Image Analysis to Obtain the Vibration Amplitude and the Residence Time Distribution of a Vibro-Fluidized Dryer

Abstract

The determination of the vibration amplitude and the residence time distribution on a vibro-fluidized dryer was carried out using the pulse method. Measuring the dryer displacement through image analysis, the vibration amplitude was determined and the vibro-fluidized bed was classified as a vibrated fluidized bed. The material used was ground eggshell, and tracers were ground eggshell dyed with black ink spray. The mass fraction of the tracer particles in each sample was calculated using image analysis. Two digital photographs were taken for each sample. On each photo, a grey level was specified. As the tracer has a greater percentage of grey level, compared to the non-marked sample, it was possible to count the amount of marked material using the image histogram. The influence of the residence time distribution was studied by varying the amplitude intensity, the solid feed rate and the air flow. It was inferred that the residence time increases as vibration amplitude decreases. Regarding the solid feed rate and the air flow, it was observed that the residence time increases with increase in the solid flow for low values of solid flow and air flow, and decreases with increase in the solid flow for high air flow. An addition of 0.06 m 3 s −1 in the air flow causes a 2.4-fold increase in the residence time.