V94.2 CCGT Power Plant – GT Exhaust Metal Bellow to Fabric Retrofit in Wales

The replacement and upgrade of the existing metallic expansion joint with another metal expansion joint would have required a full NDT, splicing in new section of bellow and extremely delicate welding. Alternatively, a fabric expansion joint retrofit boasted multiple advantages...

Client: Centrica Barry Power Station

Barry Power Station is a 230 MW gas-fired power station eight miles west of the Welsh capital, Cardiff. This CCGT power station has one 160 MW Siemens V94.2 gas turbine feeding exhaust gas at 544°C to a Heat Recovery Steam Generator (HRSG). The generator on the gas turbine was rated at 180 MVA and had a terminal voltage of 15 kV; the steam turbine’s was 11 kV.

Total Output:

230 MW

Date Operational: 1998
Location: Wales, UK
Primary Fuel: Natural Gas

Original: Standard Metallic Bellow

The OEM arrangement was a pre-stressed steel expansion joint, installed at the turbine outlet, to compensate for the thermal expansion between a V94.2 gas turbine and the diffuser.

Regular problems caused by this design:
  • Cracking from the circumferential weld to top of convolution.
  • Scuffing of internal liner plate.
  • Damage to cladding and insulation.

Solution: DEKOMTE Fabric Expansion Joint

The replacement and upgrade of the existing metallic expansion joint with another metal expansion joint would have required a full NDT, splicing in new section of bellow and extremely delicate welding. Alternatively, a fabric expansion joint retrofit boasted multiple advantages, including:

 

  • Individual adjustment and modular build-up of every bellow layer.
  • Outstanding vibration dampening features.
  • Low shipping and mounting expenditure and low net weight.
  • No power transmission to duct connecting elements due to negligible low adjusting forces.
  • Outstanding insulation possibilities through targeted thermodynamic design under consideration of heat transfer mechanisms.

 

Operating Temperature: 600°C
Movement: Axial: +/-60mm
Lateral: 3mm

 

This project was installed within 12 days and involved the following steps:

 

  1. Removal of cladding, lagging, weather shield and existing metallic bellow.
  2. Modification of adjacent duct insulation support pins and welding of new frames externally on the diffuser.
  3. Installation of pinned internal insulation bolsters and gas-tight closing of fabric expansion joint. Finally, torque fixings and installation of adjacent external insulation.
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