1 / 78

Roy Hubbard

Roy Hubbard. A g e nda. Understanding the three basic piping systems Design and Off-design operation Advantages and Disadvantages Low DeltaT Syndrome – causes, effects, and solutions Design & Control Considerations (VPF) Chillers CHW Pumps Bypass Valve. 4.

celina
Download Presentation

Roy Hubbard

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RoyHubbard

  2. Agenda • Understanding the three basic pipingsystems • Design and Off-designoperation • Advantages andDisadvantages • Low DeltaT Syndrome – causes, effects, andsolutions • Design & Control Considerations(VPF) • Chillers • CHWPumps • BypassValve 4

  3. Chilled Water Piping System Types(typical) 4

  4. LoadEquation Load = Flow XDeltaT SecondaryPumps 4

  5. Constant Primary Flow(CPF) SecondaryPumps 4

  6. Load = Flow XDeltaT Constant Primary Flow(CPF) DedicatedPumping SecondaryPumps 4

  7. Constant Primary Flow atDesign 56ºF (13.3ºC) SecondaryPumps 56ºF (13.3ºC) (189 l/s) @ 6.7ºC) 56ºF (13.3ºC) (1760kW) (63l/s) 56ºF (13.3ºC) (189 l/s) @ 13.3ºC) 4

  8. Constant Primary Flow at 75%Load 75% 53ºF (11.7ºC) SecondaryPumps 53ºF (11.7ºC) (189 l/s) @ 6.7ºC) 53ºF (11.7ºC) (1760kW) (63l/s) 56ºF (13.3ºC) 53ºF 53ºF (11.7ºC) (189 l/s) @ 11.7ºC) 8

  9. Constant Primary Flow at 50%Load 50% 50ºF (10ºC) SecondaryPumps 50ºF (10ºC) (189 l/s) @ 6.7ºC) 50ºF (10ºC) (1760kW) (63l/s) 56ºF (13.3ºC) 50ºF (189 l/s) @ 10ºC) 50ºF (10ºC) 9

  10. Constant Primary Flow at 25%Load 25% 47ºF (8.3ºC) SecondaryPumps 47ºF (8.3ºC) (189 l/s) @ 6.7ºC) 47 ºF (8.3ºC) (1760kW) (63l/s) 56ºF (13.3ºC) 47ºF (189 l/s) @ 8.3ºC) 47ºF (8.3ºC)

  11. Constant FlowPrimary • Advantages • Lowest installedcost • Less plant space thanP/S • Easy to Control &Operate • Easy toCommission • Disadvantages • Highest Plant Energy Cost (must run all, even at lowloads)

  12. Primary (Constant) / Secondary(Variable)

  13. Primary (Constant) / Secondary(Variable) SLoad = Flow XDeltaT SecondaryPumps PLoad = Flow XDeltaT

  14. Primary (Constant) / Secondary(Variable) Headered Pumping SecondaryPumps

  15. Primary (Constant) / Secondary(Variable) DedicatedPumping SecondaryPumps

  16. Primary (Constant) / Secondary(Variable) Rule ofFlow Primary flow must always be equal to or greater thanSecondaryflow. SecondaryPumps

  17. Primary/Secondary atDesign 100% Load = 100% SecFlow 56ºF (13.3ºC) SecondaryPum ps ºF C 3000 GPM @44 189 l/s @ 6.7º 100 ft (303 kPa)Head 56ºF (13.3ºC) 56ºF (13.3ºC) 44.0 °F (6.7°C) (1760kW) 0 GPM @ 44ºF 0 l/s @ 6.7ºC (63l/s) 3000 GPM @ 56ºF 56ºF (13.3ºC) (189 l/s) @ 13.3ºC) (189 l/s) @ 13.3ºC) 50 ft (152 kPa)Head

  18. Primary/Secondary at 75%Load 75% Load = 75% SecFlow 75% 53ºF (11.7ºC) SecondaryPumps 2250 GPM @ 44ºF 142 l/s @ 6.7ºC 53ºF (11.7ºC) 53ºF (11.7ºC) 44.0 °F (6.7°C) (1760kW) 750 GPM @ 44ºF 47 l/s @ 6.7ºC (63l/s) 2250 GPM @ 56ºF 3000 GPM @ 53ºF (189 l/s) @ 11.7ºC) 56ºF (13.3ºC) (142 l/s) @ 13.3ºC)

  19. Primary/Secondary at 50%Load 50% Load = 50% SecFlow 50% Secondary Pumps 1500 GPM @ 44ºF 95 l/s @ 6.7ºC 53ºF (11.7ºC) 53ºF (11.7ºC) 44.0 °F (6.7°C) (1760kW) 500 GPM @ 44ºF 32 l/s @ 6.7ºC (63l/s) 1500 GPM @ 56ºF 2000 GPM @ 53ºF (126 l/s) @ 11.7ºC) 56ºF (13.3ºC) (95 l/s) @ 13.3ºC)

  20. Primary/Secondary at 25%Load 25% Load = 25% SecFlow 25% SecondaryPumps 750 GPM @ 44ºF 47 l/s @ 6.7ºC 53ºF (11.7ºC) 44.0 °F (6.7°C) (1760kW) 250 GPM @ 44ºF 16 l/s @ 6.7ºC (63l/s) 750 GPM @ 56ºF 1000 GPM @ 53ºF (63 l/s) @ 11.7ºC) 56ºF (13.3ºC) (47l/s) @ 13.3ºC)

  21. What Controls the Flow of the SecondaryLoop? But what controls theVSD’s?

  22. Valve Controls Leaving Air Temperature(LAT)

  23. Valve Controls Leaving Air Temperature (LAT) Set Point = 55º (12.8º)LAT T

  24. Valve Controls Leaving Air Temperature (LAT) Set Point = 55º (12.8º)LAT T

  25. Valve Controls Leaving Air Temperature (LAT) Set Point = 55º (12.8º)LAT T

  26. As Valve Opens, Pressure in loop lowers As Valve Closes, Pressure in looprises

  27. Pressure Differential Sensor Controls Secondary PumpSpeed • Differential Pressure sensor on lastcoil • controls speed • to Set Point (coil WPD+Valve PD+PipingPD+Safety) • located at end of Index Circuit for bestefficiency SetPoint P=25 ft (76kPa) P

  28. Primary (Constant) / Secondary(Variable) • Advantages • Easy toControl • Easy toCommission • Loopseparation • Easiertrouble-shooting • Separating isolated loads/buildings for lower total pumpenergy • Lower Plant Energy (can sequence chillers and ancillaryequipment) • Versatile – multi-circuitcapability • Disadvantages • Medium Pump EnergyCost • Highest Installed Cost (Sec Pumps, Piping,etc.) • Potential for higher plant energy loss because of Low Delta Tsyndrome

  29. Variable PrimaryFlow

  30. Load = Flow XDeltaT Variable PrimaryFlow Variable Primary Flow at 100% System Load Two-way valves control capacity By varying flow of water incoils PrimaryPumps Chillers Closed 30

  31. Primary/SecondarySystem ThreeDifferences? Variable PrimarySystem PrimaryChillers Pumps 30

  32. Variable Primary Flow atDesign Variable PrimaryFlow at 100% System Load Two-way valves control capacity By varying flow of water incoils 100% Load = 100%Flow 56ºF (13.3ºC) 3000 GPM @ 44ºF 189 l/s @ 6.7ºC 56ºF (13.3ºC) 56ºF (13.3ºC) 44.0°F (6.7°C) 0 GPM @ 44ºF 500 Ton (1760kW) Primary Pumps 1000 GPMeach (63l/s) 0 l/s @ 6.7ºC Chillers Closed 3000 GPM @ 56ºF (189 l/s) @ 13.3ºC) 3000 GPM @ 56ºF (189 l/s) @ 13.3ºC) 56ºF (13.3ºC) 30

  33. Variable Primary Flow at 75%Load Variable PrimaryFlow at 75% SystemLoad Two-way valves control capacity By varying flow of water incoils 75% Load = 75%Flow 56ºF (13.3ºC) 2250 GPM @ 44ºF 142 l/s @ 6.7ºC 56ºF (13.3ºC) 56ºF (13.3ºC) 44.0°F (6.7°C) 0 GPM @ 44ºF PrimaryPumps 750 GPMeach (47l/s) 0 l/s @ 6.7ºC Closed 2250 GPM @ 56ºF 2250 GPM @ 56ºF 56ºF (142 l/s) @ 13.3ºC) (142 l/s) @ 13.3ºC) (13.3ºC) 33

  34. Variable Primary Flow at 50%Load Variable PrimaryFlow at 50% SystemLoad Two-way valves control capacity By varying flow of water incoils 50% Load = 50%Flow 1500 GPM @ 44ºF 95 l/s @ 6.7ºC 56ºF (13.3ºC) 56ºF (13.3ºC) 44.0°F (6.7°C) 0 GPM @ 44ºF PrimaryPumps 750 GPMeach (47l/s) 0 l/s @ 6.7ºC Closed 1500 GPM @ 56ºF 1500 GPM @ 56ºF 56ºF (95 l/s) @ 13.3ºC) (95 l/s) @ 13.3ºC) (13.3ºC) 34

  35. Variable Primary Flow at 25%Load Variable PrimaryFlow at 25% SystemLoad Two-way valves control capacity By varying flow of water incoils 25% Load = 25%Flow 750 GPM @ 44ºF 47 l/s @ 6.7ºC 56ºF (13.3ºC) 44.0°F (6.7°C) 0 GPM @ 44ºF PrimaryPumps 750GPM (47l/s) 0 l/s @ 6.7ºC Closed 750 GPM @ 56ºF (47 l/s) @ 13.3ºC) 750 GPM @ 56ºF (47 l/s) @ 13.3ºC) 56ºF (13.3ºC) 35

  36. Variable Primary Flow in Bypass Mode System flow below chiller min flow (250gpm) Variable PrimaryFlow at 25% SystemLoad Two-way valves control capacity By varying flow of water incoils 100 GPM @ 44ºF 6.3 l/s @ 6.7ºC 48.8 ºF (9.3ºC) 44.0°F (6.7°C) 150 GPM @ 44ºF PrimaryPumps 250GPM (15.8l/s) 9.5 l/s @ 6.7ºC Open 250 GPM @ 48.8ºF (15.8 l/s) @ 9.3ºC) 100 GPM @ 56ºF (6.3 l/s) @ 13.3ºC) 56ºF (13.3ºC) 37

  37. Varying Flow Through Chillers -Issues • Issue During NormalOperation • Chiller Type (centrifugal fast, absorbersslow) • Chiller Load (min load - no variance, full load - maxvariance) • System Water Volume (more water, more thermal capacitance, faster varianceallowed) • Active Loads (near or far fromplant) • Typical VSD pump ramp rate setting of 10%/minute (accel/decel rates set to 600seconds) 37

  38. Varying Flow Through Chillers -Issues • Issue During NormalOperation • Chiller Type (centrifugal fast, absorbersslow) • Chiller Load (min load - no variance, full load - maxvariance) • System Water Volume (more water, more thermal capacitance, faster varianceallowed) • Active Loads (near or far fromplant) • Typical VSD pump ramp rate setting of 10%/minute (accel/decel rates set to 600seconds) 37

  39. Varying Flow Through Chillers -Issues • Issue During NormalOperation • Chiller Type (centrifugal fast, absorbersslow) • Chiller Load (min load - no variance, full load - maxvariance) • System Water Volume (more water, more thermal capacitance, faster varianceallowed) • Active Loads (near or far fromplant) • Typical VSD pump ramp rate setting of 10%/minute (accel/decel rates set to 600seconds) • Issue AddingChillers • Modulating isolation valves onchillers 37

  40. Variable Primary System – Staging on chillers & changes in flowrate Current Situation – 1 chillerrunning Variable PrimaryFlow at 100% System Load Two-way valves control capacity By varying flow of water incoils 1000 GPM @ 44ºF 63 l/s @ 6.7ºC 44.0 °F (6.7°C) PrimaryPumps 500 GPMeach (32l/s) Closed 1000 GPM @ 56ºF (63 l/s) @ 13.3ºC) 56ºF (13.3ºC) 40

  41. Variable Primary System – Staging on chillers & changes in flowrate Current Situation –building load increases, valve opens, second chillerstarts Variable PrimaryFlow at 100% System Load Two-way valves control capacity By varying flow of water incoils If valve opens tooquick: Chiller1 shuts down on low ch water tempcutout illed Bestpractice! Open valve over 1.5 to 2 minutesto allow for systemstabilization 1100 GPM @ 45ºF 69 l/s @ 7.2ºC 45.0 °F (7.2°C) PrimaryPumps 550 GPMeach (35l/s) Closed 1100 GPM @ 57ºF (69 l/s) @ 13.9ºC) 57ºF (13.9ºC) 48

  42. Variable Primary Flow (VPF) SystemArrangement • Advantages • Lower Installed Cost (approx. 5% comparedP/S) • No secondary Pumps or piping, valves, electrical, installation,etc. • Offset somewhat by added 2W Bypass Valve and more complexcontrols • Less Plant SpaceNeeded • Best Chilled Water Pump Energy Consumption (most optimeadyconfiguration) • VSD energysavings • Lower Pump DesignHead 48

  43. Primary/Secondary 56ºF (13.3ºC) SecondaryPumps 3000 GPM @ 44ºF 189 l/s @ 6.7ºC 100 ft (303 kPa)Head 56ºF (13.3ºC) 56ºF (13.3ºC) 44.0 °F (6.7°C) (1760kW) 0 GPM @ 44ºF 0 l/s @ 6.7ºC (63l/s) 3000 GPM @ 56ºF 56ºF (13.3ºC) (189 l/s) @ 13.3ºC) (189 l/s) @ 13.3ºC) 50 ft (152 kPa)Head 48

  44. Variable PrimaryFlow Variable PrimaryFlow at 100% System Load Two-way valves control capacity By varying flow of water incoils 56ºF (13.3ºC) 3000 GPM @ 44ºF 189 l/s @ 6.7ºC 56ºF (13.3ºC) 56ºF (13.3ºC) 44.0°F (6.7°C) 0 GPM @ 44ºF 500 Ton (1760kW) Primary Pumps 1000 GPMeach (63l/s) 0 l/s @ 6.7ºC Chillers Closed 3000 GPM @ 56ºF (189 l/s) @ 13.3ºC) 3000 GPM @ 56ºF (189 l/s) @ 13.3ºC) 56ºF (13.3ºC) 140 ft (424 kPa)Head 48

  45. PumpEnergy BHP= GPM X Head 3960 XPumpEff 48

  46. Variable Primary Flow (VPF) SystemArrangement • Advantages • Lower Installed Cost (approx. 5% comparedP/S) • No secondary Pumps or piping, valves, electrical, installation,etc. • Offset somewhat by added 2W Bypass Valve and more complexcontrols • Less Plant SpaceNeeded • Best Chilled Water Pump Energy Consumption (most optimeadyconfiguration) • VSD energysavings • Lower Pump DesignHead • Higher PumpEfficiency 48

  47. Pump Curves - PumpEfficiency 48

  48. Pump Curves - PumpEfficiency With VPF you will need larger pumps compared to P/S, but they will be operating at a more efficient point, yielding energysavings 48

  49. PumpEnergy BHP= GPM X Head 3960 XPumpEff 48

  50. Variable Primary Flow (VPF) SystemArrangement • Advantages • Medium Installed Cost (approx. 5% comparedP/S) • No secondary Pumps or piping, valves, electrical, installation,etc. • Offset somewhat by added 2W Bypass Valve and more complexcontrols • Less Plant Space Needed (vsP/S) • Best Chilled Water Pump Energy Consumption (most optimeadyconfiguration) • VSD energysavings • Lower Pump DesignHead • Higher PumpEfficiency • Lower potential impact from Low Delta T (can over pump chillers ifneeded)

More Related