Lifecycle of a Power Plant Lump of Coal

Fifty Percent of our electricity is derived from coal.  Did you ever wonder what has to take place for that to happen?  I thought I would walk through the lifecycle of a piece of coal  to give you an idea.  I will not start back when the it was still a tree in a prehistoric world where dinosaurs grew long necks to reach the branches.  I will begin when the large scoop shovel digs it out of the ground and loads it onto a coal truck.

The coal is loaded onto trucks like these before it is dumped onto the train cars. This photo was found at http://www.gillettechamber.com/events/eventdetail.aspx?EventID=2827

The coal for the power plant in North Central Oklahoma came from Wyoming.  There were trains from the Black Thunder Mine and the Powder River Basin.

Coal Trains on their way to power plants

It’s a long ride for the lump of coal sitting in the coal train on it’s way to Oklahoma.  Through Nebraska and Kansas.  It’s possible for the coal to be visited by a different kind of traveler.  One that we may call “A tramp.”  Someone that catches a ride on a train without paying for the ticket.

One time a tramp (or a hobo, I don’t remember which), caught a ride on one of our coal trains.  They forgot to wake up in time, and found their self following the lumps of coal on their next phase of the journey.  You see.  Once the coal reached the plant, one car at a time enters a building called the “Rotary Dumper”.

A rotary dumper much like the one that was at our Power Plant

As each train car enters the dumper four clamps come done on the car and it rolls upside down dumping the coal into a bin below.  Imagine being a tramp waking up just in time to find yourself falling into a bin full of coal. with a car full of coal dumping coal on top of you.  One coal car contained 102 tons of coal (today they carry 130 tons).  Today one train contains 13,300 tons of coal.  This is over 26 million pounds of coal per train.

Miraculously, this passenger survived the fall and was able to call for help or someone saw them fall.  He was quickly rescued and brought to safety.  Needless to say, the tramp went from being penniless to being, “comfortable” very quickly.  I don’t know that it made the news at the time.  I think the electric company didn’t want it to become “viral” that they had dumped a hobo into a coal bin by accident.  Well.  They didn’t know what “going viral” meant at the time, but I’m sure they had some other phrase for it then.

Ok.  Time for a Side Story:

Since I’m on the subject of someone catching a clandestine ride on a train, this is as good of a place as any to sneak in the tragic story of Mark Meeks.  Well.  I say it was tragic.  When Mark told the story, he seemed rather proud of his experience.  You see.  Mark was a construction electrician.  He hired on as a plant electrician in order to settle down, but in his heart I felt like he was always a construction electrician.  That is, he didn’t mind moving on from place to place.  Doing a job and then moving on.

Mark explained that when he was working at a construction job in Chicago where he worked for 2 years earning a ton of overtime, he figured that by the time he finished he would have saved up enough to buy a house and settle down.  He was married and living in an apartment in Chicago.  He didn’t spend much time at home as he was working 12 hour days at least 6 days each week.  He figured that was ok, because when he was done, he would be set for life.

Unknown to him at the time, each morning when he woke up before the crack of dawn to go to work, his wife would drive to O’Hara airport and catch a plane to Dallas, Texas where she was having an affair with some guy.  By the time Mark returned from work 14 hours later, she was back home.  Each day, Mark was earning a ton of overtime, and his wife was burning it on airline tickets.

When the two years were over, Mark came home to his apartment to collect his wife and his things and go live in peace in some small town some where.  That was when he learned that his wife had been having the affair and using all his money to do it.  She was leaving him.  Penniless.

Completely broke, Mark drifted around for a while.  Finally one day he saw a train that was loaded down with wooden electric poles.  Mark figured that wherever those poles were going, there was going to be work.  So, he hopped on the train and traveled all the way from Minneapolis Minnesota riding in the cold, wedged between some wooden poles on one of the cars on the train.

The train finally arrived at its destination somewhere at a port in the Gulf of Mexico.  I don’t remember if it was Mississippi or Louisiana.  He watched as they unloaded the poles, waiting to see what jobs were going to be needed for whatever the poles were for.  He watched as they took the large wooden poles and piled them up in the ocean.  They were using them to build up the shoreline.  There were no jobs.

It is when you have been beaten down to the point of breaking when you reach a very important point in your life.  Do you give up, or do you pick yourself up and make something of yourself?  Mark chose the latter.  He was a natural fighter.  He eventually ended up at our plant as contract help, and then was hired as a plant electrician.

End of side story.

Let’s follow the lump of coal after it is poured out of the coal train in the dumper…

The coal is fed onto a conveyor belt.  Let’s call this Conveyor 1, (because that is what we called it in the plant).  This has a choice to feed it onto belt 2 which leads up to the stack out tower, or it can feed the other way to where some day it was planned to add another conveyor with another stackout tower.  This was going to go to a pile of coal for two other units that were never built.

Anyway, when the coal drops down on Conveyor 2, way under ground, it travels up to the ground level, and continues on its way up to the top of the stackout tower where it feeds onto Belt 3.  Belt 3 is a short belt that is on an arm that swings out over the coal pile.  The coal is fed onto the coal pile close to the stack out tower.  I suppose it is called stack out, because the coal is stacked up next to the tower.

A view of the coalyard from the top of the Smoke Stack. The tower with the conveyor running up to the top is the stack out tower. Belt 3 is the arm pointing to the right in this picture

Anyway, there are large dozers (bulldozers) and dirt movers that pickup the coal and spread it out to make room for more coal from more coal trains.  As mentioned above.  One train now carries 26 million pounds of coal.

Dirt Mover full of coal

the  coal that is spread out on the coal pile has to stay packed down otherwise it would spontaneously combust.  That is, it would catch on fire all by itself.  Once coal on a coal pile catches on fire it is impossible to “reasonably” put out.  You can spray all the water on it you want and it won’t go out.  When a file breaks out, you just have to drag the burning coal off of the pile and let it burn out.

In order to keep the coal from performing spontaneous combustion, the dirt movers kept it packed down.  As long as the coal is packed tight, air can’t freely reach the buried coal, and it doesn’t catch fire.  So, dirt movers were constantly driving back and forth on the coal pile to keep the coal well packed.  Even on the picture of the coalyard above from the smoke stack, you can see two pieces of heavy equipment out on the coal pile traveling back and forth packing the coal.

Anyway, the next phase in the life of the lump of coal happens when it finds itself directly under the stack out tower, and it is fed down by a vibratory feeder onto a conveyor.  In our plant, these belts were called, Belts 4, 5, 6 and 7.  Belts 4 and 5 fed onto Belt 8 and belts 6 and 7 fed onto belt 9.

Belts 8 and 9 brought the coal up from under the coal pile to the top of the Crusher tower.  In the picture above you can see that tower to the right of the stack out tower with the long belts coming from the bottom of the tower toward the plant.  The crusher tower takes the large lumps of coal that can be the size of a baseball or a softball and crushes it down to the size of marbles and large gumballs.

Coal conveyor carrying coal to the coal silos from the coalyard.  This is the size of the coal after it has been crushed by the crusher

From the crusher tower the lump of coal which is now no more than a nugget of coal travels from the coal yard up to the plant on belts 10 and 11.

conveyor 10 and 11 are almost 1/2 mile long

Up at the top of this belt in the distance you can see another tower.  This tower is called the Transfer tower.  Why?  Well, because it transfers the coal to another set of belts, Belt 12 and 13.  You can see them going up to the right to that tower in the middle between the two boilers.

The tower between the two boilers is called the Surge Bin tower.  That basically means that there is a big bin there that can hold a good amount of coal to feed to either unit.  At the bottom of the white part of the tower you can see that there is a section on each side.  This is where the tripper galleries are located.  There are two belts in each tripper, and two belts that feed to each tripper belt from the surge bin.  So, just to keep counting, Belts 14 and 15 feed to unit one and belts 16 and 17 feed to unit 2 from the surge bin.  then Belts 18 and 19 are the two tripper belts that dump coal into the 6 silos on unit one, while belts 20 and 21 feed the silos on unit 2.

Once in the Coal silos, the coal is through traveling on belts.  The silos are positioned over things called bowl mills.  The coal is fed from the silo into the bowl mill through something called a Gravimetric feeder, which is able to feed a specific amount of coal into the bowl mill.  This is the point that basically decides how hot the boiler is going to be.

Once the coal leaves the gravimetric feeder and drops down to the bowl mill, it is bound for the boiler.  The gravimetric feeder is tied right to the control room.  When they need to raise load more than just a minimal amount, a control room operator increases the amount of coal being fed from these feeders in order to increase the flow of coal into the boiler…..  I don’t know… maybe it’s more automatic than that now….  The computer probably does it these days.

When the nugget of coal falls into the bowl mill the long journey from the coal mine in Wyoming is almost complete.  Its short life as a nugget is over and it is pulverized into powder.  The powder is finer than flour.  Another name for a bowl mill is “Pulverizer”.  The coal comes from the Powder River Basin in Wyoming and just before it is consumed in Oklahoma it really does become powder.

Big rollers are used to crush the coal into fine particles.  The pulverized coal his blown up pipes by the primary air fans and blown directly into the boiler where they burst into flames.  A bright orange flame.  The color reminds me of orange sherbet Ice cream.

The color of the fireball in the boiler

At this point an incredible thing happens to the coal that so many years ago was a part of a tree or some other plant.  The chemical process that trapped the carbon from the carbon dioxide millions of years earlier is reversed and the carbon is once again combined to the oxygen as it was many millennium ago. A burst of heat is released which had been trapped after a cooling effect below the tree as it sucked the carbon out of the environment way back then.

The heat is transferred to the boiler tubes that line the boiler.  The tubes heat the water and turn it into steam.  The steam shoots into the turbine that turns a generator that produces the electricity that enters every house in the country.  The solar power from eons ago that allowed the tree to grow is being used today to power our world.  What an amazing system.

To take this one step further, the carbon dioxide that is released into the atmosphere today is replenishing the lost carbon dioxide from many years ago.  Back when plants could breathe freely.  Back before the carbon dioxide level was depleted almost to the point of the extinction of plant life on this planet.  Remember, what we look on as a pollutant and a poison, to a plant is a chance to grow.  The Sahara desert used to be a thriving forest.  Maybe it will be again some day.

So, there is the question of global warming.  We humans are so short sighted sometimes.  We want to keep everything the same way we found it when we were born.  We try desperately to keep animals from becoming extinct.   We don’t think about the bazillions (ok, so I exaggerate) of animals that were extinct long before man arrived.  It is natural for extinction to occur.  That is how things evolve.  We are trying to keep a system the same when it has always been changing.

Years from now we may develop ways to harness the energy from the sun or even from the universe in ways that are unimaginable today.  When that time arrives, let’s just hope that we remain good stewards of the world so that we are around to see it.  I believe that the use of fossil fuels, (as odd as that may seem) is a major step in reviving our planet’s natural resources.