Fluidized bed boiler SNCR (selective non-catalytic reduction) denitration system

Abstract

The utility model relates to the technical field of boiler flue gas denitration, in particular to a fluidized bed boiler SNCR (selective non-catalytic reduction) denitration system which comprises a hearth, a cyclone separator and a reducing agent injection component, one side of the top of the hearth is communicated with a smoke outlet pipe; the cyclone separator is arranged on one side of the hearth and is communicated with the flue gas outlet pipe; the reducing agent spraying assembly comprises a reducing agent source and reducing agent spraying guns, the reducing agent spraying guns comprise the first spraying gun and the second spraying gun, the first spraying gun is arranged on the lower portion of a hearth of the boiler, the second spraying gun is arranged on the smoke outlet pipe, and the first spraying gun and the second spraying gun communicate with the reducing agent source through pipelines. The utility model has the advantages that by arranging the first spray gun and the second spray gun, when the boiler runs at a low load and the temperature of smoke in the smoke outlet pipe is too low, the first spray gun at the lower part of the hearth is started; and when the boiler is in high-load operation, the temperature of the flue gas in the flue gas outlet pipe reaches the standard, and the second spray gun on the flue gas outlet pipe is started to realize high-efficiency denitration of the flue gas.

Description

Technical Field

[0001] The utility model relates to the technical field of boiler flue gas denitration, in particular to a fluidized bed boiler SNCR denitration system. Background Art

[0002] In the conventional SNCR (selective non-catalytic reduction) flue gas denitrification process of the fluidized bed, the reducing agent (ammonia solution or urea solution) spray gun is arranged at the inlet flue of the cyclone separator. When the boiler is running at high load, the flue gas temperature at the furnace outlet is 850-900℃, which is in the SNCR flue gas denitrification area. The flue gas rotates and mixes at high speed in the separator, so that the reducing agent and the flue gas are fully in contact, and the denitrification efficiency is very high (usually up to 60%-70%).

[0003] However, the disadvantage of this denitrification process is that when the boiler is started and stopped and operates at low load, the flue gas temperature at the furnace outlet is far below 850°C, which is outside the optimal reaction temperature of SNCR denitrification. The denitrification chemical reaction no longer proceeds or reacts poorly. Even if the reducing agent is sprayed, it has no effect on the flue gas denitrification, causing NOx emissions to exceed the standard when the boiler is started and stopped and operates at low load, and cannot meet environmental emission requirements. Utility Model Content

[0004] The utility model aims to overcome the shortcomings of the prior art and provide a fluidized bed boiler SNCR denitration system.

[0005] The purpose of the utility model is achieved through the following technical solutions: a fluidized bed boiler SNCR denitrification system, comprising a furnace, a cyclone separator and a reducing agent injection assembly; a flue gas outlet pipe is connected to one side of the top of the furnace; the cyclone separator is arranged on one side of the furnace and is connected to the flue gas outlet pipe; the reducing agent injection assembly comprises a reducing agent source and a reducing agent spray gun, the reducing agent spray gun comprises a first spray gun and a second spray gun, the first spray gun is arranged at the lower part of the furnace, the second spray gun is arranged on the flue gas outlet pipe, and the first spray gun and the second spray gun are both connected to the reducing agent source through pipelines.

[0006] The utility model forms two reducing agent injection positions by respectively arranging a first spray gun and a second spray gun at the lower part of the furnace of the boiler and on the flue gas outlet pipe of the boiler. When the boiler is in a low-load operation state, the flue gas temperature in the flue gas outlet pipe is low. At this time, no denitration reaction occurs when the second spray gun on the flue gas outlet pipe sprays the reducing agent, but at this time, the flue gas temperature in the furnace is higher than the temperature of the flue gas in the flue gas outlet pipe. The first spray gun in the furnace is turned on and the second spray gun on the flue gas outlet pipe is turned off to allow the denitration reaction to proceed. When the boiler is in a high-load operation state, the flue gas temperature in the furnace is too high, while the temperature of the flue gas in the flue gas outlet pipe is appropriate, and the denitration reaction can occur. At this time, the second spray gun on the flue gas outlet pipe is turned on and the first spray gun is turned off, so that the denitration reaction can proceed smoothly in the flue gas outlet pipe. By turning on the first spray gun or the second spray gun under different boiler load conditions, the best flue gas denitration effect is achieved.

[0007] In some embodiments, the reducing agent source includes a reducing agent tank and a dilution water tank, which are mixed with each other through the pipeline and connected to the first spray gun and the second spray gun. The reducing agent tank and the dilution water tank cooperate to realize the supply of reducing agent.

[0008] In some embodiments, the pipeline includes two liquid outlet branches connected to the reducing agent tank and the dilution water tank respectively, a mixing pipe connected to the two liquid outlet branches, and two liquid supply branches connected to the mixing pipes, and the two liquid supply branches are connected to the first spray gun and the second spray gun respectively. The high-concentration reducing agent in the reducing agent tank and the dilution water in the dilution water tank flow to the mixing pipe through the liquid outlet branches to mix, and the high-concentration reducing agent is diluted after mixing, and the diluted reducing agent enters the first spray gun or the second spray gun through the liquid supply branches.

[0009] In some embodiments, a driving pump is provided on both of the liquid outlet branches to pressurize the liquid in the pipeline to ensure that the first spray gun and the second spray gun have sufficient pressure when spraying the reducing agent.

[0010] In some embodiments, both of the two liquid supply branches are provided with regulating valves, and the regulating valves are used to adjust the flow rates of the reducing agent and the dilution water.

[0011] In some embodiments, a plurality of the first spray guns are evenly distributed on the furnace wall at the lower part of the furnace. The evenly distributed spray guns enable the reducing agent to be evenly sprayed in the furnace.

[0012] In some embodiments, the evenly distributed first spray guns are arranged in a single layer or multiple layers in the vertical direction. Arranging multiple layers or a single layer of first spray guns can ensure that a sufficient amount of reducing agent is sprayed into the furnace to participate in the denitration reaction.

[0013] In some embodiments, a plurality of the second spray guns are evenly distributed on the flue gas outlet pipe. The second spray guns evenly distributed on the flue gas outlet pipe allow the reducing agent to be evenly sprayed in the flue gas outlet pipe, thereby achieving a better denitration effect.

[0014] The utility model has the following advantages:

[0015] The utility model sets a first spray gun at the lower part of the furnace of the boiler and sets a second spray gun on the flue gas outlet pipe. When the boiler is running at a low load, the flue gas temperature in the flue gas outlet pipe is low and does not meet the denitration reaction conditions, while the flue gas temperature in the furnace meets the denitration reaction conditions. At this time, the first spray gun at the lower part of the furnace is opened to spray a reducing agent for denitration reaction; when the boiler is in a high load operation state, the temperature of the flue gas in the flue gas outlet pipe meets the temperature of the denitration reaction. At this time, the second spray gun on the flue gas outlet pipe is opened and the first spray gun is closed, and a reducing agent is sprayed in the flue gas outlet pipe for denitration reaction. By setting the first spray gun and the second spray gun, the boiler can switch between high load and low load operation, and the flue gas can undergo denitration reaction when the boiler is running at high and low loads, so as to meet the environmental protection requirements of flue gas emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the SNCR denitration system of a fluidized bed boiler of the utility model;

[0017] In the figure: 1. furnace; 11. flue gas outlet pipe; 2. cyclone separator; 31. first spray gun; 32. second spray gun; 41. reducing agent tank; 42. dilution water tank; 51. liquid outlet branch pipe; 52. mixing pipe; 53. liquid supply branch pipe; 6. driving pump; 7. regulating valve. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model, that is, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The components of the embodiments of the utility model described and shown in the drawings can be arranged and designed in various different configurations.

[0019] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

[0020] like Figure 1As shown, a fluidized bed boiler SNCR denitrification system includes a furnace 1, a cyclone separator 2 and a reducing agent injection assembly; a flue gas outlet pipe 11 is connected to one side of the top of the furnace 1; the cyclone separator 2 is arranged on one side of the furnace 1 and is connected to the flue gas outlet pipe 11; the reducing agent injection assembly includes a reducing agent source and a reducing agent spray gun, and the reducing agent spray gun includes a first spray gun 31 and a second spray gun 32, the first spray gun 31 is arranged at the lower part of the furnace 1, and the second spray gun 32 is arranged on the flue gas outlet pipe 11, and the first spray gun 31 and the second spray gun 32 are both connected to the reducing agent source through pipelines.

[0021] Specifically, in this embodiment, the first spray gun 31 is arranged on the furnace wall at the lower part of the furnace 1, and the spray head is located inside the furnace 1. The second spray gun 32 is arranged on the pipe wall of the flue gas outlet pipe 11, and the spray head is located inside the pipe wall of the flue gas outlet pipe 11.

[0022] During the implementation of this embodiment, when the boiler is running at a low load, the flue gas temperature in the flue gas outlet pipe 11 is low and does not meet the conditions for the denitration reaction, while the flue gas temperature at the lower part of the furnace 1 is in the temperature range of the denitration reaction. Therefore, when the boiler is at a low load, the first spray gun 31 at the lower part of the furnace 1 is turned on to allow the denitration reaction to proceed. When the boiler is at a high load, the flue gas temperature in the flue gas outlet pipe 11 is high and is in the temperature range of the denitration reaction. The reductant is sprayed here for denitration, which can obtain a higher denitration efficiency. At this time, the second spray gun 32 on the flue gas outlet pipe 11 is turned on to allow the denitration reaction to proceed in the flue gas outlet pipe 11. Through the first spray gun 31 and the second spray gun 32, the boiler can smoothly carry out the denitration reaction under both low load and high load conditions, so that the flue gas emissions meet environmental protection requirements.

[0023] Preferably, the reducing agent source includes a reducing agent tank 41 and a dilution water tank 42, and the reducing agent tank 41 and the dilution water tank 42 are mixed through the pipeline and communicated with the first spray gun 31 and the second spray gun 32. Specifically, in this embodiment, a high-concentration ammonia solution or urea solution is stored in the reducing agent tank 41, and is diluted with water in the dilution water tank 42 and then sprayed out by the first spray gun 31 or the second spray gun 32.

[0024] Preferably, the pipeline includes two liquid outlet branches 51 respectively connected to the reducing agent tank 41 and the dilution water tank 42, a mixing tube 52 connected to the two liquid outlet branches 51, and two liquid supply branches 53 connected to the mixing tube 52, and the two liquid supply branches 53 are respectively connected to the first spray gun 31 and the second spray gun 32. The high-concentration reducing agent solution flows through the liquid outlet branch 51 to the mixing tube 52 to be mixed and diluted with the dilution water, and the diluted reducing agent solution then enters the first spray gun 31 or the second spray gun 32 through the liquid supply branch 53.

[0025] Preferably, the two liquid outlet branches 51 are both provided with a driving pump 6. The driving pump 6 drives the solution in the reducing agent tank 41 and the water in the dilution water tank 42 to pressurize the liquid in the pipeline.

[0026] Preferably, both of the two liquid supply branches 53 are provided with a regulating valve 7. The regulating valve 7 is used to adjust the liquid flow rate.

[0027] Preferably, the first spray guns 31 are evenly distributed on the furnace wall at the lower part of the furnace 1. The first spray guns 31 are evenly arranged in the lower area of ​​the furnace 1, so that the reducing agent is more evenly sprayed into the furnace 1 and fully mixed with the flue gas.

[0028] Preferably, the evenly distributed first spray guns 31 are arranged in a single layer or multiple layers in the vertical direction. The first spray guns 31 arranged in a single layer or multiple layers ensure that sufficient reducing agent is sprayed into the furnace 1 .

[0029] Preferably, a plurality of the second spray guns 32 are evenly distributed on the flue gas outlet pipe 11. The plurality of second spray guns 32 are evenly arranged on the flue gas outlet pipe 11, so that the reducing agent sprayed into the flue gas outlet pipe 11 is more even, and the denitration reaction is more sufficient.

[0030] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the utility model by using the above-mentioned technical content without departing from the scope of the technical solution of the utility model, or modify it into an equivalent embodiment of equivalent changes. Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments based on the technology of the utility model without departing from the content of the technical solution of the utility model shall fall within the protection scope of the technical solution of the utility model.

Claims

1. A fluidized bed boiler SNCR denitrification system, characterized in that: include: A furnace (1), wherein a smoke outlet pipe (11) is provided on one side of the top of the furnace (1); a cyclone separator (2), the cyclone separator (2) being arranged on one side of the furnace (1) and being in communication with the flue gas outlet pipe (11); A reducing agent injection assembly, the reducing agent injection assembly comprising a reducing agent source and a reducing agent spray gun, the reducing agent spray gun comprising a first spray gun (31) and a second spray gun (32), the first spray gun (31) being arranged at the lower part of the furnace (1), the second spray gun (32) being arranged on the flue gas outlet pipe (11), the first spray gun (31) and the second spray gun (32) being both connected to the reducing agent source through a pipeline.

2. The SNCR denitration system for a fluidized bed boiler according to claim 1, characterized in that: The reducing agent source comprises a reducing agent tank (41) and a dilution water tank (42). The reducing agent tank (41) and the dilution water tank (42) are mixed through the pipeline and then communicated with the first spray gun (31) and the second spray gun (32).

3. The SNCR denitration system for fluidized bed boiler according to claim 2, characterized in that: The pipeline comprises two liquid outlet branch pipes (51) respectively connected to the reducing agent tank (41) and the dilution water tank (42), a mixing pipe (52) connected to the two liquid outlet branch pipes (51), and two liquid supply branch pipes (53) connected to the mixing pipes (52); the two liquid supply branch pipes (53) are respectively connected to the first spray gun (31) and the second spray gun (32).

4. The SNCR denitration system for a fluidized bed boiler according to claim 3, characterized in that: A driving pump (6) is provided on each of the two liquid outlet branch pipes (51).

5. The SNCR denitration system for fluidized bed boiler according to claim 3, characterized in that: Both of the two liquid supply branch pipes (53) are provided with regulating valves (7).

6. The SNCR denitration system for fluidized bed boiler according to claim 1, characterized in that: A plurality of the first spray guns (31) are evenly distributed on the furnace wall at the lower part of the furnace chamber (1).

7. The SNCR denitration system for fluidized bed boiler according to claim 6, characterized in that: The evenly distributed first spray guns (31) are arranged in a single layer or multiple layers in the vertical direction.

8. The SNCR denitration system for fluidized bed boiler according to claim 1, characterized in that: A plurality of the second spray guns (32) are evenly distributed on the smoke outlet pipe (11).

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