Comparison of the hot flue gas aerosol of 2 municipal waste incineration plants exhibiting significantly different super heater corrosion rates

Transcription

1 Comparison of the hot flue gas aerosol of 2 municipal waste incineration plants exhibiting significantly different super heater corrosion rates Christian Deuerling 1, Jürgen Maguhn 1, Hermann Nordsieck 2, Ragnar Warnecke 3 and Ralf Zimmermann 1,2,4 1 Institute of Ecological Chemistry, Helmholtz Zentrum München, Neuherberg, Germany 2 bifa-environmental Institute, Augsburg, Germany 3 GKS Gemeinschaftskraftwerk Schweinfurt GmbH, Schweinfurt, Germany 4 University of Rostock, Germany EAC 2008, Thessaloniki, Greece August 27, 2008 Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

2 Reduction of Corrosion in Municipal Waste Incineration Plants (MSWI) Situation Corrosion rate of the superheaters in MSWI can vary extremely. Maintenance time at different (similar) plants: between approx. 1 and 10 years High costs due to corrosion in many plants Potentially influencing parameters: (Solid) fuel mixture and condition Operation mode / burning parameters Boiler geometry and construction Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

3 Reduction of Corrosion in Municipal Waste Incineration Plants (MSWI) Particles Decisive impact on the corrosion process: Substrate of reactive compounds, like heavy metals and salts Corrosion is most intense at regions of thickest fouling Particle mass concentration Particle size distribution Particle chemical composition Particle deposition/adhesion Gas phase Condensables SO 2, HCl - correlating with sulphation of the particles Task: Characterization of particles (30 nm 3 mm aerodynamic diameter) and gas phase in the raw gas from the combustion chamber to the point of corrosion Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

4 Porous Tube Diluter (PTD) Sampling Probe Use of a Porous Tube Diluter (PTD): Rapid dilution of the raw gas (5x-10x) Rapid cooling to T = 300 C Minimize further chemical reactions Minimize coagulation, nucleation, condensation Minimize thermophoretic and inertial impaction sample suction scales consistant steel porous tube heated tube coolant outlet dilution air inlet sampling suction swan neck inlet Total length: approx mm, diameter: approx. 55 mm coolant inlet Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

5 Measuring Ranges of the Applied Instruments Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

6 Sampling System Synchronous sampling of gaseous and particulate matter Each measurement was carried out by 2 sampling systems running in parallel: 1) reference point: 2nd pass 2) further pass Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

7 2 Plants exhibiting different Corrosion Rates Plant A: 0.33mm/1000h; several measurement campaigns since 2005 Plant B: < 0.05 mm/1000h; 2-week measurement campaign in 2007 Plant A Plant B Heat power 20 MW 40 MW Steam parameter 65 bar / 435 C 40 bar / 400 C Boiler construction Vereinfachter Kesselschnitt Anlage B 37 28,3m ÜH 2 ÜH ,7m ÜH 3 ECO ,0m ÜH 4 ECO 5 20,5m ÜH 6 ECO ,5m ÜH 5 ECO ,7m ECO 2 21 Measuring Points 10,7m ECO ,5m 9,4 6,0 4 pass, vertical 4 pass, vertical Grate, fire zone co-current reciprocating grate, first pass at grate front rotating rollers, first pass at grate end Corrosion rate (SH) 0.33 mm / 1000 h < 0.05 mm / 1000 h Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

8 Results Total Mass Concentration of the 4 Passes Plant A Total Mass Concentration in each pass Mass conc. [mg/m³] g/m³ 3.18 g/m³ 2.64 g/m³ 2.08 g/m³ 1st pass 2nd pass 3rd pass 4th pass ELPI APS Isokinetic divider I Sampling Tube Passage Inlet-PTD PTD Cyclone Inlet Total dust mass annualized from particle measurements: 840 t/a (7490 operation h/a, 7250 kg waste/h, 4500 m³n/t waste) Total dust mass according to operator s (GKS) data: 915 t/a (deviation: 8 %) Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

9 Raw Gas Particulate Matter: Total Mass Concentration Anlage J Massenkonzentration conc. [g/m³] (g/m³) Plant A st 1. Zug pass 2nd 2. Zug pass 3rd 3. Zug pass 4th 4. Zug pass Anlage B 3.5 ELPI 3 APS 2.5 Massenkonzentration (g/m³) 2 Cyclone Zyklon 1.5 Inlet Einlasskrümmer Plant B 1st 1. Zug pass 2nd 2. Zug pass 3rd 3. Zug pass 4th 4. pass Zug Plant B Significantly lower total mass concentration Less reduction through the boiler (corresponds with the observed lower tendency for fouling) Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

10 Chemical Composition of Particles of 2nd pass All Size Fractions Plant A Plant B Massenanteil conc. % Rest Cl S Pb Zn K Na Ca Si >0.063 >0.125 >0.250 >0.500 >1.000 >2.000 >4.000 >8.000 >20 >63 >125 >250 >500 >1000 Particle Partikelfraktion size fraction [µm] Krümmer Inlet >0.063 >0.125 >0.250 >0.500 >1.000 >2.000 >4.000 > Particle Partikelfraktion size fraction [µm] > 125 Krümmer Inlet Fine fraction (secondary particles): A: (Na, K, Cl) B: more non-na/k/cl (more Na, less K/Cl) Coarse fraction (primary particles): A/B: Ca, Si, High "Rest" Inlet: A/B: mixture of all fractions Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

11 Chemical Composition of Particles of all 4 Passes Plant A Chemical Composition 1st pass Chemical Composition 2nd pass Mass conc. [%] Mass conc. [%] Rest Cl S Pb Zn K Na Ca Si < > 20 Inlet Particle fraction [µm] < >20 Inlet Particle fraction Chemical Composition 3rd pass Chemical Composition 4rd pass Mass conc. [%] Mass conc. [%] Fine fraction: Reduction of Cl (1 2) Increase of S (1 2) Coarse fraction/inlet: No significant changes 2 2 < >20 Inlet < >20 Inlet Particle fraction Particle fraction Inlet of 4th pass nearly blank Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

12 Chemical Composition of Particles of all 4 Passes Plant B 10 Chemical Composition 1st pass 10 Chemical Composition 2nd pass Mass conc. % Rest Cl S Pb Zn K Na Ca Si < 1µm 1-20µm > 20µm Inlet < 1µm 1-20µm > 20µm Inlet Particle fraction Particle fraction Chemical Composition 3rd pass Chemical Composition 4rd pass Fine fraction: Reduction of Cl (1 2) Increase of S (1 2) Mass conc. % Coarse fraction/inlet: No significant changes < 1µm 1-20µm > 20µm Inlet Particle fraction < 1µm 1-20µm > 20µm Inlet Inlet of 4th pass nearly blank Particle fraction Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

13 Size Fractionated Mass Concentration of the 4 Passes Plant GKS A - Mass Concentration, 1st - 4th Pass (mean values) 10 1 Mass Conc. [g/m³] Particle size [µm] 1st pass 2nd pass 3rd pass 4th pass Bimodal distribution: 1 st mode: secondary particles (nucleation, condensation). Maximum shifts to slightly higher values (coagulation, condensation), nearly no reduction. 2 nd mode: primary particles (ashes, calcium oxide spherules). Similar particle mass conc. as 1 st mode; however, more reduced along the flue gas duct (impaction). Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

14 Size Fractionated Mass Concentration Plant A : Plant B Plant GKS A - Mass Concentration, 1st - 4th Pass (mean values) 10 1 Fine fraction: (< 1 µm): nearly equal Midsize fraction (1-20 µm): more at plant B! Coarse fraction (> 20 µm): less at plant B Mass Conc. [g/m³] Mass Conc. [g/m³] Particle size [µm] 1st pass 2nd pass 3rd pass 4th pass Plant AEZ B - Mass Concentration, 1st - 4th Pass (mean values) Particle size [µm] 1st pass 2nd pass 3rd pass 4th pass Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

15 Sulphation of Particles Sulphation Sulphation of the chlorides is supposed to play a key role in corrosion processes of MSI super heaters. If sulphation occurs during the flight of chloride containing aerosol particles, chlorine is released mainly as indifferent HCl, as concerning corrosion: 2 KCl + SO 3 + H 2 O K 2 SO HCl (1) The sulphation of particles already deposited on superheater tubes is supposed to result in the formation of active chlorine that subsequently reacts with the iron of the tube steel: 2 NaCl + SO 3 + ½ O 2 Na 2 SO 4 + Cl 2 (2) Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

16 Sulphation: Plant A : Plant B (Particles (Particle < 10µm, fraction 1st < 10µm) 2nd pass) Plant A Plant B Equivalent Conc. [Eq/kg] p1_n1 p2_n1 p1_n2 p2_n2 p1_n3 p2_n3 Sulfur Chlorine 12,0 10,0 8,0 6,0 4,0 2,0 0,0 Zug _n1 Zug _n1 Zug _n2 Zug _n2 Zug _n3 Zug _n3 Plant A: Sulphation of approx. 2 of the chlorides along the flight before reaching the SH Plant B: Sulphation of approx. 3 of the chlorides along the flight before reaching the SH This conversion corresponds with an increase of the hydrogen chloride content of the raw gas. Nordsieck et al., 2008 Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

17 Adhesive Properties 3rd pass: Comparison of chemical composition of 4 fractions 2nd look 6 Zug 3, < 1 µm Anlage Plant B Anlage Plant A J 6 Zug 3, 1-20 µm Si Ca Na+K Pb+Zn S Cl Rest Zug 3, > 20 µm Anlage Plant B Anlage Plant A J 6 Si Ca Na+K Pb+Zn S Cl Rest Zug 3, Krümmer Si Ca Na+K Pb+Zn S Cl Rest Si Ca Na+K Pb+Zn S Cl Rest Nordsieck et al., 2008 Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

18 Conclusions Comparison of plant A (high corrosion rates) and plant B (low corrosion rates): Plant B: Total mass concentration (TMC) is lower, especially the coarse fraction portion Lower reduction of TMC along the boiler passes Higher Sulphation achieved before particles reach the superheaters Probably less stickiness of mid and coarse size particles (different chemical composition, mid fraction stays higher until boiler end) High temperature aerosol analysis has discovered several corrosiontriggering properties which all are suitable to amplify corrosion at plant A. With this set of indicators it should be possible to directly control (and later perhaps even quantify) the real effect of actions undertaken to reduce corrosion at the measured or at any other plant. Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,

19 Thank you for your attention! Municipal Waste Incineration Plant ACKNOWLEDGEMENTS: This project is funded by the Bayerisches Staatsministerium für Umwelt, Gesundheit und Verbraucherschutz within the scope of the European Regional Development Fund (ERDF). Christian Deuerling would like to thank the Buchner Foundation for kind support. Christian Deuerling, Jürgen Maguhn, Hermann Nordsieck, et al. EAC 2008, Thessaloniki,