The peak efficiency achieved in the design point of pumps of different specific speeds1 has not changed much in the past decades. It seems that most commercially available (and engineered) machines approach an invisible efficiency limit. Considering the complete hydraulic system, however, the average system efficiency is less than about 40%.3
Selecting the pump that best fits a given hydraulic system and the control methods of the pump systems offer significant energy savings. Pumps consume between 20 to 60% of the total electricity usage of many industries. The energy saving opportunity has an impact not only on the profitability of the industry, but it is also important in reducing CO2 emissions. Every one megawatt hour (MWhr) electric energy saved can reduce the carbon dioxide (CO2) emission by about 0.6 metric ton. The full potential of energy saving can be achieved only by system level modeling and optimization of hydraulic and thermal processes and their control scheme while respecting the operational constrains.
The energetic revision of pump systems is an optimization task, the objective function of which can be given either in the form of the life cycle cost (LCC) calculated by the remaining life of the system or by the payback time of the conversion.
The topology of the system is described as a general looped network, based on which the equilibrium thermo-hydraulic state is calculated with Kirchhoff’s laws using Newton-Raphson iteration.5 The method allows a quick evaluation of the equilibrium state based on the specified technological conditions (e.g., prescribed pressures or volume flows), design parameters (e.g., pipe length, pipe diameter, pump impeller diameter), and control parameters (e.g., valve settings, pump speed).
This topic describes the functionality and capabilities of the software ""XL+"" which can optimize pipeline systems and control in order to achieve optimum operations.