Effect of filtration aid on downstream processing of polymer particles : Effektivisering av avvattningsprocessen av polymerpartiklar
Abstract: Polymer particles are expandable and produced by Nouryon. The production consists of polymerization, dewatering and drying. Dewatering of polymer particlesis an important part of the production process and have a large impact on how efficient the downstream process can be performed. An efficient dewatering enablesa fast and effective drying process and is therefore of great importance for a fastproduction process. Here, today, there are big variations. For mostpolymer particlegradesthe dewatering aid DEW1is added to the slurry. DEW1is a non-ionic surfactant that greatly increases dewatering abilities of slurry and thus increases speedof the downstream process. But, DEW1cannotbeused for allpolymer particlegrades due to regulations. Therefore, thosepolymer particlesdemand longer downstream times with higher production costs and higher energy consumption following. The aim ofthisdiploma work was to find an alternative dewatering aid which can be used for all polymer particle grades, has a good environmental profile and increases speed of the drying process. Several compounds weretestedin laboratory scaleduring this studyto investigatetheir effect ondry contentafter dewatering.One ofthem, DEW2, showedpromising features as an alternativedewatering aid which isalso bio-based. The highestdry content ofdewatered polymer particleslurrywith DEW2as dewatering aidwasXwt% dry polymer particles.This was2.2wt% higher dry content thanthe results achieved with DEW1.Also, the effect of heated polymer particleslurry and wash water on dry content wasinvestigatedduring this study. A strong relation between higher temperatures of especially wash water and increased dry content of dewatered polymer particleswasdetected. The highest dry content achieved was Xwt% dry polymer particlesfrom a test with slurry 20 °Cand wash water 80 °C. This was an increase in dry content with 26.9 % compared to the lowest dry content achieved. The lowest value was obtained when both slurry and wash water temperature was 20 °C, which during these tests gave a dry content of Xwt%. However, polymer particlesfrom testswith high temperatures showed signs of agglomerationof polymer particles on dispersion testwhich is not accepted for polymer particles of good quality.Two full scale production trialswere performed with wash water heated to 40 °C. No agglomerated polymer particleswereseen in the dried product, and the production speed increased with 18 respectively 11 %
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