Main line pump

Main Line Pump

The main component of the pump is the housing with a horizontal connector in a plane passing through the pump axis. The pump housing is a complex cast iron casting consisting of two parts (pump cover and pump body), in which channels of semi-spiral inlets and spiral outlets are cast. In the lower part of the housing, inlet and discharge nozzles, support lugs, trough-shaped brackets for leak collection, and bearing housing attachments are also cast. The location of the inlet and discharge nozzles at the bottom of the housing allows disassembly of the pump without removing the pipelines. The nozzles are directed horizontally in opposite directions. The horizontal connector is sealed with a paronite gasket. Bolts along the connector are tightened with cap nuts to prevent hot water from seeping through the bolt threads. To supply water from the first to the second stage of the pump, a transfer pipe is provided in the upper part of the housing (cover). To reduce leakage between stages, a diaphragm is installed. In the upper part of the transfer pipe and pump housing (cover), holes are provided for air release, and in the lower part of the pump housing, holes are provided for water discharge from the pump. During pump operation, the holes are plugged. To reduce possible vertical temperature displacements of the housing, the support surfaces of the lugs are maximally close to the pump axis, and the pump is supported by foundation frame pedestals. To ensure directed thermal expansion of the pump, pins are installed in the lower part of the housing, serving as guide pins. Sealing rings are installed at the impeller sealing points in the pump housing.

The pump rotor of Main Line Pump  is an independent unit consisting of a shaft, impellers, protective sleeves, bushes, bearing bushings, oil deflectors, and fastening elements. Double-sided inlet impellers, installed on the shaft with a sliding fit, abut against protective sleeves and are fixed in the axial direction through bushings with round nuts. Thermal clearances are provided between the rotor components to compensate for thermal expansions. The rotor is dynamically balanced after assembly. The rotor is relieved from axial forces by using double-sided inlet impellers.

The shaft seal is of the mechanical type with cooling. To ensure reliable operation of the mechanical seal in the pump housing, seal sleeves are installed, forming chambers (thermo barrier) into which cooling liquid is supplied. The cooling liquid supplied to the seal is divided into two streams. One stream washes the outer surface of the seal sleeve and is discharged into the drain pipeline, while the other stream passes through an opening in the seal sleeve to the lantern ring and is supplied to the packing. Leakage through the seal is collected in the tray and discharged into the leakage drain pipeline. The design provides relief for the second-stage seal by diverting water from the seal through a relief pipe to the inlet of the first stage. Leakage through the seal is collected in the tray and discharged into the drain.

The option of installing end seals is possible.

The rotor of the Main Line Pump is supported by roller bearings, which are installed in detachable housings. The bearing housings are made of two halves with a horizontal connector. A roller bearing is installed in the bearing housing on the drive side, which absorbs radial loads. In the bearing housing on the free end of the shaft, two radial-thrust ball bearings are installed, which absorb residual axial forces and radial loads. The bearing lubrication is liquid, ring (sump) type with the help of lubricating rings. Oil level indicators are provided in the bearing housings for oil level monitoring. The bearing housings are provided with chambers, and coolers are installed to supply cooling liquid for oil cooling.

Alignment of the rotor with the stator is achieved by moving the bearing housings with adjusting screws. After final alignment, the bearing housings are fixed relative to the pump housing by tapered pins.

Within the pump, there is a system of auxiliary pipelines for cooling the end seals of the rotor and bearing assemblies.

An asynchronous motor with a squirrel-cage rotor is used as the drive.

The pump and motor are connected to each other using a flexible bush-finger coupling. The coupling is covered by a guard.

The designation of the pump means: SE – network electric pump; 1250 – delivery in m3/h; 140 – head in m; 11 – pressure at the inlet in kgf/cm2.

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