ACERC conference 20 21 Feb Salt Lake City

ACERC conference, 20 -21 Feb, Salt Lake City Reducing corrosion and ash deposition in Dutch Wt. E plants TNO Environment, Energy and Process Innovation t Jaap Koppejan

Content • General info on Dutch waste incineration sector • Corrosion processes • Corrosionreductionmeasures t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 2

Waste to Energy plants in the Netherlands • 11 installations, total capacity approx. 5. 5 Mton • Existing. Wt. E plants were retrofitted in 90’s • Very low emissions t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 3

3, 11% O ) Emission limits (dry m 2 Component Emissionlimit total dust 5 mg/m 3 HCl 10 mg/m 3 HF 1 mg/m 3 CO 50 mg/m 3 VOC 10 mg/m 3 SO 2 40 mg/m 3 NOx 70 mg/m 3 Sum of heavy metals 1 mg/m 3 Cd 0, 05 mg/m 3 Hg 0, 05 mg/m 3 PCDD's + PCDF's 0, 1 ng I-TEQ/m 3 t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 4

Wt. E plantsin the. Netherlands Processing capacity E-Power output Heat output Number of lines Date of operation kton/yr MWe MWth Alkmaar 465 42 3 1995 Amsterdam 840 80 4 1993 Rotterdam 380 26 4 1962 Rijnmond 1150 108 7 1972 (6 lines) 1995 (1 line) Roosendaal 67 14 MWth 2 1972 Dordrecht 240 9 4 1972 / 1992 Moerdijk 600 3 1997 Nijmegen 340 28 2 1987/1995 Arnhem 360 25 3 1985/1990/1991 Hengelo 285 26 2 1997 Wijster 720 48 3 1996 t 100 (distilled water) 195 Steam to CHP 75 (district Heating) Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 5

Need for increased availability • Typical: • steam conditions 40 Bar/400°C, efficiency 22% • Availability in hours/year: 90% • 1 day productionloss equals about 125, 000 $ ® corrosion in first pass and boiler is major reason for production loss. • Higher steam conditions needed for higher efficiencies (e. g. 100 Bar/500°C) ® Corrosion and deposition problems t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 6

Overview of corrosion processes in Wt. Eboilers Boiler: 400°C/ 40 Bar Boiler water wall chlorides +CO ~700°C Ev S S Ev Ec Ec 900 -1100°C Ceramic Lining Na. Cl(g) > Na. Cl(s) chlorides +H 2 O gas Na. Cl Zn. Cl 2 Sulphates of Na. Cl and Zn. Cl 2 Generation of Volatile chlorides Super heaters Cl-gas corrosion Na. Cl+ SO 2 + O 2 = Na 2 SO 4 + Cl 2 Fe + Cl 2 = Fe. Cl 2 + O 2 = Fe 3 O 4 + Cl 2 Grate t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 7

Typical temperatures in boilers of Wt. Eplants Boilerpart Steam T metal °C T gas °C Waterwall, evaporator 265 °C ~ 300°C ~ 1100 -700 °C Evaporator tubes 265 °C ~ 300 °C Superheater 400 °C ~ 450 °C t Reducing corrosion and ash deposition in waste incinerators ~ 800 -700 °C ~ 700 -600 °C Feb 20, 2003 8

Typical corrosion in Dutch Wt. E plants Evaporator Superheater Metal temperature ~ 250 -300 °C ~ 400 -530 °C Construction Membrane wall Tube bundles Material C-steel (St. 35. 8) Alloy (15 Mo 3) Typical corrosion velocities 0, 15 -0, 30 mm/y 0, 20 -0, 40 mm/y t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 9

Corrosionon water walls 1. CO corrosionat locations withreducing conditions t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 10

CO corrosion on furnace walls Carbon steel corrosion at 450 °C t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 11

Corrosionon water walls 1. CO corrosionat locations withreducing conditions 2. Corrosion by metal chloride deposits 3. Erosion due to high dust loads and high local velocities 4. Missing refractory tiles t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 12

Corrosion on superheater tubes t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 13

Corrosionon superheatertubes 1. Corrosion by. Cl 2 or HCl containing gas(active oxidation) 2. Corrosion by metal chloride deposits 3. Erosion due to high dust loads and local high velocities 4. Sulphate corrosion (less influence) t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 14

Active oxidation from Cl in gas at 500 C, no SO 2 1. 2 Na. Cl + Fe 2 O 3 + ½ O 2 = Na 2 Fe 2 O 4 + Cl 2 2. Fe + Cl 2 = Fe. Cl 2 , attaching. Fe 3 O 4 layer t Metal chloride T 4 (°C) Fe. Cl 2 536 Fe. Cl 3 167 Cr. Cl 2 741 Cr. Cl 3 611 Ni. Cl 2 607 Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 15

Corrosionreductionmeasures 1. Combustionconditions 2. Boiler cleaning mechanisms 3. Materials used 4. Boiler design t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 16

1. Combustionconditions • Improvement of air distribution • Optimisation of combustion behaviour • Better fluegas temperature control t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 17

2. Improved boilercleaningmechanism • Removal/adaptation of soot blowers • Optimisation of boiler tube cleaning system • Cleaning with dynamite/gas explosions • Water jet cleaning t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 18

Cleaning withexplosives t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 19

Effect of cleaning with explosives 750 700 650 Flue gas temperature 600 550 500 450 400 350 300 250 200 150 100 50 0 jan-01 feb-01 apr-01 jun-01 jul-01 sep-01 nov-01 dec-01 feb-02 apr-02 mei-02 jul-02 sep-02 date t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 20

3. More advanced materials • Cladding Alloy 625 t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 21

steel 15 Mo 3 tube corrosion t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 22

Alloy 625 tubecorrosion t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 23

3. More advanced materials • Cladding, e. g. Alloy 625 • Compositetubesfor superheaters • Advanced refractory on membrane walls , e. g. Si. C tiles or better fixation t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 24

4. Adaptations of design: • Super heater configuration t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 25

Changing configurationof super heater bundles Temperatures and corrosion of 15 Mo 3/St 35. 8 600 Steam temperature °C 550 Much corrosion 500 450 Little corrosion 400 350 300 250 2 3 1 200 450 500 550 600 650 700 750 800 Flue gas temperature °C t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 26

$4. Adaptations of design: • Super heaterbundleconfiguration • Water injectionin steamsystem • Increasingrefractory areaor$

4. Adaptations of design: • Super heaterbundleconfiguration • Water injectionin steamsystem • Increasingrefractory areaor claddingin first pass • Water cooled grate (if sufficient heating value) t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 27

Summary: Good experiences exist in the Netherlands with • Optimization of combustion process (case specific) • Improved boiler tube cleaning • Improved materials and constructions (cladding, superheaterconfiguration) t Reducing corrosion and ash deposition in waste incinerators Feb 20, 2003 28