Thermo-Economic Analysis of Four sco2 Waste Heat Recovery Power Systems

Transcription

1 Thermo-Economic Analysis of Four sco Waste Heat Recovery Power Systems Steven A. Wright Chal S. Davidson William O. Scammell V

2 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

3 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 (@ / 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

4 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 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= , 7700 eff.s=8% eff.s=85% 9. = 19 C

5 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

6 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% Turbine H Comp 68.8 Turbine R e 7700 Pratio 3.1 Primary 6D 6H HX / Heater WHR Eff % 5D=3D HT Recuperator =8 Stack d Gas Cooler h Flow Split = LT "D" Recup =3h CG WHR Eff 8.1% Stack Preheating Cycle Thermal Cycle Efficiency = 7.80% Primary HX / Simple Recuperated Brayton Cycle with Preheating for WHR Net Cycle Efficiency = Turbine 183 Comp eff= 4017 Flow Split = 68.5% HT Recup 3 CG a dt= Effectiveness 90.5% CG % 948 e Pwr Pratio 3.1 Net Pwr = 8601 rpm e Gas Effectivene All WHR sco Cycles Use Split Flow

7 Temperature () Simple Recuperated Brayton Cycle glide curve eff mech-elec Split Flow with Preheating Power Cycle for sco WHR Systems T-S Sat Liq eff WHR Sat Vap Heat Source Net Efficiency 8.3% eff CO-mech 470 WHR Efficiency 61.% 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%

8 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%

9 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% Turbine R Turbine H Comp e Primary HX / Heater Pratio 3.1 6D 6H Gas Cooler 811 WHR Eff 78.36% Stack D=3D HT Recuperator = d =3h LT "D" Recup Flow Split = h 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.%

10 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 Primary HX / Turbine 183 Flow Split = 68.5% HT Recup 3 CG a dt= Effectiveness 90.5% CG e Pratio 3.1 Pwr rpm Comp 3584 eff= 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%

11 Four sco Power Cycles WHR Eff 78.36% Stack Primary HX / Heater D Turbine H =8 Comp =3h Turbine R H LT "D" Recup 5D=3D 6.% Total Efficiency= 0.53% e HT Recuperator Pratio 3.1 Flow Split = d 811 Gas Cooler h 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 Thermal Cycle Efficiency = 7.80% CG Primary HX / Simple Recuperated Brayton Cycle with Preheating for WHR Turbine 948 eff= 4017 Flow Split = 68.5% HT Recup a dt= Effectiveness 90.5% Net Cycle Efficiency = 1 Turbines 1 Compressor 1 Recuperators 1 CO Chiller Prim Hx 6 Components + Split Flow CG % 38.9 e Pratio 3.1 Net Pwr = Pwr rpm Comp e Gas Effectivene

12 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

13 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% Turbine R Turbine H Comp Turbo Machinery + Aux Cost = SpecCost Turb+Aux * Pwr e e Primary HX / Heater Pratio 3.1 6D 6H Gas Cooler 811 WHR Eff 78.36% Stack D=3D HT Recuperator = d h LT "D" Recup Flow Split = =3h Primary Heater Recuperators CO Chillers Q=U * A * LMDT Cost =SpecificCost HX * Q/LMDT = U * A

14 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% Turbine H Turbine R Comp 68.8 $1000/e 811. $5000/(/) WHR Eff 78.36% Stack e 7700 Pratio 3.1 Primary 6D 6H Gas HX Cooler / Heater D=3D HT Recuperator = d $1700/(/) Flow Split = LT "D" Recup =3h $500/(/) h 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

15 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 Mass flow rate thru Comp Max flow rate in Heater 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 Max Turbine Inlet T ( C ) C Stack Exit Temp () Stack Exit Temp ( C ) C WHR are Grouped Together Max TIT Higher for Pat. Cycles Total UA / Recup UA / Heater UA / Chiller UA / 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 () () CC Heat Rate (GT only=9611 BTU/h) BTU/h Effective Revenue from Elect Sales $M/year Approx $/e Net $/e Net Elect. Power e Combined Cycle Total Efficiency % 46.6% 48.5% 48.7% 49.1% Total Capital Costs (FOA) M$ 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)

16 Capital Cost k$/e Total Efficiency Net Power (e) Net Revenue (M$/yr) ~1 MWe Additonal Power 300 k$/we Additional Capital Costs CapX ~ $/We A C Economic Performance Summary Chart for sco Bottoming Cycle Net Electric Power (SRBC versus WHR-Cycles) SRBC Cascaded Dual Recup Preheating Capital Costs ($/We) B D % 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 % SRBC Cascaded Dual Recup Preheating 0.00% SRBC Cascaded Dual Recup Preheating

17 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 $ $ $ $ $0.050 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 $ $ $ $ $0.000 $ $ 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)

18 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 MWe more compared to SRBC Annual Revenue for WHR sco increases $ k/yr (1-15% above SRBC) Capital costs increase from 1 M$ to 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