Investigating the Relationship between the Time Constant Ratio and Plug-Flow Behaviour in the Pneumatic Conveyance of Biomass Material

Abstract

This study introduces a novel methodology to evaluate the behaviour of biomass material by examining the ratio of aeration and deaeration time constants. To this end, a series of tests were conducted on four different materials, namely, cottonseed, wood chips, wood pellets, and wheat straw, in order to investigate their aeration and deaeration behaviours. The study derives the aeration and deaeration pressure drop equations, and discusses the corresponding time constant expression. Subsequently, the four materials were conveyed in 12 m long batch-fed and continuous pneumatic conveying pipelines to examine their behaviour in longer pipelines. The results indicate that the aeration and deaeration time constants increased with an increase in air superficial velocity. However, the ratio of the aeration and deaeration time constants was identified as a unique number, where a value close to 1 indicates a higher likelihood of plug flow. On the basis of the results, cottonseed, with the lowest ratio of time constant, was more likely to form a stable plug flow in both batch-fed and continuous pneumatic conveying. Given the unique properties of biomass and the limited research on the pneumatic conveyance of biomass, this methodology represents a novel approach for predicting modes of flow in materials with complex properties.

Recent Advancement in Pneumatic Conveying for Application in Feed Industry: A Review

“…Song et al carried out experiments alongside with simulation to study the conveying characteristics of shrimp feed pellets, where they constructed a correlation between system energy consumption and solid-gas ratio [11]. Rajabnia et al investigated the aeration and deaeration behaviours of four different biomass materials and further proposed a new algorithm to reduce trial test, providing a novel approach for predicting flow modes [7]. Alizadeh et al specifically carried out study on perennial ryegras to examine the effects of particle mass, size and moisture content on the performance of pneumatic conveying, with an emphasis on terminal velocity and drag coefficient [51].…”

“…Halstensen et al reported their design of an on-line monitoring device to acquire the velocity of feed pellet [6]. Rajabnia et al investigated into the relationship between the time constant ratio and plug-flow behavior on differet biomass materials including cottonseed and wood pellet [7]. Apart from the aforementioned experimental works, some other researchers focus on theoretical simulation.…”