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 precipitati on based on the measurement of pressure drop across an in-line filter. An i n-line filter of a nominal size of 60 mu m was used to capture the precipit ate and thus detect the onset, which was indicated by a dramatic increase i n 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 bi tumens. For both bitumens, the qualitative behavior of the onsets with solv ent type (carbon number) and temperature were similar, displaying an increa se in the onsets at lower carbon number and temperature values and decrease at the higher values. To identify the effectiveness of resin type compound s to dissolve asphaltenes, 20 g of various aromatic, hydrogen donor, hetero atom 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 compo unds increased the onset ratio by a moderate degree, whereas surfactants in creased the onset ratio by the highest degree. (C) 1999 Elsevier Science B. V. All rights reserved.