The flame detector is an important device in the boiler furnace monitoring system. Its function is to detect the combustion conditions in real time according to the combustion characteristics of the flame. Once the flame combustion state does not meet the normal conditions or is extinguished, a signal is given in a certain way, and the fuel supply is stopped when the boiler is extinguished. It is mainly composed of two parts: the probe and the signal processor.
Earlier flame detectors appeared in the 1950s. In the 1960s, foreign countries first developed ultraviolet flame detectors. Since the 1970s, foreign countries have successively appeared flame detectors that release infrared and visible light when detecting flame combustion. In the 1980s, boiler combustion monitoring devices based on images and videos appeared. Later, there were flame detectors with combined probes (infrared, ultraviolet). Since its development, the detection and discrimination capabilities of flame detectors have become stronger and stronger, and detection has also become more intelligent.
The role of flame detection equipment runs through the entire process from boiler startup to full-load operation. It is used to determine the establishment/extinguishment of the flame in the entire furnace or unit burner or the presence or absence of fire. When the entire furnace is extinguished or the unit burner is extinguished, the flame detection equipment contacts accurately operate to issue an alarm, relying on the FSSS system interlocking function to stop the operation of the corresponding powder feeder, coal mill, fuel main valve or primary fan, etc., to prevent the accumulation of fuel in the furnace, abnormal conditions are ignited and cause the occurrence of boiler explosion accidents. Therefore, the performance of the equipment, that is, the reliability of the equipment operation and the accuracy of the detection are directly related to the operation and stability of the unit.
Detection principle
The combustion of oil, coal or gas fuel is actually the release of fuel chemical energy in the form of electromagnetic waves. The flame of the burner can generally emit an almost continuous luminescence spectrum. Its emission source is the high-temperature carbon microparticles, micro-powder carbon particle groups and gases generated during the combustion process. The intermediate products in the combustion process of different fuels are not exactly the same or the proportions of the intermediate products are different. The spectra emitted by different combustion intermediate products are not exactly the same. This is the basis for selecting different types of flame detectors. C2 emits visible light (emission wavelength is about 473.7 nanometers), CH compounds emit spectra in the ultraviolet to blue light band, carbon particle groups emit red light spectrum, triatomic gases such as CO2, H2O and SO2 emit infrared light. The spectral distribution characteristics of different fuels are that oil flames contain a large amount of infrared, some visible light, and a small amount of ultraviolet, and coal powder flames contain a small amount of ultraviolet, rich visible light and a small amount of infrared. Gas flames have abundant ultraviolet rays, infrared rays and less visible light, and for a single burner flame, its radiation spectrum is regularly distributed along the flame axis. For example, the pulverized coal burner in a pulverized coal boiler is divided into four areas along the axis from inside to outside, namely the preheating area, the initial combustion area, the combustion area and the burnout area. In the initial combustion area, not only is the visible light abundant, but the energy radiation rate changes intensively. Therefore, it is the best choice to accurately align the flame detection probe with the initial combustion area of the burner.
This is the introduction to the detection principle of the flame detector. Xixian New District Tengyan Combustion Control Technology Co., Ltd. is mainly engaged in the technical development, technology transfer, production, sales, installation and technical services of combustion control system products such as Shaanxi flame detectors, Shaanxi high-energy igniters, Shaanxi semiconductor nozzles, Shaanxi high-energy ignition cables, high-voltage ignition cables, conductive rods, ignition guns, etc. Welcome friends in need to call us for consultation on this business, and look forward to further communication with you.
