Bypass and Exhaust Gas Systems


Exhaust gas systems are designed with an elbow for connecting to the exhaust stack in simple cycle power plants.  In combined cycle power plants the bypass systems include a diverter damper or a T-box with louver/guillotine dampers.

With a delivery time of only 4 - 6 months, a bypass stack can be installed to allow power generation ahead of the HRSG erection.


The advantages of a bypass system with diverter are:

  • short delivery times
  • high plant flexibility
  • controlled start-up of the HRSG reduces thermal stresses and prolongs lifetime
  • flexibility during HRSG maintenance
  • fast HRSG shut-off in emergency situations
  • reduced mass flow to HRSG in intermediate positions assisting to control the steam production


NPS has supplied a large number of flue gas and bypass systems with stack diameters ranging from 2605 to 9769 mm, stack heights between 20 and 65 meters and design gas temperatures up to 670 °C (1238 °F).


A comprehensive reference list is available upon request. Please feel free to contact us.