Feasibility study on steam supply expansion of combined heat and power based on molten salt energy storage

doi:10.3969/j.issn.2097-0706.2026.05.008

Abstract

Abstract:

Combined heat and power （CHP） units utilize part of the steam that has performed work as a secondary product for heating or industrial steam supply， which is an important approach for in-depth energy saving and emission reduction. However， the operation mode of CHP units —where power generation is determined by heat demand—limits their deep peak shaving capability. Molten salt energy storage technology can improve the operational flexibility of units and achieve heat-power decoupling to a certain extent. Therefore， a 660 MW power unit with a steam supply of 150 t/h （at 1.8 MPa and 300 ℃） was taken as the case study， and the EBSILON software was used for modeling to optimize the conventional steam supply scheme of desuperheating and depressurizing the hot reheat steam. By combining the ejector on the steam turbine side and the molten salt device on the heating network side， a steam supply scheme was proposed—namely， the main steam extraction-induced hot reheat steam coupled with molten salt. This scheme stored heat during the off-peak electricity price period and released the stored heat during the peak electricity price period. The results showed that to provide industrial steam supply of 150 t/h （at 1.8 MPa and 300 ℃）， the power operation range of the units under the original steam supply scheme was 39.34%~94.08% turbine heat acceptance （THA）， while that under the molten salt-coupled steam supply scheme was 21.74%~99.17% THA. The molten salt steam supply scheme not only broadened the safe operation boundary of heat supply， but also extended the operation range of thermal power units， thereby providing a reference for heat storage systems to participate in unit operation scheduling. On a typical day， the increased benefits after configuring the molten salt system mainly came from compensation benefits and coal-saving benefits. The coal consumption cost was reduced by 178 700 yuan per day， the new compensation benefits reached 351 000 yuan per day， the daily profit increased by 392 300 yuan， and the system payback period was 5.54 years.

Key words: molten salt energy storage, combined heat and power generation, power peak shaving, simulation model, economic analysis, flexibility retrofit

CLC Number:

TK01

ZHANG Yongjian, LI Bin, XING Geyu, SUN Junpeng, XU Gang, XUE Xiaojun. Feasibility study on steam supply expansion of combined heat and power based on molten salt energy storage[J]. Integrated Intelligent Energy, 2026, 48(5): 74-82.

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参数	数值
主蒸汽流量/(t·h^-1)	1 796.4
主蒸汽压力/MPa	30.00
主蒸汽温度/℃	605
冷段再热蒸汽压力/MPa	5.37
冷段再热蒸汽温度/℃	333.7
热段再热蒸汽压力/MPa	4.99
热段再热蒸汽温度/℃	622
热段再热蒸汽流量/(t·h^-1)	1 408.7
额定背压/kPa	4.5
发电机额定功率/MW	660

工况	模拟值/MW	设计值/MW	误差/%
100%THA	659.02	660.00	-0.15
75%THA	495.67	495.00	0.14
50%THA	330.54	330.00	0.16
30%THA	198.96	198.00	0.48

参数	数值
组分	60%NaNO₃, 40%KNO₃
比热容/[kJ·(kg·K)^-1]	1.52
密度/(Kg·m^-3)	1 860
熔点/℃	240
最高工作温度/℃	575

参数	储热过程	放热过程
储放热时间/h	8.00	2.11
锅炉负荷率/%	30	100
单位时长换热量/(MW·h)	25.56	96.74
熔盐量/（t·h^-1）	310	1 173
机组负荷/MW	143.54	654.54

时段		电价
平段	00:00 — 08:00	0.306
峰段	08:00 —10:00 17:00 —23:00	0.499
谷段	09:00 —17:00	0.186