- Pumping systems are good candidates for reducing energy consumption in manufacturing facilities.
- Proper sizing and speed controls provide significant energy savings.
- The free Pump System Assessment Tool can help you evaluate your system's performance.
Pumping systems are often critical to manufacturing operations; directly supporting production processes. They use a substantial amount of energy, however, which contributes a significant amount to annual operating costs. In many facilities, much of this energy is wasted due to aging equipment, oversizing, as well as poor maintenance and operational practices. Therefore, it is reasonable to look at pumps when searching for ways to reduce energy consumption in motor-driven systems.
Optimizing Pumps and Pump Systems
The U.S. Department of Energy recommends specific energy-efficiency measures to optimize system performance and save significantly on energy costs:
Reduce overall system requirements (do not assume requirements are fixed)
- Equalize flow over production cycle using holding tanks for a 10% to 20% savings
- Eliminate bypass loops and other unnecessary flows for a 10% to 20% savings
- Reduce safety margins in design system capacity and save 5% to 10%
Match pump size to load
- Install parallel systems for highly variable loads, or install a larger pump with speed controls and save 10% to 50%
- Reduce pump size to better fit the load (pumps are routinely over sized by 15% to 25%)
- The Hydraulic Institute recommends using two or more small pumps instead of one large pump, so excess pump capacity can be turned off
Reduce or control pump speed
- Reduce speed for fixed loads—trim impeller, lower gear ratio
- 82% of pumps have no load modulation
- Studies cite savings of 75% in food processing
- Replace throttling valves with speed controls to meet variable loads
- Adjustable Speed Drive installations show savings of 30% to 80% (these savings only apply to circulating pump systems, not systems with static heads)
Replace system components with more efficient models
- Replace typical pumps with the most efficient model, or one with an efficient operating point that is better suited to the operating flows
- 16% of pumps are more than 20 years old
- The problem is not the age of the pump, it is the fact that the process has changed over time (10% to 25% savings)
Reduce friction losses
- Improve friction inefficiency by eliminating unnecessary flow paths and reducing high-flow rate, as well as replacing piping components; throttle valves, in particular, are associated with friction losses
Improve operational and maintenance practices
- Replace worn impellers, especially in semi-solid applications
- Inspect and repair bearings, lip seals, packing, and other seals
- Pump efficiency degrades from 1% to 6 % for impellers less than the maximum diameter, and with increased wear-ring clearance
- The Hydraulic Institute recommends maintaining pumps and all system components in virtually new condition to avoid efficiency loss
- Use pumps operating as turbines to recover pressure energy that would otherwise be wasted
In addition to the improvements mentioned above, other measures for reducing pump system components include adjusting the system flow paths, trimming the pump impeller, and adding a gear reducer and a two-speed motor to the existing pump system.
For more detailed information on increasing pump system efficiency, see Improving Pump System Performance: A Sourcebook for Industry from the U.S. Department of Energy.
Assess the Efficiency of Your Pumping System
The Pumping System Assessment Tool (PSAT), available from the U.S. Department of Energy, helps to evaluate the efficiency of pumping system operations. PSAT uses achievable pump performance data from Hydraulic Institute standards and motor performance data from the MotorMaster+ database to calculate potential energy and associated cost savings. The PSAT software is available free of charge.