Water pump unit layout and foundation

First, the layout of the pump unit

The arrangement of the pump unit is an important part of the layout of the pump station, which determines the size of the pump room. The distance between the units is based on the principle of not impeding the need for operation and maintenance. The unit layout should ensure safe operation, convenient loading and unloading, maintenance and management, the shortest total pipeline length, the smallest joint fittings, and the smallest head loss, and should consider the expansion of the pumping station. The basic arrangement of the unit is as follows.

1. Vertical arrangement

The longitudinal alignment of the pump unit axes is parallel, as shown in Figure 1. The vertical arrangement is compact, the motor shaft is convenient, and the construction area is small. However, the span of the pump room is large, the number of pipe fittings is large, and the hydraulic condition is poor. Generally, the overhead crane needs to be hoisted. The longitudinal arrangement is suitable for eg IS single-stage single-suction cantilever centrifugal pumps. Because the cantilever pump is flooded at the top, the longitudinal arrangement allows the suction tube to remain straight (pump 1 in Figure 1). If the pump room is equipped with a centrifugal pump with both lateral inlet and lateral outlet (as in Fig. 1, the pumps 2 are both SH type or SA type), the longitudinal arrangement is debatable. If the SH-type pump is in the majority, the longitudinal arrangement is undesirable. For example, in the case of the 20SH-9 pump, the width of the pump plus the size of the suction nozzle and the length of two 90° elbows are 3.9 m (Figure 2). If it is arranged horizontally, the pump width is 4.1m, its width is not much larger than the tandem, but the hydraulic conditions of the import and export are greatly improved, and it can save a lot of power consumption in long-term operation.

Figure 1 Vertical arrangement of pump units

1-IS water pump; 2-SH water pump

Figure 2 Comparison of tandem and horizontal rows (20SH-9 type)

The size of each part between the units should meet the following requirements.

(1) The pump house door is required to be unobstructed. It can accommodate the largest equipment (pump or motor) and has room for operation. The width of the site is generally expressed by the net distance A from the outer wall of the pipe and the wall. A is equal to the width of the largest device plus 1m, but it must not be less than 2m.

(2) The net distance B between the pipe and the pipe should be greater than 0.7m to ensure that the staff can pass it easily.

(3) The outer wall of the pipe and the distribution equipment shall maintain a certain safe operation distance C. When the low voltage distribution equipment, C value is not less than 1.5m, when the high voltage distribution equipment, the C value is not less than 2m.

(4) The net distance D between the protruded part of the pump and the wall shall meet the requirements for the installation of pipeline fittings. However, in order to facilitate the on-site maintenance of the pump, the value of D shall not be less than 1m; if the pump does not protrude from the basic shape, the value of D indicates The distance between the foundation and the wall.

(5) The net distance E between the projected part of the motor and the wall should ensure that the rotor of the motor can be disassembled during inspection and maintenance and leave room for it. The E value is generally 0.5m for the motor shaft length, but should not be less than 3m. If the motor does not protrude from the basic shape, the E value represents the net distance between the foundation and the wall.

(6) The distance F between the outer wall of the pipe and the protruding part of the adjacent unit should not be less than 0.7m. If the motor capacity is greater than 55kW, F should not be less than lm.

2. Horizontal arrangement

The horizontal axis of the pump is in a straight line, as shown in Figure 3.

Figure 3 Horizontal arrangement of pump units

The transverse pumping house has a small span, the inlet and outlet pipes are straight, and the hydraulic conditions are good. The hoisting equipment uses a monorail crane girder interface. However, the pump room is long and the fittings are not easy to disassemble. The horizontal arrangement is mainly applied to the pumps for lateral inlet and outlet, such as the arrangement of single-stage double-suction horizontal centrifugal pumps Sh type and SA type water pumps. The dimensions of the laterally arranged sections should meet the following requirements.

(1) The clear distance A1 from the pump protrusion to the wall is the same as the first requirement of the above longitudinal arrangement. If the pump shape does not protrude from the foundation, Al denotes the net distance between the foundation and the wall.

(2) The net distance B1 between the outlet side pump base and the wall should be determined according to the installation requirements of the plumbing fittings. However, considering that the pump outlet side is the main channel for management operations, B1 should not be less than 3 meters.

(3) The net distance D1 between the pump base and the wall of the water inlet side shall also be determined according to the installation requirements of the pipeline fittings, but not less than 1m.

(4) The net distance between the protruding part of the motor and the power distribution equipment shall ensure that the rotor of the motor can be disassembled during inspection and maintenance and maintain a certain safety distance. Its value requirement is: Cl = motor shaft length + 0.5m. However, low-voltage power distribution equipment should be Cl ≥ 1.5; high-voltage power distribution equipment Cl ≥ 2.0m.

(5) The net distance between the pump bases El and C1 is the same, ie El=Cl. If the motor and the pump protrude from the foundation, the E1 value is expressed as the net distance of the projection.

(6) In order to reduce the span of the pump room, it is also considered to set the suction valve outside the pump room.

3. Horizontal two-row arrangement (Figure 4)

Figure 4 horizontal double row arrangement (down, forward)

The horizontal double row arrangement is compact, the pump room area is small, the fittings are small, and the hydraulic conditions are good. However, the span of the pump room is large, and an overhead crane needs to be installed. The horizontal two-row arrangement is mainly applicable to round intake pump rooms using double-suction centrifugal pumps, and this arrangement can save more base construction prices. It should be pointed out that the steering of the two-row pumps of this type of arrangement is opposite to each other in the direction of the motor. Therefore, special instructions should be given to the pump plant when ordering the pump so that the pump plant can be configured with different steering sleeve locking devices. For size requirements, refer to the related regulations for horizontal single row arrangement.

Second, the basic of the pump unit

The basic function of the water pump is to support and fix the unit so that it runs smoothly without violent vibration and sinking. Therefore, it is required that the foundation has enough strength and a certain weight to meet the stiffness requirements. The requirements for the foundation are: a. Solid and firm. Besides being able to withstand the static load of the unit, it can also withstand mechanical vibration loads; b. On the foundation of the foundation, it should not be poured on soft ground or new town, so as to avoid foundation sinking or uneven subsidence.

Horizontal pumps are block foundations, and their size is generally determined by the data provided by the mounting dimensions of the selected pump. If there is no such information, a small pump with a base can be selected:

Base length L=base length L1+(0.15~0.20)(m)

Base width B=base screw hole spacing (in the width direction) bl+(0.15~0.20)(m)

Base height H = depth of embedment of base anchor screw + (0.15-0.20) (m)

The buried depth of the anchor bolt is generally 20d+4d (d is the bolt diameter, 4d is the cross tail or hook height)

For basic sizes of large and medium-sized pumps without a base, the length and width of the pumps can be determined according to the pitch of the screw holes of the pump or motor (whichever is wider) plus 0.4 to 0.5m. The basic height determination method is the same as above. After determining the height of the foundation, it should also be reviewed according to the weight requirements. The basic weight should be greater than 2.5 to 4.0 times the total weight of the unit. Under the condition that the basic plane size and concrete bulk density are known, the required height of the foundation can be calculated. The basic height should generally be not less than 50-70 cm, and the foundation height should be approximately 10-20 cm higher than the indoor floor. Where there is a trench near the foundation, the depth of the foundation below the floor shall not be less than the depth of the trench. Since water promotes the propagation of vibration, the base of the foundation should be above the groundwater level. Otherwise, the pumping station floor should be made into an integral continuous reinforced concrete slab, and then the foundation should be cast on the floor. At this time, part of the thickness of the floor can be counted. Base thickness.

For large vertical pump units, the pump and motor foundations should be divided. The design principles are basically the same as the horizontal water pump foundations. The special point is that the following factors should be taken into consideration when calculating the weight of the computer group and considering the strength of the foundation: For the vertical pump, the turbulent direction produces water with eccentric moment, the weight of the water pump cannot be balanced, and the shear bolt is transmitted to the anchor bolt when closed. When the brake is started, the generated thrust reacts to the pump. Therefore, the motor base load of the high-power vertical pump unit requires the weight of the pump impeller, the weight of the drive shaft, and the axial tension in addition to the motor's own weight.

In order to ensure the reliable operation of the pump station, safe operation and easy management, the following provisions shall be complied with when laying out the unit.

(1) There shall be a certain width of aisles between the foundations of adjacent units for the passage of workers. When the motor capacity is not more than 55KW, the net distance should not be less than 0.8m; when the motor capacity is greater than 55KW, the net distance should not be less than 1.2m. When the motor capacity is less than 20KW, the width of the aisle can be appropriately reduced. However, in any case, between the protruding parts of the equipment or between the protruding part and the wall is not less than 0.7m, if the motor capacity is greater than 55KW, it shall not be less than 1.0m.

(2) For non-horizontal joint pumps, the shaft and impeller are often taken out along the axial direction during inspection. Therefore, when the pumping station is not counted, there is room for this direction to be taken into consideration, that is, the pump leaves the wall or other. The unit distance should be greater than the length of the pump shaft plus 0.25m. In order to remove the rotor from the motor, the same distance should be set.

(3) In pumping stations equipped with large-sized units, an appropriate area should be reserved for the overhaul of the units. Its size should be maintained in the aisle with a distance of 0.7-1.0m around the repaired unit.

(4) The width of the main channel in the pump station should not be less than 1.2m.

(5) Auxiliary pumps (drain pumps, vacuum pumps) are usually placed in the pump room in the appropriate place, do not increase the size of the pump room as much as possible. Auxiliary pump reliable wall installation, only need to leave aisle. If necessary, the vacuum pump can be placed on the bracket.