How to choose a vertical multistage centrifugal pump? Does anyone know?

Pipeline Pump Selection:

1. What is the required flow rate (also need to consider whether the water can be sufficient**.) If the incoming water is only 30m h, and the user needs 40m h, then it can only be selected according to the amount of incoming water).

2. What is the required head (required head = height difference + pipeline loss + pressure required at the water outlet).

3. What is the diameter of the required pump, which is divided into DN32 40 50 65 80 100 125 150 200 and other calibers.

Because the pipeline centrifugal pump generally refers to the single-stage single-suction vertical horizontal pipeline centrifugal pump, if the head is high (more than 70 meters), it is best to choose a vertical or horizontal multistage centrifugal pump. Single-stage impeller, after more than 70 meters, the efficiency is poor. (DL vertical multistage centrifugal pump, D type horizontal multistage centrifugal pump).

If the flow rate required by the user is large (more than 200m h) and the flow rate is about 70 or 80 meters, the double suction pump (horizontal) can be considered.

Vertical multistage centrifugal pump is a centrifugal pump with compact overall structure, small size, light weight, low noise, remarkable energy-saving effect and easy maintenance. With a standard vertical motor and a quick-release mechanical seal, it is very easy to replace. The overflow part of the pump is made of stainless steel (304 316), which can be used for mildly corrosive media.

When purchasing a horizontal multistage centrifugal pump, the following aspects should be considered to ensure that the right pump type is selected:

Use and working conditions: clarify the purpose of the pump, such as water supply, drainage, refrigeration, pot high celery such as furnace transportation, etc. Understand the working environment and working conditions of the pump, including flow, head, pressure, temperature, medium properties, etc.

Pump performance parameters: According to the use and working conditions, determine the main performance parameters of the pump, such as flow rate (q), head (h), working pressure (p), speed (n), efficiency ( ), etc. When selecting, we should try to choose to work in the center of the pump performance curve to ensure the stable operation and high efficiency of the pump.

Pump material: According to the nature of the conveying medium, select the appropriate pump material to ensure the corrosion resistance, wear resistance and high temperature resistance of the pump. For example, when transporting corrosive media, a pump made of corrosion-resistant materials such as stainless steel should be selected.

Pump structure: According to the installation, transportation and maintenance requirements of the pump, select the appropriate pump structure, such as bearings, seals, couplings, etc. At the same time, consider whether the structure of the pump is easy to install, disassemble and maintain.

Pump manufacturer and after-sales service: Choose a pump manufacturer with a good reputation and service to ensure the quality of the pump and after-sales service. When selecting a model, you can consult the technical staff of the manufacturer's Shouzai and let them provide advice on a case-by-case basis.

Economy: On the premise of meeting the performance requirements, the purchase cost, operating cost and maintenance cost of the pump are comprehensively considered, and the pump type with higher cost performance is selected.

In the process of purchasing, you can refer to the relevant standards and norms, or consult professional opinions. In addition, in order to ensure the safe operation of the pump, the configuration of auxiliary equipment such as safety valves and control systems should also be considered when purchasing.

1) High efficiency, low noise, energy-saving pumps should be selected, and it is strictly forbidden to choose eliminated products. Choose regular Sun Bo manufacturers, such as Shanghai Sunshine Pump Industry.

2) The pump should be selected according to the design flow rate and the required head, and considering the decrease in the pump output due to wear and tear, the pump can be selected according to the calculated head h multiplied by the coefficient; The characteristic curve should be selected as the pump whose head gradually decreases with the increase of flow, so that the pump works stably and is reliable when the state is delayed and works in parallel; And the operating point of the pump should be kept in the high-efficiency range, which is energy-saving and not easy to damage the parts.

3) When there is no regulating facility in the water supply pipe network, it is advisable to use the speed control pump unit or the rated speed pump group to run the water supply. The maximum water output of the pump unit should not be less than the design flow rate of the community water supply, and should be checked by fire protection conditions.

4) The number of pumps should be minimized when choosing the lifting pump of the water tank and water tower, and it is advisable to use one and one to prepare; When a single pump can meet the requirements, it is not appropriate to use multiple parallel connections; If it is necessary to use multiple parallel operation or large and small pumps, the model and number should not be too much, and the model should not exceed two types, and the head range of the pump should be similar; When running in parallel, each pump should still be operating within the high-efficiency zone.

5) The design water supply flow rate of the variable frequency speed control pump (group) should ensure that it meets the requirements of the maximum design second flow rate in the domestic water supply system. The power supply must be reliable (dual power supply or dual circuit power supply); The working point of the pump should be selected in the high-efficiency working area of the pump characteristic curve (Q-H curve), and should not be selected on the extension line of the Q-H curve, and the most unfavorable working point of the design should be at the right end of the high-efficiency section of the pump characteristic curve, that is, the point where the pump has the largest water output and the head is low but can meet the requirements, that is, the intersection of the low point of the high-efficiency area of the pump characteristic curve and the pipeline characteristic curve. The working range of the pump speed regulation can be within the high-efficiency section of the pump as much as possible; The speed regulation range should be set between 25% and 100% of the water supply of the pump; The equipment should have automatic water level control function.

Centrifugal pump is a kind of vane pump, relying on the rotating impeller in the rotation process, due to the interaction between the blades and the liquid, the blades will transfer mechanical energy to the liquid, so that the pressure of the liquid can be increased, to achieve the purpose of transporting the liquid.

The commissioning of the pump shall meet the following requirements:

The steering of the drive machine should be the same as that of the pump;

Identification of the steering of pipeline pumps and coaxial pumps;

There should be no loosening of each fixed connection part, and the specifications and quantity of lubricant filled with each lubrication part should comply with the provisions of the technical documents of the equipment;

The parts with pre-lubrication requirements should be pre-lubricated according to the regulations;

All indicating instruments and safety protection devices should be sensitive, accurate and reliable;

The crank should be flexible and have no abnormal phenomena;

The high-temperature pump should be preheated before the trial operation, and the temperature should rise evenly, and the temperature rise per hour should not be greater than 50; The temperature difference between the surface of the pump body and the process pipeline with the inlet of the working medium should not be greater than 40;

A connecting device to eliminate the effect of temperature rise is installed, and a bypass connection device is installed to provide a cooling water source.

There are four points to pay attention to when starting the centrifugal pump:

There is a limit to the head produced by a centrifugal pump at a certain speed. The operating point flow and shaft power depend on the condition of the unit system connected to the pump (differential position, differential pressure and loss of line). The head varies with the flow rate.

The work is stable, the conveying is continuous, and the flow and pressure are pulsation-free.

Generally, there is no self-priming ability, and the pump needs to be filled with liquid or the pipeline pumped into a vacuum before it can start working.

The centrifugal pump is started with the discharge line valve closed, and the vortex pump and axial flow pump are started with the valve fully open to reduce the starting power.

Because the centrifugal pump relies on the suction of the impeller centrifugal force to form a vacuum to lift the water, when the centrifugal pump starts, the gate valve must be closed and the water is filled. If the water level exceeds the impeller part, the air in the centrifugal pump is discharged before it can be started. After starting, a vacuum is formed around the impeller to suck the water upwards, and its gate valve can automatically open to lift the water.

Therefore, the gate valve must be closed first.

——From "Shanghai Sunshine Pump Industry".

This is a vertical multistage centrifugal pump, there will be abnormal sound after installation, and the coupling is installed in the wrong way after inspection

Which is the best historical multistage centrifugal pump? Let's choose a brand.