| Popis: |
Electricity demand is growing globally due to increasing population and growing economy, it is projected that the global energy demand will increase by 2.3% a year. One of the most reliable ways to generate electricity is by using gas turbines. Although gas turbines are efficient in terms of generating electricity, their power output significantly varies throughout the year due to temperature variance, especially in the summer time where the temperature can reach up to 50 C°. This is because gas turbines power output is proportional to the mass flow of air/fuel through the engine. Since the volumetric flow of air through the engine is essentially constant, mass flow therefore changes with temperature of the air entering the compressor of the gas turbine. When the ambient temperature is high, the power output and efficiency are reduced. Thus, by cooling the gas turbine inlet air, the turbine power output is significantly increased and its efficiency improves. Cooling the combustion air even by few degrees can improve the power output substantially. This is because cool air is denser and therefore gives the turbine a higher mass flow-rate and pressure ratio, resulting in increased turbine output and efficiency as much as 0.5% per degree Fahrenheit or about 1% per degree Celsius. Another advantages in cogeneration is the higher exhaust mass flows resulting in more steam generation. Turbine inlet cooling can be installed in most of the turbines of Saudi Aramco in order to increase their nominal capacity and improve their NOx emission. This paper will analyze the mechanism behind the turbine inlet cooling and will presents the results of a techno economical study conducted for retrofitting a TIAC system on the existing GE Frame VII gas turbines of Abu Safah and Qatif plant facilities. |
