填料塔计算表.xls

SCRUBBER DESIGN(PACKED COLUMN)Prepared by:Column Tag No.:HCL ScrubberChecked by:Job No.:4506ADate:Client:JOLProject:SR-Plant-4,5Input DataStream:HCL Vap.Packing type=Intallox SaddlesPacking size=25 mmPacking MOC=PPGas pr.Drop/m bed=15 mmWC/m packing height=147.1(N/m2)/mTotal packing height=3.2 m(including all packed beds)Gas/Vapour PropertiesGas/Air flow rate=1000 kg/hOR0 m3/h=0.2778 kg/s=0 m3/sGas pressure at entry=1.0000 atmGas temperature at entry=30.00oC=303.00oKGas/Air mol weight=29Component to be scrubbedComponent Name=HCL VapComponent flow rate=70 Kg/h%comp.in air/gas=6%(v/v)(presumed)/(given by client)/(by process cal.)Molecular weight of comp.=36.5Liquid/Scrubbing media PropertiesScrubbing media=20%NaOHLiquid flow rate,L=77 kg/h=0.0214 kg/sLiquid Density,L=1100 kg/m3Conversion:Liquid Viscosity,L=0.0035000 Ns/m23.5 Cp =0.00350000Ns/m2Packing factor,Fp=21 m-1Charac.Packing Factor,Cf=33 Ref.Table 6.3,Characterstics of Random packingsConversion factor,J=1.0 factor for adequate liquid distribution&irrigation across the bedSheet 1 of 10 CalculationsTO CALCULATE COLUMN DIAMETERSince larger flow quantities are at the bottom for an absorber,the diameter will be chosen to accommodate the bottom conditions.To calculate Gas densityAvg.molecular weight=29.45 Kg/KmolIf gas flow rate is given in kg/hIf gas flow rate is given in m3/hGas in =0.009432183 Kmol/sGas in =(m3/s)x 273x pr.in atm x 1kmol=mass/mol wt T in kelvin1.0 atm22.4=(kmol/s)x T in kelvin x 1.0 atm x 22.4 273 pr.In atm 1=0 Kmol/s=0.234499 m3/s=0 Kg/smass=mol wt x kmolSelect vol.flow rate and mass flow rate from above,Selected mass flow rate=0.277778 Kg/sSelected vol.Flow rate=0.234499 m3/sSelected molar flow rate=0.009432 Kmol/sTherefore,gas density=1.1846 Kg/m3(mass flow rate/vol.Flow rate)To find L,G and Tower c/s areaAssuming essentially complete absorbtion,Component removed=0.0207 Kg/s(molar flow rate x%comp.x mol.Wt.)Liquid leaving=0.0420 Kg/s(Inlet liquid flow rate+comp.Removed)L G0.5=0.00497G LUsing 0.00497as ordinate,Refer fig.6.34 using a gas pressure drop of147.1(N/m2)/m G 2 Cf L0.1 J=0.04 (from graph)G(L-G)gcTherefore,G=0.04 G(L-G)gc0.5 Cf L0.1 J=1.6665 Kg/m2.sTower c/s area=0.1667 m2(c/s area=mass flow rate/G)Tower diameter=0.4607 m=460.7 mm=500 mmSheet 2 of 10 Corresponding c/s area=0.1963 m2TO ESTIMATE POWER REQUIREMENTEfficiency of fan/blower=60%assumed/givenTo calculate pressure dropPressure drop for irrigated=470.72 N/m2(pressure drop per m packing x total ht.of packing)packingFor dry packing,O/L Gas flow rate,G=1.3095 Kg/m2.s(Gas inlet flow rate-Component removed)/c/s areaO/L Gas pressure=100854.3 N/m2(subtracting pressure drop across packing)Gas density,G=gas mol wt.x 273 xgas o/l pr.22.41m3/Kmol T in kelvin101330=1.1605 Kg/m3CD=96.7 Ref.Table 6.3,Characterstics of Random packingsDelta P=CD G 2 ZG =142.89 N/m2Pressure drop for packing=613.61 N/m2(irrigated packing+dry packing)Pressure drop for internals=25 mmWC(packing supports and liquid distributors)=245.17 N/m2Gas velocity=7.5 m/sInlet expansion&outlet=1.5 x Velocity heads=1.5 x(V2/2g)contraction losses=42.19 N m/Kg=49.97 N/m2(divide by density)Total pressure drop=908.75 N/m2(packing+internals+losses)Fan power output=pressure drop,N/m2 x(gas in-component removed)Kg/sO/L gas density,Kg/m3=201.35 N.m/s=0.20 kWPower for fan motor=0.34 kW(fan power output/motor efficiency)=0.45 hpSheet 3 of 10 COLUMN DIAMETER/HYDRAULIC CHECKLiq.-Vap.Flow factor,FLV=(L/V)x (V/L)=0.0025Design for an initial pressure drop of 15mm H2O/m packingFrom K4 v/s FLV,K4=0.85K4 at flooding=6.50Trial%flooding=(K4/K4 at flooding)x 100=36.1620Gas mass flow rate,Vm=K4.V(L-V)13.1 Fp(L/L)0.1=3.7763 kg/m2.sTrial column c/s area=V/Vm(Trial As)=0.0736 m2Trial column dia.,D=0.3060 mD=(4/pi)x Trial AsRound off D to nearest standard sizeTherefore,D=0.500 mColumn C/S area,As=0.1963 m2As=(pi/4)x D2%flooding=13.5472%flooding=Trial%flooding x(Trial As/As)ConclusionGenerally packed towers are designed for 50%-85%flooding.If flooding is to be reduced,(i)Select larger packing size and repeat the above steps.OR(ii)Increase the column diameter and repeat the above steps.(1/2)Sheet 4 of 10 HETP PREDICTIONNortons Correlation:ln HETP =n-0.187 ln +0.213 ln Applicable when,liquid phase surface tension 4 dyne/cm&0.08 cP&0.83 cPConversion:Input Data0.018 N/m =18dyne/cmLiquid-phase Surface Tension,=20 dyne/cmNortons Correlation ApplicableLiquid Viscosity=3.5 cPNortons Correlation NOT applicablen=1.13080Calculationln HETP=0.837437HETP=2.310437 ft=0.704221 mFor separations,less than 15 theoritical stages,a 20%design safety factor can be applied.Considering 20%safety factor,HETP=0.845065 mFor separations,requiring 15 to 25 theoritical stages,a 15%design safety factor can be applied.Considering 15%safety factor,HETP=0.809854 mSheet 5 of 10 Table 6.2Constant for HETP CorrelationRef.:Random Packings and Packed Towers -StrigleRef.:Chemical Engineering,Volume-6,COULSON&RICHARDSONSRef.:Mass Transfer Operation:Treybal