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Published byMelinda Hancock Modified over 9 years ago
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1 Hospital Building and Campus Piping
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2 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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3 Hospital – Stand alone operation Larger building Larger pumps Similar applications
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4 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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5 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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6 Campus Piping Systems
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7 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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8 Two Pipe Direct Return C H I L L E R C H I L L E R C H I L L E R Return Supply Pump Controller Secondary Pumps Primary Pumps Expansion Tank Air Separator Common Pipe
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9 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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10 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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11 Two Pipe Direct Return Advantages Simplicity First Cost Efficient Disadvantages Over-pressurization Balancing Head requirement Thermally linked
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12 Primary-Secondary-Tertiary C H I L L E R C H I L L E R Zone A Zone B Zone C Optional Variable Speed Pump ∆P Sensor Modulating Control Valves Secondary Pump C H I L L E R Primary Pumps Tertiary Pumps Common Pipe Common Pipe
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13 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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14 Tertiary Loop Piping T3 T1 Load MV Load MV Common Pipe T2 Tertiary Zone Pumps Tertiary Bridge Secondary Pump(s) Secondary Chilled Water Return Small Bypass Maintains Accurate Temperature Reading Magna3 MV
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15 Primary-Secondary-Tertiary w/Plate HX Expansion Tank Air Separator Expansion Tank Air Separator C H I L L E R C H I L L E R Optional VS Pump ∆P Sensor Modulating Control Valves Secondary Pump C H I L L E R Primary Pumps Magna3 Common Pipe Plate HX Tertiary Pumps
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16 Tertiary Loop Piping w/ Plate HX Small Bypass Maintains Accurate Temperature Reading T3 T1 Load MV Load MV T2 Tertiary Zone Pumps Tertiary Bridge Secondary Pump(s) Secondary Chilled Water Return Small Bypass Maintains Accurate Temperature Reading Magna3 T3 T1 Load MV Load MV Load MV T2 Tertiary Zone Pump Tertiary Bridge Secondary Pump(s) Secondary Chilled Water Return Magna3 MV Plate HX
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17 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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18 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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19 Open Piped Systems Chiller Piping Condenser water piping Condenser water with economizer.
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20 Condenser Water Piping Return Supply Tower Evaporator Condenser Primary Pump(s) Secondary Pump(s) Condenser Pump(s) Chiller Sediment Separator Expansion Tank And Air Separator
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21 Condenser Water w/ Economizer Return Supply Tower Evaporator Condenser Primary Pump(s) Secondary Pump(s) Condenser Pump(s) Head Pressure Control Valve Heat Exchanger Loads Sediment Separator Expansion Tank And Air Separator
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22 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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23 Best Practice Design
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24 Best Practice Design Why Constant speed pump Variable speed pump Optimize Pump Impeller
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Best Practice Design Why ‒ Equipment over-sizing ‒ Cost penalty ‒ Mandate Optimize Pump Impeller
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26 Best Practice Design Constant speed pump Trim the impeller. Utilize the affinity laws. Follow the system curve. Save operating cost. First costs.
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27 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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28 Primary Piping for Hot Water Systems Pump out of a boiler Keep the boiler at the lowest possible pressure Remember NPSH! Boiler 2 P1P2 Boiler 1 Best Practice Design
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29 Primary Piping for Chilled Water Systems Pump into a chiller Largest pressure drops after the pump Chiller Primary Pumps Chiller Best Practice Design
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30 System Bypass Options Return Supply Pump Controller Secondary CS Pump(s) Common Pipe Chiller 2Chiller 1Chiller 3 Best Practice Design
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31 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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32 Effect at minimum VFD speed Below 30% speed: CS, but still VV 120 110 100 90 80 50 40 30 20 10 70 60 0 1020304050 60708090100 0 % Flow Head 100 % Speed 30% Speed Best Practice Design
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33 1000 GPM Pump 1 Variable Speed: 500GPM @ 100 Ft Pump 2 Constant Speed: 500 GPM @ 100 Ft Wrong! Mixing CS and VS Pumps Best Practice Design
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34 Sensor Location Return Supply Pump Controller VFDs ∆P∆P Sensor Chiller 3 Chiller 2Chiller 1 Primary Pumps Secondary Pumps Best Practice Design
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35 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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36 Optimized solution not only for the pumps, but for the total system conditions Uncontrolled (constant volume) curve Constant pressure Proportional pressure Temperature control FLOW ADAPT AUTO ADAPT Best Practice Design
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37 Best Practice Design Q 100%25% H 1. Uncontrolled 2. Constant pressure 3. Proportional pressure (calculated) 4. Proportional pressure (measured) 5. Temperature control 0 20 40 60 80 100 100 80 60 40 20 0 Flow in % Effect in % 1. 2. 3. 4. 5. Get Additional Energy Savings
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38 Best Practice Design - Demand More Total Efficiency vs. Control Modes
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39 Best Practice Design - Demand More Comparison
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Flow Limit 0255075100 FLOW LIMIT Potential saving compared to an unintelligent pump Potential saving compared with proportional pressure mode Duty point Additional saving with FLOW LIMIT Performance curve Intelligent Control – FLOW ADAPT /FLOW LIMIT Best Practice Design - Demand More 40
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41 Best Practice Design - Demand More
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42 UPDATE Q 100%25% H 1.Uncontrolled 2.Constant pressure 3.Proportional pressure (calculated) 4.Proportional pressure (measured) 5.Temperature control 0 20 40 60 80 100 100 80 60 40 20 0 Flow in % Effect in % 1. 2. 3. 4. 5. Best Practice Design – Demand More Intelligent Control - Overview
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43 Best Practice Design - Demand More Drive Motor and Pump Effeciency
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44 100% 80% 70% 60% 50% 25% 90% HRPM 0 Max. curve Control curve Pressure reduction DP1DP3DP4DP2 Control mode Best Practice Design – Demand More Intelligent Control - Pressure Control
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45 100% 80% 70% 60% 50% 25% 90% HRPM 0 Max. curve Control curve Pressure reduction DP1DP3DP4DP2 Control mode Best Practice Design - Demand More Intelligent Control: Calculated Pressure Control
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46 100% 80% 70% 60% 50% 25% 90% HRPM 0 Max. curve Control curve Pressure reduction DP1DP3DP4DP2 Control mode Best Practice Design - Demand More Intelligent Control: Measured Pressure Control
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47 100% 80% 70% 60% 50% 25% 90% HRPM 0 Max. curve Control curve Pressure reduction DP1DP3DP4DP2 Control mode Best Practice Design - Demand More Intelligent Control: Temperature Control
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48 Best Practice Design
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49 Affinity Laws Capacity varies to the ratio of the diameter change Head varies to the ratio of the square of the diameter change Brake horsepower varies to the ratio of the cube of the diameter change Best Practice Design
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50 Affinity Laws Best Practice Design
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51 What Impacts the System Head? Actual component pressure drops Actual piping loses Present vs. future loads Safety Factors Heating vs. cooling flow Best Practice Design
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52 What Happened if......you read a flow rate of 1425 gpm instead of the design 1150 gpm? Best Practice Design
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53 12.1” Impeller Curve Best Practice Design System Curve #1 System Curve #2
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54 Throttle Valve Best Practice Design System Curve #1 System Curve #2
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55 Best Practice Design HP Penalty? HP = Flow x Head x Specific Gravity/3960 x Pump Eff. Throttled Head = Design Head – Measured Head Throttled Head = 138 – 120 = 18 feet Throttled HP = 1150 x 18 x 1/3960 x 0.86 Wasted HP across balance valve? HP = 6.08
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56 Correcting pump over-sizing: Close valve at pump Balance system Trim the impeller VFD Best Practice Design
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57 10”inch Impeller Curve 10.00 in System Curve #1 System Curve #2 Best Practice Design
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58 Best Practice Design True HP Penalty HP = Flow x Head x Specific Gravity/3960 x Pump Eff. Head at actual point of operation = 80 feet Head savings = 138 – 80 = 58 feet, not 18 feet Wasted HP with untrimmed impeller… HP = 1150 x 58 x 1/3960 x 0.82 HP = 20.54! Trim impeller from 12.10” to 10.0”
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59 Operating Cost Pump Motor Best Practice Design
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60 Operating Cost: “Standard Efficiency” Motor = 90.9 BHP = (1150 x 138 x 1.0) / 3960 x 0.86 = 34.47 kW = (34.47 x 0.7457) / 0.909 = 28.28 AOC = 28.28 x 8760 x $0.10/kWh = $24,768 Best Practice Design
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61 Operating Cost: “High Efficiency” Motor = 93.4 BHP = (1150 x 138 x 1.0) / 3960 x 0.86 = 34.47 kW = (34.47 x 0.7457) / 0.934 = 27.52 AOC = 27.52 x 8760 x $0.10/kWh = $24,108 Best Practice Design
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62 Operating Cost Comparison: Motor change out only @ $0.10/kWh Standard Efficiency$24,768 High Efficiency$24,108 Annual Savings$ 660 Best Practice Design
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63 Trim the Impeller to 10”: Flow = 1150 gpm Head = 80 ft Pump efficiency = 0.82 Standard efficiency motor = 87.9 High efficiency motor = 90.3 Best Practice Design
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64 Operating Cost: “Standard Efficiency” Motor = 87.9 BHP = (1150 x 80 x 1.0) / 3960 x 0.82 = 28.33 kW = (28.33 x 0.7457) / 0.879 = 24.04 AOC = 24.04 x 8760 x $0.10/kWh = $21,055 Best Practice Design
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65 Operating Cost: “High Efficiency” Motor = 90.3 BHP = (1150 x 80 x 1.0) / 3960 x 0.82 = 28.33 kW = (28.33 x 0.7457) / 0.903 = 23.39 AOC = 23.39 x 8760 x $0.10/kWh = $20,494 Best Practice Design
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66 Std EffHi EffDifference @138 Ft $24,768 $24,108 $660 @ 80 ft $21,055 $20,494 $561 Difference $ 3,713 $ 3,614 $4,274 Operating Cost Comparison: High Eff. Motor + Trimming Impeller Best Practice Design
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67 Best Practice Design Impeller Trimming True cost to trim impeller Remove and replace impeller Replace seals Replace bearings Downtime Calculate payback
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68 Best Practice Design Maximize impeller to non-overloading motor size. Impeller Trim Curves NOL HP
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