Absorber bubble column

Bubble column [3.48-3.53], vessel absorber Bubble columns without liquid circulation ... 

In the following first example the liquid ozone concentration and the OH-radical concentration are calculated with semi-empirical formula from the mass balance for ozone (Laplanche et al., 1993). For ozonation in a bubble column, with or without hydrogen peroxide addition, they developed a computer program to predict the removal of micropollutants. The main influencing parameters, i. e. pH, TOC, U V absorbance at 254 nm (SAC254), inorganic carbon, alkalinity and concentration of the micropollutant M are taken into consideration. 

Reactive absorption can be realized in a variety of equipment types, e.g., in him absorbers, plate columns, packed units, or bubble columns. This process is characterized by independent how of both phases, which is different from distillation and permits both cocurrent (downflow and uphow) and countercurrent regimes. 

There are several other types of apparata used for reactive absorption, though these are less widespread. In mechanically agitated bubble columns it can be assumed that both phases are ideally mixed, whereas in the jet absorber, the gas stream breaks on a liquid surface and is dispersed in the liquid. In spray towers and venturi scrubbers, liquid is sprayed as fine droplets. Thin-jilm contactors, in which liquid film is scrapped from the walls by impellers, are applied for reactive absorption in viscous liquids. Some units, such as wetted-wall columns, contactor, laminar jet absorber and disc (sphere) column are used mainly in laboratory. 

The two bubble class model is applied here to the absorption of CO2 in NaOH, which conforms to a fast pseudo-first order reaction under certain operating conditions (15). In the data reported by Schumpe et al. ( 7 ), COo was absorbed during cocurrent flow in NaOH solution in a 0.102 m diameter bubble column. The gas phase consisted of approximately 10 vol % of CO2 in N2. The gas velocities ranged from 0.025 to 0.15 m/s. Since the churn turbulent regime prevailed for gas velocities greater than approximately 0.07 m/s, only the data in the range 0.07 m/s to 0.15 m/s were considered. 

Description Fresh methanol is split into two streams and is contacted with reactor offgas in the high-pressure absorber (7) and light gases in the low-pressure absorber (8). The methanol, exiting the absorbers, are recombined and mixed with the recycle liquid from the recycle-surge drum (6). This stream is charged to a unique bubble-column reactor (1). 

Bubble columns where a gas is dispersed through a deep pool of liquid are commonly used in industry as absorbers, strippers, or reactors when a large liquid holdup, large liquid residence time, or large heat transfer is needed. They may be operated either countercurrently, cocurrently, or semibatch. Other advantages of bubble columns are the absence of moving parts, minimum maintenance, small floor space, ability to handle sol-... 

For some gas-liquid reactions, it is advantageous to use a very tall reactor rather than one that is shorter but larger in diameter. With a tall bubble column, the hydrostatic head increases the driving force for gas absorption at the bottom, and this effect plus the increase in gas residence time permits a greater fraction of the reactant gas to be absorbed. A tall reactor also requires less space for installation. Other factors to consider are the increased work of compression, though the work does not go up in proportion to the depth, and the effect of hydrostatic head on the volumetric gas... 

Fluid phase only Countercurrent flow Absorber Countercurrent flow Absorber Countercurrent flow Spray tower Co-current or countercurrent Bubble column Absorber or Reactor Venturi Static mixers Falling film, etc. 

Bubble columns where a gas is dispersed through a deep pool of liquid are commonly used in industry as absorbers, strippers or reactors when a large liquid holdup, large liquid residence... 

Unlike some other absorbers (for example, bubble columns), by proper design, harmful deviations from plug flow behaviour may be avoided although many different parameters have adverse effects. 

Gas is dispersed into the wash liquid, the liquid phase remains continuous (column absorber with transfer trays, bubble columns, vessel absorber, dispersing agitator)... 

In bubbling columns [3.1] during the absorption process mass and heat transfer takes place at the interface of bubbles rising in the wash liquid, which is at rest or slowly moving. Bubbling columns are suitable when poorly liquid-soluble gases have to be absorbed (Fig. 3-17). 

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