Urea system for reducing nitrogen oxide emissions in waste incineration flue gas

Abstract

The utility model relates to garbage incineration power generation technical field, specifically disclose a kind of for reducing the urea system of nitrogen oxides compound emission in garbage incineration flue gas, including the urea dissolving tank for preparing urea and at least two with the number matching of incinerator spray device, soft water is connected with each spray device respectively by soft water tank, spray device includes the first nozzle and second nozzle of being arranged in flue gas duct one of incinerator from bottom to top sequentially;The spray device is also provided with several third nozzles, and third nozzle is arranged at flue gas duct one 28m~32m place.The utility model increases a layer of nozzle compared with prior art urea system, and the nozzle is increased to three layers, nitrogen oxides in flue gas can be handled in time, improve the denitration efficiency of flue gas;In addition, the flue gas temperature in the flue gas duct of third nozzle is just located in the preferred urea reaction temperature range area, so the denitration efficiency of flue gas can be greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of waste incineration power generation technology, and in particular to a urea system for reducing nitrogen oxide emissions in waste incineration flue gas. Background Technology

[0002] Waste-to-energy incineration plants are equipped with SNCR (Selective Non-Catalytic Reduction) systems in their incinerator flue gas ducts. These systems primarily reduce nitrogen oxide emissions from the flue gas. The principle involves injecting a reducing agent (such as ammonia or urea solution) into the high-temperature flue gas to reduce nitrogen oxides into harmless nitrogen and water. The denitrification efficiency is generally 30%-70%, depending on factors such as temperature control and the uniformity of the reducing agent mixing.

[0003] Reference Figure 1 The existing urea system includes a urea dissolving tank (1) for preparing urea and at least two injection devices (4) matching the number of incinerators. The injection devices (4) are used to inject urea into the incinerator. Compressed air is connected to each injection device (4) through pipes. Soft water is connected to each injection device (4) through a soft water tank (3). A first soft water pump (301) for providing power is provided on the pipe connecting the soft water tank (3) and the injection device (4). The urea dissolving tank (1) is connected to the urea storage tank (2) through a first main pipe (101). The urea storage tank (2) is connected to the injection device (4) through a second main pipe (201). A first urea pump (102) is provided on the first main pipe (101), and a first reducing agent pump (202) is provided on the second main pipe (201). The injection device (4) includes a plurality of first nozzles (401) and second nozzles (402) arranged sequentially from bottom to top in the incinerator. The first nozzle (401) is located 22m from the first flue of the incinerator, with a temperature of about 1050℃; the second nozzle (402) is located 24m from the first flue of the incinerator, with a temperature of about 1000℃.

[0004] Practice has shown that the urea system injection device has too few nozzle layers (only two layers), which cannot process nitrogen oxides in the flue gas in time, resulting in low denitrification efficiency. In addition, the optimal temperature for urea reaction is 850℃-1000℃, and the nozzles of the above-mentioned injection device are not located in the optimal denitrification temperature range, which also leads to low denitrification efficiency. Utility Model Content

[0005] To address the technical problems of low denitrification efficiency in existing urea systems, such as insufficient nozzle layers and nozzle placement outside the optimal denitrification temperature range, this invention provides a urea system for reducing nitrogen oxide emissions from waste incineration flue gas.

[0006] The technical solution adopted in this utility model is as follows: a urea system for reducing nitrogen oxide emissions in waste incineration flue gas, comprising a urea dissolving tank for preparing urea and at least two injection devices matching the number of incinerators. The injection devices are used to inject urea into the incinerator. Compressed air is connected to each injection device through pipelines, and soft water is connected to each injection device through a soft water tank. A first soft water pump for providing power is installed on the pipeline connecting the soft water tank and the injection device. The urea dissolving tank is connected to a urea storage tank through a first main pipe, and the urea storage tank is connected to the injection device through a second main pipe. A first urea pump is installed on the first main pipe, and a first reducing agent pump is installed on the second main pipe. The injection device includes a plurality of first nozzles and second nozzles arranged sequentially from bottom to top in the flue of the incinerator. The injection device is also provided with a plurality of third nozzles, which are arranged above the second nozzles at a distance of 28m to 32m from the flue of the incinerator.

[0007] Furthermore, the first nozzle, the second nozzle, and the third nozzle are made of stainless steel.

[0008] Furthermore, a first branch pipe is connected to the urea dissolving tank, and the other end of the first branch pipe is connected to the first main pipe. A second urea pump for providing power and a corresponding valve are installed on the first branch pipe.

[0009] Furthermore, a first pressure relief pipe is connected to the first main pipe, and the other end of the first pressure relief pipe is connected to the urea dissolving tank. A first pressure relief valve is installed on the first pressure relief pipe.

[0010] Furthermore, it also includes a second branch pipe, the two ends of which are respectively connected to the second main pipe at both ends of the first reducing agent pump. The second branch pipe is equipped with a second reducing agent pump for providing power and a corresponding valve.

[0011] Furthermore, it also includes a second pressure relief pipe, one end of which is connected to the second main pipe between the first reducing agent pump and the injection device, and the other end is connected to the urea storage tank. A second pressure relief valve is installed on the second pressure relief pipe.

[0012] Furthermore, it also includes a third branch pipe, the two ends of which are connected to the pipes at both ends of the first soft water pump. The third branch pipe is equipped with a second soft water pump for providing power and a corresponding valve.

[0013] Furthermore, it also includes a third pressure relief pipe, one end of which is connected to the pipe between the first soft water pump and the jetting device, and the other end is connected to the soft water tank. A third pressure relief valve is installed on the third pressure relief pipe.

[0014] The beneficial effects of this utility model are:

[0015] 1. Compared with the existing urea system, this utility model adds an extra layer of nozzles, increasing the number of nozzles to three, which can promptly treat nitrogen oxides in the flue gas and improve the denitrification efficiency of the flue gas; in addition, the flue gas temperature in the flue where the third nozzle is located is exactly in the optimal urea reaction temperature range, thus greatly improving the denitrification efficiency of the flue gas.

[0016] 2. The spare pipe of this utility model can realize online maintenance of urea pump, reducing agent pump and soft water pump without stopping the machine, making the maintenance process more convenient and faster, without affecting the normal production process, and ensuring the orderly production process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a urea system in the prior art.

[0018] Figure 2 This is a schematic diagram of the structure of this utility model.

[0019] Figure 3 This is a schematic diagram of the spraying device of this utility model.

[0020] The diagram is marked as follows:

[0021] 1. Urea dissolving tank; 101. First main pipe; 102. First urea pump; 103. First branch pipe; 104. Second urea pump; 105. First pressure relief pipe; 106. First pressure relief valve;

[0022] 2. Urea storage tank; 201. Second main pipe; 202. First reducing agent pump; 203. Second branch pipe; 204. Second reducing agent pump; 205. Second pressure relief pipe; 206. Second pressure relief valve;

[0023] 3. Soft water tank; 301. First soft water pump; 302. Third branch pipe; 303. Second soft water pump; 304. Third pressure relief pipe; 305. Third pressure relief valve;

[0024] 4. Spraying device; 401. First nozzle; 402. Second nozzle; 403. Third nozzle;

[0025] 5. Incinerator; 6. One flue. Detailed Implementation

[0026] In the description of this utility model, it should be noted that the terms "front", "up", "down", "left", "right", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0027] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Example

[0030] In view of the technical problems existing in the background art, the present invention provides a urea system for reducing nitrogen oxide emissions in waste incineration flue gas. This embodiment takes three incinerators of a certain company as an example, and the three incinerators need to be equipped with three injection devices.

[0031] In the specific technical solution, refer to Figure 2 The urea system for reducing nitrogen oxide emissions in waste incineration flue gas includes a urea dissolving tank 1 for urea preparation and three injection devices 4 matching the number of incinerators. The injection devices 4 are used to inject urea into the incinerator 5. Compressed air is connected to each injection device 4 through pipes, and soft water is connected to each injection device 4 through a soft water tank 3. A first soft water pump 301 for providing power is installed on the pipe connecting the soft water tank 3 and the injection device 4. The urea dissolving tank 1 is connected to the urea storage tank 2 through a first main pipe 101, and the urea storage tank 2 is connected to the injection devices 4 through a second main pipe 201. A first urea pump 102 is installed on the first main pipe 101, and a first reducing agent pump 202 is installed on the second main pipe 201. The injection devices 4 include a number of first nozzles 401 and second nozzles 402 arranged sequentially from bottom to top in the flue duct 6 of the incinerator.

[0032] Urea system principle: Since the nozzle of the injection device 4 is located inside the incinerator, the temperature inside the incinerator is as high as 850℃~1400℃. Therefore, the nozzle is in a high-temperature environment and needs to be cooled down. For this purpose, soft water is introduced into the injection device to cool the nozzle. The purpose of introducing compressed air into the injection device is to atomize urea and provide injection power.

[0033] The structure described above is the same as that of existing urea systems. However, existing urea systems suffer from low denitrification efficiency due to insufficient nozzle layers and nozzle placement not being within the optimal denitrification temperature range. Therefore, this embodiment makes the following further improvements: (Refer to...) Figure 2 and Figure 3In this embodiment, the spraying device 4 is also provided with a plurality of third nozzles 403. The third nozzles 403 are arranged above the second nozzles 402 and are located at 28m to 32m of the flue 6 of the incinerator.

[0034] As is well known, the temperature inside the incinerator 5 reaches 850℃ to 1400℃, and the temperature increases further as the flue gas duct 6 approaches the furnace. In other words, the temperature of the flue gas gradually decreases from bottom to top within the flue gas duct. Field measurements show that at a depth of 28m to 32m in the flue gas duct 6, the flue gas temperature is around 900℃, while the optimal temperature for urea reaction is between 850℃ and 1000℃. This temperature range falls precisely within the optimal urea reaction temperature range, thus significantly improving the denitrification efficiency of the flue gas. Furthermore, compared to existing urea systems, this invention adds an extra layer of nozzles, increasing the number to three layers, which can promptly treat nitrogen oxides in the flue gas and further improve the denitrification efficiency.

[0035] The nozzles need to be resistant to high temperatures and corrosion, so the first nozzle 401, the second nozzle 402 and the third nozzle 403 are made of stainless steel.

[0036] To enable online inspection and maintenance of the first urea pump 102 and to extend its service life, refer to Figure 2 Therefore, in this embodiment, a first branch pipe 103 is connected to the urea dissolving tank 1. The other end of the first branch pipe 103 is connected to the first main pipe 101. A second urea pump 104 for providing power and a corresponding valve are provided on the first branch pipe 103.

[0037] As can be seen from the above structure, in this application, urea in the urea dissolving tank 1 can be transported to the urea storage tank 2 through two pipelines. Under normal circumstances, one pipeline is used for standby. When one urea pump fails or needs maintenance, the other pipeline is used for transportation. This enables online maintenance and repair of the urea pump. Moreover, to avoid the single urea pump from running under high load for a long time, the two urea pumps can also be used alternately under normal circumstances, which protects the urea pump and effectively improves its service life.

[0038] To avoid damage to pipelines and equipment caused by pressure buildup, refer to Figure 2Therefore, in this embodiment, a first pressure relief pipe 105 is connected to the first main pipe 101, and the other end of the first pressure relief pipe 105 is connected to the urea dissolving tank 1. A first pressure relief valve 106 is provided on the first pressure relief pipe 105. Because the power of the first urea pump 102 is constant, if the amount of urea required by the incinerator is small, the valve on the first main pipe 101 needs to be adjusted to a smaller position. At this time, the urea flow rate in the first main pipe 101 is small, while the power of the first urea pump 102 remains unchanged. This will cause the pressure in the first main pipe 101 between the first urea pump 102 and the valve to increase, eventually leading to pipe rupture or damage to the urea pump. Therefore, to avoid the above situation, the first pressure relief pipe 105 is provided in this embodiment. When the pressure inside the first main pipe 101 is high, that is, when the amount of urea required by the incinerator is low, the first pressure relief valve 106 is opened. At this time, some of the urea flows back to the urea dissolving tank 1 through the first pressure relief pipe 105, thereby reducing the pressure inside the first main pipe 101 and thus avoiding the occurrence of pipe rupture or urea pump damage.

[0039] To enable online inspection and maintenance of the first reducing agent pump 202 and to extend its service life, refer to Figure 2 Therefore, this embodiment also includes a second branch pipe 203. The two ends of the second branch pipe 203 are respectively connected to the second main pipe 201 at both ends of the first reducing agent pump 202. The second branch pipe 203 is equipped with a second reducing agent pump 204 for providing power and a corresponding valve. From the above structure, it can be seen that under normal circumstances, a one-for-one standby configuration is used. When one reducing agent pump fails or needs maintenance, the other pipeline is used for delivery, thus enabling online maintenance and repair of the reducing agent pumps. Furthermore, to avoid long-term high-load operation of a single reducing agent pump, the two reducing agent pumps can be used alternately under normal circumstances, thereby protecting the reducing agent pumps and effectively improving their service life.

[0040] This embodiment also includes a second pressure relief pipe 205 and a third pressure relief pipe 304. One end of the second pressure relief pipe 205 is connected to the second main pipe 201 between the first reducing agent pump 202 and the injection device 4, and the other end is connected to the urea storage tank 2. A second pressure relief valve 206 is provided on the second pressure relief pipe 205. One end of the third pressure relief pipe 304 is connected to the pipe between the first soft water pump 301 and the injection device 4, and the other end is connected to the soft water tank 3. A third pressure relief valve 305 is provided on the third pressure relief pipe 304. The second pressure relief pipe 205 and the third pressure relief pipe 304 operate in the same way and on the same principle as the first pressure relief pipe 105, both being used to reduce the pressure in the corresponding pipes. Referring to the first pressure relief pipe 105, the specific operating methods and principles of the second pressure relief pipe 205 and the third pressure relief pipe 304 will not be described in detail here.

[0041] To enable online inspection and maintenance of the first soft water pump 301 and to extend its service life, refer to Figure 2 Therefore, this embodiment also includes a third branch pipe 302. The two ends of the third branch pipe 302 are connected to the pipes at both ends of the first soft water pump 301. A second soft water pump 303 for providing power and a corresponding valve are installed on the third branch pipe 302. From the above structure, it can be seen that under normal circumstances, a one-for-one standby configuration is used. When one soft water pump fails or needs maintenance, the other pipeline is used for delivery, thus enabling online maintenance and repair of the soft water pumps. Furthermore, to avoid long-term high-load operation of a single soft water pump, the two soft water pumps can be used alternately under normal circumstances, thereby protecting the soft water pumps and effectively improving their service life.

[0042] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A urea system for reducing nitrogen oxide emissions in waste incineration flue gas, comprising a urea dissolving tank (1) for preparing urea and at least two injection devices (4) matching the number of incinerators, the injection devices (4) for injecting urea into the incinerators (5), compressed air being connected to each injection device (4) via pipes, and soft water being connected to each injection device (4) via a soft water tank (3), a first soft water pump for providing power being installed on the pipe connecting the soft water tank (3) and the injection device (4). (301), the urea dissolving tank (1) is connected to the urea storage tank (2) through the first main pipe (101), and the urea storage tank (2) is connected to the injection device (4) through the second main pipe (201). The first main pipe (101) is equipped with a first urea pump (102), and the second main pipe (201) is equipped with a first reducing agent pump (202). The injection device (4) includes a plurality of first nozzles (401) and second nozzles (402) arranged sequentially from bottom to top in the flue (6) of the incinerator. The injection device (4) is also provided with several third nozzles (403), which are arranged above the second nozzles (402) and are located at 28m to 32m from the first flue (6) of the incinerator.

2. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, The first nozzle (401), the second nozzle (402) and the third nozzle (403) are made of stainless steel.

3. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, The urea dissolving tank (1) is connected to a first branch pipe (103), the other end of which is connected to the first main pipe (101). The first branch pipe (103) is equipped with a second urea pump (104) for providing power and a corresponding valve.

4. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, The first main pipe (101) is connected to a first pressure relief pipe (105), the other end of which is connected to a urea dissolving tank (1), and a first pressure relief valve (106) is provided on the first pressure relief pipe (105).

5. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, It also includes a second branch pipe (203), the two ends of which are respectively connected to the second main pipe (201) at both ends of the first reducing agent pump (202). The second branch pipe (203) is equipped with a second reducing agent pump (204) for providing power and a corresponding valve.

6. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, It also includes a second pressure relief pipe (205), one end of which is connected to the second main pipe (201) between the first reducing agent pump (202) and the injection device (4), and the other end is connected to the urea storage tank (2). A second pressure relief valve (206) is provided on the second pressure relief pipe (205).

7. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, It also includes a third branch pipe (302), the two ends of which are connected to the pipes at both ends of the first soft water pump (301). The third branch pipe (302) is equipped with a second soft water pump (303) for providing power and a corresponding valve.

8. The urea system for reducing nitrogen oxide emissions in waste incineration flue gas as described in claim 1, characterized in that, It also includes a third pressure relief pipe (304), one end of which is connected to the pipeline between the first soft water pump (301) and the jetting device (4), and the other end is connected to the soft water tank (3). A third pressure relief valve (305) is provided on the third pressure relief pipe (304).

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