Commissioning of Combined Cycle Power Plants

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    Commissioning of Combined Cycle

    Power Plants

    Commissioning of Combined Cycle Power Plants Part 1

    This is the rst in a series of four articles on the commissioning of combined cycleplants. This article covers the preparatory work, normally conducted in the oce ofthe architectengineering rm, before the startup team goes to the !ob site.1 "ntroductionPhases of a New PlantThe creation of a new power plant moves through thefollowing phases#

    Contract negotiation

    $esign

    Procurement

    Construction %tartupcommissioning

    &perationThe startup phase is a crucial and nal 'uality check of the previous phases. (nyprevious mistakes or omissions which have been overlooked will be uncovered.Problems which are brought to light during commissioning can be very e)pensive tocorrect. The procurement and delivery of new e'uipment during the startup phasecan be costly. To commission a plant, e)perienced startup personnel are necessary,since they have ac'uired the skills to implement the various programs that arediscussed in this article.

    Types of Plants to Discuss( typical combined cycle power plant has two dual*fuel combustion turbinegenerators, two heat recovery steam generators +-%/s0, and one steam turbine,with a hydrogen*cooled generator. $uct burners may be specied to compensate formegawatt production shortfall during non*isometric conditions. The total output of atypical combined cycle plant is appro)imately 22 34.

    "n this article, the term 5combustion turbine6 will be used, rather than 5gas turbine,6because many facilities do not use fuel gas, but rather a li'uid fuel.

    3any simple cycle combustion turbine generators are also being commissioned atthe present time. "n addition, various chemical plants, reneries, and process plantsare adding combined cycle power plant additions to their facilities.

    7 4ork in the &ce(ssignmentsThe nucleus of the commissioning crew should be brought onto the pro!ect in theearly design stage. The startup manager and the lead discipline engineers shouldbe drafted to work in the oce of the architectengineering rm. They can assist indesign review, and, while in the oce, they can prepare the startup deliverables.

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    Contract -eviewThe startup manager will review the pro!ect contract to identify the pro!ectdeliverables in his scope of responsibility. The schedule dates for the milestoneactivities should be ascertained.

    $eliverables

    The following are e)amples of typical contract deliverables that may be included inthe commissioning scope#

    Commissioning schedule

    %ystem turnover packages

    Commissioning organi8ation chart

    3anpower schedule

    Commissioning procedures

    9ockout and tag out program

    9ist of chemicals

    9ist of lubricants

    %tartup consumables list &perating procedures

    Training program for operators and maintenance personnel

    :mission guarantee procedures +air permit0

    eat balance guarantee procedures

    Plant acceptance testing procedures+;ote# &n some pro!ects, the last three items are prepared by thearchitectengineering rm.0

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    Commissioning 3anualThe commissioning program is detailed in the Commissioning 3anual, which shouldbe distributed to all pro!ect organi8ations.

    Cleaning ProceduresThe cleaning of systems should be conducted in accordance with approved

    procedures. The e'uipment and pipes must be cleaned to the level re'uired for theirservice. The procedures are included in the Commissioning 3anual, and becomepart of the respective system turnover package when the procedure is completed.

    Commissioning Procedures:ach individual system should have a commissioning procedure whichdemonstrates that the system has been placed into operation within designparameters. The procedures are included in the Commissioning 3anual, andbecome part of the respective system turnover package when the procedure iscompleted.

    %chedule

    The startup manager reviews the pro!ect schedule to identify activities andmilestone dates. The milestone schedule activities that are evaluated by the startupmanager are#

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    the plant owner, the operators, etc.0. The pro!ect management should approve andimplement the division of responsibilities.

    The matri) of responsibilities is included in the commissioning manual. The plantowner is normally responsible for reviewing and approving the commissioning dataand results. The startup manager must identify the process for the review and

    approval.

    Aendor -epresentatives%ome e'uipment may re'uire the assistance of vendor representatives during thecommissioning phase, to bring their e)pertise and also to protect productwarranties. The startup manager will review the vendor representative re'uirementsand make arrangements for the vendors to arrive at the !ob at the correct time. Therepresentatives for the following e'uipment may be re'uired#

    eat recovery steam generators

    $uct burners

    %oot blowers %tack dampers

    (u)iliary boiler

    :mergency or black start diesel generator+s0

    ?ire pumps

    ?ire detection and suppression systems

    4ater treatment e'uipment

    Chemical feed systems

    ?eed water pumps

    as compressors

    %team and combustion turbine generator sets

    Continuous emissions monitoring +C:30 $istributed controls system +$C%0

    Programmable logic controllers

    Power transformers

    igh voltage oil*lled cables

    %witchgear

    %witchyard e'uipment%ome pro!ects may have special e'uipment re'uirements, which necessitate avendor representative, but other pro!ects do not need the vendor. :)periencedstartup personnel can commission many pieces of e'uipment without the vendorassistance.

    (dditional "tems to -eview%ome additional programs or activities which the startup manager should reviewwhile in the oce#

    Commissioning water program +based on the source of water, destination ofwaste water, recycling water during commissioning, waste water limitations,and water permits.0

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    welding machines, rigging e'uipment, and sca=olding, may be supplied by theconstruction team, at least for the beginning of the commissioning e=ort.

    &n some pro!ects, there has been considerable time lost because the right gasketwas not available, or maybe the pipetters needed a 7 1B6 slugging wrench, or nomore fuses were left for the $C% input circuits. The commissioning team that

    prepares all the necessary consumables and tools will not have those costly delays.

    %ome seemingly insignicant tools can be very important during a startup. ( ncomb, for e)ample, can straighten out the ns on an air conditioning condenserbefore a walk down, and therefore avoid unnecessary punch list records.

    %afety%afety e'uipment, such as eye wash stations, safety showers, breathing apparatus,respirators, etc. should be ready for use during the system commissioning, asconditions warrant. "f the permanent safety e'uipment is not yet available,temporary e'uipment can be purchased or rented. %afety signs and warningbeacons must be in place, and the workers in the area should be trained in the

    identication of safety ha8ards and the remedial actions in case of an incident oraccident. Permits should be used for conned space entry, in order to have theproper e'uipment for monitoring the safety of the atmosphere in the vessel, and tohave the re'uired standby personnel to monitor those in the vessel.

    3aterial %afety and $ata %heets must be available onsite for all the ha8ardouschemicals used during the startup.

    4ork permits are used to allow construction personnel to work within theboundaries of a system that has been turned over to startup. %pecial attentionshould be placed on 5hot work permits,6 where any welding, cutting, or grinding willoccur.

    The safety tagging program +lock out and tag out0 is the principle means ofpreventing in!ury to personnel or e'uipment when the systems have beenenergi8ed.

    ?igure 1

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    Commissioning of Combined Cycle PowerPlants Part 2

    $an Parker 3ar 11, 722DThis is the second in a series of four articles on the commissioning of combinedcycle plants. This article covers the beginning of the eld work for the startup team,from the point of the system turnovers from construction to the component testing.1 %ystem Turnover +from Construction to Commissioning0Turnover PackagesThe construction team builds the power plant by area +for e)ample, the ?uel %torage(rea0.

    ?igure 1The construction e'uipment, such as a welding machine, is most eciently used bycompleting one area at a time and concentrating on the bulk work. (s work

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    progresses, the construction team should change their focus to the completion ofsystems +for e)ample, the ?uel &il eating %ystem, the ?uel &il Enloading %ystem,and the ?uel &il ?orwarding %ystem0. 4hen system construction is complete, theconstruction team prepares a turnover package for each system.

    :arly in the pro!ect, the startup manager provides marked*up engineering drawings,

    P>"$/s, and electrical one*line diagrams, which depict the boundaries of eachsystem and the e'uipment included. These drawings are the 5system scopingdrawings.6 The drawings identify all the e'uipment, pipes, cables, and instrumentsthat are in each system.

    &n some pro!ects, where computeri8ed databases of e'uipment are available, thelists can be coded for the respective systems and may be included in the turnoverpackage.

    The system scoping drawings and completed test documents are assembled into aturnover package. The startup manager also provides a schedule that species thetarget date for each system turnover. 4hen the construction team is satised that a

    system is ready for turnover, the system turnover package is submitted to thestartup manager for review. (ny incomplete construction items are noted in thepackage documentation. Those work items are completed later, under thecommissioning work permit program.

    %ystem 4alkdown(fter the startup manager reviews the turnover package, a !oint construction andcommissioning walkdown of the system is scheduled. The walkdown veries that allwork within the boundaries is complete. (ny incomplete work is noted in the punchlist.

    Punch 9istThe punch list contains individual records for each deciency noted. "t lists therespective system, the component tag number and description, a denition of thediscrepancy, the work group responsible for )ing the deciency, the dates that theitem was generated and closed, etc. The punch list is sorted by the systemdesignator, using the same designators as the turnover packages.

    &n some pro!ects, there is a tendency for each organi8ation to keep their own punchlist, but those pro!ects that combine the punch lists into one integrated list seem tocomplete the work faster. ( single pro!ect punchlist allows for better scheduling ofe'uipment and manpower, which allows for the work to be completed faster or in away that better supports the overall schedule.

    The punchlist should be kept in a database program. &n many pro!ects, thepunchlist is kept in a word processor le or a spreadsheet le.

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    within one record, because it is dicult sometimes to determine which ones areclosed.

    7 Component Testing-esponsibilities&n some pro!ects, the construction team performs some or all of the component

    testing, and on other pro!ects, the commissioning team performs some or all ofthem.

    ;ameplate $ata

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    4ater and oil piping systems are usually @ushed using the installed pumps. "n somecases, temporary pumps of high volume are used during the @ushing.

    &ver the past few years, high*pressure water has been used, with special lancesand no88les, to blast debris and rust from pipe interiors. This techni'ue has beensuccessfully employed as a prelude to steam blows or air blows on steam piping.

    $epending on the nature of the debris, @ush water may be considered a ha8ardouswaste. (t some facilities, where there is a shortage of water, the @ushing water hasbeen recycled by temporary ltration and ion e)change.

    %ome modications may be re'uired to prepare the system for @ushing. Temporarypiping !umpers are installed to avoid pumping debris into heat e)changers or controlvalves, and to avoid putting @ushing oil into bearings.

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    4ater and chemicals are introduced into the boiler and related piping, heated in thetemporary heat e)changer, and then circulated by means of temporary !umperpiping and the temporary pump. The chemistry of the cleaning solution is closelymonitored to ensure the proper chemical reactivity. The safe and economicaldisposal of chemical cleaning eIuent is an important consideration in planning thisactivity. The waste water amounts to several hundred thousand gallons, including

    the rinse water.

    (ir

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    Transformers and %witchyardsTransformer and switchyard tests are performed according to the manufacturer/sinstructions. Transformers, bushings, circuit breakers, and disconnect switches arecommonly inspected and tested by a subcontractor.

    &il*lled transformers, A bushings, and circuit breakers may re'uire conditioning of

    the insulating oil to remove vapors and water. %pecial e'uipment is re'uired for thisconditioning and testing process, and normally a subcontractor is hired to processthe oil.

    :lectrical 3eters and -elaysPower transformers, switchyard e'uipment, generators, switchgear, and loadcenters are protected by sophisticated relay systems. "f the protective relays detectfaults, they will re*route or trip the circuits in order to protect personnel ande'uipment.

    3eter and relay testing must be coordinated with the local utility, for those circuitsthat interact with the utility grid. Plant power output and utility*supplied power input

    are metered for performance and billing data. %pecial e'uipment and e)pertise isre'uired for setting the meters and relays. The design engineer species the relaysettings, testing re'uirements, and acceptance criteria by means of a relaycoordination study. ( subcontractor often tests the circuits.

    "nstrumentationThe eld instrumentation devices must be calibrated and installed prior tocommissioning. "nstrumentation devices are initially inspected and calibrated in theshop, but nal calibration often takes place in the eld, in the installedconguration. Calibration set points are provided by the design engineer, or by thevendor. Calibration stickers are a)ed to the instrument after the eld calibration issuccessfully completed.

    9oop Checks( sensing instrument is tested by simulating a specic parameter, which is thenconverted to an electrical signal and displayed on the control system graphics.

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    ?igure 7

    The displayed parameter, scaling, and engineering units are conrmed at the paneldisplay. The transmitter is then tested through a range of settings and certied asaccurately tuned. 3any input signals to the plant control system are used to controlvarious system processes. ?or e)ample, the input signal above may be used as an

    output signal to control a valve. The architecture of this input and output +"&0 signalconguration is known as a loop. There may be thousands of loops in a combinedcycle plant, with the total number dependent upon the design philosophy anddegree of automation. (larm, runback, and trip signals are all functionally testedduring commissioning.

    Commissioning of Combined Cycle PowerPlants Part 3

    $an Parker 3ar 7, 722D

    This is the third in a series of four articles on the commissioning of combined cycleplants. This article covers the continuation of the eld work for the startup team,with the system commissioning, which energi8es each system in the plant.1 System Commissioning$C Power and EP% %ystemThe rst electrical system to be energi8ed during commissioning is the directcurrent +$C0 power system. %ometimes the pro!ect contract or specications re'uirethe $C system to be load tested. The commissioning team rents load banks for thistesting.

    The $C power system provides power to the switchgear circuit breakers, e'uipment

    protective relays, and emergency pumps +such as the steam turbine emergencylubricating oil and seal oil pumps0. $C voltage also powers an uninterruptible powersupply +EP%0, which supports the plant control system. $uring commissioning, the$C system battery chargers are temporarily powered using construction power.

    The battery room must be ventilated to e)haust hydrogen gas developed during thecharging process. (n eyewash station must be available for personnel safety. Thebattery room @oors are coated with an acid*resistant sealer.

    4hen the $C system distribution system is energi8ed, testing of the (C switchgearand associated relays may begin.

    "nitial Plant :nergi8ationThe initial energi8ation of switchgear is an important commissioning milestone.:nergi8ation of large, high voltage e'uipment such as the switchyard or thegenerator step*up transformer re'uires coordinated planning between the plant andthe public utility. ( detailed procedure should be prepared, reviewed, and approved.

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    (t some plants, due to the pro!ect schedule, back feed power cannot be achieved intime to support the commissioning e=ort. 9arge diesel generators and transformerscan be rented to provide temporary power.

    $istributed Control %ystem

    ?igure 1

    Typical steps in the checkout of the distributed control system +$C%0#

    "nspect and inventory the hardware

    Check the ground connection

    Clear any grounds

    :nergi8e, but with no terminations made

    :nergi8e each processor and check status

    9oad software

    %etup the human machine interface +3"0

    Perform component and functional checks

    Aerify data historian hardware and software

    :stablish communications between the $C% and the other control systems,such as the combustion turbine controls, the steam turbine controls, theC:3%, etc.

    (s entire systems are placed in service, and the plant becomes operational,the $C% personnel will perform 5loop tuning,6 where the control parameters+proportional, integral, and derivative gains, or P"$0 are ad!usted to achieveoptimum control. %chedule time should be allotted for this loop tuning.

    "nstrument (irThe rst mechanical system to be started during commissioning is the instrumentair system. ?or comple) air compressor congurations, the vendor should bepresent to assist in the startup. The controls for the compressor should be veriedagainst the design.

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    3oisture traps on the discharge of the air compressor should be inspected veryclosely to make sure they are installed correctly. -eview the vendor literature.

    The air dryers, if they are self*regenerating, may take some time to produce dry air.The system humidity indicator should be closely monitored for proper indication

    during the initial operation. $uring the blowing of the system/s distribution piping,the air dryers should be monitored to prevent e)cessive @ow rates.

    The piping system must be blown out with dry air, and the drops to each instrumentshould be cleaned vigorously.

    (t add*on units where the e)isting unit will provide the instrument air, the new plantundergoing commissioning may draw more air than normal, because of thecommissioning activities. This can !eopardi8e the operation of the e)isting facility. "nthese cases, rented compressors and driers may be necessary.

    4ater Treatment

    ;ormally, the second mechanical system to start is the water treatment system.3odern water treatment systems can be very large, with complicated controlsystems. The vendor representative should be e)pected to work with thecommissioning team until the system is running reliably in the automatic mode.

    The chemical analysis e'uipment needed to monitor the systems should be madeavailable, and a suitable 5laboratory6 should be fabricated. (t some pro!ects, arented cargo container suces for a temporary chemistry laboratory, with thevarious utilities connected. The following items should be completed prior to addingthe resin to a deminerali8er vessel#

    The interior portions of deminerali8ers should be inspected.

    The regeneration control se'uence +valve stroking, pumps starts and stops0should be thoroughly tested.

    The rinse water @ow rates and chemical dilution @ow rates should bead!usted.

    (n eductor should be purchased, since most vendors re'uire that an eductorbe used to sluice the resin into the vessels.

    4aste 4ater Treatment4hen the water treatment system is started, there is a corresponding need to getrid of waste water. $eminerali8ers and reverse osmosis units generate predictable'uantities of waste water. %o the waste water treatment system is very important,and should receive a high priority in the commissioning planning. (t some pro!ects,

    waste water and solid waste e)port must be subcontracted.

    (t some facilities, the waste water treatment system can be 'uite comple), such asat a 58ero discharge6 plant. This consists of multiple trains of reverse osmosis units,ltration systems, evaporators, concentrators, and lter presses. %ometimes thein@uent water to the plant is a 5gray water6 eIuent from a nearby sewagetreatment facility. Then there are additional backwash lters, clariers, and lterpresses. "t is vital that the manpower re'uired to commission and maintain bigsystems like these not be underestimated.

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    3ost plants incorporate some type of oily water separation. The separating deviceshould be tested early in the startup se'uence, since invariably there will be someoil to process.

    ?ire $etection and Protection

    The installation subcontractor normally tests the re detection system, but thecommissioning personnel must monitor the testing closely, in order to becomefamiliar with the system.

    ?ire protection systems, such as sprinklers, deluge valves, and gas dischargesystems may be tested by a subcontractor, or by the commissioning team.$epending on the !ob location, a government inspector or an insurance companyinspector may need to witness the testing.

    ?ire pumps should be one of the rst pumps to be placed in service, after the watersupply system makes water available. +(t some plants, the re protection watersupply comes from well water or raw water, while at other plants, the source may

    be a water treatment system.0 3onitor the !ockey pump for fre'uent cycling, whichmay be an indication that there is a leak in the re main, perhaps underground. Themotor*driven or diesel*driven re pump should be placed in the automatic mode assoon as possible.

    "f the cooling tower is fabricated from wood, the associated re protection delugevalves should be placed in service as soon as possible.

    3ake sure that post indicator valves have their indicators 5calibrated6 to show thecorrect position.

    Cooling 4aterCirculating water systems that use seawater need special care during thecommissioning phase, due to the corrosive nature of seawater and the marine lifeand debris associated with seawater. The rakes, traveling screens, tube cleaningsystems, and pump intake screens re'uire meticulous care during thecommissioning phase, to prevent the introduction of debris into the condenser.

    9arge circulating water pumps must be aligned carefully and accurately. $ependingon the system design, the pumps may have a special valve that vents the air fromthe discharge column. %eal water for lubrication of the pump packing may have tobe provided by a backup system. The pump discharge valve is normally motor*operated, and its operation should be veried prior to starting the pump.

    The condenser water bo)es may have vent valves which must be opened andclosed manually when starting the system. "f there is a water bo) priming system, itshould be commissioned and placed in service at the beginning of the program. "fnot, air pockets will build up in the water bo)es, and some tubes may not be lledwith seawater. %ome plants re'uire throttling of the outlet valves on the waterbo)es, to setup the proper @ow or pressure parameters. The water bo)es may havesacricial 8inc anodes. These anodes must be checked after the initial operation of

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    the system. The commissioning personnel must research these features prior tostarting the system.

    $uring the walkdown of the condenser, all the ttings should be inspected closely,to make sure there are no materials installed that are non*compatible withseawater.

    Cooling towers re'uire special monitoring prior to use. The spray no88les,distribution headers, and ll should be inspected before starting the system, andalso sometime after the rst use, to make sure there are no problems created bythe force of the water. Cooling tower fans should be checked for vibration, and theirgearbo)es should be monitored for proper lubrication. "f the cooling tower has aplace to mount corrosion coupons, the coupons should be installed prior tointroducing water. ( wooden cooling tower should have its re protection system inservice as soon as possible. &nce a wooden cooling tower is put in service, it shouldremain wet as much as practicable, so that it does not dry out and become a reha8ard.

    %team, ?eed 4ater, and Condensate(fter these systems are cleaned, as discussed above, they are prepared for service.

    The condensate pumps are tested, along with their various control valves. %pecialcare is taken with the pump seal or packing. %ome pumps re'uire an e)ternalsource of seal waterK the pump technical manual should be reviewed for thisfeature. "f possible, some spare seals or packing should be on the list of spare parts.

    The condenser air removal system may consist of steam !et air e!ectors, vacuumpumps, or a combination of the two. The startup engineer must monitor the varioussteam traps very closely, making sure they have free drainage to their destination.%ome traps on air e!ector packages re'uire a vent line back to the after condenser.%ome plants have a vacuum breaker valve, which re'uires seal water to prevent airin*leakage. 3ake sure the seal water is installed.

    The condenser +or steam turbine0 rupture disc should be inspected closely prior tovacuum operations. %ome discs have to be installed in one particular direction. Thearea around the disc should not be accessible for personnel.

    The deaerator should be inspected before use, to make sure the trays are installedin the proper orientation, and that they are secure. The spray no88les should be leftout, if not yet installed, or removed, if they have been installed. The deaeratorshould be inspected after the initial round of @ushing, to remove any debris thatsettled in the storage vessel, and to install the spray no88les. The deaerator shouldreceive a nal inspection after the period of initial operation, to check the sprayno88les and trays.

    The various types of feed water pumps need customi8ed care to ensure smoothoperation. The pump suction strainer is very likely to plug when rst running thepump. The minimum @ow valve and any minimum @ow orice should be inspectedto make sure they don/t cause too much @ow restriction for the pump. "f the pumphas an automatic recirculation valve in the discharge, the valve should either be

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    e)pansion of the gas causes the temperature to plummet precipitously, and free8ingcan occur.

    9i'uid ?uel(t some plants, a li'uid fuel, such as distillate, is used as a backup fuel for thecombustion turbine, the au)iliary boiler, and the duct burners. The li'uid fuel

    system must be cleaned well, to prevent plugging of e'uipment with closetolerances.

    %ome li'uid fuel tanks have @oating suction devices. This hardware should beinspected prior to lling the tank. (ny special coatings in the tank interior shouldalso be checked. %iphon breakers on the tank should be disassembled, to make surethere are no shipping stops in the valves.

    The li'uid fuel unloading station should be checked for proper spill containment andre safety.

    (ir Conditioning and Aentilation

    (t many plants, the air conditioning and ventilation systems are seeminglyabandoned after their initial start, because they are 5someone else/s6 responsibility.Therefore, a good commissioning team will monitor these systems, even if they arein fact some other organi8ation/s responsibility, because degradation of thesesystems can have an adverse impact on plant performance.

    -eplace air lters regularly during startup. Ese good 'uality pleated air lters,rather than the cheap berglass types. The pleated air lters can take more abuse,and they keep your system cleaner. $ue to the dust and dirt at construction sites,air conditioning condenser coils may need fre'uent cleaning.

    Condensate drains need to be directed to a suitable location. 3ost units have a 5ptrap6 on the condensate, to allow the water to drain, but not allow un*ltered air tobe drawn into the unit. "f there are troubles with the trap, it may cause water toback up in the unit.

    %ystem CheckoutThe remaining systems needed for running the combustion turbine and -% aretested on a system basis. The e'uipment is energi8ed, and the process @uid is putinto the system. The various control circuits are checked, to verify controls andinterlocks work as designed. 4here possible, the system parameters are ad!usted toproduce the various set points which cause the controls and interlocks to function.?or e)ample, tank levels are raised and lowered to trigger alarms or trips, or systemvalves are throttled to cause low @ow or low pressure conditions.

    "f a system has heat tracing installed on its pipes or instrument lines, and theweather predictions are for free8ing temperatures, make sure the heating supply isready and the insulation is installed. The heat may be applied from steam or anelectrical supply.

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    Combustion Turbine"n most plants, the commissioning of the combustion turbine itself is theresponsibility of the turbine vendor. They provide specialists in the various systemsof the turbine# the controls, the electrical systems, and the mechanical systems.

    The lubricating oil @ush is customarily one of the rst activities, and has traditionally

    been a milestone benchmark. Temporary power is used to power the lubricating oilpumps for the @ush. The oil should be puried before lling the reservoir, sincebrand new oil shipments have been received with debris in the oil.

    The turbine control systems also receive a temporary power supply, in order tocheckout the circuits early in the commissioning program. The aim of the systemcommissioning period is to get the combustion turbine shaft rotating and ready forring.

    %team TurbineThe steam turbine is also commissioned by the vendor/s personnel, who arespecialists in their area of responsibility. The steam turbine commissioning occurs

    later in the schedule, so permanent power is usually available for the steam turbinee'uipment. The lubricating oil @ush of the steam turbine is conducted in a mannersimilar to that of the combustion turbine.

    The goal of the system commissioning period is to have the turbine shaft on turninggear, with gland sealing steam applied and vacuum on the condenser. The steamturbine is then ready to admit steam.

    Thermal :)pansion

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    during the initial rst re operation.

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    raising the combustion turbine ring +or by raising the steam turbine steamadmission rate0.

    ?ailure to accurately synchroni8e the generator to the grid before closing the circuitbreaker may damage the generator. Protective relays detect any out*of*phaseconditions and will not permit breaker closure.

    4ater Ese$uring chemical cleaning and rst re operation, deminerali8ed water demands cane)ceed the water production rate and storage capacity. Chemical cleaning re'uireslarge 'uantities of deminerali8ed water for preparing the cleaning solutions and thesubse'uent lling, @ushing, and rinsing of the piping and -%Gs.

    (t the time of combustion turbine rst re, fre'uent blowing down of the -% isre'uired to remove loose magnetite and achieve the steam purity necessary forsteam admission to the steam turbine.

    $uring commissioning, the water treatment system will become increasingly reliable

    and will attain the throughput guarantees and chemical purity specications. "t maybe necessary on a temporary basis to augment the water production by mobiledeminerali8ers.

    ;ormal

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    ?igure 7

    %tep NO# The condensate piping and the -% drums, economi8ers, andevaporators are lled via the condensate make*up pump cold ll line.

    %tep N# The condensate pump is started and placed in recirculationoperation from the $C%. Pump motor amperage, thermal rise, and vibrationare monitored. Pump suction pressure, discharge pressure, and suctionstrainer di=erential pressure are also monitored.

    %tep N# The condenser hotwell level controls are veried in both manual andautomatic operation.

    %tep NH# Condensate @ows to the -% 9P economi8er and is recirculated tothe condenser via the economi8er recirculation line +if such a recirculationline is included0.

    %tep NB# Condensate @ows through the 9P economi8er D*way valve bypassand into the 9P drum. The condensate is then redirected via the D*way valveinto the economi8er and into the 9P drum. D*way bypass control is veried atthe $C%. Thermocouple indications in the 9P economi8er are veried at the$C%.

    %tep NQ# ( feed water pump is started and placed in recirculation operation.9P drum level indicator signals are monitored at the $C%. 9evel control valveoperation is veried. ?eed water pump lubricating oil distribution,temperature and pressure is veried locally and at the $C%. Cooling water@ow and temperature is monitored locally and at the $C%. Pump motoramperage, thermal rise, and vibration are checked. Pump suction pressure,

    discharge pressure, and suction strainer di=erential pressures are monitored."f the condenser has e)cessive leakage while under vacuum, and all the normalleakage sites have been checked by site personnel, it is benecial to subcontract aspecialist in condenser air in*leakage testing. These companies use heliumdetectors, installed at the air discharge of the condense air removal system, andthey spray helium around the !oints, man ways, and @anges of the condenser andsteam turbine. The helium detector can even be RcalibratedR to estimate theamount of leakage. The subcontractor can spot the source of the leakage in amatter of hours.

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    and then they will pump a system*friendly compound into the tting to stop theleak. These leak repairs have been successfully employed on high pressure steamsystems, circulating water systems, glycol cooling systems, and elsewhere.

    (nother techni'ue for making repairs on the run is to use a Rfree8e sealR to isolatean otherwise un*isolable section of a system and allow a repair to be made. Sits are

    available for Rdo it yourselfR free8e seals, or subcontractors can be employed for themore dicult cases. -epairs on @anges or valves can often be performed by an Rinplace machiningR subcontractor.

    ousekeeping"t is a well*known fact that plants that have good housekeeping are easier to start.4hen the commissioning team is not encumbered by construction dirt and debris,the e'uipment stays clean and more trouble*free. The startup manager should insiston good housekeeping from all the organi8ations on the pro!ect.

    Performance TestingThe heat rate test is based on the engineered heat balances supplied by the plant

    designer. The net plant heat rate typically supercedes any individual combustionturbine and steam turbine guarantees and is calculated as

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    meters will be used to pay fuel costs and to calculate the plantGs electrical salesrevenues.

    :missions Testing-% stack emissions testing validates the emission limit guarantees. "n manyplants, the combustion turbine e)haust gas nitrous o)ide +;&)0 reduction

    e'uipment will not satisfy the local environmental permit re'uirements, and it istherefore necessary to supplement the combustion turbine ;&) reductione'uipment with an -% selective catalytic reduction +%C-0 unit. The combustionturbine e)haust enters the -% and passes through %C- modules located behindthe high pressure evaporator modules. (mmonia is in!ected into the @ue gas, and itreduces the ;&) while on the catalyst surface. The ammonia decomposes ;&) intoharmless ;7 and 7&, according to the reactions#

    The stack ;&) is tested as ;&7 and measured in parts per million +PP30 by volumeon a dry gas basis, corrected to 1 o)ygen. -% stack emissions testing mayalso include tests for#

    (mmonia +e)cess ammonia admitted to the %C-0

    Carbon mono)ide

    Particulate +si8ed in microns0

    Aolatile organic compounds +e.g. methane0

    %ulfur-% stack emissions testing is typically performed after the installed C:3 hasbeen certied. owever, if the permanent plant C:3 is not certied at the time of

    emissions testing, a rented, portable C:3 is used. The -% stack emission testingmay be performed in con!unction with the heat rate testing. owever, the emissionstest may be conducted at several di=erent load points +2, H, 122 fore)ample, with and without duct burners0 on a one*hour average basis, while theheat rate testing may be performed at only one load point. Combustion turbinee)haust gas ;&U emission guarantees of Q.2 ppmvd +V1 &70 are now common.Combined cycle plant -% stack emission guarantees +with an %C-0 can be as lowas D. ppmvd +V 1 &70.

    Contract TestingThe following tests may be re'uired by the contract#%team Turbine and Combustion Turbine &verspeed Tests 3odern overspeed controls

    are now redundant electronic circuits +replacing the spring*loaded mechanical bolt*type overspeed device0. (t least two overspeed tests are performed +one on eachcircuit0, and then repeated if necessary.

    C&7 Concentration Tests(fter the combustion turbine C&7 piping is cleaned and pressure tested with air,and the re control and alarm system is fully tested, the C&7 storage tank may belled. The system is dynamically tested by initiating a re alarm +via any of the heat

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    %ystem 4alkdownThe system walkdown is conducted in the same manner as the constructionturnover walkdown. The walkdown veries the work within the boundaries iscomplete. (ny incomplete work is noted on the punchlist. Those work items arecompleted later, under the ownerGs work permit program.

    R4ish 9istRThe ownerGs personnel are not always conversant with the contract for designingand building the plant, and sometimes they write into the punch list items which arebeyond the scope of the contract +therefore known as Rwish listR items0. The startupmanager will di=erentiate between in*scope deciencies and out*of*scope re'uests.The plant owner may need to establish a separate contract to add theseenhancements at a later time, after the plant startup is completed.

    3 Conclusions$ue to the popularity of the combined cycle power plant, many startups haveoccurred in the past few years, and a system of commissioning has evolved. That

    system is based on the historical groundwork of the electrical utility fossil andnuclear plant startups, and has been modied to match the needs of the moderncombined cycle power plant.

    :)perienced startup personnel have been trained and are ready to meet thetechnical demands and challenges of their industry.