Secondary Flow Control Research Articles

99/00600 The integration of low NO x control technologies at the Southern Energy, Inc. Birchwood Power Facility

The Southern Energy, Inc. (SEI) Birchwood Power Facility, a cogeneration unit, represents the first application worldwide of the TFS 2000{trademark} firing system and selective catalytic reduction (SCR). The installation of these state-of-the-art NOx control technologies was necessary to meet strict Commonwealth of Virginia environmental regulations requiring a 0.10 lbs/10{sup 6} Btu (0.043 g/MJ) NOx emission rate based upon a 30-day rolling average. The plant successfully completed all performance and emission testing on September 24, 1996. Commercial operation began November 14, 1996. Stack NOx emission rates are consistently maintained below 0.10 lbs/10{sup 6} Btu. The paper describes the integration of both in-furnace and post-combustion NOx control technologies into the overall boiler design. Operational data depicting boiler outlet NOx, stack NOx and loss on ignition (LOI) are presented across the design load range from 32% to 100% boiler output. The description, arrangement, design parameters and operation of the NOx control equipment are discussed. Novel design features include a split economizer, an air heater suitable for ammonia applications, Dynamic{trademark} classifiers, and a multi-zone secondary air flow control system utilized for the TFS 2000{trademark} firing system.

Three level time decomposition quasi-static active and reactive power flow control

A three-level time-decomposition quasi-static power-flow control model of power systems is presented. The model enables the simple solution and computation of the primary, secondary and tertiary quasi-static power flow control effects. The active and reactive power flow control characteristics are considered. The model exploits the Newton-Raphson method for the computation of all three control subproblems. Computational efficiency is ensured by the specific application of the inversion matrix lemma and the decoupled model constant coefficient matrices. The developed model is intended for security and emergency analysis/control computations.

Secondary Flow Control and Loss Reduction in a Turbine Cascade Using Endwall Fences

An attempt to control secondary flow was made in order to improve turbine aerodynamic performance. Boundary layer fences were attached to endwalls of a linear turbine rotor cascade. Measurements of total pressure losses and three-dimensional flow velocities were taken for 5 different heights and 7 different pitchwise locations of the fences. It was found that the fences were most effective when they were 1/3 of the inlet boundary layer thickness high and located half a pitch away from the blades. These optimum fences reduced streamwise vorticities, the thickness of the endwall loss region, secondary kinetic energy, and the maximum underturning by half. Moreover they diminished the secondary loss by 22 percent, and the gross loss, including kinetic energy dissipation, by 25 percent. A critical fence height above which the fences trap the pressure side legs of horseshoe vortices was found, and the optimum fences proved to be fences of the minimum critical height.