Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: gas dispersion

Sortuj według:

Ogranicz wyniki do:

A discussion on the limitations of image analysis for determining bubble size in industrial flotation when using algorithms successfully tested from idealized images

Vinnett Luis

Physicochemical Problems of Mineral Processing

2023

Vol. 59, iss. 5

art. no. 174474

This paper evaluates the capacity of an automated algorithm to detect bubbles and estimate bubble size (Sauter mean diameter, D32) from images recorded in industrial flotation machines. The algorithm is previously calibrated from laboratory images. The D32 results are compared with semi-automated estimations, which are used as "ground truth". Although the automated algorithm is reliable to estimate bubble size at laboratory scale, a significant bias is observed from industrial images for D32 >3.0-4.0 mm. This uncertainty is caused by the presence of small and large bubbles in the same population, with large bubbles forming complex clusters and being observed incomplete, limited by the region of interest. Flotation columns are more prone to this condition, which hinders the estimation of Sauter diameters. The results show the need for bubble size databases that include industrial images. As several image processing tools are currently available, software calibration from ideal bubble images (synthetic or from laboratory rigs) will mostly lead to biased D32 estimations in industrial flotation machines.

The Influence of Impeller Geometry on the Gas Bubbles Dispersion in Uro-200 Reactor – RTD Curves

Saternus M., Merder T., Pieprzyca J.

Archives of Metallurgy and Materials

2015

Vol. 60, iss. 4

2887--2894

URO-200 reactor belongs to batch reactors used in refining process of aluminium and its alloys in polish foundries. The appropriate level of hydrogen removal from liquid aluminium can be obtained when the mixing of inert gas bubbles with liquid metal is uniform. Thus, the important role is played by the following parameters: flow rate of refining gas, geometry of the impeller, rotary impeller speed. The article presents the results of research conducted on physical model of URO-200 reactor. The NaCl tracer was introduced to water (modelling liquid aluminium) and then the conductivity was measured. Basing on the obtained results the Residence Time Distribution (RTD) curves were determined. The measurements were carried out for two different rotary impellers, flow rate equaled 5, 10, 15 and 20 dm3/min and rotary impeller speed from 250 to 400 rpm every 50 rpm.

Reaktor URO-200 jest reaktorem cyklicznym stosowanym powszechnie w Polsce do procesu rafinacji aluminium i jego stopów. Odpowiedni stopień usuwania wodoru z ciekłego aluminium uzyskuje się wówczas, gdy wymieszanie ciekłego metalu z pęcherzykami gazu obojętnego jest równomierne. Ważną rolę odgrywają takie parametry procesowe jak: natężenie przepływu gazu, kształt wirnika oraz prędkość obrotowa rotora. W artykule przedstawiono wyniki badań w oparciu o model fizyczny reaktora URO-200. Mierzono konduktywność roztworu wodnego (modelującego ciekłe aluminium), do którego wprowadzano znacznik NaCl. W oparciu o otrzymane wyniki wykreślono krzywe mieszania RTD (Residence Time Distribution). Pomiary prowadzono dla dwóch różnych wirników przy natężeniu przepływu gazu 5, 10, 15 i 20 dm3/min oraz przy obrotach wirnika 250, 300, 350 i 400 obr/min.