Pressure drop liquids

A low-pressure-drop liquid cyclone is sometimes used to clarify liquor discharged from the evaporator. The driving force is the pressure drop across the circulating pump. Thickened slurry is returned through a wide-open cyclone underflow connection to the circulating piping before the pump suction. 

Prandtl-Nikuradse treatment and considered the liquid film to involve a laminar and a turbulent layer. Anderson and Mantzouranis work is an extension of the equations presented by Dukler and Bergelin (D5), and makes use of the von Karman universal velocity profile. In general, if any two of pressure drop, liquid flow rate, or film thickness are known, the third quantity can be calculated. 

Recently Iliuta and Larachi [44] developed a generalized slit model for the prediction of frictional two-phase pressure-drop, liquid hold-up, and wetting efficiency in TBR operated under partially-and fully wetted conditions. This proposed model mimicked the actual bed void by two geometrically identical inclined slits, a wet slit and a dry slit (see Figure 5.2-14). 

R.A. Holub, M.P. Dudukovic and P.A. Ramachandran, A phenomenological model for pressure drop, liquid hold-up and flow regimes transition in gas-liquid trickle flow, Chem. Engng. Science, 47 (1992) 2343-2348. 

Downcomer Backup Flooding Aerated liquid backs up in the downcomer because of tray pressure drop, liquid height on the tray, and frictional losses in the downcomer apron (Fig. 14-32). All these increase with increasing liquid rate. Tray pressure drop also increases as the gas rate rises. When the backup of aerated liquid exceeds the tray spacing, liquid accumulates on the tray above, causing downcomer backup flooding. 

I. Iliuta, F. Larachi, Mechanistic model for structured-packing containing columns Irrigated pressure drop, liquid holdup and packing fractional wetted area, Ind. Eng. Chem. Res. 40 (2000) 5140-5146. 

In the past 50 yrs. much attention has been focused on pressure drop, liquid holdup, flow regime transition, and liquid distribution in TBR. Though significant progress in modeling the hydrodynamics of TBR theoretically has been made, the prediction of some... 

Holub, R.A. Dudokovic, M.P. Ramachandran, P.A. Pressure drop, liquid holdup, and flow regime transition in trickle flow. Am. Inst. Chem. Eng. J. 1993, 39, 302. 

The overall distillation plate efficiency, E , may be correlated in terms of the following variables liquid density, vapor density, liquid viscosity, vapor viscosity, liquid diffusivity, surface tension, pressure, temperature, pressure drop, liquid flow rate, vapor flow rate, bubble size, contact time. 

The areas concerned with hydrodynamics in trickle beds include flow regimes, liquid distribution on the solid (catalyst) packing, pressure drop, liquid holdup, and, more generally, the effect of the physical properties of the liquid and gas phases on all hydrodynamic properties. 

There have been many studies of the hydrodynamics of trickle beds that describe the different flow regimes and give empirical correlations for the pressure drop, liquid holdup, and the partial wetting of the catalyst. Only a few of these studies are discussed here, since extensive reviews are available [18-21]. A recent review [20] includes over 170 references. 

Venturi scrubbers ate costly to operate because of the high pressure drop associated with their use, particularly for large gas flows. Figure 3.2-17 indicates some of the trade-offs of pressure drop, liquid/gas ratio, and entraimnent size removal. Various correlations ate given in the literature, particularly by Calvert and a good review is found in Perry and Green, but vendors should be consulted for actual design data. 

Flow regimes, pressure drop, liquid holdup, liquid distribution, mixing, residence time distridution, heat and mass transfer,, xial and radial segregation of solids ... 

At this point most of the column and tray parameters have been tentatively determined. Next, a performance check is carried out at various operating conditions to determine the operable ranges and whether any of the design parameters need to be adjusted. Performance checks include such items as pressure drop, liquid handhng capacity, entrainment, and weeping. 

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