Crude feed

Fractionator-feed preheaters partially vaporize charge stock from an upstream unfired preheater en route to a fractionating column. A typical refinery application a crude feed to an atmospheric column enters the fired heater as a liquid at 505 K (450°F) and leaves at 644 K (700°F), having become 60 percent vaporized. 

The VPS overhead consists of steam, inerts, condensable and non-condensable hydrocarbons. The condensables result from low boiling material present in the reduced crude feed and from entrainment of liquid from the VPS top tray. The noncondensables result from cracking at the high temperatures employed in the VPS. Inerts result from leakage of air into the evacuated system. Steam and condensable hydrocarbons are condensed using an overhead water-cooled condenser. The distillate drum serves to separate inerts and non-condensables from condensate, as well as liquid hydrocarbons from water. Vacuum is maintained in the VPS using steam jet ejectors. 

In this process use is made of an endothermic reaction between the aluminum (in the vapor form) in the crude feed material and gaseous aluminum trichloride... 

Process inputs Ranges from crude feed stocks with variable properties to high purity materials Pure, high quality raw materials... 

Nature of the feed stock to the unit. Adding 10 to 15% cracked residuum to a reduced crude feed increased the lump yield 10 to 15% at constant temperature and constant soaking time. 

One Ninian stabilization train was commissioned to prove the plant and to provide gas for power and steam generation. Very early in the commissioning operation, however, severe foaming occurred in the second-stage (low-pressure LP ) gas/oil separator, which operated at 0 7 bar gauge [10 Ibf/sq in ], when the temperature of the initial dead-crude feed was raised to 9I4°F ]490°C. As a result, large quantities of crude were carried into ihe flare relief system. 

To avoid reliance on foam inhibitor addition, a plant iumution assessment was conducted to determine the maximum crude feed rate that could be handled. This was found to be only 40% of the design rate, which is equivalent to a crude resistance time of 8.0 and 11.5 minutes in the HP and LP separators, respectively. To install additional vessels to compensate for this would have been both difficult and costly. 

Figure 6.5 is a plot of the liquid level in a crude preflash drum versus time. We were steadily withdrawing 10 percent more flashed crude from the bottoms pump, than the inlet crude feed rate. The rate of decline of the liquid level noted in the control center was only about 25 percent of our calculated rate. Suddenly, when the apparent level in the control room had reached 40 percent, the level indication started to decline much more rapidly. Why ... 

From the perspective of a generalized analytical or preparative purification strategy, it is obviously desirable to select chromatographic conditions in which the In k at f (or In (1 /[ C, ])) retention dependencies approximate case a or case b, rather than cases c and d. For the latter two cases the KassoCj, of the biosolute for the stationary phase is obviously too high, the desorption window suitable for elution is too narrow, and the mass (or bioactivity) recovery potentially is at risk. However, with crude feed stocks implementation of the case a or d scenario should not necessarily be excluded out of hand from a selectivity point of view. For example, situations have been... 

Additional stages can be used in series to gain additional reductions in the salt content of the crude oil. Two stages are typical, but some installations use three stages. About 90 percent of the emulsified water can be recovered in one step, whereas 99 percent recovery is possible with a two-step process.9 The additional investment for multiple stages is offset by reduced corrosion, plugging, and catalyst poisoning of downstream equipment with the cleaner crude feed. 

The distillation train first separates the benzene/toluene byproduct from main crude styrene stream (8). Unconverted EB is separated from styrene (9) and recycled to the reaction section. Various heat recovery schemes are used to conserve energy from the EB/SM column system. In the final purification step (10), trace C9 components and heavies are separated from the finished SM. To minimize polymerization in distillation equipment, a dinitrophenolic type inhibitor is co-fed with the crude feed from the reaction section. Typical SM purity ranges between 99.90% and 99.95%. 

Free fatty acids (as Cl 6 0) %) Same as crude feed 0.10% max. 

A dual-solvent fractional extraction process can provide a powerful separation scheme, as indicated by the examples given above, and some authors suggest that fractional extraction is not utilized as much as it could be. In many cases, instead of using full fractional extraction, standard extraction is used to recover solute from a crude feed and if the solvent-to-feed ratio is less than 1.0, concentrate the solute in a smaller solutebearing stream. Another operation such as crystallization, adsorption, or process chromatography is then used downstream for solute purification. Perhaps fractional extraction schemes should be evaluated more often as an alternative processing scheme that may have advantages. 

In the second area, a purified compound is needed to obtain a final product, and the cost of the production of the compoxmd is an important cost factor that will have to be minimized. The production will last a significant period of time, whether it is continuous or by batches rrm periodically, and the operation is relatively routine. The cost components, equipment, solvent, packing material, crude feed, and downstream processing become prominent and must be taken into account together. Then significant investment in the design of the separation process is required for a careful optimization of the experimental conditions. Optimization procedures are discussed in Chapter 18. 

Feed cost (FeC) The part of the separation or purification costs corresponding to the amoimt of crude feed lost during the operation because of a recovery yield, Y, below 100%. The feed costs are proportional to 1 — Y. See Chapter 18, Section 18.2.1. 

Each curve in Fig. 6 is analogous to a population distribution curve for the molecules in the crude feed and products. Each could also be represented as weight or volume distribution. The curves are constructed from the amoimts of material with atmospheric boiling points in, for example, three-degree boiling range intervals in the precision distillation or gas chromatographic analyses. 

Desalted hot crude oil feed is sent to a preflash column where it is separated into gas, gasoline, naphtha, and topped crude as shown in Figure 9.5. Using column modules representation, determine the number of degrees of freedom for this operation. What specifications may be used to define the column performance The crude feed is of fixed composition and thermal conditions. The stripping steam thermal conditions are fixed, but its flow rate may be varied. The column pressure is independently fixed. 

Comparison of Base Stock Yields and Their Distributions from 20,000 bpd Reduced Crude Feed to a Solvent Refined... 

While these cases were based upon a light crude feed, other cases which have been run using heavier crudes show much the same result. 

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