Treating caustic

Amines remove the bulk of the H2S primary amines also remove the COj. Amine treating is not effective for removal of mercaptan. In addition, it cannot remove enough H2S to meet the copper strip corrosion test. For this reason, caustic treating is the final polishing step downstream of the amine units. Table 1-3 illustrates the chemistry of some of the important caustic reactions. 

Olefin from paraffin NaX (caustic treated) Light olefin [161]... 

Water wash caustic-treated jet fuel to remove traces of caustic. 

Material in the evaporator feed tank goes to an evaporator/ crystallizer. The SCWO product contains about 4 weight percent salt. The evaporator system can handle about 125 percent of the 11,122 lbs/hr of caustic-treated feed from each SCWO reactor. It operates continuously, producing 24,870 lbs/hr of condensate and 574 lbs/hr of solids. 

Sulfur removal, as practiced in various refineries, can take several forms for instance, concentration in refinery products such as coke (Table 7-1), hydrode-sulfurization, or chemical removal (acid treating and caustic treating, i.e., sweetening or finishing processes). Nevertheless, the desulfurization of petroleum is almost universally accomplished by the catalytic reaction of hydrogen with the sulfur-containing constituents of petroleum to produce hydrogen sulfide that can be readily separated from the liquid products (Chapter 9). 

A schematic drawing is shown in Figure 2. The small amounts of ester formed are reverted with a caustic-treating plus water wash. Distillation in a light ends column removes unreacted olefins, paraffin byproduct, plus other light components present in the crude alcohol. A second distillation is used to remove trace heavy components. Hydrogenation eliminates trace unsaturation, aldehydes, etc. Filtration assures clear, solids free product. 

The amount of caustic treat to be added for neutralization of soybean oil is calculated as ... 

Re-Refining— In handling dark oils, it frequently happens that no matter how efficient the original caustic refining of a crude cottonseed oil may be, the bleached color is less than desired. Under these circumstances, it becomes necessary to re-refine the oil for additional color removal. Usually, 1% or 2% of a 16°Be caustic treat is sufficient to provide a bleach color of 2.0 to 2.5 Lovibond red color (123). 

The clay mineral or mixture was reacted with NaOH for about 20 minutes and then placed in a drying oven at 105 for 5 to 30 minutes to reduce the moisture content. The sample was then removed from the oven, filtered, water washed, and air dried. In a few experiments the caustic-treated clay mixture was filtered to remove excess moisture and then placed in the drying oven the sample was again filtered and water washed. These two sets of experiments evaluated the effect of the treatment steps prior to microwave irradiation. 

Figure 1. Experimental sequence for mesophilic digestion of caustic-treated feed...

Thermophilic (55 C) digestion of the caustic-treated feed at 0.4 lb VS/ft -day loading and a 6-day detention time showed the same methane yield of about 4 SCF/lb VS added as observed during mesophilic digestion of the pretreated feed at a 0.1 lb VS/ft -day loading and a 12-day detention time (Run 5T/24, Table II). However, the thermophilic gas production rate was 4-5 times the mesophilic rate. Also, the caustic requirement for feed pretreatment was lower for the thermophilic run owing to the recycling of the spent caustic solution. 

The oily layer formed after acidification and settling may amount to 1 to 5%, rarely 8%, of the volume of phenolic spent caustic treated. It may contain from 0.5 to 5% of paraffinic HC in dispersion. In fact the layer comprises (Table 39) ... 

Treating improves the odor, color, and stability of straight-run liquids and conversion-unit products. Sulfuric acid treating removes olefins, sulfur, nitrogen, oxygen compounds, and other contaminants. Clay/lime treating of acid-treated oil removes any residual traces of asphaltenes. Caustic treating... 

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