1. The system docosane-diphenylhexane (DPH)-furfural is representative of complex systems encountered in the solvent refining of lubricating oils. Six hundred kg/h of a 40 wt\% mixture of DPH in docosane are to be extracted in a countercurrent system with 600kg/h of a solvent containing 98wt% furfural and 2wt DPH to produce a raffinate of 5wt%DPH. Equilibrium diagram at 80C is given in Figure 1 . Calculate, with a right-triangle diagram, a) The number of theoretical stages required, b) The number of kg/h of DPH in the extract at 80C. EQUILIBRIUM DATA: BINODAL CURVES IN DOCOSANE-DIPHENYLHEXANE-FURFURAL SYSTEM [IND. ENG. CHEM., 35, 711 (1943)] The tie lines in the docosane-diphenylhexane-furfural system are: Figure 1. Equilibrium Data