HRSG diverter damper

Application

 

To fully utilize exhaust gas for more power generation, a HRSG is installed together with gas turbine. When HRSG requires a shutdown, but gas turbine doesn’t, combined cycle is switched into simple cycle, then diverter damper can guide exhaust gas into atmosphere via bypass stack. Diverter damper has one input port and two output ports, which are connected with gas turbine, bypass system and HRSG separately. It makes exhaust gas go to either HRSG horizontally, or bypass stack vertically.

 

Structure

 

• Damper gate. Mechanical seal adopts double layer flexible metal sealing plates, which forms a chamber space with sealing retainer. Damper gate inside is covered with thermal insulation materials. Lining plate uses heat resistant stainless steel.
• Sealing air system. Two booster fans (one as standby) provide air at higher pressure (500Pa) than exhaust gas to avoid leakage. System inlet is equipped with non-return valve to prevent backflow of hot exhaust gas.
• Hydraulic oil system. It consists of hydraulic oil pump, hydraulic cylinder, accumulator, pressure switch, temperature switch, solenoid valve, etc.

 

Function

 

• Diverter damper provides additional flexibility for combined cycle. HRSG is isolated when gas turbine needs to run individually. Especially suitable for operation with small capacity gird which requires fast startup, quick response.
• Better coordination between gas turbine and HRSG. It takes only 10-30 minutes for gas turbine to run at rated load from a coal start. For HRSG and steam turbine, the speed depends on allowed thermal stress of metal. Opening adjustment of diverter damper could make a good match between gas turbine and HRSG.
• When load changes greatly, diverter damper could direct part of exhaust gas into bypass stack to avoid overpressure of HRSG.
• Fast closing function is the most effective method to reduce load of HRSG in emergency handling.

 

Feature

 

1. Diverter damper is driven by mechanical actuator or hydraulic cylinder. It could open/close within 0~90 degree for isolation or flow control.
2. Remote control by DCS or local control by PLC.
3. Air sealing for better isolation, minimum to zero leakage.