Method and device for lightening heavy oil by utilizing a suspension-bed hydrogenation process

A method for lightening heavy oil by utilizing a suspension-bed hydrogenation process, comprising the following steps:

• mixing a part of a raw oil with a suspension-bed hydrocracking catalyst to form a first mixture, carrying out first shear and second shear in sequence on the first mixture to obtain a catalyst slurry;
• mixing the catalyst slurry with remaining raw oil and hydrogen to form a second mixture and feeding the second mixture into a suspension-bed hydrogenation reactor for undergoing hydrocracking reaction at a pressure of 18-22.5 MPa, a temperature of 390-460° C. and a volume ratio of hydrogen to oil being 800-1500 to obtain a hydrocracked product;
• and
• subjecting the hydrocracked product obtained in the mixing step to a hot high pressure separation to obtain a gas stream and an oil stream;
• subjecting the gas stream obtained from the hot high pressure separation to a cold high pressure separation and a cold low pressure separation in sequence to obtain an oil stream,
• subjecting the oil stream obtained from the hot high pressure separation to a hot low pressure separation to obtain a gas stream and an oil stream, subjecting the gas stream obtained from the hot low pressure separation and the oil stream obtained from the cold low pressure separation to stripping separation to obtain dry gas, naphtha and bottom oil;
• and
• subjecting the oil stream obtained from the hot low pressure separation to vacuum distillation to obtain a first sidestream oil at a first sidestream line and a second sidestream oil at a second sidestream line, and
• feeding the first sidestream oil, the second sidestream oil and the bottom oil into a fixed-bed hydrogenation reactor for undergoing hydrotreatment again to obtain a hydrogenated product which is then subjected to separation to obtain a light oil of less than 350° C.,
• wherein, the suspension-bed hydrocracking catalyst comprises a composite support and an active metal oxide loaded on the composite support,
• wherein the composite support consists of a semi-coke pore-enlarging material, a molecular sieve and a spent catalytic cracking catalyst at a mass ratio of (1-5):(2-4):(0.5-5), and the suspension-bed hydrocracking catalyst accounts for 0.1-10 wt. % of the catalyst slurry.