Peak shaving and capacity increasing system suitable for supercritical parameter unit

Abstract

The utility model discloses a peak regulation and capacity increase system suitable for a supercritical unit, which is characterized in that excessive heat energy and electric energy are stored in fused salt through organic fusion of a steam-fused salt energy storage technology and an electric heating fused salt energy storage technology in the off-peak period of a power grid, and the generated output of a thermal power generating unit is reduced; and in the peak period of the power grid, the stored high-temperature fused salt is used for generating supercritical parameter steam, and the supercritical parameter steam and steam generated by the boiler enter the steam turbine together to do work through expansion, so that the power generation power of the unit is improved. The bidirectional load regulation of the supercritical thermal generator set is realized, and the flexibility of the set is greatly improved. The system disclosed by the utility model not only can reduce the power generation output of the unit in a low-load stage, but also can increase the peak capacity of the unit in a high-load stage, has double effects of downward peak regulation and upward capacity increase, is an important regulation technology for a future high-capacity thermal power generating unit, particularly a supercritical unit, and has a wide application prospect. The method plays an important role in construction of a novel power system.

Description

Technical Field

[0001] The utility model relates to a peak shaving and capacity increasing system applicable to supercritical parameter units, and belongs to the regulation technology for enhancing the flexibility of traditional thermal power units under the construction of a new power system. Background Technique

[0002] The installed capacities of wind power and photovoltaic power in China have been continuously increasing. According to the data statistics of the National Energy Administration, by the end of 2023, the total installed power generation capacity in China reached 2.919 billion kilowatts. Among them, the installed capacity of thermal power was 1.39 billion kilowatts, accounting for about 47.6%. The cumulative installed capacity of photovoltaic power generation was 609 million kilowatts, the cumulative installed capacity of wind power reached 441 million kilowatts, and the cumulative installed capacity of "photovoltaic + wind power" reached 1.051 billion kilowatts, and the proportion of the two in the total installed capacity was 36%.

[0003] Under the background of the "dual carbon" strategy, the proportion of new energy installed capacity represented by solar energy and wind energy has been increasing year by year, which is a typical feature of the new power system. Due to the fact that the power generation power of solar energy and wind energy is severely affected by resources, the high proportion of new energy structure brings unprecedented challenges to the safety of the power system.

[0004] There are various ways to solve the security of the new power system. Using energy storage technology to enhance the regulation characteristics of the power grid and achieve the balance of electricity quantity and power is an important way. By the end of 2023, the cumulative installed capacity of new energy storage in China has exceeded 30 million kilowatts, and the installed capacity of pumped storage has exceeded 50 million kilowatts, and the cumulative capacity of the two has exceeded 80 million kilowatts.

[0005] In addition to the above energy storage technology, the new power system also puts forward higher requirements for the flexibility of traditional thermal power units. Calculated according to the aforementioned installed capacity, if the regulation ability of thermal power units is increased by 10%, the regulation ability of the power grid will increase by 139 million kilowatts. Traditional thermal power units have a certain variable load capacity. Taking a coal-fired power unit with condensing power generation as an example, the on-grid power of the unit can usually be adjusted to 40%-50% of the rated power for operation. For a cogeneration unit or a pure condensing unit, if the load regulation ability is to be improved, multiple types of flexibility technologies must be adopted. Currently, the commonly used methods include: low-load stable combustion technology, wide-load denitration technology, steam turbine flow path and extraction steam transformation, etc. The transformation costs of the above technical paths are usually relatively high, and the main equipment such as boilers and steam turbines operate at low loads for a long time, which will not only reduce the power generation efficiency, but also cause damage to the equipment life, and even lead to safety accidents.

[0006] The present utility model is proposed under the above background. By organically integrating steam - molten salt energy storage and electro - thermal energy storage technologies, the load regulation ability of thermal power generating units, especially supercritical units, is improved. This technology can not only increase the peak - shaving depth of the unit at low loads but also increase the power generation of the unit during peak periods. Currently, supercritical thermal power generating units are the main models of the power grid, and this technology is of far - reaching significance for the construction of China's new power system. Summary of the Utility Model

[0007] To solve the above - mentioned technical problems, the present utility model designs a peak - shaving and capacity - increasing system applicable to supercritical parameter units.

[0008] The present utility model adopts the following technical solutions:

[0009] A peak - shaving and capacity - increasing system applicable to supercritical parameter units, characterized in that it includes an energy storage mode and a heat - release capacity - increasing mode;

[0010] The energy storage mode includes: a cold salt tank, a hot salt tank, a cold salt pump, a boiler, a steam turbine, a generator, a main transformer, a high - pressure feed - water system, a steam - molten salt heating system, a molten salt electro - thermal device, and a high - pressure return water pump; the cold salt tank, the hot salt tank, the cold salt pump, the steam - molten salt heating system, and the molten salt electro - thermal device form the molten salt system in the energy storage mode, and the boiler, the steam turbine, the generator, the main transformer, the high - pressure feed - water system, the steam - molten salt heating system, the molten salt electro - thermal device, and the high - pressure return water pump form the steam / water system in the heat - storage mode;

[0011] During low - load periods when peak - shaving is required, a part of the steam coming out of the boiler goes to the steam turbine to do work and generate electricity, and another part enters the steam - molten salt heating system to transfer heat to the molten salt. The steam is gradually condensed in this process and enters the high - pressure feed - water system through the high - pressure return water pump, mixes with the water coming out of the high - pressure feed - water system and enters the boiler, and successively completes the processes of heating up, evaporation, and superheating, thus completing a cycle of the steam / water system in the heat - storage mode;

[0012] The cold molten salt is pumped out of the cold salt tank, enters the steam - molten salt heating system to complete the first - stage temperature rise, and then enters the molten salt electro - heating device to complete the second - stage temperature rise. When the temperature of the molten salt reaches the set temperature, it enters the high - temperature molten salt tank, thus completing a cycle of the molten salt system in the heat - storage mode;

[0013] The exothermic capacity expansion mode includes: a cold salt tank, a hot salt tank, a hot salt pump, a boiler, a steam turbine, a generator, a main transformer, a high-pressure water supply system, a molten salt-steam preheating evaporation system, a steam-water separation device, and a molten salt-steam superheater; the cold salt tank, the hot salt tank, the hot salt pump, the molten salt-steam preheating evaporation system, and the molten salt-steam superheater constitute a molten salt system in the exothermic capacity expansion mode; the boiler, the steam turbine, the generator, the main transformer, the high-pressure water supply system, the molten salt-steam preheating evaporation system, the steam-water separation device, and the molten salt-steam superheater constitute a steam / water system in the exothermic capacity expansion mode;

[0014] During the peak load period, the water from the high-pressure water supply system enters the supercritical boiler, where it completes the preheating, evaporation and superheating processes; the other way enters the molten salt-steam preheating evaporation system, the steam-water separation device and the molten salt-steam superheater in sequence. The steam parameters generated are consistent with the main steam parameters at the boiler outlet. The two are combined and enter the steam turbine to drive the generator to generate electricity, and then the main transformer is boosted and connected to the power grid;

[0015] The hot molten salt is extracted from the hot salt tank and enters the molten salt-steam superheater and the molten salt-steam preheating evaporation system in turn, releasing the heat to the steam-water system and returning to the cold salt tank after the temperature is lowered, completing a cycle of the molten salt system in the heat release mode.

[0016] Preferably, the electric energy of the molten salt electric heating device comes from the output terminal of the generator, and the connection point is located before the main transformer.

[0017] Preferably, the steam / water system in the energy storage mode and the heat release capacity expansion mode uses water and water vapor as the working medium.

[0018] Preferably, in the exothermic capacity expansion mode, the high-temperature water of the molten salt-steam preheating evaporation system comes from between the high-pressure heating system and the boiler.

[0019] Preferably, water of the high-pressure water supply system is input from a water inlet through a water supply pump.

[0020] The beneficial effects of the present utility model are as follows: (1) By organically integrating the steam-molten salt energy storage technology and the electrothermal molten salt energy storage technology during the low grid load period, the present utility model stores the excess heat energy and electrical energy in the molten salt, reducing the power output of the thermal power unit. During the high grid load period, the stored high-temperature molten salt is used to generate supercritical parameter steam, which enters the steam turbine together with the steam generated by the boiler to expand and do work, thereby increasing the power generation of the unit. The two-way load regulation of the supercritical thermal power unit is realized, greatly improving the flexibility of the unit. (2) The present utility model can reduce the power output of the unit during the low load stage and increase the peak shaving capacity of the unit during the high load period. It has the dual effects of downward peak shaving and upward capacity increase. It is an important regulation technology for future large-capacity thermal power units, especially supercritical units, and will play an important role in the construction of a new power system. Brief Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the present utility model in the energy storage mode;

[0022] Figure 2 It is a schematic structural diagram of the present utility model in the heat release and capacity increase mode;

[0023] In the figure: 1, cold salt tank; 2, hot salt tank; 3, cold salt pump; 4, boiler; 5, steam turbine; 6, generator; 7, main transformer; 8, feed water pump; 9, high-pressure feed water system; 10, steam-molten salt heating system; 11, molten salt electrothermal device; 12, high-pressure return water pump; 13, hot salt pump; 14, molten salt-steam preheating and evaporation system; 15, molten salt-steam superheater; 16, steam-water separation device. Detailed Embodiments

[0024] The technical solution of the present utility model will be further specifically described below through specific embodiments in combination with the drawings:

[0025] Embodiment: As Figure 1 shown, a peak shaving and capacity increase system applicable to a supercritical unit mainly includes, in the energy storage mode: a cold salt tank 1, a hot salt tank 2, a cold salt pump 3, a boiler 4, a steam turbine 5, a generator 6, a main transformer 7, a feed water pump 8, a high-pressure feed water system 9, a steam-molten salt heating system 10, a molten salt electrothermal device 11, and a high-pressure return water pump 12.

[0026] During the low load period when peak shaving is required, a part of the steam coming out of the boiler goes to the steam turbine to do work and generate electricity, and the other part enters the steam-molten salt heating system to transfer heat to the molten salt. The steam is gradually condensed during this process and enters the feed water system through the high-pressure return water pump, mixes with the water coming out of the high-pressure feed water system, and then enters the boiler to complete the processes of heating, evaporation, superheating, etc. in sequence, completing a primary cycle of the steam / water system in the heat storage mode.

[0027] The cold molten salt is drawn out from the cold salt tank, enters the steam-molten salt heating system to complete the first-order heating, and then enters the molten salt electric heating device to complete the second-order heating. The electric energy of the molten salt electric heating device comes from the output terminal of the generator. The connection point is usually located before the main transformer. When the temperature of the molten salt reaches the set temperature, it enters the high-temperature molten salt tank, completing a cycle of the molten salt system in the heat storage mode.

[0028] In the energy storage mode, the system completes the first-order energy storage through the steam-molten salt heating system, and then completes the second-order energy storage through the molten salt electric heating device. This can store and consume more heat and electricity, improve the downward regulation ability of the unit during low-load periods, and also improve the molten salt parameters, making preparations for the peak and capacity expansion of the system during peak periods.

[0029] like Figure 2 As shown, a peak load regulation and capacity expansion system suitable for supercritical units mainly includes: a cold salt tank, a hot salt tank, a hot salt pump 13, a boiler, a steam turbine, a generator, a main transformer, a feed water pump, a high-pressure feed water system, a molten salt-steam preheating evaporation system 14, a steam-water separation device 16, and a molten salt-steam superheater 15 in the heat release mode.

[0030] During peak load periods, the feed water from the high-pressure water feed system goes one way to the supercritical boiler, where it completes the preheating, evaporation and superheating processes; the other way enters the molten salt-steam preheating evaporation system, the steam-water separation device and the molten salt-steam superheater in sequence. The steam parameters generated are consistent with the main steam parameters at the boiler outlet. The two are then combined and enter the steam turbine to drive the generator to generate electricity, which is then boosted by the main transformer and connected to the power grid.

[0031] The hot molten salt is extracted from the hot salt tank and enters the molten salt-steam superheater and the molten salt-steam preheating evaporation system in turn, releasing the heat to the steam-water system and returning to the cold salt tank after the temperature is lowered, completing a cycle of the molten salt system in the heat release mode.

[0032] In the exothermic mode, steam with supercritical parameters is generated by high-temperature molten salt, which is consistent with the main steam generated by the boiler. The two are combined and enter the steam turbine to generate power, thereby increasing the steam inlet flow rate of the turbine, improving the power generation capacity of the unit, and enhancing the peak capacity of the supercritical unit during peak hours.

[0033] According to the needs, a peak load regulation and capacity expansion system suitable for supercritical units can have the following changes without changing the essence of the utility model:

[0034] In the steam power system of the present utility model, water and steam are used as the working medium. Water and steam are the most commonly used working fluids in current thermal power generating units. Other types of media such as carbon dioxide, air, helium, and organic working fluids can also be used according to needs. The system will be reconstructed to a certain extent according to the characteristics of different working fluids.

[0035] The present utility model expounds the relevant technologies with a supercritical unit, and the relevant technologies are also applicable to units with other parameters. To adapt to the characteristics of supercritical units, a steam-water separation device is set in the molten salt heat release mode of the present utility model to meet the start-stop and operation requirements of the system. For units with other parameters, the above functions can be achieved by setting devices such as steam drums.

[0036] In the energy storage mode of the present utility model, the high-temperature water coming out of the steam-molten salt heating system returns between the high-pressure feed water system and the boiler. According to needs, the position of the system return water point can also be between the high-pressure feed water system and the feed water pump, or inside the high-pressure feed water system (the high-pressure feed water system includes multiple heaters, and the return water point is arranged between different heaters).

[0037] In the heat release mode of the present utility model, the high-temperature water of the molten salt-steam preheating and evaporation system comes from between the high-pressure heating system and the boiler. According to the needs of the system, the position of the water intake point can also be between the high-pressure feed water system and the feed water pump, or inside the high-pressure feed water system (arranged between different high-pressure heaters).

[0038] In the heat storage mode of the present utility model, the electric energy of the molten salt electric heating device preferably comes from the outgoing line end of the unit generator, that is, the low-voltage side of the unit main transformer. This scheme has the advantages of low voltage level and low investment cost. The system can also come from the high-voltage side of the transformer or the power grid according to needs.

[0039] The system described in the present utility model can not only reduce the power generation output of the unit in the low-load stage, but also increase the peak capacity of the unit in the high-load period. It has the dual effects of downward peak shaving and upward capacity increase. It is an important regulation technology for future large-capacity thermal power units, especially supercritical units, and will play an important role in the construction of a new power system.

[0040] The above-described embodiments are only a preferred solution of the present utility model, and do not impose any form of limitation on the present utility model. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A peak shaving and capacity increasing system applicable to supercritical parameter units, characterized in that, It includes energy storage mode and heat release capacity expansion mode; The energy storage mode includes: a cold salt tank, a hot salt tank, a cold salt pump, a boiler, a steam turbine, a generator, a main transformer, a high-pressure water supply system, a steam-molten salt heating system, a molten salt electric heating device, and a high-pressure return water pump; the cold salt tank, the hot salt tank, the cold salt pump, the steam-molten salt heating system, and the molten salt electric heating device constitute the molten salt system in the energy storage mode, and the boiler, the steam turbine, the generator, the main transformer, the high-pressure water supply system, the steam-molten salt heating system, the molten salt electric heating device, and the high-pressure return water pump constitute the steam / water system in the heat storage mode; During low-load periods when peak load regulation is required, part of the steam from the boiler goes to the steam turbine to generate power, and the other part enters the steam-molten salt heating system to transfer heat to the molten salt. The steam is gradually condensed in this process and enters the high-pressure feed water system through the high-pressure return water pump. It is mixed with the water from the high-pressure feed water system and enters the boiler, completing the process of heating, evaporation, and superheating in sequence, completing a cycle of the steam / water system in the heat storage mode. The cold molten salt is extracted from the cold salt tank, enters the steam-molten salt heating system to complete the first-order heating, and then enters the molten salt electric heating device to complete the second-order heating. When the temperature of the molten salt reaches the set temperature, it enters the high-temperature molten salt tank, completing a cycle of the molten salt system in the heat storage mode; The exothermic capacity expansion mode includes: a cold salt tank, a hot salt tank, a hot salt pump, a boiler, a steam turbine, a generator, a main transformer, a high-pressure water supply system, a molten salt-steam preheating evaporation system, a steam-water separation device, and a molten salt-steam superheater; the cold salt tank, the hot salt tank, the hot salt pump, the molten salt-steam preheating evaporation system, and the molten salt-steam superheater constitute a molten salt system in the exothermic capacity expansion mode; the boiler, the steam turbine, the generator, the main transformer, the high-pressure water supply system, the molten salt-steam preheating evaporation system, the steam-water separation device, and the molten salt-steam superheater constitute a steam / water system in the exothermic capacity expansion mode; During the peak load period, the water from the high-pressure water supply system enters the supercritical boiler, where it completes the preheating, evaporation and superheating processes; the other way enters the molten salt-steam preheating evaporation system, the steam-water separation device and the molten salt-steam superheater in sequence. The steam parameters generated are consistent with the main steam parameters at the boiler outlet. The two are combined and enter the steam turbine to drive the generator to generate electricity, and then the main transformer is boosted and connected to the power grid; The hot molten salt is extracted from the hot salt tank and enters the molten salt-steam superheater and the molten salt-steam preheating evaporation system in turn, releasing the heat to the steam-water system and returning to the cold salt tank after the temperature is lowered, completing a cycle of the molten salt system in the heat release mode.

2. The peak shaving and capacity increasing system for supercritical parameter units according to claim 1, characterized in that, The electric energy of the molten salt electric heating device comes from the outlet terminal of the generator, and the connection point is located before the main transformer.

3. A peak shaving and capacity increasing system applicable to a supercritical parameter unit according to claim 1, characterized in that, The steam / water system in the energy storage mode and the heat release capacity expansion mode uses water and water vapor as the working medium.

4. A peak shaving and capacity increasing system applicable to a supercritical parameter unit according to claim 1, characterized in that, In the exothermic capacity expansion mode, the high-temperature water of the molten salt-steam preheating evaporation system comes from between the high-pressure heating system and the boiler.

5. A peak shaving and capacity increasing system applicable to supercritical parameter units according to claim 1, characterized in that, The water of the high-pressure water supply system is input from the water inlet through a water supply pump.

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