Design and economic analysis of the molten salt heat storage system for a 300 MW coal-fired heating unit

doi:10.3969/j.issn.2097-0706.2024.09.006

Abstract

Abstract:

Deep peak shaving for thermal power units is an important measure to ensure the stable operation of the power grid. A thermodynamic model of a 300 MW coal-fired heating unit in China is established by software EBSILON. The accuracy of the model is verified by comparing the simulation parameters with the design values. To further enhance the deep peak shaving capability of the unit， two molten salt heating schemes powered by extracted main steam and reheat steam are proposed. To meet heating demands， the molten salt heat storage system is coupled to the original thermodynamic model， considering the storaged/released heating power of the system and molten salt heat storage capacity. Based on the model， the peak shaving depth and the power generation during non-peak shaving period are obtained. The main steam extraction scheme and the reheat steam extraction scheme can increase the peak shaving depth by 34.26 MW and 19.30 MW， respectively， and raise the peak power generation by 14.77 MW and 12.33 MW. At the same time， the economic performance analyses of the system in the electricity auxiliary service market and the electricity spot market are carried out. The results show that under certain peak shaving subsidies or peak-valley electricity price differences， the capital internal return rate of the project can reach 10%.

Key words: coal-fired heating unit, molten salt thermal storage, simulation model, economic analysis, "dual carbon" target, fexibility modification, deep peak shaving

CLC Number:

TK01

ZHAO Dazhou, XIE Yurong, ZHANG Zhongping, DENG Ruifeng, LIU Lili. Design and economic analysis of the molten salt heat storage system for a 300 MW coal-fired heating unit[J]. Integrated Intelligent Energy, 2024, 46(9): 45-52.

Figures/Tables 14

Fig.1

Table 1

Table 2

Fig.2

Table 3

Fig.3

Table 4

Fig.4

Table 5

Table 6

Table 7

Table 8

Table 9

Fig.5

References 20

[1]	李建林, 邸文峰, 李雅欣, 等. 长时储能技术及典型案例分析[J]. 热力发电, 2023, 52(11):85-94.
	LI Jianlin, DI Wenfeng, LI Yaxin, et al. Analysis of long-term energy storage technologies and typical case studies[J]. Thermal Power Generation, 2023, 52(11):85-94.
[2]	李峻, 祝培旺, 王辉, 等. 基于高温熔盐储热的火电机组灵活性改造技术及其应用前景分析[J]. 南方能源建设, 2021, 8(3):63-70.
	LI Jun, ZHU Peiwang, WANG Hui, et al. Flexible modification technology and application prospect of thermal power unit based on high temperature molten salt heat storage[J]. Southern Energy Construction, 2021, 8(3):63-70.
[3]	左芳菲, 韩伟, 姚明宇. 熔盐储能在新型电力系统中应用现状与发展趋势[J]. 热力发电. 2023, 52(2):1-9.
	ZUO Fangfei, HAN Wei, YAO Mingyu, et al. Application status and development trend of molten salt energy storage in novel power systems[J]. Thermal Power Generation, 2023, 52(2):1-9.
[4]	张国龙, 居文平, 常东锋, 等. 电阻式熔盐加热器动态建模与参数化分析[J]. 热力发电, 2023, 52(9):155-161.
	ZHANG Guolong, JU Wenping, CHANG Dongfeng, et al. Dynamic modeling and parametric analysis of resistance molten salt heater[J]. Thermal Power Generation, 2023, 52(9):155-161.
[5]	沈强, 顾晓鸥, 翁建明, 等. 蒸汽加热熔盐换热试验研究[J]. 锅炉技术, 2023, 54(1):27-33.
	SHEN Qiang, GU Xiaoou, WENG Jianming, et al. Experimental study on heat transfer characteristics of steam heated molten salt system[J]. Boiler Technology, 2023, 54(1):27-33.
[6]	罗晓乐, 宋洋, 徐翔, 等. 计及风电不确定性的综合能源系统储能优化配置研究[J]. 东北电力技术, 2021, 42(12):18-25,46.
	LUO Xiaole, SONG Yang, XU Xiang, et al. Research on optimal allocation of energy storage of integrated energy system considering wind power uncertainty[J]. Northeast Electric Power Technology, 2021, 42(12):18-25,46.
[7]	孟强, 杨洋, 熊亚选. 添加纳米SiO₂熔盐传热储热稳定性能研究[J]. 综合智慧能源, 2023, 45(9):32-39. doi: 10.3969/j.issn.2097-0706.2023.09.005
	MENG Qiang, YANG yang, XIONG Yaxuan. Study on thermal stability of molten salt composites added with SiO₂ nanoparticles[J]. Integrated Intelligent Energy, 2023, 45(9):32-39. doi: 10.3969/j.issn.2097-0706.2023.09.005
[8]	邹小刚, 刘明, 肖海丰, 等. 火电机组耦合熔盐储热深度调峰系统设计及性能分析[J]. 热力发电, 2023, 52(2):146-153.
	ZOU Xiaogang, LIU Ming, XIAO Haifeng, et al. Design and performance analysis of deep peak shaving system of thermal power units coupled with molten salt heat storage[J]. Thermal Power Generation, 2023, 52(2):146-153.
[9]	马汀山, 王伟, 王东晔, 等. 基于熔盐储热辅助煤电机组深度调峰的系统设计及容量计算方法研究[J]. 热力发电, 2023, 52(7):113-118.
	MA Tingshan, WANG Wei, WANG Dongye, et al. Research on system design and capacity calculation method for deep peak shaving of coal-fire unit based on molten salt heat storage assistance[J]. Thermal Power Generation, 2023, 52(7):113-118.
[10]	宋晓辉, 韩伟, 王兴, 等. 基于高温熔盐储热系统的火电机组深度调峰方案对比及分析[J]. 热能动力工程, 2023, 38(11):64-74.
	SONG Xiaohui, HAN Wei, WANG Xing, et al. Comparison and analysis of deep peak shaving schemes for thermal power units based on high-temperature molten salt heat storage system[J]. Journal of Engineering for Thermal Energy and Power, 2023, 38(11):64-74.
[11]	庞力平, 张世刚, 段立强. 高温熔盐储能提高二次再热机组灵活性研究[J]. 中国电机工程学报, 2021, 41(8):2682-2690.
	PANG Liping, ZHANG Shigang, DUAN Liqiang. Flexibility improvement study on the double reheat power generation unit with a high temperature molten salt thermal energy storage[J]. Proceedings of the CSEE, 2021, 41(8):2682-2690.
[12]	刘金恺, 鹿院卫, 魏海姣, 等. 熔盐储热辅助燃煤机组调峰系统设计及性能对比[J]. 热力发电, 2023, 52(2):111-118.
	LIU Jinkai, LU Yuanwei, WEI Haijiao, et al. Design and performance comparison of peak shaving system of coal-fired unit aided by molten salt heat storage[J]. Thermal Power Generation, 2023, 52(2):111-118.
[13]	苗林, 刘明, 张可臻, 等. 集成电制热熔盐储热的燃煤发电系统热力性能研究[J]. 工程热物理学报, 44(11):2999-3007.
	MIAO Lin, LIU Ming, ZHANG Kezhen, et al. Thermodynamic analysis on the coal-fired power plant integrated with power-to-heat molten salt thermal energy storage system[J]. Journal of Engineering Thermophysics, 44(11):2999-3007.
[14]	WANG B G, MA H, REN S J, et al. Effects of integration mode of the molten salt heat storage system and its hot storage temperature on the flexibility of a subcritical coal-fired power plant[J]. Journal of Energy Storage, 2023(58):1307-1318.
[15]	魏海姣, 鹿院卫, 吴玉庭, 等. 燃煤机组灵活性运行系统㶲分析[J]. 北京工业大学学报, 2022, 48(12):1307-1318.
	WEI Haijiao, LU Yuanwei, WU Yuting, et al. Exergy analysis of flexible operation of coal-fired power plant[J]. Journal of Beijing University of Technology, 2022, 48(12):1307-1318.
[16]	魏海姣, 鹿院卫, 张灿灿, 等. 燃煤机组灵活性调节技术研究现状及展望[J]. 华电技术, 2020, 42(4): 57-63.
	WEI Haijiao, LU Yuanwei, WU Yuting, et al. Exergy analysis of flexible operation of coal-fired power plant[J]. Huadian Technology, 2020, 42(4): 57-63.
[17]	王永旭, 周天羽, 邓庚庚, 等. 配置吸收式热泵的热电联产机组厂级智能运行优化[J]. 综合智慧能源, 2024, 46(3): 20-28. doi: 10.3969/j.issn.2097-0706.2024.03.003
	WANG Yongxu, ZHOU Tianyu, DENG Genggeng, et al. Plant-level intelligent operation optimization for cogeneration units equipped with absorption heat pumps[J]. Integrated Intelligent Energy, 2024, 46(3): 20-28. doi: 10.3969/j.issn.2097-0706.2024.03.003
[18]	王芳. 热储能技术在新型电力系统中的应用综述[J]. 东北电力技术, 2024, 45(3):13-15.
	WANG Fang. Review on application of thermal energy storage technology in new power systems[J]. Northeast Electric Power Technology, 2024, 45(3):13-15.
[19]	张钟平, 刘亨, 谢玉荣, 等. 熔盐储热技术的应用现状与研究进展[J]. 综合智慧能源, 2023, 45(9): 40-47. doi: 10.3969/j.issn.2097-0706.2023.09.006
	ZHANG Zhongping, LIU Heng, XIE Yurong, et al. Application and research progress of molten salt heat storage technology[J]. Integrated Intelligent Energy, 2023, 45(9): 40-47. doi: 10.3969/j.issn.2097-0706.2023.09.006
[20]	陈睿哲, 熊亚选, 张慧, 等. 储能供热熔盐换热器设计及运行特性分析[J]. 华电技术, 2020, 42(12): 54-59.
	CHEN Ruizhe, XIONG Yaxuan, ZHANG Hui, et al. Design and dynamic performance analysis on a molten salt heat exchanger for energy storage and heating[J]. Huadian Technology, 2020, 42(12): 54-59.

管线	平均/最大热负荷/（t·h^-1）	温度/℃	压力/MPa	抽汽位置
次高压供热管线	16.52/23.04	320	3.05	汽轮机一段抽汽减温减压
中压供热管线1	33.75/58.75	265	2.25	机组再热冷段减温减压
中压供热管线2	59.15/77.06	280	1.50	机组再热热段减温减压
低压供热管线	106.92/51.77	270	1.00	汽轮机四段抽汽经减温器减温

技术路线	具体储/放热过程
1	储热：抽主蒸汽加热熔盐，换热后的蒸汽供应次高压供热管线、中压供热管线1，2；释热：熔盐放热产生3种不同品级的蒸汽，分别供应次高压供热管线、中压供热管线1，2
2	储热：抽再热热段蒸汽加热熔盐，换热后的蒸汽供应中压供热管线1，2以及低压供热管线；释热：熔盐放热产生3种不同品级的蒸汽，分别供应中压供热管线1，2以及低压供热管线

项目	二元熔盐	三元熔盐
组分	60%NaNO₃+40%KNO₃	53%KNO₃+40%NaNO₂+7%NaNO₃
使用温度/℃	290~560	190~425

项目		VWO工况	100%THA工况
发电功率	仿真值/MW	332.74	300.87
	设计值/MW	331.74	300.00
	相对误差/%	-0.30	-0.29
一级抽汽回热量	仿真值/(t·h^-1)	79.32	65.87
	设计值/(t·h^-1)	78.95	65.51
	相对误差/%	3.61	-0.55
二级抽汽回热量	仿真值/(t·h^-1)	81.89	69.86
	设计值/(t·h^-1)	83.13	70.96
	相对误差/%	-2.59	1.55
三级抽汽回热量	仿真值/(t·h^-1)	26.71	21.18
	设计值/(t·h^-1)	26.4	22.14
	相对误差/%	1.36	4.30
四级抽汽回热量	仿真值/(t·h^-1)	88.05	77.61
	设计值/(t·h^-1)	87.61	76.76
	相对误差/%	-0.49	-1.10
五级抽汽回热量	仿真值/(t·h^-1)	26.21	22.68
	设计值/(t·h^-1)	27.01	23.44
	相对误差%	2.97	3.25
六级抽汽回热量	仿真值/(t·h^-1)	39.96	35.68
	设计值/(t·h^-1)	39.16	34.88
	相对误差/%	-2.06	-2.30
七级抽汽回热量	仿真值/(t·h^-1)	18.98	15.60
	设计值/(t·h^-1)	19.00	15.73
	相对误差/%	0.13	0.83
八级抽汽回热量	仿真值/(t·h^-1)	35.28	28.57
	设计值/(t·h^-1)	35.76	28.55
	相对误差/%	1.35	-0.08
低压缸排气量	仿真值/(t·h^-1)	619.37	558.44
	设计值/(t·h^-1)	618.73	558.1
	相对误差/%	-0.10	-0.06
除氧器给水温度	仿真值/℃	141.59	137.59
	设计值/℃	141.3	137.3
	相对误差/%	-0.20	-0.21

项目	技术路线1	技术路线2
抽汽量/（t·h^-1）	163.79	157.15
熔盐量/t	1 500	1 200
换热器储/释热功率/MW	21.22/31.03	17.29/25.54
高温熔盐温度/℃	493.44	493.23
低负荷时发电量/MW	125.74	141.65
调峰深度/MW	34.26	19.30
顶峰发电量/MW	14.77	12.33