Felt Conditioning Technology Delivering Value through People Chemistry Impact of Felt Problems on Performance Compaction Filling Sizing Wear Fiber damage 900 850 800 ml/minute • • • • • CD Felt Permeability 750 700 650 600 550 500 CD Position Delivering Value through People Chemistry Philosophy of Felt Conditioning • Condition press felts to keep them in their original, “broken in” condition throughout their useful lives • Slow down the process of felt filling and deposit formation • Remove built-up contaminants with the proper cleaning chemistry Delivering Value through People Chemistry Felt Permeability over Time vs. Felt Treatment ml/minute “Broken in” permeability Ideal performance Batch cleaning only Conditioning only Untreated Days Delivering Value through People Chemistry Which Treatment? • • • • • Survey the machine Identify root causes Correct mechanical problems Determine customer goals Prepare treatment options – Different programs have different costs and results Delivering Value through People Chemistry Felt Cleaning • Type of contaminant • Feed schedule – Down batch – Batch-on-the-fly (BOTF) • Shower location Delivering Value through People Chemistry Contaminants and Cleaning Agents Solvent Extractable Amide Asphalt Latex, Grease Polyethylene Oil, Wax Abietic Acid Rosin Size Fatty Acid Fatty Ester Starch Alkaline Dry Strength Extractable Biological Slime Lignin Glue Fatty Acid Salt Abietic Acid Salts Wet Strength Alkaline Size Aluminum Hydroxide Calcium Carbonate Clay, Talc, TiO2 Delivering Value through People Chemistry Ash Acid Extractable Down Batch vs. BOTF Cleaning Down Batch • Advantages – Intensive cleaning – Not regulated regarding food contact, etc. – Easy to keep personnel out of the press section • Disadvantages – Requires machine downtime – Not performed until felts become significantly dirty Delivering Value through People Chemistry BOTF • Advantages – Milder cleaning than down batch – No machine downtime required – Felts only become a little dirty before performing • Disadvantages – May surprise personnelmust warn operators, etc. before performing – Regulated regarding food contact, etc. Amazon Felt Cleaners • AmiClean AP2048 (Down Batch/ BOTF) – Non-solvent – Good for Tissue & wet strength • AmiClean AP1850 (Down Batch/ BOTF) – Water-soluble solvent – Good for latex • AmiClean AP1894 (Down Batch) – Heavy solvent – High odor – Good for stickies Delivering Value through People Chemistry Chemical Action: CleanerDown Batch/BOTF Delivering Value through People Chemistry Chemical Shower Location: Down Batch Delivering Value through People Chemistry Chemical Shower Location: BOTF Light weight grades Heavy weight grades Delivering Value through People Chemistry Felt Conditioning • Type of contaminant/grade of paper • Three basic approaches – Surfactants – Passivation – Solvents (acid/alkali/hydrocarbon) • Shower location • Percentage of product by felt position Delivering Value through People Chemistry Chemical Action: Surfactant Delivering Value through People Chemistry Commonly Used Surfactants Dispersants • Anionic • Effective on charged materials – Pitch – Coated broke – Filler _ _ __ _ _ _ Non-ionic surfactants • Charge neutral • Emulsifiers and penetrants • Effective on non-charged materials – Size – Oils – Antifoams _ _ Contaminant _ _ _ _ _ _ _ Delivering Value through People Chemistry Contaminant Chemical Shower Location: Surfactants If overspray or dripping is a concern If overspray or dripping is not a concern Delivering Value through People Chemistry Chemical Action: Passivation Delivering Value through People Chemistry Passivation: Surface Energy Modification Contaminant spreads and becomes well attached Contaminant < Surface Delivering Value through People Chemistry Contaminant does not spread and is removed easily Contaminant > Surface Chemical Shower Location: Passivation Good choice for surface contaminationmust minimize shower volume Good general purpose choice Usually 1st choice for internal filling control Delivering Value through People Chemistry Choosing the Right Felt Conditioner • Passivation – Especially effective on stickies – Product feed rate is independent of application shower volume – Must have at least -30 µeq/liter charge in headbox – Must use fresh water in application shower Delivering Value through People Chemistry • Surfactants – Can use clarified white water in the application shower – May cause foam – Product feed rate is dependent on application shower volume • Solvents – Potential environmental and safety concerns – Product feed rate is dependent on application shower volume Amazon Felt Conditioners • Passivation – AmiSpray AP8683 – AmiSpray AP8694 • Surfactant-based – AmiClean AP2048 – AmiSpray AP8705 Delivering Value through People Chemistry Felt Conditioner Feed Rates by Felt Position • Feed according to need • More water removed by the felt means more contaminants in the felt • Pickup felts need extra attention • Mechanical cleaning affects felt conditioning needs – Needle shower pressure – Oscillation rate Delivering Value through People Chemistry Conditioner Distribution by Felt Position 2nd top: 20% Pickup: 50% Transbelt 1st bottom: 30% Delivering Value through People Chemistry Commonly Monitored Variables Indirect Monitoring Direct Monitoring • Uhle box vacuum • Production • Uhle box water flow • Machine speed • Uhle box air flow • Felt life • Felt permeability • Sheet breaks • Felt moisture • Sheet defects • Sheet moisture profile • Dryer section steam Delivering Value through People Chemistry • Downtime for cleaning Uhle Box Vacuum • Oldest indicator of felt performance • Increase in vacuum level can indicate filling, compaction, or higher water content in felt • Decrease in vacuum level can indicate felt wear or partial vacuum loss – Uhle box deposits – Misplaced deckle strips • Only indicates average performance across the felt width • Not useful with a Turbo blower or shared Delivering Value through People Chemistry vacuum source Huyck Smith Porosity Tester • Portable vacuum source and gauge • Can be used to measure percent loss of porosity over the life of the felt • Gives readings across the width of the felt Delivering Value through People Chemistry Uhle Box Water Flow over Time Liters/minute 800 0 Delivering Value through People Chemistry Days Microwave Moisture Meter • Measures the water content of the felt • Gives a detailed profile of the felt across its width • Excellent tool for troubleshooting and checking press loading and roll crown problems • Strongly influenced by press section shower volumes Delivering Value through People Chemistry Felt Permeability Tester • Measures the ability of the felt to accept water • Gives a very precise profile in the cross machine direction • Can be used to troubleshoot, like the microwave moisture meter • Can detect felt sizing Delivering Value through People Chemistry High Pressure Shower Recommendations • Nozzles – 6” or 12” (15 or 30 cm) center to center – 0.040” (0.1 cm) diameter orifice – 0.59 gpm (2.2 l/min) • Oscillator stroke: 12” (30 cm) • Pressure: 150-350 psi (10-24 bar)- depends on felt structure and contaminant load Delivering Value through People Chemistry • Position – Sheet side – 15-45o angled against felt run – 4-8” (10-20 cm) from felt • Operation – – – – Continuous Pressure regulation Warm water Proper oscillation rate Illustration of High Pressure Shower Cleaning Jet 10 cm 10-20 cm >20 cm .2 cm 2400 Kpa HP Cleaning Summary Phase Distance Comments I 0-4” / 10 cm .040” (.1 cm) cleaning;>tendency for felt damage/wear II 4-8” / 10-20 cm .080” (.2 CM) cleaning;>velocity - max cleaning action through IIIDelivering overValue 8” / >20 cmPeople Chemistry Jet velocity breakup; jet expands and entrains air - little cleaning Correct Shower Oscillation Rate S: Running Speed (m/min) N: Rev. per Min (rpm) R: Stroke Rate (cm/min) L: Loop Length (m) t: Width cleaned per Nozzle (cm) Oscillation Rate = R = S * t/L EXAMPLE: S = 1100 m/min, L = 21 m Felt, C = 5.75 m for a 1.8 m dia roll and t = .1 for a .1 cm orifice nozzle Felt Complete Coverage Stroke Rate:Complete Coverage Cleaning Incorrect Oscillator Rate S·t 1100 * 0.1 R= L = 21 = 5.2 cm/min Delivering Value through People Chemistry Uhle Box Shower Recommendations • Nozzles – 6-8” (15 -20 cm) center to center – 0.03 - 0.07 gpm/inch (0.045-0.075 l/min-cm) • Pressure: 20-30 psi (1.4-2.1 bar) • Position – Angled into Uhle box nip • Operation – Continuous – Pressure regulation – Warm water Delivering Value through People Chemistry Chemical Shower Recommendations • Nozzles – 6-8” (15 -20 cm) center to center – 0.08-0.15 gpm/inch (0.120.23 l/min-cm) • Pressure: 40-50 psi (2.75-3.4 bar) • Position – Conditioning application: inside with dwell time – Passivation application: sheet side – BOTF: Uhle box lube shower Delivering Value through People Chemistry • Operation – Continuous (BOTF is intermittent) – Pressure regulation – Warm water (fresh water for passivation) – Even coverage Uhle Box Recommendations • Vacuum: 10” Hg (35 kPa) - 15” Hg (50 kPa) • Dwell Time: 3-5 milliseconds • Air Flow Rate: – Slots: 12-15 cfm/in2 (3.2-4.0 m3/h-cm2, or 8.8-11 m/sec) – Herringbone: 12 cfm/in2 • Square cover edges on uhle boxes (doctoring effect) • Separate vacuum source for each felt • Control atmospheric Delivering Value through People Chemistry (breaker) valve