Naphtha streams

Raffinate. In extraction processes, the stream that has had the extracted material removed from it is called raffinate, in contrast to the other produced stream, the extract. Usually associated with aromatics extraction from naphtha streams. 

In 2000 two major petrochemical companies installed process NMR systems on the feed streams to steam crackers in their production complexes where they provided feed forward stream characterization to the Spyro reactor models used to optimize the production processes. The analysis was comprised of PLS prediction of n-paraffins, /xo-paraffins, naphthenes, and aromatics calibrated to GC analysis (PINA) with speciation of C4-C10 for each of the hydrocarbon groups. Figure 10.22 shows typical NMR spectral variability for naphtha streams. Table 10.2 shows the PLS calibration performance obtained with cross validation for... 

Figure 10.22 H process NMR spectra and related chemistry of naphtha streams feeding a steam cracker.

The model was then solved for the total refinery network and the PVC petrochemical complex. As shown in Table 5.4, the proposed model redesigned the refinery network and operating policies and also devised the optimal production plan for the PVC complex from all available process technologies. The model selected gas oil, an intermediate refinery stream, as the refinery feedstock to the petrochemical complex as opposed to the normally used light naphtha feedstock in industrial practice. In fact, this selection provided the optimal strategy as the light naphtha stream was used instead in the gasoline... 

Aluminum Chloride Processing A refining method using aluminum chloride as a catalyst to improve the appearance and odor of steam cracked naphtha streams. Aluminum chloride functions as a catalyst for the polymerization of olefins into higher-molecular-weight, less-problematic compounds. 

Example 5.2 Assume that a typical hydrocarbon naphtha liquid from a fractionation tower-side cut stream is to be cooled to 150°F. The naphtha stream enters the air cooler at 250°F at a flow rate of 273,000 lb/h. The physical tube-side properties at the average temperature of 200°F are ... 

Table 10.4 Ethylene and Propylene from Low Value Naphtha Streams...

Gasoline is usually produced as a blend of several petroleum streams that boil in the range of naphtha. A typical gasoline might contain 50% by volume of cracked naphtha with benzene content between 0.5 wt% and 2.0 wt% and 25% by volume of catalytically reformed naphtha with benzene content between 1 wt% and 3 wt%. Estimate the cost per gallon of gasoline of reducing the final benzene content to 0.62% by volume. Compositions of other components in the naphtha streams can be found in the patent literature. 

In Example 9.9, separation strategy is considered for producing pentanes from a naphtha stream. The above heuristic rules are taken into account as well as other factors that are specific to the problem. 

A mixture of primarily C5 components is to be separated from a naphtha stream containing hydrocarbons ranging from C3 to CIO. It is proposed to utilize two existing columns to carry out the separation, one having 18 theoretical stages and the other, five. It is required to investigate alternative configurations for the process. 

In the present study, silicon and transition metal substituted aluminophosphate molecular sieves have also been evaluated for activity and selectivity for para-xylene production via Cg aromatic isomerization. In commercial practice, Cg aromatic cuts are obtained from reformate gasoline and from pyrolysis naphtha streams. Both feeds contain a significant fraction of ethylbenzene which is difficult to separate from xylenes by physical techniques,... 

Figure 11.1 gives typical boiling curves for a light naphtha stream. The curve on the left is a TBP curve and that on the right is an ASTM D-86 curve. The abscissa is volume percent distilled. The ordinate is temperature. Note that the initial and final parts of the curves are quite different because of the fractionation that occurs in the TBP distillation. The 50% boiling point is almost the same (249 and 243 °F). Table 11.1 compares the results of these two methods. 

The distillate rate is set at 20,000 B/D. This will be adjusted later to obtain a desired ASTM 95%pointof 375 °F for the liquid distillate product, which is a fight naphtha stream. Note that there is only one degree of freedom in this rectifying column since there is no reboiler. All of the vapor coming up the column comes from the partially vaporized furnace effluent. 

The vapor leaving the top of the column is condensed in a water- or air-cooled condenser. The liquid distillate is a heavy naphtha stream, which is used for the production of gasoline. It has ASTM 5% and 95% boiling points of 195 and 375 °F, respectively. In some refineries, it is sent to a reforming unit to produce aromatics (benzene, toluene, and xylenes) and hydrogen. The condensed water is decanted off the reflux drum. Note that this water stream is quite large (17,180 Ib/h) because of all the open stripping steam that is used in the column base and sidestream strippers. 

The 95% boiling point specification on the heavy naphtha stream is 350 F. 

Effect of Changing a 95% Specification. Suppose we change the 95% boiling point specification on the heavy naphtha stream from 375 to 350 °F, with the other degrees of freedom unchanged. The result is a decrease in the heavy naphtha flow rate from 6830 to... 

The next lightest fraction isolated at the refinery consists of the naphtha streams. These generally find their way into gasoline (petrol), either directly or after further treatment within the refinery to remove... 

The naphtha streams are further processed to produce gasoline by low-pressure hydrogenation (50 bar/370 °C). The middle and heavy creosote oils are also... 

Aromatics [benzene, toluene, and xylene (BTX)] are obtained from refinery and petrochemical light naphtha streams. Aromatics are produced in the reforming process and in steam cracking. Extraction or various extractive distillation processes are used to isolate and separate aromatics from the naphtha streams. Typical extraction processes are based on tetraethylene glycol, sulfolane, N,N -methylpyrolidene, or morpholine. They produce a mixture of aromatics that are subsequently separated by distillation, extractive distillation, or—in the case of xylene isomers—differential adsorption or fractional crystallization. 

A de-ethanizer tower has 10 trays, we will assume the trays have 50 percent efficiency in this case, hence, there will be five theoretical stages. Ninety percent of the Ethane is being stripped out of the Naphtha stream, thus 10 percent of the Ethane fed to the tower in the Naphtha stream is left in the bottoms product (Fig. 50.9). 

After we have completed the steam specifications, the column model will run automatically and quickly converge to the solution. We may receive warnings about a potential aqueous phase in the Light Naphtha stream. We will ignore these warnings until we complete building the entire column model. 

Figure 2.77 Composition of light naphtha stream indicating small aqueous phase.

We now vary the specification for the LGO draw and copy the resnlts into an Excel spreadsheet. We vary the draw rate from 85% to 115% of the base draw rate of LGO. Figure 2.90 summarizes the results of the case study. We do not include the results for Kerosene, Light and Heavy Naphtha streams since these streams not affected by the draw rate of LGO. In addition, when the draw rate of LGO increases, the 10% point of the residue increases significantly. This means that the LGO stream get heavier (drawing material from residue) as the draw rate of LGO increases. However, if the refiner wishes lighter material in LGO stream, the steam stripping rate of the cut above LGO, i.e. Kerosone, should be increased. 

Create a side draw for the heavy naphtha stream (T201 HN Draw) and specify its draw rate. 

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