Chen Junwu: The story of the origins of catalytic cracking technology in China’s oil refining industry

Phase 1: Initial efforts in independent research and development and exploration of foreign technologies. In the early 1960s, the catalytic cracking technology used at the Lanzhou Refinery, which was built with the help of the Soviet Union, was of the moving-bed type; the catalysts used were still amorphous silica-alumina spheres. In contrast, the West already possessed fluidized catalytic cracking technology, with catalysts in the form of microsphere molecular sieves, resulting in much higher yields of light oils and better selectivity compared to that of the Soviet Union. We found that Soviet technology was 20 years behind Western technology, equivalent to the level of the United States in the 1940s. At that time, the Soviet Union also did not have more advanced technology; their technology had not progressed beyond the level of that available in the United States in the 1940s. Therefore, how to catch up with the international advanced technologies of the 1960s was a major challenge facing the domestic oil refining industry at that time. At that time, ordinary foreign technologies could be sold to you, but strategic advanced technologies were never sold to us. The United States imposed a technological blockade on China, forcing the country to consider developing its own technologies and rely on its own efforts for exploration and innovation. This was the original intention behind the scientific and technical conference on the development of new oil refining technologies held by the Ministry of Petroleum in Beijing in December 1961. However, some of the experiments we conducted at Lanzhou Refinery were not successful, as there was excessive loss of catalyst; we are very eager to go abroad to study advanced catalytic cracking technologies. At the end of 1961, several experts from our Ministry of Petroleum were invited to Cuba for an inspection. The ministry’s leaders visited two refineries in Cuba, one built by the United States and the other by Britain. Among them was the most advanced fluidized catalytic cracking unit at that time; this technology was one of the new technologies to be developed, as determined at the Xiangshan Conference held by the Ministry of Petroleum, and I was appointed as the designer for this unit. The leaders of the Ministry of Petroleum felt that a trip to Cuba was a once-in-a-lifetime opportunity. In Cuba’s refineries, the high-level personnel were all foreigners; after the success of the Cuban Revolution, most of them left. Cuba generously provided us with a lot of information, but how do you make use of it? Information alone isn’t enough to solve problems; it needs to be processed and transformed into skills that one possesses, which requires a great deal of effort. The leaders of the Petroleum Ministry are determined to send five more technical experts from different fields to Cuba for on-site inspections. I specialize in process engineering and am a designer for facilities in Fushun; I am tasked with combining engineering design work in China with field inspections abroad. The other colleagues come from fields such as equipment, machinery, and instrumentation. The extensive literature on fluidized catalytic cracking studied in Cuba not only helps to address the technical issues related to fluidized catalytic cracking but also covers other related technologies in petroleum refining processes. Our research team focused on catalytic cracking technology, while also taking into account technical information related to atmospheric and vacuum distillation as well as catalytic reforming; within half a year, we made every effort to copy or organize this information in written form. At the time, the core issue was to figure out the problems related to processes and equipment, so as to guide domestic engineering design and equipment manufacturing. Fortunately, several of us who went to Cuba took on this responsibility; we inspected everything that needed to be inspected and noted down everything that needed to be recorded. So after returning, I developed China’s catalytic cracking technology from scratch, starting from nothing. Over the two and a half years from September 1962 to February 1963, and again from September 1964 to February 1965, we mastered the core of this technology; in many aspects, we not only understood how it worked but also understood why it worked that way.

Phase two: from \"imitating by copying\" to \"imitating by learning from the master model\". The 600,000 tons per year fluidized catalytic cracking units built in Fushun and Daqing can be considered an example of \"imitating by copying\"; later, the Ministry of Petroleum decided to design and build a 1.2 million tons per year fluidized catalytic cracking unit at the Shengli Oil Refinery in Shandong, which represents \"imitating by learning from the master model\". The design of this system was carried out by the Beijing Design Institute, with me serving as the technical advisor. Problems arose during the process of imitating others, and the main issue was our inadequate technical skills. Copying verbatim is fine, but when the scale is doubled and the installation capacity is also doubled, problems arise. Moreover, the management at that time required some innovation, and under these circumstances, there were issues with the design we created. By the end of 1967, the 1.2 million tons per year fluidized catalytic cracking unit was operating relatively stably during the commissioning phase, but the daily catalyst loss amounted to about 30 tons, forcing the unit to shut down. It would definitely be unsustainable to consume 30 tons of catalyst per day. At that time, China was conducting research on this type of catalyst (which was also one of the development tasks under the “Five Golden Flowers” project); however, it couldn’t yet be produced on an industrial scale. The catalyst used in China at the time was the imported British-made 3A zeolite molecular sieve catalyst, which was extremely expensive. This requires us to thoroughly study the basic theory of fluidization and identify the causes of catalyst loss in industrial equipment. But this cannot be done in the laboratories of any research institute; tests must be carried out on-site at large industrial facilities. The regenerator of industrially operating units in hot operation has a diameter of about nine meters; it cannot be replicated as easily in a laboratory, which requires the development of proper testing and research plans. I was appointed as the head of the special investigation team, leading the team on multiple trips to Fushun and Daqing. After analyzing and comparing the data on the normal operation of the fluidization process in Daqing, as well as the catalyst density and distribution data related to the design of the regenerator in the 1.2 million tons per year catalytic cracking unit, it was determined that uneven airflow distribution in the fluidized bed was the key reason for catalyst loss at Shengli Oil Refinery. The problems encountered with industrial units prompted us to conduct more in-depth theoretical studies on the fluidization mechanism. We started by investigating and testing units with a capacity of 600,000 tons per year; after that, we carried out partial tests on larger units with a capacity of 1.2 million tons per year, followed by full-scale tests. This process was repeated numerous times, and eventually some patterns were identified, which became the testing rules and design standards for subsequent fluidized catalytic cracking units. Testing is about understanding the patterns and data that we were not fully aware of before; through new tests, more data is obtained, and after organizing it, further improvements are achieved. Testing is not that simple; when the diameter of a large-scale reactor or regenerator is increased by ten times, it is not easy to understand all the complexities involved. Both theoretical analysis and certain fluidization testing techniques are required. Later, as the scale of our refineries increased, a 600,000-ton/year fluidized catalytic cracking unit became insufficient, and it was necessary to increase its capacity to 1.2 million tons per year. As the scale increases, many problems arise in terms of fluidization, and these are addressed by combining theoretical analysis with testing and diagnosis. After developing a set of testing and diagnosis methods, both the operational efficiency and design quality of industrial plants improved significantly, and the design scale of fluidized catalytic cracking units reached a new level. In 1962, we began to learn about the foreign 600,000 tons per year catalytic cracking technology by imitating it, and it was put into operation in 1965; the 1.2 million tons per year catalytic cracking system was also developed through imitation, and it came online in 1968. After some problems arose, continuous improvements were made, and by 1969 it had been successfully operational – in other words, we succeeded even through imitation.

Phase 3: The design institute builds an oil refining experimental plant. In 1972, the Ministry of Fuel Chemistry approved the construction of an oil refining experimental plant at the Luoyang Design Institute, aimed at systematically developing new processes, materials, and equipment for oil refining. After the experimental plant was completed in 1975, a series of experiments on catalytic cracking were carried out, establishing a new model of technological innovation that closely integrated engineering design with technology development. Before the 1970s, no residue oil was blended into foreign catalytic cracking feedstocks. Considering that the contents of nickel and vanadium—elements harmful to catalysts—in China’s Daqing crude oil are very low, we set up a pilot plant to conduct catalytic cracking tests involving the blending of atmospheric residue from Daqing crude oil. Stable production was achieved without the need for external heating. Meanwhile, the Petroleum and Chemical Science Research Institute also achieved success in experiments at the Mudanjiang Refinery, thus breaking the taboo surrounding the use of residue oil in catalytic cracking. In 1983, the predecessor of Sinopec Group, the China Petrochemical Corporation, was established. In order to bring our country’s refining technology to the international forefront, it was decided to launch efforts to advance this field. Academician Min Enze and I served as the head and deputy head of the catalytic cracking task force, which was part of the **\"Sixth Five-Year Plan\" research projects. The goal was to develop new processes for catalytic cracking of atmospheric residue from Daqing, as well as new types of catalytic cracking catalysts. I divided the key research topic into nine sub-topics, and categorized the heat extraction from the regenerator bed into two categories: heat extraction via internal coils and heat extraction via external heat exchangers (the external heat exchangers were further subdivided into \"upstream\" and \"downstream\" types). In the structural design of the external heat exchanger, I proposed a high-efficiency heat extraction scheme using longitudinal finned tubes, which improved the heat transfer efficiency and made the heat exchanger structure more compact. At the same time, some basic applied research that had been lacking in the past was also initiated; for example, the Petroleum University was tasked with conducting research on coking kinetics, while the Institute of Process Engineering of the Chinese Academy of Sciences was assigned to carry out research on fluidization. In 1985, the catalytic cracking project for atmospheric residue oil in Daqing was successful at the Shijiazhuang Refinery. These achievements have placed China at the world’s leading level in the field of catalytic cracking of residue oil. Abroad, catalytic cracking units have employed various layout configurations such as side-by-side units at the same height, units with different heights placed side by side, and coaxial units. In China, however, the catalytic cracking units built in earlier years all adopted the side-by-side configuration at the same height. Following the advice of Mr. Jiao Liansheng, the company’s deputy chief engineer, I developed a coaxial catalytic cracking unit at the company’s Luoyang test plant – one that required less space and was more flexible to operate. Key challenges were overcome in terms of plug valves, process control, and two-stage regeneration; as a result, a catalytic cracking unit with an annual capacity of 50,000 tons was put into operation. After evaluation by experts from Sinopec, guidance was provided to a team led by Mr. Chen Daoyi to build a unit with an expanded capacity of 500,000 tons per year in Lanzhou. This unit won the **Design Gold Award** and the **First Prize for Scientific and Technological Progress** in 1984 and 1985 respectively. In 1988, Chief Engineer Zhu Renyi from the Shanghai Gaqiao Petrochemical Refinery proposed to me that the newly built 1 million tons per year catalytic cracking unit at Gaqiao should feature both a compact coaxial design and efficient regeneration of the coking drums. We accepted this challenge and proposed a more innovative solution involving the installation of a large-hole distribution plate at the top of the coking vessel, with a high-speed turbulent bed placed on this distribution plate. Fluidization tests were conducted at the company’s equipment research institute, and the system was successfully put into operation at the Takahashi Petrochemical Company’s refinery. Today, we are able to design fluidized catalytic cracking units flexibly according to the process requirements of enterprises, with production capacities ranging from 50,000 to 100,000 tons per year to 3.5 million to 4 million tons per year. The engineering design of catalytic cracking has evolved from mere imitation to a truly innovative approach. If the successful development of the Fushun catalytic cracking unit back then was like a single blooming flower, now it is like a garden full of beautiful flowers. As one of the developers of fluidized catalytic cracking engineering technology in China, I have witnessed the development and growth of China’s refining technology, and I feel extremely proud.

Study hard, Chen Junwu, and make contributions to the development of the petrochemical industry.

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