b'PRESS FABRIC OPERATIONPress fabric operation and influence on tissue shoe press applicationsBy Matt Bryer, Product Manager, Tissue Press Fabrics,The Americas, Albany International CorpEntering a new decade of tissue and paper making, revolutionary technologies continue to break the norm.From new machine concepts to the industrial internet of things, the best practices of making paper have come a long way.Looking toward 2020, one can also look back and begin to celebrate the anniversary of something equally as revolutionarythe birth and growth of the Shoe Press.It was in the early 1980s when the first shoe presses were starting up in the heavy paper grades; and they have continued to evolve and grow to become a standard press component in any newly erectedFigure 1. Pressure Profile of a Shoe Press versus a Conventional Roll Press for a Tissue Machine.packaging or publication grade paper machine.The advent of the Tissue Machine shoe press does not spanof either faster machine speeds, oran inside, pre-press vacuum zone back as far as other paper grades, butlower energy consumption at a givenrollalso known as the Suction its evolutionary path has been equallyspeed.Elevated dryness also means aTurning Roll.This key machine as important.The Press Fabrics thatstronger sheet, leading to less breakscomponents function is to ensure an run on these machines, and theirand better overall machine efficiency. optimal moisture ratio in the press fundamental performance have beenThe specific pressure profile of a shoefabric and sheet prior to the nip to a key contributor to the growth of shoepress, with a lower peak pressuremaximise pressing efficiency, while press applications for Tissue and Towelalso leads to improved bulk, or thepreventing sheet disruption.While grades. same bulk with less pulp fibre usagethe sheet consistency of a non-shoe compared to a conventional roll press. The adventpress will be in the ~12% range before WHY THE GROWTH IN TISSUE TRADES All of these attributes can contribute toof the Tissuethe press, the suction turning roll will A shoe press against a Yankee dryerthe bottom line for the tissue maker. Machine shoeachieve ~23% solids prior to the nip.generates the following nip dynamicsFigure 1 shows an example comparingpress doesWithout the suction turning roll or with compared to a conventional suction orthe pressure profile of a shoe pressnot span backtoo little vacuum and air flow, at high blind drilled press:1.) A lower peakversus a conventional roll press. as far asspeeds the hydraulic pressure in the pressure; 2.) An increased dwell time;other papershoe press nip would be so high that 3.) An increased nip impulse.As aGENERAL OPERATION ON TISSUE SHOE PRESSgrades, but itsit would cause crushing of the tissue result, and given the correct pressMACHINES evolutionarysheet.With too much vacuum and fabric design, these conditions lead toOne of the prerequisites for thepath has beenair flow, the press fabric will run too higher sheet dryness.This increasesuccessful operation of a shoe pressequally asdry in the press nip, causing a lower in paper solids can take the formon a high speed Tissue machine isimportant. hydraulic pressure and a loss of press 92 TISSUE TECHNOLOGY INTERNATIONAL'