Key points for installation of self suction centrifugal pumps and different energy-saving schemes

≪ One> Attention points for installation of self suction centrifugal oil pump

Working principle of self suction centrifugal oil pump: The pump adopts an axial return liquid pump body structure. The pump body is composed of a suction chamber, a liquid storage chamber, a scroll chamber, a liquid return hole, a gas-liquid separation chamber, etc. After the pump starts normally, the impeller absorbs the liquid in the suction chamber and the air in the suction pipeline together, and mixes them in the impeller. Under the effect of centrifugal force, the liquid carries the gas to the outer edge of the scroll chamber, forming a thick white foam belt and a high-speed rotating liquid ring on the outer edge of the impeller. The gas-liquid mixture enters the gas-liquid separation chamber through a diffusion tube. At this point, due to a sudden decrease in flow rate, lighter gas is separated from the mixed gas and liquid, and the gas continues to rise and discharge through the pump outlet. The degassed liquid returns to the storage chamber and enters the impeller again through the reflux hole. It mixes again with the gas sucked in from the suction pipeline inside the impeller. Under the action of the high-speed rotating impeller, the self suction centrifugal oil pump flows back to the outer edge of the impeller. As this process continues in a cyclic manner, the air in the suction pipeline continuously decreases until the gas is completely absorbed, completing the self suction process, and the pump is put into normal operation

Some pumps also have cooling chambers at the bottom of their bearing bodies. When the bearing heats up and causes the temperature of the bearing to rise by more than 70 degrees, any coolant pipe joint can be used to inject coolant for circulating cooling in the cooling chamber. The sealing mechanism inside the pump to prevent liquid leakage from the high-pressure area to the low-pressure area is the front and rear sealing rings. The front sealing ring is installed on the pump body, and the rear sealing ring is installed on the bearing body. When the pump has been running for a long time and the sealing ring is worn to a certain extent, which affects the efficiency and self suction performance of the pump, it should be replaced

When directly connecting the pump and motor for transmission, attention should be paid to the coaxiality between the pump shaft and the motor output; The accuracy of pump installation has a significant impact on the smoothness of pump operation and service life, so careful and careful installation and calibration are necessary

2. Use nuts for the pump coupling and tighten them to prevent loosening, otherwise it may cause impeller displacement and mechanical failure

3. To maintain the storage liquid in the pump body, in order to achieve better self suction capacity and prevent dry friction of the mechanical seal, the pump should be raised above the centerline of the pump shaft

4. Attention should be paid to the installation of the suction pipeline: A. The installation height of the suction port should not exceed 5 meters. When conditions permit, the installation height of the suction port should be as low as possible below the water storage level of the pool, and the length of the suction pipe should be shortened as much as possible, with fewer elbows installed. This is beneficial for shortening the self suction time and improving the self suction function

B. The valves, flanges, etc. in the suction pipeline should be strictly prevented from leaking air or liquid, that is, there should be no air leakage in the suction pipeline

C. It is necessary to prevent solid and other debris from being sucked into the pump body. Therefore, a filter should be installed on the suction pipeline. The filtration area of the filter should be 2-3 times the cross-sectional area of the suction pipe, and the filter should be inspected regularly

D. The suction and discharge pipelines should have their own brackets, and the pump body itself is not allowed to bear the load of the pipelines

5. When installing the pump, the static grounding resistance of the pump and pipeline should meet the specified requirements

6. During installation, it is necessary to strictly inspect the pump casing and pipelines for debris such as stones and iron sand

7. Correct the installation clearance and coaxiality of the pump coupling and motor dynamic coupling, with a allowable deviation of 0.1mm for different axial degrees. The height difference between the pump shaft and the motor shaft can be adjusted by placing copper or iron sheets on the feet

8. After 3-4 hours of actual operation of the unit, conduct a post inspection. If there are no defects, it is mainly because the installation is complete. During the trial operation, the shaft should be checked

9. The cooling water joint of the pump bearing body equipped with a cooling chamber device is used for matching rubber or plastic pipes with an inner hole of 12, and its thread size is M12x1.75

10. If a one-way valve is installed on the outlet pipeline of the pump and cannot smoothly discharge gas during the self suction process, an exhaust pipe and valve should be added at the outlet of the pump

< II Energy saving solutions for different self suction centrifugal pumps. Self suction centrifugal pumps can be classified into multiple categories according to different conditions, and enterprises need to develop different solutions for different self suction centrifugal pumps. According to the working principle of self suction centrifugal pumps, they can be divided into three categories: blade type self suction centrifugal pumps, positive displacement self suction centrifugal pumps, and other types of pumps. Most enterprises in our country rely on single-stage absorption self suction centrifugal pumps, which are one type of blade self suction centrifugal pumps. This type of pump works by relying on the pressure generated by the fluctuation of the blades when the impeller rotates at high speed to transport liquid

At the same time, other types of self suction centrifugal pumps have different working characteristics and usage methods, so corresponding changes need to be made in energy conservation. Overall, the main way to save energy for self priming centrifugal pumps is to promote the matching between the pump and the pipeline, and to achieve full opening of the outlet valve of the pump as much as possible, thereby reducing energy consumption caused by mutual adjustment with the pipeline. The first thing to determine is whether energy conservation measures need to be taken for self suction centrifugal pumps. Therefore, if the outlet valve of the self suction centrifugal pump consumes too much energy, the implementation of energy-saving measures should be immediately considered. When determining the energy consumption of a self suction centrifugal pump, a serious and cautious attitude should be taken to conduct highly accurate measurements. Theoretical calculation values should be used as the basis for calculation, combined with actual measurement data for correction, and the method of combining theory with practice should be adhered to