Strategies For High Vacuum Dewatering On Paper Machines

The Paper machine vacuum system is an important contrivance for dewatering of wet web as well as increasing percentage solids in web.There are various models  available to assess the influence of vacuum on the above parameters. In this present investigation the steady state model is discussed for estimating optimum vacuum load in flat boxes of fourdrinier paper machine as the flat boxes are the main components to dewater the sheet as well as wire/ felts in the paper machine. From the detailed investigation it has been found that  for a given furnish and vacuum level, there is an ultimate achievable dryness beyond which the sheet will not go, no matter what the length of exposure is.Further there are  two main factors in vacuum dewatering - the ultimate achievable dryness for that vacuum, and the rate at which that dryness is attained. This paper also indicates the effect of temperature and slots design for vacuum dewateringThe Paper machine vacuum system is an important contrivance for dewatering of wet web as well as increasing percentage solids in web.There are various models  available to assess the influence of vacuum on the above parameters. In this present investigation the steady state model is discussed for estimating optimum vacuum load in flat boxes of fourdrinier paper machine as the flat boxes are the main components to dewater the sheet as well as wire/ felts in the paper machine. From the detailed investigation it has been found that  for a given furnish and vacuum level, there is an ultimate achievable dryness beyond which the sheet will not go, no matter what the length of exposure is.Further there are  two main factors in vacuum dewatering - the ultimate achievable dryness for that vacuum, and the rate at which that dryness is attained. This paper also indicates the effect of temperature and slots design for vacuum dewatering