[Q&A] 2017.7.9
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This post was last edited by LQ198619 on 2017-7-8 18:35. What are the methods for adjusting the flow rate of centrifugal pumps? Answer: Flow regulation in centrifugal pumps is achieved by altering the pump’s characteristic curve and the pipeline’s characteristic curve. 1. Method of changing the pump’s characteristic curve: a. Change the pump’s speed. b. Cut the outer circumference of the impeller ； Change the impeller diameter. 2. Change the pipeline characteristic curve ； The most common method is to adjust the opening degree of the centrifugal pump outlet valve. When the valve is closed, the local resistance in the pipeline increases, the pipeline’s characteristic curve becomes steeper, the operating point shifts to the left, and the flow rate decreases. http://down.hcbbs.cc/attachment/forum/201706/10/203353z7y06fdo70r6eod0.jpg Petrochemical sector – New ideas for energy savings: the “Creative Ideas” campaign (the second phase is currently in full swing). http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1666758 (Source: Haichuan Chemical Industry Forum) 2017: “My Technical Upgrades” in the coal chemical industry. http://bbs.hcbbs.com/thread-1786290-1-1.html (Source: Haichuan Chemical Industry Forum website)
1. Pump speed 2. Regulate backflow 3. Pump outlet opening 4. Head pressure
(1) Throttling regulation. The principle of throttling control is to change the shape of the pipeline characteristic curve, thereby altering the operating point of the centrifugal pump. When the flow rate needs to be reduced while the pump is in operation, the discharge gate valve of the pump is closed, which increases the resistance of the gate valve. Since more energy is consumed in the gate valve due to its being closed partially, this regulation method results in high losses and poor economic efficiency; however, it is widely used in practice due to its simplicity. (2) Bypass return regulation. This adjustment method involves opening the bypass valve of the pump, allowing a portion of the liquid to flow back from the pump’s discharge pipe to the suction pipe, thereby reducing the flow rate in the discharge pipe. This method is more suitable for vortex pumps, as the characteristic curve of vortex pumps shows a sharp increase in head when the flow rate decreases, resulting in an increase in shaft power; whereas when the flow rate increases, the shaft power slightly decreases. (3) Variable speed adjustment. The principle is to change the position of the pump’s characteristic curve by adjusting the speed of the centrifugal pump, thereby altering the operating point. This adjustment method incurs no additional energy loss, making it a relatively economical approach. But a variable-speed motor must be used. (4) Adjustment of the outer diameter of the cutting impeller. Reducing the outer diameter of the centrifugal pump impeller can alter the pump’s performance at the same rotational speed, thereby changing both the flow rate and the head. This adjustment method also incurs no additional energy loss, making it a cost-effective approach; however, it is only suitable for use when the centrifugal pump needs to operate at a low flow rate over an extended period of time.
(1) Throttling regulation. (2) Bypass return regulation. (3) Variable speed adjustment. (4) Adjustment of the outer diameter of the cutting impeller.
(1) Throttling regulation. (2) Bypass return regulation. (3) Variable speed adjustment. (4) Adjustment of the outer diameter of the cutting impeller.
(1) Throttling regulation. (2) Bypass return regulation. (3) Variable speed adjustment. (4) Adjustment of the outer diameter of the cutting impeller.
(1) Throttling regulation. The principle of throttling control is to change the shape of the pipeline characteristic curve, thereby altering the operating point of the centrifugal pump. When the flow rate needs to be reduced while the pump is in operation, the discharge gate valve of the pump is closed, which increases the resistance of the gate valve. Since more energy is consumed in the gate valve due to its being closed partially, this regulation method results in high losses and poor economic efficiency; however, it is widely used in practice due to its simplicity. (2) Bypass return regulation. This adjustment method involves opening the bypass valve of the pump, allowing a portion of the liquid to flow back from the pump’s discharge pipe to the suction pipe, thereby reducing the flow rate in the discharge pipe. This method is more suitable for vortex pumps, as the characteristic curve of vortex pumps shows a sharp increase in head when the flow rate decreases, resulting in an increase in shaft power; whereas when the flow rate increases, the shaft power slightly decreases. (3) Variable speed adjustment. The principle is to change the position of the pump’s characteristic curve by adjusting the speed of the centrifugal pump, thereby altering the operating point. This adjustment method incurs no additional energy loss, making it a relatively economical approach. But a variable-speed motor must be used. (4) Adjustment of the outer diameter of the cutting impeller. Reducing the outer diameter of the centrifugal pump impeller can alter the pump’s performance at the same rotational speed, thereby changing both the flow rate and the head. This adjustment method also incurs no additional energy loss, making it a cost-effective approach; however, it is only suitable for use when the centrifugal pump needs to operate at a low flow rate over an extended period of time.
Reduce backflow and open the outlet valve
(1) Throttling regulation. The principle of throttling control is to change the shape of the pipeline characteristic curve, thereby altering the operating point of the centrifugal pump. When the flow rate needs to be reduced while the pump is in operation, the discharge gate valve of the pump is closed, which increases the resistance of the gate valve. Since more energy is consumed in the gate valve due to its being closed partially, this regulation method results in high losses and poor economic efficiency; however, it is widely used in practice due to its simplicity. (2) Bypass return regulation. This adjustment method involves opening the bypass valve of the pump, allowing a portion of the liquid to flow back from the pump’s discharge pipe to the suction pipe, thereby reducing the flow rate in the discharge pipe. This method is more suitable for vortex pumps, as the characteristic curve of vortex pumps shows a sharp increase in head when the flow rate decreases, resulting in an increase in shaft power; whereas when the flow rate increases, the shaft power slightly decreases. (3) Variable speed adjustment. The principle is to change the position of the pump’s characteristic curve by adjusting the speed of the centrifugal pump, thereby altering the operating point. This adjustment method incurs no additional energy loss, making it a relatively economical approach. But a variable-speed motor must be used. (4) Adjustment of the outer diameter of the cutting impeller. Reducing the outer diameter of the centrifugal pump impeller can alter the pump’s performance at the same rotational speed, thereby changing both the flow rate and the head. This adjustment method also incurs no additional energy loss, making it a cost-effective approach; however, it is only suitable for use when the centrifugal pump needs to operate at a low flow rate over an extended period of time.