Back crude distillation column

Keeping the top tray temperature at an adequate margin above the dew point of the component A typical example is a refinery crude distillation column. Should top tray temperature fall below the dew point of water, water will condense on the top trays. The result will be equivalent to refluxing water back into the column. 

Ny lon-6 (108 g) carpet backed with calcium-carbonate-filled latex and polypropylene was charged to a 1000-mL three-neck round-bottom flask (equipped with a condenser) with 6 mL of 85% phosphoric acid. Superheated steam was injected continuously during a 45-min period. The vapor temperature of the reaction medium was 250-300°C. The volume of distillate collected was 1065 mL. The distillate contained 1.9% e-caprolactam (as determined by GC), which corresponded to a crude yield of 37.5%. The distillate was fractionated in a distillation column and the nonaqueous phase removed. The remaining aqueous phase was treated with 2% potassium permanganate at 40-50°C for 2 h. Evaporation of... 

The aromatics-laden or fat solvent is fractionated in a distillation column. The widely different boiling points of the solvent and aromatics make the separation relatively easy and clean. The solvent is recycled back to the beginning of the process. The arorhatic extract, called crude benzene, is usually passed through a clay treater to remove any olefins that sometimes get created in the process and then distilled once again to produce high purity benzene. 

Another advantage is that the final purification and working up of the wa waters can be tied in with the production of the crude ester. Figure 12-6 illustrates the essentials of this process. The raw materials are first blended in the correct proportions and fed from the feed tank in a steady stream throu a preheater into the esterifying column. From the top of the column is taken off a mixture of about -20 per cent ester, 10 per cent water, and 70 per cent alcohol, while a suitable amount of the same distillate is refluxed back to the column at (A). The ternary mixture taken off passes... 

After leaving the reactor, the reaction mixture consisting of aniline, water, and excess hydrogen is cooled and condensed prior to the purification steps. First, the excess hydrogen is removed and recycled back to the reactor. The rest of the mixture is sent to the decanter where the water and aniline are separated. The crude aniline, which contains less than 0.5% of umeacted nitrobenzene and about 5% water, is distilled in the crude aniline column. The aniline is further dehydrated in the finishing column to yield the purified aniline. Meanwhile, the aqueous layer from the decanter, which contains about 3.5% aniline, is extracted to recover the aniline and dean up the water before it is sent to the waste-water treatment plant. 

Propene and syngas are fed to the reactor, where the gases are intimately contacted with the ligand-modified rhodium catalyst in solution. The reaction exotherm is removed by a dedicated heat exchanger. The liquid effluent from the reactor passes to a degassing column where unreacted propylene and syngas is evaporated from the catalyst/product solution and recycled back to the reactor. In the fourth column the hydroformylation products are separated from the Rh-catalyst by distillation. While butyraldehydes leave the column over the top the catalyst remains at the bottom of the column dissolved in liquid heavy products of the process to be recycled back to the reactor. The crude aldehyde products undergo a further purification step in the crude aldehyde column prior to their transfer to the n/iso-butyraldehyde splitter column. 

The bottom of Figure 4 indicates one system for the handling of the crude with silt from the bottom of the column before, after, or without a heat exchanger to recover the sensible heat of the bottoms from this still. A continuous thickener, of the usual rotating type with hoes, thickens the suspended silt into an oil-mud which is removed, washed, and steamed before discard. The solvent recovered from this washing of mud goes back to the feed dissolution. The clear crude kerosene solution, now free of water and silt, has kerosene removed by distillation, or it is pumped to the refinery. Often where the crude does not contain too much water in a permanent emulsion or is not too difficult to pump, it would not require the initial dilution. 

Description The cut enters the pre-distillation tower, in which methyl acetylene, propadiene and other light components are separated as gaseous overhead product. Its bottom product enters the bottom section of the main washer column while NMP solvent enters at the column top. Overhead product raffinate consisting of butanes and butenes is drawn off. The loaded solvent is sent to the rectifier, which comprises a vertical plate in its upper section. In its first compartment, the less soluble butenes are stripped and fed back into the main washer. In its second compartment, the acetylenes are separated from crude butadiene (BD) due to their higher solubility in NMP. 

Distillation is widely used in the petroleum and chemical industries. A sophisticated distillation apparatus is used to separate the numerous organic components of crude oil, including petroleum ether, gasoline, kerosene, and jet fuel fractions. This requires fractional distillation, in which part of the v q)or recondenses in a fractionatii column that would be mounted vertically on top of the distillation flask in the apparatus shown in Figure 2.11. The most-volatile components enter into the condenser and are condensed back to liquid products less-volatile liquid constituents return to the distillation flask. The net effect is that of numerous distillations, which gives a very efficient separation. 

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