Carbon dioxide absorption coefficients

First, the overall mass transfer coefRcient k a of the microreactor was estimated to be 3-8 s [43]. For intensified gas liquid contactors, kj a can reach 3 s while bubble columns and agitated tanks do not exceed 0.2 s Reducing the flow rate and, accordingly, the liquid film thickness is a means of further increasing kj a, which is limited, however, by liquid dry-out at very thin films. Despite such large mass transfer coefficients, gas-liquid microreactors such as the falling film device may still operate between mass transfer and kinetic control regimes, as fundamental simulation studies on the carbon dioxide absorption have demonstrated [44]. Distinct concentration profiles in the liquid, and even gas, phase are predicted. 

Coppock and Meiklejohn (C9) determined liquid mass-transfer coefficients for the absorption of oxygen in water. The value of k, was observed to vary markedly with variations of bubble velocity, from 0.028 to 0.055 cm/sec for a velocity range from 22 to 28 cm/sec. These results appear to be in general agreement with the results obtained by Datta et al. (D2) and by Guyer and Pfister (G9) for the absorption of carbon dioxide by water. 

Cryder and Maloney(40) presented data on the absorption of carbon dioxide in diethanolamine solution, using a 200 mm tower filled with 20 mm rings, and some of their data are shown in Figure 12.14. The coefficient KGa is found to be independent of... 

A comprehensive review of work on the absorption of carbon dioxide by alkaline solutions has been carried out by Danckwerts and Siiarma(43) who applied results of research to the design of industrial scale equipment. Subsequently, Sahay and Sharma(44) showed that the mass transfer coefficient may be correlated with the gas and liquid rates and the gas and liquid compositions by ... 

Thus, when deahng with gas transfer in aerobic fermentors, it is important to consider only the resistance at the gas-liquid interface, usually at the surface of gas bubbles. As the solubihty of oxygen in water is relatively low (cf. Section 6.2 and Table 6.1), we can neglect the gas-phase resistance when dealing with oxygen absorption into the aqueous media, and consider only the liquid film mass transfer coefficient Aj and the volumetric coefficient k a, which are practically equal to and K a, respectively. Although carbon dioxide is considerably more soluble in water than oxygen, we can also consider that the liquid film resistance will control the rate of carbon dioxide desorption from the aqueous media. 

In this study, the solubilities of carbon dioxide were represented by the Bunsen absorption coefficients and their values given in Table I for lithium chloride and in Table II for calcium chloride. The densities of salt solutions are... 

Carbon dioxide. Collision-induced absorption in carbon dioxide shows a discernible density dependence beyond density squared, even at densities as low as 20 amagats [34]. Over a range of densities up to 85 amagats the variation of the absorption with density may be closely represented by a (truncated) virial series (as in Eq. 1.2, with I(v) replaced by a(v)) of just two terms, one quadratic and the other cubic in density. The coefficient of g3 is negative. Relative to the leading quadratic coefficient, it is,... 

The absorption rate of carbon dioxide increases in the presence of amines or ammonia. Therefore, the reaction kinetics of NH3 and C02 has been considered in the model equations, too. The rate constant as a function of the temperature has been determined according to Ref. 136. The coefficients for the calculation of the chemical equilibrium constants in this system of volatile weak electrolytes are taken from Ref. 137. 

The Bunsen absorption coefficient of carbon dioxide in water at 20°C is 0.88. Calculate the solubility of carbon dioxide in water at 20°C and a partial pressure of carbon dioxide of 0.54 atm. 

Perez and Sandall (1974) studied the absorption of carbon dioxide in aqueous carbopol solution. The rheological behavior of the solution was described by the power law model with flow behavior indices varying from 0.91 to 0.59. For an agitated vessel with a turbine impeller, the mass-transfer coefficient across the unbroken interface was correlated as... 

Abstract—Gas-liquid interfacial areas a and volumetric liquid-side mass-transfer coefficients kLa are experimentally determined in a high pressure trickle-bed reactor up to 3.2 MPa. Fast and slow absorption of carbon dioxide in aqueous and organic diethanolamine solutions are employed as model reactions for the evaluation of a and kLa at high pressure, and various liquid viscosities and packing characteristics. A simple model to estimate a and kLa for the low interaction regime in high pressure trickle-bed reactors is proposed. 

The reported study on gas-liquid interphase mass transfer for upward cocurrent gas-liquid flow is fairly extensive. Mashelkar and Sharma19 examined the gas-liquid mass-transfer coefficient (both gas side and liquid side) and effective interfacial area for cocurrent upflow through 6.6-, 10-, and 20-cm columns packed with a variety of packings. The absorption of carbon dioxide in a variety of electrolytic and ronelectrolytic solutions was measured. The results showed that the introduction of gas at high nozzle velocities (>20,000 cm s ) resulted in a substantial increase in the overall mass-transfer coefficient. Packed bubble-columns gave some improvement in the mass-transfer characteristics over those in an unpacked bubble-column, particularly at lower superficial gas velocities. The value of the effective interfacial area decreased very significantly when there was a substantial decrease in the superficial gas velocity as the gas traversed the column. The volumetric gas-liquid mass-transfer coefficient increased with the superficial gas velocity. 

Saada25 measured the gas liquid mass-transfer coefficients for absorption of carbon dioxide into NaOH solutions for cocurrent upflow. Goto et al.8 evaluated the liquid-gas mass-transfer coefficients for the desorption of oxygen from water into nitrogen in a 2.58-cm-i.d. glass tube packed with CuO-ZnO particles... 

The Rectisol process [667], [707], [711]-[715] seems to be the prime choice in partial oxidation plants. The process, invented by Lurgi and developed further by Linde, operates with chilled methanol, a cheap and readily available solvent, in which carbon dioxide, hydrogen sulfide and carbonyl sulfide (COS) are readily soluble at low operating temperatures of below - 30 °C. The Henry absorption coefficient for H2S is about six times higher than for C02-... 

In 1896 he made the first quantitative link between changes in carbon dioxide concentration and climate. He calculated the absorption coefficients of carbon dioxide and water based on the emission spectrum of the moon, and he also calculated the amount of total heat absorption and corresponding temperature change in the atmosphere for various concentrations of carbon dioxide. His prediction of a doubling of carbon dioxide from a temperate rise of 5-6°C is close to modern pre-... 

The major absorption bands occurring in CO2 in the infrared are at 2.7, 4.3, 15, and 100 /X [10, 11], These bands are so narrow and weak that solid CO2 can be considered to be highly transparent in the infrared. The data on solid CO2 films shown in Fig, 4 are consistent with a model of a film with an absorption coefficient with little wavelength dependence and a vacuum-carbon dioxide film reflection coefficient of 0.10. 

A filler such as titanium dioxide, having a refractive index much higher than that of the polymer, will therefore exhibit considerable scattering and will give white products, unless its absorption coefficient is high in which case dark, opaque composites will be produced (carbon black or black iron oxide are the ultimate in this instance). 

---