Equivalent height

In the case of a plate column the performance of a real plate is related to the performance of a theoretical one by the plate efficiency. In the case of a packed column the height equivalent to a theoretical plate HETP) gives a measure of the contacting efficiency of the packing. 

Sometimes the height equivalent to a theoretical plate (HETP) is employed rather than and to characterize the performance of packed towers. The number of heights equivalent to one theoretical plate required for a specified absorption job is equal to the number of theoretical plates,... 

An alternative to determining packed height is through the use of an empirical term, height equivalent to a theoretical plate (HETP). This term can be measured in a fashion similar to that used for the overall plate efficiency of a column (eq. 44) ... 

HTU (Height Equivalent to One Transfer Unit) Frequently the values of the individual coefficients of mass transfer are so strongly dependent on flow rates that the quantity obtained by dividing each coefficient by the flow rate of the phase to which it apphes is more nearly constant than the coefficient itself. The quantity obtained by this procedure is called the height equivalent to one transfer unit, since it expresses in terms of a single length dimension the height of apparatus required to accomplish a separation of standard difficulty. 

Design data for separation of the particular or similar mixture in a packea column are not available. Design procedures are better estabhshed for tray-type columns than for packed columns. This is particularly so with respect to separation efficiency since tray efficiency can be estimated more accurately than packed height equivalent to a theoretical stage (HETP). 

Height equivalent to a theoretical plate (HETP) plate tower data ... 

A, Gross-sectional area of tower m ft HETS Height equivalent to a m ft... 

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)]. 

HETP height equivalent to theoretical plate, m HTU height equivalent to a transfer unit, m... 

The effective stack height (equivalent to the effective height of the emission) is the sum of the actual stack height, the plume rise due to the exhaust velocity (momentum) of the issuing gases, and the buoyancy rise, which is a function of the temperature of the gases being emitted and the atmospheric conditions. 

Many operating variables, such as sample volume, flow rate, column length, and temperature, must be considered when performing any separation. The relative importance of these variables for Toyopearl HW-55F resin columns has been specifically evaluated. For example. Fig. 4.47 shows the relationship between column efficiency, or height equivalent of a theoretical plate (HETP),... 

Column efficiency (number of theoretical plates) As in batch chromatography, one needs to determine the efficiency of the column in order to evaluate the dispersion of the fronts due to hydrodynamics dispersion or kinetics limitations. The relationship of N proportional to L can be expressed in terms of the equation for height equivalent to a theoretical plate (HETP) as ... 

HETP = height equivalent to a theoretical plate, ft HTU = height of a transfer unit, ft L = liquid mass velocity, Ib/hr-ft m = exponent a 1.0 n = exponent 0.44 Pr = Prandtl number, dimensionless Sc = Schmidt number dimensionless U, = linear velocity of gas based on total column cross-sectional area, ft/sec... 

FP = flow parameter, dimensionless HETP = height equivalent of a theoretical plate, in. 

The HETP (Height Equivalent to a Theoretical Plate (stage or plate)) is the tray spacing divided by the fractional overall tray efficiency [82]. The transfer unit concept has been useful for generalized correlations [89]. Because packed towers operate with continuously changing compositions through the packed height, the concept... 

Commercial preparations of these supports are available in narrow mesh-range fractions to obtain particles of uniform size the material should be sieved to the desired particle size range and repeatedly water floated to remove fine particles which contribute to excessive pressure drop in the final column. To a good approximation the height equivalent of a theoretical plate is proportional to the average particle diameter so that theoretically the smallest possible particles should be preferred in terms of column efficiency. Decreasing particle size will, however, rapidly increase the gas pressure necessary to achieve flow through the column and in practice the best choice is 80/100 mesh for a... 

Height equivalent to a theoretical plate (HETP) A measure of the efficiency of a column usually expressed in millimeters. HETP — LIN, where L is the length of a column and N is the number of theoretical plates. The reciprocal of HETP is also used to describe efficiency and is often expressed by the terms plates per meter. 

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