Gas absorption with reaction

Sada, E., Kumazawa, H. and Butt, M.A., 1977. Single gas absorption with reaction in a slurry containing fine particles. Chemical Engineering Science, 32, 1165-1170. 

In case (1), the reaction is used for the removal of an undesirable substance from a gas stream. In this sense, the process is commonly referred to as gas absorption with reaction. Examples are removal of H2S or CO, from a gas stream by contact with an ethanolamine (e g., monoethanolamine (MEA) or diethanolamine (DEA)) in aqueous... 

Enhanced surfactant flooding, 23 532 Enhancement factor, gas absorption with reaction, 1 47-48 Enhancement programs, aquatic organisms, 3 183, 198 Enhancement reagents, 12 102 Enhancer, 10 688 Enichem oxo-alcohols, 17 725 Enkaid, molecular formula and structure, 5 92t... 

Example 143.d-I Gas Absorption with Reaction in a Plate Column... 

F. Gas Absorption with Chemical Reaction—Time-Dependent Bulk Concentration. 346... 

Burning of coal Roasting of ores Attack of solids by acids Gas-liquid absorption with reaction Reduction of iron ore to iron and steel... 

The nitrous gas absorption step (reactions 9.13 and 9.14) is slow, especially if concentrated HN03 is required, since cooling to 2°C is then necessary. Consequently, large countercurrent towers of stainless steel are needed, with associated high capital cost. The recovery of the heat of reaction of this step is inefficient because of the low temperature of the source gases that must be maintained. It has been suggested that the energy of reaction 9.12 could be more effectively recovered if it is run in a fuel cell (see Exercise 15.8). 

Figure 6.3a shows the idealized sketch of concentration profiles near the interface by the 1 latta model, for the case of gas absorption with a very rapid second-order reaction. The gas component A, when absorbed at the interface, diffuses to the reaction zone where it reacts with B, which is derived from the bulk of liquid by diffusion. Ihe reaction is so rapid that it is completed within a very thin reaction zone this can be regarded as a plane parallel to the interface. The reaction product diffuses to the liquid main body. The absorption of CO2 into a strong aqueous KOH solution is close to such a case. Equation 6.21 provides the enhancement... 

Figure 6.3 Gas absorption with chemical reaction (a) rapid second-order reaction and (b) slow pseudo first-order reaction.

Hikita H, Asai S. Gas absorption with (m, ri)-th order irreversible chemical reactions. Int Chem Eng 1964 4 332-340. 

Scala, F. (2002). Gas absorption with instantaneous irreversible reaction in a slurry containing sparingly soluble fine reactant particles, IEC Research, 41 5187-5195. 

Exothermic Gas Absorption with Complex Reaction Sulfonation and Discoloration in the Absorption of Sulfur Trioxide in Dodecylbenzene... 

Many processes of gas absorption with chemical reaction are set up at high pressures, result of technical and/or economical requirements. That is, for example, processes of hydrocracking and hydrorefining of heavy oils and processes of oxydation of liquid effluents. However, if many chemical systems are found to determine the mass transfer parameters in an industrial reactor at atmospheric pressure by using the chemical method, they become scarce at elevated pressures. Several physical and chemical methods have been proposed chemical methods present some severe drawbacks, since one has to replace the gas-liquid system of interest by another one, presenting different physical properties (specially a different coalescence behaviour). 

In a previous work ( 5), the film theory was used to analyze special cases of gas absorption with an irreversible second-order reaction for the case involving a volatile liquid reactant. Specifically, fast and instantaneous reactions were considered. Assessment of the relative importance of liquid reactant volatility from a local (i.e., enhancement) and a global (i.e., reactor behavior) viewpoint, however, necessitates consideration of this problem without limitation on the reaction regime. 

Shah158 analyzed gas absorption with a first-order chemical reaction, assum-... 

To describe gas absorption with simultaneous chemical reaction, the film theory will be used for purposes of illustration, because the predictions based on the three models are quite similar (except in regard to the effect of solute gas and reactant diffusivities on the rate of absorption). 

In the overall picture, different expressions are proposed for the rate of gas absorption with chemical reaction, depending on the forms of the enhancement factor E corresponding to different kinetic regimes, going from reaction-controlling to mass transfer-controlling. Typical cases are ... 

Multiphase Reactors Reactions between gas-liquid, liquid-liquid, and gas-liquid-solid phases are often tested in CSTRs. Other laboratory types are suggested by the commercial units depicted in appropriate sketches in Sec. 19 and in Fig. 7-17 [Charpentier, Mass Transfer Rates in Gas-Liquid Absorbers and Reactors, in Drew et al. (eds.), Advances in Chemical Engineering, vol. 11, Academic Press, 1981]. Liquids can be reacted with gases of low solubilities in stirred vessels, with the liquid charged first and the gas fed continuously at the rate of reaction or dissolution. Some of these reactors are designed to have known interfacial areas. Most equipment for gas absorption without reaction is adaptable to absorption with reaction. The many types of equipment for liquid-liquid extraction also are adaptable to reactions of immiscible liquid phases. 

Holroyd and Kenney argued that if the overall reaction could be described by a mechanism of this type, it should be possible to study some of the individual steps by adopting the techniques for investigating gas absorption with the chemical reactions developed for aqueous systems. The rate of absorption of sulphur dioxide was found to be proportional to (S02)(V20s) the rate of oxygen absorption into a partially reduced melt, assuming the vanadium is present only as and is proportional to (02)° (V ) . The implications of these types of measurements are discussed below. 

---