Closing the gap

Engineers at Siemens have used a simple trick to increase the efficiency of gas turbines in power plants.

The engineers developed a hydraulic system that reduces the ‘radial clearance,’ the gap between a turbine’s rotor blades and its housing. Secondary flows that pass by the rotor blades unused are reduced, which increases the turbine’s efficiency.

The hydraulic optimisation of a gas turbine’s clearance improves its efficiency by about 0.2 percentage points. With a 100-megawatt turbine, that represents annual fuel cost savings of about 60,000 Euros. Siemens says that existing turbines can be retrofitted with the new system at any time. One such system has already been installed at the Mainz-Wiesbaden power plant in Germany.

Gas turbines are used in power plants to generate electricity. The turbines work by means of a compressor that draws air from the environment, compresses it and then channels it into a combustion chamber, where a pressurised mixture of air and fuel, usually natural gas, is burned.