Actual

FOR NO PREVIOUS PHI VALUES AVAILABLE (KO = 0) MAKE FIRST ESTIMATES OF ACTUAL VAPOR COMPOSITION... 

START ITERATIVE CALCULATION OF ACTUAL VAPCR COMPOSITION, ZKI)... 

CALCULATE VAPOR PHASE FUGACITY COEFFICIENTS FOR ACTUAL COMPOSITION OF... 

Reactor diluents and solvents. As pointed out in Sec. 2.5, an inert diluent such as steam is sometimes needed in the reactor to lower the partial pressure of reactants in the vapor phase. Diluents are normally recycled. An example is shown in Fig. 4.5. The actual configuration used depends on the order of volatilities. 

Whether an extraneous component, product, or feed is used as a heat carrier, the actual configuration, as before, depends on the order of the volatilities (again assuming distillation as the means of separation). 

Given the estimate of the reactor effluent in Example 4.2 for fraction of methane in the purge of 0.4, calculate the.actual separation in the phase split assuming a temperature in the phase separator of 40°C. Phase equilibrium for this mixture can be represented by the Soave-Redlich-Kwong equation of state. Many computer programs are available commercially to carry out such calculations. 

Repeat the calculation from Example 4.2 with actual phase equilibrium data in the phase split instead of assuming a sharp split. 

Having computed actual vapor load can be calculated... 

Example 5.3 Using Eq. (5.8), determine the best sequence for the mixture of alkanes in Table 5.2. Assume the ratio of actual to minimum reflux to be 1.1. 

The overlap in the shifted curves as shown in Fig. 6.15a means that heat transfer is infeasible. At some point this overlap is a maximum. This maximum overlap is added as a hot utility to correct the overlap. The shifted curves now touch at the pinch, as shown in Fig. 6.156. Since the shifted curves just touch, the actual curves are separated by AT ,in at this point (see Fig. 6.156). 

First, determine the shifted temperature intervals T from actual supply and target temperatures. Hot streams are shifted down in temperature by and cold streams up by AT J2, as detailed... 

More than 7.5 MW could be added from a hot utility to the first interval, but the objective is to find the minimum hot and cold utility. Thus from Fig. 6.186, QHmin = 7.5MW and Qcmm = 10MW. This corresponds with the values obtained from the composite curves in Fig. 6.5a. One further important piece of information can be deduced from the cascade in Fig. 6.186. The point where the heat flow goes to zero at T = 145°C corresponds to the pinch. Thus the actual hot and cold stream pinch temperatures are 150 and 140°C. Again, this agrees with the result from the composite curves in Fig. 6.5a. 

The grand composite curve is obtained by plotting the problem table cascade. A typical grand composite curve is shown in Fig. 6.24. It shows the heat flow through the process against temperature. It should be noted that the temperature plotted here is shifted temperature T and not actual temperature. Hot streams are represented ATn,in/2 colder and cold streams AT iJ2 hotter than they are in practice. Thus an allowance for ATj in is built into the construction. 

Figure 6.30 shows the grand composite curve plotted from the problem table cascade in Fig. 6.186. The starting point for the flue gas is an actual temperature of 1800 C, which corresponds to a shifl ed temperature of (1800 — 25) = mS C on the grand composite curve. The flue gas profile is not restricted above the pinch and can be cooled to pinch temperature corresponding to a shifted temperature of 145 C before venting to the atmosphere. The actual stack temperature is thus 145 + 25= 170°C. This is just above the acid dew point of 160 C. Now calculate the fuel consumption ...

The turbine isentropic efficiency tjt measures the ratio of the actual to ideal work obtained ... 

The ratio of ideal to actual shaftwork is usually around 0.6. Thus... 

Providing film coefficients vary by less than one order of magnitude, then Eq. (7.6) has been found to predict network area to within 10 percent of the actual minimum. ... 

Calculate factors for those streams which require a specification different from that of the reference using Eq. (7.23) or Eq. (7.24). If Eq. (7.23) is to be used, then the actual network area Anetwork must first be calculated using either Eq. (7.6) or Eq. (7.19) and (VuNiTs or - SHELLS, whichever is appropriate. 

The problem of explosion of a vapor cloud is not only that it is potentially very destructive but also that it may occur some distance from the point of vapor release and may thus threaten a considerable area. If the explosion occurs in an unconfined vapor cloud, the energy in the blast wave is generally only a small fraction of the energy theoretically available from the combustion of all the material that constitutes the cloud. The ratio of the actual energy released to that theoretically available from the heat of combustion is referred to as the explosion efficiency. Explosion efficiencies are typically in the range of 1 to 10 percent. A value of 3 percent is often assumed. 

Distillation capital costs. The classic optimization in distillation is to tradeoff capital cost of the column against energy cost for the distillation, as shown in Fig. 3.7. This wpuld be carried out with distillation columns operating on utilities and not integrated with the rest of the process. Typically, the optimal ratio of actual to minimum reflux ratio lies in the range 1.05 to 1.1. Practical considerations often prevent a ratio of less than 1.1 being used, as discussed in Chap. 3. 

Figure 15.1a shows a single-stage evaporator represented on both actual and shifted temperature scales. Note that in shifted temperature scale, the evaporation and condensjftion duties are shown at different temperatures even though they are at the same actual temperature. Figure 15.16 shows a similar plot for a three-stage evaporator. 

Furthermore, actual designs will normally observe the pinch division. Hence A shells should be evaluated and taken as the next largest integer for each side of the pinch. The number-of-shells target is then... 

Heat exchanger cost data can usually be manipulated such that fixed costs, represented by the coefficient a in Eqs. (F.2) to (F.4), do not vary with exchanger specification. Equations (F.3) and (F.4) can now be rearranged to give the modified exchanger area A as a function of actual area A and the cost law coefficients ... 

A stream-specific cost-weighting factor 4)j to apply to the h value of a special stream j can now he defined. This is the ratio of weighted to actual stream h values ... 

P interval temperature hot streams are represented ATn,in/2 colder and cold streams AT , /2 hotter than actual tem-... 

British thermal unit (Btu) The most commonly used industrial heal unit the amount of heat required to raise 1 lb of water through UF under specified conditions. Since the specific heat of water varies, particularly with temperature, the actual value of Btu is dependent on the conditions chosen as stan-... 

Folic acid and its derivatives (mostly the tri-and heptaglutamyl peptides) are widespread in nature. It is a specific growth ctor for certain micro-organisms, but in animals the intestinal bacteria provide the small quantities needed for growth. The coenzyme forms are actually... 

---