CFD Modeling - Stoker Boiler

Cogentrix Richmond Station

In 2003 CFD modeling was employed by Steag Energy Services (formerly ESA) for Cogentrix Richmond station to redesign Over Fired Air in a spreader stoker fired boiler. An existing system of multiple small nozzles on several levels was redesigned to improve performance. The redesign utilized a set of compound OFA ports, developed by Steag Energy Services (formerly ESA) and GTI. The compound OFA ports composed of three different sized nozzles to provide good cross-sectional distribution of air as well as good penetration of air.

The redesigned OFA ports improved the NOx control of the stoker boiler, while requiring fewer boiler penetrations than other designs. Based on the performance at Richmond, the compound nozzles were retrofit to 22 additional units operated by Cogentrix.

BoiseCascade DeRidder Mill

In 2006 CFD modeling was performed by Steag Energy Services (formerly ESA) for BoiseCascade’s DeRidder Boiler. The DeRidder power boiler was a bark burning stoker boiler producing 300,000 lb/hr of process steam for the DeRidder papermill. CFD modeling was performed to design an improved combustion air system to increase the ability of the boiler to operate at full capacity.  Steag Energy Services (formerly ESA) designed a MultiNozzle Overfired Air (MNOFA) system, flue gas recycle (FGR) delivery under the bark grate, and changes to the bark delivery system to improve combustion in the boiler, limiting flyash carryover.

Xcel Bayfront

In 2007 Steag Energy Services (formerly ESA) employed CFD modeling of the Xcel Energy Bayfront boilers 1 and 2 for the design of combustion air and urea SNCR systems to significantly reduce NOx emissions (50+ %). The Bayfront boilers are coal and wood burning stoker boilers producing up to 200,000 lb/hr of steam. The combined NOx control system incorporated undergrate FGR to limit NOx formation during primary combustion on the grate, a MultiNozzle OFA system to stage the combustion air to limit NOx formation, modifications to the wood spreaders to improve fuel distribution, and a urea SNCR system to clean up NOx post-combustion.

In addition to CFD modeling, Steag Energy Services (formerly ESA) conducted engineering and procurement of all system components, supervised installation, started-up and tested the system.