Oslo, February 17th, 2010

Transcription

1 Oslo, February 17th, 2010 HIGH DUST SELECTIVE CATALYTIC NOx REDUCTION AT WTE PLANT IN BRESCIA Paolo Rossignoli Mario Nenci Lorenzo Zaniboni A2A, Brescia, Italy

2 INTEGRATED WASTE MANAGEMENT SYSTEM Waste prevention Separate collection (for material recycling) Composting of organic waste Energy from remaining waste (renewable energy) Landfilling minimization (only safe residues)

3 DESIGN GOALS: 1. ENVIRONMENTAL PROTECTION 2. HIGH EFFICIENCY OF ENERGY RECOVERY 3. SAFETY, RELIABILITY, AVAILABILITY

4 DISTRICT HEATING SYSTEM OF BRESCIA 584 km of double pipe inhabitants supplied 38,5 Mm 3 heated volume connected buildings 695 MW MW th 230 MW MW el P.Plant north 1 km P.Plant south WTE

5 TERMOUTILIZZATORE DISTRICT HEATING SYSTEM OF BRESCIA CONNECTED BUILDINGS VOLUMES YEARS Mm 3

6 TERMOUTILIZZATORE DISTRICT HEATING SYSTEM OF BRESCIA USED FUELS NAT. GAS OIL COAL SOLID WASTE and BIOMASSES ANNI GWh

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8 TERMOUTILIZZATORE WASTE BUNKER

9 Combustion grate under construction

10 MAIN TECHNICAL DATA Heat capacity of treated waste (3 boilers) 310 MW Waste throughput 3 x 33 t/h Electrical generation capacity (net) 80 MW el Heat generation capacity 170 MW th ISO Environmental certification in april 2006

11 OPERATIONAL DATA 2008 Treated waste 801,000 tons ( of which biomass tons ) Electricity production (net) 570 GWhel District heating 568 GWhth Fossil fuels saving (Tons of Oil Equivalent) > 150,000 TOE CO 2 avoided emissions > 400,000 tons

12 NOx CONTROL METHODS PRIMARY (NOx prevention) - staged combustion (gradual O 2 supply) - combustion temperature control SECONDARY (NOx reduction) - SNCR (Selective Non-Catalytic Reduction) - SCR (Selective Catalytic Reduction): - High dust (on raw gas) - Tail-end (after gas cleaning) - Low dust (after gas de-dusting)

13 HIGH DUST SCR LOCATION

14 CATALYST LAYER MIXER (SPACE FOR UP TO 5LAYERS) DAMPERS NOx NOx FLUE GAS HIGH DUST SCR LAYOUT

15 IMPLEMENTED NOx CONTROL IN BRESCIA WTE (starting situation - since 1998) PRIMARY - low combustion excess air - 30 compartment grate - infrared camera for optimization of primary and secondary air supply - flue gas recirculation TERMOUTILIZZATORE SECONDARY (NOx reduction) - SNCR (NH 3 injection with 27 nozzles, positioned at three levels)

16 SNCR DENOX SYSTEM

17 INSTALLATION AND TESTING OF A SCR HIGH DUST SYSTEM (non industrially available yet) GOALS: - further NOx reduction ( mg/nm 3 ) - ammonia slip improvement - lowering ammonia consumption - keep high energy plant efficiency

18 PROBLEMS: SCR HIGH DUST SYSTEM (non industrially available yet) - catalyst clogging - catalyst poisoning ADVANTAGES: - much higher energy efficiency (no need of gas reheating and lower gas pressure losses) - simpler installation - lower investment and operating cost

19 installation: 2005 Sep Feb. operation: inspection: 2 nd phase: TERMOUTILIZZATORE SCR HIGH DUST History highlights started 2006 Mar. (1 st phase one cat. layer) Sep (cleaning and catalyst analysis showing some pore plugging and catalyst poisoning with sulphates) started 2006 Oct. after inspection (2 cat. layer) inspections: 2007 Apr. and Sep. (only cleaning) 2008 Apr. (erosion starts to become evident) November: removal of one layer and installation of a new 2008 layer

20 SPACE FOR SCR HIGH DUST INSTALLATION

21 TERMOUTILIZZATORE (The waste to energy plant of Brescia HIGH DUST SCR SPACE FOR SCR HIGH DUST INSTALLATION

22 CATALYST UNDER CONSTRUCTION

23 HIGH DUST SCR RESULTS SCR operation start (1 layer) NO x- NH 3 emissions 90 Start with 600 NO x - NH 3 stack emissions [mg/nm³] nd layer NH 3 consumption [l/h] NOx NH3 slip NH3 cons , ,3 1,8 3,7 2,5 4 4, /1/06 1/5/06 29/8/06 27/12/06 26/4/07 24/8/07 22/12/07 20/4/08 18/8/08 16/12/08 15/4/09 13/8/09 11/12/09 0 NOx NH 3 consumption ammonia slip

24 HIGH DUST SCR RESULTS Start with 2 nd layer T, p SCR 325 3, , , , , ,75 T [ C] ,50 1,25 p [mbar] T SCR [ C] Dp [mbar] 100 1, , , ,25 0 3/7/06 31/10/06 28/2/07 28/6/07 26/10/07 23/2/08 22/6/08 20/10/08 17/2/09 17/6/09 15/10/09 0,00 T gas p SCR

25 NOx and NH3 emissions monthly media May-09 Mar-09 Jan-09 Nov-08 Sep-08 Jul-08 May-08 Mar-08 Jan-08 Nov-07 Sep-07 Jul-07 May-07 Mar-07 Jan-07 Nov-06 Sep-06 Jul-06 May-06 Mar-06 Jan TERMOUTILIZZATORE L1 NOx L1 NH3 L2 NOX month L2 NH3 mg/nm3

26 SCR HIGH DUST TEST RESULTS L1: SNCR only L2: SNCR + HD SCR (2 layers) NOx: mg/nm 3 NH 3 slip: mg/nm 3 NH 3 consumption: m 3 /h (25% concentrated) Pressure losses: negligible

27 HIGH DUST SCR Modifications of the catalyst to reduce erosion new geometry in order to increase plates stiffness increasing plates thickness new composition of the catalyst material in order to increase plates hardness

28 TERMOUTILIZZATORE CATALYST AFTER 2 YEARS OF OPERATION After Cleaning Before Cleaning

29 TERMOUTILIZZATORE HIGH DUST SCR INSPECTION OCTOBER 2009 CATALYST REMOVED AFTER 32 MONTHS OF OPERATION

30 TERMOUTILIZZATORE HIGH DUST SCR INSPECTION OCTOBER 2009

31 TERMOUTILIZZATORE HIGH DUST SCR CATALYST REMOVED AFTER 32 MONTHS OF OPERATION

32 TERMOUTILIZZATORE HIGH DUST SCR CATALYST REMOVED AFTER 32 MONTHS OF OPERATION

33 HIGH DUST SCR FUTURE TEST STEPS : monitoring of fouling and activity of catalyst with new geometry optimization of catalyst layout (single / multiple layers) optimization of duct cleaning with modified geometry lifetime assessment of the catalyst with new materials industrial cost evaluation

34 HIGH DUST SCR CONCLUSIONS: improving the reaction between ammonia and NOx low impact on the plant efficiency: small pressure losses and low impact on fan consumption life-time rather short, but costs relatively small in comparison with other SCR systems: costs for reheating the flue gas and energy for IDfan (vs Tail-end) costs for ammonia consumption (vs pure SNCR)

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