Executive Summary : | India has a total installed base of about 40000 MW of Gas turbines in its power plants and about 50000 MW in Fertilizer, petrochemicals & pipeline compression applications. This translates to roughly about 1.5 X 108 metric tons of Natural gas consumption per year. Any effort towards reducing this natural gas consumption is welcome and the Government provides good incentives for efficiency improvement projects. The revenue loss to the exchequer on account of efficiency losses due to ineffective cleaning of compressor blades could be anywhere between INR 300 Crores to INR 1000 Crores per year. This calculation assumes a total installed capacity of Gas turbines in India up to 120000 MW for Power and other applications. Fouling of the gas turbine compressor blades can lead to efficiency and power loss as high as 5% (ex: 5MW for 100MW machine). The current online water-wash systems to remove the blade fouling are not effective which eventually requires machine shutdown and offline/manual washing. A typical graph of the effect of fouling on turbine efficiency and improvement with online washing, offline washing and without any cleaning indicates significant loss of power and increased water consumption, especially for the off-shore conditions. Currently, a trial and error approach is used to decide spray nozzle locations, water quantity and temperature. Droplets, if in excess quantity and high velocity, impact the blades leading to erosion, in turn leading to loss of performance. To avoid erosion and permanent damage to blades and cost replacement a conservative spray system is designed. This causes a deficit of droplets or low velocity hence insufficient cleaning of the deposits thereby leading to aerodynamic losses/efficiency penalty. The focus of the current project is to design and develop an Advanced Water Spray Washing system for effective cleaning of compressor blades thereby improving Gas Turbine efficiency, Turbine Life and water consumption. A strategic approach will be adopted for the investigation that would begin with laboratory-scale Design of Experiments (DOE) based on spray impact tests to identify the optimum injection parameters to ensure maximum removal of foulants and minimum material erosion. The knowledge gained from the DOEs can assist the development of a prototype multi-injector spray wash system. This is an important intermediate stage that bridges the gap between lab-scale experiments and full-scale design of the system. In parallel, based on the initial and boundary conditions in the DOE, Computational Fluid Dynamic (CFD) simulation of the spray impact process will be carried out. The purpose of the simulation is to facilitate a parametric study of the system and assist the final product development and also new designs for scaled systems in the future. Finally, a full-scale online multi-injector water washing system will be developed. |
