Polk Power Key Lessons for IGCC Gasification Technologies Conference October 15, 2015

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1 Polk Power Key Lessons for IGCC Gasification Technologies Conference October 15, 2015 Mark Hornick Tampa Electric Company

2 Tampa Electric Company Investor owned - NYSE Regulated rates FL PSC $2.4b Revenue (Electric & Gas) 700,000 Customers (Electric) 4,800 MW Capacity 60% natural gas 40% coal/pet coke Partnership Bayside Big Bend Polk Phillips

3 Polk 1 IGCC Overview (1) In service date September 1996 DOE Clean Coal Technology co-funding $120M of $600M Gasification technology originally developed by Texaco, now General Electric Oxygen blown, slurry fed, entrained flow gasifier Operating pressure 400 psi nominal Gasifier vessel refractory lined (1,800 cuft) Radiant plus convective syngas coolers for heat recovery (no quench) Single train configuration (one gasifier supplying one CT) 320 MW Gross output, 250 MW net

4 Polk 1 IGCC Overview (2) CT fuel syngas primary, natural gas startup/co-fire/full load CT is GE 7F w/ MNQC combustors, larger 1st stage nozzle Diluent N2 plus syngas saturation for NO x control (no SCR) Modest air extraction rate from CT to ASU (currently out of service) Feedstock is 2200 tons/day coal and petroleum coke blend (20/80) ASU by Air Products, 2100 tons/day oxygen production Acid gas removal via MDEA and COS hydrolysis Sulfuric acid plant by Monsanto

5 Polk 1 IGCC Process Flow Air Feedwater Steam to power block Air Separation Oxygen Coal GE Gasifier (400 psig) Syngas Cooling Scrubbers COS Hydrolysis Syngas Cooling MDEA Sulfuric Acid Plant Acid Gas Sulfuric Acid Slag Char Syngas Diluent (N 2 ) Process Condensate Reheat/ Humid Clean Fuel Gas Extraction Air ~ ~ 128 Mwe (122 Mwe) Natural Gas Startup/co-fire/alternate fuel

6 Aerial View of Polk Power Station

7 IGCC drivers vs other gasification Electric power production has unique requirements and constraints Generation = Demand (instantaneous basis) No practical storage of product Ultra-high reliability for end user % Electric system reliability met by having multiple generating units Florida requires reserve capacity 20% greater than peak hour Minimum demand hour is 1/3 of peak demand hour Overall generating fleet utilization factor (capacity factor) is around 50% Implications for IGCC units: Natural gas fuel backup for syngas at the CT provides high electric power reliability Gasification area not designed for high reliability (no spare gasifier, slurry feed pump, ASU, etc.) Economic justification for high reliability design is based on differential feedstock costs (coal versus gas) not on loss of product revenue

8 IGCC lessons Equipment maintenance intervals and implications (1) IGCC maintenance intervals are dictated by CT parts life GE 7F on syngas requires maintenance at 8,000 hour intervals Major maintenance required at 24,000 hour intervals (3 years) Critical success factor to align gasifier refractory maintenance with CT major maintenance intervals (30 day planned outage every 3 years) Refractory life is typically < 3yrs in other gasification applications Careful management of refractory life is needed: 1. Operating temperature (O to C) versus ash fusion temperature 2. Wear rate monitoring by direct measurement (off-line) and indirect measurement (chromium content of slag) Polk experience shows that refractory life can be managed to 3+ years however carbon conversion is negatively impacted (lower O to C ratio)

9 IGCC lessons Equipment maintenance intervals and implications (2) Carbon conversion < 90% creates an obvious efficiency loss and high carbon content of slag makes it unsuitable for beneficial re-use Polk experience shows that high carbon material in slag is present in smaller size fraction Slag handling system was modified (in several iterations) to include wet vibratory screening of slag and recycle of fines fraction back to slurry feed With this modification, carbon conversion is effectively 100% Result: Refractory life is reliably managed to coincide with CT maintenance intervals Plant efficiency losses through unconverted carbon are eliminated and slag is sold for beneficial re-use

10 IGCC lessons Equipment maintenance intervals and implications (3)

11 IGCC lessons Equipment maintenance intervals and implications (4)

12 IGCC lessons CT natural gas co-firing and heat exchanger fouling (1) Polk 1 IGCC has a unique configuration with syngas cooling and heat recovery Primary syngas cooling uses a large radiant syngas cooler (no quench). Syngas temps reduced from 2,400 F to 1,200 F Secondary syngas cooling is done in two, 50% capacity convective syngas coolers. Syngas temps reduced from 1,200 F to 750 F. Convective syngas coolers have experienced fouling since initial operation. Multiple modifications over many years only improved run time between cleanings to approximately 45 days. Fouling mechanism complex. Contributing factors: Feedstock constituents sodium, vanadium, Temperature rapid fouling > 1,250 F Geometry of inlet multiple iterations of aerodynamic ferrules Velocity related to production rate and temperature

13 IGCC lessons CT natural gas co-firing and heat exchanger fouling (2) Convective syngas cooler tube sheet with inlet ferrules fouling conditions

14 IGCC lessons CT natural gas cofiring and heat exchanger fouling (3)

15 IGCC lessons CT natural gas cofiring and heat exchanger fouling (4) In 2012 TEC changed the startup/backup fuel system on the CT from distillate oil to natural gas. Control modifications were also made to allow co-firing of syngas and natural gas. Co-firing allows operation at full electric power production with reduced syngas production rates. Testing has shown that reducing the syngas production rate by approx 10% dramatically reduces the rate of CSC fouling. (100+ days operation with no significant fouling) Operating at reduced rates actually provides more annual MWhrs from syngas fuel due to reduced downtime for CSC cleaning. Co-firing CT is dispatched as a separate unit with its own economic profile. Unique solution for IGCC with electric power as final product

16 Conclusions Gasification for electricity has unique drivers/challenges Electric power production is quite different from other manufacturing or process industries (no product storage and wide variations in demand from hour to hour) Dual fuel combustion turbine (syngas & natural gas) provides high reliability of power production with lesser syngas reliability The integrated nature of gasification with power block require alignment of maintenance needs/intervals (3 year major outages) High level of process interrelationships means that solving one problem may create another in a different area of plant (refractory life management creates need for fine slag recycle) High level of integration also creates the possibility of solving a problem in one area by changing operations in another (co-firing natural gas in CT mitigates fouling issue in syngas coolers)

17 Polk Power Key Lessons for IGCC Gasification Technologies Conference October 15, 2015 Mark Hornick Tampa Electric Company