Table of Contents
How many stages does a gas turbine have?
The turbine is normally based on the reaction principle with the hot gases expanding through up to eight stages using one- or two-spooled turbines.
What is a turbine stage?
This combination of rows of guide (nozzle) vanes and moving blades (arranged in series) is a turbine stage. Turbine blades and inlet and outlet units form the flow passage. Turbines are classified as axial and radial (radial-axial) depending on the direction of the flow relative to the rotor rotation axis (Figure 1).
What is gas turbine cycle?
Most gas turbines operate on an open cycle in which air is taken from the atmosphere, compressed in a centrifugal or axial-flow compressor, and then fed into a combustion chamber. Here, fuel is added and burned at an essentially constant pressure with a portion of the air.
What is stage in gas turbine engine?
The turbine converts gaseous energy into mechanical energy by expanding the hot, high-pressure gases to a lower temperature and pressure. Each stage of the turbine consists of a row of stationary vanes followed by a row of rotating blades. This is the reverse of the order in the compressor.
Why are there more compressor stages than turbine stages?
Very simply, a turbine has fewer stages than the compressor, because the flow in the turbine is going in the direction of reducing pressure – the air wants to go that way naturally. But a compressor has to make the air flow in the direction of increasing pressure.
Some units produced by various OEM’s (Original Equipment Manufacturer) have three (such as GE) stages of turbine, and for a similar output some have four (such as Siemens). Occasionally one might see five stages (as in the case of Alstom). This may be of some cost concern when considering hot gas path replacement or performance-related issues.
What is the power capacity of a pressure-staged turbine?
Pressure-staged turbines can range in power capacity from a few to more than 1.3 million kilowatts. Some manufacturers prefer to build units with impulse stages simply to reduce thrust-bearing loads. Such units may have as many as 20 sequential stages.
What affects the owner/operator of a gas turbine?
A good example, that affects the owner/ operator directly, is the number of stages in the gas turbine hot section, even though they have similar ratings of MW capacity. Some units produced by various OEM’s (Original Equipment Manufacturer) have three (such as GE) stages of turbine, and for a similar output some have four (such as Siemens).
What is turbine staging?
Turbine staging. Only a small fraction of the overall pressure drop available in a turbine can be extracted in a single stage consisting of a set of stationary nozzles or vanes and moving blades or buckets.