Definition of Mild Hdrocraking
The term “mild hydrocracking” implies hydrocracking at mild operating conditions. Mild Hydrocracking is the refining process designed to performs partial hydrocracking only.
It is carried out mostly for producing middle distillates and fuel oils from vacuum distillates, catalytic dewaxing for lube base stock at a pressure below 10 MPa (100 bar) and at a temperature range varying from 350°C to 450°C. Since pressure is low compared to hydrocracking reactors, mild hydrocracking can be carried out in traditional hydrotreating reactors. Conversion of vacuum distillates may not exceed 50%.
Further, a one-stage reactor without recycle is used in mild hydrocracking. The major characteristics
of this process is the production of a high yield of middle distillate and fuel oil and a savings of hydrogen, since the process is operated at almost half of the hydrogen pressure used in conventional hydrocracking.
The other type of hydrocracking is conventional Hydrocracking; which involves higher operating conditions, two or more reactors, two stages, and recycling of un-converted heavies for more than 90 % conversion.
A comparison of mild and conventional hydrocracking, operating parameters is given in the attached file.