W h e n a gaseous component is absorbed by a liquid under simultaneous reaction with a component of the liquid, the overall rate of reaction proves to be a dimensionless function of four limiting rates: a. the maximum rate of diffusion of the gaseous component through the liquid film b. the maximum rate of diffusion of the liquid-component through the liquid film c. the limiting rate of reaction within the liquid film (during diffusion) d. the maximum rate of reaction within the main body of the liquid.
Vapour pressures of aqueous solutions containing ammonia and carbon dioxide, ammonia and hydrogen sulphide or ammonia, carbon dioxide and hydrogen sulphide, have been determined at temperatures from 20‐60° C. Dissolved hydrogen sulphide is present almost completely in the form of ammonium hydrosulphide. Dissolved carbon dioxide is present in the form of carbonate, bicarbonate and carbamate of ammonium.
The experimental vapour pressure data are interpreted from the viewpoint of the ionic equilibria in the solutions. The numerical values of the equilibrium constants have been derived.
A method is described enabling one to calculate the vapour pressure for arbitrary compositions of the solutions.
Diagrams are given for the vapour pressures of the two‐component system ammonia‐carbon dioxide, as a function of the total ammonia content and the ratio R (= total carbon dioxide/total ammonia). From these diagrams also the vapour pressures of the three‐component system ammonia‐carbon dioxide‐hydrogen sulphide can be derived approximatively.
Granules of wet marl, suspended from the beam of a torsion balance, were dried in a current of dry air. Two rate periods were observed; during the first the rate of drying remains constant, during the second it decreases. With the aid of the conception of Ceaglske and Hougen on moisture distribution in granular materials equations for the rate of drying during the second stage could be derived which arc proved to be in agreement with the experiments. Besides these theoretical equations dimensionless empirical expressions were derived for the two drying stages which enable the rate of drying of single granules under arbitrary conditions to be calculated.Granules of nitrochalk fertilizer, when dried in the same apparatus, showed quite a different behaviour. At first the rate of drying decreased rapidly and soon reached a constant value. This constant rate was over a thousand times smaller than the rate of drying in the case where mass transfer through the gas film is rate determining. The rapid decrease of the drying me at the start could be ascribed to n filling of the pores by solid ammonium nitrate. As soon as the rate became constant drying took place exclusively by diffusion of water vapour through a thin crystal film which had an average thickness of 10‐3 to 10‐5 cm. In this period the rate of drying was only influenced by temperature and by size and structure of the granule.
A dimensionless equation has been derived for the mass transfer coefficient in the liquid phase (k1) both for physical and chemical absorption.
The equation can be written:
where the dimensionless groups2) have the following significance:
When the absorption is purely physical the group Ha has the value of 1. The equation is checked with the available data in the literature and those from experiments by the authors.
The “constant” c seems to depend on the relation: \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm diameter}\,{\rm of}\,{\rm packing}}}{{{\rm height}\,{\rm of}\,{\rm scrubber}}} $\end{document}; the function can be approximated by the formula:
The equation derived resembles the non‐dimensionless equation of Sherwood and Holloway3) (for physical absorption).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.