Thread Content
This post was last edited by WoBenShanliang on August 14, 2016, at 16:29. Progress in the application of hydrocracking technology for residue oil. At present, China’s economic development has entered a “new normal” phase, with greater emphasis being placed on the quality of development, environmental protection, and resource conservation. Achieving clean energy production and efficient utilization is the main challenge facing the green, clean, and sustainable development of China’s refining industry. Currently, international oil prices are low, and it is no longer economically viable for refineries to process very low-quality crude oil. However, in the long term, the trend toward increasingly lower quality crude oil is inevitable, and heavy oil processing technologies, including those for viscosity reduction, coking, and residue hydrogenation, remain key technologies that need to be focused on and continuously developed and improved in the future. Compared to thermal processing methods such as viscosity reduction and coking, residue hydrogenation technology offers strong adaptability to different feedstocks and processing flexibility, enabling the clean and efficient utilization of residues. It is therefore a key technical solution for addressing the challenge of increasingly heavy and low-quality crude oils. Residue hydrogenation technology is mainly divided into hydroprocessing and hydrocracking according to its application. Resid hydrotreating technology primarily involves fixed-bed hydrotreating, a mature process used for resid upgrading to serve as feedstock for catalytic cracking units; however, the conversion rate is typically only 15%–20%. Residue hydrocracking technology is mainly divided into two types: fluidized bed and suspended bed, which are used to convert low-quality residues into fuel oils. The fluidized bed hydrocracking technology can be used to process low-quality residue oils with high carbon residue and metal content; it combines both cracking and refining functions, offering high conversion rates (60%–80%) and a high degree of refining ； However, the hydrogen pressure is high (>15 MPa), which also imposes special requirements on the catalyst. The primary characteristics of the residue suspension bed hydrocracking technology are a high conversion rate and a low amount of effluent tail oil. Compared to fluidized-bed hydrocracking, the conversion rate in suspended-bed hydrocracking can generally reach over 90%, demonstrating a clear advantage; however, it is not yet as mature and widely used in industrial applications as fluidized-bed hydrocracking. Current status and comparative analysis of technological applications: 1. Residuum fluidized-bed hydrocracking technology >>>> Current application status. Globally, the main residuum fluidized-bed hydrocracking technologies include Axens’ H-Oil technology, CLG (Chevron Lummus Global)’s LC-Fining technology, and Sinopec Group’s STRONG technology. Currently, commercially operational residue fluidized-bed hydrocracking units all employ H-Oil and LC-Fining technologies. Sinopec’s STRONG technology has seen an industrial demonstration unit built, and preliminary tests have been conducted. As shown in Table 1, the industrial application units of H-Oil technology from Axens have been used in approximately 13 enterprises, with a total production capacity of around 24 million tons per year. The LC-Fining technology of CLG Company is deployed in, and under construction in, the facilities shown in Table 2; it has been applied industrially in approximately 13 enterprises, with a total production capacity of nearly 32 million tons per year. Among them, the LC-MAX residue processing technology (a combination of LC-Fining and solvent deasphalting) was first licensed to Shandong Shenchili Chemical Co. in China in 2013; the 2.76 million tons per year plant that the company is building is scheduled to come online in 2016. The Fushun Research Institute of Petroleum and Petrochemicals, Sinopec, has successively completed a series of technological developments, including the fluidized-bed hydrocracking process, catalysts, patented equipment and its internal components, the catalyst loading/unloading control system, and the treatment of spent catalysts. Ultimately, it has developed the STRONG integrated technology with independent intellectual property rights. In September 2015, Jinling Petrochemical built an industrial demonstration plant using the STRONG technology with a capacity of 50,000 tons per year, and conducted preliminary tests. The results of these tests were satisfactory; once the technology is further refined, plans are to build an industrial-scale plant. >>>>Technical comparison analysis: The H-Oil technology typically uses two reactors in series, whereas LC-Fining employs three reactors in series, resulting in a higher impurity removal rate. As shown in Figure 1, there is no fundamental difference between these two processes; their reactor structures are essentially the same, both including a fluid distribution system, a separation and recycling system, and an online addition and removal system for catalysts, with the catalysts being interchangeable between them as well. The difference is that the H-Oil technology uses an external circulation mode with an external circulation pump, while the LC-Fining technology employs an internal circulation mode with an internal circulation pump. 2 Residue slurry bed hydrocracking technology >>>> Current application status: At present, there are two residue slurry bed hydrocracking units in operation worldwide, with a combined capacity of 1.8 million tons per year. ENI’s EST technology was put into use in October 2013 at the Sannazzaro refinery in Italy to operate an industrial unit for residue fluidized-bed hydrocracking with a capacity of 1.35 million tons per year. BP’s VCC technology was used in January 2015 at the Yanchang Petroleum Group to put into operation the world’s first 450,000 tons per year kerosene co-processing plant, with a feed ratio of coal to oil of 1:1. In addition, multiple units are currently under construction or planned for construction. For example, Pakistan **Refining Limited has adopted the Uniflex SHC technology and plans to start operations in 2016; at that time it will produce 2 million tons per year of diesel and 225,000 tons per year of lubricants ； The Russian Mendeleev Group is using VCC technology to build an industrial facility with a capacity of 3.5 million tons per year, with commissioning expected in 2018 ； The Puerto La Cruz refinery in Venezuela is using the HDHPlus/SHP technology to build a plant with an annual capacity of 2.75 million tons, with commissioning expected in 2016. >>>>Technical comparison analysis: To improve the conversion rate of residue and the yield of products, aside from the VCC technology, other technologies recycle the unconverted bottom oil or vacuum gas oil back to the reactor for further conversion. The catalysts used also vary; a comparative analysis is presented in Table 4. The EST, HDHPlus/SHP, and VRSH technologies employ a recycle operation scheme for unconverted bottom oil, enabling quite high conversion rates. In the EST process, the non-converted bottom oil is subjected to solvent deasphalting; the resulting asphalt and catalyst are then recycled back to the reactor. Only a small amount of tail oil is discharged, with a conversion rate exceeding 97% ； In the HDHPlus/SHP process, the oil from the bottom of the converter, after having the metals recovered in a metal recovery unit, is mixed with the feed oil to continue the hydrogenation reaction, achieving a conversion rate of nearly 100% ； A portion of the non-converted bottom oil from the VRSH process is returned to the first reactor for further reaction; the heavier fraction, after solvent deasphalting, has its catalyst in the residue re-activated and recycled. The conversion rate is nearly 100%. In addition to the cyclic reaction of unconverted bottom oil, the HDHPlus/SHP and VRSH technologies also involve the cyclic reaction of straight-run vacuum gas oil. The HDHPlus/SHP technology circulates the straight-run vacuum gas oil to the SHP section for hydrogenation, whereas the VRSH technology sends it to a second fluidized bed reactor. The UniflexSHC technology adopts a one-pass scheme for residue, with vacuum heavy gas oil being recycled to the reactor for further reaction; some unconverted bottom oil is removed, achieving a conversion rate of >90%. The VCC technology employs a single-pass scheme for residue oil, sending straight-run vacuum gas oil to the hydrotreating section, with a conversion rate of 85%–95%. The treatment methods for unconverted bottom oil using the aforementioned technologies are shown in Table 5; these mainly include coking, cement production, asphalt blending, and the extraction or recovery of metals from unconverted oil. New developments in R&D 1: Slurry oil fluidized bed hydrocracking technology. In addition to being used for the hydrocracking of conventional slurry oil, fluidized bed hydrocracking technology is primarily employed for the hydroprocessing of unconventional crude oils such as those from Canadian oil sands asphalt; it is often used in combination with coking and solvent deasphalting processes to produce synthetic crude oil. In recent years, research on fluidized-bed hydrocracking technology has also mainly focused on the integrated development with technologies such as coking and solvent deasphalting. >>>>Combined integration process: At the 2012 annual meeting of the American Fuel and Petrochemical Manufacturers Association (AFPM), Axens and CLG presented the integrated processes of H-Oil – delayed coking – and LC-Fining – solvent deasphalting (LC-Max). The most typical feature of the LC-MAX process is the layout of the solvent deasphalting (SDA) unit. In many previous processes that utilized a combination of SDA with fluidized-bed and fixed-bed hydrocracking, the SDA unit was generally placed upstream of the residue hydrocracking unit. This indeed made residue hydrocracking easier to carry out, but the overall conversion rate was affected due to the large amount of asphalt produced after the solvent deasphalting of vacuum residue. Therefore, the SDA unit must be installed in locations where asphalt formation is to be minimized and the overall conversion rate is to be increased. CLG Company used vacuum residue derived from difficult-to-process Russian exported crude oil as raw material, and conducted hydrocracking tests using the LC-Fining and LC-MAX processes respectively; the test data are shown in Table 6. The LC-Max process is seeing the construction of the world’s first industrial plant in Dongying City, Shandong Province, China. With an annual production capacity of 2.76 million tons, the plant is scheduled to come online in 2016. It will primarily process a 50:50 mixture of Merey-18 and Arab heavy crude oil distillate residues, achieving a conversion rate of 90%; as a result, ultra-low sulfur diesel meeting Euro V standards and naphtha suitable for catalytic reforming will be produced. The deoiled asphalt produced by the LC-MAX unit is used as a raw material in a gasification unit (E-Gas technology transferred from CB&I Company) to produce hydrogen. Based on the research and development of the STRONG process, the Fushun Research Institute of Petrochemicals of Sinopec has successively carried out the development of integrated processes such as fluidized bed-catalytic cracking, fluidized bed-coking, and fluidized bed-fixed bed residue hydrogenation. The test results show that when catalytic cracking experiments are conducted using residue from boiling bed hydrogenation, the yield of light oils is above 63%, while the yield of gasoline + diesel + liquefied gas is 78.27%. This indicates that after being treated by boiling bed hydrogenation, such low-quality residue can be used as a feedstock for catalytic cracking, resulting in high yields of light oils; moreover, when catalytic cracking cycle oil is blended in at different proportions, the yield of gasoline + diesel + liquefied gas increases by at least 1.04% ； Compared with the conventional coking process, the integrated fluidized bed-coking process for processing low-quality residue oil increases the total liquid yield by 13.57%, resulting in significant economic benefits. Additionally, this integrated process offers advantages such as wide raw material adaptability, process flexibility, and high stability of the produced oils, making it an excellent solution for the efficient utilization of crude oil resources ； In the integrated fluidized-bed fixed-bed hydrotreatment process for treating low-quality residue oils with metal contents of 118 g/g and 233 g/g, respectively, and carbon residue contents of 15.7% and 21.1% respectively, both the fluidized-bed and fixed-bed units can operate stably. The metal contents in the resulting hydrotreated residues are 10.6 g/g and 7.8 g/g, respectively, while the carbon residue contents are 5.6% and 5.2% respectively; these residues can be used directly as feedstock for catalytic cracking units, offering better economic viability. This setup enables stable operation over 3 years, allowing it to match downstream units and facilitate simultaneous start-up and shutdown. Represented by the delayed coking process and fluidized bed hydrocracking process, which are the most commonly used for processing vacuum residue, the U.S.-based Fluor Company utilized the linear programming model of Aspen software to compare the economic viability of three alternatives: the coking option, the fluidized bed hydrocracking option, and the combination of fluidized bed hydrocracking with existing coking processes, as shown in Table 7. Compared to the coking option, which only requires an 23% increase in capital expenditure, the boiling bed hydrocracking option offers a 3.9% higher return on investment ； A combined approach of fluidized-bed hydrocracking and existing coking units can even achieve better returns. Furu Company believes that the economic evaluation of upgrading vacuum residue must be determined based on capital expenditures, raw material and product markets, project location and logistics, as well as return on investment; no single solution can apply to all situations. The fluidized bed hydrocracking approach is potentially attractive for large refineries with a production capacity of over 15 million tons per year; however, for existing or newly built refineries with a capacity of 10–12.5 million tons per year, the capital expenditure required for this approach exceeds the financial capacity to undertake such investments. The combination of fluidized-bed hydrocracking and existing coking can increase the yield of distillates, which is better than using either process alone. However, the coking capacity of this combination is limited by the amount of coke produced; this issue can be addressed by balancing the conversion rates of residue oil in coking and fluidized-bed hydrocracking. To achieve the efficient processing and utilization of heavy vacuum residue, the Topchiev Institute of Petrochemical Synthesis in Russia and the U.S.-based company CLG have jointly developed a hydrocracking process for residue in a fluidized bed, which utilizes specially synthesized ultrafine nanocatalysts. This process involves extremely low catalyst consumption—no more than 0.01%—and generates no waste. The catalysts are insensitive to impurities; they almost completely convert heavy oil components with high contents of resins, asphaltenes, metals, sulfur, and nitrogen into light and medium distillates, thereby maximizing the production of fuels, petrochemical products, and base oils. Under conditions of a reactor hydrogen pressure of 6.0–8.0 MPa and a space time of 0.5–2.0 h–1, 92%–95% of the feed can be converted into light components such as gasoline and diesel, with fuel oil production significantly reduced or even eliminated, making it highly economically attractive. Table 8 shows the changes in product yields before and after the refinery adopted this process. It can be seen that, without the production of fuel oil, the yields of liquefied gas, naphtha, and diesel all increased significantly, while gasoline production decreased slightly; the overall output increased by 37%. >>>> Catalysts At present, the boiling bed hydrocracking catalysts available on the international market include Albemarle’s KF series (KF1300, KF1315, KF1312, KF1316, KF1317, etc.), Criterion’s RN series (RN-680, RN-681) and TEX series (TEX2910, TEX2720, TEX2731, TEX2740), as well as HDS-1495. ART’s GR series, LS series, ULS series, as well as HSLS and HCRC are also available. TEX2910 is the latest generation of fluidized bed catalyst developed by Criterion Company, featuring excellent sediment control and residue conversion capabilities, as shown in Figure 3; it is suitable for two-stage reactors. The newly developed HCRC catalyst by ART Corporation can reduce reaction severity and minimize thermal reactions, thereby significantly decreasing the formation of deposits/coke and improving the conversion rate of residue. Under normal reaction conditions, using an HCRC catalyst, the conversion rate of residue increased by 4%, while the desulfurization and denitrification rates improved by 4% and 3%, respectively. The removal rate of microchar increased by 6%, and the nitrogen content in distillates and vacuum wax oils also decreased. Meanwhile, ART explored the reaction effects of employing a dual-catalyst system of HCRC/HSLS in a fluidized bed reactor setup, namely using the HSLS catalyst in Reactor 1 and the HCRC catalyst in Reactors 2/3. Pilot test results show that, compared to using the HCRC catalyst alone, the HCRC/HSLS dual-catalyst system enhances the operational flexibility of the plant, as shown in Figure 4. The product yield and selectivity can be adjusted by optimizing catalyst performance, modifying the catalyst loading ratio, and changing reaction conditions, while the removal efficiency of impurities (sulfur, nitrogen, metals) can also be controlled. 2. Residuum suspended-bed hydrocracking technology: Although two industrial units utilizing the suspended-bed hydrocracking technology have been put into operation, the technology is not yet mature; there is still a long way to go before its large-scale application. At present, the research efforts of various institutions still focus on ensuring the long-term operation of the devices (with an emphasis on addressing the problem of coking), as well as on developing catalysts with high activity and good dispersion. >>>>Process: The industrial operation of the world’s first 1.35 million tons/year residue slurry bed hydrocracking unit shows that the temperature in the slurry bed reactor remains essentially constant, with an axial temperature difference of <2°C and a radial temperature difference of <0.1°C. It offers efficient gas-liquid separation without the formation of bubbles. The raw material conversion rate reaches 95%–96%, with no coke being produced. The product quality meets the design requirements, with the yield of Euro V diesel exceeding 40%. Three months after the first start-up, due to external factors such as power failures that caused disruptions in the steam conversion unit, and considering the need to improve the reliability, efficiency, and operating procedures of the unit, it was decided to shut it down for maintenance. In June 2014, the adjusted unit was brought online for the second time; it is said to have been operating well, with further technical improvements still in progress. ENI has licensed this technology; in July 2015, it signed the first technology transfer agreement with Total. In addition to the more well-known processes such as EST, HDHPlus/SHP, UniflexSHC, and VCC, the Iranian Petroleum Industry Institute (RIPI) has also developed a heavy residue hydrocracking process (HRH). This process has been patented in countries such as the United States, Canada, South Korea, and Japan, and an industrial plant with a capacity of 180,000 barrels per day is currently under design. The HRH process features the use of nanocatalysts to produce high-value products without the need for decarburization ； The sulfur removal rate reaches 60%–80% ； Removes metal impurities from the feed and recovers them in the form of metal oxides through a proprietary separation process ； The volume recovery rate reached 110%. Compared to larger-sized nanocatalysts, smaller-sized nanocatalysts exhibit better mobility and higher activity. >>>>Catalysts: At present, ENI is working on the development of second-generation nanocatalysts, with the aim of improving their cracking efficiency and exploring catalyst recovery techniques from unconverted bottom oil. China National Petroleum Corporation is conducting research on oil-soluble catalysts. It has successfully developed a series of oil-soluble Co, Mo, and Ni catalysts, which exhibit better hydrogenation performance than the existing water-soluble catalysts. Additionally, it has identified anti-coking additives and their optimal concentrations suitable for various raw materials. The company has also studied the sulfidation process conditions, thereby preliminarily determining the oil-soluble catalysts and additives. The Research Institute of Petroleum Industry (RIPI) of Iran has developed a method for preparing nanocatalysts for slurry-phase hydrocracking. By selecting appropriate surfactants and using different formulations to achieve an optimal hydrophilic-lipophilic balance, it is possible to obtain the smallest possible droplet size. Studies have shown that the use of non-ionic surfactants can reduce the size of nanocatalysts by a factor of 10, to 1–2 nm, as shown in Figure 5; this means that the diameter of the active metal is only 1/100 of the size of the asphaltenic micelles. Therefore, this catalyst possesses better catalytic activity, enabling a significant improvement in the performance of suspended-bed hydrocracking units, and providing the possibility for the development of a new generation of such hydrocracking processes. The Mexican Institute of Petroleum prepared a liquid-phase catalyst (a homogeneous catalyst made from sulfuric acid, ammonium heptamolybdate, and nickel sulfate, suitable for the slurry-bed hydrocracking process) in the laboratory for the hydrocracking of residue oil, and it was compared with hydrocracking using thermal cracking and a commercial heterogeneous catalyst (NiMo/Al2O3). The experiment was conducted in a autoclave reactor, and the experimental results are shown in Table 9. Under the same experimental conditions (100 kg/cm2, 420°C, reaction time of 1 hour, oil-to-catalyst ratio of 1:250), thermal cracking yielded the lowest conversion rate, at 46.7%; heterogeneous catalyst hydrogenation cracking came next with a conversion rate of 53.8%, while liquid-phase catalyst hydrogenation cracking achieved the highest conversion rate, at 65.3%. This is because liquid-phase catalysts have the best dispersibility and fluidity ； However, heterogeneous catalysts are more effective for desulfurization and denitration, possibly due to the higher concentrations of Ni and Mo on them. Furthermore, this liquid-phase catalyst can be recovered and reactivated for reuse, offering cost advantages over heterogeneous catalysts. Due to their large specific surface area, metal nanoparticles can enhance catalytic activity, and they have been widely used in catalytic processes in recent years. Korea’s Korea University made an initial attempt to use the nanosheet structure WS2 as a dispersed catalyst in the hydrocracking of residue oil. The experiments were conducted in a high-pressure reactor at a reaction temperature of 400°C and a hydrogen pressure of 70 bar; the experimental results are shown in Table 10. The reaction activity of single-layer and multi-layer WS2 catalysts was evaluated based on the experimental results, and they were compared with conventional bulk WS2 and Mo S2 catalysts. The single-layer WS2 catalyst, having the smallest particle size and thus the highest specific surface area (97.6 m2/g), exhibited the best reaction performance, with a C5 asphaltenes conversion rate of 75.3% and an API value for the liquid products of 13.8 (API is a measure of the density of petroleum products established by the American Petroleum Institute). Conclusion: As the most efficient mature technology for the processing of residue at present, fluidized-bed hydrocracking will continue to play an important role in the global utilization of residue. Although fluidized-bed hydrocracking technology has been widely applied, there is still much room for improvement in this technology. Future research and development will focus on further improving the adaptability of raw materials, the degree of conversion, and the lifespan of catalysts, as well as reducing catalyst consumption. At the same time, there is a need to further develop and apply integrated processes that combine fluidized bed technology with other techniques, as well as processes for treating unconverted residual oil. Suspension bed hydrocracking technology represents a world-class challenge and cutting-edge technique in the modern petroleum refining industry; it holds good prospects for widespread application, but it is necessary to develop highly active and well-dispersed catalysts as well as to address the issue of coking in the reactors. Furthermore, since the raw materials used in slurry bed processing are of lower quality, the majority of the metals in these materials, the condensation products formed during the reaction process, and almost all catalysts end up concentrated in the unconverted bottom oil. As a result, the unconverted bottom oil has poor reprocessing properties, making it difficult to utilize it for further processing. Therefore, how to properly handle and utilize unconverted bottom oil is another technical challenge and research direction for the industrialization of slurry bed hydrocracking technology and to avoid environmental pollution. Source: Author: China National Petroleum Corporation Research Institute for Petroleum and Petrochemicals (Ren Wenpo, Li Zhenyu, Li Xuejing, Jin Yuhao); compiled by Shihua Yuan and Chemical Engineering 707 editorial team