Absorption material balance

Whether for a distillation, absorption, or stripping system the material balance should be established around the top, bottom, and feed sections of the column. Then, using these liquid and vapor rates at actual flowing conditions, determine the flooding and maximum operating points or conditions. Then, using Figures 9-21B, -21E, or -21F, establish pressure drop, or assume a pressure drop and back-calculate a vapor flow rate, and from this a column diam-... 

In many applications of mass transfer the solute reacts with the medium as in the case, for example, of the absorption of carbon dioxide in an alkaline solution. The mass transfer rate then decreases in the direction of diffusion as a result of the reaction. Considering the unidirectional molecular diffusion of a component A through a distance Sy over area A. then, neglecting the effects of bulk flow, a material balance for an irreversible reaction of order n gives ... 

A reactive absorption is done in a countercurrent packed tower. The material balance is made in terms of solute-free quantities. Inlet conditions are X2 = 0, Yx - 0.5 outlet Xx =0.8, Y2 = 0.1. Bottom is 1, top is 2. 

Material balance. To produce 1000 kg of cyclonite, 833 kg of hexamine and 8779 kg of HN03 are required 3482 kg of dilute 55% HN03 are recovered plus 3429 kg of HN03 from the absorption towers. Thus the net consumption of HN03 for nitration is 1868 kg. In addition, 490 kg of H2S04 are used for the concentration of HN03. 

Figure 13.15. Mechanism, nomenclature, and constructions for absorption, stripping and distillation in packed towers, (a) Two-film mechanism with equilibrium at the interface, (b) Sketch and nomenclature for countercurrent absorption or stripping in a packed tower, (c) Equilibrium and material balance lines in absorption, showing how interfacial concentrations are found, (d) Equilibrium and material balance lines in stripping, showing how interfacial concentrations are found, (e) Equilibrium and material balance lines in distillation, showing how interfacial concentrations are found.

For a dilute gas, and when the equilibrium curve can be approximated by a linear relationship passing through the origin, Eq. (25) is applicable, and an average absorption factor A can be applied to describe the contactor. Under these conditions, an analytical solution of the material balance equation and the equilibrium relationship is possible, giving the Kremser equation ... 

The material balances for an absorption column is normally set up per unit cross-sectional area, i.e. 

Note that the material balances for an absorption column are normally written on a solute-free basis (the solute is the component being absorbed). In other words, we give the flow rates in terms of the components which are not being absorbed. This makes the calculations easier as the solute-free flow rates of both gas and liquid in or out of the column are constant. 

In addition, most situations that involve mass transfer require material balances, but the pertinent area is ambiguous. Examples are packed columns for absorption, distillation, or extraction. In such... 

In the analysis of Ramchandran and Sharma,139 it was assumed that the solid dissolution process increases the absorption rate of the gaseous reactant. If we consider another case, where the rate of dissolution of the solid is also enhanced by the reaction between the absorbed gas and the dissolved solid species in the liquid film between x = 0 and x = A, then the material balance for the diffusing gas for 0 < x < A is given by the following equation ... 

Figure 116. Ammonia production based on heavy fuel oil (l.inde flow scheme with Texaco gasification) a) Air separation unit h) Soot extraction c) C02 absorption d) Methanol/H,() distillation e) Stripper f) Mol regenerator g) Refrigerant h) Dryer i) liquid N2 scrubber j) Syngas compressor k) Nil, reactor Material Balance...

SEPARATION COLUMNS (DISTILLATION, ABSORPTION AND EXTRACTION) Material balance... 

Material balance calculations on separation processes follow the same procedures used in Chapters 4 and 5. If the product streams leaving a unit include two phases in equilibrium, an equilibrium relationship for each species distributed between the phases should be counted in the degree-of-freedom analysis and included in the calculations. If a species is distributed between gas and liquid phases (as in distillation, absorption, and condensation), use tabulated vapor-liquid equilibrium data, Raoult s law, or Henry s law. If a solid solute is in equilibrium with a liquid solution, use tabulated solubility data. If a solute is distributed between two immiscible liquid phases, use a tabulated distribution coefficient or equilibrium data. If an adsorbate is distributed between a solid surface and a gas phase, use an adsorption isotherm. 

---