Method for controlling ozone escape in flue gas ozone denitration process
By managing ozone escape in the flue gas ozone denitrification process through real-time monitoring and collaborative control logic, the safety and environmental risks and equipment corrosion problems caused by ozone escape have been solved, achieving safe and efficient ozone escape control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
- Filing Date
- 2026-01-15
- Publication Date
- 2026-05-05
AI Technical Summary
The uncertainty in ozone escape control in existing flue gas ozone denitrification processes leads to safety and environmental risks, equipment corrosion, and conflicting control strategies. There is a lack of collaborative decision-making capabilities and a lack of online monitoring methods for escaped ozone.
By monitoring the NOx and ozone concentrations in the flue gas at the outlet of the denitrification system in real time, a collaborative control logic based on dual-objective state judgment is established to adjust the ozone dosage and activate the emergency destruction device, thereby achieving risk-level management of escaped ozone.
It achieves safe and rapid control of ozone escape while ensuring that pollutants are discharged in compliance with standards, reducing safety risks and equipment corrosion, and improving system response speed and stability.
Smart Images
Figure CN121971968A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flue gas purification technology, and more specifically, to a method for controlling ozone escape in a flue gas ozone denitrification process. Background Technology
[0002] Ozone denitrification technology is a promising technology for the synergistic removal of multiple pollutants, especially suitable for treating medium and low temperature flue gas. Its core principle is to use the strong oxidizing properties of ozone (O3) to oxidize nitric oxide (NO), which is insoluble in water, in the flue gas into nitrogen oxides that are easily soluble in water and then achieve efficient removal through an alkaline absorbent in the absorption tower.
[0003] However, this technology faces a key challenge in practical engineering applications: the control of ozone addition and the reaction process are uncertain. If excessive ozone is added, or if the reaction with flue gas is insufficient, unreacted ozone (i.e., "escaping ozone") will enter downstream equipment and chimneys with the flue gas. The following shortcomings exist: (1) Safety and environmental risks: Ozone is a highly oxidizing and toxic gas. Its escape and emission violate environmental protection regulations and pose a direct threat to the surrounding ecological environment and human health, forming a secondary pollution source.
[0004] (2) Equipment corrosion: The strong oxidizing properties of ozone will accelerate the corrosion of downstream flues and chimneys, significantly increasing maintenance costs.
[0005] (3) Isolated and contradictory control strategies: Existing process control strategies mainly rely on the NOx concentration at the inlet and / or outlet to adjust the ozone dosage with a single objective (denitrification efficiency) optimization, ignoring the independent monitoring and handling of escaped ozone. When the goals of pursuing high denitrification efficiency (requiring increased ozone) conflict with ensuring operational safety (requiring reduced ozone escape), the system lacks collaborative decision-making capabilities, resulting in either substandard denitrification efficiency or accumulated safety risks.
[0006] (4) Lack of monitoring methods: The existing industrial flue gas continuous emission monitoring system (CEMS) is generally not equipped with online ozone escape monitoring instruments, making it impossible for operators to understand the risk status of ozone escape. Summary of the Invention
[0007] The technical problem to be solved by this invention is to provide a method for controlling ozone escape in a flue gas ozone denitrification process. By introducing real-time monitoring and risk classification of escaped ozone, a collaborative control logic based on NOx concentration and ozone concentration status judgment is established to achieve optimal control of the safety risk of escaped ozone while ensuring that pollutants are discharged in compliance with standards. The solution adopted by this invention to solve the technical problem is: A method for controlling ozone escape in a flue gas ozone denitrification process, specifically referring to: The NOx concentration value in the flue gas at the outlet of the denitrification system obtained by real-time monitoring is compared with the preset emission standard value to determine whether the denitrification efficiency status is "compliant" or "exceeds the standard"; the ozone concentration value in the flue gas at the outlet of the denitrification system obtained by real-time monitoring is compared with the preset ozone emission standard to determine whether the ozone escape status is "compliant" or "exceeds the standard". If the NOx concentration exceeds the standard, adjust and increase the ozone dosage, and adjust the operating status of the ozone destruction device connected to the denitrification system according to the ozone concentration. If the NOx concentration meets the standard but the ozone concentration exceeds the standard, adjust and reduce the ozone dosage and adjust the operating status of the ozone destruction device.
[0008] In some possible implementations, the formula for calculating the ozone dosage is: ; in, This refers to the amount of ozone added. F represents the flow rate of the flue gas at the inlet of the denitrification system under standard dry conditions and reference oxygen content; k is the adjustment coefficient; M O3 This represents the relative molecular weight of ozone. M NOx This represents the relative molecular weight of NOx. C NOx The NOx concentration value of the outlet flue gas of the denitrification system under standard dry conditions and reference oxygen content; C 标准 This is to set the NOx emission standard for the outlet flue gas of the denitrification system under dry conditions and reference oxygen content.
[0009] In some possible implementations, when the calculation result obtained by the calculation formula is positive, the operation is to increase the ozone dosage; when the calculation result obtained by the calculation formula is negative, the operation is to decrease the ozone dosage.
[0010] In some possible implementations, the statement that if the NOx concentration exceeds the standard, the ozone dosage is adjusted and increased, and the operating status of the ozone destruction device connected to the denitrification system is adjusted according to the ozone concentration; specifically, this means: When both NOx and ozone concentrations exceed the standard, increase the ozone dosage and activate the ozone emergency destruction device to operate at full capacity.
[0011] Increase the ozone dosage when the NOx concentration exceeds the standard but the ozone concentration meets the standard.
[0012] In some possible implementations, the statement that if the NOx concentration meets the standard but the ozone concentration exceeds the standard, the ozone dosage is adjusted and reduced to adjust the operating status of the ozone destruction device; specifically, this means: If the NOx concentration meets the standard but the ozone concentration exceeds the standard at the same time, the ozone concentration will be compared with the preset first-level, second-level, and third-level concentration thresholds to determine whether the risk level of escaped ozone is a first-level warning, a second-level warning, or a third-level warning. If the risk level of ozone escape is a Level 1 warning, reduce the amount of ozone added. If the risk level of escaped ozone is a Level II warning, reduce the ozone dosage and activate the ozone emergency destruction device to operate at a low level. If the risk level of escaped ozone is a Level III warning, reduce the ozone dosage and activate the ozone emergency destruction device to operate at a high level.
[0013] In some possible implementations, the low-level operation specifically refers to the ozone emergency destruction device operating at 10-50% load.
[0014] In some possible implementations, the high-level operation specifically refers to the ozone emergency destruction device operating at 50-100% load.
[0015] In some possible implementations, if both NOx and ozone concentrations meet the standards, the process parameters are diagnosed: If the process parameters are abnormal, an early warning message will be output. If the process parameters are normal, maintain the current state.
[0016] In some possible implementations, the process parameters include ozone dosage, flow rate of flue gas at the inlet of the denitrification reaction system, temperature of flue gas at the inlet of the denitrification reaction system, oxygen content of flue gas at the inlet of the denitrification reaction system, and NOx concentration of flue gas at the inlet of the denitrification reaction system.
[0017] In some possible implementations, a monitoring component one is provided at the inlet end of the denitrification reaction system for real-time monitoring of the flow rate, NOx concentration, temperature, pressure, moisture content, and oxygen content of the flue gas entering the denitrification reaction system, and a monitoring component two is provided at the outlet end of the denitrification reaction system for real-time monitoring of the NOx concentration, temperature, pressure, moisture content, oxygen content, and ozone concentration in the flue gas exiting the denitrification system.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses the ozone concentration value in the flue gas at the outlet of the denitrification system and the ozone concentration value in the flue gas at the outlet of the denitrification system as control targets, and establishes a collaborative control logic based on dual-target state judgment to achieve optimal control of the safety risk of escaped ozone while ensuring that pollutants are discharged in compliance with standards. This invention improves the safety response speed by tens of times compared to relying on manual response or slow process adjustment by real-time identification and automatic intervention of ozone escape risk, and can effectively prevent ozone emission accidents exceeding the standard. This invention addresses different levels of ozone escape risk by employing differentiated measures, ranging from adjusting ozone dosage to activating emergency devices in stages, to ensure precise response and avoid significant system fluctuations. Attached Figure Description
[0019] Figure 1 This is a flowchart of the process of the present invention. Detailed Implementation
[0020] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0021] The present invention will now be described in detail.
[0022] like Figure 1 As shown: A method for controlling ozone escape in a flue gas ozone denitrification process, specifically referring to: The NOx concentration value in the flue gas at the outlet of the denitrification system obtained by real-time monitoring is compared with the preset emission standard value to determine whether the denitrification efficiency status is "compliant" or "exceeds the standard"; the ozone concentration value in the flue gas at the outlet of the denitrification system obtained by real-time monitoring is compared with the preset ozone emission standard to determine whether the ozone escape status is "compliant" or "exceeds the standard". If the NOx concentration exceeds the standard, adjust and increase the ozone dosage, and adjust the operating status of the ozone destruction device connected to the denitrification system according to the ozone concentration; specifically: When both NOx and ozone concentrations exceed the standard, increase the ozone dosage and activate the ozone emergency destruction device to operate at full capacity.
[0023] Increase the ozone dosage when the NOx concentration exceeds the standard but the ozone concentration meets the standard.
[0024] If the NOx concentration meets the standard but the ozone concentration exceeds the standard, adjust and reduce the ozone dosage, and adjust the operating status of the ozone destruction device; specifically: When the NOx concentration meets the standard and the ozone concentration exceeds the standard, the ozone concentration is compared with the preset first-level, second-level, and third-level concentration thresholds to determine whether the risk level of escaped ozone is a first-level warning, a second-level warning, or a third-level warning. When the risk level of escaped ozone is at Level 1 warning, reduce the amount of ozone added. When the risk level of escaped ozone is a Level II warning, reduce the amount of ozone added and activate the ozone emergency destruction device to operate at a low level. When the risk level of escaped ozone is at Level III warning, reduce the amount of ozone added and activate the ozone emergency destruction device to operate at a high level.
[0025] If both NOx and ozone concentrations meet the standards, the process parameters should be diagnosed. When process parameters are abnormal, an early warning message will be output. If the process parameters are normal, maintain the current state. The process parameters include ozone dosage, flow rate of flue gas at the inlet of the denitrification reaction system, temperature of flue gas at the inlet of the denitrification reaction system, oxygen content of flue gas at the inlet of the denitrification reaction system, and NOx concentration of flue gas at the inlet of the denitrification reaction system.
[0026] In some possible implementations, the low-level operation specifically refers to the ozone emergency destruction device operating at 10-50% load.
[0027] In some possible implementations, the high-level operation specifically refers to the ozone emergency destruction device operating at 50-100% load.
[0028] In some possible implementations, the formula for calculating the ozone dosage is: ; in, This refers to the amount of ozone added. F represents the flow rate of the flue gas at the inlet of the denitrification system under standard dry conditions and reference oxygen content; k is the adjustment coefficient; M O3 This represents the relative molecular weight of ozone. M NOx This represents the relative molecular weight of NOx. C NOx The NOx concentration value of the outlet flue gas of the denitrification system under standard dry conditions and reference oxygen content; C 标准 To meet the NOx emission standards for the outlet flue gas of denitrification systems under dry conditions and reference oxygen content; When the calculation result obtained by the formula is positive, the ozone dosage is increased; when the calculation result obtained by the formula is negative, the ozone dosage is decreased.
[0029] In some possible implementations, a monitoring component one is provided at the inlet end of the denitrification reaction system for real-time monitoring of the flow rate, NOx concentration, temperature, pressure, moisture content, and oxygen content of the flue gas entering the denitrification reaction system, and a monitoring component two is provided at the outlet end of the denitrification reaction system for real-time monitoring of the NOx concentration, temperature, pressure, moisture content, oxygen content, and ozone concentration in the flue gas exiting the denitrification system.
[0030] Example 1: In this embodiment, an industrial flue gas purification system employs a denitrification process combining ozone oxidation and semi-dry absorption. The flue gas volume is 500,000 Nm³ under standard dry conditions and reference oxygen content. 3 / h, the local NOx emission requirement under standard dry conditions and baseline oxygen content is 50 mg / Nm³. 3 The NOx emission standard for the pre-set outlet of the denitrification reaction system is 45 mg / Nm³. 3 The ozone emission requirement is 2 ppm, and the preset ozone emission standard for the denitrification reaction system outlet is 1.5 ppm. The adjustment coefficient k is set to 1.5; among which, the first-level warning threshold is 1.5 ppm, the second-level warning threshold is 3.0 ppm, and the third-level warning threshold is 10.0 ppm; Monitoring component two is installed in the flue on the outlet side of the denitrification reaction system, and an ozone destruction device is deployed in the flue downstream of monitoring component two.
[0031] When C is obtained through monitoring NOx When the concentration of NOx reaches 65 mg / Nm³, the NOx concentration exceeds the standard. Simultaneously, C... O3 If the concentration is 4.0 ppm, then the ozone concentration exceeds the standard. The following operations will be performed, calculating the required increase in ozone dosage Δ according to the formula. O3 : Δ O3 =50×10 4× (65-45) × 1.5 × 10 -6 ×48 / 30 = +24 kg / h; At the same time, the ozone emergency destruction device was activated to 100% load.
[0032] When C is obtained through monitoring NOx When the concentration of NOx reaches 65 mg / Nm³, the NOx concentration exceeds the standard; simultaneously, C is monitored and obtained. O3 =1.0ppm, then the ozone concentration value meets the standard; The following operations will be performed, calculating the required increase in ozone dosage Δ according to the formula. O3 =+24kg / h.
[0033] When C is obtained through monitoring NOx =40mg / Nm³, then the NOx concentration exceeds the standard; at the same time, C was monitored and obtained O3 =4ppm, at which point a level 2 warning will be issued; Perform the following operations and calculate, according to the formula, the required reduction in ozone dosage Δ O3 =-6kg / h; at the same time, activate the ozone emergency destruction device to 40% load.
[0034] When monitoring obtains C NOx =40mg / Nm³, then the NOx concentration value meets the standard. When the monitoring obtains C O3 =11ppm, a Level 3 warning will be issued; perform the following operations, and calculate according to the formula, the ozone dosage needs to be reduced by Δ. O3 =-6kg / h, and at the same time, activate the ozone emergency destruction device to 50% load.
[0035] When monitoring obtains C NOx =40mg / Nm³, then the NOx concentration exceeds the standard, and C is monitored at the same time. O3 =1.0ppm, then the ozone concentration value meets the standard; dynamic analysis will be carried out, and it was found that the flue gas temperature dropped sharply by 20℃ while the ozone dosage remained unchanged. Then, a yellow warning was output on the operation interface: "Temperature abnormal, pay attention to ozone reaction efficiency".
[0036] This invention compares the escaped ozone concentration with at least two incremental thresholds, classifying it into multiple risk levels such as "Level 1 Warning," "Level 2 Warning," and "Level 3 Warning." Based on the risk level, it adopts a tiered approach, including "ozone reduction only," "ozone reduction + low-level damage," and "ozone reduction + high-level damage." By establishing a collaborative control logic based on dual-objective (NOx compliance and O3 safety) status judgment, it achieves optimal control of the safety risk of escaped ozone while ensuring that pollutants are discharged in compliance with standards.
[0037] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.
Claims
1. A method for controlling ozone escape in a flue gas ozone denitrification process, characterized in that, The NOx concentration value in the flue gas at the outlet of the denitrification system obtained by real-time monitoring is compared with the preset emission standard value to determine whether the denitrification efficiency status is "compliant" or "exceeds the standard"; the ozone concentration value in the flue gas at the outlet of the denitrification system obtained by real-time monitoring is compared with the preset ozone emission standard to determine whether the ozone escape status is "compliant" or "exceeds the standard". If the NOx concentration exceeds the standard, adjust and increase the ozone dosage, and adjust the operating status of the ozone destruction device connected to the denitrification system according to the ozone concentration. If the NOx concentration meets the standard but the ozone concentration exceeds the standard, adjust and reduce the ozone dosage and adjust the operating status of the ozone destruction device.
2. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 1, characterized in that, The formula for calculating the ozone dosage is as follows: ； in, This refers to the amount of ozone added. F represents the flow rate of the flue gas at the inlet of the denitrification system under standard dry conditions and reference oxygen content; k is the adjustment coefficient; M O3 This represents the relative molecular weight of ozone. M NOx This represents the relative molecular weight of NOx. C NOx The NOx concentration value of the outlet flue gas of the denitrification system under standard dry conditions and reference oxygen content; C 标准 This is to set the NOx emission standard for the outlet flue gas of the denitrification system under dry conditions and reference oxygen content.
3. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 2, characterized in that, When the calculation result obtained by the formula is positive, the ozone dosage is increased; when the calculation result obtained by the formula is negative, the ozone dosage is decreased.
4. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 1, characterized in that, The aforementioned adjustment and increase of ozone dosage if the NOx concentration exceeds the standard, and adjustment of the operating status of the ozone destruction device connected to the denitrification system according to the ozone concentration; specifically refers to: When both NOx and ozone concentrations exceed the standard, increase the ozone dosage and activate the ozone emergency destruction device to operate at full capacity. Increase the ozone dosage when the NOx concentration exceeds the standard but the ozone concentration meets the standard.
5. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 1, characterized in that, The statement that if the NOx concentration meets the standard but the ozone concentration exceeds the standard, the ozone dosage will be adjusted and reduced to adjust the operating status of the ozone destruction device; specifically, this means: If the NOx concentration meets the standard but the ozone concentration exceeds the standard at the same time, the ozone concentration will be compared with the preset first-level, second-level, and third-level concentration thresholds to determine whether the risk level of escaped ozone is a first-level warning, a second-level warning, or a third-level warning. If the risk level of ozone escape is a Level 1 warning, reduce the amount of ozone added. If the risk level of escaped ozone is a Level II warning, reduce the ozone dosage and activate the ozone emergency destruction device to operate at a low level. If the risk level of escaped ozone is a Level III warning, reduce the ozone dosage and activate the ozone emergency destruction device to operate at a high level.
6. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 5, characterized in that, The aforementioned low-level operation specifically refers to the ozone emergency destruction device operating at 10-50% load.
7. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 5, characterized in that, The aforementioned high-level operation specifically refers to the ozone emergency destruction device operating at 50-100% load.
8. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 1, characterized in that, If both NOx and ozone concentrations meet the standards, the process parameters should be diagnosed. If the process parameters are abnormal, an early warning message will be output. If the process parameters are normal, maintain the current state.
9. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 8, characterized in that, The process parameters include ozone dosage, flow rate of flue gas at the inlet of the denitrification reaction system, temperature of flue gas at the inlet of the denitrification reaction system, oxygen content of flue gas at the inlet of the denitrification reaction system, and NOx concentration of flue gas at the inlet of the denitrification reaction system.
10. The method for controlling ozone escape in a flue gas ozone denitrification process according to claim 1, characterized in that, The inlet of the denitrification reaction system is equipped with a monitoring component 1 for real-time monitoring of the flow rate, NOx concentration, temperature, pressure, moisture content, and oxygen content of the flue gas entering the denitrification reaction system, and a monitoring component 2 is installed at the outlet of the denitrification reaction system for real-time monitoring of the NOx concentration, temperature, pressure, moisture content, oxygen content, and ozone concentration of the flue gas exiting the denitrification system.