final report on the multiport dryer - Argonne National Laboratory

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24x = 0.77160140∆ T = 5.6o Cx = 0.30x = 0.00Steam TemperatureWall TemperatureCoolant Temperature120Temperature ( o C)1008060402000.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5Axial Location (m)Fig. 11. Temperature distribution2.5System Pressure = 170 kPa - 620 kPaQuality = 0.10 - 0.802.0Pressure Gradient (kPa/m)1.51.00.50.00 10 20 30 40 50Mass Flux (kg/m 2 s)Fig. 12. Two-phase pressure gradient as function of mass flux
25Wall Temperature Distribution. A typical plot of wall temperature, steam temperature, andcoolant temperature distribution is given in Fig. 11. Three parameters contribute to ensuring theuniformity of dryer wall temperature: high condensing heat transfer coefficients, condensing heattransfer coefficients approximately independent of quality, and low steam pressure drop tomaintain a near-constant saturation temperature. As noted, all three of these criteria have nowbeen demonstrated in our current experimental results. Together, they ensure the temperatureuniformity needed in cylinder dryer applications. A numerical simulation of the MD wasconducted to provide axial distributions of temperature and condensate layer thickness. Theresults also show a near-uniform dryer surface temperature profile and a very thin condensatelayer on the order of 0.1 mm (0.004 in.).9 POTENTIAL BENEFITS9.1 Comparison with Conventional Cylinder DryersThe condensing heat transfer coefficients in a multiport cylinder dryer can be compareddirectly with those from steam condensation in conventional dryers with or without spoiler bars.The values for Multiport dryers are ≈ 15,000 W m 2 K (2600 Btu hr ft 2o F). In the conventionalcase, for an overall heat transfer coefficient of 328 W m 2 K (58 Btu hr ft 2o F, fine paper), thebase value for the condensing heat transfer coefficient in a dryer without spoiler bars rangesfrom 665 to 850 W m 2 K (117 to 150 Btu hr ft 2o F). The base value for the condensing heattransfer coefficient in a conventional dryer with spoiler bars is 2270 W m 2 K (400 Btu hr ft 2o F)[7, 18]. As shown in Fig. 13, the condensing heat transfer coefficient in the multiport cylinderdryer is ≈7 times greater than that in a conventional dryer with spoiler bars, and ≈20 timesgreater when compared with that in a conventional dryer without spoiler bars. This very largeimprovement in heat transfer coefficient for multiport cylinder dryers when compared withconventional dryers is the key to the increased efficiency of the heat transfer process in multiportcylinder dryers.9.2 Potential Benefits and ImpactsMultiport dryer technology will provide the following attractive benefits and impacts:• Increased drying rate or increased productivity, a major impact of the multiportcylinder dryer technology on the paper production industry, comes from the potential toincrease paper drying rates or production rates in existing machines. An increase indrying rate can be viewed in two ways. The number of dryers can be reduced whilepaper production rate remains the same, or alternatively, system speed can be increased
Page 1: ARGONNE NATIONAL LABORATORY9700 Sou
Page 4 and 5: Figures1 Resistances to heat transf
Page 6 and 7: 21 INTRODUCTIONThe pulp and paper i
Page 8 and 9: 4A B C D EF G HA - Steam convection
Page 10 and 11: 6In some cases, spoiler bars have b
Page 12 and 13: 8The structure of the multiport cyl
Page 14 and 15: 10TpSICAFMITemperaturePressureSight
Page 16 and 17: 12Nine Type-K thermocouples (T a,T
Page 18 and 19: 14D. After-condenser heat dump.The
Page 20 and 21: 165.2 ShutdownA. Turn off all Multi
Page 22 and 23: 18∆qh(z) =s(z)∆A s [ T s(z) −
Page 24 and 25: 2010080Heat Loss (W)60402000 20 40
Page 26 and 27: 22Average Condensing Heat Transfer
Page 30 and 31: 26to produce paper at a higher rate
Page 32 and 33: 28a steady-state market penetration
Page 34 and 35: 30• The condensing heat transfer
Page 36 and 37: 32[9] J. C. Y. Wang, L. J. Qiu, and
Page 38 and 39: 34more of the available energy from
Page 40 and 41: 36Market Penetration, Energy Saving
Page 42 and 43: 38Market Penetration, Energy Saving

final report on the multiport dryer - Argonne National Laboratory

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