Gas Turbine performance

Let us agree 1st on the below

Performance is how effectively a machine or system can achieve its goal, while

efficiency is how much resources are used to achieve that goal

Efficiency requires reducing the number of unnecessary resources used to produce a given output

In A simple way

Performance is the measure of quality of the work done by?any machine.?

efficiency is the ratio of desired output?to the required input for any?machine.

Gas turbines used for converting fuel energy into electric power?(via electric generators). They normally use the Brayton Cycle, which is a thermodynamic cycle that involves compression and expansion of a gaseous medium. An ideal cycle may offer 100% performance, but?a real gas turbine will always have a certain level of losses and friction.

Performance equation in its simplified form:?

Shaft Power =Fuel Energy – Power Required for Compression – Exhaust

Energy - Mechanical Losses?

?it means that profitability is based on the turbine’s output and the cost of fuel.?The operator can only control the turbine’s output.

To understand what we are dealing with let us go through the following 1st

A natural gas fired power plant features three major sections:

1-?????Compressor: draws, pressurizes and directs the air to the combustion chamber. Air is at extremely high speed here.

2-?????Combustion Chamber:?comprises of a fuel injector set that creates a stream of fuel for mixing with air. After being burnt at 2000 degrees F, this mixture forms a high-pressure high-temperature gas stream that is ready to enter the turbine.

3-?????Turbine Section: it is made of a complex combination of rotating and fixed aero-foil-section blades. The rotating blades respond to the expansion of the hot combustion gas. These blades have two essential functions- spin the generator for electricity generation and drive the compressor for more compressed air into the combustion chamber.

gas turbine is composed of several components- turbine, combustor and compressor. When the characteristics of any of these components are altered,?there might be increased heat rate and power output loss. This will increase fuel costs incurred by the power plant.

It is important to realize that ?in?the?gas?turbine?the?processes?of?compression, combustion ?and ?expansion ?do ?not ?occur ?in ?a ?single component as they occurred in a reciprocating engine.

There are several parameters that affect gas turbine performance including compressor compression ratio, combustion inlet temperature and turbine inlet temperature (TIT), compression ratio, ambient temperature, air to fuel ratio, turbine inlet temperature & both compressor and turbine efficiencies

to be continued...,