Experimental low temperature water content in gaseous methane, liquid ethane, and liquid propane in equilibrium with hydrate at cryogenic conditions

In low temperature gas processing, the presence of water can result in the formation of gas hydrate plugs. To avoid this problem, it is important to know the water solubility in natural gas components in equilibrium with gas hydrate. In this study experimental measurements of water content in gaseous methane in equilibrium with hydrate at 3.45 MPa (500 psia) and 6.90 MPa (1000 psia) and temperatures ranging from -3.2 degreesC (26.2 degreesF) to -80 degreesC (- 112 degreesF) are presented. Similar measurements are presented for liquid ethane at 3.45 MPa (500 psia) and temperatures from -2.2 degreesC (28.0 degreesF) to -70 degreesC (-94 degreesF), and for liquid propane at 0.86 MPa (125 psia) and temperatures down to -60 degreesC (-76degreesF), respectively. In measuring the water content, a Panamettics moisture sensor (calibrated to 1 ppb water content in nitrogen) has been used in flowing streams of the hydrocarbon-rich phases that are saturated with water. The results obtained with the Panametrics hygrometer show good agreement (normally better than 4%) with previous measurements, which were obtained by a gas chromatographic technique for methane, ethane, and propane at temperatures ranging from -2.0degreesC (28.4degreesF) to -30degreesC (-22degreesF), which are within the hydrate region. (C) 2004 Elsevier B.V. All rights reserved.