(1) Selection of installation point
The flue gas temperature at the installation point should meet the requirement of less than 700°C. Generally speaking, the lower the flue gas temperature, the longer the service life of the detector, and the higher the flue gas temperature, the shorter the service life. The detector cannot be installed in a dead corner where the flue gas does not flow, nor can it be installed in a place where the flue gas flows rapidly (such as in the expansion chamber of some bypass air passages). In addition, the flue gas leakage is required to be small, and the detector is easy to install and maintain. For medium and small boilers, it is recommended to install it before the economizer and after the superheater, because the flue gas of the boiler system flows from the furnace to the steam drum. Coal burner and air preheater are discharged from the chimney after being recycled by the induced draft fan. If the measuring point is too close to the outlet of the flue gas furnace, due to the high temperature and fast flow rate, the stainless steel casing of the detector will be eroded and corroded, which will shorten the service life; It will cause the oxygen value at the measuring point to be too high, which cannot faithfully reflect the oxygen content of the flue gas in the furnace.
(2) The detector fixing flange on the furnace wall
The transition frame is made of steel as shown in the figure. The flange of the transition frame can be directly welded on the wall of the furnace wall or buried in the furnace wall, but it is required to be airtight and firm. The flange at the other end of the transition frame is designed to fix the detector, so it must match the screw holes of the detector fixing flange. If the 12mm mounting holes are selected, four mounting holes of ￠12mm are evenly distributed on the ￠130mm circle of the transition frame flange, and four M1O×40 screws are used to fasten it with the fixing flange of the detector. To prevent air leakage, a rubber cardboard sealing ring can be filled between the two flanges.
(3) Installation of the detector
The reference gas of the detector is provided by natural convection of the air, the detector needs to be installed horizontally, and the reference gas and standard gas interfaces are correspondingly downward. Rubber cardboard must be filled between the detector mounting flange and the transition frame flange to prevent air from leaking into the flue and affecting the measurement accuracy. The end of the detector must be more than 150mm away from the inner wall of the boiler, so that the exposed part of the porous ceramic filter faces the flow direction of the flue gas (the direction of the filter can be rotated independently) to avoid the ceramic body being washed by the gas and prolong the service life. When the detector is pushed into the hot flue, in order to prevent the zirconium tube from bursting, it should be pushed in gradually, generally at 10-20 cm/min.
(4) Lead wire
The wiring between the sensor and the secondary instrument or transmitter includes a total of six wires of zirconia, thermocouple, and heating furnace, and the wires can be made of O.75mm2. plastic insulated wires.
