The raw material of Catalytic cracking process
Catalytic cracking raw materials Catalytic cracking raw materials come from a wide range of sources, 350~500℃ straight distillate, atmospheric residual oil and reduced pressure residual oil into the secondary processing fraction can be used as catalytic cracking raw materials.
1. Straight distillate
Straight-run fractions mainly refer to atmospheric pressure heavy fractions and reduced pressure fractions. The properties of straight-run fractions differ depending on the nature of the crude oil.
However, in comparison, straight-run fractions contain more alkanes and fewer aromatics and are easier to crack.
The straight-run distillate obtained from the distillation of our crude oil is used as the catalytic feedstock, which has the following characteristics:
1) Adequate catalytic cracking raw materials, China's crude oil has few light components, mostly below 30%.
2) The raw material contains low sulphur and few heavy metals, only the isolated crude oil distillate has high sulphur and heavy metal content.
3) The catalytic cracking raw materials of major crude oils (Daqing, Renqiu, etc.), with high wax content and high K-value, generally 12.3~12.6. China's catalytic cracking raw materials are large in quantity and quality, and the light oil yield and total conversion rate are also high, which is the ideal catalytic cracking raw material.
2. Normal pressure residual oil and reduced pressure residual oil
In China's crude oil processing process, the amount of residual oil is large, and the yield of reduced-pressure residual oil accounts for about 40% of crude oil, while atmospheric residual oil accounts for 65%~75%. The heavy oil catalytic cracking process can increase the depth of crude oil processing, usually by blending reduced-pressure residual oil in different proportions on top of conventional catalytic cracking feedstock, or by directly using full-distillation atmospheric residual oil. As a result, the family composition changes with the increase of gum, asphaltene, heavy metals and residual carbon values in the heavy oil catalytic cracking feedstock. The impact of high residual carbon values and high heavy metal content on the catalytic cracking process has to be addressed if oil resources are to be used efficiently.
3. Secondary processing distillates
①Wax paste and wax down oil from ketone benzene dewaxing are ideal catalytic cracking raw materials, containing more alkanes, easy to crack and less raw coke.
②Coking wax oil, viscosity reduction cracking distillate can be used as catalytic cracking raw materials, because it has been cracked, generally can not be used alone, more aromatic content, poor cracking performance, higher coke yield.
(3) Deasphalted oil and residual oil can be blended with straight distillate distillate as a... They can be used as catalytic cracking feedstock. Because it contains more aromatic hydrocarbons, easy to condense and difficult to crack, the conversion rate is low and the amount of raw coke is high.
