A de-asphalter is a piece of heavy-duty industrial equipment found in many oil refineries and fuel processing facilities. These machines are used in oil distilling, which is the process of extracting usable products from a barrel of crude oil. A standard de-asphalter is used to manufacture asphalt, which is widely used to pave roads and other surfaces throughout the world. These machines also produce a number of additional by-products that can be used as fuel sources or lubricants.
To understand how a de-asphalter works, it's helpful to understand how the oil distillation process works. Refineries start by subjecting the entire barrel of crude oil to a process known as vacuum distillation. This divides the oil into many products, each with varying levels of purity and contaminants. The more purified products of distillation are sent forward for further refining, where they are made into gasoline and liquid propane. Some of the more contaminated products, such as the heavy sludge found on the bottle of the barrel, are transported to the de-asphalter for additional processing.
The majority of de-asphalter systems throughout the world rely on a solvent-based de-asphalting process. These machines consist of large metal drums filled with a hydrocarbon solvent like propane or butane. As the sludge by-products of vacuum distillation are deposited in these drums, many of the natural gases within the sludge dissolve. The solid asphaltenes retain their solid state, and can be extracted from the machine and used to produce asphalt. The propane or butane solvents remain in the drum for reuse.
After being removed from the de-asphalter, the asphaltenes are subject to oxidation, which gives them the properties needed for use in paving. A certain amount of waste sludge at the bottom of the de-asphalter cannot be processed any further, and must be sent to an industrial landfill for disposal. Resinous by-products produced during oxidation are separated from the asphalt to become lubricant or grease used for machinery and vehicles.
The dissolved gases and some remaining resins within the de-asphalter are also collected and processed even further. These gases and resins are subject to a process known as hydrocracking, which helps to remove any remaining impurities and transforms these materials into de-asphalted oil (DAO). De-asphalted oil serves as a common fuel or lamp oil, and is a slightly less refined version of kerosene. The high number of impurities remaining in DAO cause it to burn fairly dirty, and have led many to seek out cleaner-burning fuels.