A configuration of an intermediate heat-integrated sequence of distillation columns (IHISDC)is proposed in this paper.The IHISDC configuration is analyzed by applying it in a direct sequence of distillation columns for ternary mixture separation.In this configuration

heat is transferred from the rectifying section of the high pressure column to the stripping section of the low pressure column through intermediate heat exchangers.Comparing to the conventional heat integrated sequence of distillation columns

the proposed IHISDC system presents smaller pressure difference between the two heat-integrated columns in the sequence

and consequently saves the energy cost for the reboiler of the high pressure column or for the condenser of the low pressure column.It is also found that the heat duties of the reboiler of the high pressure column and the condenser of the low pressure column are higher

and that the investment cost increases with the increase of the number of heat exchangers.The IHISDC needs to be optimized in order to lower its total annual cost(TAC).