Removal of Solids

Removal of Solids. Sohds incorporated in the mud during drilling generally are separated mechanically, reduced by dilution, or removed chemically by flocculation. It is desirable to maintain a low concentration of drill sohds (4—8 vol %) and in some cases total removal is required. In the latter case, the drilling fluid is clear, consisting of fresh water or brine, and high drilling rates can be achieved. Polymeric flocculants added in small (0.03—0.06 kg/m (0.01—0.02 Ib/bbl)) quantities maintain a clear hquid (139). 

A gravity diyer consists of a stationaiy vertical, usually cylindrical housing with openings for the introduction of sohds (at the top) and removal of solids (at the bottom). Gas flow is through the sohds bed and may be cocurrent or countercurrent and, in some instances, cross-flow. By definition, the rate of gas flow upward must be less than that required for fluidization. 

Process Concept Three potential surface-based regimes of separation exist when a second, immiscible liquid phase is added to another, solids-containing liquid in order to effect the removal of solids. These regimes (Fig. 22-37) are ... 

On the other hand, flotation usually imphes the removal of solid particulate material. Most important under the latter category is ore flotation, which is covered separately in Sec. 19. 

The eyeles in these power reeovery applieations are relatively simple. Figures 1-2 and 1-3 are typieal examples. The eyele eonfigura-tions involve the removal of solids or liquids ahead of the expander, and often the ineoming stream is heated so its temperature will not reaeh its frost point at the diseharge. This addition of heat also inereases the amount of available power. Some examples of this applieation are expansion of waste gas, waste produets of eombustion in oxidation proeesses, waste earbon dioxide, and expansion of high-pressure synthesis gas streams. 

Hygroscopicity Collection and removal of solid Direct measurement with... 

Chemical treatments -How organic polymers and inorganic coagulants work to counteract solids stabilization mechanisms and enhance removal of solids from water, and... 

Air flotation is one of the oldest methods for the removal of solids, oil grease and fibrous materials from wastewater. Suspended solids and oil grease removals as high as 99%+ can be attained with these processes. 

Removal of solids from the separation unit in which they are contained... 

The removal of solid particles from gas/vapor or liquid streams can be accomplished by several techniques, some handling the flow dry, others wetting the stream to settle/agglomerate the solids (or even dissolve) and remove the liquid phase from the system with the solid particles. Some techniques are more adaptable to certain industries than others. Figure 4-54 illustrates typical ranges of particle size removal of various types of common equipment or technique. All of these will not be covered in this chapter. Attention will be directed to the usual equipment associated with the chemical/petrochemical industries. 

The organic acid salts, such as EDTA and heptonate, are included for water softening properties, and to assist in the removal of solid particles. Gluconate and heptonate, in particular, are effective in the highly alkaline solutions used for etching aluminium and prevent the precipitation of aluminium hydroxide scale and sludge. 

Whatever cleaning method is used, the possibility of removal of solid metal is present. This will result in error in the determination of the corrosion rate. One or more cleaned and weighed specimens should be recleaned by the same method and reweighed. Loss due to this second treatment may be used as a correction to that indicated by the first weighing. 

Removal of solid debris using a micro-centrifuge is an alternative technique to filtration. Although it requires special apparatus, the... 

Many mechanical separations involve the movement of solid particles or liquid drops through a fluid. The fluid may be gas or liquid, and it may be flowing or static. As some assortment of examples mention may be made of the removal of dust and fumes from air or flue gas, the removal of solids from liquid wastes to permit discharge into public domain, and of the recovery of acid mists from an acid plant gaseous wastes. 

Conical ends are used to facilitate the smooth flow and removal of solids from process equipment such as, hoppers, spray-dryers and crystallisers. 

Granular bed filters are used in porcelain enameling wastewater treatment to remove residual solids from clarifier effluent (sedimentation effluent or flotation effluent). Filtration polishes the effluent and reduces suspended solids and insoluble precipitated metals to very low levels. Fine sand and coal are media commonly utilized in granular bed filtration. The filter is backwashed after becoming loaded with solids and the backwash is returned to the treatment plant influent for removal of solids in the clarification step.10-12... 

Centrifugal forces can also be exploited in hydrocyclones. As discussed in Chapter 8, designs are different for the removal of solids and dispersed oil. In contrast to solids... 

The soluble ions of iron and aluminium are usually reduced to a minimum by adjusting the electrolyte pH. For the removal of solid iron hydroxide and aluminium hydroxide Bayer decided to use a new pre-coat-free brine purification technology -back-pulse filtration using GORE-TEX membrane filter cloths. 

The fate of surfactants (Fig. 1.17) in wastewater treatment plants (WWTP) is determined by, among other factors, the composition of the wastewater, the operational type of the WWTP and the physicochemical properties of the surfactant molecule itself. In general, WWTPs provide a primary treatment, which is simply the removal of solid materials by mechanical means. 

Since the removal of solids from liquids in these ways is discussed elsewhere, this section is concerned only with the removal of suspended particles and liquid mists from gases. 

In addition to the removal of solids from gases, the problem of small quantities of compounds causing odour nuisance must frequently be handled. Activated carbon filters are used for this purpose and, in continuous operation, gaseous impurities from the air-stream are adsorbed on the activated carbon granules. The carbon will frequently adsorb contaminants until they reach a level of 20-30 per cent of the mass of the carbon. 

The conventional assay systems (If include dilutions of 1 2 to 1 5, as part of the extraction. Hence, the levels of detection are limited. The use of minimum amounts of extractant coupled with the physical removal of solids can improve the limits of detection and measurement. 

Another feature in favor of fluidized beds is the increased productivity of the catalyst-due to the smaller size of the particles, which in turn leads to better utilization of the surface area of the catalyst. In addition, the removal of solids from a fluidized bed is an easy task (Mukhlyonov et al, 1979). 

Evaporators employ heat to concentrate solutions or to recover dissolved solids by precipitating them from saturated solutions. They are reboilers with special provisions for separating liquid and vapor phases and for removal of solids when they are precipitated or crystallized out. Simple kettle-type reboilers [Fig. 8.4(d)] may be adequate in some applications, especially if enough freeboard is provided. Some of the many specialized types of evaporators that are in use are represented on Figure 8.16. The tubes may be horizontal or vertical, long or short the liquid may be outside or inside the tubes, circulation may be natural or forced with pumps or propellers. 

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