Saturday, March 29, 2008

All in a Day's Work: Backpass Inspection


The dreaded outage has begun. Unit 2 came off line last night about midnight and things cooled down enough for us to get in and do a backpass inspection this afternoon. I have a few more pictures for you too look at. The backpass in Unit 2 is the same as in Unit 1, so there really isn't a lot new here.

This is a roomy and comfortable hole know as the 'economizer'. After the steam has gone over the turbine and condensed back to water, that water is pumped back into the boiler to be used again, as it is very pure. But is is also very cold compared to the boiler and would cause problems if it were pumped directly back into it. So it goes through a series of feedwater heaters (more on these later) that use waste and low quality steam to preheat the water. The last heater is actually in the coolest part of the gas path and the water picks up quite a bit of heat that would otherwise be wasted. Walking around in the Economizer is tricky, and the pipe is covered with slippery ash, kind of the consistency of flour. So you can appreciate the care that is taken by each of us as we walk around on these tubes.


Here is a little hole to let us go from the top parts, to the lower parts. Beneath this is a pipe called a sootblower lance. Periodically the soot blower shoots steam out of the end of this pipe as it rotates it slowly, and pushes it into the space. The steam knocks ash of the tubes and that lets them transfer heat more efficiently.


One thing that we didn't do last time, on the short outage, was to wash the boiler cavity and remove all the clinkers and ash so that work can begin down below without worry of a boulder sized clinker falling 18 floors and smashing you flat. We have tried several different methods to remove these clinkers, and this time we are washing them out with a water cannon. This is a fancy nozzle that you can hook two 2-1/2" fire hoses to.

Well, that is about it. More adventures tomorrow. We are both tired at the start. It might be a really long month.

Wednesday, March 26, 2008

Food Fight!!




Someone has way too much time on their hands. But it is kind of fun anyway.

Stupid Things I Could Have Done

You all know me well enough to realize that I could have easily been the person who thought this "sounded like a good idea at the time".....


..(Names have been removed to protect the stupid!)
Actual Letter from someone who writes, and farms
__________________________________
I had this idea that I was going to rope a deer, put it in a stall,
feed it up on corn for a couple of weeks, then kill it and eat it.
The first step in this adventure was getting a deer. I figured that,
since they congregate at my cattle feeder and do not seem to have
much fear of me!
When we are there (a bold one will sometimes come right up and sniff at
the bags of feed while I am in the back of the truck not 4 feet away),
it should not be difficult to rope one, get up to it and toss a bag over
its head (to calm it down) then hog tie it and transport it home.
I filled the cattle feeder then hid down at the end with my rope.
The cattle, having seen the roping thing before, stayed well back.
They were not having any of it.
After about 20 minutes, my deer showed up -- 3 of them. I
picked out.....a likely looking one, stepped out from the end of the
feeder, and threw.. ..my rope. The deer just stood there and stared at me.
I wrapped the rope around my waist and twisted the end so I would have a
good hold. The deer still just stood and stared at me, but you could
tell it was mildly concerned about the whole rope situation.
I took a step towards it...it took a step away. I put a little tension on!
The rope and then received an education.
The first thing that I learned is that, while a deer may just
stand there looking at you funny while you rope it, they are spurred to
action when you start pulling on that rope.
That deer EXPLODED.
The second thing I learned is that pound for pound, a deer is a LOT
stronger than a cow or a colt. A cow or a colt in that weight range I
could fight down with a rope and with some dignity.
A deer-- no chance.
That thing ran and bucked and twisted and pulled. There was no
controlling it and certainly no getting close to it. As it jerked me off
my feet and started dragging me across the ground, it occurred to me
that having a deer on a rope was not nearly as good an idea as I had
originally imagined.
The only up side is that they do not have as much stamina as many other
animals.
A brief 10 minutes later, it was tired and not nearly as quick to jerk
me off my feet and drag me when I managed to get up. It took me a few
minutes to realize this, since I was mostly blinded by the blood flowing
out of the big gash in my head. At that point, I had lost my taste for
corn-fed venison. I just wanted to get that devil creature off the end
of that rope.
I figured if I just let it go with the rope hanging around its neck, it
would likely die slow and painfully somewhere.
At the time, there was no love at all between me and that deer. At that
moment, I hated the thing, and I would venture a guess that the feeling
was mutual.
Despite the gash in my head and the several large knots where I had
cleverly arrested the deer's momentum by bracing my head against
various large rocks as it dragged me across the ground, I could still
think clearly enough to recognize that there was a small chance that I
shared some tiny amount of responsibility for the situation we were in,
so I didn't want the deer to have to suffer a slow death, so I managed
to get it lined back up in between my truck and the feeder - a little
trap I had set before hand...kind of like a squeeze chute.
I got it to back in there and I started moving up so I could get my rope
back.
Did you know that deer bite? They do! I never in a million years would
have thought that a deer would bite somebody, so I was very
surprised when I reached up there to grab that rope and the deer grabbed
hold of my wrist.
Now, when a deer bites you, it is not like being bit by a horse where
they just bite you and then let go. A deer bites you and shakes its head
--almost like a pit bull. They bite HARD and it hurts.
The proper thing to do when a deer bites you is probably to freeze and
draw back slowly. I tried screaming and shaking instead. My method was
ineffective.
It seems like the deer was biting and shaking for several minutes, but
it was lik ely only several seconds.
I, being smarter than a deer (though you may be questioning that claim
by now) tricked it.
While I kept it busy tearing the tendons out of my right arm, I reached
up with my left hand and pulled that rope loose. That was when I got my
final lesson in deer behavior for the day.
Deer will strike at you with their front feet. They rear right up on
their back feet and strike right about head and shoulder level, and
their hooves are surprisingly sharp.
I learned a long time ago that, when an animal -- like a horse--strikes
at you with their hooves and you can't get away easily, the best thing
to do is try to make a loud noise and make an aggressive move towards
the animal.
This will usually cause them to back down a bit so you can escape.
This was not a horse. This was a deer, so obviously, such trickery would
not work. In the course of a millisecond, I devised a different strategy.
I screamed like a woman and tried to turn and run.
The reason I had always been told NOT to try to turn and run from a
horse that paws at you is that there is a good chance that it will hit
you in the back of the head.
Deer may not be so different from horses after all, besides being twice
as strong and 3 times as evil, because the second I turned to run , it
hit me right in the back of the head and knocked me down.
Now, when a deer paws at you and knocks you down, it does not
immediately leave. I suspect it does not recognize that the danger has
passed. What they do instead is paw your back and jump up and down on
you while you are laying there crying like a little girl and covering
your head.
I finally managed to crawl under the truck and the deer went away.
So now I know why when people go deer hunting they bring a rifle with a
scope to sort of even the odds.

Sunday, March 9, 2008

All in a Day's Work

Spring has sprung, sort of, and thoughts of outages come unbidden to young and old men's minds. Mostly the come because we dread it so much and there is so much to get ready for. This weekend we had a short outage on Unit 1 to fix a few things that we could run with now, but probably would get worse and force and outage later.

Yesterday afternoon we did our back pass inspection. The boiler consists of two sections. The boiler cavity is where the fire is. The mills grind the coal to a flour like fineness and big fans blow it through specially designed burners into the cavity of the boiler.

It is a pretty big structure, and mostly you can't see anything but a huge, blinding ball of fire when it is on line. A lot of heat is created here, and a lot of it is absorbed into the boiler walls which are made of steel tubing and filled with boiler water. The water boils in these tubes and rises to where it is guided into the drum. The drum separates the water from the steam. The water falls back down some large pipes called downcomers and is recycled back into the wall tubes. The steam is cool - for steam, and needs to get more heat energy before it goes to the turbine. So, in the gas path there are hundreds of more tubes that absorb more of the heat from the gas, and as they do, they heat up the steam that travels through them.
Here are a couple of pictures of the back pass. The whole steam/gas path interaction is complex but can be summed up in the coolest steam is warmed by the coolest gas in the path, and as the steam travels up and forward it moves against the gas path and is in contact with increasingly warmer gas.

In a backpass inspection, you crawl through on the tubes and look for broken soot blowers (horizontal pipe in lefthand picture), or places where the soot blower has eroded the tubing and it needs to be shielded or pad welded.

One last picture. These are the platen pendants and they hang over the fireball and pick up a lot of heat. They aren't the last stage in steam warming, but pretty close. Just a little part of what it takes to keep the lights on.