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National Technical University of AthensMechanical Engineering Department
Thermal Engineering SectionLaboratory of Steam Boilers and Thermal Plants
9 Heroon Polytechniou STR, Athens 15780 - Greece
Title of Project :
Concept study for a 700C power plant: using poor quality
brown coal with ultra supercritical PF boiler
Sub - Contract to VGB
Final Report
covering NTUA-LSBs activities from 1/1/2006 to 31/10/2006
Compiled by
Prof. Emm. Kakaras, Dr. A. Doukelis, Dr. Pan. Grammelis,
Mr. A. Koumanakos, Mr. M. Agraniotis
Athens, October 2006
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Summary
Main topic of the present study is the investigation of the conceptual design for a700oC power plant burning exclusively low rank coal, such as the Greek brown coal.Although significant progress can be reported on the component materialdevelopment and the plant design of the 700 oC technology, the main fuel taken intoconsideration is hard coal or high quality brown coal and no investigations have been
performed for the case of low rank coals. This gap is covered by the present work.Alternative plant configurations for the low rank coal - fuel scenario are analysedand compared in terms of efficiency, auxiliary power consumption and net poweroutput. The technical analysis is followed by a survey on the funding opportunities forthe demonstration of the 700 oC technology in Europe and the United States and a
presentation of the current research priorities in the field of thermal power plants inthe EU.More specific, the first part of the study contains an overview on the progress in the700C technology. The development of new materials (Ni based alloys), which will
allow main and reheat temperatures to be raised up to the 700
C region and mainpressure to the 350-375 bar, resulting to an efficiency increase of 5-6 percentagepoints, are the main targets towards the new generation of pulverised fuel plants. Thecurrent research activities in EU, US and Japan in the particular field are reported inthis section. The second part focuses on the different predrying concepts for theutilization of fuels with high moisture and ash content. It is assumed that pre dryingwill be a critical step, especially for low rank coals, in order to reach high furnacetemperatures necessary for the 700C steam conditions. Different predrying methodsare presented and compared in terms of thermal consumption and efficiency. The third
part includes the main case study of two different designs for a 700C power plantburning low rank coal and their comparisons with the equivalent steam cycles of
conventional plans. An estimation of the expected efficiency gain and the modifiedcapital cost is further presented. In the two final parts the funding possibilities for thedemonstration of the 700C power plant technology through European andinternational organizations and funds are reported. A comparison of the particularconcept with the current research priorities of the E.C. in the field of thermal power
plants is included. The findings from the Working Groups in the Technology Platformfor Zero Emission Fossil Fuel Power Plants (ZEP) are finally used in order toelaborate convincing arguments for the necessity to implement the 700C technology,encouraging its funding through the 7th FP.
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Kurzfassung
Thema der vorhandenen Studie ist die Untersuchung eines Designkonzepts fr einKraftwerk mit ultra berkritischen Dampfparametern und Einsatz von minderwertigerBraunkohle, wie die griechische Braunkohle. Obwohl es bei der Entwicklung derKomponentenmaterialien und des allgemeinen Kraftwerksdesigns fr ein 700 oCKraftwerk ein signifikanter Fortschritt zu sehen ist, bleibt als bercksichtigterReferenzbrennstoff die Steinkohle oder die Rheinische Braunkohle und keineUntersuchung wurde bis zu dieser Zeit fr den Fall einer minderwertigen Kohledurchgefhrt. Ziel der vorhandenen Arbeit ist diesen Mangel zu decken. AlternativeKonfigurationen des minderwertige Kohle - Szenarios werden bercksichtigt und
berechnet und unter den Aspekten des Effizienzgrades, des zustzlichenLeistungsverbrauchs und der Nettoleistung vergliechen. Nach der technischen Studiewird eine Recherche ber die Finanzierungsmglichkeiten einer Demonstration der700 oC Technologie in der EU und den USA presentiert und eine Darstellung deraktuellen Forschungsprioritten im Bereich der thermischen Kraftwerke in EU
eingegeben.Der erste Teil der Studie beinhaltet einen berblick auf die aktuellenForschungsergebnisse im Bereich der 700 oC Kraftwerkstechnologie in der EU, denUSA und Japan. Die Entwicklung neuer Materialien (Ni-basierte Legierungen), dieDampftemperaturen von 700 oC und Drcke von 350-375 bar erlauben, was zu einerErhhung des Effizienzgrades von 5-6 Prozent fhren wird, ist das Hauptziel fr dienexte Generation der konventionellen fossilen Kraftwerke. Der zweite Teilkonzertriert sich auf die verschiedenen Vortrocknungskonzepte fr die Ausnutzungvon Brennstoffen mit hohem Asche - und Wasseranteil. Man erwartet, dass dieVortrocknung, besonders fr die minderwertigen Kohlen, ein kritischer Punkt fr dasErreichen der bentigten hohen Brennkammertemperaturen und der entsprechenden
erhhten Dampfparameter sein wird. Verschiedene Vortrocknungsmethoden werdenangegeben und bezglich des thermischen Verbrauchs und der Effizienz vergliechen.Der dritte Teil beinhaltet die Darstellung von zwei berechneten Designkonzepten frein 700 oC Kraftwerk mit Einsatz von minderwertiger Braunkohle und derenVergleich mit den Dampfkreislufen heutiger konventioneller Kraftwerke. EineAnnahme der erwarteten Effizienzsteigerung und der genderten Kapitalkosten wirdauch angegeben. In den zwei letzten Teilen wird es ber dieFinanzierungsmglichkeiten der Demonstration der 700 oC Kraftwerkstechnologiedurch europische und internationale Institutionen und Funds berichtet. Ein Vergleichdes betrachteten Forschungsthemas mit den aktuellen Forschungsprioritten der EUwird einbezogen. Die Erkenntnisse der Arbeitsgruppen der Technology Platform for
Zero Emission Fossil Fl Power Plants (ZEP) werden genutzt, um berzeugendeArgumente fr die Notwendigkeit der Implementierung der 700 oC Technologieauszuarbeiten, und deren Frderung durch das 7. Rahmenprogramm (7th FP) zu
bestrken.
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CONTENTS
1. Introduction 32. Analysis of the current achievements of R&D projects addressing
key issues of the 700C technology.
3
3. Fuel handling issues introduction of predrying technologies (eg.WTA) for lignite and integration into the steam cycle
10
4. Initial layout and design of the 700C plant using pulverized lignite,Balance of Plant, estimated efficiency and generation costs.
15
5. Analysis of public funding possibilities to sponsor the particulartechnology (Article 169, RFCS, Framework Program, EIB, DoE)
23
6. Comparison of this technology with the Research Priorities of theEC.
27
7. Conclusions 298. References 30
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1. IntroductionIt is generally expected that coal will continue to play a key role in the future energy mix as
the most abundant and cheapest fossil fuel source. The higher stability of the coal marketcompared to the oil and natural gas market, guarantees stable electricity costs, which couldntbe achieved without the utilization of coal as the main fuel for electricity production.However, as the global climate change and the Kyoto-protocol impose a reduction of the CO2emissions produced from fossil fuel power plants, the increase of their efficiency and theminimization of their emissions become the main challenges for the power producers and themanufacturers. Towards this direction the research effort is focused on the development ofcomponent materials for a 700 oC ultra super critical power plant and the optimization of thesteam cycle and the overall process diagram. Although these examinations have been carriedout for reference plants burning hard coal or Rheinish brown coal, the case of using low rankcoals as fuel, such as the Greek brown coal, has not been examined yet.
The aim of this study is therefore the investigation of the conceptual design for a 700o
Cpower plant burning exclusively low rank coal, such as the Greek brown coal. In this way, thepotential to deploy the 700 oC plant technology for a wider fuel matrix, apart from the onesalready examined increases. Within the study, possible funding opportunities are seeked,which may contribute to the realization of the first demonstration plant in a closer time
perspective.The first part of the study contains an overview of the technological achievements and theresearch and demonstration projects on the main aspects of the 700C plant technology, suchas the development of new materials and component designs. The main R&D activities inUSA, Europe and Japan are described. An introduction on the brown coal pre dryingtechnologies is given in the second part of the study. It is assumed that the pre drying will be a
critical step in order to reach high furnace temperatures necessary for the 700C steamtemperatures. Especially, in the case of low rank coals pre drying may be proven as a required
process to achieve the target temperatures. In the third part two initial layouts of a 700Cpower plant are presented and compared with the equivalent process diagrams of conventionalplants. The results provide an estimation of the expected efficiency gain and estimations aboutthe capital cost. In the last two parts, attention is being given on the possible means of fundingthe demonstration of the 700C power plant technology through international and Europeanorganizations and funds. A comparison of the technology with the current research prioritiesof the E.C. in the field of thermal power plants is also included.
2. Analysis of the current achievements of R&D projects addressing key issues of the700C technology.
The main objective of this task is to summarize the results attained from research activities inEurope and world wide on the next generation of Ultra Super Critical (USC) power plants.Possible ways of improving the efficiency of conventional power plants by raising the steamcharacteristics through the use of new materials have been investigated in Europe, Japan andUSA since the early 90s. A comparative study of the Clean Coal Centre (IEA) [1] betweenthe different CO2 abatement concepts for existing coal power plants showed that, increasingsteam temperature and pressure to Ultra Super Critical parameters may bring a significantefficiency gain compared to a conventional subcritical plant, Table 1. Moreover the concept
of upgrading the thermodynamic characteristics of conventional steam cycle power plants is
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proven to be comparable with other new and more sophisticated plant concepts, such as theIGCC and the PFBC plants.
Table 1: CO2 abatement in existing coal-fired plants, Source [1]
Technology Net plant
efficiency% LHV
CO2 emission
factorgCO2/kWh
CO2
reduction%
Conventionalsystems
PulverizedCoal
Reference Plant 36 953,3 0
Subcritical Steam 39 876,3 8
Supercritical steam 42-45 759-814 15-20
Ultra-supercriticalsteam
47 744,3 22
AFBC Subcritical Steam 39 880 8CombinedCycles
IGCCDemonstratedsystems
38-45 755,3-894,7 8-22
PFBC Subcritical Steam 42 814 15
Supercritical steam 44 777,3 18
Fuel blendingPulverisedCoal
Subcritical steam,coal / natural gas(85/15)
37 869 9
Subcritical steam,
coal / oil (47/53) 36 836 12
Subcritical steam,coal / biomass(80/20)
36 759 20
AFBCSubcritical steam,coal / biomass(50/50)
39 440 53-54
2.1 Overview of the technological progress
The plants efficiency increase in the last years was based on the progress of new hightemperature resistant materials. The development of the 9% Cr steels P91 and P92 in the late80s and 90s was the result of an international effort and allowed the increase of steam
parameters to the range of 300bar and 600C. The new generation of the 600C power plants,has showed a satisfactory performance in terms of reliability, flexibility, efficiency andeconomy [2]. The recent 600C power plants are presented in Table 2.
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Table 2: Recent 600C power plants, Source: [2]
Power Station Capacity(MW)
Steam parameters Fuel Year ofcomm.
Eff. (%)
Matsuura 2 1000 255bar/598C/596C PC 1997
Skaerbaek 3 400 290bar/580C/580C NG 1997 49
Haramachi 1000 259bar/604C/602C PC 1998
Nordjylland 400 290bar/580C/580C PC 1998 47
Nanaoota 700 255bar/597C/595C PC 1998
Misumi 1 1000 259bar/604C/602C PC 1998
Lippendorf 934 267bar/554C/583C Lignite 1999 42.3
Boxberg 915 267bar/555C/578C Lignite 2000 41.7
Tsuruga 2 700 255bar/597C/595C PC 2000
Tachibanawan2
1050 264bar/605C/613C PC 2001
Avedore 400 300bar/580C/600C NG 2001 49.7
Niederaussem 975 265bar/565C/600C Lignite 2002 >43
Isogo 1 600 280bar/605C/613C PC 2002
The further development of the ferritic steel materials has reached however an uppertemperature limit in the range of 610-630C, the steel barrier. In order to reach the 700-720C/ 350-375bar steam characteristics, new Nickel based superalloys, known from the gasturbine- and nuclear reactors- technology, are being further developed. In comparison with thecurrent standard levels of steam temperature and pressure - of 540-560C/ 250bar and theefficiency rate of 44% -, the steam cycle with the advanced characteristics is expected to havea net efficiency of at least 50-51%, (Figure 1) which leads to an efficiency increase of at least6 percentage points.
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Figure 1: Efficiency in the power plants of Elsam SA, Source [2]
2.2 European R&D, D activities
2.2.1 The AD700 project
The European Union supports the efforts on increasing the steam parameters of power plantsby co-financing the research projects AD700 and COMTES 700, targeting on the materialsdevelopment, mechanical testing and demonstration in existing power plants.
More specific, main tasks of the AD700 have been:
- The demonstration of Nickel based superalloys for long term operation in the temperature
range 700-720C. The new materials will be used in the fabrication of thin-walled superand reheater tubes, of thick-walled outlet headers and steam piping and of specific turbinecomponents.
- The development of new fabrication methods for components made of super-alloys
- The development of new austenitic steels for boiler tubes operating in the temperaturerange 600-700C in order to minimize the use of expensive super-alloys.
- The investigation of the corrosion resistance of the new alloys operating at 700-750C inexisting boilers.
The results of the AD700 project indicate a number of materials as candidates for the nextgeneration of power plants. For furnace panels with expected temperature above 500C the12Cr steel HCM12 is proposed. For the thin walled super heater and reheater tubes anaustenitic and a Ni-based material are tested and demonstrated. Regarding the ferritic steels adeeper understanding of the microstructures is needed to optimize their chemical compositionin order to further improve the strength performance in the already developed materials.Furthermore, additional experience is gained in the materials commercial scale productionand several details regarding their fabricability pipe production, hot blending and weldingare investigated.
The AD700 Project was realized in two phases. The 1st phase of the project (1998-2004) wasfocused on the development and mechanical testing of new materials, on the development of
new furnace designs and on the technoeconomical study regarding the economic viability ofthe new plant concept. The 2nd phase (2002-2005) included the demonstration of the
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manufacturing of the new materials, the design of the component test facility and all thepreparatory work for the next demonstration phases. The 3d phase would have included a fullscale demonstration of all developed materials in an existing plant, but the proposal didntsucceed to be funded by the EU. Instead of this the realization of a two smaller scale testinstallations, is taking place in the COMTES700 project. Details about the projects financial
aspects can be seen in Table 3
2.2.2 The COMTES700 project
The main target of the COMTES700 project is the demonstration of the new materials in acomponent test facility (CTF) at a German Power plant and in a smaller test rig in a Danish
power plant. The testing period of the components will be approximately 20.000 hours, whilethe facilities are expected to operate in total more than four years during the project workplan.Main parts of the component test facility in the German Power Plant are an evaporator panel,superheater tubes, high pressure- headers, piping, bypass and safety valves. The rig in theDanish power plant includes a single loop of superheater tubes installed in the superheaterarea of the boiler. The steam is taken from the outlet of superheater 1, superheated to 720Cand cooled down to 560C again before entering the HP turbine.
2.3 R&D, D activities in USA
2.3.1 The US DoE project on the development of new materials
Similar research activities for developing new materials for USC steam parameters are beingcarried out in the USA. The alloys to be developed during the US national research projectwill provide mid term improvements to boilers and a higher efficiency steam cycle potentialfor the power plants to be constructed in the medium and long term (National Project Vision
21 power plants). However, as the research on the materials is still ongoing, no componentdemonstration in commercial power plants has been scheduled yet.
The goals set in the national research program are [4, 5, 6]:
- Identification of the materials performance issues that limit the operating temperatures
- Identification of improved alloys, fabrication processes and coating methods that willpermit boiler operation of steam temperature up to 760C and steam temperatures of up to378bar
- USC power system ready for commercial demo by 2010-2012 time frame
- Definition of issues impacting designs that can permit power generation at temperatures
greater or equal to 870
C (1600
F).The planned duration of the project is 5 years (2001-2006). The coordinator of the project isEnergy Industries of Ohio Inc. and the consortium consists of major boiler manufacturers(Alstom, Babcock Borsig, Babcock & Wilcox, Mc Dermott Technology, Foster Wheeler, OakRidge National Laboratory, and other specialized contractors for Testing and Analysis). TheRoad map for the development of new materials is presented in Figure2.
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Figure 2: Roadmap of the USC materials development and demonstration, Source: [4]
2.3.2 The Coal ash corrosion resistant materials testing program
Although no in plant demonstration of new developed high temperature resistant materials hastaken place in USA yet, a long term demonstration program of Babcock & Wilcox on thecorrosion behavior of ferritic steels for steam temperatures up to 600C is reported in theliterature. This corrosion issue is rarely being investigated in Europe or Asia, since most ofthe European or Asian coals have low sulfur content and so the presence of highly corrosivesulfur compounds in the flue gases is usually avoided. However, as high temperature firesidecorrosion is a common problem for US boiler manufacturers and operators, due to the usual
high sulfur content in US coals, the investigation of these phenomena in increasedtemperature levels is very important.Main goals of the project are :
- The evaluation of the corrosion performance of newer materials for coal-fired boilers atsurface temperatures expected with 593C steam temperature,
- The selection of materials resistant to fireside corrosion
- The generation of long-term corrosion field data.The demonstration includes the installing and operation of three test sections in thesuperheater region of a 110MWel power plant burning 3 - 3.5% sulfur coal. The sections arecooled by reheat stream (371,1 C, 21,7 bar), which is afterwards superheated to 593C.
Performing the tests with low pressure reheat steam allowed focusing on the high temperaturecorrosion phenomena. Moreover savings the fabrication costs were achieved, which wouldotherwise be much higher due to the need for thicker tube materials. Twelve different alloyswere tested. The three sections were identical to each other and consisted of four rows. Eachspecimen was included three times in each section enabling the exposure of each material inthree different temperature regimes. Finally, the sections differ on their scheduled time ofremoval and evaluation - after one, three and five years of operation for the 1st, 2nd and 3dsection accordingly. More information on the results of the project concerning materials
performance can be found in [7, 8, 9]
Other research activities in the US include:
- The development of TiAlCr alloys which can be used as smart protective high
temperature coatings for boiler materials [10]
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- Lab scale tests and evaluation of the corrosion performance of state-of-the-art candidatematerials (ferritic, austenitic, Ni based alloys) in coal ash, alkali sulfate, and alkalichloride environments at temperatures in the range of 650-800C [11].
- Evaluation and qualification of boiler materials needed to reach the USC steamparameters (720C, 350 bar). Characterisation and study of their microstructural
behaviour during aging and creep [12]- Assessment of the necessary materials for the next generation of USC steam turbines
[13].
2.4 R&D, D activities in Japan
Japan has been playing a leading role worldwide in the materials development and theincrease of steam parameters in power plants. The first supercritical power plant in Japan(241bar, 538/566C) was commissioned in 1967. Steam conditions reached 593C in Japanese
power plants in 1993. The 1000MW Haramachi No.1 unit had steam characteristics 245bar,
566/593C. Additionally, an 700MW power plant with 593
C steam temperature in both main
and reheat cycles is currently in the commissioning phase. In the middle of 90s Hitachi hasstarted a joint project with the Electric Power Development Co. (EPDC) and other plantconstructors, on the subject of future USC plants with steam parameters of 300bar/ 630,650C. In this research activity new 12Cr steels are evaluated for their future use in power
plants.
Table 3: Overview of Research Projects in EU, Japan and USA, scheduled budget
Country/group ofcountries
Project Name Fundingorganization
Coordinator Years TotalBudget
ActualFunding
EU AD700 Phase1 EU FP4 ElsamEngineeringSA
1998-2004
21 M 8,4 M
EU AD700 Phase2 EU FP5 ElsamEngineeringSA
2002-2005
11 M 5,5 M
EU COMTES700 RFCS VGB 2004-2009
15 M 6 M
USA Departmentof Energy(DoE)
EnergyIndustries ofOhio Inc.
2001-2006
15.3 M$ 10.5 M$
USA Coal ash corrosion
resistant materialstesting program
DoE Babcock &
Wilcox
1999-
2005
1,864 M$ 0,699 M$
Japan na. Ministry ofInternationalTrade andIndustry
ElectricPowerDevelopmentCompany
n.a. n.a n.a.
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3. Fuel handling issues introduction of predrying technologies (eg. WTA) for ligniteand integration into the steam cycle
Due to the low calorific value of Greek brown coal, the design data of the state of the artpower plants, which are currently available for 700C concept (BoA II, NRW ReferencePower Plant) cannot be fully exploited as a reference case. Therefore, the different
possibilities to handle and upgrade low rank coals have to be examined in more detail.
Possible concepts under consideration are the lignite pre drying methods, such as the fluidizedbed predrying with internal heat utilization (WTA), the mechanical and thermal dewatering(MTE) method and the tubular dryer [3]. Efforts were focused on the optimal integration ofthe WTA predrying concept in the ultra supercritical boiler technology. The fluidized beddrying was examined, as the most developed technology compared to the proposed alternativedrying concepts. It is worth mentioning that a full scale prototype of the dryer is underconstruction and will be integrated in the BoA I power plant at Niederaussem, Germany. Theanalysis in this task targeted on the optimization of the different operational parameters of thedryer, in order to achieve the optimum matching of the drying technology in the advanced
steam cycle.
3.1 Fluidised bed drying with internal waste heat utilisation, WTA (Wirbelschicht
Trocknung mit interner Abwrmenutzung)
The examined technology has been developed by Rheinbraun (now RWE-Power). It has beentested since 1993, when the first prototype was constructed in Frechen, Germany, operated forover 13,000 hours and dried 50,000 tons of raw brown coal. Since 1999, a new prototypewhich is based on the fine-grain WTA technology was developed and demonstrated improvedcapital and operation costs. From 2007, the technology will be implemented at commercialscale, when initially one unit of 114 t/h dry lignite throughput will be installed and connected
to the BoA power plant. This historical background confirms the operation suitability andintegration capability of the dryer to a power plant process.
The operation concept of the WTA technique is shown in Figure 3. The brown coal is insertedinto the dryer following its pre-heating at 65 oC within heat exchanger using condensed waterfrom the drying process of the previous charge. It is fluidised at 100 oC under the influence ofslightly superheated steam. The main part of heat needed for the moisture heating andevaporation is provided by pressurised steam from the drying of the previous charge in a heatexchanger. The steam, which is used for the fluidisation, also contributes to the evaporation offuel moisture. After being cleaned in an E-filter, the evaporated moisture is fed into the steamcompressor, where its temperature is increased from 100 up to 150 oC by pressuring it in
many steps up to 4-5 bar. A small part of this evaporated moisture is used as a fluidisationmedium. The condensed water from heat exchanger is used for cooling the steam compressoras well as for pre-heating of raw brown coal. The residence time of the brown coal in thedryer depends on the moisture content and is approximately 60-90 minutes.
Alternative to this close cycle concept, where the evaporated steam from the coal isreutilised as a heating medium for the drying process after being compressed, the opencycle concept has been developed. It avoids the installation of a compressor by the use oflow temperature steam extracted from the low pressure part of the steam turbine. Theevaporated steam from the coal is afterwards utilised at the first water preheater step of the
power plant. The open cycle concept was finally chosen to be implemented in the firstWTA prototype which will be integrated in the BoA block of the Niederaussem power plant.The lack of the mechanical compression part, which is a technical step with its owndifficulties and failure characteristics, simplifies the overall design and improves the expected
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availability of the plant. Any risk for the reliable operation of the 1000 MWel unit, generatedby a malfunction in the drying process due to a possible failure of the steam compressor, is inthis way avoided.
Raw Brown
Coal
Compressor of the
evaporated moisture
Dryer
E-filter
Dried coal
cooler
Coal
Preheater
bar
oC
kJ /kg
kg / s
1.02
106.0 124.2
2686.73
1.02
106.0 124.2
2686.73
1.02
106.0
183.62
3.2
246.4 61.84
2957.48
1.23
126.8 62.36
2726.16
1.02
70.0 130.10
202.76
1.0
20.0 130.10
57.93
1.02
106.0 68.26
183.62 1.0
69.84 68.26
120.992.5
55.1 61.84
230.94
3.0
127.5 61.84
535.64
Condensed
water
Cooler
18.1
39.4 236.58
166.41
18.3
36.7 236.58
155.34
17.9
43.7 236.58
184.48
3.2
140.0 68.08
2736.30
2.5
45.0 61.84
188.60
3.2
127.5
535.67
6.25
Figure 3: Calculated Data of WTA-Dryer.
3.2 Tubular dryer
The drying medium is steam bled from the turbines and condensed by passing over thesurfaces of the dryer tubes. The condensate is conducted to a low-pressure steam heatexchanger, thus pre-heating the feed water. A further heating of feed water takes place usingthe dried fuel before entering the furnace. Therefore, a reduction of the bled steam quantity isachieved.
Three alternative test cases 2.23bar/203.1C (test case 1), 5.18bar/294.5C (test case 2) and20.00bar/470.1C (test case 3) were examined. The highest efficiency and power output of thetotal power plant were calculated in the first test case. The produced power using the tubulardryer is lower than the reference case. This is due to the fact that the bled steam used for fuel
pre-drying does not produce work in the steam turbines. The higher the pressure of the bledsteam, the lower the effective power output. The corresponding operational characteristics ofthe tubular dryer are shown in Figure 4.
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Raw Brown Coal
Hot Steam
Dryer tubes
E-motor
Condensed
steam
Dried coal
Air
+
Evaporated
mois ture at 110 Co
bar
oC
kJ /kg
kg / s
1.0
110.0 123.72
1.0
110.0 68.29
190.55
20.0
57.93
130.15
1.0
2.0
117.1 74.88
491.29
2.23
203.1 74.88
2874.57
Figure 4: Calculated Data of the tubular dryer for the test case 1.
3.3 MTE-Dryer (Mechanische-Thermische Entwsserung/Mechanical Thermal
Dewatering)The MTE is a combination of thermal and mechanical moisture extraction. Compared to the
previous processes, the MTE dewatering operation is not continuous but it is performed incycles. Also, although the final water content of the dried fuel is higher, the process appearsto be attractive for application. This can be explained due to the lower energy demand forwater extraction compared to the other examined drying processes. The main characteristicsof the dryer operation are shown in Figure 5.
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F
Coal fill
Steam
Pressure
plate
waste water''hot"
waste water
''cold"
RawBrown
Coal
Post
evaporation
183.6 53.00
781.20
10.5
382.1 10.53
3223.81
45.0 64.24
193.62
1.0
183.5 78.79
370.76 1.0
80.0 75.76
154.72
1.0
132.50
57.93
20.0
bar
oC
kJ /kg
kg / s
Figure 5: Calculated Data of MTE-Dryer.
3.4 Integration of an External WTA Dryer into a Steam Cycle
The integration of each drying concept into the steam cycle of an existing Greek power plant,the Agios Dimitrios Unit V was modelled with the modified code ENBIPRO (Energie BilanzProgram) [11]. The initial code was programmed to evaluate the characteristics of thermallyinteracting flows in the air-flue gas and water-steam cycles of a power plant. The necessarymodifications concerned the programming of a new module into the code in order to simulatethe drying process. Therefore, an additional flow type representing the fuel input and output atthe dryer was modelled.
The thermodynamic characteristics of the working fluid remained practically unchanged in all
test cases. Furthermore, the flue gas exit temperature and the air excess ratio remainedunchanged, approximately 150C and 1.29, respectively. The energy producing andconsuming equipment (steam turbines, pumps, fans and compressors) was assumed to have amechanical and electrical efficiency of 97.5 % and 99 %, respectively. The considered rawfuel was Greek brown coal from Ptolemais Region whose typical characteristics are shown inTable 4. In all cases, the final water content of the dried fuel was considered to be 15% exceptfor the MTE method where it was assumed to be 22%. The dried coal composition and thecorresponding lower heating values are shown in Table 4.
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Table 4: Main characteristics of Greek raw and pre-dried brown coal.
Fuel C (%) H (%) S (%) O (%) N (%) Ash (%) H2O
(%)
Hu
(MJ/kg)
Greek
lignite
18.46 1.49 0.44 8.72 0.51 14.98 55.4 5.58
Predried
lignite
35.18 2.84 0.84 16.62 0.97 28.55 15.00 12.85
Predried
lignite
(MTE)
32.28 2.61 0.77 15.25 0.89 26.20 22.00 11.59
All the test cases characteristics are summarised in the following Table 5. It is well indicatedthat applying fuel pre-drying process a reduction of the fuel consumption of about 20% can beachieved. The tubular dryer is already applied successfully in industrial scale for power
production. However, more attractive seem to be the methods, where either no bleeding steamfrom the turbine or only a small amount is required for the drying process. If bled steam isused its pressure should be the lowest one (tubular dryer). The same conclusion for the
pressure influence on the plant efficiency exists in the case, where the evaporated moisture isexploited in the drying process itself (WTA). An efficiency increase is obtained in allexamined test cases, which can rise up to 5.5-6.9 [%] when the WTA-Dryer (grain size) isused. The WTA and MTE methods have been proven to be the most efficient dryingtechniques. Compared to WTA, the MTE process has a higher net power output, which is dueto the lower energy consumption of this dewatering technology.
The results obtained in this study for some test cases show a significant deviation from the
available literature data, as it can be seen in Figure 6. This is due to the different thermodyna-mic data of the used drying steam. However, other particular mathematical models mentionedin the respective literature can confirm the tendency of the achieved results. As shown in
Table 5: Comparison of all calculated test cases.
Test Case
(Drying Method)
Raw Fuel
Consumption
(kg/s)
Drying Medium
Consumption
(kg/s) (% total)
Pgross(MW)
Pnet(MW)
(%)
Flue Gas 162.30 190.0 (24.16 %)100.0 (21.81 %)
- - -
Turbular dryer 1 130.15 74.87 -35.5 -32.4 4.71-//- 2 132.10 73.62 -41.1 -38 3.33
-//- 3 131.56 72.39 -66.1 -61.9 0.24
WTA dryer 1 130.10 68.08 - -16.6 6.90
-//- 2 134.95 74.24 +4.4 -21.9 4.61
MTE dryer 3 132.50 10.53 -8.8 -7 7.39
Table 5 the integration of pre-drying to the power generation scheme leads to substantialefficiency increase but it also reduces the produced power output. This is due to the extractedsteam, which is then used for the pre-drying process. Therefore, it is expected that an externaldryer can be considered as a part of a new erecting power plant and not for an existing one.
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0
2
4
6
8
10
12
0 1 2 3 4 5 6 7 8
Efficiency increase, [%]
Literature Data
Calculated
Tubular Dryer, 4-5 bar
Tubular Dryer, 2.23 bar
Tubular Dryer, 5.18 bar
Tubular Dryer, 20 bar - 0.24
WTA-Dryer, 4-5 bar
TA-Dryer, 3.2 bar
TA-Dryer, 5 bar
7.39
4.61
6.90
5.5
3.33
4.71
3.2
MTE-Dryer
MTE-Dryer 5.0
Figure 6: Comparison of the calculated net efficiencies.
4. Initial layout and design of the 700C plant using pulverized lignite, Balance ofPlant, estimated efficiency and generation costs.
Based on the results of the previous section, a study on the thermodynamic analysis of theadvanced steam cycle utilizing Greek brown coal was performed. The main objective of the
present task was to investigate the influence on the performance of a power plant fired withlow-quality lignite of ultra supercritical steam parameters, with the main and reheat steamtemperatures at 700 C and 720 C respectively, and the steam pressure at the exit of the
boiler being at 350 bar. The development of new suitable materials is the decisive factor,which will lead in high efficiencies concerning PF power plants.
In order to provide a comparative view of the power plants efficiency increase when theabove-mentioned advanced supercritical steam parameters are applied, four cases areexamined:
Case 1: Reference power plant
Case 2: Reference power plant with lignite pre-drying system (WTA)
Case 3: AD700 power plant
Case 4: AD700 power plant with lignite pre-drying system (WTA)
The fuel utilized for all cases is low-quality lignite with high moisture and ash content. Table1 illustrates the ultimate analysis of the lignite and its LHV.
According to the pre-drying concept applied in this study, the heat content of the moisture thatis removed in the form of steam from the raw lignite, is compressed up to 3.2 bar andconsequently used for the drying (WTA drying system). This technology affects positively theefficiency of the PF power plant. The water content of the raw lignite is 55.3 % w/w while itdrops to 12 % w/w at the exit of the dryer. As a result, the LHV is increased significantlyfrom 5.418 kJ/kg to 13.025 kJ/kg. The ultimate analysis and LHV of the dried fuel are shownin Table 2 below.
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Table 1: Raw Lignite ultimate analysis
C w% 18.5
H w% 1.5
S w% 0.4
O w% 8.7N w% 0.6
Ash w% 15.0
H2O w% 55.3
LHV (kJ/kg) 5.418
Table 2: Dried Lignite ultimate analysis
C w% 36.4
H w% 2.9
S w% 0.8
O w% 17.2
N w% 1.1
Ash w% 29.5
H2O w% 12.0
LHV (kJ/kg) 13.025
4.1 Results
The table below illustrates the main data resulting from the simulations of case 1 and case 2.
The reference power plant is a 360 MWel gross power output plant with reheat and 7 waterpreheaters with steam extraction from the ST. The PF boiler is supercritical with main steamoutput temperature and pressure 540 C and 190 bar respectively. The influence of the pre-dryer for the high-moisture content lignite is quite beneficial, increasing significantly the
power plants efficiency.
In table 4 the simulation results of cases 3 and 4 (advanced supercritical steam parameters) arepresented. The main steam pressure and temperature is 350 bar and 700 C, while therespective values for the reheat steam are 75 bar and 720 C. The power plant configuration ismaintained the same as in the reference cases, but it has been assumed that higher turbine
polytropic stage efficiencies are achieved compared to the reference power plant, to take into
account the turbine design developments. The power plant net efficiency is estimated to bemore than 50% (on raw fuel LHV) when a pre-drying system is applied. On the other hand,for the same boiler fuel heat input, the gross power output is increased by more than 60MWel.
Figure 1 shows the process flow diagram (PFD) for cases 1 and 3 (power plants withoutlignite pre-drying system), while the PFD for cases 2 and 3 (power plants with lignite pre-drying system) is presented in Figure 2. The costs for the installation of the separate parts andthe whole power plant are given below.
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Table 3: Main data for Reference power Plant and Power Plant with WTA Dryer.
Power consumptionReference case Reference case with
pre-drying system
FD fans MWel 1.60 1.27ID fans MWel 3.20 1.98
Lignite mills MWel 11.52 9.06
ESP MWel 0.57 0.45
FW pumps MWel 9.22 9.24
Condensate pumps MWel 0.50 0.50
Circulating and coolingwater pumps
MWel2.15 2.16
Pre drying system MWel - 24.75
Total MWel 28.76 49.41
Fuel flow Kg/s 170.1 133.87Heat Input (On rawfuel LHV)
MWth921.6 725.31
Gross power output MWel 361.17 361.93
Net power output MWel 332.41 312.52
Net efficiency % 36.07 43.09
Table 4: Main data for AD700 Power Plant with and without WTA Dryer
Power consumptionAD700 without lignite pre-
drying system
AD700 with lignite pre-
drying system
FD fans MWel 1.60 1.27
ID fans MWel 3.20 1.97
Lignite mills MWel 11.52 9.05
ESP MWel 0.57 0.45
FW pumps MWel 15.68 15.69
Condensate pumps MWel 0.84 0.84
Circulating andcooling water pumps
MWel1.86 1.86
Pre drying system MWel - 24.71
Total MWel 35.27 55.84
Fuel flow Kg/s 170.1 133.67
Heat Input (On rawfuel LHV)
MWth 921.6 724.22
Gross power output MWel 422.53 422.77
Net power output MWel 387.26 366.93
Net efficiency % 42.02 50.67
Table 5: Installation costs of AD700 Power Plant with WTA Dryer.
Coal & Ash
HandlingBoiler ESP FGD Steam Boiler BoP TOTAL
M M M M M M M
40 250 16 63 82 86 537
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Figure 1: PFD for Reference Power Plant and AD700 Power Plant without lignite pre-drying system.
Figure 2: PFD for Reference Power Plant and AD700 Power Plant with lignite pre-drying system.
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Heat and Mass Balances
Reference Power Plant
Temperature(oC)
Pressure (bar)Flow(kg/s)
Enthalpy(kJ/kg)
G1 20.000 1.000 422.669 4.491G2 23.742 1.040 422.669 8.282
G3 255.528 1.040 422.669 245.844
G4 860.000 0.977 667.223 1,105.549
G5 623.018 0.977 567.223 769.939
G6 457.896 0.977 567.223 547.489
G7 309.653 0.977 567.223 356.241
G8 165.000 0.977 567.223 177.459
G9 169.659 1.013 567.223 183.104
F1 20 1.02 170.1 57.93
Temperature(oC) Pressure (bar) Flow(kg/s) Enthalpy(kJ/kg)
S1 243.270 241.595 276.792 1,055.496
S2 320.800 236.763 276.792 1,443.535
S3 388.463 236.763 276.792 2,500.000
S4 490.000 210.719 276.792 3,187.756
S5 540.000 189.647 276.792 3,375.242
S6 295.233 35.400 256.684 2,962.764
S7 499.900 35.400 256.684 3,449.721
S8 540.100 31.860 256.684 3,544.497
S9 289.768 5.175 222.604 3,042.114
S10 35.867 0.059 188.502 2,365.405
S11 35.867 0.059 235.117 1,952.588
S12 35.867 0.059 235.117 149.657
S13 35.959 18.000 235.117 151.781
S14 153.205 10.000 235.107 645.844
S15 184.758 246.500 276.792 795.807
S16 295.233 35.400 20.108 2,962.764
S17 468.581 20.000 12.287 3,397.858
S18 371.794 10.000 9.291 3,203.456
S19 289.882 5.180 12.491 3,042.337
S20 200.478 2.231 13.088 2,869.833
S21 103.306 0.741 8.824 2,685.622
S22 69.946 0.311 12.194 2,563.336S23 67.530 0.280 46.615 283.222
S24 91.465 0.741 34.387 383.563
S25 123.735 2.231 25.577 519.513
S26 153.205 5.180 12.491 645.567
S27 212.427 20.000 32.395 908.916
S28 243.270 35.400 20.108 1,053.119
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Reference Power Plant with WTA lignite pre-drying system
T (C) P (bar) m (kg/s) h (kJ/kg)
G1 20.00 1.00 334.99 4.49
G2 23.74 1.04 334.99 8.28
G3 268.02 1.04 334.99 258.91
G4 1240.00 0.98 400.91 1493.19G5 864.52 0.98 382.91 995.00
G6 602.09 0.98 382.91 664.49
G7 363.10 0.98 382.91 380.60
G8 165.00 0.98 382.91 159.14
G9 169.74 1.01 382.91 164.30
T (C) P (bar) m (kg/s) h (kJ/kg)
F1 20 1.02 133.87 57.93
F2 70 1.02 133.87 202.76
F3 106 1.02 68.00 174.29
D1 106 1.02 119.83 2686.733
D2 106 1.02 53.81 2686.733
D3 126.4 1.23 53.81 2726.149
D4 106 1.02 66.02 2686.733
D5 246.3 3.2 66.02 2958.346
D6 139.8 3.2 72.70 2735.846
D7 127.5 3 72.70 535.705
D8 127.5 3 6.68 535.705
D9 127.5 3.2 6.68 535.729
D10 127.5 3 66.02 535.705
D11 57.8 3 66.02 242.039
T (C) P (bar) m (kg/s) h (kJ/kg)
S1 243.27 241.59 277.36 1055.50S2 320.80 236.76 277.36 1443.54
S3 388.46 236.76 277.37 2500.00
S4 490.00 210.72 277.37 3187.76
S5 540.00 189.65 277.37 3375.24
S6 295.23 35.40 257.22 2962.76
S7 499.90 35.40 257.22 3449.72
S8 540.10 31.86 257.22 3544.50
S9 289.77 5.18 223.08 3042.11
S10 35.87 0.06 188.90 2365.41
S11 35.87 0.06 235.60 1952.73
S12 35.87 0.06 235.60 149.66S13 35.96 18.00 235.60 151.78
S14 153.20 10.00 235.60 645.84
S15 184.76 246.50 277.36 795.81
S16 295.23 35.40 20.15 2962.76
S17 468.58 20.00 12.31 3397.86
S18 371.79 10.00 9.31 3203.46
S19 289.88 5.18 12.52 3042.34
S20 200.48 2.23 13.12 2869.83
S21 103.31 0.74 8.84 2685.62
S22 69.95 0.31 12.22 2563.34
S23 67.53 0.28 46.69 283.22S24 91.46 0.74 34.47 383.56
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S25 123.73 2.23 25.63 519.51
S26 153.20 5.18 12.52 645.57
S27 212.43 20.00 32.46 908.92
S28 243.27 35.40 20.15 1053.12
AD700 Power PlantT (C) P (bar) m (kg/s) h (kJ/kg)
G1 20.00 1.00 422.67 4.49
G2 23.74 1.04 422.67 8.28
G3 306.64 1.04 422.67 299.52
G4 855.00 0.98 667.22 1098.29
G5 578.70 0.98 567.22 709.37
G6 486.50 0.98 567.22 585.33
G7 341.48 0.98 567.22 396.65
G8 165.00 0.98 567.22 177.46
G9 169.66 1.01 567.22 183.10
F1 20 1.02 170.1 57.93
T (C) P (bar) m (kg/s) h (kJ/kg)
S1 294.13 422.28 258.24 1295.23
S2 370.00 413.84 258.24 1705.56
S3 452.66 413.84 258.33 2500.00
S4 593.48 368.32 258.33 3353.96
S5 700.02 350.00 258.36 3713.13
S6 432.60 78.93 237.13 3227.92
S7 550.00 78.93 237.13 3521.60
S8 720.00 75.00 237.13 3932.91
S9 411.76 12.21 202.28 3285.07S10 35.87 0.06 160.93 2353.69
S11 35.87 0.06 215.72 1850.00
S12 35.87 0.06 215.72 149.66
S13 36.06 32.76 215.72 153.53
S14 188.78 24.76 215.83 802.28
S15 234.23 430.86 258.24 1020.64
S16 432.60 78.93 21.23 3227.92
S17 632.73 47.17 10.17 3744.24
S18 521.36 24.76 11.16 3509.45
S19 411.77 12.21 13.42 3285.10
S20 301.14 5.26 13.66 3065.41
S21 180.36 1.75 8.98 2831.76
S22 103.06 0.73 18.75 2685.24
S23 88.37 0.66 54.79 370.60
S24 116.07 1.75 36.05 487.11
S25 153.79 5.26 27.07 648.09
S26 188.78 12.21 13.42 801.94
S27 260.38 47.17 31.41 1136.49
S28 294.13 78.93 21.23 1311.85
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AD700 Power Plant with WTA lignite pre-drying system
T (C) P (bar) m (kg/s) h (kJ/kg)
G1 20.00 1.00 334.78 4.49
G2 23.74 1.04 334.78 8.28
G3 330.17 1.04 334.78 324.42
G4 1230.00 0.98 400.63 1479.45G5 792.47 0.98 382.63 902.44
G6 645.99 0.98 382.63 718.43
G7 413.18 0.98 382.63 438.56
G8 165.00 0.98 382.63 159.13
G9 169.74 1.01 382.63 164.28
T (C) P (bar) m (kg/s) h (kJ/kg)
F1 20 1.02 133.67 57.93
F2 70 1.02 133.67 202.76
F3 106 1.02 67.9 174.29
D1 106 1.02 119.65 2686.733
D2 106 1.02 53.73 2686.733
D3 126.4 1.23 53.73 2726.149
D4 106 1.02 65.92 2686.733
D5 246.3 3.2 65.92 2958.346
D6 139.8 3.2 72.59 2735.846
D7 127.5 3 72.59 535.705
D8 127.5 3 6.67 535.705
D9 127.5 3.2 6.67 535.729
D10 127.5 3 65.92 535.705
D11 57.8 3 65.92 242.039
T (C) P (bar) m (kg/s) h (kJ/kg)
S1 294.13 422.28 258.39 1295.23
S2 370.00 413.84 258.39 1705.56
S3 452.66 413.84 258.54 2500.00
S4 593.48 368.32 258.54 3353.96
S5 700.02 350.00 258.54 3713.13
S6 432.60 78.93 237.30 3227.92
S7 550.00 78.93 237.30 3521.60
S8 720.00 75.00 237.30 3932.91
S9 411.76 12.21 202.39 3285.07
S10 35.87 0.06 161.01 2353.69
S11 35.87 0.06 215.83 1849.98
S12 35.87 0.06 215.83 149.66S13 36.06 32.76 215.83 153.53
S14 188.78 24.76 215.96 802.28
S15 234.23 430.86 258.39 1020.64
S16 432.60 78.93 21.24 3227.92
S17 632.73 47.17 10.17 3744.24
S18 521.36 24.76 11.17 3509.45
S19 411.77 12.21 13.43 3285.10
S20 301.14 5.26 13.67 3065.41
S21 180.36 1.75 8.98 2831.76
S22 103.06 0.73 18.76 2685.24
S23 88.37 0.66 54.82 370.60S24 116.07 1.75 36.07 487.11
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S25 153.79 5.26 27.09 648.09
S26 188.78 12.21 13.43 801.94
S27 260.38 47.17 31.43 1136.49
S28 294.13 78.93 21.24 1311.85
5. Analysis of public funding possibilities to sponsor the particular technology(EU Framework Programmes, RFCS, National Research Programmes,
DoE)
An overview is provided of the various sources of grant funding for coal utilisation R,D & D that can support both fundamental and pre-competitive, applied research aswell as some demonstration activities in Europe and the United States. These sourcesmainly include:
For the EU:
1. The EU Framework Programmes and European Research area networks (ERA-Net)
2. Research Fund for Coal and Steel (RFCS), formerly the European Coal and SteelCommunity (ECSC) Programme
3. The National Research programmes in the EU member states, Germany and UK.
4. US Department of Energy (DoE) Research programs
5.1 EU Framework Programmes and European Research Area Network (ERA-Net)
Many of the EU R, D & D activities are implemented through research, technologicaldevelopment and demonstration (RTD) Framework Programmes, which are managed
by the European Commission (EC). The non-nuclear energy component of the SixthFramework Programme (FP6) for the period 2002-2006 included several thematic
priority areas, of which that entitled Sustainable development, global change andecosystems is relevant to fossil fuels (European Commission 2004). Work on fossilfuels has been focused on the development and demonstration of techniques for CO 2CCS from power plants. In order to ensure EU critical mass, there has been a move tolarge integrated, industry led projects [15].
Alongside these projects, there has been the establishment of European wide networksof excellence, designed to bring together leading EU researchers on specific topics.
Throughout FP6, there has been an ongoing campaign by EU industry to broaden thefossil energy R, D & D agenda to include the integration of efficiency andenvironmental improvements, particularly for coal fired power generation. Much ofthis lobbying has been directed via three thematic networks that bring together EU-wide industry, research institutes and universities. These are Powerclean, coveringsolid fossil fuel power generation, CO2Net, covering CO2 capture and storage plusCAME-GT, covering cleaner more efficient gas turbines [16-19].
For FP7, there has been the necessary shift of emphasis in the R, D & D objectives[19]. A separate cooperation theme has been allocated exclusively for Energy. Themain objective in this priority is to adapt the fossil-fuel based energy system into a
more sustainable one with particular attention to lower and non-CO2 emitting energytechnologies combined with enhanced energy efficiency and conservation. A separate
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project is expected to be appointed for the demonstration of advanced and ultra-supercritical steam cycle. Efforts will be undertaken for follow-up activities in theAD700/2 FP5 and COMTES700 RFCS projects, with the ultimate goal to achieve700C steam temperature and pressure of 300 bar based on coal. Work is required onthe materials development, component manufacturing, testing, and demonstration in
real conditions. Further information can be found at CORDIS, the EuropeanCommunitys R&D Information Service, which offers access to information frommore than 40,000 web pages, 285,000 database records and thousands of documents(www.cordis.lu/search).
In order to improve the cooperation and coordination of research activities carried outat national or regional level in the Member and Associated States, EU has initiatedand supports a Network scheme for the European Research Area (ERA-Net). Maintasks and actions of the above scheme are:
the networking of research activities conducted at national or regional level, and
the mutual opening of national and regional research programmes.
ERA-Net is not a funding scheme or organisation and is not in position to cover thespecific R&D, D needs for the development of the new generation of fossil fuel power
plants. Its role is important however, in order to strengthen the cooperation betweenresearch institutions and industry. This networking activity will also enable nationalsystems to take on tasks collectively that they would not have been able to tackleindependently.
One of the ongoing networks is the FENCO ERA-Net. It targets to link the R&D anddemonstration needs of EU member states, the EU, industry and academia on anextended European level to describe a technology path towards low or even zero
emission power plants [20]. The specific actions planned for the realisation of theabove are:
Implementing and continuously improving a platform for information exchangeon fossil fuel R&D activities at national and regional level;
Establishing a common knowledge base for the development of a Europeanpolicy towards zero emission power plants;
Strengthening the European R&D and demonstration infrastructure on cleanfossil power generation through joint programming, management, personnelexchange and targeted integration activities;
Supporting the Lisbon strategy of the European commission process byenhancing the competitiveness of European power plant manufacturers.
Through the participation in the FENCO ERA-NET, each member will take theopportunity to share knowledge and funding options for a step-by-step improvementof the fossil energy technologies and especially the 700 oC concept. Additionally, theregulations of the EU structural funds, which can sponsor large infrastructure projectsin EU member states and mainly the accession countries are collected and examined.
5.2 Research Fund for Coal and Steel
The Research Programme of the RFCS, adopted in February 2002, succeeded the
ECSC programme. The programme consists of two main RTD actions: research, pilotand demonstration projects and accompanying measures related to the promotion of
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the use of the knowledge gained. The programme, which is now managed by EC DGResearch, continues to be directed primarily towards industrially orientated activitiesthat have a short to medium term horizon. As such, in the coal utilisation programme,much of their work has been focussed towards improving the efficiency,environmental performance and amenity value of existing coal fired plant. In addition
there is support for some work on gasification related issues that has a medium termhorizon. The aim is to complement other activities in Member States and existingCommunity research programmes, such as the Framework Programme(http://cordis.europa.eu/coal-steel-rtd/). The budget allocated for financing coal andsteel research was 60 million for 2003 and 60 million for 2004. In broad terms,this equates to an annual budget for coal utilisation R,D&D of about 15 million.
5.3 The National Research programmes in Germany and UK
The German research projects on the new generation of fossil fuel power plants areincluded in the national main Energy Research Programme Innovation and New
Energy Technologies[21], which is funded by the Federal Ministry of Economy andTechnology (BMWi) jointly with three other Federal Ministries. Main strategies ofthe programme are:
The maintenance of a secure and balanced energy mix in Germany.
The substantial improvements in the energy conversion efficiency.
The increase of the proportion of renewable energies for covering primaryenergy demand without any loss of the economic performance.
The achievement of the set goals for the international climate protection at thelowest possible cost.
In addition to the abovementioned targets, major renewal requirements concerningfossil-fired power plants are predicted by experts for the next few decades. InGermany, this will be of the order of magnitude of 40,000 megawatts. In Europe, thecorresponding demand is estimated to be 200,000 megawatts.
In order to support the power plant sector for the upcoming transition period, theBMWi has developed, together with the industry and academia, the COORETECconcept [22] for future priorities in research and development for modern power planttechnologies. Through this action different future plant concepts under developmenthave been evaluated and a technological basis for a low-emission and in the long termemission-free coal-fired power plants is set.
The approved budget for the funding of the Energy conversion technologies in theoverall National Energy Programme is 284 million for the years 2005-2008. The 10-15% of this amount is expected to be the share for the coal and gas power plant sector,whereas the other part will be used to fund the R&D activities in other energy sectors,such as the Fuel Cell and the CO2 storage and hydrogen technologies, the energyoptimised construction and the energy efficiency in industry, trade, commerce andservices.
In the UK, the Department of Trade and Industry (DTI) supports the researchprogramme on the new generation of fossil fuel power plants through the CarbonAbatement Technologies (CATs) Initiative [23]. These technologies include:
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Higher efficiency conversion processes, which aim at a reduction of the CO 2emissions generated and the fuel consumed in industrial conversion processes(eg power generation, oil refining) up to 10-30% by the increase of theirefficiency.
Fuel switching from solid fuels like coal to lower carbon alternatives, such asnatural gas, which reduces emissions by about 50% per unit of output, or co-firing of coal with CO2 - neutral biomass to a certain percentage up to 5-10%,which can deliver emissions reductions of CO2 emissions in the order of 5-10%.
CO2 capture and storage (CCS) which includes the capture of the carbon in fossilfuels (as CO2) either before or after combustion and its long-term storage ingeological formations. The estimated emissions reduction lays up to 85%depending on the type of non-capture plant displaced. Even higher levels can beattained by combining CCS with co-firing with biomass.
The scheduled funding allocated by the DTI is up to 20M in total for the period
2005/06 to 2007/08. Industry-led R&D projects will be funded through this actionmainly targeting to laboratory or semi industrial based research. This budget is alsointended to assist UK collaboration in international R&D Programmes including theMemoranda of Understanding with the USA and China and covers DTIs ongoingcontribution to the British Coal Utilisation Research Associations (BCURAs)research programme, and membership contributions to the IEAs ImplementingAgreement on Cleaner Coal.
As demonstrations up to full-scale may be necessary in the upcoming period in thelow to zero CO2 emission technologies, as well as in the hydrogen production and fuelcell technologies, the UK Government will provide a funding package of 40M overfour years commencing in 2006/07 for demonstrations across CATs, hydrogen andfuel cells. Of the total around 25M is expected to be dedicated to CATs and the restof the budget with the approximate balance split of 50:50 to hydrogen and fuel cells.Projects that combine technologies, for example CATs and hydrogen, will be able toseek funding from both elements. This funding will be made available in the form ofCapital Grants, and will be subject to State Aid rules and approval.
5.4. The US Department of Energy (DoE) Research programs
Main initiatives of the US DoEs Research Programmes are below others:
The Clean Coal Power Initiative
The FutureGen project Tommorrows Pollution Free Power Plant
The Advanced Materials Research Project
The Clean Coal Power Initiative (CCPI), initiated in 2002, is an innovativetechnology demonstration program that fosters more efficient clean coal technologies(CCTs) for use in new and existing electric power generating facilities in the UnitedStates [24, 25]. The allocated budget for the initiative lays up to 2 $billion for the nextdecade. Candidate technologies are demonstrated at sufficient scale to en-sure proof-of-operation prior to commercialization. Technologies emerging from the programwill help to meet new environmental objectives for America embodied in the ClearSkies Initiative, Global Climate Change Initiative (GCCI), FutureGen, and the
Hydrogen Initiative. Early CCPI demonstrations emphasize technologies applicable toexisting power plants and to new plant construction.
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The FutureGen Initiative is a coal-fuelled 275 MW IGCC prototype plantincorporating carbon capture, designed in order to allow the co-production ofelectricity and hydrogen [26]. The available public funds for FutureGen are $950million for a period of ten years.
The Advanced Material Research Initiative focuses on the development of the newgeneration of materials to be applied in the power plant technology in the comingdecade. Details on specific research actions in the framework of the AdvancedMaterials Initiative are given in the chapter 2.3 of the present study.
6. Comparison of this technology with the Research Priorities of the EC.As it is well known, the concept study for a 700C power plant is closely related toCO2 capture and storage technology (CCS), since the latter can be implemented onlyin high efficiency power plants. Experts agree that CCS together with improvedenergy conversion efficiency is a near-term solution to reducing CO2 emissions fromfossil fuel power generation on massive scale. Following developments in clean
power generation and the priority given to zero emission power generation in theFP6, industrial stakeholders and the research community had several meetings in2004, which resulted in the creation of a Technology Platform for Zero EmissionFossil Fuel Power Plants (ZEP). The main objective of this initiative is to identify andremove barriers to creating highly efficient power plants with zero emissions, whichwould drastically reduce the environmental impact of fossil fuel use, particularly coal.In simple words, its utmost goal is to enable zero CO2 emissions from European fossilfuel power plants by 2020 [27].
The relationship between the development of Zero Emission Fossil Fuel Power Plants(ZEP) and energy efficiency increase is sharply described here. As the capture process
requires energy, it has a direct cost due to the reduced efficiency of power generation(or other processes), or through increased fuel requirements. Increasing the efficiencyof energy conversion processes will therefore play a key role in offsetting this cost.Both fuel consumption and CO2 emissions will be reduced when integratingefficiency increase with CO2 capture technology, leading to reduction ofenvironmental impact, savings of energy resources and lowered costs, thus improvingcompetitive advantage.
In particular, clean coal technology needs to improve plant efficiency, reliability andcosts substantially through R,D&D of clean coal and other solid fuel conversiontechnologies which produce secondary energy carriers (including hydrogen) and
liquid or gaseous fuels. The main goal for steam power plants is to achieve over 50%efficiency by designing novel steam turbines and further developing boiler technologyfor steam parameters of 700 oC+. Towards this purpose, key activities that have to beundertaken are [27]:
Develop and qualify new materials for high-temperature-loaded areas in steamgenerators, piping, valves and turbine for 700oC+
Research component adapted design and integrity concepts
Develop new protective coatings
Improve welding methods, cost-cutting measures for manufacturing andcertification, safeguarding of properties, manufacturing large components and
measures for detecting defects and flaws. Investigate corrosion under oxy-coal atmosphere
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Develop novel steam turbine designs with steam cooling, ceramic coatings,improved clearance control, new sealings and improved aerodynamics
Improve water/steam cycles
Enhance design tools and codes in order to calculate heat transfer,aerodynamics and components
Conduct experimental validation and rig tests as required for successfulimplementation
Higher plant output by advanced components
Improve materials, aerodynamic and thermodynamic performance, coolingsystems and Instrumentation & Control systems
Fuel processing and multi-fuel capacity
Achieve reliability > 98%, availability > 95%
Improve part-load efficiency
Apart from the R&D activities, there is urgent need for demonstration projects too.
Several power companies around the world are now investing in pilot-scale facilitiesfor all three of the main CO2 capture technologies. However, to date, there are no full-scale demonstrations of CO2 capture, although it is technologically possible.
The chart below illustrates the expected impact of the roadmap to be followed for theZEP development by 2020. The left axis shows the CO2 that would be avoided by the
progressive deployment of ZEPs. The red line shows how costs could be expected todecline as we move from R&D to industrial-scale deployment. Once the expected costof deployment is less than the expected long-term value of CO2 traded in the EU ETS(European Union Emissions Trading Scheme), commercial entities will invest inindustrial-scale projects. To enable deployment before it can be financed by the EU
ETS, a combination of national and European policies is essential. To allow thedevelopment of those policies and reduce the cost of deployment, the implementationof 10-12 large-scale demonstration projects is therefore vital. The chart illustrates theimpact of 10 such projects, enabled by European early mover funding mechanisms. Insuch demonstration projects, the implementation of 700oC+ technology is of vitalimportance.
Figure 3: Development of ZEPs by 2020.
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Further to the R,D&D activities, strong cooperation from all stakeholders in order tooptimise resources and avoid duplication is required. EC is already co-ordinatingMember State activities through the European Research Area, e.g. FENCO ERA-NETinitiative, which runs from 2005-2009. This ERA-NET aims to coordinate nationalagencies and governments and improve the cooperation between national RTD
programmes towards the enforcement of European research skills in CCS. EC playsalso an active role in many global initiatives, eg. the Committee of Energy andInternational Energy Agency (IEA) and the Carbon Sequestration Leadership Forum(CLSF), which involves 22 countries worldwide. At the same time, it sponsors and
participates in the IEA Greenhouse Gas and Clean Coal Centre ImplementingAgreements.
From the R&D initiatives that have already taken place, it is clear that many technicalaspects of large-scale CO2 storage are suitable for international co-operation. For thisreason, opportunities for international collaborative projects should be included withinthe Seventh Framework Program (FP7). This would not only ensure continuity in the
collaboration already initiated (e.g. with China), but pave the way for further co-operation with other major industrial countries, as well as emerging economies.
7. Conclusions
The present study was focused on the technological aspects of the 700 oC power planttechnology especially for low quality brown coals and the funding opportunities forits demonstration. Although significant progress can be reported on the componentmaterial development and the plant design, the main fuel taken into consideration ishard coal or high quality brown coal and no investigations have been performed forthe case of low rank coals, which is the main objective of this effort.
The thermodynamic analysis carried out in the study shows that the expectedefficiency of a 700 oC power plant burning low rank coal, such as the Greek coal, isup to 42% when using a conventional lignite drying system, and up to 50% in the caseof using a pre drying system based on the WTA technology. Compared to the current,state of the art efficiency value of 36% for a Greek power plant, the calculatedfeasible increase of 6-14 percentage points indicates the substantial potential of the700 oC concept and the WTA pre drying for this kind of fuels. The furtherdemonstration of the major and minor components and of a first plant prototype isregarded as the necessary next step towards the technologys commercialization.
For this target a general study on the funding opportunities for such a technology
demonstration action was carried out. The study included the main research programsand funds in Europe and the US, which support the further development of theconventional fossil fuel power plant technology. The research and demonstrationactivities in Europe for the new generation of fossil fuel power plants are mainlyfunded by the European Commission through the 6th and 7th Framework Programmeand the Research Fund for Coal and Steel. Especially for FP7, a separate cooperationtheme has been allocated exclusively for Energy. The main objective in this priority isto adapt the fossil-fuel based energy system into a more sustainable one with
particular attention to lower and non-CO2 emitting energy technologies combinedwith enhanced energy efficiency and conservation. A separate project is expected to
be appointed for the demonstration of advanced and ultra-supercritical steam cycle.Efforts will be undertaken for follow-up activities in the AD700/2 FP5 and
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COMTES700 RFCS projects, with the ultimate goal to achieve 700C steamtemperature and pressure of 300 bar based on coal. Work is required on the materialsdevelopment, component manufacturing, testing, and demonstration in realconditions.
In the US, the R,D&D activities in the Clean Coal Technologies are funded by theDepartment of Energy through a number of Initiatives like the Clean Coal PowerInitiative and the Advanced Material Research Project.
Finally, the results of the Technology Platform for Zero Emission Fossil Fuel PowerPlants (ZEP) are presented, with which the AD700 technology is closely related. Onecan distinguish the need for further activities in the three directions of R&D,demonstration and international collaboration projects. Clean coal technology R&D
projects should focus on the needs to improve plant efficiency, reliability and costs.The main goal for steam power plants is to achieve over 50% efficiency by designingnovel steam turbines and further developing boiler technology for steam parameters of700 oC+. To enable deployment of the technology, the implementation of 10-12
large-scale demonstration projects is vital. Further to the R,D&D activities, strongcooperation from all stakeholders in order to optimise resources and avoid duplicationis required. Part of all aforementioned activities has been included in the FP7.
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