Реферат: Liquid-liquid contacting for solute extraction or carrying out chemical reactions is widely employed in chemical industry. Various types of contactors used for liquids mixing are available: mechanically stirred vessels, rotor–stator and centrifugal apparatuses, static mixers, sieve-tray columns, etc. Conventional contactors are known to have both advantages and disadvantages. For example, static mixers cannot provide long residence time, their pressure drop increases with length. Centrifugal and stirred contactors are efficient, but they may result in emulsification, their rotating parts and sealing need to be maintained. Vertical sieve-tray columns cannot provide fast mass-transfer. It is known that structured confined vortex flows can provide some benefits for multiphase processes intensification purposes [1], e.g. for gas-liquid contacting [2]. As an example of a liquid-liquid contactor, the efficient contacting can be achieved by using of two-fluid Taylor-Couette flow where two immiscible liquids are stratified and contacted without emulsification in the annulus between spinning coaxial cylinders [3]. The present work is devoted to the development of an approach to liquids contacting in a strained confined swirled flow produced in a static vortex chamber (VC). Here VC is a substantially cylindrical shell having the top and the bottom end walls with at least one of them providing for liquid outlet. Fluid flow enters the body of VC via a swirler located at the periphery. The swirler consists of a ring with multiple tangential speeding up slots designed to convert the pressure energy to rotational motion. Fluid enters the VC body with a great angular momentum, which is slowed down by flow friction on the end wall surfaces to provide a spatial shear stress field within totally turbulent vortex flow with effective dissipation of incoming pressure energy inside the flow. The developed VC displays also sufficient values of centrifugal gravity to sustain the vortex motion and of residence time to complete solute extraction. LLVC is intended initially for realization of efficient liquids contacting for the extraction purposes of sour impurities, such as mercaptans, from liquid hydrocarbon stream to an aqueous caustic solution in the MEROX process [4,5]. Current industry practice is to use a sieve-tray column with its large mass and overall dimensions. Developed approach can serve to facilitate contacting and settling while minimizing the size of contactor. For example (see figure below), the water addition into the vortex flow of hexane leads to formation of homogenous liquid emulsion inside a VC, which is immediately partitioned after leaving the VC. The one of the most important advantages of the developed approach is the possibility to carry out effective mixing and contacting of liquids with possible gas addition and/or removal of the gaseous reaction products. Tested configurations of LLVC provided residence times of 3÷6 sec and energy dissipation rates of 7÷15 W/L at relatively low pressure drops of 30÷50 kPa. Developed simplified theoretical description of the flow in a VC is made with an axisymmetrical flow assumption. It is shown that friction stresses on the side and end walls of VC is responsible in establishing a desired flow pattern inside VC. The angular momentum balance conservation relation leads to the law for angular velocity distribution, which can be used then for calculation of other vortex flow parameters. Liquid-liquid vortex contactor has some attractive characteristics. Experimental evidences were obtained that the shear stresses inside the vortex flow result in very intensive liquids contacting with fast renovation of interfacial surface. Contactor provides sufficient yet not excessive mixing facilitating the subsequent phase separation and does not contain any moving or spinning parts. It was shown, that almost 100% of a theoretical extraction may be achieved in few seconds of residence time, as measured for a process of a dye extraction from water into pentanol stream. Various designs of LLVC may be suggested to satisfy different requirements such as intensity of mixing, residence time value, number of stages and throughput.

Библиографическая ссылка: Kuzmin A.O. , Pravdina M.K.
Static Vortex Contactor for Intensification of Interphase Processes Between Liquids
В сборнике 22nd International Congress of Chemical and Process Engineering, CHISA 2016 and 19th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2016. 2016. – C.411-412. Scopus РИНЦ

Идентификаторы БД:

Scopus:	2-s2.0-85050730222
РИНЦ:	35738572

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