Question

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8.25 Sulfur dioxide is converted to sulfur trioxide by oxidation over a V20, catalyst at atmospheric pressure. In the reactor configuration shown in Figure P8.25, SO2 and O2 avalable at 300°C and 25°C, respectively, are preheated to 425°C and fed in stoichiometric ratio to the reactor. Conversion is 96% and, to keep the reactor temperature from rising too much, 10 kcal/g-mol of com bined feed is removed by external medium. The last heat exchanger in the process is used to generate 300 psia steam by cooling down the reactor effluent to 400C. Calculate all unknown temperatures and flows. Assume no heat losses to the environment. Given C, (cal/gmol °C) SO2 So, Avg Cp, 25-425°C Avg Cp, 300-900°C 7.6 10.4 15.3 7.8 11.8 17.2 Saturated Steam, 300 psia so2 300 °C Heat exchanger 10 kcal/gmol Boiler 425 °C 400 °c SO2 425 °C Reactor O2 Heat exchanger O2 25 °C Sat water 300 psia Figure P8.25

Answer 1

Anscen he prcblem the Pigue given Considen in Satuoatel Sea m So2 300'c Heat Catchangen ic Kcal 42sc 9 Reaicen 42s 'c Heat eschangen Sal anten 3co PSia Caleulake boansfegn in heat echagen 1. heat the x AT (425-300) cal /emok 1300 13 kcal /gmek bempenatusre of so2. Hene AT is change irn heat bonansfeg in heat excharg= Similanly, calailabe the Gie 1 cal /gmek : 3040 kal/gmel 3.04 Find the latent heat of vaponization f the calesn at usirg Salusnatel steam table. 300 Psia

kal /kg 449, 656 kal/g ニ0449 O449 IS kalAmok kal/gmel 81082 - Theanefone, heat asfein last heat cechargen is kal /amol 8.082 Calaulate the tempeauene he 9nacton efflue nt enbesring the last heat exchangen using heat balane cefe T-400) Hene the avesageof the specific heats af Soe, Og and tempenatuse ef fluent SC3, and T3 is last enkesing heat exchangen. in Calculale avesage of the spexfie heats 7.8+8 +17. 2 C)epf 12.27 cal /grol_°c the value f Cep)eff Substitute and &in equabion ー400 8,082= 12.27メ( 400 660

the tempesnatUNe entenirg în Similaslcakeulate eachangen 2 heat Cepeff CTe-Ts) values Substitute expncssion the inatove 3.0l4 12.27T-400 66 400 908C Simi Lasnky cal culate the lempenakue ef effluen heat eachanges) 1 entening the Cpe LT-Te) in abeve exPNession. Substitute the values 3 12,27 LT, -400.908 T 40O14 C the empegalu re of effluent atering in heat Hence exchangens ,2 and T 401.0I4C Te 4006600 heat exchangons The hea t floas in 2 and 3 aIC 3 Kal gmo 3.04 kcal /gmok e