Important! This session is approved for 0.2 IACET or 1.5 PDH. Many states accept this for Professional Continuing Education. To qualify for credit you must: Be sure your badge was scanned when you entered the workshop Stay for the entire session Participate in Question and Answer sessions Fill out the Evaluation auato Form and hand it to the epocto proctor as you leave e If you are registered in Florida, New York, or North Carolina, you must also sign the sheets in the back at the end of the session. Please print your name, include your registration number, and sign the sheet. TITLE GOES HERE TITLE GOES HERE TITLE GOES HERE TITLE GOES HERE TITLE GOES HERE 1
Review of Practices in the District i t Cooling Systems and Pumping Schemes to Manage the Impact on Energy Burj Khalifa Case Study Ahmed Abdul Ganhi Chairman Allied Consultants Cairo, Egypt 2 Learning Objectives 1. Understand distribution systems reliability 2. Determine distribution system energyrunningrunning cost 3. Understand new Middle East techniques in District cooling 3 2
United Arab Emirates 4 Dubai 5 3
Burj Khalifa 6 Burj Khalifa 7 4
Burj Khalifa 8 Burj Khalifa 9 5
2012 GEC Ghani Workshop 3/23/2012 Master Plan DCP 1 ASHRAE check Figure 215 Sq.ft/TR Connected Load 45,700 TR Diversity Factor 94 % Plant load DCP 1 DCP 4 DCP 4 43,000 TR ASHRAE check Figure DCP 3 ASHRAE check Figure 80,700 TR Diversity Factor 74 % Plant load 59,500 TR Diversity Factor 67 % 40,000 TR DCP 2 g ASHRAE check Figure 60,000 TR DCP 3 215 Sq.ft/TR Connected Load Plant load 215 Sq.ft/TR Connected Load DCP 4 215 Sq.ft/TR Connected load 51,300 TR Diversity Factor 68 % Plant load 35,000 TR DCP 2 10 Master Plan DCP 1 DCP 3 DCP 4 DCP 2 11 6
Interface with Building Direct Connection Indirect Connection 12 Direct Connection Advantages More economical no HE (~ 100 $/T exchanger + accessories). No water treatment at user side. Reduced ETS space (xxxxxxx Sq. ft /TR). Increased ΔT thus reduced distribution system capital cost. Rd Reduced dequipment maintenance and potential shutdowns for HE cleaning. Disadvantages Building design pressure should be same as the DCS which could add cost to the end user. Cross contamination that could affect both systems. Building specific water treatment may not be met as treatment at central plant. Plant & network design pressure might be affected by end user. 13 7
Direct Connection Decision taken ETS for all users except for Mall (direct connection) owned by the Energy Provider. Burj indirect due to static impact. Pipes Pre insulated with HDPE Jackets Leak detectors 14 Pumping Scheme Primary Secondary 15 8
Pumping Scheme Primary Distributed Secondary 16 Case Study Primary Secondary vs. Primary Distributed Secondary 1) Primary Secondary 17 9
Case Study 2) Distributed Secondary 18 Pressure Gradient Diagram 1) Primary-Secondary System Pressure Gradient PRESSURE GRADIENT PRIMARY-SECONDARY SYSTEM 200.000 175.000 MAX PRESSURE: 834PSI 83.4 150.000 SYSTEM HEAD (ft) 125.000 100.000 75.000 Supply Line Return Line 50.000 25.000 0.000 Point 0 VB-01 Plot - A Plot - B Plot - C Plot - D Plot - E VB-2 STATIONS Plot - F Plot - G Plot - H Plot - J Plot - K K------HEX 19 10
Pressure Gradient Diagram 2) Primary-Distributed Secondary Pressure Gradient 200.000 PRESSURE GRADIENT PRIMARY-DISTRIBUTED SYSTEM 175.000 150.000 MAX PRESSURE: 49.5 PSI SYSTEM HEAD (ft) 125.000 100.000 75.000 Supply Line Return Line Pressure at Each Station 50.000 25.000 0.000 Point 0 - PP-S VB-01 Plot - A Plot - B Plot - C Plot - D Plot - E STATIONS VB-2 Plot - F Plot - G Plot - H Plot - J Plot - K Observe Pump Head Max System Pressure 20 Energy Curve of Both 800000.00 YEARLY POWER CONSUMPTION PRIMARY-DISTRIBUTED VERSUS PRIMARY SECONDARY 700000.00 POWER CONSUMPTION (KW) P 600000.00 500000.00 400000.00 300000.00 200000.00 Primary Secondary Distributed Secondary 100000.00 0.00 1 2 3 4 5 6 7 8 9 10 11 12 MONTHS 21 11
Energy Saving Table System Primary Secondary Primary Distributed Secondary Months (KW) (KW) January 114830.54 55911.45 February 145975.33 71075.98 March 306453.67 149213.53 April 359681.81 175130.52 May 494584.78 240815.33 June 629377.48 306446.44 July 666851.04 324692.46 August 659807.36 321262.87 September 543639.12 264700.08 October 404525.63 196965.16 November 248761.68 121123.06 December 155666.54 75794.67 TOTAL (MW) 4730.15 2303.13 22 Advantages of Selected Pumping Scheme No ΔP control valve required. Distributed pumps handle the pressure variations. Chilled water can be obtained from any plant. 23 12
Advantages of Selected Pumping Scheme Any supply temperature could be achieved by direct mixing as return pressure higher than supply 24 DCP Configuration DCP 2 Convention Plant Capacity 35,000 TR DCP 1 Ice Storage Capacity 40,000 TR 25 13
DCP 2 What are chillers arrangement configurations? 1) Parallel Arrangement 26 DCP 2 2) In-Series Arrangement Series chillers have better kw/ton. Single path chiller with lower ΔP across evaporator. Both chillers in series have higher primary pump head. 27 14
What Happens if Secondary is not Matching Primary? Fig-1: Series Arrangement 28 What Happens if Secondary is not Matching Primary? Fig-2: Parallel Arrangement 29 15
Load Profile has to be Analyzed Loading % in each arrangement should be computed LOADING PERCENTAGE COMPARISON 100.00 90.00 80.00 LOA ADING PERCENTAGE 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 HOURS Series Arrangement Parallel Arrangement 30 Load Profile has to be Analyzed Hour by hour energy needs to be computed Fig-1 Inseries Arrangement 31 16
Load Profile has to be Analyzed Fig-1 Parallel Arrangement 32 Buffer Tank (TES) May Improve the chiller KW/ton as the chillers will be loaded at all their best efficiency time, but no space 33 17
Buffer Tank (TES) Advantages Reduced compressor lift. Disadvantages Increased chilled water pump head (two in series evaporators). Increased condenser pump head (two in series condensers). Increased bypassed energy through decoupler. Conclusion Analyze series/parallel arrangement with load profile and chiller loadingpercentage include pumping energy in primaryandand condenser circuits. Net results. Shows saving if chiller staging is properly watched. 34 Chiller Arrangement of DCP 2 Series counter flow configuration Number of chillers original design = (2 x 2500) x 7 modules Number of chillers used (2 x 1250) x 14 modules Increased number of chillers staging Reduced wastage of energy through decouple 35 18
Cooling Tower Types Counter Flow Cross Flow Induced draft counter-flow tower Induced draft cross-flow tower 36 Advantages of Counter Flow Easier to maintain as water basin not restricted by wet deck. Less space needed because of increased efficiency and lack of plenum space required for cross flow towers. Longer service life as deck supported from structural supports underneath. No sagging as cross flow. Wet deck is encased on all sides with no impact from direct prevailing wind. No hot water basin on top of tower, so less and easy maintenance achieved. Taller in height that meanless prone to recirculation effect. When towers are laid side by side, towers still accessible. Less pumping energy as no spray nozzles pressure. 37 19
arge V d Plume 2012 GEC Ghani Workshop 3/23/2012 Orientation with Wind Direction Disch Wind Vw Vp Effect of wind velocity and discharge velocity on plume behavior Recirculation potential in a forced draft cooling tower Comparative recirculation potential of round and rectangular towers 38 Orientation with Wind Direction Proper orientation of towers in a prevailing longitudinal wind (requires relative minimal tower size adjustment to compensate for recirculation and interference effects) 39 20
For Wet Coolers where: Humidity is expressed in absolute units of moisture content, for example, grains of moisture per pound of air. 40 For Wet Coolers Recirculation impacts design wet bulb temp CFD Modeling Conducted to validate tower performance at prevailing wind speed. Capacity Heat rejection Chiller motor cooling Safety Design wet bulb temp. considering recirculation Pump NPSH NPSH A > NPSH R H s + H a H f H v > NPSH R Found safe Other tools to overcome NPSH issues 41 21
For Wet Coolers Sand storm & development construction activity dust Cooling tower dirt removal Sweeper systems Side stream filtration Ozone Issues & concerns of ozone Corrosion of steel parts (chiller marine box) 42 Other Points Considered Network air venting & dirt removal Impact of air on pump p 43 22
Other Points Considered Gas venting (oxygen + nitrogen) Source Air dissolved in make up water: used up by the initial corrosion. Air trapped in the system after initial filling: proper air venting Large bore vent to pass air bubble Surface tension breaker 44 Other Points Considered Diffusion: Expansion Tanks Expansion tank with a bag Expansion tank with a membrane Air ingress due to negative pressure: expansion tank pressure should be maintained. 45 23
Other Points Considered Air vents (1.64 ft/s) Air & dirt separators Water speed versus removal time ascending flow (3.28 ft/s) (2.46 ft/s) (1.64 ft/s) Water speed versus removal time horizontal pipe 46 Other Points Considered Baffle Separator Centrifugal Separator Wire Mesh Separator 47 24
Plant Configuration Plant Arch Configuration Plant foot print 200 x 200 ft (60 x 60 mt) Chillers foot print 0.75 Sq. ft/t (0.07 Sq.m/T) Heat rejection required area 0.43 Sq.ft/T (0.04 Sq.m/T) Electrical work required area 0.54 Sq.ft/T (0.05 05 Sq.m/T) Pumps require area 0.32 Sq. ft/t (0.03 Sq.m/T) 48 Plant Configuration Basement: Ground: Mezzanine: Roof: Pumps + water tank Height 7 mt Chiller Hall + Electrical + Expansion Height 9 mt Crane Offices + Control Room Isolation from structure via vibration matt. Cooling Tower 49 25
DCP 2 Plant Section 50 DCP 2 Photo 51 26
District Cooling Plant 1 First large size district plant with Ice storage Capacity 43000 TR Foot print 200 x 200 ft (60 x 60 m) Piles completed with no basement Challenges Foot print notadequate for heat rejection equipment (200 x 200 ft) No basement available No space for chillers at ground floor 52 District Cooling Plant 1 Mall design Temp differs from Burj ΔT16 o F ( 8.8 o C) Supply 42 o F(5.5 o C) Temp Challenge due to 5 stages with cascaded ETS 56 o F 37 o F 53 27
District Cooling Plant 1 Solution Thermal storage No sufficient land for chilled storage 03 0.3 06m 0.6 3 /Thr Low temp below 39.4 o F so chilled storage not possible due to density change. Ice storage technique 0.07 0.08 m 3 /Thr Tank on ground and up to 1st floor As tank occupied the ground, chillers moved to 1st floor Electric platform elevator 40 T on capacity (4.5 M US $) 54 District Cooling Plant 1 Condenser pump on 1st floor NPSH A not sufficient Proposed NPSH diffuser CT on roof elevated dby 2 mt 55 28
District Cooling Plant 1 Low Supply Temp Chillers Load achieved through: Low temp chillers as base load to operate at 37 o F (20,000 TR ). Glycol chillers to produce ice and operate at peak load via glycol heat exchangers (15,000 TR). Heat exchangers between tank water and chilled water (7,000 TR ). 56 District Cooling Plant 1 Ice Storage Discharging Mode Glycol Chillers Ice Storage Glycol Chillers Chilling Mode Base Load Chillers The Peak Day Load Profile External Melt Ice-On-Coil 57 29
Flow Diagram 58 DCP 1 Plant Section 59 30
DCP 1 Plant Section Challenges Dirt impact on glycol chiller tube heat transfer. Manualcleaning is required to maintain capacity. Automatic tube cleaning was used with brushes + diverting valve + controller to clean tubes 4 times /Day. 60 DCP 1 Plant Section ATB System Valve Automatically reverses flow for 30 sec every six hours ATB System Control 61 31
DCP 1 Plant Section 62 DCP 1 Plant Section 63 32
REMEMBER TO FILL OUT AND TURN IN THE EVALUATION FORM Reminder: If you are registered in Florida, New York, or North Carolina, you must also sign the sheets in the back at the end of the session. Please print your name, include your registration number, and sign the sheet. 64 33