New Highspeed Mass-transfer Trays

The mass-transfer trays HighspeedTray, HighFlexiTray and SieveTray belong to a new generation of mass transfer trays that enable increase the capacity-efficiency profile and the flexibility of tray columns significantly. This increase is achieved by a special vapor and liquid distribution and contact systems installed on these trays and a combination of two different tray designs. These trays cover gas/vapor load factors F up to 12 Pa and turndowns up to 1:20. They offer a miniaturization of columns, which results in significant savings of equipment costs. The trays can be used for new mass transfer equipment as well as for revamp of existing columns. INTRODUCTION Some fundamentally new designs in column internals have been developed and introduced during the last years. These new internals offer a dramatic gain in efficiency and capacity for separation columns. These internals are characterized by optimal capacity-efficiency profiles, improved operation properties and low costs. Bravo [1] wrote recently about this development „the 1990s are the decade of high performance tray“. Especially fractionation trays have a large potential for significant improvements, using new principles for the organization of the contact between the phases on the trays which allow to increase the process intensity and efficiency. Another direction for increasing the capacity-efficiency profiles of mass transfer columns is to combine new tray constructions with conventional ones in such a way that the new design gains the benefits of both trays and the new internals possess the best properties of the highspeed tray as well as the good properties of the conventional trays. In this paper are presented new tray designs and tray combinations. One design, the HighspeedTray, is characterized by special contact and separating elements (CSE) on the trays. In the inner of these CSE massand heat transfer take place in cocurrent flow. The combination of highspeed trays with valve trays offer a new mass transfer column design the new HighFlexiTray with a very high flexibility (turndown). Another way of increasing the capacity-efficiency profile of conventional fractionation trays consists in enlarging the mass transfer surface area and its permanent renewal. The SieveTray represents a conventional sieve tray with a special froth stabilizer which allows to increase the capacity of sieve columns up to twofold. THE HIGHSPEED MASS-TRANSFER TRAY The high-speed mass transfer tray [2-5] (Fig. 1) is a tray with weir and downcomer. It is equipped with contact and separating elements fixed into the opening of the tray plate. The CSE consists of a vertical cylinder with an annular row of holes in its lower section. The axial swirler, which is firmly attached to the inside of the cylinder has inclined vanes in the upper section and is provided with a net of ribs arranged straightly along the nozzle axis at the lower section. The mass exchange zone is directly above the swirler. The cyclone separator with the concentric annular slot separates the liquid from the gas/vapor phase. Deflection rings have to prevent the short-circuit of the liquid after the mass transfer.