OFF-DESIGN PERFORMANCE ANALYSIS OF A PUMPING SYSTEM IN A NATURAL GAS COMBINED CYCLE TAKING INTO CONSIDERATION ENVIRONMENTAL CONDITIONS

Bravo S.F.; Bravo H.J. · ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) (2024) · DOI: 10.1115/imece2024-145982

Resumen

Centrifugal pumps are essential and vitally important components in thermodynamic electricity generation cycles such as Natural Gas Combined Cycles (NGCC). Reliability and the correct choice of equipment can define the correct functioning of a thermal generation power plant. Environmental conditions can have a direct impact on the performance and behavior of thermal machines and combined cycles are no exception. This behavior directly affects the pumping systems since flow rate, thermal properties of the fluid and Total Dynamic Head (TDH) are modified. Environmental conditions such ambient pressure, ambient temperature and relative humidity are commonly used as input parameters to make real simulations of thermal electric plants. This research focuses on a design and an off-design methodologies which together can predict the behavior and performance of a combined cycle by taking into consideration two of the most important variables before mentioned: environmental pressure and ambient temperature. Centrifugal pumps in specific are directly modified since those changes will directly affect the performance of the plant and therefore the demand for working fluid is also modified. This specific investigation focuses on how meteorological parameters modify the behavior of the pumping system of a Rankine cycle included in NGCC, and how only considering the design conditions when modeling a thermal plant can mean oversizing the centrifugal pumps physically and energetically, making them unnecessarily larger. The study has taken real meteorological data from two places: La Joya and Majes (located in south of Peru). The energy demand in Peru is constantly growing, industry and mining activities are considered important in the economy of the country. The modeling under design and off-design conditions used in this research could predict the behavior of the pumping system in an hourly simulation for a full year (8760 simulations). The results show that the flow rate of the average working fluid is greatly reduced, between 23.79% and 30.03% in La Joya and between 31.69% and 39.03% in Majes in real conditions, the TDH varies slightly but without significant importance, it is shown that the oversizing of the pumping equipment can become energetically considerable compared to the conditions at the design point, being on average 22.95% and 28.65% lower in La Joya and Majes respectively, finally the energy consumption of the pumping system in La Joya is higher than in Majes by 4.64% but this is compensated by the energy generated in La Joya which is bigger by 6.64% compared to Majes. Copyright

Instituciones: Universidad Nacional de San Agustín de Arequipa; Universidad Tecnológica del Perú