Cooling Oil Unit (also known as Oil Cooler), a core temperature control device for industrial lubrication/hydraulic systems, is most widely used in power plant steam turbines. It removes heat from the oil through heat exchange, maintaining stable oil temperature and protecting equipment.

Operating Principle

The mainstream is shell-and-tube type: cooling water flows through the tube side, while high-temperature lubricating oil flows through the shell side (baffles force the oil to flow in an S-shape, enhancing heat exchange); heat is transferred from the oil side to the water side through the tube walls, and the oil temperature is controlled by adjusting the flow rate of the cooling water (usually controlling the entering bearing oil temperature at 35-45℃). The cooling medium is mainly circulating water, with some models using air cooling for water-scarce situations; plate-type cool oilers rely on the thin film flow between metal plates for rapid heat exchange, which is more efficient but also more costly.

Structure and Classification

Core Components: Shell, Heat Exchanger Tube Bundle (Copper / Stainless Steel Tubes), Upper and Lower Water Chambers, End Caps, Baffle Plates, Sealing System (O-rings / Metal Gaskets to prevent oil and water leakage), with interfaces for oil/water intake/output, exhaust, drainage, and temperature/pressure measurement ports.

Installation Method

Horizontal: Low pressure drop, resistant to water hammer, suitable for high flow rates.

Vertical: Compact footprint, flexible installation.

Structure Type

Tube-in-tube (traditional mainstream, cost-effective, reliable)

Plate-type (high heat exchange efficiency, compact in size, suitable for large-scale units)

Finned tube (enhanced heat transfer, suitable for high oil viscosity conditions).

Primary Application Scenarios

Power: Turbine / Generator bearing lubricant cooling, Coal mill / Air oil system;

Industrial: Hydraulic stations, air compressors, ship main engines, metallurgical rolling mill lubrication/hydraulic oil cooling.

Chemical Industry: Temperature control for recirculating oil system.

Common Faults and Maintenance Tips

Scaling/Blocking: Leads to reduced heat exchange efficiency and higher oil temperature; requires regular water-side backwashing, chemical cleaning, and oil-side filtration to remove impurities.

Leakage (Oil-Water Mixing): Oil pressure is usually higher than water pressure; aging seals and corroded tube plates can easily allow water to leak into oil. Regular inspection of seals and pressure testing for leaks is required.

Routine Inspections: Monitor incoming/outgoing oil temperature, oil pressure, and coolant water volume; ensure exhaust is unobstructed to avoid airlock.

Standby cool oil cooler: Large units commonly use double-row parallel configuration for easy online switching and maintenance.

Key Selection Parameters

Cooling water volume, oil flow rate, inlet and outlet oil/water temperatures

Work pressure, temperature, and oil viscosity.

Heat exchange requirement (kW), dirt factor, pressure drop limit;

Installation space, cooling medium supply conditions.