How Does A Gas Turbine Work?

How does a gas turbine work? This a question that is asked quite often. Gas turbines are a well-proven technology and their cycle is described by the ideal Brayton cycle. How does OPRA’s Radial OP16 Gas Turbine work?

Air is sucked in by the compressor at point 1 which then compresses the air to a higher pressure. No heat is added, but due to the compression of the air temperature at the discharge side of the compressor is increased. After leaving the compressor, the air enters the combustion chamber of the gas turbine.

Fuel is injected into the combustion chamber (steps 2-3; Heat addition) and the heat released during the combustion increases the temperature of the combustion mixture. The high-pressure, high-temperature gas is expanded through the turbine (steps 3-4; Expansion) before it is exhausted to the atmosphere. The expansion in the turbine provides the work. Part of this work is used to drive the compressor (directly coupled) and the remaining portion of the produced energy is the useful power.

The gas turbine shaft is coupled to a generator to transfer the mechanical power to electrical power or directly to other equipment for direct-drive applications (e.g. pump, compressor). Besides the mechanical power, the gas turbine exhaust contains a high amount of high-quality heat that can be used in downstream processes, either for direct drying applications or for generating steam. The steam can be used in the downstream process or in a steam turbine to generate additional electricity. The latter is referred to as a combined cycle plant.

The OP16 all radial gas turbine

The OPRA OP16 is a single-shaft all-radial gas turbine for industrial, commercial, marine, and oil & gas applications. Since its market introduction in 2005 over 140 generator sets based on the OP16 gas turbine have been delivered worldwide. The OP16 gas turbine features a single-stage centrifugal compressor with a pressure ratio of 6.7:1.

The moderate pressure ratio reduces the need for gas compression before introducing the fuel into the gas turbine. The radial turbine wheel, which is mounted back-to-back with the compressor, has been aerodynamically optimized to achieve high efficiency.

The compact compressor/turbine configuration permits the use of an overhung rotor assembly where the bearings are located on the cold side only. The all-radial configuration makes it a robust design and insensitive to foreign object damage and fuel contaminants. Also, the lack of intricate cooling geometries in the hot-flow path allows the OP16 gas turbine to handle fuels contaminated with solid particles.