Paper Machine Room Ventilation Guidelines - TAPPI

1 Paper Machine room Ventilation Guidelines John nielsen BE&K Engineering Co., LLCTAPPI PaperCon 09St. Louis, MO June 3, 2009 Session 64 TIP 0404-50 Paper Machine room Ventilation Guidelines Purpose of 2009 Revision Earlier issues: Numerous methods wide range of flow rates Establish base Ventilation rates tied to Machine parameters Scope Guidelines for designing systems Design criteria Ventilation principles Sizing or dimensioning exhaust, supply, and misc. systems Overview of heat recovery options Air surveys Performance indicatorsPerception Statements often made in discussing Ventilation : Doesn t directly make Paper Only for personnel comfort Added equipment to operate and maintain Increased energy consumption Increased exhaust didn t improve conditionsPaper Machine room Ventilation Guidelines - 3 Purpose1.

2 Replaces air removed as part of process, drying, and vacuum systems2. Provide a controlled environment for papermaking, personnel, and preservation of the building which includes containment and removal of: Water vapor Heat DustPaper Machine room Ventilation Guidelines - 4 Consequences Fog Paper Machine room Ventilation Guidelines - 5 Consequences Fog Stratified flowsPaper Machine room Ventilation Guidelines - 6 Consequences CondensationPaper Machine room Ventilation Guidelines - 7 Deteriorated GirtsConsequences Structural FailurePaper Machine room Ventilation Guidelines - 8 Consequences Structural FailurePaper Machine room Ventilation Guidelines - 9 Basis of Guidelines Design Criteria TemperatureLocationMinimum FMaximum above ambient FGround floor65 10 Operating floor tending side, wet end75 5 Operating floor tending side.

3 Elsewhere65 5 Operating floor drive side65 10 Mezzanine- 20 Underside Roof- 25 Paper Machine room Ventilation Guidelines - 10 Basis of Guidelines Design Criteria Water vaporLocationMaximumabove ambientGrains/lbDAGround floor 50 Operating floor 50 Mezzanine 100 Underside Roof 150 Paper Machine room Ventilation Guidelines - 11 Basis of Guidelines Design Criteria Dust OSHA Requirements Total airborne particles:15 mg/m3 Respirable particles, less than 10 m:5 mg/m3 Paper Machine room Ventilation Guidelines - 12 Basis of Guidelines Displacement Ventilation Paper Machine room Ventilation Guidelines - 13 AIR SUPPLIED INTO OCCUPIED ZONEAT LOW VELOOCITYBOUYANT SOURCEROOF EXHAUSTSTRATIFIED LAYERMEZZANINE FLOOROPERATING FLOORGROUND FLOORREAR CURTAINB asis of Guidelines Exhaust Systems Exhaust systems Process Former Vacuum Dryer section hood Saveall Pulper Building Wet end false ceiling Size press and coater false ceiling Roof SummerPaper Machine room Ventilation Guidelines - 14 Purpose.

4 Capture and contain water vapor carried with the wire and mist from showers Exhaust rate is a function of former type, Machine speed, geometry, and stock temperature Higher exhaust rates-Fourdrinier w/top ply > Gap former > Fourdrinier -On Machine silo > Off Machine silo-Increased Machine speeds-Higher stock temperatures Exhaust Systems Former Paper Machine room Ventilation Guidelines - 15 Based on flow per trim width and speed with correction for temperature Flow Adjustment, B added exhaust to ensure in flow Flow Factors, F total pumped air flow vnniiiitVBwFC =+ Exhaust Systems Former Paper Machine room Ventilation Guidelines - 16 Temperature CorrectionFlow factor based on former and pickup locationTrim WidthMachine SpeedFlow AdjustmentVolumetric Flow Exhaust Systems Fourdrinier Air Flows Paper Machine room Ventilation Guidelines - 17 BREAST ROLLHEADBOXBOUNDARY LAYEREXHAUSTFLOW ADJUSTMENT (B) TO MAINTAIN AN INFLOWFLOW FACTOR (F)

5 AIR PUMPED THROUGH AND WITH WIREE xhaust Systems Fourdrinier Paper Machine room Ventilation Guidelines - 18 HEADBOX/ BREAST ROLLFLUME & SILODRIVE SIDEPLENUMCOUCHPITF ourdrinier Pickup LocationFlow Factor, FftFlow Adjustment, Bft3/minBelow Wire Headbox & Breast ,000 Couch SiloBelow and inside wire loop drive side SiloInside wire and Systems Top Wire Paper Machine room Ventilation Guidelines - 19 HPCLEANINGSHOWERINSIDE WIRE LOOPTop Wire/Top PlyPickup LocationFlow Factor, FftFlow Adjustment, Bft3/minBeneath top former headbox (Top Ply) ,500 Inside top wire high pressure Systems Gap Former Paper Machine room Ventilation Guidelines - 20NO. 1 WIRESTRETCH ROLLHPCLEANINGSHOWERHEADBOXAREANO. 1 WIRE LOOP & SAVEALLFELTNO. 2 WIRE LOOP & SAVEALLGap Former Pickup LocationFlow Factor, FftHeadbox 1 Outer/Backing Wire Loop & 1 Stretch 2 Inner/Conveying Wire Loop & Systems Former Paper Machine room Ventilation Guidelines - 21 Machine Speed, ft/minExhaust Rate, ft3/min/in010002000300040005000600002004 00600800 Gap Former120 FFourdrinierOn M achine Silo140 FFourdrinier+TopPly140 FFourdrinier+TopWire120 FFourdrinierOff Machine Silo120 FExhaust rate versus former type and speedExhaust Systems Wet End Heat and water vapor transferred to room Paper Machine room Ventilation Guidelines - 2210'-11 "10'-11 "Exhaust Systems Wet End Paper Machine room Ventilation Guidelines - 23 Purpose.

6 Capture and contain water vapor originating from former and press top surfaces Exhaust rate is a function of surface area, Machine speed, geometry, number of steam boxes, and stock temperature Based on flow per surface area with correction for temperature, and geometry() vtwVBACCnDwE =++ 14243 Exhaust Systems Wet End Paper Machine room Ventilation Guidelines - 24 Exhaust Rate Turbulent mass transfer rates across a flat plate constant air and water temperatures 100 grain/lbDA pickup ratioMachine Speed Geometry factor Flow Constant Trim WidthSurface AreaSteam box / lazy steam shower exhaust rateTemperature CorrectionQuantity Wire surface area correctionExhaust Rate per AreaPaper Machine room Ventilation Guidelines - 25 Vaporization rate versus stock temperature and Machine speedExhaust Systems Wet End Stock Temperature, FVaporization Rate, lbH2O/ - 3000 ft/min4000 ft/min3000 ft/min2000 ft/min1000 ft/minExhaust Systems Supplemental Roof Exhaust Purpose.

7 Remove heat and water vapor not contained by other exhaust systems Exhaust rate is a function of: Water vapor from open and uncontained sources: False ceiling Dryer section hood sheet break Open tanks and chests Heat gain from the following sources: Paper product Refiners Pumps and fans Motors Tanks PipingPaper Machine room Ventilation Guidelines - 26 Supplemental Roof Exhaust Process Heat GainsPaper Machine room Ventilation Guidelines - 27 SourceFloorLevelHeat10-3 Btu/tonRefinersOperating58 88 CleanersOperating1,000 Btu/h/ft2 Stock Prep Pumps & PipingGround20 Vacuum SystemOperating37 Forming & Press Pumping & PipingGround75 Forming & Press PM Dryer PM PM Roof Exhaust Process Heat Gains Refiner loads Based on Paper grade 10% of total motor load Pumps and AC motors 10% of motor nameplate PM drive motors Calender, coater, reel.

8 And winder 50% of motor load All others 15% transferred into roomPaper Machine room Ventilation Guidelines - 28 Exhaust Systems Supplemental Roof Exhaust Paper Machine room Ventilation Guidelines - 29 Exhaust Systems Supplemental Roof Exhaust Exhaust rate for water vapor sources Minimum truss area exhaust 25% of wet end false ceiling exhaust rate 10% of dryer section hood exhaust rate Exhaust rate for heat sources Minimum Winter: 25 F temperature differential Summer: 10 F temperature differential for ground floor heat loadsPaper Machine room Ventilation Guidelines - 30 Supply Systems Fog What role do supply systems have in eliminating fog? Paper Machine room Ventilation Guidelines - 31 Basis of Guidelines Supply Systems Exhaust and make-up air systems are required to prevent fog and condensation: Increase humidity load = Condensation Decrease temperature = Condensation Key is to prevent uncontrolled air infiltration: Building air balance of 90-to-105% exhaust mass flow rate Proper air distribution Supply air to operating areas Displace heat and vaporPaper Machine room Ventilation Guidelines - 32 Basis of Guidelines Miscellaneous Systems Pocket Ventilation and Hood Make-up Hood Balance: 60-to70% of hood exhaust mass flow Source: mezzanine Roof Supply Required flow rate: Roof heat loss (R-value) Humidity load Minimum of R18 (ft2- F-hr/Btu) recommended Wet end.

9 Cfm/ft2 Trim Systems 70-to-80% of air should be extracted before entering pulper Paper Machine room Ventilation Guidelines - 33 System Performance1. Condensation or Corrosion ?2. Water vapor containment?3. Cold weather operation?4. Dryer hoods spillage?5. Building air pressure?6. Cold spots or hot spots?7. Temperature and humidity levels?8. Energy consumption? Paper Machine room Ventilation Guidelines - 34 Air System Surveys Purpose Identify root causes Establish a benchmark for future improvement Scope Condition of equipment Exhaust and supply airflows Compare to rated performance Building air balance Exhaust system effectiveness Dryer section hood Airflow paths Temperature and humidity distribution Control strategy Performance indicesPaper Machine room Ventilation Guidelines - 35 Performance Indices Overall Exhaust RateExhaust air compared to production ratePaper Machine room Ventilation Guidelines - 3633(ft or m / min)(lb or kg/ min)

10 Total Winter ExhaustProduction RatePaper Gradeft3/lb paperm3/kg paperBleached Board545 Medium375 530 Linerboard375 Indices Wet End Exhaust Flow rate Temperature and HumidityPaper Machine room Ventilation Guidelines - 37()322scfm or m /min(ft or m )Wet End ExhaustFormer + Press Area2150 grains H O/lbDAHumidity Ratio Pick up<25 FRoof Exhaust DB Operating Floor DB <o5 FDry Bulb Dew Point >oPerformance Indices Building Make-up Air Balance 90-to-105% of Exhaust 50% of wet end Air Distribution(%) Paper Machine room Ventilation Guidelines - 38 Floor LevelTotalTending SideDrive SideMezzanine0 5-0 5 Operating 70 8050 6010 20 Ground20 3010 205 10 Performance Indices Maintenance Equipment Performance Excellent 90% Good 75% Poor < 75% Paper Machine room Ventilation Guidelines - 39()()33 cfm or m /mincfm or m /minMeasured Exhaust Supply FlowsRated Exhaust Supply Flows++Summary room Ventilation is a necessary component of papermaking with serious consequences when ignored.