Liquid-solid contacting

Bubble Point Large areas of microfiltration membrane can be tested and verified by a bubble test. Pores of the membrane are filled with liquid, then a gas is forced against the face of the membrane. The Young-Laplace equation, AF = (4y cos Q)/d, relates the pressure required to force a bubble through a pore to its radius, and the interfacial surface tension between the penetrating gas and the liquid in the membrane pore, y is the surface tension (N/m), d is the pore diameter (m), and P is transmembrane pressure (Pa). 0 is the liquid-solid contact angle. For a fluid wetting the membrane perfectly, cos 0 = 1. 

A liquid-solid contact angle away from 90° induces the formation of a meniscus on the free surface of the liquid in a vertical tube (the solid phase). In the nonwetting case, the meniscus concaves upwards to the air. The upwards meniscus is the result of a downward surface tension at the liquid-tube interface, causing a capillary depression. In the wetting case, the meniscus has a concave-downward configuration. The downwards meniscus is the result of an upward surface tension at the liquid-tube interface, causing a capillary rise. 

Naouri et al. (1991) described another contained fluidized bed, the so-called high compacting multiphasic reactor (HCMR), which they used for malic and lactic acid fermentations for wine improvement. Bioparticles were contained within a tapered region and liquid was rapidly recycled through this region by pumping improved liquid/solid contact was cited as the advantage of this reactor. 

Fig. 15 shows the detailed structure of the droplet from a viewing angle of 60°. Experimental images show that a hole is formed in the center of the droplet for a short time period (3.4 4.8 ms) and the center of the liquid droplet is a dry circular area. The simulation also shows this hole structure although a minor variation exists over the experimental images. As the temperature of the surface is above the Leidenfrost temperature of the liquid, the vapor layer between the droplet and the surface diminishes the liquid-solid contact and thus yields a low surface-friction effect on the outwardly spreading liquid flow. When the droplet periphery starts to retreat due to the surface-tension effect, the liquid in the droplet center still flows outward driven by the inertia, which leads to the formation of the hole structure. 

Liquid-solid contact Liquid-liquid contact Statistical distribution due to ion concentration fluctuations Double layer (zeta potential) disruption Volta potential (for electron conducting materials) Electrolytic (galvanic) potential (for ionic systems)... 

Liquid-liquid contact will be basically similar to liquid-solid contact. In this case, both phases would be mobile, however, and some of the extreme charge separations possible in liquid-solid contacts would not be possible. 

Bevrox Biotreatment, or liquid-solids contact (ESC) digestion, is a patented, ex situ process for the treatment of biodegradable contaminants in soil, groundwater, or process water. 

An appropriate model for trickle-bed reactor performance for the case of a gas-phase, rate limiting reactant is developed. The use of the model for predictive calculations requires the knowledge of liquid-solid contacting efficiency, gas-liquid-solid mass transfer coefficients, rate constants and effectiveness factors of completely wetted catalysts, all of which are obtained by independent experiments. 

Some of the remaining studies did not necessarily observe incomplete catalyst wetting, but included this concept either directly as an adjustable parameter in the model to fit the observed conversion versus liquid mass velocity data,(7,9,13, 16-18), or indirectly via use of a correlation for liquid-solid contacting established for non-porous absorber column packings (11,19-20). 

The above discussion on previous experimental studies in trickle-bed reactors suggests that both liquid-solid contacting and mass transfer limitations play a role in affecting trickle-bed reactor performance. Except for a few isolated cases, the reactor models proposed in the literature for gaseous reactant limiting reactions have not incorporated particle-scale incomplete contacting as paft of their development. For cases where it was used, this parameter served as an adjustable constant to match the observed conversion versus liquid mass velocity data so that the true predictive ability of the model... 

The second portion of El-Hisnawi s study consisted of evaluating liquid-solid contacting efficiency and liquid holdup using impulse response tracer experiments. Experiments were performed using the same catalyst packing and solvents employed... 

EXTERNAL STATIC HOLDUP LIQUID-SOLID CONTACTING CORRELATION CONSTANTS 0.0204 ... 

A review of previous reaction studies used to support the development of trickle-bed reactor models is presented. This review suggests that these previous models have neglected the effect of incomplete liquid-solid contacting even though it was experimentally observed in a number of cases. For the few cases where it was included, it was used as an adjustable parameter to match the measured conversion versus liquid mass velocity data to the model. 

If a soil/sediment sample contains an obvious non-aqueous liquid phase, or contains more than two phases (i.e. non-aqueous liquid/aqueous liquid/solid), contact the Sample Management Office (SMO) in order to determine which phase(s) should be analyzed. 

Better mixing is obtained. A wider range of particle sizes can be used and better gas liquid-solid contact is possible. 

At present, very little is known on how the liquid-solid contact efficiency depends upon the gas and liquid flow rates. It is knovyn that higher gas and [iquid loadings can improve the contact efficiency. However, it is not clear what effects the wettability of the particles and the heal effects occurring during the chemical reactions have on the contacting efficiency. A s maller surface tension or higher viscosity of the liquid appears to increase the contacting efficiency. 

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