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中原工学院 材料与化工学院

化工原理课程设计说明书

设计名称: 班 级: 组 别: 组 员: 指导老师:

日 期:2013 年 12月28日

1

设计任务书

一、设计题目

3000吨酒精连续填料精馏塔设计

二、设计任务及操作条件

1、 设计任务:

生产能力(塔顶产品) 3000 吨/年 操作周期 300 天/年

进料组成 35 (质量分数,下同) 塔顶产品组成 ≥94% 塔底产品组成 ≤0.1% 2、 操作条件

操作压力 常压 (塔顶) 进料热状态 35℃ 3、 设备型式 自选 4、 厂 址 郑 州 地 区 三、设计内容:

(1) 精馏塔的物料衡算; (2) 塔板数的确定;

(3) 精馏塔的工艺条件及有关物件数据的计算; (4) 精馏塔的塔体工艺尺寸计算; (5) 塔板主要工艺尺寸的计算; (6) 塔板的流体力学验算; (7) 塔板负荷性能图; (8) 精馏塔接管尺寸计算; (9) 绘制生产工艺流程图; (10) 绘制精馏塔设计条件图;

(11) 对设计过程的评述和有关问题的讨论。

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四、参考资料

1. 陈英南,刘玉兰. 常用化工单元设备的设计. 上海:华东理工大学出版社,2005 2. 黄璐,王保国. 化工设计. 北京:化学工业出版社,2001

3. 贾绍义,柴诚敬. 化工原理课程设计(化工传递与单元操作课程设计). 天津:天津大学

出版社,2002

4. 陈敏恒,丛德兹等. 化工原理(上、下册)(第二版). 北京:化学工业出版社,2000 5. 柴诚敬,刘国维,李阿娜. 化工原理课程设计. 天津:天津科学技术出版社,1995 6. 石油化学工业规划设计院. 塔的工艺计算. 北京:石油化学工业出版社,1997

7. 化工设备技术全书编辑委员会. 化工设备全书—塔设备设计. 上海:上海科学技术出版

社,1988

8. 时钧,汪家鼎等. 化学工程手册,. 北京:化学工业出版社,1986

9. 上海医药设计院. 化工工艺设计手册(上、下). 北京:化学工业出版社,1986

10. 大连理工大学化工原理教研室. 化工原理课程设计. 大连:大连理工大学出版社,1994

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目 录

一、概述 ·············································································································· 6

1. 设计依据 ·································································································· 6 1. 技术来源 ·································································································· 6 1. 设计任务及要求 ······················································································· 6 二、计算过程 ······································································································· 7

1. 塔型选择 ·································································································· 7 2. 操作条件的确定 ······················································································· 7

2.1 操作压力 ························································································· 7 2.2 进料状态 ························································································· 8 2.3 加热方式 ························································································· 8 2.4 热能利用 ························································································· 8 3. 有关的工艺计算 ······················································································· 8

3.1 最小回流比及操作回流比的确定··················································· 9 3.2 塔顶产品产量、釜残液量及加热蒸汽量的计算 ···························· 9 3.3 全凝器冷凝介质的消耗量 ···························································· 10 3.4 热能利用 ······················································································· 10 3.5 理论塔板层数的确定 ···································································· 11 3.6 全塔效率的估算 ··········································································· 11

3.7 实际塔板数NP ············································································ 12 4. 精馏塔主题尺寸的计算 ········································································· 13 4.1 精馏段与提馏段的体积流量 ························································ 13

4.1.1 精馏段 ················································································ 13 4.1.2 提馏段 ················································································ 14 4.2 塔径的计算 ··················································································· 15 4.3 塔高的计算 ··················································································· 17 5. 塔板结构尺寸的确定 ············································································· 18

5.1 塔板尺寸 ······················································································· 18 5.2 弓形降液管 ··················································································· 19

5.2.1 堰高 ···················································································· 19 5.2.2 降液管底隙高度h0 ····························································· 19 5.2.3 进口堰高和受液盘 ····························································· 19 5.3 浮阀数目及排列 ··········································································· 19

5.3.1 浮阀数目 ············································································ 19 5.3.2 排列 ···················································································· 20 5.3.3 校核 ···················································································· 20

6. 流体力学验算························································································· 21

6.1 气体通过浮阀塔板的压力降(单板压降)hp ································· 21

6.1.1 干板阻力hc ······································································· 21

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6.1.2 板上充气液层阻力h1 ···································································· 21

6.1.3 由表面张力引起的阻力h? ···················································· 21

6.2 漏液验算 ······················································································· 21 6.3 液泛验算 ······················································································· 22 6.4 雾沫夹带验算 ··············································································· 22 7. 操作性能负荷图 ····················································································· 23

7.1 雾沫夹带上限线 ··········································································· 23 7.2 液泛线 ·························································································· 23 7.3 液体负荷上限线 ··········································································· 24 7.4 漏液线 ·························································································· 24 7.5 液相负荷下限线 ··········································································· 24 7.6 操作性能负荷图 ··········································································· 24 8. 各接管尺寸的确定 ················································································· 25

8.1 进料管 ·························································································· 25 8.2 釜残液出料管 ··············································································· 25 8.3 回流液管 ······················································································· 25 8.4 塔顶上升蒸汽管 ··········································································· 26 8.5 水蒸汽进口管 ··············································································· 26

三、课程设计数据总结 ·············································································· 27

四、课程设计评价与认识 ·················································································· 27

1. 课程设计评价 ················································································· 27

2. 课程设计认识 ················································································· 27

五、参考资料 ·································································································· 29

六、附录图 ········································································································· 29

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一、概述

乙醇~水是工业上最常见的溶剂,也是非常重要的化工原料之一,是无色、

无毒、无致癌性、污染性和腐蚀性小的液体混合物。因其良好的理化性能,而被广泛地应用于化工、日化、医药等行业。近些年来,由于燃料价格的上涨,乙醇燃料越来越有取代传统燃料的趋势,且已在郑州、济南等地的公交、出租车行业内被采用。山东业已推出了推广燃料乙醇的法规。

长期以来,乙醇多以蒸馏法生产,但是由于乙醇~水体系有共沸现象,普通的精馏对于得到高纯度的乙醇来说产量不好。但是由于常用的多为其水溶液,因此,研究和改进乙醇`水体系的精馏设备是非常重要的。

塔设备是最常采用的精馏装置,无论是填料塔还是板式塔都在化工生产过程中得到了广泛的应用,在此我们作板式塔的设计以熟悉单元操作设备的设计流程和应注意的事项是非常必要的。 1. 设计依据

本设计依据于教科书的设计实例,对所提出的题目进行分析并做出理论计算。 1. 技术来源

目前,精馏塔的设计方法以严格计算为主,也有一些简化的模型,但是严格计算法对于连续精馏塔是最常采用的,我们此次所做的计算也采用严格计算法。 1. 设计任务及要求

原料:乙醇~水溶液,年产量3000吨

乙醇含量:35%(质量分数),原料液温度:45℃ 设计要求:塔顶的乙醇含量不小于94%(质量分数) 塔底的乙醇含量不大于0.1%(质量分数)

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表1 乙醇~水溶液体系的平衡数据

液相中乙醇的含量(摩尔分数) 汽相中乙醇的含量(摩尔分数) 液相中乙醇的含量(摩尔分数) 汽相中乙醇的含量(摩尔分数) 0.0 0.004 0.01 0.02 0.04 0.06 0.08 0.10 0.14 0.18 0.20 0.25 0.30 0.35 二:计算过程 1. 塔型选择

0.0 0.053 0.11 0.175 0.273 0.34 0.392 0.43 0.482 0.513 0.525 0.551 0.575 0.595 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.894 0.90 0.95 1.0 0.614 0.635 0.657 0.678 0.698 0.725 0.755 0.785 0.82 0.855 0.894 0.898 0.942 1.0 根据生产任务,若按年工作日300天,每天开动设备24小时计算,产品流量为417kg/h,由于产品粘度较小,流量较大,为减少造价,降低生产过程中压降和塔板液面落差的影响,提高生产效率,选用浮阀塔。 2. 操作条件的确定 2.1 操作压力

由于乙醇~水体系对温度的依赖性不强,常压下为液态,为降低塔的操作费用,操作压力选为常压

其中塔顶压力为1.01325?105Pa

7

塔底压力[1.01325?105?N(265~530)]Pa

2.2 进料状态

虽然进料方式有多种,但是饱和液体进料时进料温度不受季节、气温变化和前段工序波动的影响,塔的操作比较容易控制;此外,饱和液体进料时精馏段和提馏段的塔径相同,无论是设计计算还是实际加工制造这样的精馏塔都比较容易,为此,本次设计中采取饱和液体进料 2.3 加热方式

精馏塔的设计中多在塔底加一个再沸器以采用间接蒸汽加热以保证塔内有足够的热量供应;由于乙醇~水体系中,乙醇是轻组分,水由塔底排出,且水的比热较大,故可采用直接水蒸气加热,这时只需在塔底安装一个鼓泡管,于是可省去一个再沸器,并且可以利用压力较底的蒸汽进行加热,无论是设备费用还是操作费用都可以降低。 2.4 热能利用

精馏过程的原理是多次部分冷凝和多次部分汽化。因此热效率较低,通常进入再沸器的能量只有5%左右可以被有效利用。虽然塔顶蒸汽冷凝可以放出大量热量,但是由于其位能较低,不可能直接用作为塔底的热源。为此,我们拟采用塔釜残液对原料液进行加热。 3. 有关的工艺计算

由于精馏过程的计算均以摩尔分数为准,需先把设计要求中的质量分数转化为摩尔分数。已知进料口、塔顶、塔釜的质量分数分别是45%、94%和0.1%。

原料液的摩尔组成:

xf?nCH3CH2OHnCH3CH2OH?nH2O?35/46?0.1740

35/46?65/18同理可求得: xD?0.8598,xW?0.0004原料液的平均摩尔质量:

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Mf?xfMCH3CH2OH?(1?xf)MH2O?0.174?46?0.826?18?22.872kg/mol

同理可求得:

MD?42.074kg/kmol,MW?18.0kg/kmol在45℃下,原料液中?H2O?971.1kg/m3,?CH3CH2OH?735kg/m3

由此可查得原料液,塔顶和塔底混合物的沸点,以上计算结果见表2。

表2 原料液、馏出液与釜残液的流量与温度 名称 xf/% xf(摩尔分数) 原料液 35 0.1740 22.872 83.83 馏出液 94 0.8598 42.07 78.62 釜残液 0.1 0.0004 18.0 99.38 摩尔质量kg/kmol 沸点温度t/℃

3.1 最小回流比及操作回流比的确定

由于是泡点进料,xq?xf?0.174,过点e(0.174,0.174)做直线x?0.174交平衡线于点d,由点d可读得yq?0.516,因此:

Rmin?xd?yq0.859?80.516??1.005yq?xq0.516?0.174

可取操作回流比:R?2.0Rmin?2.0?1.005?2.01,故R取3.0 3.2 塔顶产品产量、釜残液量及加热蒸汽量的计算

以年工作日为300天,每天开车24小时计,进料量为:

F?

3000?1000?18.217kmo/lh300?24?22.872

由全塔的物料衡算方程可写出:

V0?F?D?W y0?0(蒸汽) D?3.6731kmol/h

2mo/lh V0y0?Fxf?DxD?WxW W?29.736k9

2mo/lh W?L'?L?qF?RD?qF q?1(泡点) V0?14.693k3.3 全凝器冷凝介质的消耗量

塔顶全凝器的热负荷:QC?(R?1)D(IVD?ILD) 可以查得IVD?1266kJ/kg,ILD?253.9kJ/kg,所以

Qc??3?1??65.85?3.6731?(1266-253.9)?9.79?105kJ/h 平均温度下的比热cpc?4.174kJ/kg?oC,于是冷凝水用量可求:

Qc9.79?105??11727kg/h Wc?Cpc?t2?t1?4.174??45?25?3.4 热能利用

以釜残液对预热原料液,则将原料加热至泡点所需的热量Qf可记为: Qf?Wfcpf(tf2?tf1) 其中tfm?83.83?45?64.4oC 2在进出预热器的平均温度以及tfm?64.4oC的情况下可以查得 比热cpf?4.275kJ/kg?oC,所以,

4800?0310?4.275?(83.?83?45) Qf?300?2461?.k1J07 h10/釜残液放出的热量Qw?Wwcpw(tw1?tw2) 若将釜残液温度降至t2w?55oC 那么平均温度twm?99.38?55?77.2oC 2其比热为cpw?4.191kJ/kg?oC,因此,

Qw?364.85?4.191?(99.38?55)?1.228?106kJ/h

可知,Qw?Qf,于是理论上可以用釜残液加热原料液至泡点。

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3.5 理论塔板层数的确定 精馏段操作线方程:

yn?1?RxDxn??0.75xn?0.215R?1R?1 WWxm?xm?2xm?0.0008 V0V0提馏段操作线方程:

yn?1? q线方程:x?0.174

由精馏段和提馏段的操作线方程,用逐板计算法可以求出 X1=0.5976 Y1=0.8598 X6=0.03385 Y6=0.1264 X2=0.3228 Y2=0.6632 X7=0.0172 Y7=0.0669 X3=0.1693 Y3=0.4571 X8=0.008348 Y8=0.0336 X4=0.1099 Y4=0.3378 X9=0.003896 Y9=0.0159 X5=0.06361 Y5=0.2191 X10=0.001704 Y10=0.006994 X11=0.0006327 Y11=0.002608 X12=0.0001127 Y12=0.0004654

NT?12块(含塔釜)

其中,精馏段3块,提馏段9块。 3.6 全塔效率的估算

用奥康奈尔法(O'conenell)对全塔效率进行估算: 由相平衡方程式y??xy(x?1)可得??

1?(??1)xx(y?1)根据乙醇~水体系的相平衡数据可以查得:

y1?xD?0.8598x 1 ? 0 . 840 ( 塔顶第一块板)

y f ? 0 .516 x f 0 . (加料板) ?174 x w ? y w ? 0 .026 ( 塔釜 ) 0 . 002因此可以求得:

11

?1?1,?f?5.06,?w?13.32全塔的相对平均挥发度:

33?m??1??f??w?1.0?5.06?13.32?4.13

全塔的平均温度:

tm?tD?tf?tW3?78.62?83.83?99.38?87.30oC3在温度tm下查得?H2O?0.327mPa?s,?CH3CH2OH?0.38mPa?s 因为?L??xi?Li

所以,?Lf?0.174?0.38?(1?0.174)?0.327?0.336mPa?s 全塔液体的平均粘度:

?Lm?(?Lf??LD??LW)/3?(0.327?0.38?0.327)/3?0.344mPa?s1?45%

(4.36?0.344)0.245全塔效率:ET?0.49(??L)?0.245?0.49?Np?NT12??27ET0.453.7 实际塔板数NP

块(含塔釜)

其中,精馏段的塔板数为:

3?7块 0.4512

4. 精馏塔主题尺寸的计算

4.1 精馏段与提馏段的体积流量 4.1.1 精馏段

整理精馏段的已知数据列于表3(见下页),由表中数据可知:

液相平均摩尔质量: M?

液相平均温度: tm?

表3 精馏段的已知数据

位置 进料板 塔顶(第一块板) Mf?M122.872?42.0744??32.4732kg/kmol22tf?tD84.10?78.62??81.36℃22x'f?0.35 质量分数 y1?xD?0.94 x1?0.9848 yf?0.6898 xf?0.174 摩尔分数 y1?xD?0.8598 x1?0.5976 MLf?42.0744 MVL?34.73 78.62 yf?0.516 摩尔质量/kg/kmol MLf?22.872 MVf?32.45 83.83 温度/℃

在平均温度下查得?H2O?971.1kg/m3,?CH3CH2OH?735kg/m3 液相平均密度为:

1?Lm?'xLm?CHCHOH32?'1?xLm?HO

2xLm?0.35?0.9848?0.6674213

其中,平均质量分数 所以, ?Lm?799.66kg/m3精馏段的液相负荷:L?RD?11.02kmol/h

Ln?LM?11.02?32.47?0.447m3/h799.66

?Lm同理可计算出精馏段的汽相负荷。

精馏段的负荷列于表4。

表4 精馏段的汽液相负荷

名称 平均摩尔质量/kg/kmol 平均密度/kg/m 体积流量/m/h

33汽相 32.47 799.66 0.447(0.000124m/s) 3液相 33.59 1.251 3804(1.056m/s) 34.1.2 提馏段

整理提馏段的已知数据列于表5,采用与精馏段相同的计算方法可以得到提馏段的负荷,结果列于表6。

表5 提馏段的已知数据

位置 塔釜 进料板 x'w?0.001 质量分数 x'f?0.35 y'w?0.00412 y'f?0.6898 14

xw?0.0004 摩尔分数 xf?0.174 yf?0.516 MLf?22.872 yW?0.026 MLW?18.1 摩尔质量/kg/kmol MLV?18.05 温度/℃ 99.38

表6 提馏段的汽液相负荷

名称 平均摩尔质量/kg/kmol 平均密度/kg/m 体积流量/m/h 33MVf?32.45 83.83 液相 汽相 20.486 25.25 874.11 0.2583(0.00007174m/s) 30.816 4132(1.15m/s) 3

4.2 塔径的计算

由于精馏段和提馏段的上升蒸汽量相差不大,为便于制造,我们取两段的塔径相等。有以上的计算结果可以知道: 汽塔的平均蒸汽流量:

Vs?(Vsj?Vst)0.822?0.947??0.8845 22汽塔的平均液相流量:

LS?LSJ?LST0.000124?0.00007174??0.000196m3/s22

汽塔的汽相平均密度:

15

? 2 ?(Tmc?T2)1.2?1Tmc?T1?V??VJ??VT2?1.251?0.816?1.0335kg/m3

2汽塔的液相平均密度:

?799.66?874.11?836.89kg/m32

2

塔径可以由下面的公式给出:

?L??LJ??LT D?4VS ?u由于适宜的空塔气速u?(0.6~0.8)umax,因此,需先计算出最大允许气速umax。

umax?C?L??V ?V取塔板间距HT?0.4m,板上液层高度h1?60mm?0.06m,那么分离空间:

6 HT?h1?0.4?0.0?0.m 34功能参数:

?LS??V?S??L0.00146????1.103?V836.89?0.005061.0335从史密斯关联图查得:C20?0.073,由于C?C20(力:

?20)0.2,需先求平均表面张

TD?TF?TW78.62?83.83?99.38??87.28℃在此温度下, 全塔平均温度,33

0.5976?0.174?0.004?0.257乙醇的平均摩尔分数为

3温度:

所以,液体的临界

TC??xiTic?0.257?(273?243)?(1?0.257)?(273?342.2)?589.71K

设计要求条件下乙醇~水溶液的表面张力?1?26dyn/m2 平均塔温下乙醇~水溶液的表面张力可以由下面的式子计算:

16

所以:

?589.7?(273?87.28)??2???26?25.53dyn/cm??609??273?83.83??1.2

u?0.7?2.181?1.527m/s根据塔径系列尺寸圆整为D?900mm 此时,精馏段的上升蒸汽速度为:

4VSJ4?0.822??1.2928m/s 22?D??0.94V 提馏段的上升蒸汽速度为:uJ?SJ?1.4893m/s

?D2 uJ? 4.3 塔高的计算

塔的高度可以由下式计算:

?STH?FH? WH Z?HP?(N?2?S)HT已知实际

?25.53?HT?0.4m由C?0.073??20??0.2塔板数为N?27块,板间距

?0.0767于料液较清洁,无需经常

清洗,可9块板设一个

?max取每隔?L??V836.89?1.0335?C?0.0767??2.181m/s?V1.0335人孔,

则人孔的数目S为:

S?27?1?2个9

取人孔两板之间的间距HT?0.6m,则塔顶空间HD?1.2m,塔底空间

HW?2.5m,进料板空间高度HF?0.5m,那么,全塔高度:

17

5. 塔板结构尺寸的确定 5.1 塔板尺寸

由于塔径大于800mm,所以采用单溢流型分块式塔板。 取无效边缘区宽度WC?40mm,破沫区宽度WS?70mm, 查得lW?705mm

弓形溢流管宽度Wd?146mm 弓形降

Z?1.5??27?2?2??0.4?2?0.6?0.5?1.5?2?15.9mA2f?0.07m0 6 Af/AT?0.0706/0.?7854

R?D/2?WC?0.45?0.04?0.41m

x?D/2?Wd?Ws?0.45?0.146?0.07?0.334m 验算:

液体在精馏段降液管内的停留时间 ?fHT?0.4J?AL?0.0360ST1.24?10?4?227.74s?5s 液体在精馏段降液管内的停留时间

?fHTT?AL?0.0706?0.4ST7.174?10?5?393.6s?5s

18

液管面积

5.2 弓形降液管

5.2.1 堰高

采用平直堰,堰高hw?h1?how

取h1?50mm,how?10mm,,则hw?50?10?40mm 5.2.2 降液管底隙高度h0

若取精馏段取h0?15mm,提馏段取为25mm,那么液体通过降液管底隙时的 流速为 精馏段:

LSJ1.24?10?4????0.0118m/s u0lwh00.7?0.015提馏段:

LST7.174?10?3????0.126m/s u0lwh00.7?0.025'u0的一般经验数值为0.07~0.25m/s

5.2.3 进口堰高和受液盘

本设计不设置进口堰高和受液盘 5.3 浮阀数目及排列

采用F1型重阀,重量为33g,孔径为39mm。 5.3.1 浮阀数目

4VS ?d02u0浮阀数目N?19

气体通过阀孔时的速度u0?F?v 取动能因数F?11,那么u0?N?11?36.19m/s,因此

0.09240.8845?4?20.47个=21个 2??0.039?36.19 5.3.2 排列

由于采用分块式塔板,故采用等腰三角形叉排。若同一横排的阀孔中心距

'为: t?75mm,那么相邻两排间的阀孔中心距t计'? t计Aa NtAa?2[xR2?x2??180?R2sin?1x]R ?2[0.284?0.462?0.2842? =0.487m2't计??180??0.462sin?10.284] 0.460.487?75.5mm

86?0.075 5.3.3 校核

4VS4?0.8845??10.7577m/s ?d02N??0.039气体通过阀孔时的实际速度:u0?实际动能因数:F0?10.7577?1.0335?10.94(在9~12之间) 开孔率:

?d02N阀孔面积??(0.039)2?89?100%??100%??13.5%

塔截面积4AT4?0.7854开孔率在10%~15%之间,满足要求。

20

6. 流体力学验算

6.1 气体通过浮阀塔板的压力降(单板压降)hp

气体通过浮阀塔板的压力降(单板压降)hp?hc?h1?h?

6.1.1 干板阻力hc

浮阀由部分全开转为全部全开时的临界速度为uoc:

uoc?1.82573.1/?V?1.82573.1/1.0335?10.22m/s

因为uoc?u0?10.7577m/s 所以

2?Vu01.0335?10.75772hc?5.34?5.34??0.0389m2?Lg2?836.89?9.816.1.2 板上充气液层阻力

取板上液层充气程度因数??0.5,那么:

6.1.3 由表面张力引起的阻力h?

由表面张力导所以一般情况下可

h1??hL?0.5?0.06?0.03m致的阻力一般来说都比较小,以忽略,所以:

hp?0.0367?0.03?0.0667m,p?0.0667?836.89?9.81?547.60Pa

6.2 漏液验算

动能因数F0?5,相应的气相最小负荷VSmin为:

21

其所

以VSmin??d02Nu0min4u0min?F?V?5/1.0335?4.92m/s

VSm??402i?.n0?m3 30?s93?8m可见不会产生过量漏液。 6.3 液泛验算

溢流管内的清液层高度Hd?hp?hd?hL?h? 其中,hp?0.0643m,hL?0.04m

所以,Hd?0.643?0.04?0.002?0.685m

为防止液泛,通常Hd??(HT?hw),取校正系数??0.5,则有:

可见,产生液泛。 6.4 雾沫夹带验算

?(HT?hw)?0.5?(0.4?0.03)?0.215mHd??(HT?hw),即不会

VS?V?L??V?1.36LSZL泛点率=KCFAb

查得物性系数K?1.0,泛点负荷系数CF?0.097

Ab?AT?2Af?0.7854?2?0.0706?0.6442m2ZL?0.9?2Wd?1?2?0.146?0.608m22

所以,

0.8845?1.0335?1.36?0.00146?0.608836.89?1.033551.71%?80%

1?0.097?0.6442 泛点率=

可见,雾沫夹带在允许的范围之内 7. 操作性能负荷图 7.1 雾沫夹带上限线

取泛点率为80%代入泛点率计算式,有:

VS0.8??V?L??V?1.36LSZL?VSKCFAb1.0335?1.36?0.708LS836.89?1.0335

0.097?0.6442整理可得雾沫夹

带上限方程为:

VS?1.422?27.39LS

7.2 液泛线

2/3液泛线方程为aVS2?b?cL2S?dLS

其中,a?1.91?105?v?LN2?1.91?105?1.0335?0.5348

836.89?212b??HT?(??1??0)?0.5?0.4?(0.5?1?0.5)?0.03?0.17

c?0.1530.153??192.4 22lwh00.7052?0.0152d?(1??0)E(0.667)12/3lw?(1?0.5)?1.02?0.667?1?3.553 0.705223S代入上式化简后可得:VS?0.318?360L?6.64L

22S23

7.3 液体负荷上限线 取??5s,那么

LSmax?AfHT5?0.0706?0.4?0.00565m3/s 5 7.4 漏液线

取动能因数F0?5,以限定气体的最小负荷: VSmin??4d0N25?V??4?0.07062?21?5?0.1277m3/s

1.0335 7.5 液相负荷下限线

L2.84?1.02?[Smin]2/3?0.006 1000lw取how?0.006m代入how的计算式:

整理可得:LSmin?2.1m3/h?0.000584m3/s 7.6 操作性能负荷图

由以上各线的方程式,可画出图塔的操作性能负荷图。

根据生产任务规定的气液负荷,可知操作点P(0.00146,1.103)在正常的操作 范围内。连接OP作出操作线,由图可知,该塔的雾沫夹带及液相负荷下限, 即由漏液所控制。由图可读得:

所以,塔的操作弹性为1.65/0.57?2.89

有关该浮阀塔的工艺设计计算结果汇总于表7

(VS)max?1.65m3/s,(VS)min?0.57m3/s24

表7 浮阀塔工艺设计计算结果

项目 塔径D,m 板间距HT,m 塔板型式 空塔气速u,m/s 溢流堰长度lW,m 溢流堰高度hW,m 板上液层高度hL,m 降液管底隙高度h0,m 浮阀数N,个 阀孔气速u0,m/s 阀孔动能因数F0 临界阀孔气速u0c,m/s 孔心距t,m 排间距t',m 单板压降?p,Pa 液体在降液管内的停留时间?,s 降液管内的清液高度Hd,m 泛点率,% 气相负荷上限(VS)max 气相负荷下限(VS)min 开孔率,% 操作弹性 数值与说明 1.0 0.4 单溢流弓形降液管 1.476 0.705 0.05 0.01 0.025 89 10.38 5 10.32 0.075 0.065 564.7 41.8 12.6 0.1297 63.4 1.65 0.57 13.5 2.89 备注 分块式塔板 等腰三角形叉排 同一横排的孔心距 相临二横排的中心线距离 精馏段 提馏段 雾沫夹带控制 漏夜控制 25

8. 各接管尺寸的确定

8.1 进料管

FMf30.72?872?0.771m3h?2.14?10?4m3s

911.3 进料体积流量 Vsf??f?取适宜的输送速度,uf?2.0ms故

dif?4Vsf?4?2.14?10?4?0.01167m

2?

?u经圆整选取热轧无缝钢管(YB231-64),规格:?45?3mm

4?2.14?10?4?0.18ms 实际管内流速:uf???0.03928.2 釜残液出料管

釜残液的体积流量:

VSW?WMw?w?12.97?18.0?0.2436m3h?6.77?10?5m3s

958.4取适宜的输送速度uW?1.5m/s,则 d计?4?6.77?10-5?5.75?10-3m

1.5?经圆整选取热轧无缝钢管(YB231-64),规格:?45?3mm

4?6.77?10?5?0.0567ms 实际管内流速:uw???0.03928.3 回流液管

回流液体积流量 VSL?LML?L?7.9824?34.73?0.3711m3h?1.031?10?4m3s

74726

利用液体的重力进行回流,取适宜的回流速度uL?0.5m/s,那么

d计?4?1.031?10?4?0.0162m

0.5?经圆整选取热轧无缝钢管(YB231-64),规格:?57?3.5mm

4?1.031?10?4实际管内流速:uw??0.863m/s 2??0.0398.4 塔顶上升蒸汽管

塔顶上升蒸汽的体积流量: VSV?2?7.9824?34.73?594.91m3h?0.165m3s

1.398取适宜速度uV?2.0m/s,那么

d计?4?0.165?0.324m2?经圆整选取热轧无缝钢管(YB231-64),规格:?273?5mm 实际管内流速:usv?8.5 水蒸汽进口管

通入塔的水蒸气体积流量: VSO?42.0744?18?1268.57m3h?0.3524m3s

0.5974?0.165?3.04ms 2??0.263取适宜速度u0?2.5m/s,那么

d计?4?0.3524?0.4238m

2.5?经圆整选取热轧无缝钢管(YB231-64),规格:?245?5mm 实际管内流速:u0?

27

4?0.3524?8.1289ms 2??0.235

三、课程设计数据汇总

摩尔组成 沸点/℃ 平均摩尔摩尔流量(kmol/h) 分子量 液体名称 质量组成 料液F 0.35 0.174 0.8598 0.00196 83.83 78.62 99.38 22.87 42.07 18.1 18.22 3.67 29.74 产品液D 0.94 塔釜液W 0.01 此次课程设计回流比取3,总共27块塔板,第8块为加料板,精馏段为7块,提馏段为20块。

四、课程设计评价与认识

1、课程设计评价

此次化工原理课程设计采用相对较大回流比,设备尺寸小,设备费用低。可以使用标准换热器,加热能力提高较易,检修安装方便。由于乙醇--水体系腐蚀性小直接采用塔壁作为降液管的一部分,降低了设备费用。操作比较麻烦,故操作费用相对增加。 2、课程设计认识

课程设计给我很多专业知识以及专业技能上的提升,使我对化学产生了更大的兴趣。同时,设计让我感触很深,让我对抽象的理论有了具体的认识。通过这次课程设计使我充分理解到化工原理课程的重要性和实用性,更特别是对精馏原理及其操作各方面的了解和设计,对实际单元操作设计中所涉及的个方面要注意问题都有所了解。通过这次对精馏塔的设计,不仅让我将所学的知识应用到实际

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中,而且对知识也是一种巩固和提升充实

通过本次课程设计的训练,让我对自己的专业有了更加感性和理性的认识,这对我们的继续学习是一个很好的指导方向,我们了解了工程设计的基本内容,掌握了化工设计的主要程序和方法,增强了分析和解决工程实际问题的能力。同时,通过课程设计,还使我们树立正确的设计思想,培养实事求是、严肃认真、高度负责的工作作风,加强工程设计能力的训练和培养严谨求实的科学作风更尤为重要。

其次通过这次课程设计,对板式塔的工作原理有了初步详细精确话的了解,加深了对设计中所涉及到的一些力学问题和一些有关应力分析、强度设计基本理论的了解。使我们重新复习了所学的专业课,学习了新知识并深入理解,使之应用于实践,将理论知识灵活化,这都将为我以后参加工作实践有很大的帮助。非常有成就感,培养了很深的学习兴趣。

此次设计的全过程中,我们达到了最初的目的,对化工原理有了较深入的认识,对化工设备的设计方面的知识有了较全面的认识,熟悉了板式塔设计的全过程及工具用书。我去图书馆查阅了这方面的有关书籍并上了一些网站检索了相关内容,从中学到了很多知识,受益匪浅。

在此感谢我们的王红芳老师.,老师严谨细致、一丝不苟的作风一直是我工作、学习中的榜样;老师循循善诱的教导和不拘一格的思路给予我无尽的启迪;这次课程设计的细节和每个数据,都离不开王老师的细心指导。而您开朗的个性和宽容的态度,帮助我能够很顺利的完成了这次课程设计。

同时感谢同组的队友,谢谢他们对我的帮助和支持,让我感受到同学的友谊。由于本人的设计能力有限,在设计过程中难免出现错误,恳请老师们多多指教,我十分乐意接受你们的批评与指正,我将万分感谢。

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五、参考资料

[1] 华东理工大学化工原理教研室编. 化工过程设备及设计. 广州:华南理工大学出版社. 1996.02

[2] 天津大学化工原理教研室编. 化工原理(下). 天津:天津大学出版社. 1999.04 [3] 陈敏恒,丛德兹等. 化工原理(上、下册)(第二版). 北京:化学工业出版社,2000

[4] 柴诚敬,刘国维,李阿娜. 化工原理课程设计. 天津:天津科学技术出版社,1995

[5] 石油化学工业规划设计院. 塔的工艺计算. 北京:石油化学工业出版社,1997

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