A deep peak-shaving system and method for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat

Abstract

This invention discloses a deep peak-shaving system and method for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat. It relates to the field of thermal power generation and includes a gasifier, an ammonia cracking hydrogen production unit, a cooler, a separator, an ammonia storage tank, an ammonia-hydrogen storage system, a peak-shaving burner, and a boiler. This invention utilizes the waste heat of the thermal power boiler to vaporize liquid ammonia into gaseous ammonia. The ammonia cracking hydrogen production unit uses medium- and high-temperature waste heat or electrical energy, along with an ammonia cracking catalyst, to crack a portion of the ammonia gas, producing an ammonia-hydrogen-nitrogen mixture. This mixture is then separated by a separator to obtain an ammonia-hydrogen mixture. The ammonia-hydrogen mixture is mixed with ammonia gas to produce mixtures with different ammonia-hydrogen ratios, which are stored in the ammonia-hydrogen storage tanks. The ammonia-hydrogen ratio used in the burner is adjusted according to different loads to maintain stable combustion. This invention can maintain stable combustion in the burner under low loads, achieving deep peak-shaving of thermal power plants, and can also deeply utilize waste heat from thermal power plants, improving power generation efficiency.

Description

Technical Field

[0001] This invention relates to the field of energy technology, specifically to a deep peak-shaving system and method for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat. Background Technology

[0002] Climate change is one of the major threats to the Earth's environment, with emissions from fossil fuels and carbon dioxide in the atmosphere exacerbating global warming. Currently, the electricity and heat production sector accounts for the largest share of national carbon emissions.

[0003] To reduce carbon emissions from fossil fuels, it is necessary to vigorously develop green new energy sources, including photovoltaics and wind power. However, the volatility, anti-peak-shaving characteristics, and significant forecasting errors of wind power increase the peak-to-valley difference in the power system, placing higher demands on its peak-shaving capabilities. The continuous increase in the capacity of individual thermal power units leads to a wider range between low and high loads, resulting in poorer peak-to-valley power regulation performance. Especially during nighttime peak-shaving, the grid load is lower than the boiler's minimum stable combustion load, causing some energy waste. Therefore, deep peak-shaving is needed to meet the needs of new energy absorption and balance load fluctuations.

[0004] Ammonia, as a new type of carbon-free fuel for energy consumption and storage, has the characteristics of high energy density, low storage and transportation costs, and high safety. Compared with coal, ammonia burns faster, and liquid ammonia has an energy density comparable to that of coal. In order to reduce carbon emissions from thermal power and achieve flexible peak shaving of thermal power, ammonia is used to replace coal for power generation. It is expected to replace coal to achieve deep peak shaving of thermal power. At present, there is an urgent need to achieve deep peak shaving in thermal power plants that blend ammonia.

[0005] Currently, the main technical approach for peak shaving in thermal power plants is to add heat storage and release devices to the thermal power generation system to store the excess steam generated during unit operation, thereby achieving peak shaving. In addition, invention patent application number CN202311703060.5 proposes an ammonia-to-hydrogen device and method based on enhanced combustion and cracking using extraction gas. This method only applies to ammonia cracking for hydrogen production and does not involve peak shaving in thermal power plants. Invention patent application number CN202311541342.X proposes a peak shaving and frequency regulation method using "electrolysis hydrogen production + solid-state hydrogen storage," solving the challenging problems of safe, low-cost, and large-capacity hydrogen storage through magnesium-based solid-state hydrogen storage equipment. Invention patent application number CN202211161931.0 proposes a deep peak shaving device and method for thermal power units based on hydrogen ignition technology, and stores energy in hydrogen through an electrolysis water hydrogen production device, improving the peak shaving capacity of thermal power generators. However, the peak-shaving method of using water electrolysis to produce hydrogen for energy storage places extremely high demands on hydrogen storage equipment, resulting in high storage costs. Furthermore, this method cannot fully utilize waste heat from thermal power plants, thus failing to improve the power generation efficiency of thermal power. Given that ammonia has higher energy density, lower storage and transportation costs, and higher safety compared to hydrogen, it has broader application prospects in the field of thermal power. Achieving deep peak-shaving in ammonia-blended thermal power plants is now urgent. Therefore, there is an urgent need for a deep peak-shaving technology for thermal power plants that combines ammonia cracking for hydrogen production with the utilization of waste heat from thermal power plants. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a deep peak-shaving system and method for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, thereby achieving deep peak-shaving for thermal power plants. This invention utilizes the waste heat of a thermal power boiler to vaporize liquid ammonia into gaseous ammonia. An ammonia cracking hydrogen production unit uses medium-to-high temperature waste heat or electrical energy, along with an ammonia cracking catalyst, to crack a portion of the ammonia gas, producing an ammonia-hydrogen-nitrogen mixture. This mixture is then separated by a separator to obtain an ammonia-hydrogen mixture. The ammonia-hydrogen mixture is mixed with ammonia gas to produce mixtures with different ammonia-hydrogen ratios, which are stored in ammonia-hydrogen storage tanks. The ammonia-hydrogen ratio used in the burner is adjusted according to different loads to maintain stable combustion. This invention can maintain stable combustion in the burner under low loads, achieving deep peak-shaving for thermal power plants, and can also deeply utilize waste heat from thermal power plants, improving power generation efficiency.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A deep peak-shaving method for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, including...

[0009] The vaporizer is equipped with a liquid ammonia inlet and a gaseous ammonia outlet. The gaseous ammonia outlet is connected to the ammonia cracking hydrogen production unit and the ammonia storage tank via a pipeline.

[0010] The ammonia cracking hydrogen production unit utilizes one or more technologies such as high-temperature waste heat from thermal power plants, electric heating, plasma, fuel-rich combustion, and catalysts to crack all or part of ammonia into a mixture of ammonia, nitrogen, and hydrogen. The high-temperature waste heat from the thermal power plants is 150-900℃.

[0011] The ammonia storage tank is connected to the ammonia outlet of the vaporizer at one end to store the ammonia produced by the vaporizer, and connected to the ammonia-hydrogen storage system and the peak-shaving burner at the other end.

[0012] The ammonia-hydrogen storage system stores a mixture of ammonia, nitrogen, and hydrogen produced by an ammonia cracking hydrogen production unit, or a mixture of ammonia and hydrogen after separation and purification, and stores ammonia from an ammonia storage tank, thereby achieving hydrogen storage at a certain ammonia-hydrogen ratio. The ammonia-hydrogen mixture is then piped into a peak-shaving burner.

[0013] Peak-shaving burners utilize a mixture of hydrogen and ammonia gas and preheated air to generate high-temperature flames and active components, igniting one or more combined fuels such as liquid ammonia, gaseous ammonia, and coal to form a stable combustion flame, thereby ensuring stable combustion under low-load conditions of the boiler.

[0014] A boiler is equipped with one or a combination of peak-shaving burners, ammonia burners, ammonia-coal burners, and coal burners, and at least one peak-shaving burner is installed.

[0015] Furthermore, it also includes a cooler and a separator; the cooler is connected to the ammonia cracking hydrogen production unit via a pipeline; the cooler is connected to the separator and the ammonia storage tank via pipelines respectively; the cooler cools the ammonia-nitrogen-hydrogen mixture produced by the ammonia cracking hydrogen production unit by absorbing heat through liquid ammonia vaporization; the separator separates the ammonia-nitrogen-hydrogen mixture into an ammonia-hydrogen mixture, and connects it to the ammonia-hydrogen storage system via a pipeline.

[0016] Furthermore, the vaporizer (1) uses the low-temperature waste heat of thermal power, ambient temperature air or electric heating to vaporize the introduced liquid ammonia; the low-temperature waste heat of thermal power is 50-150℃.

[0017] Furthermore, the ammonia-hydrogen storage system includes a first ammonia-hydrogen storage tank, a second ammonia-hydrogen storage tank, and a third ammonia-hydrogen storage tank; the first ammonia-hydrogen storage tank, the second ammonia-hydrogen storage tank, and the third ammonia-hydrogen storage tank respectively store ammonia-hydrogen mixture in different proportions, from high to low hydrogen-ammonia ratio.

[0018] Furthermore, the peak-shaving burner includes an ammonia-hydrogen burner and an ammonia-hydrogen-coal burner; the ammonia-hydrogen burner and the ammonia-hydrogen-coal burner are burners that use ammonia-hydrogen to stabilize the flame in order to achieve deep peak shaving in the boiler; the ammonia burner, the ammonia-coal burner, and the coal burner are burners that use ammonia, ammonia-coal, and coal respectively for combustion, and have poor flame stability.

[0019] Further, the vaporizer vaporizes the introduced liquid ammonia and then feeds it into an ammonia cracking hydrogen production unit and an ammonia storage tank, respectively. The ammonia cracking hydrogen production unit cracks ammonia to form a mixture of ammonia, nitrogen, and hydrogen, and feeds the cracked mixture into a cooler, or feeds it into an ammonia-hydrogen storage system through a pipeline. The cooler uses liquid ammonia to cool the mixture produced by the ammonia cracking hydrogen production unit, and the cooled mixture is fed into a separator. The vaporized liquid ammonia is then fed into the ammonia storage tank. The separator separates the ammonia and hydrogen from the mixture and feeds the ammonia-hydrogen mixture into the ammonia-hydrogen storage system. The ammonia storage tank feeds ammonia into the ammonia-hydrogen storage system. The ammonia-hydrogen storage system feeds the hydrogen-ammonia mixture into a peak-shaving burner at a certain flow rate according to the peak-shaving depth of the thermal power plant and the boiler power. The peak-shaving burner is installed on the boiler, and the flame it produces maintains stable combustion at low boiler load.

[0020] Furthermore, the peak-shaving burner includes three operating modes: Mode 1, Mode 2, and Mode 3. In Mode 1, the ammonia cracking hydrogen production unit has high power, and the first, second, and third ammonia hydrogen storage tanks have small volumes. When the thermal power plant is at its peak, the ammonia cracking hydrogen production unit, cooler, and separator are shut down, and the gasifier is turned on. The low-temperature waste heat is used to vaporize liquid ammonia to produce ammonia gas, which is then fed into the peak-shaving burner for combustion. When the thermal power plant is at its trough, the gasifier, ammonia cracking hydrogen production unit, cooler, and separator are turned on to produce an ammonia-hydrogen mixture. The ammonia-hydrogen mixture in different proportions is supplied to the peak-shaving burner according to the boiler power to achieve stable combustion at low boiler load.

[0021] Furthermore, in Mode 2, the ammonia cracking hydrogen production unit has a moderate power output, and the first, second, and third ammonia hydrogen storage tanks have moderate volumes. When the thermal power plant is at its peak, the gasifier, ammonia cracking hydrogen production unit, cooler, and separator are turned on to produce an ammonia-hydrogen mixture. This mixture is stored in the first, second, and third ammonia hydrogen storage tanks until they are full. Then, the ammonia cracking hydrogen production unit, cooler, separator, and gasifier are turned off, and the ammonia gas produced by gasifying liquid ammonia using low-temperature waste heat is fed into the peak-shaving burner for combustion. When the thermal power plant is at its trough, the gasifier, ammonia cracking hydrogen production unit, cooler, and separator are turned on to produce an ammonia-hydrogen mixture, which is fed into the first, second, and third ammonia hydrogen storage tanks. The ammonia-hydrogen mixture is supplied to the peak-shaving burner in different proportions according to the boiler power to achieve stable combustion at low boiler load.

[0022] Furthermore, in Mode 3, the ammonia cracking hydrogen production unit has low power, while the first, second, and third ammonia hydrogen storage tanks have the largest volumes. The gasifier, ammonia cracking hydrogen production unit, cooler, and separator operate 24 / 7, producing an ammonia-hydrogen mixture. This mixture is stored in the first, second, and third ammonia hydrogen storage tanks. When the thermal power plant is at its peak, the ammonia gas produced by the gasifier is fed into the peak-shaving burner for combustion. When the thermal power plant is at its trough, the first, second, and third ammonia hydrogen storage tanks supply different proportions of the ammonia-hydrogen mixture to the peak-shaving burner according to the boiler power, achieving stable combustion at low boiler loads.

[0023] Furthermore, the ammonia-hydrogen mixture is stored in a storage tank in a certain proportion to avoid hydrogen embrittlement and reduce the risk of hydrogen storage.

[0024] Furthermore, by absorbing the low-temperature waste heat from thermal power plants with liquid ammonia and then vaporizing it to produce ammonia gas, the waste heat from thermal power plants is utilized in a deeper way, thereby improving the power generation efficiency of thermal power plants.

[0025] Furthermore, the boiler peak shaving includes the following process:

[0026] 1) When the boiler is running at 40-50% or more of its power, the ammonia-hydrogen burner and the ammonia-hydrogen coal burner should operate at minimum power or be shut down. The ammonia burner, the ammonia-coal burner, and the coal burner should operate at appropriate power according to the boiler power requirements.

[0027] 2) When the boiler is running at less than 40-50% of its power, the ammonia-hydrogen burner and the ammonia-hydrogen-coal burner should operate at appropriate power and ammonia-hydrogen ratio to meet the requirements for stable operation of the boiler at low load. The ammonia burner, ammonia-coal burner, and coal burner should operate at appropriate power according to the boiler power requirements.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention utilizes liquid ammonia vaporization to absorb low-temperature waste heat from thermal power plants, thereby improving the power generation efficiency of thermal power. The vaporized ammonia is then introduced into the burner, enhancing combustion stability. Ammonia is cracked to produce hydrogen using an ammonia cracking hydrogen production device. Based on the boiler power, different proportions of hydrogen-ammonia mixture are introduced into the peak-shaving burner to ensure stable combustion of the boiler under low load, thus achieving deep peak shaving of thermal power. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an example of a thermal power deep peak shaving system based on ammonia cracking hydrogen production coupled with deep utilization of waste heat according to the present invention.

[0031] Figure 2 This is a schematic diagram of Example 2 of a thermal power deep peak shaving system based on ammonia cracking hydrogen production coupled with deep utilization of waste heat according to the present invention.

[0032] Figure 3 This is a schematic diagram of the burner type used in a deep peak shaving method for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, according to the present invention.

[0033] In the figure, the attached labels are as follows: 1-gasifier; 2-ammonia cracking hydrogen production unit; 3-cooler; 4-separator; 5-ammonia storage tank; 6-ammonia-hydrogen storage system; 6-1-first ammonia-hydrogen storage tank; 6-2-second ammonia-hydrogen storage tank; 6-3-third ammonia-hydrogen storage tank; 7-peak-shaving burner; 7-1-ammonia-hydrogen burner; 7-2-ammonia-hydrogen coal burner; 8-boiler; 8-1-ammonia burner; 8-2-ammonia-coal burner; 8-3-coal burner. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0035] According to two embodiments of the present invention, such as Figure 1-3 As shown, a deep peak-shaving system for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat is presented.

[0036] It includes a vaporizer 1, which has a liquid ammonia inlet and a gaseous ammonia outlet. The gaseous ammonia outlet is connected to the ammonia cracking hydrogen production unit 2 and the ammonia storage tank 5 through a pipeline.

[0037] Ammonia cracking hydrogen production unit 2 utilizes a combination of technologies including high-temperature waste heat from thermal power plants, plasma, fuel-rich combustion, and catalysts to crack all or part of ammonia into a mixture of ammonia, nitrogen, and hydrogen. The high-temperature waste heat from the thermal power plants is 150-900℃.

[0038] Ammonia storage tank 5 is connected at one end to the ammonia outlet of vaporizer 1 to store ammonia produced by vaporizer 1, and at the other end to ammonia-hydrogen storage system 6 and peak-shaving burner 7 respectively.

[0039] The ammonia-hydrogen storage system 6 stores a mixture of ammonia, nitrogen, and hydrogen produced by the ammonia cracking hydrogen production unit 2 or a mixture of ammonia and hydrogen after separation and purification, and stores ammonia from the ammonia storage tank 5, so as to store hydrogen in a certain ammonia-hydrogen ratio. The ammonia-hydrogen mixture is then introduced into the peak-shaving burner 7 through a pipeline.

[0040] The peak-shaving burner 7 uses a mixture of hydrogen and ammonia and preheated air to generate a high-temperature flame and active components, which ignite liquid ammonia and coal combined fuel to form a stable combustion flame, so as to meet the stable combustion of boiler 8 under low load conditions.

[0041] Boiler 8 is equipped with peak-shaving burner 7, ammonia burner 8-1, and coal burner 8-3.

[0042] It also includes a cooler 3 and a separator 4; the cooler 3 is connected to the ammonia cracking hydrogen production unit 2 via a pipeline; the cooler 3 is connected to the separator 4 and the ammonia storage tank 5 via pipelines respectively; the cooler 3 cools the ammonia-nitrogen-hydrogen mixture produced by the ammonia cracking hydrogen production unit 2 by absorbing heat through liquid ammonia vaporization; the separator 4 separates the ammonia-nitrogen-hydrogen mixture to obtain an ammonia-hydrogen mixture, and connects it to the ammonia-hydrogen storage system 6 via a pipeline.

[0043] The ammonia-hydrogen storage system 6 includes a first ammonia-hydrogen storage tank 6-1, a second ammonia-hydrogen storage tank 6-2, and a third ammonia-hydrogen storage tank 6-3; the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3 respectively store ammonia-hydrogen mixture in different proportions from high to low hydrogen-ammonia ratio.

[0044] The vaporizer 1 utilizes the low-temperature waste heat (50-150℃) of the thermal power plant to vaporize the introduced liquid ammonia, thereby improving the waste heat utilization rate and the total enthalpy of ammonia, and thus improving the power generation efficiency of the thermal power plant.

[0045] The ammonia cracking hydrogen production unit 2 utilizes the high-temperature waste heat (150-900℃) from the thermal power plant to preheat ammonia, and then uses plasma-assisted ammonia-rich combustion, combined with the ammonia cracking catalyst to produce a mixture of hydrogen, ammonia, nitrogen and hydrogen, which improves the reactivity and combustion stability of the fuel and ensures that the boiler operates stably at low load without shutting down during deep peak shaving.

[0046] The peak-shaving burner 7 includes an ammonia-hydrogen burner 7-1 and an ammonia-hydrogen-coal burner 7-2. The ammonia-hydrogen burner 7-1 and the ammonia-hydrogen-coal burner 7-2 utilize a hydrogen-ammonia mixture and preheated air to generate a high-temperature flame and active components, igniting the liquid ammonia and coal combined fuel to form a stable combustion flame, thereby achieving stable combustion and safe operation of the boiler 8 under low load. One of the ammonia-hydrogen burner 7-1 or the ammonia-hydrogen-coal burner 7-2 can be selected for use as needed. The ammonia burner 8-1, the ammonia-coal burner 8-2, and the coal burner 8-3 are burners that utilize ammonia, ammonia-coal, and coal combustion respectively, and have relatively poor flame stability.

[0047] The vaporizer 1 vaporizes the introduced liquid ammonia and then feeds it into the ammonia cracking hydrogen production unit 2 and the ammonia storage tank 5, respectively. The ammonia cracking hydrogen production unit 2 cracks the ammonia to form a mixture of ammonia, nitrogen, and hydrogen, and then feeds the cracked mixture into the cooler 3. The cooler 3 uses liquid ammonia to cool the mixture produced by the ammonia cracking hydrogen production unit 2, and the cooled mixture is fed into the separator 4. The vaporized liquid ammonia is then fed into the ammonia storage tank 5. The separator 4 separates the ammonia and hydrogen from the mixture and feeds the ammonia-hydrogen mixture into the ammonia-hydrogen storage system 6. The ammonia storage tank 5 feeds ammonia into the ammonia-hydrogen storage system 6. The ammonia-hydrogen storage system 6 feeds the hydrogen-ammonia mixture into the peak-shaving burner 7 at a certain flow rate according to the peak-shaving depth of the thermal power plant and the boiler power. The peak-shaving burner 7 is installed on the boiler, and the flame it produces maintains stable combustion of the boiler 8 at low load.

[0048] The peak-shaving burner 7 includes three operating modes: Mode 1, Mode 2, and Mode 3. In Mode 1, the ammonia cracking hydrogen production unit 2 has high power, while the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3 have smaller volumes. When the thermal power plant is at its peak, the ammonia cracking hydrogen production unit 2, the cooler 3, and the separator 4 are shut down, and the gasifier 1 is opened. The liquid ammonia is vaporized using low-temperature waste heat to produce ammonia gas, which is then introduced into the peak-shaving burner 7 for combustion. When the thermal power plant is at its trough, the gasifier 1, the ammonia cracking hydrogen production unit 2, the cooler 3, and the separator 4 are opened to produce an ammonia-hydrogen mixture. The ammonia-hydrogen mixture is supplied to the peak-shaving burner 7 in different proportions according to the boiler power, thereby achieving stable combustion of the boiler at low load.

[0049] In Mode 2, the ammonia cracking hydrogen production unit 2 has a moderate power output, and the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3 have moderate volumes. When the thermal power plant is at its peak, the gasifier 1, the ammonia cracking hydrogen production unit 2, the cooler 3, and the separator 4 are turned on to produce an ammonia-hydrogen mixture. This mixture is stored in the first ammonia-hydrogen storage tank 6, the second ammonia-hydrogen storage tank 7, and the third ammonia-hydrogen storage tank 8 until they are full. After this process, the ammonia cracking hydrogen production unit 2 and the cooler 6-3 are turned off. Units 3, 4, and 1 are used to generate ammonia gas by gasifying liquid ammonia using low-temperature waste heat. This ammonia gas is then fed into peak-shaving burner 7 for combustion. When the thermal power plant is at a low point, units 1, 2, 3, and 4 are turned on to generate ammonia-hydrogen mixture. This mixture is then fed into the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3. The ammonia-hydrogen mixture is supplied to peak-shaving burner 7 in different proportions according to the boiler power, thus achieving stable combustion of the boiler at low load.

[0050] In Mode 3, the ammonia cracking hydrogen production unit 2 operates at low power, while the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3 have large volumes. The gasifier 1, the ammonia cracking hydrogen production unit 2, the cooler 3, and the separator 4 operate continuously, producing an ammonia-hydrogen mixture. This mixture is stored in the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3. When the thermal power plant is at its peak, the ammonia gas produced by the gasifier 1 is fed into the burner 9 for combustion. When the thermal power plant is at its trough, the first ammonia-hydrogen storage tank 6-1, the second ammonia-hydrogen storage tank 6-2, and the third ammonia-hydrogen storage tank 6-3 supply different proportions of the ammonia-hydrogen mixture to the peak-shaving burner 7 according to the boiler power, achieving stable combustion at low boiler loads.

[0051] Ammonia and hydrogen are mixed and stored in a storage tank at a specific ammonia-hydrogen ratio to avoid hydrogen embrittlement and reduce the risks associated with hydrogen storage. Liquid ammonia absorbs the low-temperature waste heat from thermal power plants, and the vaporized ammonia produces ammonia gas, thus making full use of the waste heat and improving the power generation efficiency of thermal power plants.

[0052] The boiler 8 is equipped with an ammonia-hydrogen burner 7-1 and an ammonia-coal burner 8-2. The ammonia-hydrogen burner 7-1 uses ammonia-hydrogen to stabilize the flame and ignite the fuel introduced into the ammonia-coal burner 8-2, thereby achieving deep peak shaving of the boiler. The ammonia-coal burner 8-2 is a burner that uses ammonia-coal combustion and has poor flame stability.

[0053] The peak shaving process of boiler 8 includes the following steps:

[0054] 1. When boiler 8 is running at 40-50% or more of its power, ammonia-hydrogen burner 7-1 stops operating, and ammonia-coal burner 8-2 operates at a suitable power according to the power requirements of boiler 8;

[0055] 2. When boiler 8 is operating at a power level below 40-50%, ammonia-hydrogen burner 7-1 operates at a suitable power and ammonia-hydrogen ratio to meet the requirements of stable operation of boiler 8 at low load, while ammonia-coal burner 8-2 operates at a suitable power according to the power requirements of boiler 8.

Claims

1. A deep peak-shaving system for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, characterized in that, include: The vaporizer (1) is equipped with a liquid ammonia inlet and a gaseous ammonia outlet. The gaseous ammonia outlet is connected to the ammonia cracking hydrogen production unit (2) and the ammonia storage tank (5) through a pipeline. Ammonia cracking hydrogen production unit (2) utilizes one or more technologies such as high-temperature waste heat from thermal power plants, electric heating, plasma, fuel-rich combustion, and catalysts to crack all or part of ammonia into a mixture of ammonia, nitrogen, and hydrogen. The high-temperature waste heat from thermal power plants is 150-900℃. Ammonia storage tank (5) is connected at one end to the ammonia outlet of the vaporizer (1) to store the ammonia gas generated by the vaporizer (1), and at the other end to the ammonia-hydrogen storage system (6) and the peak-shaving burner (7). The ammonia-hydrogen storage system (6) stores ammonia-nitrogen-hydrogen mixture produced by the ammonia cracking hydrogen production unit (2) or ammonia-hydrogen mixture after separation and purification, and stores ammonia from the ammonia storage tank (5) to achieve hydrogen storage in a certain ammonia-hydrogen ratio. The ammonia-hydrogen mixture is then introduced into the peak-shaving burner (7) through a pipeline. The peak-shaving burner (7) uses a mixture of hydrogen and ammonia and preheated air to generate a high-temperature flame and active components to ignite one or more combined fuels such as liquid ammonia, gaseous ammonia, and coal to form a stable combustion flame, so as to meet the stable combustion of the boiler (8) under low load conditions. The boiler (8) is equipped with one or more of the following: peak-shaving burner (7), ammonia burner (8-1), ammonia-coal burner (8-2), and coal burner (8-3), and at least peak-shaving burner (7) is installed.

2. The deep peak-shaving system for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat according to claim 1, characterized in that: It also includes a cooler (3) and a separator (4); the cooler (3) is connected to the ammonia cracking hydrogen production unit (2) through a pipeline; the cooler (3) is connected to the separator (4) and the ammonia storage tank (5) through pipelines respectively; the cooler (3) cools the ammonia-nitrogen-hydrogen mixture produced by the ammonia cracking hydrogen production unit (2) by absorbing heat through liquid ammonia vaporization; the separator (4) separates the ammonia-nitrogen-hydrogen mixture to obtain an ammonia-hydrogen mixture, and connects it to the ammonia-hydrogen storage system (6) through a pipeline.

3. The deep peak-shaving system for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat according to claim 2, characterized in that: The vaporizer (1) uses the low-temperature waste heat of thermal power, ambient air or electric heating to vaporize the introduced liquid ammonia; the low-temperature waste heat of thermal power is 50-150℃.

4. A deep peak-shaving system for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, as described in claim 3, is characterized in that: The ammonia-hydrogen storage system (6) includes a first ammonia-hydrogen storage tank (6-1), a second ammonia-hydrogen storage tank (6-2), and a third ammonia-hydrogen storage tank (6-3); the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3) store ammonia-hydrogen mixture in different proportions, from high to low, respectively.

5. A deep peak-shaving system for thermal power plants based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, as described in claim 4, is characterized in that: The peak-shaving burner (7) includes an ammonia-hydrogen burner (7-1) and an ammonia-hydrogen coal burner (7-2); the ammonia-hydrogen burner (7-1) and the ammonia-hydrogen coal burner (7-2) are burners that use ammonia-hydrogen to stabilize the flame in order to achieve deep peak shaving in the boiler; the ammonia burner (8-1), the ammonia-coal burner (8-2), and the coal burner (8-3) are burners that use ammonia, ammonia-coal, and coal respectively for combustion, and have poor flame stability.

6. The deep peak shaving method for a thermal power plant based on ammonia cracking hydrogen production coupled with deep utilization of waste heat, as described in claim 5, is characterized in that: The vaporizer (1) vaporizes the introduced liquid ammonia and then introduces it into the ammonia cracking hydrogen production unit (2) and the ammonia storage tank (5), respectively. The ammonia cracking hydrogen production unit (2) cracks the ammonia to form a mixture of ammonia, nitrogen, and hydrogen, and introduces the cracked mixture into the cooler (3), or introduces the cracked mixture into the ammonia-hydrogen storage system (6) through a pipeline. The cooler (3) uses liquid ammonia to cool the mixture produced by the ammonia cracking hydrogen production unit (2), and the cooled mixture is introduced into the separator (4). The liquid ammonia after condensation is fed into the ammonia storage tank (5); the separator (4) separates the ammonia and hydrogen in the mixed gas and feeds the ammonia and hydrogen mixed gas into the ammonia and hydrogen storage system (6); the ammonia storage tank (5) feeds ammonia into the ammonia and hydrogen storage system (6); the ammonia and hydrogen storage system (6) feeds the hydrogen and ammonia mixed gas into the peak-shaving burner (7) at a certain flow rate according to the peak-shaving depth of thermal power and the boiler power; the peak-shaving burner (7) is installed on the boiler and the flame generated maintains the boiler (8) under low load and stable combustion.

7. The deep peak-shaving method for thermal power plants according to claim 6, characterized in that: The peak-shaving burner (7) includes three operating modes: mode one, mode two and mode three. In mode one, the ammonia cracking hydrogen production device (2) has high power and the first ammonia hydrogen storage tank (6-1), the second ammonia hydrogen storage tank (6-2) and the third ammonia hydrogen storage tank (6-3) have small volumes. When the thermal power is at its peak, the ammonia cracking hydrogen production device (2), the cooler (3) and the separator (4) are closed, and the gasifier (1) is opened. The liquid ammonia is vaporized using the low-temperature waste heat to produce ammonia gas, which is then introduced into the peak-shaving burner (7) for combustion. When the thermal power is at its trough, the gasifier (1), the ammonia cracking hydrogen production device (2), the cooler (3) and the separator (4) are opened to produce ammonia hydrogen mixture. The ammonia hydrogen mixture is supplied to the peak-shaving burner (7) in different proportions according to the boiler power to achieve stable combustion of the boiler at low load. In Mode 2, the ammonia cracking hydrogen production unit (2) has a moderate power output, and the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3) have moderate volumes. When the thermal power plant is at its peak, the gasifier (1), the ammonia cracking hydrogen production unit (2), the cooler (3), and the separator (4) are turned on to generate an ammonia-hydrogen mixture. This mixture is then stored in the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3) until they are full. After this process, the ammonia cracking hydrogen production unit (2) is turned off. Cooler (3), separator (4), gasifier (1) are used to generate ammonia gas by gasifying liquid ammonia using low-temperature waste heat and then pass it into peak-shaving burner (7) for combustion. When the thermal power plant is at its lowest point, gasifier (1), ammonia cracking hydrogen production device (2), cooler (3), and separator (4) are turned on to generate ammonia-hydrogen mixture, which is then passed into the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3). Ammonia-hydrogen mixture of different proportions is supplied to peak-shaving burner (7) according to the boiler power to achieve stable combustion of the boiler at low load. In Mode 3, the ammonia cracking hydrogen production unit (2) has low power, and the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3) have the largest volume. The gasifier (1), the ammonia cracking hydrogen production unit (2), the cooler (3), and the separator (4) operate all day to produce ammonia-hydrogen mixed gas. The hydrogen-ammonia mixed gas is stored in the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3). When the thermal power is at its peak, the ammonia gas produced by the gasifier (1) is fed into the peak-shaving burner (7) for combustion. When the thermal power is at its trough, the first ammonia-hydrogen storage tank (6-1), the second ammonia-hydrogen storage tank (6-2), and the third ammonia-hydrogen storage tank (6-3) provide different proportions of ammonia-hydrogen mixed gas to the peak-shaving burner (7) according to the boiler power to achieve stable combustion of the boiler at low load.

8. The deep peak-shaving method for thermal power plants according to claim 6, characterized in that: The peak shaving of the boiler (8) includes the following process: 1) When the boiler is running at 40-50% or more of its power, the peak-shaving burner (7) runs at minimum power or stops running, and the ammonia burner (8-1), ammonia-coal burner (8-2), and coal burner (8-3) run at appropriate power according to the power requirements of the boiler (8); 2) When the boiler is running at a power of less than 40-50%, the peak-shaving burner (7) operates at a suitable power and ammonia-hydrogen ratio to meet the requirements of stable operation of the boiler at low load. The ammonia burner (8-1), ammonia-coal burner (8-2), and coal burner (8-3) operate at a suitable power according to the power requirements of the boiler (8).

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