Ammonia spraying control method, control system and control device for flue gas denitration

Abstract

The invention discloses an ammonia spraying control method, system and device for kiln flue gas denitration, and relates to the technical field of glass production. The ammonia spraying control method for flue gas denitration of the kiln comprises the following steps that time nodes of fire exchange operation of the kiln are obtained, and a preset time period for keeping fire power is formed between every two adjacent time nodes; splitting a preset time period into a plurality of time segments, wherein different time segments correspondingly input different reference ammonia spraying amounts; the actual input value of nitric oxide at the flue gas inlet is obtained; obtaining a first compensation coefficient according to the actual input value of the nitrogen oxide and a reference value of the nitrogen oxide at the preset flue gas inlet, wherein the first compensation coefficient is used for adjusting on the basis of the reference ammonia spraying amount to obtain an actual ammonia spraying amount; according to the technical scheme provided by the invention, the reference ammonia spraying amount is set in advance according to different working conditions of the kiln in different time periods, and the actual ammonia spraying amount is obtained by utilizing the first compensation coefficient, so that the ammonia spraying accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of glass production, and in particular to an ammonia injection control method and a control system for furnace flue gas denitration. Background Art

[0002] When the glass industry furnace is burning, it is necessary to regularly change the fire of different temperatures, generally every 20 minutes. During the switching between the two fires, the change in combustion conditions will cause NO X In order to reduce the amount of ammonia water or ammonia gas used in denitrification, the control of ammonia injection in denitrification was generally done by operators based on monitoring the outlet NO X Manual real-time adjustment of ammonia spraying based on hourly average value wastes a lot of manpower. In addition, due to the influence of monitoring equipment, flue gas flow, and drastic changes in operating conditions during fire change, there is a time lag in monitoring data, which may lead to low accuracy in adjusting the amount of ammonia spraying. Summary of the invention

[0003] The main purpose of the present invention is to propose an ammonia spraying control method and control system for furnace flue gas denitrification, aiming to solve the problems of waste of manpower and low precision of ammonia spraying in the existing furnace flue gas denitrification.

[0004] To achieve the above object, the present invention provides a method for controlling ammonia injection for denitrification of kiln flue gas, comprising the following steps:

[0005] Obtain the time nodes of the kiln for the fire change operation, and form a preset time period for maintaining the fire power between two adjacent time nodes;

[0006] The preset time period is divided into several time segments, and different reference ammonia injection amounts are input corresponding to different time segments;

[0007] Obtain the actual input value of nitrogen oxides at the flue gas inlet;

[0008] A first compensation coefficient is obtained according to the actual input value of the nitrogen oxides and a preset reference value of the nitrogen oxides at the flue gas inlet, and the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount to obtain the actual ammonia injection amount.

[0009] In one embodiment, the preset time period is divided into a plurality of time segments, and different time segments correspond to the step of inputting different reference ammonia injection amounts, and the following steps are also included:

[0010] Obtaining an actual average value of the nitrogen oxide content at the flue gas outlet within a preset time, and obtaining a second compensation coefficient according to a preset linear curve of the average value of the nitrogen oxide content at the flue gas outlet within a preset time and the actual average value;

[0011] On the basis of the reference ammonia injection amount, a corrected reference ammonia injection amount is obtained by adjusting according to the second compensation coefficient.

[0012] In one embodiment, the step of obtaining the time nodes of the kiln for performing the fire-changing operation and forming a preset time period for maintaining the firepower between two adjacent time nodes comprises the following steps:

[0013] Obtaining control signals generated by the control system of the kiln for fire-changing operations;

[0014] The time node for changing the ignition is obtained according to the change of the control signal.

[0015] In one embodiment, the step of obtaining a control signal generated by a control system of the kiln for performing a fire-changing operation and obtaining a time node for fire-changing according to a change in the control signal further includes the following steps:

[0016] Obtaining the fire-changing pulse signal generated when the kiln performs a fire-changing operation;

[0017] Obtaining a time node for fire switching according to a change in the fire switching pulse signal; or,

[0018] Obtain the fire-changing long drive signal generated before the kiln performs the fire-changing operation;

[0019] Obtaining a time node for a fire change according to the fire change long drive signal; or,

[0020] Obtain different fire-changing point signals generated by changing different fires during kiln fire-changing operations;

[0021] Obtaining a fire-changing time node according to the change time of the different fire-changing point signals; or,

[0022] Obtaining the number of fire changes during the kiln fire change operation, and obtaining a fire change counting signal according to the number of fire changes;

[0023] The time node of the fire change is obtained according to the fire change count signal.

[0024] In one embodiment, the step of dividing the preset time period into a plurality of time segments, and inputting different reference ammonia injection amounts corresponding to different time segments, comprises the following steps:

[0025] The preset time period includes 6 time segments, wherein the 6 time segments are fire preparation period, low fluctuation period, high fluctuation period, low stability period, medium stability period and high stability period, and a benchmark ammonia injection amount is input in each time period.

[0026] In one embodiment, the preset time period includes 6 time segments, wherein the 6 time segments are respectively a fire preparation period, a low fluctuation period, a high fluctuation period, a low stability period, a medium stability period and a high stability period, and the step of injecting a reference ammonia amount input in each time period includes the following steps:

[0027] timing the fire preparation period, the low fluctuation period, the high fluctuation period, the low stability period, the medium stability period and the high stability period respectively;

[0028] When the time length of the high stability period reaches the preset time length, if the time node of the next fire change has not yet arrived, the reference ammonia injection amount corresponding to the high stability period continues to be input; or,

[0029] When the timing time length in the high stability period does not reach the preset time length, if it is advanced to the time node of the next fire change, the reference ammonia injection amount of the fire preparation period corresponding to the fire change is input.

[0030] In one embodiment, the step of obtaining a first compensation coefficient according to the actual input value of the nitrogen oxides and a preset reference value of the nitrogen oxides at the flue gas inlet, wherein the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount, further includes the following steps:

[0031] During the low stable period, medium stable period and high stable period after the fire change, the real-time nitrogen oxide concentration at the flue gas inlet is obtained;

[0032] The average concentration of nitrogen oxides at the flue gas inlet during the low stable period, the medium stable period and the high stable period is obtained by calculation, and the average content of nitrogen oxides is the actual input value of nitrogen oxides.

[0033] In one embodiment, the step of obtaining a first compensation coefficient according to the actual input value of the nitrogen oxides and a preset reference value of the nitrogen oxides at the flue gas inlet, wherein the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount, further includes the following steps:

[0034] Obtaining a first compensation coefficient according to a ratio of an actual input value of nitrogen oxides to a reference value of nitrogen oxides;

[0035] The actual ammonia injection amount is obtained according to the product of the obtained first compensation coefficient and the reference ammonia injection amount.

[0036] The present invention further proposes an ammonia injection control system for furnace flue gas denitrification, which is used to implement the ammonia injection control method for furnace flue gas denitrification, comprising:

[0037] The first acquisition module is used to acquire the time nodes of the kiln for the fire change operation, and a preset time period for maintaining the fire power is formed between two adjacent time nodes;

[0038] A splitting module is used to split the preset time period into several time segments, and different time segments correspond to inputting different reference ammonia injection amounts;

[0039] The second acquisition module is used to obtain the actual input value of nitrogen oxides at the flue gas inlet;

[0040] A third acquisition module is used to preset a reference value of nitrogen oxides at the flue gas inlet;

[0041] A calculation module, wherein the calculation module is respectively connected to the first acquisition module, the splitting module, the second acquisition module, and the third acquisition module, and the calculation module is used to obtain a first compensation coefficient according to the actual input value and the reference value of the nitrogen oxides, and the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount.

[0042] The present invention also provides an ammonia injection control device for furnace flue gas denitrification, comprising:

[0043] A first detection device, the first detection device is arranged at the flue gas inlet of the denitration reactor, and the first detection device is used to obtain data of an actual input value of nitrogen oxides at the flue gas inlet;

[0044] An ammonia gas input device, the ammonia gas input device is used to control the amount of ammonia sprayed into the denitration reactor;

[0045] A second detection device, the second detection device is connected to the ammonia input device, and the second detection device is used to obtain data on actual ammonia injection amount;

[0046] A third detection device, the third detection device is arranged at the flue gas outlet of the denitration reactor, and the third detection device is used to obtain data of an actual input value of nitrogen oxides at the flue gas outlet;

[0047] A controller, wherein the controller is respectively connected to the first detection device, the ammonia input device, the second detection device, and the third detection device; the control device is used to execute the above-mentioned ammonia injection control method for kiln flue gas denitrification.

[0048] The technical solution of the present invention obtains the time node of the kiln for fire-changing operation, and forms a preset time period for maintaining firepower between two adjacent time nodes; splits the preset time period into several time segments, and inputs different reference ammonia injection amounts corresponding to different time segments; obtains the actual input value of nitrogen oxides at the flue gas inlet and the preset reference value of nitrogen oxides at the flue gas inlet, and obtains a first compensation coefficient based on the actual input value and the reference value of nitrogen oxides, and the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount. By determining the time node of the fire-changing operation, the firepower maintenance period is divided into a preset time period, and the preset time period is further subdivided into time segments, the appropriate reference ammonia injection amount can be set in advance for different working conditions of the kiln in different time periods; in addition, in each time segment, the ammonia injection amount is input according to the preset reference value, and the ammonia injection amount can be adjusted in real time according to the change of the flue gas inlet monitoring data, thereby improving the accuracy of ammonia injection; and by real-time monitoring the actual concentration of nitrogen oxides at the flue gas inlet, and comparing it with the preset reference value to obtain the first compensation coefficient, the reference ammonia injection amount is adjusted using the first compensation coefficient to obtain the actual ammonia injection amount, which can achieve more precise control and reduce ammonia consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0050] Figure 1 A schematic diagram of the method steps of an embodiment of a method for controlling ammonia injection for denitrification of kiln flue gas provided by the present invention;

[0051] Figure 2 A schematic diagram of an embodiment of an ammonia injection control system for furnace flue gas denitrification provided by the present invention;

[0052] Figure 3 A schematic structural diagram of an embodiment of an ammonia injection control system for kiln flue gas denitrification provided by the present invention.

[0053] Description of Figure Numbers:

[0054] 1. First acquisition module; 2. Splitting module; 3. Second acquisition module; 4. Third acquisition module; 5. Calculation module; 6. First detection device; 61. First flow meter; 62. Concentration detector; 7. Ammonia input device; 8. Second detection device; 9. Third detection device; 10. Controller; 11. Mixer; 12. Frequency converter; 13. Fan; 14. Fourth detection device; 15. Ammonia shut-off valve body; 16. Flow regulating valve.

[0055] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0058] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0059] The invention provides an ammonia injection control method for furnace flue gas denitrification.

[0060] See also Figure 1 In one embodiment of the present invention, the ammonia injection control method for furnace flue gas denitrification comprises the following steps:

[0061] S100: obtaining time nodes for the kiln to perform a fire-changing operation, and forming a preset time period for maintaining the fire power between two adjacent time nodes;

[0062] S200: dividing the preset time period into a plurality of time segments, and inputting different reference ammonia injection amounts corresponding to different time segments;

[0063] S300: obtaining the actual input value of nitrogen oxides at the flue gas inlet;

[0064] S400: Obtaining a first compensation coefficient K according to an actual input value of nitrogen oxides and a preset reference value of nitrogen oxides at a flue gas inlet. The first compensation coefficient K is used to adjust an actual ammonia injection amount based on a reference ammonia injection amount.

[0065] By determining the time node of the fire-changing operation, dividing the fire-maintaining period into a preset time period, and further subdividing the preset time period into time segments, the appropriate benchmark ammonia injection amount can be set in advance for different working conditions of the kiln in different time periods; in addition, in each time segment, the ammonia injection amount is input according to the preset benchmark value, and the ammonia injection amount can be adjusted in real time according to the changes in the flue gas inlet monitoring data, thereby improving the accuracy of ammonia injection; and by real-time monitoring of the actual concentration of nitrogen oxides at the flue gas inlet and comparing it with the preset benchmark value to obtain the first compensation coefficient K, the benchmark ammonia injection amount is adjusted using the first compensation coefficient K to obtain the actual ammonia injection amount, which can achieve more precise control and reduce ammonia consumption.

[0066] In one embodiment, the step S200 of dividing the preset time period into a plurality of time segments, and inputting different reference ammonia injection amounts corresponding to different time segments, further includes the following steps:

[0067] Obtaining an actual average value of the nitrogen oxide content at the flue gas outlet within a preset time, and obtaining a second compensation coefficient k according to a preset linear curve of the average value of the nitrogen oxide content at the flue gas outlet within a preset time and the actual average value;

[0068] On the basis of the reference ammonia injection amount, the corrected reference ammonia injection amount is obtained by adjusting according to the second compensation coefficient k.

[0069] Among them, in the step of obtaining the mean linear curve of the nitrogen oxide content at the preset flue gas outlet within the preset time, illustratively, the preset time can be set to 1h, and according to the local flue gas emission standard, the mean linear curve of the nitrogen oxide content discharged at the flue gas outlet within 1h is set; the actual mean of the nitrogen oxide content at the flue gas outlet within 1h is obtained, and the second compensation coefficient k is obtained by comparing the mean linear curve with the actual mean, and finally the second compensation coefficient k is used to adjust the reference ammonia injection amount on the basis of the reference ammonia injection amount to obtain the corrected reference ammonia injection amount. In the above steps, the ratio of the actual mean of the nitrogen oxide content and the corresponding value on the mean linear curve of the nitrogen oxide content within each preset time obtains the accurate second compensation coefficient k, and the second compensation coefficient k can dynamically adjust the ammonia injection amount according to the real-time data to adapt to the change of the nitrogen oxide content at the flue gas outlet, so as to make the corrected reference ammonia injection amount more accurate. The second compensation coefficient k is used to adjust the corrected reference ammonia injection amount, and then the first compensation coefficient K is used to adjust the actual ammonia injection amount; through the continuous adjustment of the two compensation coefficients, more precise control of the ammonia injection amount can be achieved; the first compensation coefficient K is determined based on the ratio of the actual input value of nitrogen oxides to the preset reference value of nitrogen oxides, and the second compensation coefficient k is determined based on the ratio of the actual average value of the nitrogen oxide content at the flue gas outlet and the preset linear curve. The two-stage adjustment method provides additional flexibility to adapt to different operating conditions of the kiln. When changes in the nitrogen oxide content of the flue gas input and the flue gas output are detected, the final actual ammonia injection amount can be quickly adjusted by adjusting the first compensation coefficient K and the second compensation coefficient k to achieve rapid response.

[0070] In addition, after half past every hour, the actual mean value of the nitrogen oxide content at the flue gas outlet within the preset time is obtained, and the second compensation coefficient k is obtained by comparing the preset linear curve of the mean value of the nitrogen oxide content at the flue gas outlet within the preset time with the actual mean value; the reference ammonia injection amount is adjusted in real time according to the second compensation coefficient, so as to further finely control the ammonia injection. The preset time is at least 0.5h, that is, after 30 minutes of each hour, the actual mean value of nitrogen oxides at the flue gas outlet is obtained, which can improve the accuracy of the actual mean value of nitrogen oxides obtained, reduce the hysteresis effect of the monitoring equipment, and improve the control accuracy of ammonia injection. For example, the fire is changed at 10 o'clock, and the actual mean value of the nitrogen oxide content at the flue gas outlet within the preset time is obtained after 10:30, which can improve the accuracy of the actual mean value of the nitrogen oxide content obtained.

[0071] In one embodiment, the step S100 of obtaining the time nodes of the kiln for performing the fire-changing operation and forming a preset time period for maintaining the firepower between two adjacent time nodes comprises the following steps:

[0072] Obtaining a fire-changing signal generated by a kiln during a fire-changing operation;

[0073] The time node for changing the fire is obtained according to the change of the control signal.

[0074] The kiln fire-changing operation is usually automatically performed by the control system, which generates corresponding control signals to indicate the start and end of the fire-changing action. By real-time monitoring of the control system signal, the signal changes of the fire-changing operation can be captured. For example, a specific pulse signal or long drive signal may be generated during the fire-changing operation. The changes in these signals can be used to determine the time node of the fire-changing operation; when the change of the control signal is detected, the system will record this time point, which is the time node of the fire-changing operation. A preset time period for maintaining the firepower is formed between two adjacent fire-changing time nodes. During this time period, the combustion condition of the kiln needs to remain relatively stable. The preset time period can be further divided into smaller time segments, each of which corresponds to different combustion parameters and ammonia injection amounts. In each time segment, according to the preset benchmark ammonia injection amount, combined with the real-time monitoring of the nitrogen oxide content of the flue gas input, the ammonia injection amount can be adjusted to optimize the denitrification effect. By presetting the mean linear curve of the nitrogen oxide content at the flue gas outlet and comparing it with the actual monitored nitrogen oxide content, the second compensation coefficient k can be obtained. The second compensation coefficient k is used to adjust the reference ammonia injection amount to obtain a corrected reference ammonia injection amount, thereby achieving more accurate ammonia injection control. 基 The product of the corrected reference ammonia injection amount Q 修 , the first compensation coefficient K and the corrected reference ammonia injection amount Q 修 The actual ammonia injection amount Q is obtained by multiplying 实 .

[0075] In one embodiment, the step of obtaining a control signal generated by a control system of a kiln for performing a fire-changing operation and obtaining a time node for fire-changing according to a change in the control signal further includes the following steps:

[0076] Acquire the fire-changing pulse signal generated when the kiln performs the fire-changing operation;

[0077] The time node for changing the ignition is obtained according to the change of the pulse signal.

[0078] The pulse signal provides a clear time mark for the fire change, which can be performed at the right time. By changing the fire at the preset time, the combustion efficiency can be maximized, while reducing the energy waste caused by improper fire change. The accurate acquisition of the fire change time node can adjust the ammonia injection amount according to the real-time data and optimize the control of the nitrogen oxide content emitted. The automatic acquisition of the fire change time node reduces the dependence on manual monitoring and intervention, and reduces the complexity and labor intensity of the operation.

[0079] In another embodiment, the step of obtaining a control signal generated by a control system of the kiln for performing a fire-changing operation and obtaining a time node for the fire-changing operation according to a change in the control signal further includes the following steps:

[0080] Obtain the fire-changing long drive signal generated before the kiln performs the fire-changing operation;

[0081] The time node for changing fire is obtained according to the long drive signal.

[0082] The long drive signal generated before the kiln performs a fire-changing operation usually indicates that the fire-changing process is about to begin; when the long drive signal is activated, the time node of the fire-changing is obtained according to the long drive signal. The long drive signal provides a clear time mark, which is convenient for determining the time node for executing the fire-changing operation. The clear signal change serves as the basis for the time node, which improves the accuracy of subsequent adjustment of ammonia injection.

[0083] In another embodiment, the step of obtaining a control signal generated by a control system of the kiln for performing a fire-changing operation and obtaining a time node for the fire-changing operation according to a change in the control signal further includes the following steps:

[0084] Obtain different fire-changing point signals generated by changing different fires during kiln fire-changing operations;

[0085] The time node of the fire change is obtained according to the change time of different fire change point signals.

[0086] Different point signals are preset to be generated during the fire-changing operation. Different point signals represent different fire-changing stages or states. By real-time monitoring of the changes in these point signals, when a signal change is detected, this time point is recorded, and the time point of the signal change is determined as the time node of the fire-changing operation. For example, the left fire is first changed in the kiln, and then the right fire is changed. The left fire and the right fire will generate different signals. The generated point signals can be directly connected to the DCS (distributed control system) control module. The DCS module processes these point signals and performs corresponding fire-changing operations according to the preset control strategy.

[0087] In another embodiment, the step of obtaining a control signal generated by a control system of the kiln for performing a fire-changing operation and obtaining a time node for the fire-changing operation according to a change in the control signal further includes the following steps:

[0088] Obtaining the number of fire changes during the kiln fire change operation, and obtaining a fire change counting signal according to the number of fire changes;

[0089] The time node of the fire change is obtained according to the fire change counting signal.

[0090] The kiln's fire-changing control system determines the time node of the fire-changing by obtaining the number of fire-changing times. It does not rely on specific point signals, but tracks the fire-changing operation by counting the number of fire-changing times. For example, a counter is initialized to record the number of fire-changing times of the kiln, that is, each fire-changing is counted once, and 0 is temporarily set as the left fire, 1 is the right fire, 2 is the left fire, 3 is the right fire... and so on. After the count reaches the upper limit, the counter is reset and re-counted when the next fire-changing signal is received. Note that the upper limit of the counter is set to an odd number, that is, the next fire-changing must be the left fire after being reset, and the counter is 0 at this time. The counter logic is simple and requires multiple point signals, which reduces hardware requirements and potential failure points; the counter can set different upper limits of the number of fire-changing times to adapt to different process requirements.

[0091] In one embodiment, the preset time period is divided into a plurality of time segments, and different time segments correspond to inputting different reference ammonia injection amounts. Step S200 includes the following steps:

[0092] The preset time period includes 6 time segments, wherein the 6 time segments are fire preparation period, low fluctuation period, high fluctuation period, low stability period, medium stability period and high stability period, and a benchmark ammonia injection amount is input in each time period.

[0093] Nitrogen oxides are NO X , while in theory NO X The molar ratio of ammonia to nitrogen in the redox reaction with ammonia is 1:1. When the molar ratio of ammonia to nitrogen is greater than 1:1, ammonia escape will occur; when the molar ratio of ammonia to nitrogen is less than 1:1, NO X Therefore, in NO X When the kiln is changing fire, the NO X The concentration is extremely low, and a trough value appears. At this time, the amount of ammonia spray should be greatly reduced; after the combustion gun is extinguished, continue to add combustion-supporting air for purging. At this time, the oxygen content is high, and the NO converted in the flue gas X The concentration will have a peak value. At the peak, the amount of ammonia spray should be appropriately increased. When the burner is re-ignited, NO X The concentration slowly rises to the normal value, and the amount of ammonia sprayed should also match it, showing a slow upward trend; similarly, during subsequent stable combustion, such as NO X If there is a slight fluctuation, the amount of ammonia sprayed should also be adjusted accordingly. If the adjustment curve of the amount of ammonia sprayed is consistent with NO X When the fluctuation curve of the ammonia nitrogen ratio is consistent with that of the nitrogen oxides, the ammonia escape caused by the ammonia nitrogen molar ratio being seriously higher than 1:1 in a certain period of time can be greatly reduced. Therefore, the preset time period is divided into six clear stages, each with different combustion characteristics and different ammonia injection control requirements. The fire preparation period is the preparation stage before the fire is changed, NO X The content is low; the low fluctuation period is after the fire change operation begins, the combustion process will produce NOX There are some fluctuations in the content; during the high fluctuation period, there will be larger combustion fluctuations, NO X The content of NO also fluctuates greatly, and the amount of ammonia sprayed needs to be adjusted to cope with these fluctuations to ensure the denitrification effect. The low stable period is when the combustion process begins to stabilize, and NO X The content begins to increase, and the combustion process becomes more stable during the mid-stable period. X The content will be further increased, and the amount of ammonia sprayed will be further increased and adjusted to maintain the best denitrification effect; the high stability period is when the combustion process is very stable and NO X The higher the content, the higher the ammonia injection amount. That is to say, after ignition, as the combustion gun is re-ignited, NO X As the concentration rises slowly, the amount of ammonia sprayed should also increase slowly; after reaching the stable period, fine-tune the combustion: after the combustion is stable, according to NO X Fine-tune the amount of ammonia sprayed according to slight fluctuations.

[0094] Exemplarily, the 20 minutes after the fire change is a preset time period, and each time period corresponds to an amount of ammonia injection. If the kiln needs to change the fire, the steps are to change the left fire first and then the right fire; the left fire and the right fire are divided into time periods, that is, the 20 minutes after the fire change is divided into 6 time periods, and the time periods when the left fire is burning are named: left fire preparation period T1, low fluctuation period T2L, high fluctuation period T2H, low stability period T3L, medium stability period T3M, high stability period T3H; the time periods when the left fire is burning are named It is: right fire preparation period T4, low fluctuation period T5L, high fluctuation period T5H, low stable period T6L, medium stable period T6M, high stable period T6H; here high, medium and low are the high, medium and low initial concentrations of nitrogen oxides corresponding to this fire period, and a bright red indication will be made when each time period arrives to facilitate program debugging and control; among them, T1+T2L+T2H+T3L+T3M+T3H=1200s, T4+T5L+T5H+T6L+T6M+T6H=1200s.

[0095] For the above time segments, the first compensation coefficient K is respectively corresponding, the left fire preparation period T1 is provided with K1, the low fluctuation period T2L is provided with K2L, the high fluctuation period T2H is provided with K2H, the low stable period T3L is provided with K3L, the medium stable period T3M is provided with K3M, and the high stable period T3H is provided with K3H; the right fire preparation period T4 is provided with K4, the low fluctuation period T5L is provided with K5L, the high fluctuation period T5H is provided with K5H, the low stable period T6L is provided with K6L, the medium stable period T6M is provided with K6M, and the high stable period T6H is provided with K6H, and the reference ammonia injection amount Qbase (fixed value, which can be adjusted manually) is set, K*reference ammonia injection amount Qbase=actual ammonia injection amount Qactual, that is, each time period corresponds to an actual ammonia injection amount, and the automatic adjustment of the ammonia injection amount can be based on the PID adjustment of the regulating valve or the PID adjustment of the variable frequency pump.

[0096] In one embodiment, the preset time period includes 6 time segments, wherein the 6 time segments are respectively a fire preparation period, a low fluctuation period, a high fluctuation period, a low stability period, a medium stability period and a high stability period, and the step of injecting a reference ammonia amount input in each time period includes the following steps:

[0097] The fire preparation period, low fluctuation period, high fluctuation period, low stability period, medium stability period and high stability period are timed separately;

[0098] When the time length of the high stability period reaches the preset time length, if the time node of the next fire change has not yet arrived, the reference ammonia injection amount corresponding to the high stability period continues to be input; or,

[0099] When the timing time length in the high stability period does not reach the preset time length, if it is advanced to the time node of the next fire change, the reference ammonia injection amount of the fire preparation period corresponding to the fire change is input.

[0100] The preset time period is subdivided into six stages: fire preparation period, low fluctuation period, high fluctuation period, low stability period, medium stability period and high stability period. Each stage is timed independently to track the duration of each stage. In the high stability period, when the timing time reaches the preset time length, the control signal generated by the control system of the kiln for fire change operation is obtained, and the time node of fire change is obtained according to the change of the control signal. If the time node of the next fire change has not been detected, the reference ammonia injection amount corresponding to the high stability period will continue to be input. If the timing time in the high stability period does not reach the preset time period, but the time node of the next fire change is detected in advance, the system will switch to the fire preparation period and input the corresponding reference ammonia injection amount. According to the current stage and timing results, the ammonia injection amount is adjusted to ensure the denitrification effect of each stage. That is, when the fire change operation is detected, the system will adjust to the corresponding reference ammonia injection amount according to the stage after the fire change. In addition, by recording the duration, ammonia injection amount and related operation data of each stage, it is convenient for subsequent analysis and optimization, and the ammonia injection amount can be managed more accurately and effectively to ensure denitrification efficiency and environmental compliance, while reducing operating costs and environmental impact.

[0101] In one embodiment, the step S300 of obtaining the actual input value of nitrogen oxides at the flue gas inlet, obtaining a first compensation coefficient K according to the actual input value of nitrogen oxides and a preset reference value of nitrogen oxides at the flue gas inlet, and the first compensation coefficient K is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount, further includes the following steps:

[0102] During the low stable period, medium stable period and high stable period after the fire change, the real-time nitrogen oxide concentration at the flue gas inlet is obtained;

[0103] The average concentration of nitrogen oxides at the flue gas inlet during the low stable period, the medium stable period and the high stable period is obtained by calculation, and the average content of nitrogen oxides is the actual input value of nitrogen oxides.

[0104] During the low stable period, medium stable period and high stable period after the fire change, the real-time nitrogen oxide concentration at the flue gas inlet is obtained, and the average nitrogen oxide content at the flue gas inlet during the low stable period, medium stable period and high stable period is calculated. The average nitrogen oxide content is the actual input value of nitrogen oxides. The first compensation coefficient K is obtained according to the actual input value of nitrogen oxides and the preset reference value. The first compensation coefficient K is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount. By accurately controlling the ammonia injection amount, it is possible to ensure that the molar ratio of ammonia to nitrogen oxides is maintained at the optimal state at different stages, thereby improving the denitrification efficiency. Accurate ammonia injection control helps reduce ammonia waste and reduce operating costs.

[0105] In one embodiment, a reference value of nitrogen oxides at the flue gas inlet is preset, an actual input value of nitrogen oxides at the flue gas inlet is obtained, a first compensation coefficient K is obtained according to the actual input value of nitrogen oxides and the reference value, and the first compensation coefficient K is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount. The step also includes the following steps:

[0106] Obtaining a first compensation coefficient K according to a ratio of an actual input value of nitrogen oxides to a reference value of nitrogen oxides;

[0107] The actual ammonia injection amount is obtained by multiplying the obtained first compensation coefficient K and the reference ammonia injection amount.

[0108] By determining the nitrogen oxides (NO X ) is a preset benchmark value. The preset benchmark value is based on environmental protection standards or the best operating experience of the kiln. The actual concentration of nitrogen oxides at the flue gas inlet is monitored in real time and recorded. Use the formula: actual input value of nitrogen oxides / benchmark value = first compensation coefficient K. According to the calculated first compensation coefficient K, adjust the benchmark ammonia injection amount: first compensation coefficient K*benchmark ammonia injection amount = actual ammonia injection amount Qactual. If the first compensation coefficient K is greater than 1, it means that the actual nitrogen oxide concentration is higher than the benchmark value, and the ammonia injection amount needs to be increased. If the first compensation coefficient K is less than 1, it means that the actual nitrogen oxide concentration is lower than the benchmark value, and the ammonia injection amount needs to be reduced. According to the calculated actual ammonia injection amount, ensure that the ammonia injection amount matches the actual concentration of nitrogen oxides. Through real-time monitoring and adjustment, ensure that the ammonia-nitrogen molar ratio remains in the optimal state, improve the denitrification efficiency, respond quickly to changes in nitrogen oxide concentration, and adjust the ammonia injection amount in time. Avoid excessive ammonia spraying, reduce ammonia waste, and reduce operating costs; reduce ammonia escape and nitrogen oxide emissions, and reduce environmental pollution.

[0109] The technical solution of the present invention obtains the time node of the kiln for fire-changing operation, and forms a preset time period for maintaining firepower between two adjacent time nodes; splits the preset time period into several time segments, and inputs different reference ammonia injection amounts corresponding to different time segments; presets the reference value of nitrogen oxides at the flue gas inlet, obtains the actual input value of nitrogen oxides at the flue gas inlet, and obtains the first compensation coefficient K according to the actual input value of nitrogen oxides and the reference value, and the first compensation coefficient K is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount. By determining the time node of the fire-changing operation, the firepower maintenance period is divided into a preset time period, and the preset time period is further subdivided into time segments, the appropriate reference ammonia injection amount can be set in advance for different working conditions of the kiln in different time periods; in addition, in each time segment, the ammonia injection amount is input according to the preset reference value, and the ammonia injection amount can be adjusted in real time according to the change of the inlet monitoring data, thereby improving the accuracy of ammonia injection; and by real-time monitoring the actual concentration of nitrogen oxides at the flue gas inlet, and comparing it with the preset reference value to obtain the first compensation coefficient K, the reference ammonia injection amount is adjusted using the first compensation coefficient K to obtain the actual ammonia injection amount, which can achieve more precise control and reduce ammonia consumption.

[0110] The present invention also proposes an ammonia injection control system for furnace flue gas denitrification, referring to Figure 2 The ammonia injection control system for furnace flue gas denitrification includes a first acquisition module 1, a splitting module 2, a second acquisition module 3, a third acquisition module 4, and a calculation module 5, wherein the calculation module 5 is respectively connected to the first acquisition module 1, the splitting module 2, the second acquisition module 3, and the third acquisition module 4; the first acquisition module 1 is used to obtain the time node of the kiln for fire-changing operation, and a preset time period for maintaining firepower is formed between two adjacent time nodes; the splitting module 2 is used to split the preset time period into a plurality of time segments, and different time segments correspond to different reference ammonia injection amounts; the second acquisition module 3 is used to obtain the actual input value of nitrogen oxides at the flue gas inlet; the third acquisition module 4 is used to obtain the preset reference value of nitrogen oxides at the flue gas inlet; the calculation module 5 is used to obtain the first compensation coefficient K according to the actual input value and the reference value of nitrogen oxides, and the first compensation coefficient K is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount.

[0111] The function of the first acquisition module 1 is to monitor and obtain the time node of the kiln fire-changing operation, and its role is to determine the moment of the fire-changing operation so that the system knows when to start a new preset time period. The function of the splitting module 2 is to subdivide the preset time period into multiple time segments, and set different benchmark ammonia injection amounts for each time period, which allows the system to adjust the ammonia injection amount according to the combustion characteristics of the kiln in different time periods. The function of the second acquisition module 4 is to monitor and obtain the actual concentration value of nitrogen oxides at the flue gas inlet in real time, and its role is to provide actual data of nitrogen oxides in actual operation for adjusting the ammonia injection amount. The function of the third acquisition module 3 is to obtain the preset benchmark value of nitrogen oxides at the flue gas inlet, and the benchmark value is used to provide a reference value for subsequent comparison of actual nitrogen oxide values. The function of the calculation module 5 is to calculate the first compensation coefficient K based on the actual input value of nitrogen oxides and the preset benchmark value, and adjust the benchmark ammonia injection amount accordingly to obtain the actual ammonia injection amount, which is to ensure that the ammonia injection amount matches the concentration of nitrogen oxides and optimize the denitrification efficiency. The system can monitor the concentration of nitrogen oxides in real time and adjust the amount of ammonia injection in time. By subdividing the time period and setting different baseline ammonia injection amounts, the system can adapt to different combustion conditions. By calculating the first compensation coefficient, the system can accurately control the molar ratio of ammonia and nitrogen, improve denitrification efficiency, optimize the use of ammonia, reduce waste, reduce operating costs, reduce ammonia escape and nitrogen oxide emissions, and reduce environmental pollution.

[0112] The present invention also proposes an ammonia injection control device for furnace flue gas denitrification, referring to Figure 3 The ammonia injection control device for furnace flue gas denitrification includes a first detection device 6, a concentration detection device, an ammonia input device 7, a second detection device 8, a third detection device 9 and a controller 10. The first detection device 6 is arranged at the flue gas inlet of the denitrification reactor, and the first detection device 6 is used to obtain data on the actual input value of nitrogen oxides at the flue gas inlet; the ammonia input device 7 is used to control the amount of ammonia sprayed into the denitrification reactor; the second detection device 8 is connected to the ammonia input device 7, and the second detection device 8 is used to obtain data on the actual amount of ammonia sprayed; the third detection device 9 is arranged at the flue gas outlet of the denitrification reactor, and the third detection device 9 is used to obtain data on the actual input value of nitrogen oxides at the flue gas outlet; the controller 10 is respectively connected to the first detection device 6, the ammonia input device 7, the second detection device 8, and the third detection device 9; the control device is used to execute the ammonia injection control method for furnace flue gas denitrification according to any one of claims 1 to 8.

[0113] The first detection device 6 is installed at the flue gas inlet of the denitration reactor, and is used to obtain data on the actual input value of nitrogen oxides at the flue gas inlet; the ammonia input device 7 is connected to the denitration reactor, and is used to control the amount of ammonia input into the denitration reactor; the second detection device 8 is connected to the ammonia input device 7, and is used to obtain data on the actual amount of ammonia sprayed. The third detection device 9 is installed at the flue gas outlet of the denitration reactor, and is used to obtain data on the actual input value of nitrogen oxides at the flue gas outlet; the controller 10 is connected to the first detection device 6, the second detection device 8, the third detection device 9 and the ammonia input device 7, and is used to execute the ammonia spray control method, including obtaining data, calculating compensation coefficients, adjusting the amount of ammonia sprayed, etc. The concentration of nitrogen oxides in the flue gas and the amount of ammonia sprayed are monitored in real time by the detection device; according to the monitoring data, the controller 10 accurately adjusts the ammonia input device 7 to optimize the amount of ammonia sprayed; by comparing the concentration of nitrogen oxides at the flue gas inlet and outlet, closed-loop control is achieved; the controller 10 automatically executes the control method, reduces manual intervention, and improves operation efficiency and accuracy; different control strategies can be executed according to different claims.

[0114] The first detection device 6 includes a flow meter and a concentration detector 62. The flow meter is used to detect the input flow of the flue gas. The concentration detector 62 has the function of checking the concentration of nitrogen oxides. The data of the actual input value of nitrogen oxides at the flue gas inlet is obtained through the input flow of the flue gas and the concentration of nitrogen oxides. The second detection device 8 includes a second flow meter, and the third detection device 9 includes a third flow meter. The controller 10 can adopt PCL

[0115] In addition, the ammonia injection control device for furnace flue gas denitrification also includes a combustion-supporting air input device and a mixer 11. The combustion-supporting air input device includes a frequency converter 12, a fan 13 and a fourth detection device 14 connected in sequence. The fourth detection device 14 and the ammonia input device 7 are respectively connected to the mixer 11, and the mixer 11 is connected to the denitrification reactor. The mixer 11 is used to mix the combustion-supporting air and ammonia and then input them into the denitrification reactor. The frequency converter 12 is used to adjust the power of the fan 13 and adjust the air input amount; it should be noted that the frequency converter 12 is electrically connected to the controller 10, and the controller 10 adjusts the speed of the fan 13 through the frequency converter 12.

[0116] The ammonia gas input device 7 further includes an ammonia gas shutoff valve body 15 and a flow regulating valve 16, wherein the ammonia gas shutoff valve body 15 is connected to the second detection device 8, the ammonia gas shutoff valve body 15 is connected to the flow regulating valve 16, and the flow regulating valve 16 is connected to the mixer 11. The ammonia gas shutoff valve body 15 is used to control the input or stop of ammonia gas, and the flow regulating valve 16 is used to adjust the amount of ammonia gas input to the mixer 11, that is, to adjust the amount of ammonia injection.

[0117] The above are only exemplary embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for controlling ammonia injection for denitrification of kiln flue gas, characterized in that: The following steps are involved: Obtain the time nodes of the kiln for the fire-changing operation, and form a preset time period for maintaining the fire power between two adjacent time nodes; The preset time period is divided into several time segments, and different reference ammonia injection amounts are input corresponding to different time segments; Obtain the actual input value of nitrogen oxides at the flue gas inlet; A first compensation coefficient is obtained according to the actual input value of the nitrogen oxides and a preset reference value of the nitrogen oxides at the flue gas inlet, and the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount to obtain the actual ammonia injection amount.

2. The ammonia injection control method for furnace flue gas denitrification according to claim 1, characterized in that: The steps of dividing the preset time period into a plurality of time segments, and inputting different reference ammonia injection amounts corresponding to different time segments, include the following steps: Obtaining an actual average value of the nitrogen oxide content at the flue gas outlet within a preset time, and obtaining a second compensation coefficient according to a preset linear curve of the average value of the nitrogen oxide content at the flue gas outlet within a preset time and the actual average value; On the basis of the reference ammonia injection amount, a corrected reference ammonia injection amount is obtained by adjusting according to the second compensation coefficient.

3. The ammonia injection control method for furnace flue gas denitrification according to claim 1, characterized in that: The step of obtaining the time nodes for the kiln to perform the fire-changing operation and forming a preset time period for maintaining the firepower between two adjacent time nodes comprises the following steps: Obtaining a fire-changing signal generated by a kiln during a fire-changing operation; The time node of the fire change is obtained according to the change of the fire change signal.

4. The ammonia injection control method for furnace flue gas denitrification according to claim 3, characterized in that: The step of obtaining a control signal generated by a control system for a kiln to perform a fire-changing operation, and obtaining a time node for a fire-changing operation according to a change in the control signal, further includes the following steps: Obtaining the fire-changing pulse signal generated when the kiln performs a fire-changing operation; Obtaining a time node for fire switching according to a change in the fire switching pulse signal; or, Obtain the fire-changing long drive signal generated before the kiln performs the fire-changing operation; Obtaining a time node for a fire change according to the fire change long drive signal; or, Obtain different fire-changing point signals generated by changing different fires during kiln fire-changing operations; Obtaining a fire-changing time node according to the change time of the different fire-changing point signals; or, Obtaining the number of fire changes during the kiln fire change operation, and obtaining a fire change counting signal according to the number of fire changes; The time node of the fire change is obtained according to the fire change count signal.

5. The ammonia injection control method for furnace flue gas denitrification according to any one of claims 1 to 4, characterized in that: The step of dividing the preset time period into a plurality of time segments, and inputting different reference ammonia injection amounts corresponding to different time segments, comprises the following steps: The preset time period includes 6 time periods, wherein the 6 time periods are fire preparation period, low fluctuation period, high fluctuation period, low stability period, medium stability period and high stability period, and a benchmark ammonia injection amount is input in each time period.

6. The ammonia injection control method for furnace flue gas denitrification according to claim 5, characterized in that: The preset time period includes 6 time periods, wherein the 6 time periods are respectively a fire preparation period, a low fluctuation period, a high fluctuation period, a low stability period, a medium stability period and a high stability period. The step of injecting a reference ammonia amount input in each time period includes the following steps: timing the fire preparation period, the low fluctuation period, the high fluctuation period, the low stability period, the medium stability period and the high stability period respectively; When the time length of the high stability period reaches the preset time length, if the time node of the next fire change has not yet arrived, the reference ammonia injection amount corresponding to the high stability period continues to be input; or, When the timing time length in the high stability period does not reach the preset time length, if it is advanced to the time node of the next fire change, the reference ammonia injection amount of the fire preparation period corresponding to the fire change is input.

7. The ammonia injection control method for furnace flue gas denitrification according to claim 5, characterized in that: The step of obtaining a first compensation coefficient according to the actual input value of the nitrogen oxides and a preset reference value of the nitrogen oxides at the flue gas inlet, wherein the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount, further includes the following steps: During the low stable period, medium stable period and high stable period after the fire change, the real-time nitrogen oxide concentration at the flue gas inlet is obtained; The average concentration of nitrogen oxides at the flue gas inlet during the low stable period, the medium stable period and the high stable period is obtained by calculation, and the average content of nitrogen oxides is the actual input value of nitrogen oxides.

8. The ammonia injection control method for furnace flue gas denitrification according to any one of claims 1 to 4, characterized in that: The step of obtaining a first compensation coefficient according to the actual input value of the nitrogen oxides and a preset reference value of the nitrogen oxides at the flue gas inlet, wherein the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount, further includes the following steps: Obtaining a first compensation coefficient according to a ratio of an actual input value of nitrogen oxides to a reference value of nitrogen oxides; The actual ammonia injection amount is obtained according to the product of the obtained first compensation coefficient and the reference ammonia injection amount.

9. An ammonia injection control system for furnace flue gas denitrification, characterized in that: The ammonia injection control system for furnace flue gas denitrification is used to implement the ammonia injection control method for furnace flue gas denitrification according to any one of claims 1 to 8, comprising: The first acquisition module is used to acquire the time nodes of the kiln for the fire change operation, and a preset time period for maintaining the fire power is formed between two adjacent time nodes; A splitting module is used to split the preset time period into several time segments, and different time segments correspond to inputting different reference ammonia injection amounts; The second acquisition module is used to obtain the actual input value of nitrogen oxides at the flue gas inlet; A third acquisition module is used to obtain a preset reference value of nitrogen oxides at the flue gas inlet; A calculation module, wherein the calculation module is respectively connected to the first acquisition module, the splitting module, the second acquisition module, and the third acquisition module, and the calculation module is used to obtain a first compensation coefficient according to the actual input value and the reference value of the nitrogen oxides, and the first compensation coefficient is used to adjust the actual ammonia injection amount based on the reference ammonia injection amount.

10. An ammonia injection control device for furnace flue gas denitrification, characterized in that: include: A first detection device, the first detection device is arranged at the flue gas inlet of the denitration reactor, and the first detection device is used to obtain data of an actual input value of nitrogen oxides at the flue gas inlet; An ammonia gas input device, the ammonia gas input device is used to control the amount of ammonia sprayed into the denitration reactor; A second detection device, the second detection device is connected to the ammonia input device, and the second detection device is used to obtain data on actual ammonia injection amount; A third detection device, the third detection device is arranged at the flue gas outlet of the denitration reactor, and the third detection device is used to obtain data of an actual input value of nitrogen oxides at the flue gas outlet; A controller, wherein the controller is respectively connected to the first detection device, the ammonia input device, the second detection device, and the third detection device; the control device is used to execute the ammonia injection control method for kiln flue gas denitrification according to any one of claims 1 to 8.

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