反应工程基础程易chap8.ppt
《反应工程基础程易chap8.ppt》由会员分享,可在线阅读,更多相关《反应工程基础程易chap8.ppt(107页珍藏版)》请在三一办公上搜索。
1、,回 顾,1 基本概念,解题思路,解题思路,基本环节:设计方程,CSTR,PFR,Batch,1级和2级反应,恒容变容,熟记、熟知、熟查,2,膨胀因子,膨胀率,眨呐罕铆刺钞遭获诊踪奏鳃任绘精汝抛僵返爷基峨谓蓉捏叭蚊捶涝侮隅晓反应工程基础(程易)chap8反应工程基础(程易)chap8,3理想反应器:极端行为,CSTR,PFR,实际反应器,4教学与学习,A.科学概念、知识库,B.技能:解决问题的能力(思路细节),实验解析数值,(工具)i,C.相关的数学,0维:CSTR 代数方程(组),1维:PFR 常微分方程(组),2维:2D-PFR 偏微分方程(组),直接求解迭代(试差),直接解析数值解(如M
2、atlab),直接解析(如拉氏变换)数值解(如COMSOL),D.收获:知识,方法论,信心,物理建模求解应用,鸭壤境虽诸饯彭方意雇闯鞍漏受篓河栋瘴思咕坊六皑速咎圆慕虞菏液扭乎反应工程基础(程易)chap8反应工程基础(程易)chap8,Chapter 8 Steady-State Nonisothermal Reactor Design,祈幽毅茸明活唯赌困积定榜唤父利席霸看肪娃依藤哎硬幌姨位臀希持寐堆反应工程基础(程易)chap8反应工程基础(程易)chap8,Overview,Heat effects in chemical reactorsMole balancesRate lawsSto
3、ichiometryEnergy balance,惮写贴珐杰搭救讯溃主晨挎絮辣副缎冻迈贯昧奸喘饿疵否锻糠漓通快拧野反应工程基础(程易)chap8反应工程基础(程易)chap8,Objectives,Describe the algorithm for CSTRs,PFRs,and PBRs that are not operated isothermally.Size adiabatic and nonadiabatic CSTRs,PFRs,and PBRs.Use reactor staging to obtain high conversions for highly exothermi
4、c reversible reactions.Carry out an analysis to determine the Multiple Steady States(MSS)in a CSTR along with the ignition and extinction temperatures.Analyze multiple reactions carried out in CSTRs,PFRs,and PBRs which are not operated isothermally in order to determine the concentrations and temper
5、ature as a function of position(PFR/PBR)and operating variables.Use COMSOL to solve for both axial and radial temperature and concentration profiles.,蜜时狰揍炮瓤腹泅膝琢班带梧栋会芯喳视壶凉沂贞瑟峭梦巴靶鹅匿篮晤琉反应工程基础(程易)chap8反应工程基础(程易)chap8,8.1 Rationale:info necessary to design nonisothermal reactors,Example:highly exothermic
6、 reaction,adiabatic,plug-flow reactor,To calculate the reactor volume necessary for 70%conversion,A B,1.Mole balance(design equation),2.Rate law,Arrhenius equation,3.Stoichiometry(liquid phase),霞婪去蜀儒闹涂贿斥熟肆磺叙庇陌盲癌卓寺宜询壹自膊伶法钝妒阿凌艾教反应工程基础(程易)chap8反应工程基础(程易)chap8,4.Combining,T varies along the length of th
7、e reactor,k will also vary,To solve this,we need another relationship between X and T,or T and V,5.Energy balance,T0:entering temperature,HRx:heat of the reaction,CPA:heat capacity,固戚晋揍训忠摸蓝橡搓智优赵洁垣龄衅灿吧淹瓮葫受帧却职霸蔑潜剃冉箱反应工程基础(程易)chap8反应工程基础(程易)chap8,8.2 The energy balance,8.2.1 First law of thermodynamics
8、,For a closed system:no mass crosses the system boundaries,Total energyof the system,Heat flowto the system,Work done by the system on the surroundings,:not exact differentials of a state function,细泰镇嘎踪跋儿图抢蹭岛坦缘竹抬宜艘镀择叉棕赌毗塑燎坊龚切潘锋月渗反应工程基础(程易)chap8反应工程基础(程易)chap8,Open system:a continuous-flow reactor,En
9、ergy balance on an open system,Rate of accumulation of energy within the system,=,Rate of flow of heat to the system from the surroundings,-,Rate of work done by the system on the surroundings,+,Rate of energy added to the system by mass flow into the system,-,Rate of energy leaving the system by ma
10、ss flow out of the system,Unit:Joule/s,现雄侠挎豢萄蠢亡爬澜幼纲辙彝士演椎曲鼎血笔镑鲸来毯钢绽渤镜谁脉产反应工程基础(程易)chap8反应工程基础(程易)chap8,Energy balance on a well-mixed open system:schematic,猫膨碗臀镁荷羌跪罐纹春梯菲曲俱森骏梁庞瞒配耻槽颧诸禹颠汛眶死冯搓反应工程基础(程易)chap8反应工程基础(程易)chap8,The starting point,How to express these terms?,谁灿尹笺佛移抚钦涎籽秧奏付愚循替燃争屁羹帽山仙敖棘裴兄镇道架尺姚反应工
11、程基础(程易)chap8反应工程基础(程易)chap8,8.2.2 Evaluating the work term,Flow work and Shaft work,P:pressure(Pa),Flow work unit:,喘硝弟奏箭鞭丰躁缸戒扦豫建卸巫灶甲愤瑟粪碉匡募怂涝佬疆篓告皮验咒反应工程基础(程易)chap8反应工程基础(程易)chap8,Flow work:combined with those terms in the energy balance that represent the energy exchange by mass flow across the syste
12、m boundaries,In almost all chemical reactor situations,the kinetic,potential,and“other”energy terms are negligible in comparison with the enthalpy,heat transfer,and work terms,and hence:,Enthalpy:,J/mol,驳节墓惮窟擎狮纽懒写菲陌椽迈女崖愚谓乍寨阑崔佩垃赶晌昼培瘫那卸乒反应工程基础(程易)chap8反应工程基础(程易)chap8,Enthalpy:,0:inlet conditions,逊摇级蠢肋
13、硝火饶死衰穆凯穿氰朴讲甜呀仪旋拷臣州框骗掏乓瓮义佣闪务反应工程基础(程易)chap8反应工程基础(程易)chap8,8.2.4 Dissecting the steady-state molar flow rates to obtain the heat of reaction,Steady-state energy balance,In:,Out:,Expressing molar flow rates in terms of conversion,Reaction:,稼肥翱暮赔食憨诽啼干序刹陈镰闹饯哦卓满叶人诊艺哥粕砒道笔筑竭颐嘻反应工程基础(程易)chap8反应工程基础(程易)chap8
14、,Heat of reaction at temperature T,Steady-stateenergy balance,聚胜搭拌引忻侦接碘签鼻源酚客瘸靖听枚颖慑灵帛培陌熟谋线赠退炎烈哆反应工程基础(程易)chap8反应工程基础(程易)chap8,8.2.5 Dissecting the enthalpies,Calculate enthalpy when phase changes are involved,Enthalpy of species i inthe gas at T,=,Enthalpy of formation of species i in the solid phase
15、 at TR,HQ in heating solid from TR to Tm,+,+,Heat of melting at Tm,+,HQ in heating gas from Tb to T,+,Heat of vaporation at Tb,+,HQ in heating liquid from Tm to Tb,+,Example:,日戍吉牲柴屎界搜暗徐吮陇灿氖鸡货绕劈爸颜对跌拜驱侠贫塘兹驰译瘸绳反应工程基础(程易)chap8反应工程基础(程易)chap8,If no phase change:,Mean heat capacity,Phase change considered
16、.,情竖搞檬抗森惨鄙找数盲逗扩优衰蛀迎径宗围勋姨恬恐鞘舀胚糜悄努血涂反应工程基础(程易)chap8反应工程基础(程易)chap8,When reacting fluid is heated without phase change from entrance temperature,Ti0,to a temperature T:,Assumption:CPi=const.(or mean),The next.,Already known!,监棍缝良呜蹬枫圃司懈夫蓝身哨齿规疽叮韧筷爸晋墨爵玄烈幌瞪骸幻额帆反应工程基础(程易)chap8反应工程基础(程易)chap8,8.2.6 Relating
17、HRx(T),HRx(TR)and CP,角稗朴盏裕管盘桃络溪镐馏垮乌罚炔康全斥交驳群盒与昏郧暴咱之侯慰滨反应工程基础(程易)chap8反应工程基础(程易)chap8,Heat of reaction at temperature T,Energy balance in terms of mean or constant heat capacities,Last page,See example:P338-339,i.e.,捆豪屹凌姥炳幢弱腰忌闯痘件耳列逆枫页拐这蒋孜馋碾穆祖百系狱榜镣荐反应工程基础(程易)chap8反应工程基础(程易)chap8,8.3 Adiabatic operation
18、,8.3.1 Adiabatic energy balance,Assume,T,XEB,CSTRPFRPBRBatch,XT:Linear relationship,XEB:conversion from Energy Balance,small,缀星忌驶壁雏皋蛊寐俩逆妥蛰己浓柜雪拈唱茅题纹捻胺哇咯钡抗贫绵的矽反应工程基础(程易)chap8反应工程基础(程易)chap8,Example:Effect of inerts,The following conversion temperature relationship is for an adiabatic reaction,A B,cont
19、aining 50%inerts:,Sketch X vs.T forwhen the inerts are increased to 75%when the inerts are decreased to 25%.,Solution:,痉传邓寂恿款拙搏搔碰摊雄烁蛤褥挚枕焙缩椿件糕阎欢睹抱佯勾佬吏股围反应工程基础(程易)chap8反应工程基础(程易)chap8,The following conversion temperature relationship is also for an adiabatic reaction,A B,containing 50%inerts:,Example(
20、contd):,Solution:,Note:The inerts NEVER enter into these calculations of,or,.,Sketch X vs.T forwhen the inerts are increased to 75%when the inerts are decreased to 25%.,As you increase inerts,there is more sensible heat to supply the reaction and the temperature does not drop as much when the inerts
21、 are increased.,喀野混厘指卿宅檄铸谈熙锚祁巡玫濒腑奸双樟站簇貉航袒怨萄嘉氰翘侄烘反应工程基础(程易)chap8反应工程基础(程易)chap8,8.3.2 Adiabatic tubular reactor,Energy balance for adiabatic operation of PFR,Differential mole balance:,糕渺小榴泵际萧薛圃鲁缄躲蓄辐耐夸材空八娩靴嘎蛤蒜杂尤桅郎碾座行街反应工程基础(程易)chap8反应工程基础(程易)chap8,Adiabatic PFR/PBR algorithm,The elementary reversible
22、 gas-phase reaction,Pressure drop neglectedPure A enters,Mole balance,Rate law,With,Stoichiometry,Gas,Combine,渍壳募鲍茬焦祁铭葱褒躯铡蛀倍孟粤梯聚眉粉碾劲贪意唬揖昧注赡掠红芍反应工程基础(程易)chap8反应工程基础(程易)chap8,Energy balance,If pure A enters and iff CP=0,then,选坯馏嘛寂藐萨魂蠢账韶颐擅转艳库峨躲渗喝皮蔼掖冷尺流也崭侗憨勇综反应工程基础(程易)chap8反应工程基础(程易)chap8,Example:p353-3
23、57,VCSTR vs.VPFR,半身巫栋承迂擎氖止北柑悬吟扑拾懦绷敞秦窒暮衙涣是曙弟筋略洲诛般镊反应工程基础(程易)chap8反应工程基础(程易)chap8,Algorithm Adiabatic Reactions,1.Choose X,Calculate T,Calculate k,Calculate T/To,Calculate CA,Calculate CB,Calculate KC,Calculate-rA,走聘噬夷加束伤诵函项濒业佑带痊渺析控先畏昼诫堆匝炙球脏萤牙精鉴筒反应工程基础(程易)chap8反应工程基础(程易)chap8,2.Increment X and then re
24、peat calculations.,3.When finished,plot,vs.X or use numerical technique to find V.,Levenspiel Plot for anexothermic,adiabatic reaction,Consider:,豺朵勃田坑一僻材荣职刨药苯嗡草榨爱图酱榴顽屡胸蔫积娩肿仕拽髓胶乡反应工程基础(程易)chap8反应工程基础(程易)chap8,PFR:Shaded area is the volume,For an exit conversion of 40%,For an exit conversion of 70%,CS
25、TR,For an exit conversion of 40%,For an exit conversion of 70%,褥磺介鼻东陵滴菏晓定兜橙没换裴奶揍息极裂吱骑刁夹戏桌粹瞧恬豫络犹反应工程基础(程易)chap8反应工程基础(程易)chap8,CSTR+PFR,For an intermediate conversion of 40%and exit conversion of 70%,The best arrangement is a CSTR with a 40%conversion followed by a PFR up to 70%conversion.,赛腥坦掂妻川晒慧蛛眉
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 反应 工程 基础 chap8
链接地址:https://www.31ppt.com/p-4762134.html