FeedForward has successfully completed startup on 1 pulverized coal boiler and 2 chaingrate stoker fed boilers at Williams Bio-Energy in Illinois. The pulverized boiler produces 300,000 lb/hour of steam for in-house power and process steam. A Foxboro I/A System was installed with fault tolerant CP30's, an AW51(B) and 2 WP51(B)'s, and associated FBM's for analog and digital controls.
FeedForward was responsible for the following scope of work:
- Developing a new control strategy to improve response of the Boiler
- Configuring the controls and graphics to meet Operations needs
- Providing start-up support and boiler tuning services
The improved control strategy used a calculated Coal Btu Flow to the furnace. The basis for the coal flow measurement is the sum of the coal feeder speeds. The summed speed is multiplied by a correction factor based on the total boiler heat release. The steam inventory in the boiler is taken into account by acting on changes in the drum pressure. If the drum pressure is constant, the derivative (lead) function on the drum pressure signal adds a value of zero to the compensated steam flow. If the Coal Btu Flow to the furnace and the total boiler heat release values match, the difference is zero and the input to the multiplier does not change. If the total boiler heat release is greater or less than the Coal Btu Flow reference, then the multiplier is changed by an integrator until the two signals balance thereby providing the proper coal feeder speed signal.