HETS height equivalent to a theoretical

HETS Height equivalent to a theoretical stage, ft. k A constant... 

HETS height equivalent to a theoretical stage Jt total volumetric flow rate per unit area... 

The height equivalent to a theoretical stage (HETS) in an extraction tower is simply the height of the tower Zt divided by the number of theoretical stages achieved [Eq. (15-29)]. 

An additional expression of performance used for countercurrent cascades, particularly for those in the design of towers (see below), is HETS, the height equivalent to a theoretical stage. 

These terms sometimes are used interchangeably with height equivalent to a theoretical stage (HETS), but they are nearly the same only when the ratio kjka is a large number in the case of HTUa. Example 13.12 studies this difference. 

Although the most useful extraction process is with countercurrent flow in a multistage battery, other modes have some application. Calculations may be performed analytically or graphically. On flowsketches like those of Example 14.1 and elsewhere, a single box represents an extraction stage that may be made up of an individual mixer and separator. The performance of differential contactors such as packed or spray towers is commonly described as the height equivalent to a theoretical stage (HETS) in ft or m. 

In order to permit sizing a tower, data must be available of the height of a transfer unit (HTU). This term often is used interchangeably with the height equivalent to a theoretical stage (HETS), but strictly they are equal only for dilute solutions when the ratio of the extract and raffinate flow rates, E/R, equals the distribution coefficient, K = xE/xR (Treybal, 1963, p. 350). Extractor performance also is expressible in terms of mass transfer coefficients, for instance, KEa, which is related to the number and height of transfer units by... 

HETS, relative height equivalent to a theoretical stage. source R.F. Strigle, Jr., Random Packings and Packed Towers, Gulf Publishing, Houston, TX, 1987. Reprinted with permission. 

Eckert [9] showed that a relative height equivalent to a theoretical stage (HETS) vs. the dispersed-phase velocity revealed the packed-column efficiency, or simply the required height, to make one theoretical stage. (See Fig. 7.10). Eckert and others [6, 8] have shown that normally the theoretical packed-column stage requires 2.5 ft of column packed height. All this of course refers strictly to liquid-liquid extraction processing. Also, the continuous-phase velocity Vc (ft/h) and the dispersed-phase velocity VD (ft/h) are referenced to the liquid-phase... 

In continuous differential extractors (columns) it has been convenient to think in terms of a height equivalent to a theoretical stage (HETS), and to correlate HETS as a function of system and equipment variables. Alternately, correlations may be obtained on the basis of the height of a transfer unit (HTU), which is more amenable to calculations which separately include the effects of backmixing.l H ... 

In reciprocating plate columns, the height equivalent to a theoretical stage (HETS) is a strong function of the reciprocating speed, Af, the product of the reciprocation amplitude and frequency. Karr columns actually exhibit optimal values for A/where the (HETS) is clearly minimized. These... 

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