*Una Aproximacin al Diseo de Transporte Neumatico en Fase Diluida

*Etapas en el Diseo de Transporte Neumtico en Fase Diluida Propiedades del Material y del fluido (densidad, tamao y forma, viscosidad, etc.)Especificar la velocidad deseada de transporte neumticoEstimar el diametro de la caeriaCalcular la saltation velocityChequear la carga (masa solidos/masa gas) Si > 10 to 15 Necesita mayor diametro de caeriaSi < 1 Necesita mas pequeo de diametro

*Etapas ContCalcular la caida de presinPuede requerir iteracinSi es grande puede requerir gradualmente incrementar el tamao de la caeria (telescopio)No permitir que la velocidad caiga debajo de la saltation velocityTamao del soplador

*Components sum to total pressure dropFilterBlowerHopperOther ComponentsCycloneDust collectorFilterValves

Blower, silencer, inlet filterAccelerationHorizontal pipe sectionPipe bendsVertical pipe section1.2.3.4.5.

*AceleracinGas (outside of blower) and particles must accelerate up to operating velocityConveying gas velocityGas densityParticle velocityPipe cross sectional areaConveying rate (mass/time) Solids loading =

*Relacin entre Vp and VgVg Vp = slip velocityEmpirical relation by Hinkle (1954)dp = particle diameter (meters)Particle density in kg/m3In English unitsdp in feetdensity in lbm/ft3

*Bends (Curvas)Fuente importante de desgaste por atricin Prdidas de presin se asocia a la re-aceleracin de las del gas y de los slidos Las curvas generalmente se especifican por un cociente del radio de la curva al dimetro R/D de la caera Tpico en transporte R/D = 6 a 12

RD

*CurvasChambers and Marcus (1986)

R/D >= 6, B = 0.5R/D = 4, B = 0.75R/D = 2, B = 1.5

*Caeria Horizontal Pressure loss associated with frictional losses by gas and solids L = length of horizontal section = solids friction factorUse experimental data if available

*Factor Friccin para SlidosFor dp > 500 microns

For dp < 500 microns

where= TerminalVelocity

*VerticalPressure loss accounts for frictional losses plus static head (gravity)Bulk densityVoid fraction of gas phase(recall for fluidized beds voidage is typically 0.4 to 0.7)

*Calculo de f

Factor friccin gas Ecuacin de Churchillf = 2[(8/Re)^12+(1/A+B)^3/2]^1/12Re = gVgD/385100,85A = [2,457Ln[1/((1/Re)^0,9+0,27*k/D)]]^16B = (37530/Re)^16k = 0,00015Pie