Refining fuel

[khadaji2002]

I'm reading through Mongoose Traveller and ran into a question. I've checked my CT rules and T20 rules and didn't find the answer. My search-fu is not the greatest, so here I am. The question is this:

What percentage of unrefined fuel is lost in the process of refining it?

With every substance I know of the process of refining results in some amount of loss. I can see not worrying about the amount lost if you're skimming a gas giant as you factor that into the time spent refueling. However, processing the fuel from unrefined to refined should result in some amount of loss as you rid the fuel of undesirable elements.

Does anyone have a canon source, or even a home rule for this?

 

[Enoki]

I think it would depend on what you're using as the original molecule.

For example, H20 gives you the L-Hyd and the oxygen could be retained for atmosphere on the ship.
NH3, same thing. You get they L-Hyd and the nitrogen is used for atmosphere or for pressurizing other systems.
CH4, there might be an issue with the carbon as waste but you are getting a lot more hydrogen too.
Of course, you might end up having to get the hydrogen from some other molecule too. That in itself could be an issue. Is a fuel refining plant on a ship set up to process any molecule with hydrogen in it? If not, is the molecule you have available one it can process?

Of course, it would also depend on the nature of your storage tanks. If you are storing this precursor as a gas you can pressurize the tank to higher or lower pressures to obtain the same volume of hydrogen atoms / molecules. As a liquid, not so much.

A bigger problem I'd think is if you are using the same tanks to store the unrefined fuel as refined fuel. This could be a serious problem with contamination of the refined fuel.
Since refining enough fuel to fill a ship's tanks, at least by MT, could take anything from hours to days depending on the size of the processing plant this could be a real problem. Do you load unrefined fuel then process it? Or, do you process it into refined fuel loading it as you go?

 

[ShawnDriscoll]

Are there rules for air supply on ships? What to use to produce it? To recycle it? To circulate it?

 

[Condottiere]

One of the Belter supplements, I think.

Other than that, monthly cost on occupied staterooms and/or equivalent.

 

[khadaji2002]

Enoki, thank you for the post. I'm not sure I made myself clear in my opening post. My question is:

How much unrefined fuel is lost in the process of refining it?

I'm not enough of a science guy to care what source the hydrogen comes from. I'm only worried about how much is lost. So if the crew collects 40 dTons of hydrogen in the unrefined state, then process it into refined fuel, how many dTons of refined fuel did they collect? 40? 30?20?

Shawn and Condottiere, I appreciate the question of recharging the ship's atmo. Would you mind moving to another thread if you're pursuing the question further? Thank you both!

 

[Enoki]

The problem here is what the density of the liquid is. That is the amount of liquid (or gas) you have within a certain volume is determined by temperature and pressure if the volume is solid with liquid (completely filled) and in every case with a gas.

That is, you are dealing with a volume of liquid here. Since metric tons is the measure there are 1168 (rounded) liters in that volume. The only sure way would be to know the number of moles of molecules of whatever you have convert that to liters, then you can get the metric tons you have. A simple instruction video for you

https://www.youtube.com/watch?v=vViS42XM3C4

For liquids it's a bit more complex as the mass of the molecule you are using needs to be known. From that you get grams per mole that convert to metric tons of that substance.

So, for liquids, the answer is it depends on what you are making the L-hyd from to begin with.

Now, the question is moot is you are converting the whatever molecule directly to L-hyd and simply off gassing or otherwise getting rid of the waste as you do it. The only time it might matter is if you filled your fuel tanks with something other than L-hyd and then refined it afterwards.
I prefer not to allow the later as you would be contaminating the tanks with something other than L-hyd, so you'd always end up with contaminated (eg., unrefined) fuel.

 

[kilemall]

CT HG rules only rate fuel purification by amount of plant needed per 1000 tons of fuel.

CT TCS is the operational aspect of HG and provides more clues, specifically the refueling as both design choice and battle consequence in terms of fueling flexibility and therefore 'watering hole' vulnerabilities.

The key phrase to me is that a ship can pass through a gas giant once and fill up it's tanks in 7 turns.

This strongly suggests that refining occurs during the pass, which is why its' important to have enough 'realtime' fuel purifier built into the ship.

Therefore the answer at least by CT standards is, it doesn't matter what percentage of the unrefined gasses you scoop, it's getting processed right then and any wastes are being expelled immediately.

Where it counts to get an answer is pulling a fast one at the starport, buying unrefined fuel then refining it in the ship.

You would need to know how much unrefined fuel must be purchased in order to derive the 'right' amount of fuel the process needs to end up with full refined tanks.

So, assuming you allow the practice, on a game design perspective you need to figure out how much you want the unrefined option to cost, then whatever number that is that is your wastage.

So let's say your economics are that you want fuel to cost Cr300- fine, that means you require 3x the unrefined fuel as feedstock, and 2/3 of it is wastage.

Don't forget a fee opportunity to charge for taking away the waste product if it isn't usable by the ship.

Now if you want the practice to hurt or not be economical, here are a few options-

• Starport policy is to only sell you as much unrefined fuel as your tanks can initially hold (so they don't undercut their own refined fuel franchise). Figure out the wastage, and the rest of the fuel has to come from somewhere.
• Don't allow the 1/5 space rule for small ships, so the purifiers are too big for ACS or will use up all the profitable/operational cargo space.
• The practice is allowed, but the wastage elements are treated as hazmat/toxic and is a huge time/service cost to get rid of.

Bottom line, I'm sure there is a volume wastage amount you can derive from real world numbers, but I'd say make the numbers work for the world effect/ game you want to run.

 

[Enoki]

This is rough, but for game purposes, close enough. The three most likely candidates for conversion to L-hyd are water (H2O), ammonia (NH3), and methane (CH4). I'm sure there'd be others, but let's go with those as water is common, and the other two are the primary constituents of a gas giant.

By weight, the waste from converting water is 89% of the original material. This would be in the form of ozone (mono oxygen) or O2.
Conversion of ammonia results in 82% of the weight being waste material in the form of N2 Nitrogen.

As the waste from those two are gasses you could simply vent them. O2 might present an issue as it is flammable in many conditions.

Waste from methane is 75% of the material in the form of carbon, most likely as lampblack. This would be a solid you could dispose of later if disposal locally were an issue.

So, roughly, you'd need 10 metric tons of water to get a metric ton of L-hyd out.
You'd need about 5.5 metric tons of ammonia to get a metric ton of L-hyd out.
or,
You'd need about 4 metric tons of methane to get a metric ton of L-hyd.

That close enough?

 

[kilemall]

That's weight, but we are talking dtons, I think the volume might be a different ratio.

 

[khadaji2002]

Thank you both, kilemall and Enoki. What I'm hearing is that within the rules themselves there is no hard number that represents amounts lost when refining fuel. I agree that when refueling from a gas giant or cracking water on a planet the need to know wastage is often not present. However, if the crew is under time pressure that number may become important. So I'm going to pull a number out of a hat and go with that for my game, and note it in the margins of my rulebook so I stay consistent. I'll also consider how each starport is likely to react to ships refining fuel (I can see a frontier starport expecting ships to do just that, where a class A low-port would have a major issue with ships venting anything into the air.

So I have my answer. The rules appear to gloss this point over so I'm free to alter MTU to have a solid number.

 

[mike wightman]

Jupiter is about 90% hydrogen and 10% helium, since a ship skimming fuel is only dipping into the very upper reaches of the atmosphere you could argue that the % of hydrogen will be a tad higher.

The refining process has to remove impurities and vent the helium, then liquefy.

If instead you mine ice, every nine displacement tons of water will actually produce fourteen displacement tons of liquid hydrogen.

9 displacement tons of water is 9x14 = 126 tons by mass; 2/18ths of this mass is hydrogen, 2/18 x 126 = 14tons, 1 ton of liquid hydrogen is 1 displacement ton so 14 mass tons of hydrogen = 14 displacement tons
Put another way 1 displacement ton of liquid water will refine into 1.56 displacement tons of liquid hydrogen.

You can do similar calculations for ammonia - solid ammonia ice is 3/17ths hydrogen and has a density of 0.82 tons/m^3;
14m^3 of ammonia ice is 11.5 tons, from this you get 2 displacement tons of liquid hydrogen.

 

[pendragonman]

It is not specifically stated anywhere for (my guess) the following reason:

Molecular weight of water: ~18. Molecular weight of Oxygen alone:~16

So the molecular weight of hydrogen alone in water is ~2. So refined fuel would be one ninth of the collected refined fuel and thus drastically increase the refuel time AND drastically increase the number of scoop runs the ship has to make, with decreasing effect each time since there isnt seperate tanks for refined and unrefined fuels.

 

[aramis]

I'm reading through Mongoose Traveller and ran into a question. I've checked my CT rules and T20 rules and didn't find the answer. My search-fu is not the greatest, so here I am. The question is this:

What percentage of unrefined fuel is lost in the process of refining it?

With every substance I know of the process of refining results in some amount of loss. I can see not worrying about the amount lost if you're skimming a gas giant as you factor that into the time spent refueling. However, processing the fuel from unrefined to refined should result in some amount of loss as you rid the fuel of undesirable elements.

Does anyone have a canon source, or even a home rule for this?

Units note:
Tonne indicates megagram.
Td indicates displacement tons of 13.5 (MT) or 14 (CT, TNE, T4, T20) kiloliters.
SG specific gravity measured in units of water - SG 1 is 1 tonne per 1 kiloliter, and 1 gram per cc.

Well, we know that a skimming run of unrefined results in no loss in volume. But it probably also removes the non-hydrogen components (esp Helium, carbon, and oxygen; lithium as well, but it's not likely to be much). With Water, we know that it's dropping from 13.5 or 14 tonnes to 1 tonne.
So, in the case of Water to fuel, we're reducing mass by 74% (MT) or 71%(CT/TNE/T4). Now, given that H2O is 18 AMU, and the H2 is 2 of those, we've a discrepancy... but a small percentage being D20 , it's not quite as bad - but that's 0.015% or so...not enough to make up the difference.
Perhaps it's cracking the H2O then proton enriching it to make more Deuterium. Or, perhaps, it's merely focusing upon deuterium in the matrix, and the rest isn't happening with the fusion methods used.

In the case of gas giant atmosphere mix, the density is probably about 1.3 to 1.5 tonnes per Td. So, you're dumping the extra mass overboard.