CN213686786U - Coal-fired unit platen superheater overtemperature 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 screen superheater by combining an actual measurement signal, combining the maximum value with an amplitude limiting module and a rate-increasing speed-limiting module and realizing that a predicted value participates in overtemperature control; on the other hand, the actually measured wall temperature signal of the platen superheater is also combined with the amplitude limiting module and the speed increasing and limiting module to realize that the actually measured value participates in the control scheme; through adjusting the equipment such as the combustion air baffle, the primary desuperheating water adjusting valve and the like, an overtemperature control system of the screen superheater of the coal-fired unit based on wall temperature prediction is formed, and the active overtemperature inhibition and adjustment of the wall temperature of the screen 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 platen superheater overtemperature 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 platen superheater overtemperature 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 performed due to temperature measurement deviation of the water wall, the risk of tube explosion is inevitably increased when the water wall is operated at an overtemperature for a long time, and in addition, the scale is easy to fall off and block and the accident of tube explosion of the superheater is very easy to occur due to the fact that attention is not paid to monitoring of the metal temperature of the high-temperature superheater in the domestic ultra (supercritical) direct current boiler. Therefore, the real-time measurement of the wall temperature and the advance prediction and control of the wall temperature are effective ways for reducing the risk of pipe explosion.

At present, the coal burner group mainly adopts the following two schemes for measuring and controlling the wall temperature:

1) wall temperature measurement is realized by installing a large number of thermocouple wall temperature measuring points at the metal parts of the tube walls of the boiler superheater, the reheater, the water wall and the like, and an independent monitoring system or a DCS (distributed control system) system is directly connected for direct monitoring, so that the safety and stability of long-term operation of the boiler are improved; 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, only the influence of external factors on the wall temperature is considered, and static network structures such as a BP neural network and the like are adopted to predict the wall temperature of a boiler tube. The current wall temperature historical data, the upstream wall temperature historical data and the change rate of related factors are not considered, the contents of a time sequence prediction neural network structure, a neural network activation function and the like are not researched, the prediction structure is relatively backward, and the calculation result is relatively poor; and at present, the wall temperature prediction only stays in a display stage, and a prediction result is 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 platen superheater overtemperature control system based on wall temperature prediction obtains the trend of change of predicting wall temperature and current wall temperature simultaneously to accomplish wall temperature overtemperature control and operation and guide, realize leading wall temperature overtemperature initiative suppression, to the operational reliability who improves thermal power plant, effectively reduce the pipe explosion risk, extension key equipment life reduces and maintains cost of maintenance and all has important meaning.

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

the overtemperature control system of the screen type superheater of the coal-fired unit based on wall temperature prediction is characterized in that boiler feed water is divided into a left path and a right path after passing through a low-temperature superheater 1 for heat exchange, the left path is connected with a left screen type superheater 7 through a left first-stage desuperheating water regulating valve 3 and a left first-stage desuperheating water flow sensor 4, and the right path is connected with a right screen type superheater 9 through a right first-stage desuperheating water regulating valve 5 and a right first-stage desuperheating water flow; a plurality of low-temperature superheater wall temperature sensors 2 are arranged on the low-temperature superheater 1, a plurality of left-side platen superheater wall temperature sensors 8 are arranged on the left-side platen superheater 7, and a plurality of right-side platen superheater wall temperature sensors 10 are arranged on the right-side platen superheater 9; the corresponding sides of the left platen superheater 7 and the right platen superheater 9 are respectively provided with a left burning after-combustion air baffle plate 11 and a right burning after-combustion air baffle plate 12; the right side over-wall temperature sensor 10 is connected with the input end of a right side over-wall temperature maximum value calculation and storage module 13 and the input end of a right side over-wall temperature average value calculation and storage module 14, the low temperature superheater wall temperature sensor 2 is connected with the input end of a low temperature superheater wall temperature average value calculation and storage module 15, and the right side first-stage desuperheating water flow sensor 6 is connected with the input end of a right side first-stage desuperheating water flow differential calculation and storage module 16; similarly, the left screen type superheater wall temperature sensor 8 is connected with the input end of the left screen wall temperature maximum value calculation storage module 17 and the input end of the left screen wall temperature average value calculation storage module 18, and the left first-stage desuperheating water flow sensor 4 is connected with the input end of the left first-stage desuperheating water flow differential calculation storage module 19.

The output ends of the right-side screen wall-passing temperature maximum value calculation storage module 13, the right-side screen wall-passing temperature average value calculation storage module 14, the low-temperature superheater wall-temperature average value calculation storage module 15, the right-side primary desuperheating water flow differential calculation storage module 16 and the unit load data storage module 20 are connected with the input end of a right-side screen wall-passing temperature prediction model calculation module 21, the output end of the right-side screen wall-passing temperature prediction model calculation module 21 is respectively connected with the input end of a right-side screen wall-passing temperature prediction amplitude limiting module 23 and the input end of a right-side screen wall-passing temperature prediction temperature rise rate speed limiting module 24, and the output end of the right-side screen wall-passing temperature prediction amplitude limiting module 23 and the output end of the right-side screen wall-passing temperature prediction temperature rise rate speed limiting; the wall temperature sensor 10 of the right screen type superheater is respectively connected with the input end of a current value amplitude limiting module 26 of the right screen wall temperature and the input end of a current value temperature rise rate speed limiting module 27 of the right screen wall temperature, and the output end of the current value amplitude limiting module 26 of the right screen wall temperature and the output end of the current value temperature rise rate speed limiting module 27 of the right screen wall temperature are connected with the input end of a second or module 28 on the right side; the output end of the right first or module 25 and the output end of the right second or module 28 are connected with the input end of the right desuperheating water/overfire air control instruction offset module 35 to generate a control instruction, and the output end of the right desuperheating water/overfire air control instruction offset module 35 is connected with and controls the right first-stage desuperheating water regulating valve 5 and the right overfire air baffle 12; similarly, the output ends of the left screen wall-passing temperature maximum value calculation storage module 17, the left screen wall-passing temperature average value calculation storage module 18, the low-temperature superheater wall-temperature average value calculation storage module 15, the left first-stage desuperheating water flow differential calculation storage module 19 and the unit load data storage module 20 are connected with the input end of the left screen wall-passing temperature prediction model calculation module 22; the output end of the left screen over-wall temperature prediction model calculation module 22 is respectively connected with the input end of a left screen over-wall temperature prediction amplitude limiting module 29 and the input end of a left screen over-wall temperature prediction temperature rise rate speed limiting module 30, and the input end of the left screen over-wall temperature prediction amplitude limiting module 29 and the output end of the left screen over-wall temperature prediction temperature rise rate speed limiting module 30 are connected with a first left OR module 31; the wall temperature sensor 8 of the left screen type superheater is respectively connected with the input end of a current value amplitude limiting module 32 of the left screen wall temperature and the input end of a current value temperature rise rate speed limiting module 33 of the left screen wall temperature, and the output end of the current value amplitude limiting module 32 of the left screen wall temperature and the output end of the current value temperature rise rate speed limiting module 33 of the left screen wall temperature are connected with a second or module 34 on the left side; the output end of the first or module 31 on the left side and the output end of the second or module 34 on the left side are connected with the input end of the left side temperature-reducing water/over fire air control instruction offset module 36 to generate a control instruction, and the output end of the left side temperature-reducing water/over fire air control instruction offset module 36 is connected with and controls the left side first-stage temperature-reducing water regulating valve 3 and the left side over fire air baffle plate 11; the average value of the wall-passing temperature of the right side screen is calculated and stored in the module 14, and the average value of the wall-passing temperature of the left side screen is calculated and stored in the module 18, and the module 37 is connected with the over-fire air control command offset module 37, so that an over-fire air control offset command is generated to control the left over-fire air baffle plate 11 and the right over-fire air baffle plate 12.

The control method of the overtemperature control system of the screen type superheater of the coal-fired unit based on wall temperature prediction comprises the following steps:

sending a plurality of screen type wall temperature real-time data acquired by a right screen type superheater wall temperature sensor 10 into a right side screen excess wall temperature maximum value calculation and storage module 13 to calculate and obtain a right side screen excess wall temperature maximum value and store historical data, and simultaneously obtaining a right side screen excess wall temperature average value through a right side screen excess wall temperature average value calculation and storage module 14 and storing the historical data; sending the wall temperature measured by the low-temperature superheater wall temperature sensor 2 into a low-temperature superheater wall temperature average value calculation and storage module 15 for calculation to obtain a real-time low-temperature superheater wall temperature average value and storing historical data, wherein the desuperheating water flow data measured by the right first-stage desuperheating water flow sensor 6 is calculated by a right first-stage desuperheating water flow differential calculation and storage module 16 to obtain a right first-stage desuperheating water change rate; similarly, the wall temperature measured by the left screen type superheater wall temperature sensor 8 is sent to the left screen wall passing temperature maximum value calculation and storage module 17 to calculate the left screen wall passing temperature maximum value and store historical data, and the left screen wall passing temperature average value calculation and storage module 18 calculates the left screen wall passing temperature average value and stores the historical data; the desuperheating water flow value measured by the left first-stage desuperheating water flow sensor 4 is sent to a left first-stage desuperheating water flow differential calculation storage module 19 to calculate and obtain the change rate of the left desuperheating water; then the calculated maximum value of the wall temperature of the right side screen, the average value of the wall temperature of the low-temperature superheater, the variation rate of the first-level desuperheating water of the right side screen and the unit load are sent to a right side screen wall temperature prediction model calculation module 21 to be calculated to obtain a predicted value of the wall temperature of the maximum value of the right side screen, the predicted value is sent to a right side screen wall temperature prediction amplitude limiting module 23 and a right side screen wall temperature prediction temperature rise rate speed limiting module 24 to judge whether the wall temperature of the right side screen exceeds the limit, the first or the module 25 on the right side judges that any one of the wall temperature exceeds the limit, namely, an overtemperature signal is sent to the right side desuperheating water/overtemperature control instruction offset module 35 to generate an ember air offset instruction to control the opening of the right side ember air baffle 12, so that the overtemperature of the right side screen is reduced by increasing the ember air in advance Judging, namely sending an overtemperature signal to a right desuperheating water/burnout air control instruction offset module 35 to generate an ember air offset instruction and a desuperheating water regulating valve opening offset instruction by judging that any one of the overtemperature signals exceeds the limit through a right second or module 28, so that real-time control of the right first-stage desuperheating water regulating valve 5 and the right burnout air baffle 12 is realized, and overtemperature of the screen wall is avoided;

similarly, the calculated maximum value of the left-side screen wall-passing temperature, the calculated average value of the low-temperature superheater wall temperature, the calculated change rate of the left-side first-level desuperheating water and the unit load are sent to a left-side screen wall-passing temperature prediction model calculation module 22 to be calculated to obtain a predicted value of the left-side screen wall-passing maximum value wall temperature, the predicted value is sent to a left-side screen wall-passing temperature prediction amplitude limiting module 29 and a left-side screen wall-passing temperature prediction speed and temperature limit module 30 to judge whether the temperature exceeds the limit, the first left-side or module 31 judges that any one of the temperature exceeds the limit, namely, sends an overtemperature signal to a left-side desuperheating water/overfire air control instruction offset module 36 to generate an ember air; on the other hand, the left side wall temperature actually measured by the left side screen type superheater wall temperature sensor 8 is sent into a left side screen over-wall temperature current value amplitude limiting module 32 and a left side screen over-wall temperature current value temperature rise rate speed limiting module 33 for judgment, and a left side second OR module 34 judges that any one of the over-limits is over-limit, namely, sends an over-temperature signal to a left side desuperheating water/burnout air control instruction offset module 36 to generate a burnout air offset instruction and a desuperheating water regulating door opening offset instruction, so that the real-time control of the left side primary desuperheating water regulating valve 3 and the left side burnout air baffle 11 is realized, and the overtemperature of the screen;

and finally, sending the left and right side screen wall-crossing temperature average values calculated by the right side screen wall-crossing temperature average value calculation storage module 14 and the left side screen wall-crossing temperature average value calculation storage module 18 into the burnout air control instruction offset module 37 for judgment, when the wall temperature deviation of the two sides is greater than a protection set value, generating a burnout air control offset instruction to control the left burnout air baffle plate 11 and the right burnout air baffle plate 12, opening the burnout air baffle plate on the side with higher wall temperature, and reducing the burnout air baffle plate on the side with lower temperature, so as to reduce the wall temperature deviation of the two sides.

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 excess temperature closed-loop control through wall temperature prediction and wall temperature control, effectively reduces the screen and crosses wall temperature excess temperature risk.

(2) Because flue gas in the flue flows unevenly, the wall temperature difference of the left and right platen superheaters is easy to generate, so that the overtemperature risk is caused on one side, and at present, no better control method is available except for combustion adjustment. The utility model discloses when judging the great risk of wall temperature difference about appearing, with the help of the regulating action of upper strata burn out wind baffle in the short time, realized the purpose that supplementary adjustment flue gas flows, reduce the risk of overtemperature, further richened the automatic control function who burns out wind baffle.

(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, real data are used for adjusting desuperheating water and burning air in real time to complete control, two-stage protection is guaranteed, overtemperature automatic protection of the screen superheater is achieved, and the method has important significance for solving the problem that the screen overtemperature and overtemperature of the coal burner unit face.

Drawings

Fig. 1 is the utility model discloses coal-fired unit platen superheater overtemperature control system schematic diagram based on wall temperature prediction.

The reference numbers and corresponding component names in the figures are illustrated as follows: 1 Low-temperature superheater

2 low-temperature superheater wall temperature sensor

3 left side first-stage desuperheating water regulating valve

4 left side one-level temperature-reducing water flow sensor

5 right first-stage desuperheating water regulating valve

6 right side first-stage desuperheating water flow sensor

7 left side platen superheater

8 left side platen superheater wall temperature sensor

9 right side platen superheater

Wall temperature sensor of 10 right side platen superheater

11 left side burn-out air baffle

12 right side burn-out air baffle

13 maximum value calculation and storage module for wall temperature of right side screen

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

15 average wall temperature calculation and storage module of low-temperature superheater

16 one-level differential calculation and storage module for temperature reduction water flow on right side

17 maximum value calculation and storage module for wall temperature of left screen

18 left screen wall temperature average value calculation storage module

19 left-side first-stage desuperheating water flow differential calculation storage module

20 unit load data storage module

21 right side screen wall temperature prediction model calculation module

22 left side screen wall temperature prediction model calculation module

23 right side screen wall temperature-passing prediction amplitude limiting module

24 temperature rise rate speed-limiting module for predicting wall temperature of right side screen

25 right first or module

26 current value amplitude limiting module for wall temperature passing of right side screen

27 current temperature rise rate speed limiting module of wall temperature is crossed to right side screen

28 right second or module

29 left side screen wall temperature prediction amplitude limiting module

30 left side screen crosses wall temperature prediction temperature rise rate speed limit module

31 left first or module

32 left screen wall temperature-passing current value amplitude limiting module

33 current value temperature rise rate speed limit module of left side screen wall temperature

34 left second or module

35 right side desuperheating water/over fire air control instruction offset module

36 left side desuperheating water/over fire air control instruction offset module

The over-fire air control command biasing module is 37.

Detailed Description

As shown in figure 1, the utility model discloses coal-fired unit platen superheater overtemperature control system based on wall temperature prediction, boiler feed water divide into two tunnel about after low-temperature superheater 1 heat transfer, the left side is passed through left side one-level desuperheating water governing valve 3 and left side one-level desuperheating water flow sensor 4 and is connected with left side platen superheater 7, the right side is passed through right side one-level desuperheating water governing valve 5 and right side one-level desuperheating water flow sensor 6 and is connected with right side platen superheater 9; a plurality of low-temperature superheater wall temperature sensors 2 are arranged on the low-temperature superheater 1, a plurality of left-side platen superheater wall temperature sensors 8 are arranged on the left-side platen superheater 7, and a plurality of right-side platen superheater wall temperature sensors 10 are arranged on the right-side platen superheater 9; the corresponding sides of the left platen superheater 7 and the right platen superheater 9 are respectively provided with a left burning after-combustion air baffle plate 11 and a right burning after-combustion air baffle plate 12; the wall temperature sensor 10 of the right platen superheater is connected with the input end of a maximum wall temperature calculation and storage module 13 of the right platen superheater and the input end 14 of a mean wall temperature calculation and storage module of the right platen superheater, the wall temperature sensor 2 of the low temperature superheater is connected with the input end of a mean wall temperature calculation and storage module 15 of the low temperature superheater, and the first-stage desuperheating water flow sensor 6 on the right side is connected with the input end of a differential calculation and storage module 16 of the first-stage desuperheating water flow on the right side; similarly, the left screen type superheater wall temperature sensor 8 is connected with the input end of the left screen wall temperature maximum value calculation storage module 17 and the input end of the left screen wall temperature average value calculation storage module 18, and the left first-stage desuperheating water flow sensor 4 is connected with the input end of the left first-stage desuperheating water flow differential calculation storage module 19. The output ends of the right-side screen wall-passing temperature maximum value calculation storage module 13, the right-side screen wall-passing temperature average value calculation storage module 14, the low-temperature superheater wall-temperature average value calculation storage module 15, the right-side primary desuperheating water flow differential calculation storage module 16 and the unit load data storage module 20 are connected with the input end of a right-side screen wall-passing temperature prediction model calculation module 21, the output end of the right-side screen wall-passing temperature prediction model calculation module 21 is respectively connected with the input end of a right-side screen wall-passing temperature prediction amplitude limiting module 23 and the input end of a right-side screen wall-passing temperature prediction temperature rise rate speed limiting module 24, and the output end of the right-side screen wall-passing temperature prediction amplitude limiting module 23 and the output end of the right-side screen wall-passing temperature prediction temperature rise rate speed; the wall temperature sensor 10 of the right screen type superheater is respectively connected with the input end of a current value amplitude limiting module 26 of the right screen wall temperature and the input end of a current value temperature rise rate speed limiting module 27 of the right screen wall temperature, and the output end of the current value amplitude limiting module 26 of the right screen wall temperature and the output end of the current value temperature rise rate speed limiting module 27 of the right screen wall temperature are connected with the input end of a second or module 28 on the right side; the output end of the right first or module 25 and the output end of the right second or module 28 are connected with the input end of the right desuperheating water/overfire air control instruction offset module 35 to generate a control instruction, and the output end of the right desuperheating water/overfire air control instruction offset module 35 is connected with and controls the right first-stage desuperheating water regulating valve 5 and the right overfire air baffle 12; similarly, the output ends of the left screen wall-passing temperature maximum value calculation storage module 17, the left screen wall-passing temperature average value calculation storage module 18, the low-temperature superheater wall-temperature average value calculation storage module 15, the left first-stage desuperheating water flow differential calculation storage module 19 and the unit load data storage module 20 are connected with the input end of the left screen wall-passing temperature prediction model calculation module 22; the output end of the left screen over-wall temperature prediction model calculation module 22 is respectively connected with the input end of a left screen over-wall temperature prediction amplitude limiting module 29 and the input end of a left screen over-wall temperature prediction temperature rise rate speed limiting module 30, and the input end of the left screen over-wall temperature prediction amplitude limiting module 29 and the output end of the left screen over-wall temperature prediction temperature rise rate speed limiting module 30 are connected with a first left OR module 31; the wall temperature sensor 8 of the left screen type superheater is respectively connected with the input end of a current value amplitude limiting module 32 of the left screen wall temperature and the input end of a current value temperature rise rate speed limiting module 33 of the left screen wall temperature, and the output end of the current value amplitude limiting module 32 of the left screen wall temperature and the output end of the current value temperature rise rate speed limiting module 33 of the left screen wall temperature are connected with a second or module 34 on the left side; the output end of the first or module 31 on the left side and the output end of the second or module 34 on the left side are connected with the input end of the left side temperature-reducing water/over fire air control instruction offset module 36 to generate a control instruction, and the output end of the left side temperature-reducing water/over fire air control instruction offset module 36 is connected with and controls the left side first-stage temperature-reducing water regulating valve 3 and the left side over fire air baffle plate 11; the average value of the wall-passing temperature of the right side screen is calculated and stored in the module 14, and the average value of the wall-passing temperature of the left side screen is calculated and stored in the module 18, and the module 37 is connected with the over-fire air control command offset module 37, so that an over-fire air control offset command is generated to control the left over-fire air baffle plate 11 and the right over-fire air baffle plate 12.

As shown in figure 1, the utility model discloses coal-fired unit platen superheater overtemperature control system's based on wall temperature prediction control method does:

sending a plurality of screen type wall temperature real-time data acquired by a right screen type superheater wall temperature sensor 10 into a right side screen excess wall temperature maximum value calculation and storage module 13 to calculate and obtain a right side screen excess wall temperature maximum value and store historical data, and simultaneously obtaining a right side screen excess wall temperature average value through a right side screen excess wall temperature average value calculation and storage module 14 and storing the historical data; sending the wall temperature measured by the low-temperature superheater wall temperature sensor 2 into a low-temperature superheater wall temperature average value calculation and storage module 15 for calculation to obtain a real-time low-temperature superheater wall temperature average value and storing historical data, wherein the desuperheating water flow data measured by the right first-stage desuperheating water flow sensor 6 is calculated by a right first-stage desuperheating water flow differential calculation and storage module 16 to obtain a right first-stage desuperheating water change rate; similarly, the wall temperature measured by the left screen type superheater wall temperature sensor 8 is sent to the left screen wall passing temperature maximum value calculation and storage module 17 to calculate the left screen wall passing temperature maximum value and store historical data, and the left screen wall passing temperature average value calculation and storage module 18 calculates the left screen wall passing temperature average value and stores the historical data; the desuperheating water flow value measured by the left first-stage desuperheating water flow sensor 4 is sent to a left first-stage desuperheating water flow differential calculation storage module 19 to calculate and obtain the change rate of the left desuperheating water; then the calculated maximum value of the wall temperature of the right side screen, the average value of the wall temperature of the low-temperature superheater, the variation rate of the first-level desuperheating water of the right side screen and the unit load are sent to a right side screen wall temperature prediction model calculation module 21 to be calculated to obtain a predicted value of the wall temperature of the maximum value of the right side screen, the predicted value is sent to a right side screen wall temperature prediction amplitude limiting module 23 and a right side screen wall temperature prediction temperature rise rate speed limiting module 24 to judge whether the wall temperature of the right side screen exceeds the limit, the first or the module 25 on the right side judges that any one of the wall temperature exceeds the limit, namely, an overtemperature signal is sent to the right side desuperheating water/overtemperature control instruction offset module 35 to generate an ember air offset instruction to control the opening of the right side ember air baffle 12, so that the overtemperature of the right side screen is reduced by increasing the ember air in advance Judging, namely sending an overtemperature signal to a right desuperheating water/burnout air control instruction offset module 35 to generate an ember air offset instruction and a desuperheating water regulating valve opening offset instruction by judging that any one of the overlimits is exceeded through a right second or module 28, so that real-time control of the right first-stage desuperheating water regulating valve 5 and the right burnout air baffle 12 is realized, and overtemperature of the screen wall is avoided;

similarly, the calculated maximum value of the left-side screen wall-passing temperature, the calculated average value of the low-temperature superheater wall temperature, the calculated change rate of the left-side first-level desuperheating water and the unit load are sent to a left-side screen wall-passing temperature prediction model calculation module 22 to be calculated to obtain a predicted value of the left-side screen wall-passing maximum value wall temperature, the predicted value is sent to a left-side screen wall-passing temperature prediction amplitude limiting module 29 and a left-side screen wall-passing temperature prediction speed and temperature limit module 30 to judge whether the temperature exceeds the limit, the first left-side or module 31 judges that any one of the temperature exceeds the limit, namely, sends an overtemperature signal to a left-side desuperheating water/overfire air control instruction offset module 36 to generate an ember air; on the other hand, the left side wall temperature actually measured by the left side screen type superheater wall temperature sensor 8 is sent into a left side screen over-wall temperature current value amplitude limiting module 32 and a left side screen over-wall temperature current value temperature rise rate speed limiting module 33 for judgment, and a left side second OR module 34 judges that any one of the over-limits is over-limit, namely, sends an over-temperature signal to a left side desuperheating water/burnout air control instruction offset module 36 to generate a burnout air offset instruction and a desuperheating water regulating door opening offset instruction, so that the real-time control of the left side primary desuperheating water regulating valve 3 and the left side burnout air baffle 11 is realized, and the overtemperature of the screen;

and finally, sending the left and right side screen wall-crossing temperature average values calculated by the right side screen wall-crossing temperature average value calculation storage module 14 and the left side screen wall-crossing temperature average value calculation storage module 18 into the burnout air control instruction offset module 37 for judgment, when the wall temperature deviation of the two sides is greater than a protection set value, generating a burnout air control offset instruction to control the left burnout air baffle plate 11 and the right burnout air baffle plate 12, opening the burnout air baffle plate on the side with higher wall temperature, and reducing the burnout air baffle plate on the side with lower temperature, so as to reduce the wall temperature deviation of the two sides.

Claims (3)

1. Coal-fired unit platen superheater overtemperature control system based on wall temperature prediction is characterized in that: boiler feed water is divided into a left path and a right path after passing through a low-temperature superheater (1) for heat exchange, the left side of the boiler feed water is connected with a left screen superheater (7) through a left first-stage desuperheating water regulating valve (3) and a left first-stage desuperheating water flow sensor (4), and the right side of the boiler feed water is connected with a right screen superheater (9) through a right first-stage desuperheating water regulating valve (5) and a right first-stage desuperheating water flow sensor (6); a plurality of low-temperature superheater wall temperature sensors (2) are arranged on the low-temperature superheater (1), a plurality of left-side platen superheater wall temperature sensors (8) are arranged on the left-side platen superheater (7), and a plurality of right-side platen superheater wall temperature sensors (10) are arranged on the right-side platen superheater (9); the corresponding sides of the left platen superheater (7) and the right platen superheater (9) are respectively provided with a left burning after-combustion air baffle plate (11) and a right burning after-combustion air baffle plate (12); the wall temperature sensor (10) of the right screen type superheater is connected with the input end of a maximum wall temperature calculation and storage module (13) of the right screen type superheater and the input end of a mean wall temperature calculation and storage module (14) of the right screen type superheater, the wall temperature sensor (2) of the low-temperature superheater is connected with the input end of a mean wall temperature calculation and storage module (15) of the low-temperature superheater, and the first-stage desuperheating water flow sensor (6) of the right side is connected with the input end of a differential desuperheating water flow calculation and storage module (16) of the first-stage desuperheating; similarly, the left screen type superheater wall temperature sensor (8) is connected with the input end of a left screen wall passing temperature maximum value calculation storage module (17) and the input end of a left screen wall passing temperature average value calculation storage module (18), and the left first-stage desuperheating water flow sensor (4) is connected with the input end of a left first-stage desuperheating water flow differential calculation storage module (19);

the output ends of a right-side screen wall-passing temperature maximum value calculation storage module (13), a right-side screen wall-passing temperature average value calculation storage module (14), a low-temperature superheater wall-temperature average value calculation storage module (15), a right-side primary desuperheating water flow differential calculation storage module (16) and a unit load data storage module (20) are connected with the input end of a right-side screen wall-passing temperature prediction model calculation module (21), the output end of the right-side screen wall-passing temperature prediction model calculation module (21) is respectively connected with the input end of a right-side screen wall-passing temperature prediction amplitude limiting module (23) and the input end of a right-side screen wall-passing temperature prediction temperature rise speed limit module (24), and the output end of the right-side screen wall-passing temperature prediction amplitude limiting module (23) and the output end of the right-side screen wall-passing temperature prediction temperature rise speed limit module (24) are; the wall temperature sensor (10) of the right screen type superheater is respectively connected with the input end of a current value amplitude limiting module (26) of the wall temperature of the right screen and the input end of a current temperature rise rate speed limiting module (27) of the wall temperature of the right screen, and the output end of the current value amplitude limiting module (26) of the wall temperature of the right screen and the output end of the current temperature rise rate speed limiting module (27) of the wall temperature of the right screen are connected with the input end of a second OR module (28) on the right side; the output end of the right first OR module (25) and the output end of the right second OR module (28) are connected with the input end of the right desuperheating water/over-fire air control instruction offset module (35) to generate a control instruction, and the output end of the right desuperheating water/over-fire air control instruction offset module (35) is connected with and controls the right first-stage desuperheating water regulating valve (5) and the right over-fire air baffle plate (12); similarly, the output ends of a left screen wall-passing temperature maximum value calculation and storage module (17), a left screen wall-passing temperature average value calculation and storage module (18), a low-temperature superheater wall temperature average value calculation and storage module (15), a left first-stage desuperheating water flow differential calculation and storage module (19) and a unit load data storage module (20) are connected with the input end of a left screen wall-passing temperature prediction model calculation module (22); the output end of the left screen over-wall temperature prediction model calculation module (22) is respectively connected with the input end of a left screen over-wall temperature prediction amplitude limiting module (29) and the input end of a left screen over-wall temperature prediction temperature rise rate speed limiting module (30), and the input end of the left screen over-wall temperature prediction amplitude limiting module (29) and the output end of the left screen over-wall temperature prediction temperature rise rate speed limiting module (30) are connected with a first or module (31) on the left side; a left screen type superheater wall temperature sensor (8) is respectively connected with the input end of a left screen over-wall temperature current value amplitude limiting module (32) and the input end of a left screen over-wall temperature current value temperature rise rate speed limiting module (33), and the output end of the left screen over-wall temperature current value amplitude limiting module (32) and the output end of the left screen over-wall temperature current value temperature rise rate speed limiting module (33) are connected with a left second OR module (34); the output end of the first left OR module (31) and the output end of the second left OR module (34) are connected with the input end of a left desuperheating water/over-fire air control instruction offset module (36) to generate a control instruction, and the output end of the left desuperheating water/over-fire air control instruction offset module (36) is connected with and controls a left first-stage desuperheating water regulating valve (3) and a left burn-out air baffle plate (11); the average value of the wall-crossing temperature of the right side screen is calculated and stored by the module (14) and the average value of the wall-crossing temperature of the left side screen is calculated and stored by the module (18) and is connected with the over-fire air control instruction offset module (37), so that an over-fire air control offset instruction is generated to control the left over-fire air baffle plate (11) and the right over-fire air baffle plate (12).

2. The coal-fired unit platen superheater overtemperature control system based on wall temperature prediction of claim 1, wherein: the overtemperature control system of the screen type superheater of the coal-fired unit based on the wall temperature prediction comprises a right screen overtemperature prediction model calculation module (21) and a left screen overtemperature prediction model calculation module (22), and judges whether the overtemperature control system is in overrun alarm or not by combining the predicted temperature through a right screen overtemperature prediction amplitude limiting module (23), a right screen overtemperature prediction temperature rise rate speed limiting module (24), a left screen overtemperature prediction amplitude limiting module (29) and a left screen overtemperature prediction temperature rise rate speed limiting module (30); and on the other hand, the device comprises a left screen type superheater wall temperature sensor (8) and a right screen type superheater wall temperature sensor (10), and judges whether the alarm is over-limit or not by combining the actually measured left and right side wall temperatures through a right screen over-wall temperature current value amplitude limiting module (26), a right screen over-wall temperature current value temperature rise rate speed limiting module (27), a left screen over-wall temperature current value amplitude limiting module (32) and a left screen over-wall temperature current value temperature rise rate speed limiting module (33).

3. The coal-fired unit platen superheater overtemperature control system based on wall temperature prediction of claim 1, wherein: the left burning-out air baffle (11) and the right burning-out air baffle (12) belong to a secondary air system of the boiler, are arranged around the boiler, and are respectively selected to be positioned on the corresponding sides of the left screen superheater (7) and the right screen superheater (9) to control the overtemperature problem of the screen superheaters and the problem of large wall temperature deviation caused by uneven flow of smoke on two sides.

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