Experimental setup for the study of flocculation in approach system conditions
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Helsinki University of Technology |
Diplomityö
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Date
2005
Department
Major/Subject
Paperitekniikka
Mcode
Puu-21
Degree programme
Language
en
Pages
85 s. + liitt. 4
Series
Abstract
In papermaking, retention, drainage and formation have a critical influence on the efficiency of the process, run ability and the quality of final paper products. Retention drainage and formation depend strongly on the state of flocculation of furnish in the approach system. Hydro dynamical and chemical conditions in the approach system affect flocculation in numerous ways thus, the importance of understanding these phenomena is crucial for product quality and process performance. An experimental setup for the study of flocculation in approach system is developed. The objective of this work was to calibrate the system and bring it to a state where repeatable and reliable data can be obtained. The chosen approach is based on the image analysis in a furnish flow loop. In the setup papermaking furnish is run through a pipe line loop, to which chemicals and approach system shear forces are introduced. The images of fluidized furnish are acquired with a high speed CCD-camera and further analyzed with an image analysis software. Flock area distributions are obtained for each chemical and hydro dynamical condition. The instruments, devices, the control system software, the image capturing hardware, and the image analysis software were calibrated and optimized. Sensitivity ranges were identified. A number of tests investigating the sensitivity of the setup on variations in RDF-chemistry and hydrodynamics were carried out. The obtained flocculation results were explained from the standpoint of basic principles of flocculation and compared to existing conceptions published. The results well correlated with changes in chemical and hydro dynamical conditions in the approach system. The experimental setup was found to generate reliable, repeatable and satisfactory data. The experimental setup described can be used for systematic study of the effects of hydro-chemical interactions on flocculation in approach system conditions. Besides, opportunities for further development were discussed.Description
Supervisor
Paltakari, JouniThesis advisor
Jacobson, TommyKeywords
flocculation, flokkulaantuminen, image analysis, kuva analyysi, RDF chemistry, retentiokemia, hydrodynamics, hydrodynamiikka, approach system, lähestymisjärjestelmä