（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.

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 full 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. （

large Wet electrostatic precipitator Common fault: the working medium of the fan in the cement industry often contains a certain amount of homogeneous particles with different sizes and shapes, such as the induced draft fan of the dust removal system and the blower for pneumatic conveying. Because these fans work in the dusty air flow, the dust particles in the air flow will not only wear the fan, but also attach ash on the fan blades, and the wear and ash deposition are uneven. As a result, the balance of the fan rotor is destroyed, which causes the fan vibration and shortens the life of the fan. In serious cases, the fan can not work normally. In particular, the fan blades are most severely worn, Wet electrostatic precipitator manufactor It not only destroys the flow characteristics in the fan, but also easily leads to major accidents such as blade fracture and runaway. The wear of transmission parts is also a common problem of fans, including various shafts, rollers, reducers, motors, pumps and other bearing positions, bearing seats, keyways, threads and other parts. The traditional repair welding machine processing method is easy to cause material damage, resulting in deformation or fracture of parts, with greater limitations; Brush plating and spray re machining methods often require outsourcing, which not only requires long repair cycle and high cost, but also can not fundamentally solve the causes of wear (poor impact resistance and yield of metal) because the repair materials are metal materials; Many parts can only be scrapped and replaced, which greatly increases the production cost and inventory of spare parts, leaving the enterprise's good resource advantage idle and wasted

Among all kinds of mechanical and electrical equipment in all walks of life in China, the motors matched with fans account for about 60% of the installed capacity of national motors, and the power consumption accounts for about one-third of the total power generation in China. In particular, Wet electrostatic precipitator manufactor Most fans have the phenomenon of pulling a cart from a horse during use. In addition, due to changes in production and technology, it is necessary to frequently adjust the gas flow, pressure, temperature, etc; Many units still adopt the backward way of adjusting the opening degree of the wind shield or valve to adjust the gas flow, pressure, temperature, etc. In fact, this is to meet the requirements of process and working conditions for gas flow regulation by artificially increasing resistance at the cost of wasting electric energy and money. This backward regulation mode not only wastes valuable energy, but also has poor regulation accuracy, which is difficult to meet the requirements of modern industrial production and services, and has serious negative effects. With the continuous improvement and development of frequency conversion technology in recent ten years. The performance of variable frequency speed regulation is becoming increasingly perfect, large Wet electrostatic precipitator It has been widely used in AC speed regulation in different fields. It has brought considerable economic benefits to enterprises and promoted the automation process of industrial production.