AN EXPERIMENTAL INVESTIGATION INTO THE FOAMING TENDENCY OF DIETHANOLAMINE GAS SWEETENING SOLUTIONS

The foaming tendency of a 30 weight % solution of diethanolamine (DEA) in distilled water was measured over a temperature range of 20-85°C and a pressure range of 1-3 MPa in the presense of a number of contaminants including carboxylic acids, oils, 1-4 bis (2-hydroxyethyl) piperazine (HEP), methanol, iron sulphide, silicone antifoam, etc. The measurements were conducted using a Jerguson high pressure sight glass contained in an air bath. Foaming was measured at gas rates up to 7.5 standard m³/d using air, nitrogen, carbon dioxide, and ethane. One notable observation was that the addition of most of the contaminants commonly identified as foam promoters did not create a foaming system with a clean 30% DEA solution. In fact, the only solutes that produced significant foaming were the carboxylic acids as noted previously in the literature by Pauley et al. (1989). The addition of contaminants to a foaming system did increase foam heights and stability substantially and results are presented for methanol and HEP addition to a foaming system of DEA-carboxylic acid. The effects of temperature, pressure, and gas flow rates on foam heights and foam break times were measured for a number of systems. Foaming was increased by a higher temperature and by higher pressure and was much more pronounced when carbon dioxide or ethane gases were used