（3） The main faults and causes of the fan may occur during the operation of the fan. For the faults generated, the causes must be quickly identified and solved in time to prevent accidents. Faults in the Operation of 4-72-12 Centrifugal Fan and the Causes Table Fault Name Causes Severe Vibration of Bearing Box 1. The fan shaft is different from the motor shaft, and the coupling is installed askew. 2. The casing or air inlet rubs with the impeller. 3. The foundation stiffness is not enough or firm. 4. Impeller rivet is loose or wheel disc is deformed. 5. The impeller shaft disk and shaft are loose, and the coupling bolt is movable. 6. The connection between casing and bracket, bearing box and bracket, bearing box and seat is loose. 7. The air inlet and outlet pipes of the fan are poorly installed, causing vibration. 8. The rotor is unbalanced. Bearing temperature rise is too high 1. The bearing box vibrates violently. 2. The lubricating grease is poor in quality, deteriorated or overfilled, or contains dust, sand, dirt and other impurities. 3. The tightening force of connecting bolts of bearing cover seat is too large or too small. 4. The shaft and rolling bearing are installed askew, and the front and rear bearings are not concentric. 5. The rolling bearing is damaged. The motor current is too high and the temperature rise is too high. 1. The throttle valve in the air inlet pipe is not closed tightly when driving. 2. The flow exceeds the specified value, or the air duct leaks. 3. The gas density conveyed by the fan is too high. 4. The input voltage of the motor is too low or the power supply is cut off individually. 5. The coupling is improperly connected, the leather ring is too tight or the gap is uneven. 6. Affected by the violent vibration of the bearing box. 7. Affected by deterioration or failure of parallel fans. When the belt slides down, the two pulleys are not in the same plane with each other. Belt runout The distance between two pulleys is too close or the belt is too long.

Main working principles of wet electrostatic precipitator: customized Wet dust collector Spray the water mist to the discharge electrode and corona area, the water mist will split and further atomize after being charged in the powerful corona field formed by the barbed electrode, and the collision interception, adsorption and coagulation of electric field force and charged water mist will jointly trap the dust particles, and finally the dust particles will reach the dust collector under the drive of electric field force and be trapped. The water forms a continuous water film on the dust collecting electrode, and the captured dust is washed into the ash hopper and discharged with water. Operating principle of wet electrostatic precipitator. The dedusting process of electrostatic precipitator can be divided into four stages: gas ionization; The dust is charged with ions; Charged dust moves towards the electrode; Remove the dust on the electrode. Only the objects removed by wet electrostatic precipitation are dust and droplets, but their working principles are different due to the differences in physical characteristics between droplets and dust. In principle, Xiangtan Wet dust collector First of all, the existence of water droplets has an impact on the electrode discharge. To form emitting ions, free electrons in the metal electrode must obtain enough energy to overcome the ionization energy and cross the surface barrier to become emitting electrons. It is an effective measure to reduce the surface barrier by bringing water on the electrode surface. After the metal surface is covered with water, the original "metal air" interface is divided into "metal water" interface and "water air" interface. The potential barrier of the latter two interfaces is much lower than that of the former interface. In this way, after the metal surface is filled with water, the original high barrier will be divided into two low barriers, which will greatly weaken the blocking effect of the surface barrier on free electrons and make electrons easy to launch. In addition, Wet dust collector Price Under the action of electric field, various impurity ions in water can easily cross the surface barrier and become emission ions. All of these have changed the electrode discharge effect, enabling corona discharge under low voltage. Secondly, due to the existence of water droplets, the resistance of water is relatively small. When water droplets combine with dust, the specific resistance of dust with high specific electricity decreases, so the working state of wet electrostatic precipitator will be more stable; In addition, since the wet electrostatic precipitator is washed by water flow and has no rapping device, it will not produce secondary dust.

Selection and application of fan performance (I) Description of fan performance: 1. № 10, 12, 16, 20 are converted according to dimensionless performance of № 10 model. 2. № 5, 6, 8 are converted according to dimensionless performance of № 5 model. 3. № 5 and below shall be determined according to the performance of the measured prototype. Note: According to the dimensionless performance curve conversion formula, total pressure H=ρ u2 H (Pa) flow Q=900 π D22 uQ (m3/h) shaft power N=N × D22u3 ρ/4000 (kw), where D2 - impeller outer diameter (m) u - impeller outer edge linear speed (m/s) ρ - gas density (Kg/m3), the required power rate shall be based on shaft power plus mechanical loss and motor reserve. 4. The solid line is № 5 model, and the dotted line is № 10 model. The performance of the fan is expressed by the flow, total pressure, main shaft speed, shaft power, efficiency and other parameters of the fan, and there are certain relationships between the parameters, which are listed in the following table. The relationship of fan performance parameters changes density ρ, speed n changes speed n, atmospheric pressure P, gas temperature t Q1/Q2=n1/n2 H1/H2=(n1/n2) 2 ρ 1/ρ 2 N1/N2=(n1/n2) 3 ρ 1/ρ 2 η 1=η 2 Q1/Q2=n1/n2 H1/H2=(n1/n2) 2 (P1/P2) (273+t2/273+t1) N1/N2=(n1/n2) 3 (P1/P2) (273+t2/273+t1) η 1=η 2 Note: 1. In the middle, Q represents flow (m3/h), H represents total pressure (Pa), N Represents shaft power (kw), η represents total pressure efficiency, ρ represents density (kg/m3), t represents temperature (℃), n represents speed (r/min), and P represents atmospheric pressure (Pa). 2. The footnote symbol 2 indicates the known performance and related parameters, and the footnote symbol 1 indicates the required performance and related parameters. （

（2） Precautions for normal operation of fan 1. If the flow is found to be too large, which does not meet the operating requirements, or less flow is required in a short time, the throttling device can be used to adjust to meet the operating requirements. 2. The sensitivity of thermometer and oil pointer shall be checked regularly. 3. In case of any abnormal phenomenon during the start-up, shutdown or operation of the fan, it shall be checked in time. 4. For minor faults found in the inspection, find out the causes in time and try to eliminate or deal with them. If minor faults cannot be eliminated or major faults are found, repair them immediately. 5. In addition to replacing the lubricating oil during each maintenance, the lubricating oil shall also be replaced regularly. Observe the oil level at ordinary times and replenish lubricating oil in time.

The selection of fans Product performance and fan performance listed in the selection table are based on the performance of delivering air under standard conditions. Therefore, when the use condition is non-standard, the H4-72-12 centrifugal fan must convert the use performance into the performance under standard conditions according to the relationship in the table above, and then select according to the performance and selection table. （3） Treatment of excessive or insufficient flow During use, excessive or insufficient flow often occurs. There are many reasons for this phenomenon. If the flow is high and low during use, it is mainly because the resistance in the pipe network is high and low, or the fan works in a non working area. If it is gradually reduced after a long time during use, it is mainly due to pipe network blockage. After the fan is newly installed, the flow is too large or insufficient during the formal operation. The main reasons for this phenomenon are as follows: 1. The actual value of pipe network resistance is too different from the calculated value. In the general pipe network characteristic equation, H=KQ2, if the actual value K of K-resistance coefficient is less than the calculated value K, the flow will increase; If the actual value K is greater than the calculated value K, the flow decreases. See (b) below.