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SUPPORTING INFORMATION300 MW Boiler Design Study for Coal-fired Supercritical CO2 Brayton CycleWengang Bai, Yifan Zhang, Yu Yang, Hongzhi Li , Mingyu YaoNational Energy R&D Center of Clean and High-efficiency Fossil-fired Power Generation Technology, Xi'an Thermal Power Research Institute Co. Ltd , Xi'an, 710054, People’s Republic of ChinaTable S1 Main parameters of the experiments conducted by Iverson, et al. Ref. [1]Table S2 Comparison of the calculation results and the experimental dataTable S3 Structure parameter and area calculation of HSHTable S4 Structure parameter and area calculation of HRHTable S5 Structure parameter and area calculation of LRHTable S6 Structure parameter and area calculation of LSHTable S7 Structure parameter and area calculation of SHTable S8 Calculation of coal combustion (Unit: Nm3/kg)Table S9 Calculation of the flue gas parameterTable S10 Key design parameters of HTR and LTRTable S11 Tubes used in the boilerFig. S1. Structure size of the furnace of the S-CO2 boiler (Unit: m)Fig. S2. Subsection model based on the quantity of heatFig. S3. Thermal-hydrodynamic calculation model of the S-CO2 boilerModel validation for S-CO2 cycleIt is found that there is almost no published experimental data with regard to the coal-fired S-CO2 Brayton cycle. As a compromise, experimental results from the literature of Iverson, et al. Ref. [1] are employed for the validation of the present model, because the core power conversion processes in this manuscript and in Iverson’s are similar, which are used for different heat sources. The experiment test loop in SNL is a standard recompression S-CO2 Brayton cycle. The main working condition parameters are shown in Table S1.Table S1 Main parameters of the experiments conducted by Iverson, et al. Ref. [1]Main parametersMeasured valuesSplit ratio to RC0.288Mass flow rate (kg/s)3.483Inlet pressure of MC (MPa)7.485Inlet temperature of MC (℃)31.8Inlet pressure of RC (MPa)7.574Inlet temperature of RC (℃)45.1Inlet pressure of turbine A (MPa)9.894Inlet temperature of turbine A (℃)390Mass flow rate of turbine A (kg/s)1.741Inlet pressure of turbine B (MPa)9.853Inlet temperature of turbine B (℃)390.6Mass flow rate of turbine B (kg/s)1.741Inlet pressure of solar source (MPa)10.045Inlet temperature of solar resource (℃)316.1Efficiency of MC (%)36.3Efficiency of RC (%)61.9Efficiency of turbine A (%)79.1Efficiency of turbine B (%)84.6The calculation results are compared with the experimental results in Table S2. Since there is no detailed geometric parameters shown in the Ref. [1], frictional pressure drops are neglect. The turbine heat loss is a test parameter in Iverson’s experiments, thus, it is assumed with the same value in the present calculation. In general, the errors between calculation results and experiment results are all in a reasonable range, indicating that the present model can accurately reproduce the experimental results of the S-CO2 Brayton cycle. Although the calculation of the net electricity and cycle efficiency are a little bit larger than the experiments, it is still within the error range of the tests and it is mainly because the frictional pressure drop are ignored in the calculation. Table S2 Comparison of the calculation results and the experimental dataOutput parametersExperimental data[1]Calculation resultserrorHeat duty of the heater (kW)341.7341.1-0.18%Heat duty of PC (kW)239.2239.0-0.08%Power consumption of MC (kW)39.238.3-2.30%Power consumption of RC (kW)16.718.28.98%Turbine power (total) (kW)74.276.02.43%Turbine heat loss (total) (kW)16.216.2(assumed)/Net electricity (kW)16.619.517.47%Cycle efficiency (%)4.95.716.33%[1] Iverson BD, Conboy TM, Pasch JJ, Kruizenga AM. Supercritical CO2 Brayton cycles for solar-thermal energy. Applied Energy. 2013;111:957-70.Area calculation of the S-CO2 boiler(1) Area of the furnaceThe structure size of the furnace of the designed S-CO2 boiler is shown in Fig. S1. According to the structure parameters in the Fig. S1, it is easy to obtain the area of the furnace. Area of the front wall (Af):Af =12.5×50+(5.06+7.0145/2)×12.5=732.1 m2Area of the rear wall (Ar): Ar =12.5×35.65+(5.06+7.0145/2)×12.5+12.5×2.7=586.5 m2Area of the side wall (As):As =(7.0145+12.5)×4.15+12.5×35.65+(3.3+6.86+12.5)×1.35/2+13×3.3=544.3 m2Total area of the furnace (AT):AT = Af + Ar +2×As +(13+6.86)×12.5+12.5×3.3=2697 m2Area of the WRH (AWRH): AWRH =1150 m2Area of the SWH (ASWH): ASWH = AT - AWRH =2697-1150=1547 m2Fig. S1 Structure size of the furnace of the S-CO2 boiler (Unit: m)(2) Area of HSHDetails of the area calculation of the HSH of the designed S-CO2 boiler is shown in Table S3.Table S3 Structure parameter and area calculation of HSHHSHStructure parameterSymbolUnitValueOuter diameter of tubeODmm51.00Wall thickness of tubetmm8.00Transverse rowsz1-9Longitudinal rowsz2-64Transverse average spacings1mm1371.60Longitudinal average spacings2mm61.00Heating surface heighthm13.00Heating surface areaAm2 (A=h×z1×z2×3.14×OD/1000)1199.13(3) Area of HRHDetails of the area calculation of the HRH of the designed S-CO2 boiler is shown in Table S4.Table S4 Structure parameter and area calculation of HRHHRHStructure parameterSymbolUnitValueOuter diameter of tubeODmm51.00Wall thickness of tubetmm6.00Transverse rowsz1-62Longitudinal rowsz2-68Transverse average spacings1mm200.00Longitudinal average spacings2mm100.00Heating surface heighthm11.00Heating surface areaAm2 (A=h×z1×z2×3.14×OD/1000)7426.66(4) Area of LRHDetails of the area calculation of the LRH of the designed S-CO2 boiler is shown in Table S5.Table S5 Structure parameter and area calculation of LRHLRHStructure parameterSymbolUnitValueOuter diameter of tubeODmm57.00Wall thickness of tubetmm4.50Transverse rowsz1-113Longitudinal rowsz2-54Transverse average spacings1mm110.00Longitudinal average spacings2mm70.00Heating surface heighthm5.50Heating surface areaAm2 (A=h×z1×z2×3.14×OD/1000)6006.75(5) Area of LSHDetails of the area calculation of the LSH of the designed S-CO2 boiler is shown in Table S6.Table S6 Structure parameter and area calculation of LSHLSHStructure parameterSymbolUnitValueOuter diameter of tubeODmm45.00Wall thickness of tubetmm4.50Transverse rowsz1-114Longitudinal rowsz2-51Transverse average spacings1mm110.00Longitudinal average spacings2mm70.00Heating surface heighthm5.50Heating surface areaAm2 (A=h×z1×z2×3.14×OD/1000)4518.35(6) Area of SHDetails of the area calculation of the SH of the designed S-CO2 boiler is shown in Table S7.Table S7 Structure parameter and area calculation of SHSHStructure parameterSymbolUnitValueOuter diameter of tubeODmm57.00Wall thickness of tubetmm4.50Transverse rowsz1-114Longitudinal rowsz2-67Transverse average spacings1mm110.00Longitudinal average spacings2mm70.00Heating surface heighthm11.00Heating surface areaAm2 (A=h×z1×z2×3.14×OD/1000)15037.54Calculations of coal combustion and flue gas parametersThe calculations of coal combustion and the flue gas parameters have been shown in Table S8 and S9.Table S8 Calculation of coal combustion (Unit: Nm3/kg)No.NameSymbolCalculation formulaValue1Theoretical air quantityV00.089×(Car+0.375×Sar)+0.265×Har-0.0333×Oar6.0552Theoretical N2 volumeV0N20.79×V0+0.008×Nar4.7893Total volume of CO2 and SO2VRO20.01866×(Car+0.375×Sar)1.1454Theoretical volume of water vaporV0H2O0.111×Har+0.0124×Mar+0.0161×V00.6575Theoretical flue gas volumeV0gV0N2+ V0H2O + VRO26.591Table S9 Calculation of the flue gas parameterParameterSymbolUnitFurnaceHRHFlue gas damperSHAPHExcess air ratio at the exitαav-1.21.211.221.231.32Flue gas volumeVg(Vg=V0g+1.0161(αav -1)V0)Nm3/kg7.827.887.948.018.56Flue gas massGg(Gg=1-Aar/100+1.306αavV0)kg/kg10.3610.4410.5210.6011.31Fly ash massμash(μash=0.95Aar/100/Gg)kg/kg0.01150.01140.01130.01120.0105Pressure drop calculation of heat exchangersIt is widely acknowledged that Printed Circuit Heat Exchanger (PCHE) can be employed as the recuperators and the pre-cooler. Hence, to keep a same standard in the following calculations, counterflow PCHEs were employed as the recuperators. A subsection method based on quantity of heat was employed to build the calculation model for PCHE, shown in Fig. S2. The subsection number of this model was selected as 10, and it was proved to have enough calculation accuracy with less computation time.Fig. S2 Subsection model based on the quantity of heatAccording to the calculations of High Temperature Recuperator (HTR) and Low Temperature Recuperator (LTR), key design parameters of HTR and LTR are obtained, shown in Table S10. Pressure drops of HTR and LTR are 0.052 MPa and 0.047 MPa. These results are employed to obtain the boundary conditions of the present S-CO2 boiler. Table S10 Key design parameters of HTR and LTRPCHEHTRLTRcore length (flow direction)/m3.534.74core width/m64core height/m43channel shapesemicirclesemicirclediameter/mm22channel numbers2497266616641998heat transfer area/m260373.540485.6heat transfer coefficient/Wm-2K-1845.51308.8pressure drop/MPa0.0520.047Pressure drop calculation of boilerThe pressure drop in the boiler was assumed firstly, to determine the boundary conditions for the S-CO2 boiler design. Then, the elementary design of the boiler was made. After knowing the geometric constructions of all the boiler heating surfaces, thermal-hydrodynamic calculations of the boiler were made, and the new pressure drop in the boiler was calculated. The thermal-hydrodynamic calculation model shown in Fig. S3 was used, and detailed tube size is shown in Table S11.According to the thermal-hydrodynamic calculations, pressure drops of the spiral wall heater and the superheater are about 1.1 MPa and 0.9 MPa , and pressure drop of the wall re-heater and the reheaters are 0.1 MPa and 0.2 MPa, respectively. The thermal-hydrodynamic calculations presented here are simplified, and inhomogeneous distribution of heat flux and flow deviation are all neglected. Because the thermal-hydrodynamic analysis is out of the scope of this paper, it will not be further discussed in this paper, although it is an interesting topic. It would be carried out in our future work.Fig. S3 Thermal–hydrodynamic calculation model of the S-CO2 boilerTable S11 Tubes used in the boilerSWHWRHLSHHSHLRHHRHTube outside diameter /mm345045515751Tube thickness /mm54.54.564.56Tube pitch /mm4360.81131370110200 ................
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