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basic processing equipment in absorption processes. The absorber, frequently called a scrubber, features a developed surface for phase contact between a gas and a liquid. Several types of absorbing towers are known.
The absorbing tower (Figure 1) is a metal or ceramic column accommodating several horizontal grids (1) with beds of packing (2) (coke, metallic or ceramic rings, wooden gratings, stones, and so forth) and is designed to increase the gas-liquid phase-contact surface area. A mixture of gases enters the bottom of the column through the pipe (3), and the absorbent material fed into the tube (4) flows downward through the packing counterflow to the rising mixture of gases. As a result of this counterflow contact of the gas and vapor phases, the components of the gas mixture to be absorbed in the absorbent bed go into solution completely. The nonabsorbed gas
mixture components are vented from the tower via pipe (5), while the saturated absorbent flows downward through pipe (6). The cones (7) intervening between the packing sections (2) direct absorbent pushed out by the vapor toward the wall of the absorbing column back toward the center, in order to achieve more uniform wetting.
A more complicated absorbing tower comprises a column (Figure 2) in which trays (1) equipped with pipe connections (2), caps (3) with serrated edges, and overflow tubes (4) replace the grids and packing. The absorbent flows down from the tray to the tray below through the overflow tubes, while the mixture of vapors moves upward, bubbling through the layer of liquid. The vapor stream, on passing through the serrated edges of the bubble caps, breaks up into a mist of fine bubbles, thereby presenting a larger vapor-liquid phase-contact surface area. In some cases, trays in which a large number of holes have been drilled—sieve trays—are used instead of bubble-cap trays.
Absorbent towers in which the vapor moves over the surface of the liquid (bonbonne), or where the liquid becomes dispersed in fine droplets in the gas by the action of nozzles rotated by disks or turbines, are frequently employed in processes where the vapor dissolves in the absorbent.
REFERENCESRamm, V. M. Absorbtsiia gazov. Moscow, 1966.
Ciborowski, J. Osnovy protsessov khimicheskoi tekhnologii. Leningrad, 1967. (Translated from Polish.)
Kasatkin, A. G. Osnovnye protsessy i apparaty khimicheskoi tekhnologii, 8th ed. Moscow, 1971.
V. L. PEBALK