2nd IEA Oxyfuel Combustion Conference

Transcription

1 2nd IEA Oxyfuel Combustion Conference Oxyfuel Combustion with Hitachi's DST - Burner at Vattenfall's 30Wth Pilot Plant at Schwarze Pumpe S. Rehfeldt, F.-P. Schiffer, P. Weckes, C. Bergins, K.-D. Tigges 14th of Sept. 2011

2 OxPP Schwarze Pumpe, Germany Boiler ESP ASU FGD FGC CO 2 Plant Image: Courtesy of Vattenfall 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 2

3 Burner Simplified process flow sheet (air firing) Coal Air Stack SH ECO FGD OFA1 ESP OFA2 Air 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 3

4 Burner Simplified process flow sheet (Oxyfuel) Coal CO 2 purification plant CO 2 SH ECO FGC FGD OFA1 ESP OFA2 RFG RFG+O 2 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia O 2 Hitachi Power Europe GmbH 4

5 Coal features Standard fuel: pre-dried lignite Fixed Carbon 38.5 % by wt. C 57.5 % by wt. Volatiles 45.7 % by wt. H 4.16 % by wt. Ash 5.6 % by wt. N 0.63 % by wt. oisture 10.2 % by wt. S 0.61 % by wt. Particle size distribution: 7 % > 0.2 mm 0.3 % > 0.5 mm Testing of lignite with higher sulfur content Sulfur content 1.56 % by wt. 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 5

6 DST burner Hours installed: h (19 th of April 16 th of June) Oxyfuel operation: h Air operation: h 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 6

7 Oxyfuel operation - Oxyfuel flame example Heat input: 27 W th O 2 in oxydant: 32 % by vol. (wet) NO x : 416 mg/m³ = 0.13 kg/wh 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 7

8 Premixed / hybrid mode Premixed mode DST burner Hybrid mode DST burner Flue gas Flue gas + O 2 Flue gas O 2 O 2 O 2 O 2 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 8

9 Proven operational range Premixed mode High flame stability, 23 to 36 % by vol. (wet) oxygen in oxidant Corresponding recirculation rate 53 to 66 % Combustion stoichiometries < 1.15 always keeping CO- und NOx emission limits O 2 Flue gas Premixed mode DST burner Flue gas + O 2 Hybrid mode High flame stability, < 17 to 36 % by vol. (wet) oxygen in oxidant Flue gas recirculation rate > 75 % O 2 in flue gas 1.3 % by vol. (wet) measured at ESP exit always low CO and NOx emission rates, keeping limits O 2 Flue gas Hybrid mode DST burner O 2 O 2 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 9

10 Proven operational range Combustion stoichiometry: λ=1.10 λ=1.15 O 2 in oxidant [% by vol. (wet)] Premixed Hybrid O 2 in flue gas [% by vol. (wet)] CO emission rate < 0.2 kg/wh (permitted emission limit 0.2 kg/wh) NO x emission rate << 0.27 kg/wh* (permitted emission limit 0.54 kg/wh) *equals 200 mg/m³ 7% O2 in air firing 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 10

11 easuring levels and ports for temperature and species DST-burner Level 0, only one port Rear wall OFA 1 (3 nozzles each side) OFA 2 (out of operation) Level 1 Level 2 Front wall Level 3 Level 4 Level 5 Level 6 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 11

12 Findings from CFD results Boudouard reaction C + CO 2 2 CO Production of intermediate species CO without Boudouard reaction too weak Temperatures without Boudouard reaction much too high Heterogeneous watergas reaction C + H 2 O CO + H 2 Temperatures without heterogeneous watergas reaction too high Exact Arrhenius parameters required Parameters have been determined according to the analysis of the coal by Hitachi Research Laboratory, Hitachi, Japan 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 12

13 Temperature [ C] CFD results: Temperatures Temperature [ C] Level 3 Intrinsic easurements Boudouard+Watergas Distance from wall [mm] 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 13

14 CO [% by vol., dry] CFD results: CO concentration CO [% by vol., dry] 20 Level 3 Boudouard+Watergas easurements Intrinsic Distance from wall [mm] 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 14

15 easured heat flux to the furnace walls Oxy24 Oxy28 Oxy32 Oxy36 Air Level 1 Level 2 Level 3 Level 4 Level Radiative Heat Flux [kw/m²] Higher velocities in air firing lead to different flame shape different temperature different heat flux distribution 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 15

16 Results on heat transfer Radiative heat flux depends mainly on temperatures Heat fluxes to the furnace walls increase with increasing O 2 concentration As a consequence the feed water attemperation decreases 1200 Feed water attemperation 1000 Heat uptake in evaporator and convective path is influenced by many factors, such as the physical and optical properties of the flue gas, velocities, and temperatures Similar heat transfer (Oxyfuel / air firing) in radiative and convective section of the boiler can be adjusted by a certain oxygen concentration [g/s] O 2 in oxidant [% by vol. (wet)] 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 16

17 Heat uptake by Economizer [%] Heat uptake by Evaporator [%] Heat transfer calculations (HPE s boiler design software) Ad. Temp. [ C] Oxyfuel Oxyfuel Air (21% O2) Air (21% O2) O 2 in oxidant [% by vol. (wet)] O 2 in oxidant [% by vol. (wet)] Air (21% O2) Oxyfuel O 2 in oxidant [% by vol. (wet)] Similar heat transfer in evaporator and convective section by choosing the right oxygen concentration Easy retrofit of existing boilers is possible without major reconstruction works New builds can be designed flexibly 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 17

18 SO 3 measurements (sulfur rich coal combustion) SO 3 [mg/m³ (STP, dry)] Air Firing Oxyfuel ECO5 GGH ESP SO 2 /SO 3 conversion rates determined downstream of the gas-gas preheater (GGH) Air mode Oxyfuel 0.99 % 0.67 % 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 18

19 Summary Stable and safe operation of DST burner Low CO, NO x and low O 2 excess Stable flame proved in a O 2 concentration range 16 to 36 vol. % (wet) Combustion simulation Verification of modeling tools successful Heterogeneous reactions (Boudouard, Watergas) included Heat transfer investigations Similar heat transfer can be achieved by adjusting the O 2 concentration Easy retrofit of existing boilers SO 3 measurements Lower SO 2 /SO 3 conversion rate found for Oxyfuel However, SO 3 concentration is higher in Oxyfuel operation 2nd International Oxyfuel Combustion Conference, 12th-16th September 2011, Yeppoon, Australia Hitachi Power Europe GmbH 19

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