Vacuum crude still

In the following discussion of design-parameters, it should be evident that not all parameters are of equal importance in all operations. Pressure drop, for example, is of central importance in vacuum crude stills-but of little import in the liquid-liquid extraction of penicillin from fermentation mashes stage efficiency is not important in the design of a whiskey distilling column, which requires few stages, but it can be critical for a deisobutanizer, which may require over 100 stages. 

Figure 6-3. Vacuum crude still. This 40-ft ID tower was revamped from trays to random packing.

Vacuum Crude Stills Coefficient d for Heat Transfer Equation 6-25... 

Water Cooling Theory, Cooling Tower Design, Cooling Tower Fill, Gas Quench Towers, Quench Tower Design, Total Condenser Theory, Total Condenser Design, Partial Condenser Theory, Chlorine Gas Cooling, Vacuum Crude Stills, Atmospheric Crude Stills, Olefin Primary Fractionator, Olefin Water Quench Tower, Example Problem, Notation, References... 

Vacmun crude still— A vacuum tower that processes the bottoms from an atmospheric pressure distillation of crude oil. 

The camphorquinone can be purified in either of two ways, (i) To save time, the drained but still damp material can be recrystallised from water containing 10% of acetic acid, the hot filtered solution being cooled and vigorously stirred. The quinone separates as brilliant yellow crystals (yield, 2 5 g.), m.p. 192-194 , increased to 196-197 by a second reciystal-lisation. (ii) The crude camphorquinone can be dried in a vacuum desiccator (weight of dry quinone, 5 g.), and then recrystallised from petroleum (b.p. 100-120 ), the hot solution being filtered through a fluted paper in a pre-heated funnel. The quinone separates in beautiful crystals, m.p. 196-197 , 2 8 g. 

Early in the 17th century, there was still vigorous disagreement as to the feasibility of empty space Descartes denied the possibility of a vacuum. The matter was put to the test for the first time by Otto von Guericke (1602-1686), a German politician who devoted his brief leisure to scientific experimentation (Krafft 1970-1980). He designed a crude suction pump using a cylinder and piston and two flap valves, and... 

In two stage units, it is often economical to distill more gas oil in the vacuum stage and less in the atmospheric stage than the maximum attainable. Gas formed in the atmospheric tower bottoms piping at high temperatures tends to overload the vacuum system and thereby to reduce the capacity of the vacuum tower. The volume of crude vaporized at the flash zone is approximately equal to the total volume of distillate products. Of course, the vapor at this point contains some undesirable heavy material and the liquid still contains some valuable distillate products. The concentration of heavy ends in the vapor is reduced by contact with liquid on the trays as the vapor passes up the tower. This liquid reflux is induced by removing heat farther up in the tower. 

A 500-ml, three-necked, round-bottom flask is equipped with a condenser, a dropping funnel, and a thermometer in the reaction mixture. In the flask is placed a mixture of 85% hydrazine (115 ml, 118 g) and 225 ml of 95% ethanol with a few boiling chips. The solution is brought to reflux (mantle) and cinnamaldehyde (100 g, 0.76 mole) is added dropwise over about 30 minutes followed by an additional 30 minutes of refluxing. A still head is attached to the flask and volatiles (ethanol, water, hydrazine hydrate) are slowly distilled at atmospheric pressure until the pot temperature reaches 200° (about 3 hours). Hereafter, phenylcyclopropane is collected over the range 170-180°. When the pot temperature exceeds 250°, the recovery is complete. The crude product (55-65 g) is washed twice with 50-ml portions of water and dried (anhydrous potassium carbonate). Distillation under vacuum through a short column affords the product, bp 60°/13 mm, 79-80°/37 mm, n f 1.5309, about 40 g (45%). 

The residuum from vacuum distillation became, and still is, the basic component of residual fuel oil. It contains the heaviest fraction of the crude, including all the ash and asphaltenes. It is extremely high in viscosity and must be diluted with light distillate flux (a low viscosity distillate or residual fraction which is blended with a high viscosity residual fraction to yield a fuel in the desired viscosity range) to reach residual fuel viscosity. The lowest value distillates, usually cracked stocks, are used as flux. In some cases the vacuum residuum is visbroken to reduce its viscosity so that it requires less distillate flux. 

Caustic that is added downstream of the crude oil desalter. Caustic is injected downstream of the desalter to control overhead corrosion. Natural chloride salts in crude decompose to HCl at typical unit temperatures. Caustic reacts with these salts to form sodium chloride. Sodium chloride is thermally stable at the temperature found in the crude and vacuum unit heaters. This results in sodium chloride being present in either atmospheric or vacuum resids. Most refiners discontinue caustic injection when they process residue to the FCC unit. It can still be present in purchased feedstocks, however. 

Crude 2-nitrotoluene, containing some hydrochloric and acetic acids, was charged into a vacuum still with flake sodium hydroxide to effect neutralisation prior to distillation. An explosion occurred later. Similar treatments had been used uneventfully previously, using the weaker bases lime or sodium carbonate for neutralisation. It seems likely that the explosion involved formation and violent decomposition of the sodium salt of an aci-nitro species, possibly of quinonoid type. 

Two attempts to purify the crude material by vacuum distillation led to sudden exothermic decomposition of the still contents. Distillation in steam was satisfactory. 

The asphaltic residuum from atmospheric distillation amounts to roughly one-third (U.S. average) of the crude charged. This material is sent to vacuum stills, which recover additional heavy gas oil and deasphalting feedstock from the bottoms residue. 

The dinitro product is then cooled and filtered (the spent acid hquor is recoverable), the cake is washed with water, and the resulting washwater is sent to the wastewater treatment plant. The dinitro compound is then dissolved in an appropriate solvent and added to the amination reactor with water and soda ash. An amine is then reacted with the dinitro compound. The crude product is passed through a filter press and decanter and finally vacuum distilled. The saltwater layer from the decanter is discharged for treatment. The solvent fraction can be recycled to the reactor, and vacuum exhausts are caustic scrubbed. Still bottoms are generally incinerated. 

Crude biodiesel is initially purified by thoroughly washing the ester phase with water or by neutralization with a polyprotic mineral acid to eliminate base catalyst residues. Next, in a settling tank, an aqueous phase, salt precipitates, and biodiesel are separated. Another water washing step follows to further remove polar compounds that might still be present in the biodiesel product. Finally, the biodiesel is vacuum distillated at moderate-to-high temperatures (around 190-270°C) to comply with ASTM specifications (99.6% or purer). ... 

A soln of 3-benzoylbenzoic acid (23, R1 = Ph 2.0 g, 9 mmol), hydroxylamine hydrochloride (2.00 g, 29 mmol), and pyridine (2.00 mL, 25 mmol) in EtOH was refluxed for 12 h (Scheme 12). After the usual extractive workup, a white solid was obtained (2.41 g). The product 34 (R = Ph) still contained traces of pyridine, but it was used in the next step without further purification. The crude product (2.00 g, 8mmol) was dissolved in EtOH (200mL), and 10% Pd/C (2.00g) and coned HC1 (1.3mL, 16mmol) were added. The mixture was hydrogenated (1550 Torr) for lh. The catalyst was filtered off, and the mixture was concentrated. Upon trituration of the residue with Et20 and drying under vacuum, 22 (R = Ph) was obtained as a solid yield 2.12 g (97%). 

In a 500 ml round-bottomed flask equipped with a magnetic stirrer are placed 22 5 g (0 105 mole) of powdered sodium metaperiodate and 210 ml of water The mixture is stirred and cooled m an ice bath (Note 1), and 12 4 g (0 100 mole) of thio-anisole (Note 2) is added The reaction mixture is stirred for 15 hours at ice-bath temperature and is then filtered through a Buchner funnel The filter cake of sodium iodate is washed with three 30-ml portions of methylene chloride The wrater methylene chloride filtrate is transferred to a separatory funnel, the lower methylene chloride layer is removed, and the water layer is extracted with three 100-ml portions of methylene chloride The combined methylene chloride extracts are treated with activated carbon (Note 3) and dried over anhydrous sodium sulfate (Note 4) The solvent is removed at reduced pressure to yield 13 6-13 9 g of a slightly yellow oil (Note 5) which crystallizes on cooling The crude sulfoxide is transferred to a 25 ml distillation flask with the aid of a small amount of methylene chloride After removal of the solvent, a pinch of activated carbon is added to the distillation flask (Note 6) Simple vacuum distillation (Note 7) of the crude product through a short path still affords 12.7-12 8 g (91%) of pure methyl phenyl sulfoxide, b p 78-79° (0 1 mm ), m p. 33-34° (Notes 8 and 9)... 

Charge stock for the catalyst testing experiment was prepared by topping a sample of the in situ crude shale oil to 600°F in a batch still equipped with a column having 35 trays and then separating the 600°— 1000°F fraction in a vacuum flash distillation unit. Properties of the 600°-1,000°F fraction of in situ crude shale oil are shown in Table III. 

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