When choosing tower internals, with “jet-type trays” being so popular, how can you not be aware of them?

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When selecting tower internals, the popularity of \"jet-type trays\" is well-known – how could you not be aware of this? According to the Chemical Engineering 707 News Network, mass transfer and separation are extremely important chemical processes, and the performance of towers has a direct impact on production energy consumption, product yield, product purity, processing capacity, and environmental emissions, among other factors. Firstly, it is a process that requires high energy and incurs high costs; its energy consumption accounts for about one-third of the total energy consumption of chemical plants, or even more. U.S. statistics show that approximately 40% to 50% of the total energy consumption in the oil and chemical industries is used for distillation processes. If product separation during the manufacturing process does not meet the required standards, it can affect the reaction yield, increase the amount of by-products, cause catalyst poisoning, reduce the quality of the product, or result in emissions that violate regulations and thus pollute the environment. Classification of tower equipment: Tower equipment can be divided into packed towers and plate towers based on the structure of their internal components. The mass transfer processes in these towers fall into three categories: film flow, bubble flow, and spray flow. Among them, the mass transfer process in plate towers is divided into two main categories: bubbling regime and spray regime. Introduction to bubble-type trays: Bubble-type trays include bubble caps, floating valves, and sieve plates. The structure of these trays is shown in the figure below: bubble cap, floating valve, sieve plate. Analysis of the mass transfer characteristics of bubble-type trays: 1. The gas phase exhibits high turbulence, good dispersion, and rapid surface renewal. The poor dispersion in the liquid phase, large local volume of the continuous phase, and long transfer paths within the component phases result in a low transfer rate. 2. Foaming system: The bubbling state during contact itself leads to bubble formation; these bubbles are not easy to break, and both gas and liquid phases are carried along together, resulting in backmixing and a decrease in plate efficiency. In severe cases, flooding may occur. 3. The pressure drop increases; in the bubbling phase, the gas phase must pass through the hydrostatic layer of the tray, and the hydrostatic resistance as well as the resistance associated with the wet tray are quite high. 4. It is prone to being covered or clogged by solid substances and highly viscous materials, resulting in poor anti-clogging performance ； Introduction to jet-type trays 1. Mass transfer process in jet-type trays: Gas enters the cap region at an accelerated velocity as it passes through the holes in the tray plates, while liquid enters the cap region from the gap at the bottom of the tray plates. The gas lifts the liquid that has entered the cap region; after passing through processes such as film formation, film breaking, and fragmentation, this liquid then impacts the top of the cap. After the impact, the gas-liquid mixture is ejected horizontally from the side holes of the cap, the liquid droplets fall back onto the tray, while the gas rises to the upper tray. First, intense collisions and turbulent mixing between the gas and liquid within the enclosure facilitate one mass transfer process, after which the gas-liquid spray enables another mass transfer process. This process relies on the kinetic energy of the gas to transform the liquid from a continuous phase into a dispersed phase, resulting in the formation of numerous liquid droplets. We call this process the jet mass transfer process. 2. Analysis of the mass transfer characteristics of spray-type trays: Large interphase area: In the spray state, the liquid phase is transformed into a dispersed phase, resulting in numerous small liquid droplets. This provides a large interphase area for gas-liquid mass transfer, thereby **increasing** the mass transfer rate. This is also the biggest difference between it and bubbling mass transfer, where the liquid phase is a continuous phase with relatively few phase interfaces. Molecules in the liquid travel shorter distances: When the liquid phase is dispersed into numerous small droplets, the distance that molecules within the phase have to travel to reach the phase interface **decreases**, the time required for them to do so is reduced, and this lowers the resistance to mass transfer across the liquid phase. High tray space utilization: The gas-liquid contact involves a rising process inside the canopy and a falling process outside it, resulting in a large mass transfer area and a long residence time; 70% of the tray space can be utilized for mass transfer. Fast interface renewal: The droplets of the dispersed phase as well as the gas move at high speeds and collide violently, which accelerates the renewal of the droplet surface and increases the rate of molecular transfer. 3. Advantages of jet-type trays file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8DEE.tmp.jpg High production capacity: Compared to F1 floating valves, the processing capacity can be increased by 20%-50% ； file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8DEF.tmp.jpg High efficiency: For different material systems, the mass transfer efficiency is 10%-20% higher than that of F1 floating valves ； file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8DF0.tmp.jpg Plate pressure is lower: more than 20% lower than that of a regular F1 float valve ； file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8E00.tmp.jpg High operational flexibility: it can continue to function properly even under high levels of operational load ； file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8E01.tmp.jpg Strong resistance to clogging: capable of handling materials containing solid particles and those prone to self-polymerization, thereby extending the operational life of the device ； Has defoaming properties: particularly suitable for handling materials that tend to form bubbles, such as file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8E02.tmp.jpg ； file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wps8E03.tmp.jpg The liquid ejected from the nozzle is directional: this reduces liquid backmixing and the liquid level gradient, thereby increasing the mass transfer efficiency. 4. Jet-state patented tray technology 1. New Vertical Screen Tray (New-VST): New-VST is an achievement of Hebei University of Technology and is widely used in the chemical industry. Suitable for operating conditions with a low liquid-to-gas ratio. This technology won the First Tianjin Science and Technology for City Development Outstanding Contribution Award. 2. Radial Side Guide Jet Tray (CJST): CJST is a high-efficiency tray developed on the basis of the New-VST. It exhibits excellent adaptability to operating conditions with large tower diameters and high gas-liquid phase loads. This technology was selected as a project supported by the **Innovation Fund of the Ministry of Science and Technology in 2005. 3. Low-resistance membrane spray trays: This technology is well-suited for vacuum distillation systems where reduced resistance is required, for mass transfer processes that involve cooling for heat transfer, for reactive distillation, and for mass transfer processes in which self-polymers are formed. 4. Membrane spray non-backmixing tray plates (MPⅠ,Ⅱ,Ⅲ): This technology is a new product developed on the basis of low-resistance membrane spray tray plates, aimed at addressing the issue of reduced tray efficiency caused by backmixing. Suitable for operating conditions with a high liquid-to-gas ratio as well as separation processes involving materials prone to clogging. This technology was supported by the **Innovation Fund of the Ministry of Science and Technology in 2009. Separated-flow non-backmixing spray tray (PFST): This tray relies on the use of separated-flow plates to divide the liquid phase on the tray into a lean liquid stream and a rich liquid stream. It achieves no backmixing, no retention, and no skew flow in the tray. The liquid dropping system features a rectangular suspension design, which helps to hold the liquid and reduce bubbles, thereby minimizing gas phase backmixing. This tray is particularly suitable for systems with large liquid volumes and prone to foaming. Due to the advantages of its technical features, the jet-type tray has been widely applied in various industries such as coking, oil refining, natural gas processing, gasification, fine chemicals, methanol production, fertilizer manufacturing, chlor-alkali industry, and pharmaceuticals, delivering significant economic and social benefits.