The study of the kinetics of biomass pyrolysis is of great importance, for it constitutes the initial step in the process of combustion and gasification . Knowledge of the kinetics for thermal decomposition of lignocellulose (cellulose, hemicelluse, lignina) materials is a necessary requirement for the design and optimization of reactors, for this is required to know the relevant parameters in the decomposition process as are Ea activation energy , pre -exponential factor k and reaction order n.
Therefore, they are important for the design of product features and establishment of process conditions. For the determination of kinetic parameters taking into account a process with laboratory scale, they can be calculated by thermogravimetric analysis (TGA) significantly enriching the information of the decomposition mechanism used. This technique allows measurement of mass change versus temperature and the results are expressed in the form of curves of weight loss (TGA) and derivative mass loss ( DTG) .
Kinetics of pyrolysis processes is a very important factor to be understood, since it determines the composition of end-products - thus, the utilisation options for this product - as well as, influences the technical parameters of pyrolysis process. This later one has significant effects on the economic feasibility of biomass pyrolysis processes, too. TGA can be a useful method to assess the kinetics of pyrolytic processes, however, it alone will not provide all the necessary information. For the best results, more detailed analysis of both the raw material and the end-products is needed. The analysis of pyrolysis gas can provide also useful information in this issue.
Yes, it is important, but also depending on in what type of process.
For instance the pyrolysis stage in gasification, pyrolysis conditions will affect so much the reactivity of char produced which will then be critical for understanding and controlling a gasifier then. For this case, I do not think it is a good idea to use TGA for pyrolysis study. the conditions in TGA is far too away from the real environment in a gasifier, concerning about heating rate as such.
Pyrolysis can be used for producing liquid fuel by flash pyrolyisis, and also for producing char as main product by low heating rate process. However, TGA, in my opinion, only reflect some low heating rate pyrolysis phenomenon, and not so sufficient to say anything for high heating rate case.
Kinetics of pyrolysis of biomass is important because it tells us how fast a product can be yielded. Generally, kinetics do not provide he composition of end-products because it depends on the composition of raw materials.
kinetics is of great importance for reactor design and scale-up. however, due to the complex composition and reactions during biomass pyrolysis, a traditional kinetics study is hard to performed. The TGA method using models, such as single reaction model, parallel reaction model and DAEM, could obtain some useful kinetics data. but the kinetics is not clear. maybe lumping kinetics could be more useful.
- Badges
- Science topic
- Similar topics
- Engineering
- Modeling