Extractive flashing

Gas treatment also includes the recovery of various hydrocarbons associated with natural gas. There are several processes to achieve this goal lean gas absorption, various types of refrigeration, turboexpansion, and others. However, since there were certain disadvantages in these processes, there was need for a refined process which can eliminate some of these limitations to economically and efficiently recover the valuable hydrocarbons from natural gas. One of the major limitations of the conventional processes was the inflexibility to meet the market demand. A process called the Mehra Process has been patented to solve some of these problems [9], in which a physical solvent is used for the removal and recovery of only desirable hydrocarbons from the gas stream. Basically, this is an extraction process since the volatility of hydrocarbons is increased on contact with a physical solvent. The equipment used for this process are arranged in two different configurations extractive-flashing and extractive-stripping. 

The same fundamental development as presented here for vapor-liquid flash calculations can be applied to liquid-liquid equilibrium separations. In this case, the feed splits into an extract at rate E and a raffinate at rate R, which are in equilibrium with each other. The compositions of these phases are... 

We have repeatedly observed that the slowly converging variables in liquid-liquid calculations following the isothermal flash procedure are the mole fractions of the two solvent components in the conjugate liquid phases. In addition, we have found that the mole fractions of these components, as well as those of the other components, follow roughly linear relationships with certain measures of deviation from equilibrium, such as the differences in component activities (or fugacities) in the extract and the raffinate. 

Remove most of the methanol by distillation on a steam bath, and dilute the residue with 100 ml. of water. Extract the mixture with ether, wash the upper layer with water, and dry it rapidly with a little anhydrous magnesium sulphate. Remove the ether by flash distillation, and distil the residual pale yellow oil under diminished pressure. Collect the m-nitrobenzyl alcohol at 183-185°/17 mm. it solidifies to a pale yellow solid, m.p. 30°, when cooled in ice. The yield is 13 g. 

The jellyfish can be extracted to yield a photoproteia, a complex of luciferia and apoaequoria that generates light (rapid flash, 460 nm) on... 

Many nonferrous metals can be extracted by reduction smelting, eg, copper, tin, nickel, cobalt, silver, antimony, and bismuth. Blast furnaces are sometimes used for the smelting of copper or tin, but flash and reverberatory furnaces are more common for metals other than lead. 

Desalination. A special case of distillation is water desalination. In places where energy is abundant but fresh water is not, eg, the Arabian Peninsula, water may be produced from seawater ia flash evaporators. Low pressure turbiae steam is extracted to provide heat for the evaporators. Coadeased steam is returned to the cycle. Such units may be particularly prone to corrosion by salts. Sizes vary, but a plant scheduled for completion in 1996 had six units and a total capacity of 345,600 m /d. Power generation was expected to be 17,500 MW (36). 

In a large number of processes, there ate unit operations related to vapot-Hquid separations distillation, absorption, extraction, stripping, flashing, and separation of Hquid and vapor stream arising from changes in temperatures and pressures. Calculations for these unit operations necessitate trial and... 

Fixed-roof atmospheric tanks require vents to prevent pressure changes which would othei wise result from temperature changes and withdrawal or addition of liquid. API Standard 2000, Venting Atmospheric and Low Pressure Storage Tanks, gives practical rules for vent design. The principles of this standard can be applied to fluids other than petroleum products. Excessive losses of volatile liquids, particularly those with flash points below 38°C (100°F), may result from the use of open vents on fixed-roof tanks. Sometimes vents are manifolded and led to a vent tank, or the vapor may be extracted by a recov-eiy system. 

Wiped film stills in place of continuous still pots —Centrifugal extractors in place of extraction columns —Flash dryers in place of tray dryers —Continuous reactors in place of batch —Plug flow reactors in place of CFSTRs —Continuous in-line mixers in place of mixing vessels... 

POCI3 was added to a solution of amide 62 (0.075g, 0.02 mmol) in toluene (5 mL). The reaction mixture was heated to 110 °C with stirring for 5 h, then cooled to rt. A solution of 2 N NaOH (10 mL) was added and the mixture was extracted with ether (3 x 15 mL). The combined organic extracts were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The crude product was then purified by flash chromatography on silica gel (40% Ethyl acetate/hexanes) to afford the 68 mg (95%) of the title compound as... 

Hyperaspine (1) was isolated from H. campestris by extraction with MeOH and subsequent flash chromatography (01TL4621). 

Flash chromatography is widely employed for the purification of crude products obtained by synthesis at a research laboratory scale (several grams) or isolated as extracts from natural products or fermentations. The solid support is based on silica gel, and the mobile phase is usually a mixture of a hydrocarbon, such as hexane or heptane, with an organic modifier, e.g. ethyl acetate, driven by low pressure air. (Recently the comparison of flash chromatography with countercurrent chromatography (CCC), a technique particularly adapted to preparative purposes, has been studied for the separation of nonchiral compounds [90].)... 

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