Logic algorithm for automatic optimization of ammonia injection of denitration system of power plant boiler

Abstract

The invention provides a logic algorithm for automatic optimization of ammonia injection of a denitration system of a power plant boiler, and the logic algorithm comprises five parts, and specifically comprises the following steps: determining the optimal ammonia demand amount in real time based on NOx concentration multi-state judgment logic; the NOx concentration change rate of the denitration device is used as feed-forward adjustment logic; automatic parameter switching logic; and adding ammonia to optimize logic and calculating the converted value of the NOx concentration at the outlet of the denitration device. The automatic adjustment quality and the automatic input rate of the denitration system are optimized comprehensively from five aspects, intelligent optimization of the system is achieved, the full-automatic adjustment level is achieved, then the adjustment intensity of operators on ammonia spraying of the denitration system is reduced, and the large-scale application and popularization prospects are wide.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas denitration, and in particular to a logic algorithm for automatically optimizing ammonia injection in a denitration system of a power plant boiler. Background Art

[0002] The denitrification system is an important part of the production process of thermal power plants. Its function is to reduce the NOx content in the flue gas to meet the emission standards, which plays a key role in preventing environmental pollution. At present, the most widely used method in thermal power plants is the selective catalytic reduction (SCR), which uses a reducing agent (liquid nitrogen, ammonia and urea, etc.) to selectively react with NO in the flue gas under the action of a catalyst. x (mainly NO and NO2) undergo chemical reduction reaction to produce nitrogen and water, thereby removing part of the NO in the flue gas x process technology.

[0003] In recent years, as thermal power plant units have increased their participation in deep peak regulation, the denitrification automatic ammonia injection regulation system under conventional load conditions has been unable to meet the current large changes in load, resulting in a low automatic input rate and poor regulation quality, which greatly consumes personnel's adjustment energy and even causes abnormal adjustments that affect the safe operation of equipment.

[0004] CN111506031A discloses a denitration ammonia injection optimization auxiliary debugging system based on WinCC and PLC, comprising: a DCS system module, used to collect combustion parameter data of a boiler and an SCR denitration reactor; a PLC controller module, connected to the DCS system module, used to read the combustion parameter data of the DCS system module, based on the ammonia injection control logic, to control the denitration ammonia injection valve according to the combustion parameter data; a PC module, connected to the PLC controller module, comprising a STEP debugging unit and a WinCC auxiliary debugging unit, used to write and debug the ammonia injection control logic through the STEP debugging unit, and download the written ammonia injection control logic to the PLC controller module, and realize the definition and storage of the combustion parameter data of the boiler and the SCR denitration reactor and the display of the WinCC configuration screen through the WinCC auxiliary debugging unit.

[0005] CN110652866A discloses a method for optimizing the ammonia metering control logic of an SCR flue gas denitration system, including the following steps: step 100, matching the measurement accuracy and measurement range of all measuring instruments with the ammonia actually transported; step 200, setting a sending unit for real-time remote transmission of the measurement results of the temperature measuring instrument; step 300, establishing a main program for controlling the denitration process, and at the same time establishing a flow subroutine for controlling the ammonia injection flow, wherein the flow subroutine includes a temperature calculation feedforward for ammonia. By optimizing the entire ammonia injection system, unifying the measurement accuracy of each device, and adding real-time ammonia temperature measurement, the processing program is divided into modules, so that the modules that process different functions independently form a subroutine, and finally the main program is regulated according to the results of each subroutine, which can not only improve the processing efficiency but also improve the processing accuracy.

[0006] CN117167756A discloses an external boiler denitration ammonia injection control system and control method. The system includes a feedforward compensation module, a fluctuation optimization module, a phase compensation module, an ammonia injection prediction module, a control optimization module and an instruction generation module. The control system is based on the acquired denitration device operation data, including the total coal feed, the total air volume, the nitrogen oxide inlet concentration and the nitrogen oxide outlet concentration calculation, etc., and uses each module to calculate the feedforward compensation value, the phase compensation value, the fluctuation optimization value, the ammonia injection prediction value, etc., and further generates the ammonia injection flow instruction. The system fully considers multiple factors that affect the accuracy of the ammonia injection flow, and can effectively improve the control accuracy of the ammonia injection flow.

[0007] However, the above-mentioned denitrification ammonia injection method still has a low automatic input rate. In the event of equipment failure, abnormal logic and automatic data, abnormal adjustments will occur, affecting the safe operation of the denitrification system equipment. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a logic algorithm for automatically optimizing the ammonia injection of a power plant boiler denitration system. The algorithm adopts appropriate multi-state judgment logic based on NOx concentration, feedforward adjustment logic, parameter automatic switching logic, ammonia addition optimization logic and reasonable conversion of NOx concentration at the outlet of the denitration device to realize automatic optimization of ammonia injection of a power plant boiler denitration system in all aspects, ensure that NOx emissions meet the standards, and save the use of reducing agents. Rapid adjustments can be made in various abnormal situations to ensure the safe operation of the denitration system equipment.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a logic algorithm for automatically optimizing ammonia injection in a power plant boiler denitration system. The logic algorithm includes five parts, specifically:

[0011] The optimal ammonia requirement is determined in real time based on the multi-state judgment logic of NOx concentration; the NOx concentration change rate of the denitrification device is used as the feedforward adjustment logic; the parameter automatic switching logic; the ammonia addition optimization logic and the calculation of the converted value of the NOx concentration at the outlet of the denitrification device.

[0012] The logic algorithm for automatic optimization of ammonia injection in the denitration system of a power plant described in the present invention optimizes the automatic adjustment quality and automatic input rate of the denitration system from five aspects, realizes intelligent optimization of the system, and reaches the level of fully automated adjustment. It mainly adopts a logic adjustment method based on multi-state judgment of NOx concentration to find the optimal ammonia requirement in real time, realizes automatic optimization of the denitration system, and makes the change of NOx concentration at the inlet of the boiler chimney always within the concentration setting range. Compared with feedforward regulation, it can save more reducing agent usage on the basis of ensuring the stability of NOx mean value, avoid unnecessary excessive ammonia injection, and is more conducive to coping with various load conditions and more complex coal quality; the NOx concentration change rate of the denitrification device is used as the feedforward adjustment logic, which can basically cope with all changing conditions of the power plant boiler, making the logic simpler and reducing the burden on the DCS server; the parameter automatic switching logic is used to enable the NOx concentration change to be monitored in real time, so that the logic calculation is continuous and avoids large fluctuations in data; the logic is equipped with a manual input module to facilitate the operation personnel to level the two denitrification devices and deal with emergencies; the ammonia addition optimization logic is adopted to effectively avoid the NOx over-limit problem caused by equipment failure, abnormal logic automatic data, etc.; in view of the oxygen deviation problem caused by leakage in the tail flue, the conversion value of the NOx concentration at the outlet of the denitrification device is used to make the NOx concentration value at the outlet of the denitrification device basically correspond to the NOx concentration value at the inlet of the boiler chimney, so that the operation personnel can accurately control the emission concentration and meet the environmental emission requirements.

[0013] Preferably, the power plant boiler denitration system includes two denitration devices, respectively named as denitration side A and denitration side B.

[0014] Preferably, the real-time determination of the optimal ammonia requirement based on the NOx concentration multi-state judgment logic specifically includes:

[0015] Select a certain data in the calculation formula for the amount of ammonia required for denitrification, and use the inlet NOx concentration, outlet NOx concentration, NOx concentration setting value and the state change of the oxygen quantity parameter for correction to determine the optimal ammonia requirement.

[0016] The calculation formula for the amount of ammonia required for denitrification of the present invention is:

[0017] G=Q×(C1÷M1)×(M1÷M2×C2÷C1+η÷100)÷M2÷1000000

[0018] Where: G is the required ammonia amount;

[0019] Q is the standard denitrification inlet flue gas flow rate;

[0020] C1 is the NOx concentration at the standard denitrification inlet;

[0021] M1 is the molar mass of NO2;

[0022] M2 is the molar mass of NH3;

[0023] C2 is the ammonia escape concentration of standard NH3;

[0024] η is the denitrification efficiency.

[0025] Preferably, the inlet flue gas flow rate in the calculation formula for the ammonia requirement of denitrification is used as the correction data, the total air volume of the boiler is used as the base of the inlet flue gas flow rate for calculating the ammonia requirement on the A side or B side of denitrification, the actual value of the inlet flue gas flow rate on the A side or B side of denitrification is corrected by the correction coefficient, and the inlet NOx concentration on the A side or B side of denitrification, the inlet flue gas flow rate on the A side or B side, and the NOx concentration setting value are used to calculate the optimal ammonia requirement of the denitrification device, so that the real-time NOx concentration is within the set range;

[0026] The set value of NOx concentration in the present invention can be determined according to the actual operation of the power plant boiler and the NOx concentration emission standard.

[0027] Preferably, the real-time NOx concentration includes the NOx concentration at the boiler chimney inlet or the NOx concentration at the denitration device outlet.

[0028] The adjustment logic of the correction coefficient includes:

[0029] ① When the real-time NOx concentration is greater than (NOx concentration setting value + constant) and the real-time NOx concentration average value within the set time period is greater than (NOx concentration setting value - constant) and the real-time NOx concentration change rate is greater than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is accumulated with a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer accumulated with a fixed value, and the correction coefficient accumulated value when the last condition was met is maintained;

[0030] ② When the real-time NOx concentration is less than (NOx concentration setting value - constant) and the real-time NOx concentration average value within the set time period is less than (NOx concentration setting value + constant) and the real-time NOx concentration change rate is less than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is cumulatively reduced by a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer cumulatively reduced by a fixed value, and the correction coefficient cumulative reduction value when the last condition was met is maintained;

[0031] The constants and fixed values ​​are adjusted in real time according to the operating conditions;

[0032] ③ When the accumulated value or the accumulated decrement value of the correction coefficient does not meet the production process requirements, the adjustment personnel manually sets the accumulated value or the accumulated decrement value to 0.

[0033] Preferably, the NOx concentration change rate of the denitrification device includes the NOx concentration change rate at the denitrification device inlet and the NOx concentration change rate at the denitrification device outlet.

[0034] Preferably, the feedforward adjustment logic based on the NOx concentration change rate of the denitration device specifically includes:

[0035] The corresponding coefficient is calculated by the F(x) function based on the NOx concentration change rate of the denitrification device. The coefficient is multiplied by the required ammonia amount, and the required ammonia amount is output in different multiples. When the NOx concentration increase rate at the inlet of each denitrification device or the NOx concentration increase rate at the outlet of each denitrification device is different, the ammonia injection valve is feedforward adjusted.

[0036] Preferably, the logic output coefficient of the F(x) function = (Y n-1 )+(Y n -Y n-1 )÷(X n -Y n-1 )×(XX n-1 );

[0037] Where: X is the current NOx concentration change rate;

[0038] X n It is the value of the X-axis closest to the right of the current NOx concentration change rate;

[0039] X n-1 It is the value of the X-axis closest to the left of the current NOx concentration change rate;

[0040] Y n Corresponding to X n The value of the Y axis;

[0041] Y n-1 Corresponding to X n-1 The value of the Y axis;

[0042] (Y n -Y n-1 )÷(X n -Y n-1 ) is the slope of the broken line segment corresponding to the current NOx concentration change rate;

[0043] XX n-1 The value where the rate of change of NOx concentration is higher than the nearest value on the left.

[0044] Preferably, the automatic parameter switching logic specifically includes:

[0045] In the calculation of the optimal ammonia demand, when the inlet NOx analyzer on one side of the denitrification sends a calibration signal, a fault signal or a maintenance signal and the oxygen parameter exceeds the set range, and the oxygen content of the inlet NOx analyzer on the other side of the denitrification is less than a certain value, the inlet flue gas NOx concentration data referenced in the calculation of the optimal ammonia demand on this side will be switched to the other side as its inlet flue gas NOx concentration data.

[0046] The automatic parameter switching logic of the present invention satisfies the continuity of the calculation of the required ammonia amount and solves the problem of sudden changes in values ​​caused by the normal working process of the instrument.

[0047] Preferably, the ammonia addition optimization logic includes increasing the amount of ammonia or forcibly fully opening the ammonia injection regulating valve according to the average value of NOx concentration at the boiler chimney inlet and the instantaneous value of NOx concentration at the boiler chimney inlet.

[0048] Preferably, when the ammonia injection regulating valve is in the automatic state, the ammonia amount is increased; when the ammonia injection regulating valve is in the manual state, the ammonia injection regulating valve is forced to be fully opened.

[0049] The ammonia addition optimization logic of the present invention increases a specific ammonia injection amount when corresponding conditions are met, thereby solving the NOx over-limit problem caused by equipment failure, abnormal logic automatic data, etc.

[0050] Preferably, the converted value of the NOx concentration at the outlet of the denitrification device is obtained by calculating the difference between the converted value of the NOx concentration at the inlet of the boiler chimney and the measured value through the F'(x) function to obtain a corresponding coefficient, which is multiplied by the NOx concentration at the outlet of the denitrification device.

[0051] The data of NOx concentration at the boiler chimney inlet directly measured by the on-site instrument device is the measured value, and the value converted by 6% oxygen content is the converted value of NOx concentration at the boiler chimney inlet.

[0052] Preferably, the logic output coefficient of the F'(x) function = (Y' n-1 )+(Y' n -Y' n-1 )÷(X' n -Y' n-1 )×(X'-X' n-1 );

[0053] Where: X' is the current difference;

[0054] X' n It is the value of the X' axis closest to the right of the current difference;

[0055] X' n-1 It is the value of the X' axis nearest to the left of the current difference;

[0056] Y' n Corresponding to X n The value of the Y' axis;

[0057] Y' n-1 Corresponding to X n-1 The value of the Y' axis;

[0058] (Y' n -Y' n-1 )÷(X' n -Y' n-1 ) is the slope of the broken line segment corresponding to the current difference;

[0059] X'-X' n-1 is the value whose difference is higher than the nearest value to the left.

[0060] The converted value of the NOx concentration at the outlet of the denitrification device of the present invention solves the problem that the NOx concentration values ​​at the outlet of the denitrification device and the inlet of the boiler chimney do not correspond when the oxygen content is different during the full load period. The functional relationship is adopted to change with the load according to the NOx concentration setting, so as to solve the problem that the operator needs to change the setting of the outlet concentration of the denitrification device during high and low load periods, and effectively control the emission during the non-load period.

[0061] As a preferred technical solution of the present invention, the logic algorithm includes 5 parts, specifically:

[0062] The power plant boiler denitration system includes two denitration devices, respectively named as denitration A side and denitration B side;

[0063] (1) Determine the optimal ammonia requirement in real time based on the multi-state judgment logic of NOx concentration;

[0064] The real-time determination of the optimal ammonia requirement based on the NOx concentration multi-state judgment logic specifically includes:

[0065] Select a certain data in the calculation formula of ammonia requirement for denitrification, and use the state changes of inlet NOx concentration, outlet NOx concentration, NOx concentration setting value and oxygen quantity parameters for correction to determine the optimal ammonia requirement;

[0066] The inlet flue gas flow rate in the calculation formula for the required ammonia for denitrification is used as the correction data, and the total air volume of the boiler is used as the base of the inlet flue gas flow rate for calculating the required ammonia for the denitrification side A or B. The actual value of the inlet flue gas flow rate for the denitrification side A or B is corrected by the correction coefficient, and the optimal ammonia requirement for the denitrification device is calculated using the inlet NOx concentration for the denitrification side A or B, the inlet flue gas flow rate for the denitrification side A or B, and the set value of NOx concentration, so that the real-time NOx concentration is within the set range;

[0067] The real-time NOx concentration includes the NOx concentration at the boiler chimney inlet or the NOx concentration at the denitration device outlet;

[0068] The adjustment logic of the correction coefficient includes:

[0069] ① When the real-time NOx concentration is greater than (NOx concentration setting value + constant) and the real-time NOx concentration average value within the set time period is greater than (NOx concentration setting value - constant) and the real-time NOx concentration change rate is greater than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is accumulated with a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer accumulated with a fixed value, and the correction coefficient accumulated value when the last condition was met is maintained;

[0070] ② When NOx concentration is less than (NOx concentration setting value - constant) and the real-time NOx concentration average value within the set time period is less than (NOx concentration setting value + constant) and the real-time NOx concentration change rate is less than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is cumulatively reduced by a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer cumulatively reduced by a fixed value, and the correction coefficient cumulative reduction value when the last condition was met is maintained;

[0071] The constants and fixed values ​​are adjusted in real time according to the operating conditions;

[0072] ③ When the accumulated value or accumulated decrement of the correction coefficient does not meet the production process requirements, the adjustment personnel manually set the accumulated value or accumulated decrement to 0;

[0073] (2) The rate of change of NOx concentration in the denitrification device is used as the feedforward adjustment logic;

[0074] The NOx concentration change rate of the denitration device includes the NOx concentration change rate at the denitration device inlet and the NOx concentration change rate at the denitration device outlet;

[0075] The feedforward adjustment logic based on the NOx concentration change rate of the denitration device specifically includes:

[0076] The corresponding coefficient is calculated by the F(x) function based on the rate of change of NOx concentration in the denitration device. The coefficient is multiplied by the required ammonia amount, and the required ammonia amount is output in different multiples. When the rate of increase of NOx concentration at the inlet of each denitration device or the rate of increase of NOx concentration at the outlet of each denitration device is different, the ammonia injection valve is feedforward adjusted; the logic output coefficient of the F(x) function = (Y n-1 )+(Y n -Y n-1 )÷(X n -Y n-1 )×(XX n-1 );

[0077] Where: X is the current NOx concentration change rate;

[0078] X n It is the value of the X-axis closest to the right of the current NOx concentration change rate;

[0079] X n-1It is the value of the X-axis closest to the left of the current NOx concentration change rate;

[0080] Y n Corresponding to X n The value of the Y axis;

[0081] Y n-1 Corresponding to X n-1 The value of the Y axis;

[0082] (Y n -Y n-1 )÷(X n -Y n-1 ) is the slope of the broken line segment corresponding to the current NOx concentration change rate;

[0083] XX n-1 It is the value where the rate of change of NOx concentration is higher than the nearest value on the left;

[0084] (3) Parameter automatic switching logic;

[0085] The automatic parameter switching logic specifically includes:

[0086] In the calculation of the optimal ammonia demand, when the inlet NOx analyzer on one side of the denitrification sends a calibration signal, a fault signal or a maintenance signal and the oxygen content parameter exceeds the set range, and the oxygen content of the inlet NOx analyzer on the other side of the denitrification is less than a certain value, the inlet flue gas NOx concentration data referenced by the optimal ammonia demand calculation on this side is switched to the other side as its inlet flue gas NOx concentration data;

[0087] (4) Ammonia addition optimization logic;

[0088] The ammonia addition optimization logic includes increasing the amount of ammonia or forcibly fully opening the ammonia injection valve according to the average value of NOx concentration at the boiler chimney inlet and the instantaneous value of NOx concentration at the boiler chimney inlet;

[0089] When the ammonia injection regulating valve is in the automatic state, the ammonia amount is increased; when the ammonia injection regulating valve is in the manual state, the ammonia injection regulating valve is forced to be fully opened;

[0090] (5) Calculate the converted value of NOx concentration at the outlet of the denitrification device;

[0091] The converted value of the NOx concentration at the outlet of the denitrification device is obtained by calculating the difference between the converted value of the NOx concentration at the inlet of the boiler chimney and the measured value through the F'(x) function to obtain a corresponding coefficient, which is multiplied by the NOx concentration at the outlet of the denitrification device;

[0092] The F'(x) function logic output coefficient = (Y' n-1 )+(Y' n -Y' n-1 )÷(X' n -Y'n-1 )×(X'-X' n-1 );

[0093] Where: X' is the current difference;

[0094] X' n It is the value of the X' axis closest to the right of the current difference;

[0095] X' n-1 It is the value of the X' axis nearest to the left of the current difference;

[0096] Y' n Corresponding to X n The value of the Y' axis;

[0097] Y' n-1 Corresponding to X n-1 The value of the Y' axis;

[0098] (Y' n -Y' n-1 )÷(X' n -Y' n-1 ) is the slope of the broken line segment corresponding to the current difference;

[0099] X'-X' n-1 is the value whose difference is higher than the nearest value to the left.

[0100] Compared with the prior art, the present invention has at least the following beneficial effects:

[0101] The logic algorithm for automatic optimization of ammonia injection in a power plant boiler denitration system provided by the present invention improves the automatic adjustment quality and automatic input rate of the denitration system, achieving a fully automatic adjustment level; and greatly reduces the adjustment intensity of operating personnel, achieving good results in saving reducing agents and controlling ammonia escape. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Figure 1 It is the logical relationship between the correction coefficients of the A and B sides of denitrification, the inlet flue gas flow rate and the total air volume of the power plant boiler.

[0103] Figure 2 It is the automatic optimization logic of the denitrification A-side correction coefficient.

[0104] Figure 3 It is the automatic optimization logic of the denitrification B-side correction coefficient.

[0105] Figure 4 It is the logic for adjusting the deviation between the NOx concentration at the A-side outlet of denitrification and the boiler chimney inlet and the set value.

[0106] Figure 5 It is the logic for adjusting the deviation between the NOx concentration at the B-side outlet of denitrification and the boiler chimney inlet and the set value.

[0107] Figure 6 It is the feedforward logic for the change rate of NOx concentration at the inlet and outlet of the denitrification A side.

[0108] Figure 7 It is the feedforward logic for the change rate of NOx concentration at the inlet and outlet of the denitrification B side.

[0109] Figure 8 It is the reference data switching logic and judgment for calculating the ammonia requirement on the A side of denitrification.

[0110] Fig. 9 It is the reference data switching logic and judgment for calculating the ammonia requirement on the denitrification B side.

[0111] Fig.10 It is the optimization logic of adding ammonia on the A side of denitrification.

[0112] Fig.11 It is the optimization logic of adding ammonia on the B side of denitrification.

[0113] Fig.12 It is the logical relationship between the NOx concentration at the outlet of the A and B sides of denitrification and the NOx concentration at the inlet of the boiler chimney. DETAILED DESCRIPTION

[0114] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0115] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0116] As a specific embodiment of the present invention, a logic algorithm for automatically optimizing ammonia injection in a power plant boiler denitration system is provided, wherein the power plant boiler denitration system includes two denitration devices, respectively named as denitration A side and denitration B side;

[0117] The logic algorithm includes five parts, specifically:

[0118] (1) Determine the optimal ammonia requirement in real time based on the multi-state judgment logic of NOx concentration;

[0119] The real-time determination of the optimal ammonia requirement based on the NOx concentration multi-state judgment logic specifically includes:

[0120] Select a certain data in the calculation formula for the amount of ammonia required for denitrification, and use the inlet NOx concentration, outlet NOx concentration, NOx concentration setting value and the state change of the oxygen quantity parameter for correction to determine the optimal ammonia requirement.

[0121] The inlet flue gas flow rate in the calculation formula for the required ammonia for denitrification is used as the correction data, and the total air volume of the boiler is used as the base of the inlet flue gas flow rate for calculating the required ammonia for the denitrification side A or B. The actual value of the inlet flue gas flow rate for the denitrification side A or B is corrected by the correction coefficient, and the optimal ammonia requirement for the denitrification device is calculated using the inlet NOx concentration for the denitrification side A or B, the inlet flue gas flow rate for the denitrification side A or B, and the set value of NOx concentration, so that the real-time NOx concentration is within the set range;

[0122] The real-time NOx concentration includes the NOx concentration at the boiler chimney inlet or the NOx concentration at the denitration device outlet;

[0123] The logical relationship between the correction coefficients of the A and B sides of denitrification, the inlet flue gas flow rate and the total air volume of the power plant boiler is as follows: Figure 1 As shown;

[0124] The automatic optimization logic of the correction coefficient of denitrification side A is as follows Figure 2 As shown; the automatic optimization logic of the correction coefficient of the denitrification B side is as follows Figure 3 As shown;

[0125] The adjustment logic of the NOx concentration deviation from the set value at the outlet of the denitrification side A and the boiler chimney inlet is as follows: Figure 4 As shown; the adjustment logic of NOx concentration deviation from the set value at the outlet of denitration side B and the inlet of boiler chimney is as follows Figure 5 As shown;

[0126] The adjustment logic of the correction coefficient includes:

[0127] ① When the real-time NOx concentration is greater than (NOx concentration setting value + constant) and the real-time NOx concentration average value within the set time period is greater than (NOx concentration setting value - constant) and the real-time NOx concentration change rate is greater than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is accumulated with a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer accumulated with a fixed value, and the correction coefficient accumulated value when the last condition was met is maintained;

[0128] ② When the real-time NOx concentration is less than (NOx concentration setting value - constant) and the real-time NOx concentration setting average value within a fixed time period is less than (NOx concentration setting value + constant) and the real-time NOx concentration change rate is less than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is cumulatively reduced by a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer cumulatively reduced by a fixed value, and the correction coefficient cumulative reduction value when the last condition was met is maintained;

[0129] The constants and fixed values ​​are adjusted in real time according to the operating conditions;

[0130] ③ When the accumulated value or accumulated decrement of the correction coefficient does not meet the production process requirements, the adjustment personnel manually set the accumulated value or accumulated decrement to 0;

[0131] (2) The rate of change of NOx concentration in the denitrification device is used as the feedforward adjustment logic;

[0132] The NOx concentration change rate of the denitration device includes the NOx concentration change rate at the denitration device inlet and the NOx concentration change rate at the denitration device outlet;

[0133] The feedforward logic of the NOx concentration rate change at the inlet and outlet of the denitrification A side is as follows Figure 6 As shown; the feedforward logic of the change of NOx concentration rate at the inlet and outlet of denitrification B side is as follows Figure 7 As shown;

[0134] The feedforward adjustment logic based on the NOx concentration change rate of the denitration device specifically includes:

[0135] The corresponding coefficient is calculated by the F(x) function based on the rate of change of NOx concentration in the denitration device. The coefficient is multiplied by the required ammonia amount, and the required ammonia amount is output in different multiples. When the rate of increase of NOx concentration at the inlet of each denitration device or the rate of increase of NOx concentration at the outlet of each denitration device is different, the ammonia injection valve is feedforward adjusted;

[0136] The logical output coefficient of the F(x) function = (Y n-1 )+(Y n -Y n-1 )÷(X n -Y n-1 )×(XX n-1 );

[0137] Where: X is the current NOx concentration change rate;

[0138] X n It is the value of the X-axis closest to the right of the current NOx concentration change rate;

[0139] X n-1 It is the value of the X-axis closest to the left of the current NOx concentration change rate;

[0140] Y n Corresponding to X n The value of the Y axis;

[0141] Y n-1 Corresponding to X n-1 The value of the Y axis;

[0142] (Y n -Y n-1 )÷(X n -Y n-1 ) is the slope of the broken line segment corresponding to the current NOx concentration change rate;

[0143] XX n-1It is the value where the rate of change of NOx concentration is higher than the nearest value on the left;

[0144] (3) Parameter automatic switching logic;

[0145] The automatic parameter switching logic specifically includes:

[0146] Denitrification A side ammonia demand calculation reference data switching logic and judgment Figure 8 As shown, the calculation of the required ammonia amount on the denitrification side B refers to the switching logic and judgment of the data. Fig. 9 As shown;

[0147] In the calculation of the optimal ammonia demand, when the inlet NOx analyzer on one side of the denitrification sends a calibration signal, a fault signal or a maintenance signal and the oxygen content parameter exceeds the set range, and the oxygen content of the inlet NOx analyzer on the other side of the denitrification is less than a certain value, the inlet flue gas NOx concentration data referenced by the optimal ammonia demand calculation on this side is switched to the other side as its inlet flue gas NOx concentration data;

[0148] (4) Ammonia addition optimization logic;

[0149] Denitrification A side ammonia addition optimization logic is as follows Fig.10 As shown; the optimization logic of adding ammonia to the denitrification B side is as follows Fig.11 As shown;

[0150] The ammonia addition optimization logic includes increasing the amount of ammonia or forcibly fully opening the ammonia injection valve according to the average value of NOx concentration at the boiler chimney inlet and the instantaneous value of NOx concentration at the boiler chimney inlet;

[0151] When the ammonia injection regulating valve is in the automatic state, the ammonia amount is increased; when the ammonia injection regulating valve is in the manual state, the ammonia injection regulating valve is forced to be fully opened;

[0152] (5) Calculate the converted value of NOx concentration at the outlet of the denitrification device;

[0153] The converted value of the NOx concentration at the outlet of the denitrification device is obtained by calculating the difference between the converted value of the NOx concentration at the inlet of the boiler chimney and the measured value through the F'(x) function to obtain a corresponding coefficient, which is multiplied by the NOx concentration at the outlet of the denitrification device;

[0154] The logical relationship between the NOx concentration at the outlet of the A and B sides of denitrification and the NOx concentration at the inlet of the boiler chimney is as follows: Fig.12 As shown;

[0155] The F'(x) function logic output coefficient = (Y' n-1 )+(Y' n -Y' n-1 )÷(X' n -Y' n-1 )×(X'-X' n-1 );

[0156] Where: X' is the current difference;

[0157] X' n It is the value of the X' axis closest to the right of the current difference;

[0158] X' n-1 It is the value of the X' axis nearest to the left of the current difference;

[0159] Y' n Corresponding to X n The value of the Y' axis;

[0160] Y' n-1 Corresponding to X n-1 The value of the Y' axis;

[0161] (Y' n -Y' n-1 )÷(X' n -Y' n-1 ) is the slope of the broken line segment corresponding to the current difference;

[0162] X'-X' n-1 is the value whose difference is higher than the nearest value to the left.

[0163] In summary, the logic algorithm for automatic optimization of ammonia injection in a power plant boiler denitrification system provided by the present invention adopts a multi-state judgment logic based on NOx concentration to determine the optimal ammonia requirement in real time, a feedforward adjustment logic based on the NOx concentration change rate of the denitrification device, automatic parameter switching logic, ammonia addition optimization logic and calculation of the converted value of the NOx concentration at the outlet of the denitrification device, which improves the automatic adjustment quality and automatic input rate of the denitrification system, reaches the fully automated adjustment level, reduces the adjustment intensity of the operating personnel, and achieves the good effect of saving reducing agents and controlling ammonia escape; it can quickly respond to and handle abnormalities in the denitrification system, ensure the safe operation of the equipment, and is suitable for large-scale promotion and application.

[0164] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A logical algorithm for automatically optimizing ammonia injection in a power plant boiler denitration system, characterized in that: The logic algorithm includes five parts, specifically: The optimal ammonia requirement is determined in real time based on the multi-state judgment logic of NOx concentration; the NOx concentration change rate of the denitrification device is used as the feedforward adjustment logic; the parameter automatic switching logic; the ammonia addition optimization logic and the calculation of the converted value of the NOx concentration at the outlet of the denitrification device.

2. The logic algorithm according to claim 1, characterized in that: The power plant boiler denitration system includes two denitration devices, respectively named as denitration A side and denitration B side; Preferably, the real-time determination of the optimal ammonia requirement based on the NOx concentration multi-state judgment logic specifically includes: Select a certain data in the calculation formula of ammonia requirement for denitrification, and use the state changes of inlet NOx concentration, outlet NOx concentration, NOx concentration setting value and oxygen quantity parameters for correction to determine the optimal ammonia requirement; Preferably, the inlet flue gas flow rate in the calculation formula for the ammonia requirement of denitrification is used as the correction data, the total air volume of the boiler is used as the base of the inlet flue gas flow rate for calculating the ammonia requirement on the A side or B side of denitrification, the actual value of the inlet flue gas flow rate on the A side or B side of denitrification is corrected by the correction coefficient, and the inlet NOx concentration on the A side or B side of denitrification, the inlet flue gas flow rate on the A side or B side, and the NOx concentration setting value are used to calculate the optimal ammonia requirement of the denitrification device, so that the real-time NOx concentration is within the set range; Preferably, the real-time NOx concentration includes the NOx concentration at the boiler chimney inlet or the NOx concentration at the denitration device outlet.

3. The logic algorithm according to claim 2, characterized in that: The adjustment logic of the correction coefficient includes: ① When the real-time NOx concentration is greater than (NOx concentration setting value + constant) and the real-time NOx concentration average value within the set time period is greater than (NOx concentration setting value - constant) and the real-time NOx concentration change rate is greater than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is accumulated with a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer accumulated with a fixed value, and the correction coefficient accumulated value when the last condition was met is maintained; ② When the real-time NOx concentration is less than (NOx concentration setting value - constant) and the real-time NOx concentration average value within the set time period is less than (NOx concentration setting value + constant) and the real-time NOx concentration change rate is less than 0, the following logic is executed: when it is detected that the above conditions are met, the correction coefficient is cumulatively reduced by a fixed value; when it is detected that the above conditions are not met, the correction coefficient is no longer cumulatively reduced by a fixed value, and the correction coefficient cumulative reduction value when the last condition was met is maintained; The constants and fixed values ​​are adjusted in real time according to the operating conditions; Preferably, the real-time NOx concentration includes the NOx concentration at the boiler chimney inlet or the NOx concentration at the denitration device outlet; ③ When the accumulated value or the accumulated decrement value of the correction coefficient does not meet the production process requirements, the adjustment personnel manually sets the accumulated value or the accumulated decrement value to 0.

4. The logic algorithm according to any one of claims 1 to 3, characterized in that: The NOx concentration change rate of the denitration device includes the NOx concentration change rate at the denitration device inlet and the NOx concentration change rate at the denitration device outlet; Preferably, the feedforward adjustment logic based on the NOx concentration change rate of the denitration device specifically includes: The corresponding coefficient is calculated by the F(x) function based on the NOx concentration change rate of the denitrification device. The coefficient is multiplied by the required ammonia amount, and the required ammonia amount is output in different multiples. When the NOx concentration increase rate at the inlet of each denitrification device or the NOx concentration increase rate at the outlet of each denitrification device is different, the ammonia injection valve is feedforward adjusted.

5. The logic algorithm according to claim 4, characterized in that: The F(x) function logic output coefficient = (Y n-1 )+(Y n -Y n-1 )÷(X n -Y n-1 )×(XX n-1 ); Where: X is the current NOx concentration change rate; X n It is the value of the X-axis closest to the right of the current NOx concentration change rate; X n-1 It is the value of the X-axis closest to the left of the current NOx concentration change rate; Y n Corresponding to X n The value of the Y axis; Y n-1 Corresponding to X n-1 The value of the Y axis; (Y n -Y n-1 )÷(X n -Y n-1 ) is the slope of the broken line segment corresponding to the current NOx concentration change rate; XX n-1 The value where the rate of change of NOx concentration is higher than the nearest value on the left.

6. The logic algorithm according to any one of claims 1 to 5, characterized in that: The automatic parameter switching logic specifically includes: In the calculation of the optimal ammonia demand, when the inlet NOx analyzer on one side of the denitrification sends a calibration signal, a fault signal or a maintenance signal and the oxygen parameter exceeds the set range, and the oxygen content of the inlet NOx analyzer on the other side of the denitrification is less than a certain value, the inlet flue gas NOx concentration data referenced in the calculation of the optimal ammonia demand on this side will be switched to the other side as its inlet flue gas NOx concentration data.

7. The logic algorithm according to any one of claims 1 to 6, characterized in that: The ammonia addition optimization logic includes increasing the amount of ammonia or forcibly fully opening the ammonia injection regulating valve according to the average value of NOx concentration at the boiler chimney inlet and the instantaneous value of NOx concentration at the boiler chimney inlet.

8. The logic algorithm according to claim 7, characterized in that: When the ammonia injection regulating valve is in automatic state, the amount of ammonia will be increased; when the ammonia injection regulating valve is in manual state, the ammonia injection regulating valve will be forced to be fully opened.

9. The logic algorithm according to any one of claims 1 to 8, characterized in that: The converted value of the NOx concentration at the outlet of the denitrification device is obtained by calculating the difference between the converted value of the NOx concentration at the inlet of the boiler chimney and the measured value through the F'(x) function to obtain a corresponding coefficient, which is multiplied by the NOx concentration at the outlet of the denitrification device.

10. The logic algorithm according to claim 9, characterized in that: The F'(x) function logic output coefficient = (Y' n-1 )+(Y' n -Y' n-1 )÷(X' n -Y' n-1 )×(X'-X' n-1 ); Where: X' is the current difference; X' n It is the value of the X' axis closest to the right of the current difference; X' n-1 It is the value of the X' axis nearest to the left of the current difference; Y' n Corresponding to X n The value of the Y' axis; Y' n-1 Corresponding to X n-1 The value of the Y' axis; (Y' n -Y' n-1 )÷(X' n -Y' n-1 ) is the slope of the broken line segment corresponding to the current difference; X'-X' n-1 is the value whose difference is higher than the nearest value to the left.

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