Thermo-Economic Analysis of Four sco Waste Heat Recovery Power Systems Steven A. Wright swright@supercriticaltech.com Chal S. Davidson cdavidson@supercriticaltech.com William O. Scammell bscammell@supercriticaltechnologies.com V0150515
Introduction Goal: Provide A System Performance and Economic Analysis of Four Waste Heat Recovery sco power system Four WHR sco power systems: Simple Recuperated Brayton Cycle (SRBC) Cascaded Cycle : Patented & WHR Dual Recuperated Cycle: Patented & WHR Preheating Cycle: Public & WHR Assumptions Gas Turbine, M500 extending EPRI Study by imzey sco Bottoming Cycle Power Systems Economic, Component Costs and Operating Conditions Comparison of System Performance Focus: on Maximizing Annual Revenue = Electric Power Produced Answers these questions: Does It make economic sense to use HX s of High Effectiveness? How do the publically available cycles compare to the commercially patented cycles? Economic Summary (System Costs, Annual Revenue, LCOE, Rates of Return) Conclusions All WHR have Higher Revenue, Lower LCOE, Produce Substantially Greater Elect Power But at greater cost As a group the WHR Perform Similarly in terms of Electrical Power and Economics Recuperators with High Effectiveness are Generally Favored
Gas Turbine Assumptions Primary Gas Turbine LM-500PE Mass Flow Rate Gas Turbine 68.8 Temp of Gas Turbine Exhaust 8.1 Efficiency (at Gen Terminals at 15 C ambient) 35.5% Thermal Combustion Power (@ 10146 / BTU/hr) 63,131 th Thermal Exhaust (Waste Heat) Power (@ 15 C) 40,731 th LM500PE Gas Turbine 8.1 (538 C) 68.8 Turbine SRBC Compressor 40.7 MW th Recuperator
sco Assumptions sco Power Cycle Assumptions Value Turbine Isentropic Efficiency 85% Compressor Isentropic Efficiency 8% Losses Shaft to Electrical (Bearings, Gears, Generator, etc.) 7% Water Inlet Temp 9. = 19 C Compressor Inlet Pressure 7700 Compressor Inlet Temp 305.4 Compressor Pressure Ratio 3.1 Operating Conditions Varied to Optimize Net Annual Revenue Variables were: Turbine Inlet T + All Heat Exchanger - Approach Temperatures, Split Flow Fraction and Compressor Mass Flow Rate P.ratio=3.1 305.4, 7700 eff.s=8% eff.s=85% 9. = 19 C
Performance Optimization Optimization Parameters Mass Flow Rate Turbine Inlet Temp dt approach Recuperator Cold side dt approach Recuperator Hot side dt approach Prim HX Split Flow (if used) TIT mሶ eff.s=8% dt dt dt + Flow Split
Four sco Power Cycles Simple Recuperated Brayton Cycle Cascaded Cycle Dual Dual Recuperated Recuperated sco WHR Power Cycle Cycle Thermal Cycle Efficiency= 8.17% Net Cycle Efficiency= 6.% Net Power 83 e Total Efficiency= 0.53% 64.49 5 Turbine H Comp 68.8 Turbine R 743.5 793.4 305.4 4353 1 0 338 8948 811. 3760 e 7700 Pratio 3.1 Primary 6D 6H HX / Heater 63.5 479.5 343.6 7855 7855 4000 WHR Eff 31759 586.5 78.36% 5D=3D HT Recuperator 48.8 0.00 3760 19190.9 7=8 Stack 366.6 48.8 64.49 8 387.9 8d Gas Cooler 811 11.77 3760 366.6 8h Flow Split = 57. 479.5 LT "D" Recup 343.6 7855 6496 4000 409.0 4=3h 366.6 8 7777 387.9 3760 343.6 64.49 4000 CG1 68.8 811. WHR Eff 8.1% Stack 390.0 68.8 Preheating Cycle Thermal Cycle Efficiency = 7.80% 5 1006 66.6 3760 Primary HX / Simple Recuperated Brayton Cycle with Preheating for WHR 11.4 550.5 7855 6 Net Cycle Efficiency = Turbine 183 Comp eff= 4017 Flow Split = 68.5% 11.44 HT Recup 3 CG 56.7 66 343.6 83.15 545. 3760 4 7 363.3 363.3 8 8a 11.4 183.1 dt= Effectiveness 90.5% 159 343.6 4000 CG3 343.6 38.9 390.0 4000 5.9% 948 e Pwr Pratio 3.1 Net Pwr = 8601 rpm 3584 343.6 4000 1 e 305.4 7700 Gas Effectivene All WHR sco Cycles Use Split Flow
Temperature () Simple Recuperated Brayton Cycle glide curve eff mech-elec 870 770 Split Flow with Preheating Power Cycle for sco WHR Systems T-S Sat Liq eff WHR 670 570 Sat Vap Heat Source Net Efficiency 8.3% eff CO-mech 470 WHR Efficiency 61.% 370 70 1 1.5.5 3 Entropy (j/kg-) Net Efficiency is eff NET = eff WHR * eff co-mech * eff mech-elec (93%) CG Exit Temp is Limited by Recup High Pressure Exit Temp: This is high (see glide curve) This lowers Waste Heat Recovery Efficiency eff WHR =(Q CO /Q WH ) = 61.% Power Optimization Increases eff CO = 30.4%
Cascade Cycle glide curve CG Exit Temp is now limited by Compressor Exit Temp: This is low (see glide curve) This Increases Waste Heat Recovery Efficiency eff WHR =(Q CO /Q WH ) 85.6% Power Optimization with Turbines and Recup Increases eff CO = 6.5%
Duel Recuperated Cycle Dual Recuperated sco WHR Power Cycle glide curve Thermal Cycle Efficiency= 8.17% Net Cycle Efficiency= 6.% Net Power 83 e Total Efficiency= 0.53% 64.49 68.8 5 Turbine R Turbine H Comp 811. 743.5 3760 4353 793.4 0 8948 e 338 1 305.4 7700 Primary HX / Heater Pratio 3.1 6D 6H 479.5 63.5 343.6 7855 7855 4000 Gas Cooler 811 WHR Eff 78.36% Stack 31759 387.9 48.8 586.5 3760 64.49 5D=3D HT Recuperator 48.8 19190.9 366.6 7=8 0.00 8 8d 11.77 409.0 3760 479.5 7855 4=3h 387.9 3760 64.49 LT "D" Recup 6496 343.6 4000 366.6 8 Flow Split = 57. 343.6 4000 366.6 8h CG Exit Temp is now limited by LT Recup Exit Temp This is intermediate (see glide curve) This Increases Waste Heat Recovery Efficiency eff WHR =(Q CO /Q WH ) 78.4% Power Optimization with Turbines and Recup Increases eff CO = 8.%
sco Preheating Cycle glide curve Simple Recuperated Brayton Cycle with Preheating for WHR Thermal Cycle Efficiency = 7.80% Net Cycle Efficiency = 5.9% Net Pwr = 8601 e CG1 WHR Eff 8.1% Stack 390.0 68.8 68.8 811. 5 1006 66.6 3760 Primary HX / 11.4 550.5 7855 6 Turbine 183 Flow Split = 68.5% 11.44 HT Recup 3 CG 56.7 66 343.6 83.15 545. 3760 4 7 363.3 363.3 8 8a 11.4 183.1 dt= Effectiveness 90.5% 159 343.6 4000 CG3 343.6 38.9 390.0 4000 948 e Pratio 3.1 Pwr rpm 343.6 4000 Comp 3584 eff= 1 305.4 7700 Gas 4017 Effectivene CG Exit Temp is now limited by Compressor Exit Temp This is low (see glide curve) This Increases Waste Heat Recovery Efficiency eff WHR =(Q CO /Q WH ) 8.1% Thermal Cycle Efficiency: eff CO = 7.8%
Four sco Power Cycles WHR Eff 78.36% Stack 68.8 811. 409.0 31759 5 743.5 3760 Primary HX / Heater 387.9 3760 6D Turbine H 4000 366.6 8 8948 7=8 Comp 479.5 63.5 343.6 7855 7855 4000 479.5 7855 4=3h 387.9 3760 64.49 64.49 Turbine R 48.8 4353 586.5 3760 6496 6H 793.4 64.49 LT "D" Recup 5D=3D 6.% Total Efficiency= 0.53% 0 343.6 19190.9 e HT Recuperator Pratio 3.1 Flow Split = 366.6 7777 48.8 57. 343.6 4000 338 1 0.00 8 305.4 7700 366.6 7777 8d 811 Gas Cooler 11.77 8h Simple Recuperated Brayton Cycle Cascaded Cycle 1Turbine 1 Compressor 1 Recuperator 1 CO Chiller 1 Prim Hx 5 Components : No Split Flow Dual Recuperated Cycle Turbines 1 Compressor Recuperators 1 CO Chiller 1 Prim Hx 7 Components + Split Flow Preheating Cycle Dual Recuperated sco WHR Power Cycle Thermal Cycle Efficiency= 8.17% Net Cycle Efficiency= Net Power 83 e Turbines 1 Compressor Recuperators 1 CO Chiller 1 Prim Hx 7 Components + Split Flow CG1 WHR Eff 8.1% Stack 390.0 68.8 Thermal Cycle Efficiency = 7.80% 68.8 811. CG 545. 390.0 1006 66.6 3760 Primary HX / 159 5 56.7 3760 Simple Recuperated Brayton Cycle with Preheating for WHR 550.5 7855 Turbine 948 eff= 4017 Flow Split = 68.5% 11.44 HT Recup 3 66 343.6 83.15 4 7 363.3 363.3 8 8a 11.4 183.1 dt= Effectiveness 90.5% 343.6 343.6 4000 11.4 6 Net Cycle Efficiency = 1 Turbines 1 Compressor 1 Recuperators 1 CO Chiller Prim Hx 6 Components + Split Flow CG3 183 5.9% 38.9 e Pratio 3.1 Net Pwr = Pwr rpm 343.6 4000 8601 Comp 3584 4000 1 e 305.4 7700 Gas Effectivene
Economic Assumptions Economic Assumptions Value Plant Lifetime 0 yr Plant Utilization Factor 85% Discount Rate 5% Sale Price of Electricity $0.06/h e Thermal Exhaust (Waste Heat) Power (@ 15 C) 40,731 th + Component Specific Costs
Component Costs Dual Recuperated sco WHR Power Cycle Thermal Cycle Efficiency= 8.17% Net Cycle Efficiency= 6.% Net Power 83 e Total Efficiency= 0.53% 64.49 68.8 5 Turbine R Turbine H Comp Turbo Machinery + Aux Cost = SpecCost Turb+Aux * Pwr e 811. 743.5 3760 4353 793.4 0 8948 e 338 1 305.4 7700 Primary HX / Heater Pratio 3.1 6D 6H 479.5 63.5 343.6 7855 7855 4000 Gas Cooler 811 WHR Eff 78.36% Stack 31759 387.9 48.8 586.5 3760 64.49 5D=3D HT Recuperator 48.8 19190.9 366.6 7=8 0.00 8 8d 11.77 3760 366.6 8h 479.5 LT "D" Recup Flow Split = 57. 343.6 7855 6496 4000 409.0 4=3h 366.6 8 7777 387.9 3760 343.6 64.49 4000 Primary Heater Recuperators CO Chillers Q=U * A * LMDT Cost =SpecificCost HX * Q/LMDT = U * A
Component Specific Costs Dual Recuperated sco WHR Power Cycle Thermal Cycle Efficiency= 8.17% Net Cycle Efficiency= 6.% Net Power 83 e Total Efficiency= 0.53% 64.49 5 Turbine H Turbine R Comp 68.8 $1000/e 811. $5000/(/) WHR Eff 78.36% Stack 743.5 305.4 4353 793.4 1 0 338 8948 3760 e 7700 Pratio 3.1 Primary 6D 6H Gas HX Cooler / Heater 479.5 63.5 343.6 7855 7855 4000 811 31759 586.5 5D=3D HT Recuperator 48.8 0.00 3760 19190.9 7=8 11.77 366.6 48.8 64.49 8 387.9 8d $1700/(/) 409.0 3760 Flow Split = 57. 479.5 LT "D" Recup 343.6 7855 6496 4000 4=3h 366.6 8 7777 387.9 3760 343.6 64.49 $500/(/) 4000 366.6 8h Component Description Cost Units Component Specific Costs Recuperators (cost/ua) $/(.th/) 500 Fin Tube Primary Heater (cost/ua) $/(.th/) 5000 Tube and Shell CO-Chiller (cost/ua) $/(.th/) 1700 Turbomachinery+Gen+Mtr+Gear+Piping+Skid+I&C+Aux.BOP $/e 1000
Summary of Results SRBC Cascaded Dual Recup Preheating LM-500PE Units Waste Heat (Brochure) LM500.th 40,731 40,731 40,731 40,731 Waste Heat Combustion Model.th 40530 40530 40530 40530 Mass flow rate thru Comp 93. 14.6 11.8 11.4 Max flow rate in Heater 93.18 56 64.49 11.4 Efficiency of WHR 61.% 85.6% 78.4% 8.1% Net SCO Cycle Efficiency 8.3% 4.7% 6.% 5.9% Total Efficiency 17.31% 1.13% 0.53% 1.% Max Turbine Inlet T 685.0 756.9 743.5 66.6 Max Turbine Inlet T ( C ) C 411.8 483.8 470.3 389.5 Stack Exit Temp () 497.1 37 409.0 390.0 Stack Exit Temp ( C ) C 3.9 99 135.9 116.8 WHR are Grouped Together Max TIT Higher for Pat. Cycles Total UA / 1795 807.98 447 966 Recup UA / 630.5 1036.96 78.8 16.76 Heater UA / 446.6 837.58 794.1 740.71 Chiller UA / 718. 933.45 870.4 998.97 Recup Costs $ 1,576,314,59,403 1,957,006 3,066,890 Heater Costs $,3,836 4,187,885 3,970,675 3,703,565 Chiller Costs $ 1,1,01 1,586,858 1,479,69 1,698,46 Total HX Costs 5,030,171 8,367,146 7,407,310 8,468,70 HEAT EXCHANGER EFFECTIVENESS Prim HT HX % 94.6% 94.0% 95.0% 93.5% Preheater HX % 90.8% HT Recup % 94.0% 9.3% 83.1% 90.5% LT Recup % 88.4% 91.8% - CO Chiller % 73.8% 8.3% 81.8% 81.% Closest Approach Temperature () () 10.7 18.0 1.1 18.0 CC Heat Rate (GT only=9611 BTU/h) BTU/h 733 7037 701 6949 Effective Revenue from Elect Sales $M/year.168.339.456.473 Approx $/e Net $/e 1717 019 1890 1985 Net Elect. Power e 7017 814 83 8601 Combined Cycle Total Efficiency % 46.6% 48.5% 48.7% 49.1% Total Capital Costs (FOA) M$ 1.047 16.581 15.79 17.070 Rate of Return % 18.0% 14.1% 15.6% 14.5% High Effectiveness for HXs Approach Temps 10 C 1 C CC Heat Rate Near 7000 BTU/h See Bar Charts (Next)
Capital Cost k$/e Total Efficiency Net Power (e) Net Revenue (M$/yr) ~1 MWe Additonal Power 300 k$/we Additional Capital Costs CapX ~ $/We A C Economic Performance Summary Chart for sco Bottoming Cycle 1000 900 800 700 600 500 400 300 00 100 50 00 150 100 Net Electric Power (SRBC versus WHR-Cycles) SRBC Cascaded Dual Recup Preheating Capital Costs ($/We) B D.500.450.400.350.300.50.00.150.100.050.000 5.00% 0.00% 15.00% 10.00% Net Annual Revenue (M$/year) SRBC Cascaded Dual Recup Preheating Total Efficiency Versus sco Cycle Type 300 k$/yr Additional Revenue 3% points Additional Net Efficiency for sco Bottom Cycle 50 5.00% SRBC Cascaded Dual Recup Preheating 0.00% SRBC Cascaded Dual Recup Preheating
Combiined Cycle Efficiency Combined Cycle Economic Comparisons SRBC Cascaded Dual Recup Preheating Gas Turbine Only LCOE at Fuel Costs of 3$/MMBTU $0.094 $0.091 $0.089 $0.089 $0.034 LCOE at Fuel 5$/MMBTU $0.0416 $0.0409 $0.0406 $0.0405 $0.050 A B 49.5% 49.0% 48.5% 48.0% 47.5% 47.0% 46.5% 46.0% 45.5% 45.0% Combined Cycle Efficiency SRBC Cascaded Dual Recup Preheating $0.0600 $0.0500 $0.0400 $0.0300 $0.000 $0.0100 $0.0000 LCOE for the Combined Cycle and Gas Turbine LCOE at Fuel Costs of 3$/MMBTU LCOE at Fuel 5$/MMBTU CC Eff 35.5% to 46-49% Combined Cycle Capital Costs ($0.750/We for Gas Turbine and $/We for sco) = $1.05/We Combined Cycle Efficiency Increases from 35.5% to 46-49%) LCOE Decreases from $0.05/h to $.04/h (Well below Grid Price of Elect) (5$/MM BTU of Nat Gas)
Conclusions Conclusions for Combined Cycle Combined Cycle Efficiency Increases from 35.5% to 46-49% With LCOE reduction of 1cent/h at $5/MMBTU Natural Gas LCOE is well below market price of electricity in most markets Reduction of Heat Rating from 9611 BTU/h to ~7000 BTU/h Conclusions for sco WHR Power Systems All WHR systems perform about the same (both power and economics) All WHR cycles produce 1.-1.6 MWe more compared to SRBC Annual Revenue for WHR sco increases $00-300 k/yr (1-15% above SRBC) Capital costs increase from 1 M$ to 16-17 M$ (from 1.7 to ~ $/We) HXs represent about 40-50% of total system cost Economic benefit to increasing HX Effectiveness to 93-95% range WHR Efficiency is 61% for SRBC and 75-85% for WHR systems sco WHR Performance and Economic Benefits are Substantial ey: A Business Model that Meets Customer s Needs Expanding Markets, New Markets, Modularity, Power Independence, Grid Independence, Grid Reliability, High Reliability, More Competitive Products