高溫高壓條件下漿態(tài)鼓泡床氣液傳質(zhì)特性的研究

化工論文編號(hào):HG007  字?jǐn)?shù):25168.頁(yè)數(shù):60

目 錄

符 號(hào) 說 明 .....................................................................1
前 言........................................................................... 3
第一章  文獻(xiàn)綜述 ................................................................4
1.1  漿態(tài)床反應(yīng)器技術(shù)的發(fā)展?fàn)顩r..................................................4
1.2  漿態(tài)鼓泡床的優(yōu)點(diǎn)............................................................7
1.3  漿態(tài)鼓泡床應(yīng)用的典型工藝及操作條件..........................................7
1.4  漿態(tài)鼓泡床反應(yīng)器的研究領(lǐng)域..................................................8
1.5  漿態(tài)鼓泡床內(nèi)的混合與操作要求 ...............................................9
1.6  漿態(tài)鼓泡床氣液傳質(zhì)的研究概況 ..............................................10
1.7  影響傳質(zhì)系數(shù)的主要因素 ....................................................12
1.7.1  系統(tǒng)壓力 ................................................................12
1.7.2  溫  度 ..................................................................12
1.7.3  表觀氣速 ................................................................13
1.7.4  液體性質(zhì) ................................................................13
1.7.5  固含率及固體顆粒性質(zhì).....................................................14
1.8  傳質(zhì)系數(shù)模型...............................................................15
1.8.1  傳質(zhì)系數(shù)的理論模型 ......................................................15
（1）雙膜模型 ..................................................................15
（2）滲透模型...................................................................15
（3）表面更新模型...............................................................16
（4）旋渦池理論 ................................................................16
1.8.2  傳質(zhì)系數(shù)的經(jīng)驗(yàn)關(guān)聯(lián)式.....................................................16
1.9  傳質(zhì)系數(shù)的測(cè)量方法 ........................................................18
1.9.1  物理法...................................................................18
1.9.2  化學(xué)法 ..................................................................19
1.10 漿態(tài)鼓泡床傳質(zhì)特性的研究趨勢(shì) ..............................................19
1.11 課題的意義 ................................................................20
第二章  實(shí)驗(yàn)部分................................................................21
2.1  實(shí)驗(yàn)物系及實(shí)驗(yàn)條件.........................................................21
2.1.1  實(shí)驗(yàn)物系 ................................................................21
2.1.2  實(shí)驗(yàn)條件.................................................................22
2.2  實(shí)驗(yàn)裝置及測(cè)量方法 ........................................................22
2.3  實(shí)驗(yàn)測(cè)試方法及分析過程 ....................................................23
2.3.1  氣體濃度的測(cè)定方法 ......................................................23
2.3.2  氣液體積傳質(zhì)系數(shù)的測(cè)定 ..................................................24
2.3.3  氣含率的測(cè)定及公式推導(dǎo)...................................................25
2.6.3  相界面積的計(jì)算...........................................................27
第三章 空氣－水體系中氧氣傳質(zhì)系數(shù)的研究.........................................29
3.1   引 言.....................................................................29
3.2   氣體濃度隨時(shí)間的變化曲線 .................................................29
3.3   實(shí)驗(yàn)結(jié)果與討論 ...........................................................30
3.3.1  系統(tǒng)壓力的影響...........................................................30
3.3.2  溫度的影響...............................................................30
3.3.3  表觀氣速的影響 ..........................................................31
3.3.4  固含量的影響.............................................................31
3.3.5  塔徑的影響...............................................................32
3.4   傳質(zhì)系數(shù)的關(guān)聯(lián)式..........................................................33
3.5   小  結(jié)....................................................................34
第四章 有機(jī)體系傳質(zhì)特性的研究 ..................................................35
4.1   引  言 ...................................................................35
4.2   氣體濃度的測(cè)定............................................................35
4.2.1 氣體濃度隨時(shí)間變化的規(guī)律 .................................................35
4.3   結(jié)果與討論 ...............................................................36
4.3.1 操作條件對(duì)的影響 .........................................................36
4.3.1.1   壓力對(duì)傳質(zhì)系數(shù)的影響..................................................36
4.3.1.2   溫度對(duì)傳質(zhì)系數(shù)的影響 .................................................37
4.3.1.3   表觀氣速對(duì)傳質(zhì)系數(shù)的影響 .............................................38
4.3.1.4   固含率對(duì)傳質(zhì)系數(shù)的影響 ...............................................39
4.3.2 體積傳質(zhì)系數(shù)的關(guān)聯(lián)式......................................................39
4.3.3 氣液相界面積和氣液傳質(zhì)分系數(shù)的研究........................................40
4.3.3.1   壓力的影響 ...........................................................40
4.3.3.2   溫度的影響 ...........................................................41
4.3.3.3   表觀氣速的影響 .......................................................42
4.3.3.4   固含率的影響 .........................................................43
4.4   小  結(jié) ...................................................................43
第五章 結(jié) 論....................................................................45
參考文獻(xiàn)........................................................................46
附  錄..........................................................................52
致  謝..........................................................................54

摘 要
漿態(tài)鼓泡床反應(yīng)器具有結(jié)構(gòu)簡(jiǎn)單、傳熱、傳質(zhì)性能好以及溫度易控制等優(yōu)點(diǎn)，在化工生產(chǎn)中，例如F-T合成、液相合成甲醇、合成二甲醚等一些強(qiáng)放熱的多相反應(yīng)體系中有著廣泛的應(yīng)用。因此，漿態(tài)鼓泡床被認(rèn)為是最具發(fā)展前景的多相反應(yīng)器之一，對(duì)它進(jìn)行詳細(xì)的研究具有巨大的現(xiàn)實(shí)意義和潛在的應(yīng)用價(jià)值。
傳質(zhì)特性是反應(yīng)器設(shè)計(jì)和放大的重要參數(shù)之一，也是當(dāng)今反應(yīng)器研究的熱點(diǎn)和難點(diǎn)。在大多數(shù)情況下，傳質(zhì)過程是整個(gè)反應(yīng)過程的控制步驟，它直接影響著反應(yīng)速率的快慢以及產(chǎn)物分布等。因此，對(duì)三相漿態(tài)反應(yīng)器傳質(zhì)特性進(jìn)行研究有利于了解反應(yīng)器內(nèi)的傳質(zhì)特征，使我們能夠更好地利用漿態(tài)床反應(yīng)器。
本文針對(duì)工業(yè)上對(duì)二甲苯氧化反應(yīng)器的特點(diǎn)，建立了高溫高壓的漿態(tài)鼓泡床反應(yīng)器實(shí)驗(yàn)裝置，對(duì)氣體在水體系和液體石蠟體系中傳質(zhì)特性進(jìn)行了研究。實(shí)驗(yàn)采用動(dòng)態(tài)氣體吸收法測(cè)定了體系的體積傳質(zhì)系數(shù)，著重考察了溫度（T）、 壓力（P）、表觀氣速（）、固含率（）以及塔徑（）等對(duì)液相體積傳質(zhì)系數(shù)（）的影響；同時(shí)，對(duì)于有機(jī)體系實(shí)驗(yàn)還利用床層塌落法測(cè)定了反應(yīng)器內(nèi)氣泡含率（大、小氣泡分率）和氣泡上升速度，由此根據(jù)氣泡上升速度與氣泡直徑的關(guān)聯(lián)式，求取相界面積（）和液相傳質(zhì)分系數(shù)（），進(jìn)而考察了操作條件對(duì)相界面積和液相傳質(zhì)分系數(shù)的影響，實(shí)驗(yàn)結(jié)論如下：
在溫度（293K~473K）, 壓力（1.0MPa~3.0MPa）,表觀氣速（0.03m/s~0.1m/s），固含率（0%(w)~20%(w)）的實(shí)驗(yàn)條件下，液相體積傳質(zhì)系數(shù)隨著溫度、壓力、表觀氣速的增加而增大；隨著固含率的增加而減小。對(duì)于不同直徑的反應(yīng)器來(lái)說，大塔中的傳質(zhì)系數(shù)略高于小塔中的傳質(zhì)系數(shù)。
在有機(jī)體系中，相界面積受壓力、表觀氣速、固含率的影響較大，而受溫度的影響較��；而傳質(zhì)分系數(shù)受溫度、固含率的影響較大，受表觀氣速和壓力影響較小。
在實(shí)驗(yàn)范圍內(nèi)得出氣體（,,,）在兩種體系(水、液體石蠟)中傳質(zhì)系數(shù)的計(jì)算關(guān)聯(lián)式。
對(duì)于水-空氣-石英砂體系：

對(duì)于氣體-液體石蠟-石英砂體系：

實(shí)驗(yàn)從流體力學(xué)的角度定性地解釋了氣液傳質(zhì)的變化規(guī)律，有利于更加深入地認(rèn)識(shí)傳質(zhì)特性。本實(shí)驗(yàn)結(jié)果可為漿態(tài)床鼓泡反應(yīng)器的設(shè)計(jì)和放大提供一些基礎(chǔ)實(shí)驗(yàn)數(shù)據(jù)。

關(guān)鍵詞    漿態(tài)鼓泡床，傳質(zhì)特性，氣液傳質(zhì)系數(shù), 液相傳質(zhì)分系數(shù)，相界面積
MASS TRANSFER CHARACTERISTICS OF GAS－LIQUID IN A SLURRY BUBBLE COLUMN REACTOR UNDER HIGH TEMPERATURE AND HIGH PRESSURE

ABSTRACT

Slurry Bubble Column Reactor（SBCR）has been widely used in petrochemical, metallurgical, environmental, such as Fischer-Tropsch synthesis, LPMeOH, LPDME and so on. It offers many advantages over other multiphase reactors — simple construction, no mechanically moving parts, good mass transfer properties, high thermal stability, low energy supply and hence low construction and operation costs understood. So SBCR has become one of the most promising multiphase reactors. It has enormous significance and potential application value to study mass transfer of bubble column.
Mass transfer characteristics affect reaction rates and product distribution for chemical processes. Thus, they play an important role in designing and scaling-up the slurry bubble column reactors.
According to the characteristic of p-xylene oxidation reactor, A slurry bubble column reactor operating with water and organic liquid under high temperature and high pressure was set up. The effects of temperature, pressure, superficial gas velocity, solid concentration and diameter of reactors on the volumetric mass transfer coefficients using dynamic method are studied systematically. Moreover, the gas holdup and bubble rise velocities are measured using dynamic gas disengagement technique, which is used to calculate and estimate the Sauter mean bubble diameter and the gas-liquid interfacial area. Experimental study has resulted in the following conclusions:
Gas-liquid volumetric mass transfer coefficients increase with the increase of system pressure, temperature and superficial gas velocity, and decrease with the increase of solid concentration under the ranges of temperature (293K~473K), pressure (1.0Mpa~3.0Mpa), gas velocity (0.03m/s~0.1m/s) and solid concentration (0%(w)~20%(w)). For different reactors,  values in bigger reactor are slightly larger than those in smaller one.
 values are much more affected by pressure, superficial gas velocity and solid concentration, but less by temperature. However,  values are much more affected by temperature, solid concentration, but less by pressure and superficial gas velocity.
Based on analysis of the experimental data, two experiential correlations for predicting  values of gas in different liquids are obtained.
For Air-water- arenaceous quartz system:

For gas- paraffin- arenaceous quartz system:

In this paper, mass transfer characteristics are illustrated on the disciplinarian of hydrodynamics, which makes us understand mass transfer deeply in mass transfer behaviors of SBCR under high temperature and high pressure. The results of the experiment can provide some basic data to the design and scale-up of SBCR.

KEY WORDS: mass transfer coefficient, slurry bubble column reactor, gas-liquid mass transfer, gas-liquid mass transfer coefficient, gas-liquid interfacial area