Total Cost of Ownership (TCO) for Variable Speed Pumping Systems

Transcription

1 Total Cost of Ownership (TCO) for Variable Speed Pumping Systems 1

2 What are the Overall Pump Operational Costs? Consider: 1. Pump System Efficiency 2. System Asset Management 3. True Cost of Power Source: Courtesy of Hydraulic Institute and Pump Systems Matter > Variable speed pumping equipment purchase represents only $.10 for every $1 spent over the life of the system! > Must look at bigger picture! > 90% of TCO spent after initial equipment purchase 2

3 Objectives: Upon Completion You Will: 1. Be able to calculate Pump System Efficiency penalty for operation above and below the Best Efficiency Point (BEP) 2. Define how efficiency of a Pump System relates to equipment Asset Management 3. Tell the difference between Total Electrical Power Costs and Electrical Power Rates, usually expressed as kw/hour 3

4 Seminar Discussion Topics Pump System Inefficiencies Defined using BEP, are not properly accounted for during design Pump System Asset Management may only consider Mechanical Maintenance True Cost of Power may be measured in kwh only Best Practices in managing all 3 of these issues can result in drastic TCO Reduction in Pumping Systems Overview and Schneider Electric Resources Conclusion, Questions and Answers 4

5 Maximizing Energy Efficiency: Only Part of the Equation Let s not forget > Affinity laws for centrifugal loads dictates power versus speed > HP varies as the cube of speed reduction > Physics have been main driver for applying VFD s to these type loads 5

6 Maximizing Energy Efficiency: Only Part of the Equation 6

7 How Can a VFD Benefit Pump Systems Traditional control valves controlling pump Variable speed drive controlling pump Motor running full speed : Control valve regulates the flow Motor speed controlled by variable speed drive to regulate the flow 7

8 Example 100% Flow If a pump runs at 100% flow continuously: > With VFD > No energy savings > Reduced inrush current > Performance diagnostics > Soft Start may be better BUT > How many systems really run at 100% flow? 8

9 Example 80% Flow Running at 80% flow: > With VFD > 50% energy savings vs full flow > Reduced inrush current > Performance diagnostics > With mechanical system: > 10% energy savings vs full flow > Additional mechanical components > Higher maintenance needed 9

10 Example 50% Flow Running at 50% flow: > With VFD > 85% energy savings vs full flow > With mechanical system: > 25% energy savings vs full flow > VFD uses 1/5 of energy of mechanically restricted flow control system 10

11 Example Pump Curve 11

12 Best Efficiency Point (BEP) is Where You Want to Operate Source: Courtesy of Barringer & Associates- Pump practices & life > Inherent in the pump s mechanical design > Should be considered as a factor affecting system TCO > Equipment life, maintenance costs impacted by operation away from BEP > The BEP is achieved with the correct balance between head and flow > Drives can be set to operate pump at or near BEP ALL THE TIME 12

13 Cost Mean Time Between Failure (MTBF) of Operating Away from BEP: > Reduced equipment life > 75% of pump systems are oversized by 30%, which causes operation away from BEP > Reliability can decrease to 50% of design by operation of pump at -20% to +10% of BEP > In extreme cases, operation from -30% to +15% of BEP decreases reliability by 90%! Source: Courtesy of Barringer & Associates Pump practices & life 13

14 Operating at 60% of BEP Can Result In: Designing system to allow pump to operate at/near BEP is critical to system efficiency 50% 20% 25% 100% 50% lifetime reduction of seals 20% lifetime reduction of bearings 25% lifetime reduction of casing and impeller Approximately 100% increase of maintenance cost Source: Barringer & Associates Pump practices & life 14

15 Seminar Discussion Topics Pump System Inefficiencies Defined using BEP, are not properly accounted for during design Pump System Asset Management may only consider Mechanical Maintenance True Cost of Power may be measured in kwh only Best Practices in managing all 3 of these issues can result in drastic TCO Reduction in Pumping Systems Overview and Schneider Electric Resources Conclusion, Questions and Answers 15

16 Worn Parts Can Impact Pump Efficiency Curves Operation away from BEP causes: > Increased maintenance costs > Decreased pump life > Increase in overall TOC Source: 16

17 Seminar Discussion Topics Pump System Inefficiencies Defined using BEP, are not properly accounted for during design Pump System Asset Management may only consider Mechanical Maintenance True Cost of Power may be measured in kwh only Best Practices in managing all 3 of these issues can result in drastic TCO Reduction in Pumping Systems Overview and Schneider Electric Resources Conclusion, Questions and Answers 17

18 How Can Drives Help Reduce TCO? Elements of Electrical Utility Charges > Analyze current utility costs > See if certain loads can be run at off peak times > Examine peak demand charges when starting larger motors Customer Charge + Actual Energy Charge Demand Charge + + Power Factory Penalty > Avoid power factor penalties by upgrading systems to VFD s = Electrical Energy Bill 18

19 Harmonic Mitigation: Finding the Balance > IEEE 519 Guideline provides recommended limits to determine if any mitigation is needed first > New IEEE only requires current harmonic distortion limits at building transformer primary or secondary > Devices will reduce waveform harmonics so power is distributed more efficiently > Yet, filters and transformers generate heat, adding inefficiency to the system Harmonic Reduction Line Reactor Multi-Pulse Transformer Medium High High Efficiency High Medium Low Filters or Active Front end Size Small Large Small Cost Low Medium High Complexity Low Low High It s a trade off: need to find the sweet spot 19

20 Understanding Load Characteristics Linear load: Voltage and current of a load have the same shape > Resistive Loads Heating elements, incandescent lights, etc. > Inductive Loads such as transformers and motors > Capacitive Loads Non-linear or distorting load: Current waveform is different to voltage waveform. > Welding machines, electric arc furnaces, UPS, servers, PCs > AC & DC Drives 20

21 Understanding Load Characteristics Linear load: Voltage and current of a load have the same shape > Resistive Loads Heating elements, incandescent lights, etc. > Inductive Loads such as transformers and motors > Capacitive Loads Non-linear or distorting load: Current waveform is different to voltage waveform. > Welding machines, electric arc furnaces, UPS, servers, PCs, etc. > AC & DC Drives 21

22 What Causes Harmonics? Harmonics are the created by charging and discharging of the DC bus capacitors in the VFD > Current draw is in abrupt short pulses through diodes / SCRs as part of the rectification of AC power to DC Power (converter portion of any VFD) > The current waveform applied to the VFD becomes slightly distorted by the cumulative effect of current pulses through diodes/ SCR used to convert AC power to DC power > Current distortion is produced in multiples of the fundamental Frequency (60 HZ) > Three phase systems will dominantly produce ODD Order (3, 5, 7, 9, 11 etc.) multiples of the fundamental (60 HZ) > The 5th harmonic in a VFD system is 300Hz Rectifiers lead to distortion which creates harmonics 22

23 Conclusions Three pronged approach can lower Total Cost of Ownership (TCO) 1. Pump BEP operation provides maximum benefit using VFD s 2. Asset Management reduced maintenance costs using VFD s 3. True Energy Cost Management involved more than just examination of utility bill Customer Charge + Actual Energy Charge Demand + Charge + Power Factory Penalty Source: Reducing maintenance costs and downtime with intelligent pumping VFD systems can significantly Electrical lower overall equipment operational = Energyexpenses. Bill 23

24 VFDs are Part of Best Practices > Affinity laws still offer large savings over mechanical flow restriction > VFDs should be fully integrated into process systems > VFDs have a big impact on overall pump TCO > VFDs monitor and manage pump life cycle > VFDs alert owners when maintenance is required > Governing bodies are considering new regulations that mandate efficiency Altivar Process provides maximum smart pumping benefit to reduce overall TCO! 24

25 How Can a Modern VFD Impact my TCO? BEP operation can be key to both process and energy efficiency > Must establish system parameters > VFD can operate pump at or near BEP > Alarm when out of tolerance Smart pumping starts with inputting characteristics to determine pump curve Actual screenshots 25

26 System Asset Management: Maintenance Excellence > Troubleshooting messages with Dynamic QR Codes can speed the time it takes to get a pump back in operation; Code can suggest causes not just indicate Trip > Fast device replacement with assistance from keypad, control system or cloud parameter backup storage > Diagnostic tools and support like trend logs and error/warning logs can assist operators in knowing what happened before VFD trip point Actual screenshots 26

27 True Cost of Power > VFD s can help users analyze individual pump loads within the process using built in accurate power meters > Utilities charge for power differently, knowing which loads are costing the most is important in overall energy budget > Harmonic management of non-linear VFD loads should be part of efficiency studies 27

28 Questions? 28

29 Thank You! 29