The coexistence of equilibrium phases depends on the system pressure and temperature as follows:Ī. Ethane vapor phase in equilibrium with liquid waterī. Ethane vapor phase in equilibrium with ice or hydrateĬ. Ethane liquid phase in equilibrium with liquid waterĭ. Ethane liquid phase in equilibrium with hydrateįigure 1 illustrates the presence of these equilibrium phases as a function of temperature for the isobar of 200 psia (1379 kPa). The propane water content was estimated by the following procedures.Ī. For temperatures of 200 ☏ to about 47.5 ☏ (93 to ~ 8.6 ☌), the ethane vapor is in equilibrium with liquid water phase so the water saturator tool of ProMax was used.ī. For temperatures of about 47.5 ☏ to -6 ☏ (~ 8.6 to -21.1 ☌), the ethane vapor was in equilibrium with the hydrate phase, so one mole of pure ethane stream was mixed with a pure water stream atpressure of 200 psia (1379 kPa). Pressure adjustment summary for pressure higher than 496 psia (3420.7 kPa) The summary of results for the adjusted pressures is presented in Table 2.
The calculated pressure was increased slightly, i.e. For a binary system of 50–50 mole % ethane–water, at the specified temperature and 0 % vapor the pressure was calculated.Ģ. Table 1 indicates that even the ethane water contents are very low (from 2 to 733 ppm by mole), the average absolute percent deviations are relatively low and are from 11 to 18.5 %.įor pressures higher than 496 psia (3421 kPa), to form liquid ethane and liquid water (L HC-L W) phases at equilibrium, the experimental pressures reported in Table 1 were adjusted as follows:ġ. For these set of pressures and temperatures, all three methods give relatively good results. The SRK EOS (Soave-Redlich-Kwong equation of state) with its ProMax default binary interaction parameters were used. See below for detail of pressure adjustment. * The pressure in parenthesis are the experimental values which were adjusted to form liquid ethane. Table 1. Comparison of vapor or liquid ethane water content (PPM by mole) in equilibrium with liquid water or hydrate by ProMax against the GPA-RR 132 experimental data ►ProMax 3: Water content was estimated by performing flash calculations for a binary system of 50–50 mole % ethane–water at system pressure and temperature. To determine the water content of the mixed stream, the solver tool of ProMax was used to adjust the pure water stream flow rate to match the system temperature. ►ProMax 2: One mole of pure ethane stream was mixed with a pure water stream at the desired pressure. ►ProMax 1: Water content was estimated using a water saturator tool. These three methods are labeled and described as follows: Three methods within ProMax were utilized. A summary of water content comparisons for ethane vapor (G) or liquid (L HC) in equilibrium with hydrate (H) and liquid water (L W) is presented in Table 1. The performance of the ProMax simulation software, for estimating the water content of ethane in equilibrium with hydrate or liquid water was evaluated against limited GPA RR 132 experimental data. For each isobar a temperature range of -60 ☏ to 200 ☏ (-51 ☌ to 104 ☌) is covered.Įvaluation of the Water Content Prediction Methods Second, the tip studies the effect of pressure and temperature on the ethane water content in equilibrium with liquid water, ice, or hydrate phase.
In this tip, we will evaluate the accuracy of water content predicted by a process simulation software against limited measured experimental data. At lower temperatures, ice or hydrates is formed. Very low mutual solubility in liquid phases.Ģ. Like propane–water system, the ethane–water system is complicated for the following two reasons:ġ. Continuing the September 2018 tip of the month (TOTM), the phase behavior of ethane and water binary system was studied.