CN112097243A - Wall temperature prediction-based overtemperature control system and method for high-temperature superheater of coal-fired unit - Google Patents
Wall temperature prediction-based overtemperature control system and method for high-temperature superheater of coal-fired unit Download PDFInfo
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- CN112097243A CN112097243A CN202011100921.7A CN202011100921A CN112097243A CN 112097243 A CN112097243 A CN 112097243A CN 202011100921 A CN202011100921 A CN 202011100921A CN 112097243 A CN112097243 A CN 112097243A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/02—Applications of combustion-control devices, e.g. tangential-firing burners, tilting burners
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22G—SUPERHEATING OF STEAM
- F22G5/00—Controlling superheat temperature
- F22G5/20—Controlling superheat temperature by combined controlling procedures
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Abstract
The system is combined with an actual measurement signal to predict the maximum value of the wall temperature of the high-temperature superheater, and is combined with an amplitude limiting module and a speed limiting module to realize that a predicted value participates in the overtemperature control; on the other hand, the measured wall temperature signal of the high-temperature superheater is also combined with the amplitude limiting module and the speed limiting module to realize that the measured value participates in the control scheme; the opening degree of the combustion air baffle plates on the periphery of the boiler is adjusted, the flame center of the boiler is reduced, the overtemperature risk of the high-temperature superheater is reduced, and the overtemperature active inhibition and adjustment of the wall temperature of the high-temperature superheater are realized; the method and the device simultaneously obtain the predicted wall temperature and the current wall temperature variation trend, realize the advanced wall temperature overtemperature active inhibition, and have important significance for improving the operation reliability of the thermal power plant, effectively reducing the risk of pipe explosion, prolonging the service life of key equipment and reducing the maintenance cost.
Description
Technical Field
The invention relates to the field of automatic control of coal-fired units, in particular to a system and a method for controlling the overtemperature of a high-temperature superheater of a coal-fired unit based on wall temperature prediction.
Background
With the continuous improvement of the grade of the thermal power generating unit, the improvement of power generation parameters such as steam temperature, pressure and the like is an important way for improving the efficiency of the ultra-supercritical unit, but the steam temperature rise puts higher requirements on steam pipeline materials and wall temperature control. The method is limited by the restriction of creep strength and endurance strength of materials, temperature fluctuation must be within a safety margin, parameter adjustment cannot be timely carried out due to wall temperature measurement deviation of a heated surface, the risk of tube explosion is inevitably increased when the heated surface is operated at an overtemperature for a long time, and in addition, the existing domestic supercritical (super) direct current boiler is easy to generate scale shedding and blocking and is easy to generate tube explosion accidents of the heated surface due to insufficient attention on monitoring of the metal temperature of the heated surface. Therefore, the method is an effective way for reducing the risk of tube explosion for real-time measurement of the wall temperature of the heating surface and advanced prediction and control of the wall temperature.
At present, the measurement schemes of the coal-fired unit for the wall temperature of the heating surface mainly comprise the following two schemes:
1) the wall temperature measurement is realized by installing a large number of thermocouples at the metal parts of the tube walls of the positions of a boiler superheater, a reheater, a water-cooled wall and the like, and the safety and the stability of the long-term operation of the boiler are improved by directly monitoring by using an independent monitoring system or directly accessing a DCS (distributed control system); at present, the method has higher requirements on the environment around a measuring point, but the environment in a furnace is often severe, and has certain influence on the measuring precision and accuracy; meanwhile, the method can only measure the temperature value at the current moment, and only when the measuring points are over-temperature due to more measuring points, an alarm can be given out, so that the operating personnel can correspondingly adjust the boiler parameters according to actual experience. Therefore, operators can not judge a large number of wall temperature measuring points in real time in the process of monitoring the wall temperature overtemperature, and can not solve the overtemperature problem in time when overtemperature alarming is carried out, and adverse influence is brought to the operation safety of the boiler.
2) And establishing a wall temperature prediction model by a mechanism or mathematical analysis method, thereby realizing the calculation and prediction of the wall temperature. The method is complex, has more boundary parameters, can not give all boundary parameters for actual measuring points of the power plant, and needs to be continuously corrected under different conditions of the model, so that the method does not meet the requirement of on-line calculation and can not participate in closed-loop control of the wall temperature of the power plant in real time; based on a mathematical modeling analysis method, a wall temperature prediction method based on an artificial neural network is mostly adopted at present, the boiler tube wall temperature can be predicted by static network structures such as a BP neural network, but the wall temperature prediction only stays in a research stage and a display alarm stage at present, and prediction results are not used to participate in thermal power closed-loop control.
In summary, the existing wall temperature overtemperature countermeasures and prediction means only stop displaying alarm, so that the parameters are changed by means of the experience of operators, and closed-loop control is not realized. On the other hand, the wall temperature prediction model needs to be optimized, so that accurate prediction of the wall temperature is realized, and advanced closed-loop operation is realized to avoid overtemperature of the wall temperature.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a system and a method for controlling the overtemperature of the high-temperature superheater of the coal-fired unit based on wall temperature prediction, which have important significance for improving the operation reliability of a thermal power plant, actively inhibiting the overtemperature problem of the high-temperature superheater, effectively reducing the risk of pipe explosion, prolonging the service life of key equipment and reducing the maintenance and repair cost.
In order to achieve the purpose, the invention adopts the following technical scheme:
the boiler feed water heat exchange is divided into two paths to flow through a left screen superheater 1 and a right screen superheater 3 respectively, the left screen superheater 1 is connected with a left second-stage desuperheating water regulating valve 5, the right screen superheater 3 is connected with a right second-stage desuperheating water regulating valve 7, and then the left and right cross heat exchange is connected with a final superheater inlet header so as to be connected with a plurality of high temperature superheaters 9; the screen type superheater comprises a left screen type superheater 1, a right screen type superheater 3, a plurality of high temperature superheater 9, a plurality of screen type superheater wall temperature sensors 2, a plurality of screen type superheater wall temperature sensors 4, a plurality of temperature superheater devices 10, a plurality of temperature superheater devices 11, a plurality of temperature superheater devices; a plurality of layers of secondary air doors are arranged around a boiler formed by the left screen superheater 1, the right screen superheater 3 and the high-temperature superheaters 9, wherein the upper layer of secondary air doors comprise a first burn-out air baffle 12, a second burn-out air baffle 13, a third burn-out air baffle 14 and a fourth burn-out air baffle 15;
the screen on the right side is connected with the input end of the wall temperature average calculation storage module 16, the screen on the left side is connected with the input end of the wall temperature average calculation storage module 17, the screen on the right side is connected with the input end of the second-stage desuperheating water flow differential calculation storage module 18, the screen on the left side is connected with the input end of the second-stage desuperheating water flow differential calculation storage module 19, the first input end of the second-stage desuperheating water temperature sensor 10 is connected with the input end of the first-stage desuperheating water temperature storage module 19, and the input end of the second-temperature super;
the output ends of the high overtemperature and high overtemperature prediction calculation module 24 are respectively connected with the input ends of a high overtemperature prediction maximum value amplitude limiting module 25 and a high overtemperature prediction maximum value speed limit module 26, and the output ends of the high overtemperature prediction maximum value amplitude limiting module 25 and the high overtemperature prediction maximum value speed limit module 26 are connected with the input end of a first or module 27; the second wall temperature sensor 11 of the easily overtemperature high-temperature superheater is connected with the input ends of an amplitude limiting module 28 higher than the current value of the second wall temperature and a speed limiting module 29 higher than the current value of the second wall temperature, and the output ends of the amplitude limiting module 28 higher than the current value of the second wall temperature and the speed limiting module 29 higher than the current value of the second wall temperature are connected with the input end of a second OR module 30; the first wall temperature sensor 10 of the easily overtemperature high-temperature superheater is connected with the input ends of an amplitude limiting module 31 higher than the current value of the first wall temperature and a speed limiting module 32 higher than the current value of the first wall temperature, and the output ends of the amplitude limiting module 31 higher than the current value of the first wall temperature and the speed limiting module 32 higher than the current value of the first wall temperature are connected with the input end of a third OR module 33; the right screen type superheater wall temperature sensor 4 is connected with the input ends of a right screen current value amplitude limiting module 34 and a right screen current value speed limiting module 35, and the output ends of the right screen current value amplitude limiting module 34 and the right screen current value speed limiting module 35 are connected with the input end of a fourth or module 36; the left screen type superheater wall temperature sensor 2 is connected with the input ends of a left screen current value amplitude limiting module 37 and a left screen current value speed limiting module 38, and the output ends of the left screen current value amplitude limiting module 37 and the left screen current value speed limiting module 38 are connected with the input end of a fifth or module 39; the output ends of the first or module 27, the second or module 30 and the third or module 33 are connected with the input end of the sixth or module 40, and the output ends of the second or module 30, the third or module 33, the fourth or module 36 and the fifth or module 39 are connected with the input end of the condition judgment module 41; the output ends of the sixth or module 40 and the condition judgment module 41 are connected to the input end of the burn-out air baffle control instruction bias module 42, the output end of the burn-out air baffle control instruction bias module 42 is connected to the first burn-out air baffle 12, the second burn-out air baffle 13, the third burn-out air baffle 14 and the fourth burn-out air baffle 15, and the burn-out air baffle control instruction bias module 42 generates a bias control instruction to control the first burn-out air baffle 12, the second burn-out air baffle 13, the third burn-out air baffle 14 and the fourth burn-out air baffle 15.
The control method of the overtemperature control system of the high-temperature superheater of the coal-fired unit based on wall temperature prediction comprises the following steps:
with the multiple screen formula wall temperature real-time data of right side screen formula over heater wall temperature sensor 4 collection send into right side screen and cross wall temperature average and calculate storage module 16 and calculate the acquisition wall temperature average and store historical data, with left side screen formula over heater wall temperature sensor 2 collection a plurality of screen formula wall temperature real-time data send into with left side screen and cross wall temperature average calculate storage module 17 and calculate acquisition wall temperature average and calculate that the acquisition wall temperature average is calculated to the second side and carry out the second grade of temperature reduction module and calculate that the rate of flow of the second grade of temperature is measured to the second grade of temperature reduction heat flow sensor and send into the second grade of temperature reduction heat flow sensor 8 data that the rate of the second grade of temperature reduction heat flow is measured to the second grade of temperature reduction heat flow sensor and the second grade of temperature reduction heat flow sensor right side is calculated to the second grade of temperature flow rate of the second grade of temperature reduction heat flow sensor and is measured and is sent into the second grade of temperature flow rate The large value calculation and storage module 20 obtains the maximum value of the wall temperature and stores historical data, and a plurality of real-time data of the high overtemperature high-temperature superheater, which are acquired by the first wall temperature sensor 10, are sent to the maximum value calculation and storage module 21 for the high overtemperature high-temperature superheater and the first wall temperature to obtain the maximum value of the wall temperature and store the historical data; then, the average value of the over-wall temperature of the right side screen, the average value of the over-wall temperature of the left side screen, the change rate of the secondary amount of the reduced temperature water on the right side, the change rate of the secondary amount of the reduced temperature water on the left side, the high over-temperature-prone maximum value, the main steam flow stored in the main steam flow data storage module 22 and the load historical data of the unit load data storage module 23 are sent to a high over-wall temperature prediction calculation module 24 to be predicted to obtain a high over-wall temperature prediction maximum value, then whether the over-wall temperature is exceeded or not is judged through a high over-wall temperature prediction maximum value amplitude limiting module 25 and a high over-wall temperature prediction speed limiting maximum value module; similarly, the current actual value measured by the second wall temperature sensor 11 of the high-temperature superheater easy to overtemperature is sent to a second wall temperature current value amplitude limiting module 28 and a second wall temperature current value speed limiting module 29 to judge whether the current value exceeds the second wall temperature current value, and then the current value is sent to a second OR module 30 to carry out logic judgment; sending the current actual value measured by the first wall temperature sensor 10 of the high-temperature superheater easy to overtemperature into a first wall temperature current value amplitude limiting module 31 and a first wall temperature current value speed limiting module 32 for judging whether the current value exceeds the first wall temperature current value, and then sending the current value into a third OR module 33 for logic judgment; sending a current actual signal measured by the right screen type superheater wall temperature sensor 4 into a right screen current value amplitude limiting module 34 and a right screen current value speed limiting module 35 for judging whether the current actual signal exceeds the current value, and then sending the current actual signal into a fourth OR module 36 for logical judgment; sending the current actual signal measured by the left screen type superheater wall temperature sensor 2 into a left screen current value amplitude limiting module 37 and a left screen current value speed limiting module 38 for judging whether the current actual signal exceeds the current value amplitude limiting module, and then sending the current actual signal into a fifth OR module 39 for logical judgment; then sending signals of the first or module 27, the second or module 30 and the third or module 33 into a sixth or module 40 for judgment, if any one of the signals meets the condition, sending an instruction into an ember air baffle control instruction offset module 42, outputting a small offset instruction, adjusting the opening degree of the ember air baffles on the periphery of the upper layer of the boiler to be small and large, enabling the flame to move downwards, and preventing the wall temperature of the high-temperature superheater from being over-temperature; sending signals of the second or module 30, the third or module 33, the fourth or module 36 and the fifth or module 39 to a condition judgment module 41 for logic judgment, if prediction control does not prevent the continuous overtemperature of the high-temperature superheater from exceeding a certain upper limit or the overtemperature phenomenon of the high-temperature superheater and a screen superheater generally occurs, sending an instruction to an ember air baffle control instruction offset module 42 to generate a larger offset instruction signal, controlling the opening adjustment of the larger ember air baffle to further move the flame center downwards, and completing the overtemperature control of the high-temperature superheater; besides the completion of active inhibition control, the system also sends out an alarm signal to operators in advance, operation time is reserved, the operators are assisted to adjust a fuel link, a secondary air door and a water supply link, and in order to prevent pipe explosion of a high-temperature superheater, a coal quantity instruction is properly reduced, a water-coal ratio and a flame center are adjusted, and wall temperature control is further realized.
Compared with the prior art, the invention has the following advantages:
(1) in the prior art, a large number of thermocouple wall temperature measuring points are only arranged at the metal parts of the tube walls of the positions of a boiler superheater, a reheater, a water wall and the like to realize wall temperature measurement, and an independent monitoring system or a DCS (distributed control system) directly connected for direct monitoring is utilized; the method can only measure the temperature value at the current moment, and only when the over-temperature phenomenon occurs at the measuring point, the alarm can be sent out, and the over-temperature part and the over-temperature condition can not be quickly judged due to more measuring points. On the other hand, the wall temperature overtemperature monitoring process cannot judge a large number of wall temperature measuring points in real time by operators, and when overtemperature alarm occurs, control operation processing is carried out, so that the overtemperature problem cannot be solved in time, and adverse influence is brought to the operation safety of the boiler. The invention is developed on the basis of the existing wall temperature measuring point, the wall temperature measuring point is not improved, the wall temperature overtemperature prediction and the overtemperature active inhibition control can be realized through the wall temperature prediction and the wall temperature control, and the high overtemperature risk of the wall temperature is effectively reduced while the stability of the main steam temperature is ensured. On one hand, the method carries out prediction on the maximum value of the wall temperature of the high-temperature superheater by combining with an actual measurement signal, and combines the maximum value with an amplitude limiting module and a speed limiting module to realize that the predicted value participates in overtemperature control; on the other hand, the measured wall temperature signal of the high-temperature superheater is also combined with the amplitude limiting module and the speed limiting module to realize that the measured value participates in the control scheme; the opening degree of the combustion air baffle plates on the periphery of the boiler is adjusted, the flame center of the boiler is reduced, the overtemperature risk of the high-temperature superheater is reduced, and the overtemperature active inhibition and adjustment of the wall temperature of the high-temperature superheater are realized; the method and the device simultaneously obtain the predicted wall temperature and the current wall temperature variation trend, realize the advanced wall temperature overtemperature active inhibition, and have important significance for improving the operation reliability of the thermal power plant, effectively reducing the risk of pipe explosion, prolonging the service life of key equipment and reducing the maintenance cost.
(2) When the invention predicts and judges that the risk of high wall-over temperature and high overtemperature is large, the invention uses the small opening degree of the baffle plate to reduce the flame height by means of the regulating action of the upper-layer burn-out air baffle plate in a short time, actively inhibits the overtemperature risk and further enriches the automatic control function of the burn-out air baffle plate. When the overtemperature risk appears in the pipe panel that is too high at most, open upper burner wind baffle aperture greatly, further suppress the flame height, reduce the overtemperature risk, predict the warning in advance simultaneously, give the operating personnel operating time.
(3) According to the invention, the wall temperature is predicted in advance, and when the overtemperature is predicted, the overtemperature of the wall is reduced in advance through the over-fire air regulation effect. Meanwhile, according to actual temperature measurement data, real-time alarm overtemperature prevention control is carried out, control is completed by adjusting burning-out air in real time through real data, two-stage protection is guaranteed, overtemperature active suppression protection of the high-temperature superheater is achieved, and the method has important significance for solving the problem that the wall temperature of the high-temperature superheater faces the coal burner unit.
Drawings
FIG. 1 is a schematic diagram of a high-temperature superheater overtemperature control system of a coal-fired unit based on wall temperature prediction.
The reference numbers and corresponding component names in the figures are illustrated as follows:
1 left screen type superheater
2 left screen type superheater wall temperature sensor
3 right screen type over heater
4 right side screen type superheater wall temperature sensor
5 left two-stage desuperheating water regulating valve
6 left side two-stage desuperheating water flow sensor
7 right-side two-stage desuperheating water regulating valve
8 right side two-stage desuperheating water flow sensor
9 high-temperature superheater
First wall temperature sensor of 10 easy overtemperature high temperature superheater
Second wall temperature sensor of 11 easy-overtemperature high-temperature superheater
12 first burnout wind baffle
13 second ember wind baffle
14 third ember wind baffle
15 fourth burn-out air baffle
Average value calculation storage module for wall temperature of screen on right side of 16
17 average value of wall temperature is crossed to left side screen calculates storage module
18 right-side two-stage desuperheating water flow differential calculation storage module
19 left-side two-stage desuperheating water flow differential calculation storage module
Calculation and storage module for 20-degree-of-excess-temperature higher than second wall temperature maximum value
21 easy-to-overtemperature calculation and storage module higher than first wall temperature maximum value
22 main steam flow data storage module
23 unit load data storage module
24 high excess wall temperature prediction calculation module
25 high excess wall temperature prediction maximum value amplitude limiting module
26-high over-wall temperature prediction maximum value speed-limiting module
27 first or module
28 is higher than second wall temperature current value amplitude limiting module
29 is higher than current value speed limit module of second wall temperature
30 second or module
Amplitude limiting module for current value of 31 higher than first wall temperature
32 is higher than the current value speed-limiting module of the first wall temperature
33 third or module
34 right screen current value amplitude limiting module
35 right screen current value speed limit module
36 fourth or module
37 left screen current value amplitude limiting module
38 left screen current value speed limit module
39 fifth or module
40 sixth or Module
41 condition judging module
The overfire air damper control command offset module is 42.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, in the coal-fired unit high-temperature superheater overtemperature control system based on wall temperature prediction, boiler feed water heat exchange is divided into two paths to flow through a left screen superheater 1 and a right screen superheater 3 respectively, the left screen superheater 1 is connected with a left secondary desuperheating water regulating valve 5, the right screen superheater 3 is connected with a right secondary desuperheating water regulating valve 7, and then the left and right cross heat exchange is connected with a final superheater inlet header so as to be connected with a plurality of high-temperature superheaters 9; the screen type superheater comprises a left screen type superheater 1, a right screen type superheater 3, a plurality of high temperature superheater 9, a plurality of screen type superheater wall temperature sensors 2, a plurality of screen type superheater wall temperature sensors 4, a plurality of temperature superheater devices 10, a plurality of temperature superheater devices 11, a plurality of temperature superheater devices; left side screen formula over heater 1, right side screen formula over heater 3 and the boiler that a plurality of high temperature over heater 9 formed arrange the multilayer secondary air door all around, and wherein upper strata secondary air door contains first burn out air baffle 12, second burn out air baffle 13, third burn out air baffle 14 and fourth burn out air baffle 15.
Right side screen formula over heater wall temperature sensor 4 is connected with the input that wall temperature average calculated storage module 16 was shielded on the right side, left side screen formula over heater wall temperature sensor 2 is connected with the input that wall temperature average calculated storage module 17 was shielded on the left side, right side second grade desuperheating water flow sensor 8 is connected with the input that storage module 18 was calculated to right side second grade desuperheating water flow differential, storage module 19 was calculated to left side second grade desuperheating water flow differential, the first input of temperature block of temperature-exceeding is connected with the first high temperature of temperature-exceeding module of the second grade of temperature-exceeding module 10, the first input of temperature-exceeding module of temperature-exceeding is connected with the first high temperature of the second grade temperature-exceeding module, the first input of temperature-exceeding.
The output ends of the high overtemperature and high overtemperature prediction calculation module 24 are respectively connected with the input ends of a high overtemperature prediction maximum value amplitude limiting module 25 and a high overtemperature prediction maximum value speed limit module 26, and the output ends of the high overtemperature prediction maximum value amplitude limiting module 25 and the high overtemperature prediction maximum value speed limit module 26 are connected with the input end of a first or module 27; the second wall temperature sensor 11 of the easily overtemperature high-temperature superheater is connected with the input ends of an amplitude limiting module 28 higher than the current value of the second wall temperature and a speed limiting module 29 higher than the current value of the second wall temperature, and the output ends of the amplitude limiting module 28 higher than the current value of the second wall temperature and the speed limiting module 29 higher than the current value of the second wall temperature are connected with the input end of a second OR module 30; the first wall temperature sensor 10 of the easily overtemperature high-temperature superheater is connected with the input ends of an amplitude limiting module 31 higher than the current value of the first wall temperature and a speed limiting module 32 higher than the current value of the first wall temperature, and the output ends of the amplitude limiting module 31 higher than the current value of the first wall temperature and the speed limiting module 32 higher than the current value of the first wall temperature are connected with the input end of a third OR module 33; the right screen type superheater wall temperature sensor 4 is connected with the input ends of a right screen current value amplitude limiting module 34 and a right screen current value speed limiting module 35, and the output ends of the right screen current value amplitude limiting module 34 and the right screen current value speed limiting module 35 are connected with the input end of a fourth or module 36; the left screen type superheater wall temperature sensor 2 is connected with the input ends of a left screen current value amplitude limiting module 37 and a left screen current value speed limiting module 38, and the output ends of the left screen current value amplitude limiting module 37 and the left screen current value speed limiting module 38 are connected with the input end of a fifth or module 39; the output ends of the first or module 27, the second or module 30 and the third or module 33 are connected with the input end of the sixth or module 40, and the output ends of the second or module 30, the third or module 33, the fourth or module 36 and the fifth or module 39 are connected with the input end of the condition judgment module 41; the output ends of the sixth or module 40 and the condition judgment module 41 are connected to the input end of the burn-out air baffle control instruction bias module 42, the output end of the burn-out air baffle control instruction bias module 42 is connected to the first burn-out air baffle 12, the second burn-out air baffle 13, the third burn-out air baffle 14 and the fourth burn-out air baffle 15, and the burn-out air baffle control instruction bias module 42 generates a bias control instruction to control the first burn-out air baffle 12, the second burn-out air baffle 13, the third burn-out air baffle 14 and the fourth burn-out air baffle 15.
As shown in fig. 1, the control method of the overtemperature control system of the high-temperature superheater of the coal-fired unit based on wall temperature prediction of the invention comprises the following steps:
with the multiple screen formula wall temperature real-time data of right side screen formula over heater wall temperature sensor 4 collection send into right side screen and cross wall temperature average and calculate storage module 16 and calculate the acquisition wall temperature average and store historical data, with left side screen formula over heater wall temperature sensor 2 collection a plurality of screen formula wall temperature real-time data send into with left side screen and cross wall temperature average calculate storage module 17 and calculate acquisition wall temperature average and calculate that the acquisition wall temperature average is calculated to the second side and carry out the second grade of temperature reduction module and calculate that the rate of flow of the second grade of temperature is measured to the second grade of temperature reduction heat flow sensor and send into the second grade of temperature reduction heat flow sensor 8 data that the rate of the second grade of temperature reduction heat flow is measured to the second grade of temperature reduction heat flow sensor and the second grade of temperature reduction heat flow sensor right side is calculated to the second grade of temperature flow rate of the second grade of temperature reduction heat flow sensor and is measured and is sent into the second grade of temperature flow rate The large value calculation and storage module 20 obtains the maximum value of the wall temperature and stores historical data, and a plurality of real-time data of the high overtemperature high-temperature superheater, which are acquired by the first wall temperature sensor 10, are sent to the maximum value calculation and storage module 21 for the high overtemperature high-temperature superheater and the first wall temperature to obtain the maximum value of the wall temperature and store the historical data; then, the average value of the over-wall temperature of the right side screen, the average value of the over-wall temperature of the left side screen, the change rate of the secondary amount of the reduced temperature water on the right side, the change rate of the secondary amount of the reduced temperature water on the left side, the high over-temperature-prone maximum value, the main steam flow stored in the main steam flow data storage module 22 and the load historical data of the unit load data storage module 23 are sent to a high over-wall temperature prediction calculation module 24 to be predicted to obtain a high over-wall temperature prediction maximum value, then whether the over-wall temperature is exceeded or not is judged through a high over-wall temperature prediction maximum value amplitude limiting module 25 and a high over-wall temperature prediction speed limiting maximum value module; similarly, the current actual value measured by the second wall temperature sensor 11 of the high-temperature superheater easy to overtemperature is sent to a second wall temperature current value amplitude limiting module 28 and a second wall temperature current value speed limiting module 29 to judge whether the current value exceeds the second wall temperature current value, and then the current value is sent to a second OR module 30 to carry out logic judgment; sending the current actual value measured by the first wall temperature sensor 10 of the high-temperature superheater easy to overtemperature into a first wall temperature current value amplitude limiting module 31 and a first wall temperature current value speed limiting module 32 for judging whether the current value exceeds the first wall temperature current value, and then sending the current value into a third OR module 33 for logic judgment; sending a current actual signal measured by the right screen type superheater wall temperature sensor 4 into a right screen current value amplitude limiting module 34 and a right screen current value speed limiting module 35 for judging whether the current actual signal exceeds the current value, and then sending the current actual signal into a fourth OR module 36 for logical judgment; sending the current actual signal measured by the left screen type superheater wall temperature sensor 2 into a left screen current value amplitude limiting module 37 and a left screen current value speed limiting module 38 for judging whether the current actual signal exceeds the current value amplitude limiting module, and then sending the current actual signal into a fifth OR module 39 for logical judgment; then sending signals of the first or module 27, the second or module 30 and the third or module 33 into a sixth or module 40 for judgment, if any one of the signals meets the condition, sending an instruction into an ember air baffle control instruction offset module 42, outputting a small offset instruction, adjusting the opening degree of the ember air baffles on the periphery of the upper layer of the boiler to be small and large, enabling the flame to move downwards, and preventing the wall temperature of the high-temperature superheater from being over-temperature; sending signals of the second or module 30, the third or module 33, the fourth or module 36 and the fifth or module 39 to a condition judgment module 41 for logic judgment, if prediction control does not prevent the continuous overtemperature of the high-temperature superheater from exceeding a certain upper limit or the overtemperature phenomenon of the high-temperature superheater and a screen superheater generally occurs, sending an instruction to an ember air baffle control instruction offset module 42 to generate a larger offset instruction signal, controlling the opening adjustment of the larger ember air baffle to further move the flame center downwards, and completing the overtemperature control of the high-temperature superheater; besides the completion of active inhibition control, the system also sends out an alarm signal to operators in advance, operation time is reserved, the operators are assisted to adjust a fuel link, a secondary air door and a water supply link, and in order to prevent pipe explosion of a high-temperature superheater, a coal quantity instruction is properly reduced, a water-coal ratio and a flame center are adjusted, and wall temperature control is further realized.
Claims (4)
1. Coal-fired unit high temperature over temperature control system based on wall temperature prediction its characterized in that: the boiler feed water heat exchange is divided into two paths which respectively flow through a left screen type superheater (1) and a right screen type superheater (3), the left screen type superheater (1) is connected with a left second-stage desuperheating water regulating valve (5), the right screen type superheater (3) is connected with a right second-stage desuperheating water regulating valve (7), and then the left and right cross heat exchange is connected with a final superheater inlet header so as to be connected with a plurality of high-temperature superheaters (9); the screen comprises a left screen superheater (1), a plurality of left screen superheater wall temperature sensors (2), a right screen superheater (3), two high-temperature superheaters easy to overtemperature, a first wall temperature sensor (10) of the high-temperature superheater easy to overtemperature, and a second wall temperature sensor (11) of the high-temperature superheater easy to overtemperature, wherein the left screen superheater (1) is provided with the plurality of left screen superheater wall temperature sensors (4); a plurality of layers of secondary air doors are arranged around a boiler formed by the left screen superheater (1), the right screen superheater (3) and the high-temperature superheaters (9), wherein the upper secondary air doors comprise a first burn-out air baffle (12), a second burn-out air baffle (13), a third burn-out air baffle (14) and a fourth burn-out air baffle (15);
the screen on the right side is passed wall temperature sensor (4) and is passed the input that wall temperature average calculated storage module (16) with the screen on the right side and be connected, left side screen is passed wall temperature sensor (2) and is passed wall temperature average calculated storage module's (17) input with the screen on the left side and be connected, right side second grade desuperheating water flow sensor (8) and right side second grade desuperheating water flow differential calculated storage module's (18) input are connected, second grade desuperheating water flow sensor (6) on the left side is connected the input of second grade desuperheating water flow differential calculated storage module (10) and the input of second grade desuperheating water flow differential calculated storage module (21), the second grade desuperheating water flow differential calculated storage module's on the left side is connected the input of second grade desuperheating water temperature sensor (10), the second grade desuperheating water flow differential calculated storage module's on the input is connected with the high temperature of first grade desu;
the output ends of a right screen wall-crossing temperature average value calculation and storage module (16), a left screen wall-crossing temperature average value calculation and storage module (17), a right secondary desuperheating water quantity storage module (18), a left secondary desuperheating water quantity storage module (19), an easy overtemperature and first wall temperature maximum value calculation and storage module (20), an easy overtemperature and second wall temperature maximum value calculation and storage module (21), a main steam flow data storage module (22) and a unit load data storage module (23) are connected with the input end of a high wall-crossing temperature prediction and calculation module (24), the output end of the high over-wall temperature prediction calculation module (24) is respectively connected with the input ends of a high over-wall temperature prediction maximum value amplitude limiting module (25) and a high over-wall temperature prediction maximum value speed limiting module (26), the output ends of the high over-wall temperature prediction maximum value amplitude limiting module (25) and the high over-wall temperature prediction maximum value speed limiting module (26) are connected with the input end of the first OR module (27); a second wall temperature sensor (11) of the easily overtemperature high-temperature superheater is connected with the input ends of a current value amplitude limiting module (28) higher than the second wall temperature and a current value speed limiting module (29) higher than the second wall temperature, and the output ends of the current value amplitude limiting module (28) higher than the second wall temperature and the current value speed limiting module (29) higher than the second wall temperature are connected with the input end of a second OR module (30); a first wall temperature sensor (10) of the easily overtemperature high-temperature superheater is connected with the input ends of a current value amplitude limiting module (31) higher than a first wall temperature and a current value speed limiting module (32) higher than the first wall temperature, and the output ends of the current value amplitude limiting module (31) higher than the first wall temperature and the current value speed limiting module (32) higher than the first wall temperature are connected with the input end of a third OR module (33); the right screen type superheater wall temperature sensor (4) is connected with the input ends of a right screen current-value amplitude limiting module (34) and a right screen current-value speed limiting module (35), and the output ends of the right screen current-value amplitude limiting module (34) and the right screen current-value speed limiting module (35) are connected with the input end of a fourth OR module (36); the left screen type superheater wall temperature sensor (2) is connected with the input ends of a left screen current value amplitude limiting module (37) and a left screen current value speed limiting module (38), and the output ends of the left screen current value amplitude limiting module (37) and the left screen current value speed limiting module (38) are connected with the input end of a fifth OR module (39); the output ends of the first OR module (27), the second OR module (30) and the third OR module (33) are connected with the input end of the sixth OR module (40), and the output ends of the second OR module (30), the third OR module (33), the fourth OR module (36) and the fifth OR module (39) are connected with the input end of the condition judgment module (41); the output ends of the sixth OR module (40) and the condition judgment module (41) are connected with the input end of the burn-out air baffle control instruction biasing module (42), the output end of the burn-out air baffle control instruction biasing module (42) is connected with the first burn-out air baffle (12), the second burn-out air baffle (13), the third burn-out air baffle (14) and the fourth burn-out air baffle (15), and the burn-out air baffle control instruction biasing module (42) generates a bias control instruction to control the first burn-out air baffle (12), the second burn-out air baffle (13), the third burn-out air baffle (14) and the fourth burn-out air baffle (15).
2. The coal-fired unit high-temperature superheater overtemperature control system based on wall temperature prediction of claim 1, characterized in that: the overtemperature control system of the high-temperature superheater of the coal-fired unit based on the wall temperature prediction comprises a high-temperature-exceeding-degree calculation storage module (21) for predicting the wall temperature prediction maximum value of the high-temperature superheater, and a high-wall-temperature-exceeding-degree prediction maximum value limit module (25) and a high-wall-temperature-exceeding-degree prediction maximum value speed limit module (26) for judging whether to alarm the overtemperature; on the other hand, the screen wall temperature sensor (2) on the left side, the screen wall temperature sensor (4) on the right side, the first wall temperature sensor (10) of the high temperature superheater easy to exceed, the actual wall temperature signal collected by the second wall temperature sensor (11) of the high temperature superheater easy to exceed, respectively form the first wall temperature current value amplitude limiting module (31), the first wall temperature current value speed limit module (32) of the high-exceeding, the second wall temperature current value amplitude limiting module (34) of the high-exceeding screen, the second wall temperature current value amplitude limiting module (35) of the high-exceeding screen, the second wall temperature current value amplitude limiting module (38) of the high-exceeding screen, the second wall temperature current value amplitude limiting module (35) of the high-exceeding screen, the second wall temperature current value amplitude limiting module of the left side, the second wall temperature limiting module (34.
3. The coal-fired unit high-temperature superheater overtemperature control system based on wall temperature prediction of claim 1, characterized in that: the first burnout air baffle (12), the second burnout air baffle (13), the third burnout air baffle (14) and the fourth burnout air baffle (15) belong to a secondary air system of the boiler.
4. The control method of the overtemperature control system of the high-temperature superheater of the coal-fired unit based on the wall temperature prediction as recited in any one of claims 1 to 3, characterized by comprising the following steps:
the method comprises the steps of sending real-time data of the screen wall temperatures collected by a right screen type superheater wall temperature sensor (4) into a right screen type superheater wall temperature average value calculation storage module (16) to calculate and obtain a wall temperature average value and store historical data, sending the real-time data of the screen wall temperatures collected by a left screen type superheater wall temperature sensor (2) into a left screen type superheater wall temperature average value calculation storage module (17) to calculate and store the wall temperature average value, sending the acquired wall temperature average value to a right screen type superheater wall temperature differential value calculation storage module (18) to obtain a wall temperature differential value, sending the obtained wall temperature differential value to a left screen type superheater wall temperature differential value calculation storage module (17) to obtain a wall temperature differential value, sending the obtained wall temperature differential value to a right screen type superheater wall temperature differential value calculation storage module (8) to obtain a second-grade superheater wall temperature flow rate calculation module (8) to obtain a second-grade superheater wall temperature flow, the method comprises the steps that a plurality of real-time data of the high overtemperature and high temperature of the wall, which are acquired by a second wall temperature sensor (11) of the high overtemperature and high temperature of the wall, are sent to a maximum calculation and storage module (20) of the high overtemperature and high temperature of the wall to acquire the maximum value of the wall temperature and store historical data, and a plurality of real-time data of the high overtemperature and high temperature of the wall, which are acquired by a first wall temperature sensor (10) of the high overtemperature and high temperature of the wall, are sent to a maximum calculation and storage module (21) of the high overtemperature and high; then sending the average value of the over-wall temperature of the right side screen, the average value of the over-wall temperature of the left side screen, the change rate of the secondary amount of the reduced temperature water on the right side, the change rate of the secondary amount of the reduced temperature water on the left side, the high over-temperature-prone maximum value, the main steam flow stored by the main steam flow data storage module (22) and the load historical data of the unit load data storage module (23) into a high over-wall temperature prediction calculation module (24) for prediction to obtain a high over-wall temperature prediction maximum value, then judging whether the over-limit is caused by a high over-wall temperature prediction maximum value amplitude limiting module (25) and a high over-wall temperature prediction maximum value speed limiting module (26), and then sending the over-limit to; similarly, the current actual value measured by a second wall temperature sensor (11) of the high-temperature superheater easy to overtemperature is sent to a limiting module (28) higher than the current value of the second wall temperature and a speed-limiting module (29) higher than the current value of the second wall temperature for judging whether the current value exceeds the limit, and then the current value is sent to a second OR module (30) for logic judgment; sending a current actual numerical value measured by a first wall temperature sensor (10) of the easily overtemperature high-temperature superheater into a first wall temperature current value amplitude limiting module (31) and a first wall temperature current value speed limiting module (32) for judging whether the actual numerical value exceeds the first wall temperature current value, and then sending the actual numerical value into a third OR module (33) for logic judgment; sending a current actual signal measured by a right screen type superheater wall temperature sensor (4) into a right screen current-passing value amplitude limiting module (34) and a right screen current-passing value speed limiting module (35) for judging whether the current actual signal exceeds the limit, and then sending the current actual signal into a fourth OR module (36) for logical judgment; sending the current actual signal measured by the left screen type superheater wall temperature sensor (2) into a left screen current value amplitude limiting module (37) and a left screen current value speed limiting module (38) for judging whether the current actual signal exceeds the limit, then sending the current actual signal into a fifth OR module (39) for logic judgment, then sending signals of the first OR module (27), the second OR module (30) and the third OR module (33) into a sixth or module (40) for logic judgment, sending signals of a fifth or module (33) into a burnout baffle small-amplitude opening degree judgment module (41) for logic judgment, sending signals of a fifth or module (33) for judging whether the surrounding burnout baffle large-amplitude opening degree or a high-temperature baffle small-amplitude opening degree meets the requirements, sending signals of a fifth or module (33) into a burnout baffle small-amplitude opening degree judgment module (40) for logic judgment, sending signals of a high-temperature baffle large-amplitude instruction or a high-temperature baffle plate (36) into a condition judgment module (41) for logic judgment, sending, if the prediction control does not prevent the continuous overtemperature of the high-temperature superheater from exceeding a certain upper limit or the overtemperature phenomenon of the high-temperature superheater and the screen superheater generally occurs, sending an instruction to a burn-out air baffle control instruction offset module (42) to generate a larger offset instruction signal, and controlling the opening adjustment of the larger burn-out air baffle to further move the flame center downwards so as to complete the overtemperature control of the high-temperature superheater; besides the completion of active inhibition control, the system also sends out an alarm signal to operators in advance, operation time is reserved, the operators are assisted to adjust a fuel link, a secondary air door and a water supply link, and in order to prevent pipe explosion of a high-temperature superheater, reduce a coal quantity instruction, adjust a water-coal ratio and a flame center, wall temperature control is further realized.
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