Classification of pumping stations, Requirements for the design...

Classification of pumping stations

Pumping stations of water supply systems are a complex complex of hydromechanical, electrical and automatic equipment that provides water supply in accordance with the needs of the consumer. The composition of structures, their design features, type and number of main pumping units and auxiliary equipment are determined based on the principles of ensuring the reliability and continuity of water supply and integrated use of water resources and environmental protection.

In the implementation of the main function of the pumping station - water supply - the most important design stage is the selection of the types and parameters of the equipment, taking into account its characteristics, relationships, convenience and safety.

The main power equipment includes pumps and drive motors. Depending on the required head and feed at the station, centrifugal, axial and diagonal pumps are installed. The drive of pumps is most often carried out with the help of electric motors, less often internal combustion engines, even less often gas or steam turbines. A complex consisting of a pump and a drive motor is called an hydraulic unit or simply an unit. The number of pumping station units may vary and depends on the calculated feed and reliability category. With the required large feed, the stations tend to reduce the number of aggregates by increasing their unit capacity.

Mechanical equipment pumping stations includes hoisting and transport mechanisms, closures. Lifting and transport equipment serves mainly for the installation and dismantling of equipment, pipelines and their fittings.

Ancillary equipment includes technical water supply systems, drainage and drainage systems, oil and pneumatic facilities, vacuum system.

The electrical devices of the pumping station include power transformers, inputs and outputs of high and low voltage, switchgears, current leads to electric motors, control panels, control systems and electrical equipment for auxiliary purposes. The power supply system must correspond to the reliability category of the pumping station, which is ensured by the appropriate redundancy of supply and equipment inputs.

The type of the pumping station is determined by its purpose, supply, type and mode of the water supply source, type and characteristics of the main equipment, climatic conditions, relief, hydrogeology of the terrain, water level in the source, etc. Possible combinations of these conditions have predetermined the presence of a large number of signs, according to which the types and designs of pumping stations of water supply systems can be classified. We will highlight the most significant signs of the classification of pumping stations: pumping stations of I and II lifts; boosting; circulating.

By location relative to the surface of the earth: buried (mine type); partially buried (3 ... 4 m); ground (pump axis at or above the ground).

By the nature of the control: with manual control (starting and stopping are performed by the maintenance personnel, and control over the operation by automatic control devices); automatic (all operations - start, stop, control - perform the appropriate automatic devices); with telecontrol - automatic control of communication lines at a considerable distance from the control center.

Requirements for the design of pumping stations of II lifting

The choice of the type and construction of the building of a water pumping station and the solution of its communications should be made taking into account the need to ensure: the most efficient operation of power equipment; reliability and ease of use; the least head loss; reliable operation; possibly short construction terms.

At the pumping stations with centrifugal horizontal pumps, the following are the main distribution schemes of the units: single-row arrangement of units, pump axes are parallel to the longitudinal axis of the station; single-row arrangement of aggregates, pump axes are perpendicular to the longitudinal axis of the station; two-row arrangement of aggregates in staggered order.

The advantage of a single-row arrangement of pump units (Fig. 5.7, a, 6) is the compactness of equipment placement, a small width of buildings, and when using double-entry pumps, pumped liquid and reduced hydraulic losses. However, with a large number of pumping units, the station building is very long. Therefore, for a large number of pumping units, the chess location of the pumping units should be used (Figure 5.7, c).

Schemes for placing pumping units (M - motor; H - pump)

Fig. 5.7. Schemes for placing pumping units (M - motor, H - pump):

a, 6 - single-row; in - chess

Suction and pressure pipelines of pumping units are made of steel pipelines. Connect the pipes and fittings with electric welding, and in the places where the reinforcement is installed - with flanges.

Suction tube location in the intake chamber

Fig. 5.8. Location of the suction pipe in the intake chamber:

a - front section; b - horizontal cut

The main requirement for suction pipelines of centrifugal pumps from the point of view of their reliable and uninterrupted supply of water is their airtightness, since, according to numerous experiments and observations, air penetration into the interlobble channels of the pump impeller greatly adversely affects its characteristics. Even small (up to 1% in 1 m3 of water), the presence of undissolved air can reduce the pump flow by 5 ... 10%, and if the air content is increased to 10 ... 15%, the pump loses its suction capacity and breaks its operation.

The diameters of the suction and pressure pipes are determined by the technical and economic calculation based on the water flow rates within the limits indicated in Table. 5.1.

Table 5.1

Diameters of suction and pressure pipelines depending on the speed of water

Pipe diameter, mm

Water velocity in pipelines of pumping stations, m/s

suction

pressure head

Up to 250

0.6 ... 1.0

0.8 ... 2.0

More than 250 to 800

0.8 ... 1.5

1.0 ... 3.0

Over 800

1.2 ... 2.0

1.5 ... 4.0

Uninterrupted operation of the pump and minimum hydraulic losses in the suction line are also ensured by the correct arrangement of suction pipes in the receiving chamber of the pumping station (Figure 5.8, a, b).

In Fig. 5.9 shows a separate type pumping station, which is the lifting station I in the water supply scheme of a large settlement. The station is equipped with three D630-9 pumps, of which two are operational and one is standby. The foundations of pump units are designed in such a way that they can, if necessary, replace the pumps with more powerful D1265-65 or D1600-90.

Pump station of mining type I lifting

Fig. 5.9. Pump station of mine type I lifting:

1 - suction pipeline; 2 - pump unit; 3 - gate valve with electric drive; 4 - pressure pipeline; 5 - drainage pumps; 6 - vacuum pumps

The pumping station II of the lift, equipped with four pumps, is shown in Fig. 5.10. The width of the machine building is 12 m, the length of the buried part is 18 m, the height above the ground is 5.4 m. The floor of the pump room is buried at 2.4 m.

The water to the pumps is supplied by individual suction pipes. On the pressure line, a manifold is arranged, from which two pressure pipelines move. Flowmeters of the Venturi nozzle type are installed on pressure pipelines in wells located 10 m from the station.

For the installation of equipment and repair work, the station building is equipped with a single-girder bridge crane with manual control. At the end of the building are placed the premises of power transformers, switchgears, switchboard facilities, utility rooms and a sanitary unit.

Pumping Station II Lift

Fig. 5.10. Pumping station II of the lift:

1 - suction pipes; 2 - household space; 3 - rectifiers; 4 - placing static capacitors; 5 - a bathroom; 6 - Workshop; 7 - switchgears; 8 - shield; 9 - Transformer chambers; 10 - pressure pipelines; 11 - computer room; 12 - suspended crane-beam

thematic pictures

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