How to choose oil-water-free lubricated air compressor for cement production

In the cement production process, the compressed air system is the core power source to ensure equipment operation, process stability and product quality. Due to the special nature of cement production (high temperature, dust, corrosive environment), the reliability, energy efficiency and air quality of air compressors are extremely high. Due to its unique advantages, oil-free lubricated air compressors have gradually become the preferred choice in the cement industry. Based on international standards (ISO, IEC, EN) and combined with cement production process requirements, this paper systematically analyzes its technical parameter selection, application scenarios and economic benefits.

1. Cement production process and the necessity of oil-free lubrication air compressor

The cement production process mainly includes:Raw material crushing, raw meal grinding, calcination (kiln system), clinker cooling, cement grinding and packaging。The characteristics of the demand for compressed air in each link are as follows:

1. Raw material treatment and grinding
   • demand characteristics: In high-dust environments, pneumatic valves and conveying equipment require stable and dry compressed air.
   • Advantages of oil-free air compressor: 100% oil-free air (complies with ISO 8573-1 Class 0 standard) to avoid mixing oil and dust and clogging the filter element.
2. Calcination and cooling process
   • demand characteristics: The pneumatic actuators of kiln head/kiln tail burners and coolers need compressed air that is resistant to high temperatures and anti-pollution.
   • Advantages of oil-free air compressor: Water lubrication technology reduces exhaust temperature (usually ≤40°C) and reduces the risk of seal aging caused by high temperatures.
3. Cement packaging and bulk
   • demand characteristics: The packaging machine injection system must be free of polluting air to prevent oil from being mixed into cement from affecting strength and environmental compliance.
   • Advantages of oil-free air compressor: Eliminate oil residues and meet food-grade contact standards (such as FDA/EC 1935/2004).

2. Core selection parameters of oil-water-lubricated air compressors (based on international standards)

1. Exhaust volume and pressure
   • Displacement (m³/min): Calculated based on the total air consumption of the cement plant (based on the number of pneumatic equipment × air consumption of single unit +20% redundancy), it must comply with ISO 1217 volumetric flow test standard.
   • Working pressure (bar): 7-8 bar is needed for raw meal grinding, 6-7 bar is needed for packaging system, and multi-pressure section adjustment (such as VSD frequency control) is needed.
2. energy efficiency rating
   • Specific power (kW/(m³/min)): According to ISO 50001 requirements, it needs to be ≤6.5 kW/(m³/min)(7 bar working conditions), which is 10%-15% better than traditional oil machines.
   • heat recovery efficiency: The water lubrication system can recover 80% of the compression heat for waste heat power generation or raw meal drying.
3. Water lubrication system parameters
   • water quality requirements: Comply with ISO 3690 industrial water standard, conductivity ≤50 μS/cm, hardness ≤100 ppm.
   • Water consumption (L/h): Fully enclosed cycle design, water consumption ≤0.5 L/h (taking the 37kW model as an example).
4. environmental adaptability
   • Intake air temperature (℃): Supports wide temperature operation from-10 ° C to 50°C (EN 1012 standard).
   • protection grade: IP66 (dust and water resistance) and EX explosion-proof certification (dust explosion environment).

3. Potential risks of not using oil-free lubricated air compressors

1. Process failures caused by oil contamination
   • After the oil is mixed with the raw meal, a crust is formed in the preheater (accumulation of material in the C5-C1 cyclone), which reduces the thermal efficiency by 10%-20%.
   • The nozzle of the packaging machine is blocked by oil pollution, and the failure rate increases by 30%-50%.
2. Operation and maintenance costs surge
   • Frequent replacement of oil filters and oil-gas separators (every 2000 hours per time) will increase the annual maintenance cost by US$20,000 – 30,000 (taking the 100kW model as an example).
   • Oil mist emissions require additional purification equipment (EPA Tier 4/EU IED Directive requirements).
3. Environmental and legal risks
   • Oil mixed into cement products may lead to excessive heavy metals (such as PAHs and polycyclic aromatic hydrocarbons) and violate REACH regulations or GB 31893-2015 standards.

4. Economic benefits of oil-free lubricated air compressors

1. Direct cost savings
   • Eliminate annual consumption of lubricating oil (37kW models save 400-600 liters per year) and extend the maintenance cycle to 8000 hours.
   • The heat recovery system can reduce coal consumption by 1.5-2.5 kg/ton of clinker (calculated based on 0.5 MW waste heat power generation).
2. Improved indirect benefits
   • The product pass rate increased by 0.3%-0.5%(oil-free air ensures packaging tightness).
   • Reduce carbon emissions by 15%-20%(compliant with ISO 14064 carbon footprint certification).

5. Technical comparison between oil-free lubrication and oil-free air compressor

VI. Conclusion

With its zero-pollution, high energy efficiency and low maintenance characteristics, oil-free lubricated air compressors perfectly meet the stringent requirements for reliability and sustainability of cement production. When selecting models, it is necessary to focus on matching exhaust volume, pressure, energy efficiency and environmental adaptability parameters, and at the same time comply with international standards such as ISO and IEC. In the long run, its full life cycle cost advantage will help cement companies achieve the dual goals of cost reduction, efficiency improvement and green transformation.