Industrial Power Augmentation Technologies for Aero-Derivatives GT Used as Natural Gas Compressor Drives

Abstract

Abstract Gas Turbines are widely used for Mechanical Drive applications, especially compressor drive for LNG Plants. Aero-derivative turbines are increasingly used for this application as they offer many advantages in terms of superior efficiency and fast start up and reaction to changing demand. However, aero-derivative turbine are highly ambient dependent. When the weather gets hot, gas turbines lose up to 20-40 percent of power output and consequently the production of the LNG plant decreases. Efficiency also decreases when the ambient temperature is higher. The high ambient dependency of aero-derivative turbines has been the main drawback of this technology in very hot climates. Turbine inlet air cooling (TIAC) has been proven to be the solution for this challenge, especially in Middle East. The technical background behind this phenomenon is that aero-derivative turbines have a fixed volumetric inlet air flow. When the ambient air temperature increases the density of the air decreases and therefore the inlet mass flow decreases accordingly. As the power output of the gas turbine is proportional to the inlet air mass flow, for higher temperatures the output will be lower. With TIAC technologies, the inlet air is cooled to avoid the problem of high temperature and low density. TIAC has been implemented in the power sector as a cost efficient power augmentation solution for more than 25 years but it is not common for gas turbines used in Oil & Gas fields because of two main reasons: ▪For the las years, Oil & Gas market was not so much concerned about cost▪Standard chillers are not able to comply with the high requirements of the Oil & Gas Industry However, the falls in oil price are forcing the industry to find solutions for capital cost reduction, which together with the state-of-the-art TIAC technologies characterized for using API standard industrial compressors, is recently turning TIAC a cost effective needed technology in the Oil & Gas sector. Initial examples include the last greenfield developments made by Saudi Aramco and Gazprom in which TIAC technologies has been considered and successfully implemented to reduce the overall capital cost. After several years of successful operation and data collection, the results of the TIAC system implemented in three LM6000-PC located in the North of Mexico will be presented. The power output and heat rates were measured with and without cooling, and the CAPEX and OPEX was evaluated and compared with the installation of a new gas turbine. Based on those results, it is found that capital and operation cost is significantly reduced with TIAC for aero-derivative turbines at Oil & Gas fields.