Intensification of transfer processes in biotechnology and chemical engineering using static mixers. (Review)

Tudose, R. Z.

doi:10.1002/abio.370150102

Cited by 12 publications

(13 citation statements)

References 22 publications

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“…One may distinguish (Gavrilescu and Tudose, 1995) (i) helical elements, typified by the Kenics mixer (ii) blades or corrugated sheets, examples of which are the SMX and SMV mixers (iii) short tubes or channels with holes, and (iv) wire meshes. Apart from the number of elements and their overall size, which determines the Reynolds number for a given application, several other lengths and angles are needed to specify the geometry of each mixer.…”

Section: Introductionmentioning

confidence: 99%

Simulation of gas–liquid flow in a helical static mixer

Zidouni

Krepper

Rzehak

et al. 2015

Chemical Engineering Science

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Section: Introductionmentioning

confidence: 99%

Simulation of gas–liquid flow in a helical static mixer

Zidouni

Krepper

Rzehak

et al. 2015

Chemical Engineering Science

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“…Using static mixers, small bubble sizes can be obtained with a relative homogeneous bubble distribution over the riser column cross section and with a narrower bubble size distribution. The intersecting channels which the corrugate sheets form by adjoining one another split the fluid into individual streams at open intersecting channel of the mixing element [12]. Any inhomogeneity is spread two dimensionally in the first mixing element and three dimensionally in the following one, which is turned at 90°angle.…”

Section: Resultsmentioning

confidence: 99%

“…This objective can be realized in dynamic mixers by means of moving elements which needs 2-external-loop (downcomer); 3-static mixers; 4-pump; 5-heat exchanger; 6-rotameter an external energy input or by means of static mixers [12]. Recently, new constructive types of static mixers have been developed, which supply spectacular effects concerning transfer rate increase in all fields of chemical and biochemical engineering.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics in external-loop airlift bioreactors with static mixers

Roman

Tudose

1997

Bioprocess Engineering

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Liquid circulation superficial velocity and gas holdup behaviours were investigated in an external-loop airlift bioreactor of 0.170 m3 liquid volume in gas-induced and forcedcirculation-loop operation modes, in the presence of static mixers made of corrugated stainless steel pieces, resulting in packets with the height-to-diameter ratio equal to unity and using non-Newtonian starch solutions as liquid phase. The static mixers were disposed in the riser in three blocks, each with three mixing packets, successively turned 90°to the adjacent mixing element. It was found that in the presence of static mixers and forced-loop operation mode, liquid circulation superficial velocity in the riser section was significantly diminished, while gas holdup increased in a great measure. It was considered that static mixers split the fluid into individual streams and break up the bubbles, resulting in small bubble sizes with a relative homogeneous bubble distribution over riser cross section. They act as supplementary resistances in liquid flow, reducing riser cross sectional area, equivalent with A D /A R area ratio diminishing. List of symbolsa coefficient in Eq. (12) A D downcomer cross sectional area (m2) AL gas-induced-loop circulation mode ALF forced-loop circulation mode A R riser cross sectional area (m2) b exponent in Eq. (12) c coefficient in Eq. (13) f coefficient in Eq. (8) H D distance in downcomer between pH probes (m) H d dispersion height in riser (m) H R liquid height in riser (m) K consistency index (Pa sn) M index refering to static mixers presence m exponent in Eq. (8) n flow behaviour index (-) t D time between the maxima at upper and downcomer pH probe, respectively (s) v LD liquid linear velocity in downcomer (m/s) v LR liquid linear velocity in riser (m/s) v SGR gas superficial velocity in riser (m/s) v SLR liquid superficial velocity in riser (m/s) av average shear rate (s\1) GR gas holdup in riser (-) ap apparent liquid viscosity (Pas) shear stress (Pa)

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“…Then mixing occurs in the SM, in which higher Re and flow velocities are predominant because of a reduced free area by the elements of the SM. 55 Switching from co-axial mixing to mixing in the T-piece results in local mixing of feed suspension and anti-solvent. Therefore, most of the precipitation occurs in the T-piece.…”

Section: Methods Before the Precipitation Experiments Withmentioning

confidence: 99%

Performance Characterization of Static Mixers in Precipitating Environments

Kreimer

Zettl

Aigner

et al. 2019

Org. Process Res. Dev.

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This work investigates the application of static mixers (SMs) in precipitating environments as present in certain pharmaceutical processes, in which the undesired side effect of precipitation of the residual dissolved fraction leads to equipment fouling and process stability challenges. The tests were conducted using saturated suspensions mixed with an anti-solvent to challenge the system with a step change of solubility in the presence of seeds and SMs. Various equipment configurations such as co-axial vs perpendicular mixing, different equipment dimensions, plastic vs metal SM, or ultrasound (US) irradiation were investigated, and fouling probability and stability were analyzed for different precipitation rates by monitoring the pressure level. The process stability was highly influenced by the setup configuration. The most stable and satisfactory process was achieved by co-axial mixing of the fluids before the SM plus using US irradiation. With this setup a run time of 5 h was achieved, continuous processing beyond 5 h could be realized by parallel arrangement of SMs, in which the process is switched from one SM to another after a pressure threshold is triggered. Furthermore, the particle size in various feed and outlet suspensions was analyzed, and correlations between the amount of suspended particles and the particle growth were determined. The highest initial solids in the feed suspension (30 wt%) resulted in the smallest growth of the particles in the outlet suspension (d 50 increased by 17.7%) after anti-solvent addition.

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Intensification of transfer processes in biotechnology and chemical engineering using static mixers. (Review)

Cited by 12 publications

References 22 publications

Simulation of gas–liquid flow in a helical static mixer

Simulation of gas–liquid flow in a helical static mixer

Hydrodynamics in external-loop airlift bioreactors with static mixers

Performance Characterization of Static Mixers in Precipitating Environments

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