Greek Lignite / Cardoon co-firing at PPC Kardia PP

Transcription

1 Centre for Research and Technology Hellas Institute for Solid Fuels Technology and Applications (CERTH / ISFTA) Greek Lignite / Cardoon co-firing at PPC Kardia PP 2 nd International Workshop on Bio-CCS th October 2011, Cardiff, Wales CERTH (GR): Emmanouil Karampinis *, Panagiotis Grammelis, Emmanuel Kakaras IFK (DE): Aaron Fuller, Eva Miller, Joerg Maier ECN (NL): Jana Kalivodova ALSTOM (DE): Markus Michel, Ioannis Tsolakidis * Tel: , Fax : , karampinis@certh.gr

2 Introduction Support mechanisms for co-firing biomass Green Certificates or feed-in tariff systems for bioenergy; Financially supported by many EU countries (e.g. NL, UK, DK), limited or no support in others (e.g. BE, FR, DE); Biomass availability and market Imported biomass for electricity and heating sector important for meeting targets in some countries (e.g. NL, UK), while others rely on domestic biomass sources; Growing EU and international wood pellet trade; Competition with traditional end-user of wood (paper & pulp industry, etc) and domestic heating sector Growing interest for agricultural biomass; however, limited market and supply chain development Technical issues Substitution of coal with biomass up to 10-20% on energy basis typically considered easy to implement, at least for woody biomass; Growing trend to increase co-firing percentage above the typical limit or repower to 100% biomass combustion due to structure of support mechanisms; Issues related to slagging / fouling and corrosion, especially for herbaceous biomass; 2

3 A collaborative project with 17 partners (electricity utilities, research institutes, industrial partners). Greece: PPC & CERTH / ISFTA Budget: ~ 7 M / Duration: Jan Dec 2011 Demonstration and assessment of advanced and innovative co-firing techniques focusing on : Fuel supply chains for different bio-fuel qualities (wood pellets, agro-biomass, RDF); The application of advanced co-firing techniques to a number of pulverised fuel power plants burning both lignite and bituminous coals; The detailed evaluation of the role of co-firing in a sustainable energy market, including both the technical and socio-economic impacts. FP7 DEBCO Project Demonstration of Large Scale Biomass CO-Firing and Supply Chain Integration /

4 Greek Energy Sector & Co-firing Energy Sector and Lignite Greek energy sector domineered by lignite (>50% of electricity production), followed by natural gas, oil (mostly for noninterconnected islands) and hydropower; Lignite mining and power production takes place mostly in Region of Western Macedonia; operated by Public Power Corporation S.A.; Most power plants are quite old and have low efficiencies and high specific CO 2 emissions; RESe growing constantly and receive strong governmental support through feedin tariff mechanisms; Goal of 40% energy produced from RESe, mostly wind and solar; Biomass and co-firing potential Feed-in tariff: / MWhe depending on capacity (one of the highest in EU); Co-firing eligible for support (at least in theory); Low lignite price and CO 2 cost put limits to the maximum price at plant gate for potential co-firing fuels; Wood biomass is limited or hard to collect and can claim higher prices on growing pellet heating sector; Good availability of agricultural land; many farmers are looking to switch from traditional crops (tobacco, cotton, etc) to energy crops; Co-firing biomass in lignite power plants has the added advantage of acting as support fuel in case of poor lignite quality; 4

5 The Kardia PP Co-firing Project The Kardia Power Plant Located in the Kozani Prefecture, West Macedonia, Greece. 4 Units, total capacity 1250 MWe; co-firing initiative implemented in Unit I (300 MWe) Produces ~13% of the electricity in Greece; Fuel: mostly lignite from the nearby Kardia mine. Low heating value, high moisture, ash and calcium content; Due to poor lignite quality is forced to utilize lignite from other sources, resulting in large variations of quality; Cardoon Cultivation Pilot program initiated by Prefecture of Kozani for energy crops cultivation in order to supply biomass for co-firing trials. Budget ~ 1 m ; 60 farmers with 400 ha total participated; Cynara Cardunculus (cardoon), a herbaceous energy crop of Mediterranean origin was selected as the biomass fuel to be cultivated and combusted due to reported high yield potential with limited input; A supply chain was organized by CERTH, PPC and local agencies taken into account limitations of power plant (e.g. no closed storage or dedicated feeding system); 5

6 Kardia The Joint Measurement Campaign Super heater area: Fouling/slagging probes Cooled corrosion-probe Particle sampling Gas measurements Burner area: APCD: Gas measurement Boiler modelling Emissions evaluation ESP performance Ash characteristics Ash usability Joint Measurement Campaign implemented by PPC (Greece) University of Stuttgart / IFK (Germany) ECN (Netherlands) CERTH/ISFTA (Greece) ALSTOM (Germany) First Scernario - boundary conditions (19 & 25 / 10 / 2010) Boiler load: 100% lignite Second Scernario - boundary conditions (20 22 / 10 / 2010) Boiler load: 90% lignite 10% cardoon 6

7 Indications before the JMC Combustion efficiency Potential increase of unburnt material in bottom ash (CFD modeling) Enhanced combustion conditions in the boiler (CO decrease at pilot units) Limited impact on fly ash burnout Depends on particle size Emissions SOx reduction due to lower sulfer content of cardoon anf calcium retention NOx reduction of up to 10% (CFD modeling, pilot scale combustion) Slagging, Fouling, Corrosion Limited risk of chlorine corrosion at 10% cardoon share (pilot scale combustion) Serious corrosion issues at higher shares Beneficial effect on fouling at 10% thermal share (pilot scale combustion) Risk of fouling (calcium sulfates, alkali chlorides) at higher shares 7

8 Fuel Characterization & Monitoring 8

9 Cardoon / lignite feeding Contemporary chipping through harvesting with forage harvesters; Cardoon quality monitored upon delivery to plant; Yard mixture: 50 tn lignite, 5 thn cardoon (~20% thermal share); Combustion after one month of open storage; Addition of further quantities of lignite straight from the mine for a final thermal share of %; Fuel mixture sampled before the mills; Difficulty to keep constant lignite quality; Harvesting Sampling Chipped cardoon Mixing with lignite

10 Monitoring of cardoon samples (1/2) Moisture (as received) Ash, dry basis Moisturear, mean = ± 3.82 %wt Ashdb, mean = 8.63 ± 1.12 %wt 20.0 weight (%)

11 Monitoring of cardoon samples (2/2) 22.0 LHV (as received) HHV, dry basis 20.0 HHVdb mean = ± 0.51 MJ/kg LHVar, mean = ± 0.87 MJ/kg 18.0 Heating Value (MJ/kg)

12 Fuel Analysis Parameters* Cardoon Lignite 1 ( ) Lignite 2 ( ) Lignite after mill ( ) 10% cardoon mix after mills ( ) Moisture (ar) [% wt] Ash (d.b.) [% w.t.] LHV (raw) [MJ/kg] Parameters* Volatiles (daf) Fixed Cardon (daf) C (daf) H (daf) O diff (daf) N (daf) S (daf) Cl (daf)

13 Ash composition (%) Cardoon Lignite 1* ( ) Sample Lignite 2* ( ) 10% cardoon mix ( ) Al 2 O CaO Fe 2 O K 2 O MgO Na 2 O P 2 O TiO SiO MnO SO Total Sample Mineral Phase Cardoon Lignite Calcite (CaCO 3 ) Dolomite (CaMg(CO 3 ) 2 ) + Hematite (Fe 2 O 3 ) + Anhydrite (CaSO 4 ) Sylvine (KCl) +++ Arcanite (K 2 SO 4 ) +++ Quartz (SiO 2 ) ++ Lime (CaO) +++ Mullite (3Al 2 O 3 2SiO 2 ) + Hematite (Fe 2 O 3 ) + Lignite: high but varying calcium content in several mineral phases (calcite, anydrite, lime), high silica content, Al, Fe Cardoon: high calcium content (calcite), also potassium (sylvine, arcanite). High sodium content in tested sample, probably in amorphous phase 13

14 Ash melting temperatures Fuel Initial Deformation Temperature [ C] Softening Temperature [ C] Hemisphere Temperature [ C] Fluid Temperature [ C] Slagging Index [ C] Cardoon > 1550 > 1550 > 864 Lignite 1* ( ) Lignite 2* ( ) 10% cardoon mix ( ) Cardoon has very low IDT, high potential for slagging Changes in lignite quality are also indicated by changes in the melting temperatures 14

15 Fuel mixture Size: > 10 mm Size: 1-10 mm 15

16 Boiler measurements 16

17 Boiler measurements IFK Particle sampling Uncooled deposition (ceramic probe) Gas measurement Corrosion probe ECN Particle sampling Slagging / fouling probe (cooled probe) IFK Gas measurement 17

18 Particle sampling at 42 m, compositions Parameters Lignite combustion 10% thermal share cardoon Volatiles Ash Burnout (LOI; O C) 0.31 < 0.1 C (daf) S (daf) Cl (daf)

19 19 Samples ash compositions

20 Ash fusion behavior softening range range between ID and HT melting range range between HT and FT Softening range Melting range 1450 Temperature [ C] Deposit lignite Deposit cardoon 10% th. Share FA lignite FA cardoon 10% th. Share 20

21 Conclusion of boiler measurements (1/2) Particle sampling Lignite firing particles were dominated by calcium and silicates; 10% cardoon share particles revealed chlorine, indicating influence of cardoon combustion; lower LOI indicates better combustion conditions; Deposits Significant deposit formation and fouling has been observed during both firing scenarios; Lignite deposits showed calcium sulfates and silicon to be dominant; 10% cardoon deposits showed calcium sulfates, carbon, silicon, iron, and aluminum to be dominant; Potassium detected in form of silicates; decrease of melting point of the ash Fine powdery ash formation and deposition: impaction (W-side) less deposit significant build up on (L-side) No sintering at SH level observed - deposit removal with conventional soot blowing technique High concentration of S in the ash (SO2 autocapture) - possible risk of corrosion; 21

22 Conclusion of boiler measurements (2/2) Corrosion Corrosion probe monitoring verified sulphur induced corrosion; Indications of chlorine induced corrosion not detected; possible beneficial impact of the sulphur content of coal which increases the S:Cl molar ratio Gas formation Addition of cardoon reduced SO 2 emissions; NO x increased contrary to expectation; likely due to more thermal NO x creation from higher temperatures; Higher CO 2 concentration during co-firing suggests improvement of combustion behaviour possibly due to the higher volatile content of cardoon; HCl concentration at 42 m is 5.81 mg / Nm 3, which is quite low compared to other measurements; 22

23 Emissions & ESP 23

24 Stack emissions, NOx 550 concentration (mg/nm 3, dry 6% O 2 ) NOX (10% cardoon) time (h) NOX (lignite) 24

25 Stack emissions, CO 200 concentration (mg/nm 3, dry 6% O 2 ) time (h) CO (10% cardoon) CO (lignite) 25

26 Stack emissions, CO 2 & O concentration (vol. %) time (h) O2 (10% cardoon) O2 (lignite) CO2 (10% cardoon) CO2 (lignite) 26

27 Stack emissions, dust concentration (mg/nm 3, dry 6% O 2 ) time (h) dust(10% cardoon) dust (lignite) 27

28 Stack emissions- future required limits Limit (LCPD) 100% lignite 10% cardoon [mg/nm3] 6% O 2 6% O 2 Emission 6% O 2 [mg/nm3] [mg/nm3] NOx ( ) SO CO Dust Increase of SO 2 emissions usually means lower Dust emissions and vice versa 28

29 ESP Performance 29

30 ESP performance Dust load before and after ESP (mg/nm 3 ) Day Dust [mg/nm 3 ] ESP ESP 1 (before) ESP 2 (after) collection efficiency 20-Oct 29, Oct 45, Oct 26, Photo of a PILAT MARK V cascade impactor 30

31 ESP performance Concentration, normalised [%w/w] Elemental composition of Cascade Impactor measurements at 10% cardoon co-firing before & after ESP Si Al Ti Fe Ca Mg S Na K P Concentration, normalised [%w/w] Cl 0 Si Al Ti Fe Ca Mg S Na K P Cl Course particles: CaO, silicates Fine fraction <1µm: CaO and CaSO 4 31

32 ESP performance high dust emissions due to high ash content of lignite relatively high dust emissions to stack ESP efficiency 99.5% coarse particulates represent the largest fraction by weight; CaO, silicates submicron fraction mainly consists of salts (Ca, K, S, Fe) calcination, sulphation potassium detected in aluminium-silicates agglomerations and also in the fine fraction (K 2 SO 4 ) fine particles (PM2.5) and aerosols are emitted after ESP negative impact on human health 32

33 Ash Characteristics 33

34 34 Fly Ash components

35 Bottom Ash combustible content Parameters [wt.-%] lignite BA ( ) 10% cardoon BA ( ) 10% cardoon BA ( ) 10% cardoon BA ( ) lignite BA ( ) Total moisture LOI Total Carbon Total inorganic Carbon Total organic Carbon

36 Overall conclusions 36

37 Conclusions & Future Needs Main Conclusions Lignite issues: low heating value, high moisture and ash content; Cardoon issues: chlorine content and low IDT may be an issue for dedicated cardoon combustion; Co-firing can be a beneficial option for both fuels; Generally positive results identified for 10% cardoon thermal share in modeling and pilot scale combustion tests; Variations of lignite quality has bigger impact on boiler performance and slagging / fouling that the addition of cardoon; difficulty in judging effect of cardoon addition; However no significant issues were detected during the testing; co-firing cardoon appears to be a promising option to reduce GHG emissions for lignite-fired boilers; Future Needs Increase duration of testing and optimize feeding system; Long-term monitoring of boiler performance anc especially of corrosion potential required; Testing of other types of biomass (agricultural residues, other energy crops) to avoid logistics issues and minimize environmental and supply risks; Identify the optimal biomass thermal share for maximum GHG emissions reduction; Investigate through CFD modeling and pilot testing the co-firing of Greek lignite and biomass under oxy-fuel conditions. Evaluate the potential for applicating both co-firing and CCS technology to newer lignite-fired boilers; 37

38 Thank you for your attention The financial grant of the European Commission through the DEBCO project (TREN/FP7EN/218968) and the support of Public Power Corporation S.A.are gratefully acknowledged. 38