Feb 23, 2009

ravenswood

I went on a great tour this morning of the Ravenswood Power Plant.  It used to be part of New York's ConEdison before generation was deregulated and the plant was sold off to Keyspan and then TransCanada.  It's located in Long Island City just east of Roosevelt Island and is one of the primary sources of electrical generation for Manhattan with a nameplate capacity of about 2 gigawatts.  

It has 4 primary gas fired generators and a number of smaller secondary gas fired generators. The 4 big boys are monstrous.  The largest being the 1 gigawatt "Big Allis" or Generator 30 (named after the manufacturer Allis Chalmers).  It has two sisters, Generators 10 & 20.  All 3 are single cycle gas fired generators.  Natural gas is burned, it heats up an air/water mixture, the pressurized steam drives the rotation of a magnet, and this creates electricity.  

Generator 40 is smaller and newer but is a much more efficient design; a CCGT or combined cycle gas turbine.  CCGTs are more efficient because they process the residual heat coming out of the initial turbine to drive a second one. Almost all generators being built today are CCGT. They also have a few 'airplane jet' generators that are used to generate a small amount of electricity for high demand days but they can be fired up very very quickly. 

Here's an aerial of the plant.   That's the East River on the left.  You can see two barges which bring in fuel oil or (resid or bunker C) and presumably other supplies.  Depending on the price of natural gas and fuel oil, the plant can chose to burn the cheaper one.  You can see the 4 white-red smoke stacks; one for each generator.  The smoke stacks for 10/20/30 are on the bottom complex.  You can see 40's smoke stack in a separate building at the top of the picture.

Here's a view from the river.  Smoke stacks from left to right are 40, 30, 20, 10. You can see a massive conveyor belt complex in front. That used to transport coal from river barges when it was first built. The plant upgraded to burning relatively clean natural gas in the 60s. The coal apparatus remains.

And here's the inside.  This is generator 20 and behind it generator 10.  It's hard to gauge scale but this is one massive building.  You can see a brown door on the white box to the right but it's tough to gauge how far back it goes.  And it goes an equal distance behind this where Big Allis is housed.  The primary gas firing takes place to the left in huge vertical chambers.  The heated water vapor is brought back down from the top of the chamber, under the floor you see here and into the turbines you see below. 

If you look at the left side of the white generator you'll see a silver module which is a pump to push the steam into the high pressure turbine (the first white section) which drives the generator (the second white section behind). The exhaust is then fed into a second lower pressure turbine-generator to the right of the first one and that drives more electricity. The steam at this point is so hot (and thus dry) that if you get a leak you cannot see it. You can hear it but not see it. My guide said they use brooms to wave around to locate leaks which will burn the broom.
 

Here's Big Allis.  Like the others it has a dual high pressure and low pressure turbine-generator. The generator shaft on the right right recently cracked.  They had to pull apart the entire axle and send it out to be repaired.  It is supposed to be back up in April/May.  When they first deployed this generator in the 60s (I believe) it was the largest in the US.  As they were deploying the generator on the left, it dropped about 1 foot and trashed the entire system.  One of the guys there said it felt like a massive earthquake.  They ended up ordering a second one. Not a cheap piece of equipment.
 

Here's the China Syndrome-like control room for 10 & 20.  The main control is done with computers that you see in front.  A lot of it is still manual though.  While it looks complicated, a lot of the stuff in here is really measuring things like pressures, temperatures, vibrations, expansion of the equipment as it gets hot, etc.  It is used to make sure everything is running well.  When Big Allis developed a hairline fracture it was a vibration detector that let the engineers know something was up.  The newer 40 control room is not like this.  It's a set of computer screens.  If you look at the center screen you can see the ISO (the coordinator for generation in the region) is asking for 104 MW of production while the plant is operating at 108 MW.  So the control room chief was manually clicking a 'minus' button on the screen to take it down a notch.
 

And the final shot is the firing chamber.  In case it is not clear this is looking up towards the top of the chamber.  This thing is enormous and remarkably low tech in its design.  I was very lucky to see this.  It's rare the chamber is open according to the guide.  This 'walled' chamber is actually a bunch of small pipes (running up-down) that you can see if you look closely.  That is sheathed in about a foot of insulating material.  Outside one of the chambers that was running you could not detect the heat because inside the chamber operates at a slightly negative pressure so it pulls in oxygen (and any heat) from the air around it.  

You can also see two vertical black strips.  These are the natural gas nozzles that fire and are pointed in such a way that it creates a cyclone in the chamber.  Water passes through the hundreds of pipes and is converted into steam which is fed to the turbine-generator.  This is the same chamber that fired with coal many years ago.  That coal was first crushed into a fine powder and aerated into the chamber and ignited.  What a mess that must have been.  You can see at the bottom of the picture the tubes slope inward from vertical.  This was to make sure the coal ash collected in the center at the bottom.  In relative terms these are now quite clean burning generators with no 'scrubbing' necessary to meet current emissions limits.
Amazingly about 200 people run the plant. We saw few people except those in the control rooms as we walked around. The guys working there were very knowledgeable and great fun. Thankfully they kept the Wall Street ribbing jokes to a minimum :).

3 comments:

Anonymous said...

Hey there Chooky - Can you tell me how I too can get a tour of Ravenswood - contact number, etc.? Thanks a lot for the post, Toby.

toby@linetechindustries.com

C. Fuzzbang said...

Unfortunately I can't. It was set up for me via a sell-side firm that we pay for services. You could try calling TransCanada which owns the plant.

Anonymous said...

C.B. : Great article on Ravenswood. I'm actually an out of state contractor working at the plant now, but found your stories intriguing prior to my arrival at the plant.