Design for Dilute Phase Transport

Design of a dilute phase transport system involves selection of a combination of pipe size and gas velocity to ensure dilute flow, calculation of the resulting pipeline pressure drop and selection of appropriate equipment for moving the gas and separating the solids from the gas at the end of the line. 

Bearing in mind the uncertainty in the correlations for predicting choking and saltation velocities, safety margins of 50 % and greater are recommended when selecting the operating gas velocity. 

Equation (8.15) applies in general to the flow of any gas-particle mixture in a pipe. In order to make the equation specific to dilute phase transport, we must find expressions for terms 3 (gas-to-wall friction) and 4 (solids-to-wall friction). 

In dilute transport the gas-to-wall friction is often assumed independent of the presence of the solids and so the friction factor for the gas may be used (e.g. Fanning friction factor - see worked example on dilute pneumatic transport). 

Several approaches to estimating solids-to-wall friction are presented in the literature. Here we will use the modified Konno and Saito (1969) correlation for estimating the pressure loss due to solid-to-pipe friction in vertical transport and the Hinkle (1953) correlation for estimating this pressure loss in horizontal transport. Thus for vertical transport (Konno and Saito, 1969)  

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