Reflux cycle

To perform a dialytic extraction, the apparatus is assembled and preextracted for 48 hours using pyridine and methylene chloride outside and inside the membrane, respectively. The coal ftvlOO g) is then slurried in a 2-3 fold excess of pyridine (ACS reagent grade) and placed in the sample compartment, where it is constantly stirred. The methylene chloride reflux is begun at this point, and the extract collects in the receiver. When the buildup of pyridine in the receiver results in stoppage of the reflux cycle, the contents of the receiver are collected, and it is refilled with clean methylene chloride. The overflow from the sample compartment was evaporated under a flow of dry nitrogen, redissolved in pyridine, and replaced in the sample compartment daily. The dialytic extraction is slower than the soxhlet procedure, and the yield is substantially less. For example, the yield of a four day dialytic extraction of Powhatan Coal was 6%, while a two day pyridine soxhlet on the same coal yields 12-15% extract. 

Some control systems may induce an instability known as "reflux cycle (68) in gravity systems. This is discussed in Sec. 19.2. 

For those columns with gravity return reflux, a severe oscillation in overhead vapor flow to the condenser is sometimes encountered. This is commonly called reflux cycle and has a typical period of several minutes. It has been observed primarily in columns where reflux flow is the difference between rate of condensation and distillate flow rate that is, where distillate is on automatic flow control or column-composition control. Reversing the controls—that is, employing automatic reflux flow or flow-ratio control and allowing distillate to be the difference flow—provides a positive cure. 

Keep condensate subcooling to a minimum. If subcooling is zero, there will be no reflux cycle. 

Product On single cracking of fuel oil (I ( le) On repeated cracking in tandem of heavy reflux (cycles II-XV) Total throughout light cracking process... 

The lean oil from the lean-oil fractionator passes through several heat exchangers and then through a refrigerator where the temperature is lowered to —37° C. Part of the lean oil is used as a reflux to the lower section of the rich-oil deethanizer. Most of the lean oil is presaturated ia the top section of the deethanizer, is cooled again to —37° C, and is returned to the top of the absorber, thus completing the oil cycle. 

Heavy cycle oil, heavy naphtha, and other circulating side pumparound reflux streams are used to remove heat from the fractionator. They supply reboil heat to the gas plant and generate steam. The amount of heat removed at any pumparound point is set to distribute vapor and liquid loads evenly throughout the column and to provide the necessary internal reflux. 

A dual reflux PSA cycle with both stripping and enriching has been proposed to obtain high enrichment and recovery. The separation is much better than that obtainable by normal PSA and suggests that it is possible to obtain two nearly pure products from a dilute feed stream [see Mclntire et al., Ind. Eng. Chem, Res., 41, 3499 (2002)]. 

Essentially, polarity is alternation. Therefore, the esoteric use of polarity is the knowledge of alternation, of the tides of flux and reflux, within and without. There is only now, the present moment. In the daily cycle, now is constant, but at a certain phase, day predominates, and at another, night. When engaged in conversation, you may be in an active mode (the speaker) at one moment and in a passive mode (the listener) at another, although, the conversation (an act of mental communion through physical instrumentality) is constant, regardless of which participant is in which polarity. 

Methoxy-2 -methylbiphenyl. o-Tolylboronic acid, 10.0 g (73.6 mmol) (Note 1), 16.8 g (71.8 mmol) of 4-iodoanisole (Note 2), and 200 mL of acetone (Note 3) are combined in a 1-L, three-necked flask equipped with an efficient stirbar, two stoppers, and a reflux condenser attached to a gas-flow adapter with a stopcock. Potassium carbonate, 25.0 g (0.180 mol), is dissolved in 200 mL of water (Note 4) in a separate 250-mL Schlenk flask. In a third flask (25-mL Schlenk flask) 3.30 mg (0.02 mmol, 0.2%) of palladium acetate (Note 5) is dissolved in 10 mL of acetone. All three flasks are then thoroughly degassed by four freeze-pump-thaw cycles. Under an argon back flow, one of the stoppers on the three-necked flask is replaced with a rubber septum, and the carbonate and catalyst solutions are added via cannula to form a biphasic mixture. The top layer turns brown upon addition of the catalyst. The septum is... 

In this reaction, the initially introduced Se02, insoluble in organic solvent, is converted to soluble SeCO by CO (30 atm) under reflux in toluene, which is the active catalyst for the reductive carbonylation of nitrobenzene or nitropyridine. The metallic selenium (insoluble) is also converted to SeO under CO pressure. After completion of the reaction, soluble selenium catalyst solution was readily recovered by simple filtration and reused. The recovered catalyst solution was used for five cycles without loss of activity. 

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