INVERTO

In order to optimize the use of the limited potential of lignocellulosic biomass, it seems necessary to improve the economic and environmental performances of the conversion processes. This could be done thanks to a synergetic approach coupling energy and chemical recovery in the same process. This approach may be applied to torrefaction. Torrefaction, as a thermal pretreatment of biomass, produces a solid bioenergy carrier, which can be used in particular in Biomass-to-Liquid processes. Condensables are torrefaction co-products that are considered at the moment as problematic components. They are either eliminated or in the best case burnt to produce some energy for the process. Several thousand tons of these condensables are produced each year by a single medium-size torrefaction unit and they are constituted of numerous valuable components that are identical to the components used in chemical industry. Using this “natural” synthesis of molecules appears therefore as an attractive option, which could significantly increase the global process performance. However, to our knowledge, this option has never been explored up to now. In this context, the objective of the INVERTO project is to study the feasibility and viability of such a process of chemical recovery of the condensable co-products obtained by lignocellulosic biomass torrefaction into highly valuable molecules. The working plan is separated into six tasks. The first one aims at coordinating the whole project. The aim of task 2 is to determine as accurately as possible the composition of condensables obtained from a representative panel of biomasses, in order to select the condensable species with a high potential of valuable recovery for chemical industry and to specify the associated specifications on these products. To achieve this goal, improvement of the mass balance closure will firstly be done in two lab-scale torrefaction facilities with several different analyzers, among which some will be specifically developed. Then a detailed characterization of the molecules will be done. In task 3 the torrefaction parameters will be optimized in order to increase the yield of the selected molecules. For this purpose, a kinetic model will be developed thanks to experiments in a thermobalance coupled with a gas analyzer. Tests of solid characterization will be done to check the quality of the solid product obtained under these conditions. Task 4 will be devoted to a critical issue of the process, which is the extraction and isolation of the valuable molecules according to the specifications defined in task 2. Experimental work will be done to acquire some “process” data as well as some lab-scale tests. Simulation work will also be done to define the optimal sequence of unitary processes. Based on the results of tasks 3 and 4, a validation of the process at the pilot scale will be done in task 5. Condensables will be produced in a torrefaction pilot; then they will be treated in a separation pilot and characterized in relation with their further recovery. These results will bring data to be used in task 6. In this task, a techno-economic assessment of the process will be done, as well as a life cycle analysis. Studies of toxicity, ecotoxicity and sustainability of the products will also be performed. Based on these final results, conclusions will be drawn regarding the process performances and its potential of industrial implementation into biorefineries. A comparison with the standard process of torrefaction will also be done. To succeed in this project, the consortium is based on four partners which are famous experts in each main step of the process.