Fluid penetration rate

The effect of fluid penetration rate and the extent of penetration on granule size distribution from drum granulation experiments is illustrated in Fig. 20 (since no example for fluidized bed granulation is available). From Fig. 20, it is clear that for fluids with a similar extent of penetration, increasing the penetration rate increases the average granule size for various levels of liquid loading. 

As an example of Washburn approaches, the effect of fluid penetration rate and tne extent of penetration on granule-size distribution for drum granulation was shown by Gluba et al. [Powder Hand, ir Proc., 2, 323 (1990)]. Increasing penetration rate, as reflected by Eq. (21-98b), increased granule size, and decreased asymmetry of the granule-size distribution as shown in Fig. 21-101. 

If a situation arises whereby formation fluid or gas enters the bore bole the driller will notice an increase in the total volume of mud. Other indications such as a sudden increase in penetration rate and a decrease in pump pressure may also indicate an influx. Much depends on a quick response of the driller to close in the well before substantial volumes of formation fluid have entered the borehole. Onoe the BOP is closed, the new mud gradient required to restore balance to the system can be calculated. The heavier mud is then circulated in through the kill line and the lighter mud and influx is circulated out through the choke line. Once overbalance is restored, the BOP can be opened again and drilling operations continue. 

Increase pore size to increase rate of fluid penetration. Decrease pore size to increase extent of fluid penetration. Modify particle size distrihiition of feed ingredients. Alter milling, classification or formation conditions of feed if appropriate to modify particle size distrihiition. 

For a fixed value of pressure drop, the fluid flow rate is approximately proportional to the size of the overflow diameter. A reduction in the overflow diameter leads to an increase in the pressure drop over the cyclone in order to keep the fluid flow rate unchanged. When the fluid flow rate is fixed, then, in general, the reduction in the size of the overflow diameter results in an increase in efficiency. This is simply because a small outlet opening makes it difficult for the particles to penetrate the cyclone. 

It is a well-known fact in drilling practice that clear (fresh) water is the best drilling fluid as far as penetration rate is concerned. Therefore, whenever possible, drilling operators try to use minimum density and minimum solids drilling fluids to achieve the fastest drilling rate. Originally, the low solids-clear (fresh) water muds were used in hard formations, but now they are also applied to other areas. 

Clear freshwater is the best drilling fluid in terms of penetration rate. Therefore it is desirable to achieve a maximal drilling rate using a minimal amount of solid additives. Originally low-solids mud formulations were used in hard formations, but they now also tend to find use in other formations. Several types of flocculants are used to promote the settling of drilled solids by flocculation. 

Rapid fluid flow cannot be achieved with active metal brazes because of the need to form solid wettable reaction product layers for their liquid fronts to advance. Equations (10.1) to (10.2) relating liquid flow rates to the opposed effects of surface energy imbalances and of viscous drag are not relevant. Actual penetration rates are so slow, usually of the order of 1 pm.s, that the usual practice is to place the active metal braze alloy within the joints rather than expecting it to fill them, and, as explained already, gap width is not the dominant consideration when designing ceramic-metal joints. 

Passive diffusion of sulfonamides into human red cells is determined by plasma dmg binding and lipid solubility. Apparent partition coefficients between chloroform and water at pH 7.4 show an almost linear relation with penetration constant for sulfonamides and a number of other acids. Penetration rates of sulfonamides into the aqueous humour and cerebrospinal fluid also correlate with partition coefficients (Fig. 5.11) moreover, as can be seen from the data in Fig. 5.12, the antibacterial effects of fatty acids and esters towards B. subtilis correlate with octanol/water partition coefficients. 

The durability of SPC structures in aggressive environments depends on the diffusion rate of chemically active reagents into a material. Fluid penetration is realized through imperfections in molecular packing of the binder and it is accelerated at an increase of temperature and pressure. In this connection, definition of a diffusion coefficient (as a key parameter of a liquid carryover) becomes the important problem. 

Water penetration rates are usually calculated according to the gas laws from measurement of pressure decay upstream of the filler over the whole period of testing with the gas (air) volume above the fluid held constant. They are therefore subject to temperature variations. Although the principle of the water penetration test is sound, and the avoidance of the use of potentially adulterating solvents is attractive, the low rates of water penetration calculable from only very small pressure drops within test systems have raised doubts about the robustness of the method for routine application in its contribution to the decision-making process. 

Relations may be developed to represent the steady pore fluid pressures that develop around a penetrometer under steady penetration, at penetration rate, U. These rtKxlels necessarily employ simple linearized constitutive relations, but incorporate the important influence of a porous medium migrating past the penetrometer tip, albeit in a simplified form. Dislocation models (Elsworth, 1991 1993) may be applied to represent a penetrometer of infinitesimal-radius, but suffer the disadvantage that penetration-induced pressures become singular at the assumed penetrometer tip. The approximate solution for a finite radius penetrometer avoids this shortcoming, as explored in the following. 

Tetiachloroethylene applied to a patch of abdominal skin of ICR mice for 15 minutes/week resulted in an in vivo absorption rate of 0.24 mg/cm%our (Tsuruta 1975). An in vitro study using excised rat (SD-JCL) skin demonstrated that the rate of penetration by tetiachloroethylene was much slower than that of several other halogenated hydrocarbons (i.e., 2,070 times slower than that of the fastest compound, dichloromethane), and the measured rate for tetiachloroethylene penetration was 0.005 mg/cm%our. The penetration rate observed in the in vitro method was 44 times slower than that observed in the in vivo method. The difference may result from the solubility of the substance in 0.9% sodium chloride and its solubility in body fluids (Tsumta 1977). 

Comparison of penetration rates obtained from in vitro and in vivo assays have been made (Bartek and LaBudde 1975), often with a good correlation. Differences in the methods for some compounds could be explained by the different solubilities in the receptacle fluid and blood others could not be explained. Skin of the weanling pig and miniature swine appear to be good in vitro models for most compounds (Bartek et al. 1972). On the basis of a limited number of studies, the skin of monkeys also appears to be a good model (Wester and Maibach 1983). Further details may be found in Bronaugh and Maibach... 

Large Diameter Well with Recyclable Foam. The objective on this well was to drill a 26-inch surface hole to 1500 feet and a 17.5-inch intermediate hole to 6000 feet with foam. Previous drilling in this particular region had proven to be excessively expensive due to low penetration rates. There existed a known potential for lost circulation, large fresh water influxes, and unconsolidated formations in the upper section of the well. Foam was chosen as the drilling fluid of choice, due to its ability to function effectively in the presence of high water influxes and... 

Once the returned fluid had been cleaned, blender tests were run to determine the makeup concentrations of foamer and polymer. Due to natural adsorption of surfactant on the cuttings surface, maintenance concentrations of foamer and polymer were added to maintain the desii ed performance. The percentage of makeup depended on many different factors, such as penetration rate, temperature, rock type, etc. On this particular well makeup percentages were in the 0.1-0.2% range out of the original 0.8% loading. The foam system was considered to be very controllable, economical and successful by all those involved. Penetration rates of 5-10 times those achieved with conventional mud systems were realized. 

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