Sand Displacement Method

Another possible way of measuring the envelope density of coarse particles is by the sand displacement method. It uses fine sand, into which a known amount of the coarse particles of the sample is mixed. The density of the sample is determined from the difference of the bulk density of the sand alone and that of the mixture. This method is sometimes used for density determinations of coarse bone particles, for example, and it gives lower density than that of the solid bone as measured by pyknometry. A similar method has recently been used by Buczek and Geldart19. 

The use of the effective (aerodynamic) particle density is largely restricted to fluidization and pneumatic conveying applications at the moment. It is, however, potentially useful in other areas like particle size measurement by sedimentation or elutriation, or flow through packed beds where it has not yet been fully accepted. 

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The density of the sand by displacement methods was measured to be 2.600 kg/m. The sand is to be fluidized with air at 100°C. Atmospheric pressure is 772 mm Hg. Estimate the minimum fluidization velocity. Calculate the composite particle diameter by means of... 

Figure 16.8 GEC construction with displacement method under water, Kirfehir, Turkey. The image shows filling with sand (excavator) and the vibrator waiting to remove the steel pipe, compacting the column.

Fig. 5 shows control methods often used on vertical separators. The first is strictly level control. A regular displacer float is used to control the gas-oil interface and regulate a control valve dumping oil from the oil section. An interface float is used to control the oil-water interface and regulate a water oudet control valve. Because no internal baffling or weirs are used, this system is the easiest to fabricate and handles sand and solids production best. 

Table I also includes a summary of four methods for recovering the hydrocarbon values without mining the oil sand. Three involve combustion as (at least) part of the displacement technology. The fourth uses a steam drive to emulsify the oil in water.

P-j-Ca3(PO4)2- -10CO. To avoid the loss of one-third the phosphorus by its reversion to the normal phosphate, sand is admixed with the charge in the retort, when 2Ca(P03)2-i-2Si02-(-10C=4P-(-2CaSi03-(-10CO. The manufacture of phosphorus by these methods is discussed by J. L. Smith, W. Jettel, G. W. Stose, E. Orloff, J. B. Readman, etc. Electrical heatjng has now virtually displaced the retort processes. 

All above three methods have their own disadvantage for measuring the work ability of explosives. There are new experiment methods in study. For example, when the explosion is under water, the new experiments include the broken dome method of spray center initiate velocity or dome method of water cylinder, the measurement of water impact energy, and bubble energy. For explosive cylinders with certain diameter, it s also a method to measure the velocity of radial displacement of cylinder shell after the explosion from one end. The earthquake method measures the highest pressure of shock waves in the water (sand, or earth), which are certain distance away from the explosion center. The experiment data of earthquake method match the calculated one very well. Because the experiment earthquake energy is linearly proportional to the mass of packed explosives, it s suitable for measuring the work ability of explosives. 

The major problem experienced in the field to date in chemical flooding processes has been the inability to make contact with residual oil. Laboratory screening procedures have developed micellar-polymer systems that have displacement efiiciencies approaching 100% when sand packs or uniform consolidated sandstones are used as the porous medium. When the same micellar-polymer system is applied in an actual reservoir rock sample, however, the efficiencies are usually lowered significantly. This is due to the heterogeneities in the reservoir samples. When the process is applied to the reservoir, the efiiciencies become even worse. Research is being conducted on methods to reduce the effect of the rock heterogeneities and to improve the displacement efficiencies. 

Control measures require information about the biofilm population. Molecular methods permit early detection of growth on surfaces (Amann et al. 1995). Using the principle of modification of the microbial community. Sand et al. (1991) proposed oxygenation as a means of alleviating the propagation of SRBs. Alternatively, biocides can be effective in controlling biofilms and subsequent deterioration of materials (Bell and Chadwick 1994 Bell et al. 1992 Wakefield 1997). Other attempts at community modification include precipitation of microbially produced H2S by ferrous chloride (Morton et al. 1991) and displacement of Thiobacillus by heterotrophic bacteria (Padival et al. 1995). AH of these efforts have met with limited success. 

Centrifugation is the preferred technique for the extraction of pore-water from chalks, sandstones, sands and other materials of relatively high permeability. The method is generally not suitable for very low permeability materials, such as clays. The porosity of samples is often not an issue, so long as the material is relatively permeable, and pore-water may be extracted from sandstones and chalks with moisture contents as low as 1%. The likelihood and efficiency of extraction, particularly from relatively lower porosity and decreasingly permeable material, is increased substantially when using the displacement technique. 

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