Preventive measures for boiler induced draft fan accident

In the operation of the boiler induced draft fan, accidents such as burning of the motor, the shaft, the impeller, and the bearing damage often occur, which seriously endangers the personal safety of the equipment and employees, and causes certain economic losses to the enterprise.

How can we effectively prevent the occurrence of an induced draft fan accident? Through the analysis of many cases of induced draft fan accidents, the main causes of the accident are as follows:

(1) The furnace workers are not strictly operated according to the operating regulations, and even operate in violation of regulations, so that the induced draft fan is loaded with load, causing the motor to overload and burn out.

(2) There is no regular overhaul of the fan, or the overhaul quality is not closed, the impeller and the shaft are loose, and the hub rivet is loose, causing the fan shaft or the impeller to fly.

(3) The dust removal effect of the dust collector is not good or the dust removal equipment is not installed. The flue is not cleaned regularly, and the dust is too much. The impeller blades of the induced draft fan are seriously worn.

(4) The impeller blades are not subjected to anti-wear measures, and are worn and damaged by dust. In severe cases, the blades are broken and the main shaft is bent.

(5) Daily maintenance and maintenance did not keep up, the fan bearing lacked oil and water shortage, causing overheating damage of the bearing.

(6) The operation technology of the electrician is unclear, the motor junction box is not tightly sealed, the wire end is not fastened, the circuit is out of phase, and the bearing or the motor is damaged.

(7) The inspection is not diligent or strict, or the fault is not handled in time, so that the failure of the induced draft fan is further expanded into a damage accident.

(8) The system is not perfect, not specific, and the furnace operator misuses after drinking, which artificially causes the induced draft fan to be damaged.

For the above reasons, the following precautions should be taken:

(1) Strengthen operational management and prohibit illegal operations. The start-up and operation of the boiler induced draft fan must have strict operating procedures. If the induced draft fan must be started at no load, it is strictly forbidden to start with load. Especially when the boiler is raised, the temperature of the flue gas is too low. If the induced draft fan is loaded with load (that is, the fan inlet baffle is opened or fully open), the starting current will be Increase a lot, and the startup time is too long, the fan motor is easy to overheat, it is likely to be overloaded; when the boiler (especially the pulverized coal furnace) is ignited, pay attention to the opening sequence of the drum and the induced draft fan, and cannot be reversed. That is, the air blower can be started by first opening the induced draft fan and running for 10 minutes to remove dust or flammable gas from the furnace and the flue. If the blower is first opened, then the induced draft fan is opened, which not only increases the load of the induced draft fan, but also causes the induced draft fan motor to overheat and burn, which may cause a furnace explosion accident.

(2) Support the regular overhaul of the induced draft fan and strictly control the quality of maintenance. The draft fan should be overhauled regularly. Eliminate the hidden dangers of the accident in the bud. The overhaul should be comprehensive and thorough. The wear of the impeller should be carefully checked. The balance between the spindle and the impeller should be balanced. The internal connection should be loose or collided. The inlet baffle switch is flexible and the bearing is lubricated and cooled. Happening.

(3) Surface strengthening treatment of the impeller piece to improve the wear resistance of the blade. Since the induced draft fan is mostly high-temperature flue gas of about 200 °C, the flue gas contains a large amount of fly ash, SO2 and other corrosive gases, and the fan blades are seriously worn, which is prone to accidents such as falling fan output, vibration, and blade breakage. Therefore, the blade working face or the severely worn part should be surfacing to improve the wear resistance of the blade. Surfacing welding should use DC welding machine, using manual arc welding method, using special fan wear-resisting electrode (such as wear-resistant No. 1, Mo-Cr-B hard alloy wear-resistant electrode, etc.), and wear-resistant electrode in 300 ~ Dry at 350 ° C for 1 hour. Before welding, the surface of the blade should be cleaned of ash, rust, etc., preheated to 100 ° C, with small current, low voltage, temperature, short arc, symmetrical welding. Practice has proved that the wear resistance of the blade after surfacing welding is greatly improved, which not only changes the frequent wear of the fan impeller, but also lays a good foundation for the safe operation of the fan.

(4) Take flue gas dedusting measures, regularly clean the flue and improve the working environment of the induced draft fan. Units with dust removal equipment should strengthen dust removal operation management and improve dust removal efficiency; units without dust removal equipment should regularly add boiler-specific cleaning agent to the furnace, and remove the ash from the flue in time to avoid clogging of the flue. The occurrence of a damage accident.

(5) Strengthen the routine maintenance and patrol inspection of the induced draft fan, find problems and deal with them in time. The furnace worker should always check the voltage, current, oil level, temperature and sound of the induced draft fan. If the cooling water is normal, if it is found that the fan is vibrating, oil leakage, bearing overheating, loose screws on the ground, bad coupling cushion, and interruption of cooling water, it should be handled in time. When you hear that the fan has severe noise or severe collision sound or motor “beep” sound, or smells burnt, or finds that the temperature of the motor rises sharply, you need to stop the emergency and take corresponding measures to repair it in time. In daily maintenance, the electrician should carefully and carefully tighten the wire when wiring, to prevent phase loss. At the same time, it is necessary to close the outlet hole of the junction box with a rubber retainer as much as possible to prevent the front bearing of the motor from forming a convection path with the air, affecting the lubrication effect of the bearing and causing the bearing to overheat damage.

(6) Establish and improve the equipment management system, increase the post training of the furnace workers, and improve the operational technology level of the furnace workers.