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3 A Papermachine Steam Systems Part1


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3 A Papermachine Steam Systems Part1

  1. 1. <ul><li>Paper Machine Steam Systems </li></ul><ul><li>Session 4 </li></ul>Energy Management Seminar , Ho Chi Minh City, May 2008
  2. 2. PAPER INDUSTRY <ul><li>Classification of paper mills </li></ul><ul><li>Terminology </li></ul><ul><li>Steam & Condensate System </li></ul><ul><li>Rotary Joints & Syphons </li></ul>
  3. 3. CLASSIFICATION <ul><li>Based on Raw Material Used </li></ul><ul><ul><li>Agro Based </li></ul></ul><ul><ul><ul><li>Rice, Wheat Straw, Husk, Jute </li></ul></ul></ul><ul><ul><li>Recycled Based </li></ul></ul><ul><ul><ul><li>Recycled Paper </li></ul></ul></ul><ul><ul><li>Integrated Pulp & Paper Mill </li></ul></ul><ul><ul><ul><li>Hardwood & Softwood </li></ul></ul></ul>IN PAPER MILLS
  4. 4. TERMINOLOGY <ul><li>GSM – Grams per meter square of paper produced </li></ul><ul><ul><li>Typical GSM for different papers </li></ul></ul>IN PAPER MILLS Paper Type GSM Tissue/Towels 9-40 Newsprint 45-48 Writing Printing 40-80 Kraft 90-220 Board Paper 200-600
  5. 5. TERMINOLOGY <ul><li>Draw Rate </li></ul><ul><ul><li>Kgs of paper drawn per unit time </li></ul></ul><ul><ul><li>Normally measured in Kg/hr </li></ul></ul><ul><ul><li>Draw Rate (Kg/Hr) </li></ul></ul><ul><ul><li>= GSM x 10 -3 x Paper Width x mpm x 60 </li></ul></ul><ul><ul><li>… .mpm = meters per minute </li></ul></ul>IN PAPER MILLS
  6. 6. TERMINOLOGY <ul><li>Drying Rate </li></ul>Rate at which water is removed from dryer per unit area per hour = <ul><li>DR = M evap / Area </li></ul><ul><li>= M evap / (  * D * L * n) </li></ul><ul><li>… DR = Drying Rate Kg/Hr-m 2 </li></ul><ul><li>… D = OD of drying cylinder - m </li></ul><ul><li>… L = Cylinder Length - m </li></ul><ul><li>… n = No. of cylinders </li></ul>IN PAPER MILLS
  7. 7. TERMINOLOGY <ul><ul><li>Typical Drying Rates Observed </li></ul></ul><ul><ul><li>(in Indian scenario, for reference only) </li></ul></ul>IN PAPER MILLS Paper Quality DR – Kg/hr-m 2 Tissue 20 Writing Printing 18-20 Craft 15-20 Newsprint 20-25
  8. 8. TERMINOLOGY <ul><li>Specific Steam Consumption </li></ul>IN PAPER MILLS Specific Steam Consumption Kg of Steam -------------------------------- Kg of water Evaporated Kg of Steam -------------------------------- Kg of Paper Drawn Theoretical Approach Practical Approach
  9. 9. TERMINOLOGY <ul><li>Specific Steam Consumption </li></ul><ul><ul><li>Theoretical Value : 1.13 </li></ul></ul><ul><ul><li>TAPPI standard : 1.3 </li></ul></ul><ul><ul><li>(For all grades) </li></ul></ul><ul><ul><li>In India : 1.6-1.8 </li></ul></ul>IN PAPER MILLS Kg of Steam Kg of Water Evaporated 2) Kg of Steam Kg of Paper Drawn * Values are for reference only Depends on moisture 1) Newsprint 1.8-1.9 * Wr/Pr 1.6-1.9 * Kraft 1.75-1.9 * Paper Board 2.1-2.3 * Tissue 2.5-2.6 *
  10. 10. FORMULAE <ul><li>Basic Formula for Calculating Mass of water evaporated: </li></ul>M evap M prod = D exit D enter - 1 … M evap = Kg of moisture evaporated per unit time … M prod = Kg of paper produced per unit time … D exit = Dryness at the exit of machine … D enter = Dryness at entry of machine IN PAPER MILLS
  11. 11. STEAM & CONDENSATE SYSTEM <ul><li>Major Three Type of Condensate Evacuation System: </li></ul><ul><ul><li>Conventional Trap Based System </li></ul></ul><ul><ul><li>Cascaded System </li></ul></ul><ul><ul><li>Thermocompressor based Blow Thru System </li></ul></ul>IN PAPER MILLS
  12. 12. <ul><li>Conventional Trap Based System: </li></ul><ul><li>Steam traps are installed for condensate evacuation from the cylinders. </li></ul>STEAM & CONDENSATE SYSTEM IN PAPER MILLS
  13. 13. STEAM & CONDENSATE SYSTEM Conventional Trap Based System IN PAPER MILLS
  14. 14. STEAM & CONDENSATE SYSTEM <ul><li>Conventional Trap Based System: </li></ul><ul><ul><li>Disadvantages: </li></ul></ul><ul><ul><li>Not suitable for higher speed machines fitted with rotary syphons </li></ul></ul><ul><ul><li>Low surface temperatures results in lower drying rates </li></ul></ul><ul><ul><li>Adequate dP is not ensured </li></ul></ul>IN PAPER MILLS
  15. 15. <ul><li>Cascade System: </li></ul><ul><ul><li>System installed on medium & high speed machines </li></ul></ul><ul><ul><li>Blow thru steam from one dryer group is cascaded to previous dryer group </li></ul></ul>STEAM & CONDENSATE SYSTEM IN PAPER MILLS
  17. 17. <ul><li>Cascade System: </li></ul><ul><li>Disadvantages: </li></ul><ul><ul><li>Operating Pressure of main steam section dictates pressure limit for remaining sections </li></ul></ul><ul><ul><li>Interdependency of drying groups reduces flexibility for machine operation and machine runnability </li></ul></ul>STEAM & CONDENSATE SYSTEM IN PAPER MILLS
  18. 18. <ul><li>Thermocompressor based Blow thru system: </li></ul><ul><ul><li>Low pressure flash steam is boosted using Thermocompressor system </li></ul></ul><ul><ul><li>Recompressed blow thru & flash steam is recirculated back in the same drying group </li></ul></ul>STEAM & CONDENSATE SYSTEM IN PAPER MILLS
  19. 19. STEAM & CONDENSATE SYSTEM Thermocompressor based Blow thru system IN PAPER MILLS
  20. 20. <ul><li>Thermocompressor based Blow thru system: </li></ul><ul><li>Advantages: </li></ul><ul><ul><li>Each steam group can be operated at highest steam pressure governed by temp profile for that GSM </li></ul></ul><ul><ul><li>Each individual steam section can be controlled independently </li></ul></ul><ul><ul><li>Greater degree of flexibility in addressing drying problems </li></ul></ul>STEAM & CONDENSATE SYSTEM IN PAPER MILLS
  21. 21. STEAM & CONDENSATE SYSTEM <ul><li>Selection of Steam & Condensate System </li></ul>IN PAPER MILLS Speed Range Recommended System 150-250 Trap Based 250-650 TC based Blow Thru >650 TC based Blow Thru
  22. 22. <ul><li>ROTARY JOINTS AND SYPHONS </li></ul>IN PAPER MILLS
  23. 23. ROTARY JOINTS <ul><li>Rotary Joints: </li></ul><ul><ul><li>Interface between Rotating Dryers and Stationary steam & condensate piping </li></ul></ul><ul><ul><li>Performance requirement: To ensure adequate supply of steam and effective condensate evacuation from rotating dryers </li></ul></ul>IN PAPER MILLS
  24. 24. ROTARY JOINT <ul><li>Construction : </li></ul>IN PAPER MILLS RRJ – For rotary syphon SRJ – For stationary syphon
  25. 25. ROTARY JOINT <ul><li>SRJ Construction: </li></ul>IN PAPER MILLS
  26. 26. ROTARY JOINT <ul><li>SRJ Mounting: </li></ul>IN PAPER MILLS
  27. 27. ROTARY JOINT <ul><li>RRJ Construction: </li></ul>IN PAPER MILLS
  28. 28. ROTARY JOINT <ul><li>RRJ Mounting: </li></ul>IN PAPER MILLS
  29. 29. SYPHON <ul><li>Collects and transfers the condensate in dryer, to rotary joint. </li></ul><ul><li>Types: </li></ul><ul><ul><li>Stationary Syphons </li></ul></ul><ul><ul><li>Rotary Syphons </li></ul></ul>IN PAPER MILLS
  30. 30. SYPHONS <ul><li>Stationary Syphon: </li></ul>IN PAPER MILLS
  31. 31. SYPHONS <ul><li>Rotary Syphon: </li></ul>Syphon Shoe Profile IN PAPER MILLS
  32. 32. SYPHONS <ul><li>Syphon Selection: </li></ul>IN PAPER MILLS Syphon type Low speed Stationary Rotary High speed Stationary Speed range (mpm) 150-250 250-650 >650 Clearance (mm) 10 – 12 1.5 – 3.0 3.0-5.0