Day 3: Fans and Pumps

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Energy Audit in Building A Regional Training Workshop
1 - 5 June, 2010

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  • Have large running clearances, which is useful for airborne-solids (dust, wood chips and metal scraps) handling services
  • draft: courant d’air
  • kW: Real Power, kVA: Apparent Power
  • IGV: Inlet Guide Vanes VFD: Variable Frequency Drives
  • Hello.
  • Day 3: Fans and Pumps

    1. 1. Fans & Pumps ADNAN JOUNIRCREEE EnERgy Audit in Buildingtunis, 1st – 5th JunE 2010 1
    2. 2. Contents1 General Introduction2 Fans & Blowers3 Pumps & Pumping systems 2
    3. 3. General IntroductionPumps and fans are probablythe devices the most frequentlyused in our lifeBoth are necessary to movematerial and energy 3
    4. 4. General IntroductionIn building sector their usage is essential to secure comfort and welfareEnergy saving concerns 2 levels: • The device itself • The removed energy or material 4
    5. 5. Fans & Blowers Equipment Specific Ratio Pressure rise (mmWg)Comparison Fans up to 1.11 1136 Blowers 1.11to 1.20 1136 –2066 5
    6. 6. ContentsIntroductionTypes of fans and blowersEnergy audit of Fans 6
    7. 7. IntroductionWhat are Fan systems?Any device that produces a current of air by themovement of broad surfaces can be called a fanFans are similar in many respects to pumps. Both are turbo machines that transfer energy to aflowing fluid.It is easy to distinguish between fans and pumps:pumps handle liquids; fans handle gasses.Broadly speaking, the function of a fan is to propel,displace, or move air or gas. 7
    8. 8. IntroductionFan componentsSystem resistanceFan curveOperating pointFan laws 8
    9. 9. IntroductionFan Network Components Turning Vanes (typically used on short radius elbows) Outlet Diffusers Heat Exchanger Baffles Filter Inlet Vanes Motor Controller Variable Frequency Drive Centrifugal Fan Belt Drive Motor 9
    10. 10. Introduction System Resistance: • Sum of static pressure losses in system • Increases with square of flow rateActual withsystemresistancecalculated 10
    11. 11. Introduction Fan Curves 11
    12. 12. Introduction Operating Point Fan curve and system curve intersection Move to flow Q2 by closing Flow Q1 atdamper (increase pressure P1 and system fan speed N1 resistance) Move to flow Q2 by reducing fan speed 12
    13. 13. Introduction Fan Laws Minimizing Energy through Fan selection Fan Affinity Laws Pre. 13
    14. 14. ContentsIntroductionTypes of fans and blowersEnergy Audit of Fans 14
    15. 15. Types of Fans & Blowers Peak Efficiency Type of Fan RangeTypes of fans Centrifugal fans: Airfoil, Backward 79-83 • Centrifugal curved/inclined Modified radial 72-79 • Axial Radial 69-75 Pressure blower 58-68 Forward curved 60-65Types of blowers Axial fans: Vane axial 78-85 • Centrifugal Tube axial 67-72 Propeller 45-50 • Positive displacement 15
    16. 16. Types of Fans & Blowers Centrifugal Fans• Advantages • High pressure and temp • Simple design • High durability • Efficiency up to 75% • Large running clearances• Disadvantages • Suited for low/medium airflow rates only 16
    17. 17. Types of Centrifugal Fans 17
    18. 18. Types of Fans & BlowersExample of Centrifugal FansBackward-inclined• Advantages • Operates with changing static pressure • Suited for high flow and forced draft services • Efficiency >85%• Disadvantages • Not suited for dirty airstreams • Instability and erosion risk 18
    19. 19. Types of Fans & Blowers Axial Fans• Work like airplane propeller: • Blades create aerodynamic lift • Air is pressurized • Air moves along fan axis• Popular : compact, low cost and light weight• Applications • Ventilation (requires reverse airflow) • Exhausts (dust, smoke, steam) 19
    20. 20. Types of Fans & Blowers Example of Axial Fans – Tube axial fans• Advantages • Pressures to overcome duct losses • Suited for medium-pressure, high airflow rates • Quick acceleration• Disadvantages • Expensive • Moderate noise • Low energy efficiency 65% 20
    21. 21. Types of Fans & Blowers Blowers • Difference with fans • Much higher pressures <1.20 kg/cm2 • Used to produce negative pressures for industrial vacuum systems • Types • Centrifugal blower • Positive displacement 21
    22. 22. ContentsIntroductionTypes of fans and blowersEnergy Audit of Fans 22
    23. 23. Energy Audit of FansIntroduction Example for the distribution of cost over the life cycle of fansFans are themain consumer Maintenance Capital (5%)for auxiliary 8%)SystemsIn Most situationsthe potential ofEnergy Saving is Energymore than 30% (87%) 23
    24. 24. Energy Audit of FansSteps Involved Data collection Observations and Analysis Exploration for energy conservation measures Report preparation 24
    25. 25. Energy Audit of Fans Data CollectionCollect detailed design specification & operatingparameters: Make, Type, Model, Fluid characteristics,Rated Flow, Inlet pressure, Efficiency, motorcharacteristics, Regulation systems, Collect Details of the fans and ducting system: Collect the schematic diagram / network of the ducting system Collect Performance characteristics of all fans Compile design, previous best and last energy audit values withrespect to fans and draft system If the fans are operated in parallel then it is advised to collect theperformance curve for the parallel operation Air quality and pressure equipments at the users as per the designrequirements 25
    26. 26. Energy Audit of Fans Instruments RequiredPower Analyzer: Used for measuring electrical parameters suchas kW, kVA, pf, V, A and HzTemperature Indicator & ProbeStroboscope: To measure the speed of the driven equipmentand motorSling hygrometer or digital hygrometerAnemometer, Pitot tubesOn line instruments – (calibrated)Digital Manometer of suitable range and appropriate probes formeasurement of pressure head and velocity head.Additional pressure gauges with appropriate range ofmeasurement and calibrated before audit. 26
    27. 27. Energy Audit of FansMeasurements & observations to be made Energy consumption pattern of fans Motor electrical parameters (kW, kVA, Pf, A, V, Hz,) of fans Fan operating parameters to be measured/monitored for each Fan are: 1. Discharge flow rate 2. Pressure (suction & discharge) 27
    28. 28. Energy Audit of FansMeasurements & observations to be made3. Damper position / guide vane position/ VSD Setting4. Temperature of fluid handled5. Load variation6. Fan operating hours and operating schedule7. Pressure drop in the system8. Pressure drop and temperature variation across the equipment9. Fan /Motor speed Oxygen content, flow, temperature and pressure measurement across in exhaust gas path 28
    29. 29. Energy Audit of Fans Energy consumption patternIf the plant is monitoring the energy consumption, itis suggested to record the data and monitor the dailyand monthly consumption pattern. (Collect data for 12months) Work out the total consumption of fans to arrive atpercentage to the total consumption of the auxiliaryconsumption If the energy meters are not installed to fans,instantaneous measurements can be carried out,based on the loading pattern daily consumption canbe worked out. 29
    30. 30. Energy Audit of Fans Fan Operating Efficiency EvaluationThe parameters to be studied in detailed are: Air /gas rates of fans / main ducts Static pressure and dynamic pressure and totalpressure Power consumption of fan (for estimating theoperating efficiency of the fans) Monitor present flow control system and frequency ofcontrol valve operation if any (for application of variablespeed drives) 30
    31. 31. Energy Audit of Fans Fans Performance assessment• Static pressure – Potential energy put into the system by the fan• Velocity pressure – Pressure arising from air flowing through the duct. This is used to calculate velocity• Total pressure – Static pressure + velocity pressure – Total pressure remains constant unlike static and velocity pressure 31
    32. 32. 32
    33. 33. 33
    34. 34. Energy Audit of Fans Fan Operating Efficiency EvaluationFan static kW = Q in m3/ s x static pr. developed by fan in mmwc 102 Fan static kW x 100Fan static efficiency % = Input kW to motor x ηmFan mechanical Efficiency % = Fan total kW x 100 Input kW to motor x ηm Parameter Details Unit Q Air flow rate m3/ s Static pressure Difference between discharge & suction pressure mmwc Fan static/ total kW Static / total power consumption of the fan kW Input kW to motor Measured power consumption of the motor kW ηm Efficiency of the motor at operating load Total pressure Difference between discharge & suction pressure mmwc 34
    35. 35. Energy Audit of Fans Fan Operating Efficiency Evaluation 273 X 1.293Corrected air density, γ = 273 + Air temperature in 0 C Cp x √2 x 9.81 x Diff. velocity pr. in mmwc x γVelocity in m / s = γ Parameter Details Unit Cp Pitot tube constant 0.85 or as given by manufacturer γ Density of air or gas at test condition Kg / m3 Volumetric flow (Q), m3/s = Velocity, m/s x Area, m2 35
    36. 36. Energy Audit of Fans Fan Performance AnalysisCompare the actual values with the design / performance test values ifany deviation is found, list the factors with the details andsuggestions to over come. The investigations for abnormality are to be carried out forproblems. Enlist scope of improvement with extensive physical checks /observations. Based on the actual operating parameters, enlist recommendationsfor action to be taken for improvement, if applicable such as-Replacement of fans, Impeller replacement, VFD application.Cost analysis with savings potential for taking improvementmeasures. 36
    37. 37. Energy Audit of FansFan Performance Analysis Recirculation Damper 100P IGVo 75 Inlet Guide Vaneswe 50r VFD 25 Variable Frequency Drive Ideal 25 50 75 100 Flow 37
    38. 38. Energy Audit of Fans Fan Performance AnalysisSystem characteristics and Fan curves Impact of speed reduction 38
    39. 39. Energy Audit of Fans Fan Performance AnalysisVisual survey of insulation & the ducting system: Insulation status (measure the surface temperature with theaid of surface thermocouple / infrared pyrometer or by usingthermal imaging cameras) Bends and ducting status Physical condition of insulation Identification of locations where action is required toimprove the insulation (provide with detailed techno-economics) Improvement options for ducting systems if any 39
    40. 40. Energy Audit of FansExploration of Energy Conservation OpportunitiesImprovement of systems and drives: Use of energy efficient fans Change of impeller with energy efficient impeller Correcting inaccuracies of the fan sizing Use of high efficiency motors Fan speed reduction by pulley diameter modifications for optimization Option of two speed motors or variable speed drives for variable dutyconditions High Performance Lubricants: The low temperature fluidity and hightemperature stability of high performance lubricants can increase energyefficiency by reducing frictional losses Use of energy efficient transmission systems (Use of latest energy 40efficient transmission belts)
    41. 41. Energy Audit of FansExploration of Energy Conservation Opportunities Improvement in operations:  Minimizing excess air level in combustion systems to reduce fan load.  Minimizing air in-leaks in hot or cold flue gas path to reduce fan load  Minimizing system resistance and pressure drops  improvements in duct system / Insulation aspects Measures to up keep the performance After the identification of energy conservation measures, detailed techno-economic evaluation has to be carried out 41
    42. 42. Energy Audit of Fans Case StudyA fan is used to draw air through a bag filter. 􀂃 Flow rate is 90 m3/s at a static pressure of 80 mm water column(WC) 􀂃 65 mm WC is the static pressure across the bag filter 􀂃 Motor power drawn is 120 kW 􀂃 Motor efficiency is 86% 􀂃 Impeller diameter is 70 mm 􀂃 RPM is 1000After consultation we decided to replace the bag filter with anelectrostatic precipitator (ESP). 􀂃 Static pressure across the ESP is 20 mm WC 􀂃 Flow rate increased by 20% 􀂃 The flow rate can be brought back to 90 m3/s by two options: (a)Impeller trimming and (b) Reduced pulley diameter to reduce the RPM 42
    43. 43. Energy Audit of Fans Case Study We must Calculate the following: 1. Fan static efficiency before installation of the ESP 2. The new impeller diameter if the impeller is trimmed, that would result in a reduction in fan efficiency of 5% 3. The new RPM that would result in a fan efficiency of 60% 4. Which of the two options is more energy efficient 43
    44. 44. Energy Audit of FansCase Study1. Fan static efficiency before installation of the ESPPower input at fan shaft = 120 x 0.86 = 103.2 kWFan efficiency = 90 x 80/(102 x 103.2) = 68 %2 New impeller diameter if the impeller is trimmedNew fan static efficiency = 68% - 5% = 63%New static = 80 – 65 + 20 = 35 mm WCNew flow rate Q = 90 m3/s x 1.2 = 108 m3/sStatic pressure at a flow of 90 m3/s with ESP installedQ1 / Q2 = (H1/H2)2 result H2 = 32 mmPower required at the fan shaftFan static efficiency: 0.63 = (90 x 32) / (102 x power)Power developed at fan shaft = 44.8 kW New impeller diameter (D2) 44 (D1 / D2) = (kW1 / kW2) 1/ 3 result D2 = 53 mm
    45. 45. Energy Audit of Fans Case Study3. Calculate the new RPM that would result in a fan efficiencyof 60%Power required at fan shaft0.60 = 90 x 32 / 102 x Power required at fan shaftPower required at fan shaft = 47 kWNew RPM (N2): (N1 / N2) = (kW1 / kW2) 1/ 3N2 = 769 RPM4. Determine which of the two options is more energy efficientPower required by impeller trimming = 44.8 kWPower required by reducing RPM = 47 kWTherefore impeller trimming is the more energy efficient option. 45
    46. 46. Pumps 46
    47. 47. ContentsIntroductionType of pumpsEnergy Audit of Pumps 47
    48. 48. Introduction What are Pumping Systems• 20% of world’s electrical energy demand• Used for • Domestic, commercial, industrial and agricultural services • Municipal water and wastewater services 48
    49. 49. Introduction What are Pumping Systems Objective of pumping system• Transfer liquid from source to destination• Circulate liquid around a system 49
    50. 50. IntroductionWhat are Pumping Systems• Main pump components • Pumps • Prime movers: electric motors, diesel engines, air system • Piping to carry fluid • Valves to control flow in system • Other fittings, control, instrumentation• End-use equipment • Heat exchangers, tanks, hydraulic machines 50
    51. 51. Introduction Pumping System Characteristics• Head • Resistance of the system • Two types: static and friction• Static head • Difference in height between source and destination • Independent of flow • Static head at certain pressure Head (m) = Pressure (Pa) 1000xSpecific gravity 51
    52. 52. Introduction Pumping System Characteristics In most cases: Total head = Static head + friction head• Friction head • Resistance in pipe and fittings System curve • Depends on size, pipes, pipe System fittings, flow rate, nature of liquid head Friction head • Proportional to square of flow rate Static head Flow 52
    53. 53. Introduction Pumping System Characteristics Pump performance curve Relationship between head andPump operating point flow Pump performance curve • Duty point: rate of flow at certain head Pump operating • Pump operating Head System point curve point: intersection of pump curve and Static system curve head Flow 53
    54. 54. IntroductionPumping System CharacteristicsPump suction performance• Cavitation or vaporization: bubbles inside pump• If vapor bubbles collapse • Erosion of vane surfaces • Increased noise and vibration • Choking of impeller passages• Net Positive Suction Head (NPSH) • NPSH Available: how much pump suction exceeds liquid vapor pressure • NPSH Required: pump suction needed to avoid cavitation 54
    55. 55. IntroductionPumping System Characteristic curves 55
    56. 56. IntroductionPumping System Characteristics Pumps in parallel: Curves 56
    57. 57. Contents: PumpsIntroductionType of pumpsEnergy Audit of Pumps 57
    58. 58. Type of Pumps Pump ClassificationClassified by operating principle Pumps Others (e.g. Positive Dynamic Impulse, Buoyancy) Displacement Centrifugal Special effect Rotary Reciprocating Internal External Slide Lobe gear gear vane 58
    59. 59. Type of PumpsPositive Displacement Pumps• For each pump revolution • Fixed amount of liquid taken from one end • Positively discharged at other end• If pipe blocked • Pressure rises • Can damage pump• Used for pumping fluids other than water 59
    60. 60. Type of PumpsDynamic pumps• Mode of operation • Rotating impeller converts kinetic energy into pressure or velocity to pump the fluid• Two types • Centrifugal pumps: pumping water in industry – 75% of pumps installed • Special effect pumps: specialized conditions 60
    61. 61. Type of Pumps Centrifugal PumpsHow do they work? • Liquid forced into impeller • Vanes pass kinetic energy to liquid: liquid rotates and leaves impeller • Volute casing converts kinetic energy into pressure energy 61
    62. 62. Type of Pumps Centrifugal PumpsImpeller • Main rotating part that provides centrifugal acceleration to the fluid • Number of impellers = number of pump stages • Impeller classification: direction of flow, suction type and shape/mechanical constructionShaft • Transfers torque from motor to impeller during pump start up and operation 62
    63. 63. Impellers 63
    64. 64. Contents: PumpsIntroductionType of pumpsEnergy Audit of Pumps 64
    65. 65. Energy Audit of Pumps IntroductionExample for the distributionof cost over the life cycle of a Maintenance Capitalwater-based pump system. (5%) 10%) In Most situations the potential of Energy Saving is Energy more than 30% (85%) 65
    66. 66. Energy Audit of PumpsSteps Involved Data collection Observations and Analysis Exploration for energy conservation measures Report preparation 66
    67. 67. Energy Audit of Pumps Data CollectionCollect detailed design specification & operatingparameters: Make, Type, Model, Fluidcharacteristics, Rated Flow, Inlet pressure,Efficiency, motor characteristics, RegulationsystemsCollect the above information for all pumps in thewater circuitCollect the Performance Characteristics curves ofall pumps 67
    68. 68. Energy Audit of Pumps Data CollectionCompile design, previous best and last energy audit valuesof the pumping system being audited If the pumps are operated in parallel, then it is advised tocollect the performance curves for the parallel operation of thepumps Schematic diagram of Water pumping network (whichdepict the source, pumps in operation & stand by, line sizesand users) Water and pressure equipments at the users as per thedesign requirements Brief description of the system, in which pumps are used 68
    69. 69. Energy Audit of PumpsInstruments Required Power Analyzer: Used for measuring electricalparameters such as kW, kVA, pf, V, A and Hz Temperature Indicator & Probe Pressure Gauge: To measure operating pressure andpressure drop in the system Stroboscope: To measure the speed of the drivenequipment and motor Ultra sonic flow meter or online flow meter The above instruments can be used in addition to thecalibrated online / plant instruments 69
    70. 70. Energy Audit of Pumps Parameters to be measured Energy consumption pattern of pumps (daily / monthly/yearly consumption) Motor electrical parameters (kW, kVA, Pf, A, V, Hz) forindividual pumps Pump operating parameters to be monitored for each pumpDischarge Flow, Head (suction & discharge), Valve position, Temperature, Load variation, Simultaneous powerparameters of pumps, Pumps operating hours and operatingschedule, Pressure drop in the system (between dischargeand user point), Pressure drop and temperatures across theusers (heat exchangers, condensers, etc), Pump /Motorspeed, Actual discharge pressure and required / prevailingpressure at the user end, User area pressure of operation and 70
    71. 71. Energy Audit of Pumps Observations & Measurements Operating efficiency and performance evaluation of pumps Flow distribution System Details: Detailed interactions (plant personnel) have tobe carried out to get familiarization for system detail andoperational details. The brief system should be briefed in thereport Energy consumption Pattern: If the plant is monitoring theenergy consumption, it is suggested to record the data andmonitor the daily and monthly consumption pattern Collect the past energy consumption data (month wise for atleast 12 months, daily consumption for about a week for differentseasons, daily Consumption during the audit period) 71
    72. 72. Energy Audit of PumpsEfficiency & Performance Evaluation of the Pumps Performance parameters for water pumps 72
    73. 73. Energy Audit of PumpsEfficiency & Performance Evaluation of the Pumps Performance parameters for water pumps contd.. 73
    74. 74. Energy Audit of Pumps Efficiency & Performance Evaluation of the PumpsPump hydraulic power can be calculated by the formula: Q x Total Head, (hd – hs) x ρ x g Hydraulic kW = 1000 Parameter Details Unit Q Water flow rate m3/s Total head Difference between discharge head, hd & suction head, hs m ρ Density of water or fluid being pumped Kg/m3 g Acceleration due to gravity m2/s Hydraulic power Pump efficiency, ηPump = Pump shaft power Pump shaft power = Hydraulic power x η Motor 74
    75. 75. Energy Audit of PumpsEfficiency & Performance Evaluation of the Pumps 75
    76. 76. Energy Audit of PumpsEnergy Conservation Opportunities Compare the actual values with the design / performance test values ifany deviation is found, list the factors with the details and suggestions toover come. Compare the specific energy consumption with the best achievablevalue (considering the different alternatives). Investigations to be carriedout for problematic areas.. Enlist scope of improvement with extensive physical checks /observations. Based on the actual operating parameters, enlistrecommendations for action to be taken for improvement, if applicablesuch as: Replacement of pumps Impeller replacement Impeller trimming Variable speed drive application, etc 76
    77. 77. Energy Audit of PumpsEnergy Conservation OpportunitiesAvoiding Over sizing of Pump Pump Curve at Const. Speed Pump Efficiency 77% 70 m Partially B Oversize Pump 82% closed valve A 50 m Full open valve 42 m System Curves C Required Pump Head Meters Static Operating Points Head 300 500 Flow (m3/hr) 77
    78. 78. Energy Audit of PumpsEnergy Conservation OpportunitiesAvoiding Over sizing of Pump by impellertrimming 28.6 kW 14.8 kW 78
    79. 79. Energy Audit of PumpsEnergy Conservation Opportunities Provision of variable speed drive 79
    80. 80. Energy Audit of Pumps Energy Conservation Opportunities Improvement of systems and drives. Use of energy efficient pumps Replacement of inefficient pumps Trimming of impellers Correcting inaccuracies of the Pump sizing Use of high efficiency motors Integration of variable speed drives into pumps High Performance Lubricants: lubricants can increase energy efficiencyby reducing frictional losses. Booster pump application Centralization/ decentralization Categorizing according to the pressure requirement 80
    81. 81. Energy Audit of PumpsCase StudyIn a commercial Building a clear water Pump has: Parameter Design Operating Flow Q (m³/h) 800 550 Head H (m WC) 55 24 (after delivery valve) Power P (kW) 160 124 RPM 1485 1485Water flow rate varies from 500 m³/h to 700 m³/h.Pump flow rate has been reduced by partially 81closing the delivery valve. Motor efficiency is
    82. 82. Energy Audit of PumpsCase Study1. Calculate the operating efficiency2. Explain what would be the best option to obtain the required flow rate variation3. Calculate the power savings if the options suggested under question 2 would reduce the flow rate of the pump is 550 m³/h 82
    83. 83. Energy Audit of PumpsCase StudySOLUTION1. Calculate the operating efficiencyEfficiency of the pump = (550 x 24 x 9.81) / (3600 x124 x 0.93)= 0.3867 = 38.67%2. Explain what would be the best solutionThe pump is operating at a poor efficiency of38.67% due to throttling of the flow. Since the pumpdischarge requirement varies from 500 m³/h to 700m³/h, the ideal option would be to operate with avariable speed drive (VSD). 83
    84. 84. Energy Audit of PumpsCase Study3. Calculate the power savingsAccording to affinity laws: 􀂃 Relationship Q and RPM: Q1/Q2 = N1/N2 􀂃 Relationship H and RPM: H1/H2 = (N1/N2)2 􀂃 Relationship P and RPM: P1/P2 = (N1/N2)3For a flow rate Q1 = 550 m³/h, the reduced speedof pump (N1 in RPM) would be: N1 = 1021 RPMPower would be P1 = 52 kWPower saving = 124 kW - 52 kW = 72 kW 84
    85. 85. Energy Audit of Pumps Good PracticesGP1:•A waste-fuelled heating plant fed two networkswhich supply an industrial area and a residentialarea.•An analysis of the pumps used to supplynetworks showed that the pumps were all runcontinuously at high power, although thepumping power required was often very low. 85
    86. 86. Energy Audit of Pumps Good PracticesSystem optimisation measures:Complete separation of the pumps from the mains supplywhen they are switched offReplacement of existing pumps with smaller, highlyefficient pumpsUse of variable speed drive for operation at adjustablespeedsInstallation of high efficiency motorsInstallation of the new pumps and variable speed drive 86
    87. 87. Energy Audit of Pumps Good PracticesEnergy savings and efficiencyparameters•Electricity savings: 64 % or 325,000 kWh p.a.•Cost savings: € 32,500 p.a.•Investment: € 67,000•Payback period: 2.1 years•Return on investment: 48 % 87
    88. 88. Energy Audit of Pumps Good PracticesGP2:•A combined heat and power plant provides a district(houses, hospitals, welfare and handicapped facilities,commercial kitchen and a laundry ) heat via a districtheating network.•The energy audit focused on the optimization of themain district heating pumps in the power supply centre.The analysis showed considerable potential to optimizethe pump control system, which until now has beenregulated by hand. 88
    89. 89. Energy Audit of Pumps Good PracticesSystems optimisation measures:•Hydraulic alignment of the district heating network•Installation of a proportional control system for thepumps•Use of variable speed drive for operation atadjustable speeds•Replacement of the two network pumps•Use of high efficiency motors 89
    90. 90. Energy Audit of Pumps Good PracticesEnergy savings and efficiencyparameters•Electricity savings: 39 % or 129,000 kWh p.a.•Cost savings: € 14,100 p.a.•Investment: € 41,700•Payback period: 3 years•Return on investment: 31 % 90
    91. 91. THANK YOU FORYOUR ATTENTION 91

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