Main types of burner flame detectors

The function of the monitoring system is to ensure the safe operation of the burner. Its main components are flame monitor, pressure monitor and external monitoring temperature monitor. The main function of a flame monitor is to monitor the flame formation and generate signals to report to the program controller. There are three main types of flame detectors: photosensitive resistance, ULTRAVIOLET UV electric eye and ionization electrode.

A.photosensitive resistance, used for light oil, heavy oil burner, its function and working principle is: teach resistance and A light has three contact flame relay connected, light teach resistance value with device receives the brightness of the light changes, receives the brighter the light, the lower the resistance value, when add voltage must be on opposite sides of the photosensitive resistance, the higher the current in the circuit, when the current reaches A certain value, the flame relay is activated, so that the burner continue to work down. When the optical-soft resistance does not feel enough light, the flame relay does not work and the burner will stop working. Photoresistance does not apply to gas burners.

B.Ionization electrode: mainly used on gas burners. Program controller to the ionization electrode power supply, if there is no flame, electrode on the power supply will stop, if there is a fire, gas is its high ionization, ion current to flow between the electrodes, flame and combustion head, ion current rectifier into a dc, and through the grounding of the burner shells to flame relay work, to ensure that the burner order after work smoothly. If the ionization electrode is grounded, the current generated is AC instead of DC, the flame relay will not work, and the program controller will be locked. In addition, the flame instability in the ionization region will also cause the burner to break when the flame still exists, which may be solved by adjusting the amount of air or gas as the ratio of air to gas is inappropriate, or the uneven distribution of air and gas on the combustion head can be solved by adjusting the position of the combustion head.

C.ultraviolet UV magic eye: generally used in oil-gas combined burner, the magic eye can only feel the flame of ultraviolet spectral range (190 ~ 270 nm), UV tube not flashing in the hearth, ordinary light or furnace refractory sun glow material response, the service life of the UV tube in no more than 50 ℃ environment temperature is about 10000 hours, the environment temperature is too high for the life has very big ring. If it receives an adequate amount of ULTRAVIOLET light, it can generate an electric current, which is suitably amplified, and the machine or flame relay closes it. If the UV tube of the battery, even if there is no ultraviolet ray, it will still show received UV, in order to overcome this defect, every time before opening, program controller is coupled with an appropriate voltage at both ends, so even if the battery runs out, it will only signal indicates no flame, such a program controller will immediately cease to work. In order to detect the effect of UV electric eye, after ignition, pull it out of the original position for at least one minute, UV electric eye is pulled out, can not detect the UV emitted by the flame, the related relay is disconnected, the burner stops working. Even a small amount of oil can block ultraviolet light from entering the photocell and cause the internal sensors to fail to receive enough uv light to function. The photocell must therefore be thoroughly cleaned. The UV tube is insensitive to sunlight or light from ordinary lamps, and its sensitivity can be tested by a spark between the two electrodes of a flame or an ordinary ignition transformer. To ensure that the burner works properly, its current must be stable and not lower than the current required by the programmable controller.