Welcome! Log In Create A New Profile Recent Messages


What atmospheric pressure can do

Posted by IronChief 
What atmospheric pressure can do
September 06, 2018 02:29PM
Here is a video I seen a few weeks ago, it shows the vacuum created when steam condenses.

A bit elementary, but entertaining.


Re: What atmospheric pressure can do
September 06, 2018 05:54PM
Fun with science!

I once sketched up a vacuum boiler refiller. When running, a couple valves open and exhaust steam from engine flushes air out of a small vacuum tank, probably a couple feet of 4" schedule 40 steel pipe. When you shut it down, the valves close and steam condenses to make a vacuum. If boiler cools enough for automatic blowoff to empty it [for freezeproof standby], then the next time you start up, a different valve opens to connect the boiler to the vacuum tank at the refill water level. Vacuum pulls water from water tank through feedwater pipes and pump and into boiler. When water level in boiler reaches the refill level, some water flows to a float chamber, and then the float automatically resets everything to the "run" setting. The vacuum would refill the boiler pretty quickly.

The trick would be getting absolutely tight valves in this refiller. The tiniest vacuum leak would make this setup stop working if the system sat for a few days. But with tight valves, it would be a pretty simple system. No electricity needed; all mechanical.

Vacuum will do a lot of work. Imagine the force & energy needed to crush a big oil drum, as in the video. Big hydraulic jack and lots of hard work pumping. Or a couple small burners and a little bit of water. Early steam engines ran entirely on the vacuum created by condensing steam from atmospheric pressure.

Re: What atmospheric pressure can do
September 10, 2018 07:09AM
I saw sometime back similar video on youtube of railroad tank car imploding with vacuum. They were getting ready to cut it up for scrap and wanted to see if it could be collapsed with vacuum. It did. Technically a perfect tank would hold, but nothing is perfect. Run a steam engine on 15 psi steam, or atmospheric steam and condense it, same power. But the temperature change needed to condense takes time to implement which slows the cycle time and reduces efficiency, being the temp of the cylinder never gets up enough to prevent loosing some to condensation before the right time. But it worked and got steam power started when technology could not yet produce a pressure vessel.
Re: What atmospheric pressure can do
September 10, 2018 08:13AM
This is the entire concept behind a subatmospheric condenser. Far too many people think the ejectors (air pumps) generate the vacuum, but this is not so. They establish a vacuum on light off, and remove air plus other noncondensable gasses released from the steam, but they do not maintain the vacuum. THAT is accomplished by the collapse in volume of steam condensing.
Sorry, only registered users may post in this forum.

Click here to login