{"id":1521,"date":"2005-11-01T10:35:42","date_gmt":"2005-11-01T16:35:42","guid":{"rendered":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/?p=1521"},"modified":"2012-12-07T11:16:31","modified_gmt":"2012-12-07T17:16:31","slug":"selecting-the-correct-phase-envelope","status":"publish","type":"post","link":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/2005\/11\/selecting-the-correct-phase-envelope\/","title":{"rendered":"Selecting the Correct Phase Envelope"},"content":{"rendered":"

In a previous \u201cTip of the Month\u201d we discussed several methods of heavy ends characterization and as an example, for a rich natural gas, we tuned the heavy end parameters to match the experimentally measured saturation pressure. After tuning the heavy end parameters, we obtained a phase envelope for each method that passed through the experimental dew point; however, their shapes and specifically, their cricondentherm points were different. At the end, we were faced with the question of \u201cwhich one is the right phase envelope?\u201d<\/p>\n

In this tip, we will explain a procedure for selecting an appropriate C6+<\/sub> characterization method which results in a broader match with the experimental information. For further detail, please refer to Gas Conditioning and Processing, Volume 3, Advanced Techniques and Applications.<\/p>\n

Let\u2019s consider a lean natural gas with the composition shown in the first two columns of Table 1. This lean gas contains only 0.067 mol% C6+<\/sub> and even though the amount of C6+<\/sub> is very small, we will see that it has a large impact on the condensate. The detail laboratory analyses [1] of C6+<\/sub> are shown in the 1st<\/sup> and 2nd<\/sup> columns of Table 1. We used the SRK EoS in GCAP Software for Vol. 3 of Gas Conditioning and Processing and determined the C6+<\/sub> properties of MW=94.12, SG=0.738, andNBP=195 \u00b0F. All other calculations were performed using theSRK EoS.<\/p>\n

Table 1. Characterization\/Distribution of C6+<\/sub> by different methods<\/strong><\/p>\n

\"\"<\/a><\/p>\n

We have plotted the experimentally measured Potential Hydrocarbon Liquid Condensed (PHLC) at 594.7 psia as a function temperature in Figure 1, and by extrapolation, a dew point temperature of 52.1 \u00b0F was obtained. We used the methods discussed in the previous tip of the month to characterize the C6+<\/sub> by matching the experimentally determined dew point. For each method, we have presented the tuned<\/span> MW and distribution of components in Table 1 and the predicted PHLC as a function of temperature and the phase envelope were plotted in Figures 1 and 2, respectively. It should be pointed out that the cricondentherm for the lumped C6+<\/sub> method was below 15 \u00b0F; therefore, zero values for PHLC were predicted.<\/p>\n

\"\"<\/a><\/p>\n

Figure 2 indicates that three of the characterization methods practically generate the same phase envelope. Are all of these phase envelopes presenting the true phase behavior of this lean gas? The answer is \u201cYes\u201d and \u201cNO\u201d. Figure 1 indicates that, for temperatures close to the dew point, all three methods predict the PHLCs very close to the experimental values; however, at lower temperatures (about 20 \u00b0F) the deviation from experimental values increases. Only the normal alkane distribution method gives accurate values even at lower temperatures.<\/p>\n

In summary, for sound process design and\/or operation we suggest using at least one experimental saturation measurement such dew point or bubble point near the potential operating conditions to characterize the heavy ends. Once the characterization is established, additional experimental measurements should be utilized to verify the accuracy and validity of the tuning technique.<\/p>\n

\u00a0<\/strong><\/p>\n

By: Dr. Mahmood Moshfeghian<\/em><\/p>\n

\"\"<\/a><\/p>\n

Reference:<\/strong><\/p>\n

    \n
  1. Derks, P. A. H., van der Meulen-Kuijk, L., and Smit, A. L. C., \u201cDetailed Analysis of Natural Gas for an Improved Prediction of Condensation Behavior,\u201d Proceedings, 72nd<\/sup> Annual Convention, Gas Processors Association, 1993.<\/li>\n
  2. Riazi, M.R. and T.E. Daubert, Hydr. Proc. P. 115, (March) 1980<\/strong><\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

    In a previous \u201cTip of the Month\u201d we discussed several methods of heavy ends characterization and as an example, for a rich natural gas, we tuned the heavy end parameters to match the experimentally measured saturation pressure. After tuning the heavy end parameters, we obtained a phase envelope for each method that passed through the […]<\/p>\n","protected":false},"author":23,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[3],"tags":[],"coauthors":[15],"class_list":["post-1521","post","type-post","status-publish","format-standard","hentry","category-gas-processing"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1pQc4-ox","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts\/1521","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/users\/23"}],"replies":[{"embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/comments?post=1521"}],"version-history":[{"count":2,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts\/1521\/revisions"}],"predecessor-version":[{"id":1621,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts\/1521\/revisions\/1621"}],"wp:attachment":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/media?parent=1521"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/categories?post=1521"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/tags?post=1521"},{"taxonomy":"author","embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/coauthors?post=1521"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}