RogueRose
International Hazard
Posts: 1585
Registered: 16-6-2014
Member Is Offline
|
|
What temp is considered super heated steam and what materials will withstand these conditions?
I'm trying to figure out is a 10 bar vessel (180C/357F) would be considered super heated steam, and if steam of that temp would rapidly degrade
iron/steel. I need to find a material that can handle this temp in both a containment vessel (~1-1.5L) as well as tubing that can carry the steam
from the vessel into a turbine system. I'm also looking at something that will allow for the 180C to be further heated as a couple coils (maybe 3-5ft
long) are passed through a hot fire (1500-2000F) to further increase the temp after it leaves the vessel. In this case it would most likely be used
to pass over hot carbon, not run into a turbine - though I'd like to test that was well and see if there is significant increase in power output.
I'm leaning towards 304/316 SS for the vessel (appropriate thickness) with a blow-off valve (brass OK?), and then the same material for the tubing
(probably 3/16" - 3/8" ID) or if possible some thick walled copper if it is strong enough to handle the pressure and IDK if hot steam degrades copper
the same as it does iron/steel.
|
|
|
Twospoons
International Hazard
Posts: 1282
Registered: 26-7-2004
Location: Middle Earth
Member Is Offline
Mood: A trace of hope...
|
|
I would try to use the same material throughout, no matter what you choose, otherwise galvanic corrosion may be a big problem , unless you select
materials carefully.
Espresso machines operate in the vicinity of your stated conditions : https://www.wholelattelove.com/blogs/articles/espresso-machi...
SS is probably your best bet, so long as there's no chlorine/choride in the water.
[Edited on 9-10-2019 by Twospoons]
Helicopter: "helico" -> spiral, "pter" -> with wings
|
|
|
Vomaturge
Hazard to Others
Posts: 285
Registered: 21-1-2018
Member Is Offline
Mood: thermodynamic
|
|
In the case of steam, superheated means the temperature is greater than the boiling point of water at a given pressure. 180C and 10 atm is close to
saturation, so probably not superheated. Also, I don't think e.g. 180C steam at 5 atmospheres would be more corrosive than 300C steam at 90 atm,
simply because the former was "superheated" and the latter was not.
I'd say you could use normal carbon/mild steel pipe, or even copper at 180C, (although soldered joints may start having problems at temperature). For
the 800C superheater, stainless steel and realize its strength will be a half to a quarter of what it is at room temperature
For either setup, assume there will be a few catastrophic failures, due to engineering flaws temperature/pressure excursions, etc. before you get it
running smoothly. Be safe and have fun.
PS why is espresso brewed at high pressure? Is it to enable liquid water at ~200C, or is it just part of forcing the water to flow through the grinds?
The espresso websites talk about final (in the cup) temp, pressure while brewing, but not brewing temperature.
|
|
|
Yttrium2
Perpetual Question Machine
Posts: 1104
Registered: 7-2-2015
Member Is Offline
|
|
I think it's to move the water through the grinds
Good question!
I wonder how pressure cooker coffee would taste, it might be the next best thing!
|
|
|
Ubya
International Hazard
Posts: 1232
Registered: 23-11-2017
Location: Rome-Italy
Member Is Offline
Mood: I'm a maddo scientisto!!!
|
|
maybe you misread, espresso machines have never used steam at 180°C.
coffee grounds would char at that temperature.
maybe you read 200° F as 200°C
---------------------------------------------------------------------
feel free to correct my grammar, or any mistakes i make
---------------------------------------------------------------------
|
|
|
Twospoons
International Hazard
Posts: 1282
Registered: 26-7-2004
Location: Middle Earth
Member Is Offline
Mood: A trace of hope...
|
|
I was referring to the pressure. Coffee is ideally brewed at 95C. But there are also single tank espresso machines that heat the tank to ~120 to 130C
for steaming milk. So not exactly the same conditions, but a similar sort of engineering problem.
Helicopter: "helico" -> spiral, "pter" -> with wings
|
|
|
rockyit98
Hazard to Others
Posts: 283
Registered: 12-4-2019
Location: The Known Universe
Member Is Offline
Mood: no mood is a good mood
|
|
aluminium would do fine up to 350 Celsius it can handle the pressure.
do careful research about stainless steel type. this old tony
https://www.youtube.com/user/featony
"A mind is a terrible thing to lose"-Meisner
|
|
|
Metacelsus
International Hazard
Posts: 2531
Registered: 26-12-2012
Location: Boston, MA
Member Is Offline
Mood: Double, double, toil and trouble
|
|
Wouldn't chemical reactivity with 350 °C steam be an issue? I don't think the surface oxide layer would be stable under those conditions.
[Edited on 2019-10-10 by Metacelsus]
|
|
|
andy1988
Hazard to Others
Posts: 135
Registered: 11-2-2018
Location: NW Americus ([i]in re[/i] Amerigo Vespucci)
Member Is Offline
Mood: No Mood
|
|
You may enjoy this read on boiler corrosion, and perhaps similar material.
A great discussion here on creating a magnetite layer.
Also a good read on magnetite.
[Edited on 10-10-2019 by andy1988]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
