Flue gas waste heat utilization system

Abstract

The utility model discloses a flue gas waste heat utilization system which comprises a waste heat boiler, a first heat storage system, a second heat storage system and a power generation system, the first heat storage system absorbs and stores heat energy of a flue gas high-temperature section of the waste heat boiler, and the second heat storage system absorbs and stores heat energy of a flue gas low-temperature section of the waste heat boiler. The high-temperature heat storage medium output end of the first heat storage system is connected with the high-temperature heat storage medium input end of a fourth heat exchange module in the power generation system, and the high-temperature heat storage medium output end of the fourth heat exchange module is connected with the low-temperature heat storage medium input end of the first heat storage system; the high-temperature heat storage medium output end of the second heat storage system is connected with the high-temperature heat storage medium input end of a third heat exchange module in the power generation system, and the low-temperature heat storage medium output end of the third heat exchange module is connected with the low-temperature heat storage medium input end of the second heat storage system. A power generation working medium in the power generation system sequentially passes through the third heat exchange module and the fourth heat exchange module and then enters the power generation device to do work for power generation.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas waste heat utilization, and in particular relates to a flue gas waste heat utilization system. Background Art

[0002] At present, chemical fields such as coking plants and industrial silicon smelters will generate high-temperature flue gas waste heat. For example, the flue gas waste heat of dry coke quenching can reach 950°C, and the flue gas waste heat of industrial silicon can reach about 500°C. At present, this part of the flue gas waste heat is generated by waste heat boilers to generate high-temperature and high-pressure steam, which is directly used for steam turbine power generation system to generate electricity.

[0003] Since the high-temperature steam generated by the waste heat boiler needs to be used immediately to generate electricity or provide heating for users, when users have no electricity or heat demand during a certain period of time, the high-temperature steam output by the waste heat boiler will be difficult to be normally consumed, which can easily lead to waste. Utility Model Content

[0004] In order to solve the above problems, the purpose of the utility model is to provide a flue gas waste heat utilization system, which can improve the utilization rate of the heat energy in the flue gas by absorbing and storing the heat energy in different temperature sections of the flue gas respectively, and can realize the shift of the flue gas heat energy utilization time period, so as to better match the fluctuations of user needs.

[0005] The technical solution provided by the utility model is: a flue gas waste heat utilization system, comprising: a waste heat boiler, comprising a flue gas flow channel and a first heat exchange module and a second heat exchange module sequentially arranged in the flue gas flow channel along the flue gas flow direction;

[0006] a first heat storage system, for absorbing and storing heat energy of the high-temperature section of the flue gas, wherein a low-temperature heat storage medium output end of the first heat storage system is connected to a low-temperature heat storage medium input end of the first heat exchange module via a first pipeline, and a high-temperature heat storage medium output end of the first heat exchange module is connected to a high-temperature heat storage medium input end of the first heat storage system via a second pipeline;

[0007] a second heat storage system, for absorbing and storing heat energy of the low-temperature section of the flue gas, wherein a low-temperature heat storage medium output end of the second heat storage system is connected to a low-temperature heat storage medium input end of the second heat exchange module via a third pipeline, and a high-temperature heat storage medium output end of the second heat exchange module is connected to a high-temperature heat storage medium input end of the second heat storage system via a fourth pipeline;

[0008] A power generation system, comprising a third heat exchange module, a fourth heat exchange module and a power generation device, wherein the power generation medium in the power generation system absorbs heat energy through the third heat exchange module and the fourth module in sequence and then enters the power generation device to perform work and generate electricity;

[0009] The high-temperature heat storage medium output end of the first heat storage system is connected to the high-temperature heat storage medium input end of the fourth heat exchange module through a fifth pipeline, and the high-temperature heat storage medium output end of the fourth heat exchange module is connected to the low-temperature heat storage medium input end of the first heat storage system through a sixth pipeline;

[0010] The high-temperature heat storage medium output end of the second heat storage system is connected to the high-temperature heat storage medium input end of the third heat exchange module through a seventh pipeline, and the low-temperature heat storage medium output end of the third heat exchange module is connected to the low-temperature heat storage medium input end of the second heat storage system through an eighth pipeline.

[0011] Preferably, the first heat storage system includes: a first low-temperature storage tank, used to store a low-temperature heat storage medium; a first high-temperature storage tank, used to store a high-temperature heat storage medium; a first low-temperature pump, used to pump the low-temperature heat storage medium in the first low-temperature storage tank to the low-temperature heat storage medium input end of the first heat exchange module through the first pipeline; a first high-temperature pump, used to pump the high-temperature heat storage medium in the first high-temperature storage tank to the high-temperature heat storage medium input end of the fourth heat exchange module through the fifth pipeline.

[0012] Preferably, the second heat storage system includes: a second low-temperature storage tank for storing a low-temperature heat storage medium; a second high-temperature storage tank for storing a high-temperature heat storage medium; a second low-temperature pump for pumping the low-temperature heat storage medium in the second low-temperature storage tank through the third pipeline to the low-temperature heat storage medium input end of the second heat exchange module; and a second high-temperature pump for pumping the high-temperature heat storage medium in the second high-temperature storage tank through the seventh pipeline to the high-temperature heat storage medium input end of the third heat exchange module.

[0013] Preferably, the first heat storage system is a heat storage system using molten salt as the heat storage medium or a heat storage system using heat transfer oil as the heat storage medium, and the second heat storage system is a heat storage system using water as the heat storage medium.

[0014] Preferably, the power generation medium is water, the power generation device is a steam turbine generator set, the fourth heat exchange module is a steam generator, the water working medium input end of the steam generator is connected to the water working medium output end of the third heat exchange module through a first water working medium pipeline, the steam output end of the steam generator is connected to the steam input end of the steam turbine generator set through a second water working medium pipeline, the steam output end of the steam turbine generator set is connected to the water working medium input end of the third heat exchange module through a third water working medium pipeline, and a condenser is arranged on the third water working medium pipeline.

[0015] Preferably, the third heat exchange module includes a first-stage heat exchanger and a second-stage heat exchanger, the water working medium input end of the first-stage heat exchanger is connected to the water working medium output end of the third water working medium pipeline, the water working medium output end of the first-stage heat exchanger is connected to the water working medium input end of the second-stage heat exchanger, and the water working medium output end of the second-stage heat exchanger is connected to the water working medium input end of the steam generator.

[0016] Preferably, the power generation system also includes a deaerator, a first input end of the deaerator is connected to the water working medium output end of the first-stage heat exchanger, a second input end of the deaerator is connected to the exhaust output end of the steam turbine generator set, and an output end of the deaerator is connected to the water working medium input end of the second-stage heat exchanger.

[0017] Based on the same concept, the utility model also provides a flue gas waste heat utilization system used in factories, and the flue gas waste heat utilization system includes any one of the flue gas waste heat utilization systems described above; the flue gas waste heat utilization system is used to utilize the heat energy in the flue gas discharged from the factory to supply electricity for the factory.

[0018] Due to the adoption of the above technical solution, the utility model has the following advantages and positive effects compared with the prior art:

[0019] 1. The utility model can fully absorb and store the heat energy of different temperature sections in the high-temperature flue gas flowing through the waste heat boiler in sections by setting the first heat storage system and the second heat storage system, thereby realizing the step-by-step utilization of the heat energy in the flue gas, and further realizing the full utilization of the heat energy in the high-temperature flue gas. At the same time, since the second heat storage system and the first heat storage system respectively form two-stage heating of the power generation medium through the third heat exchange module and the fourth heat exchange module, the heat energy stored in the first heat storage system and the second heat storage system can be fully utilized respectively, thereby realizing the full utilization of the heat energy in the flue gas.

[0020] 2. Since the first heat storage system and the second heat storage system can store the thermal energy in the flue gas, it is possible to shift the time period of thermal energy utilization in the flue gas, thereby better matching the fluctuation of user demand. At the same time, due to the existence of the first heat storage system and the second system, even if the flue gas supply stops, the power generation system can still use the thermal energy stored in the first heat storage system and the second heat storage system to maintain the operation of the power generation system.

[0021] 3. Since the city electricity is divided into peak and valley electricity, the waste heat utilization system in the utility model is applied to the factory. When the city electricity is in the valley electricity stage, the valley electricity can be used to maintain the operation of the factory itself, and the first heat storage system and the second heat storage system can be used to store the heat energy in the high-temperature flue gas. When the city electricity is in the peak electricity stage, the heat energy stored in the first heat storage system and the second heat storage system is released to the power generation system to generate electricity to supply the factory's own electricity, thereby reducing the factory's consumption of peak electricity and effectively reducing the factory's operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specific implementation of the utility model is further described in detail below with reference to the accompanying drawings, wherein:

[0023] Figure 1 It is a schematic diagram of the composition of the flue gas waste heat utilization system in the utility model.

[0024] Description of reference numerals:

[0025] 1-flue gas flow duct; 2-second low-temperature storage tank; 3-second high-temperature storage tank; 4-first low-temperature storage tank; 5-first high-temperature storage tank; 601-third pipeline; 6011-second low-temperature pump; 602-seventh pipeline; 6021-second high-temperature pump; 603-eighth pipeline; 604-fourth pipeline; 701-first pipeline; 7011-first low-temperature pump; 702-fifth pipeline; 7021-first high-temperature pump; 703-second pipeline; 704-sixth pipeline; 801-first stage heat exchanger; 802-second stage heat exchanger; 9-fourth heat exchange module; 10-power generation device; 11-condenser; 12-deaerator; 13-first heat exchange module; 14-second heat exchange module; 1301-first water working medium pipeline; 1302-second water working medium pipeline; 1303-third water working medium pipeline. DETAILED DESCRIPTION

[0026] The utility model is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the utility model will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0027] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] First embodiment

[0029] See also Figure 1This embodiment provides a flue gas waste heat utilization system, including:

[0030] The waste heat boiler includes a flue gas flow duct 1 and a first heat exchange module 13 and a second heat exchange module 14 sequentially arranged in the flue gas flow duct 1 along the flue gas flow direction; in this embodiment, the flue gas is input from the upper part of the flue gas flow duct 1 and output from the lower part of the flue gas flow duct 1, and the first heat exchange module 13 is located above the second heat exchange module 14.

[0031] The first heat storage system is used to absorb and store heat energy from the high-temperature section of the flue gas. The low-temperature heat storage medium output end of the first heat storage system is connected to the low-temperature heat storage medium input end of the first heat exchange module 13 through the first pipeline 701, and the high-temperature heat storage medium output end of the first heat exchange module 13 is connected to the high-temperature heat storage medium input end of the first heat storage system through the second pipeline 703;

[0032] The second heat storage system is used to absorb and store the heat energy of the low-temperature section of the flue gas. The low-temperature heat storage medium output end of the second heat storage system is connected to the low-temperature heat storage medium input end of the second heat exchange module 14 through the third pipeline 601, and the high-temperature heat storage medium output end of the second heat exchange module 14 is connected to the high-temperature heat storage medium input end of the second heat storage system through the fourth pipeline 604;

[0033] The power generation system comprises a third heat exchange module, a fourth heat exchange module 9 and a power generation device 10. The power generation medium in the power generation system absorbs heat energy through the third heat exchange module and the fourth module in sequence and then enters the power generation device 10 to generate electricity;

[0034] The high-temperature heat storage medium output end of the first heat storage system is connected to the high-temperature heat storage medium input end of the fourth heat exchange module 9 through the fifth pipeline 702, and the high-temperature heat storage medium output end of the fourth heat exchange module 9 is connected to the low-temperature heat storage medium input end of the first heat storage system through the sixth pipeline 704;

[0035] The high-temperature heat storage medium output end of the second heat storage system is connected to the high-temperature heat storage medium input end of the third heat exchange module through the seventh pipeline 602, and the low-temperature heat storage medium output end of the third heat exchange module is connected to the low-temperature heat storage medium input end of the second heat storage system through the eighth pipeline 603.

[0036] In the technical solution of this embodiment, a first heat storage system and a second heat storage system are provided, which can fully absorb and store the heat energy of different temperature sections in the high-temperature flue gas flowing through the waste heat boiler in sections, thereby realizing the step-by-step utilization of the heat energy in the flue gas, and then realizing the full utilization of the heat energy in the high-temperature flue gas, and improving the utilization rate of energy. At the same time, since the second heat storage system and the first heat storage system respectively form two-stage heating of the power generation medium through the third heat exchange module and the fourth heat exchange module 9, that is, the second heat storage system first preheats the power generation medium, and then performs secondary heating of the power generation medium through the first heat storage system, so that the temperature and pressure of the power generation medium reach the preset requirements. Thereby, the heat energy stored in the first heat storage system and the second heat storage system can be fully utilized respectively, thereby realizing the full utilization of the heat energy in the flue gas.

[0037] In addition, since the first heat storage system and the second heat storage system can store the heat energy in the flue gas, it is possible to achieve a shift in the time period for utilizing the heat energy in the flue gas, thereby being able to better match the fluctuations in user demand. At the same time, due to the existence of the first heat storage system and the second system, even if the flue gas supply stops, the power generation system can still utilize the heat energy stored in the first heat storage system and the second heat storage system to maintain the operation of the power generation system. Since the city electricity is divided into peak and valley electricity, the waste heat utilization system in the utility model is applied to the factory, and the valley electricity can be used to maintain the operation of the factory itself when the city electricity is in the valley electricity stage, and the first heat storage system and the second heat storage system can be used to store the heat energy in the high-temperature flue gas. When the city electricity is in the peak electricity stage, the heat energy stored in the first heat storage system and the second heat storage system is released to the power generation system for power generation to supply the factory's own electricity, thereby reducing the factory's consumption of peak electricity and effectively reducing the factory's operating costs.

[0038] In this embodiment, the first heat storage system includes: a first low-temperature storage tank 4, used to store a low-temperature heat storage medium; a first high-temperature storage tank 5, used to store a high-temperature heat storage medium; a first low-temperature pump 7011, used to pump the low-temperature heat storage medium in the first low-temperature storage tank 4 to the low-temperature heat storage medium input end of the first heat exchange module 13 through the first pipeline 701; a first high-temperature pump 7021, used to pump the high-temperature heat storage medium in the first high-temperature storage tank 5 to the high-temperature heat storage medium input end of the fourth heat exchange module 9 through the fifth pipeline 702.

[0039] The technical solution of this embodiment configures a first low-temperature storage tank 4 and a first high-temperature storage tank 5 in the first heat storage system, which can realize the storage of heat in the high-temperature flue gas, that is, the heat storage medium absorbs the heat energy of the high-temperature flue gas and stores the high-temperature heat storage medium after absorbing the heat energy in the first high-temperature storage tank 5. When necessary, the high-temperature heat storage medium stored in the first high-temperature storage tank 5 is used to heat the power generation medium in the power generation system through the fourth heat exchange module 9 to release energy. In a feasible embodiment, the power generation system can be a steam power generation system, and the high-temperature heat storage medium stored in the first high-temperature storage tank 5 is used to heat and evaporate the power generation medium (i.e., water medium) in the power generation system through the fourth heat exchange module 9 to generate steam that enters the steam turbine unit to generate power, thereby increasing the overall power generation power of the steam power generation system, and when the high-temperature flue gas stops supplying, the high-temperature heat storage medium stored in the first high-temperature storage tank 5 can still be used to supply heat energy to the steam power generation system to maintain the normal operation of the power generation system. Of course, in other embodiments, the power generation system can also be any power generation system in the prior art that is compatible with the waste heat utilization system of the utility model. The high-temperature flue gas in the utility model can come from industrial waste gas or the flue gas discharged from a thermal power plant. The utilization of industrial waste gas can improve the utilization rate of heat energy in the waste gas and realize the translation of the utilization period of flue gas heat energy. The use of flue gas discharged from a thermal power plant can further improve the peak-shaving and valley-filling capabilities of existing thermal power plants. When electricity consumption is low, there is no need to significantly reduce the combustion power of the boiler in the thermal power plant, but the heat energy is stored through the first heat storage system. When electricity consumption is high, there is no need to significantly increase the combustion power of the boiler in the thermal power plant, but the heat energy stored through the first heat storage system is input into the power generation system through the fourth heat exchange module 9 for power generation. In this way, the self-circulating power of the thermal power plant can be relatively stably regulated without significantly adjusting the self-circulating power of the thermal power plant. Of course, in other embodiments, the first heat storage system can also be a storage tank, which includes a first area and a second area separated from each other, wherein the first area is equivalent to the function of the first low-temperature storage tank in this embodiment, and the second area is equivalent to the function of the first high-temperature storage tank in this embodiment.

[0040] In this embodiment, the second heat storage system includes: a second low-temperature storage tank 2, used to store low-temperature heat storage medium; a second high-temperature storage tank 3, used to store high-temperature heat storage medium; a second low-temperature pump 6011, used to pump the low-temperature heat storage medium in the second low-temperature storage tank 2 to the low-temperature heat storage medium input end of the second heat exchange module 14 through the third pipeline 601; a second high-temperature pump 6021, used to pump the high-temperature heat storage medium in the second high-temperature storage tank 3 to the high-temperature heat storage medium input end of the third heat exchange module through the seventh pipeline 602.

[0041] In the technical solution of this embodiment, a second low-temperature storage tank 2 and a second high-temperature storage tank 3 are configured in the second heat storage system, which can realize the storage of heat energy in high-temperature flue gas. In one embodiment, the circulating medium in the second heat storage system can be a water medium, that is, the low-temperature water medium absorbs the heat of the flue gas and is converted into a high-temperature water medium, and the high-temperature water medium is stored in the second high-temperature storage tank 3. When necessary, the high-temperature water medium stored in the second high-temperature storage tank 3 is preheated to the power generation medium in the power generation system through the third heat exchange module, thereby improving the overall power generation power of the power generation system, and when the flue gas supply stops, the high-temperature water medium stored in the second high-temperature storage tank 3 can still be used to supply heat energy to the power generation system to maintain the operation of the power generation system. Of course, the circulating medium in the second heat storage system can also be other heat storage media with heat storage function. The high-temperature flue gas in the utility model can come from industrial waste gas or flue gas discharged from a thermal power plant. The use of industrial waste gas can improve the utilization rate of heat energy in the waste gas and realize the translation of the flue gas heat energy utilization period. By utilizing the flue gas discharged from the thermal power plant, the peak-shaving and valley-filling capabilities of the existing thermal power plant can be further improved. When the power consumption is low, there is no need to significantly reduce the combustion power of the boiler in the thermal power plant, but the heat energy is stored through the second heat storage system. When the power consumption is peak, there is no need to significantly increase the combustion power of the boiler in the thermal power plant, but the heat energy stored through the second heat storage system is input into the power generation system through the third heat exchange module. In this way, the relatively stable regulation of the self-circulating power of the thermal power plant can be achieved without significantly adjusting the self-circulating power of the thermal power plant. In addition, the technical solution of this embodiment uses the heat energy stored in the second heat storage system to preheat the power generation medium, so there is no need to consume other energy to preheat the power generation medium, therefore, the utilization rate of the heat energy in the flue gas is effectively improved, and the consumption of other energy is reduced. Of course, in other embodiments, the second heat storage system can also be a storage tank, which includes a third area and a fourth area separated from each other, wherein the third area is equivalent to the function of the second low-temperature storage tank in this embodiment, and the fourth area is equivalent to the function of the second high-temperature storage tank in this embodiment.

[0042] Specifically, in this embodiment, the first heat storage system is a heat storage system using molten salt as the heat storage medium, and the second heat storage system is a heat storage system using water as the heat storage medium, wherein molten salt refers to a melt of one, two or more salt compounds, and the heat storage performance of the molten salt needs to meet the requirements of the heat storage system for the heat storage temperature range, stability, etc. of the molten salt. Specifically, in this embodiment, the molten salt is a melt of a mixture of sodium nitrate and potassium nitrate, and the water working medium in the second heat storage system is desalted water. Of course, in other embodiments, the first heat storage system can also be a heat storage system using heat transfer oil as the heat storage medium.

[0043] The technical solution of this embodiment configures the first heat storage system and the second heat storage system as heat storage systems with different heat storage capacities. The first heat storage system with higher heat storage capacity is used to absorb and store the heat energy of the high-temperature section of the flue gas, and the second heat storage system with lower heat storage capacity is used to absorb and store the heat energy of the low-temperature section of the flue gas. In addition, the first heat storage system is used as the main heating source of the power generation medium of the power generation system, and the second heat storage system is used as the preheating source of the power generation medium of the power generation system. The configuration of heat energy is more reasonable and the utilization efficiency is higher. Of course, in different embodiments, the heat storage medium in the first heat storage system and the second heat storage system can be any type of heat storage medium in conventional use. The use of conventional heat storage medium should also fall within the inventive concept of the utility model.

[0044] Specifically, in this embodiment, the power generation medium in the power generation system is water medium, the power generation device 10 is a steam turbine generator set, and the fourth heat exchange module 9 is a steam generator (in the steam generator, liquid water medium can be converted into water vapor). The water medium input end of the steam generator is connected to the water medium output end of the third heat exchange module through the first water medium pipeline 1301, and the steam output end of the steam generator is connected to the steam input end of the steam turbine generator set through the second water medium pipeline 1302. The steam output end of the steam turbine generator set is connected to the water medium input end of the third heat exchange module through the third water medium pipeline 1303, and a condenser 11 is arranged on the third water medium pipeline 1303.

[0045] The technical solution of this embodiment uses the first heat storage system as the heat source of the steam generator of the power generation system and the second heat storage system as the heat source of the third heat exchange module of the power generation system, thereby performing secondary heating on the power generation medium in the power generation system and improving the thermal energy utilization rate of the high-temperature flue gas.

[0046] Furthermore, in this embodiment, the third heat exchange module includes a first-stage heat exchanger 801 and a second-stage heat exchanger 802, the water working medium input end of the first-stage heat exchanger 801 is connected to the water working medium output end of the third water working medium pipeline 1303, the water working medium output end of the first-stage heat exchanger 801 is connected to the water working medium input end of the second-stage heat exchanger 802, and the water working medium output end of the second-stage heat exchanger 802 is connected to the water working medium input end of the steam generator.

[0047] The technical solution of this embodiment preferably configures the first-stage heat exchanger 801 and the second-stage heat exchanger 802, which can fully utilize the heat of the water medium in the first heat storage system. The high-temperature water medium first supplies heat to the second-stage heat exchanger 802 and then supplies heat to the first-stage heat exchanger 801, so that the overall heating efficiency is high, the heat energy in the high-temperature water medium is more fully utilized, and the temperature difference between the heating medium and the heated medium is relatively small, which is beneficial to the operation of the heat exchanger, thereby extending the service life of the heat exchanger.

[0048] In this embodiment, the power generation system further includes a deaerator 12, a first input end of the deaerator 12 is connected to the water working medium output end of the first stage heat exchanger 801, a second input end of the deaerator 12 is connected to the exhaust output end of the steam turbine generator set, and an output end of the deaerator 12 is connected to the water working medium input end of the second stage heat exchanger 802. The deaerator 12 is configured in the technical solution of this embodiment to remove oxygen in the power generation working medium to prevent oxygen from corroding and damaging the steam turbine system.

[0049] Based on the same concept, the utility model also provides a flue gas waste heat utilization system used in factories, the flue gas waste heat utilization system includes any one of the above-mentioned flue gas waste heat utilization systems; the flue gas waste heat utilization system is used to utilize the heat energy in the flue gas discharged from the factory to supply the factory with electricity for its own use.

[0050] Since the city electricity is divided into peak and valley electricity, the waste heat utilization system in the utility model is applied to the factory. When the city electricity is in the valley electricity stage, the valley electricity can be used to maintain the operation of the factory itself, and the first heat storage system and the second heat storage system can be used to store the heat energy in the high-temperature flue gas. When the city electricity is in the peak electricity stage, the heat energy stored in the first heat storage system and the second heat storage system is released to the power generation system to generate electricity to supply the factory's own electricity, thereby reducing the factory's consumption of peak electricity and effectively reducing the factory's operating costs.

[0051] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalent technologies, they still fall within the protection scope of the present invention.

Claims

1. A flue gas waste heat utilization system, characterized in that: include: A waste heat boiler comprises a flue gas flow passage and a first heat exchange module and a second heat exchange module sequentially arranged in the flue gas flow passage along a flue gas flow direction; a first heat storage system, for absorbing and storing heat energy of the high-temperature section of the flue gas, wherein a low-temperature heat storage medium output end of the first heat storage system is connected to a low-temperature heat storage medium input end of the first heat exchange module via a first pipeline, and a high-temperature heat storage medium output end of the first heat exchange module is connected to a high-temperature heat storage medium input end of the first heat storage system via a second pipeline; a second heat storage system, for absorbing and storing heat energy of the low-temperature section of the flue gas, wherein a low-temperature heat storage medium output end of the second heat storage system is connected to a low-temperature heat storage medium input end of the second heat exchange module via a third pipeline, and a high-temperature heat storage medium output end of the second heat exchange module is connected to a high-temperature heat storage medium input end of the second heat storage system via a fourth pipeline; A power generation system, comprising a third heat exchange module, a fourth heat exchange module and a power generation device, wherein the power generation medium in the power generation system absorbs heat energy through the third heat exchange module and the fourth module in sequence and then enters the power generation device to perform work and generate electricity; The high-temperature heat storage medium output end of the first heat storage system is connected to the high-temperature heat storage medium input end of the fourth heat exchange module through a fifth pipeline, and the high-temperature heat storage medium output end of the fourth heat exchange module is connected to the low-temperature heat storage medium input end of the first heat storage system through a sixth pipeline; The high-temperature heat storage medium output end of the second heat storage system is connected to the high-temperature heat storage medium input end of the third heat exchange module through a seventh pipeline, and the low-temperature heat storage medium output end of the third heat exchange module is connected to the low-temperature heat storage medium input end of the second heat storage system through an eighth pipeline.

2. The system according to claim 1, characterized in that The first heat storage system comprises: A first low-temperature storage tank, used to store low-temperature heat storage medium; A first high temperature storage tank, used for storing high temperature heat storage medium; a first cryogenic pump, used to pump the cryogenic heat storage medium in the first cryogenic storage tank to the cryogenic heat storage medium input end of the first heat exchange module through the first pipeline; The first high-temperature pump is used to pump the high-temperature heat storage medium in the first high-temperature storage tank to the high-temperature heat storage medium input end of the fourth heat exchange module through the fifth pipeline.

3. The system according to claim 1, characterized in that The second heat storage system comprises: A second low-temperature storage tank, used for storing low-temperature heat storage medium; A second high-temperature storage tank, used for storing high-temperature heat storage medium; a second cryogenic pump, used to pump the cryogenic heat storage medium in the second cryogenic storage tank to the cryogenic heat storage medium input end of the second heat exchange module through the third pipeline; The second high-temperature pump is used to pump the high-temperature heat storage medium in the second high-temperature storage tank to the high-temperature heat storage medium input end of the third heat exchange module through the seventh pipeline.

4. The system according to claim 1, characterized in that The first heat storage system is a heat storage system using molten salt as a heat storage medium or a heat storage system using heat transfer oil as a heat storage medium, and the second heat storage system is a heat storage system using water as a heat storage medium.

5. The system according to any one of claims 1 to 4, characterized in that: The power generation medium is water, the power generation device is a steam turbine generator set, the fourth heat exchange module is a steam generator, the water working medium input end of the steam generator is connected to the water working medium output end of the third heat exchange module through a first water working medium pipeline, the steam output end of the steam generator is connected to the steam input end of the steam turbine generator set through a second water working medium pipeline, the steam output end of the steam turbine generator set is connected to the water working medium input end of the third heat exchange module through a third water working medium pipeline, and a condenser is arranged on the third water working medium pipeline.

6. The system according to claim 5, characterized in that The third heat exchange module includes a first-stage heat exchanger and a second-stage heat exchanger, the water working medium input end of the first-stage heat exchanger is connected to the water working medium output end of the third water working medium pipeline, the water working medium output end of the first-stage heat exchanger is connected to the water working medium input end of the second-stage heat exchanger, and the water working medium output end of the second-stage heat exchanger is connected to the water working medium input end of the steam generator.

7. The system according to claim 6, characterized in that The power generation system also includes a deaerator, a first input end of the deaerator is connected to the water working medium output end of the first stage heat exchanger, a second input end of the deaerator is connected to the exhaust output end of the steam turbine generator set, and an output end of the deaerator is connected to the water working medium input end of the second stage heat exchanger.

8. A flue gas waste heat utilization system used in a factory, characterized in that: The flue gas waste heat utilization system is selected from the flue gas waste heat utilization system according to any one of claims 1 to 7; The flue gas waste heat utilization system is used to utilize the heat energy in the flue gas discharged from the factory to supply the factory with self-use electricity.

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