Pumps are energy-intensive machines that can be expensive to operate. In many cases, a pump’s energy costs can constitute 90 percent of its lifecycle cost over a 10-year period. However, this cost depends on where the pump is being operated on its curve. Optimizing pump operation by implementing a continuous energy-improvement program can substantially reduce energy, operation and maintenance costs, while also improving productivity, system reliability and safety.
With a continuous energy improvement program, companies realize benefits through a series of activities that, when combined, lead to continuous energy improvement. These activities involve:
- Assigning a pump system “champion.”
- Identifying and managing key performance indicators (KPIs).
- Conducting a comprehensive assessment, including evaluating the
system load (i.e., the need for the pump), as well as the pump, piping,
controls and other system-related equipment.
- Training and educating staff.
- Working with qualified vendors and contractors to optimize pump
1. Assign a Pump System ChampionA pump system champion ensures that the design, operation and maintenance of the pump system are optimized relative to the business objectives (production, safety and energy) of the company. The system champion helps management determine ways in which operation and maintenance practices can be enhanced to contribute to the optimal long-term performance (energy and productivity) of the pump system. Specifically, the pump system champion:
- Minimizes lifecycle cost and maximizes the business
objectives of the system by advocating for the proper design, use, operation
and maintenance of the pump system.
- Understands the details associated with the supply and demand sides
of the pump system.
- Uses his or her knowledge to implement design, operation, maintenance
and commissioning requirements in the safest, most cost-effective way possible.
- Works with management to establish, track and administer the system
to meet the KPIs.
- Communicates performance (energy, productivity and safety) issues and
recommends necessary changes to the pump systems’ management team.
For example, a power reduction of 135 hp (100 kW) in a process that runs 24/7 will reduce energy costs $40,000 per year at an energy price of $0.05/kWh. The maintenance and productivity benefits of improving a pump system’s performance are generally one to two times the value of the energy savings. Plants with large throttled-pump systems often can save up to 50 percent of the electrical cost for operating such systems. Because having a system champion only costs about $12,000 a year (assuming 10 to 15 percent of an $80,000 per year full-time staff position), this savings translates to a significant net benefit.
2. Identify and Manage Key Performance IndicatorsKPIs are important to properly manage any large or critical pump system. The specific performance indicators for pump systems will depend on the particular application, but they might include tracking maintenance costs as a proxy for efficiency (figure 1) or analyzing the actual power required to pump a given volume of fluid (referred to as specific energy [ES], or kWh/Q). To calculate, remember that specific energy (ES) is defined as the quotient that results from dividing the amount of energy used by the pump volume.
3. Conduct a Comprehensive AssessmentEnergy is the single largest cost of ownership of an industrial pump-driven system. It is in the fundamental best interest of the company and the pump-system champion to evaluate the lifecycle costs of the pump system before installing new equipment or carrying out a major overhaul. Lifecycle costing helps identify the lowest total cost of ownership options available. A pump system champion should use a lifecycle cost analysis to evaluate various cost elements, including:
- Equipment costs.
- Installation and commissioning costs.
- Energy costs.
- Maintenance and repair costs.
- Downtime costs.
- Decommissioning and disposal costs.
- Matching supply to demand.
- Right sizing and upgrading motors and pumps.
- Reviewing the applicability of various control methods.
- Turning off equipment that is not needed.
- Lowering operating speeds if possible.
- Operating closer to the best efficiency point.