Bubble‐point measurements in the ammonia‐carbon dioxide system

Abstract

Abstract The bubble‐point pressures in the NH 3 ‐CO 2 system, at complete chemical equilibrium, have been measured in the range of 130–185°c corresponding to pressures of 30–175 atm. The NH 3 ‐CO 2 system exhibits a sharp pressure minimum; in the area of high NH 3 concentration, critical behaviour and retrograde condensation have been found. The results, as part of the NH 3 ‐H 2 O‐CO 2 system, are discussed from the standpoint of chemical phase theory and are shown to be consistent with the NH 3 ‐H 2 O and CO 2 ‐H 2 O systems. The relation of these measurements to the commercial urea synthesis is also discussed.