Because of the high relative densities, asphaltenes precipitate out of crude oil in storage. The solids form a layer of tacky, gummy sludge on the bottom of the storage tank that grows over time and eventually must be removed. The tank cleaning process is typically long and difficult and results in large volumes of hazardous waste that must be disposed at a hazardous landfill via incineration at a very large cost to the client. Asphaltenes also deposit in process equipment such as de-salters, tower bottoms, and heat exchangers. These deposits can create process inefficiencies including heat transfer losses and process upsets, and are typically removed by mechanical methods such as hydro-blasting. All of this is a maintenance expense and a production loss to the customer.
While it is a dispersant, FQE Solvent-H also works as a solvent to dissolve the asphaltenes. While any aromatic solvent can dissolve asphaltenes, they do not suspend asphaltenes, leaving the asphalt to re-precipitate out of the solvent and form a hard layer of asphaltenes in a vessel.
FQE Solvent-H is a non-combustible liquid with a flash of over 116°C (240°F). It is intended to be applied at concentrations ranging from 2–20% in a carrier hydrocarbon liquid. In a typical refinery application, FQE Solvent-H would be diluted in light cycle oil (LCO), atmospheric gas oil (LGO), light vacuum gas oil (LVGO), or diesel oil. Any of these hydrocarbon streams is acceptable as the carrier fluid for FQE Solvent-H application. This mixture is heated to 60 – 82°C (140-180°F) and circulated in the vessel or through piping.
FQE Solvent-H dissolves asphalt. It can remove fouling deposits in process equipment and restore system efficiency. It also removes heavy deposits in oil storage tanks. This yields two very important results: it lowers disposal costs, and eliminates the need for personnel entry into a confined space, which results in a much safer tank cleaning process.
FQE Solvent-H is valuable for its capability to dissolve asphaltenes. But many other solvents, like xylene, can dissolve asphaltene, too. What sets FQE Solvent-H apart is its asphaltene dispersion capability. By preventing asphaltenes from re-precipitation, the dissolved liquids not only eliminate a disposal expense, but become a valuable recovered hydrocarbon source, which can be reintroduced into the refining process without concern. No catalyst poisons. No process upsets.
In general, refineries use hot solvents like diesel to flush / dissolve asphaltenes from equipment. The solvent / dissolved solids are put into storage, where the asphaltenes precipitate out as a solid that must be addressed later. The flushing process never removes all of the asphalt deposits. The residual asphalt is mechanically removed in the pre-maintenance cleaning. For storage tank accumulations, the asphalts are mined out with bulldozers for disposal.