Four steps to optimize the pump system

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In terms of energy usage, water pumps are a product with very low costs. However, they account for 25% of the total energy consumed by industrial motors, and this figure is much higher in pump-intensive applications such as urban water supply, wastewater treatment, and processing plants. Although the pumps are highly efficient—reaching up to 90% efficiency for individual units—many facilities do not achieve even close to the efficiency they are capable of reaching. In fact, a study conducted in Finland on 1,690 pumps in 20 processing plants found that the average operating efficiency of the pumps was below 40%, with one-tenth of the pumps having an efficiency lower than 10%. Therefore, when it is necessary to replace the pump or to significantly reduce costs, optimizing the pumping system may be a solution. The following four steps can be taken to optimize the pumping system. First, reduce the system head. Reducing the system head and the energy required to achieve it is the first step. System head: (1) The sum of the pressure difference and height required by the pump to lift the fluid (static head); (2) The resistance generated as the fluid flows through the pipes (friction head); (3) The sum of the resistances caused by valves that are closed in certain sections (control head). Among these three, controlling the head provides the best energy-saving goal. Most systems use valves because their pumps have too high a capacity, and throttling is needed to maintain an appropriate flow rate. For most systems where the control head is too high and there are ongoing maintenance issues, purchasing a smaller pump that better meets the flow requirements or switching to a variable-speed pump can enable users to reduce the system’s control head and save on electricity and maintenance costs. Second, a lower flow rate or operating time. Some pumps keep running, whether the process requires all the flow or not. When the system is diverted, operators have to pay for the electricity they fail to utilize effectively. There are two ways to solve this problem. One option is to switch to a variable-speed pump, which allows the flow rate to be increased or decreased as needed. The second method is to use a set of mixed pumps, some larger and some smaller, and turn them on and off in stages to meet the demand. Both of these methods can reduce bypass flow, thereby saving energy. Third, modify or replace equipment and controls. If the energy savings resulting from lower head and lower flow rates/operation time appear attractive, owners should consider replacing the equipment and control systems. If the system uses a large number of valves for throttling, replace them with smaller pumps that do not require throttling and have lower operating costs. For systems with multiple pumps and fluctuating demand, overhauls may include smaller or variable pumps as well as control logic to automatically turn the pumps on and off as needed. Fourth, improve installation, maintenance, and operational practices. Surprisingly, many maintenance issues start with installation. A cracked foundation or a pump that is not properly aligned can lead to vibration and wear. Improperly configured suction pipes may suffer premature wear due to cavitation or hydraulic loading. When purchasing a pump, installation support must be discussed. For critical applications, it is worthwhile to pay third-party experts for pump commissioning to ensure that the new pump operates as designed throughout its entire service life. There are many ways to handle routine maintenance. Small, inexpensive pumps that fail to meet critical requirements may incur costs due to operational failures. For most pumps, regular preventive maintenance is beneficial. Predictive maintenance – collecting data and using it to determine when operators need to intervene – is a powerful tool for keeping pumps in compliance with specifications. This does not require complex or costly measures; by measuring factors such as pump pressure, energy consumption, and vibration on a monthly or quarterly basis, operators can detect changes in efficiency before issues that may lead to failures occur, and plan appropriate corrective actions.