Experience From Alstoms TPP26 Project in Moscow

Experience from Alstom’s TPP-26Project in Moscow: District Heating

with the KA26 Combined Cycle PowerPlant

Christian Bohtz, Stefan Jeken, Thomas

Experience from Alstom’s TPP-26 Project in Moscow:

District Heating with the KA26 Combined Cycle Power Plant

Conference Paper

POWER

Experience from Alstom’s TPP-26 Project in Moscow: District Heating with the KA26 Combined Cycle Power PlantChristian Bohtz, Stefan Jeken, Thomas Wunsch - Alstom Power - Baden, Switzerland

Russia Power 24-26 March 2010, Moscow, Russia© Alstom 2010. All rights reserved. Information contained in this document is provided without liability for information purposes only and is subject to change without

notice. No representation or warranty is given or to be implied as to the completeness of information or fitness for any particular purpose.




Experience from Alstom’s TPP-26 Project in Moscow: District Heating with the KA26 Combined Cycle Power Plant

Experience from Alstom’s TPP-26 Project in Moscow: District Heating with the KA26Combined Cycle Power PlantChristian Bohtz, Stefan Jeken, Thomas Wunsch - Alstom Power - Baden, Switzerland

Abstract .........................................................................................................................................21 The TPP-26 project .......................................................................................................................3

1.1 - TTP-26 Plant in Detail ................................................................................................................31.2 - Set-up of the Project ..................................................................................................................41.3 - Specialties of Joint Plant Engineering in Russia and Switzerland........................................................5

1.3.1 - Different Norms for Piping ...............................................................................................51.3.2 - Engineering Processes ......................................................................................................51.3.3 - Steel Work and Plant Arrangement ....................................................................................51.3.4 - Documentation and Certification ........................................................................................5

1.4 - Transportation of Gas Turbine and Generator .................................................................................62 Market situation in Russia ............................................................................................................7

2.1 - Use of District Heating................................................................................................................72.2 - Alstom’s EPC Capability in Russia .................................................................................................7

3 Alstom KA26 technology: Extraordinary high operational flexibility ............................................83.1 - Sequential Combustion ...............................................................................................................83.2 - Start-up Behaviour ....................................................................................................................93.3 - Large Operation Range and High Part-Load Efficiency .....................................................................93.4 - Low Load Operation Capability ...................................................................................................103.5 - KA26 for District Heating ..........................................................................................................103.6 - Alstom CCPP References in District Heating Applications ...............................................................103.7 - OEM, Plant Integrator and EPC capability....................................................................................11

4 Major Components and Systems ................................................................................................124.1 - Gas Turbine.............................................................................................................................124.2 - Steam Turbine .........................................................................................................................134.3- Generators ...............................................................................................................................144.4 - Heat Recovery Steam Generator.................................................................................................144.5 - Main Steam System ................................................................................................................154.6 - Condensing System ..................................................................................................................164.7 - District Heating System ...........................................................................................................164.8 - Fuel Gas Supply System ............................................................................................................164.9 - Instrumentation & Control (I&C) .................................................................................................16

5 TTP-26 Operation Modes............................................................................................................175.1 - Condensing Mode for Power Production .....................................................................................175.2 - District Heating Mode for combined Heat and Power Production ....................................................17

6 Summary.....................................................................................................................................17

TPP-26 Unit 8 is a combined-cycle power plant (CCPP), which is also usedfor district heating and is currently being constructed in Moscow, the capitaland economical centre of Russia.

The power plant is being built by Alstom and its consortium partner EMAlliance. It is the first Russian power plant to be built on the basis of a turnkeyengineering, procurement and construction (EPC) contract by a non-Russiancompany. The customer is OJSC Mosenergo, a public-joint stock companyand the biggest utility provider in the Moscow region. Notice to Proceed wasgiven in 2007 and erection works is coming to full swing.

The plant is based on Alstom’s KA26 combined cycle power plant in a one-on-one multi-shaft arrangement for high operational flexibility, comprising aGT26 gas turbine (GT), heat recovery steam generator (HRSG), steamturbine (ST) and two turbogenerators, whereas Alstom is supplying the keycomponents.

With the high operational flexibility and the operation range from 100%combined cycle load down to less than 40% load, the KA26 is ideally suited fordistrict heating, producing either 420 MW electrical power in full-condensingmode or up to 265 MWth heat in the highly-efficient district heating modewith a fuel utilisation above 85%. This flexibility as well as the superior part-load efficiency is achieved with the unique sequential combustion and3 variable compressor guide vanes of the GT26 gas turbine.

The new CCPP will be installed as unit 8 of the existing TPP-26 plant,increasing the total installed capacity from 1’400 to 1’820 MW.Synchronisation to the grid of the new power plant is planned in the secondhalf of 2010.

Utilising its Plant Integrator™ approach for designing and constructingturnkey EPC power plants and its experience gained from the engineering ofTPP-26, Alstom is able to offer optimised, tailor-made district heating powerplants utilising its in-house core components (GT, Generator, ST, HRSG,condenser, control system, ...). Alstom is therefore in a good position tosupport Russia, which has a demand to modernize its district heating powerplants, by both, brownfield and greenfield installations or repowering ofexisting steam power plants, reducing domestic fuel gas consumption tofoster export by increasing the efficiency of Russia’s district heating powerplants.

Abstract

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1 - The TPP-26project

The TTP-26 combined-cycle power plant is providing power and heat fordistrict heating. It uses Alstom’s proven and mature combined-cycletechnology based on the advanced class GT26 gas turbine, with more than1.5 million hours operating experience mainly in combined-cycle plants,including Co-Generation and also Repowering applications. The gas turbineand steam turbine are arranged in a multi-shaft configuration, each turbineprovided with its own air-cooled TOPAIR turbogenerator. In addition theblock features one HRSG, one water-cooled condenser, two steam/waterheat exchangers for district heating, and the auxiliaries required to operatethe plant. The unit’s control system is based on Alstom’s ALSPA DCStechnology.

It is anticipated that the plant will need to accommodate daily load variationsin the range between 50-100 per cent relative load. However, daily start-upand shut-down cycles are also envisaged, as is short-term plant operation atgas turbine loads down to 30 per cent. District heat extraction will be possible between 30-100 per cent of gasturbine load. The facility will be capable of operating at baseload without anyrestrictions in an ambient temperature range of -42ºC to 35ºC. Designambient conditions are ambient temperature (-3.1ºC), ambient pressure(995 mbar) and relative humidity (77%).

The plant is designed to operate principally with natural gas and oil as theback-up fuel. It complies with strict near-field and far-field noise guaranteeswhich are considerable more onerous than the industry ‘norm’ and belowthose stipulated in the contract for the plant’s metropolitan location.

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The cutaway schematicclearly shows both thegenerator block and the district heating systemof the high-efficiencyTPP-26 CHP plant

1.1 - TTP-26 Plant in Detail

The TPP-26 turnkey project is a consortium comprising Alstom Switzerland,Alstom Russia and EM Alliance: Alstom Switzerland is doing conceptualengineering, supplying key equipment (GT26 and steam turbine, each withgenerator and auxiliary systems and the ALSPA Distributed Control System(DCS), basic overall engineering and detail engineering for the GT and ST. Inaddition, it is also assigning technical consultants during engineering,construction and commissioning.

Alstom Russia is the consortium leader with the key management functions,assigning technical supervisors for erection supervision and commissioning.Alstom Russia is supplying the Heat Recovery Steam Generator (HRSG),designed according to Russian norms and regulations.

EM Alliance is providing detail-engineering, supplies the Balance of Plant(BoP) equipment and electrical equipment (step-up transformer, auxiliarytransformer and switchboard), as well as all commodities. EM Alliance isexecuting the civil and erection works, pre-commissioning andcommissioning together with Alstom.

OJSC “TEK-Mosenergo” as a sub-contractor to EM Alliance for detailengineering is providing necessary engineering resources, knowing thesituation in Mosenergo’s existing plants as well as country-specific Russianexpertise to perform detail engineering according to Russian norms andregulations.

1.2 - Set-up of theProject

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View of the TPP-26 turbine hall Compact arrangement inside the turbinehall: ST turbogenerator and lateral STexhaust at the front, GT at the back(with air intake on the right side)

1.3 - Specialties of JointPlant Engineeringin Russia andSwitzerland

1.3.2 - EngineeringProcesses

1.3.1 - Different Normsfor Piping

1.3.3 - Steel Work andPlantArrangement

1.3.4 - Documentationand Certification

With specific parts of the power plant being engineered in Russia, it waspossible to benefit from local engineering experience. Alstom in Switzerlandcal sourcing, GOST standard piping was used for the majority of the piping(For the main steam pipe work, ASME was used as no technical equivalentGOST piping was available). The use of GOST piping facilitated thecertification of the piping, as it was possible to use well-introducedengineering tools familiar to the Russian authorities. On the other hand, theinstallation of numerous transition pieces between the different pipe normsand European-supplied equipment was necessary.

In particular, the conversion of plant design according to ASME standards toa plant with Russian GOST standards needed to be considered. With some ofthe plant engineering performed in Russia and the benefit from localsourcing, GOST standard piping was used for the majority of the piping (Forthe main steam pipe work, ASME was used as no technical equivalent GOSTpiping was available). The use of GOST piping facilitated the certification ofthe piping, as it was possible to use well-introduced engineering tools familiarto the Russian authorities. On the other hand, the installation of numeroustransition pieces between the different pipe norms and European-suppliedequipment was necessary.

For Alstom, so called “fast-track” engineering, the parallel work oninterconnected systems and final consolidation has proven to be a timeeffective approach. However with a more step-wise approach in Russia,requiring more design data for a start of the detailed engineering, acceleratedengineering schedules are difficult to follow for tailor-made projects.

In particular the steelwork needed to be planned prior to the engineering ofthe piping, requiring additional time. The use of 3D piping and arrangementplanning was not yet widely introduced in Russia and Russian designerspartly do not use the benefits from 3D modelling in order to achieve anoptimised plant arrangement. Missing resources were compensated byAlstom, performing overall engineering management, integration of thedifferent engineering disciplines and review of all process relevant design byown staff, significant lowering the number of modifications duringconstruction.

The steelwork was planned based on Russian norms, that typically areheavier built than European design, requiring smaller margins due tocontinuously improved design tools. Deviating design concepts in Russiarequire additional supports to the steelwork resulting in numerousadaptations of pipe work against Alstom’s standard.

Having a long-time experience as EPC provider in many countries, Alstomwas also able to consider the specialties of the Russian legislation for thedocumentation and certification of the plant. With the experience from theTPP-26 project, Alstom can now benefit for future projects in Russia.

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1.4 - Transportation ofGas Turbine andGenerator

Transportation of GTthermal block indisassembled conditionon a barge

Alstom already evaluated the transportation of the heavy plantcomponents prior to the start of the project: The generators and the gasturbine were too large for rail transport. Due limited navigability of theVolga channel system between November and April, even airfreight wasconsidered at the beginning.

Weight limitations for road transportation in Moscow posed anadditional challenge. The GT had to be transported in disassembledcondition and also the rotor of the GT generator needed to be removedand reassembled on site.

Finally the GT was shipped from the factory in Mannheim via the riverRhine to Rotterdam and loaded on a heavy lift vessel to St. Petersburg.From St. Petersburg the equipment was shipped on barges through theVolga channel system to Moscow with a transit time of 20 days for1’542 km! In Moscow, the bearing weight capacity of two bridges needed to beinvestigated in order to get permission for the 20 km heavy lift transportfrom the South River Port to site.

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2.1 - Use of DistrictHeating

2.2 - Alstom’s EPCCapability in Russia

2 - Market situationin Russia

Russia has the largest district heating system in the world. Districtheating plants as TPP-26 provide more than 70% of the heat supply. Inlarge cities between 70% to 95% of the homes are connected to districtheating systems, whose total length amounts to 200’000 km. Around30% of the supplied heat is produced in close to 500 Combined Heat andPower (CHP) plants. The rest is produced in more than 65’000 mainlygas-fired boiler houses.

With an average lifetime above 20 years, mainly using natural gas atlower efficiency (< 38%), there is a large potential for new CHP plantsthat offer fuel utilisation factors up to 90% and above. Also re-poweringis an attractive option for such plants: With the installation of a new GTand a new HRSG, the existing steam turbine and its foundation andauxiliary equipment can be maintained.

Alstom is building the TPP-26 combined-cycle power plant (CCPP) onturnkey-basis, and as an Original Equipment Manufacturer (OEM),Alstom is also providing all main plant components.

Alstom has fully established the required local organisation andresources to execute such projects, including a Russian legal entity.Alstom’s organisational setup, having his headquarter in the centre ofMoscow, is taking care of the full product range, from consulting andservice up to EPC plant delivery. For any required technical expertise,Alstom can benefit from the know-how of over 50’000 employees in itsPower Sector to provide any support required.

Depending on customer requirements, Alstom can provide power plantequipment, full turnkey combined-cycle power plants or repowering ofexisting steam plants with a new GT and HRSG, maintaining the steamturbine or including an upgrade of the steam turbine. Alstom is thereforein a good position to support the modernisation and expansion of thelarge Russian power generation fleet.

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For the TPP-26 project, Alstom was offering the most effectivecombined-cycle power plant technology in its class. Alstom as designer,manufacturer and supplier is providing the key equipment from a singlesource. One of the key project drivers of the Unit 8 contract was a largereduction in gas consumption. In the first year of operation alone thistranslates into a $55 million saving (based on 2011 expected gasprices).

Alstom has integrated its heavy-duty GT26 gas turbines into anoptimized single-shaft or multi-shaft combined-cycle generating block –the KA26 Reference Plants. In the mid-1990s, Alstom introduced twosimilar sequential combustion gas turbines, the GT24 for the 60 Hzmarket and the GT26 for the 50 Hz market. Since their launch, theseadvanced class GT24/GT26 units have demonstrated that thistechnology platform offers significant advantages to plant operators –superior operating flexibility, low emissions, high part-load efficiencyand world class levels of reliability being amongst them.

These benefits are brought about by utilizing the concept of sequentialcombustion: The GT26 combustion system is based on the well-provenAlstom combustion concept using the EV (EnVironmental) burner in afirst annular combustor followed by the SEV (Sequential EnVironmental)burner in the second combustor. The dry, low NOx EV burner has a longoperating history and is used across the whole range of Alstom gasturbines.

About 50 per cent of the total fuel (at baseload) is burned in the firstcombustion chamber. After this the combustion gas expands throughthe single stage, high-pressure (HP) turbine, which reduces the pressureby approximately a factor of two. The remaining fuel is then added in thesecond combustion chamber, where the combustion gas is heated asecond time and finally expanded in the four-stage low-pressure (LP)turbine.

Utilizing sequential combustion, the GT24/GT26 design is able toachieve a high power density in a compact unit with a small footprint.

TPP-26 Unit 8 will burn either natural gas or, as a back-up, liquid fuel.With a rated output of 266 MW at an ambient temperature of 15ºC, theunit will have an exhaust gas flow rate of 620 kg/s, leaving the turbineat a temperature of 625ºC. At that point it will enter a three-pressurereheat, horizontal type HRSG, which is capable of generating steam inany operation state of the gas turbine. From there the steam enters thethree casing steam turbine.

3 - Alstom KA26technology:Extraordinaryhigh operationalflexibility

3.1 - SequentialCombustion

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The advanced KA26 combined cycle power plant technology and thesequential combustion of the GT26 gas turbine offer a number of keyadvantages:� excellent start-up characteristics for hot, warm and cold starts� operational flexibility from 100 per cent down to 40 per centcombined-cycle power plant (CCPP) load and below

� high part-load efficiency � low NOx emissions down to 40 per cent CCPP load and below� extremely low ‘parking load’ during off-peak periods at about 20 percent CCPP load

� a very good fuel flexibility capability with regard to varying natural gascompositions.

The start-up behaviour of a power plant is determined both by the start-up time and the reliability.

With the optimal plant concept it has been shown that the KA26combined-cycle baseload can achieve a hot start within 50 minutes(i.e. after about an eight hour shut-down). This is achieved without anauxiliary boiler or other special steam conditioning equipment. Suchshort start-up time means the plant is able to supply power sooner andtherefore earn money for its owner. This ability is an importantadvantage in a market environment with a volatile electricity price. Itallows the operator to take opportunities with minimal time delay.

Secondly, Alstom’s monitoring of its KA24/KA26 fleet has demonstrateda start-up reliability of more than 95 per cent. This is again importantbecause a missed start can be extremely expensive in terms of buying inthe previously committed power. There may also be further benefitssuch as revenues from non-spinning reserve payments.

The short start-up times and high start-up reliability thus have theability to boost revenue for customers, compared to CCPPs using othertechnologies.

The KA26 power plant has a large operation range from 100% down toless that 40% CCPP load. Superior part-load efficiency is achieved withthe combination of the sequential combustion system (2 combustionchambers) and three rows of variable compressor guide vanes tomaintain a high GT exhaust temperature with partially closedcompressor inlet guide vanes.

High part-load efficiency is important to achieve high operationalflexibility: Even in case of lower power demand or low electricity prices,the plant operator can continue to operate the plant at reduced poweroutput without sacrificing substantial efficiency.

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3.2 - Start-up Behaviour

3.3 - Large OperationRange and HighPart-LoadEfficiency

Therefore the number of starts is reduced, decreasing the associatedstarting costs.

Alstom’s KA26 plant has the unique Low Load Operation Capability(LLOC): The plant can be operated at approx. 20% CCPP load, with thesteam turbine remaining in operation. With only the first combustionchamber in operation, low NOx can be maintained. From the LLOCmode, plant baseload can be reached in less than 30 minutes as thesteam turbine remains in operation.

With the low fuel gas consumption of the LLOC, the plant can remain inoperation at even lower electricity prices – ready to load up immediately.Therefore the lifetime consumption that is related to the number ofstarts of the gas turbine can be controlled by freely choosing whetherthe gas turbine is shut-down during low price periods, or not. This offersan important advantage, which significantly increases the flexibility inoutage planning. Furthermore, the high part-load efficiency indirectlyallows control of the starts reduces the absolute emissions producedduring start-up.

In particular for district heating plants, Alstom’s plant integrationcapability based on the Plant Integrator™ approach brings a bigadvantage for a customer, as the plant is fully optimized and tailor-madebased on Alstom’s engineering capabilities and experience with districtheating plants. As an OEM, Alstom can even adapt the main plant components andoffer customised steam turbine and district heater designs in order tosupply the optimum district heating plant solution.

In particular the GT24 and GT26 are very well suited for Co-Generation,as they have been designed for combined-cycle applications in KA24 andKA26 plants.The large load range from 100% down to less than 40% plant load is a bigadvantage for Co-Generation – and with sequential combustion and3 variable compressor guide vanes, superior efficiency can be achievedeven in part-load operation.

Beside of the large number of conventional CCPP, Alstom has built overthe last 30 years a dozen plants in district heating applications. Theseplants were based on the entire Alstom gas turbine portfolio, both for50 Hz and 60 Hz, including the GT8, GT11, GT13E2 and most recentlythe GT26 at TTP-26.

An example for the KA13E2 is the Diemen plant in the Netherlands thatwent into operation in 1995. Same as the TTP-26 plant, this plant wasbuilt on turnkey-basis.

3.4 - Low LoadOperationCapability

3.5 - KA26 for DistrictHeating

3.6 - Alstom CCPPReferences inDistrict HeatingApplications

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3.7 - OEM, PlantIntegrator and EPCcapability

Bird view of the TPP-26plant-layout: Full indoor arrangementincludes HRSG and water pumps

In power production mode, it is providing 253 MWe at an efficiency of55.5%. In district heating mode, it is providing 193 MWth heat and228 MWe power with a fuel utilization of 87%.

Alstom is one of the few OEMs in the market able to offer all the majorpower generation technologies in-house; bringing together theknowledge and expertise of the ‘architect-engineer’, or EPC contractorwith those of an OEM. With the in-depth knowledge of the main powerplant components, Alstom can integrate them into a fully optimizedplant.

With this approach, Alstom has the appropriate capabilities, the requiredskills and credentials to contribute significantly to power expansion andreplacement capacity needs in precisely the way currently beingundertaken in Moscow. Moreover, this approach is highly conducive tomeeting the increasing demand globally for EPC turnkey solutions.

This comprehensive approach to turnkey EPC includes performance andschedule guarantees, warranties and assurances encompassing theentire scope of the plant, rather than being limited to individualcomponents or packages, reducing the end-user risk significantly.

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The GT26 type gas turbine consists of a solid welded rotor with22 compressor stages, one HP turbine stage and four LP turbine stages.Heat input is performed by two annular combustion chambers(EV & SEV burners).

The rotor is rigidly coupled to the generator shaft. The airflow throughthe gas turbine is controlled by the angular position of three variableguide vane (VGV) rows. During part-load above the 25 per cent gas turbine load, the turbinecontroller maintains the exhaust gas temperature at the maximum part-load temperature by opening the VGV and increasing fuel injection toboth combustors.

4 - MajorComponents and Systems

4.1 - Gas Turbine

GT26 thermal block

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4.2 - Steam Turbine

For cooling and sealing purposes, air is drawn off the compressor at anumber of stages. Two airflows are cooled external to the gas turbine –one flow by an HP and the other by a LP air cooler referred to as a ‘oncethrough cooler’. These coolers are producing additional steam, whichresult in additional power produced by the steam turbine.

An anti-icing and air prewarming system based on a heat exchanger isprovided in order to preheat the air during icing conditions, enabling thenormal operation of the gas turbine.

For the steam turbines, Alstom can select from a large portfolio of steamturbines optimised for use in combined cycle power plants and rangingup to 400 MW. Several configurations in singe and two casing turbines,for backpressure and condensing-extracting operation are available.

The Alstom STF15C used at the TPP-26 plant consists of one reheat typesingle flow HP chamber, one single flow IP (intermediate pressure)chamber and one double flow LP chamber. The turbines are rigidlycoupled. HP live steam enters the HP turbine through a single valveblock, consisting of one stop and one control valve, and is expanded toreheat pressure. The cold reheat steam is mixed with the IP steam,generated in the HRSG, and reheated. The hot reheat steam enters theIP turbine via two intercept valve blocks, each equipped with a one stopand one control flap, where it is mixed with the IP steam before enteringthe LP turbine. The outlet steam of the LP turbine is discharged to thewater-cooled condenser.

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GT filter house withintegrated anti-icing andair prewarming systembased on a heatexchanger

The IP steam turbine is equipped with extractions for district heatingoperation. Steam for the district heater DH1 is drawn off from the IPexhaust. District heater DH2 receives steam from the IP steam turbineat an intermediate stage. During pure condensing mode, a minimumamount of steam is flowing through the last stages of the IP turbine inorder to prevent ventilation, and discharged into an intermediate state ofthe LP steam turbine.

The GT26 is driving an Alstom TOPAIR generator producing electricity at19 kV, while the steam generator drives a TOPAIR generator at 15 kV.The generators are of a two-pole, three-phase synchronous design. Thehot air is re-cooled in heat exchangers located in the generator housing.The heat is transferred into cooling water and rejected to atmospherethrough a remote cooling system.

The gas turbine-generator is equipped with a static frequency converterfor using the generator as a synchronous motor. During start-up, thestarting energy is provided via redundant connection from the stationservice transformers by the high voltage (HV) grid across the generatorstep-up unit transformer.

In the HRSG, the exhaust energy from the Gas Turbine is used toproduce steam.

At TPP-26, a single, horizontal type HRSG, triple pressure reheat unitoperates in natural circulation mode for the LP, IP and HP systems.

A simplified flowdiagram of the TPP-26combined-cycle CHPplant

4.3- Generators

4.4 - Heat RecoverySteam Generator

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GG

CLOSEDCOOLING

WATER LOOP

FORCE COOLED COOLING SYSTEM

Steam

Water

Cooling water

Fuel

DEMINWATER

CONDENSER

FEEDWATERTANK

HRSG

TO GT COOLINGAIR COOLERS

FROM GTCOOLING

AIRCOOLERS

COOLING TOWERBLOWDOWN WATER

LP STEAMHRSG

STEAMTPP 26

AUX. NETWORK

AIRINLET

ANTI ICING AIRPRE-WARMING SYSTEM

GT26 GAS TURBINE

FUEL OIL

NATURAL GAS

COLD REHEAT

LP HRSG

IP HRSG

HOT REHEAT

HP HRSGSTEAM TURBINE

TODISTRICT HEATING

NETWORK

CITY HEATER

FROMDISTRICT HEATING

RETURN

4.5 - Main SteamSystem

Heat discharged from the gas turbine as hot exhaust gas serves as theheat source to produce superheated HP, IP and reheat steam andsuperheated LP steam.

The HP/IP feedwater pumps feed the HRSG, which the LP feedwater isextracted downstream of the second row of IP/LP economizers. Thefeedwater flows are pre-heated in the respective economizers andadmitted via control valves into the HP, IP and LP drums. Saturatedsteam is generated at the HP, IP and LP evaporator.

The HP steam is led to the multi-stage HP super-heater, the IP steam tothe IP super-heater and subsequently to the re-heater. The LP steam issuper-heated also. At the outlet of the HRSG, the HP and re-heat steamare attemperated with feedwater extracted from the HP economizerfeedwater line and IP economizer section. This mixing line is equippedwith a manual valve, which can be adjusted during commissioning.

A blow down tank collects the drains of the HRSG and the drains of thesteam turbine external steam system, which are located near the HRSG.After separation, steam is discharged to atmosphere and condensate isdischarged to the wastewater system.

Alstom produces a broad range of HRSG technologies and designs, formedium, large and very large gas turbines, designed to any standardcode (ASME, EN, GOST, IBR, etc.), based on natural circulation,controlled circulation or once-through technologies.

Alstom’s HRSGs are optimised for cyclic operation, as required forCo-Generation. Improved features include single row harps, steppedcomponent thickness, an optimized drain system and a high level ofpre-fabrication in Alstom workshops requiring minimal site welding.All together, this leads to less leakages and higher availability.

The main steam system consists of the HP steam line, the cold re-heatsteam line, the IP steam line and the LP steam line. The HP steam linetransfers the HP steam produced in the HRSG to the HP section of thesteam turbine.

The HP steam is expanded in the steam turbine and released into the coldreheat steam line. When the steam turbine is not in operation, the HP bypassguides the HP steam into the cold reheat steam line. The cold reheat steam linetransfers the cold reheat steam back to the HRSG, where it is re-heated andmixed with the IP steam. Steam is taken from the cold reheat steam line forthe supply of the air removal system and the gland steam system. It alsosupplies the auxiliary steam header with steam and acts as a secondary supplyof the high temperature cogeneration heater.

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This is a horizontally arranged two-pass condenser, cooled directly usingwater from the cooling tower. Non-condensable gases on the steam sideare extracted at a defined point of every tube bundle with the lowestpressure – the so-called ‘air coolers’.

The district heaters (DHs) consist of surface heat exchangers. Districtheating water enters the inlet water box of the first heater, flowsthrough the tubes and leaves the heater via the outlet water box. Then itpasses through the second district heater in much the same way.Condensing heater DH2 is fed with steam turbine extraction steam,while the condensate from it drains into DH1 through an expansiondevice. The condensing and sub-cooling heater DH1 is fed with cascadecondensate from DH2, steam turbine extraction steam and with hotfeedwater from the HRSG. The hot water from the HRSG drains into theheater through its expansion device. Cooled condensate from the heater DH1 leaves the heater via the heatercondensate extraction pumps, of which there are four.

Fuel gas is delivered to the plant by a pipeline. Because of the highvariability in supply pressure and quality of the feed gas, it has to betreated or conditioned before it can be fed to the gas turbine fuel gasblocks. The fuel gas enters the plant via the main gas inlet valve andpasses the redundant gas scrubber units. Separated condensate iscollected in a skid and returned to the client systems. A redundant fuelgas compressor system increases the gas pressure from a minimum ofonly 10 bar to the needs of the gas turbine. In this way, gas pressure iscontrolled by a dedicated system of recirculation.

The I&C system permits the safe running and supervision of the wholeCHP plant. The unit’s control system is based on Alstom’s ALSPA DCStechnology. Alstom’s scope of work covers the control and monitoring ofthe gas turbines, water and steam cycle, HRSG, steam turbine, all theauxiliaries, and steam turbine generator, including the electricalequipment.

4.6 - Condensing System

4.7 - District HeatingSystem

4.8 - Fuel Gas SupplySystem

4.9 - Instrumentation& Control (I&C)

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5 - TTP-26Operation Modes

5.1 - Condensing Modefor PowerProduction

5.2 - District HeatingMode for combinedHeat and PowerProduction

These are loosely divided into ‘Condensing Mode’ and ‘District Heating’modes. Both are considered in the plant automation and are designed tobe selectable by the plant operator through a human machine interfacemodule.

In this operating mode the exhaust steam from the HP steam turbine isre-heated in the HRSG and directed into the IP steam turbine, passing acrossover line into the LP steam turbine, and finally condensed. In thismode, the steam extraction control and check valves are closed, hotcirculated feedwater is returned to the feedwater tank, the DH watercontrol valve is closed and the DH condensate pumps are out ofoperation. The load of the power plant is controlled according to the gridrequirements (i.e. electric load/frequency).

In this operational mode, the plant is providing both power and heat fordistrict heating. The steam turbine is in operation, with the steamextraction control and check valves open, hot circulated feedwater isbeing fed into the DH1, the DH water control valve is open and the DHcondensate pumps are in operation.

District heating network operators will determine the water flow andheater outlet temperature in accordance with the required heat load.The DH flow controller will throttle the DH water control flap accordingto requirements.

The KA26 combined cycle power plant currently under construction atthe TPP-26 project in Moscow is the ideal plant for district heating: Itprovides a large operational flexibility with an operation range from100% combined cycle load down to less than 40% load at superior part-load efficiency. The plant can either provide 420 MWe power or up to265 MWth heat for the district heating system.

With this project, Alstom has gained experience in the execution ofturnkey-power plants in Russia. Utilising its Plant Integrator™ approachfor designing and constructing turnkey power plants, Alstom is able tooffer optimised, tailor-made district heating power plants based on itsin-house core components (GT, generator, ST, HRSG, condenser, controlsystem, ...).

The necessary local organisation, combined with the long-termexperience in power generation puts Alstom in a good position tosupport Russia, which has a demand to modernize its district heatingpower plants, by new greenfield and brownfield installations orrepowering of existing steam plants.

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6 - Summary

Alstom Power

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Experience From Alstoms TPP26 Project in Moscow