Temple-Inland uses a single multi-fueled boiler to supply 650 psig steam to a board mill. Fuels are predominantly bark and sawdust with two gas burners for times when bark or dust is wet or curtailed. Load swings are significant with an average load of 100 Kpph, and average swings in flow of 50 Kpph every 12 minutes. Swings have been noted up to 70 Kpph as frequent as six minutes apart for an hour or more. Normal load changes are 50 Kpph over 12 minutes. A steam accumulator is used to help moderate steam swings to multiple digesters.

Emerson Process Management's preconfigured Boiler Control Package for the DeltaV digital automation system was adapted for use with this boiler system. Additions include: a more advanced steam header pressure control strategy with fuel allocation and feedforward, simultaneous multiple fuel firing, and furnace pressure control with three transmitters for redundancy.

The boiler strategy was designed by Emerson and the balance of control system was engineered and installed by Scallon Controls of Beaumont, TX. Most notable was that the boiler was converted from older AC2 single loop controllers to the DeltaV system without a shutdown (yes, it was converted with the boiler running). Controls also include soot blowing, all motors and conveyors, feedwater, deaerator, and makeup water. Next fall, the burner management system will be converted from an older PLC to the DeltaV system.

Startup was completed early May 1998, and has been running well. Notable improvements were: boiler trips for low drum level due to load swings have been almost eliminated, header pressure variation has been reduced from 50 to typically less than 15 psi, manual intervention has been noticeably reduced, and furnace pressure is controlling much better. Bark fuel burning efficiency has improved as measured by the much-reduced quantity of char in the ash pit.

The system includes two DeltaV controllers and two workstations and redundant DeltaV controllers.