Effective utilization of catalytic cracking slurry
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This post was last edited by lijianhuai on 2011-7-1 at 13:47. I saw someone in the forum posting about the utilization of catalytic slurry; during my studies, I focused on the effective use of catalytic cracking slurry and reviewed many documents on the subject. Now I’m sharing here the summary related to the utilization of catalytic cracking slurry from my thesis’ literature review, so that we can discuss it together. In fact, there are only a few ways in which catalytic cracking slurry can be utilized. Any similarities with other documents are normal, but every source cited in this text has been read and summarized by me personally. Catalytic slurry, as the heavy fractions produced at the bottom of catalytic cracking units, is primarily used as fuel. Depending on its application, it is mainly divided into fuel oil for marine diesel engines and fuel oil for furnaces. However, as oil resources become increasingly scarce, using sludge as fuel represents a significant waste. The components in sludge have potential value: it contains 30%–40% saturated hydrocarbons, which make it an excellent raw material for catalytic cracking, while aromatic hydrocarbons account for about 50% of the sludge, and can be processed into high-value products through various methods ； In addition, starting from January 1, 2009, the consumption tax on refined oil in China was significantly increased. The consumption tax on fuel oil rose from 0.1 yuan per liter to 0.8 yuan per liter; using oil sludge as fuel oil required paying a high amount of such tax, thereby increasing the costs for refineries. Therefore, the rational and effective utilization of oil slurry to develop high-value-added products is of great significance. Currently, the utilization of oil slurry mainly focuses on two aspects: one is to integrate the oil slurry with various processes in refineries, in order to improve both the processing procedures and the properties of the products, while also making effective use of the oil slurry. (Mainly asphalt modifiers, modifiers produced by co-treatment with coal for road asphalt, enhancers for solvent deasphalting, activators to enhance distillation, and components used in heat treatment processes, etc.) On the other hand, oil slurry is used to produce various petrochemical products (mainly as softeners and filler oils for rubber, for the production of carbon fiber materials, needle coke, carbon black, heat transfer oils, petroleum aromatic plasticizers, and brighteners for casting, etc.). 1. Production of heavy-duty road asphalt: With the increase in road construction projects in China, high-grade road asphalt enjoys good market prospects, and there is a high demand for such asphalt. However, over 80% of China’s crude oil is paraffin-based, which makes it unsuitable for producing high-grade asphalt. The main reason why high-grade asphalt produced in China is not accepted by users is the high wax content in such asphalt. In high-quality asphalt from abroad, the mass fraction of aromatics is generally 40% to 55%, while the mass fraction of waxes is less than 3.0%. When asphalt has a high pitch content and high hardness, an appropriate amount of aromatics and gums can be added to adjust its four components, thereby improving its elongation and durability in use. The wax content in the oil slurry is generally low, and it contains a large amount of polycyclic aromatic hydrocarbons, making it an excellent raw material for asphalt modification. Therefore, research on using oil slurry, a wax-poor and aromatic-rich component, to produce high-grade road asphalt is currently very active and has yielded fruitful results. This process of producing road asphalt from oil slurry is simple, requires low investment and costs, and is easy to implement; it represents an effective way to address the supply-demand imbalance of road asphalt in our country. 2 is used as a reinforcing agent for solvent deasphalting. The solvent deasphalting process involves utilizing the differences in solubility of various low-molecular-weight hydrocarbons and their mixtures for different types of hydrocarbons, in order to remove the undesirable components from residue oil or other heavy oils. According to the principle of like dissolves like, low-boiling, small-molecule, non-polar hydrocarbons are ideal deasphalting solvents, such as propane and butane. Propane, on the other hand, has certain solvency and good selectivity, and is often used by refineries as a solvent for deasphalting. To increase the yield of deasphalted oil, mixed solvents (such as propane/butane) are often used for extraction. Due to the high density, low flash point, and low viscosity of the oil slurry, adding it to vacuum residue increases the density of the feed in the extraction tower while reducing its viscosity. This increases the density difference between the two phases in the tower, thereby reducing the extraction resistance and facilitating mass transfer between the phases. As a result, the extraction process is improved, and the yield of deasphalted oil can be increased effectively. At the same time, some heavy aromatics and gums remain in the deoiled asphalt, improving its properties and yielding a higher-quality raw material for further processing. Studies have shown that by blending catalytic slurry into residue and using solvent extraction for deasphalting, the yield of deasphalted oil (DAO) increases significantly. The DAO obtained has a low carbon residue and metal content, as well as a high saturated fraction, resulting in improved properties ； The quality of deoiled asphalt (DOA) has also improved significantly; most residue oils can be processed into qualified road asphalt after extraction, and some can even yield high-quality road asphalt. As an activator for enhanced distillation of residue, increasing the distillation yield as much as possible is beneficial for atmospheric and vacuum distillation. Achieving enhanced distillation by adding an activator in order to alter the properties of the distillation system is an effective method for improving the distillation yield. Enhanced distillation activators are additives that consist of active substances added to crude oil or heavy oil, thereby increasing the distillation yield. Currently, there are two types of agents used for enhanced distillation activation: one type consists of aromatic-rich substances, such as catalytic cracking recycle oil or catalytic slurry ； Another category is surfactants. Using oil slurry as an activator to enhance crude oil distillation in order to increase the yield of light oils and the overall recovery rate of fractions is a research topic that has received considerable attention at present. Duan Tianping and others used catalytic slurry and furfural extract oil as enhancers for the vacuum distillation of Yumen residue in a real boiling point distillation apparatus, and studied the extraction efficiency. It was found that the yield of the distilled oil could be increased by up to 2.08%, and the properties of the residual vacuum residue after distillation improved, making it more suitable for use as road asphalt. Although slurry enhances the distillation process, it is merely a simple separation method; the quality of the product is greatly influenced by the properties of the raw materials, its scope of application is limited, and its practicality is low. As a coking feedstock, in addition to being used as a component in fuel oil blends, another major use of oil sludge is to be mixed into residue as a coking feedstock. Due to its high aromatic content and low H/C atom ratio, catalytic slurry yields lower total liquid yields from coking when used as a coking feedstock alone, but results in a higher coke yield. If a small amount of slurry is blended into delayed coking, the total liquid yield of the product decreases, the coke yield increases, and the quality of the wax oil deteriorates. However, the coking wax oil can be properly processed in catalytic cracking units, and overall, using slurry as a coking feedstock is more economically advantageous than using it as fuel oil. According to the formation mechanism of needle coke, the raw materials used for its production must have a high aromatic content, an aromatic index of not less than 120, low levels of impurities and metals. Moreover, they should exhibit a high transition temperature for the mesophase and a wide range of mesophase temperatures during the thermal conversion process, thereby enabling the formation of larger mesophase spheres. The oil slurry contains a high amount of aromatics with short side chains, which meets all the requirements for producing needle coke; it is therefore an excellent raw material for such production. Both industrial practice and laboratory studies show that oil slurry itself yields at least 40% coke in coking reactions, while the yield of gasoline and diesel is only around 20%, which is significantly lower than that of oil slurry. If oil slurry is used as a feedstock in coking units, the highly condensed polar polycyclic aromatic hydrocarbons continue to undergo condensation and polycondensation in the coking towers, ultimately resulting in the formation of coke. Therefore, after incorporating oil slurry into coking units, the yields of gases and coke increase, as does the total yield of diesel and wax oil. 5 is used as a rubber softener and filling oil. A softener is an additive used during the rubber processing to improve the processability of the rubber compound. Adding a softener to the raw rubber not only improves the plasticity of the compound, reduces its viscosity and mixing temperature as well as shortens the mixing time and saves energy consumption during mixing; it also enhances the dispersion and mixing of carbon black with other additives. It acts as a lubricant during calendering and extrusion, reduces the hardness of the vulcanized rubber, and improves its tensile strength, elongation, and cold resistance. Based on the physicochemical properties of softeners, they can be classified into aromatic softeners, naphthenic softeners, and alkanic softeners. Aromatic softeners feature high density, high viscosity, good affinity, and excellent processability, making them suitable softeners for the rubber industry. Oil slurry is indeed an excellent rubber softener rich in aromatics. The Jinzhou refinery uses oil slurry with an aromatic content of over 40%, which, after sedimentation and separation, is used directly as a softener for natural rubber and various synthetic rubbers. References: Zhang Zhaoqian, Li Zheng, Zhu Genquan, et al. Technical progress of catalytic cracking slurry. Chemical Industry Progress, 2007, 26(11): 1559–1563. Li Shujie. Production of binary hydrocarbon-based rubber plasticizers from catalytic cracking slurry. Petroleum Refining and Chemistry, 1994, 25(1): 19–25. Zhang Qingyu. Research on the use of catalytic cracking heavy aromatics as rubber softeners. Petroleum Refining and Chemistry, 1998, 29(3): 24–28. Bi Hongzhang. Recent developments in carbon fiber worldwide. High-Tech Fibers and Applications, 2003, 28(5): 54–56. Wen Shu. Carbon fibers. Friends of Chemical Industry, 1997, 15(2): 25–26. Li Yucai, et al. Industrial production of acicular coke. Fine and Special Chemicals, 2002, (13): 6–8. Na Hongyu. Equipment and methods for carbon black production. Carbon Black Translation Series, 2003, 12(15): 21–25. Xia Chunshan, Wang Yafan. Disposal and utilization of heavy oil catalytic cracking slurry. Journal of Daqing Petroleum Institute, 1999, 16(3): 60–63. Zheng Yanhua, Li Changbai. Deeply processed products from catalytic cracking slurry and their applications. Chemical Technology Market, 2001, 8: 18–20. Jia Shengsheng, Cheng Jian, Luo Zaohua. Influence of adding catalytic cracking slurry on the deasphalting process of residue oil. Oil Refining Design, 1995, 25(4): 8–11. Duan Tianping, Tong Xiulong, et al. Research on enhanced distillation technology for Yumen mixed crude oil. Journal of East China University of Science and Technology, 2003, 29(6): 551–556. Hu Yaoliang. Economic and technical analysis of processing catalytic cracking slurry in delayed coking units. Jinling Science and Technology, 2005, 12(5): 1–9. Kang Weiqing. Utilization of catalytic cracking slurry and related processes. Jiangxi Petroleum and Chemical Industry, 1999, (2): 31–36.
Well, a lot has been written; it’s good. However, I have a question: as for how to treat the catalyst in the slurry in order to meet the requirements of the raw materials for subsequent processing
Several comprehensive utilization methods for catalytic cracking slurry: 1. As a modifier for road asphalt. 80% of China’s crude oil is paraffin-based, making it unsuitable for producing high-grade asphalt. Therefore, research on producing high-grade road asphalt using the wax-poor and aromatic-rich components of refinery FCC slurry as modifiers is very active. By using enhanced distillation – that is, by adding an enhancer to asphalt or residue and then carrying out vacuum distillation to evaporate the saturated components that are detrimental to the quality of asphalt, while leaving the components beneficial to asphalt behind – high-quality asphalt can be produced. At the Jinling Petrochemical Refinery, after the oil slurry is extracted using furfural, the fractions with a boiling point above 490°C are blended with semi-oxidized asphalt and No. 10 construction asphalt to produce No. 100 Type A and B road asphalts as well as No. 60 road asphalt. The essence of using catalytic slurry as a modifier (blending agent) to formulate high-grade road asphalt is to add the components in the slurry that are beneficial to the properties of asphalt to the asphalt itself, thereby achieving a proper composition and improving the quality of the asphalt. The heavy aromatic components in catalytic slurry can be used as excellent components for blending road asphalt in order to improve its quality, and 2) as a booster in propane deasphalting. Compared to vacuum residue, catalytic cracking slurry has a higher density, lower viscosity, and lower flash point. The extraction process for propane deasphalting involves bringing the feed material into contact with propane in an extraction tower, using the difference in density to separate the deasphalted oil from the deoiled asphalt. Therefore, blending catalytic cracking slurry increases the feed density and decreases the viscosity of the extractor tower, which facilitates the extraction process and improves the yield of deasphalted oil. Guangzhou Petrochemical Company conducted industrial trials on a propane deasphalting unit by adding 16.4% catalytic slurry; under the same deasphalting conditions, the yield of deasphalted oil increased by 11%. This technology is highly productive and easier to industrialize compared to the furfural extraction process. 3. Used as a rubber softener and filling oil. Rubber softeners are additives used in the rubber processing industry to improve the properties of the rubber compound, with petroleum-based softeners being the most widely used. Adding a softener to raw rubber not only improves the plasticity of the compound, reduces its viscosity and the temperature during mixing, thereby shortening the mixing time and saving energy consumption during mixing, but it also enhances the dispersion and mixing of carbon black with other additives. It acts as a lubricant during calendering and extrusion, and at the same time it reduces the hardness of the vulcanized rubber while increasing its tensile strength, elongation, and cold resistance. FCC slurry has a high density and viscosity, as well as a high content of aromatics and naphthenes; it exhibits good compatibility with synthetic rubbers. Therefore, it is suitable for use in the processing of synthetic rubbers such as styrene-butadiene, cis-butadiene, and chloroprene rubber, as well as natural rubber. It is also appropriate for use in heavy-duty tires and dark-colored rubber products. Luoyang Petrochemical Engineering Company uses FCC heavy aromatic hydrocarbons (FCCHA) to produce rubber softeners. FCCHA possesses a unique unsaturated molecular structure with a high content of aromatic compounds, and its polarity is similar to that of conventional SBR/BR rubbers. As a result, it exhibits good compatibility with rubber, facilitates the dispersion of carbon black, and ensures uniform mixing with the rubber compound. It fully meets the requirements of rubber processing. Moreover, the softeners made from FCCHA feature a high molecular weight, a high flash point, a low freezing point, resistance to freezing, and ease of use. 4. Production of petroleum aromatic plasticizers. Petroleum aromatic plasticizers have good compatibility with PVC resin, are easy to use for plasticization, offer good electrical and mechanical properties, are inexpensive, and can help reduce the cost of PVC products; they can be used as auxiliary plasticizers, replacing up to 1/3 of the primary plasticizer. PVC using aromatics as auxiliary plasticizers has excellent properties, allowing it to be used not only in rigid and semi-rigid products but also in soft products; thus, it holds great market prospects. 5. Used as carbon fiber material. Carbon fiber materials are a new type of material featuring high strength, high toughness, heat resistance, wear resistance, corrosion resistance, and radiation resistance; they are widely used in fields such as aerospace, military industry, healthcare, and sports and entertainment products. Asphalt-based carbon fibers have attracted considerable attention due to their low cost, as well as their high strength and high modulus. Currently, the United States and Japan have achieved good results in the development of asphalt-based carbon fibers. The basic composition of FCC slurry is a fraction containing large amounts of 2-4 ring aromatic hydrocarbons, with boiling points primarily in the range of 300°C–500°C. Based on the theory of intermediate phase formation through liquid-phase carburization and inference from intermolecular interaction energy, the oil slurry system exhibits high aromaticity; the temperature range over which the intermediate phase remains plastic is wide, facilitating the formation of an anisotropic, graphitizable microstructure. Therefore, FCC slurry is one of the high-quality raw materials for producing carbon fiber materials. 6. Used for the production of needle coke. Acicular coke, also known as high-quality petroleum coke, is a new type of carbon material. The carbon products made from it possess high crystallinity, high purity, low ablation rate, and a low coefficient of thermal expansion, which is why they are widely used in fields such as steel manufacturing and aerospace. According to the formation mechanism of needle coke, the raw materials used for its production must meet requirements such as a high aromatic content (excluding polycyclic large-molecule aromatics), a BMCI value of not less than 120, low levels of impurities, and low contents of ash metals. Additionally, they should exhibit a high intermediate conversion temperature and a wide range of intermediate phase temperatures during the thermal conversion process, thereby enabling the formation of larger intermediate phase spheres. The FCC clarifies that oil is almost entirely composed of aromatics with short side chains, making it the best raw material for producing needle coke. In collaboration with Anqing Petrochemical Plant, the Beijing Research Institute of Petroleum and Chemical Technology conducted industrial trials on the plant’s 400,000 t/a delayed coking unit; using FCC clarified oil and reprocessed oil extract as raw materials, a needle coke yield of 40% could be achieved. 7. Used for producing carbon black. Carbon black is an important raw material in rubber processing and ink production. The heavy aromatics in FCC slurry have a high carbon content and few impurities, making them an excellent raw material for producing carbon black. Abroad, FCC light cycle oil and clarified oil are commonly used directly as raw materials for producing carbon black; they yield high yields, produce particles with fine sizes and good strength, making them suitable as fillers for high-grade rubber products. Used in the metallurgical industry as electrodes for high-grade electric furnaces, they can withstand severe thermal shocks and high current densities. 8. Used as an additive for enhanced distillation of residue oil. Enhanced distillation refers to the addition of active substances to crude oil or heavy oil to increase the distillation yield. Using catalytic cracking slurry as an activator to enhance crude oil distillation in order to increase the yield of light oils and the overall yield of distillates is one of the research topics that has received considerable attention at present, and its development direction is worth watching. The Heavy Oil Research Institute of the Petroleum University adds catalytic slurry to atmospheric residue for redistillation (intensified distillation). By blending catalytic slurry into atmospheric residue, in addition to obtaining distillate oil equal to the amount of slurry added, 3%-4% (based on the atmospheric residue) of distillate oil can also be obtained. Experimental results show that, at the same percentage yield of residue, distillation after blending with oil slurry increases the penetration of the residue. For residue with the same penetration, the elongation of the distilled residue after blending with oil slurry increases. Therefore, subjecting atmospheric residue to vacuum distillation after blending it with catalytic slurry not only increases the yield from vacuum distillation for use as a secondary processing feedstock, but also improves the properties of the residue. 9. Used as heat transfer oil. Heat transfer oil is an important heat carrier in petrochemical production. At present, the main similar products in China are the YD series of heat transfer oils produced by Beijing Yanshan Petrochemical Company; their main components are aromatic hydrocarbon compounds such as naphthalene, methylnaphthalene, and dimethylbenzene, that is, aromatics with 3–4 rings. The actual flash point of YD-type heat transfer oil ranges from 110°C to 140°C, and its raw material comes from medium-weight aromatics in catalytic diesel. The light and heavy aromatics extracted from the catalytic slurry can be used as two grades of heat transfer oil products. The flash point ranges from 200°C to 280°C, and its performance is **superior to that of similar domestic products. Furthermore, slurry can be used as a brightener for casting. Aromatic pitch is a type of high-brightness carbon material, with a brightness carbon content that can exceed 50%, which is 7 to 15 times that of natural cast coal powder. Industrial casting tests conducted by major factories such as the Process and Materials Research Institute of Luoyang Tractor Factory and Shanxi Yuci Hydraulic Parts Factory, along with systematic research carried out by Tsinghua University, have shown that it offers excellent anti-sticking properties. The castings produced have smooth surfaces, and there are no irritating odors during the casting process, **which reduces the labor intensity required for cleaning the surface of the castings. The quality of the castings is excellent; it is the best anti-sand-clogging material in China, reaching international advanced standards. Our country is a major producer of castings, with an annual output of millions of tons. Due to the lower cost of aromatic asphalt, market demand is expected to increase. Additionally, oil slurry can also be used as a solvent for special building coatings and similar products.
This post was last edited and replied to by lijianhuai on 2011-7-1 at 13:47. Reply 2# wuzhangzhu: Catalyst slurry typically contains 500–1000 ug/L of catalyst powder, and the presence of this powder limits the effective use of the slurry, forcing most of it to be used only as a component in the formulation of fuel oil. The main methods for removing catalyst powder from the oil slurry include natural sedimentation, flocculation sedimentation, electrostatic separation, filtration separation, and centrifugal separation. The oil slurry after the separation of catalyst powder is called clarified oil, and its properties vary greatly depending on the characteristics of the crude oil and the conditions of the production process. The slurry we studied during our studies in school basically contained no catalyst powder, and it’s not entirely clear what separation methods were used. Most of the slurry in our workshop is now sent to the coking plant.