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 commissioning of combined cycle plants. This article covers the preparatory work, normally conducted in the oce of the architectengineering rm, before the startup team goes to the !ob site. 1 "ntrodu "nt roducti ction on Phases of a New Plant The creation of a new power plant moves through the following phases# Contract negotiation $esign Procurement Construction %tartupcommissioning &peration The startup phase is a crucial and nal 'uality check of the previous previous phases. (ny previous mistakes or omissions which have been overlooked will be uncovered. Problems Problems which are brought brought to light during commissioning can be very e)pensive to correct. The procurement and delivery of new e'uipment during the startup phase can 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 are discussed in this article. • • • • • •
Types of Plants to Discuss ( typi typica call comb combin ined ed cycl cycle e powe powerr plan plantt has has two two dual dual*f *fue uell comb combus usti tion on turb turbin ine e generators, two heat recovery steam generators +-%/s0, and one steam turbine, with a hydrogen*cooled generator. $uct burners may be specied to compensate for megawatt production production shortfall during non*isometric conditions. The total output of a typical combined cycle plant is appro)imately 22 34.
"n this article, the term 5combustion turbine6 will be used, rather than 5gas turbine,6 because many facilities do not use fuel gas, but rather a li'uid fuel. 3any simple cycle combustion turbine generators are also being commissioned at the present time. "n addition, various chemical plants, reneries, reneries, and process plants are adding combined cycle power plant additions to their facilities. 7 4ork in the &ce &c e (ssignments The nucleus of the commissioning commissioning crew should be brought onto the pro!ect in the early design stage. The startup manager and the lead discipline engineers should be drafted to work in the oce of the architectengineering rm. They can assist in design review, and, while in the oce, they can prepare the startup deliverables.
Contract -eview The startup manager will review the pro!ect contract to identify the pro!ect deliverables in his scope of responsibility. The schedule dates for the milestone activities should be ascertained. $eliverables The following are e)amples of typical contract deliverables that may be included in the commissioning scope# Commissioning schedule %ystem turnover packages Commissioning organi8ation chart 3anpower schedule Commissioning procedures 9ockout and tag out program 9ist of chemicals 9ist of lubricants %tartup consumables list &perating procedures Training Training program program for operators operators and maintenance maintenance personnel personnel :mission guarantee procedures +air permit0 eat balance guarantee procedures Plant acceptance testing procedures +;ote# &n some pro!ects, the last three items are prepared by the architectengineering rm.0
- breaks, and living accommodations at the eld location0. • • • • • • • • • • • • • •
Pro!ect -eview 4hile in the oce, the commissioning personnel personnel can utili8e their uni'ue perspective to review the design of the pro!ect. They can criti'ue the piping and instrumentation diagrams +P>"$/s0, electrical one*line diagrams, vendor manuals, and other related documents. They can interact with the design personnel, and develop relationships which will promote problem solving during the dicult startup phase ahead. They can review pro!ect drawings and documents for commissioning feasibility, system operability, and maintainability. The architectengineering architectengineering rm will also produce lists, such as e'uipment lists, valve lists, lists, instr instrume ument nt lists, lists, and line line +pipi +piping0 ng0 lists, lists, which which should should be collec collected ted by the commissioning crew for later use.
Contract -eview The startup manager will review the pro!ect contract to identify the pro!ect deliverables in his scope of responsibility. The schedule dates for the milestone activities should be ascertained. $eliverables The following are e)amples of typical contract deliverables that may be included in the commissioning scope# Commissioning schedule %ystem turnover packages Commissioning organi8ation chart 3anpower schedule Commissioning procedures 9ockout and tag out program 9ist of chemicals 9ist of lubricants %tartup consumables list &perating procedures Training Training program program for operators operators and maintenance maintenance personnel personnel :mission guarantee procedures +air permit0 eat balance guarantee procedures Plant acceptance testing procedures +;ote# &n some pro!ects, the last three items are prepared by the architectengineering rm.0 - breaks, and living accommodations at the eld location0. • • • • • • • • • • • • • •
Pro!ect -eview 4hile in the oce, the commissioning personnel personnel can utili8e their uni'ue perspective to review the design of the pro!ect. They can criti'ue the piping and instrumentation diagrams +P>"$/s0, electrical one*line diagrams, vendor manuals, and other related documents. They can interact with the design personnel, and develop relationships which will promote problem solving during the dicult startup phase ahead. They can review pro!ect drawings and documents for commissioning feasibility, system operability, and maintainability. The architectengineering architectengineering rm will also produce lists, such as e'uipment lists, valve lists, lists, instr instrume ument nt lists, lists, and line line +pipi +piping0 ng0 lists, lists, which which should should be collec collected ted by the commissioning crew for later use.
Commissioning 3anual The commissioning commissioning program is detailed in the Commissioning Commissioning 3anual, which should be distributed to all pro!ect organi8ations. Cleaning Procedures The cleaning of systems should be conducted in accordance accordance with approved approved procedures. The e'uipment and pipes must be cleaned to the level re'uired for their service. The procedures are included in the Commissioning 3anual, and become part of the respective system turnover package when the procedure is completed. Commissioning Procedures :ach :ach indi indivi vid dual ual syst system em shou should ld hav have a comm commis issi sion onin ing g proc proced edur ure e whic which h demons demonstra trates tes that that the the system system has been been placed placed into into opera operatio tion n within within desig design n parame parameter ters. s. The The proc procedu edure res s are are includ included ed in the Commi Commiss ssion ioning ing 3anua 3anual, l, and become part of the respective system turnover package when the procedure is completed. %chedule The startup manager reviews the pro!ect schedule to identify activities and milestone dates. The milestone schedule activities that are evaluated by the startup manager are#
The commissioning commissioning portion of the pro!ect schedule has the same outline as the commissioning work# the individual components are inspected and tested, then the system is tested by itself, then the combustion turbine is started, and nally the entire plant is operated and tested. 3ost pro!ects use scheduling software to track the pro!ect pro!ect schedule schedule.. Commissi Commissionin oning g personne personnell can nowadays nowadays easily easily build build and modify their own startup schedules that can be linked to the construction schedule. The predecessor and successor relationships, relationships, total @oat, constraints, and resources resources are some of the schedule parameters that should be analy8ed. 3atri) of -esponsibilities The startup manager must identify the specic responsibilities responsibilities of each party in the pro!ect +the design organi8ation, the construction team, the commissioning team,
the plant owner, the operators, etc.0. The pro!ect management should approve and implement the division of responsibilities. The matri) of responsibilities is included in the commissioning manual. The plant owner is normally responsible for reviewing and approving the commissioning data and 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 the commissioning phase, to bring their e)pertise and also to protect product warranties. The startup manager will review the vendor representative re'uirements and make arrangements for the vendors to arrive at the !ob at the correct time. The representatives 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 a vendor representative, but other pro!ects do not need the vendor. :)perienced startup personnel can commission many pieces of e'uipment without the vendor assistance. • • • • • • • • • • • • • • • • • • • •
(dditional "tems to -eview %ome additional programs or activities which the startup manager should review while in the oce# •
Commissioning water program +based on the source of water, destination of waste water, recycling water during commissioning, waste water limitations, and water permits.0
?uel specications ?uel consumption +at some plants, the client needs to know the anticipated consumption during commissioning, to make bids for fuel0 Craft support re'uirements 3aintenance program, in accordance with the vendors/ literature "nterface*points between the new plant, outside utilities, or an e)isting plant overnment or insurance company inspectors re'uired for testing safety valves, re detectionprotection systems, etc. :'uipment to Purchase or -ent
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Chemicals 9ubricants Test e'uipment Chemical analysis e'uipment Tools +mechanic/s tool set, electrician/s tool set, packing removal tools, rigging gear, air conditioning tool set, valve wrenches of all si8es0 %torage container for tools %torage container for e'uipment which has been temporarily removed from the plant Temporary pumps, hoses, plastic tubing, and ttings %pare parts +mechanical seals for pumps, $C% cards0 Consumables +gaskets, packing, light bulbs, fuses, panel lenses, etc.0 %olvents to dissolve grease or remove rust Truck+s0 for hauling e'uipment and personnel on !obsite &ce space, oce e'uipment, furniture, supplies, telephones, fa) machine Computers, printers, and software for the commissioning oce -adios +and fre'uencies0, antennas, base stations, and repeaters for onsite communication Transportation re'uirements for personnel +automobiles, vans, and drivers for international locations0 The startup manager needs to determine who is responsible for supplying the various chemicals and lubricants. &n some pro!ects, the commissioning team is responsible for supplying the rst load of chemicals andor lubricants, and the plant owner is responsible after that. • • • • •
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"f the architectengineering rm does not produce their own lubrication list, the startup manager may be able to have one of the well*known oil companies produce a lubrication list for the pro!ect, as part of their scope of supply. "t is more cost e=ective to rent the more unusual test e'uipment for a limited time, and to purchase the normal, everyday type of test e'uipment. The schedule for the full*blown commissioning e=ort occurs at a time when the construction team is winding down their manpower and e'uipment, so you cannot always rely on them for support in areas like tools and consumables. The startup manager should therefore plan on purchasing or renting a full repertoire of tools. %ome tools, like
welding machines, rigging e'uipment, and sca=olding, may be supplied by the construction team, at least for the beginning of the commissioning e=ort. &n some pro!ects, there has been considerable time lost because the right gasket was not available, or maybe the pipetters needed a 7 1B6 slugging wrench, or no more 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. ( n comb, for e)ample, can straighten out the ns on an air conditioning condenser before 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, as conditions warrant. "f the permanent safety e'uipment is not yet available, temporary e'uipment can be purchased or rented. %afety signs and warning beacons 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 or accident. Permits should be used for conned space entry, in order to have the proper e'uipment for monitoring the safety of the atmosphere in the vessel, and to have the re'uired standby personnel to monitor those in the vessel. 3aterial %afety and $ata %heets must be available onsite for all the ha8ardous chemicals used during the startup. 4ork permits are used to allow construction personnel to work within the boundaries of a system that has been turned over to startup. %pecial attention should be placed on 5hot work permits,6 where any welding, cutting, or grinding will occur. The safety tagging program +lock out and tag out0 is the principle means of preventing in!ury to personnel or e'uipment when the systems have been energi8ed. ?igure 1
Commissioning of Combined Cycle Power Plants Part 2 $an Parker 3ar 11, 722D This is the second in a series of four articles on the commissioning of combined cycle plants. This article covers the beginning of the eld work for the startup team, from the point of the system turnovers from construction to the component testing. 1 %ystem Turnover +from Construction to Commissioning0 Turnover Packages The construction team builds the power plant by area +for e)ample, the ?uel %torage (rea0.
?igure 1 The construction e'uipment, such as a welding machine, is most eciently used by completing one area at a time and concentrating on the bulk work. (s work
progresses, the construction team should change their focus to the completion of systems +for e)ample, the ?uel &il eating %ystem, the ?uel &il Enloading %ystem, and the ?uel &il ?orwarding %ystem0. 4hen system construction is complete, the construction team prepares a turnover package for each system. :arly in the pro!ect, the startup manager provides marked*up engineering drawings, P>"$/s, and electrical one*line diagrams, which depict the boundaries of each system and the e'uipment included. These drawings are the 5system scoping drawings.6 The drawings identify all the e'uipment, pipes, cables, and instruments that are in each system. &n some pro!ects, where computeri8ed databases of e'uipment are available, the lists can be coded for the respective systems and may be included in the turnover package. The system scoping drawings and completed test documents are assembled into a turnover package. The startup manager also provides a schedule that species the target 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 the startup manager for review. (ny incomplete construction items are noted in the package documentation. Those work items are completed later, under the commissioning work permit program. %ystem 4alkdown (fter the startup manager reviews the turnover package, a !oint construction and commissioning walkdown of the system is scheduled. The walkdown veries that all work within the boundaries is complete. (ny incomplete work is noted in the punch list. Punch 9ist The punch list contains individual records for each deciency noted. "t lists the respective system, the component tag number and description, a denition of the discrepancy, the work group responsible for )ing the deciency, the dates that the item was generated and closed, etc. The punch list is sorted by the system designator, using the same designators as the turnover packages. &n some pro!ects, there is a tendency for each organi8ation to keep their own punch list, but those pro!ects that combine the punch lists into one integrated list seem to complete the work faster. ( single pro!ect punchlist allows for better scheduling of e'uipment and manpower, which allows for the work to be completed faster or in a way that better supports the overall schedule. The punchlist should be kept in a database program. &n many pro!ects, the punchlist is kept in a word processor le or a spreadsheet le.
within one record, because it is dicult sometimes to determine which ones are closed. 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 of them. ;ameplate $ata
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4ater and oil piping systems are usually @ushed using the installed pumps. "n some cases, temporary pumps of high volume are used during the @ushing. &ver the past few years, high*pressure water has been used, with special lances and no88les, to blast debris and rust from pipe interiors. This techni'ue has been successfully 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 ha8ardous waste. (t some facilities, where there is a shortage of water, the @ushing water has been recycled by temporary ltration and ion e)change. %ome modications may be re'uired to prepare the system for @ushing. Temporary piping !umpers are installed to avoid pumping debris into heat e)changers or control valves, and to avoid putting @ushing oil into bearings.
-un the pump as necessary to @ush the system. $uring the @ushing, after some time of regular operation is achieved, the pump performance and vibration data can be collected. Pumps should be tested in accordance with a standard test program +such as (%3: Performance Test Code H.1 or B.7, or the ydraulic "nstitute %tandards0. ?or centrifugal pumps, the capacity versus the head is compared to the pump curve, which was developed during the factory shop test. Aerify the pump meets or e)ceeds the design point. Positive displacement pumps should be tested for the capacity measurement by volume rate of @ow. 9ubricating &il ?lushing The site personnel may @ush the combustion turbine and steam turbine lubricating oil systems. The area around the turbine should be free of dirt and construction debris +especially the reservoir and bearing areas0. Temporary power and lighting must be available. %everal strategically located emergency lubricating oil pump shuto= switches should be installed. ?ire protection e'uipment must be available. (lthough it seems like it would be very unusual to have a re during a lubricating oil @ush, it has indeed happened in the past. (lso, make provisions for dealing with oil spills and leaks +have sucient adsorbent compound, rags, plastic bags, s'ueegees, and barrels on hand0. Personnel should be trained to handle oil spills. (t some plants, a subcontractor, using temporary @ush skids with pumps, lters, and heat e)changers, performs the lubricating oil @ushing. %ome bigger pumps, like feed water pumps, have an integral lubricating oil system. These systems are generally cleaned in a manner similar to that used on the turbines. eat :)changers 4hen @ushing the system, it is preferable to bypass any heat e)changer, to prevent debris from entering the e)changer.
4ater and chemicals are introduced into the boiler and related piping, heated in the temporary heat e)changer, and then circulated by means of temporary !umper piping and the temporary pump. The chemistry of the cleaning solution is closely monitored to ensure the proper chemical reactivity. The safe and economical disposal of chemical cleaning eIuent is an important consideration in planning this activity. The waste water amounts to several hundred thousand gallons, including the rinse water. (ir
%team blows use very large 'uantities of water. 4here permanent deminerali8er water production is not sucient to sustain the steam blow, e)pensive portable deminerali8er rentals are re'uired. Temperature Cycling This is the core of the debate on air blow vs. steam blow. The steam blow proponents argue that it is only by @e)ing the pipe, through repeated heating and cooling, that the mill scale is removed. (ir blow proponents argue that a proper disturbance factor ensures the mill scale will be scoured. (s indicated previously, high*pressure water has been used, with special lances and no88les, to blast mill scale, debris, and rust from pipe interiors. This techni'ue has been successfully employed as a prelude to steam line cleaning. &n one pro!ect that had two identical units side*by*side, one plant was cleaned by air blow and the other by steam blow. The cleanness results were identical. &n both air blow and steam blow, the respective techni'ues must be performed accurately for good results. $epending on the plant conguration, it may be benecial when conducting air blows to connect unrelated systems together to form a larger reservoir of air. This produces longer air blows. ?or e)ample, at one very large chemical plant, the product line was combined with the main steam header to produce a reservoir of much larger si8e. 3otors The internal heaters on large motors, generators, and motor*operated*valves should be energi8ed with temporary power. &n pro!ects which have a long duration, the heaters may be energi8ed in the warehouse or laydown area. 9arge motors and generators are megger*tested during the construction period to verify insulation integrity. ( megger test instrument introduces a moderately high voltage into the motor windings. (ny winding insulation breakdown that permits winding*to*winding shorts, or winding*to*ground shorts is detected by the megger instrument. :lectric motors should be tested uncoupled from the driven component to verify proper motor rotation and operation. Cables, %witchgear, and 3otor Control Centers (ll cables and switchgear3CC buses are tested prior to energi8ation. Cables are tested for continuity and insulation resistance. The megger test instrument introduces a moderately high voltage +22 or 1,222 Aolts0 to detect any shorts to ground that may be caused by an insulation breakdown. ?or switchgear and 3CC/s, hi*pot testing +using very high voltage0 to test high voltage feeders and switchgearbuses re'uires special test e'uipment. The design engineer typically provides hi*pot test acceptance criteria.
Transformers and %witchyards Transformer and switchyard tests are performed according to the manufacturer/s instructions. Transformers, bushings, circuit breakers, and disconnect switches are commonly 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 this conditioning and testing process, and normally a subcontractor is hired to process the oil. :lectrical 3eters and -elays Power transformers, switchyard e'uipment, generators, switchgear, and load centers are protected by sophisticated relay systems. "f the protective relays detect faults, they will re*route or trip the circuits in order to protect personnel and e'uipment. 3eter and relay testing must be coordinated with the local utility, for those circuits that 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 is re'uired for setting the meters and relays. The design engineer species the relay settings, testing re'uirements, and acceptance criteria by means of a relay coordination study. ( subcontractor often tests the circuits. "nstrumentation The eld instrumentation devices must be calibrated and installed prior to commissioning. "nstrumentation devices are initially inspected and calibrated in the shop, but nal calibration often takes place in the eld, in the installed conguration. Calibration set points are provided by the design engineer, or by the vendor. Calibration stickers are a)ed to the instrument after the eld calibration is successfully completed. 9oop Checks ( sensing instrument is tested by simulating a specic parameter, which is then converted to an electrical signal and displayed on the control system graphics.
?igure 7 The displayed parameter, scaling, and engineering units are conrmed at the panel display. The transmitter is then tested through a range of settings and certied as accurately tuned. 3any input signals to the plant control system are used to control various 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 signal conguration is known as a loop. There may be thousands of loops in a combined cycle plant, with the total number dependent upon the design philosophy and degree of automation. (larm, runback, and trip signals are all functionally tested during commissioning.
Commissioning of Combined Cycle Power Plants Part 3 $an Parker 3ar 7, 722D This is the third in a series of four articles on the commissioning of combined cycle plants. 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 $C Power and EP% %ystem The rst electrical system to be energi8ed during commissioning is the direct current +$C0 power system. %ometimes the pro!ect contract or specications re'uire the $C system to be load tested. The commissioning team rents load banks for this testing. The $C power system provides power to the switchgear circuit breakers, e'uipment protective relays, and emergency pumps +such as the steam turbine emergency lubricating oil and seal oil pumps0. $C voltage also powers an uninterruptible power supply +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 the charging process. (n eyewash station must be available for personnel safety. The battery room @oors are coated with an acid*resistant sealer. 4hen the $C system distribution system is energi8ed, testing of the (C switchgear and associated relays may begin. "nitial Plant :nergi8ation The initial energi8ation of switchgear is an important commissioning milestone. :nergi8ation of large, high voltage e'uipment such as the switchyard or the generator step*up transformer re'uires coordinated planning between the plant and the public utility. ( detailed procedure should be prepared, reviewed, and approved.
(t some plants, due to the pro!ect schedule, back feed power cannot be achieved in time to support the commissioning e=ort. 9arge diesel generators and transformers can be rented to provide temporary power. $istributed Control %ystem
?igure 1 Typical steps in the checkout of the distributed control system +$C%0# • • • • • • • • • •
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"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, the C: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 achieve optimum control. %chedule time should be allotted for this loop tuning.
"nstrument (ir The rst mechanical system to be started during commissioning is the instrument air system. ?or comple) air compressor congurations, the vendor should be present to assist in the startup. The controls for the compressor should be veried against the design.
3oisture traps on the discharge of the air compressor should be inspected very closely 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 instrument should be cleaned vigorously. (t add*on units where the e)isting unit will provide the instrument air, the new plant undergoing commissioning may draw more air than normal, because of the commissioning activities. This can !eopardi8e the operation of the e)isting facility. "n these 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 control systems. The vendor representative should be e)pected to work with the commissioning team until the system is running reliably in the automatic mode. The chemical analysis e'uipment needed to monitor the systems should be made available, and a suitable 5laboratory6 should be fabricated. (t some pro!ects, a rented cargo container suces for a temporary chemistry laboratory, with the various utilities connected. The following items should be completed prior to adding the resin to a deminerali8er vessel# The interior portions of deminerali8ers should be inspected. The regeneration control se'uence +valve stroking, pumps starts and stops0 should be thoroughly tested. The rinse water @ow rates and chemical dilution @ow rates should be ad!usted. (n eductor should be purchased, since most vendors re'uire that an eductor be used to sluice the resin into the vessels. 4aste 4ater Treatment 4hen the water treatment system is started, there is a corresponding need to get rid 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. • •
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(t some facilities, the waste water treatment system can be 'uite comple), such as at a 58ero discharge6 plant. This consists of multiple trains of reverse osmosis units, ltration systems, evaporators, concentrators, and lter presses. %ometimes the in@uent water to the plant is a 5gray water6 eIuent from a nearby sewage treatment facility. Then there are additional backwash lters, clariers, and lter presses. "t is vital that the manpower re'uired to commission and maintain big systems like these not be underestimated.
3ost plants incorporate some type of oily water separation. The separating device should be tested early in the startup se'uence, since invariably there will be some oil to process. ?ire $etection and Protection The installation subcontractor normally tests the re detection system, but the commissioning personnel must monitor the testing closely, in order to become familiar with the system. ?ire protection systems, such as sprinklers, deluge valves, and gas discharge systems may be tested by a subcontractor, or by the commissioning team. $epending on the !ob location, a government inspector or an insurance company inspector may need to witness the testing. ?ire pumps should be one of the rst pumps to be placed in service, after the water supply system makes water available. +(t some plants, the re protection water supply 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, which may be an indication that there is a leak in the re main, perhaps underground. The motor*driven or diesel*driven re pump should be placed in the automatic mode as soon as possible. "f the cooling tower is fabricated from wood, the associated re protection deluge valves should be placed in service as soon as possible. 3ake sure that post indicator valves have their indicators 5calibrated6 to show the correct position. Cooling 4ater Circulating water systems that use seawater need special care during the commissioning phase, due to the corrosive nature of seawater and the marine life and debris associated with seawater. The rakes, traveling screens, tube cleaning systems, and pump intake screens re'uire meticulous care during the commissioning phase, to prevent the introduction of debris into the condenser. 9arge circulating water pumps must be aligned carefully and accurately. $epending on the system design, the pumps may have a special valve that vents the air from the discharge column. %eal water for lubrication of the pump packing may have to be 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 and closed manually when starting the system. "f there is a water bo) priming system, it should be commissioned and placed in service at the beginning of the program. "f not, air pockets will build up in the water bo)es, and some tubes may not be lled with seawater. %ome plants re'uire throttling of the outlet valves on the water bo)es, to setup the proper @ow or pressure parameters. The water bo)es may have sacricial 8inc anodes. These anodes must be checked after the initial operation of
the system. The commissioning personnel must research these features prior to starting 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 with seawater. Cooling towers re'uire special monitoring prior to use. The spray no88les, distribution headers, and ll should be inspected before starting the system, and also sometime after the rst use, to make sure there are no problems created by the force of the water. Cooling tower fans should be checked for vibration, and their gearbo)es should be monitored for proper lubrication. "f the cooling tower has a place to mount corrosion coupons, the coupons should be installed prior to introducing water. ( wooden cooling tower should have its re protection system in service as soon as possible. &nce a wooden cooling tower is put in service, it should remain wet as much as practicable, so that it does not dry out and become a re ha8ard. %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. %pecial care is taken with the pump seal or packing. %ome pumps re'uire an e)ternal source of seal waterK the pump technical manual should be reviewed for this feature. "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, vacuum pumps, or a combination of the two. The startup engineer must monitor the various steam 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 air in*leakage. 3ake sure the seal water is installed. The condenser +or steam turbine0 rupture disc should be inspected closely prior to vacuum operations. %ome discs have to be installed in one particular direction. The area around the disc should not be accessible for personnel. The deaerator should be inspected before use, to make sure the trays are installed in the proper orientation, and that they are secure. The spray no88les should be left out, if not yet installed, or removed, if they have been installed. The deaerator should be inspected after the initial round of @ushing, to remove any debris that settled in the storage vessel, and to install the spray no88les. The deaerator should receive a nal inspection after the period of initial operation, to check the spray no88les and trays. The various types of feed water pumps need customi8ed care to ensure smooth operation. The pump suction strainer is very likely to plug when rst running the pump. The minimum @ow valve and any minimum @ow orice should be inspected to make sure they don/t cause too much @ow restriction for the pump. "f the pump has an automatic recirculation valve in the discharge, the valve should either be
removed for the initial operation, or +in some cases0 a special 5startup trim6 installed for initial operation. eat -ecovery %team enerator +-%0 ( few plants, which burn crude oil or some other heavy oil, have soot blowers. The alignment of the soot blower is critical to their smooth operation. (lso important is proper lubrication. %ome plants can run the combustion turbine solo, by means of a stack damper and a simple cycle stack, then later put the e)haust through the -% and out the main stack. The stack damper must be tested to ensure it operates in simple cycle mode without allowing any leakage into the -%. -%/s with hori8ontal tube bundles have recirculation pumps.
e)pansion of the gas causes the temperature to plummet precipitously, and free8ing can occur. 9i'uid ?uel (t some plants, a li'uid fuel, such as distillate, is used as a backup fuel for the combustion 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 close tolerances. %ome li'uid fuel tanks have @oating suction devices. This hardware should be inspected prior to lling the tank. (ny special coatings in the tank interior should also be checked. %iphon breakers on the tank should be disassembled, to make sure there are no shipping stops in the valves. The li'uid fuel unloading station should be checked for proper spill containment and re safety. (ir Conditioning and Aentilation (t many plants, the air conditioning and ventilation systems are seemingly abandoned after their initial start, because they are 5someone else/s6 responsibility. Therefore, a good commissioning team will monitor these systems, even if they are in fact some other organi8ation/s responsibility, because degradation of these systems 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 5p trap6 on the condensate, to allow the water to drain, but not allow un*ltered air to be drawn into the unit. "f there are troubles with the trap, it may cause water to back up in the unit. %ystem Checkout The remaining systems needed for running the combustion turbine and -% are tested on a system basis. The e'uipment is energi8ed, and the process @uid is put into the system. The various control circuits are checked, to verify controls and interlocks work as designed. 4here possible, the system parameters are ad!usted to produce 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 system valves are throttled to cause low @ow or low pressure conditions. "f a system has heat tracing installed on its pipes or instrument lines, and the weather predictions are for free8ing temperatures, make sure the heating supply is ready and the insulation is installed. The heat may be applied from steam or an electrical supply.
Combustion Turbine "n most plants, the commissioning of the combustion turbine itself is the responsibility of the turbine vendor. They provide specialists in the various systems of 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 oil pumps for the @ush. The oil should be puried before lling the reservoir, since brand new oil shipments have been received with debris in the oil. The turbine control systems also receive a temporary power supply, in order to checkout the circuits early in the commissioning program. The aim of the system commissioning period is to get the combustion turbine shaft rotating and ready for ring. %team Turbine The steam turbine is also commissioned by the vendor/s personnel, who are specialists in their area of responsibility. The steam turbine commissioning occurs later in the schedule, so permanent power is usually available for the steam turbine e'uipment. The lubricating oil @ush of the steam turbine is conducted in a manner similar to that of the combustion turbine. The goal of the system commissioning period is to have the turbine shaft on turning gear, with gland sealing steam applied and vacuum on the condenser. The steam turbine is then ready to admit steam. Thermal :)pansion
Commissioning of Combined Cycle Power Plants Part 4 $an Parker (pr 2B, 722D 1 &perational Testing ?irst ?ire The combustion turbine is ready for rst re after successfully completing control se'uence checks, cranking checks, emergency shutdown checks, false*re checks, and has been on turning gear for twenty four hours. &nce the combustion turbine is red, the hot e)haust gas will generate steam in the -%. The steam can be vented from the -% drums and superheater vents
during the initial rst re operation.
?igure 1 enerator %ynchroni8ation (fter a combustion turbine or steam turbine starts, its generator is connected to the utility grid to e)port power. The generator breaker is closed to the grid after synchroni8ing the voltage and fre'uency of the generator to the systemGs voltage and fre'uency. The generatorGs eld e)citation and speed are ad!usted until the voltage and fre'uencies of both systems are closely matched. The generator breaker is then closed, and the power output of the generator is increased by
raising the combustion turbine ring +or by raising the steam turbine steam admission rate0. ?ailure to accurately synchroni8e the generator to the grid before closing the circuit breaker may damage the generator. Protective relays detect any out*of*phase conditions and will not permit breaker closure. 4ater Ese $uring chemical cleaning and rst re operation, deminerali8ed water demands can e)ceed the water production rate and storage capacity. Chemical cleaning re'uires large 'uantities of deminerali8ed water for preparing the cleaning solutions and the subse'uent lling, @ushing, and rinsing of the piping and -%Gs. (t the time of combustion turbine rst re, fre'uent blowing down of the -% is re'uired to remove loose magnetite and achieve the steam purity necessary for steam 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 may be necessary on a temporary basis to augment the water production by mobile deminerali8ers. ;ormal <&P %ystems &peration (fter a balance of plant +<&P0 system checkout is complete, the system is placed in normal operation in a step*by*step fashion. This activity may take several days, and may re'uire fre'uent stops in order to perform inspections, make e'uipment ad!ustments, or review data. The following e)ample of the condensate and feed water initial startup demonstrates this process. •
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%tep N1# The condensate storage tank is lled with deminerali8ed water. Tank level indicator signals are veried at the $C%. %tep N7# The condensate make*up pump is started and placed in recirculation operation from the $C%. Pump suction pressure, discharge pressure, and suction strainer di=erential pressure are monitored. %tep ND# The condenser hotwell is lled using the condensate make*up pump. otwell level indicator signals are veried at the $C%. The control valve operation is checked, and then the controls can be placed in the automatic mode.
?igure 7 %tep NO# The condensate piping and the -% drums, economi8ers, and evaporators are lled via the condensate make*up pump cold ll line. %tep N# The condensate pump is started and placed in recirculation operation from the $C%. Pump motor amperage, thermal rise, and vibration are monitored. Pump suction pressure, discharge pressure, and suction strainer di=erential pressure are also monitored. %tep N# The condenser hotwell level controls are veried in both manual and automatic operation. %tep NH# Condensate @ows to the -% 9P economi8er and is recirculated to the condenser via the economi8er recirculation line +if such a recirculation line is included0. %tep NB# Condensate @ows through the 9P economi8er D*way valve bypass and into the 9P drum. The condensate is then redirected via the D*way valve into the economi8er and into the 9P drum. D*way bypass control is veried at the $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 valve operation 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 motor amperage, 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 normal leakage sites have been checked by site personnel, it is benecial to subcontract a specialist in condenser air in*leakage testing. These companies use helium detectors, installed at the air discharge of the condense air removal system, and they spray helium around the !oints, man ways, and @anges of the condenser and steam turbine. The helium detector can even be RcalibratedR to estimate the amount of leakage. The subcontractor can spot the source of the leakage in a matter of hours. •
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%hift 4ork 4hen the combustion turbines are red for the rst time, the commissioning team moves into shift work, with two or three shifts assigned for round*the*clock coverage. &n some pro!ects, the most e)perienced personnel are assigned to the night shift. %ince there are fewer workers on night shift to coordinate, and fewer distractions, the night shift can initiate new tests much easier than can be done on day shift. Test $ata "n preparing for testing, the startup manager prepares test log sheets and may also use $C% software logs that capture operational data. %oftware logs can be formatted to depict operating data graphically, displaying the dynamics of the system operation. %team Traps %team traps are deceptively simple components, which can cause big problems if they are not specied properly, or if they are installed incorrectly. The commissioning team should check the design features of the traps, to make sure they are installed with the correct range of pressures, temperatures, and back* pressures. They should also check the various piping runs, and verify that traps are installed at all the necessary points in the systems. $uring the system walkdown, the commissioning team should make sure the traps are installed in the proper orientation, and that the associated piping is routed correctly. (fter some period of operation, the traps which have internal strainers should be disassembled and cleaned. Plant &utages $uring the operation of the plant, there will be a collection of punch list items which re'uire the plant to be shutdown in order to perform the work. (lso, the startup schedule will include some known outage activities, like removing the strainers from the steam turbine inlet valves, or pulling the strainers from the combustion turbine fuel lines. The work should be scheduled !ust like a regular plant outage, with work permits arranged in advance, materials staged in the warehouse, and personnel assigned to the tasks. 4hen the predetermined time arrives for the outage, the work can then proceed smoothly. There should also be an ongoing list of punch list items that can be done during a short outage, so that if the plant is shutdown or trips without notice, some of those short work items can be accomplished. %pecial %ituations :mergency leak repair is sometimes warranted if there is a bad leak but you donGt want to shutdown the plant to ) the leak. ( leak repair subcontractor can be called to the site. They will make a temporary tting which can be applied around the leak,
and then they will pump a system*friendly compound into the tting to stop the leak. These leak repairs have been successfully employed on high pressure steam systems, circulating water systems, glycol cooling systems, and elsewhere. (nother techni'ue for making repairs on the run is to use a Rfree8e sealR to isolate an 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 the more dicult cases. -epairs on @anges or valves can often be performed by an Rin place 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 insist on good housekeeping from all the organi8ations on the pro!ect. Performance Testing The heat rate test is based on the engineered heat balances supplied by the plant designer. The net plant heat rate typically supercedes any individual combustion turbine and steam turbine guarantees and is calculated as
eat rate testing should be performed when the plant is in a new and clean condition with less than D22 hours of operation. 4hen this is not possible, the plant designer will supply heat rate degradation correction curves for calculating the ad!usted heat rate. (dditional correction curves are supplied to ad!ust the heat rate calculation to the guaranteed combustion turbine compressor inlet temperature, humidity, and barometric pressure +commonly cited as Qo ?, 2 relative humidity, 1O. psia barometric pressure0. The specied fuel gas heating value +
The heat rate test procedure will typically identify the temporary test instruments and permanent plant instruments that will be used to collect data. These instruments re'uire calibration certicates to validate their accuracy and tolerances. &f special importance are the electrical power output meter, the au)iliary electrical load meter, and the fuel gas @ow meter. 4henever possible, the data should be read on the actual plant revenue or billing meters, since these
meters will be used to pay fuel costs and to calculate the plantGs electrical sales revenues. :missions Testing -% stack emissions testing validates the emission limit guarantees. "n many plants, the combustion turbine e)haust gas nitrous o)ide +;&)0 reduction e'uipment will not satisfy the local environmental permit re'uirements, and it is therefore necessary to supplement the combustion turbine ;&) reduction e'uipment with an -% selective catalytic reduction +%C-0 unit. The combustion turbine e)haust enters the -% and passes through %C- modules located behind the high pressure evaporator modules. (mmonia is in!ected into the @ue gas, and it reduces the ;&) while on the catalyst surface. The ammonia decomposes ;&) into harmless ;7 and 7&, according to the reactions#
The stack ;&) is tested as ;&7 and measured in parts per million +PP30 by volume on a dry gas basis, corrected to 1 o)ygen. -% stack emissions testing may also 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 has been 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 testing may be performed in con!unction with the heat rate testing. owever, the emissions test may be conducted at several di=erent load points +2, H, 122 for e)ample, with and without duct burners0 on a one*hour average basis, while the heat rate testing may be performed at only one load point. Combustion turbine e)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 low as D. ppmvd +V 1 &70. • • • • •
Contract Testing The 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 each circuit0, 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 be lled. The system is dynamically tested by initiating a re alarm +via any of the heat
detection sensors0. The C&7 concentration is measured. The concentration test re'uires special e'uipment and is typically performed by the re system vendor. :lectrical ?ull*9oad -e!ection Test ( full*load re!ection test demonstrates the ability of each combustion turbine and the steam turbine to instantly shed their full*load, without tripping on overspeed, and then run down to full*speed*no*load. Combustion turbine full*load re!ection tests are conducted individually, one combustion turbine at a time. "n order to achieve full*load on the steam turbine both combustion turbines must be in base load operation. 4hen the steam turbine generator breaker is opened, the combustion turbines must runback to a preset lower load and begin dumping steam to the condenser via the steam turbine bypass. Control of this runback and bypass operation is a function of the $C% control logic. ( station trip test simulates a switchyard failure, wherein the combustion turbine generators and steam turbine generator are separated from the grid. "n this case, the steam turbine is tripped and the combustion turbines run back to full*speed*no* load. "n stations where there is no backup power, one of the combustion turbine generators may be congured to runback and later implement a safe shutdown. $uct
Turnover Packages The commissioning team maintains the system turnover packages during the commissioning phase, and the various records collected for each system are added to the packages during the commissioning. %ometimes an entire train of one combustion turbine generator and associated -% are turned over to the owner as one package. This type of turnover includes multiple system turnover packages being turned over simultaneously.
