Context
This project consists in studying the energy aspects of the carbonization of lignocellulosic matters and the quality of its products in semi-continuous retort kiln.The think a wood charcoal producer wonders about today is : “how to produce a charcoal of certified quality at a reasonable price, while respecting the environment ?” This requires to control the parameters linked to carbonization (operational parameters related to the feedstock and the carbonization reactor). A carbonization technology allows to master these parameters, while being of a reasonable investment, and is characterized by a very good control of gaseous emissions : the semi-continuous retort kiln. The Department has therefore decided to focus its researches on this technology.
The optimization of carbonization in semi-continuous retort kiln requires to master solids and gas's mass flux as well as gaseous energy flows.
Objectives
In order to reach this skill, the study lead by the Department aims at :- determining the bilans and mass flux of carbinization in relation with the quality of the charcoal obtained, according to the parameters of carbonization ;
- predicting the energy flux of carbonisation in semi-continuous retort kiln, according to the parameters of carbonization ;
- from a wood charcoal quality obtained, defining the characteristics of the feedstock allowing to optimise the energy flows.
Description of tasks
To reach these objectives, the Department leads some experimentations in thermobalance kilns. The variation factors are :- the type, moisture content, size and shape of the feedstock ;
- the final temperature and the residence time at final temperature ;
- the heating rate of the reactor.
The analysis equipment appeals to infrared spectrometry, paramagnetism, , thermal conductivity, elementary analysis as well as to conventional analyses of the wood charcoal. The analysis of the results requires an original statistical method, allowing to take into account the carbonization dynamics (gaseous and liquid mass flux, energy flows).
Results obtained
Carbonization tests put forward the prominent importance of wood moisture content on mass and energy flows. The other physical parameters – bulk density, size, shape – only intervene in a secondary way. The heating rate is also a determining factor of the mass and energy flows.The results of carbonization tests lead to the phenomenological modelling of mass and energy flows of the total volatile matter produced by the carbonization of wood in retort kiln. This modelling is based on the utilization of the symmetrical logistic function. The model of mass flow is applied to the industrial pilot kiln developed in the CRA-W. This application confirms the prominent effect of wood moisture content on the economy of carbonization.
Contribution
Agricultural Research Centre – Wallonia (Gembloux) – Biometry Section for the statistical analysis of the results, Data management and Agro-meteorology, Farming Systems Unit for the elementary analyses (C, H, O, N)Partners
Catholic University of Louvain - TERM Unit. Faculty of Agronomical Sciences of Gembloux - Forest Management and Economy Unit, General and Organic Chemistry Unit, Physics Unit.Funding
- CRA-W - Walloon Agricultural Research Centre
