Simulation of packed distillation and absorption columns

Abstract

A nonequilibrium stage model of countercurrent separation processes is used to model a packed distillation column and a packed absorber. A key feature of the model Is that the component material and energy balance relations for each phase are solved simultaneously with the mass and energy transfer rate equations and interface equilibrium equations. Computations of quantities such as HETP and HTU are completely avoided. The terminal stream composition, flow rates, and temperature profiles over the packed depth predicted by the model are compared with results of field tests. There is good agreement between the two; the deviations are only of the order of magnitude of the experimental errors.

Simulation and Optimization of the Waste Nitric Acid Recovery Process

“…Krishnamurthy and Taylor (1985) presented a nonequilibrium model based on heat and mass transfer between liquid and vapor phases and the equilibrium relationship in the interface. Krishnamurthy and Taylor (1985) presented a nonequilibrium model based on heat and mass transfer between liquid and vapor phases and the equilibrium relationship in the interface.…”

“…In one method the continuous contacting area of the packed column is divided into many subdivisions and each of them is considered as a tray (Holland, 1975). Krishnamurthy and Taylor (1985) presented a nonequilibrium model based on the former method which employed mass and energy transfers at liquid and vapor phases as well as interfacial equilibrium relations. Krishnamurthy and Taylor (1985) presented a nonequilibrium model based on the former method which employed mass and energy transfers at liquid and vapor phases as well as interfacial equilibrium relations.…”

Evaluation of the column components size on the vapour enrichment and system performance in small power NH3–H2O absorption refrigeration machines

“…The Murphree efficiency used with the height equivalent to a theoretical plate concept (HETP) [5] has been widely used to determine the packed height. Though this method can give results that are not in good agreement with experiments [6]. Design procedures based on the height of a transfer unit (HTU) and the related number of transfer units (NTU) can [7], since HTU can be correlated more easily than HETP.…”

“…More recent models for packed columns take into account both the mass and heat transfer resistances of the liquid and vapour phases and are based on the classical twofilm theory of Lewis and Whitman [8]. In these models the column (or any continuous contact device) is either divided in sections where mass and energy balances and heat and mass transfer equations are applied [6,9] or differential equations are used which are solved by a numerical integration scheme [10,11]. Recently, the differential method approach has been used by Fernández-Seara et al [12] to simulate the distillation of the ammonia-water mixture in a packed column.…”

Ein allgemeines Simulationsprogramm zur Berechnung verfahrenstechnischer Prozesse

“…austausches 1aBt eine verbesserte Beschreibung erwarten [3]. Der Rechenaufwand wird hierdurch jedoch erhoht, was sich insbesondere bei der dynamischen Berechnung auswirken wird.…”