Fractional Condensation of Bio-Oil Vapors

The research project described in this thesis deals with an investigation on the fractional condensation of bio-oil vapors to improve the separation of some of the key components of the bio-oil and, consequently, improve the properties and the value of each of the separated product streams. In the first part, the separation of a mixture of three model compounds of bio-oil from a vapor and carrier gas stream was investigated with the help of a series of three condensers maintained at different temperatures. The practical performance of the fractional condensation train was improved by comparing the experimental results with the theoretical results predicted by the HYSYS modeling tool. It showed that good heat transfer and mixing was essential, and could be achieved by using condensers with a cyclonic entry. It also showed that a good demister was essential to achieve effective separation. The second and third parts of the investigation focused on the fractional condensation of actual bio-oil vapors produced from the pyrolysis of two different biomasses: birch bark and Kraft lignin, respectively. In both cases, the temperatures of the condensers were optimized in order to separate the water present in the bio-oil vapor stream and increase the quality and the stability of the remaining bio-oil. The condenser train consisted of a condenser-cum-electrostatic precipitator (C-ESP) installed between two cyclonic condensers. The water content of the fractionated bio-oil was found to be less than 1 wt% with both biomasses. In case of Kraft lignin, the phenolics recovered in different bio-oil fractions were also analyzed. The effect of pyrolysis temperature on the fractionated bio-oil yield and characteristics was investigated