CN213453601U - Coal-fired unit high temperature over-temperature control system based on wall temperature prediction - Google Patents

Abstract

The system is used for predicting the maximum value of the wall temperature of the high-temperature superheater by combining an actual measurement signal, combining the maximum value with an amplitude limiting module and a speed limiting module and realizing 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 utility model discloses obtain the trend of change of prediction wall temperature and current wall temperature simultaneously, realize leading wall temperature overtemperature initiative suppression, to the operational reliability who improves thermal power plant, effectively reduce the pipe explosion risk, prolong key equipment life, reduce and maintain cost of maintenance and all have important meaning.

Description

Coal-fired unit high temperature over-temperature control system based on wall temperature prediction

Technical Field

The utility model relates to a coal-fired unit's automatic control field, concretely relates to coal-fired unit high temperature over temperature control system 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 problem that above-mentioned prior art exists, the utility model provides a coal-fired unit high temperature over temperature control system based on wall temperature prediction to the operational reliability who improves thermal power plant, the super temperature problem of initiative suppression high temperature over heater effectively reduces the pipe explosion risk, prolongs key equipment life, and it all has important meaning to reduce the maintenance cost.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the boiler feed water heat exchange is divided into two paths to flow through a left-side platen superheater 1 and a right-side platen superheater 3 respectively, the left-side platen superheater 1 is connected with a left-side secondary desuperheating water regulating valve 5, the right-side platen superheater 3 is connected with a right-side secondary desuperheating water regulating valve 7, and then the left-side and right-side cross heat exchange is carried out and then the two paths of heat exchange are connected with a final superheater inlet header so as to be connected with a plurality of high-temperature superheaters 9; a plurality of left-side platen superheater wall temperature sensors 2 are arranged on the left-side platen superheater 1, a plurality of right-side platen superheater wall temperature sensors 4 are arranged on the right-side platen superheater 3, two high-temperature superheaters which are easy to overheat are selected from the plurality of high-temperature superheaters 9, and a first wall temperature sensor 10 of the high-temperature superheater which is easy to overheat and a second wall temperature sensor 11 of the high-temperature superheater which is easy to overheat are respectively arranged; a plurality of layers of secondary air doors are arranged around a boiler formed by the left screen type superheater 1, the right screen type 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 wall temperature sensor 4 of the right platen superheater is connected with the input end of a right platen superheater wall temperature average value calculation and storage module 16, the wall temperature sensor 2 of the left platen superheater is connected with the input end of a left platen superheater wall temperature average value calculation and storage module 17, the right secondary desuperheating water flow sensor 8 is connected with the input end of a right secondary desuperheating water flow differential calculation and storage module 18, the left secondary desuperheating water flow sensor 6 is connected with the input end of a left secondary desuperheating water flow differential calculation and storage module 19, the first wall temperature sensor 10 of the easily-overtemperature high-temperature superheater is connected with the input end of a first wall temperature maximum value calculation and storage module 21, and the second wall temperature sensor 11 of the easily-overtemperature high-temperature superheater is connected with the input end of a second wall temperature maximum value calculation and storage module 20;

the output ends of a right screen wall-passing temperature average value calculation and storage module 16, a left screen wall-passing temperature average value calculation and storage module 17, a right secondary desuperheating water flow differential calculation and storage module 18, a left secondary desuperheating water flow differential calculation and storage module 19, an easy overtemperature and high second wall temperature maximum value calculation and storage module 20, an easy overtemperature and high first 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 overtemperature prediction and calculation module 24, the output end of the high excess wall temperature prediction calculation module 24 is respectively connected with the input ends of a high excess wall temperature prediction maximum value amplitude limiting module 25 and a high excess wall temperature prediction maximum value speed limiting module 26, and the output ends of the high excess wall temperature prediction maximum value amplitude limiting module 25 and the high excess wall temperature prediction maximum value speed limiting 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 a current value amplitude limiting module 31 higher than the 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 platen superheater wall temperature sensor 4 is connected with the input ends of a right platen current value amplitude limiting module 34 and a right platen current value speed limiting module 35, and the output ends of the right platen current value amplitude limiting module 34 and the right platen current value speed limiting module 35 are connected with the input end of a fourth OR module 36; the left platen superheater wall temperature sensor 2 is connected with the input ends of a left platen current value amplitude limiting module 37 and a left platen current value speed limiting module 38, and the output ends of the left platen current value amplitude limiting module 37 and the left platen 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:

sending a plurality of screen wall temperature real-time data collected by a right screen superheater wall temperature sensor 4 into a right screen superheater wall temperature average value calculation storage module 16 to calculate and obtain a wall temperature average value and store historical data, sending a plurality of screen wall temperature real-time data collected by a left screen superheater wall temperature sensor 2 into a left screen superheater wall temperature average value calculation storage module 17 to calculate and obtain a wall temperature average value and store the historical data, sending right secondary desuperheating water flow measured by a right secondary desuperheating water flow sensor 8 into a right secondary desuperheating water flow differential calculation storage module 18 to calculate and obtain a flow change rate, sending left secondary desuperheating water flow measured by a left secondary desuperheating water flow sensor 6 into a left secondary desuperheating water flow differential calculation storage module 19 to calculate and obtain a flow change rate, sending a plurality of excess wall temperature real-time data collected by an easy overtemperature high temperature second wall temperature sensor 11 into an easy overtemperature and highest wall temperature 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 platen superheater wall temperature sensor 4 into a right platen current value amplitude limiting module 34 and a right platen 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 platen superheater wall temperature sensor 2 into a left platen current value amplitude limiting module 37 and a left platen current value speed limiting module 38 for judging whether the current actual signal exceeds the current value, 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 overtemperature phenomena of the high-temperature superheater and the platen superheater commonly occur, sending a command to a burn-out air baffle control command offset module 42 to generate a larger offset command signal, and controlling the opening adjustment of the larger burn-out air baffle to further move the flame center downwards so as to complete 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 utility model discloses the development of going on the basis of current wall temperature measurement station does not add wall temperature measurement station transformation, can realize wall temperature excess temperature prediction and overtemperature initiative restraint control through wall temperature prediction and wall temperature control, when guaranteeing that main steam temperature is stable, effectively reduces the high overtemperature risk of wall temperature that crosses. Specifically, the utility model discloses an aspect combines actual measurement signal to carry out the prediction of high temperature over heater wall temperature maximum value to combine it with limit amplitude module, speed limit module, 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 utility model discloses obtain the trend of change of prediction wall temperature and current wall temperature simultaneously, realize leading wall temperature overtemperature initiative suppression, to the operational reliability who improves thermal power plant, effectively reduce the pipe explosion risk, prolong key equipment life, reduce and maintain cost of maintenance and all have important meaning.

(2) The utility model discloses when the great risk of high excess wall temperature overtemperature appears in the prediction judgement, use the baffle aperture of small size with the help of the regulating action of upper burning ember wind baffle in the short time, reduce the flame height, the automatic control function of burning ember wind baffle has further been richened to the initiative suppression overtemperature risk. 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) The utility model discloses a wall temperature predicts in advance, and when the prediction overtemperature, through the effect of burning out the wind adjustment realize reducing wall temperature overtemperature in advance. 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 the utility model discloses coal-fired unit high temperature over temperature control system schematic diagram based on wall temperature prediction.

The reference numbers and corresponding component names in the figures are illustrated as follows:

1 left platen superheater

2 left side platen superheater wall temperature sensor

3 right side platen superheater

4 right side platen 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

16 average value of wall temperature is crossed to right side screen calculates storage module

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 over current value amplitude limiting module

35 current value speed limiting module is crossed to right side screen

36 fourth or module

37 left screen over current value amplitude limiting module

38 left screen current value speed limiting 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 figure 1, the utility model discloses coal-fired unit high temperature over-temperature control system based on wall temperature prediction, boiler feed water heat transfer divide two the tunnel to flow through left side platen superheater 1 and right side platen superheater 3 respectively, left side platen superheater 1 links to each other with left side second grade desuperheating water governing valve 5, right side platen superheater 3 links to each other with right side second grade desuperheating water governing valve 7, links to each other with last superheater entry collection case after the left and right cross heat transfer afterwards to link to each other with a plurality of high temperature over heaters 9; a plurality of left-side platen superheater wall temperature sensors 2 are arranged on the left-side platen superheater 1, a plurality of right-side platen superheater wall temperature sensors 4 are arranged on the right-side platen superheater 3, two high-temperature superheaters which are easy to overheat are selected from the plurality of high-temperature superheaters 9, and a first wall temperature sensor 10 of the high-temperature superheater which is easy to overheat and a second wall temperature sensor 11 of the high-temperature superheater which is easy to overheat are respectively arranged; the boiler that left side platen superheater 1, right side platen superheater 3 and a plurality of high temperature superheater 9 formed arranges 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.

The right screen type superheater wall temperature sensor 4 is connected with the input end of a right screen overtemperature average value calculation storage module 16, the left screen type superheater wall temperature sensor 2 is connected with the input end of a left screen overtemperature average value calculation storage module 17, the right secondary desuperheating water flow sensor 8 is connected with the input end of a right secondary desuperheating water flow differential calculation storage module 18, the left secondary desuperheating water flow sensor 6 is connected with the input end of a left secondary desuperheating water flow differential calculation storage module 19, the first wall temperature sensor 10 of the easy overtemperature high temperature superheater is connected with the input end of a first wall temperature maximum value calculation storage module 21, and the second wall temperature sensor 11 of the easy overtemperature high temperature superheater is connected with the input end of a second wall temperature maximum value calculation storage module 20.

The output ends of a right screen wall-passing temperature average value calculation and storage module 16, a left screen wall-passing temperature average value calculation and storage module 17, a right secondary desuperheating water flow differential calculation and storage module 18, a left secondary desuperheating water flow differential calculation and storage module 19, an easy overtemperature and high second wall temperature maximum value calculation and storage module 20, an easy overtemperature and high first 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 overtemperature prediction and calculation module 24, the output end of the high excess wall temperature prediction calculation module 24 is respectively connected with the input ends of a high excess wall temperature prediction maximum value amplitude limiting module 25 and a high excess wall temperature prediction maximum value speed limiting module 26, and the output ends of the high excess wall temperature prediction maximum value amplitude limiting module 25 and the high excess wall temperature prediction maximum value speed limiting 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 a current value amplitude limiting module 31 higher than the 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 platen superheater wall temperature sensor 4 is connected with the input ends of a right platen current value amplitude limiting module 34 and a right platen current value speed limiting module 35, and the output ends of the right platen current value amplitude limiting module 34 and the right platen current value speed limiting module 35 are connected with the input end of a fourth OR module 36; the left platen superheater wall temperature sensor 2 is connected with the input ends of a left platen current value amplitude limiting module 37 and a left platen current value speed limiting module 38, and the output ends of the left platen current value amplitude limiting module 37 and the left platen 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 figure 1, the utility model discloses coal-fired unit high temperature over temperature control system's based on wall temperature prediction control method does:

sending a plurality of screen wall temperature real-time data collected by a right screen superheater wall temperature sensor 4 into a right screen overtall temperature average value calculation and storage module 16 to calculate and obtain a wall temperature average value and store historical data, sending a plurality of screen wall temperature real-time data collected by a left screen superheater wall temperature sensor 2 into a left screen overtall temperature average value calculation and storage module 17 to calculate and obtain a wall temperature average value and store the historical data, sending a right secondary desuperheating water flow measured by a right secondary desuperheating water flow sensor 8 into a right secondary desuperheating water flow differential calculation and storage module 18 to calculate and obtain a flow change rate, sending a left secondary desuperheating water flow measured by a left secondary desuperheating water flow sensor 6 into a left secondary desuperheating water flow differential calculation and storage module 19 to calculate and obtain a flow change rate, sending a plurality of overtall temperature real-time data collected by a second overtall temperature sensor 11 into a highest overtemperature and highest wall temperature easy overtemperature sensor 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 platen superheater wall temperature sensor 4 into a right platen current value amplitude limiting module 34 and a right platen 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 platen superheater wall temperature sensor 2 into a left platen current value amplitude limiting module 37 and a left platen current value speed limiting module 38 for judging whether the current actual signal exceeds the current value, 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 overtemperature phenomena of the high-temperature superheater and the platen superheater commonly occur, sending a command to a burn-out air baffle control command offset module 42 to generate a larger offset command signal, and controlling the opening adjustment of the larger burn-out air baffle to further move the flame center downwards so as to complete 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 (3)

1. Coal-fired unit high temperature over temperature control system based on wall temperature prediction its characterized in that: 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 carried out 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); a plurality of left screen type superheater wall temperature sensors (2) are arranged on the left screen type superheater (1), a plurality of right screen type superheater wall temperature sensors (4) are arranged on the right screen type superheater (3), two high-temperature superheaters which are easy to overtemperature are selected from the plurality of high-temperature superheaters (9), and a first wall temperature sensor (10) of the high-temperature superheater which is easy to overtemperature and a second wall temperature sensor (11) of the high-temperature superheater which is easy to overtemperature are respectively arranged; a plurality of layers of secondary air doors are arranged around a boiler formed by the left screen type superheater (1), the right screen type 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 wall temperature sensor (4) of the right screen type superheater is connected with the input end of a right screen overtall temperature average value calculation storage module (16), the wall temperature sensor (2) of the left screen type superheater is connected with the input end of a left screen overtall temperature average value calculation storage module (17), the right secondary desuperheating water flow sensor (8) is connected with the input end of a right secondary desuperheating water flow differential calculation storage module (18), the left secondary desuperheating water flow sensor (6) is connected with the input end of a left secondary desuperheating water flow differential calculation storage module (19), the first wall temperature sensor (10) of the easily overtemperature high-temperature superheater is connected with the input end of a first wall temperature maximum value calculation storage module (21), and the second wall temperature sensor (11) of the easily overtemperature high-temperature superheater is connected with the input end of a second wall temperature maximum value calculation storage module (20);

the device comprises a right screen overtall temperature average value calculation storage module (16), a left screen overtall temperature average value calculation storage module (17), a right secondary desuperheating water flow differential calculation storage module (18), a left secondary desuperheating water flow differential calculation storage module (19), an easily overtemperature and second wall temperature maximum value calculation storage module (20), an easily overtemperature and first wall temperature maximum value calculation storage module (21), a main steam flow data storage module (22) and a unit load data storage module (23), wherein the output ends of the easily overtemperature and first wall temperature maximum value calculation storage module (21), the main steam flow data storage module (22) and the unit load data storage module (23) are connected with the input end of a high overtall temperature prediction calculation module (24), the output end of the high overtall temperature prediction calculation module (24) is respectively connected with the input ends of a high overtall temperature prediction maximum value amplitude limiting module (25) and a high overtall temperature prediction maximum value speed limiting module (26), and the output end of the high overtall temperature prediction maximum value speed limiting (ii) a 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 platen superheater wall temperature sensor (4) is connected with the input ends of a right platen current-passing value amplitude limiting module (34) and a right platen current-passing value speed limiting module (35), and the output ends of the right platen current-passing value amplitude limiting module (34) and the right platen current-passing value speed limiting module (35) are connected with the input end of a fourth OR module (36); the left platen superheater wall temperature sensor (2) is connected with the input ends of a left platen current-passing value amplitude limiting module (37) and a left platen current-passing value speed limiting module (38), and the output ends of the left platen current-passing value amplitude limiting module (37) and the left platen current-passing 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-easily-exceeding-first maximum wall temperature calculation and storage module (21) for predicting the maximum wall temperature of the high-temperature superheater, and a high-wall-temperature-exceeding-predicting-maximum-value amplitude limiting module (25) and a high-wall-temperature-exceeding-predicting-maximum-value speed limiting module (26) for judging whether to alarm for overtemperature exceeding or not by combining the predicted temperature; and on the other hand, the device comprises a left screen type superheater wall temperature sensor (2), a right screen type superheater wall temperature sensor (4), a first wall temperature sensor (10) of an easily overtemperature high-temperature superheater, and an actual wall temperature signal collected by a second wall temperature sensor (11) of the easily overtemperature high-temperature superheater, and respectively forms logic judgment with a current value amplitude limiting module (31) higher than the first wall temperature, a current value speed limiting module (32) higher than the first wall temperature, a current value amplitude limiting module (28) higher than the second wall temperature, a current value speed limiting module (29) higher than the second wall temperature, a current value amplitude limiting module (34) of a right screen, a current value speed limiting module (35) of a right screen, a current value amplitude limiting module (37) of a left screen and a current value limiting module (38) of.

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.

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