In Figure PI. 3 the distillation configuration for the separation of benzene from tuluene is given. The feed to the distillation comes from the reactor, where toluene has been hydrodealkylated to produce benzene: toluene+H2benzene+CH4 after the excess H2 and the produced CH4 have been removed in a flash unit. For the distillation system: (a) Identify all the control objectives (make sure that you have included all the operational objectives). (b) Identify all external disturbances. (c) All the available measurements and manipulated variables