Technical aspects of the rheological properties of microbial cultures

Charles, Marvin

doi:10.1007/3-540-08557-2_1

Cited by 61 publications

(31 citation statements)

References 57 publications

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“…Furthermore, the fungal morphology is an important parameter in influencing the physical properties of the fermentation broth, e.g., oxygen uptake rate [13,[15][16][17].…”

Section: Resultsmentioning

confidence: 99%

Effect of Oxygen Transfer and Pellet Size for Producing of Glucosamine Using Aspergillus sydowii BCRC 31742 Cultivated in a Fermenter

Hs¹,

Lin²

2017

J Food Process Technol

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“…Furthermore, the fungal morphology is an important parameter in influencing the physical properties of the fermentation broth, e.g., oxygen uptake rate [13,[15][16][17].…”

Section: Resultsmentioning

confidence: 99%

Effect of Oxygen Transfer and Pellet Size for Producing of Glucosamine Using Aspergillus sydowii BCRC 31742 Cultivated in a Fermenter

Hs¹,

Lin²

2017

J Food Process Technol

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“…Although these values are outside the laminar¯ow range [6,29], the power number values do not appear to approach a region of constant value. This slight decline may be caused by the tank and impeller geometry as well as the baf¯e placement 5 offset since declines in power number with Reynolds' number have been noted for baf¯eless tanks [20,27].…”

Section: Qualitative Comparison Of Power Number As a Function Of Reynmentioning

confidence: 95%

Influence of impeller type on power input in fermentation vessels

Junker

Stanik

Barna

et al. 1998

Bioprocess Engineering

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Prior investigations comparing radial¯ow Rushton impellers with axial¯ow hydrofoil impellers (Max¯o T and A315) were extended at the pilot scale. Six types of impellers (disk-style Rushton, Prochem Max¯o T hydrofoils of three diameters pumping downwards and A315 hydrofoils pumping upwards and downwards) were compared for qualitative differences in power number behavior with Reynolds' number, single versus double impeller power draw, gassed power reduction with aeration number and gas hold-up. Power measurements were obtained using watt transducers which, although limited in accuracy and prone to interferences, were able to provide useful qualitative monitoring results. Measurements were conducted using three model liquid systems: water, glycerol and Melojel (soluble starch). Apparent viscosities for actual Streptomyces cultivations were estimated using measured gassed power values and the experimental relationships obtained for gassed/ungassed power to aeration number and power number to Reynolds' number for the glycerol model system. Results con®rmed the lower power number and lower shear environment for hydrofoil impellers, yet suggested useful trends for various process parameters and process¯uids.List of symbols c constant relating average tank shear rate to impeller speed g gravitational acceleration, 9X807 m/s 2 g c gravitational acceleration conversion factor, 1 kg Á m/s 2 Á N k¯uid consistency index n power law index n I number of impellers p T pressure at tank top, mPa v S super®cial velocity of sparged air based on tank diameter, m/s D I impeller diameter (tip to tip), m D T fermenter vessel diameter, m H tank hold up based on dispersion volume H L height of liquid in tank excluding bottom dish, m H T total height of tank, m IS impeller shear, s À1 ITS impeller tip speed, pD I N, m/s K constant relating N A to P g aP 0 N impeller speed, s À1 N A aeration or¯ow number, QaND 3 I N Fr Froude number, N 2 D I ag N P Newton or power number, P 0 aqN 3 D 5 I N Re Reynolds' number for impeller, ND 2 I qal N We Weber number for impeller P exp gas expansion power, m 3 as P 0 ungassed power draw, kW P g gassed power draw, kW P L power loss, kW Q volumetric gas¯owrate, m 3 as S impeller spacing, m V L ungassed liquid volume of tank, m 3 V T total volume of tank, m 3 W width of tank baf¯es, cm q liquid density, g/cm 3 q g gas density, g/cm 3 l viscosity, MPa Á s l a apparent viscosity, MPa Á s c T average shear rate in stirred tank, s À1 c V average shear rate in viscometer, s À1 r surface tension, dynes/cm 1 Introduction Substantial research has been conducted at Merck Research Laboratories comparing radial¯ow Rushton impellers with axial¯ow Prochem Max¯o T and Lightnin A315 impellers [4, 10, 15±17]. The main characteristics of these impellers are summarized in Table 1. It has been well-demonstrated that Rushton turbines lose up to 70% of their power draw when aerated due to the formation of air ®lled ventilated cavities behind the blades [17]. In high viscosity broths, these air cavities become stabilized [18] alth...

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“…The rheological behavior of fermentation broths have been reviewed (Metz, 1976;Charles, 1978;Riley et al, 2000) and will generally Oosterhuis and Kossen, 1984. ) be influenced by the morphology of the microorganism and in some cases by the formation of extracellular products such as xanthan gum (Amanullah et al, 1998b) and gellan gum (Dreveton et al, 1996).…”

Section: -2 Scale-up/scale-down Of Fermentation Processesmentioning

confidence: 99%