Time-Dependent Exergy Analysis of a 120 MW Steam Turbine Unit of Sapele Power Plant
American Journal of Electrical Power and Energy Systems
Volume 2, Issue 6, November 2013, Pages: 129-136
Received: Oct. 9, 2013;
Published: Nov. 10, 2013
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Obodeh, O., Mechanical Engineering Department Ambrose Alli University, Ekpoma, Edo State, Nigeria
Ugwuoke, P. E., Mechanical Engineering Department Petroleum Training Institute, Effurun, Delta State, Nigeria
Time-dependent exergy model was used to assess the exergy losses that occurred in the major components of a 120 MW steam turbine unit of Sapele power station. Data used for the analysis were both base parameters and measured values recorded in the station operational logbook for the period of January 2007 to December 2011. Component’s exergy destruction increments as compared with its base value were highlighted and possible causes of the increment were identified. The boiler section had the highest value. The economiser had a maximumof 4.26 % in 2009 and minimum of 1.25 % in 2007. While the evaporator had a maximium of 5.02 % in 2009 and minimum of 1.50 % in 2008. The superheater had maximum of 4.64 % in 2011 and minimum of 1.48 % in 2007. For the reheater, the maximum was 3.57 % in 2011 while the minimum was 1.71 % in 2007. Tube fouling, defective burners, steam traps and air heater fouling were adduced for the increment. Upgrading components with better designs, optimizing system performance and elimination of conditions that degrade efficiency between maintenance outages were suggested for improving the performance of the boiler section. The analysis showed that for the three turbine stages, HP turbine had the highest increment while the LP turbine had the lowest. The loss in the three turbine stages were attributed to throttling losses at the governor valves and silica deposits at the nozzles and blades. Retrofitting of rotors, diaphragms or complete stator/ rotor modules (inner block) were suggested for improving the situation. The results generally showed that exergy loss increased with increased operation time. It was observed that deterioration and obsolescence may be the major problems and that plant rehabilitation is a feasible solution. It was noted that the suggested modification and refurbishment of Sapele power plant units is an attractive solution to improve the plant economy and keep production cost competitive in a restructured Nigerian power system.
Ugwuoke, P. E.,
Time-Dependent Exergy Analysis of a 120 MW Steam Turbine Unit of Sapele Power Plant, American Journal of Electrical Power and Energy Systems.
Vol. 2, No. 6,
2013, pp. 129-136.
A. S. Sambo, Achieving the Millennium Development Goals (MDGs): The Implication for Energy Infrastructure in Nigeria, Proceedings of COREN 16th Engineering Assembly, 28-29 August (2007), Abuja, Nigeria, 121-141.
G. I. Efenedo, I. O. Akalagboro, The Challenges of Power Generation, Utilization and Supply, The Nigeria Vision for the 21st Century, J. Emerging Trends in Engg and Applied Sci., 3 (2012) 886-891.
O. Obodeh, F. O. Isaac, Performance Indicators for Sapele Thermal Power Station, Nigeria: 1997-2006, Advancd Materials Res. 367(2012) 667-675.
Presidential Action Committee on Power, Roadmap for Power Sector Reform: A customer-Driven Sector-Wide Plan to Achieve Stable Power (2010), accessed from www.nigeriaelectricityprivatisation.com/wp-content/plugins/download-monitor/download.php?id=43 on December 12, 2012.
A. O. Cole, Restructing the Electric Power Utility Industry in Nigeria, Proceedings of National Conference of the Nigerian Society of Engineers (Electrical Division), 6-7 October (2004) 1-6.
K. Jin-ho, P. Jong-Bae, P. Jong-Keun, C. Yeung-Han, Generating Unit Maintenance Scheduling under Competitive Market Environments, Elect. Power and Energy Systems, 27 (2005) 189-194.
A. Badri, A. N. Niazi, Preventive Generation Maintenance Scheduling Considering System Reliability and Energy Purchase in Restructured Power System Systems, J. Basic and Applied Sci. Res. 2 (2012) 12773-12786.
O. Obodeh, P. E. Ugwuoke, P. E. (In Press); Optimal Maintenance Scheduling of Generating Units in a Restructured Nigerian Power System, American J. Elect. Power and Energy Systems.
M. A. Rosen, I. Dincer, M. Kanoglu, Role of Exergy in Increasing Efficiency and Sustainability and Reducing Environmental Impact, Energy Policy, 36 (2008) 128-137.
K. R. Tapan, D. Amitava, G. Amitava, G. Ranjan, Exergy-based Performance Analysis for Proper O & M decisions in a Steam, Energy Conversion and Management, 51 (2010) 1333-1344.
S. Salari, H. Abroshan, Aging Influence on Exergy Destruction in an Operating 320 MW Steam Power Plant, American Institute of Physis Conference Proceedings, Melaka, Malaysia, 3-4 October, 1440 (2011) 444-450.
S. Barari, A. A. Shirazi, M. Keshavarzi, I. Rostamsowlat, Numerical Analysis and Field Study of the Time-Dependent Energy-exergy of a Gas-Steam combined Cycle, J. Serbian Chemical Society, 77 (2012) 945-957.
S. K. Som, A. Datta, Thermodynamic Irreversibilities and Exergy Balance in Combustion Processes, Science Direct Progress in Energy and Combustion Science, 34 (2008) 351-376.
P. Regulagadda, I. Dincer, G. F. Naterer, Exergy Analysis of a Thermal Power Plant with Measured Boiler and Turbine Losses, Appl. Thermal Engg, 30 (2010) 970-976.
B. Kiran, K. Sachdeva, Performance Optimization of Steam Power Plant through Energy and Exergy Analysis, Int. J. Current Engg and Techno., 2 (2012) 285-289.
J. C. Ofodu, D. P. S. Abam, Exergy Analysis of Afam Thermal Power Plant, Nigerian Society of Engineers (NSE) Tech. Trans., 37 (2002) 14-28.
S. Sengupta, A. Datta, S. Duttagupta, Exergy Analysis of a Coal-based 210 MW Thermal Power Plant, Int.l J. Energy Res., 31 (2007) 14-28.
P. Peerapong, B. Limmeechokchai, Exergetic and Thermoeconomic Analysis of the Rice-Husk Power Plant in Thailand, J. Metals, Materials and Minerals, 19 (2009) 9-14.
A. Rashad, A. El Maihy, Energy and Exergy Analysis of a Steam Power Plant in Egypt, 13th International Conference on Aerospace Sciences and Aviation Technology, May 26-28, Military Technical College, Kobry Eelkobbah, Cairo, Egypt, (2009) Paper No. ASAT-13-TH-02.
C. Mborah, E. K. Gbadam, On the Energy and Exergy Analysis of a 500 kW Steam Power Plant at Benso Oil Palm Plantation (BOPP), Res. J. Environmental and Earth Sci., 2 (2010) 239-244.
B. T. Lebele-Alawa, J. M. Asuo, Exergy Analysis of Kolo Creek Gas Turbine Plant, Canadian J. Mechanical Sci. and Engg, 2 (2011) 172-184.
A. Geete, A. I. Khandwawala, Exergy Analysis of 120 MW Thermal Power Plant with Different Condenser Back Pressure and Generate Correction Curves, Int. J. Current Engg and Techno., 3 (2013) 164-167.
PHCN (2012); Sapele Power Plant Logbook, Sapele, Delta State, Nigeria.
M. A. Lozano, A. Valero, Theory of Exergy Cost, Energy, 18 (1993) 939-960.
G. Tsatsaronis, M. Winhold, Exergoeconomic Analysis and Evaluation of Energy Conversion Plants-1: A New General Methodology, Energy, 10 (1985) 69-80.
J. Szargut, D. R. Morris, F. R. Steward, Exergy Analysis of Thermal, Chemical and Metallurgical Process, Hemisphere Publishing Co. New York, USA, (1988) 330 pp.