How do you optimize the fuel-air ratio for gas turbine combustion efficiency?

2 Fuel-air ratio and emissions

The FAR also affects the emissions of gas turbine combustion, such as carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (UHC). CO and UHC are products of incomplete combustion, which occurs when there is not enough oxygen or time for the fuel to react fully. NOx are formed by the oxidation of nitrogen in the air at high temperatures. CO and UHC emissions tend to increase with lower FAR, while NOx emissions tend to increase with higher FAR. Therefore, there is a trade-off between combustion efficiency and emissions reduction.

3 Fuel-air ratio control methods

To optimize the FAR for gas turbine combustion efficiency and emissions, various control methods can be used. One method is to adjust the fuel flow rate according to the air flow rate and the desired FAR. This can be done manually or automatically by using sensors, valves, and controllers. Another method is to modify the geometry and design of the combustion chamber to enhance the mixing and distribution of fuel and air. This can be done by using swirlers, injectors, diffusers, and liners. A third method is to use secondary air injection or water injection to lower the peak temperature and reduce NOx formation. This can be done by injecting air or water into the combustion chamber or the turbine inlet.

4 Fuel-air ratio measurement techniques

To monitor and evaluate the FAR for gas turbine combustion, various measurement techniques can be used. One technique is to use gas analyzers to measure the concentration of oxygen, CO, NOx, and UHC in the exhaust gas. This can be done by sampling the exhaust gas and sending it to a laboratory or using online analyzers. Another technique is to use thermocouples or optical sensors to measure the temperature of the combustion chamber or the exhaust gas. This can be done by inserting the sensors into the combustion chamber or the exhaust duct. A third technique is to use computational fluid dynamics (CFD) to simulate the flow, heat transfer, and chemical reactions in the combustion chamber. This can be done by using numerical models and software.

5 Fuel-air ratio optimization challenges

To optimize the FAR for gas turbine combustion efficiency and emissions, several challenges need to be overcome. One challenge is to account for the variations in the fuel quality, composition, and heating value. This can affect the stoichiometric ratio and the combustion performance. Another challenge is to deal with the transient and dynamic operating conditions, such as changes in load, pressure, temperature, and humidity. This can affect the air flow rate and the combustion stability. A third challenge is to balance the conflicting objectives of maximizing efficiency and minimizing emissions. This can require a compromise or a trade-off between the FAR and other parameters.