Gas‐solid flow distribution through identical vertical passages: Modeling and stability analysis

Abstract

in Wiley InterScience (www.interscience.wiley.com).As previous evidence shows, the distribution of gas-solid flow traveling through identical parallel paths can be significantly nonuniform, often with harmful operating consequences in practice. A fundamental analytical and numerical study is performed on the distribution of gas-solid pneumatic flow passing through a ''Y branch''. While many steady-state gas-solid distribution solutions, including a uniform distribution, satisfy the governing equations, linear stability analysis indicates that the uniform distribution is stable the most likely solution of the system. Both 2-D (two-dimensional) and 3-D multiphase computational fluid dynamic simulations and stability analyses confirm the analytical conclusions.

Stability and phase space analysis of fluidized-dense phase pneumatic transport system

“…Hrenya [21], Masnadi et al [22] and Zhang et al [23,24]. These work were carried out either with granular products or coarser particles in standpipes or with fluidized beds and very little…”

“…Considering mass, momentum and energy balance across a small control volume [22], the following governing equations have been obtained:…”

Design of parallel cyclones based on stability analysis

“…Therefore, we postulate that parallel cyclones are systems which tend to adapt the minimum pressure, i.e. to minimize the rate of total energy dissipation, and the criterion for mal‐distribution can be written: 1. When the total energy dissipation at uniform distribution is less than that at non‐uniform distribution, i.e., ε T,Uniform < ε T,Nonuniform , uniform distribution is stable. 2.…”

“…However, there is mounting evidence that gas‐solid suspensions pass through identical paths in parallel can be significantly non‐uniform, resulting in a dramatically drop in overall efficiency . The non‐uniform distribution of gas solids flow through parallel cyclones is a special case of mal‐distribution of multi‐phase flow through parallel paths, including gas‐solid two‐phase flow across parallel channels, gas‐liquid two‐phase flow in manifolds and liquid‐solid two‐phase flow across river network …”

“…Grace et al introduced a simple model to explain non‐uniform distribution of gas‐solid two‐phase flow through parallel paths. Masnadi et al used Grace's model to analyze the mal‐distribution of pneumatic gas solids flow through vertical parallel pipes and across identical cyclones in parallel. Due to the neglect of interaction between solids and gas, their studies could not provide a definite instability index of uniform distribution even though their results have clearly reflected that high mass loading of solids results in mal‐distribution.…”