【Ten Years of Rapid Development in Chemical Equipment】2189–2025: New Mechanisms for Fluidized-Bed Gas-Liquid Alternating Polymerization and New Technologies for High-Grade Polyethylene Production
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Give praise and encouragement to the achievements made in China’s chemical engineering technology and equipment; your participation in discussions is the greatest encouragement. **********************【Ten Years of Great Progress in Chemical Engineering Equipment】Regularly updated summary posts – feel free to join the discussions: https://bbs.hcbbs.com/thread-3576046-1-1.html ***************** The first prize for technical inventions awarded by the Chemical Industry Federation in 2024: a new mechanism for fluidized-bed gas-liquid alternating polymerization and new technologies for producing high-quality polyethylene. Polyolefins are essential basic materials for strategic development and economic construction. China’s production capacity has exceeded 30 million tons per year, but there are significant structural issues in the product mix, with high-end polyethylene specialty materials relying heavily on imports. Among these, the gas-phase fluidized bed process accounts for over 45% of polyethylene production capacity; however, the limited options for adjusting this process lead to relatively homogeneous products and intensified competition due to homogenization. Recently, the new mechanism for fluidized-bed gas-liquid alternating polymerization and the new technology for producing high-end polyethylene, developed jointly by Zhejiang University and its Tianjin branch, won the First Prize for Technical Invention from the Chemical Industry Federation for the year 2024. Products such as the special material for octene-1 copolymerized polyethylene films and the special material for tetrapolymerized polyethylene films, produced using this technology, provide strong support in addressing the reliance on imported materials for high-end polyethylene applications. Promoting the advancement of high-end polyethylene: China’s polyolefin production capacity ranks first among the three major synthetic materials. The “14th Five-Year Plan” Guidelines for the Development of the Chemical New Materials Industry also state that high-end polyolefins are at the top of the eight types of chemical new materials that should be prioritized for development. However, at present, there is a severe shortage of high-end polyolefin products in our country, with a self-sufficiency rate of less than 40%. To promote the advancement of high-end polyethylene production in China, a project team led by Wang Jingdai, vice president of Zhejiang University, introduced the new concept of \"liquid-retaining particle polymerization.\" They invented an ethylene polymerization method that alternates between liquid-retaining particle polymerization and gas-phase polymerization, and based on this approach created \"cloud zones\" for liquid-retaining particle polymerization with varying temperatures and concentrations as well as \"non-cloud zones\" for gas-phase polymerization within a single fluidized bed. As a result, they developed technology for fluidized-bed reactors using liquid-retaining particle polymerization as well as new polymerization processes. The product possesses unique advantages such as a high degree of branching, a high relative molecular mass, a wide molecular weight distribution, and strong component compatibility. In engineering applications, it further overcomes the density limits of products produced by fluidized bed processes, enabling the facility to save costs such as foreign technology licensing fees and investment amounts exceeding 200 million yuan.
【Ten Years of Rapid Development in Chemical Engineering Equipment】2188–2025: Key Technologies and Applications for the Large-Scale Production of Liquid Fuels and Carbon Materials from Biomass https://bbs.hcbbs.com/thread-5679008-1-1.html (Source: Haichuan Chemical Industry Forum [Chemical Currents])
How can inert solutions be made \"non-inert\"? How can high-performance polyethylene products be produced through process innovations? Based on the theory of a new polymerization model using liquid-retaining particles, this team developed a series of key technologies to achieve a mechanism for the coexistence of different flow patterns, as well as techniques for the stable operation and optimization of reactors, thereby enabling practical application in engineering. Wang Jingdai stated that in liquid-retaining particle polymerization, the continuous phase is ethylene gas, while the discrete phase consists of active particles covered with a liquid film. Compared to gas-phase polymerization and slurry polymerization, this method results in polyethylene with an increased degree of branching, as well as a higher relative molecular weight. At the same time, compared to gas-phase polymerization, although liquid-retaining particle polymerization has a high content of inert alkanes, it enables inert solvents to become \"non-inert\". “Although inert solvents do not participate in the reaction themselves, they can promote the enrichment of reactant components and increase the reaction rate by influencing the reaction environment. ”Wang Jingdai explained that this is because the solvents n-hexane and isopentane are compatible with each other, which leads to a significant concentration increase of the comonomers 1-hexene and 1-octene, thereby enhancing the molecular diffusion term for α-olefins ； At the same time, when inert droplets collide with catalyst particles, it causes the liquid film to surge, thereby enhancing the convective diffusion term for α-olefins ； Furthermore, in this mode, the droplets are suspended in the fluidized bed, with the interface updating rapidly, thereby increasing the mass transfer surface area. It is the combined effect of these factors that causes inert solvents to exhibit \"inertness\", thereby indirectly facilitating the reaction. Building on the discovery of the \"regulable polymerization microenvironment in alkane liquid films,\" they developed a series of new technologies for ethylene polymerization reactors using fluidized beds with liquid-retaining particles. These include mechanisms and techniques for the coexistence of multiple flow patterns, methods for regulating these flow patterns and coordinating them with catalyst injection, as well as approaches for scaling up such fluidized-bed reactors. These innovations address the challenge of achieving coexistence of multiple flow patterns under the combined effects of liquid spraying, fluidization, and reaction. To enable engineering applications, they developed a new ethylene polymerization process using a slurry-particle fluidized bed, which includes a liquid-phase separation and injection system, temperature-controlled oscillation technology, and particle agglomeration prevention techniques, thereby addressing the challenges of temperature fluctuations and particle agglomeration at high slurry contents.
The industrial applications have yielded impressive results. As determined by the China Petroleum and Chemical Industry Federation, this achievement is highly innovative, with its overall technology at the international leading level. To date, this technology has been applied in industrial plants with a capacity of 120,000 tons per year, enabling the successful development of four categories of polyethylene grades, including ultra-low density and multi-component copolymers. It has since been extended to six plants with a capacity of 300,000 tons per year or more, yielding significant social and economic benefits. Regarding the advantages of this technology in industrial applications, Wang Jingdai used Tianjin Petrochemical’s 120,000 tons per year production facility as an example and explained: \"The team utilized conventional titanium-based catalysts along with relatively inexpensive 1-butene and 1-hexene as comonomers to develop a series of ultra-low density polyethylene products, overcoming the product density limit of 0.915 grams per cubic centimeter associated with the fluidized bed process and achieving densities as low as below 0.895 grams per cubic centimeter.\" ” In addition, the team has developed four new product series with grades whose performance indicators such as strength and toughness far exceed those of traditional vapor-phase process methods. In terms of the output of specialty materials, unit consumption, and energy consumption, compared with typical plants that use foreign technology, the plants operated by the Tianjin branch have a specialty material output ratio of over 90%, which is nearly 10 times the average value for similar plants across the country.
Give praise and encouragement to the achievements made in China’s chemical technology and equipment sector
【Ten Years of Rapid Development in Chemical Engineering Equipment】2190-2025: CNOOC Engineering completes construction of China’s first 2,000-meter-class ultra-deepwater tree https://bbs.hcbbs.com/thread-5679086-1-1.html (Source: Haichuan Chemical Industry Forum [Hua Hai Chuan Liu])