Flow loop apparatus to study the effect of solvent, temperature and additives on asphaltene precipitation

A detection technique was developed for the onset of asphaltene precipitation based on the measurement of pressure drop across an in-line filter. An in-line filter of a nominal size of 60 μm was used to capture the precipitate and thus detect the onset, which was indicated by a dramatic increase in the pressure drop across the filter. Experimental runs required only 4 h to complete and the apparatus is capable of testing opaque samples at high temperatures and pressures. The effects of solvent type and temperature on the onset of precipitation were investigated for Athabasca and Cold Lake bitumens. For both bitumens, the qualitative behavior of the onsets with solvent type (carbon number) and temperature were similar, displaying an increase in the onsets at lower carbon number and temperature values and decrease at the higher values. To identify the effectiveness of resin type compounds to dissolve asphaltenes, 20 g of various aromatic, hydrogen donor, heteroatom and surfactant compounds were added to 100 g samples of Athabasca and Cold Lake bitumens. It was found that aromatic and hydrogen donor compounds increased the onset ratio by a slight to moderate degree, heteroatom compounds increased the onset ratio by a moderate degree, whereas surfactants increased the onset ratio by the highest degree.