Pumps, boilers, steam egines and the mystery of hot water

[NosajDraw]

So I've read the wiki, and I understand how I can maximise the boilers and steam engines per pump... but I left wondering stuff, there seems to be a mystery here which my Googling reveals no answer to.

What happens to the water?

Let me explain.

So my pump pumps water to the boilers which heat it from 15c to 100c and then the water flows from those into the steam engines which generate power, now from reading the wiki I'm left to understand that the engines (in effect) cool the water down and generate electricity in return.

OK... so... what happens to the water? Does it vanish in this process? Surely it must, because if water came out the other end (lets ignore the fact that in all my test water does come out the other end) then why can't I reheat it and have more steam boilers use it? The wiki says, and Ive seen other places say also, that 1 pump is maxed out (more or less) at 14 boilers and 10 engines. But really? Is it? That would mean the game has some idea of water/fluid pressure, but nothing mentions this and I've seen no problems so far with using waste water... so... yeah... who says? How do we know that the pump gets maxed out?

Also... if I was to design a system that pushed the waste water back to the input of the boilers, would I get more efficiency? Or is extracting "waste" water nothing more than extracting potential energy from the engines?

My guess is that engines work a little like this:
1) they take water in at whatever temperature they get and they reduce its temperature by x amount over y time outputting z amount of electricity in return
2) If there is something connected to the outlet of the suitably reduced in heat water is outlet
3) whilst if there is no where for the water to outlet, vanishing/voiding any water that reaches 15c

if that's correct, then there should (it seems to me) to be optimal designs for the layout of boilers and engines, but everything I've read seem to suggest that you hook em up any which way you want and the return will be the same.

So... yeah... anyone able to provide help/guidance/hard info?

[blizgerg]

It appears to me that it doesn't reduce the temperature of the water, but the quantity. So the amount of water the steam engine voids is proportional to the temperature and the demand. But it is capped at 6 water a second.

[NateDangerous]

If it works like a real life steam engine the water/steam is getting consumed (and presumably released into the atmosphere, though it may not be shown).

How an old timey train engine works:
https://youtu.be/g8LrAsL4oH0

An animation of it:
https://youtu.be/ESfSG2OlQYQ

Though the fact that Factorio steam engines can work with any heated liquid makes me think perhaps they aren't working as real life ones do.

[DaveMcW]

If a steam engine is not connected to something that needs power, it does nothing.

While running, a steam engine makes every liquid put into it vanish at 6 per second. Power is extracted from any liquid heated above 15C.

[NosajDraw]

If a steam engine is not connected to something that needs power, it does nothing.

While running, a steam engine makes every liquid put into it vanish at 6 per second. Power is extracted from any liquid heated above 15C.

So why not just heat water to any value above 15c and push that into the engine? Why waste coal heating it to 100c?

[NosajDraw]

If it works like a real life steam engine the water/steam is getting consumed (and presumably released into the atmosphere, though it may not be shown).

How an old timey train engine works:
https://youtu.be/g8LrAsL4oH0

An animation of it:
https://youtu.be/ESfSG2OlQYQ

Though the fact that Factorio steam engines can work with any heated liquid makes me think perhaps they aren't working as real life ones do.

Whilst there may well be some approximation, since steam is never made and pressure isn't a thing it doesn't work the same way at all.

[MrDoomah]

If a steam engine is not connected to something that needs power, it does nothing.

While running, a steam engine makes every liquid put into it vanish at 6 per second. Power is extracted from any liquid heated above 15C.

So why not just heat water to any value above 15c and push that into the engine? Why waste coal heating it to 100c?

Because water that isn't 100C will yield less power. A steam engine will consume the same, it will just not output its maximum of 510W.

[NosajDraw]

If a steam engine is not connected to something that needs power, it does nothing.

While running, a steam engine makes every liquid put into it vanish at 6 per second. Power is extracted from any liquid heated above 15C.

So why not just heat water to any value above 15c and push that into the engine? Why waste coal heating it to 100c?

Because water that isn't 100C will yield less power. A steam engine will consume the same, it will just not output its maximum of 510W.

OK cool, makes sense, so why is water that leaves an engine nearly always cooler than when it went in?

[NosajDraw]

So are 6 uw/s (units of water per second) used by a engine regardless of it's output? I don't think that can be right.

Maybe it uses a maximum of 6 uw/s and less when there is lower power draw...

Still doesn't explain why water looses heat in the engine though...

Hmmm.

[Shokubai]

[starholme]

The liquid and 'steam' simulation is one area that factorio isn't very intuitive, especially if you know how it works in real life. To put it in the simplest manner: it doesn't simulate real life. Pressure doesn't exist.

A boiler increases the temperature of the water that is in it. A steam engine takes UP TO 6 units/second of water(to try and match electric demand). This water is removed from the pipe. Just 'goes away'.
Water has 1kj of energy per degree in factorio. The base temperature is 15 degrees. 1 unit of water at 100 degrees therefore gives 85kj of energy. 1 steam engine using 6 units/second of 100 degree water = 6*(100-15) = 510kj/second = 510kw (one watt is one joule per second, so one 510kj per second is 510kw).

So lower temperature water limits the maximum performance of the steam engines:
6 units/second @ 50 degrees = 6*(50-15) = 210kw
6 units/second @ 30 degrees = 6*(30-15) = 90kw

In the case that you are not using all the electricity that could be produced, water consumption drops to match.
200kw @ 100 degree water = 200/(100-15) = 2.35 units/second of water
255kw(exactly half the max of 510kw) @ 100 degree water = 255/(100-15) = 3 units/second of water

Another thing to be aware of is efficiency. Boilers are 50% efficient, steam engines are 100% efficient. So to run a steam engine @ 510kw needs 1020kw of boiler. Each boiler is 780kw/50%=390kw in your steam engine.

These numbers are the reasoning behind the commonly used 1:14:10 setup.
1 offshore pump = 60 units/second. 10 steam engines @ 6 units/second each = 60 units. 14 boilers @ 390kw each = 5460kw. 10 steam @ 510kw = 5100kw. Thats 360kw extra.
You could also do 13 boilers: 13 @ 390kw = 5070kw, 30kw short.

[Blurb]

The water disappears, which can easily be proven.
Construct a water tank, and fill it with water of any temperature above 15C.
Disconnect the water tank from its source, and then connect it to a steam engine (with an energy load).
As the steam engine produces power, the water level in the tank will gradually decrease until it eventually depletes.

The experiment can be repeated with any fluid for the same result: the fluid is effectively destroyed in the steam engine.
There is no mystery.

[MrDoomah]

It can even be found in the data files:

Factorio\data\base\prototypes\entity\demo-entities.lua, lines 1355-1365:

Code: Select all

  {
    type = "generator",
    name = "steam-engine",
    icon = "__base__/graphics/icons/steam-engine.png",
    flags = {"placeable-neutral","player-creation"},
    minable = {mining_time = 1, result = "steam-engine"},
    max_health = 300,
    corpse = "big-remnants",
    dying_explosion = "medium-explosion",
    effectivity = 1,
    fluid_usage_per_tick = 0.1,

Steam engines use 0.1 fluid 'units' per tick. Or 6 fluid units per second.