Foamability and foam stability at high pressures and temperatures. I. Instrument validation

An instrument was designed and assembled with the aim of measuring macroscopic properties of foams (such as foamability and stability) under high pressures and moderate temperatures (up to 105 bar and 425 K, respectively). The device makes use of infrared sensors to detect the foam forefront position as it is generated by gas sparging in the foaming solution. The measurement makes use of a modified dynamic Bikerman protocol to estimate the foamability and stability of the studied solution. Traditional direct observation used in foam experiments at ambient conditions is therefore circumvented and the instrument can be set up in an appropriate place and monitored remotely so as to reduce the risks involved in high-pressure, high-temperature operations. Data from the infrared system allows not only following the dynamics of foam phenomena but also the relative foam quality along the column, and the presence of air pockets in the case of unstable or pulsating foams. A series of fluorosurfactants (cationic, anionic, and nonionic) were used to validate the instrument and the effect of temperature on foamability, foam stability and foam quality is discussed. Finally, synergistic effects were observed with respect to the foam behavior of different mixtures of the studied surfactants. (C) 2003 American Institute of Physics.