Piping design of multi-stage pumps such as vertical centrifugal pumps and horizontal centrifugal pumps
The piping design of multistage pumps such as vertical centrifugal pumps and horizontal centrifugal pumps
Vertical multi-stage centrifugal pump and horizontal multi-stage centrifugal pump pipe size selection: installation cost of the entire system; minimum flow rate required by the process (for example, to avoid precipitation); minimum inner diameter required by the process (for example, solid transportation); minimization Maximum velocity of erosion of pipes and accessories (for example, erosion, wear); standard pipe diameters available in the market. When designing and laying out pipelines, the following items should be noted:
Horizontal multistage centrifugal pump
2. The maximum pressure that the inlet and outlet pipes and their pipe joints can withstand should be considered. The pump does not bear the heavy pressure of the pipeline, and the plastic pump inlet does not use "soft connection" sub-joints.
3. The pipeline layout should be as straight as possible, minimize the accessories in the pipeline and shorten the pipeline length as much as possible. When turning is necessary, the bending radius of the elbow should be 3 to 5 times the pipe diameter, and the angle should be greater than 90℃ as much as possible. The inlet pipeline is equipped with a straight pipe about 3 times the diameter.
4. Valves (ball valves or stop valves, etc.) and check valves must be installed on the discharge side of the pump. The valve is used to adjust the working point of the pump. The check valve can prevent the pump from reversing when the liquid flows backwards and prevent the pump from being hit by water hammer. (When the liquid flows back, it will produce a huge reverse pressure and damage the pump).
5. The resistance loss in the piping system leads to the resistance loss in the piping system: pipe wall, valve, elbow, tee, reducer/expanded pipe, expansion joint, container inlet/outlet. In other words, almost every place the pumped fluid passes through has interception losses, and the fluid itself also has friction losses.
6. The friction coefficient is affected by the following factors, pipe roughness, fluid viscosity, pipe size, and fluid velocity
7. System head resistance:
Hj=Hjf+His
where: Hj: resistance of the entire system, Hj: resistance loss along the pipeline, Hjs: local resistance loss.
In order to improve the suction performance of the pump, the suction pipeline of the pump should be as short as possible and bend as little as possible (the most elbow uses a large radius of curvature) to reduce the resistance loss of the pipeline. In order to prevent the pump from cavitation, the suction pipe of the pump should avoid the bladder-shaped part where gas accumulates as much as possible. When it is unavoidable, a DN15 or DN20 exhaust valve should be installed at the bladder-shaped part. When the suction pipe of the pump is in the vertical direction, if the suction pipe is equipped with a reducer, an eccentric reducer should be equipped to avoid the formation of an air bag, as shown in the figure below.
