With increasing parameters of condensate pumps, mainly supply, their dimensions and weight increase. Due to the convenience of layout and reduction of the occupied space, in domestic practice, condensate pumps of thermal power plants with a flow rate of 200 m3/h and higher are manufactured in a vertical version of the KsV type.
The vertical design not only saves space, but also provides the maximum possible head pressure according to the installation conditions and the most favorable cavitation conditions, since the first stage impeller is located at the lowest point of the pump. In addition, this arrangement makes it possible to eliminate the shaft seal and external bearing on the suction side, replacing them with an internal bearing that operates on the pumped liquid.
Also, to ensure acceptable mass and dimensional characteristics of the pumps, they are designed at a relatively high rotation speed for condensate pumps, which in turn required the creation of first-stage working bodies with high suction capacity. For this purpose, pre-engaged axial wheels or double-entry wheels are used for the first stage.
As a rule, most domestic vertical condensate pumps have a double-casing design with one external sealing joint.
A distinctive feature of pumps of this type is that they can be assembled and disassembled without disconnecting the pipelines, and it is also possible to rotate the suction pipe relative to the vertical axis, which facilitates the placement of the pump unit.
The materials of the main parts of vertical condensate pumps are gray cast iron, carbon and alloy steels. Chromium steels are used for first-stage impellers and pre-engaged axial wheels.
As an example of the design of KsV type pumps, consider the KsV 320-160-2 condensate pump.
Condensate pump KsV 320-160-2 (Figure 1) – centrifugal, vertical, double-casing, multi-stage, sectional type internal casing with single-sided impellers.
The basic part of the pump is the outer casing, which is a welded structure and consists of two parts: receiving and pressure. The inlet and pressure pipes are welded to the outer casing and are located horizontally in opposite directions (at the Customer’s request, an option in one direction is possible). Also welded to the upper part of the housing are the pump support feet with stiffeners, in which there are holes for transporting the pump. In the receiving part of the outer casing of the pump there is a threaded hole for removing vapors into the air space of the condenser during startup and operation of the pump.
The inner housing (removable part) is a separate assembly unit consisting of the following components: rotor, end seal, thrust bearing and parts: pressure cover, section housings with guide vanes, supply to the first stage. The parts of the inner body are centered among themselves on cylindrical sharpenings and connected to each other with tie rods. The joints are provided with seals made of heat-resistant rubber rings.
Seal rings for impellers are installed in the section bodies, and interstage seal rings are installed in the guide vanes.
In the inlet to the first stage there is a sliding bearing on the pumped liquid.
The support lantern of the electric motor, the stuffing box seal housing and the thrust bearing are attached to the pressure cover.
To remove the inner housing, two eye bolts are provided in the pressure cover.
The joint between the pressure cap and the outer casing is sealed with a ring made of heat-resistant rubber.
The separating joint between the receiving and pressure parts is sealed with two rings made of heat-resistant rubber.
The pump rotor is a separate assembly unit and consists of a shaft, impellers, an upstream wheel, a discharge drum, bushings, sealing parts and fasteners. To increase the suction capacity of the pump, an upstream impeller is installed in front of the first stage impeller. The parts are installed on the shaft using a sliding fit. All impellers, except the first stage, have the same flow path. The impellers, the upstream wheel, the discharge drum, and the bushings are fixed on the shaft with keys, and in the axial one with round nuts. There is a gap between the last stage wheel and the drum, which serves as a compensator for thermal expansion when the impellers are heated by the pumped condensate. The shaft is also equipped with bushings with a special screw thread for supplying condensate to the lower and oil to the upper bearings.
The assembled pump rotor is dynamically balanced.
The axial force of the rotor is perceived by the unloading piston (drum), which ensures almost complete balancing only at nominal feed. When the operating mode deviates from the nominal one, an unbalanced force acts on the rotor, which can be directed downward or upward depending on the pump flow and is perceived by two angular contact bearings
nicknames The unloading drum is mounted on a common key with the impeller of the last stage and is fixed in the axial direction with a round nut. To prevent water leakage under the drum along the shaft, a sealing ring made of heat-resistant rubber is installed.
To connect the chamber behind the unloading drum with the supply pipeline of the pump, a unloading pipe with a connecting flange is installed on the stuffing box housing and brought out.
The end seal of the pump is of the gland type with a water seal ring, to which cold condensate is supplied under pressure to cool the stuffing box and prevent air from leaking into the pump. Cold condensate is supplied from the cooling cavity of the seal housing through the holes to the water seal ring. The seal is accessible through windows in the bearing housing.
It is possible to install mechanical seals.
The rotor is supported by two bearings. The upper thrust bearing is made of two angular contact ball bearings installed in an X-shaped pattern and fixes the position of the rotor in the pump, and also perceives radial and residual axial forces. Bearing lubrication is liquid. The design of the upper pump support provides a circulating lubrication system for the bearings. An oil bath is made in the bearing housing, from which oil is supplied through a special hole to the bearings using a screw-threaded bushing. The used oil is drained by gravity into the bath through holes made in the bearing housing. Oil cooling is carried out using a coil, the spiral section of which is located in the oil bath, and the straight sections pass through vertical holes in the bearing housing and form branch pipes for supplying and discharging process water. The oil level in the bath is controlled by the oil level indicator. To drain contaminated oil, there is a special device in the lower part of the oil bath, which is an elbow covered with a cap. In the middle part of the bearing housing there is a threaded hole, closed with a plug, for filling oil. Next to the oil filling hole there is a hole connecting the oil bath to the atmosphere. To control the temperature of the bearings, there is a place on the housing for installing a resistance thermal converter.
The lower journal bearing is lubricated by the pumped condensate, which is supplied from a specially designed chamber to the bearing by a bushing with a multi-thread and, after passing through a gap, is discharged into the suction cavity. The bearing clearance is adjusted using set screws, after which the bearing sleeve is pinned. To protect against the ingress of solid particles, the bearing is covered with a mesh.
Alignment of the pump rotor in the stator (inner pump housing) is ensured by moving the bearing housing using adjusting screws. After aligning the rotor, the position of the bearing housing is fixed with pins.
An asynchronous motor with a squirrel-cage rotor is used as a drive. The electric motor is installed on the pump lantern and connected to it with an elastic sleeve-pin coupling. Alignment of the electric motor and pump is carried out by moving the lantern using adjusting screws. After centering, the position of the lamp is fixed with pins.
The pump symbol means: KsV – condensate vertical; 320 – flow rate in m3/h; 160 – head in m; 2 – second modernization.
