Discussion on the Optimization of the Entire Refining Production Process

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In recent years, due to the persistently high international oil prices and the domestic refined oil pricing mechanism, China Petrochemical’s refining segment has experienced significant book losses for an extended period of time. Faced with increasingly fierce market competition, Sinopec must rely on conceptual innovation, technological innovation, and management innovation to intensify the optimization of the entire refining process, and build a transnational energy and chemical company with strong international competitiveness. To make use of foreign ideas to drive conceptual innovation, and to achieve the ambitious goal of “building a transnational energy and chemical company with strong international competitiveness,” Sinopec should first, while adhering to independent innovation, learn from, absorb, and draw on advanced foreign concepts and proven experiences, thereby making use of foreign ideas to promote conceptual innovation. Since the 1990s, international oil companies such as Shell have developed a theory for optimizing the processing of heavy oil: by using a reduced-pressure deep drawing operation mode to lower the yield of reduced-pressure residue, and by shortening the coking cycle and reducing the recycle ratio, they increase the operating intensity and processing load of coking units in order to maximize economic benefits from heavy crude oils. The strategy implemented by Sinopec to downgrade the quality of crude oil has yielded good economic benefits, but some companies have failed to fully utilize the potential of their heavy oil processing facilities such as coking units; as a result, straight-run residue is sold directly as fuel oil, which reduces the profitability associated with crude oil downgrading. For example, Shell’s cut point for vacuum wax oil is generally above 560°C; the cut point for newly built atmospheric and vacuum distillation units has reached 615°C. In contrast, Sinopec’s cut points are usually below 540°C, with the highest being around 580°C. The reasons are as follows: first, the manufacturing process is imperfect and the equipment materials are not suitable. Although the designed cut-off temperature for the wax oil is 540°C, the heating tubes in atmospheric and vacuum distillation units are typically made of ordinary carbon steel, and there are no processes such as quenching oil at the bottom of the vacuum tower or steam injection into the vacuum distillation tubes ； The material of the coke drums in some delayed coking units is also ordinary carbon steel, and shortening the coke formation cycle can easily lead to creep spheroidization of the coke drums. The process flow can be improved at an appropriate time, and the equipment materials can be upgraded to lay a solid foundation for the optimization of heavy oil. Second, there are cognitive \"blind spots\" in the technical operation process. Operators are often concerned that an increase in the furnace outlet temperature may cause coking of the furnace tubes, affecting the production cycle. Practice has shown that the technique of calculating and plotting the coking curve of a heating furnace allows for an intuitive reflection of its operating conditions. It is precisely thanks to ideological emancipation and innovative concepts that Qingdao Refining & Chemicals boldly raised the outlet temperature of the vacuum furnace to 419°C and reduced the coking cycle ratio to 0.15, with both of these indicators reaching international advanced levels. Enterprises with insufficient heavy oil processing capacity and those that export crude distillate residue can draw on the experience of Qingdao Refining & Chemical to further improve the operational efficiency of their heavy oil systems. Adapt measures to local conditions and promote technological innovation. In the practical process of optimizing oil refining and chemical processing systems, different specialties have varying starting points and focuses, which leads to contradictions in technical management and hinders the advancement of optimization concepts as well as the implementation of optimization measures. The main current challenges restricting technological innovation are as follows: 1. The promotion of catalytic cracking flue gas turbine power generation technology. Sinopec has 60 catalytic cracking units, with a total processing capacity of over 60 million tons per year. According to the design, 80% of the exhaust turbines can be used for power generation; in other words, the main fans and exhaust turbine systems can supply electricity externally. This is a strength that makes China’s catalytic cracking technology ahead of that of foreign oil refining companies. At present, only 6 catalytic cracking units at companies such as Takahashi Petrochemical, Jiujiang Petrochemical, and Luoyang Petrochemical have reached power generation conditions. The reason is that at the critical operating conditions just before power generation, frequent changes in the unit’s drive method have an adverse effect on its operation. The equipment engineering team, from the perspective of protecting the units, believes that operation under these conditions is not feasible, while the petroleum refining engineering team, focusing on energy conservation and emission reduction, emphasizes the necessity of generating electricity. This conflict directly affects the adoption of smoke turbine power generation technology. The experience of companies that have already implemented power generation shows that, as long as the process technology is sound, comprehensive plans are in place, and critical operating conditions are avoided, this technology is still worth promoting and implementing. 2. Optimization of the pump head. The phenomenon of excessive head in the pumps used in current refining units is very common; since 2004, the refining division has been actively promoting the use of \"cutting impellers\" as a technique to reduce pump head. However, in the actual implementation process, there are significant differences among various companies in terms of the degree of impeller cutting. The reason for the slow progress in these companies is mainly that some equipment managers are afraid of the hassle, concerned about an increased workload, and worried that it might affect the operation of the equipment. This requires us to adopt a perspective focused on scientific development, further emancipate our minds, gain a deeper understanding of actual production conditions, eliminate localism, and intensify efforts to optimize things. 3. Catalytic slurry as a coking feedstock. In petroleum refining, feeding catalytic cracking slurry into coking not only enables the conversion of fuel oil into gasoline and diesel, but also effectively improves the distribution of coking products and reduces the yield of petroleum coke. Under the current price system, companies such as Qingdao Refining & Chemical, Zhenhai Refining & Chemical, and Jiujiang Petrochemical have processed all of their catalytic slurry in coking operations, achieving good economic benefits. However, many enterprises are still concerned that oil slurry may affect the quality of petroleum coke and cause wear on furnace tubes. As a result, there is a lack of unity in thinking, insufficient understanding, and inadequate implementation of measures to incorporate catalytic cracking oil slurry into the coking process, which hinders and restricts the improvement of the overall economic efficiency of oil refining. Therefore, to enhance a company’s core competitiveness, it is necessary to actively foster an environment that encourages learning about technology, trusting in technology, and relying on technology. Efforts should be made to improve capabilities in original innovation, integrated innovation, and the ability to introduce, adapt, and further develop existing technologies. Mature practices and advanced concepts should be widely adopted to facilitate continuous optimization, while management innovation must also be promoted. In the face of an ever-changing international economic landscape and market demands, Sinopec must keep breaking free from traditional mindsets and habits, and focus on advancing management innovation. As factors such as market demand, raw material properties, and price systems change, the objectives of optimization also evolve dynamically. 1. Overcome the habit of seeking convenience; adhere to precise operation to achieve ultimate control. First, it is necessary to overcome the tendency to take shortcuts for ease, be meticulous in every action, and make the most of even the smallest resources – \"even a dry towel should be squeezed to extract three drops of water.\" Refining and chemical integration enterprises should learn from Shell by recovering hydrogen, propylene, and other high-value products from dry gas, thereby making efficient use of low-carbon hydrocarbon resources. Second, it is necessary to break away from the fixed operational patterns and seek opportunities to improve efficiency in light of market changes. Third, it is necessary to adhere to the scientific outlook on development, and apply the concepts of molecular optimization and end-to-end process optimization to improve energy efficiency and productivity in oil refining. On the basis of achieving thermal combined feeding, the heat exchange network should be optimized to recover low-temperature waste heat, and insulation coating technologies should be used to reduce heat loss from the tank areas and heating furnaces. Energy conservation and efficiency improvement should be vigorously promoted from the perspective of energy flow optimization. 2. By moving from the local to the overall, from the microscopic to the macroscopic level, and by promoting the concept of end-to-end optimization, China Petrochemical aims to maximize overall efficiency. For this company, achieving maximum overall efficiency is the goal and direction of its optimization efforts; in the technical services provided in recent years, optimizing individual units or making partial improvements has yielded far less significant gains compared to end-to-end optimization. Therefore, on the basis of achieving local optimization, it is necessary to carry out coordinated planning, focusing on the integration of refining and chemical processing, as well as the optimization of resources and key processes, in order to create a new landscape of optimization across the entire oil refining process. 3. Explore and improve management models to ensure the continuous progress of dynamic optimization efforts. At present, companies such as Maoming Petrochemical, Qingdao Refining & Chemical, Jingmen Petrochemical, and Jiujiang Petrochemical have established optimization teams specializing in different areas to carry out optimization activities within their own organizations ； At the headquarters level, technical services are provided by leveraging expert resources within the system, and common improvement is achieved through knowledge sharing. Companies need to achieve innovation and breakthroughs in terms of management models and concepts. They should establish specialized optimization teams within their comprehensive management departments, leverage expert resources in research and development, design, management, and production operations, use software models as tools to improve quality, provide the necessary investment to ensure the implementation of these measures, and employ administrative constraints to guarantee the execution of critical processes and the ongoing optimization of entire workflows. Refining optimization is a dynamic process of change. Sinopec must take into account both the crude oil and product markets, as well as the characteristics of its production facilities. It needs to be open-minded, innovative, and willing to take responsibility, pursuing comprehensive innovation in terms of concepts, technology, and management. By applying advanced principles of system optimization and end-to-end process optimization, it can drive continuous improvements in efficiency, enabling refining companies to become even more advanced while those that are less advanced strive to catch up, thus maintaining a leading position in China and building multinational energy and chemical companies with strong international competitiveness