What causes high load on screw air compressors? 

Screw air compressors are core power equipment in industrial air supply systems. Frequent problems during long-term operation, such as excessive load, motor overload, soaring exhaust pressure, and abnormally high energy consumption, are common pain points in equipment operation and maintenance for industrial and mining enterprises. Operating equipment under high load for extended periods not only accelerates rotor and bearing aging and wear, leading to high-temperature trips and frequent shutdowns, but also significantly increases electricity costs and shortens the overall lifespan of the equipment. Accurately identifying the causes of excessive air compressor load is crucial for reducing load, saving energy, and ensuring stable operation.

This article, based on on-site operation and maintenance experience, systematically analyzes the various core reasons for excessive load on screw air compressors.       

I. Excessive Air Load, Exceeding Equipment Rated Operating Conditions

Excessive on-site air demand is the primary external cause of high air compressor load. After some enterprises expand their production lines and add pneumatic equipment, the total air consumption exceeds the rated air production capacity of the air compressor, causing the equipment to operate at full load or even overload for extended periods. Simultaneously, multiple leaks in the plant‘s pipelines, aging pneumatic equipment, and sudden surges in air demand can cause a sharp fluctuation in air load. To maintain the set pressure, the equipment continuously applies high-frequency loads, directly resulting in persistently high operating loads and easily triggering overload protection.

II. Intake and Filter Blockage, Increased Operating Resistance

Blockage in the intake system is a common problem causing falsely high equipment loads. If the air filter is not cleaned or replaced for a long time, a large amount of dust, lint, and impurities accumulate on its surface, causing blockage in the intake passage and a significant increase in intake resistance. Insufficient air intake from the air compressor reduces the efficiency of the compressor unit. To match the air pressure, the motor needs to continuously increase its power output, ultimately leading to a surge in equipment operating load. In addition, bends or blockages in the intake pipe, or jammed or incompletely opened intake valves, will further increase intake resistance and increase the operating load on the equipment.

III. The lubrication system is abnormal and increases the mechanical load of the airend.

Abnormal lubricating oil conditions will directly increase the mechanical friction resistance of the main engine, resulting in high equipment load. Aging and deterioration of lubricating oil, excessive oil viscosity, and excessive oil impurities will lead to poor lubrication effect of the rotor, bearings, and meshing parts, and a significant increase in mechanical friction resistance. At the same time, clogged oil filters and poor oil circuits will cause insufficient oil supply, local dry grinding of the main engine, and a sharp increase in motor drive load. If the special air compressor lubricating oil is not replaced for a long time, it will also cause the main engine to freeze and the temperature to rise too fast, further increasing the operational burden of the equipment.

IV. Cooling system failure, causing high temperature and high load

Failure of the cooling system will cause the equipment to operate at high temperatures, which will indirectly lead to an abnormal increase in load. Dust and oil accumulation on the surface of the radiator, failure of the cooling fan, and blockage of the air duct will lead to poor heat dissipation of the equipment and the exhaust temperature of the airend will continue to exceed the standard. In high temperature environments, the compressed air density changes greatly, making compression more difficult. High temperatures will aggravate the abnormal viscosity of lubricating oil, cause thermal expansion of components, increase mechanical operating resistance, and keep the equipment in high-load operation. In severe cases, high-temperature overload shutdown may occur.

V. Inappropriate Pressure Parameter Settings Leading to Continuous Equipment Loading

Improper electrical control parameter settings are a significant factor contributing to high loads. Some companies, in order to meet production demands, blindly increase the air compressor‘s loading pressure and reduce the pressure difference between loading and unloading, resulting in a significant shortening of the unloading time and a continuously increasing loading frequency. Simultaneously, malfunctioning pressure sensors and disordered controller parameters can cause inaccurate pressure detection, leading to misjudgments of air demand and prolonged continuous loading, preventing normal unloading and resulting in persistently high overall machine load.

VI. Mechanical Failures of the Main Unit Causing Overload and Operating Resistance 

Wear and failure of core components of the main unit are the core internal causes of high loads. Problems such as screw rotor wear, abnormal bearing clearance, and internal carbon buildup in the main unit increase rotational resistance and reduce compression efficiency. The motor needs to output greater torque to drive the main unit, directly causing increased current and overload. If such mechanical failures are not repaired promptly, they will continuously exacerbate the load problem, ultimately leading to major equipment failures such as main unit seizure and complete scrapping. 

In summary, excessive load on screw air compressors can be mainly categorized into four types: external air consumption, system malfunctions, parameter settings, and mechanical failures. During operation and maintenance, it is necessary to investigate each issue based on the operating conditions, promptly clear blockages, correct operating parameters, repair mechanical faults, and optimize air supply lines. This will reduce the equipment‘s operating load at its source, achieving energy-saving, stable, and long-term operation, and reducing the company‘s operation, maintenance, and electricity costs.