CN-121977193-A - Energy storage and steam supply system and method for coupling Carnot battery of thermal power generating unit

CN121977193ACN 121977193 ACN121977193 ACN 121977193ACN-121977193-A

Abstract

The invention relates to the technical field of energy storage and thermal power generating unit coupling, in particular to a thermal power generating unit coupling Kano battery energy storage and steam supply system and a method, wherein a heat pump energy storage circulation loop takes supercritical carbon dioxide as a working medium and is sequentially connected with a low-temperature heat source heat exchanger, a heat regenerator low-temperature side, a compressor, a molten salt heat exchanger, a heat regenerator high-temperature side and an expansion mechanism along a flow direction to form closed circulation; the energy release water/steam loop comprises a fused salt-water heat exchanger group thermally coupled with the high-temperature fused salt tank and is used for heating condensed water and outputting industrial steam. The quality improvement storage and the on-demand release of the waste heat of the flue gas are realized through the cooperative operation of the energy storage, the energy release and the heat regeneration steps. The problems of limited peak regulation capacity, reduced running energy efficiency and insufficient heat supply stability caused by the characteristic of 'heat fixed electricity' when the steam extraction heat supply unit deeply regulates the peak are effectively solved.

Inventors

LI QIBIN
WANG ZHILIN
WANG PENGLAI

Assignees

重庆大学

Dates

Publication Date: 20260505
Application Date: 20260106

Claims (9)

1. A thermal power generating unit coupling Kano battery energy storage and steam supply system is characterized in that, The system comprises a heat pump energy storage circulation loop, a fused salt loop and an energy release water/steam loop; The heat pump energy storage circulation loop sequentially comprises a low-temperature heat source heat exchanger, a low-temperature side of a heat regenerator, a compressor, a molten salt heat exchanger, a high-temperature side of the heat regenerator and an expander which are connected through pipelines along the flow direction of working media, and forms closed circulation; the molten salt loop comprises a high-temperature molten salt tank and a low-temperature molten salt tank, and the high-temperature molten salt tank and the low-temperature molten salt tank are respectively connected with the molten salt heat exchanger to form a molten salt circulation flow path; The energy-releasing water/steam loop comprises a molten salt-water heat exchanger group thermally coupled with the high-temperature molten salt tank and used for heating incoming water from a condensate pump and outputting industrial steam, and the molten salt-water heat exchanger group comprises a molten salt-water preheater, a molten salt-water evaporator and a molten salt-water superheater which are sequentially arranged.
2. The thermal power generating unit coupling Carnot battery energy storage and steam supply system of claim 1, The discharge pressure of the compressor ranges from 10MPa to 25MPa, the expander is a turbine expander, and the pressure of the working medium after expansion is not lower than 8MPa.
3. The thermal power generating unit coupling Carnot battery energy storage and steam supply system of claim 1, The maintaining temperature of the high-temperature molten salt tank is 380-390 ℃, and the maintaining temperature of the low-temperature molten salt tank is 190-210 ℃; The molten salt is ternary salt or binary salt, wherein the ternary salt consists of 53% of potassium nitrate, 40% of sodium nitrite and 7% of sodium nitrate, and the binary salt consists of 60% of sodium nitrate and 40% of potassium nitrate.
4. The thermal power generating unit coupling Carnot battery energy storage and steam supply system of claim 1, The low temperature heat source heat exchanger is coupled with the flue gas inlet at a temperature of 150 ℃ to 250 ℃.
5. The thermal power generating unit coupling Carnot battery energy storage and steam supply system of claim 1, The thermal power generating unit coupling Carnot battery energy storage steam supply system further comprises a thermal power generating unit, wherein the thermal power generating unit comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder and a generator, the high-pressure cylinder is connected with the boiler, the medium-pressure cylinder is connected with the high-pressure cylinder, the low-pressure cylinder is connected with the medium-pressure cylinder, and the generator is respectively connected with the low-pressure cylinder and the compressor.
6. The thermal power generating unit coupling Kano battery energy storage and steam supply system according to claim 5, The thermal power generating unit further comprises a condenser, a low-pressure heater, a deaerator and a high-pressure heater, wherein the condenser is connected with the low-pressure cylinder, the low-pressure heater is respectively connected with the low-pressure cylinder and the condenser, the deaerator is respectively connected with the medium-pressure cylinder and the low-pressure heater, and the high-pressure heater is respectively connected with the medium-pressure cylinder, the high-pressure cylinder, the boiler and the deaerator.
7. The thermal power unit coupling carnot battery energy storage and steam supply method is suitable for the thermal power unit coupling carnot battery energy storage and steam supply system as claimed in claim 1, and is characterized by comprising the following steps: under the energy storage working condition, the supercritical carbon dioxide working medium absorbs the waste heat of the flue gas in the low-temperature heat source heat exchanger to raise the temperature, then the flue gas is compressed and boosted by the compressor to raise the temperature, and then flows through the molten salt heat exchanger to release heat to the molten salt from the low-temperature molten salt tank, and the heated molten salt is stored in the high-temperature molten salt tank; Under the energy release working condition, molten salt in the high-temperature molten salt tank flows through the molten salt-water heat exchanger group, water is heated by a condensate pump to generate industrial steam, and the exothermic molten salt returns to the low-temperature molten salt tank; in the heat pump energy storage circulation loop, the working medium flowing through the molten salt heat exchanger is on the high temperature side of the heat regenerator, and sensible heat exchange is carried out on the working medium coming from the low temperature heat source heat exchanger and going into the compressor on the low temperature side of the heat regenerator.
8. The thermal power generating unit coupling Carnot battery energy storage and steam supply method according to claim 7, Under the energy storage working condition, calculating the coefficient of performance COP of the system and the efficiency of energy storage Yong, wherein the coefficient of performance COP is defined as the ratio of the increment of the heat stored by molten salt to the circulating net input work, and the efficiency of energy storage Yong is defined as the ratio of the Yong variable quantity of an energy storage medium to the sum of the input work and the heat source input Yong; Under the energy release working condition, the thermoelectric factor and the energy release Yong efficiency are calculated, wherein the thermoelectric factor is defined as the ratio of the unit output energy after the system is coupled to the unit output energy under the condition of the same boiler heat absorption, and the energy release Yong efficiency is defined as the ratio of the sum of the output electric energy and Yong contained in externally supplied steam to the sum of the change amount of the energy storage medium Yong and the fuel Yong.
9. The thermal power generating unit coupling Carnot battery energy storage and steam supply method according to claim 8, Optimizing the system operation parameters by adopting a multi-objective optimization algorithm; the operation parameters comprise at least one of compressor outlet pressure, expander outlet temperature, low-temperature molten salt tank temperature and high-temperature molten salt tank temperature; Optimization objectives include maximizing the coefficient of performance COP and maximizing the energy storage Yong efficiency.

Description

Energy storage and steam supply system and method for coupling Carnot battery of thermal power generating unit Technical Field The invention relates to the technical field of energy storage and thermal power generating unit coupling, in particular to a thermal power generating unit coupling Kano battery energy storage and steam supply system and method. Background With the promotion of the construction of a novel electric power system, the installation of new energy sources such as wind power, photovoltaic and the like and the duty ratio of power generation are continuously improved, and the output of the novel electric power system has obvious fluctuation, intermittence and randomness, so that challenges are brought to the safe and stable operation of the electric power system. In order to ensure the power balance and the power grid stability, the coal-fired thermal power unit is gradually transformed from the traditional main power supply to the basic guarantee power supply and the system regulation power supply, and the tasks of deep peak regulation, rapid climbing, starting, stopping, peak regulation and the like are needed to be born. This results in high capacity high parameter units frequently operating under low load and off-design conditions, thereby causing increased coal consumption, reduced equipment life, and both operational economics and reliability. For the steam extraction heat supply unit with heat supply tasks, the operation characteristic of 'heat fixed electricity' further compresses the peak regulation space of the unit, namely, the power generation output is difficult to flexibly adjust while the stable heat supply requirement is met, and the adjusting capability of the unit in an electric power system is limited. In order to break through the above-mentioned "heat decide electricity" constraint and promote the flexibility of thermal power generating unit, energy storage technology is regarded as effective solution. The fused salt Carnot battery is used as a novel large-scale electric-thermal energy storage technology taking high-temperature fused salt as a heat storage medium, can convert electric energy or waste heat into high-temperature heat energy for storage in a period of low electricity price or surplus new energy, and converts the stored heat energy into electric energy or industrial steam for output through efficient thermodynamic cycle when a power grid is needed. The technology has the advantages of large energy storage scale, long storage time, capability of realizing gradient utilization of heat energy and the like, and is considered to be suitable for coupling with a thermal power unit so as to improve the integral peak regulation capacity and the operation economy of the unit. However, how to integrate the fused salt Carnot battery with the existing thermal power generating unit, especially the steam extraction and heat supply unit, effectively and stably still faces technical challenges. On one hand, reasonable system configuration and cycle working medium are required to be designed to realize efficient quality improvement and storage of low-grade heat sources such as flue gas waste heat and the like, and on the other hand, the problems of flexible switching and coordination control of energy storage and energy release working conditions are required to be solved, industrial steam meeting parameters can be continuously and stably output under different working conditions and deep peak shaving, and the overall energy efficiency of the system is improved as much as possible. Therefore, an innovative system integration method and an optimized operation strategy are urgently needed. Disclosure of Invention The invention aims to provide a thermal power unit coupling Carnot battery energy storage and steam supply system and method, which solve the problems of insufficient peak regulation capacity, reduced operation energy efficiency and incapability of continuously and stably supplying industrial steam caused by 'heat power setting' constraint during deep peak regulation of a steam extraction and heating unit. In order to achieve the aim, the invention provides a thermal power unit coupling Carnot battery energy storage and steam supply system, which comprises a heat pump energy storage circulation loop, a fused salt loop and an energy release water/steam loop; The heat pump energy storage circulation loop sequentially comprises a low-temperature heat source heat exchanger, a low-temperature side of a heat regenerator, a compressor, a molten salt heat exchanger, a high-temperature side of the heat regenerator and an expander which are connected through pipelines along the flow direction of working media, and forms closed circulation; the molten salt loop comprises a high-temperature molten salt tank and a low-temperature molten salt tank, and the high-temperature molten salt tank and the low-temperature molten salt tank are respectively connected with the molten salt heat