Abstract: In a fractionation system wherein a stream of heat-containing fluid is taken from a zone effecting at least a partial control of at least one operating condition in said zone by withdrawing said fluid at a rate responsive to and correlated with a change in said condition and utilizing the heat in said withdrawn fluid.

Abstract: A process for the separation of a diolefin from a mixture thereof with other hydrocarbons having boiling points close to that of the diolefin, comprising subjecting the mixture of hydrocarbons to reaction conditions which will dimerize the diolefin, separating effluent of the dimerization into a first heavy fraction comprising the diolefin dimer and materials of higher boiling point than the diolefin dimer and a first light fraction comprising hydrocarbons having lower boiling points than the diolefin dimer, separating the first heavy fraction into a second heavy fraction comprising materials having higher boiling points than the diolefin dimer and a second light fraction comprising diolefin dimer, passing at least a portion of the second light fraction along with steam through a cracking zone under conditions sufficient to cause the diolefin dimer to be converted to the starting diolefin monomer, using at least a portion of the second heavy fraction as fuel burned to supply heat to the cracking zone, cooling