Precoat filtration with body-feed and variable pressure. Part II: Experimental tests and optimization of filtration cycles

Abstract

The classical theory of the precoat filtration with body-feed suggests the Carman equation obtained by integration of the Darcy ODE with constant pressure. Hereinafter the equation obtained in Part I by mean a mathematical modelling of the precoat filtration with body-feed in more realistic conditions of variable pressure was re-called and an experimental validation was done. A pilot filter equipped with a small centrifugal pump was used. The experimental results of the curve of filtrate volume vs. filtration time were compared both with the new equation curve and the Carman equation curve. In the specific conditions of laboratory testing, the estimation error in the filtration time with the new equation is -3.7%, while the estimation error with the classical Carman equation is -21.6%. But with higher permeability conditions of the filtration layer the error with Carman equation can greatly increase, as it was contemplate in Part I. The precoat filtration with body-feed must be followed by the filter cleaning. The research of an optimization of the filtration-cleaning cycle using the classic theory 7368 Dario Friso and Lucia Bortolini of filtration, and therefore the Carman equation, leads to the well known condition to have equal both filtration time and cleaning time. With the proposal of the new equation, in this work a new modelling of the cycle optimization was elaborated. It provided a ratio between filtration time and cleaning time always greater than 1 with values also up to 16 for the higher permeability of the filtering layer (reduced c     ). Therefore, the use of the previous optimization with a rate equal 1 is unacceptable with higher permeability, leading to a substantial halving of the filter productivity.