Heat Integration Chapt. 10. Costs Heat Exchanger Purchase Cost – C P =K(Area) 0.6...

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Transcript of Heat Integration Chapt. 10. Costs Heat Exchanger Purchase Cost – C P =K(Area) 0.6...

  • Heat IntegrationChapt. 10

  • CostsHeat Exchanger Purchase Cost CP=K(Area)0.6Annual CostCA=im[Cp,i+ CP,A,j]+sFs+(cw)Fcwim=return on investmentFs= Annual Flow of Steam, $5.5/ston to $12.1/stonFcw=Annual Flow of Cold Water$0.013/ston

  • Lost Work = Lost MoneyTransfer Heat from T1 to T2T approach Temp. for Heat ExchangerTo= Temperature of EnvironmentUse 1st and 2nd laws of Thermodynamics

    LW=QToT/(T1T2)T1T2Q

  • Minimize UtilitiesFor 4 Streams

  • Simple HEN

  • Adjust Hot Stream Temperatures to Give Tmin

  • Enthalpy Differences for Temperature Intervals

  • Interval Heat Loads

  • Pinch Analysis

    Minimum Utilities

  • Pinch Analysis

  • 4 Heat ExchangerHEN for Min. Utilities

  • Minimum Utilities HEN

  • Too Many Heat ExchangersSometimes fewer Heat exchangers and increased utilities leads to a lower annual costNHx,min= Ns + NU - NNWNo. streamsNo. discrete UtilitiesNo. independent Networks (1 above the pinch, 1 below the pinchSolution to Too Many Heat ExchangersBreak Heat Exchanger LoopsStream SplittingAttack small Heat Exchangers First

  • Break Heat Exchanger Loops

  • Example

  • Change TminCP=K(Area)0.6

    Area=Q/(UF Tmin)

  • Distillation Columns

  • Position a Distillation Column Between Composite Heating and Cooling Curves

  • Heat Integration

  • Multi-effect DistillationAdjust Pressure in C2 for Tmin

  • Heat Pumps in Distillation