Coal-fired power generation boiler system and peak regulation operation method thereof

Abstract

The invention relates to the technical field of ammonium hydrogen sulfate deposition of air preheaters, and discloses a coal-fired power generation boiler system and a peak regulation operation method thereof. The coal-fired power generation boiler system comprises a boiler body, and a denitration device and an air preheater are sequentially installed in a flue gas channel of the boiler body; the output end of the ammonia gas injection device communicates with the flue gas channel of the boiler body, the ammonia gas injection device is arranged on the upstream of the denitration device, and the input end of the ammonia gas injection device communicates with a compressed air supply pipeline; an ammonia gas pipeline is communicated between the output end of the ammonia gas generator and the flue gas channel of the boiler body, an ammonia gas branch is communicated between the output end of the ammonia gas generator and the input end of the ammonia gas injection device, and the ammonia gas pipeline is arranged between the output end of the ammonia gas injection device and the denitration device. In the deep peak regulation process of the generator set, one-step flue gas denitration is carried out in advance, the content of nitric oxide in flue gas at an inlet of a denitration device is reduced, and ammonium hydrogen sulfate deposition of an air preheater caused by excessive ammonia spraying is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of ammonium bisulfate deposition in air preheaters, and in particular to a coal-fired power generation boiler system and a peak-shaving operation method thereof. Background Art

[0002] Deep peak-shaving operation of coal-fired units is an important measure to achieve energy system planning. However, when coal-fired units are operated in deep peak-shaving for a long time, the fuel-type nitrogen oxides at the furnace outlet will increase. In order to meet environmental emission requirements, the unit must spray ammonia excessively, which increases ammonia escape. This will cause ammonium bisulfate deposition in the air preheater at the rear of the boiler, and ultimately lead to increased flue gas resistance, which is manifested as limited unit output.

[0003] At present, the main methods to solve the ammonium bisulfate deposition in the air preheater are to reduce the proportion of high-sulfur coal during operation, strengthen steam soot blowing, and use high-pressure water flushing during shutdown; the related equipment modifications mainly include the air preheater heat pipe with a pre-heater, the air preheater hot primary and secondary air countercurrent recirculation, and the air volume of the air preheater. However, the above-mentioned technical means cannot fundamentally solve the problem of excessive ammonia injection caused by the increase of nitrogen oxide content during the deep peak-shaving operation of coal-fired units. Summary of the invention

[0004] In view of this, the present invention provides a coal-fired power generation boiler system and a peak-shaving operation method thereof to solve the problem in the prior art that ammonium bisulfate deposition in the air preheater during deep peak-shaving of the coal-fired boiler leads to increased flue gas resistance and limited unit output.

[0005] In a first aspect, the present invention provides a coal-fired power generation boiler system, comprising:

[0006] The boiler body has a denitrification device and an air preheater installed in the flue gas channel in sequence;

[0007] An ammonia injection device, the output end of which is connected to the flue gas channel of the boiler body, the ammonia injection device is arranged upstream of the denitration device, and the input end of the ammonia injection device is connected to a compressed air supply pipeline;

[0008] An ammonia pipeline is connected between the output end of the ammonia generator and the flue gas channel of the boiler body, an ammonia branch is connected between the output end of the ammonia generator and the input end of the ammonia injection device, and the ammonia pipeline is arranged between the output end of the ammonia injection device and the denitrification device.

[0009] By setting up a compressed air supply pipeline, before the ammonia entering the flue gas channel from the ammonia pipeline reacts with the flue gas, compressed air is used to carry part of the ammonia in advance and enter the flue gas channel by injection, so as to perform a disturbance denitration on the flue gas, and then the ammonia entering from the ammonia pipeline is used to react with the flue gas to perform a secondary denitration at the denitration device. Compressed air can provide jet rigidity for the mixing of ammonia and flue gas, and at the same time increase the disturbance of the flue gas flow field in the flue to ensure that the flue gas and ammonia are mixed evenly. During the deep peak regulation of the generator set, ammonia is pre-injected into the flue gas channel with compressed air to perform a step of flue gas denitration in advance, reduce the nitrogen oxide content in the flue gas at the inlet of the denitration device, reduce the generation of ammonia escape, and then inhibit the deposition of ammonium bisulfate in the air preheater, and prevent the deposition of ammonium bisulfate in the air preheater due to excessive ammonia injection.

[0010] In an optional embodiment, the output end of the ammonia injection device is provided with a plurality of injection outlets, and the input end of the ammonia injection device is connected to the plurality of injection outlets via a plurality of injection flow channels.

[0011] In an optional embodiment, a plurality of injection outlets are evenly arranged in a lattice at the output end of the ammonia injection device. The lattice form of the injection outlet can ensure the uniformity of ammonia injection into the flue gas channel, thereby improving the mixing degree of ammonia and flue gas and improving the reaction efficiency of ammonia and flue gas reaction.

[0012] In an optional embodiment, an ammonia mixing device is installed at the input end of the ammonia injection device, and the compressed air supply pipeline and the ammonia generator are both connected to the ammonia mixing device.

[0013] In an optional embodiment, a compressed air storage tank is installed on the compressed air supply pipeline.

[0014] In an optional embodiment, the input end of the ammonia generator is connected to a urea solution storage element and a fan.

[0015] In an optional embodiment, an ammonia injection grid is installed at the output end of the ammonia pipeline.

[0016] In an optional embodiment, the output end of the ammonia injection device and / or the ammonia pipeline is connected to the horizontal section of the flue gas channel.

[0017] In a second aspect, the present invention further provides a peak load operation method of a coal-fired power generation boiler system, wherein the coal-fired power generation boiler system is installed in a coal-fired power generation system, comprising the following steps:

[0018] The flue gas generated by the operation of the boiler body is discharged outward from the flue gas channel, and the compressed air is transported to the ammonia injection device through the compressed air supply pipeline to be injected into the flue gas channel;

[0019] When the coal-fired power generation system enters deep peak-shaving operation conditions, the ammonia generator generates ammonia, part of which is transported to the flue gas duct through the ammonia pipeline, and the remaining ammonia enters the ammonia injection device through the ammonia branch and is mixed with compressed air before being injected into the flue gas duct.

[0020] During the deep peak regulation of the generator set, ammonia carried by compressed air is pre-injected into the flue gas channel to carry out a step of flue gas denitrification in advance, thereby reducing the nitrogen oxide content in the flue gas at the inlet of the denitrification device and reducing the generation of ammonia escape, thereby inhibiting the deposition of ammonium bisulfate in the air preheater and preventing the deposition of ammonium bisulfate in the air preheater due to excessive ammonia injection.

[0021] In an optional embodiment, when the coal-fired power generation system is running at high load, the flue gas temperature does not meet the input requirements, or the coal-fired power generation system fails, the ammonia generator stops supplying ammonia, and the compressed air supply pipeline stops supplying compressed air, thereby preventing the ammonia injection device from being blocked or burned by high temperature without air flow cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic structural diagram of a coal-fired power generation boiler system provided in an embodiment of the present invention.

[0024] Figure 2 A schematic structural diagram of an ammonia injection device provided in an embodiment of the present invention.

[0025] Explanation of the reference numerals: 1. Boiler body; 2. Denitrification device; 3. Air preheater; 4. Ammonia generator; 5. Urea solution storage; 6. Fan; 7. Ammonia injection device; 8. Compressed air storage tank; 9. Ammonia pipeline; 10. Ammonia branch; 11. Ammonia mixing device; 12. Ammonia spray grid; 13. Injection channel; 14. Injection outlet. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0027] Combine the following Figure 1 and Figure 2 , describing an embodiment of the present invention.

[0028] According to an embodiment of the present invention, on the one hand, a coal-fired power generation boiler system is provided to solve the problem of ammonium bisulfate deposition in the boiler tail air preheater 3 due to excessive ammonia injection caused by increased nitrogen oxide content during deep peak regulation of coal-fired units. The coal-fired power generation boiler system includes a boiler body 1, an ammonia injection device 7 and an ammonia generator 4.

[0029] The flue gas passage of the boiler body 1 is sequentially installed with a denitrification device 2 and an air preheater 3. The output end of the ammonia injection device 7 is connected to the flue gas passage of the boiler body 1. The ammonia injection device 7 is arranged upstream of the denitrification device 2. The input end of the ammonia injection device 7 is connected to a compressed air supply pipeline. An ammonia pipeline 9 is connected between the output end of the ammonia generator 4 and the flue gas passage of the boiler body 1. An ammonia branch 10 is connected between the output end of the ammonia generator 4 and the input end of the ammonia injection device 7. The ammonia pipeline 9 is arranged between the output end of the ammonia injection device 7 and the denitrification device 2.

[0030] By setting a compressed air supply pipeline, before the ammonia entering the flue gas channel from the ammonia pipeline 9 reacts with the flue gas, compressed air is used to carry part of the ammonia in advance and enter the flue gas channel by injection, so as to perform a disturbance denitration on the flue gas, and then the ammonia entering from the ammonia pipeline 9 reacts with the flue gas to perform a secondary denitration at the denitration device 2. Compressed air can provide jet rigidity for the mixing of ammonia and flue gas, and at the same time increase the disturbance of the flue gas flow field in the flue to ensure that the flue gas and ammonia are evenly mixed. During the deep peak regulation of the generator set, ammonia is pre-injected into the flue gas channel with compressed air to perform a step of flue gas denitration in advance, reduce the nitrogen oxide content in the flue gas at the inlet of the denitration device 2, reduce the generation of ammonia escape, and then inhibit the deposition of ammonium bisulfate in the air preheater 3, and prevent the deposition of ammonium bisulfate in the air preheater 3 due to excessive ammonia injection.

[0031] Furthermore, the output end of the ammonia injection device 7 and the ammonia pipeline 9 are connected to the horizontal section of the flue gas channel. The output end of the ammonia injection device 7 is provided with a plurality of injection outlets 14, and the input end of the ammonia injection device 7 is connected to the plurality of injection outlets 14 through a plurality of injection channels 13. The plurality of injection outlets 14 are evenly arranged in a lattice form at the output end of the ammonia injection device 7. The nozzle of the ammonia injection system adopts a lattice form to ensure the uniformity of ammonia injection; compressed air is used to provide jet rigidity, while increasing the disturbance of the flue gas flow field in the horizontal flue, to ensure that the flue gas and ammonia are evenly mixed.

[0032] Specifically, the installation position of the ammonia injection device 7 on the flue gas channel needs to be arranged behind the horizontal flue partition screen according to the flue gas temperature during the deep peak regulation period, so as to ensure that the flue gas temperature during the deep peak regulation period meets the reaction requirements between 800 and 1000°C, so that ammonia can react quickly with nitrogen oxides in the flue gas to generate nitrogen. The ammonia injection device 7 can also be freely started and stopped.

[0033] In one embodiment, an ammonia mixing device 11 is installed at the input end of the ammonia injection device 7, and the compressed air supply pipeline and the ammonia generator 4 are both connected to the ammonia mixing device 11 to mix the compressed air and ammonia before injection, thereby improving the uniformity of the components in the mixed gas of compressed air and ammonia, thereby ensuring that the kinetic energy of the compressed air can be fully provided to the ammonia, so that the ammonia enters the flue gas channel in a spraying manner, thereby improving the mixing degree of ammonia and flue gas.

[0034] In one embodiment, in order to ensure the continuity of compressed air supply, a compressed air storage tank 8 is installed on the compressed air supply pipeline. The compressed air is directly sent to the inside of the spray gun as the ammonia injection device 7 through the compressed air tank, mainly to ensure the rigidity of the air flow, while increasing the disturbance of the flue gas flow field in the horizontal flue to ensure that the flue gas and ammonia are mixed evenly. After the ammonia exits, the ammonia injection device 7 and the flue gas channel can also be purged to prevent dust deposition in the gun barrel.

[0035] In some other embodiments, the compressed air supply pipeline may be connected to an air compressor, and the air in the environment may be directly compressed by the air compressor and transported to the ammonia mixing device 11 through the compressed air supply pipeline.

[0036] In one embodiment, the input end of the ammonia generator 4 is connected to a urea solution storage element 5 and a fan 6, wherein the urea solution storage element 5 is a urea solution tank, and urea is mixed with water to form a urea solution which is arranged in the urea solution storage element 5. The urea solution is transported from the urea solution storage element 5 to the ammonia generator 4 through a pipeline, and the power provided by the fan 6 blows away the ammonia and carbon dioxide gases generated by the decomposition of the urea solution, thereby ensuring that the urea solution can be decomposed at a high efficiency in the ammonia generator 4.

[0037] In one embodiment, an ammonia spray grid 12 is installed at the output end of the ammonia pipeline 9, so that the ammonia gas enters the flue gas channel from the ammonia pipeline 9 in a more dispersed manner, thereby preventing the ammonia gas from undergoing a synthesis reaction at the outlet of the ammonia pipeline 9 and causing solid matter to be deposited at the outlet of the ammonia pipeline 9 and cause blockage.

[0038] In a second aspect, the present invention further provides a peak load operation method of a coal-fired power generation boiler system, wherein the coal-fired power generation boiler system is installed in a coal-fired power generation system, comprising the following steps:

[0039] The operation of the boiler body 1 generates flue gas which is discharged from the flue gas channel, and the compressed air is transported to the ammonia injection device 7 through the compressed air supply pipeline to be injected into the flue gas channel;

[0040] When the coal-fired power generation system enters deep peak-shaving operation conditions, the ammonia generator 4 generates ammonia, part of which is transported to the flue gas channel through the ammonia pipeline 9, and the remaining ammonia enters the ammonia injection device 7 through the ammonia branch 10 and is mixed with compressed air before being injected into the flue gas channel.

[0041] This method is mainly used in the process of deep peak regulation of the unit, using the horizontal flue as a reactor to perform flue gas denitration in advance, reduce the nitrogen oxide content, and prevent the deposition of ammonium bisulfate in the air preheater 3 due to excessive ammonia injection. In the process of deep peak regulation of the generator set, ammonia is pre-injected into the flue gas channel with compressed air to perform a step of flue gas denitration in advance, reduce the nitrogen oxide content in the flue gas at the inlet of the denitrification device 2, reduce the generation of ammonia escape, and then inhibit the deposition of ammonium bisulfate in the air preheater 3, and prevent the deposition of ammonium bisulfate in the air preheater 3 due to excessive ammonia injection.

[0042] In an optional embodiment, when the coal-fired power generation system is running at high load, the flue gas temperature does not meet the input requirements, or the coal-fired power generation system fails, the ammonia generator 4 stops supplying ammonia, and the compressed air supply pipeline stops supplying compressed air, thereby preventing the ammonia injection device 7 from being blocked or burned by high temperature without air flow cooling.

[0043] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A coal-fired power generation boiler system, characterized in that: include: A boiler body (1) has a flue gas passage in which a denitrification device (2) and an air preheater (3) are sequentially installed; an ammonia injection device (7), the output end of which is connected to the flue gas channel of the boiler body (1), the ammonia injection device (7) is arranged upstream of the denitration device (2), and the input end of the ammonia injection device (7) is connected to a compressed air supply pipeline; An ammonia generator (4) has an ammonia pipeline (9) connected between its output end and the flue gas channel of the boiler body (1), an ammonia branch (10) connected between the output end of the ammonia generator (4) and the input end of the ammonia injection device (7), and the ammonia pipeline (9) is arranged between the output end of the ammonia injection device (7) and the denitration device (2).

2. The coal-fired power generation boiler system according to claim 1, characterized in that: The output end of the ammonia injection device (7) is provided with a plurality of injection outlets (14), and the input end of the ammonia injection device (7) is connected to the plurality of injection outlets (14) via a plurality of injection channels (13).

3. The coal-fired power generation boiler system according to claim 2, characterized in that: The plurality of injection outlets (14) are evenly arranged in a dot matrix at the output end of the ammonia injection device (7).

4. The coal-fired power generation boiler system according to any one of claims 1 to 3, characterized in that: An ammonia mixing device (11) is installed at the input end of the ammonia injection device (7), and the compressed air supply pipeline and the ammonia generator (4) are both connected to the ammonia mixing device (11).

5. The coal-fired power generation boiler system according to any one of claims 1 to 3, characterized in that: A compressed air storage tank (8) is installed on the compressed air supply pipeline.

6. The coal-fired power generation boiler system according to any one of claims 1 to 3, characterized in that: The input end of the ammonia generator (4) is connected to a urea solution storage element (5) and a fan (6).

7. The coal-fired power generation boiler system according to any one of claims 1 to 3, characterized in that: An ammonia spraying grid (12) is installed at the output end of the ammonia pipeline (9).

8. The coal-fired power generation boiler system according to any one of claims 1 to 3, characterized in that: The output end of the ammonia injection device (7) and / or the ammonia pipeline (9) are connected to the horizontal section of the flue gas channel.

9. A peak load regulation operation method for a coal-fired power generation boiler system according to any one of claims 1 to 8, wherein the coal-fired power generation boiler system is installed in a coal-fired power generation system, characterized in that: The following steps are involved: The operation of the boiler body (1) generates flue gas which is discharged outward from the flue gas passage, and compressed air is transported to the ammonia injection device (7) through a compressed air supply pipeline to be injected into the flue gas passage; When the coal-fired power generation system enters a deep peak-shaving operation condition, the ammonia generator (4) generates ammonia, part of which is transported to the flue gas channel through the ammonia pipeline (9), and the remaining ammonia enters the ammonia injection device (7) through the ammonia branch (10) and is mixed with compressed air before being injected into the flue gas channel.

10. The peak load regulation operation method of a coal-fired power generation boiler system according to claim 9, characterized in that: When the coal-fired power generation system is running at high load, the flue gas temperature does not meet the input requirements, or the coal-fired power generation system fails, the ammonia generator (4) stops supplying ammonia, and the compressed air supply pipeline stops supplying compressed air.

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