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Propane dehydrogenation (PDH) processes rely heavily on efficient tower internals to maximize propylene yield and product purity. Among these, packing materials and structural tower internals are critical for optimizing mass and heat transfer. This article explores the primary materials used for propane dehydrogenation tower internals and their suitability.
Stainless steel is the most widely used material for tower internals in PDH units. Grade 316L and 321 stainless steel are preferred due to their excellent corrosion resistance, especially against hydrogen and process impurities like hydrogen sulfide. These alloys also offer high-temperature strength, withstanding the elevated temperatures (typically 500–600°C) common in PDH reactors and fractionators. Stainless steel packing, such as metal孔板波纹填料 (metal orifice plate structured packing), provides high efficiency with low pressure drop, crucial for maintaining process throughput.
Ceramic tower internals are another viable option, particularly for severe service conditions. Alumina and silica-based ceramics exhibit exceptional thermal stability and chemical inertness, making them suitable for highly corrosive or abrasive environments. ceramic packing, like raschig rings or Berl saddles, offers good wettability and resistance to thermal shock, though they are heavier than metal alternatives and may be more prone to breakage under mechanical stress.
Plastic materials, such as polypropylene (PP) and polyvinylidene fluoride (PVDF), are used in less demanding applications. They are lightweight, cost-effective, and resistant to certain chemicals, but their operating temperature limits (often below 150°C) restrict their use in high-temperature PDH sections.
Selection of tower internals material depends on process conditions: temperature, pressure, feed composition, and desired efficiency. For most modern PDH plants, stainless steel packing remains the gold standard for balance of performance and durability, while ceramics and plastics serve niche roles in specific unit sections. Understanding these material options is key to designing reliable and efficient propane dehydrogenation systems.
