Abstract: There are two main problems in hydrocracking unit with a processing capacity of 3.16 Mt/aina petroleum refinery: the surplus heat of the main fractionating column is only used by 19.2%, resulting huge cooling duty; debutanizer consumes 16.5 t/h of 2.2 MPa steam as its reboiler heat. With the help of total process simulation to the main fractionating column and absorption-stabilization system, a deep heat integration is suggested, where a new pumparound with No.9 withdrawing and No.8 returning is established, its heat is sent to deethanizer as reboiler heat; the original pumaround heat is transferred to the debutanizer replacing the 2.2 MPa steam. At the same time, the top pressure of the main fractionating column is increased to 0.25 MPa from 0.2MPa and the top pressure of the debutanizer is dropped to 0.60 MPa from 0.90 MPa. The simulation result shows that the integrated case achieves a benefit of 2.9731×107Yuan/a and a drop by 238.5 MJ/t for the comprehensive energy consumption.

Key words: hydrocracking, fractionating column, absorption-stabilization system, thermal integration