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The pump system savings have been developed based on information from several sources. Descriptions of the types of system improvements applicable to pumps for each measure cate­ gory are contained in Table 2-3.

Table 2-3: Assumptions on Pump System Efficiency Measures

Measure Sources and Method to Determine Applicable Load and Savings Fraction Reduce Overall System

Requirements

Equalize flow over production cycle Easton Consultants3 report suggests savings are in the 10–20 percent range. using holding tanks.

Eliminate bypass loops and other Easton report suggests savings are in the 10–20 percent range. unnecessary flows.

Increase piping diameter to reduce The retrofit of increasing pipe diameter has been done in 9 percent of facilities according to the prac­ friction. tices survey. This is an expensive measure but the Easton report suggests savings are in the

5–20 percent range. This is corroborated by specialists in the pulp and paper industry.4

Reduce “safety margins” in design This measure is applicable to all pumps. Easton report suggest savings are in the 5–10 percent range. system capacity.

(Table continues on next page)

3 Easton Consultants, Strategies to Promote Energy-Efficient Motor Systems in North America’s OEM Markets. Stamford, Con­ necticut. Easton Consultants, Inc. 1995.

4 Personal communications with R. Giese.

Pump system energy effi­ ciency can be improved by 20%, on average, across U.S. industry with a variety of system efficiency measures.

Table 2-3: Continued

Measure Sources and Method to Determine Applicable Load and Savings Fraction Match Pump Size to Load

Install parallel systems for highly According to the practices survey 5 percent of facilities have implemented parallel pumps. Easton variable loads. report suggest savings are in the 10–50 percent range. Other experts5 report that the “best practice”

for variable loads is to install a larger pump with speed control to obtain similar savings. Reduce pump size to better fit load. According to the practices survey 5 percent of facilities have implemented smaller pumps. Easton

report, supported by other experts, suggests that pumps are routinely 15–25 percent oversized.6

Reduce or control pump speed

Reduce speed for fixed loads: According to the inventory data, 82 percent of pumps have load modulation recorded as “none.” trim impeller, lower gear ratios. Performance optimization studies cite savings as high as 75 percent in the food processing, paper and

petrochemical industries.

Replace throttling valves with speed According to the inventory data, 6 percent of pumps have load modulation recorded as “throttle valve,” controls to meet variable loads. which seems low according to industry experts. Case studies of ASD installations show savings in the range of 30 to 80 percent.7 This measure applies to circulating pump systems, not systems with static heads.

Improve Pump Components

Replace typical pump with most According to the inventory data, 16 percent of pumps are greater than 20 years old, many of which can efficient model, or one with an be replaced with more efficient models that better match the process operating point. According to efficient operating point better industry experts, the problem is not necessarily the age of the pump but the fact that the process may suited to the process flows. have changed over time and that the operating point does not match the best efficiency point of the

pump. Easton report notes pump efficiency may degrade 10–25 percent before replacement. Newer pumps are 2–5 percent more efficient. ACEEE8 cites savings in the 2–10 percent range.

Replace belt drives with direct According to the inventory data, 4 percent of pumps have drive type as V-belt, many of which can be coupling. replaced with direct couplings. Savings are on the order of 1 percent

Operation and Maintenance

Replace worn impellers, especially According to the Hydraulic Institute9, pump efficiency degrades from 1 to 6 points for impellers less in caustic or semi-solid applications. than maximum diameter and with increased wear ring clearances. Pumps less than 15 HP are particu- Inspect and repair bearings, lip larly sensitive to reductions in pump efficiency due to mechanical losses.

seals, packings and other mechan­ ical seals.

Based on the information summarized in Table 2-3, we developed estimates of the applicability and savings fractions for pump system efficiency measures. These are shown in Table 2-4. This table and the corresponding tables for fan and air compressor efficiency measures have been reviewed by a panel of engineers and industry experts.

savings potential for pump, fan, and compressed air systems. Note that the greatest savings for pump systems relate to controlling pump speed. This is consistent with expert opinion that cir­ culating pumps are generally good candidates for ASDs.

5 Personal communication with Robert W. Bailey at Planergy, Richmond, CA, October 30, 1997. 6 Personal communication with Gunnar Hovstadius, ITT Flygt, Trumbull, CT.

7 Unpublished data, Wisconsin Performance Optimization Service Program.

8 Elliot, R. Neal. Electricity Consumption and the Potential for Electric Energy Savings in the Manufacturing Sector. Washington, D.C. ACEEE 1994.

9 Hydraulic Institute. Efficiency Prediction Method for Centrifugal Pumps. Parsippany, NJ. 1994.

They represent our best estimates of

Table 2-4: Pump System Improvement Applicability and Savings

Applicability _Savings

Measure Low Midrange High Fraction Net Savings

Reduce Overall System

Requirements 40% 50% 65% 10% 5.0%

Match Pump Size to Load 10% 20% 30% 20% 4.0%

Reduce or Control Pump Speed 15% 35% 45% 30% 10.5%

Improve Pump Components 5% 10% 15% 5% 0.5%

Operation and Maintenance 2% 5% 7% 2% 0.1%

Overall Savings 20.1%