A low-carbon peak shaving system and method of burning ammonia fuel

Abstract

This invention discloses a low-carbon peak-shaving system and method for using ammonia-blended fuel. The low-carbon peak-shaving system includes a coal-fired boiler, a coal-fired burner, an ammonia burner, a coal-fired generator, a clean energy generator, an ammonia preparation device, an ammonia storage system, ammonia pipelines, a first switch, a second switch, a third switch, a first transformer, a second transformer, a third transformer, output lines, and a power grid. The ammonia preparation device, the ammonia storage system, and the ammonia burner are connected via ammonia pipelines. This invention utilizes the excess electricity generated by the coal-fired unit to produce ammonia, enabling the actual grid-connected power of the coal-fired unit to reach the required grid-connected power. Under full load of the coal-fired unit, ammonia is injected into the main combustion zone of the furnace using a suitable flow rate and method, while controlling the combustion stability within the furnace and the NO at the furnace outlet. X Under the premise that the concentration and carbon content of fly ash have a relatively small impact, the system's renewable energy absorption capacity and carbon emissions can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of generator set, in particular to a low-carbon peak shaving system and method for blending ammonia fuel. BACKGROUND

[0002] Seeking low-carbon energy replacement is an important measure for coal-fired units to reduce carbon emissions. Ammonia, as a zero-carbon fuel, is more energy-efficient, more mature in technology, and safer to store and transport, making it an ideal candidate for low-carbon emissions, and has great potential to replace coal. Therefore, in recent years, blending ammonia combustion in coal-fired units has received considerable attention.

[0003] The properties of ammonia fuel are quite different from those of the design fuel of coal-fired units. The impact of coupling ammonia combustion in coal-fired units mainly includes: 1) ammonia combustion is relatively slow, and there is a risk of flame instability; 2) ammonia carries a large amount of nitrogen, which poses a risk of excessively high NOx concentration at the furnace outlet; 3) ammonia combustion temperature is relatively low, which poses a risk of excessively high carbon content in fly ash. X SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the defects of the prior art, and to provide a low-carbon peak shaving system and method for blending ammonia fuel, which uses excess electricity generated by a coal-fired unit to produce ammonia, so that the actual grid-connected power of the coal-fired unit can reach the required grid-connected power. Under full load of the coal-fired unit, ammonia is injected into the relatively low O2 and high NOx concentration region in the furnace at a suitable flow rate and manner, which has little effect on the combustion stability in the furnace, the NOx concentration at the furnace outlet, and the carbon content in fly ash, and can ensure that the ammonia blending ratio is above 20%, thereby effectively improving the renewable energy consumption capacity of the system and reducing carbon emissions. X X

[0005] To achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0006] In a first aspect, the present application provides a low-carbon peak shaving system for blending ammonia fuel, which comprises a coal-fired boiler, a coal-fired combustor, an ammonia combustor, a coal-fired unit generator, a clean energy generator, an ammonia preparation device, an ammonia storage system, an ammonia pipeline, a first switch, a second switch, a third switch, a first transformer, a second transformer, a third transformer, an output circuit, and a power grid.

[0007] The coal-fired unit generator is connected to the power grid through the first switch, the first transformer, and the output circuit.

[0008] The coal-fired unit generator is connected to the ammonia preparation device through the second switch and the second transformer.

[0009] The clean energy generator is connected to the ammonia preparation device through the third switch and the third transformer. ​​​

[0010] The ammonia preparation device, the ammonia storage system and the ammonia combustor are connected through an ammonia pipeline;

[0011] The coal combustor and the ammonia combustor are installed on the coal-fired boiler.

[0012] Preferably, the ammonia pipeline is provided with an ammonia pressurizing device, which is located between the ammonia preparation device and the ammonia storage system.

[0013] Preferably, the ammonia pipeline is provided with an ammonia depressurizing device, which is located between the ammonia storage system and the ammonia combustor.

[0014] Preferably, the coal-fired boiler is provided with a secondary air volume control system for controlling the secondary air volume of the coal-fired boiler.

[0015] Preferably, the coal-fired boiler is provided with a overfire air volume control system for controlling the overfire air volume of the coal-fired boiler.

[0016] Preferably, the low-carbon peak shaving system further comprises a coal volume control system for controlling the coal volume of the coal combustor.

[0017] Preferably, the low-carbon peak shaving system further comprises an ammonia volume control system for controlling the ammonia volume of the ammonia combustor.

[0018] Preferably, the low-carbon peak shaving system further comprises a power controller connected to the coal-fired unit generator, the second switch and the power grid.

[0019] Further, the operation method of the low-carbon peak shaving system is as follows:

[0020] During the low electricity consumption period of the power grid, the power controller obtains the difference between the required on-grid power of the power grid and the actual power generation of the coal-fired unit generator, closes the second switch, and uses the excess power generated by the coal-fired unit generator to prepare ammonia through the ammonia preparation device, so that the actual on-grid power of the coal-fired unit generator reaches the required on-grid power.

[0021] When the power grid needs the low-carbon peak shaving system to consume renewable energy, the third switch is closed, and the power generated by the clean energy generator is used to prepare ammonia through the ammonia preparation device; the ammonia prepared by the ammonia preparation device is sent to the ammonia storage system through the ammonia pipeline.

[0022] Under full load of the coal-fired unit, the ammonia stored in the ammonia storage system is sent into the ammonia burner through the ammonia pipeline to ensure that the ammonia blending ratio is above 20%, and as the load of the coal-fired unit increases, the ammonia blending ratio is increased; during blending combustion, the ammonia is injected into the main combustion zone of the furnace in a suitable flow rate and mode to keep the excess air coefficient of the main combustion zone below 0.7, and the temperature field of the main combustion zone, the NOx concentration at the furnace outlet and the carbon content of fly ash are monitored X .

[0023] In a second aspect, the present application provides a low-carbon peak shaving method for blending ammonia fuel, which is implemented by using the above-mentioned low-carbon peak shaving system for blending ammonia fuel, and the method comprises the following steps:

[0024] Step 1: determining whether the output power of the coal-fired unit needs to be quickly reduced, and if the output power of the coal-fired unit needs to be quickly reduced, executing step 2; determining whether the system needs to consume renewable energy, and if the system needs to consume renewable energy, executing step 3;

[0025] Step 2: controlling the power of the ammonia preparation device according to the target power reduction value of the coal-fired unit to quickly reduce the output power of the coal-fired unit;

[0026] Step 3: controlling the power of the ammonia preparation device according to the target consumption value of the renewable energy of the power grid to consume the renewable energy of the power grid;

[0027] Step 4: under full load of the coal-fired unit, the ammonia is injected into the main combustion zone of the furnace in a suitable flow rate and mode, and the ammonia blending ratio is increased as the load of the coal-fired unit increases;

[0028] Step 5: adjusting the secondary air volume control system and the overfire air volume control system of the coal-fired boiler to keep the excess air coefficient of the main combustion zone below 0.7;

[0029] Step 6: monitoring the temperature field of the main combustion zone, the NOx concentration at the furnace outlet and the carbon content of fly ash, and if the temperature of the main combustion zone is lower than the minimum stable combustion temperature of the pulverized coal, the NOx concentration at the furnace outlet is higher than the design value or the carbon content of fly ash is higher than the design value, the ammonia combustion amount of the ammonia burner is reduced for adjustment. X X

[0030] The present application has the following beneficial effects: during the low valley period of the power grid, the excess power generated by the coal-fired unit is used to prepare ammonia, so that the actual on-grid power of the coal-fired unit reaches the required on-grid power; under full load of the coal-fired unit, the ammonia blending ratio is ensured to be above 20%, the renewable energy consumption capacity of the system is effectively improved, the carbon emission is reduced, and the influence on the combustion stability in the furnace, the NOx concentration at the furnace outlet and the carbon content of fly ash is small. X BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 ​​​A structure schematic diagram of a low-carbon peak regulation system for burning ammonia fuel in admixture;

[0032] Figure 2 A flow chart of a low-carbon peak regulation method for burning ammonia fuel in admixture. DETAILED DESCRIPTION

[0033] The specific embodiments of the present application will be further described in conjunction with the accompanying drawings of the embodiments of the present application, so that the technical solutions of the present application are easier to understand and master. It should be understood that the specific embodiments described herein are only used to explain some embodiments of the present application, but not all embodiments. Other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0034] Embodiment 1

[0035] Please refer to the accompanying drawings Figure 1 , a low-carbon peak regulation system for burning ammonia fuel in admixture, comprising a coal-fired boiler 1, a coal-fired burner 2, an ammonia burner 3, a coal-fired unit generator 4, a clean energy generator 5, a coal quantity control system 6, an ammonia quantity control system 7, a secondary air quantity control system 8, a combustion air quantity control system 9, an ammonia preparation device 10, an ammonia storage system 11, an ammonia pipeline 12, an ammonia pressurizing device 13, an ammonia depressurizing device 14, a power controller 15, a first switch 16, a second switch 17, a third switch 18, a first transformer 19, a second transformer 20, a third transformer 21, an output line 22 and a power grid 23.

[0036] The coal-fired unit generator 4 is connected to the power grid 23 through the first switch 16, the first transformer 19 and the output line 22.

[0037] The coal-fired unit generator 4 is connected to the ammonia preparation device 10 through the second switch 17 and the second transformer 20.

[0038] The clean energy generator 5 is connected to the ammonia preparation device 10 through the third switch 18 and the third transformer 21.

[0039] The ammonia preparation device 10, the ammonia storage system 11 and the ammonia burner 3 are connected through the ammonia pipeline 12. The ammonia pipeline 12 is provided with the ammonia pressurizing device 13 and the ammonia depressurizing device 14. The ammonia pressurizing device 13 is located between the ammonia preparation device 10 and the ammonia storage system 11, and the ammonia depressurizing device 14 is located between the ammonia storage system 11 and the ammonia burner 3.

[0040] The coal-fired burner 2 and the ammonia burner 3 are installed on the coal-fired boiler 1. The coal-fired boiler 1 is provided with a secondary air volume control system 8 and a overfire air volume control system 9, the secondary air volume control system 8 is used for controlling the secondary air volume of the coal-fired boiler 1, and the overfire air volume control system 9 is used for controlling the overfire air volume of the coal-fired boiler 1.

[0041] The coal amount control system 6 is used for controlling the coal amount of the coal-fired burner 2, and the ammonia amount control system 7 is used for controlling the ammonia amount of the ammonia burner 3.

[0042] The power controller 15 is connected with the coal-fired unit generator 4, the second switch 17 and the power grid 23 respectively, and is used for controlling the coal-fired unit generator 4 and the second switch 17.

[0043] The operation method of the low-carbon peak regulation system is as follows:

[0044] When the power grid 23 is in the electricity low-peak period, the power controller 15 obtains the difference between the required on-grid power of the power grid 23 and the actual power generation of the coal-fired unit generator 4, closes the second switch 17, and uses the excess power generated by the coal-fired unit generator 4 to prepare ammonia by the ammonia preparation device 10, so that the actual on-grid power of the coal-fired unit generator 4 reaches the required on-grid power.

[0045] When the power grid 23 needs to consume renewable energy, the third switch 18 is closed, and the power generated by the clean energy generator 5 is used to prepare ammonia by the ammonia preparation device 10.

[0046] The ammonia prepared by the ammonia preparation device 10 passes through the ammonia pressurizing device 13 and is sent to the ammonia storage system 11 through the ammonia pipeline 12.

[0047] Under the full load of the coal-fired unit, the ammonia stored in the ammonia storage system 11 passes through the ammonia depressurizing device 14 and is sent to the ammonia burner 3 through the ammonia pipeline 12. Under the full load of the coal-fired unit, the coal amount control system 6 and the ammonia amount control system 7 are controlled to ensure that the ammonia mixing ratio is above 20%, and as the load of the coal-fired unit increases, the coal amount control system 6 and the ammonia amount control system 7 are controlled to increase the ammonia mixing ratio. When burning, the ammonia is injected into the relatively low-O2 and high-NO X concentration area (i.e. the main combustion zone) of the coal-fired boiler 1 by adopting appropriate flow rate and mode. The secondary air volume control system 8 and the overfire air volume control system 9 are controlled to keep the excess air coefficient of the main combustion zone of the coal-fired boiler 1 below 0.7. The temperature field of the main combustion zone of the coal-fired boiler 1, the NO X concentration at the furnace outlet and the carbon content of fly ash are monitored.

[0048] If the temperature of the main combustion zone of the coal-fired boiler 1 is lower than the minimum stable combustion temperature of the coal powder, the ammonia amount of the ammonia burner 3 is reduced for adjustment.

[0049] If the NOX If the concentration is higher than the design value, it can be adjusted by reducing the amount of ammonia burned in ammonia burner 3.

[0050] If the carbon content of the fly ash at the outlet of the furnace of coal-fired boiler 1 is higher than the design value, it can be adjusted by reducing the amount of ammonia burned in ammonia burner 3.

[0051] Example 2

[0052] Please see the appendix Figure 2 This is a flowchart of a low-carbon peak-shaving method for ammonia-blended fuel according to the present invention. The present invention provides a low-carbon peak-shaving method for ammonia-blended fuel, which is implemented using the low-carbon peak-shaving system for ammonia-blended fuel described in Example 1. The specific steps of this method are as follows:

[0053] Step 1: Determine if it is necessary to rapidly reduce the output power of the coal-fired power unit. If the coal-fired power unit needs to rapidly reduce its output power, proceed to Step 2. Determine if the system needs to absorb renewable energy. If the system needs to absorb renewable energy, proceed to Step 3.

[0054] Step 2: Control the power of the ammonia preparation unit according to the target power reduction value of the coal-fired unit in order to quickly reduce the output power of the coal-fired unit;

[0055] Step 3: Control the power of the ammonia preparation unit according to the grid renewable energy absorption target value in order to absorb the grid renewable energy;

[0056] Step 4: Under full load of the coal-fired unit, ammonia is injected into the furnace at a suitable flow rate and method to create a relatively low O2 and high NO content environment. X In the concentration range, the proportion of ammonia blending increases with the increase of coal-fired unit load;

[0057] Step 5: Adjust the secondary air volume control system and the burnout air volume control system to keep the excess air coefficient in the main combustion zone below 0.7;

[0058] Step 6: Monitor the temperature field in the main combustion zone and the NO at the furnace outlet. X Concentration and fly ash carbon content; if the temperature in the main combustion zone is lower than the minimum stable combustion temperature of pulverized coal, and NO at the furnace outlet... X If the concentration or carbon content of fly ash is higher than the design value, the amount of ammonia burned in the ammonia burner can be adjusted by reducing the amount of ammonia burned.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein.

Claims

1. A low carbon peak shaving system with ammonia fuel blending, characterized in that, The system comprises a coal-fired boiler (1), a coal-fired burner (2), an ammonia burner (3), a coal-fired unit generator (4), a clean energy generator (5), an ammonia preparation device (10), an ammonia storage system (11), an ammonia pipeline (12), a first switch (16), a second switch (17), a third switch (18), a first transformer (19), a second transformer (20), a third transformer (21), an output line (22) and a power grid (23). The coal-fired unit generator (4) is connected to the power grid (23) through the first switch (16), the first transformer (19) and the output line (22). The coal-fired unit generator (4) is connected to the ammonia preparation device (10) through the second switch (17) and the second transformer (20). The clean energy generator (5) is connected to the ammonia preparation device (10) through the third switch (18) and the third transformer (21). The ammonia preparation device (10), the ammonia storage system (11) and the ammonia burner (3) are connected through the ammonia pipeline (12). The coal-fired burner (2) and the ammonia burner (3) are installed on the coal-fired boiler (1).

2. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, characterized in that, The ammonia pipeline (12) is provided with an ammonia pressurizing device (13) located between the ammonia preparation device (10) and the ammonia storage system (11).

3. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, characterized in that, The ammonia pipeline (12) is provided with an ammonia depressurizing device (14) located between the ammonia storage system (11) and the ammonia burner (3).

4. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, characterized in that, The coal-fired boiler (1) is provided with a secondary air volume control system (8) for controlling the secondary air volume of the coal-fired boiler (1).

5. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, wherein, The coal-fired boiler (1) is provided with a overfire air volume control system (9) for controlling the overfire air volume of the coal-fired boiler (1).

6. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, wherein, A coal quantity control system (6) is further included for controlling the coal quantity of the coal-fired burner (2).

7. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, wherein, An ammonia quantity control system (7) is further included for controlling the ammonia quantity of the ammonia burner (3).

8. The low carbon peak shaving system with ammonia-doped combustion according to claim 1, wherein, A power controller (15) is further included and connected to the coal-fired unit generator (4), the second switch (17) and the power grid (23), respectively.

9. The low carbon peak shaving system with ammonia-doped combustion according to claim 8, characterized in that, The operation method of the low-carbon peak shaving system is as follows: During the low electricity consumption period of the power grid, the power controller obtains the difference between the required online power of the coal-fired unit generator and the actual power generation of the coal-fired unit generator, closes the second switch, and uses the excess power generated by the coal-fired unit generator to produce ammonia through the ammonia preparation device, so that the actual online power of the coal-fired unit generator reaches the required online power. When the power grid needs the low-carbon peak shaving system to consume renewable energy, the third switch is closed, and the power generated by the clean energy generator is used to produce ammonia through the ammonia preparation device; the ammonia prepared by the ammonia preparation device is sent to the ammonia storage system through the ammonia pipeline. Under full load of coal-fired units, ammonia stored in ammonia storage system is sent into ammonia burner through ammonia pipeline to ensure that the ammonia blending ratio is above 20%, and with the increase of the load of coal-fired units, the ammonia blending ratio is increased; during the blending combustion, ammonia is injected into the main combustion zone of the furnace at a suitable flow rate and mode to maintain the excess air coefficient in the main combustion zone below 0.7, while the temperature field of the main combustion zone, the NOx concentration at the outlet of the furnace and the carbon content of fly ash are monitored. X concentration and carbon content of fly ash.

10. A low-carbon peak shaving method of ammonia fuel blending, which is implemented by using the low-carbon peak shaving system of ammonia fuel blending according to any one of claims 1-8, characterized in that, The system comprises: Step 1: Determine whether the coal-fired unit needs to quickly reduce the output power, if the coal-fired unit needs to quickly reduce the output power, execute step 2; Determine whether the system needs to consume renewable energy, if the system needs to consume renewable energy, execute step 3; Step 2, control the ammonia preparation device power according to the coal-fired unit target power reduction value to quickly reduce the coal-fired unit output power; Step 3, control the ammonia preparation device power according to the grid renewable energy target consumption value to consume the grid renewable energy; Step 4, under full load of the coal-fired unit, ammonia is injected into the main combustion zone of the furnace in a suitable flow rate and mode, and the ammonia mixing ratio is increased as the load of the coal-fired unit increases; Step 5, adjust the secondary air volume control system and the overfire air volume control system of the coal-fired boiler to keep the excess air coefficient in the main combustion zone below 0.7; Step 6, monitor the main combustion zone temperature field, the furnace outlet NO X concentration and the carbon content of fly ash, if the main combustion zone temperature is lower than the minimum stable combustion temperature of the pulverized coal, the furnace outlet NO X concentration or the carbon content of fly ash is higher than the design value, adjust by reducing the ammonia combustion amount of the ammonia burner.

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