Input isobutane alkylation

Such reactions can take place predominantly in either the continuous or disperse phase or in both phases or mainly at the interface. Mutual solubilities, distribution coefficients, and the amount of interfadal surface are factors that determine the overall rate of conversion. Stirred tanks with power inputs of 5-10 HP/1000 gal or extraction-type equipment of various kinds are used to enhance mass transfer. Horizontal TFRs usually are impractical unless sufficiently stable emulsions can be formed, but mixing baffles at intervals are helpful if there are strong reasons for using such equipment. Multistage stirred chambers in a single shell are used for example in butene-isobutane alkylation with sulfuric acid catalyst. Other liquid-liquid processes listed in Table 17.1 are numbers 8, 27, 45, 78, and 90. 

The input-output structure of the flowsheet is presented in Figure 9.1. Butene (feed rate FA,0) and isobutane (feed rate FB-0) are the raw materials. The butene feed is impure with quite large amounts of propane (FI 0). The main product is the alkylate C8Hi8, at the rate FP. The selectivity of the process is not 100%, therefore heavy products are formed at the rate FR. The inert fed into the process must also leave the plant, the flow including light byproducts that are formed in secondary reactions. Often, significant quantities of n-butane are mixed with the isobutane fresh feed. For this case, development of the flowsheet and the design of the main units is left as an exercise for the reader. 

Model structure is shown in Figure 5. Process variables, unit constants (such as heat transfer coefficients), and feed streams are described on input or as selected by the optimization routine. Then, heat and material balances are performed using an assumed alkylate yield and isobutane consunq>tion. These results form a set of reaction conditions irtiich are used in correlations to calculate reactor performance. The heat and material balance calculations are repeated if reactor performance differs significantly from that used in the previous calculation. Operating incentives are then conqmted and may be used in the optimization routine to select new values of the optimization variables. 

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See also in sourсe #XX -- [ ]

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