Washington lumber mills fire back up with Procidia
Hampton Affiliates of Portland, OR, one of the Northwest's largest lumber companies, reopened the mills formerly owned by Pacific Lumber & Shipping Co. in Morton and Randle, WA.
Procidia, an open architecture process controller, was installed by Applied Control Technology (Sisters, OR), on existing biomass boilers firing the drying kilns at both sites. The biomass in this case is recovered waste, or "hog fuel," from sawmill operations.
Applied Control Technology built a PC-based interface with Procidia using i|ware PC for various combustion control functions, including drum level and furnace pressure. At the Morton facility, an existing Moore 353 controller was re-used and incorporated into the Procidia system, saving the cost of additional 1/0 and program development. In addition, Applied supplemented Procidia's standard graphical HMI with custom-built graphics, trending, and alarming displays.
Procidia also monitors and controls the variable demand conditions of the boilers. A pressure regulator downstream of the boiler maintains a minimum header pressure to the kilns, depending on how many kilns are fired at one time. If demand exceeds supply, the steam flow to the kilns is reduced, and the drying time is extended.
The combustion controls include twin feed stokers for the hog fuel with no airflow measurement. The stoker speed is used to measure fuel flow. A variable frequency drive is used on the forced draft fan to control airflow in proportion to the fuel, and the air-fuel ratio is manually adjusted. Hampton is using single element drum level control, and the furnace pressure controls the induced draft fan damper position.
Siemens Moore Process Automation's solutions help increase plant safety and productivity, reduce time-to-market, and improve product quality in industries such as chemical, pharmaceutical, biopharmaceutical, oil and gas, refining, and pulp and paper.
Edited by Jim Lardear
Managing Editor, PlantAutomation.com