Performance Evaluation of a Gas Turbine Power Plant by the application of Compressor Off-Line and On-Line Water Washing Techniques. (A Case Study of 450MW Sapele Power Station in Delta State, Nigeria)

The aim of this research is to appraise the performance of a gas turbine engine through the use of compressor online and off-line water washing optimization maintenance technique. Data were collected from the power generation station, Sapele, Delta State over a period of twenty four months (two yrs) from two gas turbine engines "GT1 & GT2", of the same capacity, and at the same location, commissioned the same time. GT1 uses both compressor online and off-line water washing optimization technique, while GT2 uses only off- line water washing optimization technique. The data collected were analyzed. It shows that before the offline water washing exercise, GT2 were operating at 8.47 bar, as depicted in trend for GT2. The compressor outlet pressure is an indication of fouling, as this menace causes a reduction of the pressure. The application of online water washing to GT1 increases the pressure to 9.99 bar. The trend shows that the use of online water washing improved the firing temperature of GT1 by 6.96%. The trend shows that the use of online water washing improved the Network output of GT1 by 6.42%. The network output momentarily decreases due to redeposition of foulants in the later stages of the compressor indicating inappropriate application of washing procedure. GT1 yielded compressor efficiency of 81.6% as a result of online water washing against the 78.5% of GT2. It also implies that the air pumping capacity of the GT1 compressor has increased. It is observed that a small change of the compressor efficiency have a significant effect on the overall GT performance and efficiency. GT1 has compressor efficiency of 81.6% which resulted to overall GT efficiency of 28.3% against 27.7% of GT2. GT1 fuel consumption was less by 2.14kg/kwh as a result of online water washing against the 18.55kg/kwh of GT2.