Post on 17-Jan-2018
description
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Hospital Building and Campus Piping
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Hospital Building
Occupancy – office and patient areas• Patient areas: 24 hours per day• Office areas: 8 am – 5 pm, Monday - Friday
Building Characteristics:• Four story with basement• 140,000 square feet per floor• Standard construction
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Hospital – Stand alone operation
• Larger building• Larger pumps• Similar applications
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Medical Complex with Central Plant
• All buildings served from a single heating and cooling source located in a central plant• Hot and chilled water are distributed to each building via piping loops
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Medical Complex with Central Plant
Similarities • All previous examples can exist in the same or larger scale
Differences• Pumps may be larger• Distribution piping can be different
• Location of central plant is critical
• Multiple central plants may be tied together
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Campus Piping Systems
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Types of Piping Systems
Closed Loop Systems• Chilled Water Systems• Hot Water Systems
Open Loop System• Condenser Water Systems• Domestic Hot Water Recirculation• Domestic Pressure Boosting (future session)
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Two Pipe Direct Return
CHILLER
CHILLER
CHILLER
Return
Supply
PumpController
Secondary Pumps
Primary Pumps Expansion TankAir Separator
CommonPipe
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Two Pipe Direct Return
Common applications• Basis of design for most CHW systems.• Small, medium, or large size buildings• Low or high rise• Single or multiple buildings• Single supply temperature
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Two Pipe Direct Return
Piping Tips• Common pipe design• Tank
• Point of No Pressure Change (PNPC)• Warmest water
• Air control and relief• 2-way valves
• Size• Location
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Two Pipe Direct Return
Advantages• Simplicity• First Cost• Efficient
Disadvantages• Over-pressurization• Balancing• Head requirement• Thermally linked
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Primary-Secondary-Tertiary
CHILLER
CHILLER
Zone A
Zone B
Zone C
Optional Variable Speed Pump ∆P Sensor
ModulatingControl Valves
Secondary Pump
CHILLER
Primary Pumps
Tertiary Pumps
Common Pipe
Common Pipe
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Primary-Secondary-Tertiary
Common applications• Multi-building campuses• Campuses with large diversity• Campuses with buildings of varying heights• Campuses with long piping runs• Campuses with multiple production plants• Campuses with elevation changes
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Tertiary Loop Piping
T3
T1
Load
Load
MV
Load MV
Common PipeT2
TertiaryZonePumps
Tertiary BridgeSecondary Pump(s)
Secondary ChilledWater Return
Small BypassMaintains AccurateTemperature Reading
Magna3T3
T1
LoadMV
LoadMV
Load MV
Common PipeT2
TertiaryZonePump
Tertiary BridgeSecondary Pump(s)
Secondary ChilledWater Return
Magna3
MV
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Primary-Secondary-Tertiary w/Plate HX
Expansion TankAir Separator
Expansion TankAir Separator
CHILLER
CHILLER
Optional VS Pump ∆P Sensor
ModulatingControl Valves
Secondary Pump
CHILLER
Primary Pumps
Magna3
Common Pipe
Plate HX Plate HXPlate HX
Tertiary Pumps
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Tertiary Loop Piping w/ Plate HX
Small BypassMaintains AccurateTemperature Reading
T3
T1
Load
Load
MV
Load MV
T2
TertiaryZonePumps
Tertiary BridgeSecondary Pump(s)
Secondary ChilledWater Return
Small BypassMaintains AccurateTemperature Reading
Magna3T3
T1
LoadMV
LoadMV
Load MV
T2
TertiaryZonePump
Tertiary BridgeSecondary Pump(s)
Secondary ChilledWater Return
Magna3
MV
Plate HX
Plate HX
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Primary-Secondary-Tertiary
Piping Tips• When HX are used, additional tanks and air separator devices must be added to tertiary
• Controls for secondary and tertiary systems are independent
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Primary-Secondary-Tertiary
Advantages• Hydraulic isolation• Thermal isolation• Horsepower reduction• Operational cost savings• System performance optimization
Disadvantages• Additional piping• Additional control valves• First cost• Over-pressurization of near zones unless plate hx is used
• More pumps
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Open Piped Systems
Chiller Piping• Condenser water piping• Condenser water with economizer.
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Condenser Water Piping
Return
Supply
Tower
Evaporator
Condenser
Primary Pump(s)
Secondary Pump(s)
CondenserPump(s)
ChillerSedimentSeparator
Expansion TankAnd Air Separator
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Condenser Water w/ Economizer
Return
Supply
Tower
Evaporator
Condenser
Primary Pump(s)
Secondary Pump(s)
CondenserPump(s)
Head PressureControl Valve
Heat Exchanger
Loads
Sediment Separator
Expansion TankAnd Air Separator
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Condenser Water Piping
Condenser Water Tips• Installation
• Keep pump suction flooded• Watch NPSH
• Operation• Air pockets• End of curve
• Maintenance• Strainers• Air vents
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Best Practice Design
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Best Practice Design
• Why• Constant speed pump• Variable speed pump
Optimize Pump Impeller
Best Practice Design
• Why‒ Equipment over-sizing‒ Cost penalty‒ Mandate
Optimize Pump Impeller
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Best Practice DesignConstant speed pump
• Trim the impeller.• Utilize the affinity laws.• Follow the system curve.• Save operating cost.• First costs.
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Variable speed pump• Impeller optimization• Follows affinity laws• Does not correct for poor engineering• Over-sized pumps minimize turndown ratio• Over-sized pumps and motors operate at lower efficiencies
• No added first costs
Best Practice Design
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Primary Piping for Hot Water Systems• Pump out of a boiler• Keep the boiler at the lowest possible pressure
• Remember NPSH!Bo
iler
2
P1P2Bo
iler
1
Best Practice Design
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Primary Piping for Chilled Water Systems• Pump into a chiller• Largest pressure drops after the pump
Chill
er
Primary Pumps
Chill
er
Chill
er
Best Practice Design
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System Bypass Options
Return
Supply
PumpController
Secondary CS Pump(s)
Common Pipe
Chille
r 2
Chille
r 1
Chille
r 3
Best Practice Design
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System Bypass Options• Locate bypass near end of system• Locate bypass near end of major loops• Selectively leave 3-way valves• Bypass with pressure activated control• Variable speed considerations
Best Practice Design
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Effect at minimum VFD speed• Below 30% speed: CS, but still VV
1201101009080
504030
2010
7060
0 10 20 30 40 50 60 70 80 90 1000 % Flow
Hea
d
100 % Speed
30% Speed
Best Practice Design
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1000 GPM
1000 GPMPump 1Variable Speed:500GPM@ 100 Ft
Pump 2ConstantSpeed:500 GPM@ 100 Ft
Wrong!
Mixing CS and VS PumpsBest Practice Design
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Sensor Location
Return
Supply
PumpController
VFDs
∆PSensor
Chille
r 3
Chille
r 2
Chille
r 1
Primary Pumps
Secondary Pumps
Best Practice Design
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Sensor Location
• The Traditional Way– Hydronically, the farthest load– Typically the largest, farthest load– Maximize the variable head loss– Multiple sensors are a benefit
Best Practice Design
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Optimized solution not only for the pumps, but for the total system conditions
• Uncontrolled (constant volume) curve• Constant pressure• Proportional pressure• Temperature control• FLOWADAPT• AUTOADAPT
Best Practice Design
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Best Practice Design
Q100%25%
H
1. Uncontrolled2. Constant pressure3. Proportional pressure (calculated)4. Proportional pressure (measured)5. Temperature control
0 20 40 60 80 100
100
80
60
40
20
0
Flow in %
Effec
t in
% 1.
2.
3.4.5.
Get Additional Energy Savings
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35
40
45
50
55
60
65
70
100%75%50%25%0%Flow in %
Efficie
ncy %
Constant P. Proportional P. Proportional P. Temperature Control
Best Practice Design - Demand MoreTotal Efficiency vs. Control Modes
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Total efficiency
30
40
50
60
70
100%75%50%25%0%Flow
Constant PressureProportional PressureProportional PressureTemperature Control
EFFECT P1
020406080100
100%75%50%25%0%Flow
Constant PressureProportional PressureProportional PressureTemperature Control
Best Practice Design - Demand More Comparison
Flow Limit
0 25 50 75 100
FLOWLIMITPotential saving compared to anunintelligent pump
Potential saving compared with proportional pressure mode
Duty point
Additional saving with FLOWLIMIT
Performance curve
Intelligent Control – FLOWADAPT/FLOWLIMIT
Best Practice Design - Demand More
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Best Practice Design - Demand More