Effects of Reactor Scale-up On Controllability

One of the classical problems in scaling-up a jacketed reactor is the decrease in the ratio of heat-transfer area to reactor volume as size is increased. This has a profound effect on the controllability of the system. Table 11.1 gives some results that quantify the effects for reactors varying from 5 gallons (typical pilot-plant size) to 5CKX) gallons. Table 11.2 gives parameter values that are held constant as the reactor is scaled up. 

Notice that the temperature difference between the cooling jacket and the reactor must be increased as the size of the reactor increases. The flow rate of cooling water also increases rapidly as reactor size increases. 

The ratio of to, which is a measure of the controllability of the system, decreases from 124 for a 5-gallon reactor to 33 for a 5000-gallon reactor. 

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