Pump should use vertical coupling submersible pump, submersible motor directly with the pump impeller coaxial connection, hydraulic components by the pump shell, impeller composition. To ensure flow stability without excessive eddy, hydraulic components should be designed and made without sharp edges. Pump outlet pipe flange should be in accordance with the ISO standard nominal pressure 1MPa.
Impeller should be no blockage and no overload characteristics of the spiral centrifugal impeller, with a soft positive force and centrifugal force, its long flow path without sharp corners, to ensure that the impeller in the transport of sewage sludge will not be blocked and damage sludge floc structure. Impeller in hydraulic design, should be combined with the positive force and centrifugal force.
Impeller should be dynamic balance, dynamic balance accuracy should not be less than G6.3 level. The vibration becomes less than 0.45mm/s.
Motor should be three-phase squirrel cage motor, three-phase 380V, 50Hz, protective grade ip68,f grade insulation. The configuration of the motor should ensure that when the h-q curve in the work, there will be no overload, the motor should be able to start 12 times per hour. The maximum temperature of the pump medium is 40 ℃, and the average temperature rise of the stator winding does not exceed 85 ℃.
The cooling form of the motor shall be cooling, that is, the current flows from the periphery of the motor to cool the motor. The cooling system and oil filling type motor which rely on pumping medium to cooling circuit are not used.
The submersible motor and the pump shall be manufactured by the same manufacturer, and the junction box with IP68 protection grade is randomly provided.
Each pump shall provide a series of sealed systems with two separate sealing devices.
The mechanical seal should be operated in the oil chamber, so that the sealing surface can be lubricated properly.
Mechanical seals should be maintenance-free, lubrication and the transfer of liquid separated, should be able to withstand thermal shock, and has a good emergency operation characteristics.
The manufacturer shall ensure that the service life of the mechanical seals is not less than 30,000 hours.
Pump in the hydraulic design should be in the medium of mud sand only wear pump suction part, in no case will not cause wear and tear on the pump shell. In the pump horn-shaped suction mouth, should be built into the horn-shaped wear-resistant lining, and axial adjustable to keep the pump at any time high efficiency, the material should be ductile iron or Brinell hardness up to 450 of high chromium cast iron. If the wear-resisting lining is to be replaced in daily operation, it is necessary to remove the suction part of the pump and remove the motor part of the pump. The design of any other irregular shape, no adjustment, and replacement of the motor and other parts shall not be adopted.
Cable and cable Seals
The motor should be equipped with a control and power underwater cable, each cable has a separate import, and reliable sealing, if the power cable is a multi-core cable, each cable will also be individually sealed. Cables should be stretched into the wiring room and sealed with reusable rubber seals and not sealed with resin or other canned sealing materials.
Shaft and bearing
The shaft of the pump and the motor should be the same unit, the pump shaft is the extension of the motor shaft, and no coupling can be adopted.
The pump/motor shaft should be supported by high quality permanent lubrication, rolling bearings, bearing design should be sufficient to withstand all axial and radial forces.
Each of the motor by the constant temperature sensor protection, three sensors should be connected in series, heat-sensitive switches in the ≤70℃ often closed, in 125 ℃ jump off. The heat-sensitive switch should be connected with the motor overload protection and connect to the control cabinet, and the junction box should include the terminal board. The terminal plate is applied with an elastic O-ring and a motor seal. The wiring board shall be threaded and connected to the cable conductor and the stator inlet line for a long time.
In order to indicate the wear of bearings, a constant temperature sensor is arranged at the upper and lower bearings, and the temperature sensor should be disconnected before the spindle or other parts of the motor are seriously damaged.
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