Carbon and Water Shipped as Reactants >> Methane and Oxygen

tahanson43206 · 2023-11-13 18:36:22

For kbd512 re #25

Post #25 appears to contain important and useful content.

This topic is set up to perform research on a specific concept, and to report the results, regardless of how they turn out.

(th)

SpaceNut · 2023-11-13 19:02:44

What I have not found is the rocket engine that has been used in all of the tests fuels.

tahanson43206 · 2023-11-13 20:24:08

Here is a table showing pressure increase as liquid hydrogen is warmed inside a closed container:

Predicted Pressure Changes in a Closed Container as Liquid Hydrogen is Heated
Temperature (°C) Pressure (Pa) Pressure (bar)
-252.87    485,423    4.85
-152.87    2,879,027    28.79
-52.87    5,272,630    52.73
47.13 7,666,234    76.66
147.13    10,059,838 100.60
247.13    12,453,442 124.53
347.13    14,847,045 148.47
447.13    17,240,649 172.41
547.13    19,634,253 196.34
647.13    22,027,857 220.28
747.13    24,421,460 244.21
750.00 24,490,157 244.90
This table provides a theoretical prediction of how the pressure inside a closed container changes as liquid hydrogen is gradually heated from -252.87 °C to 750 °C. The values are based on the ideal gas law and the assumption of ideal gas behavior.

Not shown in the table above is a supply of carbon atoms exactly matched to the supply of hydrogen. The goal of the exercise is to create conditions favorable for creation of covalent bonds, so that every available hydrogen atom is collected by every available carbon atom. The process of creating such bonds is exothermic, so the temperature in the chamber will rise further. It is this rise that will be read by instruments to determine the progress of the bond formation.

(th)

tahanson43206 · 2023-11-13 22:55:57

Here is the same table as shown in Post #28, revised to show that the process starts with liquid hydrogen loaded into the reaction chamber at 1 bar. The chamber is sealed, and heating is applied. The conditions favorable for natural production of methane occur at (about) 750 degrees Celsius.

| Temperature (°C) | Pressure (Pa) | Pressure (bar) |
|------------------|-------------------|----------------|
| -252.87 | 100,000.00 | 1.00 | <- Liquid state
| -252.87 | 485,422.84 | 4.85 |
| -152.87 | 2,879,026.61 | 28.79 |
| -52.87 | 5,272,630.37 | 52.73 |
| 47.13 | 7,666,234.14 | 76.66 |
| 147.13 | 10,059,837.90 | 100.60 |
| 247.13 | 12,453,441.67 | 124.53 |
| 347.13 | 14,847,045.44 | 148.47 |
| 447.13 | 17,240,649.20 | 172.41 |
| 547.13 | 19,634,252.97 | 196.34 |
| 647.13 | 22,027,856.73 | 220.28 |
| 747.13 | 24,421,460.50 | 244.21 |
| 750.00 | 24,490,156.92 | 244.90 |

Not shown in the table above is a supply of carbon atoms exactly matched to the supply of hydrogen. The goal of the exercise is to create conditions favorable for creation of covalent bonds, so that every available hydrogen atom is collected by every available carbon atom. The process of creating such bonds is exothermic, so the temperature in the chamber will rise further. It is this rise that will be read by instruments to determine the progress of the bond formation.

(th)

kbd512 · 2023-11-13 23:25:25

The 13.5MWe HolosGen reactor design is projected to weigh 22,680kg (1.68t/MWe), not including site shielding provided by in-situ materials, at an initial cost of $40M USD, with a total 20 year operational cost projected at $74M. If run at 10,125,000We output for 20 years (175,200hrs), providing 1,773,900MWh of electrical power, then total operational cost is about $422.375 per hour, or approximately 4.17 cents per kWh. The company wanted to sell power for 7 to 8 cents per kWh to turn a profit. It's designed to run for approximately 20 years before requiring refueling using replaceable sealed fuel catridges, and operational life of the other components is intended to last for 2 subsequent refueling cycles, for a total reactor lifespan of 60 years (all parts of the reactor retired). A fresh batch of HALEU / TRISO fuel cartridges for refueling is projected to cost $26M.

This would provide 243MWh of electricity per day. If a photovoltaic panel can provide 4kWh/m^2/day on Mars, then 60,750m^2 of panels is required. If each square meter of panel weighs 2kg, then 121,500kg (12t/MWe) of panels are required, which excludes all power cables and conditioning / distribution electronics and electrical power storage equipment. Storing half of the generated power, to contend both with what would otherwise be a wild power swing at noon and no power generated for half of the day, would require 607,500kg of Lithium-ion batteries, at 200Wh/kg at the pack level. I have no idea how much Copper wiring is required, but the photovoltaic array would cover 11.36 football fields (5,350m^2), so I assume it's a non-trivial tonnage of electrical cables. If each Starship can deliver 150t to the surface of Mars, then 1 Starship can deliver 6 reactors, for 60.75MWe / 1.458GWh of electricity per day. If all reactors were devoted to producing Hydrogen from Martian ground water, then we can make 35,132kg of Hydrogen per day. Obviously most of the power won't be used to do that, but that is the maximum Hydrogen generating capacity of the reverse fuel cells, at 41.5kWh/1kg of Hydrogen. We would need 5 Starships to deliver as much solar electrical power as a single 13.5MWe reactor.

We do need a small tracked vehicle to either dig a pit to bury the reactors or to pile the Martian regolith over the top of them. We need to figure out how to keep 11.3 football fields of solar panels sparkly clean if we opt for an all solar power solution. Putting all our eggs in one basket is a bad idea, so we should land at least one Starship with a cargo of photovoltaic panels, along with a healthy supply of Lithium-ion batteries for tools and small portable machines.

These nuclear reactors can't generate enough heat to melt the TRISO fuel pebbles if all coolant is lost, so the probability of a serious nuclear accident involving loss of fuel is pretty low. Sabotage or transportation accident cannot be ruled out, however. This has been tested using a full scale heating element test rig and subcritical (Depleted Uranium) fuel particles by heating them up to maximum thermal output and dumping all the coolant while the external heating elements continues to bake the fuel pebbles.

This was the feasibility study for powering Bagram Airbase in Afghanistan using a 13.5MWe HolosGen reactor:
Journal of Defense Management - Feasibility Study of a Micro Modular Reactor for Military Ground Applications, Kenneth S Allen, Samuel K Hartford, Gregory J Merkel, Department of Physics and Nuclear Engineering, United States Military Academy, New York, USA

So, with that much electrical power we can skip LCH4 as a rocket fuel, but continue to use much smaller quantities of CH4 or C3H8 as a fuel for fuel cell powered land vehicles to give them practical range and power output capabilities. H2 fuel could also be used, but hydrocarbon fuels are simply much easier to work with and don't make the fuel system components brittle.

We need the best energy source money can buy, which is a nuclear reactor. We should use the most performant rocket fuel money can buy, which is LOX/LH2. All other energy uses are debatable, as to which is best. Batteries, fuel cells, and heat engines all have major advantages and major drawbacks. There will be niche applications where one energy source performs better than competing options. However, access to real power supplies and the best rockets will be critical to minimizing cost and energy / mass waste.

kbd512 · 2023-11-14 22:49:29

To liquefy the 2,300kg of LH2 in a Centaur stage, at prototypical industrial liquefaction plant efficiencies, will require 15kWh/kg of H2, which means an additional 34.5MWh of electrical power. Some cryocooling methods can actually use waste heat from the reactor, so this is highly desirable if possible to use.

SpaceNut · 2023-11-15 18:32:06

So at that point we make a slurry of carbon in hydrogen and inject it into a heated chamber and out comes is pure methane. Of course we need more energy for cooling and pressurizing. But the size of the tanks to deliver and store to reduce cost must come from dead cargo ships to make this work.

tahanson43206 · 2023-11-16 12:34:50

For SpaceNut re #32

Thanks for thinking about how this system might work. Today I spent some time investigating the exothermic reaction that is the end point for the reaction we are considering in this topic. The reaction is greater than I had anticipated, but it is what it is. here is a snippet from today's work session:

Starting materials:
Carbon(solid):
Mass: 0.0421 kg
Volume: Approximately 0.00001913 m³
Hydrogen (Liquid):
Mass: 0.0141 kg
Volume: Approximately 0.000199 m³
ChatGPT
Let's conduct a reasonableness check of the pressure increase estimate based on the given reaction mass:
Initial Data:
Carbon (Solid):
Mass: 0.0421 kg
Volume: Approximately 0.00001913 m³
Hydrogen (Liquid):
Mass: 0.0141 kg
Volume: Approximately 0.000199 m³
Reasonableness Check:
Energy Release Calculation:
The calculated energy release from the formation of methane (5777.08 kJ) seemed reasonable given the amount of carbon and hydrogen. This is based on standard bond energies.
Temperature Increase:
The temperature increase to 1849.41 °C (2122.56 K) from 750 °C (1023.15 K) is significant. This calculation considered the average heat capacity of the system, including the steel vessel, carbon, and hydrogen.
Pressure Increase:
The estimated pressure increase to about 508.26 bar is based on the ideal gas law, assuming constant volume and the number of moles of gas.
The ideal gas law is a simplification, especially at high temperatures and pressures, and for reactions involving phase changes.
Potential Factors to Reconsider:
Heat Capacity at High Temperatures: The specific heat capacities of materials can change significantly at high temperatures. Our calculation used average values, which might not accurately represent the behavior at such extremes.
Non-Ideal Gas Behavior: Hydrogen at high temperatures and pressures may not behave as an ideal gas. This could affect the pressure calculation.
Phase Changes and Reaction Dynamics: The phase change of hydrogen from liquid to gas and the dynamics of the methane formation reaction add complexity to the system.
Conclusion:
While the energy release calculation appears reasonable, the resulting temperature and pressure estimates are approximations that could be affected by the factors mentioned above.
Given the potential for high pressures, it would be prudent to revisit the experimental design and calculations with more detailed models or empirical data, especially for the heat capacity at high temperatures and the behavior of gases under these conditions.

The figure of 414 bar used for comparison comes from commercially available gas storage tanks.

Apparently a nickel catalyst could reduce the temperature needed to initiate the formation of covalent bonds, but what effect that would have is for study on another day. Apparently nickel is commonly used for this purpose in Sabatier.

(the)

SpaceNut · 2023-11-16 19:18:27

No need to have that much pressure as the Sabatier reactor is way less.

https://en.wikipedia.org/wiki/Sabatier_reaction

The Sabatier reaction or Sabatier process produces methane and water from a reaction of hydrogen with carbon dioxide at elevated temperatures (optimally 300–400 °C) and pressures (perhaps 3 MPa) in the presence of a nickel catalyst.

[url=https://ntrs.nasa.gov/api/citations/20120016419/downloads/20120016419.pdf]Compact and Lightweight Sabatier Reactor for Carbon
Dioxide Reduction[/url]

simple reactor tube

tahanson43206 · 2023-11-16 19:38:01

For SpaceNut ... thank you for finding and posting the image and link in #34...

The situation is not the same .... the example you found is for Carbon Dioxide fed into the reaction chamber, along with hydrogen and in the presence of the catalyst.

This topic is not about CO2 in any way, shape or form, EXCEPT as one of the outputs when the product is burned with oxygen.

The reason the temperature and pressure are higher is because the inputs are pure Carbon and Hydrogen. There is NO oxygen present. The oxygen is removed from water shipped from Earth, and the Hydrogen is delivered to the reaction chamber along with free Carbon atoms.

Still, thanks very much for the research! It had me hoping for a moment, until I read the fine print.

I think you'll find that pure Carbon begins to react with Hydrogen at about 750 Celsius, and about 245 bar.

The use of a nickel catalyst ** might ** make a difference, but it is possible this has never been tested.

(th)

SpaceNut · 2023-11-16 20:13:56

A slurry is fed into the inlet and a float device controls the amount that is heated in the chamber so that gas will come out of the outlet. Heat is lowered by the correct catalyst selection. The solid carbon is in a powder form in the liquid hydrogen so as to be able to keep pushing more in as the rate of outlet rises.

tahanson43206 · 2023-11-16 21:44:11

For SpaceNut re #36

Please see if you can find an example of the concept you'd described. It seems to me as though you are adapting the Sabatiet concept to this new situation. A continuous flow version of the reaction would be helpful, if you can find documentation to support it.

I've chosen to follow the model provided by actual experiment, and the deductions of the geophysicists examining the historical record. You may be onto a good idea and I hope you'll pursue it.

It is ** good ** to have multiple initiatives under way in any of the many NewMars topics.

(the)

tahanson43206 · 2023-11-17 11:35:22

Today's post reports on an encouraging development in this inquiry....

In attempting to compute the temperature increase in the reaction vessel due to the exothermic reaction, ChatGPT's first attempt led to a result that meant the concept of this topic would not work. I suspect the incorrect result was due to missing the mass of the reaction vessel, compared to the very much smaller mass of the reactants. After spending some quality time working the problem, ChatGPT found a much more favorable result.

User
Now with these results fresh in mind, please apply the thermal energy released by the exothermic reaction, to see what happens to the system. Here is a quote from your earlier work: The calculated energy release from the formation of methane (5777.08 kJ) seemed reasonable
ChatGPT
After applying the thermal energy released by the exothermic reaction of methane formation to the system, the results are as follows:
Temperature Increase Due to the Exothermic Reaction: The temperature of the system is estimated to increase by approximately 76.26 K (Kelvin) due to the exothermic reaction.
New Estimated Temperature of the System: With this temperature increase, the new estimated temperature of the system is approximately 1049.33 K (about 776.18 °C).
Analysis:
The increase in temperature caused by the exothermic reaction of forming methane is substantial, but not as extreme as previously calculated.
The large heat capacity of the system, particularly due to the significant mass of the pressure vessel, helps to moderate the temperature increase.
This new temperature is still within the operational range of high-grade steel and other materials typically used in pressure vessels, as discussed earlier.
These findings suggest that while the exothermic nature of the reaction does increase the temperature of the system, the effect is somewhat tempered by the large thermal mass of the pressure vessel. This result aligns more closely with your initial concept and indicates that the process might be more manageable than previously thought.

In a practical manufacturing facility, it will be desirable to draw off the methane as soon as the reaction has completed. This will leave the reaction vessel itself at a temperature very close to the temperature after the completion of the reaction. In other words, the reaction vessel will have a temperature above 750 degrees Celsius. We will inject a new batch of reactants using a piston, and seal the reaction vessel. The goal is to need to add ONLY enough external energy to bring the reactants back up to 750 Celsius.

The methane that is drawn off will be held in another pressure vessel that is exposed to space, so the methane will rapidly cool toward the desired selling condition of liquid state. It is desirable to invest as little additional energy as possible cooling the methane to liquid, so the more that can be assigned to space the better.

(th)

SpaceNut · 2023-11-17 18:50:19

A Sabatier reactor is a design that has inlets of co2 but the topic is a solid carbon and a quest as to whether the water is electrolyzed or as steam. These choices ca\hange the equipment and power requirements.
If we do the liquid hydrogen with solid carbon then a chamber is a slurry mixture with catalysts and rise in tempoerature to vent methane at the top.

Effect of Solid Particles on the Slurry Bubble Columns Behavior – A Review

https://en.wikipedia.org/wiki/Bubble_column_reactor

The liquid will have a float switch near the top to monitor if more slurry is required on more temperature to form the buubles of gas.

https://www.sciencedirect.com/topics/ch … ry-reactor

This uses a Fischer-Tropsch Synthesis

3-s2.0-B9780444563309000127-f12-16-9780444563309.gif

tahanson43206 · 2023-11-17 21:11:58

For SpaceNut re #39

Thank you for the very interesting (and timely) additions to this topic.

SearchTerm:Sabatier ... vertical version with images

SearchTerm:Fischer-Tropsch Synthesis

These are both valuable to keep in mind as this topic proceeds.

***
It is highly likely there are few if any NewMars members who are actually following the progress of the topic. The posts that appear here from time to time will hopefully add to the interest value of the topic for someone who might have discovered it while searching the archive for something else. While some posts may not relate directly to the topic, they ** do ** connect to the overall theme, which is delivery of 1200 tons of propellant to a landed Starship on Mars, or to a visiting Starship at Phobos.

It seems to me that the on-Mars scenario is fairly well understood. It is the Phobos Re-fueling station opportunity that interests me. I am betting that a supply of propellant already produced and waiting in inventory for a buyer will attract serious attention , as compared to a hypothetical supply that might be manufactured on Mars if everything goes smoothly at every stage of the process.

This is very simple, easy to understand business play. The bet is that a bird in the hand is worth two in the bush, and that the bird in the hand is worth whatever the seller asks.

In the work session reported earlier today it was established that the energy produced by the exothermic reaction to make methane will NOT overwhelm the pressure vessel, as a first draft of the calculation had indicated might be the case. An almost immediate positive consequence of this clarification was the realization that in a production system, the reaction vessel can be kept at the reaction temperature, so that batches can be introduced as a liquid stream, heated until the exothermic reaction occurs, and then bled off when the reaction completes. In other words, the cycle time for each batch would appear to be limited by the time required for the reaction to proceed through all the atoms in the batch. Once started, a given reactor vessel could be kept in operation 24*7*240, which is the time anticipated for a flight by a Starship from Earth. The number of reactor vessels would be determined by dividing the output of each machine into the daily throughput of five tons of propellant. Each reactor vessel would be supported by associated subsystems, including power, electrolysis, cooling and reaction management subsystems. I am beginning to be able to visualize how each reactor could be packaged as a unit, which would be assembled in LEO and shipped to Phobos by slow freight, well ahead of arrival of reactants.

(th)

tahanson43206 · 2023-11-17 22:25:09

For SpaceNut re topic progress ....

Thank you for stopping in from time to time to give the topic a nudge, or a boost as the case may be ...

I've just given ChatGPT it's next assignment, and apparently it is a doozy .... it went off to it's place-of-cogitation several minutes ago and all I'm getting now are Page Unresponsive messages ...

However, even if we have to Regenerate from here, as seems likely, the stage is set for a very interesting development ...

We seem to have established that the concept is going to work with commercially off-the-shelf reactor pressure vessels. The temperatures and pressures required to convert a batch of Carbon and Hydrogen to Methane ** without ** catalysts of any kind are ** within ** the range of a top end commercial vessel.

The task I gave ChatGPT was to try to compute the cycle time for a batch. I gave it a total time for mechanical systems to perform removal of methane and delivery of the next batch of Carbon and LH2 as 60 seconds. I am assuming human engineers are capable of designing port management hardware that can perform these operations within 60 seconds. The methane will be under tremendous pressure (under 414 bar) so it will be happy to escape the chamber. The LH2/Carbon mix will be in liquid form so easy to shove through a cylinder with a piston. The valves need time to screw back into place.

ChatGPT just came back ... OK .... it "thinks" the cycle time might be as little as a few minutes, to as many as tens of minutes. For this post, let's assume a cycle time of 30 minutes, so 48 batches per day. The test system is very small, since the point of the exercise was to see if the process would work at all. We do not yet know how large the batch can be for a real, commercially available reactor vessel. That number is needed to complete the estimate of productivity of one reactor vessel and it's associated support systems.

I just asked ChatGPT to estimate the throughput of our test system in a day, using the estimate of 30 minutes per batch.

The amount of Carbon in the imaginary test system is .0421 kg (42.1 grams) ....

I asked ChatGPT to find the output methane since it had already computed that, but instead it decided to compute the output all over again.

OK! The answer showed up ... so our imaginary little test system can produce 2.7 kg of methane per day.

As a reminder, the test system is a cylinder of 1 centimeter diameter and 30 meters length. This is a completely arbitary shape and volume. It derived from the approach taken at the beginning of the investigation to see if could be made to work at all.

In future work sessions, we will attempt to discover how large the reactor vessel can be, and how large the batches can be.

We are looking at a commercially available reactor vessel that is rated for 414 bar, well above the maximum pressure we've calculated for our batch without a catalyst. It is possible a catalyst might lower the temperature of the reaction but from my point of view that is irrelevant. What ** is ** of interest is reaction time .. if a catalyst can reduce reaction time, then it is worth considering. If the reaction does not improve with the aid of a catalyst, then I see no point in bothering with it.

However, those are questions for another day. We close ** this ** day with a theoretical output of 2.7 kg of methane per day, with 42 gram batches of carbon and the associated hydrogen processed 48 times per day.

In practice, we may be able to do better in time, but at this point, that is pure conjecture.

We ** can ** expect to do a lot better in batch size. 100 kg batches of Carbon would yield 6,428 kg of methane, well above the goal of 5 tons per day.

Well well! So 1 kg batches would yield 6.4 kg per day, and we would need under 100 reactors operating full tilt.

The maximum reactor size is (probably) somewhere between 1 and 100.... Hopefully future iterations of this discovery process will reveal the answer.

(th)

SpaceNut · 2023-11-18 12:07:37

Most likely the tanks of a ship will be made use of rather than tying up mass with bringing others for this purpose. We are still going to need to prototype this unit for testing so that its capability is well known for its robustness and output as well as energy consumption.
Making the slurry will be one challenge from the cooling of hydrogen from electrolysis of water that will need supercooling equipment and a mixing chamber for the carbon powder to be added to the liquid before injection into the vertical reaction chamber.

tahanson43206 · 2023-11-18 12:20:25

For SpaceNut re #42

This is an opportunity for me to give you some positive feedback

Your suggestion of using spaceship tanks to hold output from the manufacturing facility is sensible and helpful.

The manufacturing facility itself is going to be purpose built and nothing from an ordinary spaceship would have a place there.

You have been reminding readers of this topic of the Sabatier process. I found a place for that ... on Earth, making pure carbon from captured CO2.

CO2 has no place in this topic, except as an input on Earth, and an output from the customer vessel burning the methane and oxygen from this facility.

To try to help you to understand what I mean by "purpose built" ... the reaction vessel is (apparently) going to be heated to (about) 750 degrees Celsius and held there for as long as batches of reactants are supplied and methane is produced, which could be 240 days if a customer vessel is expected, or all year if business is good. The vessel must be able to hold together at hundreds of bar, which (of course) no spacecraft component could do, with the possible exception of the combustion chamber of the rocket engine, and ** those ** have no place in this topic, except as consumers of the chemicals to be produced.

(th)

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#26 2023-11-13 18:36:22

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#27 2023-11-13 19:02:44

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#28 2023-11-13 20:24:08

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#29 2023-11-13 22:55:57

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#30 2023-11-13 23:25:25

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#31 2023-11-14 22:49:29

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#32 2023-11-15 18:32:06

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#33 2023-11-16 12:34:50

Re: Carbon and Water Shipped as Reactants >> Methane and Oxygen

#34 2023-11-16 19:18:27

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#35 2023-11-16 19:38:01

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#36 2023-11-16 20:13:56

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#37 2023-11-16 21:44:11

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#38 2023-11-17 11:35:22

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#39 2023-11-17 18:50:19

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#40 2023-11-17 21:11:58

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#41 2023-11-17 22:25:09

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#42 2023-11-18 12:07:37

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#43 2023-11-18 12:20:25

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