Yesterday afternoon, my Thermodynamics class took a field trip to the Charter Street Plant. It's the one on the losing end of a Sierra Club lawsuit. I brought a camera.
Our tour was led by a senior supervisor. He started by explaining the history of the plant. Construction started for two boilers in the mid 50's and over the years other things were added. When petroleum got expensive in the 70's, the plant removed the equipment to burn gas and oil.
The plant sends steam for heating and chilled water for cooling to campus, which is opposite of a regular power plant that would generate electricity and throw away hot water, though he said they can make up to 9 kilowatts of electricity. If I remember correctly, he said that at present they have four boilers that can produce roughly half a million pounds of steam an hour.
The professor asked about the lawsuit and he said that to come into compliance it could cost taxpayers $50 million. He said the issue was that they were doing regular maintenance to keep things in top shape so they wouldn't start breaking down and polluting, but the judge ruled that they had done too much work to stay grandfathered into the pollution laws. He said they might just consider "expanding east" from the present Charter Street location with new stuff instead of reworking old equipment.
Coal comes in on trains and sits in piles until it's conveyed up to the top of the plant. Once there it's dropped into 30ft tall gravity bins at roof level.
Two stories down, the bottom of the bins have measuring devices to measure out certain amounts of coal. Each of the bins feeds into a boiler.
On the main floor of the plant, half a story above street level, is where the burning of the fuel happens. Here are two of the three boilers. Each of them are at least three or four floors tall starting in the basement and they're about 20 x 30 feet in cross section. They have several motors that throw the coal across the burn plate in the boiler. The boilers heat the water until it's steam at 600 psi and +700 °F.
They opened some hatches and we could look into the fire. Needless to say, it was intense. It looked like a snowstorm, but with fire instead. I think I heard that it was between 2k and 3k degrees in there.
Behind the boilers, there is a large fan that pumps air into the bottom of the boilers.
The control room is located on the main floor between the boilers and the air pump. It still had the original controls. They've been integrated with modern computers. There was a back wall full of more controls and circular pen graphs.
Most of the heat from the fire goes into heating the water. But the air that comes out is still hot and has soot in it. Up in the top of the plant is the filtration system, the "fabric filter baghouse". The exhaust blows through nearly 200 2-story tall closed wind sock type things. They catch most of the pollutants, and work better as they age. They're up in the top of the plant, behind so many doors.
Here's more upper plant air equipment. Overall, the plant had quite an unearthly feel to it. Though it was dark and some parts closed in, it wasn't at all like a cave. There was a thermometer set out in one of the colder areas; it read 100°. There were multitudes of pipes, machinery, and who knows what all over the place, all of it on a bigger scale than a person, all of it going in all directions, a few floors down, or soaring higher into the hot darkness. Who knows what half of it does. Loud and noisy, all out of control, yet completely under control. I felt like an interloper who had walked in on an industrial symphony.
So then, the last part of the tour was down to the waterworks in the basement, under the cooling tower. Water is cooled by dropping it through quickly rising air. The guide said they can cool it down to 40°, but it's in the 50's most of the time. They had huge pumps that can pump water in all sorts of ways from the campus, to the boilers, etc.
They also have emergency systems should something go wrong. If all else fails they even have a connection to the city water. Down in the bottom recesses of the basement, groundwater was seeping in. The supervisor said that there were springs all over that area and that's how Spring St. got its name.
A view of campus from the coal belt at roof level.