分離過(guò)程典型例題

1、典型例題-計(jì)算題1 .第一脫甲烷塔的進(jìn)料組成及操作條件下各組分的相平衡常數(shù)如下表所示,要求甲烷的蒸出率為98%,乙烯的回收率為96%,試分別按清楚分割和不清楚分割方法計(jì)算儲(chǔ)出液和釜液的組成,并比擬兩種計(jì)算結(jié)果.序號(hào)1234567組分H2CH4C2H4C2H6C3H6C3H8C4XiF/摩爾33.85.833.225.70.500.200.70Ki/1.70.280.180.0330.0220.004解：取100Kmol進(jìn)料為基準(zhǔn),選取甲烷為輕關(guān)鍵組分,乙烯為重關(guān)鍵組分.按清楚分割的概念,組分1為輕組分,全部從塔頂儲(chǔ)出液在采出,組分4、5、6、7為重組分,全部從塔釜液中采出.由于甲烷的蒸出率為9

2、8%D25.80.985.684Kmol;B25.85.6840.116Kmol乙烯的回收率為96%B333.20.9631.872Kmol.D333.231.8721.328KmolDD1D2D333.85.6841.32840.812KmolBFD10040.81259.188Kmol或B7Bi0.11631.872：25.70.500.300.7059.188Kmoli2Di33.80.828；X2DD25.6840.139X1DD40.812D40.812X3DD31.3280.033D40.812B20.1160.002B331.8720.538X2BX3BB59.188；B59.1

3、88B425.700.434；B50.500.008X4BB59.188X5BB59.188B60.300.005；B70.700.012X6BB59.188X7BB59.188將計(jì)算結(jié)果列表如下:組分ZiXiDXiBDiBiH20.3380.828/33.8CH40.580.1390.0025.6840.116C2H40.3320.0330.5381.32831.872C2H60.257/0.434/25.70C3H60.005/0.008/0.50C3H80.003/0.005/0.30C40.007/0.012/0.701.0001.0001.00040.81259.188不清口分割k料

4、衡算由iH請(qǐng)計(jì)算各組分的相對(duì)揮發(fā)度,結(jié)果列表序號(hào)1234567組分H2CH4C2H4C2H6C3H6C3H8C4XiF/摩爾33.85.833.225.70.500.200.70Ki/1.70.280.180.0330.0220.004ai3/6.0711.00.6430.1180.0790.014D2B35.68431.8721lglgNmD3B21.3280.1163.92lg23lg6.071由于氫氣的相對(duì)揮發(fā)度很大,該組分全部從塔頂儲(chǔ)出液中采出.由曳iNmD和FiDiBi分別計(jì)算組分4、5、6、7的分布.BiB3對(duì)組分4:-D4:mS0.6433.921.3280.0074；而25.7

5、D4B4B4B331.872由此計(jì)算得D40.189;B425.511對(duì)組分5：Di5mD-0.1183.92jj28_0.00001;而0.5D5B5B5B331.872由此計(jì)算得D50.0；B50.50將計(jì)算結(jié)果列表如下：組分ZiXiDXiBDiBiH20.3380.824/33.8CH40.580.1390.0025.6840.116C2H40.3320.0320.5401.32831.872C2H60.2570.0050.4320.18925.511C3H60.005/0.008/0.50C3H80.003/0.005/0.30C40.007/0.012/0.701.0001.0001

6、.00041.00158.9992 .要求在常壓下別離環(huán)己烷a.沸點(diǎn)80.8C和苯b.沸點(diǎn)80.2C,它們的包沸組成為苯0.502摩爾分?jǐn)?shù),共沸點(diǎn)77.4C,現(xiàn)以丙酮為恒沸劑進(jìn)行恒沸精儲(chǔ),丙酮與環(huán)己烷形成恒沸物,共沸組成為0.60環(huán)己烷摩爾分?jǐn)?shù),假設(shè)希望得到幾乎純潔的苯,試計(jì)算：所需恒沸劑量.塔頂、塔釜儲(chǔ)出物量各為多少.以100kmol/h進(jìn)料計(jì)解：以100kmol/h進(jìn)料為基準(zhǔn),設(shè)丙酮包沸劑的用量為Skg,恰好與料液中的環(huán)己烷組成恒沸物,進(jìn)料量和塔頂包沸物的量和組成分別為F,D,xFi,xDioD對(duì)環(huán)己烷作物料平衡DxdiFxfi;Fxfi1000.498XD10.6083kmol恒沸劑S的

7、用量為SDXD3830.40332kmol由于塔釜希望得到幾乎純潔的苯,WW2FXF2100.50250.2kmol3 .甲醇a.-丙酮b.在55.7C時(shí)形成恒沸物,其恒沸組成為Xi0.198,水和苯均可作為萃取劑進(jìn)行萃取精儲(chǔ)以別離甲醇和丙酮,試通過(guò)計(jì)算確定水c.與苯d.的選擇度,并據(jù)理說(shuō)明哪種萃取劑更佳及塔頂儲(chǔ)出液各為何種物質(zhì)？：XS0.8mol；A120.2798；A210.2634；A130.3794；A310.2211；A230.9709；A320.5576；A140.8923；A410.7494；A240.2021；A420.1533解：以水作萃取劑A12A21)0.27980.26

8、340.2716A1S2(A1SAs1)0.37940.22110.3002A2S2(A2SAS2)0.97090.55760.7643lgS12XsAsA2sA12(12x1)0.80.30020.76430.2716(120.198)0.5025S120.3144以苯作萃取劑,A1s12(A1SAS1)0.89230.74940.82085A2S(A2sAS2)0.20210.15330.17725lgS12XsA1sA2sA12(12X1)0&0.820850.177250.2716(120,198)0.3836S122.4191以苯作為萃取劑進(jìn)行萃取精微別離甲醇和丙酮更佳,而水

9、作為萃取劑比不參加萃取劑時(shí)的效果更差.由于甲醇的沸點(diǎn)64.7C高于丙酮55.7C,那么塔頂儲(chǔ)出物為丙酮,塔釜儲(chǔ)出物為甲醇和苯.4 .乙酸甲酯a,和甲醇b,混合物在45c時(shí)為恒沸物,今以水為溶劑進(jìn)行萃取精儲(chǔ),其組成為X10.7,xs0.8;A120.447;A210.411;A131.3;A310.82;A230.36;A320.22.試求其選擇度,并說(shuō)明塔頂儲(chǔ)出何物？解:A12一(A122A21)0.4470.4110.429Ais12(A1SAsi)1.30.821.062A2slgS121一(A2s2xsA1sAs2)0.360.220.292A12(12x1)0.81.060.290.4

10、29(120.7)0.7533S125.6661由于甲醇的沸點(diǎn)64.7C低于乙酸甲酯C,那么塔頂儲(chǔ)出物為甲醇酮,塔釜儲(chǔ)出物為乙酸甲酯和水.5.某裂解氣組成如下表所小.組分H2CH4C2H4C2H6C3H6i-C4H10Ey.0.1320.37180.30200.0970.0840.01321.000現(xiàn)擬以i-C4H10微分作吸收劑,從裂解氣中回收99%的乙烯,原料氣的處理量為100kmol/h,塔的操作壓力為4.052Mpa,塔的平均溫度按-14C計(jì),求:為完成此吸收任務(wù)所需最小液氣比.操作液氣比假設(shè)取為最小液氣比的1.5倍,試確定為完成吸收任務(wù)所需理論板數(shù).各個(gè)組分的吸收分率和出塔尾氣的量和

11、組成.塔頂應(yīng)參加的吸收劑量.解：選乙烯為關(guān)鍵組分,查得在4.052Mpa和-14C下各組分的相平衡常數(shù)列于下表.a最小液氣比的計(jì)算在最小液氣比下N,人關(guān)關(guān)0.99,%：關(guān)K關(guān)0.720.990.7128Vminb.理論板數(shù)的計(jì)算1.50.71281.0692操作液氣比LV15LVmin關(guān)鍵組分的吸收因子為上31.485VK關(guān)0.72AlgNL1理論板數(shù)lgA,0.991.485lg0.99118.868lg1.485C.各個(gè)組分的吸收分率和出塔尾氣的量和組成A由.N1A關(guān)K關(guān)LAiAiiiN1KiVKi和A1以及v1,i1iVN1,i；V1vi,i；yi,iv先進(jìn)行計(jì)算結(jié)果見表組分H2CH4C

12、2H4C2H6C3H6i-C4H10EyN1,i0.1320.37180.30200.0970.0840.01321.000Ki/3.150.720.500.1450.056n1,i,kmol/h13.237.1830.29.78.41.32100.0A/0.33941.4852.13847.37419.09300.33940.990.9951.0001.00013.224.5610.3020.04850038.1115yu0.34640.64450.00790.0013d.吸收劑量V10038.111569.056kmol/hL0(L061.8885)Lo30.9442塔內(nèi)氣體的平均流率為：

13、L塔內(nèi)液體的平均流率為：由LV1.0692,得Lo42.89kmol/h6 .在一精微塔中別離苯B,甲苯T,二甲苯X和異丙苯C四元混合物.進(jìn)料量200mol/h,進(jìn)料組成zB=0.2,zT=0.1,zX=0.4mol.塔頂采用全凝器,飽和液體回流.相對(duì)揮發(fā)度數(shù)據(jù)為：BT=2.25,TT=1.0,XT=0.33,ct=0.21.規(guī)定異丙苯在釜液中的回收率為99.8%,甲苯在儲(chǔ)出液中的回收率為99.5%.求最少理論板數(shù)和全回流操作下的組分分配解：根據(jù)題意頂甲苯為輕關(guān)鍵組分,異丙苯為重關(guān)鍵組分,從相對(duì)揮發(fā)度的大小可以看出,二甲苯為中間組分,在作物料衡算時(shí),初定它在儲(chǔ)出液和釜液中的分配比,并通過(guò)計(jì)算修

14、正物料衡算如下儲(chǔ)出液di40600.99520.00240DW=98.14釜液W-600.00518800.998W組分進(jìn)料B40T60X2080C一200解得D=101.86xTD=0.5861xTW=0.0031xCD=0.00157xCW=0.8135NmlgC-DWXTXClg工CT,0.58610.8135lg0.00160.0031lg21=7.35生生LNmWxWccTdxWX20解得dx=1.05mol;WX=18.95mol組分進(jìn)料diWB4040一T60600.995600.005X201.0518.95C80800.002800.998100.9199.09組分xdixw

15、iB0.39640T0.59160.0030X0.01040.1912C0.001580.8057lgJD壇W,0.59160.8051Nxcxt0.00160.0030=7.37Nmglg10.21CT2&xxTNmWx%cTdxWx20組分進(jìn)料儲(chǔ)出液釜液數(shù)量Mol%數(shù)量mol%數(shù)量mol%苯40204039.643一甲苯603059.759.1670.33.02二甲苯20101.041.0318.9619.13異丙苯80400.160.15979.8480.55200100100.9100.0099.1100.007 .某原料氣組成如下：組分CH4C2H6C3H8i-C4H10n-

16、C4H10i-C5H12n-C5H12n-C6H14y0(摩爾分率)0.7650.0450.0350.0250.0450.0150.0250.045先擬用不揮發(fā)的爛類液體為吸收劑在板式塔吸收塔中進(jìn)行吸收,平均吸收溫度為38C,壓力為1.013Mpa,如果要求將i-C4H10回收90%.試求：為完成此吸收任務(wù)所需的最小液氣比.操作液氣比為組小液氣比的1.1倍時(shí),為完成此吸收任務(wù)所需理論板數(shù).各組分的吸收分率和離塔尾氣的組成.求塔底的吸收液量解：由題意知,i-C4H10為關(guān)鍵組分由P=1.013Mpa,t平=38C查得K關(guān)=0.56(P-T-K圖)在最小液氣比下N=0°,A關(guān)=中關(guān)=0.

17、9(LZ)minK關(guān)隈V=0.560.9=0.504.LV1.1LVmin=1.10.504=0.55440.55440.560.99Alog()N1所以理論板數(shù)為10gAlog0.990.910.9log0.9919.48組分進(jìn)料量相平衡常數(shù)KiAii被吸收量塔頂尾氣數(shù)量組成CH476.517.40.0320.0322.44874.050.923C2H64.53.750.1480.1480.6683.8340.048C3H83.51.30.4260.4261.4912.0090.025i-C4H102.50.560.990.902.2500.2500.003n-C4H104.50.41.38

18、60.994.4550.0450.0006AiN11計(jì)算結(jié)果如下:AiN1LVKi它組分吸收率公式i-C5H121.50.183.081.001.5000.00.0n-C5H122.50.1443.851.002.5000.00.0n-C6H144.50.0569.91.004.5000.00.0合計(jì)100.0一一19.81080.190以CH4為例:LAi=VKi0.554417.40.0329481_0.03210.99ccc9.481=0.03210.32V1(CH4)=(1-i)VN+1=(1-0.032)76.5=74.05V1(CH4)y1(CH4)-V1塔內(nèi)氣體平均流率:74.0

19、50.92376.510080.190v290.10Kmol/h塔內(nèi)液體平均流率:Lo(L.19.81)L=2Lo9.905由%=0.5544;Lo=40.05Kmol/h8 .乙醇-苯-水系統(tǒng)在101.3kPa,64.86C形成恒沸物,其組成為22.8mol%乙醇a.,53.9mol%苯b.和23.3mol%水c.,利用恒沸點(diǎn)氣相平衡組成與液相組成相等這樣有利條件,計(jì)算在64.86C等溫別離該包沸混合液成為三個(gè)純液體產(chǎn)物所需的最小功.解：在等溫等壓條件下,將其別離成純組分時(shí)所需最小功為Wmin,TRTnFxFilnFixFi設(shè)為理想溶液,Fi1,假設(shè)nF1kmolWmin,TRTXFilnX

20、Fi8.31(64.38273.15)0.2281n0.2280.539ln0.5390.2331n0.2332836kJ/kmol9 .含乙烯32.4%的乙烯-乙烷混合物于2Mpa壓力下進(jìn)行蒸儲(chǔ),塔頂為純乙烯,溫度為239K,塔釜為純乙烷、溫度為260K,正常操作下,塔釜參加熱量為8800kJ/kg乙烯,試計(jì)算別離凈耗功為多少？解：設(shè)環(huán)境溫度T0298K,nF1kmol,乙烯的量為10.324268.424kg_1111W爭(zhēng)QTo(一一)8.4248800298()7465.6kJ/kmolTlTh23926010 .計(jì)算題9的熱力學(xué)效率解:Wmin,TnFRTyFilnyFi8.31298

21、0.3241n0.3240.6761n0.6761560kJ/kmolWmin1560mn_0.209W凈7465.611.試求環(huán)境溫度下,下表所示的氣體別離過(guò)程的最小功組分C2C3n-C4n-C5n-C6E進(jìn)料kmol/h30200370350501000產(chǎn)品1kmol/h301924226產(chǎn)品1kmol/h836635050774解：求出各物流的組成組分C2C3n-C4n-C5n-C6E進(jìn)料kmol/h30200370350501000XiF0.030.200.370.350.051.00產(chǎn)品1kmol/h301924226Xi10.1330.8500.0171.00產(chǎn)品1kmol/h83

22、6635050774Xi20.0100.4730.4520.0651.00Wmin,tRTnk(yi,klnyi,k)nj(yi,jlnyi,j)出進(jìn)8.314298226(0.1331n0.1330.85ln0.850.0171n0.017)774(0.01ln0.010.473ln0.4730.452ln0.4520.0651n0.065)1000(0.031n0.030.21n0.20.371n0.370.351n0.350.051n0.05)1.188106kJ/kmol12 .將含丙稀80%摩爾和丙烷20%的料液在常壓下別離為含內(nèi)稀99.6面口5%的兩股產(chǎn)品,試求別離最小功.設(shè)料液和

23、產(chǎn)品均處于環(huán)境溫度298K,料液可以當(dāng)作理想溶液.解：設(shè)料液量為1kmo1,計(jì)算兩股產(chǎn)品的量：nQ10.996nQ20.0510.8nQ1nQ21聯(lián)列解得：nQ10.7928kmol,nQ20.2072kmol別離最小功由式6-15計(jì)算：wmin=0.7928(0.9961n0.996+0.0041n0.004)+0.2072(0.051n0.05+0.951n0.95)-(0.81n0.8+0.21n0.2)RT.=0.4386RT0=1087.4KJ/Kmo1料液13 .一輕姓混合物進(jìn)行精儲(chǔ)塔的計(jì)算,求得最小回流比Rm=1.45,最小理論板數(shù)Nm=8.6.求回流化為R=1.25Rm,全塔平

24、均板效率為n=0.60,所需最小塔板板數(shù).R=1.251.45=1.8125=L8125-M5=013氏+118125+1由此圖查,得:"+10,58由于,Nm=8.6所以,N=19.43實(shí)際板數(shù)為：19.43/0.6=32.4=33塊14 .某廠裂解氣組成(摩爾)如下：13.2%氫、37.18%甲烷、30.2乙烯、9.7%乙烷、8.4%丙烯、1.32異丁烷、所用的吸收劑中不含所吸收組分.要求乙烯的回收率到達(dá)99%.該吸收塔處理的氣體量為100kmo1/h,操作條件下各組分的相平衡常數(shù)如下:丙烷0.520.15甲烷異丁烷3.10.058乙烯0.72操作液氣化為最小液氣比的1.5倍試求

25、：(1)最小液氣化；(2) 所需理論板數(shù)；(3) 各組份的吸收因子、吸收率(4) 塔頂尾氣的組成及數(shù)量；(5) 塔頂應(yīng)參加的吸收劑量解：(1)最小液氣化=mA=0.72+0.P?=0,712S(2)所需理論板數(shù)N=15*07123=1口692%=15(/同A=(-)=1,0692x=1435曠K0.72N二1=8,86%(3)各組份的吸收因子、吸收率吸收因子,以甲烷為例：工十七十M.941Q口十沼Q61.0692護(hù)=(9)-rr-=1.0692x-=0.3-149中阮vK甲烷3.1吸收率,以甲烷為例:中甲烷:節(jié)篇一由烷_*T-SM4爐m_0344中郵413449=0.341塔頂尾氣的組成及數(shù)量(見表)W+1A.W+1(J)1y1H13.200013