Mixed feed

Many other mixed-feed arrangements are possible which combine the individual advantages of each type of arrangement. Figure 3.13 shows a three-stage evaporator in temperature-enthalpy terms, assuming that inlet and outlet solutions are at saturated conditions... 

Another thermally efficient kiln is the modem mixed-feed vertical kiln ia which coke is admixed with 8.5—20 cm lump limestone and charged into the top of the vertical kiln by a mobile, overhead charging system. However, use of this kiln is waning since the quaUty of mixed-feed kiln lime does not equal that of the other three kilns described above, owing to ash contamination from the coke and poorer reactivity and to the higher cost of coke in most areas. 

Dicyclohexylarnine may be selectively generated by reductive alkylation of cyclohexylamine by cyclohexanone (15). Stated batch reaction conditions are specifically 0.05—2.0% Pd or Pt catalyst, which is reusable, pressures of 400—700 kPa (55—100 psi), and temperatures of 75—100°C to give complete reduction in 4 h. Continuous vapor-phase amination selective to dicyclohexylarnine is claimed for cyclohexanone (16) or mixed cyclohexanone plus cyclohexanol (17) feeds. Conditions are 5—15 s contact time of <1 1 ammonia ketone, - 3 1 hydrogen ketone at 260°C over nickel on kieselguhr. With mixed feed the preferred conditions over a mixed copper chromite plus nickel catalyst are 18-s contact time at 250 °C with ammonia alkyl = 0.6 1 and hydrogen alkyl = 1 1. 

Trickle bed reaction of diol (12) using amine solvents (41) has been found effective for producing PDCHA, and heavy hydrocarbon codistiUation may be used to enhance diamine purification from contaminant monoamines (42). Continuous flow amination of the cycloaUphatic diol in a Hquid ammonia mixed feed gives >90% yields of cycloaUphatic diamine over reduced Co /Ni/Cu catalyst on phosphoric acid-treated alumina at 220°C with to yield a system pressure of 30 MPa (4350 psi) (43). 

Reactor Internals and Unit Hardware. Requirements for mixing feed components or separating products may determine minimum pilot unit size. If reactants caimot be premixed before they are passed into the reactor, the effectiveness of the inlet distributor in mixing the reactants can markedly affect reactor performance. This is especially tme for gases, multiple phases, or Hquid streams of greatly different kinematic viscosities. 

A cocurrent evaporator train with its controls is illustrated in Fig. 8-54. The control system applies equally well to countercurrent or mixed-feed evaporators, the princip difference being the tuning of the dynamic compensator/(t), which must be done in the field to minimize the short-term effects of changes in feed flow on product quality. Solid concentration in the product is usually measured as density feedback trim is applied by the AC adjusting slope m of the density function, which is the only term related to x. This recahbrates the system whenever x must move to a new set point. 

Mixed-feed operation is used only for special applications, as when liquor at an intermediate concentration and a certain temperature is desired for additional processing. 

Ammonolysis of phenol occurs in the vapor phase. In the Scientific Design Co. process (Figure 10-10), a mixed feed of ammonia and phenol is heated and passed over a heterogeneous catalyst in a fixed-bed sys-... 

Operability. All four series of experiments prove that HGR metha-nation is a usable and operable system. With a total gas recycle ratio of about 10 1 and with CO concentrations in the mixed feed entering the catalyst bed as high as 4.3% (wet basis), temperature control was excellent and no hot spots developed. It appears likely that lower recycle... 

Stream Time, hrs CGR Ratio Mixed Feed, % Product Gas Analysis,a %... 

Component Moles Output per mole of mixed feed... 

The data in Example 1.2 are in moles of the given component per mole of mixed feed. These are obviously calculated values. Check their consistency by using them to calculate the feed composition given that the feed contained only para-xylene and chlorine. Is your result consistent with the stated molar composition of 40% xylene and 60% chlorine ... 

Lovell RA, McChesney DG, Price WD. 1996. Organohalogen and organophosphoms pesticides in mixed feed rations Findings from FDA s domestic surveillance during fiscal years 1989-1994. J Assoc Off Anal Chem 79 544-548. 

An analogous situation occurs in the catalytic cracking of mixed feed gas oils, where certain components of the feed are more difficult to crack (less reactive or more refractory) than the others. The heterogeneity in reactivities (in the form of Equations 3 and 5) makes kinetic modelling difficult. However, Kemp and Wojclechowskl (11) describe a technique which lumps the rate constants and concentrations into overall quantities and then, because of the effects of heterogeneity, account for the changes of these quantities with time, or extent of reaction. First a fractional activity is defined as... 

Cf, Cm, and c ui are reactant concentrations in the feed, and at the inlet and outlet of the catalyst bed, respectively and Vr is the reactor volume. The mass balance equation for mixing feed with recycle is as follows ... 

The MRLs are derived from data from supervised residue trials that are generally carried out in the context of food production. Specific conditions of feed production are not considered. Therefore, many practical problems for the official control of feed must be solved in future, e.g., application of transfer factors and the calculation of MRLs for mixed feed. 

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