Influence of ultrasonic irradiation on complete suspension state of borax in crystallizer equipped by SBT impeller : bachelor thesis

Cilj rada bio je ispitati utjecaj ultrazvuĉnog djelovanja na postizanje stanja potpune suspenzije kristala dinatrijevog tetraborat dekahidrata (boraks) u kristalizatoru sa SBT miješalom. OdreĊivanje minimalne brzine vrtnje miješala za postizanje stanje potpune suspenzije, , uz i bez primjene ultrazvuka provedeno je na laboratorijskom šaržnom kristalizatoru u kojem je volumen suspenzije iznosio 2.6 dm 3 , uz primjenu Zwieteringova kriterija "1s". Ispitivanja su provedena s tri razliĉita promjera radijalnog SBT miješala i pri ĉetiri razliĉite amplitude jakosti ultrazvuka = 20 − 40% . Eksperimentalni rezultati ukazuju da primjena ultrazvuka smanjuje vrijednost u ispitivanom reaktorskom sustavu. MeĊutim, sugerira se korištenje manjih amplituda jakosti ultrazvuka (= 20%) s obzirom na to da daljnjim povećanjem intenziteta ultrazvuka vrijednosti se dodatno ne smanjuju, dok se ukupni utrošak snage miješanja znaĉajno povećava. Za ispitivanu geometriju šaržnog kristalizatora te ispitivanu koncentraciju i odreĊenu veliĉinu kristala boraksa izvedena je korelacijska jednadžba koja povezuje vrijednosti sa amplitudom jakosti ultrazvuka i simpleksa (D/(T)The aim of this research was to examine the influence of the ultrasound on the state of complete suspension of the sodium tetraborate decahydrate (borax) crystals in the crystallizer with SBT impeller. Determination of minimal impeller speed required to achieve a state of complete suspension, N JS, with or without the ultrasound, was conducted in the laboratory scale batch crystallizer with a suspension volume of 2.6 dm 3 , using Zwietering's criterion "1s". The tests were carried out at three different diameters of the radial SBT impeller and at four different amplitudes of the ultrasound (= 20 − 40%) . Experimental results showed that ultrasonic irradiation reduces the value of N JS in the examined reactor system. Nevertheless, it is suggested to use lower amplitudes of the ultrasound = (20%) since with the increasement of the ultrasound intensity N JS is not additionally reduced, while total power consumption of mixing is significantly increased. For the examined geometry of the batch crystallizer, the concentration and size of the borax crystals, an equation which correlate the N JS value with the ultrasound amplitude and simplex (D/T) was derived