Natural gas generators and heat economy

[Crapgame]

I found this interesting note on the wiki regarding using a steam room to vaporize the PW exhaust from NG gens.

I like it because it is "neat" and not because it may be the most min/max way to do this.

I'm looking for some advice on how to get this setup started.  All my attempts have ended in frustration.  I can't seem to get the room hot enough in a vacuum to vaporize the water once it is introduced.

In my case, I stuck 2 stacked NG gens and a smart battery (all steel) in the smallest possible room in a vacuum. At the bottom is a tiny catchment for the exhaust with water over the PW to prevent offgassing into the vacuum. (Don't worry about locks, I use the airlock mod.)

I start by letting everything get superhot (~250C) and then send in a drip (valve limited) of superhot water from a geyser at about 90C.  This works as intended and flashes to steam as soon as it enters the room.  But that is where I hit the wall.  Even though it is flashing to steam immediately, it also cools down the machines immediately and that turns my steam to water and temps never stay high enough to keep the steam in the room.

Any suggestions I should consider to get this room steamed up? 

P.S. Moving steam in pipes never seems to work for me. I get constant state changes even in insulated pipes.

[YOLO KNIGHT]

How hot is your natural gas? Looking at the wiki it seems they're working with 150C input temps

[Crapgame]

1 hour ago, YOLO KNIGHT said:

How hot is your natural gas? Looking at the wiki it seems they're working with 150C input temps

Thanks for the question. 

It comes out at 150 but it immediately cools down to about 90C even while still in my geyser room.  I send it to gens in insulated pipes so it gets there around that same temp. 

[blakemw]

Because the Natural Gas Generator only outputs a small amount of water, you need VERY good insulation to avoid all the heat leaking away. Ideally you want actually perfect insulation.

It's quite simple to achieve actually perfect insulation by using double walling, for an insulated tile made of igneous rock at 20 C, a temperature delta of about 250 C is required to get any heat exchange at all with solid tiles, but the temperature delta is only 10 C for gas tiles (this is because gas:solid has 25x heat exchange multiplier), the exact reason why there will be actually zero heat transfer is outside the scope of this post but it's basically because of how the calculations work, resulting in 0 temperature change.

As it is 400 kg, an Insulated Tile can absorb A LOT of heat, especially made of a material with moderately high SHC like Igneous Rock. The cleanest solution to this is double walling where the inner layer has very low mass and SHC, for example Lead Metal Tile has only 3.2% the thermal mass as an Igneous Insulated Tile.

So in short, make the steam chamber with an inner layer of lead (or gold) metal tiles which will quickly heat up to the steam temperature, and an outer layer of Igneous Insulated Tiles. Then inject enough heat to actually heat up the inner layer of tiles and anything else. Once it has all been heated up there should be no drop in temperature except that absorbed by the incoming natural gas.

[Crapgame]

That sounds interesting. Except how would I put a ST on this? Only insulated at the top? 

I'm willing to sandbox almost any suggestion. I've tried all kinds of layouts with the same result.

The biggest pain is the PW output. Even when room is full of scorching machinery it will turn to steam but then almost immediately change to water and cool everything down and now it's all broken again. 

I've always been so focused on cooling things down that I have no imaginative ways to heat things up. (Except for ATs of course but I draw the line at sticking an AT in there just to heat things up.) 

[blakemw]

23 minutes ago, Crapgame said:

That sounds interesting. Except how would I put a ST on this? Only insulated at the top? 

For the Steam Turbine you should use the best insulation material for the floor tiles (e.g. Ceramic), and run the Steam Turbine as hot as possible (e.g. try to run it at about 98 C) to minimize the temperature delta. You can also have fewer slots open (double walling the others), each steam turbine slot can consume 400 g/s of water, so even with only a single open slot it can consume the water output of 5.9 Natural Gas Generators. This should keep the heat leakage below that which would be injected by batteries/transformers.

The system MUST be thoroughly pre-heated or it won't work. An Aquatuner is the easiest honest way to do this preheating.

 

edit: I can add, that if you are really opposed to Aquatuner, you can use a Bottle Emptier and a Pitcher Pump over magma to drip some magma in, it'll instantly freeze into igneous rock debris and inject lots of heat.

[Crapgame]

This sounds promising. I knew the port blocking mechanic but honestly have never used it. All my STs have been on geysers where I want all the ports working. 

I like the magma idea. I'm guessing I would calculate how much steam per tile I want and then add that much water. Then drip the magma on the water to have it blow up?  Then start the machines when it's already full of steam? 

[JRup]

21 minutes ago, blakemw said:

should use best insulation material for the floor tiles

The best would indeed be ceramic before you get to space and then use "insulation" (the abyssalite composite) as the material. There is another alternative and that is to 'aerogel' the deal.  I'll preemptively say that making said 'aerogel' does take advantage of game mechanics and it is a lot of work, but the end result is rather satisfying, link in the spoiler tag:

Spoiler

 

As for pre-heating, the glass forge is a rather nifty alternative. Using the 1kg/s mechanic for liquid pipes is the way to go if you choose this...

All taken into account, you should actually be going for a natural gas geyser tamer. Keeping the build around the geyser will help you conserve heat because heat losses in pipes will be avoided.

41 minutes ago, Crapgame said:

Then start the machines when it's already full of steam? 

I could recommend aiming for at least 135ºC when pre-heating your steam environment.

[Crapgame]

Or kilns (now that mention glass forges). I don't have easy access to 1. 2kW where I'm building so I was trying to find creative ways to heat it up. 

[JRup]

Kilns are not a good idea to heat up a steam box. There are ways to use them, but they're all very convoluted. This is because the material that gets dropped from them is at a fixed temperature and will generally sap away heat from the surrounding gas.

[Crapgame]

Isn't it all convoluted though? 

[JRup]

6 minutes ago, Crapgame said:

Isn't it all convoluted though? 

The sky's the limit in this game, quite literally.

[Crapgame]

What do you suppose this means in the last sentence of that section:

"Instead, key the turbines to activate based on room pressure, and only reintroduce liquid when needed (above 135 °C for a self-cooled turbine, or above 200 °C for actively cooled setups)."

I pretty sure I understand the concept.  95C water is going to cool my setup down. (That has been my struggle!)  But we use atmo sensors for pressure and thermosensors for temp so this sentence kind of throws me off.  I suppose the writer meant to say "based on room temp" because that would make the statement make more sense.

Also, @blakemw's suggestion to keep the ST running hot seems to contradict this.

[JRup]

1 hour ago, Crapgame said:

keep the ST running hot

This is usually said for self cooled STs. A minor goal for self cooled steam turbines is to only cool them with their own output and run them as hot as possible. The wiki has its own information for that kind of setup but the tl;dr: on that is that the steam temperature you feed it with shouldn't exceed 135ºC when using all vents. (Yes, it can go a bit higher if some are blocked, how much is an exercise for readers...)

"When to activate the steam turbine?" is your question here.

I let it run when steam pressure has accumulated enough in my setup, usually around 6,5kg/tile and stop at 4kg/tile. (An "alternative" to the memory toggle is in the spoiler, the AND gate is wired correctly.)

Spoiler

Bear in mind that I have not said anything about re-adding the resulting water to the steam box, more about that next.

"When to cool the steam?"

That you do when the only when steam box you've built gets too hot. Where the water comes for that is what you should figure out, the STs output is ideal at 95ºC (Higher for self cooled, but I'll push for something better...).

"What to do with the resulting water from the ST?"

You can keep it in a reservoir for cooling the steam box (a liquid meter valve would work wonders when needed) and divert any excess elsewhere. ("We can do better...")

"What do you mean by 'better'?"

Adding hotter liquid is better because you "lose less heat", using a carbon skimmer for the hot CO2 from the nat-gas generators (+hot ST output) will provide very hot polluted water that does not break the pipes as easily as water. I use a self cooled setup and the resulting polluted water hovers around 100ºC. This will cool down the setup in a more gradual fashion that won't destabilize the build as dramatically as cooler water would.

Minimally off topic:

"How many natural gas generators can run off a geyser's output?"

Natural gas geysers average (somewhat) above 90g/s, which is enough to run a single generator 100% plus another a fraction of the time, this includes dormancy periods. Building your own tamer for this is a neat project I wholeheartedly agree with and that not many accomplish.

"How much water will a natural gas tamer produce if skimming the CO2 with the STs output?"

It depends. If your geyser can run at least 1 generator all the time then you might be looking at 70 g/s. Ballpark figures is the name of my game. Trivia tidbit: when boiling polluted water you'll get dirt unless you boil it a rate lower (or equal to) 100 g/s.

"Do you have a build?"

Yes I do, but I don't want to spoil your fun (yet). I've occasionally pasted my build in discord, though, but might also want to release the build in a thread of its own and explain all the bits and pieces to avoid confusion.

Just hoping this wall of text helps...

[Crapgame]

10 minutes ago, JRup said:

Just hoping this wall of text helps...

It does. Many thanks! I sandboxed a bunch of designs tonight and didn't like any of them.

It is amazing that we can "play" a game for hours and yet not actually played the game.

I'm going to try again with your suggestions and see if I can make this work. I have 2 NG geysers and I'm determined to tame the pair of them no matter how impractical it may be. Together they are outputting 600g/s so I'm planning on 6 NG gens with a ST on top. 

[blakemw]

3 hours ago, JRup said:

This is usually said for self cooled STs. A minor goal for self cooled steam turbines is to only cool them with their own output and run them as hot as possible.

While running hot is mandatory for self-cooled Steam Turbines, there's actually nothing stopping you running an Aquatuned Steam Turbine hot unless you specifically need to have shirt-sleeve temperatures for dupes or some other strange reason, and it offers mild effeciency improvements.

For example if the Steam Temperature is 200 C, and an Igneous Rock Insulated Tile floor is used, then the leakage could be expected to be about 3 kDTU/s per tile, this drops to substantially less at about 1.25 kDTU/s if Ceramic is used instead of Igneous Rock (always use Ceramic), the heat leakage can be reduced by about 40% by running hot instead of cold, saving about 6 kDTU/s in the case of Igneous Insulated Tile, or a savings of about 2.5 kDTU/s in the case of Ceramic. (you can also further improve savings by minimizing the conductiveness of the Steam Turbine by using Lead)

The savings are quite small and mainly only of significance to self-cooled setups running very close to the limits, you aren't really going to notice whether or not an Aquatuner moving 585 kdTU/s is moving an extra 2 kDTU/s.

But though the benefit is small, in many cases it's literally free, you just set the Liquid Pipe Thermo Sensor to a higher number so the Steam Turbine ends up operating at like 97 C or something. In the other cases the cooling loop is "Dual Use", you also want to use it to cool other things to some desired temperature. Now if you are a serious ONI nerd you can actually use a Liquid (Meter) Valve to greatly limit the flow rate behind the Steam Turbine, but again, this is for savings measured in mere kDTU/s so it's understandable to prefer to pay a couple of extra watts in cooling than making the build more complicated. (Though it's also understandable to pursue every efficiency improvement no matter how trivial).

 

Getting back to the primary topic of this thread.

The Temperature of the "Steam Chamber" is a nuanced topic.

First, the system because it's being fed 150 C natural gas, will tend towards an equilibrium temperature of 150 C. This is the most natural temperature for the steam to be at and the natural gas will naturally cause it to trend towards this temperature if not forced. 150 C is too hot for self-cooled Steam Turbines. If all the leakage is strictly limited it should be very easy to achieve an equilibrium temperature of 150 C ish.

Secondly, the entire point of putting power generators in a "Sauna" is abusing the fact that Power Generators tend to have output temperature = building temperature. Because of this, the "purpose" is best achieved by running the Generators as hot as possible, at like 240 C if Steel, or even hotter if using Thermium, and closing some Steam Turbine inlets to still achieve full power conversion. However operating at this temperature requires heat injection to compensate for the heat absorbed by the Natural Gas, unless you do some rather hardcore trickery to prevent the natural gas exchanging heat with the steam (this means "vacuum dripper" builds - makes it way more complicated). But injecting additional heat is certainly doable and you'll get a substantial heat profit out of it by doing so. (sustainable heat injection is of course, best done with an Aquatuner)

Thirdly, it would be reasonable though a bit contradictory to want to eliminate the Aquatuner and use self-cooled Steam Turbines, this is the only case where exhaust water should be re-introduced, and only as required to bring temperatures below 135 C (basically compensating for heat injected by the natural gas). In this case limiting the temperature greatly reduces the amount of "free heat" produced by the Generators but also eliminates an Aquatuner from the build. I would daresay that it is more in the spirit of the build to not eliminate the Aquatuner, but you aren't obligated to cool the Steam Turbine from within the build, it's very routine for me to like run cold liquid from a geyser behind a Steam Turbine, the amount needed is trifling.

 

[JRup]

23 hours ago, Crapgame said:

Together they are outputting 600g/s

Could you post the geyser's data sheets? I would go out on a limb here and say average output is far more useful for your build if you plan to have it continuously work through dormancy. For example...

[Crapgame]

10 hours ago, JRup said:

I would go out on a limb here and say average output is far more useful for your build if you plan to have it continuously work through dormancy.

And I'd agree with you. My original plan was just to build enough gens to just burn all the NG and not worry much about storing any for dormancy since I have other power sources. 

After planning everything out, I've decided against that and I'm just building for the average output which is about 250g/s so I'm building 3 gens. 

[Crapgame]

Ok, I've gone full AT/ST combo over a 3 NG hot box.  I have cold water a plenty so I'm going to be actively cooling the ST down.

I'm not 100% clear on exactly when I want to reintroduce water to the box.  For the pressure I'm going to try @JRup's automation above but what does that mean for opening the water drip?  Just set the automation so that both the ST and the faucet turn on at the same time?  Can that possibly be too much water?

Edit: I mean I'm aware the it is the same mass being extracted as injected but wondering if the water will just be too cold.  There's also the 202.5g/s of PW coming from the NG gens.

[JRup]

3 hours ago, Crapgame said:

Ok, I've gone full AT/ST combo over a 3 NG hot box.  I have cold water a plenty so I'm going to be actively cooling the ST down.

I'm not 100% clear on exactly when I want to reintroduce water to the box.

Re-adding liquid to the steam to cool it down should be done when target temperatures are reached. It all depends on the build so that would usually be around 200ºC for AT/ST combos, for example.

Not much I can say there since we can't see what you're doing (screenshots are always nice...).

[Crapgame]

(Sorry, I usually post from work so can't post screens)

Here we have my janky build. (Hold your s******ing till later.)  You can imagine that there are 2 other NG gens above and below the one you see.  I'm currently heating up that water that I brought in from a cool steam vent.  The cool water crossing across the ST is coming from a cool slush geyser so it is nice and chill.  I'm using the AT now but my intention is to remove it altogether once the thing is running since the heat should be stabilized and ST cooling is covered.  Alternatively, if a AT has to remain a part of this build forever I can build down into the PW catchment and make a home for the AT there.

Regretfully, I'm failing to understand the dynamics at play between the pressure and the temperature.  (If there is a link to somewhere to read up on it I swear I will, I don't want to make you explain it like I'm 5.)

If I control JUST for temp at 200C to turn on ST and inject more water then pressure will slowly build since that doesn't account for the 202.5g/s of PW.  Is that why I must turn on the ST for BOTH temp and pressure?  So anything above 200C OR 4000g of pressure should run the ST? This is where my eyes glaze over.

[JRup]

There are some issues that will need looking into first...

Let's start with insulated tile at the bottom, it will be necessary for there to be steam without cooking your base. Then there's the over pressure limits for the vents, it may come and haunt you.

I have a separate reservoir for the steam turbine's output, I just skim the CO2 from the generators and add the resulting polluted water as coolant for the steam box. You could choose to add liquid (water, for example) to the steam box if it gets too hot, a shutoff connected to a reservoir could help.

The steam turbine I activate when the pressure high enough for me to consider it good for extracting. If the pressure drops too low then I risk getting polluted oxygen because I add polluted water for cooling.

The aquatuner you may want to keep to maintain cool operating temperatures for the steam turbine and any other equipment on that loop, but the AT must be controlled by automation. If not, then you risk either overheating the lump of metal that it is or you risk freezing whatever is in the pipes. Any combination of that is possible.

BTW: No need to keep the liquid vent submerged... This is just a sample build:

If you intend to cool the steam turbine only with its own exhaust, then you shouldn't have steam hotter than 135ºC, if using an aquatuner to cool it then you could go as high as 200ºC.

As for pressure and temperature dynamics there is nothing too complicated: pressure has no bearing on material temperature other than taking more or less time to change the temperature for the total amount of material there is. It does make me wonder how refrigerators work in the ONI universe (compressing/decompressing gas does nothing) but then again thermoelectric plates are a thing in real life.

I hope this helps somewhat.

[Crapgame]

2 hours ago, JRup said:

I hope this helps somewhat.

Very!  I should note that your preliminary concerns are all well taken and I've accounted for them.  I have plenty of space around this build to double wall and that is why you see that weird double tile at the bottom.  I will replace that with insulated tiles later I was just low on ceramic and wanted to frame it out.  The submerged liquid vent you see down there is actually left over from filling that tank from off screen.  A new one will be built higher up along that ladder. (I did warn you it was janky)

I also now understand what you were explaining with the CO2 skimmer.  That sounds brilliant.

So I was correct in thinking that I need to turn the ST on if over 200C or ~4500g/tile.  They are independent variables but either one means that I need to get some steam out of there.

[JRup]

8 hours ago, Crapgame said:

They are independent variables but either one means that I need to get some steam out of there.

I suggest you treat them independently.

The automation I showed activates the steam turbine if pressure goes over 6500 g/tile and stops at 4500 g/tile. Regardless of steam temperature. If you want temperature stability then you can set these pressure values higher; sadly enough, atmo sensors only go up to 20 kg.

In your case "coolant" (water/polluted water) can be added to the steam box if the temperature nears the 200ºC mark.

 

[Crapgame]

Of course!  My thinking was stuck on "ST turns on means that water is introduced" and that is WRONG!  ST water is being collected independently.

That means:

• when the pressure gets in range the ST turns on.
• when the temp gets over 200C the water gets introduced.

Only took me a week to figure this out.  Thanks for the detailed responses!