What are the methods of flow regulation for centrifugal pumps?

1.Change the characteristic curve method of the pump aChange the speed of the pump. b.cutting impeller outer circle; Change the impeller diameter.

2.change the characteristic curve of the pipeline; The most common method is to adjust the opening of the outlet valve of a centrifugal pump. When the valve is closed, the local resistance of the pipeline increases, the characteristic curve of the pipeline becomes steeper, the working point moves to the left, and the flow rate decreases.

The flow rate of a centrifugal pump can be adjusted in several ways:

Adjust the outlet valve: The flow rate of the pump can be controlled by adjusting the opening of the outlet valve. When the valve opening becomes smaller, the resistance increases, and the flow rate of the pump decreases.

Frequency conversion speed regulation: The use of frequency converter can control the motor speed, so as to control the flow rate of the pump. Adjusting the output frequency of the inverter can change the speed of the motor and thus the flow rate of the pump.

Adjust the radial clearance of the impeller: When the flow rate of the pump needs to be adjusted, the flow rate of the pump can be changed by increasing or decreasing the radial clearance of the impeller. The smaller the radial clearance, the greater the flow rate of the pump and vice versa.

Replace the impeller: The impeller is one of the key components that affects the performance of the pump. By replacing the impeller, the performance of the pump can be changed, and thus the flow rate of the pump can be regulated. For example, changing the number or shape of the blades of the impeller can change the head and flow rate of the pump.

In general, the flow regulation of centrifugal pumps needs to be selected and implemented on a case-by-case basis. When choosing a regulation method, factors such as the model of the pump, the operating conditions, and the requirements of use need to be considered.

In actual production, it is often necessary to adjust the flow rate of the pump to meet the requirements of the process, and the main methods of adjustment are.

a.The centrifugal pump flow regulation method that affects the characteristics of the pipeline and changes the opening of the outlet valve, which is the most widely used, is the bypass adjustment method (return flow method).

b.Flow regulation method that affects the characteristics of centrifugal pump, adjustment method that changes the speed of prime mover, adjustment method that reduces the outer diameter of impeller, and method of blocking impeller blades.

The flow adjustment of centrifugal pumps can generally be done in the following ways:

Frequency conversion speed regulation: The frequency converter is used to adjust the speed of the motor, so as to control the flow rate of the centrifugal pump. Adjusting the speed of the motor can achieve continuous and stable adjustment, which is suitable for occasions with large requirements for flow changes.

Bulkhead adjustment: Install an adjustment baffle on the inlet or outlet of the centrifugal pump, and adjust the flow rate by changing the opening of the baffle. This method has a narrow adjustment range and is suitable for applications with a small range of flow changes.

Change the impeller diameter or blade angle: Change the flow rate of the pump by changing the impeller diameter or adjusting the blade angle. This method has a large range of adjustment, but it needs to be stopped for replacement or adjustment, and it is not flexible enough.

Pumps in series or parallel: The flow rate is regulated by connecting two or more centrifugal pumps in series or parallel. Series connection can increase the head wide return, while parallel connection can increase the flow rate. This method needs to consider the allowable flow rate and head range of the pipeline, and is suitable for occasions with large flow and head requirements.

Adjust the opening of the inlet valve: Adjust the flow rate by adjusting the opening of the inlet valve. This method has a narrow adjustment range, and it is suitable for occasions where the flow rate is not very demanding.

It is necessary to choose the appropriate adjustment method according to the specific work situation and requirements to achieve the best results.

Common centrifugal pump flow regulation methods are as follows:

1.Adjust the impeller diameter: Change the head and flow rate of the pump by adjusting the diameter of the centrifugal pump impeller or the angle of the blades.

2.Adjust the speed: Changing the speed of the centrifugal pump can change the flow rate and head of the pump. Generally speaking, the flow rate of a centrifugal pump is proportional to the rotational speed, and the head is squared to the rotational speed.

3.Adjust the inlet closure valve or outlet valve: Change the flow rate of the pump by adjusting the opening of the inlet valve or outlet valve.

4.Use a frequency converter: Installing a frequency conversion tremor calendar can change the speed of the motor, which in turn changes the flow and head of the centrifugal pump.

5.Parallel or series operation: Running multiple centrifugal pumps in parallel or series allows you to change the flow rate and head of the pump.

It should be noted that different adjustment methods correspond to different application scenarios, and the specific choice of which method should be determined according to the actual situation.

Centrifugal pumps and reciprocating pumps regulate the flow differently. The flow regulation of centrifugal pumps is usually carried out in the following three ways:

Frequency conversion speed regulation: The flow rate of the centrifugal pump is adjusted by changing the speed of the motor, which can generally be achieved by the frequency converter. This allows for continuous and smooth adjustment, but requires the installation of special frequency converter equipment.

Adjust the outlet valve: Adjust the flow rate of the centrifugal pump by adjusting the opening of the outlet valve, which is relatively simple and easy, but it needs to be adjusted manually and is not automatic enough.

Change the impeller diameter: Adjust the flow rate of the centrifugal pump by changing the diameter of the impeller. This method is more suitable for centrifugal pumps with large flow rates, but it requires the replacement of equipment parts.

The flow regulation method of reciprocating pump usually adopts the following two ways:

Changing the Stroke: Adjust the flow rate of the pump by adjusting the piston stroke of the reciprocating pump.

Adjust the displacement valve: Adjust the flow rate of the reciprocating pump by adjusting the opening of the displacement valve.

It should be noted that when carrying out flow regulation, it is necessary to choose the appropriate adjustment method according to the specific situation, and pay attention to maintaining a suitable working condition to avoid adverse effects on the operation of the pump.

Centrifugal pumps and reciprocating pumps regulate their flow rates very differently. It is mainly manifested in the following aspects:

1.Different adjustment methods: reciprocating pumps generally adjust the flow rate by changing the speed of the pump or changing the stroke length of the pump, such as through frequency converter, manual control, etc.; The centrifugal pump can adjust the flow rate by changing the opening of the inlet and outlet valves of the pump, the diameter of the impeller, etc., such as using manual valves or automatic adjustment systems.

2.Different accuracy: Because the reciprocating pump realizes the flow adjustment by changing the stroke of the moving parts, the adjustment accuracy is relatively high, but for the case of a large adjustment range, its accuracy will be affected; The centrifugal pump is adjusted by changing the diameter of the impeller or changing the valve opening, so the adjustment accuracy is relatively low.

3.Different reliability: because the reciprocating pump uses moving parts to achieve flow regulation, its reliability is relatively low, and at the same time, the requirements for sealing, strength and other aspects are also higher, and the maintenance cost is also higher; Centrifugal pumps, on the other hand, use static components such as valves and impellers to achieve adjustment, which is relatively reliable and has low maintenance costs.

Therefore, when selecting a flow adjustment mode, it is necessary to consider the specific scenario requirements and performance requirements, and select them based on their respective characteristics.

Centrifugal pump. At a fixed speed, the head is fixed, and the diversion area is adjusted by adjusting the outlet valve, which can be used to adjust the flow rate. The advantage is simplicity and ease of implementation, the disadvantage is the throttle valve.

Consumes energy. The flow rate can also be adjusted by adjusting the speed of the motor by using the inverter, which has the advantage of saving electrical energy. The details are as follows:

Flow regulation. 1. Change the opening of the valve.

Changing the valve switch on the outlet pipeline of the centrifugal pump is essentially changing the characteristic curve of the pipeline. As shown in the figure below, when the valve is closed, the local resistance of the pipeline increases, the characteristic curve of the pipeline becomes steeper, the working point moves from M to M1, and the flow rate decreases from QM to QM1. When the valve is opened, the pipeline resistance decreases, the pipeline characteristic curve becomes flatter, the working point moves to m2, and the flow rate increases to qm2.

It is fast and convenient to adjust the flow rate with a valve, and the flow rate can be continuously changed, which is suitable for the characteristics of continuous chemical production. Therefore, it is widely used. The disadvantage is that the valve is closed when the valve is closed, the resistance loss increases, and the energy consumption increases, which is very uneconomical.

2. Change the speed of the pump.

Changing the speed of the pump is essentially changing the characteristic curve of the pump. The original speed of the pump is n, the working point is m, as shown in the figure below, if the speed of the pump is increased to n1, the characteristic curve of the pump h-q moves up, the working point is moved from m to m1, and the flow rate is increased from qm to qm1. If the speed of the pump is reduced to n2, the operating point is moved to m2 and the flow rate is reduced to qm2.

This method of adjusting and dismantling the Zen section requires a variable speed device or an expensive variable speed prime mover, and it is difficult to continuously adjust the flow rate, so it is rarely used in chemical production.

The commonly used adjustment methods for centrifugal pump flow rate include variable speed adjustment, variable diameter adjustment, variable angle adjustment, throttling adjustment, etc.

1. Variable speed adjustment.

Changing the speed of the pump can change the performance of the pump, so that the working point of the pump changes, this method is called variable speed mediation.

2. Variable diameter adjustment.

After the impeller is turned, the performance of the pump will change according to a certain law, so that the working point of the pump will change. We call the method of turning the impeller to change the working point of the water pump as variable diameter adjustment.

3. Variable angle adjustment.

Changing the installation angle of the blades can change the performance of the pump, so as to achieve the purpose of changing the working condition point of the pump. This way of changing the operating point is called variable angle adjustment of the pump.

4. Throttling adjustment.

For the pump device with gate valve installed in the outlet pipeline, if the gate valve is closed for a small time, the local resistance in the pipeline is increased, and the characteristic curve of the pipeline becomes steeper, and the working point moves to the upper left along the Q-H curve of the pump. The smaller the gate valve closes, the greater the increased resistance and the smaller the flow becomes. This method of changing the operating point of the pump by closing the small gate valve is called throttle adjustment or variable valve adjustment.

Commonly used methods are:

1. Cut or increase the diameter of the impeller to reduce or increase the flow rate, and the motor power should also be changed.

2. Adjusting the outlet valve can only play the role of reducing the flow rate and increasing the head, but it cannot increase the flow rate and reduce the head.

3. Adjust through the frequency conversion control cabinet.

-Suhua Pumps.

1. Change the specific curve of the pipeline.

2. Change the speed of the pump and the diameter of the impeller.

The flow regulation methods of centrifugal pumps are discussed, including valve throttling, variable speed adjustment, cavitation adjustment, etc.

1. Valve throttling: The easiest way to change the flow rate of the centrifugal pump is to adjust the crack opening of the pump outlet valve, and use the opening of the pump outlet valve to change the pipeline characteristics of the pump, so as to change the flow rate. When the valve is closed, the local resistance of the pipeline increases, and the characteristic curve of the pipeline system moves to the upper left, and the key point of the ruler of the centrifugal pump also moves to the upper left.

2. Variable speed adjustment: by changing the speed of the centrifugal pump, the characteristic curve of the pump is changed, raised or lowered, so that the working condition and flow rate of the pump are changed.

3. Cavitation adjustment method: cavitation adjustment method, such as condensate pump, can adopt a low water level operation mode, and change the characteristic curve of the water pump through the water level of the condenser, so as to change the flow rate. This method is simple to operate and saves power, but the impeller is easily damaged and accompanied by vibration and noise.

Centrifugal pump structure

1. The impeller is the core part of the centrifugal pump, its speed is high and the output is large, and the blades on the impeller play a major role. The inner and outer surfaces on the impeller need to be smooth to reduce frictional losses from the water flow.

2. The pump body is also called the pump casing, which is the main body of the pump. It plays the role of support and fixation, and is connected with the bracket on which the bearing is mounted.

3. The function of the pump shaft is to connect the coupling with the motor to transmit the torque of the motor to the impeller, so it is the main component to transmit mechanical energy.

4. The sliding bearing uses transparent oil as lubricant, and the oil is added to the oil level. Too much oil will seep out along the pump shaft, too little bearing will overheat and burn out and cause accidents. During the operation of the water pump, the temperature of the bearing is up to 85 degrees, and the general operation is about 60 degrees.

5. The stuffing box is mainly composed of packing, water sealing ring, packing barrel, packing gland and water sealing pipe, and the function of the stuffing box is mainly to close the gap between the pump casing and the pump shaft, so as not to let the water flow in the pump flow outside and not let the outside air enter the pump, and always maintain the vacuum in the pump.