Product Overview and System Function

The gas turbine (GT) exhaust bypass system serves as a critical switching assembly for combined-cycle power plants (CCGT) and gas turbine simple-cycle facilities. Installed between the gas turbine exhaust duct and the inlet of the heat recovery steam generator (HRSG), it delivers the following core capabilities:

• Enhance combined-cycle operational flexibility: enable gas turbine simple-cycle operation, part-load operation and fast peak shaving response.

• Mitigate thermal shock: alleviate start-up thermal stress imposed on the boiler and turbine by diverting and regulating the flue gas flow entering the HRSG.

• Safeguard operational integrity: rapidly isolate the heat source upon boiler or steam turbine malfunction to implement load shedding or load reduction.

• Preserve residual heat during shutdown: closing the regulating damper at unit shutdown maintains boiler temperature, enabling expedited restart for subsequent operation.

Main Product Composition

• Bypass Stack: a steel chimney with lining structure that directly discharges high-temperature flue gas to the atmosphere.

• Flue Gas Damper: the core modulating assembly for flow switching between the HRSG passage and bypass passage, available in louver type and single-piece type.

• Metal Expansion Joint: accommodates thermal expansion and contraction within high-temperature flue ducts to safeguard downstream equipment.

• Silencer/Start-up Vent Stack: attenuates exhaust noise and complies with environmental emission standards.

Core Technology Characteristics

Bachmann's bypass system derives its competitive edge from 30 years of field-proven high-temperature actuation and sealing technology. Its key performance attributes are outlined below:

• High-temperature transmission technology: utilizing custom-formulated high-temperature alloys and outcomes from intensive joint R&D, it delivers transmission torque at merely 20% of that required by conventional designs;

• Long-life design: the baffle achieves a service life of ≥15,000 cycles, with the sealing plate maintaining full functional integrity throughout the lifecycle.

• Rapid start-up capability: supports gas turbine fast start-up within 22 minutes (30 minutes for H-class units), catering to grid peak shaving and emergency response demands.

• Thermal stress-free baffle design: structural optimisation eliminates thermal stress concentration to prevent high-temperature distortion and jamming.

• Modular construction: compatible with containerised shipment or disassembly into maximum-shippable modules, minimising field installation work.

• Sealing plate anti-flutter technology: retains compliance with NFPA sealing requirements even upon fan failure.

• HPU precision control and synchronous lifting technology: delivers precise flow regulation and soft landing, alongside shock and vibration suppression to extend the service life of the sealing plate.

• Built‑in blind flange and blade sealing structure: enables synchronous lifting with robust anti‑jamming and anti‑tilting performance, and is available in two configurations: fully enclosed intelligent premium version or cost‑effective standard version.