Deep separation method and processing system for the separation of heavy oil through granulation of coupled post-extraction asphalt residue

#The invention relates to a process and equipment for deep processing of heavy oil in the petroleum industry. More specifically, the invention relates to a deep separation method for heavy oil components using a solvent and separation of the solvent at low temperatures through granulation of coupled post-extraction asphalt residue.

#Solvent deasphalting is a technique in the petroleum industry to remove a heavy component asphalt from heavy oil, applicable to heavy oil and oil-sand bitumen, and the atmospheric and vacuum residua resulting from the processing of crude oil. The density at 20° C. of these heavy oils is typically greater than 0.934 g/cm3 (API less than 20) or the boiling point is above 350° C. The deasphalted oil after the removal of asphalt is mainly used as the base oil for lubricants or as the feedstock for subsequent processing such as catalytic cracking or hydroprocessing. The asphalt removed can be used for road pavement and construction materials or as fuel.

#The solvent used for the deasphalting process for lubricants is normally propane or butane while for catalytic cracking or hydroprocessing feedstock butane or pentane fractions are often used as solvents. The resultant asphalt is mainly used as fuel or the asphalt component for road construction. The existing deasphalting techniques use either a two stage or a three-stage process. In the first stage, the mixture of the solvent and the heavy oil becomes two phases with the light phase being composed of solvent and deasphalted oil (DAO) and the heavy phase being asphalt phase comprising deoiled asphalt and a certain amount of solvent. After discharging from the extractor, the asphalt phase is heated in a heater to a relatively high temperature to flash off most of the solvent and the remaining solvent is further removed by gas stripping, resulting in deoiled asphalt. In the second stage, the DAO phase is heated to close to the critical point of the solvent or supercritical condition to recover most of the solvent. Steam is used to further strip off the remaining solvent to produce DAO. When a three-stage process is applied, DAO is heated to a higher temperature or reduced to a low pressure to lower the dissolving capacity of the solvent so that the heavier fraction of DAO (resin) settles in the second stage separation. The DAO is heated again to a higher temperature or reduced to a lower pressure for third stage recovery of solvent. The resin and the DAO are stripped to further remove the remaining solvents, resulting in the so-called heavy DAO (or resin) and light DAO.

#FIG. 1 is a flowsheet of the process and equipment of the preferred embodiment of the present invention.

#The following are more detailed discussions of the current inventions in association of the figures and the actual schemes of the embodiments.

#The solvents used in this invention are mostly C4, C5 and C6 alkanes or their mixtures, which can contain butane, pentane, hexane and their isomers with the required pseudo critical temperature being in the range of 120-240° C. Pseudo critical temperature Tc is calculated using the equation

#Tc = ∑ i = 1 n ⁢ x i ⁢ Tc i , where xi is the molar fraction of solvent component i, Tci is its critical temperature in Celsius and n is the number of components contained in the solvent. The technical processes are as follows.