Square cut yields

We can view the overall product yields in Product Yields section. The yields shown in figure 4.75 are square cut yields. Square cut yields refer to the fixed end points for each cut for example, the naphtha cut ranges from C5 to 430 f. 

This is often quite different from the plant cut The end point of the plant naphtha cut is generally lower, therefore the square cut yield is often much higher than the plant yield. 

Since the square cut yields not directly reflect plant yields, model results for each property may not exactly match plant values. We need rigorous fractionation to compare model results with plant measurements. In addition, we will likely improve the agreement of product properties when we calibrate the model in the next workshop. 

After adding all the independent variables (Figure 4.113), we must add the dependent variables. The dependent variables in the case of refinery planning almost always refer to the yields of key products from the FCC unit. In this workshop, we use the square cut yields of the products (see Figure 4.18). However, if we wish to use plant cut yields, we can use a simple component splitter to remap the product effluent from the FCC unit plant cuts based on a TBP cut points. 

The Variable Navigator allows us to add variables and parameters from a given unit operation for observation during the case study. In this case study, we want to study the effects of feed rate and riser outlet temperature (ROT) on the overall conversion and yield distribution of products from the FCC. Since, we are only focused on the yield, we use the square cuts from the model directly. It is possible to perform the same case study on the basis of plant cuts. In that case, we would add a simple component splitter to separate the reactor effluent on the basis of initial and end points of the cuts. However, for this example, we will use square cuts exclusively. 

Table 6.4 lists the 31 optional objective functions, and Table 6.5 shows the 48 reaction activity factors for selection. Aspen H YSYS Petroleum Refining combines the input plant product distribution to construct the reactor effluent and partition the reactor effluent into Cl, C2, C3, C4, C5, and four square cuts , namely, naphtha (C6 to 430 °F cut), diesel (430-700 °F cut), bottom (700-1000 °F) cut and residue (1000 °F-i- cut) which are shown in Table 6.4. AU of the objective functions listed in Table 6.4 are either the prediction errors of crucial operations or important product yields for the HCR process. Aspen HYSYS Petroleum Refining allows us to select the desired objective functions during calibration. After selecting the objective functions, we choose appropriate activity factors to calibrate the reactor model. Figure 6.12 illustrates the relationships among the activity factor, catalyst bed, and reactor type, and Table 6.5 shows the major effect of each activity factor on the model performance, such as global activity (Rgiobai) on the bed temperature profile to help the selection of activity factors.

Step 18 Even reactor temperature profile from model satisfactorily agrees with plant measurement, model s prediction on product yields still significantly deviates from real operation. By observing the comparison between model results and plant measurement, the model has significant predicting deviations on diesel and bottom yields. Besides, real production does not include any fraction within the boiling range over 1000 °F (square cut resid oU). 

The process data are summarized in Table XI. The operation was conducted at a pressure of 250 pounds per square inch and a temperature of 934° F. The depentanized liquid product was fractionated into three cuts called preaviation, aviation, and postaviation blending agents. The yields of these three products were 22.8, 33.5, and 12.6 volume %, respectively. The aviation blending agent had an F-3 blending octane number (1-C) of 100 and an F-4 blending index number (3-C) of 216. The clear research oc-... 

Sperm Oil.—This oil is obtained from the white whale—physeter maerocephahs. This, termed also the cachalot and sperm whale, is remarkable for the enormous size of ita head, which is square, and apparently cut off in front. The animal is pursued chiefly for this oil, but it yields also ambergris. The oil is met with in several parts of the body, but the head is the principal receptacle of. it. Here it is fonnd in a large excavation of the upper jaw, anterior to, and quite distinct from the true cranium whioh contains the brain. Like tho fat of othor animals, this oil is contained in colls, or cellular membrane but besides these cells,... 

Fig. 5 The application of a noncovalently functionalized dendrimer (1) in a CFMR in the allylic animation of crotyl acetate and piperidine in dichloromethane (Koch MPF-60 NF membrane, molecular weight cut-off = 400 Da). The crossed square represents the yield expected on the basis of the retention factor of the system and the deviation is explained by catalyst decomposition...

Groundwood and high-yield pulps containing a significant amount of resins are extracted with ethanol-benzene a sample equivalent to 10 g of oven-dry pulp is cut into pieces approximately 10 mm square and placed in a coarse porosity alundum or fritted glass extraction thimble and extracted with ethanol-benzene in a Soxhlet apparatus for 4-5 h (minimum of 24 siphoning cycles). The pulp is filtered on a Buchner funnel and washed with ethanol and hot water. The moisture content of an air-dried sample is determined as described above. 

If one cuts the macrocycle of porphyrins by oxidation, helical structures become dominant. The most spectacular case has been found with zinc octaethylformyl-biliverdinate. At neutral pH, the central zinc ion is hydrated and a helix is formed with a disturbed square planar ligand field and one axial water molecule. Upon acidification, however, the water molecule is removed and the zinc ion enforces a tetrahedral ligand field by binding to two different formyl-biliverdinate molecules, rearranging to form a double-helix. Upon neutralization, hydration takes place again and the planar, monomeric monohydrate is reformed in quantitative yield. Both the helical monomer and dimer structures have been solved by single crystal analysis (Fig. 6.2.16). 

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