Biomass feeding in a dilute pneumatic conveying system

Abstract

Biomass is a renewable energy source of increasing industrial interest. However, due to particle physical characteristics, operational problems are verified during its transport, which is usually associated with the control of the feeding process. In this context, a feeding system was designed, specifically for the control of biomass flow rate, in a positive pressure pneumatic conveying line, which made it possible to evaluate the feeding efficiency of a rotary valve, using materials with different physical properties and varying air velocity, valve rotational speed and the height of material in the feeding silo. The biomasses evaluated were milled corn, corn cob, corn straw, rice husk, and wheat bran, which were characterized by their density, size, angle of repose, shape, and moisture content. The study presented relevant results, such as biomasses of low bulk density obtained greater feeding efficiencies for the conditions of lower material height in the silo due to easier breaking of the mechanical/cohesive arches formed, while the material of higher density showed greater efficiencies in conditions of greater heights. Besides this, an empirical correlation was proposed to predict the pressure drop in the feeding tee, whose coefficient of determination was 99.11%, with a maximum deviation of 10% in relation to the experimental data. The differential of this correlation is the insertion of a shape factor in its equation, given the irregularity of the biomass particles.