Split_00076 - 9 76c ΔΔ¡(¢)¢¢.¡HHn Hn Hmmiiiiww=...

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Unformatted text preview: 9- 76c. ΔΔ¡¡(¢)¢¢..¡HHn Hn Hmmiiiiww=+−=⇒FHGIKJFHGIKJ−FHGIKJ+×+FHGIKJLNMOQP−LNMOQP=⇒×∑∑ξcoCHoutin54450 kmolhmolkmolkJmolkJhkghkJkg= 1.32 10 kg steam / h1000890 362 99 102914 1057bgEnergy balance on preheater:ΔΔΔ¡¡¡HHH=+=didistack gasair0 ΔΔHnCTpbgbgstack gas35590 kmol 10 mol0.0315 kJCh1 kmolmolCkJh==−⋅= −×150 3002 64 107DD.−==⇒=×==ΔΔHHnHTHTHTaaaabgbgstack gasairairair3airTable B.8okJ / hkmolkmol / h10 mol= 5.133 kJmolkJ / mol C¢()¢().¢.2 64 101514351331997The energy balance on the furnace includes the term −∑n Hinin¢. If the air is preheated and the stack gas temperature remains the same, this term and hence¡Qbecome more negative, meaning that more heat is transferred to the boiler water and more steam is produced. The stack gas is a logical heating medium since it is available at a high temperature and costs nothing. 9.61 a. Assume coal enters at 25 C3Basis: 40000 kg coal hkg C 10 g 1 mol Ch1 kg12.01 gmol C h°⇒×=×0 76 400002531 10...
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