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Dispensing High-Viscosity Adhesives and Sealants
Published in Gerald L. Schneberger, Adhesives in Manufacturing, 2018
Static mixers are devices, usually tubular, that have within them fixed, geometrically shaped elements which act as flow-splitting and shear-energy–creating devices for the fluids which travel through them (Fig. 6). Medium pricing and no moving parts are definitely positive reasons for using static mixers. They work well if the ratio and viscosity ranges of the two materials are not too wide. High-viscosity silicones, urethanes, and epoxies have all been successfully mixed through static mixing devices. Against the use of a static mixer is the fact that they are hard to efficiently flush or purge if they contain large volumes of material. Thus, considerable material may be wasted during purging or flushing whether mixed material, base material, or solvent is used. Removable-element mixers are available which obviously allow much more efficient cleaning.
Control of pH
Published in William S. Levine, Control System Applications, 2018
Consider an acid-base reaction performed by combining the process stream and reagent in a static mixer as shown in Figure 3.3 (but without the circulating pump, whose function is described later). A static mixer consists of a pipe fitted with internal baffles which alternately split and rotate the fluids, resulting in a homogeneous blend at the exit. The principal problem with the static mixer is that it presents pure deadtime to the controller. A step change in the reagent flow will produce no observable response in the pH at the exit until the new mixture emerges, at which time the full extent of the step appears at once. The dynamic gain of the mixer is 1.0 because the step at the inlet appears as a step at the exit, not diminished or spread out over time.
Primary Sedimentation
Published in Syed R. Qasim, Wastewater Treatment Plants, 2017
Thorough dispersion of coagulating chemicals is achieved in a rapid mix or flash mix basin. This is done by a static mixer or mechanical mixer. Static mixers create turbulence in the flow stream by baffles, obstruction, contraction, or enlargement of flow area or by creating a hydraulic jump in an open channel.
Hydrodynamics of wall-bounded turbulent flows through screens: a numerical study
Published in Chemical Engineering Communications, 2023
Static mixers are now commonly used in the industry because of their inherent characteristics that allow achieving high mixing efficiencies at reduced operating costs. Compared to conventional dynamic mixers, they also offer the advantage of a much smaller volume for the reactor with its subsequent positive impact on the safety of the operation (Thakur et al. 2003; Madhuranthakam et al. 2009; Peschel et al. 2012; Al Taweel et al. 2013; Ghanem et al. 2014). Moreover, the recent advances in numerical approaches helped in properly characterizing their internal flow behavior making them popular in the field of mixing (Meng et al. 2015, 2014). A survey of the open literature reveals a large number of studies that addressed the hydrodynamics and mixing performance of static mixers under laminar or turbulent regimes for a wide array of mixer geometries. For example, several studies addressed the performance of the widely used Kenics mixer (KSM) (Hobbs et al. 1998; Hobbs and Muzzio 1998; Rahmani et al. 2008, 2005; Mahammedi et al. 2017; Belhout et al. 2020) and SMX (Jegatheeswaran et al. 2018; Leclaire et al. 2020), while others presented the performance of novel mixers in comparison with KSM and/or SMX (Stec and Synowiec 2019, 2017a, 2017b; Haddadi et al. 2020a, 2020b; Meng et al. 2020, 2017, 2015, 2014).
Optimization of biodiesel production from waste cooking oil using static mixer technology in Vietnam
Published in Biofuels, 2018
Van Phuc Nguyen*, Huynh Hung My Nguyen, Dong Truc Nguyen, Huu Luong Nguyen, Thuan Minh Huynh
A static mixer, i.e. a mechanical mixer without any moving parts, is applied to mix highly viscous liquid–liquid phases in the chemical and food processing industries. Some advantages of static mixers compared to batch reactors are low capital, maintenance and operating costs, small space requirement, short reaction time and operation in continuous systems [14,15]. Some studies on static mixer reactors for biodiesel production have been presented. For example, Thompson and He [16] applied static mixers as a continuous-flow reactor for synthesis of biodiesel from canola oil. The authors reported that static mixer reactors can be used for biodiesel production and the most favorable conditions were 60°C, 1.5 wt% of sodium hydroxide (NaOH) as a catalyst for 30 min residence time. Alamsyah et al. [17] compared the effectiveness of static mixer and blade agitator reactors in biodiesel production from refined palm oil. The results showed that in the static mixer, the reaction rate was much faster and can reach the high fatty acid methyl ester (FAME) yield in a shorter time. The optimal conditions with static mixer reactor was found as follows: 65°C, methanol-to-oil molar ratio of 10.5 and 1.0 wt% of potassium hydroxide (KOH) as catalyst for 5 min residence time.
Towards sustainable continuous co-production of biodiesel and ether from wet microalgae- a review
Published in Biofuels, 2023
Static mixers are built comprised of stationary geometric components enclosed within a pipe or a column that effectively mix two immiscible liquids as they flow through the mixer. Santacesaria et al. [72] studied continuous transesterification of oil to biodiesel by filling a tubular reactor with five different types of static mixers, including threaded rod (TRR), single-size spherical packing (RP1), dual-size spherical packing (RP21 and RP22), and stainless steel ribbon wool (RWTR). They discovered that the biodiesel yield is affected by process settings and the type of static mixer used. In 0.99 min, RP21 yielded a maximum yield of 98.2% at 2% KOH (w/w oil).