## 3 Results and Discussion
### Discussion  
The achieved results from the experimental campaign showed that mass and energy balances of an extended system lead to promising applications in an integrated biorefinery concept. Nevertheless, qualitative analysis of the different produced fractions portrays meaningful insights into the complete vaporization of the processed stream. As expected, a class-selective separation mechanism happens, leading to the concentration of different  
Figure 10: Mass and energy balances of a commercial-scale plant with a fractional condensation system. Data in black referring to the mass distribution, data in red to the energy distribution. chemical compound classes. The evolution of the concentration of light compounds, water, and the acids in the oil, as well as for sugars and carbonyls obtained in the first and second condenser as a function of the condensation temperature, is significant. The content of light compounds, water, and acids decreases rapidly at an increasing condenser temperature. Based on the specific composition of each fraction, it is possible to identify different routes to maximize the overall performance of the proposed system. Despite there being still open issues regarding the market valorization of the products, the energy assessment showed a high recovery potential for the plant output streams. This \"improved\" system layout, including the results carried out in the fractional condensation tests applied to the fast pine wood pyrolysis, leads to char and non-condensable gases production at about 28% of the initial biomass, while the bio-oil production resulted in a yield up to 70%. In the context of the alternative fuels production, the second fraction collected in the system, due to its relatively low water content and a higher concentration of light organic compounds, represents the best candidate to be further upgraded into hydrocarbon fuels mixtures through hydrotreating/hydrocracking [70; 71]. Although not the main destination envisaged by this study, co-processing in FCC reactors could also be a viable solution for the treatment of this fraction [72] as well as co-refining together with crude oil [73]. Compared to the traditional fast pyrolysis oil obtained in a single-step of condensation, this solution also separates the heavier molecular weight compounds from the main product in the first fraction, facilitating the following downstream upgrading of the second fraction. In particular, the first fraction contains almost equal energy content to the second cut, but the heavier chemical compounds make its upgrading more challenging through a typical biorefinery direct hydrotreatment towards drop-in fuels. Given its nature, this product cannot be intended as a precursor for a subsequent hydrogenation step since its processing would entail high hydrogen consumption other than having a negative effect on the catalyst's lifetime [74]. Its removal can ease the downstream operations to the final fuel product derived from the central fraction. However, other studies in the literature suggest that also this fraction can be hydrotreated through different operating conditions due to the differences in the composition and oxygen content [75]. The presence of sugars and lignin-derived oligomers opens considerations for further utilizations of these compounds via economically rewarding routes. For instance, levoglucosan can be hydrolyzed to form glucose or directly fermented to produce alcohols [76; 77]. Similarly, the water-insoluble lignin-derived oligomers can be potentially used for manufacturing bio-based materials in products such as batteries and supercapacitors applications [78; 79]. Furthermore, the heavier stream can be potentially used for the production of other higher-value co-products or energy production, therefore potentially improving the overall biorefinery economics.