Question about steam engines

Superheated steam is a "hotter" steam (sometimes called "dry" steam) which contains more thermal energy than saturated steam. It becomes mechanical energy through expansion, not a "...controlled explosion..." Steam is not a combustible..it cannot "explode." Because the steam is heated far above its condensation temperature, it can do a lot of work before its heat energy is exhausted and it condenses back to water.

You cannot heat water in a steam locomotive anywhere close to 4,500 degrees F. At its hottest, the firebox will approach 2,500 degrees in the fire. The highest super heat steam temperature I have ever seen in a steam locomotive was just under 700 degrees F. And that was on a locomotive working HARD at maximum operating pressure (temperature) with an almost perfect fire and good coal.

Well said Rich,

I just learned about vapor pressure and heating curves in Chemistry this past week. I'm sure you know this already but once you reach the boiling point of the water then the temperature stays the same because there is a phase change occuring (water to steam). The potential energy is being stored up until you reach the specific heat of vaporization which then releases that potential energy of the steam to hike up the temperature again and create even more energy. A heating curve is illustrated like this:

 The point you see that starts off the 2nd plateau is the specific heat of vaporization. Where water now transitions to a complete gas. As the temperature keeps getting higher and steam gets heated longer you get superheated steam and Lima Superpower.  

My daughter was doing quadratic equations in chalk on the driveway a few weekends ago. It was wrong, but still cool :-)  i think she knows how to solve for the maximum now.

Mike

In a boiler, the water is contained in a pressure vessel, so the water temperature does not stay the same--it increases. Maybe you're just referring to boiling water at atmospheric pressure? 

Exactly right, Steve. At 200 psi, the boiling point of water is 388 degrees F. The constant temperature which Mike refers to applies to water boiling at atmospheric pressure with no pressure build-up as the steam is released.

Re-read what I said above abut the release of pressure and all the water flashing to steam with that release of pressure.

Rich,
I found this and if I read it right the temp for 300 PSI like in the N&W J is 417 degrees F ?
http://www.boilerroomservices....acts/SteamTables.pdf

No wonder the metal can go soft with those kinds of Temps.

David

Yep...300 PSI water boils at 417 degrees F.

Steel has no problems at all at 400+ degrees. It is when the water goes away and the steel goes to 1,500 degrees or more that things start to get ugly.

Not to get political, but I remember when Rosie O'Donnell stated that the World Trade Center must have been an inside demolition job because steel wouldn't melt at the temperature of the jet fuel fire.

I just had to laugh at the ignorance on display for all to see...

Oh yeah I was referring to the atmospheric pressure. Thanks for correcting me. 

Here's a saturated steam table showing the temperatures of various steam pressures. Looks like you need to cut and paste into your browser, or click the link and go to "steam tables" on the index.

www.boilerroomservices.com/Facts/SteamTables.pdf

5th post up from yours.

David

5th post up from yours.

Duh! Sorry man, I read through your post too fast!

Well, now I know why we limped home from Hinton and got back late.  The 1953  Allegheny blow-up was discussed on the train ride.  I had remembered years ago seeing a tourist train operate around Gettysburg, PA?, if that is what we are talking about, and since that is regularly visited during York, I wondered why I had not seen any train activity around there since, although, I'm only there York week.

 Also I was at that old hobby shop formed of two passenger cars at New Oxford, Pa., once, this, too, dating me, when a tourist train pulled by steam went by, passing

right by the station still standing there.  Wonder what that trip that was?

Uh, those passenger cars that served as the shop sat there for years after that shop closed, but I have now noticed that they are gone...moved?  Anybody know the story on that?

I now think that the real question in this thread is why in the heck

 were you watching Rosie O'Donnell??