Reduce the alkaline nitrogen of coked wax oil from more than 1000ppm to 300~600ppm, simultaneously demetallize and remove residual carbon, reduce the demetallization load of hydrogenation raw materials, significantly improve the quality of catalytic cracking (FCC) and hydrocracking feeds, and increase the yield of light oil
Coker wax oil (CGO) is a secondary processed middle distillate obtained during the coking process of vacuum residue. The yield accounts for about 1% of the coked product.20%~30%, mainly used as raw material for catalytic cracking (FCC) and hydrocracking. Compared with straight-run wax oil, deeply cracked coked wax oil contains more nitrogen, condensed ring aromatic hydrocarbons and colloids.The content of alkaline nitrogen compounds is 2~3 times that of straight-run wax oil, usually up to more than 1000ppm.
During the catalytic cracking process, these basic nitrogen compounds (pyridine, quinoline) will Preferentially adsorbed on the acidic centers of the catalyst, causing the catalyst activity to decrease, and further:
Therefore, reducing the basic nitrogen content through denitrification is an effective method to improve the catalytic cracking performance of coked wax oil, increase the light recovery of the catalytic device, and improve the economic benefits of the refinery. as Coked wax oil pretreatment (refining) The key step is that complex denitrification can not only remove alkali nitrogen but also reduce the metal and carbon residue content of the hydrogenation raw material. It is also suitable for Denitrification of lubricating oil before hydrogenation Wait for the scene.
| Project | Illustrate |
|---|---|
| Coking wax oil yield | Accounting for 20%~30% of coking products |
| Basic nitrogen content | Straight-run wax oil 2~3 times |
| Typical base nitrogen levels | often >1000 ppm |
| For FCC catalyst | Adsorb acidic centers and reduce activity |
| processing target | After removal, the alkali nitrogen is reduced to 300~600 ppm level |
Large refineries at home and abroad generally use high-pressure hydrodenitrification of residual oil, which has high yields but harsh conditions and high investment; non-hydrogenation complex denitrification improves the feed with lower investment. The 100,000 tons/year coking wax oil denitrification device commissioned by a CNPC refinery is the longest-running demonstration device in China that is still in production.
The above are measured data under typical working conditions. The actual effect varies with the properties and dosage of coked wax oil. It is recommended to send samples for small test evaluation.
according to Lewis acid-base theory, the N atoms of basic nitrogen compounds (such as substituted pyridine and quinoline) in oil products contain unshielded lone pairs of electrons and are electron pair donors (Lewis bases); the N atoms in denitrification agents Quaternary phosphonium salt acidic ionic liquid Has proton properties and can provide the lone pair of electrons for H⁺ and basic nitrogen complex salt, thereby "grabbing" alkaline nitrogen from the oil.
Nitrogen-containing complexes formed Insoluble in oil, high density, it can be separated from the denitrified oil through static settling in the tank area. Since basic nitrogen is mostly concentrated in aromatic hydrocarbons and colloids,While the coked wax oil is denitrified, the colloid and metal content are also significantly reduced., to achieve "one dose for multiple removal".
| Project | Technical Indicators | Test Method |
|---|---|---|
| Appearance | homogeneous liquid | Visual inspection |
| Density (20℃) g/cm³ | ≥1.70 | GB/T 1884 |
| Freezing point ℃ | ≤-25 | GB/T 510 |
| Kinematic viscosity (50℃) mm²/s | ≤80 | GB/T 265 |
| Project | Before Denitrification | After Denitrification |
|---|---|---|
| Basic nitrogen μg/g | 2043 | 598 |
| Sulfur μg/g | 9960 | 9135 |
| Gum % | 7.1 | 5.3 |
| H/C atomic ratio | 1.647 | 1.694 |
| Kinematic viscosity (50℃) | 20.48 | 18.98 |
Basic nitrogen is reduced by more than 70%, H/C is increased, sulfur, density, colloid, and viscosity are all reduced, and the catalytic processing performance is significantly improved.
The 95~105℃ coking wax oil from the coking unit is combined with the denitrification agent from the metering pump.static mixer Mix thoroughly and react.
Oil/agent mixture enters Denitrification reaction settling tank, heat preservation and sedimentation separation at 80~100℃ 24~48 hours.
Denitrification refined oil from settling tank Extract the middle and upper layers, sent to the catalytic cracking or hydrocracking unit as feed.
Base nitrogen complex derivatives (asphaltenoids) from Discharge from the bottom of the tank, mixed with asphalt or petroleum coke and delivered externally, no waste water is produced.
| Index | Numerical Value |
|---|---|
| Raw oil feed temperature | 80~100 ℃ |
| Settling tank temperature | 80~100 ℃ |
| Oil residence time | >24 h (24~48h) |
| Nitrogen complex extraction temperature | 105~130 ℃ |
| Denitrification agent filling amount | 1.0%~1.4% (adjusted according to alkali nitrogen) |
| Source of Coked Wax Oil | Raw Material Alkali Nitrogen Μg/G | After Removal of Alkali Nitrogen Μg/G | Dealkalization Nitrogen Rate % | Denitrification Agent Dosage % |
|---|---|---|---|---|
| A CNPC Refinery | 1129 | 397.2 | 63.6 | 1.15 |
| Changyi Petrochemical | 1136 | 429.8 | 64.2 | 1.1 |
| Qingzhou Petrochemical | 1585 | 772.5 | 73.9 | 1.1 |
| Wuhan Petrochemical | 1438 | 450 | 68.7 | 1.4 |
| Daqing Petrochemical | 1322 | 313 | 76.3 | 1.3 |
| Shijiazhuang Refining and Chemicals | 1415 | 268 | 81.1 | 1.4 |
Data source: Summary of Benxin/Runerhua coked wax oil complex denitrification tests. This agent has good denitrification performance for different coked wax oils. When the dosage is 1.0%~1.2%, the denitrification rate is about 70%~80%.
Benxin prepared a construction plan for the coked wax oil complex denitrification project for Dongying Zhenghang, using tank settlement technology to improve the feed quality of its coked wax oil catalytic cracking.
View case →The coked wax oil from Changyi and Qingzhou of Hongrun Group was refined with low acid value denitrification agent. The alkali nitrogen was reduced from 1136/1585μg/g to 429.8/772.5μg/g, and the acid value after removal was 0.15~0.19mgKOH/g.
View case →The coked wax oil denitrification device, which has the longest running time in China and is still in production, is a strong evidence that the non-hydrogenation complex denitrification technology is mature and reliable.
Industry DemonstrationProvide the alkali nitrogen/acid value and other properties of coked wax oil, and our technical team will provide you with targeted denitrification plans, small-scale evaluation and device construction suggestions.