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Vacuum Column

Where is naphthenic acid corrosion found Naphthenic acid corrosion occurs primarily in crude and vacuum distillation units, and less frequently in thermal and catalytic cracking operations. It usually occurs in furnace coils, transfer lines, vacuum columns and their overhead condensers, sidestream coolers, and pumps. [Pg.264]

Isolation valves in the line from a vacuum column to the steam ejectors producing the vacuum. [Pg.240]

The relative volatility will change as the compositions and (particularly for a vacuum column) the pressure changes up the column. The column pressures cannot be estimated until the number of stages is known so as a first trial the relative volatility will be taken as constant, at the value determined by the bottom pressure. [Pg.514]

Pressure drop. The pressure drop over the plates can be an important design consideration, particularly for vacuum columns. The plate pressure drop will depend on the detailed design of the plate but, in general, sieve plates give the lowest pressure drop, followed by valves, with bubble-caps giving the highest. [Pg.561]

The pressure drop per equilibrium stage (HETP) can be lower for packing than plates and packing should be considered for vacuum columns. [Pg.589]

Calculation of the pressure drop and flooding rate is particularly important for vacuum columns, in which the pressure may increase severalfold from the top to the bottom of the column. When a heat-sensitive liquid is distilled, the maximum temperature, and hence the pressure, at the bottom of the column is limited and hence the vapour rate must not exceed a certain value. In a vacuum column, the throughput is very low because of the high specific volume of the vapour, and the liquid reflux rate is generally so low that the liquid flow has little effect on the pressure drop. The pressure drop can be calculated by applying equation 4.15 over a differential height and integrating. Thus ... [Pg.230]

For vacuum columns, where both absolute pressure and tray pressure drops vary significantly, a rigorous vapor-hydraulic model may have to be used. The modeling and simulation are easy. The numerical integration is quite difficult. This is because the ODEs become very, very stilT when vapor hydraulics are included in the model. [Pg.142]

The excess water is removed in a stripper column. The other three pieces of hardware in Figure 10-5—vacuum columns—are used to recycle the EO and to clean up the EG by splitting out the heavier glycol by-products. [Pg.151]

The older tall oil distillation columns used bubble cap trays. In new columns, structured packing is preferred. Because of the low pressure drop of structured packing, steam injection is no longer necessary. The low liquid holdup of this packing minimizes the reactions of the fatty and resin acids. A specific distillation sequence for vacuum columns using structured packing of Sulzer has been described (26). Depitching is carried out at a vacuum of... [Pg.306]

The first instruments applying differentially pumped vacuum columns were mainly used for low-magnification imaging and electron diffraction investigations... [Pg.80]

A -Acetyltyrosine methyl ester (400 mg, 1.68 mmol) and 3,5-dichloro-l-fluoropyridinium triflate (lm 632 mg, 2 mmol) were stirred under N2 in dry CH2Cl2/MeCN (10 mL, 9 1). After 8 h the starting material and reagent were consumed. The reaction mixture was poured into H20 (10 mL), neutralized with NaHC02, and separated. The organic layer was washed with H20 (10 mL), dried (Na2S04) and concentrated under reduced pressure. The crude product was purified by vacuum column chromatography (silica gel, 60% EtOAc/petroleum ether, bp 35-60 JC) yield 280 mg (65%). [Pg.445]

We found approximately 2-4 grams of caprylic, 2-5 grams of capric, and 1-2 grams of lauric acid/100 liters in our experimental continuous still beverage brandies but usually less than 1 gram of each per 100 liters in unaged commercial brandy distillates (II). New commercial brandy distillates made from fortified wine contain less than those distilled from straight dry wine. Distillates from a continuous vacuum column and a pilot pot still also contain less. [Pg.258]

This residue is further heated and introduced into a vacuum column operated at an absolute pressure of about 50 millimeters of mercury, a vacuum maintained by the use of steam ejectors. A flash separation is made to produce heavy gas oil and nondistillable pitch. [Pg.1256]

Revamps. The pressure drop advantage is invaluable in vacuum column revamps, can be translated to a capacity gain, an energy gain, a separation improvement, or various combinations of these benefits. Likewise, for towers in the suction of compressors, replacing trays by packings reduces the compression ratio and helps debottleneck the compressor. [Pg.80]

Entrainment is kept at a minimum by a wash oil section in the vacuum unit and checked with a colour specification on the FCC feed. The "real" FCC resid cracking seems to start, when the wash oil stream in the vacuum column is also routed to the FCC unit, obviously the colourof the FCC feed will deteriorate strongly. [Pg.324]

The remaining solution was diluted with DCM (2 ml), and m-chloroperbenzoic acid (mCPBA) (0.30 g, 2.0 mmol) was added portionwise. After stirring at RT for 40 h, the mixture was extracted with DCM and washed successively with aqueous sodium sulfite solution, aqueous sodium bicarbonate solution and water, dried (MgS04) and evaporated in vacuum. Column chromatography (45-70% ether-petrol, gradient elution) of the residue afforded the title epoxides (3aa,6a,7a,7aa)-6,7-epoxy-3a,6,7,7a-tetrahydrobenzo[d]-l,3-dioxol-2-one (73 mg, 47%) mp 87°-89°C and (3aa,6p,7p,7aa)-6,7-epoxy-3a,6,7,7a-... [Pg.441]

Tetrafluoroboric acid-diethyl ether complex (catalytic amount) was added to a stirred solution of epoxide (+/-)-(3aa,6a,7a,7aa)-6,7-epoxy-3a,6,7,7a-tetrahydrobenzo[d]-l,3-dioxol-2-one (32 mg, 0.2 mmol) and (R)-(+)-sec-phenethyl alcohol (0.048 ml, 0.4 mmol) in DCM at RT under argon. After 30 min, water was added and the mixture extracted with DCM (3 times). The combined organic phase was dried (MgS04) and evaporated in vacuum. Column chromatography (30-75% ether-petrol, gradient elution) of the residue afforded the alcohols [3aR-[3aa,4a,5p(R),7aa]-3a,4,5,7a-tetrahydro-4-hydroxy-5-(l-phenylethoxy)benzo[d]-l,3-dioxol-2-one and [3aS-[3aa,4a,5P(R),7aa]-3a,4,5,7a-tetrahydro-4-hydroxy-5-(l-phenylethoxy)benzo[d]-l,3-dioxol-2-one. (37 mg, 67%) as a thick oil and a 1 1 mixture of diastereomers. Subsequent HIPLC (l -Dynamax 83,123-6 column 6% isopropanol-petrol, 15 ml/min) effected separation of the diastereomers. Less polar [3aR-[3aa,4a,5p(R),7aa]-3a,4,5,7a-tetrahydro-4-hydroxy-5-(l-phenylethoxy)benzo[d]-l,3-dioxol-2-one had retention time 16.3 min [a]D2° +90.1° (c 1.1, CHCI3). [Pg.442]

Camphorsulphonic acid monohydrate (catalytic amount) was added to a stirred solution of [lR-[la,2a,3 3,4a(R),5a,6a)-3-benzyloxy-5,6-epoxy-4-(l-phenylethoxy)cyclohexane-l,2-diol (0.321 g, 0.9 mmol) in 2,2-dimethoxypropane (10 ml) at RT under argon. After 16 h, the mixture was poured into DCM and washed with aqueous sodium bicarbonate solution and water. The aqueous layers were reextracted with DCM and the combined organic extracts dried (MgS04) and evaporated in vacuum column chromatography (50% ether-petrol) of the residue afforded the title epoxy acetonide (0.317 g, 89%) as needles, m.p. 114°-115°C (recrystallized from ether-petrol) [a]D2°+134.1° (c 1.00, CHCI3). [Pg.443]

The l,3-dioxane-2-ethanol (2 ml) was added dropwise to sodium hydride (396 mg of 60% dispersion, 10 mmol) at RT under argon. When the effervescence had ceased, l l,N,N, N -tetramethylenediamine (TMEDA) (1 ml) was added, the mixture stirred for a further 4 h and then a solution of the epoxide (396 mg, 1.0 mmol) in TMEDA (1.0 ml) was added dropwise. The mixture was stirred at 100-110°C for 3 days and then allowed to cool to RT. Water was added and, after 5 min the mixture extracted with ether. The extract was washed with water and the aqueous phase reextracted with ether. The combined organic extracts were dried (MgS04) and evaporated in vacuum column chromatography (4% MeOH-10% ether-86% petrol) of the residue afforded [2(R)]-L-3-0-Benzyl-4,5-0-isopropylidene-6-0-[2-(5,5-dimethyl-l,3-dioxan-2-yl)ethyl]-2-0-(l-phenylethyl)-muco-inositol (176 mg, 31%), [a]D20 +63.4° (c 1.4, CHCI3) and [S(R)]-D-4-0-Benzyl-2,3-0-isopropylidene-6-0-[2-(5,5-dimethyl-l,3-dioxan-2-yl)ethyl]-5-0-(phenylethyl)-myo-inositol (273 mg, 48%), mp 108°-110°C, [a]D20+ 29.3° (c 0.76, CHCI3) as a thick oil and a white solid respectively, and starting epoxide (65 mg, 16%). [Pg.443]

The initiating event corresponds to a leakage in any mechanical equipment, pipe or flange, located between the vacuum column C-201 and the decomposition reactor E-207, as shown in Figure 6. Since the pipeline will be under severe conditions of acidity, pressure and temperature, an occurrence frequency of 5.23E-5/year is assumed, which is the generic value for catastrophic pipe failure (including straight pipe and connections) (Bari, 1985). [Pg.403]


See other pages where Vacuum Column is mentioned: [Pg.447]    [Pg.239]    [Pg.306]    [Pg.336]    [Pg.337]    [Pg.1327]    [Pg.1399]    [Pg.228]    [Pg.301]    [Pg.342]    [Pg.496]    [Pg.556]    [Pg.227]    [Pg.228]    [Pg.229]    [Pg.640]    [Pg.141]    [Pg.336]    [Pg.337]    [Pg.448]    [Pg.402]    [Pg.63]    [Pg.80]    [Pg.45]    [Pg.281]    [Pg.387]    [Pg.441]    [Pg.444]    [Pg.203]   
See also in sourсe #XX -- [ Pg.151 ]

See also in sourсe #XX -- [ Pg.5 , Pg.8 ]




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