A fuel gas compressor must be used on gas turbines if?

A fuel gas compressor is essential for gas turbines when the gas supply pressure is less than the compressor's last stage pressure. This is important because the compressor's function is to increase the pressure of the incoming fuel gas to ensure that it can effectively mix with the air and be injected into the combustion chamber with adequate pressure for efficient combustion. If the supply pressure is insufficient, the compressor will not be able to deliver the necessary gas pressure to maintain the desired operational performance of the turbine.

When the supply pressure is lower than what the system requires, the compressor can take the low-pressure gas and boost it to the required level, allowing for optimal combustion conditions and overall turbine efficiency. This ensures that the turbine can operate at its designed performance levels, providing reliable power generation.

Other factors such as the complexity of the gas system, pressure drops across combustors, and the number of gas nozzles affecting pressure can influence system design but do not directly necessitate the use of a fuel gas compressor in the same manner as the relationship between supply pressure and compressor output.