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`Patron: Cook, Virginia Rose
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`Journal Title: Official proceedings ... annual
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`conference of the International District
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`Energy Association.
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`.D ~ Volume: 89 Issue:
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`Month/Year: 1998Pages: 85-97
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`~ ~I District Cooling and Combustion Turbine
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`Article Author:
`
`Article Title: Clark, Kenneth M., Ebeling,
`Jerry A., and Godwin, Edward; The
`Application of Thermal Energy Storage for
`
`Inlet
`
`Imprint: Washington, D.C. ; International
`Distric
`
`11111 i~lmüiliill1ü&ilil1ll1111
`
`12/2/20133:36 PM
`(Please update within 24 hours)
`
`Call #: TH7201 .N3
`
`Location: stk
`
`Scan
`(~harge
`Maxcost: 25.001FM
`
`Shipping Address:
`Oregon State University Library
`121 The Valley Library---ILL
`Cross Streets Jefferson Way & Waldo PI
`Corvallis, OR 97331-4501
`
`Fax: 541-737-1328
`Arie'l: bSU;ILL..IiQcary.orst.e<Ju
`Email: OSU-ILLlibrary.orst.edu
`Odyssey: 128.193.169.23
`
`Note: RAPID Unmediated Location:
`FOUND
`
`PAGE 1 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`THE APPLICATION OF THERMAL ENERGY STORAGE
`FOR DISTRICT COOLING AND COMBUSTION TURBINE INLET AIR COOLING
`
`Kenneth M. Clark, P.E.
`and
`Jerry A. Ebeling, P.E.
`Bums & McDonnell Engineering Company
`Kansas City, Missouri
`and
`Edward Godwin, P .E.
`Reedy Creek Energy Services
`Lake Buena Vista, Florida
`
`ABSTRACT
`
`The use of thermal energy storage is a proven and accepted technology for both district cooling
`and combustion turbine inlet air cooling. However, the two applications may never have been
`previously combined in a single project. Reedy Creek Improvement District is realizing the
`synergies available from this combination with their chilled water thermal storage project. This
`paper will discuss the modifications of an existing 20,000 ton district chilled water cooling
`system and 38 MWe combined cycle power plant to incorporate a chilled water thermal energy
`storage system for both comfort air-conditioning and gas turbine inlet air cooling. These
`modifications provide improvements to production, reliability, and economic performance. The
`conceptual and final design process will also be presented.
`
`KEYWORDS: Thermal Energy Storage, Turbine-Inlet Cooling, Chilled Water
`
`INTRODUCTION
`
`Reedy Creek Improvement District (RCID) is a municipal entity that services the utility needs of
`the Walt Disney Company in Florida. The RCID owns several utility systems including electric,
`gas, chilled water, hot water, potable water, and sanitary sewer. The RCID Central Energy Plant
`serves the various needs ofthe Walt Disney World Resort. Reedy Creek Energy Services
`(RCES) is a private corporation providing design, build, operation and maintenance contract
`services to RCID for its utility systems.
`
`RCID and RCES recently modified the RCID Central Energy Plant. The modifications include
`the addition of a new chilled water thermal storage system and a new combustion turbine inlet air
`cooling system. The project also includes the addition of a new carbon monoxide (CO) catalyst
`
`85
`
`PAGE 2 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
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`MAGIe KINGDOM
`
`,.' =2000 '
`SCALE =
`2000'
`I
`I
`GRAPHIC SCALE
`
`TES SITE
`FIGURE 1
`
`86
`
`PAGE 3 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`•
`
`'1 I:
`I!
`I
`
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`
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`
`~
`
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`
`PAGE 4 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`system on the turbine exhaust. These modifications will provide improvements to the
`production, reliability, and economic performance of the Central Energy Plant..
`
`EXISTING F ACILITIES
`
`The RCID Central Energy Plant is an integrated energy production and distribution facility
`located one-halfmile north ofthe Walt Disney World (WDW) Magic Kingdom Theme Park.
`(See Figure 1 and 2). The plant is a cogeneration facility consisting of a nominal 32 MW
`General Electric LM5000 gas turbine generator, a three-pressure level 90,000 pph Vogt heat
`recovery steam generator (HRSG) and a nominal 8.5 MW Elliott extraction-condensing steam
`turbine generator. Steam from the HRSG is supplied to absorption chillers and a hot water
`system.
`
`A high temperature hot water district heating system provides 350 degree water to several WDW
`facilities. Production is normally supplied by steam from the HRSG by a steam-to-hot water heat
`exchanger. Back up supply eapability is provided by a dual-fuel hot water generator.
`
`A chilled water distriet cooling system provides 40 to 44 degree F water to the WDW Magic
`Kingdom theme park and area resorts. The chiller plant consists of 2 absorption ehiller and 9
`eleetric motor driven eentrifugal ehillers with a total deliverable capacity of 17,500 tons. Chilled
`water is distributed to customers by two piping loops.
`
`PROJECT OBJECTIVE
`
`RCID was in need of replacing two electric centrifugal ehillers. In addition they were seeking to
`reduce eooling energy costs and improve the efficieney and eapaeity of their gas turbine
`generator. Therefore, within the scope ofthis projeet are the following objeetives:
`
`*
`
`*
`
`*
`
`Eliminate the need ofreplaeing two ehillers with 3325 tons ofeapaeity. The
`ehillers use CFC refrigerants and operated at effieieney's that were low eompared
`to today's standards.
`
`Generate eooling during low energy cost periods and store the ehilled water for
`peak load periods.
`
`Provide cooling to the existing gas fired turbine-generator to enhanee the
`performance of the turbine.
`
`88
`
`PAGE 5 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`To meet these objeetives, the owner eleeted to develop the projeet in a designlbuild arrangement.
`The first step was to retain a eonsultant to develop the "seope doeuments" so that eompetitive
`designlbuild proposals eould be obtained. The seope documents eontained a deseription of the
`eomponents, eapaeities and design eriteria required for the projeet. A detailed deseription ofthe
`site development, eontrol schemes, tank storage eriteria and turbine-inlet-eooling requirements,
`eomponent speeifieations were included in the seope doeuments.
`
`Competitive bids were obtained and the eontraet was awarded to the sueeessful bidder. The
`bidders were given some latitude to develop the best, eost-effeetive design and proposal. The
`projeet was eompleted in April of 1998.
`
`CHILLED W ATER SYSTEM
`
`Eleven ehillers in the north Central Energy Plant (CEP) ehiller building and two ehillers in the
`Contemporary Hotel provide total sustainable eooling of 17,750 tons whieh supplies the Magie
`Kingdom and several hotel/resort eomplexes. The sustainable capacity is defined as the amount
`of tonnage the ehillers are estimated to be eapable of sustaining for more than one hour. The
`ehillers in the CEP are separated into two groups, the West Chiller Group and the East Chiller
`Group. A cross eonneetion with valving in the distribution system allows these ehiller groups to
`operate together or supply their individual east and west ehiller distribution systems. Either the
`East Group or the West Group of ehillers ean be isolated in ease of a line break:, leaving the other
`ehiller group in service. The ehillers are eapable of operating at a /:; T of 15°F whieh provides for
`a ehilled water flow of 1.6 gpm per ton. The ehilled water supply temperature is normally near
`41°F, but ean be varied between 40°F and 44°F.
`
`The west ehiller group eonsists of five ehillers with a total eooling capacity of 10,000 tons. The
`east ehiller group eonsists ofsix ehillers with a total eooling capacity of 4,775 tons. The
`Contemporary Hotel ehiller group eonsist oftwo ehillers with a total capacity of2,975 tOllS. With
`the largest ehiller out of operation, the total plant capacity is 14,950 tons. This total is still in
`exeess ofthe peak: load of 14,600 tons.
`
`The distribution system eonsists of two supply loops: the East Loop, supplying the Magie
`Kingdom, service areas, and several hotels; and the West Loop supplying additional hotels.
`These two ioops are supplied from a single underground distribution he ader on the north side of
`the ehiller building. The two ehillers at the Contemporary Hotel provide chilIed water to the east
`loop of the system. These two ehillers are used eontinuously as part of the chi lIed water supply
`system and are not normally eycled off during lower demand periods. Ofthe chi lIed water
`supplied to the eooling loops from the CEP ehiller building, approximately 25% of the total
`eooling load is supplied to the west loop and 75% is supplied to the east loop.
`
`89
`
`PAGE 6 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`UPGRADE TO CIllLLED WATER SYSTEM
`
`Thermal Stora~e Plannin~ for the Central Ener~ Plant
`
`Due to economic considerations resulting from the age of two of the existing chillers, with their
`high operating cost per ton, and their increasing maintenance costs, the decision has been made
`to provide a chi lIed water storage facility to take the place ofthe on-line capacity ofthese two
`chillers. This chilIed water storage system also provides emergency chilIed water backup
`capacity, allows for use of off-peak electricity at potentially lower rates, and reduces dependency
`on regulated "environmentally unfriendly" refrigerants. The chilIed water storage system will
`also take into account the additional cooling load added to the chilIed water system for providing
`turbine inlet cooling to the electric generation system. This turbine inlet cooling system will add
`electrical generating capacity to the generating plant, as weIl as increasing its efficiency at times,
`by cooling the inlet combustion air to the turbine generator. The chilIed water storage facility
`will consist of a chilIed water storage tank, charge / discharge pumps, and system controls.
`
`Plannin~ for the Chilled Water Distribution System
`
`The chilled water distribution loop system is vulnerable to a partial shutdown in case of failure
`of, or required maintenance on, the underground distribution header located just north of the CEP
`chiller plant. A new East / West Loop Connector was provided to reroute chilIed water from the
`chiller group remaining in operation after a distribution main shutdown. This new connector will
`allow chilIed water to be rerouted and supplied to both east loop and west loop distribution
`systems. The new chilIed water storage tank supply and return piping was tied into this loop
`connector to provide its cooling capacity to both the east and west loop distribution systems.
`
`Chilled Water Storage Tank and SlWply Pump Sizing
`
`The load capacity of the chilled water storage system will take into account the rem oval of the
`on-line capacity oftwo chillers totaling 3,325 tons, as weIl as an increase of2,000 tons of
`cooling for the turbine inlet cooling system. It is assumed that the present peak cooling load of
`14,600 tons must also be met with the largest chiller out ofservice. The minimum size ofthe
`chilIed water storage tank is determined as folIows:
`
`PRESENT FIRM CAPACITY
`Present peak chiller capacity
`Elimination oftwo chillers on-line capacity
`
`Total on-line tons available without old chillers
`
`Tonnage removed with largest chiller off-line
`
`Tons normally available without largest chiller
`
`90
`
`17,750 tons
`-3,325 tons
`
`14,425 tons
`
`-2,800 tons
`
`11 ,625 tons
`
`PAGE 7 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`TANK CAPACITY REQUIRED
`Pe~ system cooling load
`Less tons available from plant
`Plus additional tons for turbine inlet cooling
`
`Tons to be supplied by tank storage system
`Plus 10% contingency
`
`14,600 tons
`11,625 tons
`+ 2,000 tons
`
`4,975 tons
`500 tons
`
`Total required peak on-line capability to be supplied by tank
`
`5,500 tons
`
`Assuming that a 10-hour discharge time and 14-hour charge time are used, the volume ofthe
`storage tank required is determined by flow requirements of the system. As indicated above,
`2,000 tons of cooling is provided for turbine inlet cooling with the remaining 3,500 tons provided
`for comfort cooling. The'comfort cooling system normally uses water supplied to the loop
`system near 40°F and returned 15° warmer. This combination requires water to be supplied for
`comfort cooling at the rate of 1.6 gpm/ton of cooling:
`
`Comfort Cooling Flow Rate = 3,500 tons x 1.6 gpm/ton = 5,600 gpm
`
`The turbine inlet cooling system normally uses water supplied near 40°F and returned 30°
`warmer. This requires water to be supplied for turbine inlet cooling at the rate of 0.8 gpm/ton of
`cooling:
`
`Turbine Inlet Cooling Flow Rate = 2,000 tons x 0.8 gpm/ton = 1,600 gpm
`
`The total flow rate from the tank is the sum ofthe comfort cooling flow rate (5,600 gpm) and the
`turbine inlet cooling flow rate (1,600 gpm) or 7,200 gpm. Using the 10 hour discharge time
`indicated above, the total usable volume ofthe tank must be:
`
`Minimum Usable Tank Volume = 7,200 gpm x 10 hours x 60 min./hour = 4,320,000 gal.
`
`With a storage efficiency (Figure ofMerit) ofapproximately 0.9, the actual tank volume to be
`supplied is 5,000,000 gallons.
`
`The usable energy stored is as folIows, assuming an averageö T of 18.3°F and a figure of merit of
`0.9 minimum:
`
`Usable Energy = (5,000,000 gal.)(0.9 FOM)(8.34Ib/gal)(1 BTU/lb/oF)(18.3°F)
`
`= 6.87 x 108 BTU = 57,000 ton-hours usable at 18.3°F ö T
`
`The total flow rate from the chi lIed water storage tank as indicated above is 7,200 gpm. This
`water will be supplied by two chilIed water pumps sized at 3,600 gpm each. An additional
`standby pump will be provided for emergency use and to allow quick storage tank recharge with
`
`91
`
`PAGE 8 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`three operational pumps when the off-peak load allows. Pump speed and flow will be adjustable
`using variable frequency drive speed controllers on the pumps.
`
`Chiller Capacity for Chilled Water Stora~e Tank Rechar~im~
`
`After a full usable capacity tank discharge, the chilled water storage tank is normally recharged in
`14 ho urs overnight. The pumping system is designed so that two pumps can pump the warm
`water from the top of the storage tank and into the chiller return piping system. The existing
`CEP chiller pumping system then circulates the water through the chillers, cooling it, and
`returning it back to the bottom of the storage tank. As indicated above, one standby tank pump is
`provided for backup operation. In a quick charge situation, the third pump may be operated to
`decrease the recharge time from 14 hours to 6.7 hours. The chilIed water storage tank is
`recharged using chiller capaCity that is not required for the normal night time operating cooling
`load on the east and west loops. The required extra chiller capacity during this recharge time is
`as folIows:
`
`Extra chiller capacity for 14-hour charge cycle = 57,000 ton-hours
`14 hours
`
`= 4,100 tons excess capacity required.
`
`Minimum tank pump size = (1.6 "pmlton)(4,100 tons) = 3,280 gpm per pump
`(for recharge)
`2 pumps
`
`Supply pumps sized at 3,600 gpm are required for the discharge cycle, so this
`determines actual pump sizes.
`
`Extra chiller capacity for maximum =
`quick charge using 3 pumps
`
`57,000 ton-hours = 8,500 tons
`6.7 hours
`
`THERMAL ENERGY STORAGE TANK
`
`As mentioned above, the tank capacity is 5,000,000 gallons. The tank is an above ground steel
`tank. The tank is insulated with rigid insulation board and aluminum jacketing. The tank is
`required to have a maximum capacity of 57,000 ton-hours at an 18.3° t::,. T. The advantage of
`combining the turbine inlet cooling system (with its 30° t::,. T) can be seen. Ifthe cooling lo'ad was
`strictly comfort cooling with the 15° t::,. T the capacity of the tank would be only 46,700 ton-hours.
`The tank and foundation was designed and provided by the tank manufacturer. The tank is 116
`feet in diameter and is 67 feet taU.
`
`92
`
`PAGE 9 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`COMBUSTION TURBINE INLET AIR COOLING
`
`A combustion turbine' s electrical generating capability is direcdy related to the mass flow of
`combustion air through the unit. Because combustion turbines have fairly constant volumetrie
`inlet air flow, the mass flow of the combustion air increases as the density of the air increases.
`For mo_st utilities, including Reedy Creek Energy Services, the requirements for peak capacity
`occur during times of highest ambient temperatures. These high air temperatures result in lower
`air density and reduced capacity from the combustion turbine generator at the time the capacity is
`needed the most. However, cooling the ambient air before it enters the combustion turbine
`increases the air density and, therefore, allows the unit to generate electricity at a substantially
`higher capacity. Capacity enhancements ofup to 35 percent can be realized with inlet air cooling.
`AdditionalIy, cooler combustion air improves the combustion turbine efticiency and lowers the
`exhaust temperature.
`
`Several combustion turbine inlet air cooling projects have been successfully completed
`throughout the world in the past several years. This new application of existing technologies has
`become widely accepted in the utility industry as an economical method of capacity
`enhancement.
`
`Based on the success of existing combustion turbine inlet air cooling projects, Reedy Creek
`Energy Services requested an evaluation to utilize the proposed chi lIed water thermal energy
`storage system to supply chilled water for inlet air cooling of their existing General Electric
`LM5000 combustion turbine generator. It was determined that inlet air cooling would provide
`economical peaking capacity and energy, as weIl as providing a method of controlling the
`temperature of the chilIed water retuming to the storage tank.
`
`The design parameters used for the design of the combustion turbine inlet air cooling system
`were as folIows:
`
`•
`•
`
`•
`•
`
`•
`•
`•
`•
`•
`•
`•
`
`Air Flow
`Ambient Temperatures
`Dry Bulb
`WetBulb
`Inlet Air Cooled Temperature
`Chilled Water Temperatures
`Supply
`Return
`Chilled Water Flow Rate
`Air Velo city Across Coils
`Air Pressure Drop Across Coils
`Tube Material
`Tube Wall Thickness
`Fin Material
`Fin Spacing
`
`219,200 scfm
`
`95 degrees F
`79 degrees F
`50 degrees F
`
`40 - 44 degrees F
`
`1600 gpm
`500 fpm
`1.2 inch H20
`Copper
`0.049 inch
`Aluminum
`8 tins/inch
`
`93
`
`PAGE 10 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`The existing inlet filter house is located on top on the existing combustion turbine building and
`has four separate horizontal inlet air openings that converge into a common plenum. This
`common plenum connects vertically into the compressor section of the LM5000 combustion
`turbine. The new air cooling coils were located in four banks at the entrance to the existing
`combustion turbine air intake. The existing evaporative coolers, inertia separators and associated
`materials were removed from the inlet filter house. The exposed surfaces of the existing inlet
`filter house and plenum past the new air cooling coils were insulated and lagged for thermal
`efficiency and condensation protection.
`
`OPERATION
`
`Chilled Water Storage and Chiller System
`
`There are an infinite number of load conditions that the system may encounter depending on time
`ofyear, time of day, sky condition, humidity, park and hotel occupancy, etc. A large number of
`different modes of operation were analyzed to ensure that the central plant, thermal storage
`system and new distribution system can function effectively under varying load conditions. The
`effect of chiller outages and distribution system breaks were also evaluated to develop means to
`keep the system in operation. See the attached Figure 3 for system schematic.
`
`The storage system has approximately 14 different control modes. However, it boils down to
`three primary modes.
`
`*
`*
`*
`
`Tank Recharge Mode
`Tank Discharge Mode with bias to the central plant chillers
`Tank Discharge Mode with bias to the chilled water storage tank
`
`The pumping schemes for the three primary modes are further described as follows:
`
`Tank Recharge: The tank distribution pumps draw water from the top ofthe tank and supply it to
`the chiller plant. The chilled water is then returned to the bottom of the tank.
`
`Tank Discharge. Central Plant Bias: The central plant chillers and pumping system supply a
`preset flow level (base load) to the distribution system. The tank pumping system supplements
`this base load. The control system will vary the chilled water supply flow from the tank by
`adjusting the pumpes) VFDs to maintain system pressure.
`
`Tank Discharge. Tank Bias: Under this control scheme the tank pumping system is set to
`maintain apreset chilled water supply level to the distribution system. This level is maintained
`
`94
`
`PAGE 11 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
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`
`PAGE 12 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`and adjusted by tlow transmitters in the chilIed water supply to each distribution loop. The
`central plant pumps will adjust their tlow to maintain system pressure.
`
`Combustion Turbine Inlet Air Coolini System
`
`The intended use of the inlet air cooling system is to cool the combustion air for the GE LM5000
`existing combustion turbine. Cooling provides more mass flow of air thus increasing the
`generating capacity of the unit. The air cooling coils will be used for up to 24 hours per day, but
`will primarily be used during the highest temperature periods ofthe day, typically 10 hours.
`
`The operation of the combustion turbine inlet air cooling system is accomplished by a new
`programmable logic controller (PLC), and was integrated with the existing Reedy Creek Energy
`Services, Fomeyand Woodward control systems. The plant operator has the ability to start and
`stop inlet air cooling as weIl as control the air cooling temperature from ambient temperature
`down to the design cooled temperature of 50 degrees F.
`
`CONCLUSIONS
`
`RCID has been able to realize significant energy and economic advantages of the ChilIed Water
`Thermal Storage System. These include the following:
`•
`
`Utilization of off-peak electrical energy to provide a significant portion oftheir
`cooling requirements.
`
`•
`
`•
`
`•
`
`•
`
`•
`
`Capacity enhancement ofturbine-generator by up to 35% during warm weather
`conditions.
`
`Provide a reliable source of cooling during the day, if a chiller is taken out of
`service during peak load conditions.
`
`Provide for 20,000 ton-hrs of cooling (35 percent ofthe tank capacity) for the
`turbine-inlet-cooling system by adding only 25 percent additional storage volume
`to the thermal storage tank (due to the increased lJ. T between the supply and return
`to the tank).
`
`Eliminated the need to replace 3,325 tons of chiller capacity. Also, reduced
`reliance on CFC refrigerants for real time cooling.
`
`With the addition of the new chi lied water cross-tie between the east and west
`loops: realized an increase in system reliability in the distribution system.
`
`96
`
`PAGE 13 of 14
`
`PETITIONER'S EXHIBIT 1125
`
`

`
`The entire project provided adequate savings in energy usage to provide a good rate of return on
`RCID 's investment. The exact economic impact is not available for publication.
`
`97
`
`PAGE 14 of 14
`
`PETITIONER'S EXHIBIT 1125