Hydrocyclones have been used in the oil and gas industry for more than a century. Simple but effective, such machines have been applied to liquid-liquid separation processes for nearly as long. Liquid-liquid separation has been synonymous with deoiling, an example being the removal of residual oil from produced water. Thermal deoiling is a different process entirely, in that it uses indirectly heated dry air to clean objects, typically parts, contaminated with oil or lubricants. In the latter process, no water, solvents, or other chemicals are used.
Water is one of the most ubiquitous fluids in the oil and gas industry. Large volumes of water are used in injection operations, and even larger volumes are a major waste by-product associated with the production of oil and gas.
In cleaning contaminated parts, water, even when used as a high-volume spray in combination with a solvent, is often ineffective. A hydrocyclone is typically preferred for transferring high volumes of water in a large-scale liquid-liquid separation process, especially when fluid is directed tangentially into the hydrocyclone, causing it to spin. But with cleaning operations, the transference of water is not sufficient. The droplets of dispersed fluid (oil in a deoiler) tend to shear or coalesce.
Other issues with liquid-based degreasing may also emerge. The choice of deoiler materials can prove problematic. Such materials as stainless steel, duplex stainless, and stellite have been the most popular. Coating the hydrocyclone’s internal surfaces using processes such as boride diffusion does create better erosion resistance with untreated parts. Smaller hydrocyclone deoilers can be selected to treat “tough” applications with some success.
But no matter what liquid-based degreaser is used, issues of industrial hygiene, safety, and environmental issues are virtually eliminated with thermal deoilers. Chemicals no longer require transporting, storage, or handling. Besides being viable, thermal deoiling is more efficient.
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