluminum.
On the ** inside ** of the container, the dry ice will be in partial contact with the base of the container.
Some of the heat will flow into the dry ice by conduction, and liberated CO2 will allow more heat to flow via convection. The ratio of conduction to convection should decrease as more CO2 is liberated, until conduction drops to zero as the dry ice is exhausted. At that point, all heating will be by convection until the needed operating temperature (near 70 degrees Fahrenheit) is reached.
In the case of the simple cooker test, I would expect pressure to have set off the pressure relief valve, because (of course) a simple cooker cannot withstand the pressures needed for the tool.
From the experiment, it should be possible to (a) confirm heating calculations (b) determine efficiency of heat flows over time and (c) obtain a sense of the rate of progress of sublimation of the dry ice over time.
(th)
]]>tahanson43206,
Why would you want to unevenly heat the tank from the exterior instead?
You have less to bother with if the heating element is inside the tank (a metal pipe inserted through the mouth of the tank). Externally heating the tank with Methane or Propane is a good way to mess with the temper of the steel or Aluminum, which is probably not something you want to do to a pressure vessel. When the heating element (whatever that happens to be) is inside the tank, more of the heat is directed into the dry ice or resultant liquid CO2, instead of into the surrounding environment. There's also less risk of annealing the part of the tank nearest to the flame, since the solid / liquid / gas absorbs more of the heat. Uniform heating is a good thing.
The issue is the pass through holes required to isolate the metal can from the wired connections under pressure shifts from the minus values to the positive number which is not known for the heating element.
Thats why I was looking at other options such as small expansion tanks that are ganged to produce the volume at pressure from a liquid which is more dense than the dry ice and since its got to be under pressure it better suits the application where in we are making a small shift in temp to get pressures. Dry ice has no pressure in the boiler and must be brought up to pressures at higher temperatures.
]]>SearchTerm:Heating boiler for pneumatic tool gas supply
Hopefully that search term will help to find Post #93 in future: http://newmars.com/forums/viewtopic.php … 87#p178387
Do you have a suggestion where to look for prints of the ship boilers on the vessels you mentioned?
While they were (probably) orders of magnitude larger than even the largest steam locomotives, I'll bet the design principles were similar.
In thinking about this, I realized that images of sailors stoking the boilers of steam powered vessels (such as the Titanic but many others) is probably where I got the idea that heat might have been applied to the exterior of the boiler. I now understand (thanks to your hint and Wikipedia showing reality) that such boilers incorporate pipes to carry hot gases through the volume of the boiler so that heat flows to the water blanket with as much surface area exposed as possible.
How an engineer would design for the peculiar properties of dry ice is something I'm hoping to see, at some point.
***
In the mean time, absent any existing hardware, I'm thinking of investing in a cooking pressure vessel, to experiment with dry ice within the limits of the equipment. It should be possible to measure energy input accurately (electric or propane) (or natural gas since I have a grill but I'm not sure how to measure the flow in that case). If I use a propane tank I can measure the weight before and after a run.
It would be possible to measure the temperature of the gas inside the container. The pressure itself will be revealed by the gauge on the device, and by the safety valve, if it goes off, which is possible.
Edit#1: There are wireless sensors that could be dropped into a pressure cooker to measure the temperature, but I'm not sure how well the RF would make it's way out of an all aluminum Faraday Shield. Perhaps the answer to ** that ** question is to drill a hole for a tight fitting probe, since the pressure is low (only 15 psi greater than ambient)
The time required to move from dry ice dropped into the container to safety valve release could be measured.
The amount of dry ice remaining in the container could be measured, assuming there is a pressure relief valve on a pressure cooker. I'd assume there must be one, but I've never owned one, and I was too young to understand the process when my folks used one for canning.
Thanks for the tip about your first ship ...
USS Blue Ridge (LCC-19) - Wikipedia
https://en.wikipedia.org › wiki › USS_Blue_Ridge_(LC...
USS Blue Ridge (LCC-19) is the lead ship of the two Blue Ridge-class amphibious command ships of the United States Navy, and is the flagship of the Seventh Fleet.
Homeport: Yokosuka, Japan
Namesake: Blue Ridge Mountains
Draft: 28.9 ft (8.8 m)
Status: In active service
History · 1971 · February - WestPac I · Evacuation of Saigon
Impressive she's ** still ** in service !!!
(th)
]]>The first ship I was on in the Navy, USS LCC-19 Blue Ridge, used boilers. It's one of two left in the fleet (her sister ship is Mount Whitney) that have boilers. Everything else is diesel, gas turbine, or nuclear powered. Back when I was in, USS CV-63 Kitty Hawk also had boilers, but that was it. IIRC, they de-commissioned JFK around that time, she was of the same class as Kitty Hawk, and also had boilers. That seems like a lifetime ago, but it was only a little over 20 years. Time flies.
We have to break the integrity of a gas storage bottle to put gas or dry ice into and to get gas out of the bottle. I'm talking about inserting the heating element through one end of the bottle. What if we insert the heating element at one end and the valve to get gas out is at the other end (heating element inserted through an orifice at the bottom, control valve at the top; orientation doesn't matter all that much, but still)?
]]>Thank you for your (interesting to me for sure) question ...
You used the expression "want to" .... I don't think the expression fits perfectly in this case ....
Human historical precedent goes back hundreds of years, if not thousands if you include cooking by boiling water in the scope.
The design of steam engines (which are fresh on my mind) ** always ** involved external supply of heat.
That said, your introduction of the concept of heating **inside** boiler is interesting on a number of levels.
The solution you devise will necessarily break the integrity of the boiler skin, but the benefit of even distribution of heat energy to the interior of the cavity may well be worth the risk of the additional port.
That said, I accepted your lead and asked Google about precedent for fire inside a steam boiler. Boy! Did I get a quick correction to my (obviously limited) understanding of the design of steam engines.
It may have been a while since I commented here on the forum about the progress of Google's AI ... it is ** really ** coming along.
With only the **simplest** of clues it took "steam boiler with fire inside the cavity" and came back instantly with images and drawings, and also the somewhat discomfiting text from Wikipedia:
Fire-tube boiler - Wikipedia
en.wikipedia.org › wiki › Fire-tube_boiler
This type of boiler was used on virtually all steam locomotives in the horizontal "locomotive" form. This has a cylindrical barrel containing the fire tubes, but also ...
Someone with the background of Calliban would have (of course) known this, but (for whatever reason) I did not.
OK .. reset! .... Steam engines operated at pressures above the 90 psi which is the target for this exercise.
Apparently running fire tubes through the middle of the boiler was not only done but ** common **
In the present instance, taking SpaceNut's idea of multiple boilers instead of one large one, and also taking into account the equal distribution of pressure between smaller boilers due to the known behavior of gases in free space, I am now beginning to glimpse a scenario where combustion gases (propane on Earth and CO on Mars) flow through tubes ** inside ** the boiler(s) to insure an even distribution of heat to the interior of the vessels.
I have received an invitation to call Miura Steam Boilers, but I'm holding off until I have a better sense of the topic. I expect to only get one chance to make a good first impression, and my objective would include attempting to interest their management in supporting the Mars Society by participating in design of equipment for Mars. The company is small ... it only has 70 employees ... but it appears to be doing world-class work (at least that's my impression)
So! Thanks again for Post #91 ....
(th)
]]>Why would you want to unevenly heat the tank from the exterior instead?
You have less to bother with if the heating element is inside the tank (a metal pipe inserted through the mouth of the tank). Externally heating the tank with Methane or Propane is a good way to mess with the temper of the steel or Aluminum, which is probably not something you want to do to a pressure vessel. When the heating element (whatever that happens to be) is inside the tank, more of the heat is directed into the dry ice or resultant liquid CO2, instead of into the surrounding environment. There's also less risk of annealing the part of the tank nearest to the flame, since the solid / liquid / gas absorbs more of the heat. Uniform heating is a good thing.
]]>