Slop oil is the collective term for mixtures of oil, chemicals and water derived from a wide variety of sources in refineries or oil fields. It is formed when tank wagons and oil tanks are cleaned and during maintenance work or in unforeseen oil accidents.
Slop oil is conventionally stored in large oil lagoons or tanks and disposed of from time to time. It is sometimes also incinerated. This is very energy-intensive, because the mixture has a high proportion of water. Oil lagoons are also a potential hazard to the environment.
GEA Westfalia Separator Group's mechanical separation technology provides an alternative which is as kind to the environment as it is economical. In addition to avoiding costly oil lagoons, the focus is actually also the recovery of valuable oil.
The use of mechanical separation technology is well worth it, as the recovered oil can be returned to the oil production process to produce a secondary raffinate which can easily compare with first-class oils. Slop oil, once a problem and a cost factor, has now become a commodity.
Slop oil can have very different compositions. The oil content, just like the proportion of water, can fluctuate from 10 to 90 percent. The proportion of solids can also vary from one to ten percent, depending on source.
These variations mean that both disk-type separators and decanters from GEA Westfalia Separator are used. The decanters are used primarily when the proportion of solids makes up over five percent of total volume. In the downstream process, the self-cleaning disk-type separators perform the task of polishing the water or the oil phase.
The flow chart illustrates the combined use of separator and decanter. A 2-phase decanter initially removes the solids from the slop oil. The liquid phases (water and oil) which result are passed to a separator which separates the light and heavy liquid phases. Alternatively, a 3-phase decanter can also be used which is able to separate the slop oil directly into the three phases oil, water and solids.