A power generation system utilizing flue gas compression energy storage

Abstract

The present invention relates to the field of power generation technology, and specifically to a power generation system utilizing flue gas compression energy storage, comprising: a boiler, a steam turbine, a condenser, and a feedwater heater connected in sequence; the steam inlet of the feedwater heater is connected to the steam extraction end of the steam turbine; the flue gas compressor is connected to the flue gas outlet of the boiler and is electrically connected to a generator; the air inlet of a heat storage tank is connected to the flue gas compressor, the water inlet of the heat storage tank is connected to the water outlet of the condenser, and the water outlet of the heat storage tank is connected to the water inlet of the feedwater heater; a heat exchange structure and a heat storage medium are provided in the heat storage tank. The heat storage tank utilizes the flue gas compressed and transported by the flue gas compressor to heat the heat storage medium; and heats the condenser outlet water through the heat exchange structure and transports it to the water inlet of the feedwater heater; the present application utilizes flue gas compression to store heat and energy, utilizes the flue gas compressor to consume the electrical energy of the generator, and the heat storage medium absorbs and stores the heat of the flue gas compression; reduces boiler exhaust loss, improves boiler thermal efficiency, expands the load variation range, and increases the load variation rate.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and in particular to a power generation system utilizing flue gas compression to store energy. Background Art

[0002] With the rapid global increase in renewable energy use, such as solar and wind power, its volatility, intermittency, and unpredictability pose significant challenges to the stable and secure operation of power grids. In the current power system, coal-fired generators have shifted from being the primary power source to supporting the grid in deep peak load regulation. Consequently, coal-fired generators must frequently implement peak load regulation and frequency modulation to ensure the safe and stable operation of the grid. However, the frequency regulation capabilities of coal-fired generators are limited by the significant thermal inertia within the boilers, making it difficult for them to adjust their loads at the required rate to meet the demands of renewable energy integration into the grid. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the variable load rate of coal-fired power generation units is difficult to meet the demand for renewable energy to join the power grid. Based on the above situation, it is very necessary to develop a power generation system that can meet the demand for renewable energy to join the power grid.

[0004] In order to achieve the above objectives, the present invention provides a power generation system utilizing flue gas compression energy storage, comprising:

[0005] A boiler, a steam turbine, a condenser and a feedwater heater are connected in sequence; the steam inlet end of the feedwater heater is connected to the steam extraction end of the steam turbine; the steam turbine is connected to a generator;

[0006] a flue gas compressor connected to the flue gas outlet of the boiler, and the flue gas compressor is electrically connected to the generator;

[0007] A heat storage tank, wherein the air inlet is connected to the flue gas compressor through a first valve, the water inlet of the heat storage tank is connected to the water outlet of the condenser through a fifth valve, and the water outlet of the heat storage tank is connected to the water inlet of the feedwater heater; a heat exchange structure and a heat storage medium are provided in the heat storage tank; and a third valve is provided at the air outlet of the heat storage tank;

[0008] The heat storage tank has an energy storage state in which the flue gas compressed and transported by the flue gas compressor heats the heat storage medium; and has an energy release state in which the outlet water of the condenser is heated through the heat exchange structure and transported to the water inlet of the feedwater heater.

[0009] Optionally, it also includes:

[0010] The pressure-bearing structure is connected to the gas outlet of the heat storage tank through a second valve;

[0011] A flue gas heater is arranged in the boiler, and the air inlet of the flue gas heater is connected to the pressure-bearing structure through a fourth valve, and the air outlet of the flue gas heater is connected to the air inlet of the heat storage tank.

[0012] Optionally, it also includes:

[0013] An air compressor is connected to the pressure-bearing structure, and is suitable for maintaining the pressure in the pressure-bearing structure.

[0014] Optionally, it also includes:

[0015] The flue gas expander is arranged between the air outlet of the flue gas heater and the air inlet of the heat storage tank.

[0016] Optionally, the flue gas entering the flue gas compressor is flue gas that has undergone denitrification and desulfurization.

[0017] Optionally, there are multiple air compressors and multiple flue gas expanders.

[0018] Optionally, the pressure-bearing structure is a pressure tank, a salt cave or a mine cave.

[0019] Optionally, the heat exchange structure is a heat exchange pipeline or a capsule with a heat storage medium installed inside.

[0020] Optionally, the heat storage medium is thermal oil, molten salt, concrete or gravel.

[0021] Optionally, the flue gas heater is arranged in the horizontal flue of the boiler.

[0022] The above technical solution of the present invention has the following advantages over the prior art:

[0023] 1. The power generation system using flue gas compression energy storage provided by the present invention comprises: a boiler, a steam turbine, a condenser and a feedwater heater connected in sequence; the steam inlet end of the feedwater heater is connected to the steam extraction end of the steam turbine; the steam turbine is connected to the generator; a flue gas compressor is connected to the flue gas outlet of the boiler, and the flue gas compressor is electrically connected to the generator; a heat storage tank, the air inlet of which is connected to the flue gas compressor through a first valve, the water inlet of the heat storage tank is connected to the water outlet of the condenser through a fifth valve, and the water outlet of the heat storage tank is connected to the water inlet of the feedwater heater; a heat exchange structure and a heat storage medium are provided in the heat storage tank; a third valve is provided at the air outlet of the heat storage tank Three valves; the heat storage tank has an energy storage state, where the flue gas compressed and delivered by the flue gas compressor heats the heat storage medium; and an energy release state, where the heat exchange structure heats the condenser outlet water and delivers it to the water inlet of the feedwater heater. This application adopts the above technical solution, introducing external energy storage to utilize flue gas waste heat across time and space, overcoming the thermal inertia within the boiler. Heat storage is achieved through flue gas compression, using the flue gas compressor to consume the generator's electricity, while the heat storage medium absorbs and stores the excess heat generated during the flue gas compression process. This improves energy utilization efficiency during deep peak regulation, effectively reducing boiler exhaust losses by more than 50%, and improving the boiler's thermal efficiency. During the flue gas compression energy release process, the heat storage tank integrates the heat storage medium and the heat exchange structure, achieving dual functions of heat exchange and heat storage, making system modification simple. Heat storage and release occur simultaneously, ensuring flexible system operation. The heat storage tank releases energy, raising the feedwater temperature of the feedwater heater, reducing the amount of steam extracted into the feedwater heater, increasing the flow rate of the turbine, improving the turbine's output power, expanding the load variation range, and increasing the load change rate. The minimum load can be reduced to a maximum of 0MW, and the load change rate can be increased from the traditional 1-1.5%Pe0 / min to 2.65%Pe0 / min, greatly improving the flexibility of the power generation system operation and fully meeting the needs of renewable energy joining the power grid.

[0024] 2. The power generation system utilizing flue gas compression energy storage provided by the present invention further includes: a pressure-bearing structure connected to the air outlet of the heat storage tank via a second valve; a flue gas heater disposed within the boiler, with the air inlet of the flue gas heater connected to the pressure-bearing structure via a fourth valve, and the air outlet of the flue gas heater connected to the air inlet of the heat storage tank. This application adopts the above technical solution to further enhance the energy storage capacity and level through the pressure-bearing structure. Specifically, when flue gas is filled into the pressure-bearing structure, the flue gas pressure within the pressure-bearing structure is brought to storage conditions by a flue gas compressor. The compressed flue gas is then heated by the flue gas heater to increase its temperature. The heated flue gas is then returned to the heat storage tank, further enhancing the energy storage capacity and level of the heat storage tank.

[0025] 3. The power generation system using flue gas compression to store energy provided by the present invention also includes: an air compressor connected to the pressure-bearing structure, and the air compressor is suitable for maintaining the pressure inside the pressure-bearing structure; this application adopts the above technical solution, and when the pressure-bearing structure releases flue gas, the air compressor is used to ensure that the pressure inside the pressure-bearing structure remains unchanged.

[0026] 4. The power generation system using flue gas compression energy storage provided by the present invention also includes: a flue gas expander, which is arranged between the air outlet of the flue gas heater and the air inlet of the heat storage tank; this application adopts the above technical solution to make full use of high-temperature and high-pressure flue gas to drive the flue gas expander to do work, thereby improving energy utilization efficiency.

[0027] 5. The flue gas entering the flue gas compressor of the present invention is the flue gas that has undergone denitrification and desulfurization; this application adopts the above technical solution, and the flue gas that has undergone denitrification and desulfurization has a higher temperature; the high-temperature flue gas is fully utilized to store and release energy, reduce the exhaust loss of the boiler, and improve the thermal efficiency of the boiler; at the same time, it prevents the flue gas finally discharged from polluting the environment.

[0028] 6. The number of air compressors described in the present invention is multiple, and the number of flue gas expanders is multiple; this application adopts the above technical solution, by setting up multiple air compressors, the pressure level in the pressure-bearing structure is quickly increased; by setting up multiple flue gas expanders, the work efficiency of the flue gas is improved.

[0029] 7. The pressure-bearing structure described in the present invention is a pressure tank, a salt cave or a mine cave; this application adopts the above technical solution to limit the various forms of the pressure-bearing structure and reduce the modification cost of the power generation system.

[0030] 8. The heat exchange structure described in the present invention is a heat exchange pipeline or a capsule with a heat storage medium installed inside; this application adopts the above technical solution and specifically defines the heat exchange structure, thereby improving the heat exchange efficiency through the heat exchange pipeline or further improving the energy storage capacity of the heat storage tank through the capsule with a heat storage medium installed inside.

[0031] 9. The heat storage medium described in the present invention is thermal oil, molten salt, concrete or gravel; this application adopts the above technical solution to specifically limit the various forms of heat storage media to reduce the modification cost of the power generation system.

[0032] 10. The flue gas heater described in the present invention is arranged in the horizontal flue of the boiler; this application adopts the above technical solution to fully utilize the waste heat of the boiler flue gas to further heat the flue gas, increase the temperature of the flue gas, and enhance the work capacity or energy storage level. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a schematic diagram of the connection structure of a power generation system utilizing flue gas compression energy storage provided in an embodiment of the present invention;

[0035] Figure 2 A schematic diagram comparing flue gas losses between a power generation system utilizing flue gas compression energy storage and a traditional coal-fired power generation unit provided in an embodiment of the present invention;

[0036] Figure 3 Schematic diagram comparing the load variation rate of a power generation system utilizing flue gas compression energy storage and a traditional coal-fired power generation unit provided in an embodiment of the present invention.

[0037] Description of reference numerals:

[0038] 1. Boiler; 2. Steam turbine; 3. Condenser; 4. Feedwater heater; 5. Flue gas compressor; 6. First valve; 7. Heat storage tank; 8. Second valve; 9. Third valve; 10. Pressure-bearing structure; 11. Fourth valve; 12. Flue gas heater; 13. Flue gas expander; 14. Fifth valve; 15. Air compressor; 16. Sixth valve. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0042] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0043] like Figures 1 to 3 The illustrated embodiment of a power generation system utilizing flue gas compression energy storage is particularly suitable for regulating loads within a range of 20 MW. The power generation system utilizing flue gas compression energy storage specifically comprises: a boiler 1, a steam turbine 2, a condenser 3, and a feedwater heater 4, connected in sequence; a flue gas compressor 5, a heat storage tank 7, a pressure structure 10, a flue gas heater 12, and a flue gas expander 13, connected in sequence; and an air compressor 15 connected to the pressure structure 10. Specifically, the boiler 1 is a coal-fired boiler.

[0044] like Figure 1As shown, the steam inlet of the feedwater heater 4 is connected to the steam extraction port of the steam turbine 2; the water outlet of the feedwater heater 4 is connected to the water inlet of the boiler 1. The steam turbine 2 is connected to a generator, which is connected to the power grid. The flue gas compressor 5 is connected to the flue gas outlet of the boiler 1. The flue gas entering the flue gas compressor 5 is denitrified and desulfurized flue gas. The flue gas compressor 5 is also electrically connected to the generator. The air inlet of the heat storage tank 7 is connected to the flue gas compressor 5 via a first valve 6, which is a regulating valve. The water inlet of the heat storage tank 7 is connected to the water outlet of the condenser 3 via a fifth valve 14, which is a feedwater bypass regulating valve. The water outlet of the heat storage tank 7 is connected to the water inlet of the feedwater heater 4. A heat exchange structure and a heat storage medium are provided within the heat storage tank 7. Specifically, the heat exchange structure is a heat exchange pipeline or a capsule containing a heat storage medium. The heat storage medium can be thermal oil, molten salt, concrete, or gravel. A third valve 9 is provided at the outlet of the heat storage tank 7. This third valve 9 is a regulating valve, adapted to discharge low-temperature, low-pressure flue gas when opened. The heat storage tank 7 has an energy storage state, where the flue gas compressed and delivered by the flue gas compressor 5 heats the heat storage medium; and an energy release state, where the outlet water of the condenser 3 is heated via a heat exchange structure and delivered to the water inlet of the feedwater heater 4. The pressure-bearing structure 10 is connected to the outlet of the heat storage tank 7 via a second valve 8. Specifically, the pressure-bearing structure 10 is a pressure tank, salt cavern, or mine cavern. The pressure within the pressure tank is 50-80 bar. The salt cavern or mine cavern can be an existing cavern or a specially excavated cavern. The second valve 8 is a regulating valve. The flue gas heater 12 is disposed within the horizontal flue of the boiler 1, and its air inlet is connected to the pressure-bearing structure 10 via a fourth valve 11, which is a regulating valve. The flue gas heater 12 has an outlet connected to a flue gas expander 13, and the flue gas temperature entering the flue gas expander 13 is no less than 450°C. The outlet of the flue gas expander 13 is connected to the air inlet of the heat storage tank 7. The air compressor 15 is connected to the pressure-bearing structure 10 via a sixth valve 16, and is adapted to maintain the pressure within the pressure-bearing structure 10. The sixth valve 16 is a regulating valve. Furthermore, there may be multiple air compressors 15 and multiple flue gas expanders 13.

[0045] The main working process of the power generation system using flue gas compression energy storage described in this application is briefly described as follows:

[0046] When the coal-fired power generation unit requires deep peak shaving, the flue gas compressor 5 is started to compress the flue gas to above 50 bar. The first valve 6 and the second valve 8 are opened, and the third valve 9 is closed. The compressed flue gas enters the heat storage tank 7, heating the heat storage medium. The flue gas then enters the pressure-bearing structure 10. By adjusting the power of the flue gas compressor 5, the pressure of the compressed flue gas in the pressure-bearing structure 10 is adjusted so that the outlet pressure of the pressure-bearing structure 10 meets the storage conditions. When the flue gas pressure in the pressure-bearing structure 10 reaches the maximum pressure, the first valve 6 and the second valve 8 are closed. The above operations complete the energy storage process.

[0047] When energy is released, the fourth valve 11 is opened, the air compressor 15 is started, and the sixth valve 16 is opened to pump high-pressure air into the pressure-bearing structure 10. By adjusting the power of the air compressor 15, the flow rate of high-pressure air entering the pressure-bearing structure 10 is controlled to ensure that the pressure of the high-pressure flue gas remains constant during the release process, thereby improving the efficiency of the subsequent flue gas expander 13. The high-pressure flue gas released from the pressure-bearing structure 10 enters the flue gas heater 12. After being heated in the boiler 1, it enters the flue gas expander 13 to perform work. The work-performing flue gas enters the heat storage tank 7. After the remaining flue gas heat is used to heat the heat storage medium, the third valve 9 is opened to allow the low-temperature, low-pressure flue gas to enter the environment. The fifth valve 14 is then opened to divert some of the feedwater from the condenser 3 into the heat storage tank 7, where it absorbs the energy of the heat storage medium. The heated, high-temperature feedwater then flows back to the feedwater inlet of the feedwater heater 4. The increased feedwater temperature entering the feedwater heater 4 reduces the amount of steam extracted, increasing the flow rate of the steam turbine 2 and boosting its output power. The opening of the fifth valve 14 is used to adjust the water flow rate entering the heat storage tank 7 so that the water can take away the heat stored in the heat storage tank 7, so that the heat storage medium in the heat storage tank 7 can absorb more flue gas heat.

[0048] like Figure 2 As shown, taking a 660MW ultra-supercritical coal-fired power generation unit as an example, after adopting the power generation system using flue gas compression energy storage as described in this application, when the deep peak regulation is to 20% THA, the flue gas loss is reduced from 27MW to 12.7MW.

[0049] like Figure 3 As shown, taking a 660MW ultra-supercritical coal-fired power generation unit as an example, after adopting the power generation system using flue gas compression energy storage described in this application, the load change rate of the coal-fired power generation unit is increased from the original 1.5% rated load per minute to 2.65% rated load per minute. The load change rate is defined as the change in the unit output power per unit time, and the power change can be expressed as a percentage of the rated load. Assuming the rated load is Pe0, Figure 3 In the diagram, the unit of the vertical axis is %Pe0 / min, i.e. % rated load per minute.

[0050] Therefore, after adopting the power generation system using flue gas compression energy storage as described in this application, the smoke exhaust loss of the coal-fired power generation unit is greatly reduced and the peak-shaving capacity is greatly improved.

[0051] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications derived therefrom remain within the scope of protection of the present invention.

Claims

1. A power generation system utilizing flue gas compression energy storage, characterized in that: include: A boiler (1), a steam turbine (2), a condenser (3), and a feedwater heater (4) are connected in sequence; the steam inlet end of the feedwater heater (4) is connected to the steam extraction end of the steam turbine (2); and the steam turbine (2) is connected to a generator; A flue gas compressor (5) is connected to the flue gas outlet of the boiler (1), and the flue gas compressor (5) is electrically connected to the generator; A heat storage tank (7), the air inlet of which is connected to the flue gas compressor (5) via a first valve (6), the water inlet of the heat storage tank (7) is connected to the water outlet of the condenser (3) via a fifth valve (14), and the water outlet of the heat storage tank (7) is connected to the water inlet of the feedwater heater (4); a heat exchange structure and a heat storage medium are provided in the heat storage tank (7); and a third valve (9) is provided at the air outlet of the heat storage tank (7); The heat storage tank (7) has an energy storage state in which the flue gas compressed and transported by the flue gas compressor (5) heats the heat storage medium; and has an energy release state in which the outlet water of the condenser (3) is heated through the heat exchange structure and transported to the water inlet of the feed water heater (4); Also includes: The pressure-bearing structure (10) is connected to the gas outlet of the heat storage tank (7) via the second valve (8); A flue gas heater (12) is provided in the boiler (1), and an air inlet of the flue gas heater (12) is connected to the pressure-bearing structure (10) via a fourth valve (11), and an air outlet of the flue gas heater (12) is connected to an air inlet of the heat storage tank (7).

2. The power generation system utilizing flue gas compression energy storage according to claim 1 is characterized in that: Also includes: An air compressor (15) is connected to the pressure-bearing structure (10), and the air compressor (15) is suitable for maintaining the pressure in the pressure-bearing structure (10).

3. The power generation system utilizing flue gas compression energy storage according to claim 2 is characterized in that: Also includes: The flue gas expander (13) is arranged between the air outlet of the flue gas heater (12) and the air inlet of the heat storage tank (7).

4. The power generation system utilizing flue gas compression energy storage according to any one of claims 1 to 3, characterized in that: The flue gas entering the flue gas compressor (5) is flue gas that has been denitrified and desulfurized.

5. The power generation system utilizing flue gas compression energy storage according to claim 3 is characterized in that: There are multiple air compressors (15), and there are multiple flue gas expanders (13).

6. The power generation system utilizing flue gas compression energy storage according to any one of claims 1 to 3, characterized in that: The pressure-bearing structure (10) is a pressure tank, a salt cave or a mine cave.

7. The power generation system utilizing flue gas compression energy storage according to claim 6, characterized in that: The heat exchange structure is a heat exchange pipeline or a capsule with a heat storage medium installed inside.

8. The power generation system utilizing flue gas compression energy storage according to claim 7, characterized in that: The heat storage medium is thermal oil, molten salt, concrete or gravel.

9. The power generation system utilizing flue gas compression energy storage according to any one of claims 1 to 3, characterized in that: The flue gas heater (12) is arranged in the horizontal flue of the boiler (1).

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