Session: 09-13-03: Design Analysis and Optimization of Energy Conversion Systems III

Paper Number: 167075

Off-Design Performance Analysis of a Pumping System in a Natural Gas Combined Cycle Taking Into Consideration Environmental Conditions 

Pumping systems play a vital role in various industrial applications, especially in energy generation and water distribution systems, energy consumption in pumping systems can become a significant factor for medium to long term projects, such as natural gas combined cycles (NGCC). The correct selection of equipment in hydraulic systems leads to considerable economic savings, especially from an energy efficiency standpoint. This is crucial since energy consumption can represent a substantial percentage of the total costs associated with both the installation and operation of the equipment over its lifetime.

Centrifugal pumps are frequently oversized unnecessarily due to multiple factors. One of the main reasons for this is the assumption that the equipment will always operate under constant flow conditions. However, this is not true in many practical applications, particularly in thermodynamic cycles for electricity generation. In these cases, the required flow rate may vary significantly depending on several external factors, such as environmental conditions. For thermal power generation systems, ambient temperature and atmospheric pressure play a crucial role in determining the actual performance of the entire system.

To better understand these variations, an off-design energy analysis was performed, considering real meteorological data from two different geographical locations. This analysis was then compared with the results obtained from a conventional energy study conducted at the design point. The off-design simulation was executed on an hourly basis for an entire year at both selected locations. Additionally, the actual flow rate data of the Rankine cycle, which operates within the NGCC, were examined to make an optimal selection of the three centrifugal pumps that form part of the thermodynamic cycle.

The study's findings indicate that the differences in energy consumption between the selected pumping equipment in the conventional energy model and the off-design model depend on two key factors: flow rate and total dynamic head (TDH). When both parameters exhibit high values, the absolute and proportional differences between the equipment chosen through conventional selection methods and those selected via off-design analysis increase significantly.

Among the three centrifugal pumps within the thermodynamic system, the percentage differences in energy consumption between the models were observed to be as follows: between 10.65% and 12.10% for the pump with the lowest consumption, between 6.44% and 12.81% for the intermediate pump, and between 21.95% and 24.34% for the pump with the highest energy consumption. These values varied depending on the analyzed location, highlighting the importance of environmental factors in energy-efficient pump selection.

Presenting Author: Said F. Bravo Universidad Nacional de San Agustín de Arequipa

Presenting Author Biography: Student of mechanical engineering of the Universidad Nacional de San Agustín de Arequipa. I am interested in hydraulic systems, coding, simulation models and structural analysis.

Authors:

Said F. Bravo Universidad Nacional de San Agustín de Arequipa
Hector J. Bravo Universidad Tecnológica del Perú