Performance analysis and comparison of multi-type thermal power-heat storage coupling systems

doi:10.19799/j.cnki.2095-4239.2021.0347

Abstract

Abstract:

For the large-scale development of renewable energy, the flexible peak-shaving capacity of thermal power is insufficient. Herein, a solution and novel operation strategy for integrated heat-storage systems in conventional thermal power are proposed. Considering a domestic 600-MW coal-fired unit as an example, a system scheme for coupling the unit with molten-salt, concrete, and subcritical-water heat-storage systems is designed. The thermal and peak-shaving performances of each coupled system are analyzed and compared. The results demonstrate that the thermal-power-heat-storage coupling system improves the peak-shaving capacity of the system and the cycle efficiency of the entire process. The coupling scheme with the best thermal performance involves using molten salt to extract reheated steam in the heat-storage process and using the stored heat to heat the high-pressure feedwater during heat release. Its efficiency is increased by >0.8%. However, the best coupling scheme for peak shaving performance involves using molten salt to extract high-pressure cylinder exhaust steam in the heat storage process and using the stored heat to heat the high-pressure feedwater when heat is released. Through the thermal storage unit, the new upper and lower peak shaving depth is 4.83% and 5.93%, respectively. This study provides theoretical and practical guidance for the flexible peak shaving of thermal power units.

Key words: thermal power plant, heat storage, coupling system, flexible peak shavin

CLC Number:

TK 02

Xianrong ZHANG, Yujie XU, Lijun YANG, Lexuan LI, Haisheng CHEN, Xuezhi ZHOU. Performance analysis and comparison of multi-type thermal power-heat storage coupling systems[J]. Energy Storage Science and Technology, 2021, 10(5): 1565-1578.

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储热介质	方案编号	储热策略	放热策略
熔盐	R1	再热蒸汽→除氧器	除氧水→LP1入口蒸汽
	R2	再热蒸汽→除氧器	给水泵出口水→锅炉给水
	R3	#2抽蒸汽→2号高加疏水管路	给水泵出口水→锅炉给水
混凝土	H1	再热蒸汽→除氧器	除氧水→LP2入口蒸汽
	H2	再热蒸汽→除氧器	给水泵出口水→锅炉给水
	H3	#4抽蒸汽→5号低加疏水管路	凝水→5号低加出口凝水管路
热水	S	除氧器出口压力水→凝汽器	凝水→5号低加出口凝水管路

参数	单位	数值
额定功率	kW	600185
主蒸汽流量	kg/h	1848755
主蒸汽压力/温度	MPa/℃	16.67/538
高压缸排气压力/温度	MPa/℃	3.793/322.5
再热蒸汽流量	kg/℃	1576082
再热蒸汽压力/温度	MPa/℃	3.414/538
背压	kPa	15
给水温度	℃	276.0
热耗	kJ/(kW·h)	8046

工况	抽汽编号	实际值/(kg·h^-1)	模拟值/(kg·h^-1)	相对误差/%
100%额定工况	#1	131949	131949	0
	#2	127543	127543	0
	#3	69404	69100	-0.44
	#4	55332	54971	-0.65
	#5	82023	82023	0
	#6	75662	75872	0.28
	#7	79202	79202	0
50%额定工况	#1	46839	46839	0
	#2	48092	48092	0
	#3	26052	26052	0
	#4	23650	23421	-0.97
	#5	35470	35470	0
	#6	33983	33983	0
	#7	22147	22147	0
40%额定工况	#1	35568	35568	0
	#2	36489	36489	0
	#3	19357	19357	0
	#4	18667	18461	-1.10
	#5	28090	28090	0
	#6	26841	26841	0
	#7	14208	14208	0

工况	指标	实际值	模拟值	相对误差/%
100%额定工况	电功率/kW	600185	600753.51	0.09
	热耗率/[kJ·(kW·h)^-1]	8064	8068.66	0.06
	热效率/%	40.58	40.56	-0.04
	?效率/%	39.94	39.92	-0.04
50%额定工况	电功率/kW	300112	300480.89	0.12
	热耗率/[kJ·(kW·h)^-1]	8653	8656.73	0.04
	热效率/%	37.74	37.71	0.09
	?效率/%	37.14	37.11	0.09
40%额定工况	电功率/kW	240058	240350.02	0.12
	热耗率/[kJ·(kW·h)^-1]	8928	8932.84	0.05
	热效率/%	36.46	36.46	-0.01
	?效率/%	35.88	35.88	-0.01

策略编号	储热过程热负荷/MW	放热过程热负荷/MW
a	30	30
b	90	30
c	30	90
d	90	90