Preheater hot spot detection method and system

Abstract

The invention discloses a preheater hot spot detection method and system, and relates to the technical field of preheater hot spot monitoring. Temperature signals of all measuring points on an air preheater are obtained, the temperature signals of all the measuring points are input to an intelligent fire judgment model, whether hot spots exist in the air preheater or not is judged, and finally the judgment result is transmitted to an embedded touch screen and a DCS; entering a human-computer interface through internal software of the embedded touch screen; the embedded touch screen carries out fire alarm through the color and state of a signal indicating lamp on the human-computer interface. The fire condition and the equipment state are judged according to the color and state of the signal indicator lamp; clicking the man-machine interface fault query button, the real-time data button, the historical data button and the parameter setting button to enter a corresponding sub-page, and clicking a return button to return to a previous interface; and when the fire alarm needs to be eliminated, the man-machine interface alarm elimination button is clicked to eliminate the alarm information. The reliability is high; the compactness is high; the maintainability is easy; and the real-time performance of hotspot detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of preheater hot spot monitoring, and in particular to a preheater hot spot detection method and system. Background Art

[0002] The hot spot monitoring system of the air preheater of a power plant boiler is an indispensable device for monitoring whether there are fire hazards inside the air preheater and ensuring the safe, economical and reliable operation of the unit. A large number of simulation experiments and fire scene data show that most air preheater fires often occur during cold start-up and start-up after hot standby. These fires are caused by incomplete combustion of fuel oil, which results in the condensation and accumulation of incompletely burned fuel oil on the parts of the air preheater. When the temperature of the flue gas entering the air preheater increases, the deposited fuel oil dirt is baked and hardened. When a certain temperature condition is reached, these fuel oil deposits can be ignited, causing a fire.

[0003] In the prior art, the internal environment of the air preheater of a power plant boiler is harsh, and the existing HSDS-30 system is difficult to perform hotspot detection with high precision and high stability. Therefore, we propose a preheater hotspot detection method and system to solve the above problem. Summary of the invention

[0004] The object of the present invention is to provide a preheater hot spot detection method and system to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a preheater hot spot detection method, comprising:

[0006] Obtain the temperature signals of each measuring point on the air preheater, input the temperature signals of each measuring point into the "intelligent fire judgment model", judge whether there is a hot spot in the air preheater, and finally transmit the judgment result to the embedded touch screen and DCS system;

[0007] Entering the human-machine interface through the internal software of the embedded touch screen;

[0008] The embedded touch screen uses the color and status of the signal indicator light on the human-machine interface to issue a fire alarm;

[0009] Determine the fire situation and equipment status by the color and status of the signal indicator light;

[0010] Click the buttons for fault query, real-time data, historical data and parameter setting on the human-machine interface to enter the corresponding sub-pages, and click the return button to return to the previous interface;

[0011] When it is necessary to eliminate the fire alarm, click the alarm elimination button on the human-machine interface to eliminate the alarm information.

[0012] Furthermore, the signal indicator lights include: a fire alarm indicator light, an over-temperature warning light, a system fault indicator light, a cooling fault indicator light, a sensor indicator light and icon indicator lights of each component.

[0013] Furthermore, the color and state of the signal light include permanent green and red and green flashing alternately.

[0014] Furthermore, when the fire alarm indicator light flashes red and green at intervals, it indicates a fire has occurred; when it is always green, it indicates that no fire has occurred; when the over-temperature warning light flashes red and green at intervals, it indicates that the temperature exceeds the over-temperature warning threshold; when it is always green, it indicates that the temperature is normal; when the system fault indicator light flashes red and green at intervals, it indicates that a probe or thermocouple or thermistor has a fault; when it is always green, it indicates that the probe and the thermocouple or thermistor are working normally; when the cooling fault indicator light is always green, the cooling air is normal; when it flashes red and green at intervals, it indicates a cooling air fault; the sensor indicator light is used to indicate whether the corresponding sensor is normal; when it is always green, it indicates normal; and when it flashes, it indicates a fault.

[0015] Furthermore, the sensor indicator lights include indicator lights of intelligent infrared probes, thermocouples and thermal resistors; and the component icon indicator lights correspond to the intelligent infrared probes, thermocouples and thermal resistors on the air preheater.

[0016] The fault query subpage includes: displaying the fire alarm signal and occurrence time; displaying specific fault information and occurrence time; clicking the "previous day" button to display the fault record of the previous day; clicking the "next day" button to display the fault record of the next day;

[0017] The real-time data subpage includes: displaying the temperature of each intelligent infrared probe; displaying the real-time temperature of each thermocouple; displaying the temperature rise per second of each thermocouple; displaying the real-time temperature of each thermal resistor; displaying the temperature rise per second of each thermal resistor; clicking the corresponding measuring point button to display the real-time data of the measuring point, such as clicking the "1# infrared" button to display the real-time temperature value of "No. 1 intelligent infrared probe";

[0018] The historical data subpage includes: clicking the corresponding measuring point button to display the historical data of the measuring point, such as clicking the "1#" button to display the historical data of "No. 1 infrared probe"; clicking the "previous day" button to display the data of the previous day; clicking the "next day" button to display the data of the next day;

[0019] The parameter setting sub-page includes:

[0020] Infrared probe alarm threshold: It is an important parameter related to the infrared probe alarm. When its measured value reaches the preset value at the corresponding position, an alarm is triggered.

[0021] Infrared probe cooling alarm threshold: set the cooling wind detection threshold;

[0022] Thermocouple and thermal resistor alarm threshold: It is an important parameter related to the alarm of thermocouple and thermal resistor. When the measured value is greater than this parameter, an alarm will be triggered.

[0023] Thermocouple and thermal resistor temperature rise alarm threshold: When the temperature rise per second of the thermocouple or thermal resistor measurement value reaches this parameter, an alarm will be triggered.

[0024] A preheater hot spot detection system, comprising:

[0025] Temperature sampling and transmission system; collecting the temperature field signal of the air preheater rotor, the collecting of the temperature field signal of the air preheater rotor is completed by an intelligent infrared probe, a thermocouple and a thermal resistor, wherein the temperature signal sampling of the thermocouple and the thermal resistor is completed by a PLC, the sampling of the temperature signal of the intelligent infrared probe and the transmission of the data are completed by the CPU chip inside the intelligent infrared probe; the intelligent infrared probe is connected to the PLC via a Modbus bus, and the data of the temperature signal sampling is transmitted to the PLC;

[0026] Temperature signal processing and transmission system; fire alarm output dry node, fault detection, the fire alarm output dry node, fault detection is completed through the PLC switch module; the PLC is connected to the DCS system through the TCP / IP Modbus bus embedded touch screen, the PLC is connected to the DCS system through the communication interface, and the system status, system fault alarm and fire alarm information are transmitted to the embedded touch screen for display through the PLC;

[0027] Alarm display system; displays system status, system fault alarm and fire alarm information, and the system status, system fault alarm and fire alarm are displayed through an embedded touch screen.

[0028] Furthermore, the PLC is embedded with a touch screen via a TCP / IP Modbus bus, and the PLC is connected to a DCS system via a communication interface, and the system status, system fault alarm and fire alarm information are transmitted to the embedded touch screen for display via the PLC.

[0029] Furthermore, the intelligent infrared probe includes a lens, a connecting pipe, an air inlet, a valve and circuit elements.

[0030] Furthermore, the intelligent infrared probe converter adopts digital signal processing, and the intelligent infrared probe data is output in Modbus bus mode.

[0031] Furthermore, the intelligent infrared probe also includes a dust cleaning structure and a lens protection structure, and the intelligent infrared probe cleans dust on the lens through the dust cleaning structure.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. High reliability; all measuring points are external structures, which can be maintained and replaced online. The system is simple and reliable. The temperature measuring infrared probe of the traditional analog circuit is changed to a digital intelligent infrared probe, which improves the detection accuracy and greatly extends the life of the sensor. The cooling system is changed from the water cooling device of HSDS-30 to the air cooling device, and the whole cooling system is simpler and more reliable.

[0034] 2. High compactness: The bus communication structure is used to replace the traditional hard wiring structure, which greatly reduces the number of connection terminals and improves reliability. The reliable PLC control device and compact embedded touch screen make the system more concise and greatly save costs.

[0035] 3. Easy to maintain; the system's operating status and fault alarms are provided to the user's DCS system in a standard bus manner; the human-machine interface can also well reflect the system's operating status and fault alarms; infrared probe components and thermocouples and thermal resistance temperature measuring elements can be easily and quickly replaced online; the new system has changed from the original centralized control of the two air preheaters to independent control, and the hot spot detection systems of the two air preheaters do not affect each other, making the system easier to maintain.

[0036] 4. Real-time hotspot detection: replace mobile dual-point detection with plug-in multi-point detection to improve the real-time nature of fire warning. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of the preheater hot spot detection method of the present invention;

[0038] Figure 2 It is a flow chart of the preheater hot spot detection system in the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the intelligent infrared probe in the present invention.

[0040] In the figure: 11, lens; 12, connecting pipe; 13, welding seat; 14, air inlet; 15, valve; 16, circuit element; 201, temperature sampling and transmission system; 202, temperature signal processing and transmission system; 203, alarm display system.

[0041] Specific implementation

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] A preheater hot spot detection method, comprising:

[0044] Step 101, obtaining temperature signals of various measuring points on the air preheater;

[0045] Step 102, input the temperature signal of each measuring point into the "intelligent fire judgment model" to judge whether there is a hot spot in the air preheater, and finally transmit the judgment result to the embedded touch screen and DCS system;

[0046] Step 103, entering the human-machine interface through the internal software of the embedded touch screen;

[0047] Step 104, the embedded touch screen uses the color and status of the signal indicator light on the human-machine interface to issue a fire alarm; the fire situation and equipment status are judged by the color and status of the signal indicator light; wherein the signal indicator light includes: a fire alarm indicator light, an over-temperature warning light, a system fault indicator light, a cooling fault indicator light, a sensor indicator light, and each component icon indicator light; the color and status of the signal light include always green and red and green flashing at intervals; when the fire alarm indicator light flashes red and green at intervals, it indicates that a fire has occurred, and when it is always green, it indicates that no fire has occurred; when the over-temperature warning light flashes red and green at intervals, it indicates that the temperature has exceeded the limit; When the temperature exceeds the over-temperature warning threshold and it is always green, it means the temperature is normal; when the system fault indicator light flashes red and green at intervals, it means the probe or thermocouple or thermal resistor is faulty, and when it is always green, it means the probe, thermocouple or thermal resistor are working normally; when the cooling fault indicator light is always green, the cooling air is normal, and when it flashes red and green at intervals, it means the cooling air is faulty; the sensor indicator light is used to indicate whether the corresponding sensor is normal, when it is always green, it is normal, and when it flashes, it means a fault. The sensor indicator light includes the indicator lights of the intelligent infrared probe, thermocouple and thermal resistor; the icon indicator lights of each component correspond to each intelligent infrared probe, thermocouple and thermal resistor on the air preheater;

[0048] Step 105, click the human-machine interface fault query, real-time data, historical data and parameter setting buttons to enter the corresponding sub-pages, and click the return button to return to the previous interface; the fault query sub-page includes: displaying the fire alarm signal and the time of occurrence; displaying the specific fault information and the time of occurrence; clicking the "previous day" button to display the fault record of the previous day; clicking the "next day" button to display the fault record of the next day; the real-time data sub-page includes: displaying the temperature of each intelligent infrared probe; displaying the real-time temperature of each measuring point; displaying the real-time temperature of each thermocouple; displaying the temperature rise per second of each thermocouple; displaying the real-time temperature of each thermal resistor; displaying the temperature rise per second of each thermal resistor; clicking the corresponding measuring point button can display the real-time data of the measuring point, such as clicking the "1# infrared" button to display the "1# intelligent infrared" The real-time temperature value of the "external probe"; the historical data subpage, including: click the corresponding measuring point button to display the historical data of the measuring point, such as clicking the "1#" button to display the historical data of "No. 1 infrared probe"; click the "previous day" button to display the data of the previous day; click the "next day" button to display the data of the next day; the parameter setting subpage, including: infrared probe alarm threshold: an important parameter related to the infrared probe alarm, when its measured value reaches the preset value of the corresponding position, an alarm is triggered; infrared probe cooling alarm threshold: set the cooling wind detection threshold; thermocouple, thermal resistor alarm threshold: an important parameter related to the thermocouple, thermal resistor alarm, when the measured value is greater than this parameter, an alarm is triggered; thermocouple, thermal resistor temperature rise alarm threshold: when the second temperature rise of the thermocouple, thermal resistor measured value reaches this parameter, an alarm is triggered;

[0049] Step 106, when it is necessary to eliminate the fire alarm, click the "eliminate alarm" button on the human-machine interface to eliminate the alarm information. After confirming that the fire alarm has been eliminated and the air preheater is safe, be sure to manually press the "eliminate alarm" button for 5 seconds to reset the alarm status, otherwise it will affect the next alarm.

[0050] A preheater hot spot detection system, comprising:

[0051] Temperature sampling and transmission system 201; collecting air preheater rotor temperature field signals, collecting air preheater rotor temperature field signals through intelligent infrared probes and thermocouples, thermal resistors, wherein the temperature signal sampling of the thermocouples and thermal resistors is completed through PLC, the sampling of the temperature signal of the intelligent infrared probe and the transmission of data, the sampling of the temperature signal of the intelligent infrared probe and the transmission of data are completed through the CPU chip inside the intelligent infrared probe; the intelligent infrared probe is connected to the PLC through the Modbus bus, and the data of the temperature signal sampling is transmitted to the PLC;

[0052] Temperature signal processing and transmission system 202; fire alarm output dry node, fault detection, fire alarm output dry node, fault detection is completed through PLC switch module; PLC is connected to DCS system through communication interface via TCP / IP Modbus bus embedded touch screen, and system status, system fault alarm and fire alarm information are transmitted to embedded touch screen for display through PLC; intelligent infrared probe is plug-in infrared probe HSDS-40 / T, thermocouple is HSDS-40 / R, thermal resistor is HSDS-40 / Z, HSDS-40 system is packaged and shipped by components;

[0053] Alarm display system 203; displays system status, system fault alarm and fire alarm information, and the system status, system fault alarm and fire alarm are displayed through the embedded touch screen.

[0054] PLC is connected to the embedded touch screen via TCP / IPMobus bus. PLC is connected to the DCS system via the communication interface. The system status, system fault alarm and fire alarm information are transmitted to the embedded touch screen for display through PLC.

[0055] The intelligent infrared probe is composed of a lens 11, a connecting pipe 12, a welding seat 13, a valve 15 and a circuit element 16 which are connected in sequence, and an air inlet 14 is provided on the side wall of the welding seat 13 near the valve 15. The intelligent infrared probe also includes a dust cleaning structure and a lens 11 protection structure. The intelligent infrared probe cleans dust on the lens 11 through the dust cleaning structure, and compressed air enters the connecting pipe 12 through the air inlet 14 to remove sediment and fly ash on the surface of the lens 11, and at the same time, part of the circuit element 16 can be cooled; the purge air (clean air) pressure>0.5Mpa; the purge air flow rate is 4m3 / h; the lens 11 protection structure can be optionally a lens film.

[0056] Data processing is completed by PLC, which mainly realizes data transmission, alarm calculation, logical operation and data storage.

[0057] The data transmission of the intelligent infrared probe is realized through the RS485 serial port, and the data transmission between the intelligent infrared probe and the touch screen is realized through the Ethernet port. Through these interfaces, the PLC can obtain the data required by the system. With these data, the controller can perform alarm calculations, logical operations and data storage;

[0058] Alarm calculation: First, obtain the temperature signal of each measuring point from the Modbus bus, then input the temperature signal of each measuring point into the compiled "intelligent fire judgment model" to judge whether there is a hot spot in the air preheater, and finally transmit the judgment result to the touch screen and DCS system;

[0059] Logical operation: The logical operation of this system includes two parts: protective cover control and fault judgment;

[0060] Data storage: The purpose of data storage is to facilitate query, and its contents include storage of maximum value of measuring points, storage of average value of measuring points, storage of fault information and storage of fire alarm records.

[0061] The alarm mechanism of the air preheater hot spot detection system is to comprehensively judge the values ​​of all temperature measuring points installed on each preheater. The final alarm is a comprehensive alarm. The alarm decision method is simply to comprehensively consider the temperature of thermocouples, thermal resistors and infrared probes, temperature changes, and temperature change trends. It is also necessary to consider factors such as the acquisition of effective temperature when a certain measuring point fails, and use evidence theory to make alarm decisions.

[0062] High reliability. All measuring points are external structures, which can be maintained and replaced online. The system is simple and reliable. The temperature measuring infrared probe of the traditional analog circuit is changed to a digital intelligent infrared probe, which improves the detection accuracy and greatly extends the life of the sensor. The cooling system is changed from the water cooling device of HSDS-30 to the air cooling device, and the whole cooling system is simpler and more reliable.

[0063] High compactness. The bus communication structure is used to replace the traditional hard wiring structure, which greatly reduces the number of connection terminals and improves reliability; the reliable PLC control device and compact embedded touch screen make the system more concise and greatly save costs.

[0064] Easy to maintain. The system's operating status and fault alarms are provided to the user's DCS system in a standard bus manner; in addition, the system's built-in human-machine interface can also well reflect the system's operating status and fault alarms; infrared probe components and thermocouples and thermal resistance temperature measuring elements can be easily and quickly replaced online; the new system changes from the original centralized control of the two air preheaters to independent control, and the hot spot detection systems of the two air preheaters do not affect each other, making the system easier to maintain.

[0065] Real-time hotspot detection: Use plug-in multi-point detection instead of mobile dual-point detection to improve the real-time nature of fire warning.

[0066] Normal startup, operation and shutdown of the system

[0067] Normal startup of the system Under the condition that the equipment provided by the on-site user has been installed and the system settings have been completed, before the air preheater is put into operation, the operator should follow the following steps:

[0068] 1. Power on the local control box, and the system automatically enters the detection state. The system power supply is AC220V, 1KVA AC power supply;

[0069] 2. Check whether the cooling air system is normal.

[0070] Normal operation of the system

[0071] Before the boiler is officially put into operation, it is a high-risk period for fire. During the startup process, when good combustion conditions have not yet been established, the incompletely burned fuel enters the preheater from the burner and accumulates on the surface of the heat storage element. When the temperature of the heat storage element rises to a certain level, the deposited fuel will burn. Therefore, before the boiler is put into operation, the air preheater hot spot detection system must be put into operation first.

[0072] Recommended measures for operation and maintenance of air preheater

[0073] 1. Keep the soot blower in good condition and blow soot to the air preheater regularly (once per shift in principle). Pay special attention to strengthening soot blowing when the boiler is started, stopped or running at low load to keep the heat exchange surface of the air preheater clean;

[0074] 2. When the boiler is shut down after a long period of low-load operation, the deposition of combustibles on the heat exchange surface of the air preheater should be checked immediately, and the heat exchange surface should be cleaned if necessary;

[0075] 3. Strengthen boiler combustion management to ensure good boiler combustion under various working conditions. Prevent oil guns and pulverized coal burners from running with defects, and try to avoid long-term low-load operation of the boiler;

[0076] 4. The hot spot detection equipment of the air preheater must be put into normal operation, and special attention should be paid to monitoring the temperature of the flue gas and air. Abnormal temperature rise should be regarded as the possibility of re-combustion in the air preheater, and it is necessary to immediately observe and judge on site;

[0077] 5. The air preheater is in a dangerous period of re-combustion within 24 hours after the shutdown. The smoke and wind damper doors at the inlet and outlet of the air preheater should be closed and the supply and exhaust fans should be stopped in time. During this period, the air preheater should be kept running and closely monitored;

[0078] 6. The air preheater fire protection system should be inspected and maintained regularly to ensure that it can be put into normal use at any time.

[0079] Recommended control methods and fire-fighting measures after air preheater reburning accident

[0080] When the flue gas temperature and wind temperature at the air preheater outlet rise abnormally (note: when reburning occurs in an operating air preheater, the flue gas negative pressure fluctuates violently) or when this detection device sounds an alarm, it should be considered that reburning may have occurred in the air preheater. Before extinguishing the fire, the possibility of false alarm by this detection system should be ruled out. Carefully check and find out any signs of reburning in the air preheater (such as: sparks seen in the sight glass, black smoke coming out of the chimney, operation of the flue explosion-proof door, etc.). At the same time, special attention should be paid to the fact that the signs of reburning in the air preheater in the early stage may not be too obvious.

[0081] Once it is confirmed that secondary combustion has occurred in the air preheater, the following measures should be taken immediately to control and extinguish the fire:

[0082] 1. Immediately stop the operation of the boiler (if the boiler is in operation), and stop all the supply and exhaust fans, primary fans, and fire inspection cooling fans;

[0083] 2. Tightly close the smoke and air inlet and outlet damper doors of the air preheater where reburning has occurred;

[0084] 3. Keep the air preheater running and urgently lift the adjusting fan plate to the highest position to prevent the air preheater from getting stuck;

[0085] 4. Open the drainage valves on the flue gas and air sides at the bottom of the air preheater;

[0086] 5. If the degree of reburning is relatively light, use a steam fire extinguishing device to extinguish the fire. If the fire is still out of control, immediately use fire water to extinguish the fire until the flames are completely extinguished and the rotor is completely cooled;

[0087] 6. If the air preheater reburning is already serious when it is discovered, fire water should be used immediately to extinguish the fire. Do not blindly emphasize the use of steam to extinguish the fire. This can reduce the deformation of the rotor, otherwise the accident will be further expanded;

[0088] 7. When the air preheater can continue to operate after reburning, a fixed cleaning device should be used to extinguish the fire. Once the air preheater is stuck, a ring fire hose or a fire nozzle installed on the top of each compartment should be used to extinguish the fire;

[0089] 8. Check whether the drainage pipes on the smoke side and air side of the air preheater bottom are discharged normally, otherwise they should be cleared immediately;

[0090] 9. While extinguishing the fire in the air preheater where secondary combustion occurs, the other air preheater should be closely monitored to see if secondary combustion occurs.

[0091] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting hot spots in a preheater, characterized in that: include: Obtain the temperature signals of each measuring point on the air preheater, input the temperature signals of each measuring point into the "intelligent fire judgment model", judge whether there is a hot spot in the air preheater, and finally transmit the judgment result to the embedded touch screen and DCS system; Entering the human-machine interface through the internal software of the embedded touch screen; The embedded touch screen uses the color and status of the signal indicator light on the human-machine interface to issue a fire alarm; Determine the fire situation and equipment status by the color and status of the signal indicator light; Click the buttons for fault query, real-time data, historical data and parameter setting on the human-machine interface to enter the corresponding sub-pages, and click the return button to return to the previous interface; When it is necessary to eliminate the fire alarm, click the alarm elimination button on the human-machine interface to eliminate the alarm information.

2. A preheater hot spot detection method according to claim 1, characterized in that: The signal indicator lights include: a fire alarm indicator light, an over-temperature warning light, a system fault indicator light, a cooling fault indicator light, a sensor indicator light and each component icon indicator light.

3. A preheater hot spot detection method according to claim 1, characterized in that: The color and status of the signal light indicator include solid green and red and green flashing alternately.

4. A preheater hot spot detection method according to claim 2, characterized in that: When the fire alarm indicator light flashes red and green at intervals, it indicates a fire has occurred; when it is always green, it indicates no fire has occurred; when the over-temperature warning light flashes red and green at intervals, it indicates that the temperature exceeds the over-temperature warning threshold; when it is always green, it indicates that the temperature is normal; when the system fault indicator light flashes red and green at intervals, it indicates a fault in the probe or thermocouple or thermistor; when it is always green, it indicates that the probe and the thermocouple or thermistor are working normally; when the cooling fault indicator light is always green, the cooling air is normal; when it flashes red and green at intervals, it indicates a cooling air fault; the sensor indicator light is used to indicate whether the corresponding sensor is normal; when it is always green, it indicates normal; and when it flashes, it indicates a fault.

5. A preheater hot spot detection method according to claim 2, characterized in that: The sensor indicator lights include indicator lights of intelligent infrared probes, thermocouples and thermal resistors; the component icon indicator lights correspond to the intelligent infrared probes, thermocouples and thermal resistors on the air preheater.

6. A preheater hot spot detection method according to claim 1, characterized in that: The fault query subpage includes: displaying the fire alarm signal and occurrence time; displaying specific fault information and occurrence time; clicking the "previous day" button to display the fault record of the previous day; clicking the "next day" button to display the fault record of the next day; The real-time data subpage includes: displaying the temperature of each intelligent infrared probe; displaying the real-time temperature of each thermocouple; displaying the temperature rise per second of each thermocouple; displaying the real-time temperature of each thermal resistor; displaying the temperature rise per second of each thermal resistor; clicking the corresponding measuring point button can display the real-time data of the measuring point, such as clicking the "1# infrared" button, the real-time temperature value of "No. 1 intelligent infrared probe" is displayed; The historical data subpage includes: clicking the corresponding measuring point button to display the historical data of the measuring point, such as clicking the "1#" button to display the historical data of "No. 1 infrared probe"; clicking the "previous day" button to display the data of the previous day; clicking the "next day" button to display the data of the next day; The parameter setting sub-page includes: Infrared probe alarm threshold: It is an important parameter related to the infrared probe alarm. When its measured value reaches the preset value at the corresponding position, an alarm is triggered. Infrared probe cooling alarm threshold: set the cooling air detection threshold; Thermocouple and thermal resistor alarm threshold: It is an important parameter related to the alarm of thermocouple and thermal resistor. When the measured value is greater than this parameter, an alarm will be triggered. Thermocouple and thermal resistor temperature rise alarm threshold: When the temperature rise per second of the thermocouple or thermal resistor measurement value reaches this parameter, an alarm will be triggered.

7. A preheater hot spot detection system, characterized in that: include: Temperature sampling and transmission system; collecting the temperature field signal of the air preheater rotor, the collecting of the temperature field signal of the air preheater rotor is completed by an intelligent infrared probe, a thermocouple and a thermal resistor, wherein the temperature signal sampling of the thermocouple and the thermal resistor is completed by a PLC, the sampling of the temperature signal of the intelligent infrared probe and the transmission of the data are completed by the CPU chip inside the intelligent infrared probe; the intelligent infrared probe is connected to the PLC via a Modbus bus, and the data of the temperature signal sampling is transmitted to the PLC; Temperature signal processing and transmission system; fire alarm output dry node, fault detection, the fire alarm output dry node, fault detection is completed through the PLC switch module; the PLC is connected to the DCS system through the TCP / IP Modbus bus embedded touch screen, the PLC is connected to the DCS system through the communication interface, and the system status, system fault alarm and fire alarm information are transmitted to the embedded touch screen for display through the PLC; Alarm display system; displays system status, system fault alarm and fire alarm information, and the system status, system fault alarm and fire alarm are displayed through an embedded touch screen.

8. A preheater hot spot detection system according to claim 7, characterized in that: The intelligent infrared probe comprises: a lens, a connecting pipe, an air inlet, a valve and a circuit element.

9. A preheater hot spot detection system according to claim 7, characterized in that: The intelligent infrared probe converter adopts digital signal processing, and the intelligent infrared probe data is output in the form of Modbus bus.

10. A preheater hot spot detection system according to claim 7, characterized in that: The intelligent infrared probe also includes dust cleaning and lens protection, and the intelligent infrared probe dust cleaning is used to clean the dust on the lens.

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