SOAPP-CT Technology Modules

Bypass Stack & Diverter Valve

BACKGROUND

A bypass stack and diverter valve installed in the gas turbine exhaust ductwork of a combined cycle power plant allows the gas turbine to continue operation with the heat recovery steam generator (HRSG) "off-line". Originally, dampers were used to control bypass and HRSG flow volume. These dampers were direct derivatives of the louver-and-guillotine damper combination previously designed for conventional power plant equipment. These original designs were created by redesigning the dampers and expansion joints to accommodate bypass usage and increasing temperatures. High temperature transients distorted the louver dampers during turbine startups and plate buckling caused the guillotine blades to suffered binding in these initial designs. Use of internal insulation and damper blade redesign has increased the overall reliability of the system. This module addresses commercially viable bypass stack and diverter valve technologies.

SCOPE

The SOAPP-CT Technology Module on Bypass Stack and Diverter Valve systems includes technical reference information plus interactive conceptual design models for the following system configurations:

• combustion turbine combined cycle
• with a bypass stack and diverter valve
• without a bypass stack and diverter valve

The module includes discussions on basic principles and the major components of bypass stack and diverter valve systems. More detailed information on each technology, including unique processes, components, and supporting systems, is also included in this module.

Technology performance; equipment sizing; capital, O&M, and differential fuel costs; and construction schedules are modeled for each of the system configurations as a function of the following sensitivities:

• combustion turbine model selection
• number of combustion turbines
• cycle type
• fuel selection
• secondary fuel usage factors
• combustion turbine NO_x control method
• combustion turbine NO_x emission limit
• ambient dry bulb temperature
• ambient wet bulb temperature
• site elevation
• unit capacity factor

Economic analyses are based on a static set of standard economic parameters when this module is used as a separate program. When this module is launched from within the SOAPP-CT WorkStation, up to 42 project-specific economic parameters are automatically imported into the module for the user's selected project. Included in these economic inputs are fuel cost, escalation rate, tax rate, capital structure, and contingencies. Default values for all module sensitivity parameters are also set from the values stored in user's selected project when this module is launched from within the SOAPP-CT WorkStation.

Last modified: Friday, July 19, 2002