Wet Torrefaction of Poultry Litter in a Pilot Unit: A Numerical Assessment of the Process Parameters

Abstract

A numerical model for the wet torrefaction of poultry litter in a pilot unit was developed in this study. The model accounted for the following process steps: preheating biomass in a feed hopper, feeding biomass into the reactor, fluidized-bed generation using superheated steam, and the supply of additional heat by the electric heating of the reactor walls. Following a “black box” approach, a major assumption of the model is that the behavior of the fluidized-bed reactor is similar to a completely stirred tank reactor (CSTR). Under this assumption, the properties of the particles and gases do not depend on their location inside the reactor. During wet torrefaction, poultry-litter biomass was heated to a predetermined temperature and decomposed, generating biochar along with a gas phase (torgas), whose amounts depended on the content of inert ash in the biomass particles. Variable optimization in the model was performed using MATLAB software. The model successfully estimated the optimal duration required for the completion of wet torrefaction under various conditions: temperature, batch weight, reactor dimensions, etc. The model was validated using experimental data obtained from a series of wet torrefaction experiments performed in a fluidized bed, and provided reliable estimations of the duration of the process depending on material properties, reactor size and feedstock characteristics.

Characteristics of Hydrochar and Liquid Products Obtained by Hydrothermal Carbonization and Wet Torrefaction of Poultry Litter in Mixture with Wood Sawdust

“…The yields of non-condensable gases obtained from the innovative WT process have already been reported in previous studies [24,25].…”

“…The side walls of the reactor were heated electrically to maintain the required temperature in the reactor. A detailed description of the operation of the pilot reactor for WT has been provided in [25].…”

“…The side walls of the reactor were heated electrically to maintain the required temperature in the reactor. A detailed description of the operation of the pilot reactor for WT has been provided in [25]. Before initiating the experiment, roughly 6 L of hydrochar from a previous batch was poured into the wet torrefaction reactor.…”

A Review of Poultry Waste-to-Wealth: Technological Progress, Modeling and Simulation Studies, and Economic- Environmental and Social Sustainability

“…Ayub et al (2022) developed the simulation model of hydrothermal gasification for syngas production from poultry litter waste using Aspen Plus software and suggested that this process is economic-environmentally friendly and energy-saving compared with direct landfilling disposal, and the results indicated that the model has a better yield of hydrogen and methane gas with superior lower heating value at 540 • C, 25 MPa, and 20% feedstock concentration [54]. Isemin et al (2021) developed a numerical model for the wet torrefaction of poultry litter waste and successfully estimated the optimal duration required for the completion of this process under different conditions of temperature, batch weight, reactor dimensions, etc., and showed that the wet torrefaction of poultry litter increased the carbon content by 17% and reduced the oxygen content 2.46-fold while raising the heat of combustion by 12.5% [55].…”