Solutions for vibration issues in double suction middle opening pumps.
Release time:
2022-04-23
Source:
The double-suction middle-opening pump may vibrate during use. In such cases, it is necessary to analyze the situation and find fundamental judgment methods to solve the problem. Let's explore the solutions for the vibration of double-suction middle-opening pumps!
The double-suction middle-opening pump may vibrate during use. In such cases, it is necessary to analyze the situation and find fundamental judgment methods to solve the problem. Let's understand the solutions for the vibration of the double-suction middle-opening pump below!
1. Vibration caused by misalignment during the installation and assembly of the double-suction middle-opening pump.
The vibration of the pump body is caused by the deviation of the level of the pump body and thrust bearing after installation, as well as the verticality of the suction pipe, and these three control values are interrelated.
After installing the double-suction middle-opening pump, if the pump pipe and pump head are suspended without filters, when the verticality deviation of the suction pipe is too large, there will be severe vibrations during the rotation of the pump. The alternating stress generated during pump operation can cause the discharge pipe to break.
After assembling the double-suction middle-opening pump, control the discharge pipe within its full length, with a verticality error controlled within ±2mm. The longitudinal and transverse level error of the pump should be less than 0.05/1000mm. The static balance tolerance with respect to the impeller should be below 10g, and an insertion gap of about 8-12mm is required after assembly. The error in installation gaps is an important cause of pump body vibration.
2. Outlet turbulence oscillation.
The outlet of the double-suction middle-opening pump is sequentially equipped with a Dg500 short pipe, check valve, electric butterfly valve, manual valve, main pipe, and water hammer eliminator, causing irregular pulsation phenomena in water turbulence motion. Each valve's resistance experiences local resistance, leading to changes in momentum and pressure, which causes pulsating changes in pressure and velocity fields in pipe turbulence to continuously transmit energy to the pump body. When the main frequency of turbulence approaches the inherent frequency of the middle-opening pump system, energy absorption by the system causes vibration.
To reduce this vibration's impact, all valves must be fully opened, and a corresponding length of installation platform must be set on the short pipe. After this treatment, vibration values significantly decrease.
3. Torsional vibration of the double-suction middle-opening pump.
The double-suction middle-opening pump is connected to the motor using a flexible coupling, with a total drive shaft length of 24.94m. During operation, different angular frequencies of primary vibrations overlap. The result of combining two different angular frequency simple harmonic vibrations is not necessarily simple harmonic vibration; that is, there inevitably exists torsional vibration with two degrees of freedom inside the pump body. This vibration mainly affects thrust bearings and causes damage.
Working principle of the double-suction middle-opening pump:
The impeller is installed inside the pump casing and connected to the pump shaft, which is directly driven by a motor. The center of the pump casing connects to a liquid intake on the suction pipe; liquid enters through a bottom valve and suction pipe into the pump. The liquid discharge outlet of the pump casing connects to a discharge pipe; when the pump speed is constant, its head and flow rate are related to impeller diameter.
In summary, we have clarified the working principle of middle-opening pumps; however, when selecting one, it is essential to understand relevant selection principles for middle-opening pumps.
1. It must meet requirements for flow rate and head. That is, it requires that the operating point (the intersection point between device characteristic curve and pump performance curve) always operates within an efficient range while saving power and minimizing damage to components.
2. The selected pump must be compact in size, lightweight, cost-effective, with good characteristics and high efficiency.
3. It should have good anti-cavitation performance, stable operation, and long service life.
4. The selected pump should require low engineering investment and have low operating costs.
The double-suction middle-opening pump should avoid drawing and discharging excessively muddy water. Otherwise, components like impellers, wear rings, packing materials are prone to wear, increasing vibration frequency and reducing efficiency.
The above introduces solutions for vibrations occurring in double-suction middle-opening pumps. If you need more information, feel free to contact us!
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