Distillation and Gas Absorption

Couper, James R.; Penney, W. Roy; Fair, James R.; Walas, Stanley M.

doi:10.1016/b978-0-12-396959-0.00013-6

Cited by 1 publication

(12 citation statements)

References 39 publications

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“…Continuous changes in compositions of phases flowing in contact with each other are characteristic of packed towers, spray or wetted wall columns. The theory of mass transfer between phases and separation of mixtures under such conditions is based on a two‐film theory …”

Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

“…Couper et al . have reported that two special cases are commonly recognized for separations in packed towers: (1) equimolar counter‐diffusion between the phases, as in distillation with McCabe–Thiele approximations and (2) unidirectional diffusion through a stagnant film or boundary layer, as in absorption or stripping processes involving transfer of a single component between liquid and vapor phases.…”

Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

“…The numbers of transfer units (NTU G and NTU L ) for absorption to make up the total packing height are expressed as:

{NTU}_{G} = \int_{y_{1}}^{y_{2}} \frac{1}{(1 - y) In [(1 - y) / (1 - y^{*})]} d y

{NTU}_{L} = \int_{x_{1}}^{x_{2}} \frac{1}{(1 - x) In [(1 - x) / (1 - x^{*})]} d x

and the heights of transfer units (HTU G and HTU L ) are defined as follows:

{HTU}_{G} = (\frac{α {(G^{'})}^{β}}{{((), L^{'})}^{γ}}) {((), \frac{μ_{G}}{r_{G} D_{G}})}^{0.50} = (\frac{α {(G^{'})}^{β}}{{((), L^{'})}^{γ}}) {((), \frac{v_{G}}{D_{G}})}^{0.50}

{HTU}_{L} = ϕ {((), \frac{L^{'}}{μ_{L}})}^{η} {((), \frac{μ_{L}}{ρ_{L} D_{L}})}^{0.50} = ϕ {((), \frac{L^{'}}{μ_{L}})}^{η} {((), \frac{ν_{L}}{D_{L}})}^{0.50}

where the expressions ν G / D G and ν L / D L are the Schmidt numbers in gas phase and liquid phase, and the variables α , β , γ , η and ϕ are packing constants specific to each packing type . For resistance in both phases, the individual HTU values can be combined as follows:…”

Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

“…have reported that the heights of transfer units vary with the type and size of packing material, the flow rates, the distribution of flow across the cross section, and sometimes with the packing height and packed column diameter. The packing materials for the columns are readily available in a variety of shapes and sizes . Modern random packings consist of several engineered shapes intended to maximize surface‐to‐volume ratio and minimize pressure drop by utilizing the transfer unit concept .…”

Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

“…Modern random packings consist of several engineered shapes intended to maximize surface‐to‐volume ratio and minimize pressure drop by utilizing the transfer unit concept . For the multicomponent case, the numbers of overall theoretical stages (NTU OG ), can be obtained experimentally or calculated from several methods including McCabe–Thiele construction, numerical approach and integration of Eqns and . The following equation can also be used for plug flow with A = 1/ λ and E is the removal efficiency:

{((), NTU)}_{italicOG} = A / (A ‐ 1) ln ((A ‐ E) / (A (1 ‐ E)))

…”

Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

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Composite desirability function‐based empirical modeling for packed tower design in physical ammonia absorption

Yetilmezsoy

2011

Asia-Pacific J Chem Eng

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This paper describes two new empiricial models based on the composite desirability function methodology for the prediction of packed column diameter and packing height in solving problems of physical ammonia absorption. The computational analysis including a total of 131 absorption scenarios were conducted for six fundamental operating parameters such as inlet gas flow rate (500–5000 m3/h), solute concentration in the inlet gas (5–10%), desired removal efficiency (87–98%), operating temperature (10–60 °C), percentage of the minimal liquid‐to‐gas flow rates ratio (24–52%) and percent of flooding velocity (30–80%). The ceramic Raschig rings were selected as one of the most common packing types for the present analysis. The column diameter to packing size ratio were considered to be greater than 30 for a total of 500 packing sizes (0.01–5 inches in diameter) included in the numerical cycle. New non‐linear regressions as the functions of packing factor, packing size and various transfer unit constants (α, β, γ, η and ϕ) were implemented in the prediction scheme of the proposed empirical models. The performance of the models was evaluated with various descriptive statistical indicators. The testing results showed that all predictions were proven to be satisfactory with very high determination coefficients of about R2 = 0.997 and R2 = 0.963 for the packed column diameter and required packing height, respectively. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.

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Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

Section: A Brief Theory Of Packed Tower Designmentioning

confidence: 99%

“…The numbers of transfer units (NTU G and NTU L ) for absorption to make up the total packing height are expressed as: