Single liquid pressure drop

The vertical thermosiphon reboiler is a popular unit for heating distillation column bottoms. However, it is indeed surprising how so many units have been installed with so little data available. This indicates that a lot of guessing, usually on the very conservative side, has created many uneconomical units. No well-defined understanding of the performance of these units exists. Kern s recommended procedure has been found to be quite conservative on plant scale units yet it has undoubtedly been the basis for more designs than any other single approach. For some systems at and below atmospheric pressure operation, Kern s procedure gives inconsistent results. The problem is in the evaluation of the two-phase gas-liquid pressure drop under these conditions. [Pg.182]

Dimensionless correlations based on momentum-or energy-balances and using the Lockhart and Martinelli parameter, Xc, or some similar parameter. The practical relevance of such correlations is limited since their use requires the knowledge of the single-phase pressure drop of both gas and liquid furthermore, the influence of the geometry of the bed is not always well described by these single-phase pressure drops alone. [Pg.287]

A packed tower can successfully fractionate with a very small pressure drop, as compared to a tray. For a modern trayed tower, to produce one single theoretical tray worth of separation (that s like a single, 100 percent efficient tray), a pressure drop of about 6 in of liquid is needed. A bed of structured packing can do the same job, with one inch of liquid pressure drop, even when allowing for the vapor distributor. In low-pressure fractionators, especially vacuum towers used to make lubricating oils and waxes, this can be of critical importance. [Pg.79]

There are a number of pressure drop correlations for two-phase flow in packed beds originating from the Lockhart-Martinelli correlation for two-phase flow in pipes. These correlate the two-phase pressure drop to the single-phase pressure drops of the gas and the liquid obtained from the Ergun equation. See, for instance, the Larkins correlation [Larkins, White, and Jeffrey, AIChE J. 7 231 (1967)]... [Pg.59]

A method for predicting pressure drop and volume fraction for non-Newtonian fluids in annular flow has been proposed by Eisen-berg and Weinberger (AlChE J., 25, 240-245 [1979]). Das, Biswas, and Matra (Can. J. Chem. Eng., 70,431 37 [1993]) studied holdup in both horizontal and vertical gas/liquid flow with non-Newtonian liquids. Farooqi and Richardson (Trans Inst. Chem. Engrs., 60, 292-305, 323-333 [1982]) developed correlations for holdup and pressure drop for gas/non-Newtonian liquid horizontal flow. They used a modified Lockhart-Martinelli parameter for non-Newtonian liquid holdup. They found that two-phase pressure drop may actually be less than the single-phase liquid pressure drop with shear thinning liquids in laminar flow. [Pg.478]

Curvature of the vapor-liquid interface is reliant on the vapor-liquid pressure drop determined for each steady state mode as the entire hydraulic resistance of LHP or CPL. The value of curvature remains constant within single elementary cell of circumferential channel (Fig. 2, mode 2). [Pg.126]

These equations are correlated in terms of a dimensionless number called the Lockhart-Martinelli parameter (x /), which is the ratio of the single-phase pressure drop of liquid to that of the gas and is given by... [Pg.410]

For the liquid phase, the single-phase pressure drop is given by... [Pg.223]

The single-phase pressure drop per unit length for all liquid flow is determined from Eq. (7.80). Since the flow is turbulent, the friction factor is obtained with the aid of... [Pg.464]

Liquid viscosity is one of the most difficult properties to calculate with accuracy, yet it has an important role in the calculation of heat transfer coefficients and pressure drop. No single method is satisfactory for all temperature and viscosity ranges. We will distinguish three cases for pure hydrocarbons and petroleum fractions ... [Pg.126]

T. Single liquid drops in gas, gas side coefficient =2 + ANiS,Ni [E] Used for spray drying (arithmetic partial pressure difference). [88] p. 489... [Pg.615]

The simplest continuous-distillation process is the adiabatic single-stage equihbrium-flash process pictured in Fig. 13-25. Feed temperature and the pressure drop across the valve are adjusted to vaporize the feed to the desired extent, while the drum provides disengaging space to allow the vapor to separate from the liquid. The expansion across the valve is at constant enthalpy, and this facd can be used to calculate To (or T to give a desired To). [Pg.1263]

Because flashing steam-condensate lines represent two-phase flow, with the quantity of liquid phase depending on die system conditions, these can be designed following the previously described two-phase flow methods. An alternate by Ruskin [28] uses the concept but assumes a single homogeneous phase of fine liquid droplets dispersed in the flashed vapor. Pressure drop was calculated by the Darcy equation ... [Pg.141]

Qu W, Mudawar I (2002) Experimental and numerical study of pressure drop and heat transfer in a single-phase micro-channel heat sink. Int J Heat Mass Transfer 45 2549-2565 Qu W, Mudawar I (2004) Measurement and correlation of critical heat flux in two-phase micro-channel heat sinks. Int J Heat Mass Transfer 47 2045-2059 Ren L, Qu W, Li D (2001) Interfacial electro kinetic effects on liquid flow in micro-channels. Int J Heat Mass Transfer 44 3125-3134... [Pg.191]

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