A Comprehensive Plan for Energy Conservation and Consumption Reduction of Chemical Pumps

In chemical production, energy consumption optimization of centrifugal pumps is the key to cost reduction and efficiency improvement. Improving pump system efficiency not only relies on advanced control technologies, but also depends on refined maintenance processes. Based on Omron Tech Pumps's scientific research practices and production experience, this paper elaborates on how to achieve comprehensive energy conservation by reducing hydraulic losses, volumetric losses and system leakage.

I. Improve Maintenance Processes to Reduce Hydraulic Losses

Hydraulic loss is the primary factor affecting the efficiency of chemical pumps. Through refined maintenance, friction, collision and vortex losses of fluid during flow inside the pump can be significantly reduced.

1.1 Improve Flow Passage Smoothness

During maintenance, rust, scale, burrs and flash on impellers and flow passages shall be ground and polished to make the surface roughness reach above △4. Focus on treating the impeller inlet, outlet and guide vane parts—these areas have the greatest impact on efficiency. Grinding should be conducted until the metallic luster is exposed, and the original hydraulic profile must not be damaged, otherwise energy loss will be aggravated instead.

1.2 Optimize the Matching Surface Between Impeller and Pump Casing

Simultaneously grind the outer wall of the impeller and the inner wall of the pump casing to remove rust and sediments, and ensure that the impeller runout meets the standard. This measure can effectively reduce disc friction loss and improve mechanical efficiency.

1.3 Reduce Fluid Impact at Impeller Outlet

During installation, it is necessary to ensure the alignment of the flow passage centers of the impeller and guide vane, and the impeller flow passage shall not exceed the scope of the guide vane. Meanwhile, strictly control the axial dimension tolerance between the rotor and pump casing, and closely monitor the axial displacement during operation—excessive displacement will lead to intensified impact of fluid at the outlet and cause unnecessary kinetic energy loss.

II. Reduce Volumetric Losses and Improve Internal Sealing Performance

Volumetric loss originates from internal leakage of liquid from high-pressure areas to low-pressure areas, which directly affects the volumetric efficiency of the pump.

• Reduce key sealing clearances: The radial clearances of impeller front and rear wear rings, guide vane wear rings, throttle sleeves in front of balance discs and other parts should be as small as possible, and high-hardness, wear-resistant materials (such as stainless steel, tungsten carbide) combined with heat treatment processes should be adopted to extend the service life of seals.
• Standardize cold start procedures: Insufficient pump warming will lead to large temperature difference between the upper and lower parts of the pump body, causing bow deformation of the rotor and further expanding the sealing clearance. Be sure to fully warm up the pump in accordance with the regulations to avoid abnormal wear during the start-up phase.
• Monitor the drain pressure of the balance disc in real time: During normal operation, if the fluctuation of drain pressure behind the balance disc far exceeds the inlet pressure, it indicates that internal leakage has intensified and maintenance is required in a timely manner.
• Adjust the load smoothly: Avoid severe fluctuations in feedwater pressure, prevent excessive axial movement, and protect the seal pair from impact wear.

III. Eliminate External System Leakage

Even if the pump itself is highly efficient, the energy-saving effect will be greatly reduced if the system valves leak.

• Strictly inspect various drain/drainage valves: Including pump body drain valves, boiler blowdown valves, emergency drain valves, etc. During normal operation, there should be no temperature sensation behind the valves (cool to the touch); if the valves feel hot, it indicates internal leakage and immediate treatment is required.
• Repair the leakage of recirculation valves: Recirculation valves are prone to erosion damage under high pressure differences, leading to a large amount of high-pressure feedwater flowing back to the deaerator and doing useless work. It is recommended to regularly maintain or replace high-performance valves, and close the recirculation valves in a timely manner after the pump operates normally.
• Ensure the tightness of check valves of standby pumps: The outlet valves of pumps put into parallel standby are kept open; if the check valves are not tight, high-pressure water will flow back and even cause reverse rotation of the pumps. This not only wastes energy, but also threatens equipment safety. If necessary, only keep the outlet of one pump fully open for standby, and close the others to reduce leakage paths.

IV. Apply Variable Frequency Controllers: Realize On-demand Energy Supply

In addition to refined maintenance, the adoption of modern technologies and concepts for system upgrading can bring more significant energy-saving benefits.

4.1 Accurate Selection: Lay the Foundation for Energy Conservation from the Source

This is the most easily overlooked but crucial step. During selection, it is necessary to ensure that the rated flow and head of the pump are highly matched with the actual working conditions, so that the pump operates near its Best Efficiency Point (BEP).

4.2 Apply Variable Frequency Control: The Most Efficient Energy-saving Tool

Variable frequency speed regulation technology is currently recognized as the most effective energy-saving measure. By installing frequency converters and adjusting the pump speed according to actual demand, the extensive mode of flow control through valve throttling can be completely eliminated.

• Significant advantages: Variable frequency speed regulation has high efficiency and a wide range (up to 1-100%), especially suitable for working conditions with large load fluctuations. Since the power consumption of the pump is proportional to the cube of its speed (P ∝ n³), a slight reduction in speed can bring huge energy-saving returns.
• Convenient transformation: The transformation of the original motor does not require motor replacement, and the frequency converter can also be used as a soft starter to reduce the starting current and extend the service life of the equipment. When the frequency conversion device fails, it can be switched back to the main circuit for power supply without affecting production.

Conclusion

Energy conservation of chemical pumps is a systematic project integrating refined maintenance, standardized operation and intelligent upgrading. From grinding a blade to installing a frequency converter, every link contains huge energy-saving potential. Take action immediately and apply these strategies to your production practice—Omron Tech Pumps (http://www.Omron Tech Pumps.com) has always been committed to providing efficient, intelligent and green solutions for industrial fluid systems. Choosing Omron Tech Pumps can not only bring considerable economic benefits, but also be a solid step for enterprises towards green, efficient and sustainable development.