Lighting cycle

The gas oil cut from catalytic cracking called Light Cycle Oil (LCO), is characterized by a very low cetane number (about 20), high contents in aromatics, sulfur and nitrogen, all of which strongly limit its addition to the diesel fuel pool to a maximum of 5 to 10%. 

A light distillate cut (light cycle oil - LCO) similar to gas oil but having high aromaticity and low cetane number. 

Table 7. Separation of Aromatics from Nonaromatics in Light Cycle Oil...

Figure 4.12 (a) Surface response plot of a light cycle oil analysed by GC X GC. The col-... 

Light cycle oil (LCO)—used as a pumparound stream, sometimes as absorption oil in the gas plant, and stripped as a product for diesel blending and... 

In many units, the light cycle oil (LCO) is the only sidecut that leaves the unit as a product. LCO is withdrawn from the main column and routed to a side stripper for flash control. LCO is sometimes treated for sulfur removal prior to being blended into the heating oil pool. In some units, a slipstream of LCO, either stripped or unstripped, is sent to the sponge oil absorber in the gas plant. In other units, sponge oil is the cooled, unstripped LCO. 

The vapor from the primary absorber or the presaturator contains a small quantity of gasoline. The sponge oil absorber recovers this gasoline. Sponge oil is stripped or unstripped light cycle oil. It is used for final absorption of the dry gas stream. Instead of LCO, a... 

Products from the reactor are recovered in the main fractionator a J the gas plant. The main fractionator recovers the heaviest produc, such as light cycle and decanted oil, from the gasoline and ligh r products. The gas plant separates the main fractionator overhead vap< s into gasoline, Cj s, C4 s and fuel gas. The products contain sulfur compounds and need to be treated prior to being used. A combination of amine and caustic solutions are employed to sweeten these products... 

In addition, some of the nitrogen compounds end up in light cycle oil (LCO) as pyrolles and pyridines [5]. These compounds are easily oxidized and will affect color stability. The amount of nitrogen in the LCO depends on the conversion. An increase in conversion decreases the percentage of nitrogen in the LCO and increases the percentage on the catalyst. 

Adding residue to the feed increases the sulfur content of coke proportional to the incremental sulfur in the feed (Table 2-6). Thiophenic (ring-type) sulfur compounds crack more slowly, and the uncracked thiophenes end up in gasoline, light cycle oil, and decanted oil. 

Antimony-based passivation was introduced by Phillips Petroleum in 1976 to passivate nickel compounds in the FCC feed. Antimony is injected into the fresh feed, usually with the help of a carrier such as light cycle oil. If there are feed preheaters in the unit, antimony should be injected downstream of the preheater to avoid thermal decomposition of the antimony solution in the heater tubes. 

Lower cloud point in the diesel fuel. Isoparaffins in the light cycle oil boiling range improve the cloud point. 

Feed - (light cycle oil + heavy cycle oil + decanted oil) Feed... 

A refiner has several options to increase LCO yield. Since it is often desirable to maintain a maximum cracking severity while maximizing light cycle oil yield, the simplest way to increase LCO yield is to reduce the gasoline end point. Gasoline end point is usually reduced... 

Engelhard Corporation, Maximizing Light Cycle Yield, The (... 

The thermal and catalytic cracking of PP, PS, and SBR waste, dissolved in light cycle oil, was studied in a riser simulator. 19 refs. 

These rhythms seem to be innately programmed although they can be adjusted. For instance, in a normal environment, the sleep-waking cycle of humans is obviously synchronised ( entrained ) with the (24-h) dark-light cycle whereas it assumes a period of around 25-27 h in a (time-free) environment where there are no diurnal cues. Interestingly, when humans are in a time-free environment, the change in the rhythm of... 

Figure 22.1 Pathways projecting to and from the suprachiasmatic nucleus (SCN). Inputs from photoreceptors in the retina help to reset the circadian clock in response to changes in the light cycle. Other inputs derive from the lateral geniculate complex and the serotonergic, Raphe nuclei and help to reset the SCN in response to non-photic stimuli. Neurons in the SCN project to the hypothalamus, which has a key role in the regulation of the reproductive cycle, mood and the sleep-waking cycle. These neurons also project to the pineal gland which shows rhythmic changes in the rate of synthesis and release of the hormone, melatonin...

The rate of melatonin synthesis is controlled primarily by the release of noradrenaline from sympathetic fibres originating in the superior cervical ganglion. The activity of these neurons and, consequently, the synthesis and release of melatonin, follows a circadian rhythm such that sympathetic input and melatonin synthesis are both increased in the dark. This coupling with the light cycle certainly involves the SCN since destruction of this nucleus greatly reduces the fluctuations in melatonin production. Moreover, retrograde transneural tracing has shown that there is a neuronal pathway... 

Throughout these studies, adult female Sprague-Dawley rats weighing about 250 gm were used. During experimentation, they were housed in individual plastic cages. Purina Rat Chow and water were available a d 1 i hi turn. and they were maintained under an automated light cycle with illumination from 6 a.m. to 10 p.m. daily. 

Group 3 Loss of pump around flow. This grouping comprises malfunctions associated with the circulation of fluids through and around the main fractionator. The loss of one or more pump flows (slurry, light cycle oil, naphtha, and heavy cycle oil) leads to the loss of some of the fractionator heat sink. 

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