Feed injection

Resolution The chromatographic separation of two components, A and B, under trace conditions with small feed injections can be characterized in terms of the resolution, R,. For nearly Gaussian peaks ... 

The preceding eqiiations are accurate to within about 10 percent for feed injections that do not exceed 40 percent of the final peak width. For large, rec tangiilar feed injections, the baseline width of the response peak is approximated by ... 

For strongly retained components (Ic 1), the number of plates required to obtain a given resolution with a finite feed injection is approximated by ... 

For a small feed injection, the modulator concentration [Pg.1536]

TABLE 16-14 Expressions for Predictions of Chromatographic Peak Properties in Linear Gradient Elution Chromatography under Trace Conditions with a Small Feed Injection and Inlet Gradient Described by op = opo + pt (Adapted from Refs. A and B). 

When only a few solutes are separated, they may occupy only a small portion of the total column volume at any given instant. In such cases, the productivity is improved by cyclic feed injections, timed so that the most strongly retained component from an injection elutes just before the least strongly retained component from the following injection (see Fig. 16-57). For a mixture of two components with k > 1, when the same resolution is maintained between bands of the same injections and bands of successive injections, the cycle time tc and the plate number requirement are ... 

In drying solutions or slurries of solutions, the location of the feed-injection nozzle (spray nozzle) has a great effecl on the size of particle formed in the bed. Also of importance are the operating temperature, relative humidity of the off gas, and gas velocity. Particle growth can occur as agglomeration or as an onion sldnuing. ... 

Most investigators have focused their attention on a differential segment of the zone between the feed injection and the crystal melter. Analysis of crystal formation and growth in the recoveiy section has received scant attention. Table 22-4 summarizes the scope of the literature treatment for center-fed columns for both solid-solution and eutectic forming systems. 

Feed injection. An improved feed injection system provides optimum atomization and distribution of the feed for rapid mixing and complete vaporization. The benefits of improved feed injection aie reduced coke deposition, reduced dry gas yield, and improved gasoline yield. 

Feed segregation. Split feed injection involves charging a portion of the same feed to a different point in the riser. This is another tool for increasing light olefins and boosting gasoline octane. 

This requires pre-accelerating the catalyst to the feed zone. Steam or fuel gas is often used to lift the catalyst to the feed injection. Figure 7-1 shows the design criteria of using steam as a lift media to deliver a dense supply of catalyst to the feed nozzles. 

Larger Zeolite Unit Cell Size AddZSM-5 Additive Higher Cat/Oil ratio Higher Mix Zone temperature Split Feed injection Riser Quench... 

Figure 1-5 shows a typical feed preheat configuration. A hydraulic limitation usually manifests itself when increasing fresh feed rate and/ or installing high efficiency feed injection nozzles. 

Important features of a feed injection system include ... 

The choice of the feed injection system should be based on the vendor s experience in similar units with similar feeds and on his yield projection and/or performance guarantee. However, it may be difficult to substantiate the guarantee when other changes are being made in the unit. 

This chapter provided several cost recommendations that, once implemented, would provide cost-effective added value to the operation of the FCC. Examples of such items include tips on debottlenecking the air blower, wet gas compressor, and catalyst circulation. This chapter also discussed the latest technologies regarding the riser termination devices, as well as feed injection systems. Prior to implementing any new technologies, it is critical that the objectives and the limitations of the unit are clearly defined to ensure the expected benefits of the new technology are realized. 

The proper choice of a feed injection system, regenerator, and catalyst are some of the key aspects of successful RFCC operation. 

An efficient feed injection system produces extremely small droplets that vaporize quickly. Rapid vaporization minimizes the amount of non-vaporized hydrocarbons that block the active sites. An effective feed nozzle system must instantaneously vaporize and crack asphaltenes and polynuclear aromatics to lower boiling entities. 

The use of RFCC will continue to grow, particularly in regions of the world where atmospheric or vacuum residue contains low levels of contaminants. Careful regenerator and feed injection designs are important in ensuring a successful operation. 

Cat/Oil Ratio is the weight ratio of regenerated catalyst to the fresh feed in the riser feed injection zone. 

An issue with chelants, and especially EDTA as the most widely used chelant, is the risk of corrosion to the feed equipment, feed injection points, and ultraclean boiler surfaces. This issue is generally associated with a lack of oxygen control in some way or other. 

Blood and lymph are approximately isotonic to a cell so that cells do not gain or lose liquid when bathed in these fluids. Pure water is hypotonic and may cause cells to swell and burst. During intravenous feeding, injections, and storage of cell tissue, a salt (saline) solution is used with a concentration of solutes that is essentially isotonic with blood (and hence, with the cell) to prevent cell damage. 

LDPE tabular reactor is divided into several reaction zon acoirding to fhe feed injection points. Here we apply mixing cell model for tobidar rcsictor which considea s the reactor axis as series of cells which is conceptually the same as CSTRs in series. In tiiis study 40 cells are used for each reactor spool of 10 m long. The mass balant equation of a single cell at steady state can be written as follows. 

Consider the example in Fig. 26 of determining if there is a problem with the feed injection system of a fluidized catalytic cracking unit (Ramesh et al., 1992). In this example, there is a set of rules that relate combinations of process observations to establish or reject this possibility. 

The label of interest is Feed Injection System Problem. The if, and, and or statements relate specific process observations that can establish that there is a likelihood of an injection system problem. Injector header pressure is a process measurement and abnormal is an intermediate label of interest. The label abnormal can be determined by developing a numeric-symbolic interpreter that maps injector header pressure data as either normal or abnormal. 

Nonisothermal reactors with adiabatic beds. Optimization of the temperature profile described above assumes that heat can be added or removed wherever required and at whatever rate required so that the optimal temperature profile can be achieved. A superstructure can be set up to examine design options involving adiabatic reaction sections. Figure 7.12 shows a superstructure for a reactor with adiabatic sections912 that allows heat to be transferred indirectly or directly through intermediate feed injection. 

The same equations can also be used as a good approximation for other rate mechanisms with N calculated according to Table 16-13. When tc is large, Eq. (16-185) describes a single feed injection and approaches the results of Eqs. (16-173) and (16-148) for small and large values of (J), respectively. See Seader and Henley (gen. refs.), and Carta, op. cit., for sample calculations. 

---