FBC Challenges: Current Research at ÅA-University. by Patrik Yrjas 71 st IEA-FBC, Seoul

Transcription

1 FBC Challenges: Current Research at ÅA-University by Patrik Yrjas 71 st IEA-FBC, Seoul

2 Clustering Innovation Competence of Future Fuels in Power Production Project: CLIFF July June 2017 TAMPERE UNIVERSITY OF TECHNOLOGY

3 Work packages and tasks Task participants WP 0 Scientific co-ordination Co-ordination (research, web-pages, meetings, etc.) AAU WP 1 Fuels and Feedstock 1.1 Fuel advanced analysis and conversion characteristics AAU, Aalto 1.2 Elemental release TUT, AAU 1.3 Bed agglomeration AAU 1.4 Silicate based additives and corrosive vapors AAU 1.5 Plant measurements AAU, Aalto, TUT WP 2 Theoretical and Modelling 2.1 MACT Rule; TSM8 BREF AAU 2.2 Radiation heat transfer modelling LUT, VTT 2.3 Models for Kraft recovery boilers AAU, VTT, Aalto 2.4 Time dependent simulations of BFB furnace processes VTT, AAU 2.5 Improved understanding of FB bed processes VTT, LUT 2.6 Improve modelling of FB wall processes VTT 2.7 Gaseous NO formation/reduction modelling AAU 2.8 Fuel specific models AAU WP 3 Materials 3.1 High temperature erosivity AAU 3.2 Deposit adhesion and sootblowing AAU 3.3 Corrosion metals/coatings/refractories AAU 3.4 Corrosion temperature gradient AAU 3.5 Corrosion detailed mechanisms AAU, TUT 3.6 Use of isotopes in high temperature research AAU, TopA WP 4 Information and international co-operation 4.1 Highlights from conferences, seminars and workshops AAU, VTT, TUT, LUT, Aalto 4.2 Invited speakers to project meetings AAU 4.3 International co-operation AAU, VTT, TUT, LUT, Aalto

4 In this presentation Motivation challenges Task 1.3: Bed agglomeration Task 1.4: Silicate based additives and corrosive vapors Task 3.3: Corrosion - isothermal tests Task 3.4: Corrosion - temperature gradient tests

5 Major ash-forming elements in different fuels CaO+MgO Fossil SiO2 K2O+Na2O ÅA fuel database 5

6 Major ash-forming elements in different fuels 10 CaO+MgO Fossil Peat K2O+Na2O SiO2 ÅA fuel database 6

7 Major ash-forming elements in different fuels 10 CaO+MgO Fossil Peat Wood w Forest residueo Bark o Waste wood wood derived fuels SiO2 K2O+Na2O ÅA fuel database 7

8 Major ash-forming elements in different fuels CaO+MgO Fossil Peat Wood Forest residue Bark Waste wood w o o Agricultural residue wood derived fuels SiO2 K2O+Na2O ÅA fuel database 8

9 Ash chemistry of different fuel types Coal => silicate based ash chemistry, Na, S and Ca Biomass => Ca, K, Na, S, and Cl Agrofuels => Si, Ca, K, P, S and Cl Waste fuels =>...Cl + Zn and Pb (+Br, F) Black liquor => Na, K, S and Cl

10 FBC issues New, more challenging fuels Multi-fuel combustion More power superheater corrosion Standard laboratory ash vs. real boiler ash Advanced analysis of ash forming matter and prediction of ash behavior fouling, slagging, de-fluidization

11 Task 1.3 Bed agglomeration The lab-scale fluidized bed reactor

12 Temperature [ C] Pressure drop [pa] 860 KCl at 850 C T1 T2 Δp Time [s] 0 Defluidization after 12 g (0.5 g/10 min) or 3.1 weight-% of bed weight

13 Temperature [ C] Pressure drop [pa] 910 K 2 CO 3 at 900 C T1 T2 400 Δp Time [s] Defluidization after 3 g (0.5 g/10 min) or 0.8 weight-% of bed weight

14 SEM/EDX images of bed particles 870 C KCl 850 C Pure KCl, no reaction layer No observed reaction with the sand particles KCl acts as glue

15 SEM/EDX images of bed particles C 750 K 2 CO C Reacts with the sand particles forming potassium silicates

16 Phosphate salts Other tests done so far Agglomeration mechanisms in a laboratory bubbling fluidized bed due to addition of different phosphate compounds, C. Sevonius, P. Yrjas, D. Lindberg, M. Hupa, 22 nd FBC, Finland Algea and wood mixtures Agglomeration tendencies of algae and wood mixtures in fluidized bedincineration, C. Sevonius, P. Yrjas, P. Piotrowska, M. Hupa, D. Boström, Conference on Impacts of Fuel Quality on Power Production, USA NaCl and Na 2 CO 3 to be submitted Peat (at 900 C)

17 Task 1.4: Silicate based additives and Absorption of gaseous KCl with kaolin/coal ash => lower corrosion potential Al 2 O 3 2SiO 2 (s) + 2KCl(g) + H 2 O(g) => K 2 O Al 2 O 3 2SiO 2 (s) + 2HCl(g) Use of S-additives may cause a more rapid deactivation SCR-catalysts 2KCl + SO 2 + 1/2O 2 + H 2 O => K 2 SO 4 + 2HCl corrosive vapors

18 Test setup Sample holder Hole for the feeding pipe Air holes KCl crucible holder Lower tube

19 Quartz Kaolin Coal ash 15% H 2 O in air 900 C Example experimental Feeding of KCl Start of experiment Cooling after 10 min Timer stopped when sample was <770 C After experiment: - remaining KCl dissolved and analysed by ion chromatography - samples studied with SEM/EDX

20 Example results * About 300 g/kg is the max. assuming stoichiometry according to: 1. Al 2 Si 2 O 5 (OH )2 Al 2 O 3 *2SiO 2 + 2H 2 O (at about 550 o C) 2. Al 2 O 3 *SiO 2 + 2KCl + H 2 O K 2 O*Al 2 O 3 *2SiO 2 + 2HCl

21 Task 3.3 Corrosion Isothermal corrosion test method at ÅA

22 Data treatment Salt particles Oxide layer Steel Steel Salt Paste Salt particles Oxide layer Steel Epoxy Oxide layer Steel max. min. average etc.

23 Corrosion layer thickness, mm Corrosion layer thickness, mm Weigh-% Corrosion layer thickness, mm Corrosion results, 168 h, (Na, K) 2 SO 4 +(Na,K)Cl Rest 120 Nb Mn Mo Ni 60 Cr Fe % Cl T 0 = 835 C % Cl T 0 =526 C % Cl T 0 =522 C (Skrifvars et al. 2008)

24 Mean oxide layer thickness µm ZnCl 2 T melt = 283 C Demolition wood salts 80 PbCl 2 T melt = 501 C X 38 x x x X 7 x 9 X X Temperature ºC ZnO T melt = 1975 C PbO 10CrMo AISI347 T melt = 886 C x- the oxide layer thickness under the detection limit X = KCl, T melt = 770 C 24 Ref. Dorota Bankiewicz et al., 2012

25 SEM/EDX studies 10CrMo Fe Cr O K Cl

26 Task 3.4 Corrosion - temperature gradient effect on salt and corrosion Steep temperature gradient over superheater and deposit (surface => gas) Laboratory simulations

27 Measured temperatures Salt Ring Temperatures: Sample ring ~ 390 C Salt ~ 475 C, Above the salt ~ 760 C Furnace ~ 900 C

28 T 0 = 626 C T 0 = 537 C NaCl Eutectic salt mix Na 2 SO 4 Sinteredpartly molten Non-sintered

29 Camera experimental set up

30 One test run Sanicro 63 with 548oC, air ambient, first 90 min (1 frame/2 min)

31 Thank you