uop最新pfmd 高效率塔盘

UOP Sells First PFMD Tray in Aromatics Revamp UOP sold a set of Parallel Flow Multiple Downcomer (PFMD) trays in 2011 for use in an Isomar Unit Deheptanizer for the Arabian Fibers Industrial Company (IBN RUSHD) IR-2 aromatics debottlenecking project in Yanbu, Saudi Arabia. The objective of the revamp is to increase paraxylene product capacity and to maximize benzene production. This marks the first commercial sale of PFMD trays. The dual-diameter deheptanizer columnwas identified as a bottleneck for the future expansion rates. Above the feed point, PFMD trays were chosen to replace conventional sieve trays in the 2800 mm ID top section due to their high capacity without loss of efficiency, allowing for a1-for-1 retray with thirty-two (32) PFMD trays. Due to the significant increase in liquid load below the feed point, higher capacity ECMDTM trays were chosen to replace conventional sieve trays in the 3200 mm ID bottom section on a 5-for-4 retray basis with thirty-four (34) ECMD trays. The column capacity is expected to be limited by the heavily liquid-loaded bottom section. Technical Features The PFMD tray is the latest generation of UOP trays to make use of parallel flow to improve the efficiency. The tray is divided into four quadrants, each separated by a downcomer. Liquid spirals down the column so that the liquid in each column quadrant is always flowing in the same direction on each tray (see Figure 1). The efficiency gain from this type of flow is frequently referred to as a Lewis Case II enhancement. The spiral flow liquid is combined with MD tray technology so that the PFMD tray has a capacity that is more than an MD tray and with an efficiency that is greater than an MD tray and expected to be equal to a conventional tray. The benefit of parallel flow is that the rising vapors are never exposed to the same liquid composition between two trays. On conventional distillation trays, the liquid composition at the inlet to the downcomer on one tray is the same as the composition at the downcomer outlet on the tray below. This creates a “pinch point” where there is no driving force for mass transfer. Parallel flow eliminates this pinch point (see Figure 2). In addition to the unique parallel flow design, PFMD trays combine the features of other UOP distillation trays to optimize capacity and efficiency: Like other trays in the MD family, PFMD trays have long weir lengths and no seal pans for high capacity and low pressure drop. Directional slots from UOP Slotted Sieve trays are used to create preferential liquid flow direction, eliminate stagnant areas on the tray deck, and reduce froth height for higher vapor handling capacity and separation efficiency. Bubble promoters are used at the inlet to each tray deck to initiate bubbling, reduce liquid head, and prevent weeping at the inlet. This results in lower pressure drop, and higher efficiency and capacity. A sloped downcomer design allows for a deeper downcomer for higher capacity and improved operating range. Advantages and applications PFMD trays are ideal in lower pressure (less than 10 barg) columns with high vapor rates where MD trays have lower efficiency, such as: Low pressure C2 splitters Raffinate, extract, or finishing columns in Aromatics complexes Deisohexanizers and deheptanizers Methanol columns The combination of high capacity, high efficiency, and low pressure drop make PFMD trays a great solution fo