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Download fileProcess Intensification Enabling Continuous Manufacturing Processes Using Modular Continuous Vacuum Screw Filter
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posted on 2021-10-13, 18:56 authored by Claas Steenweg, Astrid Ina Seifert, Nils Böttger, Kerstin WohlgemuthA novel apparatus
concept for integrated, small-scale continuous
filtration, washing, and drying is presented. The continuous vacuum
screw filter (CVSF) allows obtaining dried and free-flowing product
particles from the continuously fed suspension. While the first study
presented the CVSF concept in detail and focused on the characterization
with respect to the product quality control and solid-phase residence
time distribution (RTDS) during sole filtration, the modular
extension with washing modules and a vacuum-induced (pre-) drying
setup is now presented here. For this purpose, a wash module was designed
and implemented. The influence of single-stage and two-stage washing
on the particle size distribution (PSD) and RTDS was investigated
for the L-alanine/water model system. Single-stage washing
increased the particle size of d90,3 by 120 μm (+19%)
due to a higher agglomeration degree, while using two-stage washing
could completely preserve the particulate properties of the inlet
suspension. To identify favorable operating conditions for efficient
(pre-) drying, the effect of varying throughputs and mean residence
times on the residual moisture of the product particles was quantified.
High filling degrees (>30%) and increased mean residence times
(>11
min), in combination with two-stage washing and efficient vacuum-induced
airflow, ensured completely isolated, free-flowing, and almost dry
particles with residual moistures of 1% and an entire maintenance
of the PSD. Measurements of the RTDS showed a slight broadening
due to the wash liquid used, still ensuring a narrow RTDS and thus almost plug-flow-like behavior. In summary, the CVSF offers
unique features, such as its modularity and rapid start-up behavior,
providing a promising concept for integrated continuous particle isolation
from suspensions.
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water model systemthus almost plugslight broadening duemean residence timeshigher agglomeration degreeensured completely isolatedallows obtaining driedproduct quality controlalmost dry particleswash liquid usedscale continuous filtrationcontinuously fed suspensionnovel apparatus conceptpre -) dryingparticle size distributionfirst study presented</ sub >)3 </ subflowing product particlesstage washing increasedproduct particlesparticle size</ subwash modulesole filtrationinlet suspensionpromising conceptwashing modulesvarying throughputsstill ensuringstage washingresidual moisturesresidual moisturerapid startparticulate propertiesmodular extensionentire maintenance