Used oil recycling
Broadly, three technological steps of waste oil recycling process at the petroleum refinery with Plasma Tube Reactor (capacity of one reactor = 40000 t/a) can be identified as follows:
1) Two-stage distillation. Preliminary the waste oil is filtrated and separated from water and mechanical sediments. Evaporation of water and light oil occurs in a first stage and prevaporization of gasoil - in a second stage. Obtained "dry" oil (Te >200°C) is transferred to the Plasma Tube Reactor (PTR).
2) PTR with a length up to 2 km comprises several segments of different diameter. Every segment has its own heating temperature, which depends on the dry oil composition. Impact minimization conditions of oil evaporation in PTR allow to avoid the unfavorable processes like cracking and to increase the oil yield. Accordingly, a small amount of oil is supplied into PTR (approximate volume of reactor is 50 l) and heated up to 420°C under deep vacuum (10 mbar abs.). Whereas the entire mass is accelerated until 1700 km/h. High level of turbulence (Re>10000) and high-speed friction against reactor walls ensure transition of practically complete oil to reactive gas phase or so called condition of kinetic plasma. Evaluation of appropriate hold-up time depends on the waste oil composition as well as requirements for distillate and goes to achieve the optimal fractionation and decontamination. Special additives (for instance, NaOH) are directly injected into PTR and homogenized by using integrated mixer, if needed. Condensation consists of four steps. Initially, disk-bowl centrifuge separates residuum. Base oil of high and low viscosity condensates in the second and third steps correspondingly, while gasoil is selected in fourth step.
3) Presence of industrial oils of low quality in feed requires additional treatment of obtained base oil. Generally, there are three methods of base oil quality improvement: treatment with sulfuric acid/bleaching followed by distillation/rectification (achievement of base oil of group 1+, Sulfur 0,2 %, Viscosity index ~90); selective treatment with solvents (achievement of base oil of group 2, Sulfur 0,03 %, Viscosity index ~95) and hydro-treating (achievement of base oil of group 3, Sulfur 0,03 %, Viscosity index ~130).
Main advantages of PTR are: versatility (suitable for treatment of crude naphta and heavy waste from refineries as well as used oils), durability (absence of general maintenance over 10 years), corrosion free and thermal resistance of walls, compact size (12,5 х 7,5 х 13 м) and high profitability.
Processsteps and Refining Products on A-Quality Used Oil, Possible Processing
| Processstep | 1) Tankstorage | 2) Filtered Inlet | 3) Dehydration | 4) Prevaporation | 5) PTR | 6) Bleaching & fine Filtration | ||
|---|---|---|---|---|---|---|---|---|
| Description Processstep | Mixture of delivered Used Oils from Industrial and Car Shops, Average Quality | Refining Inlet after settled out Water and Filtration | Low Vacuum Dewatering Destillation | Higher Vacuum Gasoil Distillation | Plasma Refining with Base and Condensed Cutting of Qualities "Base Stock" + "Spindle Oil" + "Asphalt" | Hot Vacuum Distillation, Adsorption of Colour and Smell to Clay, Fine Filtration and Pressured Air Degasing | ||
| Products | Wet Oil Mixture with Fuels, Gasoil, Chlorsolvents, Esters, Sludge, Water to settle out | Oil Mixture Filtered | Dry Oil Mixture, Fuels | Dry Hot Oil Mix, Vacuum Gasoil | Base Stock, Spindle Oil, Asphalt | Light Base Stock | ||
| "Waste" | Off Spec Oil, Water delivery | Sludge ~ 0,5%, Waste Water ~2% | Waste Water ~0,8%, Fuels ~0,2%, Chlorated Solvents ~0,01% | Waste Water ~0,1%, Gasoil ~0,5%, Chlorated Solvents 0,01%, Esters 0,2% | Fumes of FlueGas, Water vapor | Used Clay, Water Fumes | ||
| Main Produkt Quality: | Base Stock | Spindle Oil | Asphalt | Light Base Stock | ||||
| Colour | Black | Black | Black | Black | Light Brown (Colour 2) | Yellow (Colour 1) | Black | Yellow (Colour 1) |
| Water Content [%] | 3 | 1 | 0.2 | 0.1 | 0.01 | 0.09 | n.m. | n.m. |
| Viscosity 40°C [mm²/s] | 85 | 85 | 87 | 88 | 61 | 18 | 1300 | 61 |
| Ester [%] | 0.3 | 0.3 | 0.3 | 0.1 | 0.005 | 0.05 | 0.045 | 0.005 |
| Chlorine [%] | 0.02 | 0.02 | 0.01 | n.m. | n.m. | n.m. | n.m. | n.m. |
| Zinc [mg/Kg] | 1500 | 1500 | 1500 | 1500 | 5 | n.m. | 1495 | 5 |
References
| Company name | Country |
|---|---|
| BASF Turnkey coating plant |  China |
| DuPont Turnkey paint plant |  Germany |
| Tesa Turnkey synthetic resin process plant |  Sweden |
| Hüttenes Albertus Turnkey synthetic resin process plant | Germany |
| Fuchs Turnkey lube oil blending plant |  Russian Federation |
| Fuchs Turnkey lube oil blending plant |  Brazil |
| Fuchs Turnkey grease plant | Germany |
| DÖL Turnkey lube oil blending plant | Germany |
| BP Turnkey lube oil blending plant | Germany |
| Akzo Nobel Turnkey paint plant | Germany |
| DSM Turnkey synthetic resin process plant | Germany |