Catalytic Cracking Process in Petroleum Refining

Generally, only 10-40% of light oil such as gasoline, kerosene and diesel oil can be obtained from crude oil after atmospheric and vacuum distillation, and the rest are heavy distillate oil and residual oil. If more light oil products are to be obtained, secondary processing of heavy distillates and residual oils is necessary. Catalytic cracking is the most commonly used production process for gasoline and diesel, and gasoline and diesel are mainly produced through this process. This is also the most important production link for general petroleum refining and chemical enterprises.

1. Raw materials:

Residual oil and wax oil are about 70%. Catalytic cracking generally uses vacuum distillate oil and coking wax oil as raw materials. However, with the increasing crude oil and the increasing demand for light oil, most petrochemical enterprises have begun to Add vacuum residual oil to the raw material, or even directly use atmospheric residual oil as raw material for refining.

2. Products:

Gasoline, diesel oil, oil slurry (heavy distillate oil), liquid propylene, and liquefied gas; each accounted for 42% of gasoline, 21.5% of diesel, 5.8% of propylene, 8% of liquefied gas, and 12% of oil slurry.

3. Basic concepts:

Catalytic cracking is the main process of processing heavy oil (such as residual oil) into light oil (gasoline, kerosene, diesel) in the presence of catalyst, and is the main secondary processing method in the refining process. It is a chemical processing process.

4. Production process:

The normal residue and wax oil enter the riser, settler and regenerator through the raw material oil buffer tank to form oil and gas, and enter the fractionation tower.

Part of the oil and gas enters the crude gasoline tower, absorption tower, and air compressor into the condensed oil tank, and passes through the reabsorption tower, stabilization tower, and finally gasoline refining to produce gasoline.

A part of the oil and gas enters the diesel stripping tower through the fractionation tower, and then the diesel oil is refined to produce diesel oil. Part of the oil and gas enters the oil slurry circulation through the fractionation tower, and finally produces the oil slurry.

Part of the oil and gas enters the liquid hydrocarbon buffer tank through the fractionation tower, passes through the desulfurization adsorption tank, the sand filter tower, the water washing tank, the desulfurized alcohol extraction tower, the pre-alkali washing tank, the amine liquid recoverer, the desulfurization extraction tower, and the buffer tower, and finally enters the liquid state. Hydrocarbon tank to form liquefied gas.

Part of the oil and gas passes through the liquid hydrocarbon buffer tank and enters the depropanizer, reflux tower, deethanizer, refined propylene tower, reflux tank, and finally enters the spherical tank in the propylene area to form liquid propylene. The liquid propylene is further processed in the polypropylene workshop to produce polypropylene.