Study On Integral Flame Detecting And Monitoring System Based On Dual-MCU Structure

In industrial and civil fields, such as electric power, machinery manufacturing, oil refining, chemical industry, light industry and heating heating and other industries, furnace equipment with fuel, gas, or coal as fuel is needed. During the furnace operation, if the misjudgment of the flame burning status in the hearth is made, in serious case, furnace explosion can be caused, leading to the loss of life and property, therefore, it is very necessary to design a kind of specialized testing equipment for fast accurate judgment of the boiler actual internal working state —Furnace Safety Supervision System (FSSS). As its core part, for the whole FSSS performance, the detectivity of the flame detector plays a crucial role, which can convert flame signals into electrical signals with using sensor unit, after computing, after computing and processing, display the running state of the furnace, and make some security measures to ensure the normal operation of the flame detector.In this paper, according to the needs of function, the research designs an integrated flame detection monitoring system based on the structure of dual MCU, whose main work includes: using dual MCU structure, realize the farm-out of the system, and the main MCU is responsible for the flame signal acquisition and processing, determining the current status of the flame in the furnace combustion chamber. From MCU to the man-machine interface, real-time display of flame numerical information, rapid response to parameters set operation. Master/slave MCU monitor each other’s working condition, ensuring the normal operation of the system.Photodiode as the flame sensor component, together with multistage amplifier circuit, form flame signal acquisition unit, and through the MCU built-in digital converter (ADC), detect the flame intensity and frequency. Use fixed-point computation and look-up table method to simplify the FFT operation process, reduce resource consumption, improve the operation speed, complete 512 sampling points operation in 300ms with 1Hz frequency resolution, and calculate the flame intensity and frequency. Use dual relay contact state as flame status and fault status indicator, and dual relays relate with each other on hardware, make sure the correct flame status when the system make faults, regarding 4-20mA current as the analog signal of the flame intensity. On the man-machine interface, use dual-color digital tube to show the flame intensity and frequency, and provide various status instructions. And parameters set includes such two methods as keys and infrared remote control. Using the Modbus bus protocol and the RS-485 interface interaction with terminal computer information, through the PC monitoring software, realize the remote monitor and data acquisition. Adopt the safety monitoring circuit to make real-time monitor and fault alarm for the master/slave MCU running status. Flame detector circuit board uses the system structural design, divided into the front panel, the core control panel and power supply and the output control board, is advantageous for the tooling, debugging and maintenance, by double row and pin structure to realize the connection socket, narrow the volume, improve the reliability.The flame detecting and monitoring system with small volume, low cost, widely application for various heat equipment can be used for the detection of different types of flame signals, and also have the characteristics of large dynamic range, strong real-time performance and high reliability.