The document discusses steam and condensate systems used in paper mills. It describes different types of paper mills based on raw materials and classifications. It also defines key terminology used in paper mills like GSM, draw rate, drying rate and specific steam consumption. The document discusses three main types of condensate evacuation systems - conventional trap based, cascade and thermocompressor based blow-through systems. It also describes rotary joints, syphons and factors in selecting appropriate steam and condensate systems based on machine speed.

1. Paper Machine Steam Systems Session 4 Energy Management Seminar , Ho Chi Minh City, May 2008

2. PAPER INDUSTRY Classification of paper mills Terminology Steam & Condensate System Rotary Joints & Syphons

3. CLASSIFICATION Based on Raw Material Used Agro Based Rice, Wheat Straw, Husk, Jute Recycled Based Recycled Paper Integrated Pulp & Paper Mill Hardwood & Softwood IN PAPER MILLS

4. TERMINOLOGY GSM – Grams per meter square of paper produced Typical GSM for different papers 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. TERMINOLOGY Draw Rate Kgs of paper drawn per unit time Normally measured in Kg/hr Draw Rate (Kg/Hr) = GSM x 10 -3 x Paper Width x mpm x 60 … .mpm = meters per minute IN PAPER MILLS

6. TERMINOLOGY Drying Rate Rate at which water is removed from dryer per unit area per hour = DR = M evap / Area = M evap / (  * D * L * n) … DR = Drying Rate Kg/Hr-m 2 … D = OD of drying cylinder - m … L = Cylinder Length - m … n = No. of cylinders IN PAPER MILLS

7. TERMINOLOGY Typical Drying Rates Observed (in Indian scenario, for reference only) IN PAPER MILLS Paper Quality DR – Kg/hr-m 2 Tissue 20 Writing Printing 18-20 Craft 15-20 Newsprint 20-25

8. TERMINOLOGY Specific Steam Consumption 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. TERMINOLOGY Specific Steam Consumption Theoretical Value : 1.13 TAPPI standard : 1.3 (For all grades) In India : 1.6-1.8 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. FORMULAE Basic Formula for Calculating Mass of water evaporated: 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. STEAM & CONDENSATE SYSTEM Major Three Type of Condensate Evacuation System: Conventional Trap Based System Cascaded System Thermocompressor based Blow Thru System IN PAPER MILLS

12. Conventional Trap Based System: Steam traps are installed for condensate evacuation from the cylinders. STEAM & CONDENSATE SYSTEM IN PAPER MILLS

13. STEAM & CONDENSATE SYSTEM Conventional Trap Based System IN PAPER MILLS

14. STEAM & CONDENSATE SYSTEM Conventional Trap Based System: Disadvantages: Not suitable for higher speed machines fitted with rotary syphons Low surface temperatures results in lower drying rates Adequate dP is not ensured IN PAPER MILLS

15. Cascade System: System installed on medium & high speed machines Blow thru steam from one dryer group is cascaded to previous dryer group STEAM & CONDENSATE SYSTEM IN PAPER MILLS

16. STEAM & CONDENSATE SYSTEM Cascade System IN PAPER MILLS

17. Cascade System: Disadvantages: Operating Pressure of main steam section dictates pressure limit for remaining sections Interdependency of drying groups reduces flexibility for machine operation and machine runnability STEAM & CONDENSATE SYSTEM IN PAPER MILLS

18. Thermocompressor based Blow thru system: Low pressure flash steam is boosted using Thermocompressor system Recompressed blow thru & flash steam is recirculated back in the same drying group STEAM & CONDENSATE SYSTEM IN PAPER MILLS

19. STEAM & CONDENSATE SYSTEM Thermocompressor based Blow thru system IN PAPER MILLS

20. Thermocompressor based Blow thru system: Advantages: Each steam group can be operated at highest steam pressure governed by temp profile for that GSM Each individual steam section can be controlled independently Greater degree of flexibility in addressing drying problems STEAM & CONDENSATE SYSTEM IN PAPER MILLS

21. STEAM & CONDENSATE SYSTEM Selection of Steam & Condensate System IN PAPER MILLS Speed Range Recommended System 150-250 Trap Based 250-650 TC based Blow Thru >650 TC based Blow Thru

22. ROTARY JOINTS AND SYPHONS IN PAPER MILLS

23. ROTARY JOINTS Rotary Joints: Interface between Rotating Dryers and Stationary steam & condensate piping Performance requirement: To ensure adequate supply of steam and effective condensate evacuation from rotating dryers IN PAPER MILLS

24. ROTARY JOINT Construction : IN PAPER MILLS RRJ – For rotary syphon SRJ – For stationary syphon

25. ROTARY JOINT SRJ Construction: IN PAPER MILLS

26. ROTARY JOINT SRJ Mounting: IN PAPER MILLS

27. ROTARY JOINT RRJ Construction: IN PAPER MILLS

28. ROTARY JOINT RRJ Mounting: IN PAPER MILLS

29. SYPHON Collects and transfers the condensate in dryer, to rotary joint. Types: Stationary Syphons Rotary Syphons IN PAPER MILLS

30. SYPHONS Stationary Syphon: IN PAPER MILLS

31. SYPHONS Rotary Syphon: Syphon Shoe Profile IN PAPER MILLS

32. SYPHONS Syphon Selection: 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