First, the structure and working principle A complete gear pump including motor, reducer, coupling and pump head several parts, the pump head part of the pump housing, front and rear side cover, gear shaft, sliding bearings and shaft seal form. High-temperature gear pump is a positive displacement pump, work rely on the main, driven gear changes caused by the work volume changes to transport the melt. Working volume by the pump body, gear tooth groove and the function of the side plate with the composition. When the gear rotates in the direction as shown in FIG. 1, the melt enters the tooth grooves of the two gears of the suction chamber. As the gear rotates, the melt is brought into the discharge chamber from both sides, and the gears mesh again to make the The melt is forced out of the discharge chamber and pressure fed to the outlet pipe. As soon as the pump shaft is turned, the gear presses the melt down to the outlet side so that the pump outlet can reach very high pressure with little or no effect on flow and discharge pressure. Second, measures to improve operating life 1, due to the pump at high temperatures, it is cold when installed on the piping should be set hinge support seat to prevent the pipe after the temperature shift. 2, the coupling must be heat pump after heating to find the correct, in order to avoid running additional torque. 3, the pump outlet pressure measuring point to be set to stop interlocking alarm, otherwise, once the discharge pipe blocked, easy to cause damage to the pump. 4, the pump starts, no pressure in the export formation, you can not blindly speed, to prevent premature failure of the shaft or bearing. 5, cleaning pipetting, do not pump delivery of cleaning fluid, the inner part should be removed, pipetting after the end of installation, so as to avoid foreign matter in the pump. 6, the temperature of the jacket heat medium jacket can be slightly lower than the jacket before and after the heat medium temperature. Because the melt viscosity and shear rate as a decreasing function, the gear extrusion, bearing shear will make the melt temperature rise after the pump 3 ~ 5 ℃, reduce the heat medium temperature to prevent the melt degradation. Data show that by reducing the bearing zone temperature can greatly increase bearing capacity, do not need to replace the large-capacity pump, just by increasing the speed can be used gear pump output capacity increased by 50%. 7, speed to be slow, do not make the sharp rise in pressure before and after, in order to avoid damage to the bearings or melt blocked the lubrication channel. 8, behind the gear pump outlet melt filter to be replaced on a regular basis, do not long-term high pressure and pressure in the upper limit of operation. 9, Regular replacement of bearings can save maintenance costs. When it is found that the amount of wear on the inner surface of the shaft or bearing is close to the thickness of the hardened layer, the shaft can be polished and reused, replacing only the bearing. This prolongs the life of the shaft by 8 to 10 years. 10, in case of power outage or heat medium cycle interrupt more than 3Omin, the pump should be disassembled after cleaning and reassembly, so as to avoid melt curing, cracking and other causes poor bearing lubrication and pump damage. Third, the operation and management 1, routine maintenance (l) gear pump disintegration and cleaning, heating, cooling, starting and stopping should be strictly in accordance with the provisions of the operation to avoid unnecessary losses. (2) Care should be taken to maintain the stability of the population pressure of the booster pump so that it has a stable volumetric efficiency in favor of the pump itself and the stability of the downstream spinning quality. (3) The population is negative pressure of the packing shaft seal pump, packing should be kept at a pressure higher than the atmospheric pressure. When the back pressure is reduced, the pressure of the stuffing box should be adjusted in time, otherwise the pump will be sucked into the air and the belt will be broken. This will affect the pelletizing and cause the discharge of the pelletizer. (4) to check the temperature of the heat medium jacket, the main body and the front and back cover of the heat medium temperature to be consistent. (5) Every time the output increases, it is necessary to record the output, speed, output, inlet pressure and current value at the time, and compare the data before and after, and carefully analyze them so as to find the anomalies as soon as possible and deal with them in time. 2, the common faults and countermeasures are as follows: (1) Symptom: the pump can not discharge the cause of the malfunction: a, the opposite direction of rotation; b, suction or discharge valve is closed; c, the inlet without material or pressure is too low; d, viscosity is too high , The pump can not bite countermeasures: a, confirm the direction of rotation; b, confirm whether the valve is closed; c, check the valve and pressure gauge; d, check the viscosity of the liquid to low speed operation by the speed ratio of the flow rate is there, (2) Symptom: Insufficient pump flow Cause of malfunction: a. Inlet or discharge valve is closed. B. Inlet pressure is low. C. Outlet line is blocked. D. , Confirm the valve is closed; b, check the valve is open; c, to confirm the discharge is normal; d, tighten; a large number of leaks affect production, should stop running, disassembly inspection; ) Symptoms: abnormal sound failure causes: a, coupling eccentric or poor lubrication b, motor failure; c, reducer abnormalities; d, shaft seal at the installation of bad; e, shaft deformation Or wear countermeasures: a, find or fill the grease; b, check the motor; c, check the bearings and gears; d, check the shaft seal; e, parking disintegration inspection (4) Outlet pressure is too high; b, melt viscosity is too large; c, shaft seal assembly bad; d, shaft or bearing wear; e, motor failure measures: a, check the downstream equipment and pipelines; b, Seal, appropriate adjustments; d, check after parking, hand crank car is too heavy; e, check the motor (5) Symptom: pump suddenly stopped Cause of the malfunction: a, power failure; b, motor overload protection; c, coupling Damage; d, the outlet pressure is too high, interlocking reaction; e, bite abnormal pump; f, shaft and bearing adhesion stuck measures: a, check the power supply; b, check the motor; c, open the safety cover, crank inspection ; D, check the instrument interlocking system; e, after parking, positive and negative reversing confirmation; f, crank confirmation: The above symptoms and measures are one-to-one correspondence.High temperature gear pump is polyester melt delivery, And melt meter The amount of essential equipment. Compared with other types of melt pumps, the high temperature gear pump has the advantages of compact structure, reliable operation, low energy consumption, high volumetric efficiency, small shear effect on the melt, stable flow at high viscosity and high pressure, and no outlet pressure fluctuation. The pump has its unique advantages and the key role in the process, making it play an irreplaceable role in polyester production. However, if the operation of the gear pump is not properly used and not properly managed, it can not only fail to perform its functions, it can even cause sudden pump damage.
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