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Liquid-Liquid Separation
Published in Pau Loke Show, Chien Wei Ooi, Tau Chuan Ling, Bioprocess Engineering, 2019
Hui Yi Leong, Pau Loke Show, K. Vogisha Kunjunee, Qi Wye Neoh, Payal Sunil Thadani
A mixer-settler is a batch vessel that consists of two stages. The first chamber is an area where the two phases are mixed thoroughly, and the second chamber is where the mixture settles. The two phases separate by the force of gravity. In the first phase, the presence of a mechanical impeller brings the solvent and the feed stream into close contact with each other to permit the solutes to transfer from one phase to the other. The agitator’s motor mechanism also drives a turbine that pumps the now-homogenized mixture into the settling tank. The size of mixer-settlers varies with their purpose; for instance, laboratory mixers contain just the primary mixing stage, but mixers used in the copper-processing industry require a minimum of three mixers, and each of these acts as both a mixer and a pump. The benefits of using mixer-settlers in series is that the mixing time is prolonged, ensuring that all the material mixes thoroughly and there is no opportunity for the unmixed material to end up in the settling tank.
Design of a Modular Annular Centrifugal Contactor for Lab-Scale Counter-Current Multistage Solvent Extraction
Published in Solvent Extraction and Ion Exchange, 2023
Dominic Maertens, Koen Binnemans, Thomas Cardinaels
Annular centrifugal contactors (ACCs) are appealing equipment for counter-current multistage solvent extraction (SX), because they allow for high throughput at short residence times, have a small liquid hold-up, and a small footprint.[1] Packed and pulsed columns are also efficiently used for SX processes, but their required height (associated with a lack of physical stage separation) necessitates a tall process facility and building infrastructure. Especially for R&D purposes this is not always practical nor cost-efficient. Mixer-settlers have the advantage of a good stage efficiency, scalability, flexibility and throughput, although they can have relatively large liquid hold-up, requiring larger volumes of liquids compared to ACCs, and longer running times to reach equilibrium or steady-state conditions.
Gasoline pre-blending processes for efficient ethanol recovery: effects of process parameters and process modifications for improved performance
Published in Biofuels, 2021
Neil Stacey, María J. Fernández-Torres, David Glasser
A new approach to the process has been proposed, whereby ethanol is blended with gasoline without having first been fully purified, thereby exploiting liquid phase separation to conveniently eliminate the remainder of the water, as shown in Figure 1 [11–13]. The mixture naturally splits into two phases which can be separated by means of one or more mixer-settlers. In other words, the same phase split which makes water a problematic impurity in gasoline could be exploited to facilitate an energy-efficient separation; blending of water and gasoline results in the formation of two separate liquid phases without the addition of any separation energy. This process is called ‘gasoline pre-blending’ because it does not need the water to be fully eliminated prior to blending. If the design of the phase split is done correctly, the gasoline acquires the desired amount of ethanol, resulting in a suitable fuel mixture. According to Stacey et al [11,14], the overall process shown in Figure 1 results in more efficient separation of bioethanol from fermentation products, with significant energy and cost savings.
Population Balances for Extraction Column Simulations—An Overview
Published in Solvent Extraction and Ion Exchange, 2020
Hans-Jörg Bart, Hanin Jildeh, Menwer Attarakih
Reactive solvent extraction processes favor mixer-settlers as they are easy to design and scale-up when offering flexibility with respect to residence time, agitation and pH control. Columns in contrary have smaller footprint, have less solvents inventory, generate less solvent loses and offer a high throughput at a large number of theoretical stages.[4] However, fast reaction kinetics of modern ion exchangers allows the use of extraction columns at lower residence time. The first application was in the uranium field for safety reasons with pulsed columns due to their low liquid inventory to prevent radioactive hazards and an easy maintenance of an external pulsator in a non-radioactive environment.[5] They can be operated in either an emulsion or mixer-settler regime,[6] thus any residence time can be easily achieved.