Biomass Torrefaction Process Review and Moving Bed Torrefaction System Model Development [report]

Jaya Shakar Tumuluru, Shahab Sokhansanj, Christopher T Wright
2010 unpublished
Torrefaction is gaining attention as an important preprocessing step to improve the quality of biomass in terms of physical properties and chemical composition. Torrefaction is a slow heating of biomass in an inert or reduced environment to a maximum temperature of approximately 300°C. Torrefaction can also be defined as a group of products resulting from the partially controlled and isothermal pyrolysis of biomass occurring in a temperature range of 200-280ºC. Thus, the process can be called a
more » ... mild pyrolysis as it occurs at the lower temperature range of the pyrolysis process. At the end of the torrefaction process, a solid uniform product with lower moisture content and higher energy content than raw biomass is produced. Most of the smoke-producing compounds and other volatiles are removed during torrefaction, which produces a final product that will have a lower mass but a higher heating value. There is a lack of literature on the design aspects of torrefaction reactor and a design sheet for estimating the dimensions of the torrefier based on capacity. This study includes (a) a detailed review of biomass torrefaction in terms of understanding the process, product properties, off-gas compositions, and methods used, and (b) a methodology for designing a moving bed torrefier, taking into account the basic fundamental heat and mass transfer calculations. Specific objectives include establishing a set of basic calculations for configuring a torrefaction system, like the diameter and height of the moving packed bed for different capacities, and the heat loads and gas flow rates of the system. Develop Excel© worksheet so a user can define design specifications. In this report, 25-1000 kg/hr are used in equations for the design of the torrefier. Examples of calculations and specifications for the torrefier are included. iv This page intentionally left blank.
doi:10.2172/991885 fatcat:adcqtrjrnfejte34v5o4zzfc7u