Gas Turbine Exhaust Systems from Clyde Bergemann Senior

Clyde Bergemann Bachmann (CBBA) received a US$5.4 million contract from POSCO Engineering & Construction Co. Ltd. for design, manufacturing and supply of three sets of Gas Turbine Exhaust (GTEx) bypass systems and complete auxiliaries for the Chilca Uno repowering project in Peru. The contract also includes US$225k service contract for training and technical advisory for erection, start-up, test and inspection, and performance test for acceptance of the combined cycle plant.

The existing power plant is a simple cycle facility that has no provision for waste heat recovery. To address the issues of increasingly stringent environmental regulations, plant efficiency and increasing power demand, Energia del Sur SA has committed to repower the existing three Siemens gas turbine generators with combined cycle technology.

The repowering project will consist of the addition of three Heat Recovery Steam Generators (HRSG) and one steam turbine. Conversion to a combined cycle system will increase the installed capacity of the power plant in an amount of up to 800 MW. The existing gas turbine exhaust stacks shown in the picture will be replaced with CBBA GTEx bypass diverter systems.

The bypass systems, installed upstream of the new HRSGs will permit simplecycle operation and continued electricity generation in the event of a steam turbine/generator failure. The CBBA GTEx bypass exhausts systems comprise the horizontal components (transition from the GT exhaust flange, diverter and expansion joint) and the vertical components (transition, silencer, stack tube, structural steel, ladders, and platforms).

The exhaust system components are designed to be shipped to the site in modules the size of which is determined by the local transport restrictions. The entire exhaust system is designed to meet the specified Peruvian wind and seismic conditions.

The Bachmann™ GFD Model 56 diverter design is state-of-the-art and is optimised for performance to today's standards. CBBA engineers, drawing from years of experience at over 100 installations around the world, have studied every component with attention to maximising longevity and optimising shipping sizes, while minimising cost, field assembly, and commissioning time.

The Bachmann™ GFD comes in a full range of sizes including those for the largest and highest temperature turbine exhaust systems in the industry today.

Major features of our diverter product offering include the diverter blade, hydraulically actuated toggle drive and double row of pressure assisted flexible metallic seals. These dynamic components are designed specifically for today's highly cyclic operating regimes. Previous designs do not meet the demands imposed by daily start stop cycles from peaking power stations. The previous generation of diverters had life expectancies of just a few hundred cycles. The Bachmann™ GFD design has been proven to have a life expectancy of more than 15,000 cycles.

A significant contributing factor to our success in pursuit of this important gas turbine power generation project is our considerable gas turbine exhaust experience, specific to repowering of existing simple cycle plants to combined cycle systems. Our international experience in repowering projects includes five units in Canada, one in China, two in Vietnam, four in Argentina, one in Chile, and prior to this award five previous installations in Peru.

A testament to the continuing success of CBBA outsourcing business model is that engineering, flow model studies and Finite Element Analysis (FEA) will be executed in the CBBA Auburn, Maine USA offices. The dynamic components of the diverter (blade, drive, and seals) will be fabricated in Canada, while the internally insulated diverter housing will be fabricated in Mexico of ASTM materials.

The silencer baffles will be produced in Germany with DIN materials. All remaining equipment (e.g. transitions, expansion joints, blanking guillotine, stack and structure) will be supplied from People's Republic of China with ASTM materials.