Chemical Processing - July 2008 - (Page 26) Liquid in 100 0 20 40 54 60 84 80 Condensate Condensate valve position, % a simple solution TC regardless of whether the control valve is on the steam TT supply or the condensate. Steam However, the consequences of attempts to exceed the maximum are very different. The exchanger in Figure 1 has the potential to “blow steam” into < LC LT the condensate return system. As the control valve opens, the condensate level within the exchanger drops. If the valve is opened too much, the level drops entirely out of the exchanger and steam flows into the condensate return system, a somewhat unpleasant situation. Both operating lines in Condensate terminate at a Figure 2 liquid outlet temperature of 288°F. At this point, the exchanger is completely drained of condensate and the entire tube area is exposed to condensing steam. Figure 2 suggests that this 300 occurs at a valve opening 288 of 54% for the linear valve and 84% for the equal-perLinear valve centage valve. What about260 openings greater than valve Liquid out these values? In practice, the liquid outlet temperature 220 usually drops. When the exchanger blows steam, the shell pressure usually drops below the steam supply 180 pressure, giving a lower liquid outlet temperature. TC Steam TT Liquid out Liquid out Figure 3. Adding a steam trap to the condensate line keeps the exchanger from blowing steam. T Liquid in Liquid in Condensate Heat transfer Liquid outlet temperature, °F Theoretically, the minimum heat transfer rate is zero. With the control valve closed, the exchanger TT TC completely fills with condensate, resulting in no heat transfer. Steam The maximum heat transfer occurs when the exchanger is completely drained of condensate. The value for the maximum heat transfer rate is the same, 140 Equal-percentage valve LC LT Condensate Liquid in 100 0 20 40 44 60 78 80 Condensate valve position, % Condensate Expand Your World of Automation The 2008 Siemens Automation Summit - A U ser s Co nfe re nce Chicago, IL | July 23 – 25, 2008 w w w. s e a . s i e m e n s / s u m m i t Grounded by conventional wisdom? http://www.sea.siemens/summit
Table of Contents Feed for the Digital Edition of Chemical Processing - July 2008 Chemical Processing - July 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Who’s a Big Hit? Succeed with Condensate Control Take Some Basic Steps with pH Measurements Steam Projects Provide Fast Payback Process Puzzler Plant InSites Equipment & Services Product Spotlight/Classifieds/Ad-Lits Ad Index End Point Chemical Processing - July 2008 Chemical Processing - July 2008 - Chemical Processing - July 2008 (Page Cover1) Chemical Processing - July 2008 - Chemical Processing - July 2008 (Page Cover2) Chemical Processing - July 2008 - Chemical Processing - July 2008 (Page 3) Chemical Processing - July 2008 - Chemical Processing - July 2008 (Page 4) Chemical Processing - July 2008 - Contents (Page 5) Chemical Processing - July 2008 - Contents (Page 6) Chemical Processing - July 2008 - From the Editor (Page 7) Chemical Processing - July 2008 - From the Editor (Page 8) Chemical Processing - July 2008 - ChemicalProcessing.com (Page 9) Chemical Processing - July 2008 - ChemicalProcessing.com (Page 10) Chemical Processing - July 2008 - Field Notes (Page 11) Chemical Processing - July 2008 - In Process (Page 12) Chemical Processing - July 2008 - In Process (Page 13) Chemical Processing - July 2008 - In Process (Page 14) Chemical Processing - July 2008 - Energy Saver (Page 15) Chemical Processing - July 2008 - Energy Saver (Page 16) Chemical Processing - July 2008 - Compliance Advisor (Page 17) Chemical Processing - July 2008 - Who’s a Big Hit? (Page 18) Chemical Processing - July 2008 - Who’s a Big Hit? (Page 19) Chemical Processing - July 2008 - Who’s a Big Hit? (Page 20) Chemical Processing - July 2008 - Who’s a Big Hit? (Page 21) Chemical Processing - July 2008 - Who’s a Big Hit? (Page 22) Chemical Processing - July 2008 - Who’s a Big Hit? (Page 23) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 24) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 25) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 26) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 27) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 28) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 29) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 30) Chemical Processing - July 2008 - Succeed with Condensate Control (Page 31) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 32) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 33) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 34) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 35) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 36) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 37) Chemical Processing - July 2008 - Take Some Basic Steps with pH Measurements (Page 38) Chemical Processing - July 2008 - Steam Projects Provide Fast Payback (Page 39) Chemical Processing - July 2008 - Steam Projects Provide Fast Payback (Page 40) Chemical Processing - July 2008 - Process Puzzler (Page 41) Chemical Processing - July 2008 - Plant InSites (Page 42) Chemical Processing - July 2008 - Plant InSites (Page 43) Chemical Processing - July 2008 - Equipment & Services (Page 44) Chemical Processing - July 2008 - Equipment & Services (Page 45) Chemical Processing - July 2008 - Product Spotlight/Classifieds/Ad-Lits (Page 46) Chemical Processing - July 2008 - Product Spotlight/Classifieds/Ad-Lits (Page 47) Chemical Processing - July 2008 - Product Spotlight/Classifieds/Ad-Lits (Page 48) Chemical Processing - July 2008 - Ad Index (Page 49) Chemical Processing - July 2008 - End Point (Page 50) Chemical Processing - July 2008 - End Point (Page Cover3) Chemical Processing - July 2008 - End Point (Page Cover4)
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