10. Procedures for Addressing Severe Coking and Carbon Deposition in Air Compressors

The Hazards of Coking and Carbon Deposition in Air Compressors

When an air compressor operates for extended periods under high-temperature conditions or with inadequate lubrication, the lubricating oil is highly susceptible to oxidation and degradation, leading to severe coking and carbon deposition. These deposits can clog oil passages and reduce the heat-exchange efficiency of the cooler, causing the discharge temperature to rise abnormally. If left unaddressed, this not only increases equipment energy consumption but may also result in serious failures, such as rotor seizure.

Safety and Preparatory Measures Before Processing

Before performing any maintenance work, ensure that the site environment is safe and have the necessary tools and materials ready.

• Shutdown and Pressure Relief: Disconnect the equipment from the power supply and hang a warning sign; ensure that all internal system pressure has been fully relieved to prevent operation under pressure.
• Preparation of Tools and Materials: Prepare dedicated disassembly and assembly tools, an environmentally friendly carbon‑deposit cleaner, a high‑pressure water gun, clean non‑woven cloths, as well as new seals and filter elements.
• Waste oil collection: Prepare sufficient waste oil collection containers, and properly manage the discharged used lubricating oil and cleaning waste liquids in compliance with environmental protection requirements.

Core Disassembly and Cleaning Steps

For severe coking and carbon deposition, the core components must be thoroughly disassembled and cleaned.

1. Cleaning of the cooler and oil circuit pipelines

Remove the cooler and perform a soak-and-circulation cleaning using dedicated descaling and carbon‑deposit removers. For stubborn carbon deposits inside the tubes, combine high‑pressure physical flushing with chemical soaking until the effluent is clear and free of impurities; finally, rinse thoroughly with clean water and blow dry.

2. Cleaning of the Host Rotor and Cavity

If severe coking has occurred inside the host, the unit must be disassembled. Carefully remove carbon deposits from the rotor surface and within the housing using a soft scraper or a copper brush; never use hard metal tools to avoid damaging the rotor profile. After cleaning, rinse with a dedicated cleaning agent and apply a clean lubricant to provide rust protection.

3. Decarbonization of Valves and Associated Components

Disassemble components such as the minimum pressure valve, temperature control valve, and check valve, and immerse them in a cleaning agent. Remove carbon deposits from the valve spools and seats, and inspect the seals for aging and deformation; if necessary, replace them with new sealing assemblies.

Assembly, Filling, and Commissioning

After cleaning, reassemble all components to specification using the prescribed torque values and assembly procedures, and replace the oil–air separator element, oil filter, and air filter with new ones.

• Add new oil: Inject fresh lubricating oil that meets the equipment’s specified grade and viscosity, ensuring the oil level remains within the normal range.
• Turntable inspectionBefore starting, manually rotate the main unit’s coupling several revolutions to ensure smooth operation, with no binding or unusual noises.
• Trial Operation Monitoring: Perform a jog start of the equipment and monitor oil pressure and exhaust temperature. Under full-load operating conditions, closely track whether all parameters have returned to their specified ranges and inspect all connections for leaks.

Daily Prevention and Maintenance Recommendations

Dealing with severe coking and carbon deposition is costly; routine preventive measures are the key to ensuring stable equipment operation.

• Strictly control the operating temperature.Ensure the cooling system operates efficiently by regularly removing dust from the cooler’s surface to prevent the equipment from being exposed to high temperatures for extended periods.
• Proper fuel usage and regular oil changes: Only qualified, dedicated lubricating oil must be used. Mixing oils of different brands or grades is strictly prohibited, and lubricating oil must be replaced in strict accordance with the maintenance schedule.
• Improve the operating environmentEnsure adequate ventilation in the compressor room to lower ambient temperatures and minimize the ingress of airborne dust and corrosive gases into the system.