| Popis: |
Kontinuirna kristalizacija se v proizvodnji farmacevtskih učinkovin vedno bolj uveljavlja, za ustrezno aplikacijo takšnega kontinuirnega procesa pa je potrebno preučiti tudi depozicijo delcev v cevnih sistemih. V tem delu je bil preučen vpliv različnih parametrov kot so velikost delcev, premer cevi in volumski delež trdne faze na kritično depozicijsko hitrost. Cilj raziskovanja je bil ugotoviti optimalne procesne parametre za uporabo v realnem kontinuirnem kristalizatorju. Eksperimentalno delo je bilo zastavljeno tako, da sem v šaržnem reaktorju izvedel kristalizacijo. Nastalo suspenzijo sem črpal po krožni zanki, kjer sem z vizualno kontrolo (fotoaparat) spremljal depozicijo delcev v horizontalni cevi. Za spremljanje velikostnih porazdelitev delcev je bila uporabljena metoda FBRM, ki je bila preverjena z uporabo optičnega mikroskopa. Preučene so bile odvisnosti kritične depozicijske hitrosti od velikosti delcev in premera cevi, kjer je ugotovljena zveza ustrezala predpostavkam na podlagi teoretičnih modelov. Odvisnost kritične depozicijske hitrosti od volumskega deleže trdne faze v tem delu ni bila ugotovljena. Različne empirične korelacije, ki opisujejo depozicijo delcev v kontinuirnih sistemih so bile preučene, poleg tega so bile izvedene tudi primerjave z eksperimentalnimi podatki pridobljenimi v tem delu. Korelacije, ki so naš sistem najbolje opisale, so bile optimizirane in zasnovan je bil nov model kritične depozicijske hitrosti v odvisnosti od mnogih procesnih parametrov. V zaključku so bile predlagane tudi tematike za nadaljnje raziskovanje na tem področju. Continuous crystallization is increasingly used in the production of pharmaceutical ingredients, but for an appropriate application of such continuous process deposition of particles in tubular systems must be examined as well. In this work the influence of various parameters such as particle size, pipe diameter and volume fraction of solid phase on the critical deposition velocity was studied. The aim was to find the optimal process parameters for the use in a real continuous crystallizer. Experimental work started with the crystallization performed in a batch reactor. Afterwards, the obtained suspension was pumped through a closed loop, where visual control (camera) was used for monitoring the deposition of particles in a horizontal pipe. For monitoring of particle size distributions FBRM technique was used, which was also validated using optical microscopy. The dependency of critical deposition velocity on the particle size and pipe diameter was studied and a correlation was derived suiting the theoretical background information. On the other hand, the correlation between critical deposition velocity and volume fraction of solid-phase was not found in this work. Furthermore, various empirical correlations were examined and their ability to model deposition in this system was investigated. The correlations which best described our system were additionally optimized and also a new model was proposed correlating the critical deposition velocity and various process parameters examined. In conclusion some topic for further research were proposed. |
