CN112097244A - Wall temperature prediction-based screen type superheater overtemperature control system and method for coal-fired unit - Google Patents

Abstract

A system and method for over-temperature control of a flood-type superheater in a coal-fired unit based on wall temperature prediction. On the one hand, the system combines the actual measurement signal to predict the maximum value of the wall temperature of the flood-type superheater, and compares it with the limiting module, the rate of increase and the speed limit. The combination of modules realizes the predicted value participating in the over-temperature control; on the other hand, the actual measured wall temperature signal of the flood-type superheater is also combined with the amplitude limiting module and the rate-limiting module to realize the participation of the measured value in the control scheme; by adjusting the burner wind baffle , a first-stage desuperheating water regulating valve and other equipment, thus forming a coal-fired unit over-temperature control system for the superheater of the coal-fired unit based on the prediction of the wall temperature, and realizing the active suppression and adjustment of the wall temperature of the screen superheater; the present invention obtains the predicted wall temperature at the same time. It is of great significance to improve the operational reliability of thermal power plants, effectively reduce the risk of pipe burst, prolong the life of key equipment, and reduce maintenance and repair costs.

Description

System and method for over-temperature control of flood-type superheater in coal-fired units based on prediction of wall temperature

technical field

The invention relates to the field of automatic control of coal-fired units, in particular to a system and method for over-temperature control of a flood-type superheater of a coal-fired unit based on wall temperature prediction.

Background technique

With the continuous improvement of the level of thermal power units, improving steam temperature, pressure and other power generation parameters is an important way to improve the efficiency of ultra-supercritical units, but the increase in steam temperature puts forward higher requirements for steam pipeline materials and wall temperature control. Restricted by the creep strength and lasting strength of the material, the temperature fluctuation must be within the safety margin. Due to the deviation of the temperature measurement of the water wall, the parameters cannot be adjusted in time, and the long-term over-temperature operation of the water wall will inevitably increase the risk of pipe bursting. In addition, due to insufficient attention to the monitoring of the metal temperature of the high-temperature superheater, the domestic super (super) critical once-through boiler is prone to oxide skin peeling and blockage, and the superheater tube burst accident is also very likely to occur. Therefore, the real-time measurement of wall temperature and the advance prediction and control of wall temperature are effective ways to reduce the risk of pipe burst.

At present, coal-fired units mainly have the following two solutions for wall temperature measurement and control:

1) The wall temperature measurement is realized by installing a large number of thermocouple wall temperature measuring points at the tube wall metal of the boiler superheater, reheater, water wall and other parts, using a separate monitoring system or directly connecting to the DCS system for direct monitoring, Improve the safety and stability of the long-term operation of the boiler; at present, this method has higher requirements on the environment around the measuring point, and the environment in the furnace is often harsh, which has a certain impact on the accuracy and accuracy of the measurement; at the same time, this method can only measure To obtain the temperature value at the current moment, due to the large number of measuring points, an alarm will only be issued when the over-temperature phenomenon occurs at the measuring point, so that the operator can adjust the boiler parameters accordingly based on actual experience. In this way, operators cannot make real-time judgments on a large number of wall temperature measurement points during the process of wall temperature over-temperature monitoring, and when an over-temperature alarm occurs, control operations are being performed, and the over-temperature problem cannot be solved in time, which will ensure the safety of boiler operation. adversely affected.

2) The wall temperature prediction model is established by the mechanism or mathematical analysis method, so as to realize the calculation and prediction of the wall temperature. Among them, the wall temperature is calculated by the mechanism modeling analysis of the water-cooled wall, superheater and other components. This method is more complicated and has many boundary parameters. The actual measurement points of the power plant cannot give all boundary parameters, and the model needs to be continuously revised under different conditions. Therefore, It does not meet the requirements of online calculation, and cannot participate in the closed-loop control of the wall temperature of the power station in real time; based on the mathematical modeling analysis method, the wall temperature prediction method based on artificial neural network is mostly used at present, only considering the influence of external factors on the wall temperature, using BP Static network structures such as neural networks can predict boiler tube wall temperature. The current historical data of wall temperature, the historical data of upstream wall temperature and the rate of change of related factors are not considered, and the neural network structure of time series prediction, neural network activation function and other contents have not been studied, and the prediction structure is relatively backward and the calculation results are poor; And the current wall temperature prediction only stays in the display stage, and does not use the prediction results to participate in the closed-loop control of thermal power.

To sum up, the existing wall temperature over-temperature countermeasures and prediction methods only stay in the display alarm, so that the parameters are changed based on the experience of the operator, and closed-loop control is not realized. On the other hand, the wall temperature prediction model needs to be optimized, so as to achieve accurate prediction of wall temperature and realize early closed-loop operation to avoid over-temperature of wall temperature.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the above-mentioned prior art, the present invention proposes a system and method for over-temperature control of a coal-fired unit superheater based on wall temperature prediction, and simultaneously obtains the change trend of the predicted wall temperature and the current wall temperature, so as to complete the wall temperature Over-temperature control and operation guidance to achieve active suppression of advanced wall temperature and over-temperature are of great significance to improving the operational reliability of thermal power plants, effectively reducing the risk of pipe bursting, extending the life of key equipment, and reducing maintenance and repair costs.

In order to achieve the above object, the present invention adopts the following technical solutions:

Based on the prediction of wall temperature, the over-temperature control system of the superheater of the coal-fired unit, the boiler feed water flows through the low-temperature superheater 1 and is divided into left and right paths after heat exchange. The stage desuperheating water flow sensor 4 is connected to the left-side superheater 7, and the right side is connected to the right-side superheater 9 through the right primary desuperheating water regulating valve 5 and the right primary desuperheating water flow sensor 6; A plurality of low-temperature superheater wall temperature sensors 2 are arranged on the heater 1, a plurality of left-hand chimney-type superheater wall temperature sensors 8 are arranged on the left chimney-type superheater 7, and a right chim-type superheater 9 is arranged with A plurality of right-side chimney-type superheater wall temperature sensors 10; left chimney-type superheater 7 and right chim-type superheater 9 are respectively provided with left-hand chimney-type air baffles 11 and right-hand chimney-type superheater 9 12; the right side wall temperature sensor 10 is connected to the input end of the right side wall temperature maximum value calculation storage module 13 and the input end 14 of the right side wall temperature average calculation storage module , the low temperature superheater wall temperature sensor 2 is connected to the input end of the low temperature superheater wall temperature average calculation storage module 15, the right first stage desuperheating water flow sensor 6 is connected to the input of the right first stage desuperheating water flow differential calculation storage module 16 In the same way, the left side wall temperature sensor 8 and the left side wall temperature maximum value calculation storage module 17 and the left side wall temperature average calculation storage module 18 The input end of the left first stage desuperheating water flow sensor 4 is connected to the input end of the left first stage desuperheating water flow differential calculation and storage module 19 .

The right screen cross-wall temperature maximum value calculation storage module 13 , the right screen cross-wall temperature average calculation storage module 14 , the low temperature superheater wall temperature average calculation storage module 15 , the right first-level desuperheating water flow differential calculation storage module 16 The output end of the unit load data storage module 20 is connected to the input end of the right screen cross-wall temperature prediction model calculation module 21, and the output end of the right screen cross-wall temperature prediction model calculation module 21 is respectively connected with the right screen cross-wall temperature prediction model. The input end of the limiter module 23 is connected to the input end of the temperature rise rate limiter module 24, and the output end of the wall temperature prediction limiter module 23 and the output end of the temperature rise rate speed limiter module 24 are connected with the first or the right side of the module 25. The input end is connected; the right side wall temperature sensor 10 of the superheater is respectively connected with the input end of the right side screen passing the wall temperature current value limiting module 26 and the input end of the right side screen passing the wall temperature current value temperature rising rate speed limiting module 27 The output end of the current value limiting module 26 of the right screen crosses the wall temperature and the output end of the temperature rise rate limiting module 27 of the current value of the right screen crosses the wall temperature is connected to the input end of the 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 to the input end of the right desuperheating water/burn-out air control command bias module 35 to generate a control command, and the right desuperheating water/burning air The output end of the exhaust air control command bias module 35 is connected to and controls the first-stage desuperheating water regulating valve 5 on the right side and the burner wind baffle 12 on the right side; similarly, the storage module 17 for calculating the maximum value of the wall temperature on the left side screen, the left side The output end of the side screen cross-wall temperature average calculation and storage module 18, the low temperature superheater average temperature calculation and storage module 15, the left first-stage desuperheating water flow differential calculation and storage module 19 and the unit load data storage module 20 are connected to the left screen cross-wall. The input end of the temperature prediction model calculation module 22 is connected; the output end of the left screen cross wall temperature prediction model calculation module 22 is respectively connected with the input end of the left screen cross wall temperature prediction limit module 29 and the left screen cross wall temperature prediction temperature prediction module 29. The input end of the rate limiting module 30 is connected, the input end of the left panel cross-wall temperature prediction limiting module 29 and the output end of the left panel cross-wall temperature prediction temperature rising rate speed limiting module 30 are connected to the left first or module. 31 is connected; the left side wall temperature sensor 8 of the superheater is respectively connected with the input end of the left side screen passing the wall temperature current value limiting module 32 and the input end of the left side screen passing the wall temperature current value temperature rising rate speed limiting module 33 Connected, the output end of the left screen passing wall temperature current value limiting module 32 and the output end of the left screen passing wall temperature current value temperature rising rate speed limiting module 33 are connected with the left second or module 34; The output end of the OR module 31 and the output end of the second left OR module 34 are connected with the input end of the left desuperheating water/burnout air control command bias module 36 to generate a control command, and the left desuperheating water/burnout air control command The output end of the bias module 36 is connected to and controls the left primary desuperheating water regulating valve 3 and the left burner wind baffle 11; The calculation and storage module 18 is connected to the over-burning wind control command biasing module 37, thereby generating a burning wind control bias command to carry out the left burning wind baffle 11 and the burning wind. Control of the right burner wind damper 12.

The control method of the over-temperature control system of the superheater of the coal-fired unit based on the prediction of the wall temperature is as follows:

The multiple real-time data of the wall temperature collected by the wall temperature sensor 10 of the right-side superheater are sent to the right-side screen cross-wall temperature maximum value calculation and storage module 13 for calculation to obtain the right-side screen cross-wall temperature maximum value and the historical value. The data is stored, and at the same time, the average value of the right screen cross wall temperature is obtained through the right screen cross wall temperature average calculation storage module 14 and the historical data is stored; the wall temperature measured by the low temperature superheater wall temperature sensor 2 is sent to the low temperature. The superheater wall temperature average calculation and storage module 15 calculates and obtains the real-time low temperature superheater wall temperature average value and stores the historical data. The desuperheating water flow data measured by the right first-stage desuperheating water flow sensor 6 The flow differential calculation storage module 16 calculates and obtains the rate of change of the first-level desuperheating water on the right side; similarly, the wall temperature measured by the wall temperature sensor 8 of the left side superheater is sent to the left screen passing the wall temperature maximum value calculation storage module 17 for calculation The maximum value of the cross-wall temperature of the left screen and the historical data are stored, and the average value of the cross-wall temperature of the left screen is calculated by the storage module 18 of the average value of the cross-wall temperature of the left screen and the historical data is stored; The desuperheating water flow value measured by the warm water flow sensor 4 is sent to the left first-level desuperheating water flow differential calculation and storage module 19 to obtain the left desuperheating water change rate; The average value of the wall temperature, the average value of the wall temperature of the low temperature superheater, the rate of change of the first-stage desuperheating water on the right side, and the unit load are sent to the calculation module 21 of the prediction model of the right screen cross-wall temperature prediction model for calculation to obtain the prediction of the maximum value of the wall temperature of the right screen. The value is sent to the right screen cross-wall temperature prediction limit module 23 and the right screen cross-wall temperature prediction temperature rise rate speed limit module 24 to judge whether it exceeds the limit. Send the over-temperature signal to the right desuperheating water/over-burning wind control command bias module 35 to generate the burning wind bias command to control the opening of the right burning wind damper 12, thereby increasing the burning wind in advance and reducing the right screen On the other hand, the right side wall temperature measured by the right side superheater wall temperature sensor 10 is used to send the current value limiter module 26 of the right screen cross wall temperature and the current value temperature rise of the right screen cross wall temperature. The rate-limiting module 27 makes a judgment, and judges that any one of the over-limits is exceeded by the second or module 28 on the right, that is, sends an over-temperature signal to the right-side desuperheating water/burn-out wind control command bias module 35 to generate a burn-out wind bias command and The desuperheating water regulating door opening offset command, so as to realize the real-time control of the first-level desuperheating water regulating valve 5 on the right side and the burner wind baffle 12 on the right side, so as to avoid the over temperature of the screen passing through the wall;

In the same way, the calculated maximum value of the left screen passing wall temperature, the average value of the left screen passing wall temperature, the low temperature superheater wall temperature average value, the left first stage desuperheating water change rate and the unit load are sent to the left screen passing The wall temperature prediction model calculation module 22 performs calculation to obtain the maximum wall temperature prediction value of the left screen passing through, and sends it to the left screen passing wall temperature prediction limiting module 29 and the left screen passing wall temperature prediction temperature rise rate speed limiting module 30 for processing. Judging whether it exceeds the limit, the first or module 31 on the left side judges that any one exceeds the limit, that is, sends an over-temperature signal and sends it to the left desuperheating water/burning air control command bias module 36 to generate a burning ember wind bias command to control the left side combustion. The opening of the ember air baffle is 11 degrees, thereby increasing the combustion air in advance to reduce the wall temperature of the left side screen; on the other hand, the left side wall temperature measured by the wall temperature sensor 8 of the left side superheater is sent to the left side screen. The wall temperature current value limiting module 32 and the left screen pass the wall temperature current value temperature rise rate speed limiting module 33 to judge, and the second or module 34 on the left judges that any one exceeds the limit, that is, sends an over-temperature signal to the left side to reduce the temperature. The warm water/over-burning air control command bias module 36 generates the burning air bias command and the desuperheating water gate opening bias command, so as to realize the real-time monitoring of the left primary desuperheating water regulating valve 3 and the left burning air baffle 11 Control, avoid screen over temperature and over temperature;

Finally, the left and right side screen cross-wall temperature average values calculated by the right side screen cross-wall temperature average value calculation storage module 14 and the left side screen cross-wall temperature average value calculation storage module 18 are sent to the overburning wind control command bias module 37 for processing. It is judged that when the temperature deviation of the two side walls is greater than the protection set value, the combustion wind control bias command is generated to control the left combustion wind damper 11 and the right combustion wind damper 12, and the larger the wall temperature is higher. The opening degree of the combustion air baffle on the high side and the opening degree of the combustion air baffle on the lower temperature side are reduced, so as to reduce the temperature deviation of the screen on both sides.

Compared with the prior art, the present invention has the following advantages:

(1) The existing technology only installs a large number of thermocouple wall temperature measuring points at the tube wall metal of the boiler superheater, reheater, water wall and other parts to realize wall temperature measurement, using a separate monitoring system or directly connecting to DCS The system directly monitors; this method can only measure the temperature value at the current moment, and an alarm will only be issued when the over-temperature phenomenon occurs at the measuring point. On the other hand, the operators cannot make real-time judgments on a large number of wall temperature measurement points during the process of monitoring the wall temperature over-temperature, and when an over-temperature alarm occurs, they are performing control operations and processing, and they cannot solve the over-temperature problem in time. Security has an adverse effect. The invention is developed on the basis of the existing wall temperature measurement points, without adding wall temperature measurement point transformation, and the wall temperature over-temperature prediction and over-temperature closed-loop control can be realized through wall temperature prediction and wall temperature control, which effectively reduces the over-temperature of the screen. Risk of excessive wall temperature.

(2) Due to the uneven flow of flue gas in the flue, it is easy to cause the wall temperature difference between the left and right screen superheaters to be too large, resulting in the risk of overtemperature on one side. At present, there is no better control method except for combustion adjustment. When it is judged that there is a large risk of the difference between the left and right wall temperatures, the invention realizes the purpose of assisting the adjustment of the flue gas flow by means of the adjustment function of the upper layer of the combustion air baffle in a short period of time, reduces the risk of over-temperature, and further enriches the combustion air. Automatic control function of the shutter.

(3) In the present invention, the wall temperature is predicted in advance, and when the over-temperature is predicted, the over-temperature of the wall is reduced in advance by adjusting the effect of the burnout wind. At the same time, according to the actual temperature measurement data, real-time alarm and anti-over-temperature control are carried out, and the desuperheating water and burning air are adjusted in real time to complete the control through real data, so as to ensure two-level protection, so as to realize the over-temperature automatic protection of the screen superheater and prevent the combustion It is of great significance to solve the problem of screen over temperature and over temperature faced by coal generating units.

Description of drawings

FIG. 1 is a schematic diagram of the over-temperature control system of the coal-fired unit superheater based on wall temperature prediction according to the present invention.

The reference numerals and corresponding component names in the figure are explained as follows:

1 Low temperature superheater

2 Low temperature superheater wall temperature sensor

3 Left first stage desuperheating water regulating valve

4 Left first stage desuperheating water flow sensor

5 Right first stage desuperheating water regulating valve

6 Right first stage desuperheating water flow sensor

7 Left side superheater

8 Wall temperature sensor of left side superheater

9 Right side superheater

10 Wall temperature sensor of the right side superheater

11 Left ember air baffle

12 Right ember air baffle

13 Storage module for calculating the maximum value of the wall temperature on the right

14 The storage module for calculating the average value of the wall temperature of the right screen

15 Storage module for calculating the average value of low temperature superheater wall temperature

16 Storage module for differential calculation of the first-level desuperheating water flow on the right

17 The storage module for calculating the maximum value of the wall temperature on the left side

18 Storage module for calculating the average value of the left screen across the wall temperature

19 Storage module for the differential calculation of the first-level desuperheating water flow on the left

20 Unit load data storage module

21 Calculation module of the right screen over-wall temperature prediction model

22. Calculation module of left screen passing wall temperature prediction model

23 Right screen over-wall temperature prediction limiting module

24 Speed-limiting module for predicting the temperature rise rate of the right screen over the wall temperature

25 Right first or module

26 Limiting module for the current value of the right screen cross-wall temperature

27 Speed limiting module of temperature rise rate and current value of wall temperature on the right side of the screen

28 Right second or module

29 Left-side panel cross-wall temperature prediction limiting module

30 Speed limiting module for predicting the temperature rise rate of the left screen over the wall temperature

31 Left first or module

32 Limiting module for the current value of the left screen across the wall temperature

33 Speed limiting module for the temperature rise rate of the current value of the wall temperature on the left screen

34 Left second or module

35 Right desuperheating water/overburning air control command bias module

36 Left desuperheating water/overburning air control command bias module

37 Overburn air control command bias module.

Detailed ways

As shown in Figure 1, the present invention is based on the wall temperature prediction of the over-temperature control system for the superheater of the coal-fired unit. The warm water regulating valve 3 and the left first stage desuperheating water flow sensor 4 are connected to the left side superheater 7, and the right side is connected to the right side through the right first stage desuperheating water regulating valve 5 and the 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 wall temperature sensors 10 of the right-hand side-type superheater 9 are arranged; the corresponding sides of the left side-type superheater 7 and the right side-type superheater 9 are respectively arranged with a left-side burner wind baffle 11 and the right side burner wind baffle 12; the right side chimney type superheater wall temperature sensor 10 and the right side chimney type superheater wall temperature maximum value calculation storage module 13 The input end and the right side chimney type superheater wall temperature average value The input end 14 of the calculation storage module is connected, the low temperature superheater wall temperature sensor 2 is connected to the input end of the low temperature superheater wall temperature average calculation storage module 15, and the right first stage desuperheating water flow sensor 6 is connected to the right first stage desuperheating water. The input end of the flow differential calculation storage module 16 is connected; in the same way, the left side wall temperature sensor 8 and the left side wall temperature maximum value calculation storage module 17 are connected to the input end of the left side type superheater. The input end of the wall temperature average value calculation storage module 18 is connected, and the left primary desuperheating water flow sensor 4 is connected to the input end of the left primary desuperheated water flow differential calculation storage module 19 .

The right screen cross-wall temperature maximum value calculation storage module 13 , the right screen cross-wall temperature average calculation storage module 14 , the low temperature superheater wall temperature average calculation storage module 15 , the right first-level desuperheating water flow differential calculation storage module 16 The output end of the unit load data storage module 20 is connected to the input end of the right screen cross-wall temperature prediction model calculation module 21, and the output end of the right screen cross-wall temperature prediction model calculation module 21 is respectively connected with the right screen cross-wall temperature prediction model. The input end of the limiter module 23 is connected to the input end of the temperature rise rate limiter module 24, and the output end of the wall temperature prediction limiter module 23 and the output end of the temperature rise rate speed limiter module 24 are connected with the first or the right side of the module 25. The input end is connected; the right side wall temperature sensor 10 of the superheater is respectively connected with the input end of the right side screen passing the wall temperature current value limiting module 26 and the input end of the right side screen passing the wall temperature current value temperature rising rate speed limiting module 27 The output end of the current value limiting module 26 of the right screen crosses the wall temperature and the output end of the temperature rise rate limiting module 27 of the current value of the right screen crosses the wall temperature is connected to the input end of the 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 to the input end of the right desuperheating water/burn-out air control command bias module 35 to generate a control command, and the right desuperheating water/burning air The output end of the exhaust air control command bias module 35 is connected to and controls the first-stage desuperheating water regulating valve 5 on the right side and the burner wind baffle 12 on the right side; similarly, the storage module 17 for calculating the maximum value of the wall temperature on the left side screen, the left side The output end of the side screen cross-wall temperature average calculation and storage module 18, the low temperature superheater average temperature calculation and storage module 15, the left first-stage desuperheating water flow differential calculation and storage module 19 and the unit load data storage module 20 are connected to the left screen cross-wall. The input end of the temperature prediction model calculation module 22 is connected; the output end of the left screen cross wall temperature prediction model calculation module 22 is respectively connected with the input end of the left screen cross wall temperature prediction limit module 29 and the left screen cross wall temperature prediction temperature prediction module 29. The input end of the rate limiting module 30 is connected, the input end of the left panel cross-wall temperature prediction limiting module 29 and the output end of the left panel cross-wall temperature prediction temperature rising rate speed limiting module 30 are connected to the left first or module. 31 is connected; the left side wall temperature sensor 8 of the superheater is respectively connected with the input end of the left side screen passing the wall temperature current value limiting module 32 and the input end of the left side screen passing the wall temperature current value temperature rising rate speed limiting module 33 Connected, the output end of the left screen passing wall temperature current value limiting module 32 and the output end of the left screen passing wall temperature current value temperature rising rate speed limiting module 33 are connected with the left second or module 34; The output end of the OR module 31 and the output end of the second left OR module 34 are connected with the input end of the left desuperheating water/burnout air control command bias module 36 to generate a control command, and the left desuperheating water/burnout air control command The output end of the bias module 36 is connected to and controls the left primary desuperheating water regulating valve 3 and the left burner wind baffle 11; The calculation and storage module 18 is connected with the over-burning wind control command biasing module 37, so as to generate a burning wind control bias command to carry out the left burning wind baffle 11 and the burning wind. Control of the right burner wind damper 12.

As shown in Figure 1, the present invention is based on the control method of the over-temperature control system of the coal-fired unit's superheater overheating control system based on wall temperature prediction as follows:

The multiple real-time data of the wall temperature collected by the wall temperature sensor 10 of the right-side superheater are sent to the right-side screen cross-wall temperature maximum value calculation and storage module 13 for calculation to obtain the right-side screen cross-wall temperature maximum value and the historical value. The data is stored, and at the same time, the average value of the right screen cross wall temperature is obtained through the right screen cross wall temperature average calculation storage module 14 and the historical data is stored; the wall temperature measured by the low temperature superheater wall temperature sensor 2 is sent to the low temperature. The superheater wall temperature average calculation and storage module 15 calculates and obtains the real-time low temperature superheater wall temperature average value and stores the historical data. The desuperheating water flow data measured by the right first-stage desuperheating water flow sensor 6 The flow differential calculation storage module 16 calculates and obtains the rate of change of the first-level desuperheating water on the right side; similarly, the wall temperature measured by the wall temperature sensor 8 of the left side superheater is sent to the left screen passing the wall temperature maximum value calculation storage module 17 for calculation The maximum value of the cross-wall temperature of the left screen and the historical data are stored, and the average value of the cross-wall temperature of the left screen is calculated by the storage module 18 of the average value of the cross-wall temperature of the left screen and the historical data is stored; The desuperheating water flow value measured by the warm water flow sensor 4 is sent to the left first-level desuperheating water flow differential calculation and storage module 19 to obtain the left desuperheating water change rate; The average value of the wall temperature, the average value of the wall temperature of the low temperature superheater, the rate of change of the first-stage desuperheating water on the right side, and the unit load are sent to the calculation module 21 of the prediction model of the right screen cross-wall temperature prediction model for calculation to obtain the prediction of the maximum value of the wall temperature of the right screen. The value is sent to the right screen cross-wall temperature prediction limit module 23 and the right screen cross-wall temperature prediction temperature rise rate speed limit module 24 to judge whether it exceeds the limit. Send the over-temperature signal to the right desuperheating water/over-burning wind control command bias module 35 to generate the burning wind bias command to control the opening of the right burning wind damper 12, thereby increasing the burning wind in advance and reducing the right screen On the other hand, the right side wall temperature measured by the right side superheater wall temperature sensor 10 is used to send the current value limiter module 26 of the right screen cross wall temperature and the current value temperature rise of the right screen cross wall temperature. The rate-limiting module 27 makes a judgment, and judges that any one of the over-limits is exceeded by the second or module 28 on the right, that is, sends an over-temperature signal to the right-side desuperheating water/burn-out wind control command bias module 35 to generate a burn-out wind bias command and The desuperheating water regulating door opening offset command, so as to realize the real-time control of the first-level desuperheating water regulating valve 5 on the right side and the burner wind baffle 12 on the right side, so as to avoid the over temperature of the screen passing through the wall;

In the same way, the calculated maximum value of the left screen passing wall temperature, the average value of the left screen passing wall temperature, the low temperature superheater wall temperature average value, the left first stage desuperheating water change rate and the unit load are sent to the left screen passing The wall temperature prediction model calculation module 22 performs calculation to obtain the maximum wall temperature prediction value of the left screen passing through, and sends it to the left screen passing wall temperature prediction limiting module 29 and the left screen passing wall temperature prediction temperature rise rate speed limiting module 30 for processing. Judging whether it exceeds the limit, the first or module 31 on the left side judges that any one exceeds the limit, that is, sends an over-temperature signal and sends it to the left desuperheating water/burning air control command bias module 36 to generate a burning ember wind bias command to control the left side combustion. The opening of the ember air baffle is 11 degrees, thereby increasing the combustion air in advance to reduce the wall temperature of the left side screen; on the other hand, the left side wall temperature measured by the wall temperature sensor 8 of the left side superheater is sent to the left side screen. The wall temperature current value limiting module 32 and the left screen pass the wall temperature current value temperature rise rate speed limiting module 33 to judge, and the second or module 34 on the left judges that any one exceeds the limit, that is, sends an over-temperature signal to the left side to reduce the temperature. The warm water/over-burning air control command bias module 36 generates the burning air bias command and the desuperheating water gate opening bias command, so as to realize the real-time monitoring of the left primary desuperheating water regulating valve 3 and the left burning air baffle 11 Control, avoid screen over temperature and over temperature;

Finally, the left and right side screen cross-wall temperature average values calculated by the right side screen cross-wall temperature average value calculation storage module 14 and the left side screen cross-wall temperature average value calculation storage module 18 are sent to the overburning wind control command bias module 37 for processing. It is judged that when the temperature deviation of the two side walls is greater than the protection set value, the combustion wind control bias command is generated to control the left combustion wind damper 11 and the right combustion wind damper 12, and the larger the wall temperature is higher. The opening degree of the combustion air baffle on the high side and the opening degree of the combustion air baffle on the lower temperature side are reduced, so as to reduce the temperature deviation of the screen on both sides.

Claims (4)

1. The over-temperature control system of the coal-fired unit's superheater based on the prediction of wall temperature, is characterized in that: the boiler feed water is divided into left and right after heat exchange through the low-temperature superheater (1), and the left side passes through the first-level reduction of the left side. The warm water regulating valve (3) and the left primary desuperheating water flow sensor (4) are connected to the left side superheater (7), and the right passes through the right primary desuperheating water regulating valve (5) and the right primary desuperheater. The warm water flow sensor (6) is connected to the right-side superheater (9); a plurality of low-temperature superheater wall temperature sensors (2) are arranged on the low-temperature superheater (1), and on the left-hand side-type superheater (7) A plurality of wall temperature sensors (8) are arranged on the left-hand side-type superheater, and a plurality of right-side-type superheater wall temperature sensors (10) are arranged on the right side-type superheater (9). Corresponding sides of the superheater (7) and the right-side superheater (9) are respectively provided with a left-hand combustion air baffle (11) and a right-hand combustion air baffle (12); The temperature sensor (10) is connected to the input end (13) of the storage module (13) for calculating the maximum value of the wall temperature of the right-side superheater and the input end (14) of the storage module for calculating the average value of the wall temperature of the right-side type superheater. The wall temperature sensor (2) is connected to the input end of the low temperature superheater wall temperature average value calculation storage module (15), and the right primary desuperheating water flow sensor (6) is connected to the right primary desuperheated water flow differential calculation storage module (15). 16) is connected to the input end; in the same way, the input end of the left-side slug-type superheater wall temperature sensor (8) and the left-side s-type superheater maximum wall temperature calculation storage module (17) and the left-side slug-type superheater The input end of the wall temperature average value calculation storage module (18) is connected, 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); A storage module (13) for calculating the maximum value of the cross-wall temperature of the right screen, a storage module for calculating the average value of the cross-wall temperature of the right screen (14), a storage module for calculating the average value of the wall temperature of the low-temperature superheater (15), and the first-grade desuperheating water on the right The output end of the flow differential calculation and storage module (16) and the unit load data storage module (20) are connected to the input end of the right screen passing wall temperature prediction model calculation module (21), and the right screen passing wall temperature prediction model calculation module ( The output end of 21) is respectively connected with the input end of the right screen cross-wall temperature prediction limiting module (23) and the input end of the temperature rise rate speed limiting module (24), and the output end of the wall temperature prediction limiting module (23) The output end of the temperature rise rate limiting module (24) is connected with the input end of the first or module (25) on the right side; The input end of the value limiting module (26) is connected with the input end of the right side screen cross-wall temperature current value temperature rise rate speed limiting module (27), and the output end of the right screen cross-wall temperature current value limiting module (26) and the output terminal of the right side screen temperature rise rate speed limiting module (27) is connected with the input terminal of the second right or module (28); the output terminal of the right first or module (25) is connected to the right side The output end of the side second or module (28) is connected with the input end of the right desuperheating water/burn-out air control command bias module (35) to generate a control command, and the right desuperheating water/over-burn air control command bias module ( The output end of 35) is connected to and controls the first-stage desuperheating water regulating valve (5) on the right and the ember air baffle (12) on the right; similarly, the storage module (17) for calculating the maximum value of the wall temperature on the left A storage module (18) for calculating the average temperature across the wall of the side screen, a storage module for calculating the average temperature of a low temperature superheater (15), a storage module for calculating the differential flow rate of the first-stage desuperheating water on the left side (19), and a unit load data storage module (20). The output end is connected with the input end of the left screen passing-wall temperature prediction model calculation module (22); the output end of the left screen passing-wall temperature prediction model calculation module (22) is respectively connected with the left screen passing-wall temperature prediction limiting module ( The input end of 29) is connected to the input end of the left screen cross-wall temperature prediction temperature rise rate limiting module (30), and the input end of the left screen cross-wall temperature prediction limiting module (29) is connected to the left screen cross-wall temperature prediction limiter module (29). The output end of the predicted temperature rise rate limiting module (30) is connected to the left first or module (31); the left side wall temperature sensor (8) of the superheater is respectively limited to the current value of the left screen passing wall temperature The input end of the module (32) is connected to the input end of the left screen passing wall temperature current value temperature rise rate limiting module (33), and the output end of the left screen passing wall temperature current value limiting module (32) is connected to the left The output end of the temperature rise rate limiting module (33) of the current value of the screen passing wall temperature is connected with the left second or module (34); the output end of the left first or module (31) is connected with the left second or module (34). The output end of 34) is connected to the input end of the left desuperheating water/burn-out air control command bias module (36) to generate a control command, and the output end of the left desuperheating water/over-burn air control command bias module (36) is connected to And control the left first stage desuperheating water The regulating valve (3) and the left burner wind baffle (11); the right side screen passing the wall temperature average temperature calculation storage module (14) and the left side screen passing the wall temperature average temperature calculation storage module (18) and the burnout wind The control command bias module (37) is connected to generate a combustion wind control bias command to control the left combustion wind damper (11) and the right combustion wind damper (12). 2. the over-temperature control system of the coal-fired unit's flood-type superheater based on wall temperature prediction according to claim 1, is characterized in that: the described coal-fired unit's flood-type superheater over-temperature control system one based on the wall temperature prediction Aspects include a calculation module (21) for the prediction model of the right screen passing through the wall temperature, and a calculation module (22) for the prediction model of the left screen passing through the wall temperature, and combined with the predicted temperature through the right screen passing through the wall temperature prediction limit module (23), The right screen cross-wall temperature prediction temperature rise rate limit module (24), the left screen cross-wall temperature prediction limit module (29), and the left screen cross-wall temperature prediction temperature rise rate speed limit module (30) determine whether Over-limit alarm; on the other hand, it includes the left side-type superheater wall temperature sensor 8 and the right side-type superheater wall temperature sensor (10), combined with the measured left and right side wall temperatures through the right screen Wall temperature current value limiting module (26), right screen passing wall temperature current value temperature rise rate speed limiting module (27), left screen passing wall temperature current value limiting module (32), left screen passing wall temperature The current value temperature rise rate speed limiting module (33) judges whether an over-limit alarm is given. 3. the over-temperature control system of the coal-fired unit's superheater based on wall temperature prediction according to claim 1, it is characterized in that: described left side burning ember wind baffle (11) and right burning ember wind baffle (12) It belongs to the secondary air system of the boiler, which is arranged around the boiler, and the combustion air baffles located on the corresponding sides of the left-side superheater (7) and the right-side superheater (9) are selected to control the fire The problem of over-temperature of the superheater and the large deviation of wall temperature caused by the uneven flow of flue gas on both sides. 4. the control method of the over-temperature control system of the coal-fired unit's superheater overheating system based on the prediction of wall temperature according to any one of claims 1 to 3 is: it is characterized in that: The multiple real-time data of the wall temperature collected by the wall temperature sensor (10) of the right-side type superheater are sent to the calculation and storage module (13) for calculating the maximum value of the right-side screen passing-wall temperature to obtain the maximum value of the right-side screen passing-wall temperature. value and store the historical data, and at the same time obtain the average value of the right screen cross-wall temperature through the right screen cross-wall temperature average calculation and storage module (14) and store the historical data; store the low-temperature superheater wall temperature sensor (2 ) measured wall temperature is sent to the low temperature superheater wall temperature average calculation storage module (15) for calculation to obtain the real-time low temperature superheater wall temperature average value and the historical data is stored, and the first-level desuperheating water flow sensor (6) on the right side measures The desuperheating water flow rate data on the right is calculated by the first-stage desuperheating water flow differential calculation and storage module (16) on the right to obtain the change rate of the first-stage desuperheating water on the right; The temperature is sent to the left screen cross-wall temperature maximum value calculation and storage module (17) to calculate the left screen cross-wall temperature maximum value and store the historical data, and the left screen cross-wall temperature average value calculation storage module (18) calculates the left screen cross-wall temperature. The average value of the cross-wall temperature of the side screen and the historical data are stored; the desuperheating water flow value measured by the left first-stage desuperheating water flow sensor (4) is sent to the left first-stage desuperheating water flow differential calculation and storage module (19) for calculation to obtain The rate of change of the desuperheating water on the left side; then the calculated maximum value of the right screen passing wall temperature, the average value of the right screen passing wall temperature, the average value of the wall temperature of the low temperature superheater, the change rate of the first stage desuperheating water on the right side, and the unit load are sent to Enter the calculation module (21) for the prediction model of the right screen over-the-wall temperature to obtain the predicted value of the right screen over-the-wall maximum temperature, and send it to the right-side screen over-the-wall temperature prediction limiting module (23) and the right screen over-the-wall temperature The predicted temperature rise rate speed limit module (24) judges whether it exceeds the limit, and the first or module (25) on the right side judges that any one exceeds the limit, that is, an overtemperature signal is sent to the right desuperheating water/burnout air control command bias The module (35) generates a combustion air bias command to control the opening of the right combustion air baffle (12), thereby increasing the combustion air in advance to reduce the temperature of the right panel passing through the wall. The right side wall temperature actually measured by the wall temperature sensor (10) is sent to the right side screen passing wall temperature current value limiting module (26) and the right side screen passing wall temperature current value temperature rising rate speed limiting module (27) for judgment, The second OR module (28) on the right side judges that any one exceeds the limit, that is, an over-temperature signal is sent to the right desuperheating water/over-burning air control command and bias module (35) to generate the burning air bias command and the desuperheating water adjustment door to open. It can realize the real-time control of the first-stage desuperheating water regulating valve (5) on the right side and the ember air baffle (12) on the right side, so as to avoid the over-temperature of the screen passing through the wall; In the same way, the calculated maximum value of the left screen passing wall temperature, the average value of the left screen passing wall temperature, the low temperature superheater wall temperature average value, the left first stage desuperheating water change rate and the unit load are sent to the left screen passing The wall temperature prediction model calculation module (22) performs calculation to obtain the predicted value of the maximum wall temperature over the left screen, and sends it to the left screen over the wall temperature prediction limit module (29) and the left screen over the wall temperature prediction temperature rise rate limit. The speed module (30) judges whether it exceeds the limit, and the left first or module (31) judges that any one exceeds the limit, that is, sends an over-temperature signal to the left desuperheating water/burn-out air control command bias module (36) to generate The burner wind bias command controls the opening of the left burner wind baffle (11), thereby increasing the burner wind in advance to reduce the wall temperature of the left screen; on the other hand, the left side wall temperature sensor ( 8) The measured left wall temperature is sent to the current value limiting module (32) of the left screen passing wall temperature and the left screen passing wall temperature current value temperature rising rate speed limiting module (33) for judgment. Or the module (34) judges that any one exceeds the limit and sends the over-temperature signal to the left desuperheating water/over-burning air control command bias module (36) to generate the burning air bias command and the desuperheating water door opening bias command, Thereby, the real-time control of the left first-stage desuperheating water regulating valve (3) and the left burner wind baffle (11) is realized, so as to avoid the over temperature of the screen passing through the wall; Finally, the average value of the left and right side screen passing wall temperature calculated by the right side screen passing wall temperature average temperature calculation storage module (14) and the left side screen passing wall temperature mean value calculation storage module (18) is sent to the overburning wind control command bias The module (37) is set to judge, and when the temperature deviation of the two side walls is greater than the protection set value, a combustion wind control bias command is generated to execute the left combustion wind damper (11) and the right combustion wind damper ( 12), increase the opening of the air baffle on the side with the higher wall temperature, and reduce the opening of the air baffle on the side with the lower temperature, so as to reduce the deviation of the wall temperature on both sides of the screen.

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