Operation Results of a Closed Supercritical CO2 Simple Brayton Cycle

Transcription

1 Operation Results of a Closed Supercritical CO2 Simple Brayton Cycle JaeEun Cha*, Seong Won Bae*, Jekyoung Lee**, Song Kuk Cho**, JeongIk Lee**, Joo Hyun Park*** * Korea Atomic Energy Research Institute ** Korea Advanced Institute of Science and Technology *** Pohang University of Science and Technology

2 CONTENTS Introduction Overview of SCIEL Phase I Facility Phase II Facility Summary and further works

3 Introduction S-CO 2 Brayton Cycle Attractive features of S-CO 2 Brayton Cycle Small compression work due to characteristic like liquid near critical point and high thermal efficiency at moderate temperature ranges (450~750 ) Small specific volume throughout the whole system due to high pressure and enhanced economics due to compactness Compatibility with various heat sources (Nuclear, Concentrated Solar Power, Geothermal, Fuel cell and Waste heat recovery) Various research organizations are involved Research institutes : SNL, ANL, Bechtel/KAPL, KAERI, IAE-TIT, KIER, etc. University : MIT, KAIST, Univ. of Wisconsin Madison Industries : GE, Dresser-Rand, Barber-Nichols, Echogen, Toshiba, MAN, etc. Fig. Comparison various power cycle efficiencies Fig. Impeller sizes for 1MWth facility SNL(left) and KAERI(right) [Wright et al, 2010] 3 Fig. Comparing size of turbomachineries and heat exchangers [Dostal, 2004]

4 Introduction Research objectives Technological key issues on S-CO 2 Brayton Cycle Specific heat at constant pressure (J/kg-K) 18 x kpa 7500 kpa 7600 kpa 7700 kpa 7800 kpa 7900 kpa 8000 kpa 8100 kpa Temperature (K) Density (kg/m 3 ) kpa 7500 kpa 7600 kpa 7700 kpa 7800 kpa 7900 kpa 8000 kpa 8100 kpa Temperature (K) Ratio of Specific heats (C p /C v ) kpa 7500 kpa 7600 kpa 7700 kpa 7800 kpa 7900 kpa 8000 kpa 8100 kpa Temperature (K) Fig. Thermal efficiency sensitivity analysis on CIT and properties variation of S-CO 2 Operation in the vicinity of critical point for high thermal efficiency The reliable design difficulty of S-CO 2 compressor owing to its dramatic change of thermodynamic properties near critical point (304.13K, 7377kPa) Manufacture and operating experience of main components (turbomachineries, heat exchangers) Control logics development for Reactor and Power Conversion Unit (PCU) Goals of S-CO 2 Brayton Cycle Integral Experiment Loop (SCIEL) 300 kw of power generation Verification and accumulation of S-CO 2 turbomachine technology Verification of domestic PCHE technology Development of cycle control logics 4

5 Overview of SCIEL Research Organization for SCIEL Construction SCIEL : Supercritical CO 2 Integral Experiment Loop KAIST (Cycle and turbomachinery design) KAERI (System integration and construction of experiment loop) POSTECH (Heat exchanger design) JINSOLTURBO (Detailed design and manufacture of turbomachine) 5

6 Overview of SCIEL Research Organization for SCIEL Construction SCIEL : Supercritical CO 2 Integral Experiment Loop KAIST (Cycle and turbomachinery design) Total to Total Efficiency (%) Turbomachinery Efficiency-Mdot Map On-design point rpm=3600 rpm=4500 rpm=5400 rpm=6300 rpm= Mass Flow Rate (kg/s) (m) Vane Shroud Shaft Diffuser (m) x 10-3 Fig. Turbomachine preliminary design KAERI (System integration and construction of experiment loop) Fig. S-CO 2 Brayton Cycle design POSTECH (Heat exchanger design) JINSOLTURBO (Detailed design and manufacture of turbomachine) 6

7 Overview of SCIEL Research Organization for SCIEL Construction SCIEL : Supercritical CO 2 Integral Experiment Loop KAIST (Cycle and turbomachinery design) Fig. CFD simulation of airfoil fin PCHE KAERI (System integration and construction of experiment loop) Fig. PCHE performance comparison with airfoil fin PCHE and zigzag channel PCHE POSTECH (Heat exchanger design) JINSOLTURBO (Detailed design and manufacture of turbomachine) 7

8 Overview of SCIEL Research Organization for SCIEL Construction SCIEL : Supercritical CO 2 Integral Experiment Loop KAIST (Cycle and turbomachinery design) Fig. Double-sided suction S-CO 2 compressor KAERI (System integration and construction of experiment loop) Fig. S-CO 2 turbine and generator POSTECH (Heat exchanger design) JINSOLTURBO (Detailed design and manufacture of turbomachine) 8

9 Overview of SCIEL Research Organization for SCIEL Construction SCIEL : Supercritical CO 2 Integral Experiment Loop KAIST (Cycle and turbomachinery design) KAERI (System integration and construction of experiment loop) Fig. System integration and SCIEL layout POSTECH (Heat exchanger design) JINSOLTURBO (Detailed design and manufacture of turbomachine) 9

10 Overview of SCIEL Phase development strategy Phase I : Compressor Performance Test Loop Phase II : Low Compression Ratio Power Generation Loop Phase III : Simple Recuperation Cycle Loop Fig. SCIEL final layout Completion of Installation Further works 10

11 Overview of SCIEL Accepted concepts Item Cycle concept Compressor Turbine Concepts Double compression double expansion simple recuperated S- CO 2 Brayton cycle Cycle pressure ratio : 2.6 Top temperature : 500 o C LPC (Manufactured by JINSOL TURBO) Shrouded Compressor Double-sided Suction No thrust collar Flow rate : 6.4 kg/s Pressure Ratio : 1.8 Turbine, Compressor Separate Shaft Rotation rate : 70,000 rpm Gas foil bearing HPC TBD with TAC configuration LPT (Manufactured by JINSOL TURBO) Shrouded Turbine Single-sided suction Flow rate : 5.1 kg/s Rotation rate : 80,000rpm Gas foil bearing HPT TBD with TAC configuration Heat Exchanger PCHE (Manufactured by Cohex) Heater Indirect heating by thermal oil (Manufactured by S.P. Boiler) 11

12 Phase I of SCIEL Compressor Performance Test Loop Fig. Schematic diagram of Compressor Test Loop The key point of S-CO 2 Brayton cycle loop experiment is performance test of compressor and precooler in near critical point because they have the largest uncertainty. Compressor Performance Test Loop includes compressor and pre-cooler as main components to be able to verify components performance. It consists of pre-cooler, compressor, control valve and filters. 12

13 Phase I of SCIEL Compressor Performance Test Loop Fig. Compressor Performance Test Loop The key point of S-CO 2 Brayton cycle loop experiment is performance test of compressor and precooler in near critical point because they have the largest uncertainty. Compressor Performance Test Loop includes compressor and pre-cooler as main components to be able to verify components performance. It consists of pre-cooler, compressor, control valve and filters. 13

14 Phase I of SCIEL Results of Compressor Performance Test Loop 70 Temperauter ( o C) Saturation dome , T1, 10bar, 35C , T2, 30bar, 35C , T3, 40bar, 35C , T4, 50bar, 35C , T5, 48bar, 50C , T2, 70bar, 35C , LT5, 76bar 37C , T1, 76bar, 36C , T2, 78bar 40C Entropy (J/kg-K) Fig. Various compressor performance test cases (left) and examples of compressor performance curve (right) Performance tests in various compressor inlet conditions were conducted. Compressor performance test was performed up to 35000rpm (74 bar, 31 ). Although the shaft speed was relatively low, the results showed tendencies like performance curves of conventional compressors. 14

15 Phase II of SCIEL Low Compression Ratio Power Generation Loop Upgraded components 15

16 Phase II of SCIEL Low Compression Ratio Power Generation Loop Pre-cooler : not visible (Hot S-CO 2 vs Cold water) IHX (Hot oil vs Cold S-CO 2 ) S-CO 2 Radial inflow LP turbine S-CO 2 Radial LP compressor 16

17 Phase II of SCIEL Results of Low Compression Ratio Power Generation Loop Temperature ( o C) Cycle process line Saturation dome Compressor 7.8 kw (78.5bar, 75 o C) 13,000RPM Turbine Heater 1.2 kw Pre-cooler (75.5bar, 32 o C) 24,500RPM Pressure(bar), Temperature( o C) Pressure and Temperature Comp inlet Pressure Comp outlet Pressure Turb inlet Pressure Turb outlet Pressure Comp inlet Temperature Comp outlet Temperature Turb inlet Temperature Turb outlet Temperature Entropy (J/kg-K) Time(s) Fig. T-s cycle diagram (left) and compressor-turbine temperature and pressure at inlet and outlet (right) Power generation test was performed with compressor inlet condition above criticalpoint,compressor shaft speed, rpm and mass flow rate 1.3 kg/s. At the beginning, turbine load of 15kW was set to prevent the turbine overspeed. The generation test proceeded with removing turbine load taps step by step. Consequently, the power generation, 1.2kW, was accomplished with a turbine shaft speed of 13000rpm. 17

18 Phase II of SCIEL Results of Low Compression Ratio Power Generation Loop Turbine RPM (krpm) Turbine rotation and Turbine power Turbine RPM Turbine power output Time(s) Turbine power out (kw) Pressure ratio, Mass flow rate(kg/s) Pressure ratio and Mass flow rate Compressor Pressure Ratio Turbine Pressure Ratio Mass flow rate Time(s) Fig. Power output and shaft speed of turbine (left) and mass flow rate of compressor-turbine (right) Power generation test was performed with compressor inlet condition above criticalpoint,compressor shaft speed, rpm and mass flow rate 1.3 kg/s. At the beginning, turbine load of 15kW was set to prevent the turbine overspeed. The generation test proceeded with removing turbine load taps step by step. Consequently, the power generation, 1.2kW, was accomplished with a turbine shaft speed of 13000rpm. 18

19 Summary and further works Main result summary KAERI has constructed a S-CO 2 Brayton Cycle Integral Experiment Loop (SCIEL) with kWe net power to develop base technologies for the S-CO 2 turbomachinery and compact heat ex-changer. Operation and control test have being conducted to develop an operation strategy in the S-CO 2 cycle. KAERI finished the installation of the 2 nd phase of SCIEL loop (the low compression ratio loop) succeeded in generating the electric power with supercritical CO 2. Further works The control logic development will be carried out from the operation of the 2 nd phase of SCIEL facility. Additional TAC (Turbo-Alternator-Compressor) will be installed to finish the facility construction. The demonstration of high pressure ratio operation with high temperature heat source will be followed afterwards. 19

20 Summary and further works SCIEL MARS Model and Transient analysis MARS (Multi-dimensional Analysis of Reactor Safety) code is being developed by KAERI for a multidimensional and multi-purpose realistic system analysis of reactor transients. The backbones of MARS are the RELAP5 and COBRA-TF Fig. Schematic of SCIEL MARS model Normal transient analysis : Consecutive power control of decrease and increase state The cycle has to reduce power from 100% to 60% The cycle has to increase power from 60% to 105% Abnormal transient analysis : Pipe break condition, unusual operation conditions of each component 20

21 THANK YOU