VLB-SE No Run of the Mill Replacement

Two paper machines at the Bruck mill produce a total of about 300,000 tones of mainly coated wood containing paper for offset printing. Gunter Wallner, Department of Energy and Environment Manager at this Norske Skog mill in Austria, explains, “The production of pressurized groundwood pulp and paper requires large amounts of energy. So any amount we can produce with our own turbines reduces our energy costs.”

Consequently, in 1992, the planning and construction of a new combined cycle gas and steam power plant was started. The plant, by virtue of the dedicated design of its gas turbines, fulfils all operational requirements for steam and electricity generation, and is able to supply surplus electricity to the public electrical power network.

“The excellent rangeability and controllability of the VLB-SE bypass valve was a determining factor behind our purchase of the [CCI Sweden] valve,” says Wallner.

Compared with the valves often used in this application, the high rangeability of the VLB-SE bypass valve makes it possible to bypass only as much steam to the process as required in a given situation. This allows passing optimal amounts of steam to the turbine for generation of electricity. Also, conventional valves used in this application handle flows down to only 10 tons per hour. The VLB-SE allows turndowns of about one ton per hour, sending more steam to the turbine for production of electricity than a conventional bypass valve.

The VLB-SE is also extremely accurate where pressure and temperature control are concerned. Papermakers know that the greater control over steam pressure and temperature, the easier it is to control the quality of the paper produced. At the Bruck mill, operation of the VLB-SE over the past three years has shown that the accuracy of pressure and temperature control is normally limited by the response time and exactness of the control system.

“[CCI Sweden] steam conditioning valves have proven a success!” says Gunter Wallner. “Since 1993, all customer services and checks have been carried out trouble-free and on schedule. We are very satisfied with our decision to buy [these] valves.”

Published in SOLUTIONS Spring 2003