July 24, 2000
Volume 52, No. 38
Between the pipes: Emory's steamy side
The pressure inside the boilers and steam pipes is quite strong-about 115 psi-and the steam is a toasty 338 degrees. For comparison, a fire hydrant spurts out water at 70 psi. The boiler feed pump is even more intense, shooting water into the boiler at more than 300 psi. The pressure is so high that if a water droplet does not evaporate in the steam pipes, it will damage the inside of the pipes as if it was a bullet. The pressure would shoot droplets around the pipes at speeds of up to 70 mph.
Cleaning the boilers is a painstaking process. All 1,700 gallons of water must be drained and the pressure bled off. A technician in a wetsuit must then squeeze through a 17-inch manway opening and flush all the interior metal areas with water. The process takes about four hours and is repeated on each boiler once a year.
Oil means power, sometimes:
While the plant is powered by natural gas, six gargantuan blue storage tanks (they are almost 29 feet tall) sit behind the main building filled with oil-138,000 gallons, to be exact (a decent-sized swimming pool, for comparison, holds 30,000 gallons of water). That's enough to power the plant for two-and-a-half weeks. When winter weather becomes severe, Atlanta Gas Light Co. will cut off gas to the University and concentrate its power on individual homes. That happened this past January, and the steam plant had to dip into its oil reserve. This isn't a problem, but when the plant runs on oil, two technicians are required, energy costs rise slightly and the air gets a little dirtier.
One gallon equals eight pounds, roughly:
About 50,000 gallons of water a day is pumped through the system during the summer. In winter, that figure jumps to an average of 60,000-70,000 gallons a day and can even climb at 100,000 gallons. All that adds up to an average of about 400,000 pounds of water a day in the summer.
Water, water everywhere:
The plant reuses its water and also gathers condensation from air conditioners. This serves two purposes. First, it conserves natural resources. Second, recondensed water retains some of its high temperature, meaning it does not have to be reheated as much, which saves energy. The condensate tank, where water is collected both before and after it journey through the steam system, contains water that ranges between 170 and 200 degrees. Because of evaporation, some city water is used (about 25 percent, at a relatively chilly 75 degrees), but a minimum, since it has to be reheated and purified.
Baby, light my fire:
"The firebox is basically a giant carburetor," DiCarlo said. "It mixes the air and fuel together and has the same turbulence as a jet engine." It also packs a serious punch-to the tune of 2,900 horsepower. The firebox superheats the water and turns it to steam. It also boasts a fan that can move 35 million cubic feet of air per hour.
Using natural gas is one way the steam plant burns fuel cleanly. Another is when water goes through the economizer. The economizer not only heats the steam from about 218 to 260 degrees, it also cools the natural gas released into the air through the smokestacks (from 650 degrees to around 350), making for a more environmentally friendly process. In all, the steam plant burns about $6,000 in natural gas a day.
The old timers:
Because they are not as efficient and do not run as cleanly as the new boilers, the two older boilers are restricted to 500 hours of use between May and September.
While the infusion of chemicals to remove oxygen and impurities doesn't poison the water, it's not recommended for drinking. The chemical that balances its pH is found in many laxatives. Besides, even without chemical treatment, pure water is less than pleasant. "Have you ever had pure water? It tastes terrible," DiCarlo said. "Everything that gives it taste is taken out." DiCarlo then bends over and helps himself to water from the fountain on the ground floor of the plant. The city water is icy and, after more than an hour in probably the hottest place on campus, incredibly refreshing.