過(guò)程裝備優(yōu)化設(shè)計(jì)：熱集成基礎(chǔ)理論

1、過(guò)程裝備優(yōu)化設(shè)計(jì)2 熱集成基礎(chǔ)理論夾點(diǎn)的意義The Heat Recovery Pinch2.4 夾點(diǎn)的意義在T-H圖上分別作出冷、熱流股組合曲線(xiàn)；熱流股在上、冷流股在下，兩者在水平方向相互靠攏，直至組合曲線(xiàn)在某處的垂直距離等于Tmin2.4 夾點(diǎn)的意義TminQH,min，QC,minQR,max2.4 夾點(diǎn)的意義夾點(diǎn)將系統(tǒng)分為熱端和冷端。熱端在夾點(diǎn)溫度以上，只需要公用工程加熱(熱阱)冷端在夾點(diǎn)溫度以下，只需要冷公用工程冷卻(熱源)夾點(diǎn)處熱流量為 0What happens if we transfer heat across the pinch?2.4 夾點(diǎn)的意義2.4 夾點(diǎn)的意義2.4

2、夾點(diǎn)的意義2.4 夾點(diǎn)的意義The 3 Components of Cross Pinch Heat FlowAll three types results in increased hot and cold utility requirements!Do not transfer heat across the pinch:Process-to-processInappropriate use of UtilitiesSummary夾點(diǎn)處，系統(tǒng)的傳熱溫差最?。ǖ扔赥 min ），系統(tǒng)用瓶頸位置；夾點(diǎn)處熱流量為 0 ，夾點(diǎn)將系統(tǒng)分為熱端和冷端兩個(gè)子系統(tǒng)，熱端在夾點(diǎn)溫度以上，只需要公用工程加熱（

3、熱阱冷端在夾點(diǎn)溫度以下，只需要公用工程冷卻（熱源）；在一定的T min下，確定了系統(tǒng)最小的公用工程加熱負(fù)荷QH min 和系統(tǒng)最小的公用工程冷卻負(fù)荷QC min ，以及最大的熱回收量QR,max ； 夾點(diǎn)處溫度差的影響 T min大，QH, min、QC min 增大QR,max減小。Summary系統(tǒng)具有最低公用工程消耗以及最大熱回收的原則熱量不能穿透夾點(diǎn)夾點(diǎn)上方不能設(shè)置公用工程冷卻夾點(diǎn)下方不能設(shè)置公用工程加熱 夾點(diǎn)上方 熱阱 夾點(diǎn)下方 熱源夾點(diǎn)QH,min+xQC,min+x 夾點(diǎn)上方 熱阱 夾點(diǎn)下方 熱源QH,min+yQC,miny 夾點(diǎn)上方 熱阱 夾點(diǎn)下方 熱源QH,minQC,mi

4、n+zzx格子圖The Grid Diagram2.5 格子圖2.5 格子圖2.5 格子圖The pinch is much more clearly shown on:“The Grid Diagram”Which only shows heat transfer operations2.5 格子圖2.5 格子圖Rules for Construction:Hot streams run left to rightCold streams run right to leftHot streams on top; cold streams on bottomHot utility = Cold

5、 utility = Heat exchanger between streams =HCHot 1Hot 2Cold 3Cold 41234CH180801304010060301204985200012003603240Tmin=10Where the pinch?Are 1200 units of steam really necessary?2.5 格子圖T*pinch=65。熱流股：Tpinch=70；冷流股：Tpinch=60QH,min=9602.5 格子圖Hot 1Hot 2Cold 3Cold 4CH18080130401006030120498520001200360324

6、0T*pinch=65。熱流股：Tpinch=70；冷流股：Tpinch=602.5 格子圖Hot 1Hot 2Cold 3Cold 4CH180801304010060301204985200012003603240T*pinch=65。熱流股：Tpinch=70；冷流股：Tpinch=60Pinch2.5 格子圖合理的換熱網(wǎng)絡(luò)結(jié)構(gòu)，無(wú)熱量穿越夾點(diǎn)。2.5 格子圖格子圖與傳統(tǒng)HEN流程圖格子圖與傳統(tǒng)HEN流程圖格子圖與傳統(tǒng)HEN流程圖SummaryThe Grid DiagramCleary see the implications of the pinchFollow the most c

7、omplex design evolution without ever re-routing streams3 最大熱回收換熱網(wǎng)絡(luò)設(shè)計(jì)Heat Exchanger Network Design For Maximum Energy Recovery3. 最大熱回收HEN設(shè)計(jì)Rules so far:No exchanger has a temperature difference TminNo process to process heat transfer across the pinchNo heat transfer across pinch by inappropriate use

8、of utilities3. 最大熱回收HEN設(shè)計(jì)組合曲線(xiàn)T*pinch=145。熱流股：Tpinch=150；冷流股：Tpinch=140格子圖分離換熱過(guò)程熱阱，吸收熱量只需要熱公用工程加熱熱源，放出熱量只需要冷公用工程冷卻No heat across夾點(diǎn)上方Match is infeasible!夾點(diǎn)上方Above the pinch, if CPHCPC Match is feasible夾點(diǎn)下方Below the pinch, if CPHCPCMatch is feasible匹配換熱匹配換熱匹配換熱匹配換熱This match violates CP rules已經(jīng)遠(yuǎn)離夾點(diǎn)，溫位可

9、行。(必須檢查傳熱溫差約束)匹配換熱匹配換熱匹配換熱匹配換熱匹配換熱Summary Pinch design methodDivide at the pinchStart at the pinch and move awayAbove pinch CPHCPCCP table identifies essential matchesUse the “tick-off” heuristic to maximize loadsThen fill the restThe Grid DiagramWorking SessionWorking Session1234T=10, T*pinch=65熱流股：Tpinch=70冷流股：Tpinch=60Working SessionHot 1Hot 2Cold 3Cold 418080130401006030120Above PinchCPHCPC4036CP20408036CP40