500,000 to 600,000 rpm!!!!!!

[chuck foster]

just thought some one would like to see this turbine, they boast that the rpm range is 500,000 to 600,000 rpm.................that sounds scary.

http://pinktentacle.com/2007/08/worlds-smallest-gas-turbine-engine/

chuck 

[Bernd]

Chuck,

Several years ago I went on a tour of a local company that generated it's own power to supply electrcity to the plant. They had several mini gas turbines driving generators. They do run quiet and at a very high rpm. The ones we looked at ran at something in the neighborhood of 100,000 to 300,000 rpm. The tour leader told us that when they spin down they actually settle on the bearing. That's about as much I as I remember.

Now here's a  for somebody to play with. How accurate is your work? 

Bernd

[ieezitin]

Now that was an interesting article, what puzzled me was they used air bearings; why would they not used magnetism? No maintenance no moving parts or piping.

Relating to rpm,s, I was pipe welding in a nuclear power plant in San Onofre near San Diego southern California, there they have two reactors powering two Alstrom 160 Megawatt turbines each 145ft long 80 feet high.

The shut down was coming to a close and I was one of the last left for the start up of number 2 turbine, they pumped steam at one third pressure into the unit and had it idling for three days, they do this to warm up all piping systems and the rotors and blades to make sure everything expands and seats its self. Idling at 300lbs steam they started to increase pressure to its operating pressure of around 1500lbs you can hear the roar, moaning and whining of the turbines and the steam running through the piping and feel the steel deck structure which has 3 inch thick webbed I-Beams in some places wobble and creek as speeds are increased and everything gets running, the feeling and sounds are alike to sitting on the outside of a wing of a 747 and taking off. 

It was around 2 am and I was sitting in the smoke corral alone just staring at the ocean when they started to give the machine full pressure, that’s  when I though my world came to an end, this lord almighty whoosh and roar exploded behind me, making me put both of my hands over my ears which already had ear muffs on, that did little to dampen the noise, the vibrations running through my body felt that all my organs were going to pop out of my mouth. A 24 inch pop off valve ejected  ( safety valve ) releasing 1200 lbs steam to atmosphere about 300 feet in the air, then this sound which I will never forget just drowned everything that was going on, the best way to describe it is imagine 200 fully loaded freight trains running at 60 mph applying full breaks all at once. A sound which today I believe gave me hearing damage.

What happened was the turbine lost lube oil to all main journals, the back up pumping system failed too because of an electrical overload, well needless to say the machine was in do-do and probably a couple of managers too. Normally when they shut the turbine down it takes 5 days to stop rotating, this incident broke that record by grinding to a halt in 18 seconds. The unit was down for 9 months they had to break down the main rotor shaft and blades ship them back to England to get reworked and sent back, irony was the Panama canal refused to let the boat through because the contents were from a nuclear power plant which in turn forced the ship to go around south America. Stupid as the turbine is not in contact with the reactor.

Just  thought I would share.     Anthony.

[Bernd]

the feeling and sounds are alike to sitting on the outside of a wing of a 747 and taking off. 

You have sat on the wing of a 747 taking off.       

Sorry Anthony I just couldn't leave this one alone. As George Carlin always said "Let the dare devils ride on the plane, I'm getting inside".

It's a wondere that turbine stayed glued together. Apperently it hadn't reach full RPM yet?

Bernd

[rleete]

Now that was an interesting article, what puzzled me was they used air bearings; why would they not used magnetism? No maintenance no moving parts or piping.

Nice story.  Would have been exciting to see/hear that.

I belive the answer to why not to use magnetics is because of the speed.  Running at those RPM would probably set up significant eddy currents in the rotor.  May cause sparking, or mess with electrical components in the rest of the system.

[ieezitin]

Bernd. It was not up to full speed yet. Not quite sure of the full rpms, all I know is no oil = loud noise = me reverting back to the womb, coupled with Southern California Edison forking out millions in repairs and creating havoc on the electric grid demand, this was back in 2004 when electric was scarce at that time.

Rleete. Interesting!. I know of large freighters being built in Japan where they freeze the bearing housings and introduce magnetism to form the bearing journals. But I am sure those power plants no where near reach the rpm speeds.


Question, if I am getting this right if the bearing was magnetic and the revolution of the rotor was such a high speed would it be gravity that would interfere with the magnetism?

Thanks for the info.

Anthony.

[rleete]

I have no idea, just throwing that out there as a possibility.

[one_rod]

...... they had to break down the main rotor shaft and blades ship them back to England to get reworked and sent back.........

Just  thought I would share.     Anthony.

Great story Anthony.

My brother worked for a while in the machine shop where they make these rotors. Probably the same place that did that rework.

The rotors are turned from a forged billet on a very big lathe. The turner starts a cut at the beginning of his shift, another man takes over while he gets his breaks, and if all goes well he will have finished one pass by the end of his shift. The next shift turner takes over and starts the next cut and so on.
There was actually a chair bolted to the saddle of the lathe for the turner to sit in while he drives the machine.

Another world from "our" scale of engineering.



one_rod.

[ieezitin]

One rod.
Ha HA . Small world about your brother. In the paper mill where I did my apprenticeship we had a lathe that was on the back of a rail car, it came in driven by an diesel engine, we then affixed the bed rails to fixtures in the floor, then with a regular dial indicator we aligned the bed.

This particular lathe was made special for a set of charge rolls for a particular machine in the line. The radius of the roll was around 8ft x 27ft wide it basically was made by cold rolling steel plate 5/8” thick and making a cylinder by welding all the pieces of the jigsaw together, they would weld  caps on the end and then grind down or flattop the welds. It was then they turned it down to a  wall thickness of around 3/8 thick. This procedure alone took around 4 days two shifts.

Then over the skin of the roll we had to cement and adhere Italian granite tiles dug out of the alps in northern Italy. They were specially profiled to fit the cylindrical rolls. This was turned down too. But at a slower pace. That added a wall thickness of 2”. Through the shaft axis there was piping supplying steam to the roll. All in all this job took around three weeks and a set of rolls lasted around five years.

How it works is like this, the rolls are installed one on top of another, A roll B roll, B roll was the bottom unit, it was driven by a motor gearbox direct drive. The line  ( paper making machine )  was around 800ft long 50ft high in some places. Through the entire maze of rolls belt tentioners idler rolls there was strung a stainless belt called the wire, this was the width of the machine less 6 inches either side, It was made like a fine mesh to act like a strainer, a little like the strainer your mother used for castor sugar. From the pulper ( giant food mixer on steroids ) came fine white bleached wood fiber pulp, it was sucked out under pressure and delivered to the layer line positioned just in front of the said A-B rolls, it was spewed and layered on the wire, The rolls that were super heated because of the steam would squeeze and flatten the pulp, flash heating it and immediately turning it from a liquid to a sheet of paper, the rest of the machine was just for conditioning  the paper giving it a glaze while adding grain qualities.

The old-timers in the mill told me that the lathe I talked about was commandeered
By the government back in both wars it was making parts for the war efforts. What it made I have no clue. In fact the whole machine shop was making stuff for the war, papermaking production dropped drastically through this period.

But I am sure now the Chinese  can make paper like this from the back of a rickshaw and sell it for $0.25 a ream.

All the best.                   Anthony.

[cidrontmg]

ehh, on the side of "small" turbines, and high revs, what about the dentists drills? They usually do at least some 300 000 revs/min, commonly around 400 000, and at the higher end they whine at 800 000 rpm. They fit (relatively easily at that) in your mouth (even a small childīs mouth), among at least a dental mirror, a saliva aspirator and the dentistīs finger(s). And they do WORK in there...
Itīs >20 years since I last worked as a dentist, but "Borden turbine drills" were old hat already then, first being introduced around 1957-58 - over 50 years ago...