metodologiadiseno

Metodologa general para el diseo de reactores qumicos

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23La `operacin unitaria qumica

1Metodologa general para el diseo de reactores qumicosEl modelo de diseo puede resumirse en un diagrama de flujo de informacin con las `relaciones de diseo fundamentales, junto a los diferentes tipos de `variables y los datos necesarios para la simulacin:

El procedimiento ms general para el `clculo de los reactores qumicos, a partir de la resolucin simultnea de la cintica y los balances de materia y energa, consiste en representar v (Co,x,T) en forma de diagramas vxT (con v como parmetro y Co fijo); sobre dicho diagrama pueden trazarse las lneas de operacin del rgimen trmico T (To,x,q), y con la pauta de temperatura resultante se obtiene la relacin entre la velocidad y la conversin a lo largo de la reaccin v (Co,x).

El tiempo de residencia (o la velocidad espacial) en el reactor se obtienen representando Co/v vs. x, y utilizando la ecuacin de diseo correspondiente (Co,x,v) (para el reactor discontinuo, un tanque continuo agitado, o uno de flujo tubular): (Co,x).2Se desea llevar a cabo el proceso en disolucin acuosa diluida: A = R que se ajusta a una cintica reversible y exotrmica de primer orden: v = -CA/t = k1 CA - k2 CR k1 = 3,1107 e - 5850/T k2 = 1,71018e -14900/T

Curvas isocinticas: x = [k1(T)-v/CoA]/[k1(T)+k2(T)]

v = f (CoA, x, T)

Modelo cinticoEjemplo:Hoja de clculo

CoA = 1 mol/l3La temperatura de la alimentacin es: To = 20C y se desea lograr una conversin en el reactor del 80%:T = To + (q -Hr x)/Cp,mrlHr = -20 kcal/molCp = 1 kcal/lC

a) Reactor de mezcla completa:

El punto final de operacin debecoincidir con el lugar geomtrico develocidades mximas: vmax

b) Reactores de flujo de pistn:

La lnea de operacin se obtienebuscando una velocidad media en elreactor (adiabtico) que haga mnimoel tiempo de residencia: min

El calor intercambiado en cada caso se deduce del balance de energa:q = Hrx + Cp,mrl (T-To) a) q = +26,0 kcal/molA b) q = +34,0 kcal/molA

ab4La relacin entre la velocidad y la conversin a lo largo del reactor viene dada por: v = CoA [ k1 (1-x) - k2 x ]

A) Rgimen isotrmico (T = 62C)reactor de mezcla completa: = CoAx / v = 8,3 min

B) Rgimen adiabtico (To = 54C) reactor de flujo de pistn: = CoA x / v = 2,6 min

Vo = 1 m3/minVr = 8,3 m3q = +26 Mcal/min 20C62Cx = 0,80x = 0,80Vo = 1 m3/min20C54C70Cq = +34 Mcal/min Vr = 2,6 m35Anlisis de la estabilidad del `reactor de mezcla completa no isotrmicoUna vez dimensionado el reactor, los puntos de estado estacionario resultan de los balances:

(1) v (x,T) = CoA x / (2) x = Cp,mrl (T-To) / (q/xf -Hr)

con: CoA = 1 mol/l, = 8,3 min y q = 26 kcal/molA

Puede observarse que el rgimen estacionario es estable en estas condiciones operativas

Reactor de flujo de pistn `con recirculacin: = (R+1) x/v xo = Rxf /(R+1)

Permite un mejor control del proceso, a costa de mayor trasiego, energa y tamao del reactor

20C62C62Cxf = 0,80Vo = 1 m3/minVr =3,5 m3q = +42 Mcal/min qr = -16 Mcal/min R=1Xo=0,406

Datos y variables fijas (f)

Variables de estado (4)

Variables de diseo (5-f)

Ec. de diseo:

v (Co,x,T)

T (To,x,q)

( (Co,x,v)

Vr = (Vo

Grfico30.99980.86920.67330.3469-0.306-2.2648-5.5293-12.0584-31.6457-64.2912-129.58220.99960.91080.77760.55560.1116-1.2205-3.4405-7.8807-21.201-43.4017-87.8030.99930.93810.84630.69320.3872-0.531-2.0612-5.1218-14.3033-29.6059-60.21120.99880.9560.89190.78510.5715-0.0695-1.1378-3.2743-9.6839-20.3665-41.73180.99790.96770.92240.8470.6960.2432-0.5115-2.0208-6.5488-14.0956-29.1890.99650.97490.94260.88860.78080.4574-0.0817-1.1598-4.3943-9.7851-20.56660.99420.97860.95530.91640.83860.60520.2161-0.5619-2.896-6.7861-14.56640.99060.97920.96220.93390.87730.70730.4239-0.1427-1.8426-4.6758-10.34210.9850.97670.96420.94340.90180.7770.5690.153-1.095-3.1749-7.33490.97660.97050.96120.94590.91510.82290.66920.3618-0.5605-2.0976-5.17180.96410.95960.95270.94130.91850.850.73580.5076-0.1773-1.3187-3.60150.9460.94260.93750.9290.9120.8610.77610.60610.0962-0.7536-2.45310.92050.9180.91420.90790.89520.85730.7940.66750.2879-0.3447-1.60990.88570.88380.8810.87630.86690.83880.79180.69790.4163-0.0531-0.99180.83990.83850.83640.83290.8260.80530.77070.70150.4940.1482-0.54350.78210.78110.77960.77710.7720.75690.73170.68130.53010.278-0.22620.71290.71220.71110.70930.70570.69480.67670.64050.53190.3508-0.01140.63450.6340.63320.6320.62940.62170.60890.58340.50670.37880.1230.55070.55030.54980.54890.54710.54180.5330.51520.46210.37350.19630.46620.4660.46560.4650.46380.46020.45420.44210.4060.34570.22520.38580.38570.38540.3850.38420.38180.37780.36970.34550.30520.2246

v=0v=0,002v=0,005v=0,01v=0,02v=0,05v=0,1v=0,2v=0,5v=1v=2Temperatura, CConversin, xvelocidad (mol/lmin)

Hoja1Curvas isocinticas: x = [k1(T)-v/CoA]/[k1(T)+k2(T)]k1 = 3,11e7 exp( - 5850/T)k2 = 1,71e18exp(-14900/T)CoA = 1 mol/lVelocidad =2.000T (C)k1 (1/min)k2 (1/min)v (mol/lmin)x0.00.015310.000002.000-129.58225.00.022510.000012.000-87.803010.00.032650.000022.000-60.211215.00.046750.000062.000-41.731820.00.066110.000142.000-29.189025.00.092420.000332.000-20.566630.00.127780.000752.000-14.566435.00.174820.001662.000-10.342140.00.236790.003602.000-7.334945.00.317670.007612.000-5.171850.00.422330.015722.000-3.601555.00.556620.031762.000-2.453160.00.727550.062812.000-1.609965.00.943470.121762.000-0.991870.01.214220.231522.000-0.543575.01.551390.432172.000-0.226280.01.968480.792572.000-0.011485.02.481131.429102.0000.123090.03.107432.535342.0000.196395.03.868084.428362.0000.2252100.04.786757.620022.0000.2246

Hoja1000000000000000000000000000000000000000000

v (mol/lmin)xTemperatura (C)Conversin, xv (mol/l.min).

Hoja2T (C)v=0v=0,002v=0,005v=0,01v=0,02v=0,05v=0,1v=0,2v=0,5v=1v=20.00.99980.86920.67330.3469-0.3060-2.2648-5.5293-12.0584-31.6457-64.2912-129.58225.00.99960.91080.77760.55560.1116-1.2205-3.4405-7.8807-21.2010-43.4017-87.803010.00.99930.93810.84630.69320.3872-0.5310-2.0612-5.1218-14.3033-29.6059-60.211215.00.99880.95600.89190.78510.5715-0.0695-1.1378-3.2743-9.6839-20.3665-41.731820.00.99790.96770.92240.84700.69600.2432-0.5115-2.0208-6.5488-14.0956-29.189025.00.99650.97490.94260.88860.78080.4574-0.0817-1.1598-4.3943-9.7851-20.566630.00.99420.97860.95530.91640.83860.60520.2161-0.5619-2.8960-6.7861-14.566435.00.99060.97920.96220.93390.87730.70730.4239-0.1427-1.8426-4.6758-10.342140.00.98500.97670.96420.94340.90180.77700.56900.1530-1.0950-3.1749-7.334945.00.97660.97050.96120.94590.91510.82290.66920.3618-0.5605-2.0976-5.171850.00.96410.95960.95270.94130.91850.85000.73580.5076-0.1773-1.3187-3.601555.00.94600.94260.93750.92900.91200.86100.77610.60610.0962-0.7536-2.453160.00.92050.91800.91420.90790.89520.85730.79400.66750.2879-0.3447-1.609965.00.88570.88380.88100.87630.86690.83880.79180.69790.4163-0.0531-0.991870.00.83990.83850.83640.83290.82600.80530.77070.70150.49400.1482-0.543575.00.78210.78110.77960.77710.77200.75690.73170.68130.53010.2780-0.226280.00.71290.71220.71110.70930.70570.69480.67670.64050.53190.3508-0.011485.00.63450.63400.63320.63200.62940.62170.60890.58340.50670.37880.123090.00.55070.55030.54980.54890.54710.54180.53300.51520.46210.37350.196395.00.46620.46600.46560.46500.46380.46020.45420.44210.40600.34570.2252100.00.38580.38570.38540.38500.38420.38180.37780.36970.34550.30520.2246

Hoja2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000


Hoja3

Grfico21.23762376241.30975769481.39082058411.48257968871.58730158731.707941931.84842883552.01409869082.21238938052.45398773012.75482093663.13971742543.64963503654.35729847495.40540540547.117437722410.4166666667

CoA/vConversin, xRgimen isotrmico (T=62C).

Hoja1Curvas isocinticas: x = [k1(T)-v/CoA]/[k1(T)+k2(T)]k1 = 3,11e7 exp( - 5850/T)k2 = 1,71e18exp(-14900/T)CoA = 1 mol/lVelocidad =1.000T (C)k1 (1/min)k2 (1/min)v (mol/lmin)x0.00.015310.000001.000-64.29125.00.022510.000011.000-43.401710.00.032650.000021.000-29.605915.00.046750.000061.000-20.366520.00.066110.000141.000-14.095625.00.092420.000331.000-9.785130.00.127780.000751.000-6.786135.00.174820.001661.000-4.675840.00.236790.003601.000-3.174945.00.317670.007611.000-2.097650.00.422330.015721.000-1.318755.00.556620.031761.000-0.753660.00.727550.062811.000-0.344765.00.943470.121761.000-0.053170.01.214220.231521.0000.148275.01.551390.432171.0000.278080.01.968480.792571.0000.350885.02.481131.429101.0000.378890.03.107432.535341.0000.373595.03.868084.428361.0000.3457100.04.786757.620021.0000.3052

Hoja1000000000000000000000000000000000000000000



Hoja2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000


Hoja3isotrmico (T = 62C)adiabtico (To = 54C)xT (C)k1k2vCoA/vvCoA/v0.0054.00.52710.02760.80801.23760.52711.89730.0555.00.55660.03180.76351.30980.52721.89680.1056.00.58760.03650.71901.39080.52521.90400.1557.00.62020.04180.67451.48260.52091.91990.2058.00.65430.04790.63001.58730.51381.94610.2559.00.69010.05490.58551.70790.50381.98480.3060.00.72760.06280.54101.84840.49042.03900.3561.00.76680.07180.49652.01410.47332.11280.4062.00.80800.08200.45202.21240.45202.21250.4563.00.85110.09370.40752.45400.42602.34760.5064.00.89620.10680.36302.75480.39472.53360.5565.00.94350.12180.31853.13970.35762.79650.6066.00.99290.13870.27403.64960.31403.18520.6567.01.04460.15780.22954.35730.26303.80190.7068.01.09860.17950.18505.40540.20404.90250.7569.01.15520.20390.14057.11740.13597.36060.8070.01.21420.23150.096010.41670.057617.35340.8571.01.27590.26270.051519.4175-0.0319-31.35530.9072.01.34040.29780.0070142.8571-0.1340-7.46260.9573.01.40770.3374-0.0375-26.6667-0.2502-3.99741.0074.01.47800.3820-0.0820-12.1951-0.3820-2.6178

Hoja300000000000000000


00000000000000000

CoA/vConversin, xRgimen adiabtico (To=54C).

Grfico11.8972595341.89680067621.90395869711.91988577941.94613788861.98484473312.0389756662.11277103312.21247269372.3476271282.53356303122.7964962263.1852095153.80188667174.90252939457.360596144317.3533848981



Hoja1000000000000000000000000000000000000000000



Hoja2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000



Hoja300000000000000000


00000000000000000


Grfico20.0228257269-200.0352750712-150.0532722384-100.0785209173-50.112760776400.157428549850.213187647100.2794430093150.354051867800.43343819130.09523809520.51315476780.19047619050.58868763820.28571428570.65615608150.3809523810.7126464570.47619047620.75614605720.57142857140.78523551620.66666666670.79876382770.76190476190.79569666420.85714285710.77525271620.95238095240.737337645750.6831357246800.61555591850.5391797353900.4595599733950.3821068855100

x (1)x (2)Temperatura, T(C)Conversin, xBalances de materia (1) y energa (2)


Hoja1000000000000000000000000000000000000000000



Hoja2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000


Hoja3isotrmico (T = 62C)adiabtico (To = 54C)xT (C)k1k2vCoA/vtvCoA/vt0.0054.00.52710.02760.80801.23760.0640.52711.89730.0950.0555.00.55660.03180.76351.30980.0680.52721.89680.0950.1056.00.58760.03650.71901.39080.0720.52521.90400.0960.1557.00.62020.04180.67451.48260.0770.52091.91990.0970.2058.00.65430.04790.63001.58730.0820.51381.94610.0980.2559.00.69010.05490.58551.70790.0890.50381.98480.1010.3060.00.72760.06280.54101.84840.0970.49042.03900.1040.3561.00.76680.07180.49652.01410.1060.47332.11280.1080.4062.00.80800.08200.45202.21240.1170.45202.21250.1140.4563.00.85110.09370.40752.45400.1300.42602.34760.1220.5064.00.89620.10680.36302.75480.1470.39472.53360.1330.5565.00.94350.12180.31853.13970.1700.35762.79650.1500.6066.00.99290.13870.27403.64960.2000.31403.18520.1750.6567.01.04460.15780.22954.35730.2440.26303.80190.2180.7068.01.09860.17950.18505.40540.3130.20404.90250.3070.7569.01.15520.20390.14057.11740.4380.13597.36060.6180.8070.01.21420.23150.096010.41672.4130.057617.35342.6280.8571.01.27590.26270.051519.4175-0.0319-31.35530.9072.01.34040.29780.0070142.8571-0.1340-7.46260.9573.01.40770.3374-0.0375-26.6667-0.2502-3.99741.0074.01.47800.3820-0.0820-12.1951-0.3820-2.6178

Hoja300000000000000000

CoA/vConversin, xRgimen isotrmico (T = 62C).

Hoja400000000000000000

CoA/vConversin, xRgimen adiabtico (To = 54C).

Anlisis de estabilidad: reactor de mezcla completa (t = 8,3 min)Conversin, x =0.80q (kcal/molA) =26.0T(C)k1k2x (1)x (2)-20.00.00281430.000000050.0228Balance de materia: v(x,T) = Cox(1)/t-15.00.00440540.000000140.0353Balance de energa: x(2) = Cp(T-To)/(q/x-DHr)-10.00.00677950.000000420.0533-5.00.01026660.000001220.07850.00.01531270.000003370.11285.00.02251290.000008980.157410.00.03265100.000023160.213215.00.04674710.000057780.279420.00.06611410.000139690.3541025.00.09242340.000327890.43340.095230.00.12778160.000748260.51320.190535.00.17481820.001662450.58870.285740.00.23678610.003600530.65620.381045.00.31767430.007610810.71260.476250.00.42233460.015719220.75610.571455.00.55662250.031756140.78520.666760.00.72755200.062813530.79880.761965.00.94346640.121762810.79570.857170.01.21422280.231523640.77530.952475.01.55139250.432171820.737380.01.96847630.792572100.683185.02.48113381.429104740.615690.03.10742772.535340550.539295.03.86808144.428360790.4596100.04.78674987.620021780.3821

00000000000000000000000000000000000000000000000000

x (1)x (2)Temperatura, T(C)Conversin, xBalances de materia (1) y energa (2)

Grfico21.23762376241.30975769481.39082058411.48257968871.58730158731.707941931.84842883552.01409869082.21238938052.45398773012.75482093663.13971742543.64963503654.35729847495.40540540547.117437722410.4166666667



Hoja1000000000000000000000000000000000000000000



Hoja2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000



Hoja300000000000000000


00000000000000000


Date post:	04-Oct-2015
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