A flame detection system and method of detection
By equipping the coal mill with multiple flame monitoring devices and improving the anti-peeping circuit design, the problem of accidental tripping of the coal mill was solved, the system reliability and safety were improved, and the economic cost was reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NINGXIA YINXING POWER GENERATION CO LTD
- Filing Date
- 2023-12-18
- Publication Date
- 2026-06-09
Smart Images
Figure CN117839846B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of flame detection, and more specifically, to a flame detection system and detection method. Background Technology
[0002] In related technologies, each coal mill is equipped with six flame detection monitoring devices, and each device has an anti-peeping circuit. The coal mill's flame detection no-flame protection uses a six-out-of-three logic. During the inspection, it was found that the power supply in the anti-peeping circuit of the flame detection system was not installed one-to-one as required by the design, and there was a series connection of the negative common line, such as... Figure 1 and Figure 2 As shown. Therefore, if a node fails, the coal mill will mistakenly send a no-flame signal and trip, which in severe cases will cause the boiler to shut down. Summary of the Invention
[0003] To overcome the above deficiencies, this application provides a flame detection system and detection method, which aims to improve the prevention of coal mill tripping due to abnormal flame detection, thus threatening the safe and stable operation of the unit.
[0004] Firstly, this application provides a flame detection system, in which each coal mill is equipped with multiple flame monitoring devices. The flame monitoring devices include a DCS node unit and control cabinet cards. The DCS node unit has an A-channel power supply and a B-channel power supply, and the DC 0V negative lines of the A-channel power supply and the B-channel power supply are respectively led to the wiring terminals of the A2 and A1 cards of the control cabinet cards. All other cards are connected in series, thereby forming an anti-peeping fire circuit. The DC 0V negative lines of the A-channel power supply and the B-channel power supply are each led out with a set of wiring connected to the D4 and D5 flame detection cards respectively, forming a redundant configuration. The DC 24V negative lines of the D4 and D5 power supplies are connected to form a loop.
[0005] Preferably, the control cabinet cards are arranged in a 5*8 matrix design, wherein each row has the following cards arranged from left to right:
[0006] The first row contains D1, D2, D3, D4, D5, D6, E1, and E2.
[0007] The second line contains E3, E4, E5, E6, F1, F2, F3, and F4.
[0008] The third line contains C5, C6, ..., F5, and F6.
[0009] Fourth row, B3, B4, B5, B6, C1, C2, C3, C4;
[0010] The fifth row contains A1, A2, A3, A4, A5, A6, B1, and B2.
[0011] Preferably, the flame monitoring device further includes a flame detector probe, and each card in the control cabinet is a flame detector amplifier, with the output port of the flame detector probe electrically connected to the corresponding card.
[0012] In this embodiment, the flame detector amplifier is used in conjunction with the infrared flame detector probe to detect the presence or absence of flame in the combustion chamber of a multi-burner. The flame detector amplifier has the best discrimination capability because it can accurately distinguish the pulse frequency generated by the flame detector. This discrimination capability is achieved through special flame signal processing and allows the user to set independent threshold values for flame presence / absence.
[0013] Preferably, the flame monitoring device further includes a DSC control unit, which is electrically connected to the DCS node unit.
[0014] In this embodiment, the DSC control unit is a distributed control system that achieves centralized control and management of the entire system by distributing controllers across different devices. The basic principle of DSC is to connect various controllers via a network to enable data transmission and sharing, thereby achieving system monitoring and control.
[0015] Preferably, the flame detection system further includes a coal mill fire extinguishing protection module for analyzing interference between adjacent flame detectors, the coal mill fire extinguishing protection module being electrically connected to the DSC control unit in the flame monitoring device.
[0016] Preferably, the coal mill fire extinguishing protection module negates the fire detection signals of #1, #2, #3, #4, #5, and #6 and then ORs them with the corresponding fire detection fault signals for 20 seconds to determine that the corresponding fire detector has no fire.
[0017] In this embodiment, the coal mill fire extinguishing protection module primarily utilizes steam as an inert medium. The greatest advantage of using steam is its large allowable injection volume, ensuring continuous removal of volatiles. Another important advantage is that after a trip of the coal mill or raw coal feeder, combustible materials inside the mill can be quickly reintroduced into the furnace, allowing the mill to be safely restarted after venting. Furthermore, steam is non-toxic and inexpensive, resulting in minimal thermal shock to the mill casing.
[0018] Preferably, the coal mill fire extinguishing protection module performs a "three out of six" selection of the #1, #2, #3, #4, #5, and #6 no-fire signals and ensures that at least one pair of burners that trigger the no-fire signal are non-adjacent burners before triggering the fire detection loss signal to trip the coal mill.
[0019] Preferably, the flame monitoring device further includes a network unit, which is electrically connected to the DSC control unit, and the DSC control unit transmits the flame detection signal to the terminal device in real time through the network unit.
[0020] In this embodiment, the DSC system connects various controllers via a network to achieve data transmission and sharing. Network communication is the foundation of the DSC system, and it can use Ethernet, CAN bus, or Modbus communication protocols to ensure reliable data transmission and real-time performance.
[0021] Preferably, the flame detection system further includes a trip module, which is electrically connected to the DSC control unit.
[0022] In this embodiment, the trip module refers to a measure by which the protection device automatically cuts off the power supply when an overload or short-circuit fault occurs in the circuit. The principle of the trip module is based on two mechanisms: thermal protection and electromagnetic protection.
[0023] Secondly, a detection method for a flame detection system includes the aforementioned flame detection system and the following steps:
[0024] S1. Design a power circuit to prevent eavesdropping and form a double redundant ring structure;
[0025] S2. Design the fire detection protection logic, taking into account the interference from adjacent fire detectors.
[0026] Beneficial effects:
[0027] 1. By combining the improved anti-peeping fire circuit with the coal mill fire extinguishing protection module, specifically by redesigning the anti-peeping fire power circuit to form a dual-redundant ring structure; and by redesigning the fire detection protection logic to consider interference from adjacent fire detectors, the problem of preventing the coal mill from tripping abnormally due to no fire detection is addressed, thus threatening the safe and stable operation of the unit. This improves the reliability of the fire detection system, reduces maintenance cycles, and lowers the workload of personnel.
[0028] 2. Expected economic costs to decrease. Attached Figure Description
[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0030] Figure 1 This is a circuit diagram of a conventional privacy fire circuit in the background art of this application;
[0031] Figure 2 The circuit diagram is for the existing conventional fire extinguishing protection module of the coal mill in this application;
[0032] Figure 3 This is a circuit diagram of the anti-peeping fire circuit of the improved flame detection system of this application;
[0033] Figure 4 This is a circuit diagram of the coal mill fire extinguishing protection module of the improved flame detection system of this application;
[0034] Figure 5 This is a block diagram of the flame detection system of this application. Detailed Implementation
[0035] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.
[0036] Please see Figure 1 Each DCS node is connected to the terminals of card A2 and card A1 by the DC0V negative lines of power supply A and B respectively. All terminals are connected in series. When a break occurs at a certain point, it will directly trigger the anti-spying function of all cards below the contact point, causing some coal mills to trip.
[0037] Please see Figure 3 and Figure 5 This application provides a flame detection system. Each coal mill is equipped with multiple flame monitoring devices. Each flame monitoring device includes a DCS node unit and control cabinet cards. The DCS node unit has power supply A and power supply B. The DC 0V negative lines of power supply A and B are respectively led to the terminals of cards A2 and A1 in the control cabinet. All other cards are connected in series, thus forming an anti-spying circuit. The DC 0V negative lines of power supply A and B are each led out with a set of wiring connected to flame detection cards D4 and D5 respectively, forming a redundant configuration. The DC 24V negative lines of power supply D4 and D5 are connected to form a loop circuit, and all other cards are connected in series. This ultimately forms a double-redundant loop circuit, which helps prevent the series connection of negative lines in the anti-spying function power supply circuit from causing some flame detectors to fail to detect flames.
[0038] The control cabinet cards are arranged in a 5x8 matrix design, with each row containing, from left to right:
[0039] The first row contains D1, D2, D3, D4, D5, D6, E1, and E2.
[0040] The second line contains E3, E4, E5, E6, F1, F2, F3, and F4.
[0041] The third line contains C5, C6, ..., F5, and F6.
[0042] Fourth row, B3, B4, B5, B6, C1, C2, C3, C4;
[0043] The fifth row contains A1, A2, A3, A4, A5, A6, B1, and B2.
[0044] Please see Figure 5 The flame monitoring device also includes a flame detector probe. Each card in the control cabinet is a flame detector amplifier, and the output port of the flame detector probe is electrically connected to the corresponding card.
[0045] Fire detectors are mainly divided into two types: photoelectric and thermal. Photoelectric fire detectors detect the presence of a fire by utilizing the light radiation of a flame. Their principle is to use a photodiode to receive the light radiation signal from the flame, then convert the signal into an electrical signal, process it through a circuit, and finally trigger a fire alarm. Thermal fire detectors, on the other hand, detect the presence of a fire by utilizing the heat radiation of a flame. Their principle is to use a thermistor or thermocouple to sense the heat radiation signal from the flame, then convert the signal into an electrical signal, process it through a circuit, and finally trigger a fire alarm.
[0046] The working principle of a fire detector is based on the characteristics of a flame. A flame is a mixture of gases and particles produced by combustion, and its thermal and light radiation are important indicators for fire detection. When a flame burns, it generates a large amount of thermal and light radiation. These radiation signals can be sensed by the fire detector and converted into electrical signals, thereby triggering a fire alarm.
[0047] In addition, the fire detection probe is specifically an infrared fire detection probe.
[0048] The flame detector amplifier is used in conjunction with an infrared flame detector probe to detect the presence or absence of flames in the combustion chamber of a multi-burner. The flame detector amplifier has the best discrimination capability because it can accurately distinguish the pulse frequency generated by the flame probe. This discrimination capability is achieved through special flame signal processing and allows users to set independent threshold values for flame presence / absence.
[0049] It should also be noted that a converter is provided between the flame detector probe and the flame detector amplifier. A converter is a device that can convert one form of energy into another. The working principle of the converter is to achieve energy conversion through energy input and output. The working principle of the converter mainly involves two aspects: input energy conversion and output energy conversion. Input energy conversion refers to converting one form of energy into another form of energy and inputting it into the converter through the input terminal. Output energy conversion refers to converting the energy obtained inside the converter into another form of energy and outputting it through the output terminal. In the converter, input energy conversion is usually achieved through sensors or input circuits. Sensors can convert various forms of energy into electrical signals and input them into the converter through the input circuit. The input circuit converts electrical energy into other forms of energy and inputs them into the converter. For example, in a power system, the input circuit usually converts alternating current into direct current and inputs it into a DC-DC converter. Thus, in this application, a converter is used to conveniently convert analog signals into electrical signals.
[0050] The flame monitoring device also includes a DSC control unit, which is electrically connected to the DCS node unit. After receiving the flame detection signal, the DCS node unit controls subsequent operations through the DSC control unit. The DSC control unit is a distributed control system that achieves centralized control and management of the entire system by distributing controllers across different devices. The basic principle of DSC is to connect various controllers through a network to achieve data transmission and sharing, thereby realizing system monitoring and control. Specifically, the basic principle of the DSC control unit mainly includes the following aspects: 1. Network Communication: The DSC system connects various controllers through a network to achieve data transmission and sharing. Network communication is the foundation of the DSC system, and it can use Ethernet, CAN bus, or Modbus communication protocols to ensure reliable data transmission and real-time performance. 2. Controller: The controller in the DSC system is the core component for system control. The controller can be a PLC (Programmable Logic Controller), DCS (Distributed Control System), or PAC (Programmable Automation Controller). The controller is responsible for receiving signals from sensors, executing control algorithms, and outputting control signals to achieve real-time monitoring and control of the system. 3. Data Acquisition: The DSC system acquires various signals from the system through sensors, such as temperature, pressure, and flow rate. The sensor collects data, converts it into electrical signals via a converter, and inputs these signals to the controller through an analog or digital input module. 4. Data Processing: After receiving the data from the sensor, the controller processes and calculates the data. Based on a preset control algorithm, the controller processes the collected data, derives the control result, and outputs a control signal. 5. Control Output: The controller generates control signals based on the processed data and outputs them to the actuators through an analog or digital output module. Actuators can be electric valves, motors, cylinders, etc., used to control and regulate the system. 6. Monitoring and Management: The DSC system can monitor and manage the system's operating status in real time through a Human-Machine Interface (HMI). The HMI provides a graphical interface that displays system parameters, status, and alarm information, allowing users to remotely monitor and operate the system.
[0051] Please see Figure 2 The coal mill fire extinguishing protection module takes the flame detection signals from #1, #2, #3, #4, #5, and #6, negates them, then ORs them with the corresponding flame detection fault signal, and delays for 5 seconds to determine if the corresponding flame detector is not burning. If any flame detector is not burning, the module takes three out of six signals and triggers the protection. During abnormal combustion, interference can occur between adjacent burners, causing the coal mill to trip due to flame detection abnormalities.
[0052] Please see Figure 4 and Figure 5The flame detection system also includes a coal mill fire extinguishing protection module for analyzing interference from adjacent flame detectors. The coal mill fire extinguishing protection module is electrically connected to the DSC control unit in the flame monitoring device.
[0053] The coal mill fire suppression protection module takes the NOT of the fire detection signals from fire detectors #1, #2, #3, #4, #5, and #6, then ORs them with the corresponding fire detector fault signal, and delays for 20 seconds to determine if the corresponding fire detector is not firing. Here, #1, #2, #3, #4, #5, and #6 refer to... Figure 2 and Figure 4 The burner flame detector in line 6 has a flame signal or a burner flame detector fault signal.
[0054] The coal mill fire suppression protection module uses a "three-out-of-six" selection method from the no-flame signals (#1, #2, #3, #4, #5, #6) to ensure that at least one pair of burners triggering the no-flame signal are not adjacent. Only when this condition is met will the coal mill trip due to a loss of flame detector signal. (There are 16 possible selection methods: 124, 125, 126, 134, 135, 136, 145, 146, 156, 235, 236, 245, 246, 256, 346, 356). This helps to address the issue of interference from adjacent flame detectors not being considered in the "three-out-of-six" function of the coal mill protection logic.
[0055] In this embodiment, the coal mill fire extinguishing protection module primarily utilizes steam as an inert medium. The greatest advantage of using steam is its large allowable injection volume, ensuring continuous removal of volatiles. Another important advantage is that after a trip of the coal mill or raw coal feeder, combustible materials inside the mill can be quickly reintroduced into the furnace, allowing the mill to be safely restarted after venting. Furthermore, steam is non-toxic and inexpensive, resulting in minimal thermal shock to the mill casing.
[0056] The flame monitoring device also includes a network unit electrically connected to the DSC control unit. The DSC control unit transmits the flame detection signal to the terminal device in real time through the network unit, facilitating remote monitoring of the flame detection process. The DSC system connects various controllers via a network to achieve data transmission and sharing. Network communication is fundamental to the DSC system; it can employ Ethernet, CAN bus, or Modbus communication protocols to ensure reliable data transmission and real-time performance.
[0057] The flame detection system also includes a trip module electrically connected to the DSC control unit. An improved anti-peeping power supply circuit and redesigned flame detection protection logic facilitate accurate control of the coal mill tripping operation using the DSC control unit. The trip module is a measure whereby the protection device automatically cuts off the power supply when an overload or short-circuit fault occurs in the circuit. The principle of the trip module is based on two mechanisms: thermal protection and electromagnetic protection. First, the thermal protection mechanism: When there is an overload or short circuit, a large amount of heat is generated inside the electrical components. If this heat cannot be dissipated in time, the component temperature will rise. When the component temperature exceeds its maximum allowable temperature, thermal damage will occur, and even a fire may occur. Therefore, a device called a "thermal relay" is added to the circuit, which controls the switch action by sensing changes in component temperature. When the component temperature rises to a certain level, the thermal relay will automatically trip and cut off the power supply. Second, the electromagnetic protection mechanism: In some cases, such as in coil relays and AC contactors, a device called an "electromagnet" is also used to achieve the tripping function. When the coil is energized, a strong magnetic field is generated on the iron core, causing the iron plates on the core to bend or displace, thereby opening or closing the contactor contacts. When an overload or short circuit occurs in the circuit, the current increases, and the current in the coil also increases accordingly. Due to the relationship between current and magnetic field, when the current in the coil reaches a certain level, it will cause the iron plates on the iron core to bend or displace to a certain angle, thus causing the contactor to trip and cut off the power supply.
[0058] In summary, tripping is a crucial circuit protection measure that effectively prevents equipment damage and fires caused by overload or short-circuit faults. In practical applications, we need to select different types and rated tripping devices based on different situations, and regularly inspect and maintain these devices to ensure their proper functioning.
[0059] This application also provides a detection method for a flame detection system, including the above-mentioned flame detection system, and the following steps:
[0060] S1. Design a power circuit to prevent eavesdropping and form a double redundant ring structure;
[0061] S2. Design the fire detection protection logic, taking into account the interference from adjacent fire detectors.
[0062] At the same time, economic costs are expected to decrease:
[0063] Specifically, this can reduce the number of coal mill trips due to abnormal flame detectors by at least 6 times per year. Each trip affects a load of 100,000 KW, and each start-up and shutdown of the coal mill takes about 0.5 hours, resulting in a power loss of 6 × 100,000 × 0.5 = 300,000 KWh. With an electricity price of 0.25 yuan per kWh, this can save 300,000 KWh × 0.25 = 75,000 yuan per year.
[0064] This can reduce the number of times the unit trips due to circuit failures in the coal mill flame detector cabinet by at least one per year. Each unit trip will result in the power grid awarding the company 660 points in its performance evaluation, with each point worth 1,000 yuan, totaling 660 x 1,000 = 660,000 yuan.
[0065] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A flame detection system, wherein each coal mill is equipped with multiple flame monitoring devices, the flame monitoring device comprising a DCS node unit, a DSC control unit, control cabinet cards, and a coal mill fire extinguishing protection module for analyzing interference between adjacent flame detectors, the DCS node unit having an A-channel power supply and a B-channel power supply, wherein the A-channel power supply (DC0V-) is led to the A2 terminal of the control cabinet card, and the B-channel power supply (DC0V-) is led to the A1 terminal of the control cabinet card, and all other cards are connected in series, thereby forming an anti-peeping fire circuit, characterized in that… The DC0V- of power supply A is connected to the D5 flame detection card via another set of wiring, and the DC0V- of power supply B is connected to the D4 flame detection card via another set of wiring, forming a dual redundancy configuration. The DC24V- of the D4 flame detection card is directly connected to the DC24V- of the D5 flame detection card, forming a loop. The coal mill fire extinguishing protection module is electrically connected to the DSC control unit in the flame monitoring device. The logic for determining if a flame is not detected by the coal mill fire extinguishing protection module is as follows: The flame detection signals #1, #2, #3, #4, #5, and #6 are NOT checked; then, they are ORed with the corresponding flame detection fault signal; finally, the result is evaluated using a 20-bit algorithm. After a delay of one second, the final determination is that the corresponding flame detector is not working. The coal mill fire extinguishing protection module will select three out of six flame-not working signals from #1, #2, #3, #4, #5, and #6 and ensure that at least one pair of burners that trigger the flame-not working signal are not adjacent burners. In this case, the coal mill will be tripped due to the loss of the flame detector signal.
2. The flame detection system according to claim 1, characterized in that, The control cabinet cards are arranged in a 5x8 matrix design, with each row containing, from left to right: The first row contains D1, D2, D3, D4, D5, D6, E1, and E2. The second line contains E3, E4, E5, E6, F1, F2, F3, and F4. The third line contains C5, C6, ..., F5, and F6. Fourth row, B3, B4, B5, B6, C1, C2, C3, C4; The fifth row contains A1, A2, A3, A4, A5, A6, B1, and B2.
3. The flame detection system according to claim 1, characterized in that, The flame monitoring device also includes a flame detector probe. Each card in the control cabinet is a flame detector amplifier, and the output port of the flame detector probe is electrically connected to the corresponding card.
4. The flame detection system according to claim 1, characterized in that, The DSC control unit is electrically connected to the DCS node unit.
5. A flame detection system according to claim 4, characterized in that, The flame monitoring device also includes a network unit, which is electrically connected to the DSC control unit. The DSC control unit transmits the flame detection signal to the terminal device in real time through the network unit.
6. A flame detection system according to claim 4, characterized in that, It also includes a trip module, which is electrically connected to the DSC control unit.
7. A detection method for a flame detection system, characterized in that, The flame detection system includes any one of claims 1-6, and the following steps: S1. Design a power circuit to prevent eavesdropping and form a dual-redundant ring structure; S2. Design the fire detection protection logic, taking into account the interference from adjacent fire detectors.