Ansaldo Caldaie Coal Biomass Co-firing Testing Experience. Author: Giovanni Mainini Co-authors: G. Guelfi M. Penati R. Piasente L. Rusconi A.

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1 Author: Giovanni Mainini Co-authors: G. Guelfi M. Penati R. Piasente L. Rusconi A. Saponaro

2 General Overview The drive for reduction of CO 2 emissions pushes both power generation sector and boiler manufacturers towards the use of renewable energy sources Ansaldo Caldaie, a global supplier of Utility Boilers and Heat Recovery Steam Generators, in cooperation with Tirreno Power, one of the primary Italian Power Generation companies, has developed an experimental and engineering activity for the co-firing of biomasses with coal This presentation highlights the recent experimental activities for the direct co-firing of pulverised coal with pulverised Wood Pellets (WP) and other potential biomass fuels in TEA-C / TEA-C EFS Low-NOx Burner the basic design features of major biomass feeding components required for the implementation of the co-firing technology in a large scale boiler

3 Objectives of the testing activity To verify the firing performance in nominal co-firing conditions (20-30% heat input) and with increased amounts of bio-fuel up to full biomass firing To investigate on the role played by pulverised fuel fineness (for both coal and biomass) validation of commercially achievable levels To investigate and validate the biomass dosing and transport technologies within a wide range of air / biomass ratios (dense vs. semi-dense options) Dense option: < 0.25 kg air / kg biomass Semi-dense option: kg air / kg biomass optimised engineering from the cost-benefit point of view

4 Basic design criteria Direct injection of pulverised biomasses into the main pulverised coal piping upstream the coal burner no dedicated burners, no impact on coal grinding Separate biomass handling and pulverisation Pneumatic transport of pulverised biomasses small pipes, segregated environment Dense or semi-dense transport solutions minimum impact on plant lay-out and on burner fluid-dynamics

5 The firing equipment Standard design of AC Low-NOx burner (TEA-C) Optimised axial staging effect for the clean combustion of medium-high CV coals typically available on the international market Special design of AC Low-NOx burner (TEA-C EFS) Enhanced Flame Stability nozzle, optimised for the clean combustion of low CV, high ash, high moisture coals typically fired in India

6 The test facility Located in the Ansaldo Caldaie owned Combustion & Environmental Research Centre (CCA) Designed to operate in full scale a boiler burner up to 40 MWth fuel heat input, with gaseous, liquid and solid fuels Equipped to manage 2 different solid fuel streams in parallel: A coal stream (silo, feeder, ball mill + RC, primary air system to burner) A biomass stream (pulverised fuel silo, dosing system, pneumatic transport system to burner)

7 The Fuels

8 Wood Pellets Co-firing test results (TEA-C existing Burner, 35 MWth) Appreciable NOx reduction with increasing amounts of biomass co-firing Moderate increase of operating excess air Minor increase in UBC NOx, 6% O2 dry (mg/nmc) 800 STD Nox-100% coal 750 STD CO-100% coal 700 STD Nox-90%coal+10%bio 650 STD CO-90%coal+10%bio 600 STD Nox 85% coal+15%bio 550 STD CO 85%coal+15%bio 500 STD Nox 80%coal+20%bio 450 STD CO 80%coal+20%bio ,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00 5,50 6,00 6,50 7,00 O2 DRY (%) NOx CO % bio 600 O2 24 UBC NOx, CO % BIO, O2, UBC

9 Wood Pellets Co-firing test results (TEA-C EFS Burner, 35 MWth) NOx, 6% O2 (mg/nmc) Nox-100% carbone CO-100% carbone Nox-80%carbone+20%WP CO-80%carbone+20%WP Nox-75%carbone+25%WP CO-75%carbone+25%WP Nox-70%carbone+30%WP CO-70%carbone+30%WP 200 Use of enhanced flame stability nozzle ,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 7,0 O2 dry (%) Similar NOx reduction with increasing biomass heat input Better CO control Satisfactory operating excess air

10 Palm Kernel Shells Co-firing test results (TEA-C EFS Burner, 35 MWth) NOx, 6% O2 (mg/nmc) Nox-100% carbone CO-100% carbone Nox-80%carbone+20%PKS CO-80%carbone+20%PKS Nox-75%carbone+25%PKS CO-75%carbone+25%PKS ,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 7,0 O2 dry (%) Nitrogen content in bio-fuel determines a NOx increase trend CO is very well controlled Significantly lower operating excess air can be achieved

11 Wood Pellets full firing test results (TEA-C EFS Burner, 35 MWth) Warm-up with Natural Gas, load ramp with increasing amounts of bio-fuel, no flame support above 70 80% MCR Very low NOx emission (approx. 150 mg/nm 6% O 2 dry), with good CO control and typical operating O 2 (approx 4% vol) UBC values corresponding to about 0.3% Unburnt Efficiency Loss

12 Co-firing test results - Conclusions Burner co-firing capacities up to 20 30% heat input have been confirmed, according to initial targets Properly shaped and stable flames have been achieved in a wide range of operating conditions Good combustion parameters (excess air, NOx, CO) have been verified Significant benefits have been achieved by using EFS coal nozzle, also verifying the capability to accept full biomass firing on individual burners of a coal-biomass co-fired boiler

13 The reference basic design for the pulverised biomass handling Various arrangements have been evaluated, among direct / indirect systems and different bio-fuel grinding alternatives (direct grinding in coal mills, separate pulverisation with various transport options) Safety issues and capital costs have been also taken into account - Air biomass ratio TRANSPORT SYSTEM DENSE OPTION SEMI-DENSE OPTION CASE A CASE B ~ 0.25 : 1 ~ 1 : 1 ~ 0.5 : 1 - Transport flexibility with different type of biomass High Medium (moderate density variations) - Dedicated line for each burner Yes Yes - Transport air supply Compressors One blower for each line to burner Flow 4 x 3000 Nm3/h 24 x 2000 Nm3/h 24 x 900 Nm3/h Pressure (design / operating) 4 / 2.5 bar 0.6 / 0.4 bar 0.6 / 0.5 bar - Power consumption High High Medium-Low Small silos Small silos Loading valves Screw feeders Loading valves - Transport system components (4 cycles/hour) Continuous feed (2 cycles/hour) Barrels (sealing) Small hopper with load cells with load cells Rotary valves Rotary valves (sealing) - Transport line diameter 3 4" 5 6" 4" - Dosing system Gravimetric Volumetric Gravimetric for each line for each group of lines (2% accuracy) (~ 5% accur.) (~ 5% accur.)

14 AC guidelines for the reference design Direct injection of pulverised biomass into the p.c. piping upstream the burners Direct feeding system, with pneumatic transport Semi-dense phase with air blowers, small dosing bin with screw feeders and properly selected rotary valves Use of Class A biomass according to CEN/TS and EU Bionorm, with the following characteristics LHV > 3400 kcal/kg Moisture < 20% wt, a.r. basis Pulv. Fuel fineness 100% < 1.5 mm Basic engineering study, developed in cooperation with Tirreno Power, for the potential retrofit of 320 MWe class coal fired units (applicable to TP Vado Ligure Power Plant and ready for the detailed engineering & supply phases of the project)

15 AC guidelines for the reference design Lay-out study and process flow diagram of a biomass co-firing fuel supply system

16 AC guidelines for the reference design Burner logic groups equipped for coal-biomass co-firing (Vado Ligure # 3)

17 General Conclusions Ansaldo Caldaie product development for coal biomass co-firing has achieved significant results Full scale testing at Ansaldo Caldaie Combustion Centre demonstrated the satisfactory performance of Ansaldo Caldaie TEA-C Low-NOx burner, equipped with enhanced coal nozzle (EFS), in a 20 30% co-firing configuration of bituminous coal and biomass Good and stable combustion parameters, proper emission levels, wide operating load range and performance flexibility for various biomass types and for different kinds of biomass transport configurations (dense or semi-dense solutions) have been confirmed The capability of TEA-C EFS burner design to accept full biomass firing on individual burner has been verified positively A pre-engineered reference design suitable to the retrofit of large utility boilers has been developed and is ready to be implemented From the experience, Ansaldo Caldaie is ready for the development of a wide range of cofiring projects, to satisfy state of the art industry needs