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Chiller Plant Control

Chiller Plant Control. Tracer Summit Chiller Plant Control. Standard Summit Application Program Flexible to accommodate a variety of plant designs Feature rich supports control strategies Easy to understand user interface. The Value in Chiller Plant Control. Pre-engineered Features.

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Chiller Plant Control

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  1. Chiller Plant Control

  2. Tracer Summit Chiller Plant Control • Standard Summit Application Program • Flexible to accommodate a variety of plant designs • Feature rich supports control strategies • Easy to understand user interface

  3. The Value in Chiller Plant Control

  4. Pre-engineered Features • Load determination • Capacity matching • Rotation • Chiller setpoint control • Failure recovery • User interface Reliable chilled water flow

  5. Load Determination (when to add or subtract a chiller) • Match plant capacity to building load • Run as few chillers as possible at optimal efficiency Matched Capacity => Reduce Operating Costs

  6. Load Determination • Constant or variable flow systems • Add logic • Based on Supply Temp and Chilled Water Setpoint • Operator editable delay times and deadbands • Subtract logic • Based on Supply/Return Water Temps or Bypass Flow (for large systems) and Chiller Capacities • Operator editable delay times and deadbands • Custom • Adaptable to suit customer specific algorithm requirements Reduce Operating Costs

  7. Add Example Add timer starts Chiller is added 47.5° 2.5° Add temp deadband Add timer reset 45° Add delay time (10 minutes) Chilled water supply temp System supply setpoint Prevents Unnecessary Cycling

  8. Subtract Example (Temperature) Chilled water delta temp 10° Subtract timer starts Chiller is subtracted Design delta temp 6.2° Subtract timer reset Subtract delta temp 0° Subtract delay time (20 minutes) Prevents Unnecessary Cycling

  9. Subtract Example (Flow) Subtract flow threshold Subtract timer starts Chiller is subtracted 1080 GPM 900 GPM Subtract timer reset Chiller design flow capacity Subtract delay time (20 minutes) Reduce Operating Costs

  10. C h i l l e r # 2 C h i l l e r # 1 Plant Layout FlexibilityConstant Flow CW Return Temp CW Supply Temp

  11. C h i l l e r # 2 C h i l l e r # 1 Plant Layout FlexibilityVariable Flow - Decoupled Production Pressure Differential Controller or Transmitter Air Handling Units Bypass Line Distribution Variable-Speed Drive Control Valves

  12. Capacity Matching(turn the right chiller on) • Dependent on chiller plant design • Normal - identical chillers • Base - heat recovery / super efficient • Peak - back up / alternate energy source / inefficient • Swing - match the load ! • Custom - mix & match / nested CPC objects Reduce Operating Costs

  13. Rotation (which chiller leads) • Flexible for System Needs • Selected chiller types (Base / Normal) • Calendar based • Other system inputs • Run time based • Manual operator decision Reliable Chilled Water

  14. Current Limit Setpoint Control • Soft Start • Prevents excess capacity on “warm” starts • Pull down the system smoothly • Unload before start • Ride out flow transients during pump control • Variable flow / multiple pump systems • Low supply water temperatures Reduce Operating Costs

  15. Soft Start Example System chilled water supply temperature Chiller plant enabled in the soft start mode 65° Chiller plant transitions from soft startmode to normal mode 20° Soft start deadband 47.5° 2.5° Add temp deadband System supply setpoint 45° Reduce Operating Costs

  16. Failure Recovery keep chilled water flowing • Follow the standard sequence • Multiple failure inputs • Chiller level • System level • Editable time delays Reliable Chilled Water

  17. Diagnostics and Reports • Standard status reports • Diagnostic reporting and message routing Reduced Maintenance Cost

  18. User Interface • Easy to understand • Textual explanations • Graphical illustrations • Intuitive selections • Pre-engineered Reliable chilled water flow

  19. Reliable chilled water flow

  20. Take-aways • Standard Application Program • Flexible to accommodate a variety of plant designs • Feature rich supports control strategies • Easy to understand user interface

  21. Take-aways

  22. ...your systems company Chiller Plant Control

  23. Plant Optimization The meter is on the building! Reduce Operating Costs

  24. Optimization - the meter is on the building! • Chiller selection • Tower control • Distribution pumping static pressure control • System soft loading • System setpoint selection • Humidity / comfort compensation Reduce Operating Costs

  25. Optimization - Chiller - Tower Control • Low limit • Protect the tower & chiller • Chiller - tower optimization • Real Time Calculations? • Move less air? • Pump less water? Reduce Operating Costs

  26. Chiller - Tower Control what is optimal? 350 300 Chiller kW 250 Tower kW 200 Total kW kW 150 100 50 0 22.5 23 24 24.5 25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 Tower Supply Temp Reduce Operating Costs

  27. Distribution Pumping static pressure control • Normally controlled based on system supply / return pressure difference. • Highest system pressure closest to pumps • Highest system pressure at part load • 2-Way valve control stability • Large chiller plant syndrome (leaky valves) Reduce Operating Costs

  28. Distribution Pumping critical valve pressure control • Critical valve reset • Just like VAV Critical Zone Reset but on the water side • Benefits • Reduced pump energy • Better coil control • Extend pump life • Better acoustics Pressure Differential Controller or Transmitter Air Handling Units Control Valves Reduce Operating Costs

  29. Distribution Pumping critical valve pressure control • Requires fully integrated systems • Execution • Monitor critical AHU valve position • Reset distribution static pressure setpoint • Any valve > 90 % open increase setpoint • All valves < 80 % open decrease setpoint Reduce Operating Costs

  30. How to Determine What’s Best? • Remember the meter is on the building • Consider the life cycle costs • Use a computer simulation for chiller selection and tower system sizing Reduce Operating Costs

  31. Preventive Maintenance • Regular data logging / interpretation • Operator training • Regular maintenance • Scheduled teardown inspections Reduce Maintenance Costs

  32. Preventive Maintenance chiller logging - why? • Condenser water 0.5oC High 1.5 % • Condenser  0.5oC High 1.5 % • Cond approach 1.0oC High 3.0 % • Evap setpoint 0.5oC Low 1.5 % • Evap approach 0.5oC High 1.5 % • Cond pressure 15 kPa High 6.0 % -------- • Total losses 15.0 % Reduce Maintenance Costs

  33. Top Three Considerations in Chiller Plant Control • Reduced Risk • Reliable chilled water flow • Operating cost (energy efficiency) • Reduce maintenance cost

  34. Take Aways • Standard Application Program • Flexible to accommodate a variety of plant designs • Feature rich supports control strategies • Easy to understand user interface

  35. ...your systems company Chiller Plant Control

  36. Appendix Materials Follow

  37. Chiller Types, Controllers, and Interfaces

  38. Chiller 5 (480) Peak Chiller 4 (480) Base Chiller 3 (480) Normal 2 Chiller 2 (480) Normal 1 Chiller 1 (320) Swing Capacity MatchingChillers On vs. Load 92% 1760 75% 1440 % Building Load 67% 1280 50% 960 800 40% 480 25% Tons 0% Chiller Stages (1920 Ton load) Reduce Operating Costs

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