SECUENCIA DE CÁLCULOS.

Cantidad de agua evaporada.

W i=M i

θ0(60)

W i=9.850kg19.04min

(60 )=31.04kggravah

W s=M s

θ0(60)

W s=9.4 kg19.04min

(60 )=29.6218kggravah

W e=W i−W s

W e= (31.04−29.6218 )kggravah

=1.418kg A

h

Cantidad de aire necesario para el secado.

W 2=W 1=W a=W e

Y 2−Y 1

W 2=W 1=W a=1.418

kg A

h

(0.156−0.014 )kgAkgB

=0.2943kgBh

Nota: Y2 y Y1 obtenidas de grafica 1.

Masa velocidad del aire.

G=W 2

A=

W 2

2πrh

G=0.2943

kgBh

2π (0.126m)(1.877m)=0.1981

kgBh−m2

Tiempo de residencia.

F=W i

A=

W i

2 πrh

F=31.04

kggravah

2π (0.126m )(1.877m)=20.8885

kggravah−m2

β=5(Dp)−0.5

β=5(35,000μm)−0.5=0.0267

θ= 0.23 L

S N0.9D− βLG

F(1.97 )

θ=0.23(1.877m)

(0.085m /m )(1.5 r . p .m .)0.90.32m−

(0.0267 ) (1.877m)(0.1981 kgBh−m2 )

20.8885kggravah−m2

(1.97 )=11.0185min

%=θteo−θexpθ exp

100 = 19.04−11.0185

11.0185100=72.8%

Volumen de gas de secado.

V 2=( 129+Y 218 )( RT 2P )W 2

V 2=( 1

29kgBkmolB

+0.156

kg A

kgB

18kgAkmol A

)((0.08205atm−m3

kmolT−K )(164+273.15)K0.7697atm

) (0.2943 )kgBh

=0.5917 m3

h

Calor suministrado por el gas combustible.

ρg=ρC3 H 8(0.5686 )+ ρC4 H10 (0.4314 )

ρg=(1.83 gL )(0.5686 kmol AkmolT )+(2.52 gL )(0.4314 kmolBkmolT )=2.127 gL

W g=(Lg ) (17 )(60)(ρg )

1000

W g=(0.64 ) (17 )(60)(2.127 gL )

1000

W g=1.3885kggas LPh

P .C .=14,600C+62,000H

P .C .=14,600 (0.8235 )+62,000 (0.1764 )=22,959.9 btulbgas LP

=12,755.6 kcalkggas LP

Q g=(W g ) (P.C . )

Q g=(1.3885 kggas LPh )(12,755.6 kcalkggas LP )=17,711.15 kcalh

Calor absorbido por la grava.

Qs=W sCps (t f−ti )

Qs=(29.6218 kggravah )(0.17 kcalkggrava−°C ) (104−17 ) °C=438.1064 kcal

h

Calor absorbido por el gas de secado.

Qa=W aCpa ( t2−t a )

Qa=(0.2943 kgBh )(0.24 kcalkgB−° C ) (164−24 )° C=9.8884 kcal

h

Calor absorbido por el agua evaporada.

Qw=W e (H v−H a )

Qw=(1.418 kgAh ) (661.73−26.06 ) kcalkg

=901.3801 kcalh

Eficiencia térmica.

nt=Qs+Qa+Qw

Q g

(100 )

nt=(438.1064+9.8884+901.3801 ) kcal

h

17,711.15kcalh

(100 )=7.62%

Eficiencia de secado.

ns=Qw

Qs+Qa+Qw

(100 )

ns=901.3801

kcalh

(438.1064+9.8884+901.3801 ) kcalh

(100 )=66.8%

Costo de secado por kilogramo de producto.

C s=1W a

[ (W g ) (Cg )+(kW ) (C E ) ]

C s=1

0.2943kgproducto seco

h

[(1.3885 kggas LPh )(5.85 $kggas LP )+ (0.38kW )(0.7 $

kW−h )]CS=27.8661

$kg producto seco

ANEXOS

0 20 40 60 80 100

120

140

160

180

200

220

240

260

280

300

00.010.020.030.040.050.060.070.080.090.1

0.110.120.130.140.15

Ys vs. T

Temperatura

Ys