Slurry sample withdrawal

Sample Withdrawal Using L-Shaped Probes. Thin L-shaped probes are commonly used to measure local solids concentration in slurry pipelines (29-34). However, serious sampling errors may arise as a result of particle inertia. To illustrate the effect of particle inertia on the performance of L-shaped probes, consider the flow field ahead (upstream) of a sampling probe located at the center of a pipe, as shown in Figure 3. The probe has zero thickness, and its axis coincides with that of the pipe. The fluid ahead of the sampler contains particles of different sizes and densities. Figure 3a shows the fluid flow when sampling with a velocity equal to the upstream local velocity (isokinetic sampling). Of course, the probe does not disturb the flow field ahead of the sampler, and, consequently, sample solids concentration and composition to equal those in the pipe. 

Various techniques are available to measure velocity and solids concentration profiles in slurry pipeline. Sample withdrawal using an Li-shaped probe can give a representative sample at isokinetic conditions. Other sample devices will produce significant errors that must be corrected. Conductivity probes can be used to measure local velocity and concentration profiles simultaneously. However, the carrier fluid should be conductive. NMR imaging methods do not disturb the flow with a probe however, they are limited to pipes of small diameter. 

The earliest use of a small ultrasonic probe to prepare slurries from coal fly ash directly in the autosampler cups was reported by van Loenen and Weers [13]. They found ultrasonic stirring not to ensure slurry homogeneity during the time required for the autosampler to withdraw each sample aliquot unless the analyte was completely leached. 

A slurry of 2 (0.2472 g, 35.6 mmol of lithium 5.9647 g, 46.5 mmol of naphthalene 1.9765g, 15.4mmol of cobalt chloride) was prepared, and the product washed once with glyme. It was then reacted in 25 ml of glyme with 4.5955 g (22.5 mmol) of phenyl iodide. Quenches were taken periodically by withdrawing 1 ml samples and treating the samples with two drops of IM HCl. The samples were then quantitatively analyzed by GC with use of -dodecane as an internal standard and application of response factor corrections. After 1 min, 59% of the phenyl iodide remained. After 20h (last 3h at reflux), 61% remained. No biphenyl was observed until the reaction mixture was refluxed, after which an 11% yield of that compound was found. 

Introduction of the support, as well as heating the slurries to 80°C induced the pH decrease. The additional amount of the ammonia solution was required to maintain the pH value of slurries about 5.5. Decrease in pH of the slimy with time, as well as pH of the slurry below 5.5 even at NH3 Au = 7, can stem from a precursor precipitation. Supported nanoparticles are clearly visible on TEM images of the samples prepared by DPnhiI confirming that DP process followed adsorption even at room temperature. On keeping the slurry at room temperature, Au partly remained in solution (Table 1). The increase in temperature of the slurry up to 80°C resulted in complete withdrawal of Au from the solution (samples AuM-2, AuT-3). 

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