Analysis of Influence of Flue Gas Recirculation on Thermodynamic Performance and Economic Efficiency of 125 MW Supercritical CO2 Coal-Fired Power Generation Unit

doi:10.12096/j.2096-4528.pgt.24034

Abstract

Abstract:

Objectives Flue gas recirculation (FGR) can effectively mitigate the issue of high furnace wall temperature in supercritical carbon dioxide (S-CO₂) boilers. The selection of an appropriate flue gas recirculation rate is critical for the design of S-CO₂ boilers. Therefore, this study analyzes the influence of different flue gas recirculation rates on the thermodynamic performance and economic efficiency of the boilers. Methods A 125 MW S-CO₂ coal-fired boiler is taken as the research object. The thermodynamic performance of the boiler under different flue gas recirculation rates is analyzed using a thermodynamic calculation method and the conceptual design is proposed, while keeping the boiler efficiency constant. On this basis, the economic efficiency of the boiler and the unit is further studied using the multistage weighted mass method and levelized cost of electricity. Results With increasing flue gas recirculation rate, the material cost of boiler’s radiant heating surface decreases, while the cost of other heating surfaces increases, leading to an increase in the total investment cost of the boiler. However, FGR results in additional costs for fans, fuel, and other extra expenses. Conclusions Considering both safety and economic efficiency, a flue gas recirculation rate of 20%-30% is recommended for optimal boiler design.

Key words: thermal power generation, coal-fired power generation, supercritical carbon dioxide (S-CO₂), boiler, economic analysis, flue gas recirculation (FGR), thermal calculation

CLC Number:

TK 22

Jing CHEN, Hui LIU, Meng ZHU, Can WANG, Lei CHEN, Jing ZHOU, Kai XU, Long JIANG, Song HU, Jun XIANG. Analysis of Influence of Flue Gas Recirculation on Thermodynamic Performance and Economic Efficiency of 125 MW Supercritical CO₂ Coal-Fired Power Generation Unit[J]. Power Generation Technology, 2025, 46(5): 986-995.

Figures/Tables 13

References 30

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循环参数	设计值	循环参数	设计值
MC入口温度/℃	32.00	BC效率/%	89.00
MC入口压力/MPa	7.60	BC分流比	0.347
MC出口压力/MPa	26.00	CW质量流量/(t/h)	3 325.4
BC入口温度/℃	84.53	RCW质量流量/(t/h)	3 749.2
BC入口压力/MPa	7.70	BH质量流量/(t/h)	423.8
BC出口压力/MPa	25.90	CW入口温度/℃	524.92
LTR入口温度(高温测)/℃	77.33	CW入口压力/MPa	25.80
LTR出口温度(高温测)/℃	201.60	RH入口温度/℃	522.49
HTR和LTR夹点温度/℃	5.00	RH入口压力/MPa	14.05
各部件压降(除锅炉外)/MPa	0.10	SH出口温度/℃	600.00
HPT效率/%	94.00	SH出口压力/MPa	25.00
LPT效率/%	94.00	RH出口温度/℃	600.00
MC效率/%	89.00	RH出口压力/MPa	13.45

循环参数	设计值	循环参数	设计值
MC入口温度/℃	32.00	BC效率/%	89.00
MC入口压力/MPa	7.60	BC分流比	0.347
MC出口压力/MPa	26.00	CW质量流量/(t/h)	3 325.4
BC入口温度/℃	84.53	RCW质量流量/(t/h)	3 749.2
BC入口压力/MPa	7.70	BH质量流量/(t/h)	423.8
BC出口压力/MPa	25.90	CW入口温度/℃	524.92
LTR入口温度(高温测)/℃	77.33	CW入口压力/MPa	25.80
LTR出口温度(高温测)/℃	201.60	RH入口温度/℃	522.49
HTR和LTR夹点温度/℃	5.00	RH入口压力/MPa	14.05
各部件压降(除锅炉外)/MPa	0.10	SH出口温度/℃	600.00
HPT效率/%	94.00	SH出口压力/MPa	25.00
LPT效率/%	94.00	RH出口温度/℃	600.00
MC效率/%	89.00	RH出口压力/MPa	13.45

类别	参数	数值
	干燥无灰基挥发分质量分数V_daf/%	34.73
工业分析	收到基水分质量分数M_ar/%	15.55
	收到基灰分质量分数A_ar/%	8.80
	收到基碳质量分数C_ar/%	61.70
	收到基氢质量分数H_ar/%	3.67
元素分析	收到基氧质量分数O_ar/%	8.56
	收到基氮质量分数N_ar/%	1.12
	收到基硫质量分数S_ar/%	0.60
性能指标	收到基低位发热量Q_{net, ar}/(kJ/kg)	23 442

类别	参数	数值
	干燥无灰基挥发分质量分数V_daf/%	34.73
工业分析	收到基水分质量分数M_ar/%	15.55
	收到基灰分质量分数A_ar/%	8.80
	收到基碳质量分数C_ar/%	61.70
	收到基氢质量分数H_ar/%	3.67
元素分析	收到基氧质量分数O_ar/%	8.56
	收到基氮质量分数N_ar/%	1.12
	收到基硫质量分数S_ar/%	0.60
性能指标	收到基低位发热量Q_{net, ar}/(kJ/kg)	23 442

参数	300 MW S-CO₂锅炉
参数	计算值	设计值	误差/%
屏底烟温	1 270.7 ℃	—	—
炉膛出口烟温	1 030.7 ℃	1 025.0 ℃	0.56
排烟温度	1 14.2 ℃	1 10.0 ℃	3.82
主蒸汽出口温度	601.0 ℃	602.0 ℃	-0.17
主蒸汽出口压力	32.15 MPa	32.00 MPa	0.47
再热蒸汽出口温度	622.2 ℃	622.0 ℃	0.03
再热蒸汽出口压力	17.98 MPa	17.80 MPa	1.00

Analysis of Influence of Flue Gas Recirculation on Thermodynamic Performance and Economic Efficiency of 125 MW Supercritical CO₂ Coal-Fired Power Generation Unit

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参数	数值
固定开支率	0.12
折扣利率	0.06
煤炭增值率	0.02
C_LOM上升率	0.02
容量因子	0.85
煤炭价格/(元/t)	682
建造时长/a	3
设备寿命/a	30

参数	烟气再循环率
参数	10%	20%	30%	40%
发电功率/MW	125	125	125	125
净功率/MW	119.93	119.84	119.73	119.58
锅炉效率/%	93.39	93.39	93.39	93.39
循环效率/%	50.57	50.57	50.57	50.57
净效率/%	45.31	45.27	45.23	45.17
煤耗量/(t⋅h^-1)	40.65	40.65	40.65	40.65

成本项	烟气再循环率
成本项	10%	20%	30%	40%
C_LCC	0.121 8	0.122 9	0.123 8	0.126 9
C_LOM	0.063 0	0.063 0	0.063 0	0.063 0
C_LFP	0.293 2	0.293 4	0.293 7	0.294 0
C_XC	0.129 4	0.129 5	0.129 6	0.129 8
C_LCOE	0.607 4	0.608 8	0.610 1	0.613 7

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