Extraction, commercial processes fractional

Separation of Aromatic and Aliphatic Hydrocarbons. Aromatics extraction for aromatics production, treatment of jet fuel kerosene, and enrichment of gasoline fractions is one of the most important appHcations of solvent extraction. The various commercial processes are summarized in Table 4. 

Separation of niobium from tantalum and impurity metals is the most important step in its extraction from the ore. It may be achieved by several methods that include solvent extraction, ion exchange, fractional crystallization, fractional sublimation, and other techniques. Solvent extraction is apphed mostly in several large-scale commercial processes. Although the classical fractional crystalhzation method forms effective separation, it is a tedious... 

Most commercial extraction solvents currently are utilized to produce an improved raffinate. Recently, American Cyanamid announced availability of various dipropio-nitriles which are capable of recovering pure aromatics with exceptional selectivity. Extractive distillation to recover benzene or toluene from petroleum fractions has become an accepted commercial process. The possibilities of utilizing selective adsorption for concentration of aromatics has been receiving serious consideration. 

Two important extractive distillation processes were placed in commercial operation during World War II the recovery of butadiene from a C4 fraction using furfural as the entrainer (7, 22) and the segregation of toluene from petroleum fractions by means of phenol (14-16). 

Tphis work explores the important variables which must be considered - to design an extractive distillation process. The discussion identifies the economic effects of these variables and their possible interactions. Some of the design variables may have synergistic effects in terms of separation cost while others may not. As a result, the optimum design for an economic extractive distillation process must be a compromise set of values for the different process variables. These compromises are discussed and are illustrated for a particular case—i.e., separation of propane-propylene mixtures. For this commercially important separation fractional distillation is most often used, regardless of the low relative volatility (about 1.13-1.19 at 200 psia). 

The study report recommended that a vertically integrated commercial venture be established to market ingredients based on essential oils, extracts and chemical fractions derived from the species identified to UK, mainland Europe, US and possibly Japan. These ingredients would be processed using where appropriate, the latest technology such as CO2 based extraction. 

Direct solvent extraction is the most widely used oil-recovery method for soybeans, but it also requires considerable capital and large scale to compete. In actual practice, solvent extraction is used to crush over 98% of the soybean processed in the United States. Process flow diagrams are shown in Figures 3 and 4. Most soybean solvent-extraction plants process more than 2,500 MT/day (Figure 5), and some are capable of processing as much as 5,000 MT/day (especially newly constructed plants in Brazil). Direct-solvent-extraction plants smaller than 1,000 MT/day have difficulty competing in the United States. At various times, soybeans have been extracted commercially with petroleum distillate fractions that resemble gasoline, acetone, carbon disulfide, ethanol, trichloroethylene, and even water. 

Tall oil fulfils all of these requirements. Tall oil is a natural product of pine trees that is isolated by means of the Kraft pulping process. It is composed of the ether extractable, non-lignin, non-cellulosic portion of the pine tree, and it must be fractionated via steam-vacuum distillation for commercial use. Fractionation of one metric ton of crude tall oil produces about 350 kg of rosin acids, 300 kg of fatty acids and 330 kg of distillated tall oil, head and pitch. The economic value of tall oil is primarily derived from its fatty acid fraction. 

If an apphcation proves to be technically feasible, the choice of solvent-to-feed ratio is determined by identifying the most cost-effective ratio between the minimum and maximum limits. For most applications, the maximum solvent-to-feed ratio will be much larger than the ratio chosen for the commercial process however, the maximum ratio can be a real constraint when dealing with applications exhibiting high mutual solubility, especially for systems that involve high solute concentrations. Additional discussion is given by Seader and Henley [Chap. 8 in Separations Process Principles (Wiley, 1998)]. Solvent ratios are further constrained for a fractional extraction scheme, as discussed in Fractional Extraction Calculations. ... 

Dual-Solvent Fractional Extraction As discussed in Commercial Process Schemes, under Introduction and Overview, fractional extraction often may be viewed as combining product purification with product recovery by adding a washing section to the stripping section of a standard extraction process. In the stripping section, the mass transfer we focus on is the transfer of the product solute from the wash solvent into the extraction solvent. If we assume dilute conditions and use shortcut calculations for illustration, the extraction factor is given by... 

Novel mixtures of optical isomers of natural and kosher styrallyl alcohol (a-phenylethyl alcohol), and their corresponding acetate esters of styrallyl alcohol (a-phenylethyl acetate) were prepared by multiple fermentation processes and an azeotropic esterification reaction. In the first step, natural acetophenone was produced by bioconversion of cinnamic acid by Pseudomonas sp. (P), Comanonas sp, and Arthrobacter sp. 6). In the first microbial oxidation process, the side chain of cinnamic acid was oxidized to the ketone to form acetophenone that was transiently accumulated in the fermentation broth (P). The current commercial fermentation process yielded >5g/L of acetophenone in the fermentation broth following 2 days of incubation using Arthrobacter sp. The resulting acetophenone was recovered and purified from the fermentation broth by solvent extraction followed by fractional distillation. Acetophenone itself can be used in creating flavor formulations and in enhancement of aroma and taste or both. 

---