Throngs of harried workers in hard-hats are scurrying about St. Paul's Union Depot trying to put the finishing touches on the much-hyped Titanic exhibit. Today, workers are filling a giant salt-water aquarium which will hold a 20-ton section of the ship's hull recovered from the ocean bottom this summer. When the exhibit opens to the public Friday, visitors will see dozens of relics ranging from the ordinary to the exquisite. Chunks of coal used to fire the ship's engines will be displayed alongside luggage, a steward's jacket, crystal decanters and diamond rings. Titanic Conservator Stephane Pennec (steh-FAHN pon-ECK) explained the story behind some of the relics during a recent tour.