BY ROBERT P. MADER
OF CONTRACTOR'S STAFF
CHICAGO — It takes an awful lot of mechanical equipment to duplicate Mother Nature.
Edwards Engineering Co. in Elk Grove Village, Ill., recently began construction of the final phase of a new boiler installation at the Shedd Aquarium here that will ensure that millions of visitors each year will remain comfortable as will the fish, reptiles and other aquarium inhabitants.
The first phase of the current boiler project was started nearly two years ago when the Northwestern Industrial Piping Division of Edwards Engineering replaced two of the three boilers serving the Shedd. The current Phase III Shedd boiler installation consists of replacing the third boiler along with installing new pumps and new piping systems.
The John G. Shedd Aquarium has more than 200 tanks, ranging in size from 3 million gal. down to 10 gal., Facilities Supervisor Joe Stawicki said. The basement has pallet loads of brine with the name Instant Ocean that is mixed in 9,000-gal. batches.
Although the boiler room dates from the building's opening in 1929, the old boilers were only 10 years old, Stawicki said. The Shedd has since engaged a water treatment contractor to protect the new, gas-fired Bryan boilers.
The boilers are maintained at 185°F and are pumped to plate-and-frame heat exchangers that serve various zones dedicated to space heating, the kitchen, domestic hot water and aquarium tank warming.
The system is designed so that two of the boilers are used most of the time with the third on standby, said Project Manager Randy Felgenhauer, who is leading the boiler replacement project along with Foreman Doug Crawford of United Association Pipefitters Local 597.
Because of the corrosive nature of saltwater, the steel pipe from the boilers to the heat exchangers is the only steel pipe in the building, Stawicki noted. Most of the pipe used by the Shedd is fiberglass or PVC Schedule 40 or 80. The pipe ranges in size from 1/4 in. to 30 in. The heat exchangers, fabricated from stainless steel and titanium, measure from 3 sq. ft. to 25 sq. ft. in size.
Water flow is constant, Stawicki said, with temperature sensors instructing Belimo valves to open or close to send hot or chilled water the space conditioning and aquarium tank zones.
There are two Bell & Gossett pumps per each zone. The main boiler loop pumps are 40 HP and move 1,440 GPM. The main heating zones are served by 890-GPM, 50-HP pumps. Life-support zones for the aquarium tanks use 30-HP, 700-GPM pumps. And, 200-GPM pumps move domestic hot water. Most of the building's domestic hot water needs are served by that hot water loop. Stawicki explained, except for the Oceanarium exhibit, which has its own 120-gal. gas-fired, tank-type water heaters.
The aquarium tanks are piped through large sand filters, and the water is further conditioned with ozone to purify it. The sand filters are backwashed with system water, Stawicki explained, into a recovery basin and then into a recovery filter. The recovery filter is a sand filter, but the sand is much coarser and is only meant to trap large particles.
The operation is computer controlled. He said he knows what's going on with every valve and air handler from his office computer, which displays individual systems graphically.
The coordination of the construction activities and the tie-ins of the new systems to the old must be executed with tremendous care and skill to ensure that the activities and critical animal life support systems served by the Shedd boiler plant are not disrupted, said Jim Jacobsen, vice president/ marketing for Edwards Engineering.
Each year, Jacobsen noted, the Shedd hosts more than 270 nighttime events ranging from charitable functions to educational forums to private parties. The Shedd boilers support the kitchen and food service activities. Moreover, the boiler plant operation is critical to the life support of the many fish and animals at the aquarium, he said.
A half dozen years ago, Northwestern Industrial Piping installed sand filters, fractionators, deaeration towers and ozone equipment as part of the Shark Reef exhibit and building rotunda upgrade project.
The reef is comprised of a 90,000-gal. saltwater tank. Northwestern installed five 60-in. diameter vertical sand filters, and field-assembled 42-in.-diameterby-14-ft.-6-in. tall fiberglass fractionators that remove fine particles.