Oslo, February 17th, 2010 HIGH DUST SELECTIVE CATALYTIC NOx REDUCTION AT WTE PLANT IN BRESCIA Paolo Rossignoli Mario Nenci Lorenzo Zaniboni A2A, Brescia, Italy
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)
DESIGN GOALS: 1. ENVIRONMENTAL PROTECTION 2. HIGH EFFICIENCY OF ENERGY RECOVERY 3. SAFETY, RELIABILITY, AVAILABILITY
DISTRICT HEATING SYSTEM OF BRESCIA 584 km of double pipe 130.000 inhabitants supplied 38,5 Mm 3 heated volume 17.391 connected buildings 695 MW MW th 230 MW MW el P.Plant north 1 km P.Plant south WTE
2.002 2.003 2.004 2.005 2.006 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 TERMOUTILIZZATORE DISTRICT HEATING SYSTEM OF BRESCIA CONNECTED BUILDINGS VOLUMES 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 YEARS Mm 3
2003 2004 2005 2006 TERMOUTILIZZATORE DISTRICT HEATING SYSTEM OF BRESCIA USED FUELS 4.000 3.800 3.600 3.400 3.200 3.000 2.800 2.600 2.400 2.200 2.000 1.800 1.600 1.400 1.200 1.000 800 600 400 200 0 NAT. GAS OIL COAL SOLID WASTE and BIOMASSES 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 ANNI GWh
TERMOUTILIZZATORE WASTE BUNKER
Combustion grate under construction
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 14001 Environmental certification in april 2006
OPERATIONAL DATA 2008 Treated waste 801,000 tons ( of which biomass 270.000 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
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)
HIGH DUST SCR LOCATION
CATALYST LAYER MIXER (SPACE FOR UP TO 5LAYERS) DAMPERS NOx NOx FLUE GAS HIGH DUST SCR LAYOUT
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)
SNCR DENOX SYSTEM
INSTALLATION AND TESTING OF A SCR HIGH DUST SYSTEM (non industrially available yet) GOALS: - further NOx reduction (120 80 mg/nm 3 ) - ammonia slip improvement - lowering ammonia consumption - keep high energy plant efficiency
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
installation: 2005 Sep. 2006 Feb. operation: inspection: 2 nd phase: TERMOUTILIZZATORE SCR HIGH DUST History highlights started 2006 Mar. (1 st phase one cat. layer) Sep. 2006 (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
SPACE FOR SCR HIGH DUST INSTALLATION
TERMOUTILIZZATORE (The waste to energy plant of Brescia HIGH DUST SCR SPACE FOR SCR HIGH DUST INSTALLATION
CATALYST UNDER CONSTRUCTION
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] 80 70 60 50 40 30 74 217 70 179 44 2 nd layer 33 184 66 53 186 61 67 219 58 69 200 500 400 300 200 NH 3 consumption [l/h] NOx NH3 slip NH3 cons. 20 10 12 4,4 8 166 1,3 1,8 3,7 2,5 4 4,9 100 0 1/1/06 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
HIGH DUST SCR RESULTS Start with 2 nd layer T, p SCR 325 3,00 300 2,75 275 2,50 250 2,25 225 2,00 200 1,75 T [ C] 175 150 125 1,50 1,25 p [mbar] T SCR [ C] Dp [mbar] 100 1,00 75 0,75 50 0,50 25 0,25 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
NOx and NH3 emissions monthly media 2006-2007 - 2008-2009 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-06 100 90 80 70 TERMOUTILIZZATORE 60 50 40 30 20 10 0 L1 NOx L1 NH3 L2 NOX month L2 NH3 mg/nm3
SCR HIGH DUST TEST RESULTS L1: SNCR only L2: SNCR + HD SCR (2 layers) NOx: 80-90 60-70 mg/nm 3 NH 3 slip: 10-30 2-6 mg/nm 3 NH 3 consumption: 0.22 0.18 m 3 /h (25% concentrated) Pressure losses: negligible
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
TERMOUTILIZZATORE CATALYST AFTER 2 YEARS OF OPERATION After Cleaning Before Cleaning
TERMOUTILIZZATORE HIGH DUST SCR INSPECTION OCTOBER 2009 CATALYST REMOVED AFTER 32 MONTHS OF OPERATION
TERMOUTILIZZATORE HIGH DUST SCR INSPECTION OCTOBER 2009
TERMOUTILIZZATORE HIGH DUST SCR CATALYST REMOVED AFTER 32 MONTHS OF OPERATION
TERMOUTILIZZATORE HIGH DUST SCR CATALYST REMOVED AFTER 32 MONTHS OF OPERATION
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
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)