An ammonia injection control method and system for an SCR denitration system of a power plant

Abstract

The application discloses an ammonia injection control method and system for an SCR denitration system of a power plant, and comprises the following steps: determining an initial total ammonia injection amount; correcting the initial total ammonia injection amount based on an inlet NOx concentration measured value, an outlet NOx concentration measured value, a desulfurization outlet NOx concentration measured value and an actual ammonia injection amount to obtain a target total ammonia injection amount; obtaining an initial ammonia injection amount of each subzone according to the target total ammonia injection amount and a flue gas flow rate of an outlet of each subzone; and correcting each initial ammonia injection amount according to an inlet flue gas total amount, the inlet NOx concentration measured value, the outlet NOx concentration measured value and an ammonia injection amount measured value of each subzone to obtain a target ammonia injection amount of each subzone. The application realizes mutual feedback correction of the total ammonia supply amount and the subzone ammonia injection amount, reduces the ammonia escape rate, can quickly feedback the flow rate measurement result, adjusts the subzone ammonia injection amount through the flow rate measurement mode, and avoids the influence of linear difference between the ammonia supply amount and the ammonia demand amount and large time lag caused by lagged measurement result.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a method and system for controlling ammonia injection in a power plant SCR denitrification system. Background Technology

[0002] In recent years, with the commissioning of denitrification units in power plants, the problem of ash accumulation and blockage in the low-temperature section of air preheaters due to NH4HSO4 deposition has become increasingly frequent. Especially since 2020, under the influence of deep peak shaving in thermal power plants, the unit load has fluctuated greatly, and the flue gas volume and NOx content have also fluctuated accordingly. The ammonia injection regulating branch valve in traditional ammonia injection methods is a manual valve. In order to improve ammonia injection efficiency and reduce ammonia escape, many power plants have also carried out ammonia injection optimization. However, since the regulating valve is a manual valve, this optimization is only for specific load operating conditions. After adjustment, the opening of the ammonia injection branch valve remains unchanged and cannot meet the ammonia injection demand after changes in load and operating conditions. To meet environmental protection requirements, excessive ammonia needs to be injected. However, excessive ammonia can easily react with SO3 in flue gas to form NH4HSO3 and NH4HSO4. Their deposition can not only cause blockage of the air preheater, but also adhere to the catalyst surface, reducing catalyst activity. Furthermore, NH4HSO3 is corrosive and can corrode the flue. Therefore, the existing SCR ammonia injection regulation system can no longer meet the needs of flexible unit operation, and many power plants are carrying out precision ammonia injection retrofit.

[0003] Currently, the main method for precision ammonia injection retrofitting is to divide the denitrification reactor into zones and install a CEMS measurement system in each zone to achieve precise ammonia injection. However, due to the relatively long sampling pipeline of the CEMS system, the measurement results lag by more than 2 minutes. This results in poor synchronization between the ammonia supply and the actual ammonia demand. In addition, the CEMS system uses single-point sampling, leading to poor representativeness of the measurement results.

[0004] Therefore, there is an urgent need to provide a technical solution to address the above problems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method and system for controlling ammonia injection in a power plant's SCR denitrification system.

[0006] The technical solution of the ammonia injection control method for a power plant SCR denitrification system according to the present invention is as follows:

[0007] Determine the initial total ammonia injection amount for the SCR denitrification system of the power plant, so that the SCR denitrification system of the power plant injects ammonia according to the initial total ammonia injection amount;

[0008] Based on the measured values ​​of NOx concentration at the SCR denitrification inlet, NOx concentration at the SCR denitrification outlet, and NOx concentration at the desulfurization outlet of the power plant's SCR denitrification system, and the actual ammonia injection amount, the initial total ammonia injection amount is corrected to obtain the target total ammonia injection amount.

[0009] Based on the target total ammonia injection and the flue gas velocity at the outlet of each section of the power plant's SCR denitrification system, the initial ammonia injection amount for each section is obtained. Then, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each section, the initial ammonia injection amount for each section is corrected to obtain the target ammonia injection amount for each section, so that each section injects ammonia according to the corresponding target ammonia injection amount.

[0010] The beneficial effects of the ammonia injection control method for a power plant SCR denitrification system of the present invention are as follows:

[0011] The method of this invention realizes mutual feedback correction between the total ammonia supply and the ammonia injection rate in different zones, reducing the ammonia escape rate and lowering operating costs; it can quickly provide feedback on the flow rate measurement results and adjust the ammonia injection rate in different zones by measuring the flow rate, avoiding the effects of linear difference between the ammonia supply and demand and large time delay caused by the lag in measurement results.

[0012] Based on the above scheme, the ammonia injection control method of the SCR denitrification system in a power plant according to the present invention can be further improved as follows.

[0013] Further, the step of determining the initial total ammonia injection amount for the power plant's SCR denitrification system, so that the power plant's SCR denitrification system injects ammonia according to the initial total ammonia injection amount, includes:

[0014] Acquire real-time online data from the power plant's DCS terminal of the SCR denitrification system;

[0015] Using a preset mathematical model and based on the real-time online data, the predicted NOx concentration at the inlet of the power plant's SCR denitrification system is obtained; wherein, the preset mathematical model is: a big data analysis algorithm and / or a least squares support vector machine algorithm;

[0016] The initial total ammonia injection amount is calculated based on the predicted inlet NOx concentration, the set outlet NOx concentration, and the total flue gas volume at the SCR denitrification inlet, so that the power plant's SCR denitrification system can inject ammonia according to the initial total ammonia injection amount.

[0017] Further, the step of calculating the initial total ammonia injection amount based on the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet includes:

[0018] Based on a preset formula, and according to the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, the initial total ammonia injection is calculated; wherein, the preset formula is: N1=(ab)×c×d×e; N1 is the initial total ammonia injection, a is the predicted inlet NOx concentration, b is the set outlet NOx concentration, c is the total amount of flue gas at the SCR denitrification inlet, d is the catalyst characteristic evaluation reaction coefficient, and e is the ammonia-nitrogen molar ratio.

[0019] Furthermore, it also includes:

[0020] The flue gas velocity at each zone outlet is measured using a multi-point matrix Venturi flow meter installed at each zone outlet.

[0021] Further, the step of obtaining the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system includes:

[0022] Based on the area and flue gas velocity of each zone, the flue gas flow rate of each zone is calculated, and based on the target total ammonia injection and the flue gas flow rate of each zone, the initial ammonia injection amount of each zone is obtained.

[0023] The steps for correcting each initial ammonia injection rate to obtain the target ammonia injection rate for each zone, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection rate for each zone, include:

[0024] Using a neural network algorithm or a backpropagation algorithm, and based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection rate for each zone, the target ammonia injection rate for each zone is obtained.

[0025] Furthermore, it also includes:

[0026] Based on the target total ammonia injection amount, a first valve opening signal is generated for the ammonia injection main pipeline of the power plant SCR denitrification system, so as to control the ammonia injection main pipeline to inject ammonia according to the target total ammonia injection amount;

[0027] Based on the target ammonia injection rate for each zone, a second valve opening signal is generated for the ammonia injection branch pipe of each zone in the power plant's SCR denitrification system, in order to control each zone to inject ammonia according to the corresponding target ammonia injection rate.

[0028] Furthermore, the real-time online data includes: unit load, air volume ratio, total coal volume, coal mill combination, oxygen distribution, and air volume distribution.

[0029] The technical solution of the ammonia injection control system for a power plant SCR denitrification system according to the present invention is as follows:

[0030] It includes: a first processing module, a second processing module, and a control module;

[0031] The first processing module is used to: determine the initial total ammonia injection amount of the SCR denitrification system of the power plant, so that the SCR denitrification system of the power plant injects ammonia according to the initial total ammonia injection amount;

[0032] The second processing module is used to: correct the initial total ammonia injection amount based on the measured values ​​of NOx concentration at the SCR denitrification inlet, NOx concentration at the SCR denitrification outlet, NOx concentration at the desulfurization outlet, and the actual ammonia injection amount of the power plant's SCR denitrification system, so as to obtain the target total ammonia injection amount;

[0033] The control module is used to: obtain the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system; and correct each initial ammonia injection amount based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each zone, so as to obtain the target ammonia injection amount for each zone, so that each zone injects ammonia according to the corresponding target ammonia injection amount.

[0034] The beneficial effects of the ammonia injection control system of the SCR denitrification system in a power plant according to the present invention are as follows:

[0035] The system of this invention realizes mutual feedback correction between the total ammonia supply and the ammonia injection rate in different zones, reducing the ammonia escape rate and lowering operating costs; it can quickly provide feedback on the flow rate measurement results and adjust the ammonia injection rate in different zones by measuring the flow rate, avoiding the effects of linear difference between the ammonia supply and demand and large time delay caused by the lag in measurement results.

[0036] Based on the above scheme, the ammonia injection control system of the SCR denitrification system in a power plant of the present invention can be further improved as follows.

[0037] Furthermore, the first processing module is specifically used for:

[0038] Acquire real-time online data from the power plant's DCS terminal of the SCR denitrification system;

[0039] Using a preset mathematical model and based on the real-time online data, the predicted NOx concentration at the inlet of the power plant's SCR denitrification system is obtained; wherein, the preset mathematical model is: a big data analysis algorithm and / or a least squares support vector machine algorithm;

[0040] The initial total ammonia injection amount is calculated based on the predicted inlet NOx concentration, the set outlet NOx concentration, and the total flue gas volume at the SCR denitrification inlet, so that the power plant's SCR denitrification system can inject ammonia according to the initial total ammonia injection amount.

[0041] Furthermore, the first processing module is specifically used for:

[0042] Based on a preset formula, and according to the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, the initial total ammonia injection is calculated; wherein, the preset formula is: N1=(ab)×c×d×e; N1 is the initial total ammonia injection, a is the predicted inlet NOx concentration, b is the set outlet NOx concentration, c is the total amount of flue gas at the SCR denitrification inlet, d is the catalyst characteristic evaluation reaction coefficient, and e is the ammonia-nitrogen molar ratio.

[0043] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0044] Figure 1 A schematic flowchart of an embodiment of an ammonia injection control method for a power plant SCR denitrification system provided by the present invention is shown.

[0045] Figure 2 The diagram shows a flow chart of step 110 in an embodiment of an ammonia injection control method for a power plant SCR denitrification system provided by the present invention.

[0046] Figure 3 The diagram shows an overall logic block diagram of an embodiment of an ammonia injection control method for a power plant SCR denitrification system provided by the present invention.

[0047] Figure 4 The diagram shows a schematic representation of an embodiment of an ammonia injection control system for a power plant SCR denitrification system provided by the present invention. Detailed Implementation

[0048] Figure 1 The diagram illustrates a flow chart of an embodiment of an ammonia injection control method for a power plant SCR denitrification system provided by the present invention. This method is executed by a control terminal. Figure 1 As shown, it includes the following steps:

[0049] Step 110: Determine the initial total ammonia injection amount of the power plant's SCR denitrification system so that the power plant's SCR denitrification system injects ammonia according to the initial total ammonia injection amount.

[0050] Among them, such as Figure 2 As shown, step 110 includes:

[0051] Step 111: Obtain real-time online data from the power plant's DCS terminal of the SCR denitrification system.

[0052] The real-time online data includes: unit load, air volume ratio, total coal volume, coal mill combination, oxygen distribution, and air volume distribution.

[0053] Specifically, the control terminal acquires real-time online data from the power plant's DCS terminal, including unit load, air volume ratio, total coal volume, coal mill combination, oxygen distribution, and air volume distribution.

[0054] Step 112: Using a preset mathematical model and based on the real-time online data, obtain the predicted NOx concentration at the inlet of the power plant's SCR denitrification system.

[0055] Specifically, ① the preset mathematical model is: big data analysis algorithm and / or least squares support vector machine algorithm. ② The predicted NOx concentration at the inlet of the power plant's SCR denitrification system is collected using the CEMS system corresponding to the power plant's SCR denitrification system.

[0056] Specifically, the control terminal uses big data analysis algorithms and / or least squares support vector machine algorithms to obtain the predicted NOx concentration at the inlet of the power plant's SCR denitrification system based on real-time online data.

[0057] It should be noted that the specific process of calculating the predicted value of NOx concentration at the inlet using big data analysis algorithms, least squares support vector machine algorithms, or a combination of both is existing technology, and the detailed calculation process will not be elaborated here.

[0058] Step 113: Calculate the initial total ammonia injection amount based on the predicted inlet NOx concentration, the set outlet NOx concentration, and the total flue gas volume at the SCR denitrification inlet, so that the power plant's SCR denitrification system can inject ammonia according to the initial total ammonia injection amount.

[0059] Among them, ① the outlet NOx concentration setpoint is a pre-set NOx concentration value. ② The total flue gas volume at the SCR denitrification inlet is obtained from the CEMS system measurement.

[0060] Specifically, the control terminal calculates the initial total ammonia injection amount based on the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, and controls the power plant's SCR denitrification system to inject ammonia according to the initial total ammonia injection amount.

[0061] It should be noted that after obtaining the initial total ammonia injection amount, the control terminal converts the initial total ammonia injection amount into a total flow valve control signal for the main ammonia supply pipeline of the power plant's SCR denitrification system, and controls the opening degree of the total ammonia supply flow valve according to the control signal, so that the main ammonia supply pipeline injects ammonia according to the initial total ammonia injection amount.

[0062] Step 120: Based on the measured values ​​of NOx concentration at the SCR denitrification inlet, NOx concentration at the SCR denitrification outlet, and NOx concentration at the desulfurization outlet of the power plant's SCR denitrification system, and the actual ammonia injection amount, the initial total ammonia injection amount is corrected to obtain the target total ammonia injection amount.

[0063] Among them, ① the measured values ​​of NOx concentration at the SCR denitrification inlet, the SCR denitrification outlet, and the desulfurization outlet were all obtained from the CEMS system. ② The target total ammonia injection is: the corrected total ammonia injection. ③ The actual ammonia injection is: the actual total ammonia injection of the power plant's SCR denitrification system at the current moment.

[0064] Specifically, the control terminal corrects the initial total ammonia injection amount based on the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, the measured NOx concentration at the desulfurization outlet, and the actual ammonia injection amount of the power plant's SCR denitrification system, thereby obtaining the target total ammonia injection amount.

[0065] It should be noted that after the control terminal obtains the target total ammonia injection amount, it converts the target total ammonia injection amount into a total flow valve control signal for the main ammonia supply pipeline, and fine-tunes the opening of the total ammonia supply flow valve according to the control signal, so that the main ammonia supply pipeline injects ammonia according to the target total ammonia injection amount.

[0066] Step 130: Based on the target total ammonia injection and the flue gas velocity at the outlet of each section of the power plant's SCR denitrification system, obtain the initial ammonia injection amount for each section. Then, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each section, correct each initial ammonia injection amount to obtain the target ammonia injection amount for each section, so that each section injects ammonia according to the corresponding target ammonia injection amount.

[0067] Among them, ① "multiple zones" refers to the zones of the SCR reactor in the SCR denitrification system of the power plant. ② The flue gas velocity at the outlet of each zone is measured using a multi-point matrix Venturi flow meter installed at the outlet of each zone. ③ The total flue gas volume at the SCR denitrification inlet is measured using the CEMS system. ④ The measured ammonia injection rate for each zone is the actual total ammonia injection rate for each zone of the SCR reactor in the power plant's SCR denitrification system at the current moment. ⑤ The target ammonia injection rate is the corrected ammonia injection rate for each zone.

[0068] Specifically, the control terminal obtains the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system. Then, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each zone, the initial ammonia injection amount is corrected to obtain the target ammonia injection amount for each zone.

[0069] Preferably, step 113 includes:

[0070] Based on a preset formula, and according to the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, the initial total ammonia injection is calculated.

[0071] The preset formula is: N1=(ab)×c×d×e; N1 is the initial total ammonia injection, a is the predicted value of the inlet NOx concentration, b is the set value of the outlet NOx concentration, c is the total amount of flue gas at the SCR denitrification inlet, d is the reaction coefficient for catalyst characteristic evaluation, and e is the ammonia-nitrogen molar ratio.

[0072] Specifically, the control terminal substitutes the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet into a preset formula to calculate the initial total ammonia injection.

[0073] Preferably, the step of obtaining the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system includes:

[0074] Based on the area and flue gas velocity of each zone, the flue gas flow rate of each zone is calculated, and based on the target total ammonia injection and the flue gas flow rate of each zone, the initial ammonia injection amount of each zone is obtained.

[0075] Specifically, the control terminal calculates the flue gas flow rate of any zone in the SCR reactor based on the zone area and flue gas velocity, and repeats this process until the flue gas flow rate of each zone is obtained.

[0076] The steps for correcting each initial ammonia injection rate to obtain the target ammonia injection rate for each zone, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection rate for each zone, include:

[0077] Using a neural network algorithm or a backpropagation algorithm, and based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection rate for each zone, the target ammonia injection rate for each zone is obtained.

[0078] Specifically, the control terminal uses a neural network algorithm or a backpropagation algorithm to correct each initial ammonia injection amount based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each zone, thereby obtaining the target ammonia injection amount for each zone.

[0079] More preferably, it also includes:

[0080] Based on the target total ammonia injection amount, a first valve opening signal is generated for the ammonia injection main pipeline of the power plant's SCR denitrification system, so as to control the ammonia injection main pipeline to inject ammonia according to the target total ammonia injection amount.

[0081] Among them, the target total ammonia injection volume corresponds to the valve opening signal (first valve opening signal) of a total ammonia injection pipeline.

[0082] Based on the target ammonia injection rate for each zone, a second valve opening signal is generated for the ammonia injection branch pipe of each zone in the power plant's SCR denitrification system, in order to control each zone to inject ammonia according to the corresponding target ammonia injection rate.

[0083] The target ammonia injection quantity for any zone corresponds to the valve opening signal (second valve opening signal) of an ammonia injection branch pipe in that zone.

[0084] It should be noted that, Figure 3 The overall logic block diagram of this embodiment is shown. In addition to using one control terminal for data acquisition, calculation, and control as described above, two systems (terminals) can also be used for control. The pre-total prediction system is used to calculate the target total ammonia injection amount and control the total ammonia injection amount, while the zone leveling system is used to calculate the target ammonia injection amount for each zone corresponding to the SCR reactor and control the zone ammonia injection amount. The final effect is consistent with the effect obtained by using the control terminal, and will not be elaborated further here.

[0085] The technical solution of this embodiment realizes mutual feedback correction between the total ammonia supply and the ammonia injection volume in each zone, reducing the ammonia escape rate and lowering the operating cost; it can quickly feed back the flow rate measurement results and adjust the ammonia injection volume in each zone by measuring the flow rate, avoiding the effects of linear difference between the ammonia supply and demand and large time delay caused by the lag in measurement results.

[0086] Figure 4 A schematic diagram of an embodiment of an ammonia injection control system for a power plant SCR denitrification system provided by the present invention is shown. Figure 4 As shown, the system 200 includes: a first processing module 210, a second processing module 220, and a control module 230.

[0087] The first processing module 210 is used to: determine the initial total ammonia injection amount of the power plant SCR denitrification system, so that the power plant SCR denitrification system injects ammonia according to the initial total ammonia injection amount;

[0088] The second processing module 220 is used to: correct the initial total ammonia injection amount based on the measured values ​​of NOx concentration at the SCR denitrification inlet, NOx concentration at the SCR denitrification outlet, NOx concentration at the desulfurization outlet, and the actual ammonia injection amount of the power plant's SCR denitrification system, so as to obtain the target total ammonia injection amount;

[0089] The control module 230 is used to: obtain the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system; and correct each initial ammonia injection amount based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each zone, so as to obtain the target ammonia injection amount for each zone, so that each zone injects ammonia according to the corresponding target ammonia injection amount.

[0090] Preferably, the first processing module 210 is specifically used for:

[0091] Acquire real-time online data from the power plant's DCS terminal of the SCR denitrification system;

[0092] Using a preset mathematical model and based on the real-time online data, the predicted NOx concentration at the inlet of the power plant's SCR denitrification system is obtained; wherein, the preset mathematical model is: a big data analysis algorithm and / or a least squares support vector machine algorithm;

[0093] The initial total ammonia injection amount is calculated based on the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet.

[0094] Preferably, the first processing module 210 is specifically used for:

[0095] Based on a preset formula, and according to the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, the initial total ammonia injection is calculated; wherein, the preset formula is: N1=(ab)×c×d×e; N1 is the initial total ammonia injection, a is the predicted inlet NOx concentration, b is the set outlet NOx concentration, c is the total amount of flue gas at the SCR denitrification inlet, d is the catalyst characteristic evaluation reaction coefficient, and e is the ammonia-nitrogen molar ratio.

[0096] The technical solution of this embodiment realizes mutual feedback correction between the total ammonia supply and the ammonia injection volume in each zone, reducing the ammonia escape rate and lowering the operating cost; it can quickly feed back the flow rate measurement results and adjust the ammonia injection volume in each zone by measuring the flow rate, avoiding the effects of linear difference between the ammonia supply and demand and large time delay caused by the lag in measurement results.

[0097] The parameters and steps for each module to achieve their respective functions in the ammonia injection control system 200 of a power plant SCR denitrification system described above can be found in the embodiments of the ammonia injection control method of a power plant SCR denitrification system described above, and will not be repeated here.

[0098] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0099] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A method for controlling ammonia injection in a power plant SCR denitrification system, characterized in that, include: Determine the initial total ammonia injection amount for the SCR denitrification system of the power plant, so that the SCR denitrification system of the power plant injects ammonia according to the initial total ammonia injection amount; Based on the measured values ​​of NOx concentration at the SCR denitrification inlet, NOx concentration at the SCR denitrification outlet, and NOx concentration at the desulfurization outlet of the power plant's SCR denitrification system, and the actual ammonia injection amount, the initial total ammonia injection amount is corrected to obtain the target total ammonia injection amount. Based on the target total ammonia injection and the flue gas velocity at the outlet of each section of the SCR denitrification system in the power plant, the initial ammonia injection amount for each section is obtained. Then, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each section, the initial ammonia injection amount for each section is corrected to obtain the target ammonia injection amount for each section, so that each section injects ammonia according to the corresponding target ammonia injection amount. The step of determining the initial total ammonia injection amount for the SCR denitrification system of a power plant, so that the SCR denitrification system injects ammonia according to the initial total ammonia injection amount, includes: Acquire real-time online data from the power plant's DCS terminal of the SCR denitrification system; Using a preset mathematical model and based on the real-time online data, the predicted NOx concentration at the inlet of the power plant's SCR denitrification system is obtained; wherein, the preset mathematical model is: a big data analysis algorithm and / or a least squares support vector machine algorithm; Based on a preset formula, and according to the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, the initial ammonia injection volume is calculated so that the power plant's SCR denitrification system injects ammonia according to the initial ammonia injection volume; wherein, the preset formula is: ; The initial total amount of ammonia injected. The predicted value of the inlet NOx concentration. Set a value for the NOx concentration at the outlet. The total amount of flue gas at the SCR denitrification inlet. To evaluate the reaction coefficients for catalyst characteristics, The ammonia-nitrogen molar ratio is given.

2. The ammonia injection control method for a power plant SCR denitrification system according to claim 1, characterized in that, Also includes: The flue gas velocity at each zone outlet is measured using a multi-point matrix Venturi flow meter installed at each zone outlet.

3. The ammonia injection control method for a power plant SCR denitrification system according to claim 1, characterized in that, The step of obtaining the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system includes: Based on the area and flue gas velocity of each zone, the flue gas flow rate of each zone is calculated, and based on the target total ammonia injection and the flue gas flow rate of each zone, the initial ammonia injection amount of each zone is obtained. The steps for correcting each initial ammonia injection rate to obtain the target ammonia injection rate for each zone, based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection rate for each zone, include: Using a neural network algorithm or a backpropagation algorithm, and based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection rate for each zone, the target ammonia injection rate for each zone is obtained.

4. The ammonia injection control method for a power plant SCR denitrification system according to any one of claims 1-3, characterized in that, Also includes: Based on the target total ammonia injection amount, a first valve opening signal is generated for the ammonia injection main pipeline of the power plant SCR denitrification system, so as to control the ammonia injection main pipeline to inject ammonia according to the target total ammonia injection amount; Based on the target ammonia injection rate for each zone, a second valve opening signal is generated for the ammonia injection branch pipe of each zone in the power plant's SCR denitrification system, in order to control each zone to inject ammonia according to the corresponding target ammonia injection rate.

5. The ammonia injection control method for a power plant SCR denitrification system according to claim 1, characterized in that, The real-time online data includes: unit load, air volume ratio, total coal volume, coal mill combination, oxygen distribution, and air volume distribution.

6. An ammonia injection control system for a power plant SCR denitrification system, characterized in that, include: The system comprises a first processing module, a second processing module, and a control module. The first processing module is used to: determine the initial total ammonia injection amount of the SCR denitrification system of the power plant, so that the SCR denitrification system of the power plant injects ammonia according to the initial total ammonia injection amount; The second processing module is used to: correct the initial total ammonia injection amount based on the measured values ​​of NOx concentration at the SCR denitrification inlet, NOx concentration at the SCR denitrification outlet, NOx concentration at the desulfurization outlet, and the actual ammonia injection amount of the power plant's SCR denitrification system, so as to obtain the target total ammonia injection amount; The control module is used to: obtain the initial ammonia injection amount for each zone based on the target total ammonia injection amount and the flue gas velocity at the outlet of each zone of the power plant's SCR denitrification system; and correct each initial ammonia injection amount based on the total flue gas volume at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification inlet, the measured NOx concentration at the SCR denitrification outlet, and the measured ammonia injection amount for each zone, so as to obtain the target ammonia injection amount for each zone, so that each zone injects ammonia according to the corresponding target ammonia injection amount; The first processing module is specifically used for: Acquire real-time online data from the power plant's DCS terminal of the SCR denitrification system; Using a preset mathematical model and based on the real-time online data, the predicted NOx concentration at the inlet of the power plant's SCR denitrification system is obtained; wherein, the preset mathematical model is: a big data analysis algorithm and / or a least squares support vector machine algorithm; Based on a preset formula, and according to the predicted inlet NOx concentration, the set outlet NOx concentration, and the total amount of flue gas at the SCR denitrification inlet, the initial total ammonia injection is calculated; wherein, the preset formula is: ; The initial total amount of ammonia injected. The predicted value of the inlet NOx concentration. Set a value for the NOx concentration at the outlet. The total amount of flue gas at the SCR denitrification inlet. To evaluate the reaction coefficients for catalyst characteristics, The ammonia-nitrogen molar ratio is given.

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