System and method for safety time monitoring and interlocking driving of combustor

Abstract

The invention relates to the technical field of combustor safety control, in particular to a system and method for combustor safety time monitoring and interlocking driving. The system comprises a signal processing unit, a core control unit, a man-machine interaction unit and an execution driving unit which are electrically connected in sequence, according to the invention, a 24V control signal of an industrial field is successfully and safely accessed to a 3.3 V microcontroller system through the optoelectronic isolation and level conversion input circuit; an output circuit is driven by high-efficiency power, so that the microcontroller can reliably drive an industrial executive component; meanwhile, input and output adopt a photoelectric isolation technology, damage of field electromagnetic interference to the core control unit is effectively prevented, system instability caused by a ground loop is also avoided, and the durability of the driving module in a severe industrial environment is enhanced due to the design of a protection circuit at an output end.

Description

Technical Field

[0001] This invention relates to the field of burner safety control technology, specifically to a system and method for burner safety time monitoring and interlocking drive. Background Technology

[0002] As an indispensable heat energy supply device in basic industries such as metallurgy, chemical industry, and power generation, the safety of burner operation directly affects the stability of production equipment and the safety of personnel and property. During the start-up, operation, and shutdown of the burner, there are a series of critical safety time parameters, such as pre-purge time, ignition safety time, and main fire safety time. These parameters ensure that no gaseous material accumulates in the furnace before ignition and that fuel is promptly cut off in case of ignition failure, serving as a core guarantee against catastrophic accidents such as deflagration and explosion. Therefore, accurate monitoring of these safety times and rapid execution of interlocking protection in case of abnormalities are crucial aspects of the burner control system.

[0003] Currently, the common practice for monitoring and testing burner safety time in industrial settings is to use a dedicated testing instrument built around a programmable logic controller (PLC). This system acquires status signals from nodes such as the fan, igniter, and flame detector emitted by the burner control system through the PLC's digital input points, and uses the PLC's internal soft timer function for time measurement. The measured time results are then displayed on a host computer touchscreen or configuration interface. This technical approach is based on mature industrial control products and has a certain foundation in terms of logic control stability and environmental adaptability.

[0004] However, as industrial environments increasingly demand higher levels of debugging efficiency, testing accuracy, and equipment portability, the inherent technical limitations of this general-purpose PLC-based solution are becoming increasingly apparent. Its "sequential scanning, cyclic execution" working mechanism, and the modular architecture adopted to meet industrial interface specifications, reveal a series of insurmountable drawbacks when facing high-precision, miniaturized, specialized testing scenarios; specifically as follows: 1. Traditional burner safety time monitoring instruments use PLC as the main controller. Because the PLC uses a "sequential scanning" mechanism, it generates millisecond-level delays, and the PLC operates at a high frequency, resulting in low timing accuracy.

[0005] 2. Traditional burner safety time monitoring instruments use PLC as the main controller, which is large in size and inconvenient to carry.

[0006] 3. The burner emits a 24V signal, while the microcontroller typically emits 3.3V. Due to the mismatch in electrical characteristics, it is impossible to use a more precise and miniaturized microcontroller for timing and controlling the operation of components such as solenoid valves and relays in the burner control system.

[0007] Therefore, how to enable the microcontroller to input and output signals that match the electrical characteristics of the burner to solve the above problems is a problem that needs to be solved by those skilled in the art.

[0008] Therefore, this application proposes a system and method for burner safety time monitoring and interlocking drive. Summary of the Invention

[0009] To overcome the shortcomings of the prior art and solve the technical problems existing in the background art, the present invention proposes a system and method for burner safety time monitoring and interlocking drive.

[0010] This invention is achieved through the following technical solution: A system for burner safety time monitoring and interlocking drive includes a signal processing unit, a core control unit, a human-machine interaction unit and an execution drive unit connected in sequence. The signal processing unit receives external status signals from the burner, performs electrical isolation and noise filtering, and then outputs a standardized signal. The core control unit calculates safety time parameters based on standardized signals, compares them with preset thresholds, and then generates control commands. The core control unit uses a 32-bit microprocessor and has a built-in timer module configured in edge-triggered capture mode. It calculates the safety time parameter by detecting the transition interval of the standardized signal, and the timing resolution is not less than 1 microsecond. The safety time parameters include the pre-purge duration, ignition window time, main flame monitoring time, flameout response time, and post-purge duration. The core control unit has a built-in non-volatile memory to store the preset thresholds for each parameter. The range of pre-purge time is 5-180 seconds, the range of ignition window time is 1-10 seconds, the range of main flame monitoring time is 1-30 seconds, the range of flameout response time is 0.1-5 seconds, and the range of post-purge time is 5-180 seconds. The human-computer interaction unit displays safety time parameters and system status in real time; The drive unit converts control commands into action signals that can drive the burner actuators.

[0011] Preferably, the signal processing unit includes an overcurrent protection subunit, an electromagnetic isolation subunit, and a level adaptation subunit connected in sequence; The overcurrent protection subunit uses a fuse-type protection device connected in series at the signal input terminal; The electromagnetic isolation subunit uses an optocoupler as its core to achieve electrical isolation between external and internal circuits; The level adapter subunit converts 24V industrial signals into 3.3V logic signals.

[0012] Preferably, the signal processing unit further includes a noise suppression subunit, which is an RC low-pass filter circuit connected in series between the overcurrent protection subunit and the electromagnetic isolation subunit, and its cutoff frequency is not higher than 1kHz.

[0013] Preferably, the execution drive unit includes a signal amplification subunit, an isolation subunit, and a power output subunit; The signal amplification subunit amplifies the weak-level signal output by the core control unit using current. The isolation subunit blocks the electrical connection between the power circuit and the control circuit; The power output subunit outputs a drive signal of 24V / 2A or higher to the solenoid valve or relay of the burner.

[0014] Preferably, the execution drive unit further includes a back EMF absorption subunit, which is a freewheeling diode connected in parallel to the output terminal of the power output subunit, and is used to protect the power device from damage by reverse voltage of the inductive load.

[0015] A method applicable to the above-mentioned burner safety time monitoring and interlocking drive system includes the following steps: S1: Performs overcurrent protection, electromagnetic isolation, and level conversion on the acquired external status signals of the burner, and outputs standardized digital signals; S2: The safe time parameters during burner operation are calculated by detecting the state transition of the standardized digital signal through the timing module; S3: Compare the safety time parameter with the preset threshold, and generate an interlock control command when the parameter exceeds the threshold range; S4: After isolating and amplifying the interlock control command, it drives the burner actuator to achieve safety interlock.

[0016] Preferably, electromagnetic isolation in S1 is achieved through an optocoupler with an isolation withstand voltage of not less than 2500Vrms; level conversion converts the external 24V signal into a 3.3V signal compatible with the control module with a conversion delay of no more than 10 microseconds.

[0017] Preferably, the safe time calculation in S2 is specifically as follows: the time difference between the rising edge and the falling edge of the standardized digital signal is recorded by a timer, and the time parameter is calculated in combination with the timer's operating frequency, wherein the timer's operating frequency is not less than 72MHz.

[0018] Preferably, the isolation amplification in S4 includes two stages of processing: the first stage amplifies the control command current to 5-10mA through a transistor, and the second stage amplifies the signal to the power level required to drive the burner actuator through a power MOSFET.

[0019] Preferably, the system also includes a parameter configuration step: receiving a safe time threshold input by the user through a human-computer interaction interface, storing it in a non-volatile memory, and automatically loading the threshold as a comparison benchmark when the system is powered on.

[0020] The beneficial effects of this invention are: 1. This invention abandons the "sequential scanning" working method of PLC and adopts the hardware timer of microcontroller for direct input capture, improving the timing accuracy from the traditional millisecond level to the microsecond level, which greatly improves the accuracy and reliability of measurement. At the same time, the highly integrated microcontroller and peripheral circuits replace the bulky PLC module and its supporting expansion module, which greatly reduces the size and weight of the entire monitoring instrument, making it easier to carry and debug on site, and significantly reducing costs.

[0021] 2. This invention successfully and safely connects the 24V control signal from the industrial field to a 3.3V microcontroller system through opto-isolation and level conversion input circuits; through efficient power drive output circuits, the microcontroller can reliably drive industrial actuators; at the same time, both input and output adopt opto-isolation technology, which effectively prevents electromagnetic interference from the field from damaging the core control unit, and also avoids system instability caused by ground loops. The protection circuit design at the output end enhances the durability of the drive module in harsh industrial environments.

[0022] 3. This invention integrates high-precision timing, status display, safety interlock logic judgment, and powerful driving capability into a compact system, realizing the integration and specialization of burner safety time monitoring and interlock driving, thereby improving the overall performance and ease of use of the equipment. Attached Figure Description

[0023] Figure 1 This is a block diagram of the system structure of the present invention; Figure 2 This is a schematic diagram of the digital input circuit of the present invention; Figure 3 This is a schematic diagram of the digital output circuit of the present invention; Figure 4 This is a schematic diagram of the software system flow of the present invention. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The invention will now be further described with reference to the accompanying drawings and specific embodiments. The preferred embodiments and materials described herein are for illustrative purposes only.

[0026] Example 1: A system and method for burner safety time monitoring and interlocking drive, such as Figure 1 As shown, it includes: a microcontroller, an LCD display module, a digital input circuit, and a digital output circuit.

[0027] The microcontroller used is an STM32F103ZET6. Firstly, it is used to receive and process signals from digital input circuits; Secondly, it is used to control the on / off state of digital output circuits; Third, it is used to control the LCD screen to display the test results.

[0028] The LCD display module uses a 2.8-inch TFT-LCD color screen, and the controller is ILI9341. The module is connected to the microcontroller through a 4-wire SPI interface. The microcontroller sends instructions and display data to the LCD through the SPI protocol, and refreshes the display of parameters and their status such as pre-purge time and ignition safety time in real time.

[0029] The digital input circuit is responsible for receiving and processing various signals (24V digital signals) from the combustion control system to perform the burner's safe time monitoring operation.

[0030] The schematic diagram of the digital input circuit is as follows: Figure 2 As shown, its working mode is as follows: Signal Reception and Isolation: External digital signals are input through interface X01, with the 24V1 terminal connected to an external 24V power supply for isolation from internal circuitry. After passing through a current-limiting resistor, the signal drives the LED inside the optocoupler isolator (model EL357N). When the external voltage is 0V (low level), the LED illuminates; when the external voltage is 24V (high level), the LED is off. The filter capacitor removes most of the noise from the external signal, and the fuse protects other parts of the system in case of abnormal external signals, ensuring high reliability.

[0031] Level conversion: When the phototransistor on the other side of the optocoupler receives light, it conducts, pulling the potential of the microcontroller's I / O port (PA0) down to near 0V (low level); when the optocoupler is turned off, the PA0 port is pulled up to 3.3V (high level) through the pull-up resistor. In this way, isolation and conversion of the 24V signal to the 3.3V signal are achieved.

[0032] Status indication: A light-emitting diode is connected in series in the input circuit to visually indicate whether there is a signal input in that circuit.

[0033] The digital output circuit is responsible for cooperating with the burner control system to realize the burner's safety interlock mechanism, thereby ensuring the safe and stable operation of the burner. It needs to convert the 3.3V signal output by the microcontroller into a 24V signal so that it can normally control the operation of components such as solenoid valves and relays in the burner control system.

[0034] This system uses optocoupler isolation chips to isolate the microcontroller output signal from each load circuit, reducing interference between the control system and external circuits. The output optocoupler is EL357N, with a maximum switching frequency of 100kHz.

[0035] By comparing the advantages and disadvantages of various driving components, an NPN transistor was selected to form the power amplifier circuit to improve the circuit's driving capability and meet the control logic requirements of the solution. Furthermore, the transistor needs to meet the following conditions: (1) (2) The S8050 was selected as the preamp transistor.

[0036] Because the optocoupler has a small output current and insufficient driving capability, an IRF540 field-effect transistor is used for power amplification. The IRF540 is an N-channel field-effect transistor with a maximum power of 120W and strong driving capability, which can meet the application requirements of the safety interlocking mechanism. By driving the IRF540, the solenoid valve and relay are controlled, thereby ensuring the safe and stable operation of the burner control system.

[0037] The schematic diagram of the digital output circuit is as follows: Figure 3 As shown, when the PD10 port outputs a low level, the transistor S8050 and the photodiode inside the optocoupler are both in the off state. The fourth pin of the optocoupler is pulled up to 24V by a 1K resistor. At the same time, the field-effect transistor IRF540 is also in the off state. No current flows through the solenoid valve, and it does not perform any action.

[0038] When the PD10 port outputs a high level, the photodiode inside the optocoupler is turned on. The 24V power supply first passes through a 1K resistor and then through the phototransistor at the output of the optocoupler, making the VGS voltage of the field-effect transistor IRF540 greater than the turn-on voltage. At this time, the solenoid valve is turned on.

[0039] Furthermore, when the MOSFET is suddenly turned off, the coil will generate a high induced voltage. To protect the MOSFET from breakdown, this solution connects a 1N4007 diode in parallel across the MOSFET to mitigate transient energy. 0V2 is connected to external ground; to prevent interference between ground loops, this ground is isolated from the internal GND. When using this module, connect Y00 to one end of the load, and connect the other end of the load to a 24V power supply.

[0040] Example 2: like Figure 4 It can be seen that the program running in the microcontroller performs the following core steps: Step 1: System initialization; After the program powers on, it first configures peripherals such as the system clock, GPIO ports, timers, and SPI interface. In particular, it configures the GPIO port connected to the digital input as a pull-up input mode and initializes the timer used for input capture.

[0041] Step Two: Wait for signal input and high-precision timing; The program continuously monitors the status of the digital input ports. Taking the measurement of "pre-purge time" as an example: (1) When the fan start signal is detected (corresponding to the I / O port changing from high level to low level), the timer is started immediately and its count register is cleared.

[0042] (2) The timer counts freely in microseconds.

[0043] (3) When an ignition signal is detected (corresponding to a change in I / O port level), immediately capture the timer count value T at this time.

[0044] (4) Calculate the safety time parameter: pre-purge time = T × timer counting period. Since the counting period is 1 microsecond, the time value in the microsecond range can be obtained directly, and then converted to milliseconds or seconds for display as needed.

[0045] Step 3: Data display and logical judgment; The calculated time parameters are sent to the LCD display module in real time for updating. Simultaneously, this value is compared with a preset safety threshold.

[0046] Step 4: Interlocking control decision and output; If the time parameter exceeds the safety threshold, the microcontroller immediately sets the corresponding digital output port to a low level, forcibly closing the fuel solenoid valve and achieving a safety interlock shutdown.

[0047] Example 3: Using the 72MHz main frequency of the STM32, the timer can achieve microsecond-level timing resolution.

[0048] The digital input module can stably capture pulse signals with frequencies up to 200kHz.

[0049] The digital output module can drive loads with continuous current of several amperes per channel, fully meeting the needs of industrial solenoid valves.

[0050] Both inputs and outputs are opto-isolated to ensure that the core control system is not affected by field interference.

[0051] The LCD display interface refresh rate is no less than 1Hz to ensure real-time data display.

[0052] By employing a highly integrated MCU and standardized discrete components, it achieves a smaller size and lower cost compared to PLC systems.

[0053] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A system for monitoring and interlocking burner safety time, characterized in that, It includes a signal processing unit, a core control unit, a human-machine interface unit, and an execution drive unit that are connected in sequence. The signal processing unit receives external status signals from the burner, performs electrical isolation and noise filtering, and then outputs a standardized signal. The core control unit calculates safety time parameters based on standardized signals, compares them with preset thresholds, and then generates control commands. The human-computer interaction unit displays safety time parameters and system status in real time; The drive unit converts control commands into action signals that can drive the burner actuators.

2. The system for burner safety time monitoring and interlocking drive according to claim 1, characterized in that, The signal processing unit includes an overcurrent protection subunit, an electromagnetic isolation subunit, and a level adaptation subunit connected in sequence. The overcurrent protection subunit uses a fuse-type protection device connected in series at the signal input terminal; The electromagnetic isolation subunit uses an optocoupler as its core to achieve electrical isolation between external and internal circuits; The level adapter subunit converts 24V industrial signals into 3.3V logic signals.

3. The system for burner safety time monitoring and interlocking drive according to claim 2, characterized in that, The signal processing unit also includes a noise suppression subunit, which is an RC low-pass filter circuit connected in series between the overcurrent protection subunit and the electromagnetic isolation subunit, and its cutoff frequency is no higher than 1kHz.

4. The system for burner safety time monitoring and interlocking drive according to claim 1, characterized in that, The execution drive unit includes a signal amplification subunit, an isolation subunit, and a power output subunit; The signal amplification subunit amplifies the weak-level signal output by the core control unit using current. The isolation subunit blocks the electrical connection between the power circuit and the control circuit; The power output subunit outputs a drive signal of 24V / 2A or higher to the solenoid valve or relay of the burner.

5. A system for monitoring and interlocking burner safety time according to claim 4, characterized in that, The drive unit also includes a back EMF absorption subunit, which is a freewheeling diode connected in parallel to the output terminal of the power output subunit to protect the power devices from damage caused by inductive load reverse voltage.

6. A method applicable to the burner safety time monitoring and interlocking drive system as described in claims 1-5, characterized in that, Includes the following steps: S1: Performs overcurrent protection, electromagnetic isolation, and level conversion on the acquired external status signals of the burner, and outputs standardized digital signals; S2: The safe time parameters during burner operation are calculated by detecting the state transition of the standardized digital signal through the timing module; S3: Compare the safety time parameter with the preset threshold, and generate an interlock control command when the parameter exceeds the threshold range; S4: After isolating and amplifying the interlock control command, it drives the burner actuator to achieve safety interlock.

7. The method for a burner safety time monitoring and interlocking drive system according to claim 6, characterized in that, Electromagnetic isolation in S1 is achieved through an optocoupler with an isolation withstand voltage of not less than 2500Vrms; level conversion converts the external 24V signal into a 3.3V signal that is compatible with the control module, with a conversion delay of no more than 10 microseconds.

8. The method for a burner safety time monitoring and interlocking drive system according to claim 6, characterized in that, The specific calculation of safe time in S2 is as follows: the time difference between the rising edge and the falling edge of the standardized digital signal is recorded by a timer, and the time parameter is calculated in combination with the timer's operating frequency, where the timer's operating frequency is not less than 72MHz.

9. The method for a burner safety time monitoring and interlocking drive system according to claim 6, characterized in that, The isolation amplification in S4 includes two stages of processing: the first stage amplifies the control command current to 5-10mA through a transistor, and the second stage amplifies the signal to the power level required to drive the burner actuator through a power MOSFET.

10. A method for a burner safety time monitoring and interlocking drive system according to claim 6, characterized in that, It also includes parameter configuration steps: receiving the safe time threshold input by the user through the human-computer interaction interface, storing it in non-volatile memory, and automatically loading the threshold as a comparison benchmark when the system is powered on.

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