System for leveling and controlling molar ratio of ammonia to nitrogen at inlet of denitration device

Abstract

The utility model discloses an inlet ammonia nitrogen molar ratio leveling control system of a denitration device, which is characterized in that an ammonia spraying section is divided into n ammonia spraying subareas for subarea ammonia spraying, an upstream section of a first-layer catalyst at a denitration inlet is used as an ammonia nitrogen measuring section, and the ammonia nitrogen measuring section is divided into n ammonia nitrogen measuring subareas, a partition NOx / NH3 measurement system is installed on an ammonia nitrogen measurement section to measure the ammonia nitrogen molar ratio of NOx and NH3 of each ammonia nitrogen measurement partition, and the ammonia nitrogen molar ratio is used as a feedback value for automatically adjusting the ammonia spraying amount of each partition, so that the relative standard deviation of the ammonia nitrogen molar ratio of the first-layer catalyst section is not larger than 5%. According to the utility model, the partition NOx / NH3 measuring system is arranged on the upstream section of the first-layer catalyst to perform partition measurement on the ammonia nitrogen ratio, so that the influence of the large hysteresis characteristic in the denitration process on the denitration partition ammonia injection adjusting effect is weakened or even eliminated, the ammonia injection uniformity is fundamentally ensured, and the accuracy of the total ammonia injection amount control is improved; simplicity, convenience, easy transformation and high reliability are realized.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification technology in large coal-fired power plants, and in particular to a control system for adjusting the inlet ammonia-nitrogen molar ratio of a denitrification device. Background Technology

[0002] Currently, large coal-fired power plants commonly use SCR (Selective Catalytic Reduction) denitrification devices to reduce NOx emission concentrations in flue gas. SCR utilizes the reduction properties of NH3 on NOx, reducing it to environmentally harmless N2 and H2O under the action of a catalyst. In actual operation, controlling the ammonia injection rate is crucial. Increasing the ammonia injection rate helps reduce NOx emission concentrations, but it also increases the ammonia slip rate, which can easily cause blockage and corrosion of downstream air preheaters due to ammonium bisulfate deposition. It can also lead to adverse effects such as ash accumulation on electrostatic precipitator electrodes and ash adhesion to filter bags.

[0003] Regarding ammonia injection control, on the one hand, it is required to reasonably control the total amount of ammonia injected, and on the other hand, it is required to ensure the uniformity of ammonia injection (mainly referring to the relatively uniform ammonia-nitrogen molar ratio) so as to ensure that the NOx emission concentration meets the standard within the allowable ammonia slip rate range.

[0004] Ammonia injection total quantity control generally uses the measured NOx concentration at the SCR outlet as a feedback signal to adjust the ammonia injection total quantity control valve (usually one on each side). However, current SCR outlet NOx concentration is generally measured at a single point; single-point measurements have poor representativeness and cannot reflect the average NOx concentration at the SCR outlet, thus failing to fully characterize whether the ammonia injection total quantity is appropriate. Furthermore, current SCR outlet NOx concentration is generally measured using CEMS, which also suffers from long hysteresis times and high maintenance workload.

[0005] Ammonia injection uniformity is generally achieved through manual adjustment of several ammonia injection manual control valves (typically 8-40 per side). These valves are located downstream of the total ammonia injection control valve, and their adjustment is primarily based on on-site measurements of the NOx concentration distribution at the SCR outlet. In areas with locally high NOx concentrations, the corresponding upstream AIG (ammonia injection adjustment device) manual control valve is opened wider, and vice versa. This repeated adjustment ensures a relatively uniform NOx concentration distribution at the SCR outlet. If the SCR catalyst module shows no obvious wear, collapse, or ash blockage, then the ammonia injection uniformity is guaranteed.

[0006] In recent years, denitrification zone ammonia injection control technology has seen significant development, used to regulate the uniformity of NOx concentration distribution in SCR outlet zones and reduce the workload of manually adjusting ammonia injection valves. The core module of the denitrification zone ammonia injection system is the denitrification outlet zone NOx measurement system. Automatic adjustment of zone ammonia injection is based on the measured NOx values ​​of the zone. When the NOx concentration in a zone is high, the opening of the corresponding upstream ammonia injection zone's balancing valve increases, and vice versa. However, due to the significant hysteresis characteristic of the denitrification process, after the upstream ammonia injection zone's injection rate is adjusted, the NOx value obtained by the downstream zone's NOx measurement system cannot promptly and accurately reflect the adjustment effect, resulting in poor current denitrification zone ammonia injection control performance. Utility Model Content

[0007] In order to improve the control effect of ammonia injection in denitrification zones and weaken or even eliminate the influence of the large hysteresis characteristics of the denitrification process on the adjustment effect of ammonia injection in denitrification zones, this utility model provides a denitrification device inlet ammonia nitrogen molar ratio balancing control system.

[0008] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0009] A method for balancing and controlling the ammonia-nitrogen molar ratio at the inlet of a denitrification unit involves dividing the ammonia injection section into n ammonia injection zones for zoned ammonia injection, dividing the upstream section of the first-layer catalyst at the denitrification inlet into n ammonia-nitrogen measurement zones, and using the ammonia-nitrogen molar ratio of each ammonia-nitrogen measurement zone as feedback value for automatically adjusting the ammonia injection amount of each zone, so that the ammonia-nitrogen molar ratio of the first-layer catalyst section is controlled within the range of 0.90-0.99, and the relative standard deviation of the ammonia-nitrogen molar ratio of the first-layer catalyst section is not greater than 5%.

[0010] The above method uses the ammonia-nitrogen molar ratio measured at the denitrification inlet as feedback value to automatically adjust the ammonia injection amount in each zone, completely avoiding the influence of the large hysteresis characteristic of the denitrification process, and is conducive to significantly improving the real-time performance of ammonia injection control in the denitrification zones.

[0011] The aforementioned first-layer catalyst cross-section refers to the cross-section before entering the first-layer catalyst.

[0012] To improve the accuracy of feedback, the interval between each ammonia nitrogen measurement zone and the first layer of catalyst is 0–100 cm, and more preferably 20–80 cm.

[0013] The ammonia nitrogen molar ratio for each ammonia nitrogen measurement zone is measured by taking samples from each zone in a rotating manner to measure the concentrations of NOx and NH3, thus obtaining the ammonia nitrogen molar ratio for each zone. The units for NOx and NH3 concentrations are mol / L, and the ratio of NOx to NH3 concentrations in each ammonia nitrogen measurement zone is also the ammonia nitrogen molar ratio for that zone.

[0014] The above n ammonia injection zones correspond one-to-one with n ammonia nitrogen measurement zones. The ammonia nitrogen molar ratio of the ammonia nitrogen measurement zone is used as the feedback value for automatically adjusting the ammonia injection amount of the corresponding zone, which weakens or even eliminates the influence of the large hysteresis characteristics of the denitrification process on the ammonia injection regulation effect of the denitrification zone.

[0015] A denitrification unit inlet ammonia nitrogen molar ratio leveling control system divides the ammonia injection section into n ammonia injection zones for zoned ammonia injection. The upstream section of the first-layer catalyst at the denitrification inlet is used as the ammonia nitrogen measurement section, which is further divided into n ammonia nitrogen measurement zones. A zoned NOx / NH3 measurement system is installed on the ammonia nitrogen measurement section to measure the NOx and NH3 concentrations in each ammonia nitrogen measurement zone. The ratio of the NOx and NH3 concentrations in each ammonia nitrogen measurement zone is the ammonia nitrogen molar ratio of that zone. The ammonia nitrogen molar ratio of each ammonia nitrogen measurement zone is used as the feedback value for automatically adjusting the ammonia injection amount in each zone, so that the relative standard deviation of the ammonia nitrogen molar ratio of the first-layer catalyst section is not greater than 5%.

[0016] This application installs the zoned NOx / NH3 measurement system before the denitrification catalyst, which is not affected by the large hysteresis characteristics of the denitrification process, and is conducive to significantly improving the real-time performance of the denitrification zone ammonia injection control.

[0017] Ammonia injection grid is installed on the ammonia injection section, which is located in the flue between the economizer outlet and the SCR reactor inlet. A static mixer is installed downstream of the ammonia injection unit to promote uniform mixing of NOx and NH3. The aforementioned zoned NOx / NH3 measurement system is located between the first-layer catalyst and the static mixer, and close to the first-layer catalyst.

[0018] The concentrations of NOx and NH3 mentioned above are in mol / L.

[0019] To improve the accuracy of the feedback, the distance between the ammonia nitrogen measurement section and the first layer of catalyst is 0–100 cm.

[0020] The above n ammonia injection zones correspond one-to-one with the n ammonia nitrogen measurement zones, and the ammonia nitrogen molar ratio of the ammonia nitrogen measurement zones is used as the feedback value for automatically adjusting the ammonia injection amount of the corresponding zones.

[0021] To facilitate sampling while ensuring environmental protection and denitrification effectiveness, the flue gas measured by the zoned NOx / NH3 measurement system is piped between the first-layer catalyst at the denitrification inlet and the last-layer catalyst at the denitrification outlet. This allows for automatic sampling under flue gas pressure, eliminating the need for power equipment (although power equipment can be installed for specific operating conditions). Furthermore, the sampled gas returns to the denitrification catalyst layer for further denitrification, resulting in energy savings and environmental friendliness.

[0022] As is common knowledge, SCR denitrification devices install multiple layers of catalyst between the denitrification inlet and the denitrification outlet. From upstream to downstream, the first layer of catalyst is the first layer of catalyst at the denitrification inlet, and the last layer of catalyst is the last layer of catalyst at the denitrification outlet. Flue gas measured by the zoned NOx / NH3 measurement system is passed through pipelines between the first layer of catalyst at the denitrification inlet and the last layer of catalyst at the denitrification outlet to ensure denitrification effect and stability.

[0023] To improve measurement accuracy, the zoned NOx / NH3 measurement system includes zoned sampling tubes, thickened mixing tubes, delivery tubes, an online NOx analyzer, and an ammonia slip measurement and analysis instrument.

[0024] The sampling tubes are installed inside the flue, while the thickened mixing tube, delivery tube, NOx online analyzer, and ammonia slip measurement analyzer are all installed outside the flue; the thickened mixing tube has a sealed structure with both ends sealed.

[0025] Each ammonia nitrogen measurement zone is equipped with a zone sampling pipe, which is connected to the thickened mixing pipe outside the flue through a connecting pipe. Each connecting pipe is equipped with a corresponding control valve. One end of the delivery pipe is connected to the bottom of the thickened mixing pipe, and the other end is connected between the first layer catalyst at the denitrification inlet and the last layer catalyst at the denitrification outlet. The NOx online analyzer and the ammonia slip measurement analyzer are located on the delivery pipe outside the SCR outlet flue. The inner diameter of the thickened mixing pipe is more than twice the inner diameter of the connecting pipe and the delivery pipe.

[0026] The above-mentioned design of thickening the mixing tube improves the uniformity of the sampled gas, enhances the accuracy of instrument measurements, mitigates the impact of the sample gas on the instrument, and extends the instrument's service life.

[0027] The NOx online analyzer and ammonia slip measurement analyzer in this application can be replaced by an integrated ammonia nitrogen meter.

[0028] The sampling tubes for each of the above zones are set up in parallel.

[0029] To improve measurement accuracy, the sampling tubes for each zone extend from one end of the flue to the other.

[0030] To improve measurement accuracy and extend instrument lifespan, each zone sampling tube has a circular sampling hole with a diameter of 1.0–1.5 cm spaced 30–90 cm away from the airflow. One side of each zone sampling tube faces the airflow, while the other side faces away from it. This design reduces the impact of dust on measurement and instrument lifespan.

[0031] As is common sense, an air preheater is connected to the bottom of the SCR outlet flue.

[0032] Each of the above-mentioned ammonia injection zones is equipped with a corresponding ammonia injection grid, and the ammonia injection volume of each ammonia injection grid is adjusted by the ammonia injection zone leveling valve.

[0033] Any technologies not mentioned in this utility model are based on existing technologies.

[0034] This utility model's inlet ammonia-nitrogen molar ratio leveling control system for a denitrification device measures the ammonia-nitrogen ratio in zones at the upstream section of the first-layer catalyst. This measurement serves as feedback for automatically adjusting the ammonia injection amount in each zone, ensuring that the relative standard deviation of the ammonia-nitrogen molar ratio at the first-layer catalyst section is no greater than 5%. This weakens or even eliminates the impact of the large hysteresis characteristic of the denitrification process on the ammonia injection regulation effect in the denitrification zones, fundamentally ensuring the uniformity of ammonia injection and improving the accuracy of total ammonia injection control. The system is simple, convenient, easy to modify, and highly reliable. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the inlet ammonia-nitrogen molar ratio leveling control system of the denitrification device of this utility model.

[0036] Figure 2 for Figure 1 Left view schematic diagram of the NOx / NH3 measurement system in the middle zone.

[0037] In the diagram, 1 is the air preheater, 2 is the SCR, 21 is the denitrification inlet, 22 is the SCR outlet flue, 23 is the first-layer catalyst, 24 is the last-layer catalyst, 3 is the zoned NOx / NH3 measurement system, 31 is the zoned sampling pipe, 32 is the thickening mixing pipe, 33 is the conveying pipe, 34 is the NOx online analyzer, 35 is the ammonia slip measurement and analysis instrument, 36 is the control valve, and 4 is the economizer outlet flue. Detailed Implementation

[0038] To better understand this utility model, the following embodiments further illustrate its content, but the content of this utility model is not limited to the following embodiments.

[0039] The directional terms used in this application, such as up and down, left and right, top and bottom, front and back, are all based on the relative orientations or positional relationships shown in the attached drawings and should not be construed as absolute limitations on this application.

[0040] Example 1

[0041] A method for controlling the ammonia-nitrogen molar ratio at the inlet of a denitrification unit involves dividing the ammonia injection cross-section into n ammonia injection zones for zoned ammonia injection, and dividing the upstream cross-section of the first-layer catalyst at the denitrification inlet into n ammonia-nitrogen measurement zones. Each of the n ammonia injection zones corresponds one-to-one with one of the n ammonia-nitrogen measurement zones. The ammonia-nitrogen molar ratio of each measurement zone is used as feedback value for automatically adjusting the ammonia injection amount in that zone, ensuring that the ammonia-nitrogen molar ratio of the first-layer catalyst cross-section is controlled within the range of 0.90-0.99, with a relative standard deviation of no more than 5%. To improve the accuracy of the feedback, the interval between each ammonia-nitrogen measurement zone and the first-layer catalyst is 50 cm. The ammonia-nitrogen molar ratio of each measurement zone is measured by sampling and measuring the concentrations of NOx and NH3 in each zone in a cyclical manner. The units for NOx and NH3 concentrations are mol / L, and the ratio of NOx to NH3 concentrations in each measurement zone is also the ammonia-nitrogen molar ratio of that zone.

[0042] The above method uses the ammonia-nitrogen molar ratio measured at the denitrification inlet as feedback value to automatically adjust the ammonia injection amount in each zone, completely avoiding the influence of the large hysteresis characteristic of the denitrification process, and is conducive to significantly improving the real-time performance of ammonia injection control in the denitrification zones.

[0043] Example 2

[0044] like Figure 1 As shown, a denitrification unit inlet ammonia nitrogen molar ratio leveling control system divides the ammonia injection section into n ammonia injection zones for zoned ammonia injection. The upstream section of the first-layer catalyst at the denitrification inlet is used as the ammonia nitrogen measurement section, which is further divided into n ammonia nitrogen measurement zones. A zoned NOx / NH3 measurement system is installed on the ammonia nitrogen measurement section to measure the concentrations of NOx and NH3 (in mol / L) in each ammonia nitrogen measurement zone. The ratio of NOx to NH3 concentrations in each ammonia nitrogen measurement zone is the ammonia nitrogen molar ratio of that zone. The ammonia nitrogen molar ratio of each ammonia nitrogen measurement zone is used as the feedback value for automatically adjusting the ammonia injection amount in each zone, so that the relative standard deviation of the ammonia nitrogen molar ratio of the first-layer catalyst section is not greater than 5%.

[0045] Ammonia injection grid is installed on the ammonia injection section, which is located in the flue between the economizer outlet and the SCR reactor inlet. A static mixer is installed downstream of the ammonia injection unit to promote uniform mixing of NOx and NH3. The aforementioned zoned NOx / NH3 measurement system is located between the first-layer catalyst and the static mixer, and close to the first-layer catalyst.

[0046] The aforementioned installation of the zoned NOx / NH3 measurement system before the denitrification catalyst is unaffected by the large hysteresis characteristic of the denitrification process, which is beneficial to significantly improving the real-time performance of ammonia injection control in the denitrification zone.

[0047] Example 3

[0048] Based on Example 2, the following improvements were made: To improve the accuracy of feedback, the interval between the ammonia nitrogen measurement section and the first-layer catalyst was 50 cm. Each of the n ammonia injection zones corresponds one-to-one with one of the n ammonia nitrogen measurement zones, and the ammonia nitrogen molar ratio of the measurement zones is used as the feedback value for automatically adjusting the ammonia injection amount of the corresponding zone. To facilitate sampling while ensuring environmental protection and denitrification efficiency, the flue gas measured by the zoned NOx / NH3 measurement system is piped between the first-layer catalyst at the denitrification inlet and the last-layer catalyst at the denitrification outlet. In this example, there are three catalyst layers, and the measured flue gas is piped between the second and third catalyst layers. This allows sampling to be completed automatically under the pressure of the flue gas, eliminating the need for power equipment. Furthermore, the measured sample gas returns to the denitrification catalyst layer for denitrification, resulting in energy savings and environmental friendliness.

[0049] Example 4

[0050] Based on Example 3, the following improvements were further made: Figure 2 As shown, to improve measurement accuracy, the zoned NOx / NH3 measurement system includes zoned sampling tubes, thickening mixing tubes, delivery tubes, an online NOx analyzer, and an ammonia slip measurement analyzer. The zoned sampling tubes are installed inside the flue, while the thickening mixing tubes, delivery tubes, online NOx analyzer, and ammonia slip measurement analyzer are all installed outside the flue. The thickening mixing tubes are sealed at both ends. Each ammonia nitrogen measurement zone is equipped with a zoned sampling tube (the interval between the zoned sampling tube and the first-layer catalyst is 50 cm), and each zoned sampling tube is connected to the flue via a connecting pipe. The external thickened mixing pipe has corresponding control valves on each connecting pipe. One end of the delivery pipe is connected to the bottom of the thickened mixing pipe, and the other end is introduced between the first layer catalyst at the denitrification inlet and the last layer catalyst at the denitrification outlet. In this example, there are three layers of catalyst, and the measured flue gas is introduced between the second and third layers of catalyst. The NOx online analyzer and ammonia slip measurement analyzer are located on the delivery pipe outside the SCR outlet flue. Alternatively, an integrated ammonia nitrogen meter can be used instead of the NOx online analyzer and ammonia slip measurement analyzer. The inner diameter of the thickened mixing pipe is five times the inner diameter of the connecting pipe and the delivery pipe. The design of the thickened mixing pipe improves the uniformity of the sampled gas, enhances the accuracy of instrument measurements, mitigates the influence of the sample gas on the instrument, and extends the instrument's service life.

[0051] The sampling tubes for each zone are arranged in parallel; each sampling tube extends from one end of the flue to the other; a circular sampling hole with a diameter of 1.2 cm is provided every 30 cm on the back side of each sampling tube. One side of each sampling tube faces the airflow, and the other side faces away from the airflow. This design reduces the impact of dust on measurement and instrument lifespan. Each ammonia injection zone is equipped with a corresponding ammonia injection grid, and the ammonia injection rate is adjusted by the ammonia injection zone leveling valve.

[0052] Example 5

[0053] Based on Example 4, the following improvements were made: Figure 1-2 As shown, in this example, n is 10. The ammonia-nitrogen molar ratio of each ammonia-nitrogen measurement zone is used as the feedback value for automatically adjusting the ammonia injection amount of each zone, so that the ammonia-nitrogen molar ratio of the first catalyst cross section is controlled within the range of 0.90-0.99, and the relative standard deviation of the ammonia-nitrogen molar ratio of the first catalyst cross section is no more than 5%. This completely solves the influence of the large hysteresis characteristics of the denitrification process on the ammonia injection adjustment effect of the denitrification zone, so that the total amount of ammonia injection and the uniformity of ammonia injection are accurately controlled, and NOx emissions meet the standards.

[0054] Comparative Example 1

[0055] Unlike Example 5, the ammonia nitrogen measurement section was set at the SCR outlet flue, and the delivery pipe was connected to the downstream flue of the zoned sampling pipe. This resulted in a significant hysteresis problem, and NOx emissions failed to meet standards.

[0056] The ammonia-nitrogen molar ratio balancing control system at the inlet of the denitrification device in the above embodiments measures the ammonia-nitrogen ratio in zones at the upstream section of the first-layer catalyst. This measurement serves as feedback for automatically adjusting the ammonia injection amount in each zone, ensuring that the relative standard deviation of the ammonia-nitrogen molar ratio at the first-layer catalyst section is no greater than 5%. This weakens or even eliminates the impact of the large hysteresis characteristic of the denitrification process on the ammonia injection adjustment effect in the denitrification zones, fundamentally ensuring the uniformity of ammonia injection and improving the accuracy of total ammonia injection control. The system is simple, convenient, easy to modify, and highly reliable.

Claims

1. A denitrification device inlet ammonia-nitrogen molar ratio leveling control system, which divides the ammonia injection section into n ammonia injection zones for zoned ammonia injection, characterized in that: The upstream section of the first layer catalyst (23) at the denitrification inlet is used as the ammonia nitrogen measurement section. The ammonia nitrogen measurement section is divided into n ammonia nitrogen measurement zones. A zone NOx / NH3 measurement system (3) is installed on the ammonia nitrogen measurement section to measure the concentration of NOx and NH3 in each ammonia nitrogen measurement zone.

2. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification device according to claim 1, characterized in that: The interval between the ammonia nitrogen measurement section and the first catalyst layer (23) is 0~100cm.

3. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification device according to claim 1 or 2, characterized in that: There are n ammonia injection zones and n ammonia nitrogen measurement zones, and the ammonia nitrogen molar ratio of the ammonia nitrogen measurement zones is used as the feedback value for automatically adjusting the ammonia injection amount of the corresponding zone.

4. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification device according to claim 1 or 2, characterized in that: The flue gas measured by the NOx / NH3 measurement system (3) is introduced through a pipeline between the first layer catalyst at the denitrification inlet and the last layer catalyst at the denitrification outlet.

5. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification device according to claim 1 or 2, characterized in that: The zoned NOx / NH3 measurement system (3) includes a zoned sampling tube (31), a thickened mixing tube (32), a delivery tube (33), an online NOx analyzer (34), and an ammonia slip measurement analyzer (35); the zoned sampling tube (31) is installed inside the flue, while the thickened mixing tube (32), the delivery tube (33), the online NOx analyzer (34), and the ammonia slip measurement analyzer (35) are all installed outside the flue. The thickened mixing pipe (32) is a sealed structure with both ends sealed; each ammonia nitrogen measurement zone is equipped with a zone sampling pipe (31), and each zone sampling pipe (31) is connected to the thickened mixing pipe (32) outside the flue through a connecting pipe. Each connecting pipe is equipped with a corresponding control valve (36); one end of the conveying pipe (33) is connected to the bottom of the thickened mixing pipe (32), and the other end is connected between the first layer catalyst at the denitrification inlet and the last layer catalyst at the denitrification outlet; the NOx online analyzer (34) and the ammonia slip measurement analyzer (35) are located on the conveying pipe (33) outside the SCR outlet flue (22); the inner diameter of the thickened mixing pipe (32) is more than twice the inner diameter of the connecting pipe and the conveying pipe (33).

6. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification device according to claim 5, characterized in that: The sampling tubes (31) of each zone are set in parallel.

7. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification unit according to claim 5, characterized in that: Each sampling tube (31) runs from one end of the flue to the other end of the flue.

8. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification unit according to claim 5, characterized in that: Each sampling tube (31) in each zone has a circular sampling hole with a diameter of 1.0 to 1.5 cm every 30 to 90 cm on the back airflow side.

9. The inlet ammonia-nitrogen molar ratio balancing control system for the denitrification device according to claim 1 or 2, characterized in that: Each ammonia injection zone is equipped with a corresponding ammonia injection grid, and the ammonia injection volume of each ammonia injection grid is adjusted by the ammonia injection zone leveling valve.

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