Feed Slurry Temperature

Feed Slurry Temperature Temperature can be both an aid and a limitation. As temperature of the feed slurry is increased, the viscosity of the hquid phase is decreased, causing an increase in filtration rate and a decrease in cake moisture content. The limit to the benefits of increased temperature occurs when the vapor pressure of the hquid phase starts to materially reduce the allowable vacuum. If the hquid phase is permitted to flash within the filter internals, various undesired resiilts may ensue disruption in cake formation adjacent to the medium, scale deposit on the filter internals, a sharp rise in pressure drop within the filter drainage passages due to increased vapor flow, or decreased vacuum pump capacity. In most cases, the vacuum system should be designed so that the liquid phase does not boil. 

In some special cases, steam filtration can be used to gain the advantages ot temperature without having to heat the feed slurry. 

The average composition of the feed slurry used in the treatments is shown in Table 2. The composition of TS, VS and COD did not vary significantly between runs. There was significant variation (P=0.001) in BODw, VFA and NH3-N, which was related to the time of year. These characteristics generally increased with respect to TS in summer when higher ambient temperatures promoted microbial activity. The average chemical composition was veiy similar to that of slurries used elsewhere in laboratory scale treatment experiments (3, 4, 7, 13). 

Spray-dried powders are formulated to give the best overall cleaning performance and flow characteristics at the lowest possible formulation costs. Typical spray-dried detergent formulations are shown in Table 36.6. Slurry preparation is considered to be the single most important factor in spray drying. Control of the raw material order of addition, slurry solids level, slurry temperature, viscosity, and aeration enable manufacturers to deliver the desired final product characteristics. The spray tower itself is simply a contained heat source that removes moisture at a uniform rate dependent upon the quality and the quantity of feed to the dryer. If feed variables are not controlled, variability in the... 

In some special cases, steam filtration can be used to gain the advantages of temperature without having to heat the feed slurry. Where applicable, dry steam is passed through the deliquored cake to raise the temperature of the residual moisture, reduce its viscosity, and lower its content. The final dmng or cooling period which follows steam filtration uses the residuaf heat left in the cake to evaporate some additional moisture. 

Heat input to the roaster is necessary during start-up and is achieved by three removable preheat burners. Once a bed temperature of about 700°C is achieved, oxidation of the sulphide feed slurry provides adequate heat to maintain temperature. 

A flash evaporator system having no heating surfaces has been developed for separating salts with normal solubility from salts having inverse solubility. Steam is injected directly into the feed slurry to dissolve the normal-solubility salt by increasing the temperature and dilution of the slurry. The other salt remains in suspension and is separated. The hot dilute solution is then flashed to a lower temperature where the normal-solubility salt crystallizes and is separated. The brine stream is then mixed with more mixed salts and recycled through the system. This system can be operated as a multiple effect by flashing down to... 

This section describes a new and simple experimental method for obtaining the reduced cut size and the rest of the reduced grade efficiency curve of an operating separator. The method relies on feeding a known and fiiUy characterized slurry to the separator under test, and on measuring only two solids concentrations (in the feed and in the overflow), one static pressure differential (or some other flow rate-dependent variable) and the slurry temperature. These measurements are best done and logged by a personal computer, and, for hydrocyclones, have to be repeated at two different pressure settings. 

The bottom part of the filter outer enclosure into which the filter feed slurry flows A measure of the change in viscosity with temperature ASTM D-2270. 

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