Analysis of gas-liquid system hydrodynamics in a double-impeller agitated vessel

Przedstawiono wyniki analizy eksperymentalnej hydrodynamiki układu ciecz-gaz w zbiorniku z dwoma mieszadłami. Analiza obejmowała określenie wpływu rodzaju cieczy (zdolności układu do koalescencji pęcherzyków gazu w cieczy) oraz typu górnego mieszadła na wartość udziału gazu zatrzymanego w cieczy oraz średniego czasu przebywania pęcherzyków gazu w cieczy w smukłym aparacie o średnicy D = 0,288 m. Dla obu zestawów mieszadeł znacznie wyższe wartości udziału gazu ę zatrzymanego w cieczy otrzymano w układach niewykazujących zdolności do koalescencji Korzystniejszy do zapewnienia dobrego rozproszenia gazu w objętości cieczy okazał się zestaw mieszadeł RT-A 315. W oparciu o otrzymane wyniki zaproponowano równanie, uwzględniające wpływ parametrów operacyjnych oraz właściwości fizycznych fazy ciągłej (zdolności układu do koalescencji pęcherzyków gazu w cieczy) warunki wytwarzania układu ciecz-gaz.Results of experimental analysis of gas-liquid system hydrodynamics in a double-impeller system are presented in the paper. The analysis concerned an effect of liquid phase type (ability of gas bubbles to coalesce) and a type of upper impeller on the gas hold-up and average gas bubbles' residence time in the tall double-impeller vessel of inner diameter D = 0.288 m. For both sets of impellers significantly higher gas hold-up values were obtained in non-coalescing systems. Better results of gas dispersion in a liquid volume characterize the RT-A 315 configuration. The equation considering an effect of operating parameters and a liquid phase type was proposed on basis of results obtained

Conditions of production of gas liquid- floating particles system in an agitated vessel

Celem pracy była analiza warunków wytwarzania mieszaniny ciecz-gaz-cząstki lekkie w mieszalniku o średnicy D = 0,288 m, zaopatrzonym w dwa mieszadła na wspólnym wale. Wyznaczono wartości częstości obrotów mieszadła nL, hCd oraz nJD, dzięki którym określono trzy charakterystyczne struktury przepływu mieszaniny trójfazowej. Określono wpływ udziału cząstek stałych X oraz strumienia objętościowego gazu Vg, na wartości n. Udział gazu zatrzymanego w układzie zwiększał się ze zwiększaniem Vg, a jego wartość zależała od udziału cząstek oraz rodzaju fazy ciągłej.The aim of this work was to analyze the conditions for producing a liquid-gas-floating particles mixture in the agitated vessel of inner diameter 0.288 m, equipped with two agitators on a common shaft. Rotational speed values of nL, hCd and nJD were determined, thanks to which three characteristic flow structures of three-phase mixture were obtained. The effect of solid particles concentration X and gas flow rate Vg on a value of n was determined. Gas hold-up in the system increased with the increase of Vg,, and its value depended on X and a type of continuous phase

Experimental analysis of chosen parameters effect on the mass transfer process in a three-phase non-coalescing system in a large laboratory agitated vessel

W pracy przedstawiono wyniki analizy eksperymentalnej procesu transportu masy między gazem a cieczą w obecności fazy stałej, w mieszalniku o objętości roboczej równej 0,2 m3. Na postawie badań określono wpływ parametrów operacyjnych, stężenia elektrolitu oraz typu mieszadła na wartość współczynnika wnikania masy. Mieszadła TR oraz CD 6 okazały się najkorzystniejsze do prowadzenia procesu transportu masy. Dla każdego z mieszadeł zaproponowano równania do obliczania współczynnika kLa.The experimental analysis of gas-liquid mass transfer process in the presence of solid phase conducted in an agitated vessel of working volume VL = 0.2 m3 is presented in this paper. An effect of operating parameters, electrolyte concentration and agitator type on the volumetric mass transfer coefficient was determined. For non-coalescing system better results w obtained using RT or CD 6 turbines compared to A 315 one. The correlations were proposed for each type of agitator to predict the volumetric mass transfer coefficient

Effect of agitated vessel scale on mass transfer process in a mechanically agitated gas – liquid system

Przedstawiono wyniki analizy wpływu skali aparatu (średnicy mieszalnika) na wartość współczynnika wnikania masy kLa (proces transportu tlenu między gazem a cieczą). W oparciu o szeroki zbiór danych: dwa mieszalniki różniące się 10-krotnie objętością roboczą, trzy mieszadła oraz sześć wartości strumienia gazu określono wpływ średnicy mieszalnika na kLa, przy stałej pozornej prędkości gazu wog albo parametru vvm (określającego strumień gazu liczony w m3/min. odniesiony do m3 cieczy). Opracowano zależność do obliczania współczynnika kLa w układzie ciecz-gaz.The analysis results of the effect of agitated vessel scale (its diameter) on the volumetric mass transfer coefficient (gas – liquid mass transfer process) are presented in this paper. A wide range of data: two agitated vessels differ ten times in working liquid volume, three agitators and six volumetric gas flow rates, enabled one to determine the diameter effect on kLa, assuming a constant value of superficial gas velocity, wog, or vvm parameter (describing gas flow rate in m3/min per m3 of liquid phase). The correlations for kLa calculation were elaborated

Influence of production factors on the quality of the high pressure die castings made of Al-Si ALLoYS - analysis with the Ishikawa diagram

Production of products required by the customer quality is one of the most important issues related to the management company. So far, quality control of the product was carried out at the end of the production process. It is increasingly giving way to projects aimed at bringing about a situation in which the number of defective products will be significantly reduced. In this situation, it becomes necessary to take action to identify the causes of major importance for the final result of the production process. For this purpose they are increasingly used quality management tool. The article presents the use of Ishikawa cause-effect diagram to identify the causes of casting defects in high pressure die casting Al-Si alloys

Develop an innovative compensation solution for functional disorders of the hand

Currently, in times of fierce market competition in selling goods and services for the disabled, quality and innovation are becoming "strategic weapons" for manufacturers. Depending on, inter alia, the dysfunctions of the injured person, the number of the offered products is increasing. For example: improving the functionality of the upper limbs is a highly significant issue, however due to the complexity of the functions and various degrees and types of restrictions, the treatment and rehabilitation process can be very complex and long-term, which at the same time does not guarantee full recovery. The authors describe the Polish invention created by Michał Jania, who will produce. This invention is intended to help people with upper limb illnesses and to assist with their rehabilitation

Mould components impact on structure and quality of elektron 21 alloy

Magnesium alloys due to their low density and high strength-to-weight ratio are promising material for the automotive and aerospace industries. Many elements made from magnesium alloys are produced by means of sand casting. It is essential to investigate impact of the applied mould components on the microstructure and the quality of the castings. For the research, six identical, 100x50x20mm plates has been sand cast from the Elektron 21 magnesium casting alloy. Each casting was fed and cooled in a different way: one, surrounded by mould sand, two with cast iron chills 20mm and 40mm thick applied, another two with the same chills as well as feeders applied and one with only the feeder applied. Solid solution grain size and eutectics volume fraction were evaluated quantitatively in Met-Ilo program, casting defects were observed on the scanning electron microscope Hitachi S3400N. The finest solid solution grain was observed in the castings with only the chills applied. Non metallic inclusions were observed in each plate. The smallest shrinkage porosity was observed in the castings with the feeders applied

The Influence of Strontium on the Microstructure of Cast Magnesium Alloys Containing Aluminum and Calcium

The structure of Mg-9Al-2Ca-xSr alloys is composed of a-Mg grains and the Al2Ca and Al4 Sr phases in the interdendritic areas. These phases are formed as a result of eutectic reactions. Globular particles of the Al8Mn5 phase are observed within the interior of the grains. The addition of strontium to Mg-9Al-2Ca-0.4Mn alloys causes the formation of the Al4Sr phase and increase of its volume fraction with increasing strontium levels. Moreover, increase of the strontium amount causes a decrease of aluminum content in the a-Mg solid solution

Influence of technological factors on the quality of aluminum alloys castings

To produce die-cast with high quality while maintaining the required performance affects many stages of the production process. These steps are dependent on each other and in the end of production process they decide on the competitiveness of manufactured elements. The main aspect affecting on the high quality and thus on the competitiveness of castings is finding that casting is free from defects. The great diversity of the disadvantages of the castings results from the technology of production casting, which is affected by a series of many technological operations, including: design and construction of the mold, technology of melting and casting molten metal into the mold and carrying out machining after casting